Influence of plants on the chemical extractability and biodegradability of 2,4-dichlorophenol in soil

This study investigated the fate and behaviour of [UL-14C] 2,4-dichlorophenol (DCP) in planted (Lolium perenne L.) and unplanted soils over 57 days. Extractability of [UL-14C] 2,4-DCP associated activity was measured using calcium chloride (CaCl2), acetonitrile–water and dichloromethane (DCM) extractions. Biodegradability of [UL-14C] 2,4-DCP associated activity was assessed through measurement of 14CO2 production by a degrader inoculum (Burkholderia sp.). Although extractability and mineralisation of [UL-14C] 2,4-DCP associated activity decreased significantly in both planted and unplanted soils, plants appeared to enhance the sequestration process. After 57 days, in unplanted soil, 27% of the remaining [UL-14C] 2,4-DCP associated activity was mineralised by Burkholderia sp., and 13%, 48%, and 38% of 14C-activity were extracted by CaCl2, acetonitrile–water and DCM, respectively. However, after 57 days, in planted soils, only 10% of the [UL-14C] 2,4-DCP associated activity was available for mineralisation, whilst extractability was reduced to 2% by CaCl2, 17% by acetonitrile–water and 11% by DCM. This may be due to the effect of plants on soil moisture conditions, which leads to modification of the soil structure and trapping of the compound. However, the influence of plants on soil biological and chemical properties may also play a role in the ageing process.