Abstract
High residues of DDT in agricultural soils are of concern because they present serious threats to food security and human health. This article focuses on remediation of DDT-contaminated soil using laccase under different soil oxygen and soil pH conditions. The laboratory experiment results showed significant effects of soil oxygen conditions and soil pH on remediation of DDT-contaminated soil by laccase at the end of a 25-d incubation period. This study found the positive correlation between the concentration of oxygen in soil and the degradation of DDT by laccase. The residue of DDTs in soil under the atmosphere of oxygen decreased by 28.1% compared with the atmosphere of nitrogen at the end of the incubation with laccase. A similar pattern was observed in the remediation of DDT-contaminated soil by laccase under different flooding conditions, the higher the concentrations of oxygen in soil, the lower the residues of four DDT components and DDTs in soils. The residue of DDTs in the nonflooding soil declined by 16.7% compared to the flooded soil at the end of the incubation. The residues of DDTs in soils treated with laccase were lower in the pH range 2.5–4.5.
Highlights
High residues of DDT in agricultural soils are of concern because they present serious threats to food security and human health
The effects of different soil oxygen conditions and different soil pH on remediation of DDT-contaminated soil by laccase were investigated in laboratory batch experiments
The soil sample was kept at room temperature for four weeks, after that remediation experiments were carried out to assess the remedial potential of laccase
Summary
1,1,1-Trichloro-2,2-bis (4-chlorophenyl) ethane (DDT) was a widely used organochlorine pesticide with high toxicity and residual levels. In some areas the DDT concentration found in soil markedly exceeds the level set by the national soil quality standards (GB/T 18407-2001). The concentration of DDT exceeded the national soil quality standards in the agricultural soils of North of Zhejiang Province [2]. Soil pollutants may adversely affect agricultural products. Remediation of the DDT-contaminated soils must be conducted to ensure the agricultural products safety and human health. Laccase (EC 1.10.3.2) can catalyze the oxidation of organic compounds [19], and has been widely used to degrade pollutants from environment [20,21,22]. The effects of different soil oxygen conditions and different soil pH on remediation of DDT-contaminated soil by laccase were investigated in laboratory batch experiments
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