Download or read book Accumulation and Transfer of Persistent Organic Pollutants in Antartic Food Webs written by Daniel Scott Ellis and published by . This book was released on 2016 with total page 135 pages. Available in PDF, EPUB and Kindle. Book excerpt: Persistent organic pollutants (POPs) are a class of highly toxic chemicals which can travel long distances and resist degradation in the environment. Once transported, POPs are known to biomagnify in the food web, causing disease and mortality. Decades of research have found that polar regions are the final sink for POP contaminants released across the Earth. More recent research has pointed to the oceanic biological carbon pump as a mechanism to shift POPs from surface waters to deep-sea benthic ecosystems around the world. Despite the link between these two theories, no studies have attempted to test the two in tandem, in a deep-sea region of a polar ecosystem. In this study I examined how concentrations of four major groups of POPs have changed through time in the pelagic zone around Antarctica: dichlorodiphenyltrichloroethane (DDT), hexachlorobenzene (HCB), hexachlorocyclohexanes (HCHs), and polychlorinated biphenyls (PCBs). In an analysis of the published literature, I used penguin fat and eggs as biological indicators of POP contamination in the pelagic zone. My results demonstrated that DDTs have accumulated in the pelagic zone since 1964, and likely before. DDT concentrations in Antarcic pelagic feeders peaked in the early 1980s and since then have slowly declined to concentrations which are roughly equivalent to concentrations in the 1960s. Ratios of DDT/DDE in pelagic predators are evidence that DDT contamination was a result of volatilization from lower-latitude source regions. HCB contamination in the pelagic zone increased from lows in the 1960s to a peak in the mid-1990s, and declined thereafter. Increasing DDT and stable HCB concentrations in benthic fauna during the same period that DDT decreased and HCB increased in pelagic fauna suggest that they were possibly shifting from the pelagic zone to the Antarctic benthos. HCH contamination of the pelagic zone was higher between 1980-1989 than in any other decade since 1960. Temporal trends in PCB contamination in penguins from the Southern Ocean were not entirely clear; colony-fat measurements increased from 1970-1994, whereas colony-egg measurements, which rose from 1970-1974 to 1984, were variable but largely stable to the present day. Global patterns of POP emissions were evident in Antarctic penguins for DDTs and HCB, but less so for HCHs and PCBs. It took years for contaminant emissions to be transported to Antarctica and accumulate in Antarctic penguins: DDTs (14 years), HCB (14-20 years), HCHs (7 years), and PCBs (20--30 years). My examination of benthic fauna from a deep-sea region near the western Antarctic Peninsula could not detect DDT in benthic invertebrates. I measured a deposit-feeder, Abatus cavernosus, and a high-level trophic predator, the king crab Paralomis birsteini, for concentrations of three DDT isomers. In all of the examined samples, DDT isomers were below my average limits of detection: 0.29-1.06 ng/g. In this range, it is improbable that invertebrate fauna were affected by DDT contamination. It is likely that DDTs, which had accumulated at the site, were below detection limits or that the DDTs had already been redistributed by currents or more-mobile, benthic feeders such as fishes and seals. My study could not confirm that the deep-sea region in Antarctica I examined was a depositing ground for global POP stocks, but DDTs and other POPs could be accumulating in similar sites around Antarctica. My study provides the first examination of its kind in the region. Despite an absence of contaminated fauna, additional study is required to determine if the deep seas around Antarctica are final sinks for global POP stocks. Further research should seek to elucidate the interactions among major chemical pathways in the environment. Research of this kind is particularly relevant given the potential for climate change to interact with chemical transport in the environment.