Casco Bay Air Deposition Monitoring Project

Atmospheric deposition is a natural process by which pollutants are transferred from air to soil, surface water, sediment, and groundwater and potentially to living organisms. Wet and dry deposition processes (e.g., rain out, wash out, impaction, adsorption, and absorption) remove particulate and gaseous pollutants from the atmosphere and deposit them on the surface of water bodies, vegetation, buildings and structures, and soil.

Transfer of these pollutants from water bodies to sediment occurs through adsorption and sedimentation. Polluted water and sediment lead to undesirable health and environmental impacts, such as mercurycontaminated fish, harmful algal blooms, beach closures, etc. The current role of atmospheric deposition, as it relates to nitrogen, mercury, and fine particulate matter (PM2.5) pollution in Casco Bay, needed to be better understood and quantified.