The Influence Of Adsorption And Migration On DDT In The Riverbed’s Sediments By The Humic Acid Colloid

Although DDT has been banned for nearly30years, residues are still detected inenvironmental media and human body. This indicates that the threaten of DDT to ecologicalenvironment and human healthy still exists. Thus，the mode, migration conversion anddestination of occurrence of DDT in the environment, become one of the hottest issues thatthe domestic and foreign scholars’concern and research in recent years. Scholars pay moreattention to the law of DDT in soil, sediment adsorption migration. However, the research onthe influence of DDT in soil and sediment migration by colloids in groundwater almost empty.This research based on the Guanzhong Basin which is a typical study area. We defined DDTas the target pollutants, studied on the influence of adsorption and migration on DDT in theWei River sediments by the humic acid colloid in shallow groundwater by a combination ofstatic experiment and dynamic experiment. Conclusions are following:1The static adsorption kinetics experiments indicate that:When the sediments without humic acid colloid, the sediments’ adsorptive equilibriumtime of DDT is120h. When the sediments with humic acid colloid, the sediments’ adsorptionrate of DDTis accelerated, the time to reach equilibrium is shortened from120h to the48h.When the sediments without humic acid colloid, the sediments’ adsorption kinetics ofDDT in line with the first order kinetics equation. When the sediments with humic acidcolloid, the sediments’ adsorption kinetics of DDT in line with the second order kineticsequation.2The adsorption thermodynamics experiments indicate that:When the sediments without humic acid colloid, the form of the sediments’ adsorptionisotherms by o,p’-DDT、p,p’-DDD and p,p’-DDE were S-shaped, L-and L-shaped.When thesediments with humic acid colloid, the form of the sediments’ adsorption isotherms byo,p’-DDT、p,p’-DDD and p,p’-DDE were L-shaped, S-and L-shaped.When the sediments without humic acid colloid, the sediments’ adsorption of o,p’-DDTin line with Freundlich equation, the adsorption of p,p’-DDD and p,p’-DDE in line withLangmuir equation.When the sediments with humic acid colloid, the sediments`adsorption ofo,p’-DDT and p,p’-DDE in line with Langmuir equation, the adsorption of p,p’-DDD in linewith Freundlich equation.3The dynamic sand pillar leaching experiments indicate that:When the leaching experiments on the0.01mol/L chloride ion, chloride ion takes3h to penetrate the pillar, the sediments’ adsorption would become saturated after5h, the effluentconcentration was the the same as initial concentration; When the leaching experiments onthe mixed solution by0.01mol/L chloride ion and100mg/L humic acid colloid, chloride iontakes2.5h to penetrate the pillar, the sediments’ adsorption would become saturated after5h,the effluent concentration was the the same as initial concentration.This indicates that:thehumic acid colloid makes the chloride ion penetrate the pillar earlier,but the residence timeof chloride ion in sediments is prolonged.When the leaching experiments on the70μg/LDDT, DDT takes4h to penetrate the pillar,the sediments’ adsorption would become saturated after7h, the effluent concentration wasthe the same as initial concentration; When the leaching experiments on the mixed solutionby70μg/LDDT and5mg/L humic acid colloid, DDT takes3h to penetrate the pillar, thesediments’ adsorption would become saturated after5h, the effluent concentration was thethe same as initial concentration. This indicates that: the humic acid colloid makes the DDTpenetrate the pillar earlier, and the residence time of DDT in sediments is shortened.