Arsenic in a speleothem from central China: Stadial-interstadial variations and implications

In a pilot study, arsenic in a stalagmite (SJ3) collected from Central China was measured, and its association with past climate and environment was explored. Most of the SJ3 arsenic concentrations ranged from 120 to 320 ppb with the highest concentrations associated with relatively warm and humid climatic phases and lowest concentrations with cold and dry phases. The SJ3 arsenic record was very similar to the manganese record of SJ3. Variations of arsenic in SJ3 might be controlled by metal oxides of iron, manganese, and aluminum in karst groundwater at the study site, which in turn were closely related with changes in past climate and environment. A considerable proportion of arsenic was in excess over manganese in SJ3, which might be related with incorporation of arsenic into the calcite lattice during the formation of SJ3. It was speculated that more arsenic was released due to stronger weathering of the surface soils and sequestrated by metal oxides in karst groundwater under warm-humid climatic phases than under cold-dry phases. This suggested that climate shift might alter arsenic balance in sedimentary areas and aquifer systems and potentially exert significant influence on global arsenic contamination.