Mechanism of arsenic accumulation in sediments of the northern China: Insight from provenance, weathering processes and paleoenvironmental changes

Abstract

Fluctuations in sedimentary As burial have been reported throughout geological timescales, but detailed weathering pathways governed by climatic evolution are poorly understood. To this end, we reconstructed various climatic stages utilizing lithologies, geochemical indicators, and dating data and illustrated the physical–chemical pathways that affect As accumulation and release. The results revealed six climate changes. The climatic evolution was a consequence of the relative intensities of the East Asian summer monsoon (EASM) and East Asian winter monsoon (EAWM). Higher sedimentary As, Fe, and Feclay concentrations are observed in the cold-arid climates and suggest As accumulation occurred due to strong physical erosion. Moreover, correlations between Feclay and clay minerals indicate favorable clay minerals during cold-arid climates (e.g., illite, chlorite, and illite–smectite mixed layer) enhanced the accumulation of Fe-rich clay minerals and then As burial. In warm-humid climates, intense biogeochemical processes prevailed and contributed to crystalline Fe enrichment, which might accelerate As release. This analysis shows climate shifts alter solid As partitioning in sedimentary basins and potentially result in significant impacts with respect to global As contamination.