Recipient Organization
STATE UNIV OF NEW YORK
(N/A)
SYRACUSE,NY 13210
Performing Department
Chemistry
Non Technical Summary
The project will investigate the climatic, terrestrial, and anthropogenic factors that have influenced the decadal pattern in Hg wet deposition in upstate NY. Contributions to Hg wet deposition from decreases in anthropogenic emissions (e.g., decreases in coal-fired power plants & waste incinerators emissions) in NYS and nation-wide using the Community Multiscale Air Quality (CMAQ) model will be assessed with 1 an algorithm depicting state-of-the art Hg chemistry mechanisms and up-to-date Hg emission inventories.Additionally, the project will examine meteorological influence on trends of wet Hg deposition identified in the first task. The Northeast, including the Adirondacks, is experiencing long term increases in temperature and precipitation. The project will drive CMAQ with a constant annual cycle of precipitation and wind vs. realistic annual cycles for a multiyear time period to characterize and quantify the impacts of inter-annual variability of these two (2) climate variables on Hg wet deposition.Finally, throughfall, litterfall, and leaf tissue Hg concentrations and soil evasion data that have been collected at intervals will be used to constrain modeled Hg dry deposition. Total Hg deposition using measured foliar Hg accumulation, litter Hg inputs, throughfall Hg, and wet Hg deposition will be estimated. The difference between measurement-derived and modeled values will provide the range of uncertainty in modeled dry deposition and soil evasion.Awarded Start Date: 1/1/15Sponsor: NYS Energy Research and Development Authority
Animal Health Component
(N/A)
Research Effort Categories
Basic
100%
Applied
(N/A)
Developmental
(N/A)
Goals / Objectives
The major goals of this project will be answered by the following questions:1) why has Hg wet deposition not responded to decreases in anthropogenic emissions in the U.S.?, and; 2) are changes in the relative importance of domestic and global emissions shaping ambient concentrations of speciated Hg in NYS?
Project Methods
Task 1. Identification of mercury (Hg) trendsThe Research Foundation for the State University of New York on behalf of the State University of New York College of Environmental Science and Forestry (hereafter the "Contractor) shall first identify trends in Hg wet deposition flux and Hg concentrations in precipitation at the Huntington Wildlife Forest (HWF) for the period 1999 -2015, as well as interannual variability in atmospheric concentrations of speciated Hg for the period of data availability. The wet deposition data started in December 1999 and is ongoing. Measurement data of atmospheric concentrations started in spring 2006. Previous studies have examined trends in wet deposition flux and precipitation concentrations of Hg over shorter periods ranging from 3 - 6 years, and trends in atmospheric concentrations at the site over a period of one year only. The Contractor shall evaluate trends over a 16-year period (1999 -2015) for wet deposition and almost ten (10) years (2006 -2015) for atmospheric concentrations. Trends to be identified and quantified by the Contractor for the HWF site are expected to be more statistically robust.Task 2. Simulations of in- and out-of-state source contributions to Hg wet deposition at HWFThe Contractor shall assess contributions to Hg wet deposition from decreases in anthropogenic emissions (e.g., decreases in coal-fired power plants & waste incinerators emissions) in NYS and nation-wide using the Community Multi-scale Air Quality (CMAQ) model with an algorithm depicting state-of-the-art Hg chemistry mechanisms and up-to-date Hg emission inventories. Hg wet deposition largely consists of reactive gaseous Hg (ROM) and particulate-borne Hg (PBM), which result from oxidation of gaseous elemental Hg (Hg0 . To best simulate concentrations of speciated Hg; a model needs to include Hg reactions that depict Hg transformations accurately.In the literature, most models have over-simplistic chemical schemes, often using outdated or incorrect kinetic data, and including reactions that do not theoretically occur in the atmosphere. The Contractor has developed atmospheric Hg chemistry mechanisms with the most up-to-date kinetic data, reaction pathways, and a sophisticated gas-particle partitioning scheme, which will illustrate atmospheric Hg transformations with the best current scientific understanding.Model simulations shall be conducted by the Contractor in two (2) domains identified as Domain 1 and Domain 2 (Figure 1). The "mother" domain is for global model GEOS Chem output with a horizontal resolution of 0.5° x 0.6667°' which shall leverage the Contractors collaboration with Dr. Lyatt Jaegle of University of Washington. Dr. Jaegle's group has GEOS-Chem half degree simulations for the time period of 2004- 2010 over the "mother" domain as shown in Figure, 1. TheGEOS-Chem output shall be used by the Contractor to account for global influence on the northeastern U.S. by constraining the CMAQ simulations in Domain 1 with a horizontal resolution of 12 km x 12 km, CMAQ simulations in Domain 2 with a horizontal resolution of 4 km x 4 km shall be constrained by the Contractor via the Domain 1 simulations; Domain 2 is largely comprised of NYS, with HWF covered by nearly four (4) grids(of 4 km x4 km) in Domain 2, sufficient resolution for this study.The Contractor's box model has been evaluated systematically using a total of 83 cases from measurements in inland, coastal, and marine environments, when atmospheric chemistry was dominant. The model proved to be able to simulate over half of observed diurnal cycles very well and under predict the majority of the other half. This is a major improvement compared to what CMAQ could do, which could hardly capture observed reactive gaseous mercury (RGM) diurnal variation. These evaluation results among others have been written up in a manuscript that is going to be submitted soon . One of the key findings from this box modeling study is that the current gas-particle partitioning mechanism is inadequate. The Contractor is presently putting a new gas-particle scheme into the box model to further improve simulation of oxidized Hg, which shall then be coupled with CMAQ to improve the Hg chemistry and gas particle partitioning in CMAQ; The improved CMAQ shall be used by the Contractor for this project:The Contractor shall first evaluate CMAQ performance using MDN and Atmospheric Mercury Network (AMNet) measurement data. Model evaluation results shall be presented by the Contractor not only with a standard set of statistical metrics but also examination of processes. With regard to the latter, the Contractor shall evaluate CMAQ's ability, in both Domains 1 and 2, of simulating the .seasonal, annual, and year-to-year variation in and spatial distributions of total Hg wet deposition flux with respect to both patterns and magnitude. For atmospheric concentrations of speciated Hg, the Contractor shall also examine if the model can capture the diurnal variation, which could hardly be captured by CMAQ in the literature. In particular,1 the Contactor shall assess the model's ability to reproduce observed long-term trends in Hg total wet deposition and concentrations in precipitation.