College of Environmental & Resource Sciences, Zhejiang University, Hangzhou, 310058, China.
Department of Land, Air, and Water Resources, University of California, Davis, CA, 95616, USA.
Water Res. 2020 Jun 15;177:115779. doi: 10.1016/j.watres.2020.115779. Epub 2020 Apr 6.
Quantitative information on long-term net anthropogenic phosphorus inputs (NAPI) and its relationship with riverine phosphorus (P) export are critical for developing sustainable and efficient watershed P management strategies. This is the first study to address long-term (1980-2015) NAPI and riverine P flux dynamics for the Yangtze River basin (YRB), the largest watershed in China. Over the 36-year study period, estimated NAPI to the YRB progressively increased by ∼1.4 times, with NAPI (chemical fertilizer input + atmospheric deposition + seed input) and NAPI (net food/feed imports + non-food input) contributing 65% and 35%, respectively. Higher population, livestock density and agricultural land area were the main drivers of increasing NAPI. Riverine total phosphorus (TP), particulate phosphorus (PP) and suspended sediment (SS) export at Datong hydrological station (downstream station) decreased by 52%, 75% and 75% during 1980-2015, respectively. In contrast, dissolved phosphorus (DP) showed an increase in both concentration (∼7-fold) and its contribution to TP flux (∼16-fold). Different trends in riverine P forms were mainly due to increasing dam/reservoir construction and changes in vegetation/land use and NAPI components. Multiple regression models incorporating NAPI, NAPI, dam/reservoir storage capacity and water discharge explained 84% and 92% of the temporal variability in riverine DP and PP fluxes, respectively. Riverine TP flux estimated as the sum of DP and PP fluxes showed high agreement with measured values (R = 0.87, NSE = 0.84), indicating strong efficacy for the developed models. The model forecasted an increase of 50% and 7% and a decrease of 15% and 22% in riverine DP flux from 2015 to 2045 under developing, dam building, NAPI and NAPI reduction scenarios, respectively. This study highlights the importance of including enhanced P transformation from particulate to bioavailable forms due to river regulation and changes in land-use, input sources and legacy P pools in development of P pollution control strategies.
定量了解长期人为向河流输入的磷（NAPI）及其与河流磷输出的关系，对于制定长江流域（YRB）等中国最大流域可持续和有效的流域磷管理策略至关重要。本研究首次针对长江流域（YRB）进行了长期（1980-2015 年）NAPI 和河流磷通量动态的研究。在 36 年的研究期间，长江流域的 NAPI 估算值逐渐增加了约 1.4 倍，其中化肥投入+大气沉降+种子输入和净粮食/饲料进口+非粮食输入分别占 65%和 35%。较高的人口、牲畜密度和农业用地面积是 NAPI 增加的主要驱动因素。大通水文站（下游站）的河流总磷（TP）、颗粒态磷（PP）和悬浮泥沙（SS）的输出量在 1980-2015 年间分别减少了 52%、75%和 75%。相比之下，溶解态磷（DP）的浓度增加了约 7 倍，对 TP 通量的贡献增加了约 16 倍。河流磷形态的不同趋势主要归因于大坝/水库建设的增加以及植被/土地利用和 NAPI 成分的变化。包含 NAPI、NAPI、大坝/水库储水量和水流量的多元回归模型分别解释了河流 DP 和 PP 通量时间变化的 84%和 92%。将 DP 和 PP 通量之和作为河流 TP 通量的估算值与实测值高度吻合（R=0.87，NSE=0.84），表明所开发模型具有很强的有效性。模型预测，在发展中、大坝建设、NAPI 和 NAPI 减少情景下，2015 年至 2045 年期间，河流 DP 通量将分别增加 50%和 7%，减少 15%和 22%。本研究强调了在制定磷污染控制策略时，考虑到河流调控以及土地利用、输入源和遗留磷库的磷转化增强，从颗粒态到生物可用态的变化，对于控制磷污染的重要性。
