摘要
通过区域采样的方法,对黑河中游绿洲农田灌区71眼水井硝态氮(NO3--N)含量进行了分析.结果表明:调查水井的NO3--N平均含量为(10.66±0.19)mg.L-1,其中32.4%的水井NO3--N含量超过饮用水标准(NO3--N含量>10 mg.L-1),16.9%的水井NO3--N含量严重超标(NO3--N含量>20 mg.L-1).被调查的手压水井NO3--N平均含量为17.41 mg.L-1,比饮用水机井((5.75±0.20)mg.L-1)、灌溉水机井((11.44±1.70)mg.L-1)分别高67.0%和34.3%,超标和严重超标机井所占比例分别为52.4%和28.6%;地下水观测井NO3--N含量的平均值为(11.53±0.92)mg.L-1,超标和严重超标机井所占比例分别为50.0%和25.0%.该区域浅层地下水受到的污染较为严重,区域内深层水井也受到污染威胁.不同土地利用类型地下水NO3--N含量顺序为:蔬菜大棚>制种玉米>菜田>带田>水稻>小城镇.蔬菜大棚、菜田和制种玉米种植区域内的地下水污染情况严重.沙质土壤地区地下水NO3--N含量平均值为(27.20±1.96)mg.L-1,比壤土地区的(9.93±0.87)mg.L-1高2.74倍,地下水NO3--N含量的最大和最小值均高于壤土地区,超标率高28.3%,严重超标高52.5%,表明地下水NO3--N污染受土壤质地影响,沙质土壤区域内的地下水更易受到污染.
Nitrate concentration in groundwater was monitored and analyzed to assess the nitrate contamination of groundwater in the middle reaches of Heihe River, Northwest China. Water samples, from 71 wells, were marked with type of well, soil type, land using type and sampling depth. The mean value of NO3^--N contamination in groundwater for the 71 wells was （10. 66±0. 19） mg ·L^-1. 32. 4% of the wells have the nitrate concentrations above the dinking water standards established by World Health Organization （10 mg · L^-1 NO3^--N）, and 16.9% of them exceed 20 mg ·L^-1. The wells in the study areas are grouped into four according to the depth and usage： drinking wells, irrigation wells, hand-pumping wells and wells for monitoring groundwater table. The mean NO3^--N concentrations in the groundwater from drinking wells, irrigation wells, handpumping wells and wells for monitoring groundwater table are （5. 75±0.20） mg·L^-1, （11.44±1.70） L^-1, and 6.3%, 16.7 %, 28.6% and 25.0%exceeding 20 mg·L^-1, respectively. The result shows that nitrate concentration in groundwater is inversely related to depth of the well. The wells with nitrate concentrations above the dinking water standards mostly have the depth less than 20 m. Groundwater contamination by nitrate is affected by land using. NO3^--N concentrations in groundw- ater under vegetable fields, seed maize and intercropped maize are significantly higher than that under urban land or paddy fields. It is considered that the vegetable fields are the principal sources of nitrate contamination in groundwater. Soil type is also a main factor affecting nitrate concentration in groundwater. Groundwater nitrate pollution in sandy soil areas is more severe than that in loam soils.
出处
《冰川冻土》
CSCD
北大核心
2008年第6期983-990,共8页
Journal of Glaciology and Geocryology
基金
中国科学院西部行动计划项目(KZCX2-XB2-04)
国家自然科学基金项目(30670375)
甘肃省自然科学基金项目(310741B9)资助
