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Five heavy metals in propagules of ten mangrove species of China
Abstract
Five heavy metals in the propagules of 10 mangrove species in China have been investigated. The results revealed that the
levels of five heavy metals in most of the propagules were lower than the background levels of the soil. The levels of copper,
manganese, zinc, cadmium, and lead in the propagules varied at about 2.1–7.8 μg/g, 3.9–28.0 μg/g, 5.7–60.0 μg/g, 0.014–0.057
μg/g, and 0.018–0.038 μg/g, respectively. On average, the levels of five heavy metals were in the order Zn > Mn > Cu > Cd
> Pb. The biological absorption coefficients were 0.02–1.30 for copper, manganese, zinc, and cadmium and about 0.0007–0.0020
for lead in propagules, showing the following order: Zn > Cd > Cu > Mn > Pb. The above results indicate that the five heavy
metals have low accumulation in most of the propagules of 10 mangrove species and are at safe levels for the effective utilization
of mangrove resources.
... Therefore, mangrove wetlands are being used as potential waste treatment facilities (Tam 2006). Other than many laboratory experiments which focused on the physiological and molecular features of individual species, a large amount of field work has been conducted to monitor pollution in mangrove plants (Zheng et al. 1996a, b;Zheng and Lin 1996a, b;Lian et al. 1999;Ding et al. 2011 (Fig. 2). Accumulation and distribution of metal elements in mangrove plants might be dependent on the levels of metal elements in forest sediments (Xie et al. 2010). ...
... Biosediment accumulation factors (BSAFs) are defined as heavy metal concentrations in tissues divided by the concentrations in sediments. The BSAFs for each element might vary, but most values were less than 1 Wang et al. 1997;Ong Che 1999;Zan et al. 2002;Wang 2011 (Zan et al. 2002); and Zn (0.2-1.3)>Cd (0.4-1.2)>Cu (0.07-0.57)>Mn (0.02-0.21)>Pb (<0.01) for propagules of ten mangrove species (Lian et al. 1999). On the whole, mangrove plants tend to accumulate limited heavy metals. ...
... Therefore, mangrove wetlands are being used as potential waste treatment facilities (Tam 2006). Other than many laboratory experiments which focused on the physiological and molecular features of individual species, a large amount of field work has been conducted to monitor pollution in mangrove plants (Zheng et al. 1996a, b;Zheng and Lin 1996a, b;Lian et al. 1999;Ding et al. 2011 (Fig. 2). Accumulation and distribution of metal elements in mangrove plants might be dependent on the levels of metal elements in forest sediments (Xie et al. 2010). ...
... Biosediment accumulation factors (BSAFs) are defined as heavy metal concentrations in tissues divided by the concentrations in sediments. The BSAFs for each element might vary, but most values were less than 1 Wang et al. 1997;Ong Che 1999;Zan et al. 2002;Wang 2011 (Zan et al. 2002); and Zn (0.2-1.3)>Cd (0.4-1.2)>Cu (0.07-0.57)>Mn (0.02-0.21)>Pb (<0.01) for propagules of ten mangrove species (Lian et al. 1999). On the whole, mangrove plants tend to accumulate limited heavy metals. ...
China's rapid economic growth has been accompanied by increasing environmental pollution. Mangrove ecosystems are now facing greater pollution pressures due to elevated chemical discharges from various land-based sources. Data on the levels of heavy metals and organic pollutants in mangrove compartments (sediments, plants, zoobenthos, and fish) in China over the past 20 years have been summarized to evaluate the current pollution status of the mangrove ecosystem. Overall, the Pearl River and Jiulong River estuaries were severely polluted spots. Concentrations of Cu, Zn, Cd, and Pb in mangrove sediments of Guangdong, Fujian, and Hong Kong were higher than those from Guangxi and Hainan. The pollution status was closely linked to industrialization and urbanization. The highest concentrations of polycyclic aromatic hydrocarbons (PAHs) were found in mangrove sediments from Hong Kong, followed by Fujian and Guangdong. Mangrove plants tend to have low-enriched ability for heavy metals and organic pollutants. Much higher levels of Pb, Cd, and Hg were observed in mollusks.
... They also provide erosion mitigation and stabilization for adjacent coastal landforms (Harty, 1997). In a plant-soil system, strong absorption and fixation of heavy metals by soil can easily cause residual accumulation in the soil, resulting in over-absorption of heavy metals by growing plants (Lian et al., 1999;Rajkumar et al., 2007). These plant products are harmful to the health of humans (Defew et al., 2005). ...
... These plant products are harmful to the health of humans (Defew et al., 2005). For this reason, it is important and necessary to study the relation between the content of heavy metals in soil and the absorption and accumulation by plants (Lian et al., 1999). ...
The accumulative partitioning of Pb and Cu in the Rhizophora apiculata was studied randomly in the Setiu mangrove forest, Terengganu. Samples of leaves, barks and roots were collected randomly from the selected studied species. Sediments between the roots of the sampled mangrove plants were also collected. The results from analysis for Rhizophora apiculata shows that the concentration of Pb and Cu were accumulated higher in root tissue compared to bark and leaf tissue but lower than surrounding sediment level. The average concentration of Cu for Rhizophora apiculata in leaf, bark, root and sediment was 2.73, 3.94, 5.21 and 9.42 mg I(-1), respectively. Meanwhile, the average concentration of Pb in leaf, bark, root and sediment was 1.43, 1.38, 2.05 and 11.66 mg l(-1), respectively. Results of concentration factors (CF) show that the overall the concentration of Pb and Cu were accumulated much higher in roots system of Rhizophora apiculata.
... The results of the reported study were compared with different published papers at the diverse sites of five countries i.e. Australia (Saenger et al., 1990;MacFarlane, 2002;Alongi et al., 2003;MacFarlane et al., 2003), China (Peng et al., 1997); Lian et al., 1999); Li et al., 2016), Malaysia (ELTurk et al., 2018), Hong Kong (Chen et al., 2003) and Pakistan (Zahir et al., 2004). First of all, copper was compared with the studies of Australia, China, Hong Kong, Malaysia and Pakistan. ...
The objectives of this study are to assess the spatial distribution and the bio-accumulation of heavy metals (Cr,
Cu, Ni, Pb, and Zn) in the marine sediments and the mangroves (Avicennia marina) at Yanbu Red Sea, Saudi
Arabia. Cr, Cu, Ni, Pb and Zn concentrations in the sediments were 14.9–289, 17.2–217.2, 27.3–241.8,
11.5–111.3 and 48.8–511.5 μg g−1, respectively. The values in the roots were 16.3–40.5, 16.8–37.3, 17.2–38.2,
2.4–6.7 and 31.5–62.4 μg g−1 while the concentrations in the leaves were 14.2–50.1, 18.1–40.2, 16.1–56.3,
2.3–9.9 and 36.8–84.9 μg g−1, respectively. The pollution load was estimated in terms of the different ecological
pollution indices such as geo-accumulation, contamination factors and pollution index, potential ecological risk,
potential toxicity response indices and biological concentration factors. Briefly, the coastal area of the Red Sea at
Yanbu is contaminated with heavy metals, which may affect the quality of the aquatic lives and human beings.
