Changing redox potential by controlling soil moisture and addition of inorganic oxidants to dissipate pentachlorophenol in different soils

The potential for dissipation of pentachlorophenol (PCP) was investigated in soils from four different sites in China. These were an umbraqualf (Soil 1), a Plinthudult (Soil 2), a Haplustalf (Soil 3) and an Argiustoll (Soil 4) which were either flooded, to produce anaerobic conditions, or incubated aerobically at 60% water-holding capacity (WHC). The dissipation of PCP in Soil 1 at 60% WHC was higher than under flooded condition, while the opposite occurred in the other three soils. Under flooded conditions, the redox potential decreased significantly in Soil 1 and Soil 4, where sulphate reduction was occurred and the dissipation of PCP was statistically significant (about 96% and 98%, respectively) at the end of incubation. After addition of inorganic oxidants, dissipation of PCP was significantly inhibited by FeCl3, while Na2SO4 and NaNO3 had different effects, depending upon the soil type.

► The extent of the aerobic/anaerobic interface depends upon the soil properties.
► The dissipation of PCP was accelerated in some soils due to the soil-water interface.
► The addition of oxidants inhibited the decrease in soil redox potential.
► Most external oxidants added under flooded condition inhibited PCP dechlorination.