The processing of mercury in forested ecosystems

TitleThe processing of mercury in forested ecosystems
Publication TypeThesis
Year of Publication1998
AuthorsRea AWinona
DegreeDoctor of Philosophy
Number of Pages126 pp.
UniversityUniversity of Michigan
CityAnn Arbor, MI
KeywordsTOXINS
Abstract

This thesis will attempt to identify the origin of Hg deposited to forested ecosystems in litterfall and throughfall in order to understand how forested ecosystems process Hg. For the first time, a multi-element approach will be used to examine the origin of Hg in both litterfall and throughfall by comnparing Hg to other trace elements (with both anthropogenic or geologic sources) which have been previously studied in detail. Although a suite of 27 trace elements were analyzed per sample, only selected trace elements have been reported together with the Hg data because the main focus of this thesis is identifying the source of Hg in litterfall and throughfall. ... This thesis has identified dry deposition of atmospheric Hg as the source of Hg in litterfall and throughfall. Over 70% (13.2 +- 2.9 ug/m2) of the Hg entering this forested ecosystem was due to dry deposition of atmospheric Hg to the canopy. Based on this work, future research should be directed towards understanding the role of various Hg species, such as Hg+2 and methylHg, in forested ecosystems. Some of the Hg deposited to the forest floor in litterfall and throughfall may enter surrounding aquatic ecosystems through soil water run off. If a large portion of this Hg is being transported to aquatic ecosystems, it may be a significant and frequently overlooked source of Hg in fish tissue.