Article

Mercury in different environmental compartments of the Pra River Basin, Ghana

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

Artisanal gold mining (AGM) with metallic mercury has a long history in Ghana. It is believed to be over 2,000 years old. Today, AGM has escalated in a new dimension consuming about half of the country where gold lode deposits exist along riverbanks or rivers are alluvial-gold rich. The Pra River in southwestern Ghana is a site of on going application of metallic mercury in prospecting gold, and this paper examines mercury (Hg) contamination in the different environmental compartments in its watershed. Samples of water, sediment, soil and biota (i.e., human hair and fish) were collected from locations along the course of the river during the rainy and dry seasons of 2002 and 2003, respectively. Besides the obvious Hg point sources along the Pra and its tributaries, the obtained results show that Hg levels and speciation in the studied aquatic system are controlled by precipitation, which drives the hydrology and differences in flow regimes versus seasons. The seasonal difference in Hg speciation suggests that methyl mercury (MeHg) found in the aqueous phase and riverine sediments is likely of terrestrial origin where its production is favored during the rainy season by high soil water and organic matter content. The use of the enrichment factor (EF) for the assessment of sediment quality indicated moderate to severe contamination of surface sediments in the rainy season, while in the dry season, the EF index indicates nearly no pollution of surface sediments. Accordingly, most of the Hg introduced into this river system is likely transported to depositional downstream terminal basins (e.g. the river delta and the Gulf of Guinea). With regard to biota, Hg measured in hair in the dry period was higher than data obtained on samples collected during the wet period. This could be explained at least in part by the shift in diet as a result of abundance of fish in the local markets and the concurrent increase and more active fishing during the dry season. Mercury data obtained on a very limited number of fish samples collected during the dry period only are also presented.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... In May 1989, the use of Hg in small-scale gold mining was legalized in Ghana (Provisional National Defence Council Law 218). This has increased these mining activities, which nowadays provides employment to over one million people (Donkor et al., 2006). The greater part of gold production (about 81%) in Ghana comes from goldfields in its southwestern region (Fig.1), an area of about 40,000 km 2 which is drained by three main rivers: Tano, Ankobra, and Pra (Donkor et al., 2006). ...
... This has increased these mining activities, which nowadays provides employment to over one million people (Donkor et al., 2006). The greater part of gold production (about 81%) in Ghana comes from goldfields in its southwestern region (Fig.1), an area of about 40,000 km 2 which is drained by three main rivers: Tano, Ankobra, and Pra (Donkor et al., 2006). ...
... Current data available in West Africa are mostly focused on Hg and As (Amonoo-Niezer et al., 1996;Bannerman et al., 2003;Donkor et al., 2006;Asante and Ntow, 2009;Rajaee et al., 2015;Adjei-Kyereme et al., 2015). Donkor et al. (2005) measured Hg, Al, Fe, As, Pb, Cu, Cr, Ni, Mn, Co, V, and Zn in sediments sampled along the course of the Pra River. ...
Article
This study aimed at assessing trace element concentrations in two representative estuaries of Ghana (Pra and Ankobra) affected by gold-mining, relative to the levels of the unaffected Volta estuary. Surficial sediments (n = 16–17) were sampled at each estuary and analysed by ICP-MS for 25 elements after pseudo-total digestion. The enrichment and geoaccumulation indexes revealed a moderate to significant contamination of As, Ag and Cu in the Pra and Ankobra estuaries. Spatial maps of concentrations revealed non-localized sources. High As concentrations were attributable to runoff transport and sedimentation of gold mining-tailing particles, as suggested by results from granulometric distributions, correlation and PCA analysis. The probabilities of surpassing the probable effects level (PEL) were 77% for As, 50% for Cr and 27% for Ni in Ankobra; these values were of 13%, 23% and 10% for the Pra. Results reveal potential future implications on ecosystems and human health in these both estuaries as result of the gold-mining activity.
... Mercury has been touted as one of the priority toxic elements of global concern (Donkor et al. 2006). Mercury species can be organic or inorganic with the organic mercury species being more toxic (Saturday, 2108). ...
... MeHg is a potent neurotoxin, damages the central nervous system and especially toxic to fetus. It is very soluble in lipids and, therefore, crosses biological membranes with ease (Donkor et al. 2006). ...
... Over the years, there has not been keen interest on mercury contamination due to the artisanal gold mining activities, thus there is virtually no data on the fate of mercury in the Pra Estuary environment to ascertain the level or extent of pollution (Donkor et al. 2006). Available literature does not include any studies on bioaccumulation in the West African Oyster species in the Pra Estuary. ...
... Bounded on the East and West by the Pra and Tano river basins respectively, it flows about 190 km from Sefwi Wiawso in the Western Region of Ghana into the Gulf of Guinea in the south. The geology of the southwestern Ghana, in which Ankobra flows, is characterized by the Birimian and Tarkwaian groups with placer gold deposits (Kesse 1985;Dzigbodi-Adjimah and Bansah 1995;Donkor et al. 2006). Thus, located in the catchment of Ankobra and its neighboring river basins are major mining towns such as Nsuta, Tarkwa, Damang, Abosso, Bogoso, and Prestea. ...
... About 81% of Ghana's gold output comes from goldfields in this area (Addy 1998). Also, according to Adimado and Baah (2002) as indicated by Donkor et al. (2006), artisanal gold mining which is common in this area contributes about 10% of Ghana's gold output. Other economic activities in the area include the cultivation of rubber and cocoa. ...
... Recorded mercury levels in this study are comparable to those reported by other researchers in Ghana (Asante et al. 2007;Donkor et al. 2006). Apart from P. notialis harvested from Densu and Ankobra rivers, and the species in which mercury was not detected, the current data indicated that mercury levels in all the samples were far above the permissible limit established by Commission Regulation-EC (2006) for fishery products, muscle meat of fish, and crustaceans (0.5 mg kg −1 ). ...
Article
Full-text available
Crustaceans, mollusks, and fish are wetland resources that constitute an important source of protein and foreign exchange for the Ghanaian population, and many species of these are sold in the open market and restaurants, yet studies on their heavy metal contents are generally scarce. This paper evaluates the levels of mercury in five species of crustaceans, two species of mollusks, and ten species of fish inhabiting three river basins with different catchment activities in Ghana. These include the Ankobra Basin, characterized with mining and agriculture, Densu Basin, associated with urban waste discharges and agriculture, and Lower Volta River Basin, associated with agricultural activities. Mercury concentration was highest in Ankobra (2.5 ± 2.59 μg g(-1)) followed by Densu (1.75 ± 1.35 μg g(-1)) and Volta (0.74 ± 1.46 μg g(-1)). The mercury load of the organisms range from <0.1 to 4 μg g(-1) with the highest load in Cynoglossus senegalensis at Ankobra. Except for Panaeus notialis from Densu and Ankobra, and three other species from Ankobra (Tympanotonus fuscatus, Cardisoma armatum, Callinectes amnicola) in which mercury was not detected, mercury loads of all the organisms were above the permissible limit of 0.5 mg kg(-1) established by Commission Regulation-EC (2006) for fishery products and muscle meat of fish. Weekly quantities of crustaceans and mollusks considered safe for consumption by adults ranged from 88 and 1000 g while that of the fishes were between 70 and 700 g (on a dry weight basis) depending on the species. It was clear that some caution needs to be exercised in the consumption of Ghana's fresh and brackish water fisheries.
... For soils, all sites exceed the USEPA THg soil standard of 0.1 µg/g, with some sites exceeding this value by up to two orders of magnitude [USEPA, 1985]. Maximum soil THg concentrations at Senegalese ASGM sites were greater than those observed at all ASGM sites except one site in Venezuela [ ., 2011], though median soil THg concentrations at our sites were comparable to reported values in the literature ( Table 1) [e.g., Donkor et al., 2006;Feng et al., 2006;Loredo et al., 2009;Santos-Francés et al., 2011]. To our knowledge, only two other studies have examined soil MeHg concentrations at ASGM sites; our values were within the range reported in Ghana [Donkor et al., 2006], while our maximum soil MeHg concentrations exceeded those reported in China [Feng et al., 2006]. ...
... Maximum soil THg concentrations at Senegalese ASGM sites were greater than those observed at all ASGM sites except one site in Venezuela [ ., 2011], though median soil THg concentrations at our sites were comparable to reported values in the literature ( Table 1) [e.g., Donkor et al., 2006;Feng et al., 2006;Loredo et al., 2009;Santos-Francés et al., 2011]. To our knowledge, only two other studies have examined soil MeHg concentrations at ASGM sites; our values were within the range reported in Ghana [Donkor et al., 2006], while our maximum soil MeHg concentrations exceeded those reported in China [Feng et al., 2006]. Sediment THg and MeHg concentrations at Senegalese ASGM sites were comparable to median and mean values reported in previous ASGM studies, though the maximum values we report in Kolya are lower than some of the maximum values in the literature [e.g., Donkor et al., 2006;Santos-Francés et al., 2011;Nyanza et al., 2014;Marrugo-Negrete et al., 2015]. ...
... To our knowledge, only two other studies have examined soil MeHg concentrations at ASGM sites; our values were within the range reported in Ghana [Donkor et al., 2006], while our maximum soil MeHg concentrations exceeded those reported in China [Feng et al., 2006]. Sediment THg and MeHg concentrations at Senegalese ASGM sites were comparable to median and mean values reported in previous ASGM studies, though the maximum values we report in Kolya are lower than some of the maximum values in the literature [e.g., Donkor et al., 2006;Santos-Francés et al., 2011;Nyanza et al., 2014;Marrugo-Negrete et al., 2015]. For river water, all four ASGM sites exceed the USEPA THg standard of 12 ng/L for the protection against toxic levels of bioaccumulation in aquatic organisms, including fish consumed by humans [USEPA, 1985]. ...
Article
Full-text available
The largest source of global mercury (Hg) anthropogenic inputs to the environment is derived from artisanal and small-scale gold mining (ASGM) activities in developing countries. While our understanding of global Hg emissions from ASGM is growing, there is limited empirical documentation about the levels of total mercury (THg) and methylmercury (MeHg) contamination near ASGM sites. We measured THg and MeHg concentrations in soil (n = 119), sediment (n = 22), and water (n = 25) from four active ASGM villages and one non-ASGM reference village in Senegal, West Africa. Nearly all samples had THg and MeHg concentrations that exceeded the reference village concentrations and USEPA regulatory standards. The highest median THg concentrations were found in huts where mercury-gold amalgams were burned (7.5 μg/g), while the highest median MeHg concentrations and percent Hg as MeHg were found in river sediments (4.2 ng/g, 0.41%). Median river water concentrations of THg and MeHg were also elevated compared to values at the reference site (22 ng THg/L, 0.037 ng MeHg/L in ASGM sites). This study provides direct evidence that Hg from ASGM is entering both the terrestrial and aquatic ecosystems where it is converted in soils, sediment, and water to the neurotoxic and bioavailable form of MeHg.
... Common name MeHg (µg g -1 ) EDIm * HQ * Crmw * EDIm ** HQ ** Crmw * Donkor et al., (2006) All values were reported to two significant figures. a average±SD; b median concentration; *unfiltered water; **filtered water; + concentration in ng/mL; ++ concentration in ng/g; ww = fresh weight. ...
... 13.01 ± 13.73 ng L -1 ) are lower than those typically found in lotic aquatic systems in the Northwest of Colombia, such as in San Martín de Loba (17-39 µg L -1 ) (Olivero-Verbel et al., 2015) and the Achí swamps Bolívar (160-460 ng L -1 ) (Marrugo-Negrete et al., 2008a). It is also lower when compared with other countries such as the ASGMs and rivers of Suriname (Gray et al., 2002), Pra river basin, Ghana (Donkor et al., 2006) and Cikaniki river, Bogor, Indonesia (Tomiyasu et al., 2017). However, they were higher than the reported concentrations from other regions, such as the West Wits Gold Mine, Johannesburg, South Africa (Lusilao-Makiese et al., 2016) and Rio Madeira basin, Brasil (Vieira et al., 2018). ...
... However, it is emphasized that the MeHg/THg ratio of 6.5 (avg.) and the maximum of 11% in the sediments was higher than the typically reported proportions in uncontaminated aquatic sediments (0.1-1.5%) (Ullrich et al., 2001;Issaro et al., 2009) and those observed in all the aquatic systems reported in this study [except in the Pra river basin -Ghana (max. 68%)] (Donkor et al., 2006). This is a clear evidence of the excessive ability of these ecosystems to methylate mercury. ...
Article
Total mercury (THg), methylmercury (MeHg) in water, sediments, macrophytes, fish and human health risks were analyzed and assessed from abandoned gold mining ponds (AGMPs)/ mining areas in Western Colombia to know its present environmental condition. Concentrations of THg in water (avg. 13.0 ± 13.73 ng L-1) was above the EPA threshold level (12 ng L-1), suggesting possible chronic effects. Sediment sample revealed that the ponds are methylated (%MeHg: 3.3–11%). Macrophyte Eleocharis elegans presented higher THg content in the underground biomass (0.16 ± 0.13 ìg g-1 dw) than in the aerial biomass (0.05 ± 0.04 ìg g-1 dw) indicating accumulation of THg. MeHg was the most abundant chemical species in fish (MeHg/THg: 83.2–95.0%), signifying higher bioavailability and its risk towards human health. Fish samples (15%) indicate that THg were above WHO limit (0.5 ìg g), particularly in Ctenolucius beani, Hoplias malabaricus) and lowest in Sternopygus aequilabiatus and Geophagus pellegrini. Bioaccumulation and biomagnification of MeHg were higher in the carnivores representing a source of exposure and potential threat to human health. Fulton’s condition factor (K) for bioaccumulation indicate a decrease with increasing trophic level of fishes. Overall results suggest, mercury species found in different AGMPs compartments should be monitored in this region.
