7
1 Eutrophication: Challenges and Solutions
agricultural fields are key components of nonpoint source
pollution of water bodies and can accelerate eutrophication
of surface waters. In an experiment, the fertilizer input with
near-surface hydraulic gradient (free drainage, saturation, artesian seepage with and without rain) tested for contribution
to the water quality problems. The total NO 3 –N loss from
free drainage treatment was 0.01 % of the applied N while
artesian seepage with and without rain resulted into 16 and
11 % loss of NO 3 –N, respectively (Zheng et al. 2004). Sewage from New York City contributes an estimated 67 % of
the N inputs to Long Island Sound annually. Sewage treatment plants deliver from 40–80 % of the N to Kaneohe Bay,
Hawaii, and to Narragansett Bay, Rhode Island (Nixon and
Pilson 1983; National Research Council 1993). It is estimated that sewage contributes only 12 % of the flux of N from
the North American continent to the North Atlantic Ocean
(Howarth et al. 1996). Only ca. 25 % of the N and P inputs to
Chesapeake Bay come from wastewater treatment plants and
other point sources (Boynton et al. 1995). Nonpoint source
pollution of surface water by nitrate from agricultural activities is a major environmental problem in USA. An agricultural watershed in the Iowa Loess Hills with a 23 years history of annual corn production with average N fertilization
has been studied. Head cut seepage was transported through
a natural riparian zone and observed as weir base flow; surface runoff was measured separately. The concentration of
nitrate carried from the field in basin drainage steadily increased from < 1 mg/l in 1969 to > 20 mg/l in 1991 (Steinheimer et al. 1998).
The groundwater protection and eutrophication are significant environmental issues on the European agenda. The
main source of nitrogen in Europe is leaching from agricultural fields caused by excess fertilizer inputs. Since the late
1970s, nitrate concentrations have increased all over Europe
reflecting intensification of agriculture. High nitrate concentrations in ground and surface water make it unsuitable for
drinking. High nitrogen inputs in the marine environment
cause eutrophication and results in increased algal growth,
altered biological communities, and deoxygenation (Iverson
et al. 1998). Nitrates from fertilizers account for nearly 50 %
of the surface water acidification in watershed. Owing to
these N inputs, there is a strong need to cut in NO X and NH X
emissions (Hessen et al. 1997a, b).
The mathematical model has shown that phosphorus and
nitrogen input is likely to be reduced to the extent of 50 and
85 %, respectively into the Swan and Canning Rivers (Australia) provided agricultural land is reforested. The urbanization has also been reported to be a major cause of phosphorus
and nitrogen input. During the next 10 years the urbanization
is likely to increase 4 and 12 % of phosphorus and nitrogen
loads, respectively in the estuary of those rivers (Zammit
et al. 2006).
Biological transformations of N added to ponds in the
form of inorganic or organic fertilizers and formulated feeds
were found to dominate the nitrogen biogeochemistry of
aquaculture ponds. Nitrogen application in excess of pond
assimilatory capacity can lead to the deterioration of water
quality through the accumulation of nitrogenous compounds
(e.g., ammonia and nitrate) with toxicity to fish or shrimp
(Hargreaves 1998).
1.4.1.1 N-Cycle
Increased use of fertilizers in agriculture has led to the altered nitrogen cycle across the globe. The excessive use of
fertilizers increased emissions and transboundary air pollution. During the 1900s, over 50 % of the nitrogen deposition
over Republic of Korea (South Korean Peninsula) was imported from abroad. The N inputs from atmospheric deposition, fertilizers, biological fixation, imports of food, feed and
products, outputs in riverine export, crop uptake, denitrification, volatilization, runoff, sedimentation, and sea water
exchange have been quantified. The nitrogen budgets were
found positive with N inputs exceeding outputs. The excess
N inputs in turn increased N storage in ground water. Annual
accumulation of N in the Yellow Sea including inputs from
South Korea and other drainage areas was 1,229 kt per year.
The human-derived N inputs lead to excessive eutrophication and pollution of Yellow Sea (Bashkin et al. 2002).
Human activities have greatly altered the global nitrogen
(N) cycle and accelerated the rate of N-fixation in landscapes
and delivery of N to water bodies. Using data from the early
1990s, Boyer et al. (2002) quantified N inputs in 16 catchments from those of atmospheric deposition, nitrogenous
fertilizer applications, biological nitrogen fixation, and imports of N in agricultural products. Net atmospheric deposition was found to be the largest N source (> 60 %) to the
forested basins of Northern New England. However, in most
populated regions of Southern New England, the net import
of N in food was the largest N source. The agricultural inputs
were the dominant N sources in the mid-Atlantic regions
(Boyer et al. 2002).
