High mercury wet deposition at a “clean Air” site in Puerto Rico

Environmental Science & Technology
By: , and 

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Abstract

Atmospheric mercury deposition measurements are rare in tropical latitudes. Here we report on seven years (April 2005 to April 2012, with gaps) of wet Hg deposition measurements at a tropical wet forest in the Luquillo Mountains, northeastern Puerto Rico, U.S. Despite receiving unpolluted air off the Atlantic Ocean from northeasterly trade winds, during two complete years the site averaged 27.9 μg m–2 yr–1 wet Hg deposition, or about 30% more than Florida and the Gulf Coast, the highest deposition areas within the U.S. These high Hg deposition rates are driven in part by high rainfall, which averaged 2855 mm yr–1. The volume-weighted mean Hg concentration was 9.8 ng L–1, and was highest during summer and lowest during the winter dry season. Rainout of Hg (decreasing concentration with increasing rainfall depth) was minimal. The high Hg deposition was not supported by gaseous oxidized mercury (GOM) at ground level, which remained near global background concentrations (<10 pg m–3). Rather, a strong positive correlation between Hg concentrations and the maximum height of rain detected within clouds (echo tops) suggests that droplets in high convective cloud tops scavenge GOM from above the mixing layer. The high wet Hg deposition at this “clean air” site suggests that other tropical areas may be hotspots for Hg deposition as well.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title High mercury wet deposition at a “clean Air” site in Puerto Rico
Series title Environmental Science & Technology
DOI 10.1021/acs.est.5b02430
Volume 49
Issue 20
Year Published 2015
Language English
Publisher American Chemical Society
Contributing office(s) NH/VT office of New England Water Science Center, Toxic Substances Hydrology Program
Description 9 p.
First page 12474
Last page 12482
Country United States
State Puerto Rico
Other Geospatial Luquillo Mountains
Online Only (Y/N) N
Additional Online Files (Y/N) N
Google Analytic Metrics Metrics page
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