... In these activities, Hg is released by lixiviation and erosion of natural soil particles (Gerson et al., 2018;Telmer et al., 2006). Higher inputs of particulate material enriched in Hg (Donkor et al., 2006;Gerson et al., 2018;Guimaraes et al., 1999;Marrugo-Negrete et al., 2008a,b;Marrugo-Negrete et al., 2015;Pinedo-Hern andez et al., 2015) increase the bioavailability of this element to the biota (Donkor et al., 2006;Malm et al., 1995a;Marrugo-Negrete et al., 2008a,b;Marrugo-Negrette et al., 2018). ...
... In these activities, Hg is released by lixiviation and erosion of natural soil particles (Gerson et al., 2018;Telmer et al., 2006). Higher inputs of particulate material enriched in Hg (Donkor et al., 2006;Gerson et al., 2018;Guimaraes et al., 1999;Marrugo-Negrete et al., 2008a,b;Marrugo-Negrete et al., 2015;Pinedo-Hern andez et al., 2015) increase the bioavailability of this element to the biota (Donkor et al., 2006;Malm et al., 1995a;Marrugo-Negrete et al., 2008a,b;Marrugo-Negrette et al., 2018). ...
... Compared to other gold mining sites worldwide, often the observed THg levels in water and sediment of the Tapaj os Basin are measured in lower orders of magnitude. Examples are studies done in Colombia (Marrugo-Negrete et al., 2008a,b), Ghana (Donkor et al., 2006), Indonesia (Limbong et al., 2005), China (Feng et al., 2006) and Tanzania (Chibunda et al., 2008). It is important to note that the majority of the studies evaluating the impact of gold mining occurs in small river basins, with tens to few thousands of square kilometers, while the basins studied here are tens of thousands of square kilometers. ...
Article
Mercury (Hg) is known as one of the major contaminants in the Amazon. The Tapajós River basin, in the Brazilian Amazon, has diverse anthropogenic activities which increase Hg concentrations in the aquatic ecosystem. Moreover, high concentrations of Hg are naturally found in this basin. Distribution of total (THg) and methyl (MeHg) mercury were assessed in unfiltered water (n = 47), suspended particulate matter (SPM, n = 30), superficial sediment (BS, n = 29), plankton (n = 28) and fishes (n = 129) from the Tapajós River basin. Suspended particles were the main carrier of Hg in the water column and sediment. Increased erosion, prompted by anthropic activities, led to higher Hg concentrations in water from the most impacted areas. Hg is transported mainly in particulate matter; thus, anthropic disturbances influence Hg concentrations downstream. Limnological parameters such as organic matter content influenced MeHg concentrations in water, plankton and sediment of the Tapajós basin. Hg methylation in total plankton was more efficient in lakes (13-66%) than in Tapajós River main channel (2-14%). Biotic and abiotic factors interact in a complex way in the aquatic ecosystem, making Hg concentrations to vary in food web. Gold mining and deforestation probably increase Hg levels in the Tapajós basin. Thus, in addition to Hg monitoring, prevention and remediation efforts should be focused on soil and sediment erosion control.
... In Ghana, Equatorial Africa, the Volta Estuary is affected by the anthropogenic fingerprint of the Ada Foah city and by upstream damming, while the Ankobra and Pra estuaries are affected by artisanal gold-mining activities (Donkor et al., 2006;Klubi et al., 2018). The use of Hg for amalgam in small-scale gold mining was legalized in Ghana in 1989, leading to an increase in these activities which nowadays provides employment to over one million people and makes Ghana to account for half of the total gold production in the region. ...
... Mercury pollution is then a major threat for environmental and human health. Other major impacts are land degradation and the huge amount of terrigenous inputs injected into the water courses, with mining tailings carrying high concentrations of As, Cr, Zn, Cu and Pb, among other potentially harmful elements (Donkor et al., 2006;Fashola et al., 2016). Thus, Klubi et al. (2018), in their study of these three estuaries, found a moderate to significant contamination of As, Ag and Cu in sediments from the Pra and Ankobra estuaries. ...
Article
This paper reports concentrations of γ-emitter radionuclides (⁴⁰K, ¹³⁷Cs, ²¹⁰Pb, ²²⁶Ra, ²²⁸Ra, ²²⁸Th and ²³⁴Th) and some metals (Al, Cr, Fe, Co, Ni, Cu, Zn, As, Sr, Cd, Sb, Cs, Pb, Th and U) in surficial sediments from the Ankobra, Pra and Volta estuaries, in Ghana. Artisanal gold-mining in the Ankobra and Pra basins promoted moderate enrichments of As, Sb, Cu, Cs and Cr in their estuarine sediments, with respect to the reference background of the Volta Estuary. Radionuclide concentrations were in the range found in the Earth's crust. Present data do not support any conclusion on their potential enrichments due to gold-mining activities. Radionuclide isotopic ratios revealed a transfer of ²²⁸Ra from sediments to the water column. Pearson correlation coefficient matrices showed different patterns, which were reasonably understood after novel approaches: i) inter-estuaries comparison of slopes in the linear regressions of element-concentrations vs Al, Fe and Cs; ii) study of Al-normalized concentrations of elements; iii) excess ²¹⁰Pb informing on local sedimentary conditions. The metal enrichments observed in the Ankobra and Pra estuaries are associated with the Fe-rich compounds in sulphide ores (such as FeAsS) transported along the river course and deposited in the estuary.
... In contaminated waters, such as industrial wastewaters or water bodies near gold mines, Hg levels can reach the mg L À1 range (Huber and Leopold, 2016). Inadequate analytical techniques to measure low Hg concentration (Gworek et al., 2016), complexity of matrix (Kramer et al., 1998;Lamborg et al., 2012), mercury's high volatility (Kramer et al., 1998;Donkor et al., 2006), losses or contamination of the samples during handling (Donkor et al., 2006), storage and pretreatment of samples (Parker and Bloom, 2005;Hammerschmidt et al., 2011) may generate erroneous data. ...
... In contaminated waters, such as industrial wastewaters or water bodies near gold mines, Hg levels can reach the mg L À1 range (Huber and Leopold, 2016). Inadequate analytical techniques to measure low Hg concentration (Gworek et al., 2016), complexity of matrix (Kramer et al., 1998;Lamborg et al., 2012), mercury's high volatility (Kramer et al., 1998;Donkor et al., 2006), losses or contamination of the samples during handling (Donkor et al., 2006), storage and pretreatment of samples (Parker and Bloom, 2005;Hammerschmidt et al., 2011) may generate erroneous data. ...
Article
Reliable determination of mercury (Hg) in natural waters is a major analytical challenge due to its low concentration and to the risk of Hg losses or contamination during sampling, storage and pre-treatment of samples. The present work proposes a simple, efficient, sensitive and easy-handling methodology for extraction, pre-concentration and quantification of total dissolved mercury in natural waters, using iron oxide nanoparticles (NPs) coated with silica shells functionalized with dithiocarbamate groups (Fe3O4@SiO2SiDTC). Ten mg L⁻¹ of these NPs were sufficient to remove 83–97% of 500 to 10 ng L⁻¹ of Hg in ultra-pure water and artificial seawater, used as model Hg solutions, within 24 h. Mercury sorbed to the NPs was then measured directly by thermal decomposition atomic absorption spectrometry with gold amalgamation. The detection limit of approximately 1.8 ng L⁻¹ is lower than the values reported in dispersive solid phase extraction for other magnetic sorbents. As a proof-of-concept, the proposed methodology was successfully tested in real samples of fresh and saline waters and more than 91% of Hg was recovered. With this methodology the extraction and pre-concentration steps may be carried out in situ decreasing the risk of Hg losses or contamination during sampling, storage and pre-treatment of water samples.
... Although mining activities have ceased, high Hg levels are still detected due to land-use changes like deforestation and the construction of hydroelectric dams, which lead to Hg remobilization Vieira et al. 2018). ASGM has indeed been considered to be the most significant source of Hg emissions worldwide (Donkor et al. 2006;Gammons et al. 2006;Gerson et al. 2018;Marrugo-Negrete et al. 2019;UNEP 2013). ...
... Several other studies in other countries have demonstrated a correlation between gold mining activities, environmental contamination of Hg, and the human exposure through consumption of local fish, e.g., Ghana (Donkor et al. 2006), Peru (Gammons et al. 2006), Senegal (Gerson et al. 2018), and Colombia (Marrugo-Negrete et al. 2019). Subsequently, this does not merely deserve attention in the Amazon as evaluated in the present study, but also in other areas with (historical) gold mining activities. ...
Article
Full-text available
Increasing concerns have been raised about the toxicity of mercury (Hg) to humans, especially for those that consume a great amount of fish. High Hg concentrations have previously been measured in Amazonian waterbodies, both resulting from natural and anthropogenic sources. However, few studies have been conducted so far in Amazonian lakes that are fished by local populations. In addition, few of those studies included methylmercury (MeHg), the most toxic and bioaccumulative Hg form, and evaluated the influence of physico-chemical conditions and season on Hg dynamics. In the present study, total Hg (THg) and MeHg concentrations were measured in bottom sediment as well as in two fish and two crocodile species of the Amazonian Cuniã Lake. Bottom sediment MeHg concentrations were higher in the dry season than in the wet season, which is related to differences in physico-chemical (pH and electrical conductivity) conditions. Diet appeared to be related with animal tissue MeHg concentrations, with the herbivorous fish having lower MeHg levels than the predatory fish and crocodiles. Based on the measured tissue concentrations and published data on local person weight and fish consumption, MeHg risk to Cuniã Lake populations was estimated. Although the MeHg fish tissue concentrations did not exceed national and international standards, a significant risk to the local population is anticipated due to their high fish consumption rates. Graphical abstract
... As described in these studies, the soil surface receives mercury from the air and serves as the field of contact between mercury and the plants and animals in the respective area. On the other hand, there are few reports on the detailed vertical variation in mercury and soil chemistry, and the reports on MeHg concentration in soil around ASGM sites are still limited [12][13][14]. The soil surface is a dynamic field where material supply and degradation proceed, and vertical variation in mercury species may provide important information for tracking the effects of such variation. ...
... There are only a few reports about the MeHg concentration in the soil around ASGM sites. Among the reports, the highest concentration value of MeHg, < 1-162 μg kg −1 , with a median of 13 μg kg −1 (28 ± 19% of T-Hg), was reported for an ASGM in Ghana in the wet season [13]. The concentration values of 0.40-16 μg kg −1 , with a median of 5.0 μg kg −1 (0.14 ± 0.16% of T-Hg), were reported for ASGM sites in China [14], and 0.052-48 μg kg −1 , with a median of 0.78 μg kg −1 , were reported for ASGM sites in Senegal [12]. ...
Article
Full-text available
This study was conducted to understand the environmental behavior of mercury released by artisanal and small-scale gold mining (ASGM) activities. For this purpose, we attempted to assess the effect of diffused mercury on mercury concentrations in soil, demonstrate the presence of methylmercury in soil affected by the deposited mercury and determine the reactions associated with methylmercury production. The vertical profiles of mercury were obtained from two sites in the forest of the ASGM village in Pongkor (West Java, Indonesia) and from two sites in Mount Halimun-Salak National Park, which is approximately 12 km from the ASGM village. The highest total mercury concentration, 8.9 mg kg−1, was observed for soil samples collected at the ASGM village. The mercury was concentrated at the surface or in the subsurface layers, and the concentrations were several times to more than ten times higher than the lowest values observed in the deeper layers at each site. Even in the national park, the highest concentration of 1.9 mg kg−1 was observed in the upper soil layer. These results suggest that the primary source of mercury in the forest soil is atmospheric deposition; fallen plant leaves also deliver accumulated mercury to the soil surface. The organic mercury percentages of the total mercury were 0.2 ± 0.1% for the national park and 0.3 ± 0.2% for ASGM sites. The vertical variation in organic mercury concentration did not always match that in total mercury concentration, which suggested that the formation of methylmercury in soil was closely related to the decomposition of organic matter near the surface. The soil surface is an important reaction field for methylmercury production in forested areas.
... The concentrations below detection limit were rather due to high detection limits of the analysis than the absence of these metals in the seawater, because of the challenges associated with measuring ions in a seawater matrix. Particularly, our detection limit for Hg was too high to evaluate the possible contamination, as the concentrations measured in contaminated water from the Pra River basin of Ghana were typically orders of magnitude below our detection limit (Donkor et al., 2006). Preconcentration of seawater samples might have provided detectable concentrations of some elements but as it is a tedious method prone to contamination, it was not employed in this study. ...
Article
Metal contamination is a threat for marine ecosystems from an environmental, economic and public health perspective, particularly in regions where local communities rely on marine resources such as the Gulf of Guinea. Plankton are the point of entry for metals in the marine food web, potentially contaminating seafood. We investigated the bioaccumulation of 12 metals in three size classes of plankton from the coast of Ghana. Metal concentrations were high in the micro- and mesoplankton, in particular for Mn, Mo and Zn (up to 100 mg kg⁻¹) and Fe (>100 mg kg⁻¹). All metals significantly bioaccumulated (10³–10⁶ L kg⁻¹) and the bioaccumulation increased from the smallest to larger size fractions, suggesting a biomagnification. These metals included the highly toxic elements As, Cd and Pb. Our results highlight the need to monitor metal occurrence in the Gulf of Guinea, to reduce pollution and ensure food safety, in accordance with the UN SDG #14.