... However, higher Fe (4593 μg/g) and Mn (1281 μg/g) were observed in B. racemosa, Cu (101.70 μg/g) in A. officinalis and Zn (135.70 μg/g) in Acanthus ilicifolius. Apart from the mangroves leaves, Lian et al. (1999) investigated the micronutrients (Cu, Mn and Zn) in propagules of ten different mangrove species in Dongzhai Harbor National Nature Reserve of Hainan Island of China. They reported that elements content in propagules are species specific and Cu, Mn and Zn content in the propagules of different mangrove species ranged from 2.10 to 7.80 μg/g, 3.90 to 28 μg/g and 5.70 to 60 μg/g, respectively. ...
... However, higher Fe (4593 g/g) and Mn (1281 g/g) were observed in B. racemosa, Cu (101.70 g/g) in A. officinalis and Zn (135.70 g/g) in Acanthus ilicifolius. Apart from the mangroves leaves, Lian et al. (1999) investigated the micronutrients (Cu, Mn and Zn) in propagules of ten different mangrove species in Dongzhai Harbor National Nature Reserve of Hainan Island of China. They reported that elements content in propagules are species specific and Cu, Mn and Zn content in the propagules of different mangrove species ranged from 2.10 to 7.80 g/g, 3.90 to 28 g/g and 5.70 to 60 g/g, respectively. ...
... The partitioning of metals in sediments into geochemical fractions, i.e., exchangeable (F1), carbonate-bound (F2), Fe-Mn oxide-bound (F3), organic matter-bound (F4), and residual fractions (F5), is deeply related to their bioavailability and toxicity to aquatic organisms. Therefore, information on metal concentrations in the individual fractions is necessary to understand their bioavailability and potential toxicities (Lian et al. 1999;Naji et al. 2010;Guo et al. 2015). ...
Due to proximity to the urban and industrial areas, coastal environments of the Osaka Bay have been continuously polluted with the human activities. Coastal sediments are known as large pool of contaminants including heavy metals. The Osaka Bay is no exception. However, recent information regarding the distributions, geochemical speciations, and risk evaluations of metals is limited for coastal sediments in the Bay. Therefore, we investigated the distributions, geochemical speciations, bioavailabilities, and conducted risk evaluations of the heavy metals, such as cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn) in sediments collected from 25 sites of the urban coastal environment of Osaka Bay, Japan. We observed high concentrations of Zn (76–967 mg/kg dry weight; DW) followed by Cu (not detected; ND-399 mg/kg DW), Pb (ND-73 mg/kg DW), and Cd (0.2–2.9 mg/kg DW). A considerable fraction of Cd was exchangeable (ND-0.4 mg/kg DW) and carbonate-bound (0.03–0.4 mg/kg DW). Cu occurred predominantly in the organic material-bound fraction (ND-348 mg/kg DW). Both Pb and Zn occurred predominantly in the Fe-Mn oxide fraction, with concentration ranges of ND-41 mg/kg DW and 24–277 mg/kg DW, respectively. Comparison with the effect range low (ERL) and effect range median (ERM) revealed that Cd, Cu, and Zn contribute potential biological toxicities to the sediments of Osaka Bay. High bioavailable concentrations of Cd and Zn may have ecotoxicological significance, because these metals are potentially highly available, especially to the benthic organisms.
... These sediments bound metals can be taken up by rooted aquatic macrophytes and other aquatic organisms [8]. In a plant-soil system, strong absorption and fixation of heavy metals by soil can easily cause residual accumulation in the soil, resulting in over-absorption of heavy metals by the growing plants [9][10]. The uptake of heavy metals by plants are passive, and its translocation from roots to other plant organs is generally low [11][12]. ...
Mangrove swamps have unique biogeochemical interaction between the plant and the underlying sediments. The bioactive heavy metals; Zn, Cu, Fe, Mn, Pb, Ni, Cd and Co were measured using Atomic Absorption Spectrophotometer (AAS) in the bulk sediment samples and the fine fractions; 125µ, 63µ and <63µ and slack water as well as different parts of the Avicennia marina mangrove (fruits, leaves and roots) collected from 9 mangrove swamps at the nearshore zone of the Red Sea. The average percentage of the fine sediment group (125µ + 63µ + <63µ) was varied between 18.78% and 51.22% from the total sediments with recognized occurrences for the fractions 125µ and 63µ. The bulk sediments recorded the highest averages of the bioactive Zn (69.91µg/g), Mn (186.91µg/g) and Ni (19.49µg/g), the fraction 125µ recorded the highest average of Pb (16.92 µg/g), while <63µ fraction showed the highest averages of Cu and Fe (26.45 and 2744.84µg/g). In the mangrove stands, the highest averages of Zn and Cu were recorded in fruits (Avs. ≈116.41 and 15.20 µg/g), Mn in leaves (Av. ≈ 43.72 µg/g) and the highest Pb was recorded in roots (Av. ≈ 30.14 µg/g). The bio-accumulation sequence of heavy metals in the fruits and roots was Fe>Zn>Pb>Cu>Mn>Ni and in leaves was Fe>Zn>Mn>Pb>Cu>Ni. The low contents heavy metals recorded in the slack water of the mangrove swamps attributed to the reducing nature of the underlying sediments that accumulate the heavy metals in insoluble sulphide forms. The effects of the elevated metal contents in the fruits, leaves and the roots of A. marina were at the studied forests were reflected in the ramified and shorten roots, pale yellowish colour and reduction the leaves number in many of the mangrove stands.
... A. halimus typically accumulates low concentrations of Pb and Cd, but has high biomass, making it a viable candidate for use in phytoextraction in arid, saline soils (Manousaki and Kalogerakis 2009). The mangrove B. sexangula and Ceriops decandra are used as biomarker or biomonitor to heavy metal pollution (Gupta and Chakrabarti 2013) and the mode of accumulation was in the order of Cd [ Pb [ Hg (Lin et al. 1997;Lian et al. 1999). The salt-induced enhancement of Cd tolerance opens the possibility of using S. portulacastrum for Cd phytoextraction (Wali et al. 2015). ...
