Acid Volatile Sulfides and Simultaneously Extracted Metals in a Metal-Polluted Area of Taihu Lake, China

Abstract

There were similar distribution characteristics for acid volatile sulfides (AVS) and simultaneously extracted metals (SEM) in surface sediments, and the concentrations of AVS and SEM decreased from the deposition area to the center of the bay (lake). The ratio of AVS to SEM was\1 in the surface sediments, indicating that heavy metals in surface sediments may be bioavailable. The concentration of AVS increased with sediment depth, followed by a decrease with large variation, while the concentration of SEM remained constant. By comparing the concentration of SEM with total metals, it was shown that extracted Cu and Ni decreased with sediment depth, indicating increasing association of Cu and Ni with sulfides in deeper sediment layers. The lower extracted ratios for Pb and Zn compared with sulfidic sediment illustrated that AVS should not have strong control on sediment Pb and Zn. The molar ratio of AVS and reactive iron showed that heavy metals were dynamic and active in sediments in this lake.

Distribution characteristics and toxicity assessment of heavy metals in the sediments of Lake Chaohu, China

“…This was due to other metal-binding phases such organic matter, various form of Fe and Mn largely decreasing the bioavailability in sediments (Ankely et al 1996;Leonard et al 1996). Furthermore, the levels of AVS were quite dynamic in sediment, which might cause the results of the AVS-SEM models varied greatly at different sampling time (Yin et al 2008). The empirical SQGs such TEL-PEL were greatly influenced by geography, environment, derivation and resilience factors (MacDonald et al 2000;Ingersoll et al 2001;Hübner et al 2009).…”

“…Indeed, frequent resuspension will cause the components of the surface sediments to remain in a dynamic situation, especially in shallow lakes. Other factors, such as sediment transportation and bioturbation will also dilute the total metal contents in the surface sediment (Yin et al 2008).…”

“…Hübner et al (2009) compared 15 sets of common empirical SQGs and concluded that the threshold effect level (TEL)/probable effect level (PEL)-based SQGs (TEL and PEL concentrations) were the most appropriate approach because they offered a solid and justified scientific basis and extensive comparability. The use of different relationships between acid volatile sulfides (AVS) and simultaneously extracted metals (SEM) to establish mechanical models such as the ratio of SEM and AVS ( SEM/AVS), the difference between the SEM and AVS ( SEM-AVS) or the organic carbon normalized difference between SEM and AVS ( SEM-AVS)/ f oc ) to assess metal toxicity has been widely applied (Di Toro et al 1990;Burton et al 2005;Yin et al 2008). AVS is operationally defined as the amount of sulfides released during cold acid extraction, while SEM is defined as the amount of metals (normally including Cu, Pb, Zn, Cd, and Ni) liberated during the extraction of AVS (Di Toro et al 1990).…”

Sulfetos volatilizáveis por acidificação e metais extraídos simultaneamente na avaliação de sedimentos de água doce

“…[15][16][17] Existe uma região ótima de formação dos sulfetos nos sedimentos, que é intermediária entre a interface sedimento-água e as porções mais profundas. Geralmente na superfície, verifica-se a presença de O 2 , NO 3 -, Mn (IV) e Fe (III), que funcionam como receptores de elétrons em detrimento ao SO 4 2-, com consequente minimização da produção de sulfeto.…”

“…Em grandes profundidades, existe uma limitação em função da restrição na difusão dos íons SO 4 2-, o que implica em uma menor disponibilidade deste substrato para a produção de sulfeto. 17 Em ambientes fortemente influenciados por atividades antrópicas, como reservatórios de água de regiões metropolitanas, podem ser observados comportamentos bastante peculiares, como a ocorrência de concentrações consideráveis de sulfetos em porções sub-superficiais do sedimento (2-4 cm), seguida de regiões pobres em sulfetos e uma nova ocorrência dos sulfetos em porções mais profundas de tais sedimentos (11-16 cm). 18 Tal comportamento redox, nestes sedimentos impactados, pode ser atribuído às atividades bentônicas, que criam dutos nos sedimentos e propiciam a difusão de água contendo concentrações de oxigênio dissolvido relativamente maiores que os valores pré-existentes na água intersticial.…”