土壤砷污染及其修复技术的研究进展

土壤砷污染已成为严重的环境和公共健康问题,日益受到人们的密切关注。综述了土壤砷污染的现状、来源及其危害,同时探讨了土壤砷污染的物理化学修复和生物修复（特别是植物修复）技术的研究现状;并对今后砷污染修复研究方向进行了展望。     

超稳矿化材料（LDHs）对镉污染红壤性水稻土的修复效果

耕地土壤重金属污染已成为制约绿色农业健康发展的突出短板之一。超稳矿化材料（LDHs）是一种新型的层状复合金属氢氧化物,因其具有分层结构、高比表面积和可交换的层间阴离子而在土壤修复领域表现出高效、稳定的特点。探究LDHs对土壤-作物系统重金属Cd的影响,可以为Cd污染耕地安全利用提供科学依据。以Cd污染红壤性水稻土为研究对象,采用室内苋菜盆栽实验方法,设置了0、2 g·kg⁻¹ 、5 g·kg⁻¹ 、10 g·kg⁻¹ 和20 g·kg⁻¹ 5个不同LDHs用量处理,研究了LDHs用量对土壤pH、土壤有效态Cd含量及苋菜中Cd含量的影响。结果表明：与CK相比,施用LDHs后pH值显著提高0.85 ~ 3.54个单位（P<0.05）,且随施用量的增加而增大;土壤有效态Cd含量随施用量的增加显著降低了58.5% ~ 99.6%（P<0.05）。当施用量为2 g·kg⁻¹时,苋菜地上部分Cd含量与CK差异不显著;施用量≥5 g·kg⁻¹时,苋菜地上部分Cd含量随施用量增加而降低,降幅为52.5% ~ 87.8%（P<0.05）;苋菜地下部分Cd含量随施用量的增加而呈下降趋势,且较CK显著降低45.3% ~ 85.5%（P<0.05）。苋菜富集系数与上述变化规律一致。土壤pH与土壤有效态Cd含量、BCF_shoot-soil、BCF_root-soil均呈显著负相关关系;土壤有效态Cd含量与BCF_root-soil呈极显著正相关关系,与BCF_shoot-soil呈正相关关系。LDHs能显著提高土壤pH,降低土壤Cd活性,从而减少Cd在植物体内的转运和富集,对Cd在土壤-作物系统中具有良好的阻控作用,可有效应用于Cd污染农田的钝化修复。结合生产成本与修复效果综合考虑,LDHs施用量以10 g·kg⁻¹为宜。     

农田土壤重金属污染的农业生态修复技术

总结了常见的农田土壤重金属污染的农业生态修复技术,包括合理施用化肥、施用生物有机肥、秸秆还田、调整作物种植结构、筛选重金属低积累作物品种和耐性作物品种、深耕深翻、控制土壤水分以及施用石灰等修复措施,并对农田土壤重金属污染修复技术的前景进行了展望。     

不同改良剂施用对污染土壤养分转化及砷和铅生物有效性的影响

为比较不同小龙虾壳基土壤改良剂对砷、铅复合污染土壤的修复效果,通过盆栽试验,探究施用1％(w/w)小龙虾壳粉(CSP)、甲壳素(CT)、小龙虾壳炭(CSB)及甲壳素-小龙虾壳炭配施(CT-CSB,CT∶CSB为1∶1)对土壤养分、酶活性、重金属生物有效性及青菜生长的影响.结果 表明,不同改良剂施用均可显著提高土壤pH和...     

草坪缓冲带限制斜坡上葡萄园敌草隆向地表水和地下水迁移效果的研究

Trichloroethylene (TCE), as one of the most common chlorinated organic compounds in soils and aquifers at many industrial sites, is carcinogenic and often recalcitrant in environment. TCE degradation in artificially contaminated soil samples was conducted using Fenton-like processes, i.e., by addition of excess hydrogen peroxide (H2O2 ). H 2 O 2 could directly oxidize TCE without addition of ferrous iron in contaminated soil. Under the optimal condition (H2O2 concentration of 300 mg kg 1 , pH at 5.0, and reaction time of 30 min), the removal efficiency of TCE in the soil was up to 92.3%. When the initial TCE concentration increased from 30 to 480 mg kg 1 in soil, the TCE removal rates varied from 89.2% to 86.6%; while the residual TCE in soil ranged from 2.28 to 47.57 mg kg 1 . Results from successive oxidations showed that the TCE removal rate with the TCE concentration of 180 mg kg 1 increased slightly from 91.6% to 96.2% as the number of successive oxidation cycle increased from one to four. Therefore, increasing the frequency of H2O2 oxidation was perhaps a feasible way to increase TCE removal rate for TCE-contaminated soil.     

