【摘 要】
：
Wet deposition of mercury,Hg,was monitored on a daily-event basis for 18 months(July 2009-Dec 2010)at the G.T.Craig site,GTC,(41.4939,-81.6785)in urban Cleveland and at the Lake Chippewa,LCM,(41.0740,
【机 构】
：
University of Michigan Air Quality Laboratory,Ann Arbor,MI,USA
【出 处】
：
The 17th International Conference on Heavy Metals in the Env
论文部分内容阅读
Wet deposition of mercury,Hg,was monitored on a daily-event basis for 18 months(July 2009-Dec 2010)at the G.T.Craig site,GTC,(41.4939,-81.6785)in urban Cleveland and at the Lake Chippewa,LCM,(41.0740,-81.9037)rural site during the Cleveland Multiple Air Pollutant Study,CMAPS.The aim of the study was to investigate sources and distribution of air pollutants to the metropolitan area which is classified as a residual non-attainment area by the US EPA.Samples were obtained using an Automated Sequential Precipitation Sampler,ASPS,which facilitates collection of unattended wet-only event-precipitation sampling.Over the 18 month period GTC(N = 98)demonstrated a higher precipitation depth 96.9 cm compared to 75.1 cm at LCM(N = 81).The volume weighted mean concentration of Hg in samples was also higher at GTC 11.1 ng/L compared to 9.0 ng/L at LCM.Overall,wet deposition at the urban site was greater by 37%,with a total Hg deposition amount of 10.7 ?g/m2 versus 6.8 ?g/m2 at the rural site during the 18-month period of this study.Wet deposition at both sites was found to be higher during the warmer seasons consistent with greater scavenging of mercury from the atmosphere due to convective storms that are typically seen during warmer months at site latitudes.Mean wet deposition at the GTC site was 0.11 ± 0.13 ?g/m2 while it was 0.08 ± 0.11 ?g/m2 at LCM,and maximum wet deposition was 0.74 ? g/m2 and 0.56 ?g/m2 respectively at the sites.The GTC site had 16 events where deposition was greater than 0.2 ?g/m2 while the LCM site had 10 such events and for both sites most of these occurred during the spring summer months.For these events,precipitation depths at the GTC site exhibited a greater range,0.6 – 4.6 cm versus 1.47 – 4.59 cm at LCM,and the range of mercury concentrations during these deposition events at GTC was also larger,7 – 71.1 ng/L compared to a range of 6.1 – 19.8 ng/L at LCM.Overall,these results indicate a dichotomy in mercury deposition at the urban and rural site that is most likely due to greater impacts at the urban GTC site due to proximity to numerous local anthropogenic sources of mercury.
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