Time: 15:30-16:30, 17th November 2017
Venue: Lecture Hall (221), Building No.16,Weijin Campus, Tianjin University
Speaker: Prof. Holger Hintelmann, Chemistry/ERS, Trent University (Canada)
Topic: Mercury in polar environments
Abstract:
The polar regions are recognized as being geopolitically and economically important and extremely vulnerable to current and projected climate change. This presentation will summarize the use of glaciers and ice cores as an archive of past accumulation, storage and release of mercury. Long term total Hg and methylmercury records of glacier samples from the Canadian Arctic show that Hg levels increased from < 0.2 ng/L in pre-industrial times to 0.8 - 1.2 ng/L during the last 200 years. Concurrent measurements of Hg isotope ratios suggest that historical variations in the Hg isotope composition recorded in snow and firn on Canadian High Arctic ice caps over the past ~200 years compare remarkably well with those modeled for total atmospheric Hg emissions.
Methylmercury (MMHg) has serious implications for human health, especially for northern Inuit communities, whose diet is predominantly composed of marine fish and mammals. Potential sources of MMHg in the high Arctic were investigated using isotope enriched Hg tracers. We show that methylation of mercury is significant in the polar ocean itself, contributing approximately 50% to the standing pool of the MMHg present in polar marine waters. An alternative source is possibly the formation of dimethylmercury (DMHg) in the ocean. Concentrations of atmospheric MMHg and DMHg were measured during two arctic cruises.
