Total Metal Accumulation Research Articles

Accumulation of total trace metals due to rapid urbanization in microtidal zone of Pallikaranai marsh, South of Chennai, India

The article presents the results for enrichment of total trace metals (TTMs) from Pallikaranai salt marsh in South Chennai, a metropolis on the southeast coast of India. TTMs Fe, Mn, Cr, Cu, Ni, Co, Pb, Zn, Cd, Sr, V, and Hg along with sediment texture, OC, and CaCO3 were analyzed in 36 surface sediments collected during August 2008 to recognize and observe the input of TTMs in the marsh from various sources in the city limits. In view of the rapid urbanization and industrialization in Chennai City, especially on the southern side, uncontrolled input of sewage, garbage, and industrial effluents into the Pallikaranai marsh land, the elevated concentrations are not surprising. The level of enrichment of TTMs has also increased by 20% to 60% for most of the elements when compared with all other ecosystems in the world as well as the nearby area. The results also indicate that the marshy region is more heavily contaminated with Cd, Hg, Cr, Cu, Ni, Pb, and Zn than other regions on the southeast coast of India. The Enrichment Factor, Contamination Factor, and I (geo) indexes are calculated, and these values are useful to assess the degree of pollution in sediments. The spatial distributions of TTMs are also controlled by other factors like geochemical, precipitation, and flocculation of particulate substances in the marsh. The results of the present study suggest the need for a regular monitoring and management program which will help to improve the quality of Pallikaranai pristine marsh land.

Metal accumulation and metallothionein induction in the spotted dogfish Scyliorhinus canicula

Recent studies indicate that elasmobranch fish respond differently to metal exposure than marine teleosts. Accumulation rates can be high, which despite the fact that normal background levels for metals in the marine environment are low, is worrying due to the long life span and late fecundity of most shark. The goals of the present study were to examine differences in accumulation rates and toxicity of a range of metals at equimolar concentrations (10 µM) in the Mediterranean or spotted dogfish, Scyliorhinus canicula. For this purpose, we exposed the dogfish to Ni (587 µg/L), Cd (1124 µg/L), Pb (2072 µg/L), Cu (635 µg/L), and Ag (1079 µg/L and two additional exposures at 10 µg/L and 1 µg/L) for one week and measured total metal accumulation, metallothionein induction, and parameters related to osmoregulation. Our study confirms the high toxicity and accumulation rates of Ag for elasmobranch fish, even at levels 100 to 1000 times lower than exposure levels of other metals. Also Pb accumulated readily in all organs, but did not cause any osmoregulatory disturbance at the exposure levels used. Ni and Cd seem to accumulate primarily in the kidney while Cu mainly accumulated in liver. In contrast to Ni and Cd, the three other metals Ag, Cu and Pb accumulated in the rectal gland, an important organ for osmoregulation and possible target organ for metal toxicity. Only Cu succeeded in initiating a protective response by inducing MT synthesis in liver and gills.

Tolerance and accumulation of zinc (Zn) and copper (Cu) in tobacco (Nicotiana tabacum L.) overexpressing a glutathione transferase gene from soybean

