磷是人类赖以生存的重要营养元素，快速的社会经济发展改变了磷循环模式。人口增长、饮食结构变化以及经济高速发展，进一步加速了磷的单向流动，造成了大量磷排放和环境影响。作为磷的生产和使用大国，我国磷排放和污染现状不容乐观。本文从全产业链出发，结合质量平衡原理、环境压力核算方法和结构分解分析对我国1949—2012年间磷循环网络变化对磷排放的影响展开研究，为从供给侧实现磷的可持续管理提供政策参考。

本文基于质量平衡原理构建我国1949—2012年磷元素实物型供给使用表。以供给使用表为基础，通过公式计算将其转换为实物型投入产出表，描述磷元素在环境经济系统中的流动过程，反映产品间及系统整体的输入输出平衡关系。在此基础上，分别从生产视角和供给视角识别影响磷排放的关键产品。结合结构分解分析探究供给视角下社会经济因素变化所导致的磷排放量变化，得到各因素变化对磷排放变化的贡献。并以2012年为基准年，对影响磷循环活动的相关参数进行调控，构建基准情景、发展情景和综合调控情景3种情景，计算可能出现的81种磷排放变化情况。主要研究结果如下：

（1）环境压力核算结果表明，基于生产视角的磷排放重点产品包括玉米、稻谷、小麦、垃圾处置服务和磷石膏，粮食作物始终占据影响磷排放的主导地位。与生产视角下的计算结果不同，磷矿石是导致基于供给视角磷排放的主要产品，1978—2012年磷矿石基于供给视角下的磷排放量呈现明显增长趋势，累计增加107.2百万吨。其中，2012年产业链上游磷矿石的投入导致的磷排放量占总排放量的74.9%。在产业链上游对磷矿石的投入会间接推动下游部门产生大量磷排放。

（2）结构分解分析结果表明，从整体来看，人均初始投入水平变化是驱动磷排放量增加的关键因素，其次是人口、排放强度和初始投入结构的变化，共驱动磷排放量增加11.3百万吨。其中，排放强度的变化主要集中在磷化工业、种植业、畜禽养殖业和废水处理行业。生产结构变化是驱动磷排放量减少的因素，它驱动磷排放量减少2.2百万吨。此外，磷排放的影响机制与时代背景紧密相关，各历史阶段中社会经济因素对磷排放的驱动情况不同。

（3）情景分析结果表明，保持其他社会经济因素不变的情况下，发展情景和综合调控情景下人均初始投入水平改变导致的磷排放变化量最为突出，分别为4.5百万吨和-5.5百万吨。综合调控情景下，对排放强度的管控促进磷排放减少1.6百万吨。对供应链上游磷矿石开采量的调控可以极大减少下游的磷排放。提高磷石膏综合利用水平，可以减少由于磷石膏堆积和存储导致的磷排放及相关环境污染问题。

Phosphorus (P) is an essential nutrient for human survival, and rapid socio-economic development has changed the P cycling patterns. Population growth, dietary changes and rapid economic development have further accelerated the unidirectional flow of P, resulting in large P emissions and environmental impacts. As a major producer and consumer of P, the current situation of P emissions and pollution in China is not optimistic. This paper aims to investigate the impact of changes in the P cycle network on P emissions in China between 1949 and 2012 from a supply perspective, combining mass balance principle, environmental pressure accounting methods, and structural decomposition analysis. It also provides policy reference for achieving sustainable management of P from the supply side.

Based on the mass balance principle, we construct the physical supply and use table of P in China from 1949 to 2012. Then, we converted the physical supply and use table into the physical input-output table through formula calculation to describe the flow process of P in the environmental economic system and reflect the input-output balance relationship among products and the system as a whole. On the basis of this, key products that affecting P emissions were identified from the production perspective and supply perspective respectively. The changes in P emissions due to changes in socio-economic factors from the supply perspective are explored by combining structural decomposition analysis. The contributions of changes in each factor to the changes in P emissions are obtained. Then, the relevant parameters affecting P cycling activities were regulated using 2012 as the base year. We construct three scenarios and calculate 81 possible P emission changes. The three scenarios including the baseline scenario, the development scenario and the integrated regulation scenario. The main results are summarized as follows:

(1) The results of the environmental pressure accounting show that show that the key products of P emissions based on the production side include maize, rice, wheat, waste disposal services and phosphogypsum. Food crops consistently dominate the impact of P emissions. Different from production-side discovery, the main product of P emissions based on the supply perspective is phosphate rock. The P emissions from phosphate rock based on the supply side show a significant increase from 1978 to 2012, with a cumulative increase of 107.2 Mt (million tonnes). The input of phosphate rock in upstream of the industry chain in 2012 resulted in 74.9% of the total P emissions. This indicates that the input of phosphate rock in the upstream of the industry chain will indirectly promote the increase of P emissions in the downstream.

(2) The results of the structural decomposition analysis show that, as a whole, changes in primary input levels are the key factor driving the increase in P emissions, followed by changes in population, emission intensity and primary output structure, which together drive an increase in P emissions of 11.3 Mt. Of these, changes in emission intensity were concentrated in the P chemical industry, cultivation, animal husbandry and wastewater treatment industry. The change in production structure is the factor driving the decrease in P emissions, which drives a decrease of 2.2 Mt. In  addition, the influence mechanism of P emissions is closely related to the context of the era, with socio-economic factors driving P emissions differently in each historical stage.

(3) The results of the scenario analysis show that holding other socio economic factors constant, the development scenario and the integrated regulation scenario have the most prominent amount of change due to the change in the primary input level, which are 4.5 Mt and -5.5 Mt, respectively. The control of emission intensity in the integrated control scenario reduces P emissions by 1.6 Mt. Regulating the amount of phosphate rock mined in the upstream of the supply chain can significantly reduce P emissions in the downstream. In addition, increasing the level of comprehensive utilization of phosphogypsum can reduce P emissions and the associated environmental pollution problems caused by phosphogypsum accumulation and storage.