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Environmental fate & pathways

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Aluminium nitride (AlN) is susceptible to hydrolysis in aqueous solution. After the addition of water the substance undergoes hydrolysis, resulting in different poorly soluble aluminium species and ammonia.

Aluminium is the most abundant metal in the lithosphere and is characterized by a complex biogeochemical cycle (Driscoll and Postek, 1996; Exeley, 2003). Aluminium persists in the environment irrespective of the chemical species formed as a result of hydrolysis, although it may form insoluble aluminium hydroxides which precipitate.

Ammonia occurs naturally in the environment, and organisms are regularly exposed to low levels of ammonia in air, soil and water.

Ammonia is rapidly degraded and furthermore in integral part of nitrogen transformation cycles. In air, the dominant fate process for ammonia is the reaction with acid air pollutants. Formation of particulate NH4+ compounds by reactions with HNO3 and H2SO4 is rapid (Bouwman et al. 1997; Irwin and Williams 1988). In surface water, groundwater, or sediment, ammonia can undergo sequential transformation by two processes in the nitrogen cycle, nitrification and denitrification, which produce ionic nitrogen compounds, and from these, elemental nitrogen. In soil, ammonia can serve as a nutrient source for plants, which can be taken up by plants and microorganisms and converted into organic nitrogen compounds. Ammonia in soil can be rapidly transformed to nitrate by the microbial population through nitrification (Atlas and Bartha 1998; Payne 1981). The nitrate formed will either leach through the soil or be taken up by plants or other microorganisms. Very high localized concentrations of ammonia, such as those that might occur after a spill or an excessive application of ammonia-containing fertilizers can be toxic to plants, other organisms, or microbiota which, if inhibited or killed, will result in a decrease of the rates of any related nitrogen transformation processes. Under these conditions, other fate processes dictated by the physical and chemical properties of ammonia will dominate until the ammonia concentration returns to a natural background level. These physical and chemical processes include binding to soil particles (including organic carbon) or volatilization to the atmosphere.

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