Brief communication: Organochlorine pesticides in an archived firn core from Law Dome, East Antarctica

Marie Bigot,Camilla F Teixeira,Roger Cropp,Andrew D Moy,Mark A J Curran,Derek C G Muir,Darryl W Hawker,Susan M Bengtson Nash

doi:10.5194/tc-10-2533-2016

Abstract

Abstract. Organochlorine pesticides (OCPs) were, for the first time, quantified in archived firn cores from East Antarctica representative of 1945–1957 and 1958–1967 (current era, C.E.). The core sections were melted under high-purity nitrogen atmosphere, and the meltwater was analysed. Methods allowed quantification of hexachlorocyclohexanes, heptachlor, trans-chlordane, dieldrin and endrin. While the core presented evidence of nominal contamination by modern-use chemicals, indicating handling and/or storage contamination, legacy OCP concentrations and deposition rates reported are orders of magnitude lower than those from Arctic regions, lending support for their validity. The study further provides a description of equipment used and suggests methods to overcome logistical challenges associated with trace organic contaminant detection in polar regions.

Highlights

Persistent organic pollutants (POPs) are ubiquitous, toxic, anthropogenic substances that have been widely used in agriculture and manufacturing industries since the 1930s
The relatively large volumes of firn analysed in this study enabled the quantification of the legacy Organochlorine pesticides (OCPs) α- and γ -HCH, heptachlor, trans-chlordane, dieldrin and endrin in the dissolved fraction of the meltwater of both samples (Fig. 3)
While no direct link can be established between polybrominated diphenyl ethers (PBDEs) levels introduced and possible contamination of the firn core by legacy OCPs, the presence of the PBDE markers necessitates caution in the interpretation of results

Summary

Introduction

Persistent organic pollutants (POPs) are ubiquitous, toxic, anthropogenic substances that have been widely used in agriculture and manufacturing industries since the 1930s. Unlike seasonal sea ice that persists for only limited periods of time, ice sheets are deposited over thousands of years This makes them a rich archive for the study of past atmospheric composition and climate variations. As the ice compartment represents a reservoir of historically deposited POPs, quantification of concentrations in Antarctic continental ice is relevant in order to predict the possible future POP re-emission into the atmosphere and oceans through ice melt. This secondary input process has previously been demonstrated for melting alpine glaciers in Switzerland (Bogdal et al, 2009). The work addresses some of the challenges associated with the sampling of this matrix for the trace levels of POPs generally observed in Antarctica, and describes purpose-built equipment for overcoming some of these challenges

Firn core sourcing

Sampling procedures

Results and discussion

Conclusions