Analysis of Total Mercury and Methylmercury in Environmental Samples

Abstract

During a ten year collaborative project between Hydro-Québec, the Université de Sherbrooke and the Université du Québec à Montréal, analytical methods to measure total mercury (total Hg) and methylmercury (MeHg) concentrations in different compartments of hydroelectric reservoir and natural lake ecosystems were developed and adapted. As a result of improvements made to our analytical procedures for measuring dissolved Hg species techniques (i.e., gold amalgamation with cold vapor atomic absorption spectrophotometry and direct measurement with atomic fluorescence spectrophotometry) both the sample volumes needed (from 1–10 L to 10–50 mL) and the detection limits (from 5 ng L^-1 to 0.1 ng L^-1) have decreased. Similarly, in biological samples, we reduced the required sample size from 300 mg dry weight (dw) to < 1 mg dw. By allowing us to determine Hg concentrations in small environmental samples, improvements to analytical techniques represent a key link in our understanding of Hg cycling in reservoir and natural lake ecosystems.