Heavy metals are among the major pollutants from anthropogenic inputs that reach mangrove ecosystem by urban and agricultural runoff, industrial effluents, boating, mining and other processes. To minimize the detrimental effects of heavy metal exposure and their accumulations, plants in general have evolved biological detoxification mechanisms, which include avoidance or exclusion, excretion and accumulation. To protect the cellular components from oxidative damage by heavy metal contamination, biological systems have developed enzymatic and non-enzymatic antioxidant mechanisms. Another detoxification mechanisms produced in plants are osmoprotectants, which are the compatible solutes which maintain a favourable water potential gradient and protect cellular structures from toxic ions. Besides these mechanisms, another heavy metal detoxification system in plants involves the chelation of metals by metal binding molecules like metallothioneins (MTs) and phytochelatins (PCs). To limit the heavy metal toxicity from mangrove ecosystem, it was found that phytoremediation is a most useful technology where in plants are used to remove pollutants from the environment and it is considered as a comparatively new, low-cost and highly promising technology for the remediation of heavy metal. Rhizofiltration, phytovolatilization, phytoextraction and phytostabilization are the important phytoremediation techniques. Among these phytoextraction and phytostabilization are found highly important in the case of mangroves and are promising means of phytoremediation.
... In a plant-soil system, strong absorption and fixation of heavy metals by soil can easily cause residual accumulation in the soil, resulting in over-absorption of heavy metals by growing plants (Lian et al., 1999;Ravikumar et al., 2007). These plant products are harmful to the health of humans (Defew et al., 2005). ...
The study deals with the accumulation of Pb, Zn and Cd in an important mangrove species, Avicennia marina (Forssk.) Vierh., in the Vamleshwar mangrove ecosystem, near Narmada estuary, West coast of Gujarat, India with height differences of 0.5, 1.5, 2.5 meters and carried out under field conditions during October, 2009. The site was located on 21�30�11.55�� N latitude and 72�43�53.68�� E longitude. Mangrove receives heavy metal pollution from upstream areas of Narmada estuary and highly populated settlements. However, little is known about the capacity of mangrove plants to take up and store heavy metals in them. Water, sediment and plant parts such as roots, stems and leaves were analyzed for finding the trace metal accumulation of different height groups by Inductive Coupled Plasma Analyser (ICPA). Amount of the content of metals found in the water, sediment and plant parts were in the order of Pb>Zn>Cd. The average contents of heavy metals in the waters were 57.83 mg l-1 for Pb, 3.89 83 mg l-1 for Zn and 0.42 mg l-1 for Cd. It was observed that the average contents of Pb (73.6 mg l-1), Zn (8.1 mg l-1) and Cd (0.73 mg l-1) in the sediments were below the critical soil concentrations. The concentrations of heavy metals in different parts of Avicennia marina were in the order Roots>stem>leaf except for Cd, but Cd found higher in leaf. The ranges of the content of heavy metals in plants were 18.5-102.2 mg l-1 for Pb, 3.5-19.5 mg l-1 for Zn and 0.2-4.1 mg l-1 for Cd. The concentrations of all heavy metals in Avicennia marina except Pb were falling within the normal range and were much more in the plants have the highest height. The present study has shown the potential of Avicennia marina as a phytoremediation species for selected heavy metals in many mangrove ecosystems.
... The average concentration of heavy metal in the plants declined according to this sequence: Zn>Cu>Pb. The high concentration of Cu and Zn suggested an active uptake and possibly storage, because they were the essential elements for the growth of plants (Lian et al. 1999, MacFarlane & Burchett 2002, Che 1999. Cu components are ascorbic acid oxidase, tyrosinase, monoamine oxidase, uricase, and cytochrome oxidase that plants require (Che 1999) while Zinc is an essential component of the numerous enzymes, reparation enzyme activator, and biosynthesis of plant growth hormone (Macfalance & Burchett 2002). ...
The concentration of heavy metals in mangrove sediments and stems of some mangrove species in Surat Thani province, Thailand were measured, including essential elements (such as Cu and Zn) and non-essential elements (Pb). Physical-chemical properties (e.g., soil texture, pH, CEC, and OM) were analyzed by using the standard method, while heavy metals were analyzed by using an atomic absorption spectrometer. The results show that the sediment samples, have ranges of measured concentration expressed in mg kg-1 dry weight, as follows: 2.90-13.75 of Cu, 8.15-25.99 of Pb, and 7.50-46.43 of Zn, while stem samples 0.001-0.148 µg.g-1 of Cu, 0.10-0.83 µg.g-1 of Pb, and 0.57-9.77 µg.g-1 of Zn. The highest measured heavy metal values were found in Sonneratia caseolaris and Avicennia alba. The average value of heavy metals accumulated in the stems and sediments of some species were found to have significant positive correlations and some statistically non-significant (p< 0.05) correlations of heavy metal concentrations (Cu, Pb, and Zn). From this study, it can be concluded that the factors responsible for the accumulation of heavy metal were found to be the organic matter, cation exchange capacity, and the texture of the sediment.
... The toxicity and bioavailability of heavy metals were not only related to their total contents, but also to their speciation [67]. The reducible fraction referred to metal associated with Fe and Mn oxides was reducible, which might be released when subjected to more reducing conditions. ...
Overlying water, sediment, rhizosphere sediment and mangrove seedlings in the Futian mangrove forest were analyzed for heavy metals. The results showed that mangrove plant acidified sediment and increased organic matter contents. Except for chromium (Cr), nickel (Ni) and copper (Cu) in Aegiceras corniculatum sediment, heavy metals in all sediments were higher than in overlying water, rhizosphere sediment and mangrove root. Heavy metals in Avicennia marina sediments were higher than other sediments. The lower heavy metal biological concentration factors (BCFs) and translocation factors (TFs) indicated that mangrove plant adopted exclusion strategy. The geo-accumulation index, potential ecological risk index and risk assessment code (RAC) demonstrated that heavy metals have posed a considerable ecological risk, especially for cadmium (Cd). Heavy metals (Cr, Ni, Cu and Cd) mainly existed in the reducible fractions. These findings provide actual heavy metal accumulations in sediment-plant ecosystems in mangrove forest, being important in designing the long-term management and conservation policies for managers of mangrove forest.
... According to several benchmark studies from the Asian region, the mangrove system is severely polluted by heavy metals including Mercury (Hg), Lead (Pb), Tin (Sn), Cobalt (Co), Copper (Cu), Chromium (Cr), Cadmium (Cd), Manganese (Mn), Zinc (Zn), Nickel (Ni) and Iron (Fe) (Tam and Wong, 1995;Lian et al., 1999;Sarangi et al., 2002;Tam and Wong, 2000;Cuong et al., 2005;Agoramoorthy et al., 2008;Nazli and Hashim, 2010). Some of the heavy metals including Hg, Cd, Ni, Pb, Cu, Cr, and Zn are lethal to several marine organisms even in low concentration (Davies, 1978). ...
