内蒙古河套灌区粮食生产灰水足迹评价

Evaluation of grey water footprint of grain production in Hetao Irrigation District,Inner Moreongolia

随着面源污染和土壤盐渍化成为重要的环境污染源和粮食安全的制约要素，如何评价和量化农业生产的负面效应，成为亟需解决的问题。水足迹理论的出现使该负面效应的量化成为可能，水足迹包括蓝水、绿水和灰水足迹，灰水足迹可以表征不同类型负面效应的大小，粮食生产灰水足迹反映了单位粮食产量的负面效应。该文应用水足迹理论，以内蒙古河套灌区为研究区，给出粮食生产灰水足迹的计算方法，选取环境最大允许浓度Cmax和本底浓度 Cnat，逐项计算各项灰水足迹，并根据短板原理得出总灰水足迹，计算分析河套灌区粮食生产灰水足迹。结果表明：2005-2008年面源污染的灰水足迹为0.55～0.58亿m3；积盐的灰水足迹从2005年的4.570亿m3减少到2008年的1.825亿m3。总灰水足迹从2006年的5.872亿m3，减少到2008年的1.825亿m3，总灰水足迹在总水足迹中比例小于10%，有逐年降低的趋势。2005-2008年粮食生产灰水足迹分别为0.129、0.159、0.062和0.043 m3/kg，粮食生产灰水足迹有逐年降低的趋势，2008年的粮食生产灰水足迹仅相当于2006年的27.04%。节水灌溉等新技术的推广是其主要原因，节水灌溉可以减少无效灌溉水量和水分的无效蒸发量，从而减小粮食生产灰水足迹。在此基础上，给出减少粮食生产灰水足迹的措施，即节水灌溉、种植业结构调整、合理确定地下水位和合理使用化肥、农药。研究成果较好地量化了大型灌区粮食生产的负面效应和粮食生产灰水足迹，可为其他粮食主产区农业可持续发展及制定农业产业政策提供参考。

As non-point source pollution and salinization being the important environmental pollution source that affects food security, the evaluation and quantification of such negative effects on agricultural production become the urgent eco-environment issues need to be solved. It is possible to quantify the negative effects of agricultural production because of the foundation of Water Footprint Theory. Water footprint contains blue water footprint, green water footprint and grey water footprint. Grey water footprint（GWF） can represents the value of different types of negative effects, of which the GWF of grain production represents the negative effect of per unit grain production. In the study, water footprint theory is used and Hetao irrigation district in Inner Mongolia was employed as the study area. The calculation method of the grain production GWF were given and the parameters of maximum environmental allowable concentration（Cmax） and background concentration（Cnat） were selected. Each kind of GWF was calculated Item by item, and the total GWF was computed using the Cask Theory, so the GWF of grain production was calculated and analyzed. The results showed that the GWF of non-point source pollution was 0.55-0.58×108m3 during the period of 2005-2008. The GWF of salification was 4.570×108m3 in 2005 and decreased to 1.825×108m3 in 2008. The total GWF was declined from 5.872×108m3 in 2006 to 1.825×108m3 in 2008. In year of 2005-2008, the total GWF was less than 10% of total water footprint, and showed a slightly decline tend along the years. The GWF of grain production from year of 2005 to 2008 was 0.129 m3/kg, 0.159 m3/kg, 0.062 m3/kg and 0.043 m3/kg, respectively. In general, the GWF of grain production showed declining tend, which in 2008 was only equivalent to 27.04% of that in 2006. The extension of new agricultural technologies such as water-saving irrigation was the main reason, water-saving irrigation significantly reduce GWF of grain production by decreasing ineffective irrigation and invalid moisture evaporation. Based on these, the measures, including water saving, cropping structure adjustment, reasonably determination of ground water level and reasonable utilization of fertilizers and pesticides, are recommended for reducing the GWF of grain production. The negative effects of environmental issues on food production and GWF of grain production in large-scale irrigation area are quantified preferably. The results can offer a valuable reference for the agricultural sustainable development and formulating agricultural industry policy for other similar grain-producing regions.