Lakes eutrophication

Nitrite reductases (NiRs)—enzymes found in several strains of denitrifying bacteria— catalyze the one-electron reduction of nitrite anion to nitric oxide (Equation 1). - In addition to the importance of this process in the global nitrogen cycle (Figure 1), further incentive for the study of the denitrification process is provided by its environmental impact, ranging from the production of NO as a pollutant and NjO as a potent greenhouse gas, to lake eutrophication due to farm runoff that contains high concentrations of nitrates and nitrites. 

Despite the strengthening of environmental policies, problems in relation to cadmium and cyanide, dioxin, organic pollution, lake eutrophication, residential sewage, pesticide runoff, industrial discharges, and groundwater contamination by toxics and nitrates also need to be tackled. 

His 40+ publications have dealt with biogeochemical processes that control the alkalinity of surface waters, the geochemisty of dilute seepage lakes, sediment chemistry, the interpretation of water-quality trends, regional analysis of water quality, modeling lake eutrophication, lake management, reservoir water quality, and nonpoint source pollution. He recently joined the faculty of the Department of Civil Engineering at Arizona State University. 

Vollenweider, R.A. (1976) Advances in defining critical loading levels of phosphorus in lake eutrophication. Mem 1st. Ital. Idrobiol. 33, 53-83. 

R.L Hall, P.R. Leavitt, J.P. Smol, N. Zirnhelts (1997). Comparison of diatoms, fossil pigments and historical records as measures of lake eutrophication. Freshwat. Biol, 38,401-417. 

R.I. Hall, J.P. Smol (1999). Diatoms as indicators of lake eutrophication. In E.F. Stoermef, J.P. Smol (Eds), The Diatoms Applications for the Environmental and Earth Sciences (pp. 128-168). Cambridge University Press, Cambridge. 

N.J. Anderson (1998). Variability of diatom-inferred phosphorus profiles in a small lake basin and its implications for histories of lake eutrophication. J. Paleolimnol, 20, 47-55. 

Keywords seaside lakes eutrophication water quality parameters nutrients 1. Pollution Threats... 

Early approaches to lake eutrophication modelling did not distinguish between inorganic, organic, particulate or dissolved phosphorus (Vollenweider, 1975, 1976). These models consist of a mass balance for total phosphorus in the lake by considering inflow, outflow and sedimentation. They are usually combined with a hydraulic model representing the lake as a well-mixed compartment and, despite their simplicity, are able to describe the major phosphorus mass fluxes in lakes. 

Table 16.16. Process table of the lake eutrophication model by Imboden and Gachter (1978). ...

Schindler, D.W., Whole-lake eutrophication experiments with phosphorus, nitrogen and carbon, Verh. Internat. Verein. LimnoL, 21, 65, 1975. 

Finally, let us mention an argument for the stochastic model coming from the endeavour to revitalise the science of ecological modelling. Large multiparameter systems aimed at a detailed description of lake eutrophication seem to have become less popular in recent years. This may either be the consequence of either the mathematical and computational problems involved or be due to the lack of measurements, or both. It is hoped that stochastic models constitute a possibility in this regard. 

Table 7.1 Formal components of the lake eutrophication model.

Fig. 9.12. Simulated effects of different lake tot P (total phosphorus) on the Hg-concentration in top predator. A simulated liming year 20 increases mean annual lake pH from 6 to 6.7. This is one example of "biological dilution", i.e., the biological Hg-upt e decrease with increased lake eutrophication...

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