Nutrients: Difference between revisions
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|KeyReference=Bouwman et al., 2013; Bouwman et al., 2009; Van Drecht et al., 2009; | |KeyReference=Bouwman et al., 2013; Bouwman et al., 2009; Van Drecht et al., 2009; | ||
|Reference=Bouwman et al., 2011; Galloway et al., 2004; Zhang et al., 2010; Diaz and Rosenberg, 2008; UNEP, 2002; Rabalais, 2002; | |Reference=Bouwman et al., 2011; Galloway et al., 2004; Zhang et al., 2010; Diaz and Rosenberg, 2008; UNEP, 2002; Rabalais, 2002; | ||
|InputVar=Population; GDP per capita; Land cover, land use - grid; Fertilizer use efficiency; Animal stock; Livestock ration; Manure spreading fraction; Nitrogen deposition - grid; NH3 loss; Fraction of urban population; Actual crop and grass production - grid; | |InputVar=Population; GDP per capita; Land cover, land use - grid; Fertilizer use efficiency; Animal stock; Livestock ration; Manure spreading fraction; Nitrogen deposition - grid; NH3 loss; Fraction of urban population; Actual crop and grass production - grid; | ||
|OutputVar= | |OutputVar=NH3 emission - grid; N and P discharge to surface water; Nutrient discharge to water surface; Soil N budget - grid; Soil P budget - grid; | ||
|Parameter=Fraction NH3 loss; | |||
|Description=Human activities have accelerated the earth’s biogeochemical nitrogen (N) and phosphorus (P) cycles by increasing the use of fertilisers in agriculture ([[Bouwman et al., 2011]]). The changes in global nutrient cycles have both positive and negative effects. Increased use of N and P fertilisers has allowed for an increase in the production of food required to support a rapidly growing human population, and increasing per-capita consumption of particularly meat and milk ([[Galloway et al., 2004]]). This has also contributed to ongoing increases in yields, thereby making agriculture economically viable on a land area that has expanded much less than the harvested output. A side effect is that significant fractions of the mobilised N are lost through the emission of ammonia (NH3), nitrous oxide (N2O) and nitric oxide (NO) to ambient air. Ammonia contributes to eutrophication and acidification when deposited on land. Nitric oxide plays a role in tropospheric ozone chemistry, and nitrous oxide is a potent greenhouse gas. Also, large fractions of the mobilised N and P in watersheds enter the groundwater through leaching, and are released to surface waters through groundwater transport and surface runoff. Subsequently, nutrients in streams and rivers are transported towards coastal marine systems, reduced by retention but augmented by releases from point sources, such as sewage systems and industrial facilities. | |Description=Human activities have accelerated the earth’s biogeochemical nitrogen (N) and phosphorus (P) cycles by increasing the use of fertilisers in agriculture ([[Bouwman et al., 2011]]). The changes in global nutrient cycles have both positive and negative effects. Increased use of N and P fertilisers has allowed for an increase in the production of food required to support a rapidly growing human population, and increasing per-capita consumption of particularly meat and milk ([[Galloway et al., 2004]]). This has also contributed to ongoing increases in yields, thereby making agriculture economically viable on a land area that has expanded much less than the harvested output. A side effect is that significant fractions of the mobilised N are lost through the emission of ammonia (NH3), nitrous oxide (N2O) and nitric oxide (NO) to ambient air. Ammonia contributes to eutrophication and acidification when deposited on land. Nitric oxide plays a role in tropospheric ozone chemistry, and nitrous oxide is a potent greenhouse gas. Also, large fractions of the mobilised N and P in watersheds enter the groundwater through leaching, and are released to surface waters through groundwater transport and surface runoff. Subsequently, nutrients in streams and rivers are transported towards coastal marine systems, reduced by retention but augmented by releases from point sources, such as sewage systems and industrial facilities. | ||
This has resulted in numerous negative impacts on human health and the environment, such as groundwater pollution, loss of habitat and biodiversity, an increases in the frequency and severity of harmful algal blooms, eutrophication, hypoxia and fish kills ([[Diaz and Rosenberg, 2008]]; [[Zhang et al., 2010]]). Such harmful effects of eutrophication have been spreading rapidly around the world, with large-scale implications for biodiversity, water quality, fisheries and recreation, in both industrialised and developing regions ([[UNEP, 2002]]). In freshwater and coastal marine ecosystems it is not only the input of nutrients but also the disturbance of the stoichiometric balance of N, P and silica (Si) ([[Rabalais, 2002]]) that affect both the total plant production and the species that dominate the ecosystems. | This has resulted in numerous negative impacts on human health and the environment, such as groundwater pollution, loss of habitat and biodiversity, an increases in the frequency and severity of harmful algal blooms, eutrophication, hypoxia and fish kills ([[Diaz and Rosenberg, 2008]]; [[Zhang et al., 2010]]). Such harmful effects of eutrophication have been spreading rapidly around the world, with large-scale implications for biodiversity, water quality, fisheries and recreation, in both industrialised and developing regions ([[UNEP, 2002]]). In freshwater and coastal marine ecosystems it is not only the input of nutrients but also the disturbance of the stoichiometric balance of N, P and silica (Si) ([[Rabalais, 2002]]) that affect both the total plant production and the species that dominate the ecosystems. | ||
Revision as of 15:07, 6 February 2014
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Key policy issues
- How will the increasing use of fertilisers affect terrestrial and marine ecosystems, with possible consequences for human health?
- To what extent can the negative impacts be reduced by more efficient nutrient management and wastewater treatment, while retaining the positive effects on food production and land productivity?