Mechanical soil aeration is a simple, effective, and low-cost soil remediation technology that is suitable for sites contaminated with volatile chlorinated hydrocarbons（VCHs）. Conventionally, this technique is used ...Mechanical soil aeration is a simple, effective, and low-cost soil remediation technology that is suitable for sites contaminated with volatile chlorinated hydrocarbons（VCHs）. Conventionally, this technique is used to treat the mixed soil of a site without considering the diversity and treatability of different soils within the site. A laboratory test was conducted to evaluate the effectiveness of mechanical soil aeration for remediating soils of different textures（silty,clayey, and sandy soils） along a vertical profile at an abandoned chloro-alkali chemical site in China. The collected soils were artificially contaminated with chloroform（TCM） and trichloroethylene（TCE）. Mechanical soil aeration was effective for remediating VCHs（removal efficiency 〉 98%）. The volatilization process was described by an exponential kinetic function.In the early stage of treatment（0–7 hr）, rapid contaminant volatilization followed a pseudofirst order kinetic model. VCH concentrations decreased to low levels and showed a tailing phenomenon with very slow contaminant release after 8 hr. Compared with silty and sandy soils, clayey soil has high organic-matter content, a large specific surface area, a high clay fraction, and a complex pore structure. These characteristics substantially influenced the removal process, making it less efficient, more time consuming, and consequently more expensive. Our findings provide a potential basis for optimizing soil remediation strategy in a cost-effective manner.展开更多
Air samples were collected simultaneously at platform,mezzanine and outdoor in five typical stations of subway system in Shanghai,China using stainless steel canisters and analyzed by gas chromatography-mass selective...Air samples were collected simultaneously at platform,mezzanine and outdoor in five typical stations of subway system in Shanghai,China using stainless steel canisters and analyzed by gas chromatography-mass selective detector （GC-MSD） after cryogenic pre-concentration.Benzene,toluene,ethylbenzene and xylenes （BTEX） at the platforms and mezzanines inside the stations averaged （10.3±2.1）,（38.7±9.0）,（19.4±10.1） and （30.0±11.1） μg/m 3,respectively;while trichloroethylene （TrCE）,tetrachloroethylene （TeCE） and para-dichlorobenzene （pDCB）,vinyl chloride and carbon tetrachloride were the most abundant chlorinated hydrocarbons inside the stations with average levels of （3.6±1.3）,（1.3±0.5）,（4.1±1.1）,（2.2±1.1） and （1.2±0.3） μg/m 3,respectively.Mean levels of major aromatic and chlorinated hydrocarbons were higher indoor （platforms and mezzanines） than outdoor with average indoor/outdoor （I/O） ratios of 1.1–9.5,whereas no significant indoor/outdoor differences were found except for benzene and TrCE.The highly significant mutual correlations （p0.01） for BTEX between indoor and outdoor and their significant correlation （p0.05） with methyl tert-butyl ether （MTBE）,a marker of traffic-related emission without other indoor and outdoor sources,indicated that BTEX were introduced into the subway stations from indoor/outdoor air exchange and traffic emission should be their dominant source.TrCE and pDCB were mainly from indoor emission and TeCE might have both indoor emission sources and contribution from outdoor air,especially in the mezzanines.展开更多
以联苯-联苯醚混合物为萃取剂,建立了分散液液微萃取-气相色谱电子捕获检测器测定饮用水中7种挥发性卤代烃的方法。此萃取剂为无卤素萃取剂,密度大于水,可通过离心分离,萃取过程可在3 min内完成。对萃取剂用量、分散剂种类及用量、萃取...以联苯-联苯醚混合物为萃取剂,建立了分散液液微萃取-气相色谱电子捕获检测器测定饮用水中7种挥发性卤代烃的方法。此萃取剂为无卤素萃取剂,密度大于水,可通过离心分离,萃取过程可在3 min内完成。对萃取剂用量、分散剂种类及用量、萃取时间、萃取温度等条件进行了优化。5.00 m L水样用200μL萃取剂和0.30 m L分散剂(甲醇)的混合物进行萃取,室温下萃取30 s,7种挥发性卤代烃的萃取率≥90%,富集倍率为22.5~24.7。萃取液经DB-624毛细管柱分离,用电子捕获检测器定量检测,检出限为0.003~0.032μg/L。检测三氯甲烷的线性范围为0.500~100.0μg/L,三氯乙烯和三溴甲烷的线性范围为0.100~20.0μg/L,四氯化碳、四氯乙烯、二氯一溴甲烷、一氯二溴甲烷的线性范围为0.050~10.0μg/L。在上述线性范围内,工作曲线的相关系数≥0.998。方法的相对标准偏差在2.1%~7.6%之间,加标回收率在93.0%~102.9%之间。展开更多
