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Quantifying Phosphorus Flow Pathways Through Socioeconomic Systems at the County Level in China

Authors

  • Jun Bi,

    Corresponding author
    • Zengwei Yuan, School of the Environment, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing University, Nanjing 210046, P. R. China., Email: yuanzw@nju.edu.cn

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  • Qinqin Chen,

  • Ling Zhang,

  • Zengwei Yuan


Summary

Phosphorus (P) is a key factor in aquatic eutrophication, and P contamination has become a common issue worldwide. Many developing countries, including China, have made great efforts in the anti-P contamination battle. In this article we mainly discuss the P flow in Wuwei, a typical county in China with insufficient wastewater treatment, using the method of static substance flow analysis. We show that characterizing P metabolic pathways and flows at the county level can provide useful information about P pollution. Through complex calculations, we found that Wuwei County released 3,552 metric tons (t) of P into the local aquatic environment in 2008 and that its P load (3.35 kilograms P per capita per year [kg P/cap/yr] or 19.43 kilograms P per hectare per year [kg-P/ha/yr]) was greater than both the adjoining counties’ and Chaohu City's average levels combined. The agricultural subsystem discharged the largest quantity of P (2,572 t) and had a relatively low production conversion efficiency (32%) and P waste recycling rate (36%). The rural residential and small-scale livestock breeding systems also accounted for substantial portions of P discharge. Anti-P contamination efforts should consequently focus on those three subsystems. Based on the results of this case study, we also discuss the feasibility of potential efforts to reduce P contamination.

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