Spatiotemporal patterns of mercury accumulation in lake sediments of western North America

Science of the Total Environment
By: , and 

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Abstract

For the Western North America Mercury Synthesis, we compiled mercury records from 165 dated sediment cores from 138 natural lakes across western North America. Lake sediments are accepted as faithful recorders of historical mercury accumulation rates, and regional and sub-regional temporal and spatial trends were analyzed with descriptive and inferential statistics. Mercury accumulation rates in sediments have increased, on average, four times (4×) from 1850 to 2000 and continue to increase by approximately 0.2 μg/m2 per year. Lakes with the greatest increases were influenced by the Flin Flon smelter, followed by lakes directly affected by mining and wastewater discharges. Of lakes not directly affected by point sources, there is a clear separation in mercury accumulation rates between lakes with no/little watershed development and lakes with extensive watershed development for agricultural and/or residential purposes. Lakes in the latter group exhibited a sharp increase in mercury accumulation rates with human settlement, stabilizing after 1950 at five times (5×) 1850 rates. Mercury accumulation rates in lakes with no/little watershed development were controlled primarily by relative watershed size prior to 1850, and since have exhibited modest increases (in absolute terms and compared to that described above) associated with (regional and global) industrialization. A sub-regional analysis highlighted that in the ecoregion Northwestern Forest Mountains, <1% of mercury deposited to watersheds is delivered to lakes. Research is warranted to understand whether mountainous watersheds act as permanent sinks for mercury or if export of “legacy” mercury (deposited in years past) will delay recovery when/if emissions reductions are achieved.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Spatiotemporal patterns of mercury accumulation in lake sediments of western North America
Series title Science of the Total Environment
DOI 10.1016/j.scitotenv.2016.03.167
Volume 568
Year Published 2016
Language English
Publisher Elsevier
Contributing office(s) Contaminant Biology Program, John Wesley Powell Center for Analysis and Synthesis, Forest and Rangeland Ecosystem Science Center
Description 14 p.
First page 1157
Last page 1170
Country Canada, Mexico, United States
State Alaska, Alberta, Arizona, British Columbia, California, Colorado, Idaho, Mexico, Montana, Nevada, New Mexico, North Dakota, Oregon, Saskatchewan, South Dakota, Utah, Veracruz, Washington, Wyoming
Online Only (Y/N) N
Additional Online Files (Y/N) N