Claude F. Boutron

Mercury in Ancient Ice and Recent Snow from the Antarctic

Atmospheric mobilization and depositional processes are major features of the global biogeochemical Hg cycle. The atmosphere is an important pathway for the introduction of Hg into marine and terrestrial aquatic systems. Current estimates for human-related Hg emissions to the atmosphere parallel natural fluxes (Fitzgerald, 1986; Nriagu, 1989; Nriagu and Pacyna, 1991). This large anthropogenic interference has increased Hg deposition regionally and globally. In addition, the impact of anthropogenic emissions is amplified because Hg and many of its compounds, while toxic, can be converted to more poisonous forms (i.e., monomethyl mercury) in aquatic systems (Fitzgerald and Clarkson, 1991; Beiger and Jernelov, 1979). The present observed broad geographic incidence (e.g., USA, Canada, Sweden) of elevated Hg concentrations (as monomethyl mercury, MMHg) in piscivorous fish appears linked to human-related contemporary increases in Hg deposition (Lindqvist, 1991; Fitzgerald et al., 1991; Wiener et al, 1990). This is a serious international human health concern since fish and fish products are the largest source of MMHg in the human diet (Fitzgerald and Clarkson, 1991). Evidence for regional increases in atmospheric Hg deposition has been deduced from the Hg distribution in lake sediments (Rada et al, 1989; Bjorkland et al., 1984; Swain et al., 1992) and ombrotrophic bogs (Benoit et al., 1994; Madsen, 1981). On a larger spatial and temporal scale, however, hemispheric patterns of modern and historic deposition patterns are lacking. Such information is required to establish the extent of anthropogenic impact and to provide a foundation for future biogeochemical studies of Hg.

Heavy Metals in Antarctic and Greenland Snow and Ice Cores: Man Induced Changes During the Last Millennia and Natural Variations During the Last Climatic Cycles

In this chapter, we give an overview of some of the most interesting results which have been obtained by studying the changing occurrence of heavy metals in Antarctic and Greenland snow and ice cores. After recalling the pioneering role of Clair Patterson in this field, we describe first briefly the conditions which must be fulfilled to obtain fully reliable data, especially regarding the cleanliness of the samples and the use of specially designed clean laboratories. We present then some of the most interesting data which have been obtained on man induced changes during the past millennia/centuries. They show clear evidence of a global pollution of the atmosphere of our planet for heavy metals, which can be detected even in the most remote areas of the Southern Hemisphere and can be traced back to Roman times in the Northern Hemisphere. Finally, we present some recent data on past natural changes in heavy metals in ice dated back to 670 kyr BP, with pronounced variations during the successive interglacial/glacial climatic cycles.

Chapter 3 – Trace element determination in polar snow and ice. An overview of the analytical process and application in environmental and paleoclimatic studies

Publisher Summary This chapter emphasizes the study of trace element distribution in polar regions that provides information on the history of global scale atmospheric pollution caused by man. Lead concentration profiles in Greenland and Antarctic snow and ice contributes to a better knowledge of the worldwide dispersion of toxic substances emitted by several sources at mid latitudes and scavenged to the ground up to the polar ice caps. Together with Lead, other heavy metals, as cadmium, copper, and zinc, and platinum group elements (PGEs) have revealed their presence in the snow of the these environments, with concentrations above the natural background levels, pushing researchers to develop novel approaches for the determination of the analytes. The study of the occurrence of PGEs in polar snows constitutes an absolute novelty in terms of the effects for the use of gasoline of new formulation on the environment. The laboratories in the world that accepted this challenge use sophisticated sampling procedures in the field, and powerful analytical techniques such as double focusing magnetic sector Inductively Coupled Plasma Mass Spectrometry (ICP-MS), Laser Excited Atomic Fluorescence Spectrometry (LEAFS), and Thermal Ionisation Mass Spectrometry (TIMS), to produce a wealth of reliable data useful in the difficult task of deciphering snow and ice archives.