Study on the Distribution Characteristics of Metal Elements in Surface Runoff Source Water under Different Geomorphological Conditions in the Yunnan Section of the Jinsha River

为揭示金沙江云南段不同地貌区地表径流形成过程中金属元素的含量及空间分异规律，本研究基于深切割高山、红岩丘原、岩溶高原等6种地貌类型，选取7条金沙江一级支流布设18个河流源头水监测点和6个降雨水质监测点，于2022~2024年开展3次66项金属元素的连续监测，共采集144个水质样本。结合热图聚类、克鲁斯卡尔–沃利斯(Kruskal-Wallis)检验及斯皮尔曼(Spearman)相关性分析，解析数据特征。结果显示：66种目标金属元素中，42种被检出，其中钙(Ca)、镁(Mg)、钠(Na)等12种元素普遍存在(检出率100%)，砷(As)、镉(Cd)、铅(Pb)在红岩丘原与混合丘原显著富集(As最高0.018 mg/L，Cd最高0.00018 mg/L)。热图分析表明：混合丘原为高浓度元素聚集区(Ca均值33.67 mg/L，Mg均值13.77 mg/L)，深切割高山与岩溶高原为低浓度自然背景区(Ca均值11.67~16.43 mg/L)。金属元素分布受地貌类型与人类活动共同驱动，岩溶区As、Cd风险突出，混合丘原Zn、Pb受人为活动显著影响。建议构建“地貌–元素”响应模型，开展溶出机制研究，实施分区管控策略。To reveal the content and spatial differentiation patterns of metal elements during the formation of surface runoff in different geomorphological regions of the Yunnan section of the Jinsha River, this study selected 7 first-order tributaries of the Jinsha River across six geomorphological types, including deeply incised high mountains, red rock hill-plateau, and karst plateau, and established 18 river source water monitoring points and 6 rainfall water quality monitoring points. From 2022 to 2024, three rounds of continuous monitoring for 66 metal elements were conducted, yielding 144 water quality samples. Data characteristics were analyzed using heatmap clustering, Kruskal-Wallis tests, and Spearman correlation analysis. The results showed that 42 out of 66 target metal elements were detected, with 12 elements—calcium (Ca), magnesium (Mg), sodium (Na), etc.—being universally present (100% detection rate). Arsenic (As), cadmium (Cd), and lead (Pb) were significantly enriched in the red rock hill-plateau and mixed hill-plateau regions (maximum As: 0.018 mg/L; Cd: 0.00018 mg/L). Heatmap analysis indicated that the mixed hill-plateau was a high-concentration aggregation zone for elements (mean Ca: 33.67 mg/L; Mg: 13.77 mg/L), while deeply incised high mountains and karst plateaus served as low-concentration natural background areas (mean Ca: 11.67~16.43 mg/L). The distribution of metal elements was jointly driven by geomorphological types and human activities, with karst regions showing prominent risks of As and Cd, and Zn and Pb in mixed hill-plateau areas being significantly influenced by anthropogenic activities. The study recommends constructing a “geomorphology-element” response model, investigating dissolution mechanisms, and implementing zoned control strategies.