4. Nutrient Contamination
Fossil fuels also contribute to nitrogen or nutrient pollution from the breakdown of nitrogen oxides, which are produced by the combustion process itself. Even internal combustion engines burning hydrogen produce some nitrogen oxides, for example, though in much lower quantities. Along with artificial fertilizers and concentrated organic sewage, the breakdown of nitrogen oxides can contribute to algal blooms, blue baby syndrome (which kills human infants) and eutrophication events in bodies of water.
Concerns over contamination of groundwater and streams from nutrients is not new, but it continues to be among the most significant and widespread of the environmental issues faced by government agencies at all levels as well as the private sector. Results from the first phase of NAWQA water-quality assessments provide the following insights on current conditions and trends with respect to nutrients in streams and groundwater, the factors affecting regional patterns and vulnerability of hydrologic systems to nutrient contamination, and implications for environmental management.
Phosphorous contamination represents a nutrient that contributes to the excess growth of algae blooms, such as the increased reporting of cyanobacteria (blue-green algae) growth which can be toxic to human and animal life.
Nitrate concentrations were at safe levels for drinking (less than 10 milligrams per liter) in most streams and major aquifers sampled. The finding that 15 percent of the wells in 4 of 33 major aquifers sampled had concentrations above the drinking water standard is cause for some concern. The most significant nitrate contamination occurred in rural agricultural areas where aquifers are shallow and vulnerable to surface contamination. This is a potential health concern where shallow ground water is used for domestic drinking-water supply. Only one percent of public supply wells exceeded the nitrate drinking-water standard. Why?-because public supply wells tend to be deeper, withdrawing older ground water, and (or) are protected by relatively impermeable geologic materials, such as clay or dense, unfractured rocks. More than half of all streams sampled had phosphorus concentrations above the USEPA desired goal intended to control algal growth. Nitrogen and phosphorus concentrations in 75 percent of the agricultural and urban streams sampled commonly reached levels that can stimulate excessive growth of algae.