What is the utility of measuring gaseous HgII dry deposition using Aerohead samplers?: A review

The most efficient way to quantify HgII inputs to ecosystems is to measure wet and dry deposition. Wet deposition of HgII is determined by measuring Hg concentrations and the volume of precipitation. Dry deposition of HgII is determined through direct measurement and/or determined indirectly by measuring air concentrations and using model-generated deposition velocities. Here, data collected using an Aerohead sampler holding cation exchange membranes are summarized, and the utility of this method for understanding dry deposition, and other measurements and processes is discussed. This analysis includes information from publications, and recent data collected at Guadalupe Mountains National Park, Texas, USA, and Amsterdam Island, Southern Indian Ocean. This method primarily measures gaseous HgII and little particulate-bound Hg. The Aerohead method is useful for looking at large-scale trends in deposition, verifying Hg depletion events, calculating dry deposition velocities for compounds with specific chemistry, and identification of sources of HgII. At numerous locations in the western USA, deposition rates were greater at higher elevations due to elevated concentrations associated with longrange transport of atmospheric pollution. When used in tandem with the Reactive Mercury Active System or a dual-channel system, more accurate deposition velocities - that vary as a function of GOM compound chemistry - can be calculated.

Automated summary

The most efficient way to quantify HgII inputs to ecosystems is to measure wet and dry deposition. This study discusses the use of the Aerohead sampler and cation exchange membranes for collecting data on dry deposition and its utility for understanding other measurements and processes. The analysis includes data from publications and recent data collected at different locations.