Land Use Change Impact on Redox Sensitive Trace Metal Bioavailability.

In many nations with rapidly growing populations and advancements in development, such as China and India, there is an increasing emergence in the juxtaposition of industry and croplands, where one can be a source of contaminant for the other. The close proximity of these two contrasting land uses in many parts of China has lead to great concern regarding the long-term contribution of industrial processes to crop contamination or potential decrease in agricultural yield. Agricultural land use conversions can also greatly impact the mobility of trace metals and nutrients within soils. A major biogeochemical factor that impacts crop yield is the bioavailability of toxic trace metals, which can vary greatly depending upon the soil moisture regime. In this study, we demonstrate that shifts in soil moisture content through conversion of upland crops to and from lowland, flooded crops lead to the mobilization of two distinct sets of toxic trace metals imparted by coal combustion byproducts, where some are mobilized under oxidizing conditions, while others are available for plants under reducing conditions. To do this, we applied fly ash acquired from a 2400 MW capacity coal power plant in Hubei, China, agricultural soils collected from agricultural fields near the industrial city of Wuhan, followed by treatment simulating flooded or non-flooded conditions. The results of this study demonstrate the potential of multi-metal contamination of soils and crops after land use conversion events.