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Nitrogen effects on biodiversity, carbon cycling, and changes in species composition have also been demonstrated. In highly developed areas of near shore coastal ocean and estuarine systems, rivers deliver direct (e.g., surface runoff ) and indirect (e.g., groundwater contamination) N inputs from agroecosystems. [ 8 ]
Even though nitrogen is a necessary element for life, too much of it in water can have negative effects on aquatic ecosystems and endanger human health. Agricultural runoff, where fertilizers containing nitrogen compounds can seep into rivers, lakes, and groundwater, is one of the main sources of nitrogen in water.
Human activities such as fossil fuel combustion, use of artificial nitrogen fertilizers, and release of nitrogen in wastewater have dramatically altered the global nitrogen cycle. [17] [18] [19] Human modification of the global nitrogen cycle can negatively affect the natural environment system and also human health. [20] [21]
The nitrogen cycle is one of the Earth's biogeochemical cycles. It involves the conversion of nitrogen into different chemical forms. The main processes of the nitrogen cycle are the fixation, ammonification, nitrification, and denitrification. As one of the macronutrients, nitrogen plays an important role in plant growth.
A nutrient cycle (or ecological recycling) is the movement and exchange of inorganic and organic matter back into the production of matter. Energy flow is a unidirectional and noncyclic pathway, whereas the movement of mineral nutrients is cyclic.
Human activities such as fossil fuel combustion, use of artificial nitrogen fertilizers, and release of nitrogen in wastewater have dramatically altered the global nitrogen cycle. [40] [41] [42] Human modification of the global nitrogen cycle can negatively affect the natural environment system and also human health. [43] [44]
Nitrogen, phosphorus and potassium are the "Big 3" primary nutrients in commercial fertilizers, each of these fundamental nutrients play a key role in plant nutrition. [4] When nitrogen and phosphorus are not fully utilized by the growing plants, they can be lost from the farm fields and negatively impact air and downstream water quality. [5]
Nitrogen cycle pathways in mangrove ecosystems. Human activity, such as increased fertilizer use, has caused nitrogen pollution in inland and coastal waters. An influx of nitrogen inputs into aquatic ecosystems can cause negative effects such as eutrophication, resulting in anoxic conditions. [8]