4
M. N. Khan and F. Mohammad
In China, meat production rose by 127 % between 1990
and 2002 (FAO 2009), but fewer than 10 % of an estimated
14,000 intensive livestock operations have installed pollution controls (Ellis 2007). In the Black Sea region, one swine
operation, which subsequently closed, had over 1 million
pigs and generated sewage equivalent to a town of 5 million
people (Mee 2006).
Aquaculture is one of the growing sources of nutrient pollution. Annual aquaculture production worldwide increased
by 600 %, from 8 million tons in 1985 to 48.2 million tons
in 2005. Nearly 43 % of all aquaculture production is within marine or brackish environments, with the remainder
in freshwater lakes, streams, and man-made ponds (FAO
2007). Marine fish and shrimp farming generate concentrated amounts of nitrogen and phosphorus from excrement, uneaten food, and other organic waste. If improperly managed,
aquaculture operations can have severe impacts on aquatic
ecosystems as nutrient wastes are discharged directly into
the surrounding waters. For every ton of fish, aquaculture
operations produce between 42 and 66 kg of nitrogen waste
and between 7.2 and 10.5 kg of phosphorus waste (Strain
and Hargrave 2005).
1.3.1.3 Fossil Fuel and Energy Consumption
Coal-fired power plants, cars, buses, and trucks consume
fossil fuels, which is also a contributor of nutrients. On combustion fossil fuel releases nitrogen oxides into the atmosphere. These oxides of nitrogen contribute to the formation
of smog and acid rain. Nitrogen oxide is redeposited to land
and water through rain and snow, or can settle out of the air
in a process called dry deposition. Fossil fuel combustion
contributes approximately 22 Tg of nitrogen pollution globally every year, approximately one-fifth of the contribution
of synthetic nitrogen fertilizers (MA 2005). In the Baltic Sea,
atmospheric deposition, primarily from burning fossil fuels,
accounts for 25 % of nitrogen inputs (HELCOM 2005). Similarly, in the Chesapeake Bay, atmospheric deposition accounts for 30 % of all nitrogen inputs. In some areas, such as
in the US North Atlantic, atmospheric deposition of nitrogen
can exceed riverine nitrogen inputs to coastal areas (Spokes
and Jickells 2005).
Increasing demand of energy for the increasing population across the globe is one of the direct drivers of eutrophication. Total worldwide energy consumption rose by 33 %
between 1990 and 2005. Currently, more than 86 % of the
world’s energy needs are being met by fossil fuel sources
(EIA 2008). Experts estimate that per capita energy consumption will increase by approximately 18 % between 2005
and 2030, while total global energy consumption will rise
by 50 %; the developing world is projected to account for
the majority of increased energy consumption (EIA 2008).
Fossil fuels are expected to continue meeting approximately
86 % of global energy needs (EIA 2008).
1.3.1.4 Increased Fertilizer Consumption
The increasing population forces to increase the agriculture
production that is accompanied by the additional use of fertilizers. It is expected that between 2002 and 2030 fertilizers
consumption will increase by 40 % (FAO 2000). The majority of the projected increase in global fertilizer consumption
is attributed to the developing world where food production
and adoption of intensive agricultural practices are expected
to increase (FAO 2000). At present, two sources of fertilization commonly used are slurry and synthetic compounds.
Nitrogen and phosphorus losses in surface runoff from fertilized soils depend upon the quantity of transporting water and
the time and rate of fertilizer application. When fertilizers
are applied before a wet period or snowmelt, or on frozen
ground, losses are higher than when fertilization is done in
the spring. Excessive application of fertilizers and bad management practices increase nutrient loss from the soil. Lesser
amounts of nitrogen and phosphorus are lost to the surface
water of judiciously fertilized and well-managed soils.
1.3.1.5 Land-use Transformation
Enhanced food production is coupled with the transformation of forest to crop land. Cropland has experienced a net
global increase of about 3 million ha per year from 1995
to 2002, with over 90 % of the total cropland gains coming
from forests (Holmgren 2006). Agriculture is also the single
largest cause of wetland loss. Approximately 50 % of the
world’s wetlands have been lost since the 1950s. The majority of wetland loss occurred as a result of drainage for agricultural production (OECD/IUCN 1996). According to the
prediction of FAO, land-use conversion for agriculture will
continue, but at a slower pace than in the past (FAO 2002).
Natural landscapes such as forests and wetlands are important for capturing and cycling nutrients. Increasing land-use
conversion reduces the ability of these landscapes to intercept nutrients and leads to greater nutrient losses to local
waterways.
1.3.2 Indirect Drivers of Eutrophication
1.3.2.1 Population Expansion
Although population growth is an indirect driver of eutrophication but it is also the root cause for all types of the drivers
of eutrophication. The global population is predicted to grow
from 6.5 billion in 2005 to nearly 9.2 billion in 2050 with
the majority of population growth occurring in developing
countries (United Nations Population Division 2008). Population growth will increase the demand for food, land, energy, and other natural resources, ultimately leading to greater
agricultural production and increased burning of fossil fuels
to heat homes, power cars, and fuel industry.
