Casco Bay Air Deposition Monitoring Project

The Casco Bay Estuary Partnership is devoted to protecting and
restoring the water quality, and fish and wildlife habitat of the Casco Bay
ecosystem, while ensuring compatible human uses. 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.

Atmospheric deposition (estimated dry and wet deposition) of inorganic nitrogen
is a significant source of pollution to Casco Bay.

Atmospheric deposition of mercury is the dominant source of mercury to the
Casco Bay.

From 1998 to 2001, there was a trend of declining annual wet deposition of
mercury, ammonia, and nitrate totals at Casco Bay.

Other Instruments: MDN,NADP, IMPROVE samplers

Type: Estuary

Waterbody or Watershed Names: Casco Bay