Burning fossil fuels has resulted in a prominent yet unintended manipulation of the global sulfur cycle. Emissions of sulfur dioxide and reactive sulfur to the atmosphere have caused widespread health and environmental impacts and have led, ultimately, to calls to decrease sulfur emissions. However, anthropogenic modification of the sulfur cycle is far from over. Using four contrasting case studies from across the United States, we show how high levels of sulfur are added to croplands as fertilizers and pesticides and constitute a major yet under-studied environmental perturbation. Long-term sulfur additions to crops probably cause similar consequences for the health of soil and downstream aquatic ecosystems as those observed in regions historically impacted by acid rain, yet the cascade of effects has not been broadly explored. A new wave of research on the sulfur cycle will require studies that examine the integrated roles of climate, hydrology and other element cycles in modifying sulfur processes and flows within and downgradient of agricultural source areas. Such research must include not only scientists, but also farmers, regulating authorities and land managers who are engaged in developing approaches to monitor and mitigate environmental and human health impacts.

燃烧化石燃料导致对全球硫循环的重大而无意的操纵。向大气中排放的二氧化硫和反应性硫已引起广泛的健康和环境影响，并最终导致呼吁减少硫排放。然而，硫循环的人为改变远未结束。使用来自美国各地的四个不同的案例研究，我们证明了如何向农田中添加高含量的硫作为肥料和杀虫剂，并构成了一个主要但尚未被研究的环境扰动。长期向农作物中添加硫可能会对土壤和下游水生生态系统的健康造成类似的后果，就像在历史上受酸雨影响的地区所观察到的那样，但尚未广泛探索其级联效应。关于硫循环的新研究浪潮将需要进行研究，以研究气候，水文和其他元素循环在改变硫源过程和农业源区内部以及下游的硫流过程中的综合作用。此类研究不仅必须包括科学家，而且还必须包括农民，监管机构和土地管理人员，他们致力于开发监测和减轻环境和人类健康影响的方法。