Six-year trend (1990-1995) of wet mercury deposition in the upper Midwest, USA
Glass GE and Sorensen JA. 1999. Six-year trend (1990-1995) of wet mercury deposition in the upper Midwest, USA. Environmental Science & Technology. 33(19):3303-3312
Total wet mercury deposition was monitored weekly at six Upper Midwest, USA sites for a period of six years, 1990-1995, to assess temporal and spatial patterns and contributions to surface waters. Annual wet mercury deposition averaged 7.4 ug Hg/m2.yr and showed significant variations between sites and increased trends averaging 0.60 ug Hg/m2.yr (8%/yr) over the period (p<0.0001). Warm (rain) season wet mercury deposition was found to average 77% of total annual wet deposition. Warm (rain) and cold (snow) season trends showed increases of 0.31 (5.5%/yr) and 0.29 ug Hg/m2.yr (17%/yr), respectively (p<0.01). Average annual precipitation depth showed a nonsignificant increase of 0.25 cm/yr (0.4%/yr) for the period. Differences in precipitation depth, mercury concentrations, and wet mercury deposition among sites was noted. Methymercury wet deposition, measured in 36 weekly samples, averaged about 0.18 ng/L (1.5% of total mercury) in rain and strongly correlated with total mercury, major ions, and precipitation depth.
- Type
- Journal Article
- Authors
- Glass, Gary; Sorensen, John
- Units
- APIS , ARD , ISRO , SACN , VOYA
- Keywords
- ARD_Park-Air-Info_Collection, Contaminants, Deposition, Mercury, Mercury (Hg), methylmercury, Michigan, Minnesota, North Dakota, Sampling, Toxics