Anthropogenically-induced atmospheric Pb cycle in low-latitude Asia since the Industrial Revolution recorded by high-resolution stalagmites

The vigorous convective circulation in the low-latitude regions plays an important role in the global lead (Pb) cycle in the context of growing atmospheric Pb pollution. However, the brevity of reconstructions of regional Pb pollution limits our understanding of the low-latitude Pb cycle. Here, we presented continuous stalagmite-based Pb records from Klang (KL) cave in the Thai-Malay peninsula, and complementary stalagmite-based Pb records from Xianrenyan (XRY) cave in upwind region to explore the combined effects of atmospheric circulations and anthropogenic Pb emissions on the regional Pb cycle in the low-latitude regions. The analysis suggests that the XRY records reflect regional Pb pollutions in southern China, while the KL records could represent regional Pb recycling in low-latitude Asia, with the Pb pollutants coming from local and upwind territories (e.g., China, India). Moreover, the Pb variations in peninsular Thailand are significantly influenced by the East Asian Winter Monsoon (EAWM) strength with high (low) amount of Pb pollutants from the upwind territories transported to the study area during the strong (weak) EAWM. However, by comparing KL records with XRY records and other existing geological and meteorological records, we found the EAWM-induced Pb variations in the late 20th century were overwhelmed by unprecedented industry-derived Pb emissions from eastern China. Our findings suggest the ever-increasing anthropogenic emission could surpass the atmospheric circulation controls on the regional Pb cycle, offering a new perspective on understanding the relative influence of natural and anthropogenic forcing.