Arsenic content in five sediment profiles from Admiralty Bay, King George Island, Antarctica

Abstract

Admiralty Bay is the largest bay on King George Island, Antarctica, with a total area of around 131 km2 and maximum depth of 530 m. This region is of utmost importance for studies of environmental quality assessment because of the presence of scientific research stations in this region. Since the early 80’s scientific research has been focused on the Brazilian Antarctic Station “Comandante Ferraz”. In addition, the Polish Station Henry Arctowiski (Ezcurra Inlet) and the Peruvian Machu Picchu Station are also based in the bay. All activities require the consumption of fossil fuel for their operation. Fossil fuel is recognized as an important input of major pollutants (organic compounds) and trace elements (As, Cd, Cu, Pb and Zn). Among trace elements, arsenic is highly toxic even in low concentration in the environment. Accordingly, this work presents the results of arsenic in 92 samples, representing five sediment profiles from different sites (Comandante Ferraz Station, Botany Point, Ulmann Point, Arctowski Station and Barrel Point) in Admiralty Bay. The highest As content was observed for Barrel Point profile (ranging from 7 to 11 mg.kg-1). Otherwise, by using the enrichment factor and the geochronology analysis, the Brazilian Antarctic Station presented the most relevant enrichment for this metalloid, suggesting its increase due to the human activities in the bay. Studies on contamination of aquatic systems have been focused on sediments, because this layer acts as a reservoir for many chemical substances, such as metals and metalloids. The depositional feature of the elements in the sediment gives a fingerprint of the contamination, providing information on the history of the contamination (Dinescu et al, 1998; Banin et al, 1998; Ribeiro et al, 2005). However, tracing the origin of the contaminants is not an easy task since the determination of background concentrations of chemical elements (in a range of environmental matrices, including sediments) are based on degree of temporal and spatial variability of a small number of samples. Sampling might not be representative of the whole studied area, in which local variance can exceed the analytical uncertainty, thereby increasing the complexity of geochemical fingerprint studies (Gasparon and Matschullat, 2006). A large number of studies have certainly reported the impact of human activities on the Antarctic environment. However, studies for determining baseline levels of metals and metalloids are still scarce. Furthermore, information from available data sets of the impacted sites is often applied to estimate the elemental levels at a regional scale. As a result, the elemental Antarctic baseline values may have exceeded the natural content in the region. Therefore, the development of studies to distinguish anthropogenic and natural sources from metals and metalloids in the Antarctic environment has become a concern and an important issue for the international scientific community (Gasparon and Matschullat, 2006). The Admiralty Bay located in King George Island is the largest embayment in the South Shetland Islands, which 5