地表水体富营养化是我国面临的水污染核心问题之一。整体性预防和降低磷养分流失是控制水体富营养化的关键途径。然而，目前我国水体富营养化防治仍主要局限在局部和末端的污染负荷削减，政策实施成本高昂且效率低下，缺乏结构性调控措施和系统性政策方案，不能有效遏制持续恶化的水体富营养化趋势。本文综合运用物质流分析技术和产业生态学理论，围绕推进磷代谢体系的生态化转型，深入分析了我国水体富营养化的控制策略。通过建立1999年中国静态磷物质流分析模型（PHOSFLOW）和2000年滇池流域静态磷物质流模型（DLPFA），分别从国家和区域两个层次上识别了磷代谢体系的主要结构和效率特征及其发展演进趋势。在此基础上，通过类比自然生态系统和社会经济系统的物质代谢规律，阐述了我国水体富营养化的控制机理与主要原则，建立磷控制政策体系的基本框架，并对其中重点政策方案进行了定量模拟和分析评估。研究结果表明，我国磷代谢体系的整体结构特征表现为矿物资源和进口化肥输入强度大、物质生产效率和养分循环效率低、污染排放率和废物累积率高，养殖业排放污染占进入水体总负荷较大比例，关键性生态化指标呈强烈物质化趋势。与之相比，滇池流域磷代谢体系结构特征上的重要区别在于农畜产品输入和输出强度比例高、系统内部养分循环通量大、生活污染负荷比例高。依据自然生态系统发展演化规律和自我调节原理，应重点从调整物质输入多样性、控制冗余生产结构、培育分解者、构造养分循环网络、提高物质生产效率、优化空间布局等多个方面，整体性推进磷代谢体系生态化转型。根据重点政策方案的模拟结果，农畜产品替代、限制农畜产品出口、削减规模养殖数量、提高饲料养分吸收效率、转变城乡居民饮食结构、城市生活污水源分离与控制等六项政策措施，均可在不同程度上降低进入地表水体的磷污染负荷。从政策实施角度来看，我国应优先根据耕地生态承载力水平规划和调整规模化畜禽养殖业发展战略，滇池流域则应重点开展城市生活污水源分离控制示范项目建设，并逐步减少流域内农作物种植面积和规模化畜禽养殖数量。
Eutrophication is one of key water issues suffering China, and phosphorus (P) is considered as the critical control factor. As being different from natural cycle, P societal metabolism is rather of complexity in structure and of high intensity in flux, which thus leads to a significant difficulty in eutrophication control. Hitherto, fractional and end-of-pipe measures advocated by China’s governments, however, can hardly alleviate the ongoing deterioration of eutrophication, because of their weak performance in costs and effects on the one hand, and lacking systematically structural control alternatives on the other.This study integrated Substance Flow Analysis (SFA) approach and Industrial Ecology Theory (IET) into a holistic methodology, and then applied it for analyzing P control strategy and related policies in China. Two static P flow analysis models, i.e., PHOSFLOW and DLPFA, were developed at national level in 1999 and local level in the case of Dianchi Basin in 2000, respectively. Characteristics of P metabolic structure and efficiency, as well as evolutionary trend were identified subsequently based on the models. Analogizing societal economy to natural ecology in relation to the metabolic features of P, this study illuminated P control mechanism and principles, and built a policy framework up, towards an ecological restructuring of P societal metabolism. Six selected key measures were examined with respect to its societal dynamics and restraints. Finally, potential effects of P load cutting-down related to these measures were simulated using the SFA models.Based on the PHOSFLOW model, China’s P societal metabolism is characterized by high intensive input of resource and imported chemical fertilizers, low efficiencies of material productivities and nutrient recycling, high ratio of water pollutant loads and wastes accumulation, strongly materialization of critical eco-restructuring indicators, and the most intensive P load to water of livestock production. However, the general metabolic structure is quite of difference between national and local level. In the case of Dianchi Basin, input and output of crops and livestock products, nutrient recycling ratio and human source of P pollutant, are rather significant, according to the results of DLPFA model. By comparing two kinds of P metabolism within human society and natural system, this study proposed some key P-control mechanism, including shifting P input sources, restricting redundant P processes, fostering decomposers, closing nutrient flow loop, increasing P productivity, and optimizing spatial distribution of P flows. The simulated results show the related polices, i.e., substitution of chemical fertilizers requirement by crops input, output restriction of agricultural products, amount cutting-down of scaled-breeding animals, promoting P-assimilative ratio of livestock, reducing residents’ consumption of pork meat and source-separated control of urban domestic wastewater, can certainly reduce P loads to surface water to some different degrees. The results suggest China should give the highest priority to reducing the amount of scaled-breeding livestock according to a rational carrying-capacity of farmlands. In Dianchi Basin, however, the most critical measure is proposed as source-separated control of urban domestic wastewater, while decreasing cropping and breeding activities also should be considered as effective measures.
