Inflow, Chemistry and Deposition of Mercury to the West Coast of the United StatesEPA Grant Number: R829797
Title: Inflow, Chemistry and Deposition of Mercury to the West Coast of the United States
Investigators: Jaffe, Daniel , Prestbo, Eric
Institution: University of Washington
EPA Project Officer: Hunt, Sherri
Project Period: June 1, 2002 through June 1, 2005
Project Amount: $756,774
RFA: Mercury: Transport, Transportation, and Fate in the Atmosphere (2001) RFA Text | Recipients Lists
Research Category: Mercury , Air Quality and Air Toxics , Safer Chemicals , Air
The focus of this work is to better understand the role of global sources on Hg deposition in the United States. Previously we have shown that industrial emissions in Asia can be transported to the U.S. in 5-10 days. To investigate the significance of global mercury sources on the U.S., we will make observations of Hg0, Reactive gaseous mercury (RGM) and particulate (PHg) to address the following questions:
- What is the contribution of Asian Hg sources to concentrations and deposition in the U.S.? During which seasons is the transport strongest?
- What is the role of marine boundary layer processing on the Hg cycle? How is this processing different in the free troposphere?
- What is the flux of Hg0, PHg and RGM into the United States from external sources and how does the mercury speciation profile change with changing air mass source region?
- What is the chemical speciation of mercury in rain as air arrives to the United States and how does this change with changing air mass type and chemistry?
- Are current atmospheric models accurately predicting mercury fluxes, air speciation and cloud water chemistry at the in-flow boundary to their model domain?
We will measure Hg0, PHg and RGM at a coastal site on the Northwest tip of Washington state, the Cheeka Peak Observatory. This is one of the cleanest background air monitoring sites in the continental U.S. In addition we will measure these compounds in the vertical domain using a small aircraft that is available for this purpose. Our past work has shown that we can identify numerous industrial pollutants arriving to the west coast of the U.S. from sources in Asia. In this project we will extend this work to consider elemental and reactive forms of mercury. In addition we will examine the deposition of Hg by measuring the concentration and speciation in rainwater collected at the Cheeka Peak location.
This project will help determine the degree which global sources contribute to mercury deposition in the U.S. This work will be the first ever to focus on this topic. From our data, it should be possible to quantify the flux of mercury into the U.S. from global sources and the importance of those sources on deposition in the U.S.