H. F. Darko’s research while affiliated with Water Research Institute and other places

In Ghana, small-scale mining (SSM) has been carried out for many years, generating employment and income. Currently, illegal artisanal mining (“galamsey”) has impacted the environment negatively resulting in land degradation and water pollution. The government of Ghana responding to public outcry against the negative effects of “galamsey”, placed a ban on illegal small-scale mining activities in March 2017. This ban stopped both “legal” small-scale and the illegal artisanal miners from carrying out any such activity. In July 2018, this study was carried out to examine the status of water and sediment quality in 8 endemic regions of illegal mining to ascertain the outcome of the ban on the water quality of the rivers. Methodologies in the Standard Methods for the Examination of Water and Wastewater were followed. Results of the study indicated that the rivers were high in total suspended solids (TSS), turbidity and colour, suggesting inflow of wastewater from the illegal mining activities and some run-off. Colour had a strong correlation with turbidity (r = 0.95) and TSS (r = 0.94) suggesting that the pollution originates from the same sources. Low levels of metals were found in both water and sediment. However very high concentrations of Fe were detected in both water and sediment. Mercury concentrations were low in the water column but relatively higher in the sediment. A comparison of the general water quality status of the water bodies in the Pra Basin in 2013 and 2018 using the Water Quality Index (WQI) showed a marginal improvement in quality in 2018 over 2013 in the Pra Basin. The improvement of water quality in 2018 is attributable to the ban.

Artisanal small-scale mining has been part of Ghana’s history, but recent public outcry on the devastating impacts of the phenomenon on water bodies, due to expansion in the sector, has led to clamp downs by various governments on the activity. This has called for evaluation of the water quality of the South-western Rivers System, which are small-scale mining endemic areas. Thirty-five river samples were collected in July 2018 and were analyzed for physico-chemical parameters using procedures outlined in the Standard Methods for the Examination of Water and Wastewaters. The results revealed that the rivers are polluted with Fe and Cu, accompanied by very high levels of turbidity (mean = 488 NTU) and total suspended solids (TSS) (mean = 382 mg/L). NH3–N, PO4–P, BOD, and DO levels indicated mild pollution in the waters. Pollution of the rivers is attributable to impacts of artisanal small-scale mining, surface run-off as a result of high intensity rainfall, anthropogenic (indiscriminate waste disposal) and geogenic factors such as dissolution of minerals from the soil zone. It was observed that, if not strictly regulated, turbidity and TSS levels arising mainly from illegal small-scale mining activities could lead to shutdowns of a number of Ghana Water Company Limited treatment plants, leading to water supply challenges in the study area.

Recycling of e-waste using informal or crude techniques poses serious health risk not only to the workers but also to the environment as whole. It is against this background that this paper sought to measure health risk faced by informal e-waste workers from exposure to toxicants such as lead, cadmium, chromium, copper, arsenic, tin, zinc and cobalt via oral and dermal contact with bottom ash and soil. Using random sampling techniques, 3 separate sites each (where burning and manual dismantling of e-wastes are usually carried) were identified, and a total of 402 samples were collected. The samples were analysed using standard methods for chemical analysis prescribed by the American Water Works Association (AWWA). Concentrations of Pb, Cd, Cr, Cu, As, Sn, Zn and Co in bottom ash samples from location ASH1 are 5388 ± 0.02 mg/kg (Pb), 2.39 ± 0.01 mg/kg (Cd), 42 ± 0.05 mg/kg (Cr), 7940 ± 0.01 mg/kg (Cu), 20 ± 0.07 mg/kg (As), 225 ± 0.04 mg/kg (Sn), 276 ± 0.04 mg/kg (Zn) and 123 ± 0.04 mg/kg (Co), while concentrations of the aforementioned toxicants in soil samples at location ASG1 are as follows: 1685 ± 0.14 mg/kg (Pb), 26.89 ± 0.30 mg/kg (Cd), 36.86 ± 0.02 mg/kg (Cr), 1427 ± 0.08 mg/kg (Cu), 1622 ± 0.12 mg/kg (As), 234 ± 0.25 mg/kg (Sn), 783 ± 0.31 mg/kg (Zn) and 135 ± 0.01 mg/kg (Co); used as input parameters in assessing health risk faced by workers. The results of cancer health risk faced by e-waste workers due to accidental ingestion of As in bottom ash at ASH1 is 4.3 × 10⁻³ (CTE) and 6.5 × 10⁻² (RME), i.e. approximately 4 out of 1000 e-waste workers are likely to suffer from cancer-related diseases via central tendency exposure (CTE parameters), and 7 out of every 100 e-waste worker is also likely to suffer from cancer cases by reasonable maximum exposure (RME) parameters, respectively. The cancer health risk results for the other sampling sites were found to have exceeded the acceptable USEPA cancer risk value of 1 × 10⁻⁴ to 1 × 10⁻⁶ (i.e. 1 case of cancer per every 10,000 people to 1 case of cancer per every 1,000,000 people). The non-cancer health risk results for all the toxicants were higher in all the locations for both adult and children working the e-waste site. From the findings of this study, the government of Ghana has to immediately put in place policies that would address the safety of the e-waste workers as well as protect the environment.