... The relatively high TF for Mn may also be enhanced by elevated natural levels and higher bioavailability of this metal in estuarine sediments compared to other trace elements resulting in a higher uptake potential (Lacerda et al., 1999;Gueiros et al., 2003). Other studies have reported leaf BCFs of Mn commonly greater than unity in mangrove plants and typically range between 1 and 10 in most plant species (Lacerda et al., 1999;Lian et al., 1999). Low Fe BCFs may be due to a high natural abundance and/or formation of Fe plaques around root surfaces that may have hindered its translocations to aerial tissues (Baker, 1981;Taylor, 1987). ...
... They also provide erosion mitigation and stabilization for adjacent coastal landforms [8]. In a plant-soil system, strong absorption and fixation of heavy metals by soil can easily cause residual accumulation in the soil, resulting in over-absorption of heavy metals by growing plants [9,10]. ...
Abstract: The accumulation of heavy metals in the Avicennia marina was studied in the Bhira village mangrove forest, Miani Hor Balochistan, Pakistan. Samples of leaves, stem and roots were collected randomly from the selected specie (Avicennia marina). The study site is receiving continuous amount of heavy metals from effluent and discharge of different sources. The concentrations of heavy metals was in decreasing order Fe > Cd > Pb > Hg in all three parts (leaves, stem and roots) of the Avicennia marina. The average concentration of Fe was 6.45 µg g-1, Cd 0.97 µg g-1 and Pb 0.71 µg g-1 in mangrove plant Avicennia marina. The situation reflects the needs for continuous monitoring of the heavy metals in the mangrove plant forest.
... In a plant-soil system, strong absorption and fixation of heavy metals by soil can easily cause residual accumulation in the soil, resulting in over-absorption of heavy metals by growing plants (Lian et al., 1999;Ravikumar et al., 2007). These plant products are harmful to the health of humans (Defew et al., 2005). ...
The study deals with the accumulation of Pb, Zn and Cd in an important mangrove species, Avicennia marina (Forssk.) Vierh., in the Vamleshwar mangrove ecosystem, near Narmada estuary, West coast of Gujarat, India with height differences of 0.5, 1.5, 2.5 meters and carried out under field conditions during October, 2009. The site was located on 21°30´11.55´´ N latitude and 72°43´53.68´´ E longitude. Mangrove receives heavy metal pollution from upstream areas of Narmada estuary and highly populated settlements. However, little is known about the capacity of mangrove plants to take up and store heavy metals in them. Water, sediment and plant parts such as roots, stems and leaves were analyzed for finding the trace metal accumulation of different height groups by Inductive Coupled Plasma Analyser (ICPA). Amount of the content of metals found in the water, sediment and plant parts were in the order of Pb>Zn>Cd. The average contents of heavy metals in the waters were 57.83 mg l-1 for Pb, 3.89 83 mg l-1 for Zn and 0.42 mg l-1 for Cd. It was observed that the average contents of Pb (73.6 mg l-1), Zn (8.1 mg l-1) and Cd (0.73 mg l-1) in the sediments were below the critical soil concentrations. The concentrations of heavy metals in different parts of Avicennia marina were in the order Roots>stem>leaf except for Cd, but Cd found higher in leaf. The ranges of the content of heavy metals in plants were 18.5-102.2 mg l-1 for Pb, 3.5-19.5 mg l-1 for Zn and 0.2-4.1 mg l-1 for Cd. The concentrations of all heavy metals in Avicennia marina except Pb were falling within the normal range and were much more in the plants have the highest height. The present study has shown the potential of Avicennia marina as a phytoremediation species for selected heavy metals in many mangrove ecosystems.
... The highest concentrations of Mo, V, Th, Ga and Ni are 20–80 times higher than the lowest ones. Our results compare well to those of Lian et al. [31] who reported a similar concentration gradient for Zn, Mn, Cu, Cd and Pb for ten different mangrove species in a nearby location. The annual concentration of total REEs varies from 0.024 to 0.173 ppb, with an average of 0.066 ± 0.035 ppb. ...
Annual variations from 1982 to 1999 of a wide range of trace elements and reconnaissance Pb isotopes (Pb-207/Pb-206 and Pb-208/Pb-206) were analyzed by solution ICP-MS on digested ash from mangrove Rhizophora apiculata, obtained from Leizhou Peninsula, along northern coast of South China Sea. The concentrations of the majority of elements show a weak, declining trend with growth from 1982 to 1999, punctuated by several high concentration spikes. The declining trends are positively correlated with ring width and negatively correlated with inferred water-use efficiency, suggesting a physiological control over metal-uptake in this species. The episodic metal concentration-peaks cannot be interpreted with lateral movement or growth activities and appear to be related to environmental pollution events. Pb isotope ratios for most samples plot along the 'Chinese Pb line' and clearly document the importance of gasoline Pb as a source of contaminant. Shale-normalised REE + Y patterns are relatively flat and consistent across the growth period, with all patterns showing a positive Cc anomaly and elevated Y/Ho ratio. The positive Ce anomaly is observed regardless of the choice of normaliser, in contrast to previously reported REE patterns for terrestrial and marine plants. This pilot study of trace element, REE + Y and Pb isotope distribution in mangrove tree rings indicates the potential use of mangroves as monitors of historical environmental change. (c) 2006 Elsevier B.V. All rights reserved.
... The heavy metals of greatest ecotoxicological concern are copper (Cu), lead (Pb), and zinc (Zn), due to their prevalence in estuarine sediments (MacFarlane, 2002). Mangrove is a woody community that grows in tropical and subtropical zones of the world (Lian et al., 1999). It also possesses a great tolerance to relatively high levels of heavy metal pollution (Peters et al., 1997). ...
In this paper, we aimed to assess the roles of metallothioneins (MTs) in heavy metal tolerance by analyzing the expression level of BgMT2 in leaves of Bruguiera gymnorrhiza in response to heavy metals. Eight-month-old B. gymnorrhiza seedlings were exposed to different concentrations of zinc (Zn), copper (Cu) or lead (Pb) for 1, 3 and 7 d. A Real-time quantitative PCR protocol was developed to directly evaluate the expression of BgMT2, using 18S rRNA as a reference gene. Real-time quantitative PCR analysis demonstrated BgMT2 mRNA expression was regulated by Zn, Cu and Pb, but the regulation pattern was different for the three metals tested. Significant increase in the transcript level of BgMT2 was also found in response to Zn, Cu and Pb in some experimental conditions. Our results confirm that BgMT2 gene is involved in the regulation of Zn, Cu and Pb in B. gymnorrhiza leaves.
