Naturally high nitrate concentrations in groundwaters from the Sahel
Naturally high nitrate concentrations in groundwaters from the Sahel
复制标题
DOI：
10.2134/jeq1997.00472425002600050006x
复制
发表时间：
1997-09
影响因子：
2.4
通讯作者：
W. Edmunds;C. Gaye
中科院分区：
文献类型：
--
作者：
W. Edmunds;C. Gaye
在塞内加尔北部非饱和第四纪砂岩的间隙水中，广泛发现了超过50到100 mg的硝酸盐浓度L−1 NO3-N。这些高浓度和相应增加的NO3/Cl值是在未开垦和雨水灌溉的耕作区下面的土壤区产生的。高硝酸盐(平均浅层地下水中也广泛存在11 mg L(−1 NO3-N)。作为好氧条件的结果，NO3-N特征被保留下来。非饱和区包含大约50到400年期间N个投入的历史。NO3/Cl值的变化主要与天然或引种豆科植物的生长有关。还有证据表明，高比率与较潮湿的气候时期有关，而较低的比率与较干旱的气候时期有关。这些结果与来自世界其他地区的证据一起表明，高硝酸盐浓度很可能是半干旱地区地下水中普遍存在的一种现象。
Nitrate concentrations in excess of 50 to 100 mg L−1 NO3-N are found widely in interstitial waters from unsaturated Quaternary sands in northern Senegal. These high concentrations and correspondingly enhanced NO3/Cl ratios are being produced in the soil zone beneath both uncultivated and rain-fed cultivated areas. High nitrate (avg. 11 mg L−1 NO3-N) is also found extensively in shallow groundwaters. The NO3-N signature is preserved as a result of the aerobic conditions. The unsaturated zone contains a history of N inputs over a period of approximately 50 to 400 yr. Variations in the NO3/Cl ratio are mainly related to the growth of natural or introduced leguminous vegetation. There is also evidence that high ratios relate to wetter and low values to more arid climatic periods. These results, taken together with evidence from other parts of the world, demonstrate that high nitrate concentrations are likely to be a widespread and established phenomenon of groundwaters in semiarid regions.