城市居民食物氮消费变化及其环境负荷——以厦门市为例

食物消费是城市养分流动的重要环节,以厦门市为例,分析了1988—2009年居民食物氮素消费的变化特点,分析与其变化相关的经济、社会因素,并探讨了居民食物氮素消费变化所带来的环境负荷。研究结果表明,厦门市人均食物氮消费量变化与食物消费量变化并不完全一致,人均氮消费量2000年以前维持在3.29 kg N.人-1.a-1,2000年以后呈现波动性的增长,2004年达到最高值4.00 kg N.人-1.a-1。厦门市食物氮素消费总量增长幅度较大,由1988年的0.54万t增至2009年的1.50万t。同时,粮食在食物氮消费量中所占比例由45.5%下降到15.9%。畜禽肉、奶制品所占比例分别由25.0%和0.4%上升至29.8%和8.8%。通过将相关经济、社会因素与居民食物氮消费量进行相关性分析表明,人均可支配收入、食物价格指数、具有大学学历以上人口比重均与其联系较为密切,呈正相关;恩格尔系数、平均家庭人口数与居民食物氮消费量呈负相关。通过选取1988、1994、2001、2008年分析居民食物氮素消费造成的环境氮负荷发现,由其带来的环境氮负荷量由3509.12t增加至7629.36t,约90%的氮素进入了土壤和水体。其中,进入土壤的氮素占进入环境氮总量的比例由37%增长到60%,进入水体的氮素比例由57%降至35%。

Changes of residents nitrogen consumption and its environmental loading from food in Xiamen

Food consumption is an important process of urban nutrient metabolism. By taking Xiamen city for example, the changes of food nitrogen consumption during 1988-2009 years were analyzed. Then the associated economic and social driving factors and its environmental loading were researched. The results showed that changes of per capita food nitrogen consumption of Xiamen residents were not exactly the same with changes of per capita food consumption. Per capita nitrogen consumption maintained in 3.29 kg before the year 2000.However,there was a fluctuant growth after 2000, and per capita food nitrogen consumption reached a high value of 4.00 kg in 2004. The total food nitrogen consumption in Xiamen has grown rapidly, from 5400×10³ t in 1988 to 15000×10³t in 2009. Meanwhile, the proportion of grain in the food nitrogen consumption decreased from 45.5% to 15.9%. On the contrary, poultry meat and dairy products increased from 25.0% and 0.4% to 29.8% and 8.8%, respectively. In addition, correlation analysis was adopted to find that the positive correlation existed between the per capita disposable incomes, food price index, proportion of population with college degree and per capita food nitrogen consumption. Meanwhile, there was a negative correlation between the Engel's coefficient, the average number of family members, and per capita food nitrogen consumption. Selecting the year of 1988, 1994, 2001 and 2008 to analyze the environmental loading of food nitrogen consumption, it was found that the environmental nitrogen loading increased from 3509.12 t in 1998 to 7629.36 t in 2008, and more than 90% of nitrogen came to the soil and water. During 1988 to 2008, the proportion of nitrogen which entered to the soil increased from 37% to 60%. Meanwhile, the proportion of nitrogen to the water reduced from 57% to 35%.