基于生命周期评价的产品水足迹计算方法及案例分析

科学评价人类活动对水资源的影响是实现水资源可持续利用的前提。对比目前广泛应用的以虚拟水理论为基础的水足迹计算方法,详细介绍了基于生命周期评价(LCA)的产品水足迹计算方法,并以我国小麦生产为例进行实证研究。与虚拟水方法相比,LCA方法评价结果体现了水资源利用的环境影响,便于不同产品、不同生产阶段以及不同产地产品间水足迹的比较。实例研究表明:我国黄河、海河流域小麦水足迹平均为1 262 L H₂Oe·kg^-1,而长江流域仅为31 L H₂Oe·kg^-1;小麦生产对我国极度缺水的北方造成的压力远高于水资源较为丰富的南方地区。LCA方法能科学评价农产品生产对水资源的影响,为我国保障粮食安全和水资源可持续利用提供科学依据。

LCA-based Product Water Footprinting and a Case Study

In order to address the unsustainable use of global freshwater resources, indicators are needed which make the impacts of humans’ activity on water resources transparent. In this study, a life cycle assessment (LCA)-based water footprinting method is introduced and demonstrated for a case study product of wheat produced in China. Comparing with existing virtual water-based water footprint calculation, the LCA-based method enables meaningful comparisons between products, production stages and production places in terms of their potential environmental impact. The case study shows that the average water footprint of wheat produced in Huanghe and Haihe drainage basins is 1262 L H₂Oe·kg^-1 while that of wheat produced in Changjiang drainage basin is only 31 L H₂Oe·kg^-1. It is indicated that wheat production exerts much more pressure on water resources in the water-scarce north than in the water-rich south. This LCA-based water footprinting method could provide scientific basis to guide strategic decisions for China’s food production and sustainable water resources use.