This research aimed to investigate the quality of coastal surface waters and the levels of trace metals in the leaves of Rhizophora mangle L. in the Tinharé-Boipeba APA, Baixo Sul da Bahia, Brazil. The physical-chemical variables were measured in situ with the aid of a multiparameter probe and samples of Rhizophora leaves were collected at 10 sampling points for biometric, visual diagnosis and trace metal analysis (F-AAS). The results of the OD analyzes revealed changes in water quality (70% of the sampling points), associated with forms of land occupation and failures in environmental sanitation. Cluster analysis allowed the classification of samples into biogeochemical groups, according to trace element content and leaf biometry. This multivariate analysis suggested that the variation in leaf area can be explained, in part, by the levels of Cu and Zn, in addition to other ecological-environmental factors different from those investigated. The levels of trace metals in the leaves were considered normal and non-toxic and the levels of trace metals in the sediments of this APA did not characterize a polluted area, however water pollution demands coastal management, improvements in sanitation and environmental monitoring, and biomonitoring.
We present a viewpoint regarding the prospects in Sri Lanka (a tropical island nation) to depend on mangroves in the remediation of heavy metal laden coastal environments. Sri Lanka has a rich array of lagoons and estuaries (total extent of 1580.17 km²) with ideal brackish water habitats to allow mangrove proliferation and for more restoration works. Furthermore, our estimates of Total Potential Ecological Risk (PER < 150) indicate that ecological risk from metallic contamination of coastal sediments is low, which means mangrove ecosystems would be ideal natural treatment systems for such low polluting environments (but as final cum tertiary treatment systems only). Mangroves are neither metal hyperaccumulators nor good phytoremediators (no ability to take up more than 5000 mg/kg dry weight of a given metal or exhibit a bioconcentration factor ≥ 1000), which means not very effective for high polluting environments.
Heavy metal pollution in the coastal environment is a corollary of anthropogenic accomplishments. It is a grave threat to ecosystem health as heavy metals are among important pollutants and their effects on mangroves have been extensively acknowledged. Mangroves are linked to multiple ecosystem services and play a vital role in the natural purification of polluted water. Mangroves are among the most threatened tropical and subtropical ecosystems, under soaring pollution pressure, especially heavy metals and organic contaminants. This book chapter highlights heavy metal level in the soil environment, its absorption, accumulation, and dynamics in the mangrove forest ecosystem. Effective ways of heavy metals’ removal from the coastal environment through remediation techniques are also focused. It is eco‐friendly, eco‐sustainable, and potentially cost‐effective. Phytoremediation technology not only removes the pollutants but also promotes biodiversity and coastal stability through mangrove regeneration or plantation in coastal areas.
Culture-based studies have recovered fungal endophytes from numerous plant hosts, while direct examination of sporulating cultures has enabled identification. However, many endophytes cannot be identified due to the fact that they only form mycelia sterilia in culture. Although next generation sequencing (NGS), as well as ITS sequence analyses have been used to identify endophytes, identification is still rudimentary. In this study, we isolated fungal endophytes from Rhizophora apiculata in Thailand and established how many can be identified to species level based on ITS sequence data. Endophytic fungi were isolated from leaves, petioles and aerial roots of R. apiculata in four provinces of Thailand. One hundred and fifty four isolates were obtained and initially grouped into 20 morphotypes based on cultural characteristics. Nine were sporulating morphotypes, which were assigned to seven genera (Colletotrichum, Diaporthe, Hypoxylon, Neopestalotiopsis, Neodevriesia, Pestalotiopsis and Phyllosticta), and eleven morphotypes were non-sporulating mycelia sterilia. Sequence similarity comparison and phylogenetic analysis of the ITS regions were further used to identify taxa. While ITS sequence data is reliable to assign isolates at the generic rank, and can be useful to identify taxa to species level in a small number of fungal genera, it cannot generally be used to determine specific species in most genera. ITS analysis classified 30 representative isolates into 20 taxonomic units residing in 15 known genera:
Mangrove swamps have unique biogeochemical interaction between the plant and the underlying sediments. The bioactive heavy metals; Zn, Cu, Fe, Mn, Pb, Ni, Cd and Co were measured using Atomic Absorption Spectrophotometer (AAS) in the bulk sediment samples and the fine fractions; 125 µ, 63 µ and <63 µ and slack water as well as different parts of the Avicennia marina mangrove (fruits, leaves and roots) collected from 9 mangrove swamps at the nearshore zone of the Red Sea. The average percentage of the fine sediment group (125 µ + 63 µ + <63 µ) was varied between 18.78% and 51.22% from the total sediments with recognized occurrences for the fractions 125 µ and 63 µ. The bulk sediments recorded the highest averages of the bioactive Zn (69.91 µg/g), Mn (186.91 µg/g) and Ni (19.49 µg/g), the fraction 125 µ recorded the highest average of Pb (16.92 µg/g), while <63 µ fraction showed the highest averages of Cu and Fe (26.45 and 2744.84 µg/g). Low heavy metals recorded in slack water. In the mangrove stands, the highest averages of Zn and Cu were recorded in fruits (Avs. ≈116.41 and 15.20 µg/g), Mn in leaves (Av. ≈ 43.72 µg/g) and the highest Pb was recorded in roots (Av. ≈ 30.14 µg/g). The bio-accumulation sequence of heavy metals in the fruits and roots was Fe>Zn>Pb>Cu>Mn>Ni and in leaves was Fe>Zn>Mn>Pb>Cu>Ni. The effects of the elevated heavy metal contents in the fruits, leaves and the roots of A. marina were reflected in the ramified and shorten roots, pale yellowish colour and reduction the leaves number in many of the mangrove stands.
Extensive excavation of mangrove soils for aquaqulture ponds without correct knowledge and technique leads to the disturbance of acid sulfate soils (ASS) due to exposure of iron sulfide to air. This condition has been recorded in many places, particularly in southeast Asia, where the disturbance of ASS generates numerous environmental problems, such as: poor soil and water quality, reduction of aquaculture The study used three replications in subsurface soils near roots, and in the surface layer for some variables. The variables examined include pH, pHfox, redox potential, Titratable Actual Acidity (TAA), Titratable Potential Acidity (TPA), Titratable Sulfidic Acidity (TSA), water-soluble sulfate, HCl extractable sulfur (SHCl) or KCl extractable sulfur (SKCl), Peroxide Sulfur (SP), Peroxide oxidisable sulfur (SPOS), pyrite, organic content, grain size, total metal and metal fractionation. The density, establishment and the growth of Rhizophoraceae were also determined.
