非洲矿业对农业的下游影响
Downstream impacts of mines on agriculture in Africa
Journal of Development Economics · 2025 · [{"name": "Lukas Vashold", "affiliation": ["Vienna University of Economics and Business"]}, {"name": "Gustav Pirich", "affiliation": ["Vienna University of Economics and Business"]}, {"name": "Maximilian Heinze", "affiliation": ["Vienna University of Economics and Business"]}, {"name": "Nikolas Kuschnig", "affiliation": ["Vienna University of Economics and Business", "Monash University"]}]
中文摘要
非洲的采矿活动正在快速扩张，其产生的负外部性仍未得到充分理解。本文针对整个非洲大陆范围内矿山水污染对下游植被与农业的影响提供了因果证据。我们利用一项自然实验——矿山导致河流网络中的水污染呈现断点（不连续）分布——比较上游与下游地点的植被健康状况。我们发现，矿山使下游植被峰值显著降低1.3%–1.5%，损害了超过74,000平方公里农田的生产率。这些降低仅在紧邻区域就对应每年91,000–205,000吨谷物作物的损失，在肥沃地区和以金矿开采为主的地区影响尤为严重。我们的研究结果凸显了采矿活动的巨大外部性，表明迫切需要加强监督与监管。
• 评估采矿引致水污染对农业和植被的因果影响。
• 利用有向河流网络，在断点设计中进行识别。
• 非洲采矿使下游植被峰值降低1.3%–1.5%。
• 超过74,000平方公里农田受到直接影响，且影响可能波及更广范围。
• 效应在金矿开采地区和肥沃农业地区最强。
Abstract
Mining operations in Africa are expanding rapidly, creating negative externalities that remain poorly understood. In this paper, we provide causal evidence for the impact of water pollution from mines on downstream vegetation and agriculture across the continent. We exploit a natural experiment, where mines cause a discontinuity in water pollution along river networks, to compare vegetation health in upstream and downstream locations. We find that mines significantly reduce peak vegetation downstream by 1.3–1.5%, impairing the productivity of over 74,000 km 2 of croplands. These reductions correspond to annual losses of 91,000–205,000 tons of cereal crops in the immediate vicinity alone, with particularly severe effects in fertile regions and areas where gold mining predominates. Our findings highlight substantial externalities of mining and demonstrate an urgent need for oversight and regulation. • Assess causal impacts of mining-induced water pollution on agriculture and vegetation. • Exploit directed river networks for identification in a discontinuity design. • Mining in Africa reduces peak vegetation downstream by 1.3–1.5% • Over 74,000 km 2 of croplands are immediately affected and impacts may reach further. • Effects are strongest in gold mining areas and fertile agricultural regions.