Key Laboratory for Resource Use and Environmental Remediation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
Key Laboratory for Resource Use and Environmental Remediation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
J Environ Manage. 2023 Nov 1;345:118883. doi: 10.1016/j.jenvman.2023.118883. Epub 2023 Sep 6.
Legacy phosphorus (P) in watersheds continuously affects the water quality. The time lag between anthropogenic P input and algal bloom has made P dynamics prediction in aquatic ecosystems more challenging. Whether the legacy P in the Yangtze River Watershed (YRW) exceeds its storage threshold remains unknown, and the continuous impact of legacy P on the water quality has not been analyzed. This study aimed to evaluate variation trends (1970-2018) and influencing factors for accumulated P in the YRW under different economic development periods, quantitatively identify the watershed P storage threshold based on the two split line models and estimate the time required for the return of legacy P to the baseline level using an exponential decay process. The results showed that the P storage threshold of the YRW was surpassed due to intense anthropogenic activities, and the residual P still had an impact on aquatic ecosystems for a long time. The dissolved total P loadings may become the top priority to achieve better P management goals. The time lags for the legacy P restoration would require for about 1000 years to be exhausted. The legacy P in the YRW would continuously undermine the restoration efforts of the water quality. The combined effects of watershed P surplus reductions and depletion of residual P may become essential to better manage P in the future. We still need to strengthen our efforts to make soil legacy P more absorbed by crops and improve sewage treatment capacity to achieve sustainable development of YRW.
流域中遗留的磷（P）持续影响着水质。人为 P 输入与藻类大量繁殖之间存在时间滞后，这使得水生生态系统中 P 动态预测变得更加具有挑战性。长江流域（YRW）中的遗留 P 是否超过其储存阈值尚不清楚，且尚未分析遗留 P 对水质的持续影响。本研究旨在评估不同经济发展时期 YRW 中累积磷的变化趋势（1970-2018 年）及其影响因素，基于两条分割线模型定量确定流域 P 储存阈值，并利用指数衰减过程估算遗留 P 恢复到基线水平所需的时间。结果表明，由于人类活动的强烈影响，YRW 的 P 储存阈值已经超过，残留 P 仍将对水生生态系统产生长期影响。溶解态总磷负荷可能成为实现更好 P 管理目标的首要任务。遗留 P 的恢复时间滞后需要大约 1000 年才能耗尽。YRW 中的遗留 P 将持续破坏水质的恢复工作。流域 P 盈余减少和残留 P 消耗的综合影响可能成为未来更好管理 P 的关键。我们仍需加强努力，使土壤中遗留 P 更多地被作物吸收，并提高污水处理能力，以实现 YRW 的可持续发展。
