International Rice Research Institute-India, First Floor, NASC Complex, DPS Marg, PUSA, New Delhi 110012, India.
Environ Monit Assess. 2011 Jul;178(1-4):545-62. doi: 10.1007/s10661-010-1712-0. Epub 2010 Sep 24.
Increased use of nitrogenous fertilizers in the intensively cultivated rice (Oryza sativa)-wheat (Triticum aestivum) cropping system (covers a 13.5-ha m area in South Asia) has led to the concentration of nitrates (NO(3)-N) in the groundwater (GW) in Haryana State of India. Six districts from the freshwater zone were selected to identify factors affecting NO(3)-N enrichment in GW. Water and soil samples were collected from 1,580 locations and analyzed for their chemical properties. About 3% (26,796, and 10,588 ha) of the area was estimated to be under moderately high (7.5-10 mg l( -1)) and high (>10 mg l( -1)) risk categories, respectively. The results revealed that NO(3)-N was 10-50% higher during the pre-monsoon season than in the monsoon season. Nitrate-N decreased with the increase in aquifer depth (r (2) = 0.99). Spatial and proximity analyses using ArcGIS (9.2) revealed that (1) clay material in surface and sub-surface texture restricts N leaching, (2) piedmont and rolling plains act as an N sink, and (3) perennial rivers bring a dilution effect whereas seasonal rivers provide favorable conditions for NO(3) (-) enrichment. The study concludes that chemical N fertilizers applied in agro-ecosystems are not the sole factor determining the NO(3) in groundwater; rather, it is an integrated process governed by several other factors including physical and chemical properties of soils, proximity and type of river, and geomorphologic and geographical aspects. Therefore, future studies should adopt larger area (at least watershed scale) to understand the mechanistic pathways of NO(3) enrichment in groundwater and interactive role of the natural drainage system and surrounding physical features. In addition, the study also presents a conceptual framework to describe the process of nitrate formation and leaching in piedmont plains and its transportation to the mid-plain zone.
在南亚 13.5 公顷的范围内，集约型水稻（Oryza sativa）-小麦（Triticum aestivum）种植系统中增施氮肥导致印度哈里亚纳邦地下水（GW）中硝酸盐（NO3-N）浓度升高。从淡水区选择了六个地区，以确定影响 GW 中硝酸盐氮富化的因素。从 1580 个地点采集水和土壤样本并分析其化学性质。据估计，该地区约有 3%（26796 和 10588 公顷）分别处于中度高（7.5-10 mg l-1）和高（>10 mg l-1）风险类别。结果表明，前季风季节的 NO3-N 比季风季节高 10-50%。硝酸盐氮随含水层深度的增加而降低（r (2) = 0.99）。使用 ArcGIS（9.2）进行的空间和接近度分析表明，（1）表层和次表层质地中的粘土物质限制了 N 的淋溶，（2）山前和起伏平原充当 N 的汇，（3）常年河流带来稀释效应，而季节性河流则为 NO3-（-）的富化提供有利条件。研究得出结论，农业生态系统中施用的化学氮肥并不是决定地下水 NO3-的唯一因素；相反，这是一个受多种因素综合控制的过程，包括土壤的物理和化学性质、河流的接近度和类型以及地貌和地理方面。因此，未来的研究应采用更大的区域（至少流域尺度）来了解地下水 NO3-富化的机制途径以及自然排水系统和周围物理特征的相互作用。此外，该研究还提出了一个概念框架，用于描述山前平原硝酸盐形成和淋溶过程及其向中平原带的运输。