Both the experimental and field study demonstrated that the general geochemical condition required by mangrove seedlings are: higher pH and pHfox, and a reducing environment. Compared to the existing acidity (TAA) and other associated properties that count for the existing acidity level, such as water-soluble sulfate, extractable sulfur, exchangeable Al and Fe, the amount of potential acid (TPA and TSA) and pyrite on surface soils strongly correlated with the acidity, density, establishment and growth of the seedlings in the field study area. Higher amounts of potential acidity, including pyrite in surface soils, provided higher opportunities to oxidise in oxidative environments, which then release water-soluble sulfate, extractable sulfur, and exchangeable Al into subsurface soils, decrease pH and pHfox, and affect the density, establishment and growth of mangrove seedlings in the field study area.
The experimental study showed that the number of seedlings survived in non-ASS environment was higher compared to that in ASS environments. Lower sulfate and total extractable sulfur provided a good environment for mangrove seedlings to live under the non-ASS experimental environments. However, measured sulfur species as a single factor did not directly affect the density, establishment and growth of the seedlings in the field area. Sulfide correlates negatively to the establishment and growth of the seedlings. The type of environments (non-ASS and ASS) did not significantly affect the values of either the seedlings‘ total fresh length or their root length in the experiment at work. Mangrove seedlings can still grow and survive in high acidity but with lower values of density, establishment, and relative growth rate.
The concentration of metals in the environment influenced the concentration of metals in root tissues of Rhizophora stylosa seedlings. However, increasing concentration of metals (Fe, Al, Ni and Cu due to ASS disturbance in both experiment and field studies as well as addition of Ni and Cu in the experimental study did not increase BCF values. The selective mechanisms production, death of vegetation and aquatic life, and more.
ASS is a stress factor that is responsible for the failure of some mangrove restoration projects. However, there is evidence that natural revegetation of mangroves has occurred in some abandoned ponds. Available published papers on the geochemical factors that affect the success or failure of rehabilitation in ASS areas are very few, and this makes it difficult to achieve successful rehabilitation. Geochemical studies of mangrove rehabilitation in ASS environments are essential, since different areas may have different geochemical conditions. Additionally, the interactions among geochemical factors in ASS environments are complex and can affect the response of mangrove seedlings.
The establishment of mangrove seedlings in ASS environments would deal with several potential problems, particularly acid conditions and high concentration of metals. This research focuses on the concentration of two major elements released in ASS environments aluminium (Al) and iron (Fe), and two mobile metals under ASS conditions nickel (Ni) and copper (Cu).
The main objective of this study is to evaluate various geochemical factors involved in ASS environments, which in turn influence the response of mangrove seedlings to ASS. This study also seeks to determine the accumulation and translocation of metals within mangrove seedling tissues in relation to the concentration of metals in the soils of various environments, and their relationship to the mangrove seedlings‘ establishment and growth.
To achieve these objectives, a laboratory study was conducted at the Aquaculture Laboratory at QUT. For comparison, a field study was conducted in abandoned aquaculture ponds situated in the Mare District, adjacent to the Gulf of Bone, South Sulawesi, Indonesia. The study species in the laboratorory trials was Rhizophora stylosa, and the species examined in the field study included mainly R. stylosa and R. mucronata.are clearly shown in this study, where the seedlings tended to accumulate metals to certain amount based on their function and limited adsorption of non-essential metals. In regards to high levels of metals, mangrove seedlings regulated, retained metals mainly in their roots and employed an exclusion strategy, distributed them to aerial parts with low mobility and excreted them through leaf tissues.
The amount of potential acid (TPA and TSA) and pyrite in the surface soils strongly correlated with the acidity, density, establishment and growth of the seedlings. The presence of pyrite in surface soils allowed oxidation process to occur, which then enhanced the release of water-soluble sulfate, extractable sulfur, and exchangeable Al to subsurface soils, thus influencing the density and growth of mangrove seedlings. In contrast, the existing acidity (TAA) of both surface and subsurface soils, and associated existing acidity (water-soluble sulfate, extractable sulfur, exchangeable Al and Fe) in subsurface soils did not directly control the density, establishment and growth of the mangrove seedlings in the field study area. Exchangeable Al had a negative correlation with the establishment of the seedlings.
The free inundation of seawater produced an improvement in the soil quality of the study area, including higher pH (field and oxidisable), and low organic content. Free tidal inundation also generated low existing acidity, potential acidity and pyrite percentage on surface soils and reducing environments, therefore reducing the opportunity for pyrite to oxidise. Accordingly, the amounts of water-soluble sulfate, extractable sulfur and exchangeable Fe and Al on subsurface soils were low. Low organic material in these sites caused a low amount of SP and SPOS. Furthermore, physical and geochemical factors, such as: pH, redox potential, grain size, sulfur species affected metal concentrations in both soils and roots. All these processes highlight the importance of tidal inundation in improving soil quality and providing a good environment, which results in higher density, establishment and relative growth of mangrove seedlings in mangrove restoration projects. Good water circulation also allows propagule supply, therefore enabling mangroves to establish naturally.
This study provides a better understanding of the response of mangrove seedlings under conditions of various ASS, high metal concentrations, and non-ASS environments, as well as a recommended best strategy for achieving successful restoration in similar conditions.
Heavy metal pollution in the coastal areas is a serious global problem that needs to be properly assessed and mitigated. It poses negative long-term implication on the health of humans and also the ecosystem at large. Here we describe the causes and effects of heavy metal pollution in the coastal areas. Phytoremediation of heavy metals is discussed with emphasis on cadmium, arsenic, lead, copper, chromium, manganese, nickel, vanadium, and zinc. Located between marine and terrestrial environments, mangroves are transitional coastal ecosystems which are found mostly in the tropical and subtropical regions. The phytoremediation potential of several mangrove species is discussed. Finally, the different molecular mechanisms involved in phytoremediation of metals are described. There has been significant progress in determining the molecular basis for metal accumulation, which provides a strong scientific basis to outline several strategies for phytoremediation of metals. The metal transporter genes that are involved in hyperaccumulation of metals and biotechnological approaches including the transgenic plants are elucidated.