... In the last decades, few studies have been conducted on trace metals contamination in wetlands near gold mining activities in West Africa despite intensive mining in this region. Most of these studies were carried out in Ghana (Bortey-Sam et al., 2015a, 2015bDonkor et al., 2005Donkor et al., , 2006Gbogbo et al., 2016;Kwaansa-Ansah et al., 2010), Senegal (Niane et al., 2014(Niane et al., , 2015, Nigeria (Bartrem et al., 2014;Dooyema et al., 2012;Wasiu et al., 2017) and Burkina Faso (Ouedraogo and Amyot, 2013). These articles suggest in general that artisanal mining activities are a source of trace metals to wetlands, with negative consequences on human health. ...
Article
The distribution patterns and sources of arsenic and trace metals (Cd, Pb, Cu, Zn, Cr, Co, Fe, Al, Mn, and Ni) were investigated in wetland sediments that may be impacted by industrial and artisanal gold mining, along with those from non-mining areas in Divo (Bonikro and Agbaou sites) and Aboisso (Afema site) Departments, central-southern and southeastern Côte d'Ivoire, respectively. Ecological risks of sediments were examined using the potential ecological risk index (PERI) and sediment quality guidelines (SQGs). Sediments from mining activities showed significantly higher total As, Pb, Cr, Ni, Mn, Cu, and Al concentrations than the ones from non-mining areas at Afema and Agbaou. On the contrary, a reverse spatial trend was observed for Al, Cr, and As at Bonikro. Geoaccumulation index showed moderate to strong contamination in Cd whatever the sites and activity types, and a relatively low contamination in Pb, Cu, Zn, Cr, Co, Fe, Al, Ni, and Mn, confirmed by the enrichment factor. Extreme sediment contamination in As was observed in industrial mining areas at Afema. Artisanal mining was the main source of Mn and Ni, especially at Agbaou. On the contrary, Cd, Al, Pb, Co, Cu and Zn and Cr were mainly from lithogenic sources. Principal component and hierarchical cluster analyses showed that total organic carbon controls distributions of elements Ni and Cu at Afema, Cd and Cr at Agbaou, and Mn and Co at Bonikro. Based on PERI and SQGs, As could pose high risks to biota in industrial mining areas.
... In the last decades, few studies have been conducted on trace metals contamination in wetlands near gold mining activities in West Africa despite intensive mining in this region. Most of these studies were carried out in Ghana (Bortey-Sam et al., 2015a, 2015bDonkor et al., 2005Donkor et al., , 2006Gbogbo et al., 2016;Kwaansa-Ansah et al., 2010), Senegal (Niane et al., 2014(Niane et al., , 2015, Nigeria (Bartrem et al., 2014;Dooyema et al., 2012;Wasiu et al., 2017) and Burkina Faso (Ouedraogo and Amyot, 2013). These articles suggest in general that artisanal mining activities are a source of trace metals to wetlands, with negative consequences on human health. ...
Article
Full-text available
The distribution patterns and sources of arsenic and trace metals (Cd, Pb, Cu, Zn, Cr, Co, Fe, Al, Mn, and Ni) were investigated in wetland sediments that may be impacted by industrial and artisanal gold mining, along with those from non-mining areas in Divo (Bonikro and Agbaou sites) and Aboisso (Afema site) Departments, centralsouthern and south-eastern Côte d'Ivoire, respectively. Ecological risks of sediments were examined using the potential ecological risk index (PERI) and sediment quality guidelines (SQGs). Sediments from mining activities showed significantly higher total As, Pb, Cr, Ni, Mn, Cu, and Al concentrations than the ones from non-mining areas at Afema and Agbaou. On the contrary, a reverse spatial trend was observed for Al, Cr, and As at Bonikro. Geoaccumulation index showed moderate to strong contamination in Cd whatever the sites and activity types, and a relatively low contamination in Pb, Cu, Zn, Cr, Co, Fe, Al, Ni, and Mn, confirmed by the enrichment factor. Extreme sediment contamination in As was observed in industrial mining areas at Afema. Artisanal mining was the main source of Mn and Ni, especially at Agbaou. On the contrary, Cd, Al, Pb, Co, Cu and Zn and Cr were mainly from lithogenic sources. Principal component and hierarchical cluster analyses showed that total organic carbon controls distributions of elements Ni and Cu at Afema, Cd and Cr at Agbaou, and Mn and Co at Bonikro. Based on PERI and SQGs, As could pose high risks to biota in industrial mining areas.
... Moreover, grassland, human settlement, and other land cover types cover about 10% of the entire watershed. The area has a history of small-scale mining because of its world-class Birimain and Tarkwain rock formations [26,27]. Because of the gold mining activities, most of the settlement is referred to as mining towns. ...
Article
Full-text available
Ghana's economic development relies largely on the mining industry, but the ecological cost is very high, particularly for the small-scale sector. To ascertain and give an account of the ecological pressures from the small-scale gold mining sector, we quantified and appraised the ecosystems (land cover types) degradation due to mining land use along portions of the renowned Pra River basin of Ghana. The study classified and analysed high-quality Landsat image data (1986-2016) to monitor processes and changes in the river basin and adopted the Ecosystem Service Value (ESV) model to quantify the forgone value in monetary term. The results revealed that the initial ESV of 17.69 million US$ in 1986 increased to 18.40 million US$ in 2002 for the study landscape with the small-scale mining sector accounting for 8.4% of the trade-off costs. The expansion of forest areas and its higher value coefficient (VC) was, however, prevalent and this resulted in a net positive change during this period. However, in 2016, out of the total ESV of 14.63 million US$ obtained, the small-scale mining activities accounted for 36.8% of the trade-off costs. The substantial increase in trade-off costs with a subsequent decrease in ESV in the study landscape, following the intensification of small-scale gold mining, indicates that their activities have been degrading the watershed ecosystem and are, therefore, unsustainable. The study affirms the need for policymakers/government to review the laws, particularly on post-mining monitoring schemes to deter illegal miners and support the registered small-scale miners who are willing to implement land rehabilitation activities.
... Most of these occurred with catastrophic consequences (Akabzaa, 2000). Elevated concentrations of heavy metals in various media such as soils, streams (including sediments), food crops (e.g., cassava and plantain), fish (e.g., mudfish), plants (e.g., water ferns and elephant grass) and humans have been reported (see Bempah et al., 2013;Boateng et al., 2012;Antwi-Agyei et al., 2009;Amegbey and Eshun, 2003;Aryee et al., 2003;Hilson, 2006;Tschakert and Singh, 2007;Donkor et al., 2006;Essumang et al., 2007;Armah et al., 2012). ...
Article
Full-text available
To attract greater levels of foreign direct investment into their gold-mining sectors, many mineral-rich countries in sub-Saharan Africa have been willing to overlook serious instances of mining company non-compliance with environmental standards. These lapses in regulatory oversight and enforcement have led to high levels of pollution in many mining communities. The likelihood is high that the risk of pollution-related sicknesses will necessitate increasingly high healthcare expenditures in affected communities. In this study, we propose and estimate a hedonic-type model that relates healthcare expenditure to the degree of residents' exposure to mining pollution using data obtained on gold mining in Ghana. This has been confirmed by our empirical results, with an elasticity coefficient of 0.12. Furthermore, while healthcare expenditure does not vary between males and females, younger household heads spend more on their health than their older counterparts after controlling for health status, income and access to health insurance.
... In sub-Saharan African countries, environmental and health effects of Hg pollution have been reported from artisanal small-scale gold mining (Donkor et al. 2006;Ouédraogo and Amyot 2013). In Senegal, along the Gambia river impacted by the use of Hg in the gold amalgamation in small artisanal gold mining, total mercury (THg) concentrations in fish were below the European guideline of 0.5 mg kg −1 wet weight but 100 % of the mussels were above the safety limit (Niane et al. 2015). ...
Article
The presence of Cd, Pb, Hg, PAHs and PCBs was investigated in the edible flesh of six marine species of the Senegalese coastal waters. Samples were collected from five sites in 2013. Variations in pollutant concentrations were recorded both among species and among sites. The mussels (Perna perna) contained the highest concentrations of Cd (0.394 ± 0.634 mg kg⁻¹ ww) and Pb (0.185 ± 0.213 mg kg⁻¹ ww), the highest level of Hg was recorded in Tilapia (Sarotherodon melanotheron, 0.019 ± 0.014 mg kg⁻¹ ww), and sardines (Sardinella aurita) presented the highest level of PAHs (0.019 mg kg⁻¹ ww). While P. perna and S. aurita did not accumulate measurable PCBs, the concentrations of PCBs remained low in other species (between 0.001 and 0.008 mg kg⁻¹ ww). For most species, samples collected near human-impacted sites had the highest pollutant concentrations. For most species studied here, the pollutant concentrations were below the limits for human consumption defined by the European Union (EU). However, at the more polluted sites 50% of the mussels from Soumbedioune presented values above the EU limit for Cd (1 mg kg⁻¹ ww), and all sardines from Rufisque contained PAHs above the EU guideline value (0.03 mg kg⁻¹ ww). The target hazard quotients (THQ) for metals were <1 and thus did not indicate a danger to the local population. Calculations of the cancer risk (CR) indicated that for PAHs and for PCBi (PCB indicator), 90% of CR values were in excess carcinogenic risk. For dl-PCB, all CR values are well below the guideline value. We suggest that potential risk of human health exists when consuming high quantity of seafood originating from polluted areas.
... Individuals relying on these streams may be exposed to hazardous chemicals used in mining practices (e.g. mercury, arsenic) (Babut et al., 2003;Basu et al., 2011;Donkor et al., 2006), while BHs are readily available in their communities. High TDS concentrations are found on the eastern side of the Atiwa Mountain Range, with salinity likely caused by dissolution of minerals in the aquifers, rather than by saltwater intrusion (Yidana and Yidana, 2010). ...
Article
Rural Ghanaian communities continue using microbiologically contaminated surface water sources due in part to undesirable organoleptic characteristics of groundwater from boreholes. Our objective was to identify thresholds of physical and chemical parameters associated with consumer complaints related to groundwater. Water samples from 94 boreholes in the dry season and 68 boreholes in the rainy season were analyzed for 18 parameters. Interviews of consumers were conducted at each borehole regarding five commonly expressed water quality problems (salty taste, presence of particles, unfavorable scent, oily sheen formation on the water surface, and staining of starchy foods during cooking). Threshold levels of water quality parameters predictive of complaints were determined using the Youden index maximizing the sum of sensitivity and specificity. The probability of complaints at various parameter concentrations was estimated using logistic regression. Exceedances of WHO guidelines were detected for pH, turbidity, chloride, iron, and manganese. Concentrations of total dissolved solids (TDS) above 172 mg/L were associated with salty taste complaints. Although the WHO guideline is 1000 mg/L, even at half the guideline, the likelihood of salty taste complaint was 75%. Iron concentrations above 0.11, 0.14 and 0.43 mg/L (WHO guideline value 0.3 mg/L) were associated with complaints of unfavorable scent, oily sheen, and food staining, respectively. Iron and TDS concentrations exhibited strong spatial clustering associated with specific geological formations. Improved groundwater sources in rural African communities that technically meet WHO water quality guidelines may be underutilized in preference of unimproved sources for drinking and domestic uses, compromising human health and sustainability of improved water infrastructure.
... Heightened tension between gold mining firms and residents are due to repeated denial and/or down-playing of environmental health impacts of mining activities by companies and regulatory agencies (Akabzaa and Darimani 2001). In response to this situation, many studies in Ghana have explored biological and physiological mechanisms through which environmental exposures influence the health of residents in mining communities (see Adimado and Baah 2002;Akagi et al. 2000;Armah et al. 2012;Donkor et al. 2006;Hendryx and Ahern 2008;Kim and Kim 1996;Obiri et al. 2006;Wright et al. 2014). ...
Article
Full-text available
The emergence of the gold mining industry and the influx of artisanal and small-scale mining following recent discoveries of gold deposits in Northern Ghana have posed new socio-cultural, economic, environment and health challenges for residents in this dry savannah zone that is already facing negative consequences of environmental change. Yet, the extent to which residents in close proximity (impacted) and distant (affected) host communities perceive the impact of mining on their health has been nascent. Using cross sectional survey data (n=801) and applying the binary negative log-log technique, we examine residents' self-rated health in mining communities in the Upper West Region of Ghana. The findings suggest that residents in impacted communities who believed that odours from mining activities could have health impact were twice more likely to report their health as poor, while those who were uncertain were 98% more like to rate their health poor compared to those who disbelieved. However, sighting of dust was not significantly associated with subjective health in both impacted and affected communities. Based on these findings, it is recommended that Ghana's Minerals and Mining Act be reviewed to include the active involvement of host communities in mine leases while enforcing strict environmental best practices.
... PFOS in water samples from the Pra River was however significantly greater (at 90% confidence interval) than the levels in the Kakum River (p = 0.07). The Pra River was experiencing pollution from mine wastes, especially, effluents from illicit small-scale gold mining activities (Donkor et al., 2006). It is unclear if this has partly contributed to the elevated concentration PFOS in the Pra River. ...