Event Abstract Back to Event Tolerance and accumulation of zinc (Zn) and copper (Cu) in tobacco (Nicotiana tabacum L.) overexpressing a glutathione transferase gene from soybean Efstathios Efthimiadis1, Christos Kissoudis1 and Irini Nianiou-Obeidat1* 1 Aristotle University of Thessaloniki, Department of Genetics and Plant Breeding, Greece In the current study, we examined wild type and transgenic Nicotiana tabacum L. cv. Virginia plants, overexpressing the Gmgstu4 from soybean, under zinc (Zn) and copper (Cu) treatments. Our aim was to evaluate the ability of gst transgenics to tolerate and accumulate zinc and copper, supplied individually. The experiment was conducted on six week old seedlings, which were placed in a greenhouse and watered with solutions at different concentrations (0, 100 and 200 ppm) of the two heavy metals. We measured the shoot length, the dry matter and the concentration of the metals using the atomic absorption technique in both shoot and root and we calculated the total accumulation of the uptaken metals in both tissues. The statistical analysis of the data showed that transgenics and wild type plants had no significant difference concerning the shoot length. The concentration of zinc and copper did not differentiate between transgenics and wild type plants in shoot, while in root the concentration of transgenics was almost two times higher than in wild types, under both metal treatments. Dry weight did not differentiate between transgenics and wild type plants. Total metal accumulation was almost two times higher in root than in wild type plants, while no difference was shown in shoot. Keywords: Copper, Zinc, Tobacco, transgenic plant Conference: 8th Southeast European Congress on Xenobiotic Metabolism and Toxicity - XEMET 2010, Thessaloniki, Greece, 1 Oct - 5 Oct, 2010. Presentation Type: Poster Topic: Genomics - Proteomics - Metabolomics Citation: Efthimiadis E, Kissoudis C and Nianiou-Obeidat I (2010). Tolerance and accumulation of zinc (Zn) and copper (Cu) in tobacco (Nicotiana tabacum L.) overexpressing a glutathione transferase gene from soybean. Front. Pharmacol. Conference Abstract: 8th Southeast European Congress on Xenobiotic Metabolism and Toxicity - XEMET 2010. doi: 10.3389/conf.fphar.2010.60.00117 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 28 Oct 2010; Published Online: 04 Nov 2010. * Correspondence: Dr. Irini Nianiou-Obeidat, Aristotle University of Thessaloniki, Department of Genetics and Plant Breeding, Thessaloniki, GR-54124, Greece, nianiou@agro.auth.gr Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Efstathios Efthimiadis Christos Kissoudis Irini Nianiou-Obeidat Google Efstathios Efthimiadis Christos Kissoudis Irini Nianiou-Obeidat Google Scholar Efstathios Efthimiadis Christos Kissoudis Irini Nianiou-Obeidat PubMed Efstathios Efthimiadis Christos Kissoudis Irini Nianiou-Obeidat Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Total metal levels in crayfish Astacus leptodactylus (Eschscholtz, 1823), and surface sediments in Lake Terkos, Turkey

The aim of this study was to determine the total metal accumulation (aluminium, copper, manganese, lead, cadmium and iron) in different organs and eggs of Astacus leptodactylus (Eschscholtz, 1823) and sediments total metal contents (aluminium, copper, manganese, lead, cadmium, iron, zinc, chromium, nickel) in Lake Terkos. Water and sediment samples were collected from two stations at two different depths (1 and 2 m) of Lake Terkos in May 2008. Crayfish samples were collected by trammel net at the same region. Primary hydrographic conditions, such as temperature (13.6-19.4 degrees C), salinity (0.27-0.34 per thousand), dissolved oxygen (7.04-12.30 mg l(-1)) and pH (7.42-8.51), were recorded for each sampling point. Moreover, the total organic carbon (1.65-5.44%) and the total calcium carbonate contents (19.44-41.16%) of sediment samples were determined. According to the Turkish Food Codex (J Zool 26:283-288, 2002), the maximum allowable Pb and Cd levels in crayfish are 0.5 mg/kg wet weight. Accordingly, the Pb and Cd levels determined in A. leptodactylus samples are below this limit. However, when compared with the acceptable metal limits defined by WHO, Australian National Health and Medical Research Council and Ministry of Agriculture in United Kingdom (UK), it is clear that the Cu level is at the limit and the Cd results exceed the limit. When the metal contents in sediment samples from Lake Terkos are examined, it is seen that the Al, Fe, Mn, Ni and Cu contents are lower while Zn, Cr, Cd and Pb contents are higher than the crustal average values. The high values draw attention to the land-based domestic and industrial inputs. Lake Terkos sediments have high enrichment factors (EF) of Zn, Cr, Cd and Pb metals which corroborate this result. The low EFs of Fe, Ni and Cu are due to the natural (terrigeneous) inputs. Additionally, there is no Al, Fe, Ni and Cu metal enrichment in these lake sediments because of the low contamination factor (CF) values. However, it is moderately contaminated by Zn, Cr and Pb, and heavily contaminated by Cd.

Metal accumulation and metallothionein induction in the spotted dogfish Scyliorhinus canicula

