不同钝化剂和培养时间对Cd污染土壤中可交换态Cd的影响

原位化学钝化技术是修复重金属污染土壤的重要途径之一,通过施入一些钝化剂以降低土壤中重金属有效态含量,从而减少其迁移及对植物的毒害。选取羟基磷灰石（HA）、磷矿粉（PRX和PRH）、沸石、赤泥、新鲜植物残体、玉米秸秆粉末以及相应的处理共21种钝化剂,在同一培养条件和添加浓度下,比较其对人工Cd污染土壤中可交换态Cd含量的影响,并分析了其在不同培养时间对钝化效果的时间效应,试验的结果对于筛选Cd污染土壤钝化剂有着重要的意义。结果表明,纳米化赤泥、羟基磷灰石和纳米化酸洗赤泥可显著降低土壤中可交换态Cd含量,钝化比例高达35%-55%;赤泥、酸洗赤泥、沸石达15%-25%;富含巯基植物蒜苗、油菜、大葱植物残体也可达20%-25%。磷矿粉、大葱粉末、玉米秸秆和巯基化玉米秸秆的钝化效果相对较差;HA、铵型沸石、纳米赤泥、酸洗纳米赤泥、干油菜粉末、酸洗赤泥对可交换态Cd的钝化效果的时间效应不明显;赤泥、大葱残体、特别是玉米秸秆和巯基玉米秸秆随时间增长钝化效果增加显著,在8周和16周时段钝化效果较好。     

巯基膨润土钝化修复镉污染水稻土的研究

通过田间种植水稻试验,探究了巯基膨润土(Bent-SH)对镉污染土壤的修复效果及钝化机理.结果表明:添加Bent-SH对土壤理化性质的影响很小,土壤有效态镉含量随Bent-SH添加量的增加逐渐降低,与对照相比,其最大下降率为48.57％.添加Bent-SH降低了土壤镉的迁移能力,降低了大米、秸秆对土壤镉的吸收,其最大下...     

Remediation of Copper and Cadmium in Contaminated Soils using Compost with Inorganic Amendments

Water, Air, & Soil Pollution - Compost enriched with inorganic amendments has been evaluated in laboratory-based experiments for its effectiveness to immobilise heavy metals in contaminated...     

镉砷复合污染水稻土原位钝化修复技术研究进展

随着工农业的发展,稻田土壤正面临严重的重金属污染问题,水稻作为南亚和东南亚的主要粮食作物,稻米安全问题显得尤为突出。镉和砷两者在生物地球化学循环上有明显差异,因此镉和砷复合污染水稻土的修复一直是一个棘手的问题。综述了镉砷复合污染水稻土原位钝化技术的研究现状,将钝化技术梳理为氧化还原型、微生物转化累积型、材料型和耦合钝化技术四类。氧化还原型钝化技术重点指出稻田水分调控驱动的氧化还原电位Eh和pH变化、不同元素的生物地球化学循环、有机质等对镉和砷的迁移转化机制;微生物转化累积型钝化技术重点阐明功能微生物对砷和镉的吸收、转化、区室化、菌表吸附等作用机制;材料型钝化技术重点分析现有钝化材料的分类及其与镉和砷的固定化机制;耦合型钝化技术重点总结上述三种技术综合体系下,镉和砷的协同钝化应用。同时对未来镉砷复合污染水稻土的原位钝化修复提出展望,进一步探讨了镉砷在稻田土壤生物地球化学循环过程涉及的新型机制研究方向、修复钝化技术的创新延展趋势;期望在稳产、增产的基础上,寻求一种深度融合现代农业生产模式、保障稻田安全利用的土壤钝化改良技术体系或模式。     

Remediation of Lead Contaminated Soils by Stabilization/Solidification

Most available remediation technologies for treatment of heavymetal contaminated soils are very expensive and result in residues requiring further treatment. Stabilization/solidification (immobilization) techniques however, which aredesigned to decrease leaching potential of heavy metals from soil by addition of chemical additives, provide very cost-effective solutions for heavy metal contaminated soils. Thisstudy investigates the most efficient additive for immobilization of lead. To achieve this goal, several leachingexperiments were conducted for mixtures of different additives(lime, activated carbon, clay, zeolite, sand and cement) withartificially Pb contaminated (spiked) soil samples in accordancewith the Toxicity Characterization Leaching Procedure (TCLP) developed by U.S. EPA. Results showed that among the additivestried, activated carbon, clay, zeolite and sand are not very efficient for Pb immobilization. On the other hand, lime andcement are significantly effective in Pb immobilization with 88% efficiency at 1:21 lime:soil ratio and 99% efficiency at1:15 cement:soil ratio, respectively.     

