Gaseous oxidized mercury dry deposition measurements in the southwestern USA: a comparison between Texas, eastern Oklahoma, and the Four Corners area.

Mark E Sather,Kara L Allen,Johnson Mathew,Larry Scrapper,April Hathcoat,Ryan Callison,Shaibal Mukerjee,Jacque Adam,Luther Smith,Robert Brunette,Clarence Jackson,Danielle Keese,Gerard Van Der Jagt,Jason Karlstrom,Philip Ketcher

doi:10.1155/2014/580723

Abstract

Gaseous oxidized mercury (GOM) dry deposition measurements using aerodynamic surrogate surface passive samplers were collected in central and eastern Texas and eastern Oklahoma, from September 2011 to September 2012. The purpose of this study was to provide an initial characterization of the magnitude and spatial extent of ambient GOM dry deposition in central and eastern Texas for a 12-month period which contained statistically average annual results for precipitation totals, temperature, and wind speed. The research objective was to investigate GOM dry deposition in areas of Texas impacted by emissions from coal-fired utility boilers and compare it with GOM dry deposition measurements previously observed in eastern Oklahoma and the Four Corners area. Annual GOM dry deposition rate estimates were relatively low in Texas, ranging from 0.1 to 0.3 ng/m2h at the four Texas monitoring sites, similar to the 0.2 ng/m2h annual GOM dry deposition rate estimate recorded at the eastern Oklahoma monitoring site. The Texas and eastern Oklahoma annual GOM dry deposition rate estimates were at least four times lower than the highest annual GOM dry deposition rate estimate previously measured in the more arid bordering western states of New Mexico and Colorado in the Four Corners area.

Highlights

Atmospheric mercury emissions deposit to the earth through both wet and dry processes, and wet mercury deposition measurements have been taken routinely for over a decade in North America [1,2,3,4]
The research objective was to investigate gaseous oxidized mercury (GOM) dry deposition in areas of Texas impacted by emissions from coalfired utility boilers and compare it with GOM dry deposition measurements previously observed in eastern Oklahoma and the Four Corners area
Annual GOM dry deposition rate estimates were relatively low in Texas, ranging from 0.1 to 0.3 ng/m2h at the four Texas monitoring sites, similar to the 0.2 ng/m2h annual GOM dry deposition rate estimate recorded at the eastern Oklahoma monitoring site

Summary

Introduction

Atmospheric mercury emissions deposit to the earth through both wet and dry processes, and wet mercury deposition measurements have been taken routinely for over a decade in North America [1,2,3,4]. Gaseous elemental mercury (GEM) is relatively insoluble and inert, with an atmospheric lifetime of 0.5–2 years leading to global transport [12]. GOM and particulate mercury have much higher deposition velocities leading to local and regional deposition scales [13]. In many areas a significant portion of total dry deposition of mercury may consist of GOM [14], and GOM can readily deposit to water, soils, and vegetation and is more water soluble than the more abundant GEM constituent [13].

Objectives

Methods

Results