article i nfo Keywords: Elasmobranch Chondrichthyes Shark Nickel Cadmium Lead Silver Copper Urea Recent studies indicate that elasmobranch fish respond differently to metal exposure than marine teleosts. Accumulation rates can be high, which despite the fact that normal background levels for metals in the marine environment are low, is worrying due to the long life span and late fecundity of most shark. The goals of the present study were to examine differences in accumulation rates and toxicity of a range of metals at equimolar concentrations (10 µM) in the Mediterranean or spotted dogfish, Scyliorhinus canicula. For this purpose, we exposed the dogfish to Ni (587 µg/L), Cd (1124 µg/L), Pb (2072 µg/L), Cu (635 µg/L), and Ag (1079 µg/L and two additional exposures at 10 µg/L and 1 µg/L) for one week and measured total metal accumulation, metallothionein induction, and parameters related to osmoregulation. Our study confirms the high toxicity and accumulation rates of Ag for elasmobranch fish, even at levels 100 to 1000 times lower than exposure levels of other metals. Also Pb accumulated readily in all organs, but did not cause any osmoregulatory disturbance at the exposure levels used. Ni and Cd seem to accumulate primarily in the kidney while Cu mainly accumulated in liver. In contrast to Ni and Cd, the three other metals Ag, Cu and Pb accumulated in the rectal gland, an important organ for osmoregulation and possible target organ for metal toxicity. Only Cu succeeded in initiating a protective response by inducing MT synthesis in liver and gills.

Effect of heavy metal supplementation on local (Allolobophora parva) and exotic (Eisenia fetida) earthworm species: A comparative study

This study compares the effects of different metal concentration on survival, reproduction and total metal accumulation by two different earthworm species, Allolobophora parva and Eisenia fetida. The substrate was spiked with different heavy metals (Cu, Cr, Pb, Zn & Cd) with concentrations varying from 500–2500 mg/kg. Cu resulted in complete mortality at all doses for both species. The accumulation of heavy metals for Eisenia fetida in 45 days was in order of Cr > Cd > Pb > Zn where as for Allolobophora parva was Cd > Cr > Pb > Zn. Allolobophora parva accumulated significantly higher concentrations of heavy metals was found in Allolobophora parva as compared to Eisenia fetida. The percentage uptake for Cr and Pb ranged from 65–26% and 39–16% for Eisenia fetida while it was 83–30% and 70–24% for Allolobophora parva at 500–2500 mg/kg. Zn uptake was similar for both species. In case of Cd, uptake percentage for Eisenia fetida at 500 and 1000 mg/kg for local species it was 73% and 52%. Zn produced at 100% mortality at both 1500 and 2500 mg/kg, Cd produced was 43% and 44%, whereas 100% mortality at the highest concentration studied (2500 mg/kg). A mortality of 56–64% was observed at a concentration of 500–2500 mg/kg concentration of Cr while 57–68% mortality was found at 500–2500 mg/kg concentration of Pb. Cd had the greatest detrimental effect on cocoon production by Eisenia fetida and Allolobophora parva. Overall, it is concluded that local earthworm species especially the native species Allolobophora parva have tremendous potential to take up heavy metals from contaminated media/soils.

Assessing the importance of dietborne cadmium and particle characteristics on bioavailability and bioaccumulation in the nematodeCaenorhabditis elegans

To investigate the impact of multiple cadmium exposure pathways on bioavailability and bioaccumulation, Caenorhabditis elegans were exposed to either dissolved cadmium or to both particulate (dietborne) and dissolved cadmium. The dietborne metal exposure scenarios included evaluations of two bacteria species (Escherichia coli and Arthrobacter globiformis), varying bacteria concentrations, artificial particles (with different surface functional groups or coated with lipopolysaccharides), as well as a mixture of both bacteria and artificial particles. Total cadmium concentration in the nematodes was used as a proxy for total metal accumulation. Internal cadmium availability was determined using the cadmium-responsive gene-1 (cdr-1) transcript level, as quantified by real-time polymerase chain reaction. Particle-associated exposure was the predominant contributor to cadmium bioavailability and bioaccumulation; however, no clear relationship between cdr-1 expression and cadmium body burden was observed. The quality and quantity of particles, rather than the total particle-associated metal load, was of primary importance in regulating cadmium uptake and accumulation. Nematodes exposed to cadmium-contaminated bacteria displayed significantly higher levels of cdr-1 expression relative to artificial particles. Furthermore, C. elegans displayed a statistically significant difference in cadmium accumulation patterns between the biotic diet, abiotic particles, and aqueous phase. Waterborne exposure caused an increase in total cadmium body burden following inhibition of the P-glycoprotein transport system in nematodes. This may suggest that cadmium taken up by the aqueous phase is detoxified preferentially by excretion.

