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Arch Environ Contam Toxicol (2011) 61:491499 DOI 10.1007/s00244-010-9641-z
Mercury Biomagnication in the Aquaculture Pond Ecosystem in the Pearl River Delta
Zhang Cheng Peng Liang Ding-Ding Shao
Sheng-Chun Wu Xiang-Ping Nie Kun-Ci Chen
Kai-Bin Li Ming-Hung Wong
Received: 27 September 2010 / Accepted: 30 December 2010 / Published online: 3 February 2011 Springer Science+Business Media, LLC 2011
Abstract This is the rst study to investigate the rate of mercury (Hg) biomagnication in the aquaculture pond ecosystem of the Pearl River Delta (PRD), China, by analyzing total mercury (THg) and methyl mercury (MeHg) concentrations in various species of sh at different trophic levels (TLs). Species representing a gradient of trophic positions in the aquaculture pond food chains were chosen for analyzing THg and MeHg concentrations. In this study, there were two kinds of the aquaculture pond food chains: (1) omnivorous (sh feeds, zooplankton, grass carp [Ctenopharyngodon idellus], and bighead carp [Aristichthys nobilis]) and (2) predatory (zooplankton, mud carp [Cirrhina molitorella], and mandarin sh [Siniperca kneri]). Bighead carp and mandarin sh had the highest MeHg and THg concentrations, i.e., an order of magnitude higher than other species, in their respective food chains. More than 90% of the THg concentrations detected in bighead carp, mandarin sh, and mud carp were in the methylated form. In this study, %MeHg increased with
TLs and MeHg concentrations, reecting that MeHg is the dominant chemical species of Hg accumulated in higher concentrations in biota, especially biota associated with higher TLs in the food chains. The trophic magnication factors were 2.32 and 2.60 for MeHg and 1.94 and 2.03 for THg in omnivorous and predatory food chains, respectively, in PRD. Hg concentrations in sh tissue correlated to Hg levels in the ambient environment, and sediment seemed to be the major source for Hg accumulated in sh. In addition, feeding habit also affected Hg accumulation in different sh species. Four signicant linear relationships were obtained between log-THg and d15N and between
log-MeHg and d15N. The slope of the regression equations, as biomagnication power, was smaller in magnitude compared with those reported for temperate and arctic marine and freshwater ecosystems, indicating that THg and MeHg biomagnications were lower in this PRD subtropical aquaculture pond ecosystem. This was probably due to low Hg bioavailability at lower TLs...