基金supported by the National Environmental Protection Public Welfare projects(Nos.201409047 and 201109017)the “13th Five-Year Plan” National Key Research and Development Program of China(No.2016YFC0501108)+1 种基金the Fundamental Research Funds for the Central Universities(No.2016QH02)Beijing Natural Science Foundation(No.8152025)
文摘Mechanical soil aeration is a simple, effective, and low-cost soil remediation technology that is suitable for sites contaminated with volatile chlorinated hydrocarbons（VCHs）. Conventionally, this technique is used to treat the mixed soil of a site without considering the diversity and treatability of different soils within the site. A laboratory test was conducted to evaluate the effectiveness of mechanical soil aeration for remediating soils of different textures（silty,clayey, and sandy soils） along a vertical profile at an abandoned chloro-alkali chemical site in China. The collected soils were artificially contaminated with chloroform（TCM） and trichloroethylene（TCE）. Mechanical soil aeration was effective for remediating VCHs（removal efficiency 〉 98%）. The volatilization process was described by an exponential kinetic function.In the early stage of treatment（0–7 hr）, rapid contaminant volatilization followed a pseudofirst order kinetic model. VCH concentrations decreased to low levels and showed a tailing phenomenon with very slow contaminant release after 8 hr. Compared with silty and sandy soils, clayey soil has high organic-matter content, a large specific surface area, a high clay fraction, and a complex pore structure. These characteristics substantially influenced the removal process, making it less efficient, more time consuming, and consequently more expensive. Our findings provide a potential basis for optimizing soil remediation strategy in a cost-effective manner.
基金supported by the National Natural Science Foundation of China (No. 40821003)the Guangdong Natural Science Foundation (No. 7118013)the State Key Laboratory of Organic Geochemistry and the Hong Kong Polytechnic University Joint Student Program
文摘Air samples were collected simultaneously at platform,mezzanine and outdoor in five typical stations of subway system in Shanghai,China using stainless steel canisters and analyzed by gas chromatography-mass selective detector （GC-MSD） after cryogenic pre-concentration.Benzene,toluene,ethylbenzene and xylenes （BTEX） at the platforms and mezzanines inside the stations averaged （10.3±2.1）,（38.7±9.0）,（19.4±10.1） and （30.0±11.1） μg/m 3,respectively;while trichloroethylene （TrCE）,tetrachloroethylene （TeCE） and para-dichlorobenzene （pDCB）,vinyl chloride and carbon tetrachloride were the most abundant chlorinated hydrocarbons inside the stations with average levels of （3.6±1.3）,（1.3±0.5）,（4.1±1.1）,（2.2±1.1） and （1.2±0.3） μg/m 3,respectively.Mean levels of major aromatic and chlorinated hydrocarbons were higher indoor （platforms and mezzanines） than outdoor with average indoor/outdoor （I/O） ratios of 1.1–9.5,whereas no significant indoor/outdoor differences were found except for benzene and TrCE.The highly significant mutual correlations （p0.01） for BTEX between indoor and outdoor and their significant correlation （p0.05） with methyl tert-butyl ether （MTBE）,a marker of traffic-related emission without other indoor and outdoor sources,indicated that BTEX were introduced into the subway stations from indoor/outdoor air exchange and traffic emission should be their dominant source.TrCE and pDCB were mainly from indoor emission and TeCE might have both indoor emission sources and contribution from outdoor air,especially in the mezzanines.
文摘以联苯-联苯醚混合物为萃取剂,建立了分散液液微萃取-气相色谱电子捕获检测器测定饮用水中7种挥发性卤代烃的方法。此萃取剂为无卤素萃取剂,密度大于水,可通过离心分离,萃取过程可在3 min内完成。对萃取剂用量、分散剂种类及用量、萃取时间、萃取温度等条件进行了优化。5.00 m L水样用200μL萃取剂和0.30 m L分散剂(甲醇)的混合物进行萃取,室温下萃取30 s,7种挥发性卤代烃的萃取率≥90%,富集倍率为22.5~24.7。萃取液经DB-624毛细管柱分离,用电子捕获检测器定量检测,检出限为0.003~0.032μg/L。检测三氯甲烷的线性范围为0.500~100.0μg/L,三氯乙烯和三溴甲烷的线性范围为0.100~20.0μg/L,四氯化碳、四氯乙烯、二氯一溴甲烷、一氯二溴甲烷的线性范围为0.050~10.0μg/L。在上述线性范围内,工作曲线的相关系数≥0.998。方法的相对标准偏差在2.1%~7.6%之间,加标回收率在93.0%~102.9%之间。
