过碳酸钠修复石油污染土壤及其环境效应

Remediation of petroleum-contaminated soil by sodium percarbonate and its environmental effects

化学氧化可快速高效修复石油污染土壤,但很少关注研究其对土壤质量的影响以及残留污染物的环境风险。本文以过碳酸钠(SPC)为氧化剂,以柠檬酸(CA)/硫酸亚铁[Fe(Ⅱ)]为催化剂,分析了其对柴油污染土壤的修复效率,分析了柴油中不同组分的降解特征,通过残留初始总石油烃(TPH)有效性和浸提液生物毒性变化提示不同处理的环境风险,通过有机碳和傅里叶变换红外光谱(FTIR)分析修复前后土壤特性变化。结果表明,SPC单独处理效率较低,CA/Fe(Ⅱ)显著提高了TPH去除率。FTIR光谱表明,处理后土壤样品的Si-O-Si、C-H和-OH振动增强。气相色谱-质谱联用(GC/MS)图谱表明,残留TPH组分主要为长链烷烃(C_(16)~C_(21))。羟丙基-β-环糊精(HPCD)浸提液发光抑制率随着浸提液pH的增加而增加,表明SPC投加量过多产生的强碱性对土壤生物毒性具有显著影响。增加CA投加量对TPH去除率的促进幅度大于SPC和FeSO_(4),且有助于降低残留TPH的生物有效性和提升土壤总有机碳(TOC)含量。采用化学氧化修复有机污染土壤应进行环境风险分析并对修复条件进行优化。

Chemical oxidation can rapidly and efficiently repair oil contaminated soil,but little attention has been paid to its impact on soil quality and environmental risk of residual pollutants.In this study,sodium percarbonate(SPC)was used as oxidant and citric acid(CA)/ferrous sulfate[Fe(Ⅱ)]as catalyst.The remediation efficiency of activated sodium percarbonate for diesel contaminated soil and the degradation characteristics of different components in diesel were analyzed.The changes of pH availability and biotoxicity of extracts indicated the environmental risk of different treatments.The changes of soil characteristics before and after remediation were analyzed by organic carbon and FTIR.The results showed that the efficiency of SPC alone was low,and CA/Fe(Ⅱ)significantly increased the removal rate of TPH.FTIR spectra indicated that the vibration of Si-O-Si,C-H and-OH increased after treatment.GC/MS analysis exhibited that the main component of TPH was long chain alkanes(C_(16)-C_(21)).The inhibition rate of luminescent bacteria in extract of hydroxypropyl-β-cyclodextrin(HPCD)increased with the increase of pH,indicating that the strong alkalinity produced by excessive SPC dosage had a significant effect on soil biotoxicity.The increase of CA dosage can promote the removal rate of TPH more than SPC and FeSO_(4),and help to reduce the bioavailability of residual TPH and improve the content of TOC in soil.Environmental risk analysis and optimization of remediation conditions should be carried out for remediation of organic contaminated soil by chemical oxidation.