Effect of wastewater irrigation on vegetables in relation to bioaccumulation of heavy metals and biochemical changes

The present study was conducted to determine the heavy metal contamination in soil with accumulation in edible parts of plants and their subsequent changes in biochemical constituents due to wastewater irrigation. Though the wastewater contains low levels of the heavy metals (Fe, Mn, Pb, Cd, and Cr), the soil and plant samples show higher values due to accumulation. The trend of metal accumulation in wastewater-irrigated soil is in the order: Fe > Pb > Mn > Cr > Cd. Of the three species Colocasia esculentum, Brassica nigra, and Raphanus sativus that are grown, the order of total heavy metal accumulation in roots is Raphanus sativus > Colocasia esculentum, while in shoots the order is Brassica nigra > Colocasia esculentum > Raphanus sativus. The enrichment factor (EF) of the heavy metals in contaminated soil is in the sequence of Cd (3) > Mn (2.7) > Cr (1.62) > Pb (1.46) > Fe (1.44), while in plants EF varies depending upon the species and plant part. C. esculentum and R. sativus show a higher EF for Cr and Cd. All plants show a high transfer factor (TF > 1) for Cd signifying a high mobility of Cd from soil to plant whereas the TF values for Pb are very low as it is not bioavailable. Results of the biochemical parameters show decrease in total chlorophyll and total amino acid levels in plants and an increase in amounts of soluble sugars, total protein, ascorbic acid, and phenol except B. nigra for protein in plants grown in soil irrigated with wastewater as compared to control site.

PHYTOEXTRACTION OF METAL POLLUTED SOILS AROUND A Pb-Zn MINE BY CROP PLANTS

In order to assess their practical capability for the absorption and accumulation of Pb, Zn, and Cu, five common crop plants, i.e. maize (Zea mays), sunflower (Helianthus annuus), canola (Brassica napus), barley (Hordeum vulgare) and White lupine (Lupinus albus) were tested in pot experiments using six soil samples taken from mine tailings, pasture and arable soils around an old Pb-Zn mine in Spain. Metal concentration ranges of the soils were 76.2–785 mg kg−1, 127–1652 mg kg−1, and 12.4–82.6 mg kg−1 for Zn, Pb, and Cu, respectively. With the exception of the highest polluted sample, soil total metal concentration did not influence significantly biomass yields of each crop for the different growth substrates. The order found for the total metal accumulation rate (TMAR) in the crops was Zn>>Pb > Cu, with maize reaching the highest metal concentrations. Pb root concentrations were markedly higher than those of shoots for all the crops, while Zn and Cu were translocated to shoots more efficiently. Concentrations of metals extracted by EDTA and BCR sequential extraction were well correlated, in general, with both root metal content and TMAR. CaCl2-extracted Zn was well correlated with root concentrations, TMAR and, in some cases, with shoot contents. Our study showed that the test crops were not feasible to remediate the heavily or moderately contaminated soils studied here in order to achieve the total metal soil concentrations required by the current European laws.

Decontamination and/or revegetation of fly ash dykes through naturally growing plants

Present study is focused on the decontamination and/or revegetation of fly ash dykes through naturally growing plants, namely Calotropis procera, Cassia tora, Chenopodium album, Sida cardifolia, Blumea lacera. The results of sequential extraction study showed that maximum amount of metals (Na, K, Fe, Mn, Cr, Pb, Ni, Cd) were associated with residual and Fe–Mn fractions. Diethylenetriamine penta acetic acid (DTPA)–triethanolamine (TEA) extraction assessed the bioavailability of the metals. The total metal accumulation in tested plants was found in the order; C. album > S. cardifolia > C. tora > C. procera > B. lacera. The maximum bioconcentration factor (BCF) was recorded in S. cardifolia for the metals (Na, Fe, Zn, Cd), in C. procera for the metals (Mn, Cu, Ni, Cr) and in C. album for the metals (Co, Pb). However, the translocation factor (TF) of most of the metals was found more in S. cardifolia followed by C. album than other plants . Among all the plants, C. album have shown high BCF and low TF values for toxic metals (Pb, Cd) and suitable for phytostabilization of these metals. Principal component analysis was used to predict translocation behavior of the metals in different parts of the plants which was found similar for the metals (Cu, Zn, Mn, Cr). All examined plants are suitable for revegetation (naturally grows on fly ash dykes) and S. cardifolia and C. album may be used for decontamination purposes.

