Phosphorus anthropogenic

Feedbacks may be affected directly by atmospheric CO2, as in the case of possible CO2 fertilization of terrestrial production, or indirectly through the effects of atmospheric CO2 on climate. Furthermore, feedbacks between the carbon cycle and other anthropogenically altered biogeochemical cycles (e.g., nitrogen, phosphorus, and sulfur) may affect atmospheric CO2. If the creation or alteration of feedbacks have strong effects on the magnitudes of carbon cycle fluxes, then projections, made without consideration of these feedbacks and their potential for changing carbon cycle processes, will produce incorrect estimates of future concentrations of atmospheric CO2. 

Garland JL, Mills AL (1991) Classification and characterization of heterotrophic microbial communities on the basis of patterns of community-level sole-carbon-source utilization. Appl Environ Microbiol 57 2351-2359 Giuffre L, Piccolo G, Rosell R, Pascale C, Heredia OS, Ciarlo E (2001) Anthropogenic effect on soil organic phosphorus fractions in tropical ecosystems. Commun Soil Sci Plant Anal 32 1621-1628 Gottlieb S (1976) The production and role of antibiotics in soil. J Antibiot 29 987-1000... 

Given all these uncertainties, it is not currently possible to determine whether the nitrogen and/or phosphorus cycles are in a steady state. Indeed, anthropogenic inputs of both are now so large that the maintenance of a steady state seems unlikely. As noted earlier, natural deviations from a steady state in the nitrogen cycle are also deemed likely given the large spatial separation between the locales where denitrification and BNF take place. 

ANTHROPOGENIC PERTURBATIONS OF THE MARINE NITROGEN AND PHOSPHORUS CYCLES... 

The model-calculated partitioning of the human-induced perturbation fluxes In the global coastal margin of (a) nitrogen and (b) phosphorus for the period from 1850 to the present (2000) and projected to 2035 under the business-as-usual scenario, In units of lO mol/y and Mtons/y. The anthropogenic sources are plotted on the (-) side and the resulting accumulations and enhanced export fluxes are plotted on the +) side. Source-. From Mackenzie, F. T, et al. (2002). Chemical Geology 190, 13-32. 

The impact of anthropogenic nutrient emissions in the coastal zone is heightened by its chemical speciation. Pollutant nitrogen and phosphorus are delivered to the coastal waters primarily in inorganic form, whereas most of the natural riverine dissolved nitrogen and phosphorus are components of organic compounds, i.e., DON and DOE Thus, the pollutant nutrients are delivered to the coastal waters in a chemical form that can be directly assimilated by coastal plankton, whereas the organically bound (natural) forms must first be remineralized. 

Regnery J, Puttmann W, Merz, C, Berthold G (2011) Occurrence and distribution of organo-phosphorus flame retardants and plasticizers in anthropogenically affected groundwater. J Environ Monit 13 347-354... 

Phosphorus in the subsurface originates from a natural parent material or anthropogenic application on land surface (e.g., fertilizers, pesticides, surfactant products, sludge, and effluents). This element may be found in inorganic or organic forms, which are in a dynamic equihbrium with dissolved P in the subsurface liquid phase. 

Under normal circumstances, the eutrophication of a lake or pond is a very slow process, requiring hundreds or thousands of years. That rate may he altered, however, hy human activities. For example, runoff from farmlands, municipal sewage, and industrial wastes may contain compounds of phosphorus. When these materials empty into a lake or pond, they may dramatically increase the amount of phosphorus present and, hence, the rate at which eutrophication occurs. It is not unusual today for anthropogenic sources to be responsible for at least 90 percent of all the phosphorus found in a body of water. Under these circumstances, eutrophication may occur in a fraction of the normal time. 

Figure 2.22 Examples of important anthropogenic chemicals exhibiting a phosphorus-containing functional group. Some of the common uses of the chemicals are given in parentheses.

The potential for N deposition to contribute to the eutrophication of freshwater lakes is probably quite limited. Eutrophication by atmospheric inputs of N is a concern only in lakes that are chronically N-limited. This condition occurs in some lakes that receive substantial inputs of anthropogenic P and in many lakes where both P and N are found in low concentrations (e.g., Table III). In the former case the primary dysfunction of the lakes is an excess supply of P, and controlling N deposition would be an ineffective method of water-quality improvement. In the latter case the potential for eutrophication by N addition (e.g., from deposition) is limited by low P concentrations additions of N to these systems would soon lead to N-sufficient, and phosphorus-deficient, conditions. The results of the NSWS shown in Table III, for example, can be used to calculate the increase in N concentration that would be required to push N-limited lakes into P limitation (assuming total P concentrations do not change). An increase of only... 

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