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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- "In some cases, the estimated values of n sed in Eq. (4) were extremely large and could not be determined accurately, therefore, if estimates of n sed were >100, it was set to 100 according to Borgmann et al. (2004). Lethal sediment concentrations causing 25% mortality (LC25) were determined according to Norwood et al. (2007) as: "
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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- "The reason for the discrepancy is that higher metal content does not always mean more severe contamination, and more severe metal contamination does not always mean high ecological toxicity. Although the biological toxicity test using sediments with different heavy metal content has been conducted by many authors (Kemble et al., 1998; Norwood et al., 2007; Penttinen et al., 2008), the sediment quality guidelines do not account for the physico-chemical attributes (such as grain size, organic matter content, sulfides, chemical species and complexes) of the sediments that may increase or decrease the potential for toxic effects at a specific area (Ho et al., 2010). Therefore, the ecological risk evaluation based on the total concentration of trace metal in sediment is believed to be problematic because different sediments exhibit different degrees of bioavailability for the same total metal content (Di Toro et al., 1990). "
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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- "These results showed that the plants have the ability to tolerate polymetallic sawdust sludge contaminated soils having high levels of Cu, Fe, Pb, Al and Zn which are in agreement with the findings of Qihang et al. (2011). The heavy metals toxicity and extreme infertility in the contaminated soils are the major limiting factors for the plant growth (Norwood et al., 2007). A number of studies showed that organic amendment resulted in successful re-vegetation of metal contaminated soil (Ortiz and Alcaniz, 2006; Kumar et al., 2008). "
ABSTRACT: Heavy metal pollution in soil is one of the most important environmental problems throughout the world and heavy metals cause significant toxic effect on humans, animals, microorganisms and plants. An experiment was conducted in sawdust contaminated soils at glasshouse to determine the growth response, metal tolerance and phytoremediation potential of Jatropha curcas. The J. curcas seedlings were planted in the growth media: T0 (Control, 100% soil, clay), T1 (80% soil + 20% sawdust sludge), T2 (60% soil + 40% sawdust sludge), T3 (40% soil + 60% sawdust sludge), T4 (20% soil + 80% sawdust sludge) and T5 (100 % sawdust sludge). The seedlings showed the best growth performance in T2 treatment in terms of height, basal diameter and number of leaves. The highest plant biomass was recorded in T2 and the maximum reduction of copper, iron, lead and zinc was also found in this treatment. Copper, lead and zinc were highly concentrated in the roots while iron and aluminum concentrated both in roots and leaves. The Jatropha curcas found to have a high potential to accumulate high amounts of copper, iron, aluminum, lead and zinc in its roots, leaves and stems. Plant in control to medium contaminated soils showed maximum translocation factor. The species was able to tolerate and accumulate a high concentration of heavy metals. Being a biodiesel non-food plant, Jatropha curcas can be an ideal option to be grown for phytoremediation in multi-metal contaminated sites and to mitigate the soil pollution.