Remediation of a Sandy Soil Contaminated with Cadmium,Nickel, and Zinc using an Insoluble Polyacrylate Polymer

Abstract

This study was carried out to investigate whether an insoluble polyacrylate polymer could be used to remediate a sandy soil contaminated with cadmium (Cd) (30 and 60 mg Cd kg^?1 of soil), nickel (Ni) (50 and 100 mg Ni kg^?1 of soil), zinc (Zn) (250 and 400 mg Zn kg^?1 of soil), or the three elements together (30 mg Cd, 50 mg Ni, and 250 mg Zn kg^?1 of soil). Growth of perennial ryegrass was stimulated in the polymer‐amended soil contaminated with the greatest amounts of Ni or Zn, and when the three metals were present, compared with the unamended soil with the same levels of contamination. Shoots of plants cultivated in the amended soil had concentrations of the metals that were 24–67% of those in plants from the unamended contaminated soil. After ryegrass had been growing for 87 days, the amounts of water‐extractable metals present in the amended soil varied from 8 to 53% of those in the unamended soil. The results are consistent with soil remediation being achieved through removal of the metals from soil solution.     

壳聚糖修复重金属污染土壤的研究进展

壳聚糖是一种来源广泛、具有良好的生物相容性、生物降解性的高分子材料,其含有大量氨基、羟基等活性基团,能与重金属离子进行螯合,发生吸附作用。壳聚糖还具有改良土壤、促进植物生长,诱导植物抗逆的作用,在重金属污染农田土壤修复中具有独特的应用优势。综述了近年来国内外有关壳聚糖修复重金属污染土壤的研究进展,探讨了壳聚糖对土壤重金属污染修复的潜力,阐述了壳聚糖在重金属原位钝化修复、土壤淋洗修复、强化植物提取修复三个方面的应用,并指出壳聚糖在重金属污染土壤修复中存在的问题以及对其在未来修复重金属污染土壤的发展进行了展望,以期为壳聚糖重金属修复技术的推广和应用提供参考。     

土壤重金属复合污染的化学固定修复研究

本文研究糠醛渣、磷矿粉、风化煤3 种修复剂对重金属复合污染土壤的化学固定修复效果.结果表明:糠醛渣、磷矿粉、风化煤3 种修复剂都可一定程度地降低复合污染土壤中的Cu、Zn、Pb、Cd含量,其中以风化煤降低土壤有效态Zn、Cu的效果较好,在风化煤添加量为80 g/kg时土壤有效态Zn的含量降低了37.22%,土壤有效态Cu的含量降低了31.22%;磷矿粉处理修复Pb的效果比糠醛渣、风化煤好,在磷矿粉添加量为80 g/kg时,土壤有效态Pb的含量降低了23.79%;3 种修复剂都能显著降低土壤有效态Cd,在磷矿粉添加量为40 g/kg时,土壤有效态Cd的含量降低最显著,较对照降低了83.09%.在本试验条件下,3 种修复剂对4 种重金属复合污染土壤的修复效果,以Cd 较好,其次是Zn,对Pb的修复效果较差.     

Remediation of Soils Contaminated with Molybdenum using Soil Amendments and Phytoremediation