Article
Perfluoroalkyl acids (PFAAs) are persistent environmental pollutants that have been detected in various media including human serum. Due to concerns regarding their bioaccumulation and possible negative health effects, an understanding of routes of human exposure is necessary. PFAAs are recalcitrant in many water treatment processes, making drinking water a potential source of human exposure. This study presents the first report on contamination from PFAAs in river and drinking water in Ghana. The targeted PFAAs were perfluoroalkyl carboxylic acids (PFCAs) with C4–14 carbon chain and perfluoroalkane sulphonic acids (PFSAs) with C6, 8, 10. Five PFAA congeners – PFOA, PFOS, PFHxA, PFDA and PFPeA – were commonly detected in river and tap water. The mean concentrations of ΣPFAAs in the Kakum and Pra Rivers were 281 and 398 ng/L, while tap water (supplied from the treatment of water from those rivers) contained concentrations of 197 and 200 ng/L, respectively. PFOA and PFOS constituted about 99% of the ΣPFAAs. The risk quotient (RQ) attributed to drinking of tap water was estimated at 1.01 and 1.74 for PFOA and PFOS, respectively. For a country that has not produced these compounds, the RQs were unexpectedly high, raising concerns particularly about contamination from such emerging pollutants in local water sources. The study revealed limitations of local tap water treatment in getting rid of these emerging pollutants.
... Hence, measurement of mercury in environmental samples is of great importance as a major tool to protect the environment from mercury released through anthropogenic activities as well as from natural sources. Mercury has a problem of being relatively volatile (Donkor et al. 2006) and, therefore, easily lost during sample preparation and analysis. Therefore the decomposition of organic and inorganic matrices is a critical stage in trace mercury determination since it largely determines the precision and accuracy of the results (Torres et al. 2012). ...
Article
Full-text available
Three analytical methods using automatic mercury analyzer (AMA), direct mercury analyzer (DMA) and inductively coupled plasma-mass spectrometry (ICP-MS) were applied to determine mercury in fish and sediment samples from the Volta Lake in Ghana with the aim of comparing their accuracy, precision, and limit of quantifications. There was statistically no significant difference (p < 0.05) between the concentrations recorded by the methods. This indicates their suitability for the accurate determination of mercury. Limit of quantification was found to be in the order; ICP-MS (0.053 ng/g) < DMA (0.527 ng/g) < AMA (2.193 ng/g). Though each of the three methods has a suitable ability in determining accurately the concentrations of mercury in fish and sediment, for the determination of very low concentrations of mercury ICP-MS should be preferred considering the order of the detection limit which follows the trend ICP-MS (0.016 ng/g) < DMA (0.158 ng/g) < AMA (0.509 ng/g).
... Mercury processing emits toxic vapours, with predicted global mercury emission by ASGM to be 727 tonnes: 35% of the total world anthropogenic emission of mercury (UNEP 2013). The toxicity of mercury derived from ASGM operations to people and, to a lesser extent, the environment, has been well studied (Bose-O'Reilly et al. 2010;Castilhos et al. 2006;Donkor et al. 2006). However, the impact of AGSM operations on the broader water quality of these river and streams has been largely overlooked. ...
Conference Paper
Full-text available
Rivers in Ghana provide environmental and economic services such as fishery and farming, and are also the main sources of clean drinking water. Artisanal small-scale gold mining (ASGM), a significant industry in Ghana, typically occurs near streams and rivers in order to obtain a source of water for processing and waste discharge. ASGM is subsistence mining carried out by individuals or small collectives using rudimentary technologies for both extraction and processing of ore. Using small quantities of mercury for gold extraction, ASGM also releases high quantities of sediment, (along with metals and other contaminants) into local water bodies, posing environmental and downstream human health risks. In Ahafo, Ghana, we undertook a detailed assessment of the effect of ASGM on the water quality of the Surow River over one year (January 2013 to April 2014). Physico-chemical properties of the water at 11 sites along the river (above and below ASGM sites) were measured monthly. Our research indicates that the impacts of ASGM extend beyond Hg contamination, with the main effects of ASGM on river systems being changes in water conductivity, sediment loads, and metals, as well as alteration of river morphology. Dewatering water was responsible for significant increases in conductivity. We did not detect mercury above drinking water standards, with the exception being at the headwaters, presumably from natural sources. In general, we found that sites with associated ASGM activities had water qualities that did not meet Ghanaian national standards for drinking water, with manganese at particularly high concentrations. We also saw temporal variability in water quality parameters, likely due to the combination of fluctuating ASGM activities and the natural seasonal hydrology of tropical river systems.
... Piles of excavated materials have been heaped along the river bank with trees felled into the river. The impact of small scale mining on aquatic ecosystem in other parts of Ghana is reported by Babut et al. (2003) and Donkor, Bonzongo, Nartey, and Adotey (2006a). ...
Article
Full-text available
Small scale mining continues to contribute significantly to the growth of Ghana's economy. However, the sector poses serious dangers to human health and the environment. Ground failures resulting from poorly supported stopes have led to injuries and fatalities in recent times. Dust and fumes from drilling and blasting of ore present health threats due to poor ventilation. Four prominent small scale underground mines were studied to identify the safety issues associated with small scale underground mining in Ghana. It is recognized that small scale underground mining in Ghana is inundated with unsafe acts and conditions including stope collapse, improper choice of working tools, absence of personal protective equipment and land degradation. Inadequate monitoring of the operations and lack of regulatory enforcement by the Minerals Commission of Ghana are major contributing factors to the environmental, safety and national security issues of the operations.
... Small scale mining, also termed artisanal gold mining (AGM) started as early as the 4th century in Ghana, and since that time, gold has been extracted from alluvial deposits in rivers, waterways, outcrops and subsurface sediments along the side of dried-up valleys through Hg amalgamation technique [3,10,11]. ...
Article
Full-text available
The Birim River, one of the main tributaries of the Pra River is among the important freshwater bodies in Ghana which serves as a rich source for gold and diamond production in the country. Artisanal mining activities along river bodies promote continual introduction of wide range of contaminants (heavy metals) into these water bodies, and their toxicity poses great threat to the ecology as well as the environment. This study assesses the level of heavy metals (Cr, Fe, Ni, Zn, As, Cd, Hg and Pb) in the Birim River of Ghana. The concentrations of the heavy metals were determined by Atomic Absorption Spectrophotometer (AAS) and Inductively Coupled Plasma – Mass Spectrometer (ICP-MS). Heavy metals concentration were analysed in the dissolved, suspended mineral fractions, and sediment phases of the River. The result obtained showed that the Birim River is heavily polluted with heavy metals. Samples [Apapam (KB2), Ahwenease (KB3), Adadeatem (KB4), Adukrom (KB5), Akim (KA2), Abodom (KA3), Kade (KA4), Anweaso (KA10) and Kusi (KA11)] with high heavy metals concentrations are located in areas where small scale mining is dominant, indicating that the major contamination source in the water body is resulting from small scale mining activities. Heavy metals concentration measured as dissolved were lower than WHO standards with the exception of Fe. There are high accumulations of heavy metals in the suspended mineral fractions of the river. The sediments were also greatly polluted with heavy metal sinks.
... The geology of the basin characterised by Tarkwaian, Birimian, Cape Coast and Discove granitoid complex system, has attracted both large-scale and small-scale mining companies (CONIWAS 2011;Tay et al. 2014). Competition between land users and the unsustainable approach of farming (excessive use of agrochemical and land clearing) as well as mining, especially illegal small-scale mining (popularly known as galamsey), are major threats to water sustainability in the basin (Donkor et al. 2006;Tay et al. 2014;Awotwi et al. 2018;Duncan et al. 2018). ...
Article
Full-text available
Illegal mining and inappropriate use of agrochemicals have exacerbated surface water pollution in Ghana. The quality of water has changed, and knowledge of their current condition is important for formulating policies to conserve the country's water bodies. This study assessed the quality of surface waters in Ghana's Pra River Basin. A survey of 344 local farmers randomly sampled was conducted and a physicochemical analysis of 33 water samples collected from 25 rivers in the basin. Boreholes are the main source of drinking water for 85% of farmers, and they assessed water quality by its appearance. Rainwater provides over 50% of the water needed by the respondents for domestic use. River water was mainly used for crop production and only secondarily for domestic use. At more than 80% of the sampled sites, pH, Fe and P were above the WHO recommended values, while Pb was exceeded at 30% of the sites. Cu, Hg, As and Fe were above permissible levels for irrigation, especially near the mining areas. The poor quality of river water makes it unusable despite its availability. A more effective and efficient land-use policy focusing on buffer zone protection is recommended to minimise water quality degradation in the basin. HIGHLIGHTS Surface water are mainly used for crop production in the Pra River Basin.; Mercury, Copper, Arsenic and Iron concentration levels exceed the permissible limits for irrigation in mostly mining communities.; Surface water is available but the level of pollution limits its usability.; Sustainable land management practices can reduce rate of surface water pollution in small-scale mining zones.;
... Similarly, the Densu River, which supplies parts of Accra with drinking water, is reportedly heavily polluted along its tributaries such that the Ghana Water Company has complained of increased cost of treating drinking water from this source. In rural communities, the main threats endangering the sanctity of water bodies have emanated from mining and agricultural practices (Donkor et al. 2005(Donkor et al. , 2006aBortey-Sam et al. 2015). ...
Article
Full-text available
Background Many years of gold mining in Ghana has generated huge environmental legacy issues, particularly contamination from heavy metals and metalloids. The present study evaluated the contamination from arsenic (As), cadmium (Cd), copper (Cu), mercury (Hg) and lead (Pb) in sediment cores at Bibiani, a historical gold mining town in Ghana. The study took a retrospective look at these contaminations by conducting sediment core analysis of heavy metals in sediments collected from Lake Amponsah in the Bibiani district. Sediment cores were sampled to a depth of 30 cm. ResultsThe Lake was found to be undergoing sedimentation at an average rate of 1.76 cm/y. There was marginal decline in Hg concentrations over the past two decades (from the 1990s to 2010s), while the other metals showed relatively increasing trends. The Hg policy restricting Hg usage in Ghana since 1989 has contributed to the recent marginal decline of Hg in the sediment. It was found that small-scale miners illicitly applied Hg but used crude retrofits to recover some of the Hg during the gold amalgamation process. This perhaps contributed to the marginal decline being observed in the sediment compartment with depth. Nevertheless, there was concern of potential risk of exposure to gaseous Hg during the amalgamation process. Conclusion Based on findings of this study, Hg legislation in Ghana should be enforced to the latter as it has shown good sign of reducing environmental contamination from this metal.
... Inhalation of mercury vapours results in high blood concentration of mercury which are implicated for many respiratory, neurologic, renal, immunologic, dermatologic and reproductive complications [28]. Human health impacts emanating from the utilization of mercury in ASGM have been reported in African countries of Benin [29], Burkina Faso [30], Ghana [31,32] and Mali [33]. This is evidenced by elevated levels of mercury in human blood, hair, urine and breast milk [26,34,35]. ...
Preprint
Syanyonja village in the gold district of Busia, South East of the Republic of Uganda contain geologically epigenetic gold quartz vein deposits in carbonate-altered mafic metavolcanic rocks, deposited as quartz reefs in mineralized shear zones. In supracrustal rocks, alluvial gold is obtained from weathered auriferous quartz veins, which are of late orogenic granitic activity. The Syanyonja gold deposits have long been subjected to artisanal and small-scale gold mining (ASGM) by the locals for livelihood. This study determined the amount of mercury discharged with tailings into Namukombe stream, a major water body in Syanyonja village and investigated the impacts of ASGM on the mining population and the environment. Quantitation of mercury discharged with tailings was done by mass balance method. Field survey at the mining sites was done followed by administration of questionnaires to 50 stampeders in the village. The study indicates that about 8% of mercury mixed with auriferous materials are lost in tailings, accounting for an annual mercury release of about 1.757 kg into the environment. Socio-demographic results indicate that the majority of the mining population (64%) are male and ASGM have left health and environmental footprints, which directly or indirectly affects the population. The most common health problems among miners are malaria (36%) and abdominal pain (20%). The standard of living of the miners are evidently low, and most mines are characterized by school dropouts, prostitutes and thieves. Mining sites have deplorably poor hygiene, with evident burning of amalgams to recover gold. ASGM have been accompanied by wanton mowing down of vegetation, land degradation as well as mercuric pollution of water, air, land and aquatic ecosystems. It is suggested that the Ugandan government should re-enforce committees to follow up on ASGM activities, train artisans on sustainable gold mining using borax, magnets, sluice boxes as well as take up farming actively as an alternative.
... Collection of Sediment was done with a pre-cleaned polyethylene shovel (Donkor et al., 2006). Two sediment samples were picked from each station; however no sediment sample was picked at the sampling point ACH. ...
... The other part is transported to the terminal basins much further downstream. Similar comments were made by Donkor et al. [38] in the Pra River, Ghana. The determination of correlation coefficient provides an idea of the possible relationship between metals and parameters of the study environment: homogeneous distribution, identical behaviour in the physical and chemical processes and influence of one on the other. ...
Article
Full-text available
Mercury used in gold amalgamation is a global concern and a major source of contamination and dispersion in environmental aquatic of Cote d'Ivoire, mainly in the North where clandestine gold mining activities are a local interest. The aim of this study was to assess the level of total mercury (Hg-T) contamination of sediments from Bagoue River. Water and sediments samples were collected during wet and dry seasons from six stations differently impacted. Spatial and seasonal variations in physical and chemical parameters were assessed. Results revealed that the level of Hg-T in water was 0.68±0.03 µg.L-1 and in the sediments, dry weight concentration was 0.064±0.01 mg.kg-1. The Hg-T concentration in sediments was significantly higher (p<0.05) during the dry season (0.089±0.053 mg.kg-1) than that recorded in the wet season (0.064±0.039 mg.kg-1). Ultimately, strong and positive correlations have been observed between Hg-T in sediments and sandy sediments (r = +1), as well as suspended materials (r = +0.85). The pollution status of mercury in sediments according to the geo-accumulation index was uncontaminated (-47.03) at all the seasons whereas enrichment factor has been moderate over climatic seasons at downstream stations heavily impacted by gold mining. The sandy texture of the River sediments favours the infiltration of mercury and its accumulation in groundwater. As a rate, the health risks associated with the consumption of these waters are potentially high.
