Acute Silver Toxicity in Aquatic Animals Is a Function of Sodium Uptake Rate

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• 作者：Adalto Bianchini ; Martin Grosell ; Sean M. Gregory ; and Chris M. Wood
• 刊名：Environmental Science & Technology
• 出版年：2002
• 出版时间：April 15, 2002
• 年：2002
• 卷：36
• 期：8
• 页码：1763 - 1766
• 全文大小：68K
• 年卷期：v.36,no.8(April 15, 2002)
• ISSN：1520-5851

文摘

On the basis of these facts about freshwater fish andinvertebrates: (i) the Na⁺ turnover is a physiologicalprocess associated with the gill membranes; (ii) the keymechanism of acute silver toxicity consists of reduction inNa⁺ uptake by blockade of gill Na⁺,K⁺-ATPase; (iii) the mass-specific surface area of the gills depends on animalbody mass; and (iv) the gill surface is also the major siteof Na⁺ loss by diffusion, we hypothesized that whole bodyNa⁺ uptake rate (i.e., turnover rate) and secondarilybody mass would be good predictors of acute silver toxicity.Results obtained from toxicological (LC₅₀ of AgNO₃) andphysiological (²²Na uptake rate) tests performed on juvenilefish (rainbow trout, Oncorhynchus mykiss), early juvenileand adult crayfish (Cambarus diogenes diogenes), and neonateand adult daphnids (Daphnia magna) in moderately hardwater of constant quality support the above hypothesis.Therefore, sensitivity to AgNO₃, in terms of either totalmeasured silver or free Ag⁺, was reliably predicted fromthe whole body Na⁺ uptake rate in animals with body massranging over 6 orders of magnitude (from micrograms tograms). A positive log-log correlation between acute AgNO₃toxicity and body mass of the same species was alsoobserved. Furthermore, the whole body Na⁺ uptake ratewas inversely related to body mass in unexposed animals.The combination of these last two results explains whythe small animals in this study were more sensitive to Ag⁺than the larger ones. Taken together, these resultsclearly point out the possibility of incorporating the Na⁺uptake rate into the current version of the Biotic LigandModel to improve the predictive capacity of this model.In the absence of information on Na⁺ uptake rate, then bodymass may serve as a surrogate.