Oxalate and root exudates enhance the desorption of p,p'-DDT from soils.
The abiotic desorption of p,p'-DDT from seven Chinese soils spiked with p,p'-DDT and the effects of oxalate at 0.001-0.1M and the root exudates of maize, wheat, and ryegrass were evaluated using batch experiments. Soil organic carbon played a predominant role in the retention of DDT. Oxalate significantly increased the desorption of p,p'-DDT, with the largest increments ranging from 11% to 54% for different soils. Oxalate addition also resulted in the increased release of dissolved organic carbon and inorganic ions from soils. Root exudates had similar effects to those of oxalate. Root exudates significantly increased DDT desorption from the soils, and the general trend was similar among the plant species studied for all the soils (p > 0.05). Low molecular weight dissolved organic carbon amendments caused partial dissolution of the soil structure, such as the organo-mineral linkages, resulting in the release of organic carbon and metal ions and thus the subsequent enhanced desorption of DDT from the soils. The enhancing effects of oxalate and root exudates on DDT desorption were influenced by the contents of soil organic carbon and dissolved organic carbon in soils.
Luo
Lei
L
State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085, China.
Zhang
Shuzhen
S
Shan
Xiao-Quan
XQ
Zhu
Yong-Guan
YG
D000327:Adsorption; D002244:Carbon / Q000032:analysis; D003634:DDT / Q000032:analysis / Q000737:chemistry*; D008129:Lolium; D010070:Oxalates / Q000737:chemistry*; D010575:Pesticides / Q000032:analysis / Q000737:chemistry*; D018517:Plant Roots / Q000378:metabolism*; D012989:Soil Pollutants / Q000032:analysis; D014908:Triticum; D003313:Zea mays
D010070:Oxalates; D010575:Pesticides; D012989:Soil Pollutants; D002244:Carbon; D003634:DDT