单次有机肥或石灰施用阻控镉污染酸紫泥田早晚稻镉累积的效应

为明确中度Cd污染的酸紫泥田单次施常规用量有机肥、石灰对早晚稻稻米降Cd的作用效果及其调控因素,设置早稻季单次施用生石灰或鸡粪发酵的商品有机肥处理,连续两季监测水稻不同部位Cd、土壤二乙烯三胺五乙酸提取态Cd（DTPA−Cd）含量及土壤理化性质,研究了单次施有机肥、石灰的稻米降Cd效果、持续性及其影响因素。与对照相比,单次施有机肥、石灰处理,分别使早、晚稻糙米Cd含量显著降低44.4%、11.8%和72.6%、34.7%（P<0.05）,降幅呈逐季衰减趋势。单次施有机肥、石灰分别使早稻分蘖期土壤pH值提高了0.40和0.48个单位,土壤DTPA−Cd含量降低了13.6%和8.26%（P<0.05）;但是,随着双季稻周年生长时间的延长,土壤pH值和DTPA−Cd含量逐渐恢复至接近对照田块的水平。此外,单次施有机肥、石灰显著降低了早晚稻茎叶Cd富集系数、早稻糙米Cd富集系数及Cd由稻根向糙米的转运系数,显著提高了土壤酸碱缓冲容量、碱解氮、有效磷含量和电导率。单次施石灰或有机肥改善酸紫泥田酸化状况,提高了土壤肥力质量,降低了土壤Cd有效性和水稻植株对Cd的富集转运,但随双季稻周年生长时间的延长,效果逐渐减弱。实际应用中,应注重有机肥、石灰的连续施用和及时补施,实现土壤Cd持续钝化和肥力提升,降低稻米Cd累积。     

Application of the membrane interphase probe (MIP): an evaluation

Background, aim, and scope

The membrane interphase probe (MIP?) from Geoprobe Systems® has frequently been applied in different countries for the characterization of soil contaminated with volatile organic carbons (VOCs). Experience shows that misinterpretation of the collected data is common. This is mainly due to the lack of understanding and knowledge related to the detectors used, their detection limits, and the sensitivity of the MIP system. It has been noticed that the sensitivity of the system given by the producer and by different users are rather optimistic, e.g., the values given are lower (= better) than those actually experienced in the field. A need for a better understanding of the MIP system sensitivity, combined with a more scientifically based interpretation of the collected data, exists.

Materials and method

Both laboratory tests (using solutions) as well as field measurements were carried out using different detector configurations to allow a better interpretation of the detector signals/system sensitivity and to collect qualitative information. These configurations were: (1) detectors stand alone; (2) the use of a 2-ml sample loop, and (3) a purge and trap system. The configurations (2) and (3) are used in combination with a capillary column to carry out on-site qualitative and semiquantitative analyses.

Results and discussion

With respect to the configuration of “detectors stand alone,” detection limits for toluene (in aqueous solutions) range between 4 ppm (flame ionization detector—FID) and 10 ppm [photo ionization detector (PID)]. For chlorinated aliphatic hydrocarbons (CAHs), observed limits are 10 ppm (FID), 4–50 ppm (PID), and 3–10 ppm [dry electrolytic conductivity detector (DELCD)]. When using the 2-ml sample loop, relatively high concentrations have to be initially present in the soil. Observed detection limits for mono-aromatic hydrocarbons are 5–100 ppm; for CAHs, 1–50 ppm; for alkanes, 250–400 ppm; and for MTBE, 25 ppm. The application of purge and trap results in a better resolution and the detection of lower concentrations. Consequently, a better identification of the pollution with depth is possible. In this case, the detection limits are a function of the concentrations and the flushing time. In relation to the qualitative analyses, it was found that the configuration of the MIP-system with the built-in capillary column and the 2-ml sample loop or the purge and trap preconcentrator, respectively, are useful to carry out on-site analyses, thus allowing a better identification of the pollution in a vertical profile.

