城市食物磷足迹研究——以龙岩市为例

运用物质流分析法,以龙岩市为例,分析了1985—2010年城市食物磷代谢的变化,估算了食物磷足迹。研究表明,龙岩市总磷输入和总磷输出都有明显的增长(总磷输入从4110 t增加到12102 t,总磷输出从3855 t增加到11315 t);总磷足迹从6482t增加到20473 t,直接磷足迹的比例从53%下降到42%;而间接磷足迹的增速明显高于直接磷足迹;龙岩市在城市尺度上是重要的磷汇,在流域尺度上则是重要的磷源。磷足迹的研究有助于全面理解和评估城市磷代谢的特征;将磷足迹与磷流动分析结合,对我国磷资源和区域磷素管理调控具有指导意义。

Study on phosphorus footprint of urban food: a case study in Longyan City

Phosphorus (P) is an irreplaceable and essential nutrient for all living beings and a critical element for food production. However P is not only an essential and irreplaceable non-renewable resource, but also a potential water pollutant which can cause eutrophication. Phosphorus used in fertilizer for food, accounts for approximately 90% of the total phosphorus consumption. China''s rapid urbanization calls for a better and comprehensive understanding of P management in urban food systems. In this paper, we firstly present a concept model to map the P metabolism of food production and consumption system. And then we analyzed the change of urban food P metabolism and estimated food P footprint from the year 1985 to 2010 based on the method of substance flow analysis and our definition of P footprint, taking Longyan as an example. The result demonstrated that both input P and output P increased significantly (the input P increased from 4110 t to 12102 t, the output P from 3855 t to 11315 t); the total P footprint grew up from 6482 t to 20473 t and the proportion of the direct P footprint decreased from 53% to 42%; the growth of the indirect P footprint was faster than that of the direct P footprint. The P metabolism analysis reflected that Longyan was an important P sink at the city scale and main P source at the watershed scale. Our results of P footprint analysis indicated that the indirect P footprint constituted an important proportion of the total P footprint and should not be neglected. The analysis of P footprint helped to comprehensively understand and evaluate characters of urban P metabolism. Combining the analysis of P footprint and substance flow had guiding significance for national and regional P management and regulation.