Īdditional atmospheric input of inorganic nitrogen has increased significantly to a level where it is already higher than the natural nitrogen supply in the North Atlantic Ocean basin. In the recent past eutrophication has been most pronounced in the developed world, but it has to be expected that it will become more and more important in the developing countries of Asia, Africa and Latin America in the near future. However, eutrophication cannot be defined just in terms of an increase in nutrients concentration, as its manifestations (very often harmful to ecosystems) occur due to the existence of natural conditions, such as high temperatures and calm coastal waters. Discharges and emissions from land-based sources (industry, households, traffic, agriculture) provide large inputs of nutrients to coastal waters via rivers, direct discharges, diffuse sources and deposition from the atmosphere. Nutrients run-off from silage and slurry-manure, use of fertilizers leading to eutrophicationĮutrophication results from the increase of nutritional resources to a particular water body and includes the supply of mineral nutrients (nitrogen, phosphorus, silicon, trace elements) as well as organic carbon.Pollution, from use of oil, for instance.Use of insecticides and other pesticides affecting species, cultivated or not.Discharge of methane and ammonia contributing to the greenhouse effect.The contribution of agriculture to the pollution of coastal ecosystems affects biogeochemical cycles, notably in terms of : The sensitivity of the coastal zone to watershed impacts is examined in relation to land-derived pollution and water quality.Ĭontamination is usually considered a lesser degree of pollution, that occurs when an input of waste from human activities increases the concentration of a substance in seawater, sediments or an animal above the background level for that area or animal, but without (immediate) obvious effect.Įmissions and inputs from agriculture are a significant source of pollution to the coastal zone and to the atmosphere throughout the world. In this section, generic sources of pollution and effects ( eutrophication, contamination and pollution from industry and agriculture, etc.) are considered. Indirect (or diffuse) inputs are usually widespread low-level discharges and likely result in chronic pollution. Point and non-point source pollutions continue globally, resulting in the steady degradation of coastal and marine ecosystems. Quantitative estimates are difficult because of the lack of reliable data and the extreme complexity of biogeochemical cycles, especially at the sea-land and sea-atmosphere interfaces. The relative contribution of each human activity to the overall pollution impact depends on the specific situation and on the released substances. 3.4 Oil and gas and offshore installations.
#Factors affecting enzyme activity wiki free
The reason is that at V max, there are no free enzyme molecules available that can bind with extra substrate molecules.īinding certain chemicals to the enzyme, acts as a competitive inhibitor to the substrate. This velocity does not rise any further even if there is an increase in substrate concentration. In the final stage, the reaction reaches a maximum velocity or V max. If the substrate concentration increases, initially the velocity of enzymatic reaction rises. Thereafter, with an increase in pH and temperature, enzyme activity decreases as they get denatured. The enzyme activity increases steadily with an increase in pH and temperature up to the optimum pH and optimum temperature. Low temperature inactivates the enzymes and high temperature denatures the enzymes. Temperature and pH affect the enzyme activity. Some factors such as temperature, pH and change in substrate concentration or the binding of specific chemicals alter the tertiary structure of the protein thereby affecting the activity of the enzymes.
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