Bioaccumulation of heavy metals in fishes from Taihu Lake, China

The Cr, Zn, Cu, Cd, Pb contents were determined in Cyprinus carpio Linnaeus, Carassius auratus Linnaeus, Hypophthalmichthys molitrix and Aristichthys nobilis, which were caught from Meiliang Bay, Taihu Lake, a large, shallow and eutrophic lake of China. The results showed that: (1) the Cr, Cu, Pb, Cd contents in the edible parts of the four fish species were much lower than Chinese Food Health Criterion (1994), but the Zn contents were higher than the Criterion; (2) Cd contents were the highest in the liver of fish, Pb contents were almost the same in all organs of fish, Cr contents mainly enriched in the skin and gonads, Zn contents were the highest in the gonad (♀), and Cu contents were the highest in the liver; (3) the total metal accumulation was the greatest in the liver and the lowest in the muscle. The total metal accumulation was the highest in C. auratus L. This investigation indicated that fish products in Taihu Lake were still safe for human consumption, but the amount consumed should be controlled under the Chinese Food Health Criterion to avoid excessive intake of Zn.

Uptake and translocation of metals in fenugreek grown on soil amended with tannery sludge: Involvement of antioxidants

Agricultural and industrial activities cause heavy metal pollution in the soil, which adversely affect the plant growing therein. The plants of fenugreek ( Trigonella foenum-graecum L.) were grown in soil amended with different percent of tannery sludge (TS) (10%, 25%, 35%, 50%, and 100% TS) in order to study the effect on antioxidant levels due to translocation of metals (Fe, Zn, Mn, Cu, Cr, Pb). The accumulation of the metals was found more in shoots than roots, except Fe and Cr. The level of metals in seeds of the plant increased with increase in sludge amendments ratio except Mn, which decreased in roots, shoots, and seeds of the plant. Chromium was found below detection limits in the seeds at 10% and 25% TS. Correlation coefficient ( r) between total metal accumulation and extractable metals showed that Zn ( P<0.01), Cr ( P<0.01), and Cu ( P<0.05) are significantly correlated, whereas, correlation with pH showed significant positive relation with all the studied metals except Mn. Significant positive correlation was recorded between metal accumulation (Fe, Zn, Cu) and electrical conductivity, cation exchange capacity, and organic matter, however, Zn, Cr, and Cu showed significant positive correlation with bulk density, nitrate, ammonia, and available phosphorus. The analysis of the results showed that total chlorophyll content showed significant ( P< 0.5) increase in lower amendment of sludge (up to 35% TS at 30 d and 25% TS at 60 d) as over their controls. In roots, malondialdehyde, cysteine, non-protein thiol, proline, protein, ascorbic acid contents increased up to 35% TS at 30 d. Principal component analysis also showed that strong association exists among malondialdehyde, nonprotein thiol, protein, and cysteine contents in the plants grown on different amendments of TS. The level of antioxidants increased which enabled the plant to cope up the stress induced in the plants grown on lower amendments of TS, however, toxicity was observed at higher amendments.

Ecotoxicological Studies. 3. Heavy metals contaminating water and fish from Fayoum Governorate, Egypt

The distribution of some heavy metals in water and fish from Fayoum Governorate (Egypt) was studied in samples collected throughout two successive years (1997/1998 and 1998/1999). Water from Lake Qarun, a private fish farm and “Sanhour River” was found to contain heavy metals at concentration levels lower than those found in fish from the first two ecosystems. The heavy metals showed differential bioaccumulation in fish organs (e.g. flesh, head, viscera), and the accumulation pattern (as total heavy metal residues) was seasonally as follows: summer > autumn > winter > spring. Moreover, the relative accumulation of total heavy metals in the studied fish showed the following pattern: “Mousa fish” (Solea aegyptiaca) < “Bolti fish” (Tilapia sp.) < the shrimp (Penacus sp.) < “Bouri fish” (Mugil sp.). Among the analyzed metals (e.g. zinc, iron, manganese, copper, cadmium, chromium, nickel, lead, cobalt, tin), lead and cadmium were found in fish at mean concentrations above the permissible limits proposed by FAO.

Accumulation of Zn, Cd, Cu, and Pb in Chinese cabbage as influenced by climatic conditions under protected cultivation.

