有机螯合剂在镍污染土壤植物修复中的研究进展

有机螯合剂的存在能促进土壤中的固相Ni向水溶态转化，提高Ni的生物可利用性。本文讨论了土壤中镍的存在形态以及有机螯合剂对土壤中镍形态的影响。并从植物吸收Ni的机制出发，阐述有机螯合剂对植物吸收Ni和植物生物量的影响。分析了植物修复的螯合诱导技术的一些局限性，并对植物修复螯合诱导技术提出展望。     

巯基改性膨润土对小白菜吸收累积镍的影响

盆栽条件下,采用巯基改性膨润土(以下简称巯基土)为重金属钝化材料修复镍污染土壤,考察在不同镍污染程度和土壤pH下,其对盆栽小白菜吸收累积镍的影响。结果表明,巯基土可明显降低高污染土盆栽小白菜对镍的吸收累积。将巯基土按1∶1的质量比与成本较低的钠化改性膨润土混合制成混合材料,混合材料对低污染土有良好修复效果,当混合材料添加量为2.0%(质量分数)时,低污染土盆栽小白菜中的镍含量比空白对照(CK)组降低了41.8%。土壤pH为5.50时,混合材料对镍污染土壤的修复效果最好。土壤总镍含量与有效态镍含量占比呈负相关关系,盆栽小白菜中镍含量与盆栽土壤有效态镍含量占比呈极显著正相关关系。在利用重金属修复材料进行污染治理时,除关注重金属总量外,更应根据土壤中重金属的赋存形态,尤其是有效态含量来决定修复材料的施加量。     

农药污染土壤的生物修复技术

本文综述了土壤农药有机污染的生物修复技术 ,重点分析了植物、微生物对土壤农药污染的修复机制以及影响因子 ,介绍了几种生物修复技术     

植物修复及重金属在植物体内形态分析综述

植物修复是重金属污染土壤治理的重要方法,因其具有高效、经济及生态协调性等优势而广受关注。当前相关研究主要包括超积累植物体内重金属的迁移转化与形态分析方法,土壤修复后植物的减量化、无害化和资源化利用等方面。实验研究及修复工程中存在的问题主要体现为:(1)基础研究方面,目前对植物超积累重金属的分子机制、调控原理等方面的研究不够完善;(2)应用技术方面,修复植物的规模化种植、适用的栽培技术、收获物安全处置及资源化利用方面仍是植物修复技术发展的瓶颈。因此,目前需要深入研究超积累植物吸收、运输和积累重金属的生理机制,利于植物生长的农业措施以及用于修复的植物收获后的相应处理技术。同时,应结合重金属在植物体内的形态,对修复后的植物进行合理的减量化、无害化、资源化处理,以便于更加科学合理地选择土壤重金属修复植物,大规模推广植物修复技术的应用。     

农药污染土壤的生物修复技术

本文综述了土壤农药有机污染的生物修复技术,重点分析了植物、微生物对土壤农药污染的修复机制以及影响因子,介绍了几种生物修复技术。     

有机螯合剂与磷酸盐联合稳定垃圾焚烧飞灰中重金属的作用机理

为探讨二硫代氨基甲酸型有机螯合剂(FACAR)和重过磷酸钙(TSP)对垃圾焚烧飞灰中重金属Pb、Cd、Ni的稳定作用机制,对稳定前后的飞灰采用BCR连续提取法、 X射线衍射(XRD)分析以及扫描电镜-能谱(SEM-EDS)联用等分析方法进行了表征。结果表明:投加质量分数5%的FACAR能有效稳定飞灰中Pb、Cd和Ni,其浸出浓度低于《生活垃圾填埋场污染控制标准》(GB 16889-2008)规定的浸出浓度限值;采用3%FACAR和3%TSP复配药剂处理,可使飞灰达到GB 16889-2008进场要求;经复合药剂稳定处理后的飞灰颗粒表面孔隙度明显降低,飞灰中Pb、Cd和Ni的形态均由不稳定态向稳定态转化。该复合稳定剂的稳定机制主要为螯合、共沉淀和吸附联合作用机制,其中,有机螯合剂中含硫官能团是影响重金属稳定的主要因素,且重金属具有优先与含硫官能团结合的特性。     

氮磷钾和乙二胺四乙酸对镉污染三叶鬼针草的吸收特征研究

超富集植物的筛选是植物修复重金属污染土壤技术的核心内容.采用盆栽试验的方法,研究了Cd胁迫下添加营养元素N、P、K和螯合剂乙二胺四乙酸(EDTA)对三叶鬼针草(Bidens pilosa L.)的生长反应和生理生化特性以及对Cd的吸收积累特征.盆栽试验结果显示,在Cd为10 mg/kg时,添加营养元素N、P、K和EDT...     

