磷对铅、锌和镉在土壤固相-液相-植物系统中迁移转化的影响

在盆栽条件下,以磷酸二氢钾作为磷（P）添加剂,以空心菜为指示植物,借助模型Visual MINTEQ 研究了P对污染土壤中铅（Pb）、锌（Zn）和镉（Cd）在土壤固相-液相之间以及土壤-根系-地上部的迁移累积的影响.实验设了6个P剂量水平：0（CK）、 0.18（P0.18）、 0.36 （P0.36）、 0.72（P0.72）、 1.08（P1.08）、 1.44（P1.44）,P剂量水平是按照P/Pb物质量的比例（mol/mol）为基础而设计的.结果表明,与对照相比,添加P处理污染土壤后,显著（p<0.05）降低了空心菜地上部吸收的重金属Pb、Zn和Cd的含量,降低幅度分别为53％～92％、 35％～71％和59％～86％,降低了根系吸收累积重金属Pb的含量,增加了根系吸收的Zn的含量,但对Cd吸收量无显著影响.增加P的剂量水平,根系向地上部转运的Pb、Zn和Cd的量的呈指数级下降趋势.地上部吸收的各元素的相关分析结果表明,元素Pb 与元素Zn、Cd是显著正相关关系,其中相关系数最高的是Pb 与Zn（R＝0.993,p<0.01）,其次是Pb与Cd（R＝0.986,p<0.01）.说明Pb 与Zn、Cd在空心菜从根系到地上部分转运的过程中是协作关系.添加P后,提高了土壤pH,从而降低了土壤水溶性Cd的含量,Zn变化不显著,增加了土壤水溶性总Pb含量.平衡液中Pb的主要存在形态是PbHPO₄、PbOH⁺、PbH₂PO⁺₄等3种络合形态.结果还表明,根系吸收Pb的量与土壤水溶性Pb含量具有显著的负相关关系,相关系数-0.872（p<0.05）.P处理降低了土壤水溶性Zn、Cd的含量,却促进了根系吸收,这是Zn、Cd与Pb的不同之处.P具有显著降低复合污染土壤中Pb、Zn和Cd植物毒性的作用.     

3种表面活性剂对有机氯农药污染场地土壤的增效洗脱修复效应

以有机氯农药生产企业工业场地污染土壤为对象,研究Tween80、TritonX-100和SDS这3种表面活性剂对土壤中氯丹(α-氯丹和γ-氯丹)、灭蚁灵、七氯、硫丹(α-硫丹和β-硫丹)的增溶洗脱效应.结果表明,3种表面活性剂对土壤中的有机氯农药均具有一定的增效洗脱作用,且洗脱去除率随表面活性剂添加量升高而逐渐增加.3种表面活性剂对土壤中氯丹、硫丹和七氯的去除率明显高于灭蚁灵,TritonX-100对灭蚁灵的去除率明显高于SDS和Tween80.Tween80和TritonX-100添加量为10g·L-1、SDS添加量为8.50g·L-1时,对土壤中4类有机氯农药的总去除率最高,分别为32.8％、59.7％和60.1％.对于该类污染场地土壤,选择10g·L-1 TritonX-100溶液在50℃条件下振荡5min时洗脱效果最好.     

铬(Ⅵ)污染高岭土电动修复实验研究

用电动方法对铬(Ⅵ)污染高岭土的修复进行了实验室研究。选用重铬酸钾作为污染物,配制的高岭土的重铬酸钾质量分数为100mg·kg-1。实验研究了铬(Ⅵ)污染高岭土电动修复的可行性,施加电压和处理时间对去除效率的影响,阴极电解产生的OH-对去除效率的影响及其控制方法,以及铬的迁移和分布规律。实验结果表明,电动修复可以有效去除高岭土中存在的铬(Ⅵ),最高去除效率可达97.8%;高岭中六价铬[Cr(Ⅵ)]以含氧阴离子形式存在,在电动修复过程中向阳极区域迁移;用蒸馏水冲洗和醋酸中和阴极电解产生的OH-,可以提高铬的去除效率。     

Role of Acinetobacter sp. in arsenite As(III) oxidation and reducing its mobility in soil

