Organochlorine Pollutants in Western Antarctic Peninsula Sediments and Benthic Deposit Feeders

Lin Zhang,Kari Pohl,Rainer Lohmann,Rebecca Dickhut,Dave Demaster

doi:10.1021/es303553h

Abstract

Sediments and benthic deposit feeding holothurians were collected near the Palmer Long Term Ecological Research grid during the austral winter of 2008. Polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) were measured in Western Antarctic Peninsula continental shelf sediments, porewater, and benthic biota. Concentrations and fluxes in sediments decreased sharply away from the tip of the peninsula toward its interior. Sedimentary PCB fluxes were an order of magnitude lower than reported elsewhere, supporting the notion of a pristiner Antarctic environment. Hexa-chlorinated biphenyls dominated (40-100%) the PCB profiles in the sediments, while trichlorinated biphenyl 28 was the most abundant PCB congener in the porewater. PCB and OCP concentrations in holothurians were comparable to concentrations in other low trophic level biota in the Antarctic food web (i.e., krill). The partitioning of PCBs and OCPs between the sediments and porewater can be explained by a dual-mode model, which included both organic carbon and black carbon as partitioning media. Alternatively, a simpler one-parameter prediction assuming coal tar-like organic carbon performed equally well in explaining porewater concentrations The majorities of PCBs (63-94%) in the Western Antarctic Peninsula sediments were bound to black carbon or recalcitrant tar-like organic carbon, thereby lowering porewater concentrations. PCBs and OCPs in the holothurians were in equilibrium with those in the porewater.

Highlights

The Southern Ocean plays a pivotal role in the global carbon cycle and climate change [1], leading to an increasing amount of scientific activities and the establishment of numerous research stations in the Antarctic [2]
Fuoco et al showed that polychlorinated biphenyls (PCBs) were supplied by surrounding seas to the Ross Sea region [8]
Sediments and benthic biota samples were collected from five different locations on the Western Antarctic Peninsula (WAP) shelf near the Palmer long term ecological research (LTER) grid in Jul 2008 (Fig1) [41]

Summary

Introduction

The Southern Ocean plays a pivotal role in the global carbon cycle and climate change [1], leading to an increasing amount of scientific activities and the establishment of numerous research stations in the Antarctic [2]. Several baseline studies around deserted and current scientific research stations have been conducted to investigate local levels of contaminants [2, 4, 5] They have found patchy distribution of persistent organic pollutants (POPs) and higher concentrations of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) adjacent to scientific station [5, 6], indicating contamination from human activities. The inter-hemispheric exchange in the atmosphere is slow as reflected by the strong hemispheric gradients in gas phase concentrations of POPs [10] and the north-south atmospheric delivery is less efficient than west-east within the Southern Hemisphere [3] It would take several hundred years for seawater formed in the Arctic to travel to the Southern Ocean according to the 14C data [11, 12] and modeling studies found the transport time for

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