... Previous studies on the Kakum Estuary and mangrove forest mostly sought to characterize and quantify biodiversity (Adotey, 2015;Aheto, Aduomih & Obodai, 2011;Aheto et al., 2014;Okyere, 2010;Sackey, Kpikpi & Imoro, 2011), while some assessed quality of water and sediments (Dzakpasu & Yankson, 2015;Fianko, Osae, Adomako, Adotey & Serfor-Armah, 2007;Koranteng-Addo, Bentum, Awuah & Owusu-Ansah, 2011;Levy, Asare, Yankson & Wubah, 2015;Okyere & Nortey, 2018). Few published literature are available on the ecological parameters of mangroves (see FoN, 2014) and estuarine water quality (Donkor, Bonzongo, Nartey & Adotey, 2006;Okyere, 2015;Okyere & Nortey, 2018) at Pra Estuary, although other works looked at issues concerning conservation of the estuary (FoN, 2015(FoN, , 2016(FoN, , 2017Kankam & Robadue, 2013). ...
Thesis
Full-text available
Mangrove forests provide a variety of valuable uses and resources for inhabitants of coastal communities. This study was aimed at assessing the health of mangrove forests at the estuaries of Kakum and Pra using multi criteria approach involving social, biological, chemical and physical factors. The study was conducted from March 2017 to August 2018. Socioeconomic data were gathered from 136 respondents through field surveys in ten communities around the two estuaries while remote sensing and Geographic Information System (GIS) were used to characterize mangrove cover change between the period 2005-2017. Species inventory, structural parameters, litter production and soil analyses were estimated in four study plots of sizes 0.25 ha within each mangrove forest whereas physico-chemical parameters of estuarine water were measured in situ. It was observed that coastal inhabitants harvested fuel wood, timber (poles), crabs, periwinkles and tilapia from these mangrove forests. Mangrove area at Kakum reduced by 41.58 % while that of Pra increased by 12.54 %, from 2005 to 2017. A total of 23 and 20 plants species, including five and three true mangroves were encountered at the Kakum and Pra mangrove forests, respectively. The mangrove species had low structural developments in terms of size and height. Annual litter production rate was lower at the Kakum mangrove forest (9.60 t ha-1 y-1) than at the Pra mangrove forest (10.72 t ha-1 y-1). The estuaries and mangrove sediments were of moderate quality. On the basis of computed mangrove health indices (MHI), the overall health of the Kakum mangrove forest was bad, whereas the Pra mangrove forest was moderately healthy. There is the pressing need for stakeholders to institute stringent management measures for sustainable conservation of both forests.
... Rural communities that lack improved access to water supply usually rely on raw untreated water from rivers, streams, lakes and dams for their sources of drinking water. Unfortunately, many of these reservoirs in Ghana are reportedly polluted with various toxic chemicals such as heavy metals (especially from illegal small scale gold mining activities) (Donkor et al., 2005;Donkor et al., 2006) and pesticides (from agricultural fields) (Ntow, 2001;Ntow et al., 2008;Obiri-Danso et al., 2011). Drinking untreated water from such reservoirs therefore has serious environmental health consequences. ...
Article
Full-text available
Biosand filter basically applies a system of sand, gravels and biologically active microorganisms to remove unwanted substances from drinking water. Field trials of the biosand filter for domestic water treatment in rural communities have shown remarkable health gains from its application. As such, there are calls to scale up its application in developing countries. This study investigated factors that may influence the acceptability of the biosand filter at the household level in rural communities in Ghana. The study further applied lifecycle environmental and cost assessments to analyse the eco-efficiency potential of the biosand filter and examined prospects of leveraging this potential for green business development. The key demographic and socioeconomic indicators of biosand filter acceptability related to gender, age, education and wealth. Females showed greater interest in the biosand filter, while discrete increase in age, relative advancement in education and economic status of respondents may each increase the prospects of purchasing biosand filter. Compared to local sachet water production, which was considered as a quasi-alternative to the biosand filter, it was established that the latter has superior eco-efficiency, provided quite comparable profitability and potentially viable for eco-business development. The information yielded by this study is useful for scaling up considerations of the biosand filter technology in Ghana and other West African countries.
... Mercury may accumulate in fish tissue especially if their source water contains their residues (Sserunjogi, 2009). It has been reported that smoking of fish may degrade methlymercury, a toxic form of mercury (Donkor et al., 2006). This could attribute to the absence of Hg in smoked Lates niloticus and Oreochromis niloticus. ...
Conference Paper
Full-text available
Fish remains to be an important source of proteins in developing countries including Tanzania. Fish processing methods like smoking aim at improving the shelf-life of smoked fish as well as taste and aroma. During smoking, smoke by-products from different materials used as source of heat are deposited on the fish. The deposited by-products include the carcinogenic polyclic aromatic hydrocarbons (PAHs) and heavy metals. Benzo(a)pyrene has been used as a marker for the occurrence of carcinogenic PAHs. The purpose of this study was to assess the different materials that are used in fish smoking practices, determine the levels of benzo(a)pyrene, mercury, cadmium and lead in smoked Lates niloticus and Oreochromis niloticus from different fish smoking areas in Mara and Mwanza regions. A total of 32 fish smokers were interviewed to assess the material used and how they use them to smoke their fish. This was followed by collection of 32 smoked fish samples for laboratory analysis of heavy metals (mercury, Cadmium and Lead) and concentration of benzo(a)pyrene. The findings of the study indicated that people engaged in smoking fish in the study areas are mostly using firewood and charcoal as their source of heat. There were no cases of the use of plastic materials. The laboratory results indicated that mercury and cadmium were not detected in all fish species while lead was detected at a mean concentration level of 0.28 μg/kg which is below the recommended level of 0.3 μg/kg as set by the EU. This indicated that smoked fish from Mara and Mwanza did not contain heavy metals to a harmful level. The Mean benzo(a)pyrene concentration detected was 4.79 μg/kg. This amount is higher compared to a level of 2 μg/kg set by the EU in 2014. There is therefore, a need for people who smoke fish to use other improved methods which will lower the levels of benzo(a)pyrene and the Government to have a continuous monitoring plan for these contaminants.
... μg L − 1 , Yitong River, China; 0.09-0.57 μg L − 1 , Donkor et al., 2006;Zhang et al., 2007). Moreover, there are two large iron and steel manufacturing facilities adjacent to Gumu Creek, which can emit Hg into the atmosphere through metal production and industrial fossil fuel combustion (Kim et al., 2010, Fig. 1). ...
Article
To investigate mercury (Hg) sources responsible for contamination at Gumu Creek in South Korea, Hg concentration (THg) and Hg isotope ratios were measured in the soil and sediment of Gumu Creek and the samples from a hazardous waste landfill (HWL). The THg ranged between 0.29 and 327 mg kg-1 and 9.5 to 414 mg kg-1 in the soil and sediment, respectively, reflecting heterogeneous distribution and elevated levels across the entire Gumu Creek. Without the soil with the lowest THg (0.30 ± 0.01 mg kg-1, n = 3), the δ202Hg (-0.83 to -0.18‰) and Δ199Hg (-0.24 to 0.01‰) of the sediment and soil of Gumu Creek were within the ranges of the HWL samples (δ202Hg; -1.29 to -0.38‰, Δ199Hg; -0.31 to 0.01‰). The comparison with the literature reporting sediment Hg isotope ratios impacted by various anthropogenic Hg sources revealed a presence of diverse Hg sources at Gumu Creek, including commercial liquid Hg, phenyl-Hg, and fly ash, consistent with the types of waste deposited within the HWL. Using commercial liquid Hg, fly ash, and the soil with the lowest THg as end-members, the ternary mixing model yielded 25 − 88% and 12 − 57% contributions from commercial liquid Hg and fly ash to the Gumu Creek sediment, respectively. The results of our study suggest that Hg isotope ratios are an effective tool for screening potential Hg sources at sites where the distribution of Hg is heterogeneous and multiple anthropogenic activities exist.
... The mean THg content of the sediments in this study is lower than the values registered in other global studies such as that reported by Donkor et al. (2006), Ramirez-Requelme et al. (2003) andFeng et al. (2006) (Table 2). However, Ramesh et al. (2012), Oladipo et al. (2013), Lasut et al. (2010), Pataranawata et al. (2007) andTaylor et al. (2005) reported lower THg content of sediments comparable to the THg concentrations recorded in this study (Table 2). ...
Article
Full-text available
The mercury content and the contamination characteristics of water, sediments, edible muscles of a non-piscivorous fish (Oreochromis nilotica Linnaeus 1758 [Cichlidae]) and yams (Dioscorea alata) from Namukombe stream in Busia gold district of Uganda were evaluated. Human health risk assessment from consumption of contaminated fish and yams as well as contact with contaminated sediments from the stream were performed. Forty-eight (48) samples of water (n = 12), sediments (n = 12), fish (n = 12) and yams (n = 12) were taken at intervals of 10 m from three gold recovery sites located at up, middle and down sluices of the stream and analyzed for total mercury (THg) using US EPA method 1631. Results (presented as means ± standard deviations) showed that water in the stream is polluted with mercury in the range of < detection limit to 1.21 ± 0.040 mg/L while sediments contain mean THg from < detection limit to 0.14 ± 0.040 μgg-1. Mean THg content of the edible muscles of O. nilotica ranged from < detection limit to 0.11 ± 0.014 μgg-1 while D. alata contained from < detection limit to 0.30 ± 0.173 μgg-1 mean THg. The estimated daily intake ranged from 0.0049 μgg-1day-1 to 0.0183 μgg-1day-1 and 0.0200 μgg-1day-1 to 0.0730 μgg-1day-1 for fish consumed by adults and children respectively. The corresponding health risk indices ranged from 0.0123 to 0.0458 and 0.0500 to 0.1830. Estimated daily intake was from 0.0042 μgg-1day-1 to 0.1279 μgg-1day-1 and 0.0130 μgg-1day-1 to 0.3940 μgg-1day-1 for D. alata consumed by adults and children respectively. The health risk indices recorded were from 0.011 to 0.320 and 0.033 to 0.985 for adults and children respectively. The mean THg content of the sediments, edible muscles of O. nilotica and D. alata were within acceptable WHO/US EPA limits. About 91.7% of the water samples had mean THg above US EPA maximum permissible limit for mercury in drinking water. Consumption of D. alata grown within 5 m radius up sluice of Namukombe stream may pose deleterious health risks as reflected by the health risk index of 0.985 being very close to one. From the pollution and risk assessments, mercury use should be delimited in Syanyonja artisanal gold mining areas. Solution to abolish mercury-based gold mining in the area need to be sought as soon as possible to avert the accentuating health, economic and ecological disaster arising from the continuous discharge of mercury into the surrounding areas. Other mercury-free gold recovering methods such as use of borax, sluice boxes and direct panning should be encouraged. Waste management system for contaminated wastewater, used mercury bottles and tailings should be centralized.
... Inhalation of mercury vapour results in high blood concentration of mercury implicated for many respiratory, neurologic, renal, immunologic, dermatologic and reproductive complications [28]. Human health impacts emanating from the utilization of mercury in ASGM have been reported in African countries of Benin [29], Burkina Faso [30], Ghana [31,32] and Mali [33]. This is evidenced by elevated levels of mercury in human blood, hair, urine and breast milk [26,34,35]. ...
Article
Full-text available
Aims: To determine the amount of mercury discharged into Namukombe stream, the major water body in Syanyonja village, Busia gold district and investigate the impacts of mercury-based artisanal and small-scale gold mining (ASGM) on the mining population and the environment. Study Design: Quantitation of mercury discharged with tailings was done by mass balance method. Field survey at the mining sites was done followed by administration of questionnaires to 50 stampeders in the village. Place and Duration of Study: The study was done in Syanyonja village in Syanyonja parish, Busitema subcounty, Samia Bugwe constituency, Busia gold district, South East of the Republic of Uganda between April 2019 to June 2019. Methodology: Fieldwork was done in Syanyonja village to appreciate the level of environmental pollution due to mercurial ASGM in the area. Quantitation of mercury discharged with tailings was done by mass balance method. Field survey at the mining sites was done followed by administration of 50 questionnaires to stampeders of at least 18 years old and ASGM experience of not less one year. Results: About 8% of mercury mixed with auriferous materials is lost in tailings, accounting for an annual mercury release of about 1.757 kg into the environment. Socio-demographic results indicated that the majority of the mining population (64%) are male and ASGM have left human health and environmental footprints, which directly or indirectly affects the population. The most common health problems among miners are malaria (36%) and abdominal pain (20%). The standard of living of the miners are evidently low, and most mines are characterized by school dropouts, prostitutes and thieves. Mining sites have deplorably poor hygiene, with evident burning of amalgams to recover gold. Conclusion: ASGM have been accompanied by wanton mowing down of vegetation, land degradation as well as mercuric pollution of water, air, land and aquatic ecosystems. It is suggested that the Ugandan government should re-enforce committees to follow up on ASGM activities and train artisans on sustainable (non-mercury) alternative gold extraction methods that do not create new toxic exposures such as using borax, magnets and sluice boxes. Artisans should take up farming actively as an alternative.
... mudfish), plants (e.g. water ferns and elephant grass) and humans have been reported (see Amegbey and Eshun 2003;Aryee et al. 2003;Donkor et al. 2006;Hilson 2006;Essumang et al. 2007;Tschakert and Singh 2007;Antwi-Agyei et al. 2009;Armah et al. 2012;Boateng et al. 2012;Bempah et al. 2013;). ...
