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DDT is a persistent pesticide that was banned in most countries due to its significant environmental and human health hazards. Bioremediation has the potential for in-situ treatment of DDT contaminated sediment and soils. With the right microorganisms and conditions, DDT and its primary metabolites, DDD and DDE can be degraded into 4-chlorobenzoic acid or 4,4- dichlorobenzophenone under aerobic and anaerobic conditions, respectively. The extent of degradation and time required will depend on the initial concentration, respiration mode and microorganisms present. This review provides brief overview of bioremediation and discusses some of the key degradation pathways of DDT.

The primary objective of this project was to study the origin and formation of sulfate in Ohio soils in order to assist ODOT in selecting appropriate soil stabilization strategies for roadway construction. ODOT recently encountered appreciable amounts of sulfate in soils on projects where chemical stabilization of the subgrade was performed. These projects, LAK-2-3.32/7.76, PAU-24-0.00, PAU/DEF-24-12.30/0.00, and MRW-71-3.17, were included in this study. Defiance County had the most samples that were above moderate (5000 ppm) and unacceptable (8000 ppm) risk. Morrow County had the next highest number of unacceptable sulfate levels. Of the 42 Lake County soils analyzed by UA, 11 were above the 3000 ppm SO4. It is important to note that Lake County did have a higher overall number of elevated sulfate readings if the results conducted by consultants were included. The soils surrounding the road construction activities along State Route (SR) 2 and US Route (USR) 24 were similar. One probable cause of elevated sulfate levels could be the upward migration of gypsum in the till fractures. Another potential source of sulfate in Paulding and Defiance Counties was attributed to the direct deposition of gypsum as a soil amendment for farmlands. The fill used during road construction along I-71 was much thicker than that used for USR 24 or SR 2, which nullifies the probable impact of water migration from till fractures for Morrow County. The most likely sources of soil sulfate in Morrow County were deposition of gypsum for farmland activities and the oxidative weathering of pyrite. Oxidation of pyrite was corroborated by samples from Morrow County having very high iron concentrations. The addendum found that the Paulding-Defiance soils that were high in soluble SO4 and aluminum swelled the most. The fact that H4S exhibited more swell than H4D could indicate that the sulfate in the water (either by infiltration or used during stabilization) could impact the extent of heave. No recommendation can be made associated with the potential from infiltration as groundwater flow and precipitation cannot be controlled.