This study evaluated cancer risk and non-cancer human health hazard from exposure to the toxicants such as As, Cu, Pb, Zn, Mn, and CN in water from a southwestern river system in Ghana that drains through gold mining areas, using 108 water samples collected with random sampling techniques and analyzed in accordance with standard methods of chemical analysis outlined by the U.S. Environmental Protection Agency (USEPA). The concentrations of Cu and Zn were within World Health Organization and USEPA guideline values; Mn, free cyanide, As, and Pb values in most cases either exceeded USEPA and WHO values or both. The concentrations of the toxicants were used as input parameters in the cancer and non-cancer study that was conducted in line with USEPA risk assessment guidelines. The results of As cancer health risk revealed higher risk cases in two locations (Potroase and Dominase); non-cancer health risk for As was higher in 10 of the 14 locations, with other metals being of health concern at few locations in the study area. In conclusion, the findings of this study hold several policy implications as residents of mining communities still depend on these water bodies as their source of drinking water.

The Weija Reservoir has a high algal content which has posed water quality problems in the reservoir for a long time. Chlorophyll-a has been determined in water samples from the surface (0–10 cm) of the Weija Reservoir, collected at 3 different sites in the Reservoir from 2005 to 2008 at bi-monthly intervals. Chlorophyll-a concentrations were measured to determine its impact on the water quality of the reservoir, assess levels of eutrophication in the reservoir, and suggest ways of mitigating pollution in the reservoir. Chlorophyll-a concentrations in the reservoir were found to be high, ranging from 1.00 – 7.46 mg/m3 in 2005, 8.75 – 114 mg/m3 in 2006, 2.69 – 60.7 mg/m3 in 2007, and 18.4 – 106 mg/m3 in 2008, respectively. The values indicate high algal biomass in the reservoir since water bodies with low levels of nutrients (e.g. oligotrophic lakes) have low levels of chlorophyll-a (< 2.5 mg/m3) whereas waters with high nutrient contents (especially those classed as eutrophic) have high levels of chlorophyll-a (5-140 mg/m3). These levels of chlorophyll-a were then used to determine the trophic status of the Weija Reservoir. Indications are that the Weija Reservoir is a hypereutrophic lake. Chlorophyll-a concentrations showed positive correlation with Total Phosphate (r = 0.21), but negative correlation with ammonium concentrations (r = -0.24). Chlorophyll-A concentrations also showed moderately high correlations with DO (r = 0.54), TSS (r = 0.60), and COD (r = 0.60), at the 95 % level. The high chlorophyll-a concentrations could impair the aesthetic values as well as contaminate the reservoir waters, and this may be one of the reasons why water from the Weija Reservoir has unpalatable taste, consequently, compounding the high cost of potable water production at Weija.

Groundwater is a vital natural resource for provision of potable water in both the urban and rural environment. Pollution of groundwater may come from urbanization, industrial development, agricultural and mining activities, and also from natural sources. The soil strata have the capacity to attenuate contaminants in the water passing through it. The chemical composition of groundwater is an indicator of its suitability as a source of water for human and livestock consumption, and for many other purposes. In order to ensure safe drinking water for the people in the Volta Region of Ghana, the CommunityWater and Sanitation Agency (CWSA) in 2003 contracted the CSIR Water Research Institute to carry out groundwater quality assessment of boreholes that had been dug for the rural communities in the Volta Region of Ghana. Major water quality parameters like pH, conductivity, alkalinity, hardness, Ca2+, Cl−, NO3-N, NO2-N, SO42− , SiO2, PO4-P, NH3-N, were determined. Most of the parameters were within the WHO guide values for drinking water. Some parameters, however, gave occasional extreme values in few places. For example, an extreme value of 475 mg/L in NO3-N, far exceeding the WHO guideline value of 10 mg/L, was recorded in a station in the Akatsi district, and similar values elsewhere. The pH values were very satisfactory, ranging from 5.13 to 8.37 for all the three districts in question. Only very few pH values fell below pH 6.