Inverse Relationship Between Bioconcentration Factor and Exposure Concentration for Metals: Implications for Hazard Assessment of Metals in the Aquatic Environment

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The purpose of this study was to develop a site-specific water quality standard for selenium in the Great Salt Lake, Utah, USA. The study examined the bioavailability and toxicity of selenium, as selenate, to biota resident to the Great Salt Lake and the potential for dietary selenium exposure to aquatic dependent birds that might consume resident biota. Because of its high salinity, the lake has limited biological diversity with bacteria, algae, diatoms, brine shrimp, and brine flies being the only organisms present in the main (hypersaline) portions of the lake. To evaluate their sensitivity to selenium, a series of acute and chronic toxicity studies were conducted on brine shrimp (Artemia franiciscana), brine fly (Ephydra cinerea), and a hypersaline alga (Dunaliella viridis). The resulting acute and chronic toxicity data indicated that resident species are more selenium tolerant than many freshwater species. Because sulfate is known to reduce selenate bioavailability, this selenium tolerance is thought to result in part from the lake's high ambient sulfate concentrations (>5,800 mg/L). The acute and chronic test results were compared to selenium concentrations expected to occur in a mining effluent discharge located at the south end of the lake. Based on these comparisons, no appreciable risks to resident aquatic biota were projected. Field and laboratory data collected on selenium bioaccumulation in brine shrimp demonstrated a linear relationship between water and tissue selenium concentrations. Applying a dietary selenium threshold of 5 mg/kg dry weight for aquatic birds to this relationship resulted in an estimate of 27 microg/L Se in water as a safe concentration for this exposure pathway and an appropriate chronic site-specific water quality standard. Consequently, protection of aquatic birds represents the driving factor in determining a site-specific water quality standard for selenium.

Section: Bioaccumulation Studysupporting

confidence: 53%

Derivation of a chronic site‐specific water quality standard for selenium in the Great Salt Lake, Utah, USA

Brix¹,

DeForest

Cardwell

et al. 2004

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“…In the present study, a significant negative correlation was also found for Cd (p < 0.001) and Zn (p < 0.05) but not for Cu at the level of whole body (Figure 4). Such an inverse relationship between the TTF and the metal concentration in a purified diet is analogous to the relationship found between the bioconcentration factor and the metal concentration in the water [20,59] and has important implications for environmental evaluations such as classifying hazards and assessing ecological risks. Because higher TTFs were associated with lower metal burdens in prey, TTF should not be used to indicate the bioaccumulation or trophic transfer (bioavailability) without considering the exposure concentration.…”

Section: Metal Concentration Dependent Trophic Transfermentioning

confidence: 69%

Bioavailability of purified subcellular metals to a marine fish

Guo

Yao

Wang

2013

In the present study, the authors used a supply of naturally contaminated oysters to investigate how the subcellular metal distribution and the metal burden in prey affected the transfer of metals to a marine fish, the grunt Terapon jarbua. The oysters, Crassostrea hongkongensis, each with different contamination histories, were collected and separated into 3 subcellular fractions: 1) metal-rich granules, 2) cellular debris, and 3) a combined fraction of organelles, heat-denatured proteins, and metallothionein-like proteins, defined as the trophically available metal (TAM). These purified fractions showed a wide range of metal concentrations and were fed to the fish for a period of 7 d at a daily comparable feeding rate of 3% of fish body weight. After 7 d exposure, the newly absorbed metals were mainly distributed in the intestine and liver, indicating a significant tissue-specific trophic transfer, especially for Cd and Cu. The trophic transfer factors (TTFs) showed a sequence of cellular debris >TAM > metal-rich granules, suggesting the impact of subcellular distribution in prey on metal bioavailability. However, significant inverse relationships between the TTFs and the metal concentrations in diets were also found in the present study, especially for Cd and Zn. The subcellular metal compartmentalization might be less important than the metal concentration in prey influencing the trophic transfer. The authors' results have important implications for bioavailability and environmental assessment of dietary metals.

“…It follows that any water quality guidelines seeking to protect biota from deleterious effects of Tl should consider the role of K. The Tl(I) concentrations used in the uptake experiments described here (2.75 nM) exceed Tl concentrations observed in the Great Lakes (6-180 pM). Because concentration factors for some metals in aquatic organisms can be inversely related to ambient metal concentrations [26], the concentration factors reported here for Tl in phytoplankton may be underestimates. However, concentration factors on dry weight bases, determined with Tl(I) additions of 1 nM to Lakes Erie and Ontario seston, were about 1 ϫ 10 3 [7], suggesting that the concentration factors determined in the experiments reported here probably are not underestimates of the degree of enrichment of this element in natural phytoplankton communities.…”

Section: Role Of K In Tl(i) and Dmt Uptake Thallium(i) Uptake Bymentioning

confidence: 82%

Bioconcentration of inorganic and organic thallium by freshwater phytoplankton

Twiss

Twining

Fisher

2004

Uptake of inorganic Tl(I) and dimethylthallium, (CH3)2Tl+, by Chlorella spp. (Chlorophyta) and the diatom Stephanodiscus hantzschii (Heterokontophyta) were measured using radio-tracer techniques in water from Lakes Erie and Superior (North America). Uptake of both Tl(I) and dimethylthallium was bioactive. Uptake of [204Tl]-Tl(I) was greater in Lake Superior water than in Lake Erie water due to the greater K content in Lake Erie that inhibits Tl(I) uptake by phytoplankton but not that of [204Tl]-dimethylthallium. Volume-based bioconcentration factors for Tl(I) after 72 h of exposure were 5 x 10(4) and 1.1 x 10(4) for Chlorella sp. and S. hantzschii; for dimethylthallium they were 7.8 x 10(2) and 8.3 x 10(3). Both Tl(I) and Tl(III) were concentrated similarly by Chlorella spp. These results suggest that chlorophytes, but not diatoms, accumulate Tl(I) to a greater extent than dimethylthallium. Greater bioaccumulation factors of inorganic Tl are possible in waters containing low amounts of K+; water quality guidelines seeking to protect biota from deleterious effects of Tl should consider the role of K.