Thailand’s coastal zone is covered by rich mangrove forests that support a
vital ecosystem. The mangrove system provides food for the local people and nutrients
to the surrounding seas. Further, these forests protect the local environment by
acting like a green wall that reduces coastal erosion and helps reduce effects of heavy
waves and strong winds on the coast. Climate change will undoubtedly adversely affect
this ecosystem. Rising sea levels will impact the chemical and physical properties
of mangroves, resulting in harm of both plant and animal species. Mangrove forests in Thailand have already suffered destruction by intensive aquaculture encroachment
and urban area extension. The Thai government is implementing new strategies to
protect, preserve, and reforest certain areas; however, urbanization continues to release
detrimental heavy metal discharge into waterways. Continued accumulation of
these metals into the sediment will result in a long-term effect that will not be easily
mitigated. Mangrove trees are fast growing and can also serve as carbon sinks. The
impact of their ability to mitigate greenhouse effects when faced with toxic metal
discharge is unknown. Studies determining a mangrove forest’s ability to act as a
carbon sink, even under the negative impact of human activity, will be important to
preserve this ecosystem.
Accumulation and partitioning of eight heavy metals Cr, Pb, Zn, Cd, Ni, Cu, Co and Fe were studied in the root, stem and leaf of mangrove species (Sonneratia caseolaris, Acanthus ilicifolius and Excoecaria agallocha) for comparison and in mangrove sediments for calculation of bio concentration factor (BFC) in Sundarban India. Magnitude of Fe was found highest in the sediments (35371.71 mg kg(-1)) and plant parts of the three species (a maximum of 11428.0 mg kg(-1) in the root of S. caseolaris). For other heavy metals, plants showed exclusion and selection mainly based on utilization, regardless of their level in the sediments. In most of the cases significant variation of absorption was found between the three species (F=11.48 to 157.37; p<0.001) and between their plant parts (F=10.98 to 338.03; p<0.001). S. caseolaris was found to be a less potential heavy metal accumulator than the other two species, except for Fe and Zn in the root. Irrespective of the magnitude of the heavy metals, other species showed significant correlations (r=0.509 to 0.961; p<0.001) between heavy metal accumulations, exclusively due to chemical reason, whereas S. caseolaris showed significant correlations (r=0.554 to 0.926; p<0.001) between each and every heavy metal, which signifies similar mode of absorption pattern regardless of their utilization. This nonbiased manner of heavy metal accumulation pattern may help the species to withstand in the polluted areas.
The scientific literature for fate and effects of non-nutrient contaminant concentrations is skewed for reports describing sediment contamination and bioaccumulation for trace metals. Concentrations for at least 22 trace metals have been reported in mangrove sediments. Some concentrations exceed sediment quality guidelines suggesting adverse effects. Bioaccumulation results are available for at least 11 trace metals, 12 mangrove tissues, 33 mangrove species and 53 species of mangrove-habitat biota. Results are specific to species, tissues, life stage, and season and accumulated concentrations and bioconcentration factors are usually low. Toxicity tests have been conducted with 12 mangrove species and 8 species of mangrove-related fauna. As many as 39 effect parameters, most sublethal, have been monitored during the usual 3 to 6 month test durations. Generalizations and extrapolations for toxicity between species and chemicals are restricted by data scarcity and lack of experimental consistency. This hinders chemical risk assessments and validation of effects-based criteria.
We report the findings of a comparative analysis examining patterns of accumulation and partitioning of the heavy metals copper (Cu), lead (Pb) and zinc (Zn) in mangroves from available field-based studies to date, employing both species level analyses and a phylogenetic approach. Despite mangroves being a taxonomically diverse group, metal accumulation and partitioning for all metals examined were broadly similar across genera and families. Patterns of metal accumulation were also similar regardless of whether species were classified as salt secreting or non-secreting. Metals were accumulated in roots to concentrations similar to those of adjacent sediments with root bio-concentration factors (BCF; ratio of root metal to sediment metal concentration) of 1< or =. Root BCFs were constant across the exposure range for all metals. Metal concentrations in leaves were half that of roots or lower. Essential metals (Cu and Zn; translocation factors (TF; ratio of leaf metal to root metal concentration) of 0.52 and 0.53, and leaf BCFs of 0.47 and 0.51, respectively) showed greater mobility than non-essential metals (Pb; TF of 0.31 and leaf BCF of 0.11). Leaf BCFs for the essential metals Cu and Zn decreased as environmental concentrations increased. The non-essential metal Pb was excluded from leaf tissue regardless of environmental concentrations. Thus mangroves as a group tend to operate as excluder species for non-essential metals and regulators of essential metals. For phytoremediation initiatives, mangrove ecosystems are perhaps best employed as phytostabilisers, potentially aiding in the retention of toxic metals and thereby reducing transport to adjacent estuarine and marine systems.
Food chain contamination by cadmium (Cd) is the most important pathway of Cd exposure to the general population, excluding smokers. Factors affecting transfer of Cd from soil and air to plants are reviewed. The direct deposition of airborne Cd in the plants has only a marginal influence on the crop Cd concentrations in rural areas with low atmospheric Cd deposition, i.e. < 2 g Cd ha(-1) y(-1). However, the indirect evidence is presented, predicting that airborne Cd may be the major source of crop Cd and dietary Cd in conditions where atmospheric Cd deposition is well above 10 g Cd ha(-1) y(-1). This situation may occur around pyrometallurgic smelters with high Cd emissions. The absorption of Cd by plant roots is more influenced by soil factors, controlling Cd bioavailability than by total soil Cd. Elevated soil-plant Cd transfer is observed in soils with chloride salinity, in zinc deficient soils and acid soils.
Cadmium (Cd) is a potentially hazardous pollutant in the environment based upon observations of increasing emissions from production and waste-disposal operations, long-term persistence in the environment, and rapid uptake and accumulation of injurious concentrations by plants and animals. Chronic human exposure to low concentrations of cadmium in the atmosphere, water, or food may cause serious illness and possibly death. Production and consumption of cadmium is continuing to expand throughout the industrialized world. As a result, there is a critical need for understanding sources of emissions and their direct or indirect interactions with soil, water, plants, and animals so that criteria may be developed for assessing hazards.
Municipal sewage effluent with sludge injected and effluent alone were spray-irrigated on reed canarygrass (Phalaris arundinacea L.) and corn (Zea mays L.), respectively. In the maximum level (10 cm/week) reed canarygrass treatment, application rates for Cu, Zn, Cd, and Pb were 15.5, 25.5, 0.162, and 9.1 kg/ha in 1972 and 7.7, 13.2, 0.135, and 7.8 kg/ha in 1973. Rates of application for Cu, Zn, Cd, and Pb in the maximum level (7.5 cm/week) cornfield treatment were 0.6, 2.0, 0.029, and 1.1 kg/ha in 1972 and 0.6, 2.4, 0.032, and 2.4 kg/ha in 1973. Reed canarygrass was irrigated year round, while corn was irrigated only during the growing season. Copper and Zn concentrations and total uptake in the treated reed canarygrass area were generally higher than in the control for all cuttings of 1972 and 1973. Total uptake of heavy metals in the corn area control was usually as high or higher than in the treated areas. Copper and Zn concentrations and uptake in the effluent irrigated corn area were lower than in the treated reed canarygrass area. Data show a relative exclusion of Cd by Zn in the plant material, since Cd/Zn ratios in the harvested crops are lower than in either the applied waste water or the 0.1 N HCl extractable fraction of the treated soils. Accumulation of applied heavy metals in the treated soils was >93% of the amounts applied in 1972 and 1973 for all heavy metals in the reed canarygrass area and slightly less in the corn area.