... From Fig. 2 (c) and Kusimi, (2015) , ASM in the Birim is characterized by wet soil and have high organic matter and water contents since most of the ASM areas were primary forests before their conversion and are also located within floodplains. Also, there is a span of literature that have acknowledged the elevated concentrations of metals ( Nartey et al., 2011 ;Boamponsem et al., 2012 ;Zango et al., 2013 ;Bortey-Sam et al., 2015 ) especially mercury ( Amonoo-Neizer et al., 1996 ;Bonzongo et al., 2003 ;Donkor et al., 2006 ;Kwaansa-Ansah et al., 2010 ) within ASM landscapes in Ghana. Thus, the higher spectral characteristics of VRE 1 among the visible and infrared wavebands in the MSI made it possible to detect and contribute most to classifying ASM. ...
Article
Full-text available
Artisanal and Small-Scale Mining (ASM) landscapes form integral part of the Land use land cover (LULC) in the developing worlds. However, the spatial, spectral, and temporal footprints of ASM present some challenges for using most of the freely available optical satellite sensors for change analysis. The challenge is even profound in tropical West African countries like Ghana where there is prolonged cloud cover. Whiles very few studies have used Sentinel-2 data to map change analysis in ASM landscape, none examined the contribution of individual S2 bands to the ASM classifications. Also, despite the capabilities of Machine Learning (ML) and Deep Learning (DL) models for LULC classifications, few studies have compared the performances of different classifiers in mapping ASM landscape. This study utilized Sentinel-2 data, four ML and DL models (Artificial Neural Network –ANN, Random Forest – RF, Support Vector Machines –SVM, a pixel-based Convolutional Neural Network-CNN) and image segmentation to examine the performance of S2 bands and ML and DL algorithms for change analysis in ASM landscape, with the Birim Basin in Ghana as a study area. The result of the change analysis was used to assess changes in LULC during the recent ban on the expansion of ASM in the country. It was found out that ANN is a better classifier of ASM achieving the highest overall accuracy (OA) of 99.80 % on the segmented Sentinel-2 bands. The study also found out that the Band 5 Vegetation Red Edge (VRE) 1 contributed most to classifying ASM, with the segmented VRE 1 being superlative over the other predictors. In terms of expansion, ASM increased by 59.17 km² within the period of the study (January 2017 to December 2018), suggesting that ASM still took place under the watch of the ban. The classification results showed that most of the peripheral of forest and farmland have been converted to ASM with little disturbance within the interior of the forest reserves. The study revealed that, the ban was yielding very little or no results due to a number of policy deficiencies including low staff strength, lack of logistics and low remuneration. Enforcement of legal instruments against ASM and farming activities within the forest reserves, improvement in the monitoring systems and intensification of public education on the value of forest and the need to protect it are some of the major recommendations that could control encroachment on the forest reserves.
Chapter
Mercury is a ubiquitous environmental contaminant. Exposures to mercury occur globally and pose significant threats to human health. Mercury toxicity to the nervous system has been extensively studied, and risks to human health as a result of mercury exposure have been evaluated on this basis, especially for exposures at high doses. Data from experimental models, such as rodent systems, suggest that mercury may also have a significant effect on the function of the immune system. However, little is known about the risks posed to human health as a result of mercury immunotoxicity, mainly due to variations in dose, route of exposure, and differences between the rodent and human immune systems. The evidence for mercury as an immunotoxic agent is reviewed here, specifically in the context of human exposures to mercury and the relevance of models of mercury immunotoxicity to human health. In light of evidence that mercury may affect the immune system, the influence of the immune system in other organ systems targeted by mercury is also reviewed.
Article
The total and dissolved lead, cadmium, mercury, nickel, chromium, cobalt, and arsenic in 30 water samples collected from Bosomtwe Lake were analyzed. Arsenic bioavailability was also determined using the ARSOlux test system. Except for chromium, their mean values in the study results exceeded the WHO permissible limit for potability. Cancer and non‐cancer effects associated with exposure to dissolved and total metals by a child and an adult via oral and dermal routes were estimated. The hazard quotient (HQ) values obtained (except adult exposure to total arsenic of 1.71 × 10⁰⁰) were less than unity. Between child and adult, the recorded hazard index (HI) was 0.82 and 1.75, respectively. The HI results indicate that the adult population is at risk for non‐cancer health effects. Arsenic was the element of concern, and it remained biologically available for uptake by target groups. For child and adult, respectively, arsenic contributed 96.39% and 97.29% to HI values. The risk values for cancer in a child and an adult with oral and dermal exposure to dissolved and total arsenic were lower than the USEPA range. Principal component and cluster analysis identified atmospheric deposition, geogenic, and unregulated application of agrochemicals as plausible sources of water pollution in Bosomtwe Lake. Practitioner points • The hazard quotient (HQ) values obtained for adult exposure to total arsenic was 1.71 × 10⁰⁰. • Arsenic remained biologically available for uptake by target groups. • The calculated health index (HI) indicated that the adult population is at risk for non‐cancer health effects. • Arsenic contributed 96.39% and 97.29% to HI values for a child and an adult. • Atmospheric deposition, geogenic, and unregulated application of agrochemicals were the plausible sources of water pollution in Bosomtwe Lake.
Article
Full-text available
Analysis of mercury (Hg) in water and sediment samples from Krueng Sabee (KS), Panga (P) and Teunom (T) rivers have been carried out. Water and sediment samples were collected at three different sampling points. Concentration of mercury was determined by using Atomic Absorption Spectrophotometer (AAS). Measurement of temperature, pH and salinity of the water samples was carried out in situ method. The results of in situ measurements showed a temperature ranges of 24 to 32°C, pH of 6 - 8 and salinity of 0.1 - 0.3. Based on the analysis of samples, the concentration of mercury in water and sediment samples during March 2019 (sunny condition) were 0.3328 and 6.2330 μg/L, respectively and April 2019 (rainy condition) were 0.0560 and 0.2778 μg/L, respectively. Evaluation of the pattern of Hg distribution in water and sediment samples was conducted by the Principal Component Analysis (PCA) method. The result of PCA analysis in sediment samples showed a strong correlation between Hg concentration at the KS1 and KS2 sampling points. Meanwhile, the concentration of Hg in water samples showed a strong correlation at sampling points of T2 and T3.
Article
Full-text available
Environmental media contamination with mercury, because of illegal artisanal small-scale gold mining (popularly called galamsey), is a major concern in Ghana; yet specific details as to how such contaminations are influenced or distributed across different galamsey operations have been lacking. We monitored mercury levels across nine different galamsey operations (Washing Board, Washing Plant, Anwona, Dig and Wash, Dredging, Underground Abandoned Shaft, Underground Sample Pit, Chamfi and Mill House) in three hotspot assemblies (Tarkwa Nsuaem, Amenfi East and Prestea Huni Valley) of the Western Region of Ghana. Triplicate samples each of background soil, surface water/drainage, slurry/sludge and galamsey waste materials (totaling 160) were obtained and analyzed using Atomic Absorption Spectrophotometer (AAS) to determine total Hg concentrations. From the comparison of mean ranked concentration of mercury, using the Kruskal-Wallis Test, it was realized that the observed differences in ranking was significant for all four environmental media considered. Thus, the poor handling, usage and disposal of mercury from the different galamsey activities did result in elevation of harmful quantities of mercury into the environment. Overall, the highest median value obtained for mercury was recorded at the Mill House galamsey sites and within slurry/sludge medium. This was followed by Chamfi, Washing Board, Washing Plant, Anwona, Dig and Wash and Dredging in descending order, with the Underground Abandoned Shaft and Underground Sample Pit galamsey types recording values below detection limit. In terms of their contribution to mercury contamination to the environment, Mill House, Chamfi, Anwona, Washing Board and Washing Plant galamsey types recorded the highest mean rankings. Overall, key priority information required for influencing reclamation and cleanup policy decisions for mercury, for the many affected wastelands across the country, can be derived from this paper.
Article
Full-text available
Background. Mercury (Hg) is a heavy metal that can cause several adverse health effects based on its form (organic, inorganic or elemental), duration and pathway of exposure. Measurement of mercury present in human biological media is often used to assess human exposure to mercury at mining sites. Objectives. The aim of the present study was to measure the concentrations of total mercury in urine, hair, and fingernails of miners and inhabitants of Amansie West District, Ghana. Methods. Concentrations of total mercury were measured in sixty–eight miners and twelve non–miners in the study area using cold vapor atomic absorption spectrophotometry with an automatic mercury analyzer (HG 5000). Results. Total mercury in nails and hair of smelter miners was 3.32 ± 0.36 and 6.59 ± 0.01 μg/g, respectively. Total mercury concentrations in hair samples obtained from smelter miners were above the 1 μg/g guideline set by the United States Environmental Protection Agency (USEPA). Moreover, the total mercury concentration in urine samples was 6.97 ± 0.06 μg/L, far below the >25 μg/L level considered to be a high level of mercury contamination. The total mercury accrued by the individuals was not dependent on age, but was positively associated with duration of stay. Conclusions. Based on the total mercury (THg) levels analyzed in the biological media, artisanal gold mining activities in Amansie West District are on the increase with a potential risk of developing chronic effects. However, the majority of the population, particularly those engaged in artisanal small–scale gold mining, are unmindful of the hazards posed by the use of mercury in mining operations. The results showed that THg in urine, hair, and fingernails more efficiently distinguished mercury exposure in people close to mining and Hg pollution sources than in people living far from the mining sites. Further education on cleaner artisanal gold mining processes could help to minimize the impact of mercury use and exposure on human health and the environment. Participant Consent. Obtained Ethics Approval. This study was approved by the Ghana Environmental Protection Agency and the Ministry of Local Government and Rural Development in Manso Nkwanta. Competing Interests. The authors declare no competing financial interests.
Chapter
Rivers are major pathways for a variety of materials to flow in and out of reservoirs. Impounding rivers changes the characteristics of a water body from “rivers’’ to “reservoirs”, affecting not only their hydrology but also their physical, chemical, and biological characteristics. To understand the influence of damming on the distribution and methylation of Hg within a river-reservoir ecosystem, this chapter illustrates the spatial and temporal distributions of Hg species in the inflow–outflow rivers of the six cascade reservoirs in Wujiang River Basin, Southwest China. Furthermore, the influence of cascade reservoirs on the distributions of Hg species in rivers of Wujiang River Basin is elucidated as well.
Thesis
Très appréciés des consommateurs du fait de leur qualité nutritionnelle, les produits de la mer jouent un rôle important dans l'alimentation humaine. Toutefois, la confiance du consommateur vis-à-vis de leur qualité est affectée par les riques associés à une exposition aux contaminants chimiques et à la fraîcheur des produits. Si le premier aspect résulte de la pollution des eaux marines sous l'effet d'une forte anthropisation des littoraux, le second est lié à la haute périssabilité de ces produits. Évaluer les niveaux de contamination chimique et la qualité-fraîcheur des produits de la mer est plus qu'un besoin : c'est aujourd'hui une nécéssité. C'est dans ce contexte que les travaux de cette thèse ont été menés. Deux objectifs principaux ont été visés dans la présente étude. Le premier objectif de ce travail était de faire une évaluation spatiale et saisonnière des niveaux de contamination par les polluants métalliques et organiques (HAPs et PCBs) des zones côtières du Sénégal en s'intéressant aux teneurs en contaminants dans les organismes marins. Nous avons étudié 7 espèces marines représentatives des différents maillons de la chaîne trophique (une macroalgue verte, un mollusque bivalve, un crustacé et 4 espèces de poisson) prélevées le long du littoral au niveau de 5 sites présentant des degrés d'anthropisation différents. Les résultats de cette étude montrent que les teneurs en contaminants chimiques des organismes marins sont variables selon les espèces et soulignent ainsi la nécéssité de l'approche multi-espèces pour l'étude de la contamination chimique du milieu. Des variations inter-sites de la teneur en contaminants chimiques dans les organismes ont été mis en évidence. Les sites les plus anthropisés comme Soubédioune et Rusfisque sont ceux qui présentent les teneurs les plus élevées. Les niveaux de contamination métalliques et organiques dans les organismes marins du littoral sénégalais sont inférieurs ou du même ordre de grandeur que ceux mesurés dans d'autres régions d'Afrique de l'Ouest ou dans d'autres régions du monde. L'évaluation des risques associés à l'ingestion des produits de la mer analysés montre que les teneurs en contaminants chimiques sont faibles et inférieures aux limites maximales admissibles pour la consommation humaine (norme EU). Seuls les sites de Rufisque et Soumbédioune présentent quelques dépassements chez certaines espèces (moules, sardinelles). Le deuxième objectif de cette étude était de développer des méthodes permettant d'évaluer la fraîcheur des filets de poisson et de différencier des filets frais des filets décongelés. Les méthodes retenues sont basées sur la mesure de l'augmentation de la perméabilité cellulaire du muscle de poisson. La conservation des filets de poisson à 4°C va conduire à une perméabilisation des cellules dans le temps qui peut être apréhendée par la mesure de la libération d'enzymes intracytoplasmiques ou par l'augmentation de la perméabilité des cellules à des colorants fluorescents. La mesure de l'activité LDH est intéressante à double titre : elle va permettre d'une part de mesure le niveau de lyse cellulaire, donc le niveau d'altération, des filets de poisson dans le temps. Elle va permettre d'autre part grâce à sa sensibilité à la congélation de mieux cerner les conditions qui permettraient à terme de faire la distinction entre les filets frais et des filets congelés/décongelés.
