中国食物生产消费系统碳素动态变化及其环境负荷

基于物质流原理，分析了1995~2016年中国食物生产消费系统的变化情况，测算并评价了食物生产消费系统碳素流动变化及食物碳消费导致的碳素环境负荷变化.结果表明：食物农业生产系统中碳汇和碳排总量整体均呈上升趋势，且碳汇增速明显高于碳排增速；食物生产系统碳素环境负荷中畜禽养殖产生的碳素环境负荷呈下降趋势，农用物资、农业活动及食物加工运输相关产生的碳环境负荷呈快速上升趋势.食物消费系统中，居民食物碳消费发生变化，居民碳消费结构从“以粮食碳消费为主”的饮食结构转变为“以粮食、肉类、食用植物油碳消费为主”的多元饮食结构，农村居民人均食物碳消费量由95.24kg/（人×a）降低至71.62kg/（人×a），城镇居民人均食物碳消费量由52.06kg/（人×a）升至65.16kg/（人×a）.分析食物消费系统碳素环境负荷，进入大气的碳素环境负荷占主体地位，其次是土壤和水体，近年来进入土壤和水体的碳素比例增加.分析表明减少食物生产消费系统碳素环境负荷的措施，包括引导居民优化饮食结构，减少生活污水与厨余垃圾产生量，提高厨余垃圾与粪便还田比例，将系统中产生的废弃物内部循环利用等.

Carbon dynamics and environmental load of food production and consumption in China

Chinese food production and consumption changes from 1995 to 2016 were analyzed using material flow analysis. Carbon flow and environmental load of food production and consumption were calculated and evaluated. The results showed that the total carbon sequestration and emission of agricultural production system generally showed upward trends, with the growth rate of carbon sequestration obviously higher than that of carbon emission. Livestock-breeding carbon load showed downward trends, while carbon load from agricultural materials input, agricultural activities and food processing and transportation showed increasing trends. Food consumption changes were driving a food carbon consumption transition in which diets of higher in grain carbon consumption were replaced by diets higher in grains, meats and edible oils. The rural residents' average per capita food carbon consumption decreased from 95.24kg/(cap×a) in 1995 to 71.62kg/(cap×a) in 2016, and the urban residents' increased from 52.06kg/(cap×a) in 1995 to 65.16kg/(cap×a) in 2016. The national residents' total food carbon consumption decreased by 6.4% Carbon released from food consumption was mostly emitted into atmosphere environment, followed by soil and water. The proportion of environmental carbon load entered the soil and water showed increasing trend. To reduce the environmental carbon load in China, it was important to both reduce the carbon losses during food production and consumption and increase the recycling rate, such as shifting towards a more environmental-friendly diet, reducing sanitary sewage and kitchen waste discharge, effectively reusing crop, animal and kitchen wastes, and recycling the food wastes.