Conclusions

The measurements carried out using the MIP with detectors stand-alone or in combination with a loop or trap, or connected to a column, confirm that analysis is indeed very useful to characterize VOC source zones when knowing and understanding its performance. This relates mainly to the detection limits of the MIP system. For a selection of parameters, such limits have been obtained. These values seem to be more realistic than those found in the few references where numbers are given. For the qualitative measurements, it can be concluded that a better resolution is obtained, and pollutants present in lower concentrations will be detected when using the purge and trap. It is advised to determine the optimal flushing time and the detection limit of the expected pollutants in advance.

Recommendations and perspectives

This study indicates that there is still a need for further measurements and discussion between users. Finally, additional data should result in a better interpretation of the collected field data.     

手持式X射线荧光光谱快速测定仪的实践应用评价及建议

手持式X射线荧光光谱仪(XRF)作为快速筛选重金属污染的手段在污染地块调查中广泛使用,但目前国内对XRF现场检测结果指导实验室筛选检测样品的可靠性研究缺乏。本文选择两个实际污染地块调查中的Cu、Pb、As、Ni、Cd和Hg6种重金属的XRF现场检测数据和实验室实测数据,采用一元线性拟合、Pearson相关、差异分析等手段对两种测试结果的一致性进行研究。结果表明,土壤中Cu、Pb、As和Ni4种金属的XRF测定值和实验室实测值具有显著相关性。Hg和Cd的XRF测定值显著高于实验室实测值,Cu、Pb、As和Ni XRF测定值较实验室实测值偏小的样品占比超过50%。6种重金属中Cu和Pb XRF测定值和实验室实测值的相关性及一元线性拟合结果更好(相关系数0.5～0.8,R~2>0.7)。Cu在XRF测定值大于1 000 mg/kg时与实验室实测值的拟合结果更好(R~2>0.7),As和Pb分别为XRF测定值在4.0～10 mg/kg和检出限～80 mg/kg范围时更好(R~2>0.8)。采用重金属筛选值的50%作为筛选实验室样品的标准时,XRF结果预测Cu、Pb和As超标样...     

有机化工污染场地修复后的再利用风险评价

为检验污染土壤修复工程的效果,判断修复土地再利用的生态与环境风险,用人体健康风险评价法,依据土壤污染物进入人体的主要途径及可测量的参数,通过评估一块被有机物污染的场地修复前后的风险,度量了不同土地利用方式下多种土壤污染物经各种途径进入并危害人体健康的风险值及总风险。结果表明,不同土地利用方式下,苯、硝基苯、苯胺的总非致癌风险分别由修复工程实施前的4.42～46.10降低到修复后的2.50×10-3～2.61×10-2,总致癌风险则分别由3.06×10-6～7.41×10-6降低到4.75×10-7～1.19×10-6,修复后的土地适宜作为商业服务或工业用地。     

Land contaminated by radioactive materials

Abstract. Nuclear weapons' testing, mineral extraction industries and nuclear power generation are among the activities which have led to radioactively contaminated land. In the United Kingdom (UK), current activities such as the decommissioning of nuclear licensed sites and the sale of Ministry of Defence land require that the legislation, remediation and management of radioactively contaminated land be addressed. With an emphasis on the UK, this paper reviews potential management/remediation strategies for radioactively contaminated land, including consideration of the environmental mobility of potentially important radionuclides.     

堆肥缓解土壤镉的植物毒性: 对白菜生长的影响

The growth performance of pakchoi (Brassica chinensis L.) in relation to soil cadmium (Cd) fractionations was investigated to evaluate the remediating effect of poultry manure compost on Cd-contaminated soil. A yellow-brown soil (Alfisol) treated with various levels of Cd (0–50 mg Cd kg-1 soil) was amended with increasing amounts of compost from 0 to 120 g kg-1 . Compost application transformed 47.8%–69.8% of soluble/exchangeable Cd to the organic-bound fraction, and consequently decreased Cd uptake of pakchoi by 56.2%–62.5% as compared with unamended soil. Alleviation of Cd bioavailability by compost was attributed primarily to the increase of soil pH and complexation of Cd by organic matter including dissolved organic matter. In general, the improvement of pakchoi performance was more pronounced in higher Cd-contaminated soil. Addition of large amount of compost also favored the anti-oxidative capability of pakchoi against Cd toxicity. This low cost remediation method seems to be very effective in the restoration of Cd-contaminated soils.     

