Collaborative Research: Quantifying Human Forcing of Legacy Sediment and Metal Contamination Dynamics on the Yunnan Plateau of Southwestern China

在全球范围内，过去人类活动造成的金属污染阻碍了人类对环境系统，特别是土壤（农业）和水生系统（饮用水）的管理。管理这些历史污染物的一个普遍挑战是，它们可以通过风和水（通常附着在水中的沉积物上）运输。澄清这些运输途径的相对重要性对于成功管理受污染的土壤和防止未来世界范围内的土壤退化至关重要。在许多情况下，水-沉积物路径存在大量延迟，这些延迟给近期污染的风险评估带来了挑战。此外，最近的活动，如城市化，可以重新激活历史污染。本项目以中国云南地区为研究对象，这是一个有着多个金属提取和提纯历史时期的地区。重建云南空气和水传播污染物之间相互作用的悠久历史，可以检查随着工业革命而发生的大量全球金属污染对环境的影响以及土地利用变化对污染物流动的影响。本研究旨在从更长远的角度研究中国西南地区的沉积物动态，并评估湖泊环境中金属积累的时间、规模、速率和来源。具体而言，该项目将三个目标联系起来：1)利用地球化学混合模型定量估算流域土壤中金属污染物的储存量并确定其来源；2)通过检查沉积物中记录的历史事件，确定对这些金属污染物的侵蚀、运输、积累和再分配的控制，特别是人为控制；3)记录自然气候变率和人类活动对湖泊系统金属积累的影响。综合起来，这些目标提供了衡量景观中储存的污染对所有现代人类系统的风险的手段，并增强了我们对累积的流域影响如何影响我们的地球系统的理解。该奖项由地貌学和土地利用动力学项目、刺激竞争性研究实验项目和国际科学与工程办公室共同资助。

Globally, metal contamination from past human activities hinders human management of environmental systems, particularly soils (agriculture) and aquatic systems (drinking water). One of the universal challenges in the management of these historical contaminants is that they can be transported by both the wind and in water (generally attached to sediments in water). Clarification of the relative importance of these transport pathways is fundamental to the successful management of contaminated soils and prevention of future soil degradation worldwide. In many cases, there are substantial delays in the water-sediment pathway, and these delays create challenges in risk evaluation of recent contamination. Further, more recent activities such as urbanization can remobilize historical contamination. This project focuses on the Yunnan region of China, a region with multiple historical periods of metal extraction and purification. Reconstruction of the long history of interactions between the airborne and waterborne contaminant transport in the Yunnan allows examination of the environmental implications of substantial global metal contamination that has occurred with the industrial revolution and the influence of land use changes on contaminant mobilization. This research aims to develop a longer-term perspective of sediment dynamics in southwestern China and assess the timing, magnitude, rate, and source of metal accumulation in lake environments. In particular, the project links three goals: 1) Quantitatively estimate the amount of metal contaminants stored in watershed soils and attribute their source using geochemical mixing models; 2) Identify the controls on erosion, transport, accumulation, and redistribution of these metal contaminants, particularly human controls by examination of historical events recorded in sediments; and 3) Document the influences of natural climate variability versus human activity on metal accumulation in lake systems. When combined, these goals provide the means to measure the risks of contamination stored in the landscape to all modern human systems and enhance our understanding of how cumulative watershed impacts influence our Earth system.This award is cofunded by the Geomorphology and Land-use Dynamics Program, the Experimental Program to Stimulate Competitive Research, and the Office of International Science and Engineering.