For ruminants, there is a narrow span betweennutritional deficiency of Molybdenum and its potential toxicity. Molybdenosis occurs among cattlefeeding on forage with Mo concentrations above10 μg g^-1 or a Cu:Mo ratio <2. In the areaunder investigation forage Mo contents in the valleyare as high as 180 μg g^-1 due to industrialpollution, while the alpine pastures, where cattlegraze during summer, are nutrient (e.g. Cu) deficient.When driven to the valley pastures in fall, animalsoften fell ill with molybdenosis, and several died.The aim of the study was to remediate this 300 ha area. Two approaches were attempted: (1) to reduce theMo contents of the forage by immobilizing soil Mo, and(2) to increase plant Mo contents by mobilizing soilMo to increase plant Mo which may then be removed fromthe system (phytoremediation).In a soil extraction experiment we demonstrated thatphosphate fertilization, ammonium sulfate amendment,vermiculite, humic acid and sewage sludge increased Moleaching by 30 to 110%. Fe-humate and Mn-humateapplication decreased Mo in the leachate from96 μg L^-1 to 55 and 7 μg L^-1,respectively. Plant Mo contents were increased up to170% by P-fertilizer and up to 150% by vermiculite.Conversely, sewage sludge, Fe- and Mn-humate decreasedplant Mo contents by 60, 40 and 75% in thegreenhouse. In the field study, the effects weresmaller, but Mo export through plant harvest increasedby 88% after P-fertilization and 84% aftervermiculite amendment. Mn-humate and sewage sludgedecreased plant Mo content by 25 and 40%,respectively, rendering the forage suitable forfeeding of ruminants. P-fertilization and vermiculitemay thus be recommended for the severely contaminatedsites to enhance phytoremediation through Mo export,and Mn-humate and sewage sludge application appearsuited to remediate the less severely contaminated sites.     

Plant Availability and Uptake of Lead, Zinc, and Cadmium in Soils Contaminated with Anti-corrosion Paint from Pylons in Comparison to Heavy Metal Contaminated Urban Soils

Red lead (Pb₃O₄) has been used extensively in the past as an anti-corrosion paint for the protection of steel constructions. Prominent examples being some of the 200,000 high-voltage pylons in Germany which have been treated with red lead anti-corrosion paints until about 1970. Through weathering and maintenance work, paint compounds and particles are deposited on the soils beneath these constructions. In the present study, six such “pylon soils” were investigated in order to characterize the plant availability and plant uptake of Pb, Cd, and Zn. For comparison, three urban soils with similar levels of heavy metal contamination were included. One phase extractions with 1 M NH₄NO₃, sequential extractions (seven steps), and extractions at different soil pH were used to evaluate the heavy metal binding forms in the soil and availability to plants. Greenhouse experiments were conducted to determine heavy metal uptake by Lolium multiflorum and Lactuca sativa var. crispa in untreated and limed red lead paint contaminated soils. Concentrations of Pb and Zn in the pylon soils were elevated with maximum values of 783 mg Pb kg⁻¹ and 635 Zn mg kg⁻¹ while the soil Cd content was similar to nearby reference soils. The pylon soils were characterized by exceptionally high proportions of NH₄NO₃-extractable Pb reaching up to 17% of total Pb. Even if the relatively low pH of the soils is considered (pH 4.3–4.9), this appears to be a specific feature of the red lead contamination since similarly contaminated urban soils have to be acidified to pH 2.5 to achieve a similarly high Pb extractability. The Pb content in L. multiflorum shoots reached maximum values of 73 mg kg⁻¹ after a cultivation time of 4 weeks in pylon soil. Lime amendment reduced the plant uptake of Pb and Zn significantly by up to 91%. But L. sativa var. crispa cultivated on soils limed to neutral pH still contained critical Pb concentrations (up to 0.6 mg kg⁻¹ fresh weight). Possible mechanisms for the exceptionally high plant availability of soil Pb derived from red lead paint are discussed.     

Amelioration of Cadmium Contaminated Soils Using Cation Exchangers

ABSTRACT

The contamination of soil and water with cadmium (Cd) is an environmental issue worldwide. Using lettuce (Lactuca sativa cv. ‘Cos’) in a glasshouse-based growth trial, two cation exchange materials [a zeolite and a kaolin amorphous derivate (KAD)] were examined for their ability to remove Cd from the soil solution and hence decrease the uptake of Cd by plants. Zeolite (applied at a rate of 2.5 t ha^{? 1}) was ineffective at reducing Cd uptake and accumulation in lettuce. When applied at a rate of 2.5 t ha^{? 1}, the KAD significantly reduced Cd uptake in all soils examined (ranging from a 26 to 64% reduction). Thus, KAD is considered to be potentially beneficial for the growth of plants in Cd-contaminated soils, although care must be taken to ensure that growth is not limited by deficiencies of the other nutrients for which KAD has a high affinity.