Environmental Engineering Reference
In-Depth Information
Keywords
Water quality
·
Surface water bodies
·
Animal wastewater lagoons
·
Floating vegetated mats
·
Nitrogen
·
Phosphorus
9.1 Introduction
Clean water is a crucial resource for drinking supply, irrigation, industry, transporta-
tion, recreation, fishing, hunting, and support of biodiversity. Pollutant enrichment
of surface water bodies is often attributed to production areas where applied inor-
ganic fertilizers or animal wastes have moved via surface runoff or leaching from the
point of application. This enrichment may result in eutrophication of the water body,
which then places environmental and/or economic burdens on society when remedi-
ation is required. Eutrophication caused by excessive inputs of phosphorus (P) and
nitrogen (N) is the most common impairment of surface waters in the United States
[1], with impairment measured as the area of surface water not suitable for desig-
nated uses. Eutrophication accounts for approximately 50% of the impaired lake
area and 60% of the impaired river reaches in the United States [2], and is the most
widespread pollution problem of U.S. estuaries [3]. Freshwater eutrophication has
been a growing problem for decades [4, 5]. For most temperate estuaries and coastal
ecosystems, N is the element most limiting to primary production and most respon-
sible for eutrophication [3, 6-8]. For inland waters P is generally the most limiting
nutrient for ecosystems with excess P resulting in eutrophication of the water body.
Eutrophication has many negative effects on aquatic ecosystems [9]. The most obvi-
ous consequences are the increased growth of algae and aquatic weeds that interfere
with use of water. Oxygen (O
2
) shortages caused by senescence and decomposition
of nuisance plants cause fish kills.
9.1.1 Nitrogen
Nitrogen (N) contamination of surface and groundwater is a health concern for both
humans and animals. Elevated nitrate (NO
3
-N) concentrations in drinking water
have caused infant death from the disease methomoglobinemia, and toxic effects
on livestock [10, 11]. Infants are most sensitive because bacteria that live in an
infant's digestive tract can reduce NO
3
-N to nitrite (NO
2
-N), causing conversion of
hemoglobin into methemoglobin, which interferes with the oxygen-carrying ability
of blood [11]. Formation of potentially carcinogenic nitrosamines in the soil from
nitrite (NO
2
-N) and secondary amines is also a health concern. Both NO
3
-N and
NO
2
-N have been shown to negatively affect the metabolism of domestic animals
[10, 11].
Nitrate levels greater than 10 parts per million (public health standard) have been
documented in groundwater associated with agricultural activities in New York [12],
Wisconsin [13], Nebraska [14, 15], Arkansas [16], Ontario [17], England [18, 19],
Georgia [20, 21], and Oklahoma [22, 23]. These high concentrations were associated
