Total and monomethyl mercury in fog water from the central California coast

Abstract

Total mercury (HgT) and monomethyl mercury (MMHg) concentrations in fog collected from 4 locations in and around Monterey Bay, California during June‐August of 2011 were 10.7 ± 6.8 and 3.4 ± 3.8 ng L−1respectively. In contrast, mean HgT and MMHg concentrations in rain water from March‐June, 2011 were 1.8 ± 0.9 and 0.1 ± 0.04 ng L−1 respectively. Using estimates of fog water deposition from 6 sites in the region using a standard fog water collector (SFC), depositions of HgT and MMHg via fog were found to range from 42–4600 and 14–1500 ng m−2 y−1, which accounted for 7–42% of HgT and 61–99% of MMHg in total atmospheric deposition (fog, rain, and dry deposition), estimated for the coastal area. These initial measurements suggest that fog precipitation may constitute an important but previously overlooked input of MMHg to coastal environments. Preliminary comparisons of these data with associated chemical, meteorological and oceanic data suggest that biotically formed MMHg from coastal upwelling may contribute to the MMHg in fog water.

Total- and monomethyl-mercury and major ions in coastal California fog water: Results from two years of sampling on land and at sea

“…In the original work to quantify Hg in marine fog, the CASCC was set to turn on/off at fixed times of day (22:00-09:00 local time), since fog was regularly occurring at night and almost never of sufficient density to collect a sample during the day (Weiss-Penzias et al, 2012). However, this meant that the sampler could have been on for many hours before the onset of fog and thus may have accumulated gases and particles.…”

“…However, in this study, low MMHg concentrations overall were found (0.14 ± 0.10 ng L -1 ), with no seasonal variability that would have been indicative of seasonal DMHg evasion from ocean due to coastal upwelling. Subsequently, summertime marine fog water MMHg concentrations from samples collected in Santa Cruz, California were found to be enhanced (3.4 ± 3.8 ng L -1 , n = 8) relative to rain, with an apparent biotic source of MMHg associated with coastal upwelling (Weiss-Penzias et al, 2012). Similarly, MMHg of marine origin was found to accumulate in lichen on the coast of the Arctic Ocean (St. Pierre et al, 2015) and may represent a health risk to native populations who eat the caribou that feed off of the lichen.…”

“…Fog water drip can make up a significant portion of the hydrologic inputs in a relatively narrow distance from the coast, and because of the Mediterranean climate where summer rainfall is scant, a great diversity of plant and animal species have evolved in this region that rely upon fog water inputs (Sawaske and Freyburg, 2015). Due to relatively high MMHg concentrations found in fog water (Weiss-Penzias et al, 2012), coastal terrestrial ecosystems may be vulnerable to food web Hg accumulations (Ortiz et al, 2014).…”

Fogs: Physical Basis, Characteristic Properties, and Impacts on the Environment and Human Health

“…Weiss-Penzias et al [99] have investigated total mercury (HgT) and monomethyl mercury (MMHg) concentrations in fog water. They reported mean HgT concentrations of 10.7 ± 6.8 ng/L and mean MMHg concentrations of 3.4 ± 3.8 ng/L.…”

Coastal Fog, Climate Change, and the Environment

“…Recent research even shows the presence of methylmercury-a toxic bioaccumulatorin "pristine" coastal fog, which apparently originates naturally from marine aerosol [ Weiss-Penzias et al , 2012 ].…”