Article
Full-text available
The study focused on how environmental degradation due to unregulated illegal mining activities is affecting the welfare of communities in general and women in particular with regards to access good quality water. The methodological design was a qualitative approach and focused on the two districts of Shamva and Bindura in Mashonaland Central Province, Zimbabwe. The study noted that the area of environmental policing has remained weak and compromised owing to a combination of factors, key among them being the difficult socioeconomic environment which has often seen a lot of communities destroying the environment around them, political populism leading to the destruction of local ecologies and general disregard of responsibilities by companies operating mining, construction, and other enterprises.This has seen the gradual destruction and pollution of fresh water bodies across the communities.The study revealed that there is a considerable level of pollution on some water bodies in the two districts. The pollution is largely caused by the use of mercury and cyanide by the illegal gold panners and artisanal miners in the area. This has restricted opportunities for women's access to safe domestic water. Women are using strategies such as outsourcing from neighboring communities with relatively safe water for domestic use, differentiating water for cooking and drinking and for other activities like bathing and laundry, water harvesting during rain seasons and buying from shops in extreme circumstances. In conclusion, the coping mechanisms only offer temporary relief and are not be sustainable in the long run.
Chapter
This chapter employs the environmental justice framework to describe the environmental disadvantages of marginalised Roma communities in Eastern Slovakia.
Article
Full-text available
Most national and international discussions have not seriously recognized the role religio-cultural practices of indigenous Africans can play in mitigating the effects of climate change. This paper, examines the contribution the indigenous people can make towards the mitigation of the effects of climate change, using the Akan of Ghana as a case study. Mostly, indigenous people who are the major stakeholders in land use in Ghana are marginalized when policies aimed at reducing environmental degradation are made. This has resulted in low gains in the fight against environmental degradation despite several interventions in Ghana. A recent report puts Ghana into a net-emitter of GHG bracket. This means the country has to embark on a Low Carbon Development Strategy to address the situation. This paper, therefore argues that unless indigenous people—major stakeholders of land use—are duly involved; it will be difficult to address the effects of climate change in Ghana.
Article
In Senegal, the environmental impact of artisanal small-scale gold mining (ASGM) using mercury (Hg) is poorly documented despite its intensification over the past two decades. We report here a complete dataset including the distribution and speciation of Hg in soil, sediment, and water in pristine and ASGM impacted sites of the Gambia River ecosystem (Kedougou region - eastern Senegal). Selective extraction showed that soils surrounding ASGM activities were contaminated with elemental Hg [Hg(0)] at concentrations up to 3.9 mg kg ⁻¹ . In the Gambia River, high total Hg (THg: 1.16 ± 0.80 mg kg ⁻¹ ) and methylmercury (MeHg: 3.2 ± 2.3 ng g ⁻¹ ) were also measured in sediment samples collected at ASGM sites. Along the stream, THg concentrations in sediment decrease with distance from the ASGM sites, while those of methylmercury increase downstream. The study of THg and MeHg partitioning between filtered surface water and suspended particles demonstrate that particulate transport is responsible for the downstream dissemination of the Hg contamination from ASGM sites. Sedimentation of fine particles enriched in Hg downstream ASGM sites likely favors MeHg production and accumulation in sediment. Although elemental Hg is weakly labile, surface soil erosion may also provide important and long-term Hg inputs to downstream aquatic ecosystems, where it can be oxidized and methylated. Finally, the dissemination of THg and MeHg downstream from the ASGM sites in the Gambia River may constitute a long-term source of contamination and can have a large scale impact on the aquatic ecosystem through biomagnification.
Preprint
The mercuric content, pollution and contamination characteristics of water, sediments, edible muscles of a non-piscivorous fish (Oreochromis nilotica Linnaeus 1758 [Cichlidae]) and yams (Dioscorea alata) in mercury-based artisanal and small-scale gold mining (ASGM) impacted Namukombe stream and its propinquity, Busia gold district, Uganda were evaluated. Human health risk assessment from consumption of the fishes and yams as well as dermal contact with sediments from the stream were performed. Forty-eight (48) samples of water (12), sediments (12), fish (12), and yams (12) were taken at intervals of 0, 10, 20 and 30m from up, middle and down sluices of the stream and analyzed for total mercury (THg) using US EPA method 1631. Results showed that water in the stream is polluted with mercury (Hg) in the range of 0.00 to 1.21±0.070mg/L while sediments contain Hg up to 0.14±0.040μgg-1. THg content of the edible muscles of O. nilotica ranges from 0.00 to 0.11±0.010μgg-1 while yams contain 0.00 to 0.30±0.001μgg-1 of Hg. The estimated daily intakes (EDIs) ranged from 0.0049 to 0.0183μgg-1day-1 and 0.020 to 0.073μgg-1day-1 for fish consumed by adults and children respectively. The corresponding health risk indices (HRIs) ranged from 0.0123 to 0.04576 and 0.05 to 0.183. EDIs were from 0.0042 to 0.1279μgg-1day-1 and 0.013 to 0.394μgg-1day-1 for yams consumed by adults and children respectively. The HRIs recorded were from 0.011 to 0.320 and to 0.033 to 0.985. All the mean THg contents of the investigated matrices were within acceptable WHO/US EPA limits except for water samples. Consumption of yams grown at 0m up sluice of Namukombe stream may pose deleterious health risks as reflected by the HRI of 0.985 being very close to 1.0. From pollution and risk assessments, Hg usage should be delimited in Syanyonja ASGM areas; solutions to abolish mercury based ASGM in the area ought to be sought at its soonest to avert the accentuating health, economic and ecological disaster arising from the continual discharge of Hg into the surrounding areas. Other safe gold recovery methods such as use of borax should be encouraged. Waste management system for contaminated wastewater, used Hg bottles and tailings should be centralized to enable Hg waste management in ASGM areas in Syanyonja.
Article
Full-text available
The human activities impact on the mercury (Hg) distribution in the Amazon waters is still discussed but very few information regarding the Hg sources from the highly turbid Andean headwaters have been published. The annualload of suspended sediments eroded from the Bolivian Andes, averages 300 10^6 tons in the Beni river, of which till 97% is exported during the rainy season. At the edge of the Bolivian Andean piedmont, the total Hg concentration vary from 8 ng l^{-1} during the dry season, to 1600 ng l^{-1} during the high water period [1]. During this stage, it appears that the maximum concentrations of Hg associated with the fine particles and the highest Hg specific fluxes are observed in the rivers exploited for their alluvial gold during the last century. The black-shales series associated to the gold deposits are characterised by high natural Hg contents, which can be released in the hydrographic system by both chemical and physical weathering. But if we compare two clear water rivers characterised by the same suspended sediment concentrations, the maximum specific Hg flux varies between 126 kg km^{-2} j^{-1} in the pristine river, to 590 kg km^{-2} j^{-1} in the river characterised by recent human activities.
Article
Full-text available
This paper investigates the aqueous geochemistry of mercury (Hg) in three aquatic systems impacted by either past or present mining activities. The Idrija River in Slovenia flows near the Idrija mercury mine, the second largest mercury mine in the world, with continuous mining and smelting activities for five centuries. During this period, it has been estimated that over 30 000 tonnes of Hg have been released into the mine's surrounding environment, due to inefficient smelting technologies and Hg left behind in mine tailings within the river basin. In contrast to cinnabar mining in the Idrija River Basin, the Carson River in Nevada and the Madeira River in the Brazilian Amazon are impacted by metallic mercury (Hg0) used in the amalgamation process to extract gold (Au) and/or silver (Ag) from crude ores and fine alluvial materials. The Carson River Basin was the site of intensive Au- and Ag-mining for over 50 years in the late 1800s and early 1900s, resulting in an estimated 7000 tonnes of Hg lost to the river and its watershed. The Madeira River is a site of ongoing use of Hg0 in Au-prospecting. This study reports on the level and speciation of Hg, as well as factors controlling levels of methyl-Hg using aqueous data. Surface water samples collected along longitudinal transects upstream of well-identified point sources of Hg, except for the Madeira River, to river deltas were analysed for Hg and geochemical parameters of interest. Samples from Idrija and Carson rivers show clear evidence of contamination, with Hg levels up to several hundreds of ng 1-1 downstream from main point sources. Unlike Idrija and the Carson rivers, water samples collected from the Madeira River exhibited much lower Hg levels (9.51 ng 1-1 on average, n = 16). Measured physiochemical parameters are used to determine the fate of Hg in these three river systems.
Article
Full-text available
We present the first mercury measurements made in African waters utilizing ultraclean collection and state-of-the-art analytical techniques. Concentrations of total mercury (HgT) in streams entering Lake Naivasha, Kenya are similar to values obtained from runoff water in the Northern Hemisphere.
Article
Full-text available
Total concentrations of Hg, Al, Fe, As, Pb, Cu, Cr, Ni, Mn, Co, V, and Zn were determined in surface sediments collected from 21 locations within the gold mining impacted Pra River basin in southwestern Ghana. Samples were collected during both the rainy and dry seasons. We hypothesized that in the rural southwestern portion of Ghana, the lack of industrial activities makes artisanal gold mining (AGM) by Hg amalgamation the main source of water resource contamination with heavy metals. Therefore, metals showing concentration trends similar to that of Hg in the studied system are likely impacted by AGM. We found that total-Hg (THg) concentrations in riverine sediments are rather low as compared to other aquatic systems that are impacted by similar mining activities. Measured THg concentrations ranged from 0.018 to 2.917 mg/kg in samples collected in the rainy season and from about 0.01 to 0.043 mg/kg in those collected during the dry season. However, the determination of the enrichment factor (EF) calculated using shale data as reference background values showed signs of severe contamination in most of the sampled sites. In the dry season, THg concentrations correlated positively and significantly to the concentrations of As (r = 0.864, p < 0.01), Cu (r = 0.691, p < 0.05), and Ni (r = 0.579, p < 0.05). Based on our previously stated hypothesis, this could then be an indication of the impact of AGM on ambient levels of these 3 elements. However, the determined concentrations of Cu, and Ni co-varied significantly with Al, suggesting that natural sources do account for the observed levels. Accordingly, both AGM and metal inputs from weathered natural deposits are likely co-responsible for the observed levels of Cu and Ni. In contrast, the lack of correlation between As and Al tends to suggest an impact of AGM on As levels. Overall, our data suggest that besides Hg and to some extent As, the impact of AGM on ambient levels of investigated metals in the gold mining impacted Pra River remains negligible. Finally, the increase in metal concentrations from the dry to the rainy season underlines the impact of changes in hydrologic conditions on levels and fate of metals in this tropical aquatic system.
Article
Full-text available
 The lower Ganges-Brahmaputra-Meghna (G-B-M) drainage basin occupies the total Bengal Basin, which is one of the unique basins of the world because of its location and size, density of population, and catastrophic deposition of sediments. The increased heavy metal concentration in the 63 m fraction of surface sediments shows similarity among major segments of the G-B-M system in the basin, which reflects the homogenization of lithologic and chemical diversity of the greater denudation regime by the river processes. The differences in heavy metal concentation in the lower G-B-M system with that of its upper and middle counterpart is mainly related to the contrast between Himalayan rivers and the other major South Asian rivers, and may be due to the geological differences of their denudation regime. Heavy metals in the Lower G-B-M system have an affinity towards the clay fraction of the sediments. The correlation matix of heavy metals in the lower Brahmaputra and Meghna suggests the importance of Fe-Mn oxyhydroxides in their accumulations. Iron, Ti and Mn are higher in the Meghna main channel, Zn is higher in the Meghna tributaries, and Cr is higher in both the Brahmaputra and Meghna compared to the value for standard shale. The enrichment factor is ≤1 for most of the metals except Mn which is relatively higher in the Meghna and lower Ganges main channels. The geoaccumulation index (Igeo) for most of the heavy metals lies below grade zero, suggesting unpolluted sediment quality. The lower Ganges system shows relatively higher concentration in the nondetrital fraction of heavy metals, probably due to the presence of petroleum refinery, industrial and mining effluents, and agricultural runoff in the drainage basin. The relative uniformity in concentration of heavy metals in vertical profiles may be due to the uniformity in sediment grain size and catastrophic deposition of sediments, where the time period represented by the vertical sediment column is not enough to reflect the cultural accumulation of heavy metals. The Bengal basin thus represents a relatively unperturbed alluvial basin with regards to heavy metal pollution.
Article
Full-text available
 The concentrations of various metals (Cr, Cu, Co, Fe, Mn, Ni, Pb, Zn, and Cd) were determined in recently deposited surface sediments of the Gomati River in the Lucknow urban area. Markedly elevated concentrations (milligrams per kilogram) of some of the metals, Cd (0.26–3.62), Cu (33–147), Ni (45–86), Pb (25–77), and Zn (90–389) were observed. Profiles of these metals across the Lucknow urban stretch show a progressive downstream increase due to additions from 4 major drainage networks discharging the urban effluents into the river. The degree of metal contamination is compared with the local background and global standards. The geoaccumulation index order for the river sediments is Cd>Zn>Cu>Cr>Pb. Significant correlations were observed between Cr and Zn, Cr and Cu, Cu and Zn and total sediment carbon with Cr and Zn. This study reveals that the urbanization process is associated with higher concentrations of heavy metals such as Cd, Cu, Cr, Pb, and Zn in the Gomati River sediments. To keep the river clean for the future, it is strongly recommended that urban effluents should not be overlooked before their discharge into the river.
