城乡居民食物消费的水生态占用分析——以太湖流域上游常州市为例

Water Footprints of Urban and Rural Residents'Food Consumption:A Case Study of Changzhou City in the Taihu Lake Basin

本文讨论了基于产品生命周期的居民食品消费的水生态占用计算方法,认为水生态占用计算应当包括食物生产过程中所能提供的各项生态服务功能水体总量,食物运输过程中的水资源消耗,再加工过程的水资源利用量以及浪费或废弃食品的自然消纳所需要的水资源量四个部分。基于这一理论,本文以太湖流域上游常州市为例,计算出该市城乡居民人均食物消费生产过程的水生态占用,分别为999.4m3和1108.1m3。本文通过对常州市城乡居民食物消费生产过程的水生态占用结构分析,证明了改进的水生态占用计算结果完善了水生态占用的组成部分;通过对各组分进行分析,更为明确的说明了水资源在各项生态服务功能中贡献的差异性及产业过程中各环节对水生态的影响,有助于理解城乡水生态环境变化发生的根本原因。

A multitude of studies use water ecological footprint to examine water resource flows in the production-consumption system,in which the nodes are shaped not only by economics,but also by culture or ecosystem service value.According to the concept of ecological footprint,products and services provided by the water ecosystem in the product life cycle should be fully considered.The conceptual model of water ecological footprint is composed essentially of four parts,i.e.,water of different eco-services in producing,transportation,consumption,and wasting or recycling pro-cesses.The model calculates the quantity of water resources used in the＂nature-society-economic system＂,which appears to be capable of reflecting the reality on how water resources flow in the food consumption.In this study,water ecological footprint of food consumption of urban and rural residents for Changzhou City at the production node was measured by calculating ecosystem servic-es of food production and decontamination.The water resources in the food consumption could be the product of the quantity of food consumption and water ecological footprint of the unit.Pollu-tion footprint from cultivation could be the quotient of the pollution and decontamination capacity of the water.The sum of the two can be taken as the value of water ecological footprint in the pro-ducing phrase of the food consumption life cycle.Results are given as follows.1）Water ecological footprint of food consumption of urban and rural residents in Changzhou City in 2007 was 999.4 m3per capita and 1108.1 m3per capita,respectively.This suggests that the rural residents needed more water to support their food consumption than urban residents,whereas the urban residents were almost 1.5 times water footprints of those in rural area because of excessive population;2） The structure of food consumption,which seemed to be more reasonable in urban areas than in ru-ral areas from the traditional water ecological footprint perspective,had been changed when we at-tempted to take into account other ecosystem services in this study.The structural analysis of the food consumption could not only describe explicitly the contribution of water resources for each ecosystem service during the whole industrial process,but also help with an elevated understanding of water ecological impacts on different cultural and natural environments in urban and rural areas.This water footprint model appears to improve the approaches of water ecological footprint.