Modeling and mapping of atmospheric mercury deposition in adirondack park, new york.

Jiaoyan Huang,Xue Yu,Thomas M Holsen,Charles T Driscoll,Bradley D Blackwell

doi:10.1371/journal.pone.0059322

Abstract

The Adirondacks of New York State, USA is a region that is sensitive to atmospheric mercury (Hg) deposition. In this study, we estimated atmospheric Hg deposition to the Adirondacks using a new scheme that combined numerical modeling and limited experimental data. The majority of the land cover in the Adirondacks is forested with 47% of the total area deciduous, 20% coniferous and 10% mixed. We used litterfall plus throughfall deposition as the total atmospheric Hg deposition to coniferous and deciduous forests during the leaf-on period, and wet Hg deposition plus modeled atmospheric dry Hg deposition as the total Hg deposition to the deciduous forest during the leaf-off period and for the non-forested areas year-around. To estimate atmospheric dry Hg deposition we used the Big Leaf model. The average atmospheric Hg deposition to the Adirondacks was estimated as 17.4 g m yr with a range of −3.7–46.0 g m yr. Atmospheric Hg dry deposition (370 kg yr) was found to be more important than wet deposition (210 kg yr) to the entire Adirondacks (2.4 million ha). The spatial pattern showed a large variation in atmospheric Hg deposition with scattered areas in the eastern Adirondacks having total Hg deposition greater than 30 μg m−2 yr−1, while the southwestern and the northern areas received Hg deposition ranging from 25–30 μg m−2 yr−1.

Highlights

Ecosystems of the Adirondack Park in New York State, USA, have been substantially affected by mercury (Hg) contamination and the region is considered to be a ‘‘biological Hg hotspot’’ [1,2,3]
Wet Hg deposition is well monitored by Mercury Deposition Network (MDN) at 112 currently active sites as part of the National Atmospheric Deposition Program (NADP) sites in North America [9]
We developed a modified scheme, or ‘‘surface receptor’’ model to estimate atmospheric Hg deposition to the Adirondacks based on both measured atmospheric Hg concentrations; wet, litterfall and throughfall Hg deposition; and numerical modeling of atmospheric Hg dry deposition velocities

Summary

Introduction

Ecosystems of the Adirondack Park in New York State, USA, have been substantially affected by mercury (Hg) contamination and the region is considered to be a ‘‘biological Hg hotspot’’ [1,2,3]. There are limited direct anthropogenic Hg emission sources within or near the Park, and atmospheric deposition is the predominant Hg input. As a result it is important to quantify the spatial pattern of atmospheric Hg deposition to evaluate the magnitude of Hg inputs as well as the factors driving landscape variations of Hg contamination in the terrestrial and aquatic ecosystems [4]. Atmospheric Hg input to the Earth’s surface is via wet and dry deposition [6,8]. There are limited measurements of the spatial variations of atmospheric Hg concentrations and Hg dry deposition [10,11].

Methods

Results

Conclusion