Article
Full-text available
The present study was aimed to evaluate comparatively the levels of methylmercury (MeHg) in human hair, collected from different groups of Amazonian populations exposed to contamined fish. The study was undertaken in fishing villages and gold mining areas, mainly in the Tapajs and Madeira river basins, two of the main tributaries of Amazon river. The study population included 125 hair samples, chosen from a collection of over one thousand samples collected in different periods. Hair analyses were conducted with a new efficient extraction technique and measured with ECD-gas chromatographer. This analytical method presented good accuracy and precision when compared with standard hair samples from IAEA. A highly significant correlation was found at the interlaboratory exercise between National Institute for Minamata Disease and our laboratory at Federal University of Rio de Janeiro. The results of the present study showed, through hair analysis, a relationship between environmental contamination by mercury and methylmercury and dietary habits of the Amazon population. The highest levels of MeHg in hair samples were found in riverine population from upper Tapajs river and in riverine population from some tributaries of Madeira river, followed by population of fishing villages from Madeira river. Majority of the women of child-bearing age presented high MeHg concentration in hair samples (10 mg.kg-1). On the other hand, Yanomami Indians presented MeHg concentration below the limit tolerable of 6 mg.kg-1.
Article
Full-text available
The Ashanti belt of Ghana constitutes a gold province which has produced a total of about 1500 t of gold historically. Gold mineralization is found in steep, NNE-SSW to NE-SW trending shear zones predominantly transecting metasediments of the Palaeoproterozoic Birimian Supergroup (2.2–2.1 Ga), disseminated in ca. 2.1 Ga granitoids, in paleo-conglomerates of the Tarkwaian Group (< 2135 Ma), and in recent placers. The distribution of gold, its chemistry, paragenesis and mineralogical siting in the mesothermal ores of the major mines in the Ashanti belt, namely Konongo, Ashanti, Bogosu and Prestea mine, are the subject of this study. At the localities studied, gold is present in two main types of ores: 1. Quartz veins with free-milling gold. The gold is relatively silver-rich (true fineness values from 730 to 954) and is accompanied by a distinct suite of Cu, Pb, Sb sulfides. 2. Sulfide ores, consisting of arsenopyrite, pyrite and rarer pyrrhotite and marcasite, with refractory gold. The ores have apparent fineness values larger than 910. Arsenopyrite and locally (at Bogosu) pyrite were identified as the hosts of submicroscopic gold. Mean concentrations of gold in arsenopyrite in various samples from the different mines, obtained by secondary ion mass spectrometry (SIMS), range from 67 to 314 ppm Au. Gold concentration mapping in individual arsenopyrite crystals from the different deposits revealed similar patterns of gold distribution: the grains possess a gold-poor core, and elevated gold contents are present along distinct crystal growth zones towards their rims. The outermost crystal layer is usually gold-poor. The well-preserved distribution patterns also indicate that remobilization of gold from the sulfides played an insignificant role in the ores of the Ashanti belt. Multiple quartz veining and growth zoning of the sulfides are interpreted as manifestations of multiple episodes of fluid infiltration, fluid flow and mineral deposition. The bimodal occurrence of gold in spatially closely associated quartz vein and sulfide ores indicates a genetic link between these ore types. A model implying a grossly coeval formation of the ores from mesothermal fluids is proposed.
Article
Full-text available
A serious health scare involving thesupply of drinking water to Sydney, Australia hasrecently focussed attention on the environmentalstatus of river catchments of the main reservoir, LakeBurragorang. Although the Coxs River – a majorcatchment of Lake Burragorang – comprises mainlyforests and grazing land, it supports a moderate sizedtown, power stations and coal mines. The heavy metal content of stream-bed sedimentscharacterises environmental impact in this ruralcatchment and sources of contamination. Sediment in acreek flowing through a country town (population 12 000) is markedly enriched in Cr, Pb and Zn (3, 18and 52, respectively) over background, probably dueto a long history of metal-based industry. The highestCu, Pb and Zn concentrations (204, 332 and2460 g g-1, respectively) in fluvialsediment in the town are, however associated withdischarges from a sewage treatment plant. Twocoal-based power stations in the catchment contributeconsiderable Cu and Ni (maximum concentrations 562 and157 g g-1, respectively) to ambient fluvialsediments, possibly from cooling towers and coalstorage areas. The highest Co and Cr concentrations(113 and 490 g g-1) in fluvial sediments ofthis catchment are associated with coal-miningactivities. Selective extraction indicates that about50% of the anthropogenic fraction may bebioavailable, whereas sequential extraction proceduressuggest that
Article
Full-text available
The present work was carried out on the hydroelectric reservoir Petit-Saut on the Sinnamary river in French Guiana. Measurements were performed during the wet and dry seasons along a longitudinal gradient, from upstream of the reservoir in two inflow rivers, to the Sinnamary estuary downstream of the dam. Gold extraction has led to a marked increase in suspended matter and total mercury (HgT) in one of the rivers. Dissolved monomethylmercury (MMHg) measured in surface waters were similar for both rivers: 0.03-0.05 ng l(-1) (1.0-1.7% of the dissolved HgT). These results indicate similar methylation efficiency and/or transfer of MMHg into the dissolved fraction of the water column, independently of the amounts of inorganic mercury transported. Dissolved MMHg concentrations in surface waters of the reservoir were similar to those in the rivers, but were more than 10 times higher in deep anoxic waters, up to 0.6 ng l(-1) (20 % of dissolved HgT). The MMHg concentration profiles in the water column suggest that methylation occurs mainly in anoxic waters and sediments in relation with the activity of sulfate reducing bacteria. Dissolved MMHg concentrations measured in the Sinnamary at the base of the dam were still high (0.5 - 0.6 ng l(-1); 20 to 35% of the dissolved HgT).
Article
Full-text available
In the Brazilian Amazon gold mining (“garimpos”), Hg is used to amalgamatefine gold particles from placer deposits., A 2:l or even greater Hg/Auamalgamation ratio were observed by Lacerda et al. (1995) from several“garimpos” in the Amazon. Hg loss from gold mining to local ecosystems wasestimated to reach 1,300 t in the Amazon, between 1980 and 1993 (Cid deSouza and Bidone, 1994). More than 50% of this Hg were used in “garimpos”located in the Tapajos river basin, in Para State, the most important gold miningarea in Northern Brazilian Amazon in the 80’s, when the peak in Amazon “goldrush” occurres. Generally, the released Hg° is incorporate into the riversediments. Environmental methylmercury (MeHg) arises largely, if not solely,from the methylation of inorganic mercury (Hg
Article
Full-text available
Release and spreading of mercury from gold mining is a widespread problem in the Amazon area. Today we have rather good knowledge of the mercury situation. Tens of investigations have considered mainly concentrations in fish and human hair. Metallic mercury is used for amalgamation of gold, and the mercury is released by evaporation at reburning sites. The first extraction (burning) is performed in the field at the garimpos and the second (reburning) in gold shops in towns. This practice may cause severe exposure to elemental mercury by inhalation for people working with gold purification. Mercury is also released in substantial amounts to rivers and lakes. This mercury may be bioaccumulated as methylmercury in aquatic food chains. Predatory fish often contain mercury in concentrations that far exceed the safety norms in Brazil. As many people eat fish daily, there is a high exposure to methylmercury. Neurological disorders have been found in exposed persons. Methylmercury concentrations in hair are often at levels that may cause clinical symptoms of Minamata disease. The greatest health hazard index values have been estimated for people eating contaminated fish.
Chapter
In a paper entitled “A Silent Epidemic of Environmental Metal Poisoning,” published in 1988, Nriagu rang the bell on the potential health effects of increasing trace metal levels in natural systems. This paper was followed by several publications focussing on the assessment of worldwide contamination of the environment by trace metals, as well as the impact of toxic metals on ecosystem functions and human health.
Article
New results from an extensive survey on the mercury concentration in different environmental compartments (river water, suspended and bottom sediments, soil, and air), as well as in fish and human hair are presented. Concentration of mercury in bottom sediments (up to 157μg Hg.g-1 dw) from small forest streams, close to the main mining areas, as well as in fish (up to 2.7μg Hg.g-1 ww) taken from Madeira tributaries, indicate heavy mercury contamination in this area. Air-mercury concentrations prove to be quite similar to control areas, but can reach very high levels in the vicinity of Au-Hg reburning locations. The mercury burden in human hair of up to 26.7μg/g-1 suggests high exposure in local populations. -from Authors
Article
A total of 144 cases of alkyl-mercury poisoning in rural Ghana were investigated. Out of ignorance, the patients had ingested maize which was dressed with ethylmercuric chloride and intended for sowing. They all showed the usual clinical features of alkyl-mercury poisoning, and 20 persons died. This incidence demonstrates the serious health hazards involved in the agricultural use of alkyl-mercury compounds as fungicides in an unsophisticated rural community. Some recommendations for effective pesticide control are made.
Article
After almost two decades of decline, Ghana's mineral sector has rebounded significantly and is currently the main foreign exchange earner. Gold mining is the principal activity within the sector and accounted for 41 percent of total export earnings in 1996. This paper presents an overview of Ghana's mineral industry and covers mineral resources, production and reserves; mining investments; the role of mining in the economy; and the structure of the industry. An overview of the national mineral policy is also presented to depict the current regulatory and fiscal environment in which the industry operates. The spectacular reversal in mineral sector performance can be attributed to the adoption of World Bank recommendations in a new national mineral policy, the 1986 Minerals and Mining Law, aimed at revitalizing the sector.
Article
In this study, we investigated the extent of contamination of Hg in selected mine-impacted Ghanaian watersheds. Our results are suggestive of a major environmental problem with Hg in Ghana, with total-Hg concentrations ranging from 17 to 2000ng L^{-1} in surface water samples, and in hundreds of ppm for both soils and sediments.
Article
Previous studies in the Manoa watershed (Hawaii) have indicated significant anthropogenic enhancement of trace metals in road deposited sediment and fluvial bed sediments. This study was conducted to examine trace metal loadings with depth in soils of Manoa watershed. A total of 78 roadside (disturbed) and 10 background (control) soils were sampled at two depths for selected soil properties and for total and HCl-extractable (labile) concentrations of Al Cu, Pb, and Zn. Based on sample proximity to roads, typically <2 m, the automobile is considered the primary source of inputs. Concentration, mass loading, and mass per area enrichment ratio (MAER) data indicate that Pb was the most significantly enhanced trace metel. Labile Pb concentrations were log-normally distributed with maximum values of 2870 and 3560 mg kg-1 in topsoil and subsoil samples, respectively. Roadside labile Pb was four to five times higher than in background soils. Mass loading and MAER data indicate that subsoils were statistically more enriched in labile Cu and Pb, while Zn had similar values with depth. More than 50% of the subsoils were classified as having significant to extreme labile Pb anthropogenic signals. Trace metals in this study have undergone significant translocation, possibly through processes of colloidal transport and/or preferential flow. The environmental significance of this research is discussed in terms of potential influence of Pb mobility on ground and surface waters, and the continued contribution of high levels of labile Pb to fond surfaces with erosion of exposed subsoil layers.
Article
A technique is presented, which allows the rapid and precise determination of methylmercury in aqueous samples. The sample is first reacted with sodium tetraethylborate, to convert the nonvolatile monomethyl mercury to gaseous methylethylmercury. The volatile adduct is then purged from solution, and recollected on a graphitic carbon column at room temperature. The methylethylmercury is then thermally desorbed from the column, and analyzed by cryogenic gas chromatography with cold vapour atomic fluorescence detection. The method allows the simultaneous determination of labile Hg(II) species, through the formation of diethylmercury, and of dimethylmercury, which is not ethylated. The methylmercury detection limit is about 0.6 pg Hg, or 0.003 ng∙L−1 for a 200-mL sample. The technique has been successfully applied directly to a wide variety of freshwater samples and alkaline tissue digestates. Seawater is analyzed following a simple extraction step to separate the methylmercury from the interfering chloride m...
Article
This paper presents a table of abundances of the elements in the various major units of the Earth's lithic crust with a documentation of the sources and a discussion of the choice of units and data.
Article
We have measured Hg concentrations in one of the most remote aquatic systems in the world, Taylor Valley (∼78°S), Antarctica. These measurements, along with the previous work of Vandal et al. [1998], provide baseline concentrations of Hg, as well as an assessment of Hg speciation, in a remote aquatic environment. Dissolved Hg concentrations in the surface waters of these lakes and glacial streams range from 0.10 to 0.44 ngL−1. These values are similar to those reported from other remote locations and suggest these values represent current baseline values globally.
Article
Studies of Fe, Mn, Cu, Cr, Pb, Zn, Hg, and Cd were carried out on bed sediments collected from different parts of the south-east coast of India including coastal, river and river mouth regions. Data indicate that the concentration of all the metals considered decreases towards the coast. For example, Pb concentration at 65 km away from the coast has an average value of 50 ppm, at 25 km away from the coast is 20 ppm and along the coast is 5–10 ppm. Grain size is a major controlling factor in the distribution of heavy metals in the coastal sediments. Geoaccumulation indices calculated for these metals show that Cd is the most enriched metal followed by Pb. Other metals are at background concentrations.
Book
Historical aspects and present-day implications of the socio-economic factors involved in the mining and movement of Hg are discussed. Environmental contamination is surveyed, with detailed descriptions of international incidents of industrial pollution. Ancient and modern applications and uses in medicine are reviewed. It is concluded that problems associated with Hg contamination will continue with the increased use of fossil fuels unless drastic measures are undertaken. (JGB)
Book
This book presents in this publication information on the mineral and rock resources of Ghana. Minerals that do not exist in Ghana in commercial quantities are also treated and mention is made where they have been found in Ghana. Topics covered include the following: the importance of minerals; the geography, physiography, geology and geohydrology of Ghana; metallic minerals; non-metallic minerals; bulk c