Relationship between watersheds characteristic and Hg concentration in fish

Abstract
It is recognized that the watersheds constitute one of the main Hg inputs to lakes. However since Hg cycling in lake environments is very complex, the relationship between the watershed characteristic and Hg concentration in fish is very difficult to establish. It is also well known that organic carbon is an important vector of transport for Hg coming from the watershed to the lake. Many studies have used these premises to state that there is a relationship between dissolved organic carbon concentration in lake waters and the Hg contamination in the biota. However, this hypothesis remains to be confirmed as past studies were inconclusive. In regards of these finding, we studied 1) the relationship between the molecular composition of dissolved and particulate organic carbon and Hg levels in fish species (northern pike and walleye); 2) the relationship between these carbon signatures and the watershed characteristics. The lignin composition of the organic fraction is specifically targeted. The study of these relationships may lead to a better understanding of the relationship between organic carbon species, the watershed characteristics and the Hg contamination of fish.