钝化剂在烟草植物修复铅镉污染土壤中的作用

重金属钝化剂可以改变土壤中重金属的形态，降低其在土壤中的有效浓度、植物毒性及生物有效性，影响污染土壤中植物的生长及其对重金属的吸收。在温室盆栽条件下研究了施加羟基磷灰石（HA）、纳米羟基磷灰石（nHA）、纳米零价铁（nFe0）和纳米TiO2（nTiO2）对烟草植物修复铅镉污染土壤的作用。结果表明，HA降低土壤中Ph、cd的有效性、促进烟草生长、增加了烟草叶、茎、根中cd的吸收量和根系中Pb的吸收量，有利于Ph、cd的钝化和植物修复。nHA也可以降低土壤中Pb、cd的有效性，增加了烟草叶中cd的吸收量，有利于Pb、cd的钝化和cd的植物提取。nFe0和nTiO2：对于土壤Pb和cd的钝化作用和植物修复均没有显著影响。综合来看，HA最适合应用于烟草植物修复铅镉污染土壤。     

土壤重金属污染的植物修复研究进展

详细阐述了植物修复的生理学、分子生物学机制，包括超积累植物对根际土壤中重金属的活化，超量积累植物对土壤重金属吸收及其解毒机理，并就该领域今后的研究方向和存在的问题作了探讨。     

堆肥技术处理有机污染土壤的研究进展

堆肥化处理是一种新型、高效的生物修复技术 ,本文综述了国内外应用堆肥技术处理有机污染土壤的研究进展 ,总结了对有机污染土壤进行堆肥处理的主要影响因素。本文还指出了堆肥技术目前存在的问题 ,并对其发展前景进行了展望     

Effects of lead and chelators on growth, photosynthetic activity and Pb uptake in Sesbania drummondii grown in soil

Effects of lead (Pb) and chelators, such as EDTA, HEDTA, DTPA, NTA and citric acid, were studied to evaluate the growth potential of Sesbania drummondii in soils contaminated with high concentrations of Pb. S. drummondii seedlings were grown in soil containing 7.5 g Pb(NO(3))(2) and 0-10 mmol chelators/kg soil for a period of 2 and 4 weeks and assessed for growth profile (length of root and shoot), chlorophyll a fluorescence kinetics (F(v)/F(m) and F(v)/F(o)) and Pb accumulations in root and shoot. Growth of plants in the presence of Pb+chelators was significantly higher (P<0.05) than the controls grown in the presence of Pb alone. F(v)/F(m) and F(v)/F(o) values of treated seedlings remained unaffected, indicating normal photosynthetic efficiency and strength of plants in the presence of chelators. On application of chelators, while root uptake of Pb increased four-five folds, shoot accumulations increased up to 40-folds as compared to controls (Pb only) depending on the type of chelator used. Shoot accumulations of Pb varied from 0.1 to 0.42% (dry weight) depending on the concentration of chelators used.     

Heavy metal speciation and mobility assessment of arid soils in the vicinity of Al Ain landfill, United Arab Emirates

Sixty-four surface soil samples taken in the vicinity of Al Ain landfill were analysed for cadmium, chromium, copper, nickel, lead and zinc by inductively coupled plasma spectroscopy. Extraction techniques were used to establish the association of the total concentrations of the six metals in the soil samples with their contents in the exchangeable, carbonate, iron/manganese oxides, and residual fractions. In the investigated soils, the recorded concentrations were as follows: 0.043 mg kg^-1 for cadmium, 19.1 mg kg^-1 for chromium, 53.3 mg kg^-1 for copper, 60 mg kg^-1 for nickel, 13.7 mg kg^-1 for lead, and 117 mg kg^-1 for zinc. Cadmium, chromium, nickel, lead and zinc concentrations in the investigated soil samples reflect the natural background values in shale, whereas copper is slightly enriched. I-geo (geoaccumulation index) values of the metals in the soils under study indicate that they are uncontaminated with cadmium, chromium, nickel, lead and zinc, but contaminated to moderately contaminated with copper. Heavy metal contents in the sediments were found to be significantly influenced by different physico-chemical parameters. The effect of these parameters can be arranged in the following order: clay fraction > carbonate fraction > silt fraction > organic matter fractions. A sequential extraction procedure showed that the total concentrations of the heavy metals are largely bound to the residual phase (retained 71.4% of cadmium, 77.8% of chromium, 75% of copper, 47% of nickel, 62.8% of lead, and 75.8% of zinc). A likely sequence of mobility in the investigated soils is as follows: chromium > lead > nickel > cadmium > zinc > copper.     

Heavy metal contamination characteristic of soil in WEEE (waste electrical and electronic equipment) dismantling community: a case study of Bangkok,Thailand

Sue Yai Utit is an old community located in Bangkok, Thailand which dismantles waste electrical and electronic equipment (WEEE). The surface soil samples at the dismantling site were contaminated with copper (Cu), lead (Pb), zinc (Zn), and nickel (Ni) higher than Dutch Standards, especially around the WEEE dumps. Residual fractions of Cu, Pb, Zn, and Ni in coarse soil particles were greater than in finer soil. However, those metals bonded to Fe-Mn oxides were considerably greater in fine soil particles. The distribution of Zn in the mobile fraction and a higher concentration in finer soil particles indicated its readily leachable character. The concentration of Cu, Pb, and Ni in both fine and coarse soil particles was mostly not significantly different. The fractionation of heavy metals at this dismantling site was comparable to the background. The contamination characteristics differed from pollution by other sources, which generally demonstrated the magnification of the non-residual fraction. A distribution pathway was proposed whereby contamination began by the deposition of WEEE scrap directly onto the soil surface as a source of heavy metal. This then accumulated, corroded, and was released via natural processes, becoming redistributed among the soil material. Therefore, the concentrations of both the residual and non-residual fractions of heavy metals in WEEE-contaminated soil increased.     

