工业用水与经济发展的关系——用水库兹涅茨曲线

经验数据显示,发达国家工业用水随经济发展的变化存在着一个由上升转而下降的转折点。因此,工业用水随收入增长的演变模式可以用库兹涅茨曲线形式来表示。工业用水下降点对应的人均GDP的阈值是3700-17 000US$(PPP,以1985年为基数)。与之相应的第二产业在GDP总量中所占份额是30％～50％。工业用水下降的直接原因是用水效率的提高,其来源有两方面:部门用水效率的提高和经济结构调整。这提供了一个积极的信号,即发展中国家的工业用水将不会一直持续增长,从而为更好地预测发展中国家的工业用水量提供非常重要的思路,也为正确把握用水变化规律,制定符合规律的水资源对策提供科学基础。

Microbiological denitrification and inhibition of intermediates in lake waters

NITKOGEIV cycle is disturbed by human activities, while some nitrogenous compounds are harmful to hu- man health. When large amounts of nitrogenous compounds such as protein, urea, etc., which can bedegraded to NH4+ by microbes, enter waters, some of them are assimilated to biomass, but most are stillin waters. In the presence of oxygen, NH4+ are oxidized to NC2- and NO3- by autotrophic bacteria. Inanoxic phase, denitrifiers such as Pseudomonas Migula, Achromobacteaceae, Bacillus and Micrococcus,etc. will proceed denitrification, utilizing N03- as the terminal electron acceptor instead of O2 in the respiratory chain. Because bacteria denitrification, involving four steps from NO3- to NO2-, NO, N2O andN2, in fact, is an enzymatically catalytic process, changes of environmental factors such as