Corn plants, were water-cultured by varying pH and concentration of calcium, phosphorus, zinc, and iron in nutrient solution containing graded levels of cadmium.The results obtained were summarized as follows:1) With an increase of the cadmium concentration, the cadmium content of plants increased and the total dry weight and grain yield decreased markedly in the absence of calcium. Under these conditions the addition of calcium or iron caused a decrease of the cadmium content, and an increase of the dry weight and grain yield. The pH and the addition of phosphorus or zinc had no notable effect on the cadmium uptake.2) The relationship between dry weight and cadmium content indicated that the critical cadmium content, above which plants suffer from the cadmium toxicity, was about 20 ppm on a dry matter basis, independent of treatments.3) Calcium or iron at an adequate concentration in nutrient solution are effective to depress cadmium uptake by corn plants.
The effect of Cd treatment on several vegetable species was investigated using batch-culture nutrient solution techniques. Lycopersicum esculentum Mill (tomato) was shown to be particularly sensitive to Cd damage. For all species, Cd in tops tended to increase with increased Cd levels in solution. At the highest Cd treatment investigated (1 µg Cd/m), Cd concentration in tops ranged from 2.2 µg/g for Daucus carota L. (carrot) to 158 µg/g for Lycopersicum esculentum Mill (tomato). For several species, Cd treatment resulted in increased concentration and total uptake of Zn in plant tops. This effect could be interpreted to imply root damage in the presence of Cd.
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Monocyclopentadienyltitanium trichloride (CpTiCl3) was directly immobilized on silica surface. The resulting CpTiCl3/SiO2-MAO was investigated in view of its suitability for syndiospecific polymerization of styrene using ESR spectroscopy. Polymerization results show that both the syndiotacticity and the activity decrease upon immobilization. A possible explanation is that the active sites may become aspecific after immobilization and part of the immobilized active sites can be leached into the solution in the presence of MAO.
An ecological survey was carried out to determine the levels of nutrients and heavy metals in the sediments and leaf tissues of two dominant mangrove plant species, Kandelia candel and Aegiceras corniculatum, in Futian mangrove forest, Shenzhen, the People's Republic of China. The spatial and seasonal variations of these elements were also investigated. The results show that there was no major difference between two sampling sites 150 m apart. In both sites, the sediment concentrations of total and NH4
+-N, total and extractable P, total and extractable K, total organic carbon were consistently higher in the landward locations and decreased gradually towards the sea. The sediment sample collected at the seaward edge of the mangrove plant community had the lowest levels of nutrient and organic matter. The vertical variations (from the land to the sea) of sediment heavy metals were less obvious and no particular trend could be identified. Extremely high contents of Cu, Cd, Pb, Cr and Zn were found at certain locations, suggesting the occurrence of some local contamination. The mean total metal concentrations in sediments decreased in the order Mn > Zn > Cu > Cr = Pb > Cd for the sample locations. Most of the heavy metals were not in a bioavailable form as the concentrations of extractable metals were relatively low (< 1%="" of="" total="" metals).="" pb,="" cr="" and="" cd="" were="" not="" detected="" in="" leaf="" samples.="" leaf="" c,="" n,="" p="" and="" k="" contents="" were="" similar="" between="" the="" two="" species="" and="" no="" significant="" difference="" was="" found="" among="" locations,="" although="">A. corniculatum seemed to have lower Mn concentrations than K. candel. With reference to temporal variations, no significant difference in sediment concentrations of some nutrients and metals was found between the spring and autumn seasons.
Kyoto University (京都大学) 0048 新制・課程博士 博士(農学) 甲第4571号 農博第616号 新制/農/560 UT51-90-G138 1990-03-23
A series of chemical extraction procedures are used to obtain data on the partitioning of trace metals among the various geochemical phases of sediments. These components include intersititial water, solubility of solid minerals, ions on exchange sites, metal carbonates, easily reducible phases, organics and sulfides, iron oxides, and lithogenous (mineral residual) fractions. In general, a mass balance of less than 10% deviation can be obtained. Experimental results show very small fractions of trace metals to be in the form of interstital water or soluble ions. Trace metals in the exchangeable phase are almost negligible, and those in the mineral residual phases range from 2.5% Cd for one sediment to 98% Cu for another. The non-residual trace metals content is found to increase with decreasing sand content.
Residues of cadmium in the environment are of particular concern because of known toxicities of it and its compounds to human beings and animals. Cadmium is absorbed through the respiratory system and the gastrointestinal tract. Chronic exposure has been shown to result in accumulations which cause serious decline of health and even death. This paper examines the man-made and natural sources of cadmium pollution of soil, water, and air and the mechanisms by which it enters the food chains of plants, animals, and man. 79 references, 1 figure, 14 tables.
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- Tsuchiya
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Phytochemical research on mangrove plants
- Js Xu
- P Lin
- S Meguro
- S Kawachi
Uptake rate of heavy metals by plant with respect to their content and form in soil in the east suburbs Beijing
- Z L Xia
- C R Mu
- S Z Li
- W Q Meng
- ZL Xia
Chemical elements of soil and plants in Hainan Island (in Chinese)
- J H Wang
- JH Wang
Mangrove and acid sulphate soils in China
- Z T Gong
- X P Zhang
- ZT Gong
Techniques and methods for biochemistry of plants (in Chinese)
- Z L Zhang
- G Y Wu
- ZL Zhang
Advances in research of pollution ecology of mangroves
- S Y Miao
- SY Miao
Study on absorbing and accumulating cadmium from polluted soil and tolerance to it in wood plants
- H Y Huang
- D M Jiang
- C X Zhang
- Y B Zhang
- S D Li
- HY Huang
Absorption accumulation of heavy metals by three economic plants
- R G Pan
- RG Pan
Uptake of cadmium, lead, and zinc by radish from soil and air
- J V Laferweff
- JV Laferweff
Cadmium residues in the environment
- A L Page
- AL Page
Influence on the levels of heavy metals in soil and plant from sewage sludge as fertilizer
- A K Anderson
- AK Anderson