棉花、花生秸秆生物炭对棕壤中Cu(Ⅱ)运移的影响

[目的]分析棉花、花生生物炭基本理化性质,模拟自然条件下降雨对土壤中Cu(Ⅱ)淋失量的影响,探讨生物炭修复Cu(Ⅱ)污染棕壤的可行性。[方法]以棉花、花生秸秆为原料,采用限氧热解法分别在350,500,650℃下制备生物炭,将生物炭按1%的炭土干重比施入铜污染棕壤[Cu(Ⅱ)的浓度200mg/kg],通过室内土柱淋溶试验分析添加不同生物炭对土壤缓冲性能和吸附能力的影响。[结果]两类生物炭的H/C及O/C的比值随着温度的升高逐渐降低,而生物炭的BET比表面积则随着制备温度的升高而逐渐增大;添加生物炭的土壤淋溶液pH值显著高于空白处理,花生生物炭的效果更为显著;随着淋溶次数的增加,添加生物炭的土壤中Cu(Ⅱ)的淋失量明显低于空白处理;添加花生生物炭提高了土壤中Cu(Ⅱ)的专性吸附,以650℃最为显著。[结论]两种生物炭能明显提高土壤的缓冲性能和对重金属的吸持能力,其中以花生生物炭的效果更为明显。     

生物泥浆反应器在污染土壤修复中的应用

近年来生物修复技术因具有处理费用低、不产生二次污染且处理效果可靠有效的特点被认为是最具生命力的一种土壤处理手段.总结了生物泥浆反应器这种高效生物修复技术的原理,工艺流程、运行方式、应用范围和运行费用,并重点介绍了其强化手段.已有的土壤生物修复技术受环境条件限制较大,很难在短时间内达到修复目的,生物泥浆反应器作为一种高效的土壤生物修复技术在高浓度、难降解有机物污染土壤的快速修复处理中具有良好的研究开发价值和广阔的应用前景.     

生物质炭对土壤-水稻系统中Cd迁移累积的影响

探究生物质炭添加对Cd污染土壤中Cd形态、植株对Cd的吸收分配及土壤肥力的影响,为污染稻田粮食安全提供科学依据。在湖南省长沙市Cd污染稻田进行田间定位试验,设置5个生物质炭添加量处理(0,10,20,30,40t/hm^2),分析生物质炭对Cd在土壤中形态转化和水稻器官中分配的影响。结果表明:生物质炭通过将土壤中酸溶态Cd钝化为可还原态Cd以减少在水稻器官中的累积,钝化量随着生物质炭增加而增加,土壤酸溶态Cd较CK降低3.83%～19.08%;且茎对根和糙米对茎的转运系数随生物质炭的添加分别降低4.23%～9.30%和1.39%～8.33%;土壤酸溶态Cd含量直接影响糙米中Cd含量,且受土壤pH和土壤有机碳的调控。Cd污染稻田添加生物质炭可以提高土壤肥力,降低土壤Cd生物有效性,20t/hm^2生物质炭添加量可以作为研究区周边Cd污染稻田修复的参考标准。     

通风方式对柴油污染土壤生物通风修复效果的影响研究

生物通风法被广泛应用于不饱和土壤中挥发性有机物的去除,具有高效、费用低等优点。以黄壤为实验土样,柴油为污染物,采用室内一维土柱实验模拟生物通风过程,研究了抽提和注入两种通风方式下柴油的去除效果及规律。结果表明,两种通风方式的去除规律大致相同,抽提方式的去除速度要比注入快,但最终去除率仅比注入高2.28%;每日通风前后及通风过程中测定的土柱总出气口中总挥发性有机化合物(TVOC)值的变化规律也基本相同,只是通风后TVOC值相对较高;在一天8h的通风过程中,每隔1,2,3h测定的TVOC值波动变化的程度为TVOC1h > TVOC2h > TVOC3h;土壤中有效磷和速效氮的含量与柴油生物降解效率密切相关。