CHANGES IN HEAVY METAL FLUXES IN CONTAMINATED SOIL INOCULATED WITH BURKHOLDERIA SP AND PENICILLUM SP MEASURED BY DGT

The developed diffusive gradients in thin films (DGT) devices with two binding phases of conventional Chelex 100 resin and an aqueous solution of polyacrylic acid sodium (PAAS) have been demonstrated to be useful tools for predicting the bioavailability of heavy metals in plants. However, whether various microbial activities affect the results of DGT with different binding phases is unclear. Experiments were conducted on both sterilized and non sterilized soil under various soil water and microorganism inoculation conditions to compare heavy metal fluxes in natural contaminated soil measured by the two devices with different binding phases. Our results showed that the labile metal fluxes measured by PAAS DGT and Chelex 100 DGT were significantly different, but the variation trends were similar. The heavy metal fluxes measured by both DGT devices showed very little variation under conditions of non-sterilized and water-amended natural contaminated soil, indicating that native microorganisms in the soil alone had very little influence on the DGT results. In contrast, when the soil was inoculated with Burkholderia sp. and Penicillium sp., the heavy metal fluxes measured by DGT increased in all cases, indicating the potential impact of exogenous microorganisms in the tested soil on metal behavior.