Oxidation of acid-volatile sulfide in surface sediments increases the release and toxicity of copper to the benthic amphipod Melita plumulosa

Abstract

Acid-volatile sulfides (AVS) are an important metal-binding phase in sediments. For sediments that contain an excess of AVS over simultaneously extracted metal (SEM) concentrations, acute or chronic effects should not result from the metals Cd, Cu, Ni, Pb and Zn. While AVS phases may exist in surface sediments, the exposure to dissolved oxygen may oxidize the AVS and release metals to more bioavailable forms. We investigated the role of oxidation of AVS, and specifically copper sulfide phases, in surface sediments, in the toxicity to juveniles of the epibenthic amphipod, Melita plumulosa. Sediments containing known amounts of copper sulfide were prepared either in situ by reacting dissolved copper with AVS that had formed in field sediments or created in sediments within the laboratory, or by addition of synthesised CuS to sediments. Regardless of the form of the copper sulfide, considerable oxidation of AVS occurred during the 10-d tests. Sediments that had a molar excess of AVS compared to SEM at the start of the tests, did not always have an excess at the end of the tests. Consistent with the AVS-SEM model, no toxicity was observed for sediments with an excess of AVS throughout the tests. However, the study highlights the need to carefully consider the changes in AVS concentrations during tests, and that measurements of AVS and SEM concentrations should carefully target the materials to which the organisms are being exposed throughout tests, which in the case of juvenile M. plumulosa is the top few mm of the sediments.

Acid-volatile sulfide and simultaneously extracted metals in surface sediments of the southwestern coastal Laizhou Bay, Bohai Sea: Concentrations, spatial distributions and the indication of heavy metal pollution status

“…Hence, the AVS approach is suitable for heavy metal toxicity assessment in ecosystems. So far, there are a number of reports on sediment quality assessment by [SEM] Hinkey and Zaidi, 2007;Prica et al, 2008;Liu et al, 2010;Simpson et al, 2012;Gao et al, 2013), but there are only a few studies using Burton et al, 2005;Di Toro et al, 2005;De Jonge et al, 2012a;De Jonge et al, 2012b).…”

Distribution and source analysis of heavy metal pollutants in sediments of a rapid developing urban river system

“…Therefore, investigating the distribution and speciation of metals from contrasting land uses may provide unique chemical signatures in aquatic sediments that in turn provide a scientific basis to assess the pollutant source and their potential ecological and human health risks. The assessment of potential metal risks depends not only on total metal concentrations, but also on their chemical forms (i.e., speciation) influencing bioaccessibility and bioavailability (Simpson et al, 2012). For example, the exchangeable and weak acid extractable fractions are considered as the most mobile and bioavailable metal fractions (Tessier et al, 1979;Pueyo et al, 2008).…”

Metal Fluxes from Porewaters and Labile Sediment Phases for Predicting Metal Exposure and Bioaccumulation in Benthic Invertebrates

“…In this region of the sediment, a number of processes would have contributed to the observed maxima, including metal release associated with the reductive dissolution of Fe(III) and Mn(IV), 12,26,27 degradation of organic matter [28][29][30] and/or oxidation of AVS phases. 31,32 Due to the low slicing resolution (1 cm), it was not possible to distinguish the different processes. It is also likely that minor contributions occurred from metals associated with dissolved organic matter which diffused into the resin.…”