高污染土壤中多组分滴滴涕提取及污染土壤修复终点的研究

建立了高污染土壤中多组分滴滴涕（DDTs）含量的提取分析方法。采用加速溶剂萃取仪（ASE）对土壤中的DDTs进行提取;经固相萃取柱（SPE）净化和富集,最后采用气相色谱（GC）测定DDTs的含量。结果表明,本方法的回收率为84.0%-105.3%,相对标准偏差为1.3%-8.8%,仪器的检出限为0.010-0.030μg/kg,方法的检出限为0.30-0.50μg/kg。另外,本研究还采用Tenax-TA树脂对污染土壤连续氧化处理后的污染物进行提取,发现氧化4次后,p,p＇-DDE、p,p＇-DDD、o,p＇-DDT、p,p＇-DDT和总量DDTs可解吸的提取量都低于6%,并且未出现显著性变化（p〉0.05）。此方法可用于评价氧化后土壤中有机氯农药（OCPs）再次解吸至环境中的潜在风险,辅助判断污染土壤修复终点。

Study on electrokinetic remediation of cadmium contaminated soils

Kaolinite from a lead-zinc mining district,which was spiked with cadmium,has been treated by electrokinetics to investigate effects of treatment time and applied voltage gradient.The results showed that the increased test duration had induced a higher removal rate of cadmium.Being treated for 7 days,cadmium was removed from kaolinite dramatically.It was also found that higher removal rate happened when a higher voltage gradient was applied and cadmium accumulated near the cathode because pH increased.Increase of pH near the cathode caused accumulation of cadmium.Moreover,it was observed that cation exchange membrane which was placed between kaolinite and cathode could make pH lower than the initial value and avoid the higher pH near the cathode.As a result,the high concentration accumulation of cadmium near the cathode was avoided.

Use of Sorghum Crops for in Situ Phytoremediation of Polluted Soils

There has been carried out a comparative research, which allow us to determine the quantities and the central points of accumulation ofPb, Cu, Zn and Cd in the vegetative and reproductive organs of the four sorghum varieties （technical sorghtan, sugar sorghum, sudan grass and grain sorghnm）, as well as to ascertain the possibilities for their growth in soils contaminated with heavy metals and their application for phytoremediation purposes. The experimental plots were situated at different distances （0.1 and 15.0 kin） from the source of pollution-the Non-Ferrous Metal Works near Plovdiv, Bulgaria. On reaching commercial ripeness, the crops were gathered and the concentrations of Pb, Cu, Zn and Cd in their different parts-roots, stems, leaves and gains-were determined through dry mineralization. To determine the heavy metal content in the samples, ICP was used. A clearly distinguished trend exists which describes the accumulation of heavy metals within the vegetative and reproductive organs of the studied crops. Sudan grass and technical sorghum accumulated larger heavy metal quantities compared to sugar sorghum and grain sorghum, as the majority of the heavy metals was retained by the roots and a very small amount was translocated to epigeous parts. The depots for accumulation were in the following order： roots 〉 leaves 〉 stems 〉 grains. The studied crops can be related to metal-tolerant crops and can be cultivated on softs which are of low, medium or high contamination with lead, zinc and cadmium, as they do not exhibit a tendency of accumulating these elements in grains at levels above the maximum permissible concentrations for fodder. The selective accumulation of Pb, Cu, Zn and Cd in the roots and the possibility to remove the root-remains makes technical sorghum, sugar sorghum and Sudan grass extremely suitable for phytoremediation purposes. The possible use of grains for animal food guarantees the economic expedience upon the selection of these crops.

Treatment of Phenol-Contaminated Soil by Potassium Ferrate Based on pH Control

This study aims to optimize the treatment of phenol-contaminated soil by potassium ferrate. Variations in pH value can accurately reflect the state and reaction status of the entire treatment process. Therefore, the pH value could be an important variable for optimizing the reaction conditions and achieving the automatic control of the process. About 99.89% of phenol was removed after 10 min of the pH-contxolled reaction at a rotational speed of 40-70 r/min, with the initial phenol concentration equating to 10.0 g/kg and the total water consumption reaching 2.72 L （at a soil/water ratio of 1：0.68）. The test results could provide a basis for practical application of automatic reaction control by pH value.

In-situ remediation of deep petroleum-contaminated soil injection

A computational fluid dynamics(CFD)numerical simulation and field experiment were used to investigate optimal operating parameters of high-pressure jet grouting equipment and clarify the boundary law of the injection area in the remediation process.The response surface optimization design results show that the optimal injection pressure is 30 MPa,rotation speed is 23 r/min,commission speed is 30 cm/min,and the optimal injection diameter is 147.3 cm.Based on the CFD numerical simulation,the ratio of the injection core,turbulent zone,and seepage zone is approximately 1∶4∶2.The distribution law of jet core,turbulence zone and seepage zone at different cross-sections under 30 MPa operating conditions is as follows:The jet core radius is approximately 100 mm,the turbulence zone is mainly distributed at 100 to 500 mm,the seepage zone is mainly distributed at 500 to 700 mm,the seepage zone could be completed within 2 h,and the proportion of the three boundary zones in the injection zone is similar to that of the numerical simulation.This study provides theoretical parameters and practical reference for the remediation of deep pollution via in-situ chemical oxidation in the Loess Plateau soil environment.