1.4.1.2 Impact of Phosphorus
Phosphorus (P) inputs are essential for cost-effective crop
and livestock agriculture. However, P inputs can also increase the biological productivity of surface waters by accelerating eutrophication that is responsible for the impairment of surface water quality and restricts water use for
fisheries, recreation, industry, and drinking because of increased growth of undesirable algae and aquatic weeds and
the oxygen shortages caused by their death and decomposition. Phosphorus is mainly responsible for eutrophication of
most fresh water around the world (Schindler 1977; Sharpley
et al. 1994). Although nitrogen and carbon are also essential
to the growth of aquatic biota, most attention has focused on
1 Eutrophication: Challenges and Solutions
agricultural fields are key components of nonpoint source
pollution of water bodies and can accelerate eutrophication
of surface waters. In an experiment, the fertilizer input with
near-surface hydraulic gradient (free drainage, saturation, artesian seepage with and without rain) tested for contribution
to the water quality problems. The total NO 3 –N loss from
free drainage treatment was 0.01 % of the applied N while
artesian seepage with and without rain resulted into 16 and
11 % loss of NO 3 –N, respectively (Zheng et al. 2004). Sewage from New York City contributes an estimated 67 % of
the N inputs to Long Island Sound annually. Sewage treatment plants deliver from 40–80 % of the N to Kaneohe Bay,
Hawaii, and to Narragansett Bay, Rhode Island (Nixon and
Pilson 1983; National Research Council 1993). It is estimated that sewage contributes only 12 % of the flux of N from
the North American continent to the North Atlantic Ocean
(Howarth et al. 1996). Only ca. 25 % of the N and P inputs to
Chesapeake Bay come from wastewater treatment plants and
other point sources (Boynton et al. 1995). Nonpoint source
pollution of surface water by nitrate from agricultural activities is a major environmental problem in USA. An agricultural watershed in the Iowa Loess Hills with a 23 years history of annual corn production with average N fertilization
has been studied. Head cut seepage was transported through
a natural riparian zone and observed as weir base flow; surface runoff was measured separately. The concentration of
nitrate carried from the field in basin drainage steadily increased from < 1 mg/l in 1969 to > 20 mg/l in 1991 (Steinheimer et al. 1998).
The groundwater protection and eutrophication are significant environmental issues on the European agenda. The
main source of nitrogen in Europe is leaching from agricultural fields caused by excess fertilizer inputs. Since the late
1970s, nitrate concentrations have increased all over Europe
reflecting intensification of agriculture. High nitrate concentrations in ground and surface water make it unsuitable for
drinking. High nitrogen inputs in the marine environment
cause eutrophication and results in increased algal growth,
altered biological communities, and deoxygenation (Iverson
et al. 1998). Nitrates from fertilizers account for nearly 50 %
of the surface water acidification in watershed. Owing to
these N inputs, there is a strong need to cut in NO X and NH X
emissions (Hessen et al. 1997a, b).
The mathematical model has shown that phosphorus and
nitrogen input is likely to be reduced to the extent of 50 and
85 %, respectively into the Swan and Canning Rivers (Australia) provided agricultural land is reforested. The urbanization has also been reported to be a major cause of phosphorus
and nitrogen input. During the next 10 years the urbanization
is likely to increase 4 and 12 % of phosphorus and nitrogen
loads, respectively in the estuary of those rivers (Zammit
et al. 2006).
Biological transformations of N added to ponds in the
form of inorganic or organic fertilizers and formulated feeds
were found to dominate the nitrogen biogeochemistry of
aquaculture ponds. Nitrogen application in excess of pond
assimilatory capacity can lead to the deterioration of water
quality through the accumulation of nitrogenous compounds
(e.g., ammonia and nitrate) with toxicity to fish or shrimp
(Hargreaves 1998).
1.4.1.1 N-Cycle
Increased use of fertilizers in agriculture has led to the altered nitrogen cycle across the globe. The excessive use of
fertilizers increased emissions and transboundary air pollution. During the 1900s, over 50 % of the nitrogen deposition
over Republic of Korea (South Korean Peninsula) was imported from abroad. The N inputs from atmospheric deposition, fertilizers, biological fixation, imports of food, feed and
products, outputs in riverine export, crop uptake, denitrification, volatilization, runoff, sedimentation, and sea water
exchange have been quantified. The nitrogen budgets were
found positive with N inputs exceeding outputs. The excess
N inputs in turn increased N storage in ground water. Annual
accumulation of N in the Yellow Sea including inputs from
South Korea and other drainage areas was 1,229 kt per year.
The human-derived N inputs lead to excessive eutrophication and pollution of Yellow Sea (Bashkin et al. 2002).
Human activities have greatly altered the global nitrogen
(N) cycle and accelerated the rate of N-fixation in landscapes
and delivery of N to water bodies. Using data from the early
1990s, Boyer et al. (2002) quantified N inputs in 16 catchments from those of atmospheric deposition, nitrogenous
fertilizer applications, biological nitrogen fixation, and imports of N in agricultural products. Net atmospheric deposition was found to be the largest N source (> 60 %) to the
forested basins of Northern New England. However, in most
populated regions of Southern New England, the net import
of N in food was the largest N source. The agricultural inputs
were the dominant N sources in the mid-Atlantic regions
(Boyer et al. 2002).
1.4.1.2 Impact of Phosphorus
Phosphorus (P) inputs are essential for cost-effective crop
and livestock agriculture. However, P inputs can also increase the biological productivity of surface waters by accelerating eutrophication that is responsible for the impairment of surface water quality and restricts water use for
fisheries, recreation, industry, and drinking because of increased growth of undesirable algae and aquatic weeds and
the oxygen shortages caused by their death and decomposition. Phosphorus is mainly responsible for eutrophication of
most fresh water around the world (Schindler 1977; Sharpley
et al. 1994). Although nitrogen and carbon are also essential
to the growth of aquatic biota, most attention has focused on