Chronic toxicity of arsenic, cobalt, chromium and manganese to Hyalella azteca in relation to exposure and bioaccumulation.
ABSTRACT Chronic toxicity of As, Co, Cr and Mn to Hyalella azteca can be described using a saturation-based mortality model relative to total-body or water metal concentration. LBC25s (total-body metal concentrations resulting in 25% mortality in 4 weeks) were 125, 103, 152 and 57,900 nmol g-1 dry weight for As, Co, Cr and Mn respectively. LC50s (metal concentrations in water resulting in 25% mortality in 4 weeks) were 5600, 183, 731, and 197,000 nmol L-1, respectively. A hormesis growth response to As exposure was observed. Growth was a more variable endpoint than mortality for all four toxicants; however, confidence limits based on growth and mortality all overlapped, except Cr which had no effect on growth. Mn toxicity was greater in glass test containers compared to plastic. Bioaccumulation of As, Co, Cr, and Mn was strongly correlated with, and is useful for predicting, chronic mortality.
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ABSTRACT: Chronic toxicity and bioaccumulation of decamethylcyclopentasiloxane (D5) to Hyalella azteca was examined in a series of spiked sediment exposures. Juvenile H. azteca were exposed for 28d (chronic) to a concentration series of D5 in two natural sediments of differing organic carbon content (O.C.) and particle size composition. The chronic, LC50s were 191 and 857μgD5g(-1) dry weight for Lakes Erie (0.5% O.C.) and Restoule (11% O.C.) respectively. Inhibition of growth only occurred with the L. Restoule spiked sediment with a resultant EC25 of 821μgg(-1)dw. Lethality was a more sensitive endpoint than growth inhibition. Biota sediment accumulation factors (BSAFs, 28d) were <1 indicating that D5 did not bioconcentrate based on lipid normalized tissue concentrations and organic carbon normalized sediment concentrations. Organic carbon (OC) in the sediment appeared to be protective, however normalization to OC did not normalize the toxicity. Normalization of D5 concentrations in the sediments to sand content did normalize the toxicity and LC50 values of 3180 and 3570μg D5g(-1) sand dw were determined to be statistically the same.Chemosphere 12/2012; 93(5). DOI:10.1016/j.chemosphere.2012.10.052 · 3.50 Impact Factor
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ABSTRACT: Total metal concentrations (Cr, Ni, Cu, Zn, and Pb), acid volatile sulfide and simultaneously extracted metals (AVS-SEM), and heavy metal fractionation were used to assess the heavy metals contamination status and ecological risk in the sediments of the Pearl River Estuary (PRE) and adjacent shelf. Elevated concentrations at estuarine sites and lower concentrations at adjacent shelf sites are observed, especially for Cu and Zn. Within the PRE, the concentration of heavy metals in the western shore was mostly higher than that in the middle shore. The metals from anthropogenic sources mainly occur in the labile fraction and may be taken up by organisms as the environmental parameters change. A combination of total metal concentrations, metal contamination index and sequential extraction analysis is necessary to get the comprehensive information on the baseline, anthropogenic discharge and bioavailability of heavy metals.Marine Pollution Bulletin 06/2012; 64(9):1947-55. DOI:10.1016/j.marpolbul.2012.04.024 · 2.79 Impact Factor
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ABSTRACT: Experiments were conducted to evaluate the plant tolerance to Fe and its phytotranslocation by Jatropha curcas L. from an iron rich wasteland soil. The soil was collected from wasteland soil (WLS) of a small town Sandila, (Hardoi, U.P.) India, and three Jatropha clones were cultivated in WLS amended or not with sand or cowdung in a ratio of 3:2. The WLS had high pH, elevated electric conductivity (EC) and was rich in organic carbon and total NPK. Iron and Mn were 2-3 folds higher than that in the normal field soil. Net root and shoot elongation as well as fresh and dry biomass of the plants were only slightly affected at 100 d in WLS as compared with that grown in non-polluted soil. Tolerance index (TI) of J. curcas was significantly higher in cowdung amended WLS in comparison to that in WLS, or WLS amended with sand. Translocation factor (TF) from the soil to plants for Fe was significantly higher in WLS than that in the normal field soil. Bio-concentration factor (BCF) and concentration index (CI) for Fe were 0.12 to 0.37, 1.0 to 6.2 respectively. The results indicate that Jatropha plantation is suitable for phytoremediation of Fe-contaminate wasteland soils, and also that these polluted fields could be used to cultivate this important biodiesel plant species.Brazilian Journal of Plant Physiology 01/2010; Vol.22(No.4-1). DOI:10.1590/S1677-04202010000400003