Accumulation of heavy metals from agricultural soils contaminated by low levels heavy metals has important implications in the understanding of heavy metal contamination in the food chain. Through field experiments (1994-1996), the influence of thermal regime under different treatments on the accumulation of zinc, cadmium, copper, and lead in Chinese cabbage [Brassica pekinensis (Lour) Rupr. cv. Nagaoka 50] grown in a Calcareous Fluvisol (Xerofluvent) in Granada (southern Spain) was examined. Two floating row covers were used: T(1) (perforated polyethylene, 50 microm thick) and T(2) (17 g m(-2) polypropylene nonwoven fleece). An uncovered cultivation (T(0)) served as control. Zn, Cd, Cu, and Pb levels in the whole tops of experimental plants were analyzed. Treatments T(1) and T(2) gave rise to differences in environmental conditions with respect to T(0). The influence of environmental factors manipulated by floating row covers (particularly under T(1)) increased total heavy metal accumulation in the above ground plant biomass with respect to the open-air crop. The total contents of Zn, Cd, Cu, and Pb were 30, 50, 90, and 40% higher in T(1), respectively, than in T(0). This technique could be used in contaminated zones for different plant species because the thermal effect favors the process of phytoextraction and thus reduces the contamination.

Leaf biochemical parameters in Avicennia marina (Forsk.) Vierh as potential biomarkers of heavy metal stress in estuarine ecosystems

Sediment loadings and leaf accumulation of the heavy metals copper (Cu), lead (Pb) and zinc (Zn) with accompanying changes in leaf chlorophylls' ( a+ b), carotenoids and the antioxidant enzyme peroxidase were examined in the grey mangrove Avicennia marina (Forsk.) Vierh, in order to determine the applicability of these parameters as biomarkers of heavy metal stress under field conditions. Copper was found to show limited accumulation to leaf tissue, following a linear relationship at lower sediment concentrations, with saturation at higher sediment Cu concentrations. Copper accumulation relationships to leaf tissue were maintained temporally, and increases in sediment Cu, salinity, and decreases in sediment pH and Zn contributed to the accumulation of Cu to leaf tissue. Lead showed a significant relationship between sediment and leaf Pb levels, but accumulation was minimal. Accumulation relationships for Pb were not maintained temporally, and high sediment Pb, low pH and organic content increased bioavailability and accumulation of Pb. Zinc was the most mobile of all metals and was accumulated to the greatest quantities in leaf tissue in a dose-dependant relationship. Some temporal variation in Zn accumulation occurred, and higher sediment pH, organic content Zn and Pb promoted leaf Zn accumulation. Leaf Cu and Zn showed the strongest relationship with peroxidase activity and to a lesser degree Pb. Zinc was the only accumulated metal to show relationship maintenance with peroxidase activity over time. It was found that peroxidase activity best reflects the total phytotoxic effect from the combined metal stress of all three accumulated leaf metals. The only significant photopigment relationship evidenced was that of leaf Zn with the chlorophyll a/ b ratio, but was not maintained temporally. Peroxidase activity may be an appropriate biomarker for Zn or total metal accumulation in leaf tissue, and the chlorophyll a/ b ratio a suitable biomarker of Zn accumulation though requires temporal monitoring under field conditions.

Heavy metal removal efficiencies in a river–marsh system estimated from patterns of metal accumulation in sediments

Estuaries have long been thought to be effective traps for river-borne contaminants; however, accurately predicting removal efficiencies remains problematic. In the Quinnipiac River, CT, marsh system, patterns of metal accumulation (Ag, Cd, Cu, Pb) in sediments were used to estimate heavy metal removal efficiencies. Linear and multivariate regression models were fit to sediment metal concentrations to estimate removal curves and surfaces, which avoided the large temporal variability commonly encountered when using direct water column measurements. Second order regressions normalized to the shortest distance to the river channel were found to have the best fit ( r>0.67) with the lowest standard error (<32%). The heavy metal removal efficiencies estimated by comparing total metal accumulation in marsh sediments with riverine flux were Ag=21%, Cd=6%, Cu=14%, and Pb=17%, which are comparable to the maximum removal efficiency of riverine suspended particulate matter (∼28%).

Modeling and impact of metal accumulation in bottom sediments of wet ponds

Data from thirteen sites located in south and central Florida were used to evaluate the heavy metal accumulation in the bottom sediments of wet detention ponds. Accumulation rates were calculated for cadmium, chromium, copper, iron, nickel, lead and zinc. Copper, zinc and lead accumulations account for 75 percent or more of the total heavy metal accumulation, excluding iron. Relative accumulation rates for copper, zinc and lead averaged 1:4:8:11.8, respectively. Linear and non-linear predictive equations based on the ratios of total drainage are to pond surface area were developed for copper, lead and zinc accumulation rates. The impact of sediment heavy metal content on benthic organisms was evaluated for nine of the study ponds. Benthic organisms in the bottom sediments showed less species diversity than typical freshwater lakes and copper appeared to be the most detrimental metal to benthic organisms.