作者：Liu, H., Meng, C., Wang, S., Li, Y., Fu, H. & Ouyang, W.

Plateau lakes are highly sensitive to anthropogenic phosphorus (P) enrichment. Despite recent management strategies reducing watershed P inputs, lake eutrophication persists, indicating a delayed recovery of water P level in response to external P reduction. This study focuses on Xingyun Lake, a typical shallow plateau lake in central Yunnan Province (Yuxi City), China, and applies the net anthropogenic P input (NAPI) model to evaluate the influences of different P sources in the watershed of Xingyun Lake from 1989 to 2020. The convergent cross mapping (CCM) approach was utilized to detect nonlinear and time-lagged causal relationships between NAPI and total phosphorus (TP) dynamics. Segmented regression analysis was further used to identify thresholds of P inputs leading to abrupt changes in lake TP concentrations. NAPI ranged from 1,148 +/- 304 to 6,984 +/- 2,206 kg km(-2) yr(-1) during the study period and was primarily driven by food/feed net P input (Pim), ore mining P input (Pore), and fertilizer P input (Pfer). From 2000 to 2020, Pore was the dominant contributor to NAPI changes in the northern and eastern region, particularly in Jiangcheng and Luju towns. CCM analysis identified a significant nonlinear and unidirectional causal link from NAPI to TP with a 4-year time lag. Threshold analysis demonstrated that lake TP concentrations exhibited a nonlinear upward trend when Pfer and Pore exceeded 806 and 1,305 kg km(-2) yr(-1), respectively. This study provides the first quantitative evidence for the time-lagged response of lake P dynamics to anthropogenic P inputs in plateau lake systems, offering theoretical support and technical guidance for setting watershed water quality improvement goals and optimizing policy intervention timing.

高原湖泊对人为磷富集高度敏感。尽管近年来的管理策略减少了流域磷输入，湖泊富营养化依然持续，表明水体磷水平对外源磷削减的恢复存在滞后。本研究以中国云南省（玉溪市）中部典型浅水高原湖泊——星云湖为对象，应用净人为磷输入（NAPI）模型，评估了1989至2020年间星云湖流域不同磷源的影响。利用收敛交叉映射（CCM）方法检测NAPI与总磷（TP）动态之间的非线性和时滞因果关系，并进一步采用分段回归分析识别导致湖泊TP浓度突变性上升的磷输入阈值。研究期间，NAPI介于1148 ± 304至6984 ± 2206 kg·km⁻²·yr⁻¹之间，主要由食品/饲料净磷输入（Pim）、矿石开采磷输入（Pore）和化肥磷输入（Pfer）驱动。2000至2020年，Pore是流域北部和东部地区NAPI变化的主要贡献者，尤其在江城镇和路居镇。CCM分析确定了NAPI对TP存在显著的非线性单向因果联系，且具有4年的时滞。阈值分析表明，当Pfer和Pore分别超过806和1305 kg·km⁻²·yr⁻¹时，湖泊TP浓度呈现非线性上升趋势。本研究首次为高原湖泊系统磷动态对人为磷输入的时滞响应提供了定量证据，为制定流域水质改善目标和优化政策干预时机提供了理论支持与技术指导。

（来源：Journal of Hydrology 2026  DOI: 10.1016/j.jhydrol.2026.134969）