Microbial arsenite oxidation was observed by Acinetobacter sp. XS21, this strain oxidised arsenite As(III) up to 80?mM within 48–72?h of incubation. The present strain XS21 oxidised As(III) at a very high concentration in a shorter interval of time than any of the previous reported microbes. Further, XS21 was applied to the soil to observe its ability in reducing the mobility of As(III), and we found that Acinetobacter sp. XS21 efficiently removed arsenite from soluble-exchangeable fraction and removed 70% of the arsenite as compared to control. This feature makes it a potential candidate for bioremediation. Arsenic-resistant bacteria with strong As(III)-oxidising ability may have potential to improve bioremediation of As(III)-contaminated sites. To understand their basis of resistance and transformation we found the As(III) oxidase gene using degenerate primer and amplified ～550?bp of aioA gene. Amplified aioA gene sequence exhibiting 52% identity in terms of gene and deduced protein sequence to Uncultured bacterium, and Achromobacter sp. arsenite oxidase of larger subunit. Arsenite oxidase, an enzyme, was also observed in this isolate, which may provide a resistance and transforming ability. This bacterium was identified as Acinetobacter sp., by sequencing 16s rRNA gene sequence analysis.     

棉秆炭对镉污染土壤的修复效果

采用盆栽方法,研究了棉秆炭对镉污染土壤的修复效果及对镉污染土壤上小白菜(Brassica chinensis)镉吸收的影响.结果表明:以微孔为主的棉秆炭能够通过吸附或共沉淀作用降低土壤中镉的生物有效性.在轻度镉污染时,棉秆炭处理土壤对镉的吸附速率较快,随着镉污染程度的增加.吸附速率逐渐减慢,吸附量逐渐增加.棉秆炭能够明显降低镉污染土壤上小白菜可食部和根部的镉积累量,可食部镉质量分数降低49.43%～68.29%,根部降低64.14%～77.66%,说明棉秆炭具有修复土壤镉污染,降低蔬菜镉含量的作用,可提高蔬菜品质.     

电动脱除孔隙水削减底泥内源磷的效果研究

选择污染严重的底泥为研究对象,采用基于孔隙水脱除的电动修复装置,进行了底泥脱水排磷实验,探究了电动脱除孔隙水的底泥减磷效果,分析了底泥各形态磷在电动脱除孔隙水中的迁移转化过程.结果表明：电动脱水过程中阴极总脱水量为5740mL,远大于阳极（2121mL）,但脱水中总磷浓度为阳极大于阴极,80%以上的磷从阳极排出,电迁移在电动脱水排磷中起主要作用,通电使排磷总量增加了70%以上,其中在0.25V/cm的电压梯度下修复18d的条件下,排磷量最大;电动脱水排磷效率在通电48h内达到最高[0.73mg/（kW·h）],随后急剧减小;经过电动脱水排磷后,底泥含水率下降了14.07%,底泥总磷降幅最高可达231.92mg/kg,底泥中交换态磷（Ex-P）、铁结合态磷（Fe-P）、闭蓄态磷（Oc-P）、钙结合态磷（Ca-P）平均脱除率分别为80.01%、14.75%、40.65%和19.22%,其中阳极酸化导致氧化铁的溶解和Ca-P的释放,故阳极附近Oc-P、Ca-P降幅较大,而阴极碱化使Fe-P释放,故阴极附近Fe-P降幅较大.经计算可知,通过电动脱除孔隙水,底泥中生物可利用性磷（Ex-P+Fe/Al-P）平均下降了14.12%,底泥内源磷释放的风险得以降低.     