M. N. Khan and F. Mohammad
In China, meat production rose by 127 % between 1990
and 2002 (FAO 2009), but fewer than 10 % of an estimated
14,000 intensive livestock operations have installed pollution controls (Ellis 2007). In the Black Sea region, one swine
operation, which subsequently closed, had over 1 million
pigs and generated sewage equivalent to a town of 5 million
people (Mee 2006).
Aquaculture is one of the growing sources of nutrient pollution. Annual aquaculture production worldwide increased
by 600 %, from 8 million tons in 1985 to 48.2 million tons
in 2005. Nearly 43 % of all aquaculture production is within marine or brackish environments, with the remainder
in freshwater lakes, streams, and man-made ponds (FAO
2007). Marine fish and shrimp farming generate concentrated amounts of nitrogen and phosphorus from excrement, uneaten food, and other organic waste. If improperly managed,
aquaculture operations can have severe impacts on aquatic
ecosystems as nutrient wastes are discharged directly into
the surrounding waters. For every ton of fish, aquaculture
operations produce between 42 and 66 kg of nitrogen waste
and between 7.2 and 10.5 kg of phosphorus waste (Strain
and Hargrave 2005).
1.3.1.3 Fossil Fuel and Energy Consumption
Coal-fired power plants, cars, buses, and trucks consume
fossil fuels, which is also a contributor of nutrients. On combustion fossil fuel releases nitrogen oxides into the atmosphere. These oxides of nitrogen contribute to the formation
of smog and acid rain. Nitrogen oxide is redeposited to land
and water through rain and snow, or can settle out of the air
in a process called dry deposition. Fossil fuel combustion
contributes approximately 22 Tg of nitrogen pollution globally every year, approximately one-fifth of the contribution
of synthetic nitrogen fertilizers (MA 2005). In the Baltic Sea,
atmospheric deposition, primarily from burning fossil fuels,
accounts for 25 % of nitrogen inputs (HELCOM 2005). Similarly, in the Chesapeake Bay, atmospheric deposition accounts for 30 % of all nitrogen inputs. In some areas, such as
in the US North Atlantic, atmospheric deposition of nitrogen
can exceed riverine nitrogen inputs to coastal areas (Spokes
and Jickells 2005).
Increasing demand of energy for the increasing population across the globe is one of the direct drivers of eutrophication. Total worldwide energy consumption rose by 33 %
between 1990 and 2005. Currently, more than 86 % of the
world’s energy needs are being met by fossil fuel sources
(EIA 2008). Experts estimate that per capita energy consumption will increase by approximately 18 % between 2005
and 2030, while total global energy consumption will rise
by 50 %; the developing world is projected to account for
the majority of increased energy consumption (EIA 2008).
Fossil fuels are expected to continue meeting approximately
86 % of global energy needs (EIA 2008).
1.3.1.4 Increased Fertilizer Consumption
The increasing population forces to increase the agriculture
production that is accompanied by the additional use of fertilizers. It is expected that between 2002 and 2030 fertilizers
consumption will increase by 40 % (FAO 2000). The majority of the projected increase in global fertilizer consumption
is attributed to the developing world where food production
and adoption of intensive agricultural practices are expected
to increase (FAO 2000). At present, two sources of fertilization commonly used are slurry and synthetic compounds.
Nitrogen and phosphorus losses in surface runoff from fertilized soils depend upon the quantity of transporting water and
the time and rate of fertilizer application. When fertilizers
are applied before a wet period or snowmelt, or on frozen
ground, losses are higher than when fertilization is done in
the spring. Excessive application of fertilizers and bad management practices increase nutrient loss from the soil. Lesser
amounts of nitrogen and phosphorus are lost to the surface
water of judiciously fertilized and well-managed soils.
1.3.1.5 Land-use Transformation
Enhanced food production is coupled with the transformation of forest to crop land. Cropland has experienced a net
global increase of about 3 million ha per year from 1995
to 2002, with over 90 % of the total cropland gains coming
from forests (Holmgren 2006). Agriculture is also the single
largest cause of wetland loss. Approximately 50 % of the
world’s wetlands have been lost since the 1950s. The majority of wetland loss occurred as a result of drainage for agricultural production (OECD/IUCN 1996). According to the
prediction of FAO, land-use conversion for agriculture will
continue, but at a slower pace than in the past (FAO 2002).
Natural landscapes such as forests and wetlands are important for capturing and cycling nutrients. Increasing land-use
conversion reduces the ability of these landscapes to intercept nutrients and leads to greater nutrient losses to local
waterways.
1.3.2 Indirect Drivers of Eutrophication
1.3.2.1 Population Expansion
Although population growth is an indirect driver of eutrophication but it is also the root cause for all types of the drivers
of eutrophication. The global population is predicted to grow
from 6.5 billion in 2005 to nearly 9.2 billion in 2050 with
the majority of population growth occurring in developing
countries (United Nations Population Division 2008). Population growth will increase the demand for food, land, energy, and other natural resources, ultimately leading to greater
agricultural production and increased burning of fossil fuels
to heat homes, power cars, and fuel industry.