Mercury and trace elements in cloud water and precipitation collected on Mt. Mansfield, Vermont

Abstract

The lack of high quality measurements of Hg and trace elements in cloud and fog water led to the design of a new collector for clean sequential sampling of cloud and fog water. Cloud water was collected during nine non-precipitating cloud events on Mt. Mansfield, VT in the northeastern USA between August 1 and October 31, 1998. Sequential samples were collected during six of these events. Mercury cloud water concentrations ranged from 7.5 to 71.8 ng l(-1), with a mean of 24.8 ng l(-1). Liquid water content explained about 60% of the variability in Hg cloud concentrations. Highest Hg cloud water concentrations were found to be associated with transport from the Mid-Atlantic and Ohio River Valley, and lowest concentrations with transport from the north of Mt. Mansfield out of Canada. Twenty-nine event precipitation samples were collected during the ten-week cloud sampling period near the base of Mt. Mansfield as part of a long-term deposition study. The Hg concentrations of cloud water were similar to, but higher on average (median of 12.5 ng l(-1)) than Hg precipitation concentrations (median of 10.5 ng l(-1)). Cloud and precipitation samples were analyzed for fifteen trace elements including Mg, Cu, Zn, As, Cd and Pb by ICP-MS. Mean concentrations were higher in cloud water than precipitation for elements with predominately anthropogenic, but not crustal origin in samples from the same source region. One possible explanation is greater in-cloud scavenging of crustal elements in precipitating than non-precipitating clouds, and greater below-cloud scavenging of crustal than anthropogenic aerosols.

Speciation of Mercury (II) and Methylmercury in Cloud and Fog Water

“…The concentration of Hg(II) used for the model was 0.25 nM. This is equivalent to 50 ng/L, which is within the range of 2.0 to 71.8 ng/L measured in cloud and fog water (Malcolm et al, 2003).…”

Estimation and Mapping of Wet and Dry Mercury Deposition Across Northeastern North America

“…Lawson, 1999;Malcolm and Keeler 2002;Malcolm et al, 2003) indicate that mercury is not enriched with respect to its concentration in precipitation as is the case for more soluble compounds. This behavior is expected given the low RGM and particulate-mercury (H p ) Figure 1.…”

Transplanted Lichen Pseudovernia furfuracea as a Multi-Tracer Monitoring Tool Near a Solid Waste Incinerator in Italy: Assessment of Airborne Incinerator-Related Pollutants

“…Thus, we performed preliminary experiments (data not published) to evaluate the losses of lichen from and the ingress of macrofauna into bags when using a 1-cm mesh nylon netting; our results demonstrated that the impacts of these two processes are negligible in comparison to the increase in area of exposed surface of lichen. Besides, the use of net bags with a very narrow mesh can allow the condensation of cloud water, which is usually higher in pollutant levels than normal deposition; this could therefore enhance the uptake or concentrations reflected in the lichen measurements (Malcolm et al 2003).…”