重金属钝化剂阻控生菜Cd吸收的功能稳定性和适用性

利用重金属钝化剂阻控蔬菜吸收重金属是治理中轻度重金属污染菜地和保障蔬菜安全生产的重要举措.以重金属固定细菌Bacillus megaterium N3（N3）、稻壳生物炭（BC）、羊粪有机肥（SM）、菌株N3联合生物炭（BC+N3）和菌株N3联合羊粪有机肥（SM+N3）为重金属钝化剂,采用盆栽试验连续种植生菜3次,而只在种植第1次时施重金属钝化剂,研究不同处理对生菜吸收Cd的影响及其功能的稳定性,并利用动态加权综合函数评估这几种钝化材料的综合适用性.结果表明,第1次种植生菜时,与对照相比,所有重金属钝化剂均能显著降低（61.2%~81%）生菜可食用部分Cd的含量.而在第3次种植生菜中,只有菌株N3联合羊粪有机肥的处理能显著降低生菜对Cd的吸收,这表明菌株N3联合羊粪有机肥阻控生菜Cd吸收的功能稳定性最好.利用动态加权综合函数,从新鲜生菜可食用部分Cd含量、土壤有效态Cd含量、每亩产量和每亩修复成本等4个方面进行综合评价.结果显示,菌株N3联合羊粪有机肥的综合适用性最好,其次是羊粪有机肥、菌株N3联合生物炭和生物炭,而菌株N3的综合评价效果最差.本研究结果为重金属污染菜地钝化修复提供理论依据和技术支撑.     

Investigation and risk assessment modeling of As and other heavy metals contamination around five abandoned metal mines in Korea

Tailings, agricultural soils, vegetables and groundwater samples were collected from abandoned metal mines (Duckum, Dongil, Dongjung, Myoungbong and Songchun mines) in Korea. Total concentrations of arsenic (As) and heavy metals (Cd, Cu, Pb and Zn) were analyzed to investigate the contamination level. Several digestion methods (Toxicity characteristics leaching procedure (TCLP), synthetic precipitation leaching procedure (SPLP), 0.1 N/1 N HCl) and sequential extraction analysis for mine tailings were conducted to examine the potential leachability of As and heavy metals from the tailings. The order of urgent remediation for the studied mines based on the risk assessment and remedial goals was suggested. The Songchun mine tailings were most severely contaminated by As and heavy metals. Total concentrations of As and Pb in the tailings were 38,600–58,700 mg/kg (av. 47,400 mg/kg) and 11,800–16,800 mg/kg (av. 14,600 mg/kg), respectively. Agricultural soils having high As concentrations were found at the all mines. Average concentrations of Cd in the vegetables exceeded the normal value at all mines areas, while As only at the Dongjung, Myoungbong, and Songchun mine area. One groundwater sample each from the Dongil and Myoungbong mines, and 4 groundwater samples from the Songchun mine had values above 10 μg/L of As concentration. The TCLP method revealed that only Pb in the Songchun tailings, 6.49 mg/L, exceeded the regulatory level (5 mg/L). Employing the 1-N HCl digestion method, the concentration of As in the Songchun mine tailings, 4,250 mg/kg, was up to 3,000 times higher than its Korean countermeasure standard. Results from the sequential extraction of As in the tailings showed that the easily releasable fraction in the Myoungbong and Songchun mine tailings was more than 30% and the residual fraction was less than 40%. Based on results showing the exposure health risk employing the hazard quotient and cancer risk of As, Cd and Zn, the Dongil mine needs the most urgent remedial action. The concentration reduction factor (CRF) of As in both soil and groundwater follows the order: Songchun>Dongjung>Dongil>Myoungbong>Duckum mine.     

典型禾本科植物对石油污染土壤的修复作用

石油类污染物对土壤生态系统的结构与功能造成了较为严重的破坏,影响植物的生长,甚至直接影响到人类健康。选择典型禾本科植物-高粱和玉米,通过盆栽实验,种植于模拟石油污染的土壤中,植物成熟收割后,通过测定土壤中总石油烃的含量,植物体中多环芳烃和直链烷烃的含量,研究高粱和玉米对石油污染土壤的修复作用。结果显示:在种植高粱、玉米后,土壤中总石油烃含量明显降低,并且在收获的高粱、玉米植物体中直链烷烃和多环芳烃含量明显高于空白对照组(未检出)。说明高粱、玉米对石油烃具有一定的去除作用,且高粱对土壤中石油烃的去除作用高于玉米;高粱、玉米对土壤中的多环芳烃和直链烷烃具有一定的积累与富集作用。     

应用地球化学工程学修复水、气、土壤污染的研究进展

本文简要介绍了地球化学工程学的基本概念、主要环境技术及尺度 ,综述了地球化学工程学在水、大气、土壤污染修复中的研究进展。