| environ. |
nitrification The process by which ammonia compounds, including man-made fertilizer and the humus provided by organic matter or plant and animal origin, are converted into nitrites and then nitrates, which are then absorbed as a nutrient by crops. Excess nitrate can be leached into surface waters and groundwaters, causing pollution. Excess nitrate may also be converted by microbes back into gaseous nitrogen, which is an important greenhouse gas, and released back into the atmosphere. The ultimate source of nitrogen in the ecosystem is the molecular nitrogen in the atmosphere. To a very limited extent, some dissolves in water. However, none is found in rock (氨水混合物，包括人造肥料、由有机物或者动植物源提供的腐殖质，被转换为亚硝酸盐而后是硝酸盐，其被吸收作为庄稼营养物的过程。过量硝酸盐可浸入地表水和地下水而引起污染。过量硝酸盐可能通过微生物转变为氮气，它是一种重要的温室气体，并且释放进入大气。生态系统中的氮的重要来源是空气中的分子氮。在有限的程度之上，一些溶解在水里。不过，没有在岩石里发现氮。) |
