Threats to Aquatic Environments - Air Pollution Affects Water Quality

Water quality can be affected by pollutants emitted into the air during fossil fuel combustion or industrial, agricultural and forestry activities. Nutrients, oil and dirt particles, and some chemicals (such as mercury) are known to be carried through the air and deposited onto waterbodies. This process is called atmospheric disposition. In addition, aquatic environments can be harmed indirectly, through changes in climate and atmospheric phenomena due to human activities.

Phytoplankton

Phytoplankton (planktonic plant life) are microscopic photosynthesizing species that form the basis of nearly all marine food chains. (See Figure 4.11.) In many parts of the world, phytoplankton seems to be declining. The most severe damage appears to be in the waters off Antarctica, FIGURE 4.9 Fish consumption advisories due to mercury, 2004 "Fish Consumption Advisories for Mercury," in Ten Individual Slides Providing National Summaries and Statistics for the 2004 National Listing of Fish Advisories (NLFA) Database, U.S. Environmental Protection Agency, September 15, 2005, http://epa.gov/waterscience/fish/advisories/2004slides.ppt#3 (accessed February 11, 2006)where phytoplankton are severely depleted. The depletion of phytoplankton has implications all the way up the food chain, affecting not only the zooplankton that consume them but larger species such as penguins, seals, and whales. Scientists believe that phytoplankton declines are a result of the thinning atmospheric ozone layer (caused by industrial pollutants such as chlorofluorocarbons, or CFCs), which allows increasing amounts of ultraviolet radiation to penetrate the Earth's surface. Ultraviolet radiation decreases the ability of phytoplankton to photosyn-thesize and also damages their genetic material.