Cd、Ni单一及复合污染对土壤酶活性的影响

采用外源添加重金属和露天盆栽实验研究了Cd、Ni对含羞草、三叶草根际土壤脲酶、过氧化氢酶和蔗糖酶活性的影响。结果表明,Cd、Ni单一污染条件下,低浓度的Cd、Ni对含羞草组、三叶草组的脲酶、过氧化氢酶有激活作用,高浓度的Cd、Ni对土壤脲酶、过氧化氢酶有一定的抑制作用;对蔗糖酶有较强的抑制作用。在Cd、Ni复合污染条件下,对含羞草组、三叶草组的脲酶、过氧化氢酶和蔗糖酶产生抑制作用;Cd、Ni单一及复合污染对土壤酶活性的抑制大小顺序为:脲酶>蔗糖酶>过氧化氢酶,其中土壤脲酶可以作为Cd、Ni污染的预警指标。含羞草能显著提高土壤脲酶、过氧化氢酶和蔗糖酶的活性,修复能力大于三叶草,在Cd、Ni污染修复方面有很好的应用前景。     

污泥果肥利用中重金属迁移特征研究

为了厦门城市污泥的安全利用，将石渭头污水处理厂污泥经过好氧堆肥后施用于柚子树，对重金属元素在土壤、树叶及果肉中的迁移特征进行了研究。结果表明：Cd在土壤中的富集能力强；重金属元素从土壤向树叶迁移累积能力比向果肉的大得多，污泥肥料不能用于叶类食用植物的施用；Cr向树叶、Ni向果肉的迁移累积能力强；泥肥的施用加重了土壤中Cd的污染，提高了Cr向树叶、Ni向果肉的迁移能力；污泥果肥利用需降低Ni的浓度，对污泥中含量较高的Cu、Zn、Ni、Cr和Cd需进行跟踪检测。     

Phytoremediation of mixed-contaminated soil using the hyperaccumulator plant Alyssum lesbiacum: evidence of histidine as a measure of phytoextractable nickel

In this study we examine the effects of polycyclic aromatic hydrocarbons (PAHs) on the ability of the hyperaccumulator plant Alyssum lesbiacum to phytoextract nickel from co-contaminated soil. Planted and unplanted mesocosms containing the contaminated soils were repeatedly amended with sorbitan trioleate, salicylic acid and histidine in various combinations to enhance the degradation of two PAHs (phenanthrene and chrysene) and increase nickel phytoextraction. Plant growth was negatively affected by PAHs; however, there was no significant effect on the phytoextraction of Ni per unit biomass of shoot. Exogenous histidine did not increase nickel phytoextraction, but the histidine-extractable fraction of soil nickel showed a high correlation with phytoextractable nickel. These results indicate that Alyssum lesbiacum might be effective in phytoextracting nickel from marginally PAH-contaminated soils. In addition, we provide evidence for the broader applicability of histidine for quantifying and predicting Ni phytoavailability in soils.     

Sorption of cobalt and nickel on anaerobic granular sludges: isotherms and sequential extraction

The objective of this study was to investigate the sorption capacity and the fractionation of sorbed nickel and cobalt onto anaerobic granular sludges. Two different anaerobic granular sludges (non-fed, pH=7) were loaded with nickel and cobalt in adsorption experiments (monometal and competitive conditions). The combination of sequential extraction with the sorption isotherm analysis allowed the assessment of the sorption capacity of individual fractions present in the anaerobic granular sludges. The operational fractionation of the sorbed heavy metals was determined using a modified Tessier sequential extraction procedure. The sorption characteristics of each extracted fraction (exchangeable, carbonates, organic matter/sulfides and residual fractions) fitted well to the Langmuir model. The organic matter/sulfides fraction showed the highest affinity for cobalt and nickel in both sludges investigated compared to the other operationally defined fractions. The presence of iron negatively affected cobalt and nickel accumulation in this organic matter/sulfides fraction. The trace metals-iron sulfide interactions are likely to be the key process in controlling the distribution of cobalt and nickel during sorption onto non-fed methanogenic granules due to the high affinity of iron sulfides towards the metals studied.     

Spatial distribution and ecological assessment of nickel in sediments of a typical small plateau lake from Yunnan Province,China

Nickel (Ni) in small plateau lake sediments plays an important role in influencing the quality of lake ecosystems with a high degree of endemism and toxicity. This paper focuses on the spatial distribution and ecological risks of nickel in the sediments of Jianhu Lake, a small plateau lake in China, and the influence of pH and total organic carbon (TOC) on nickel concentrations. The results showed that average total nickel concentrations were 138.99 ± 57.57 mg/kg (n = 38) and 184.31 ± 92.12 mg/kg (n = 60) in surface sediments (0–10 cm top layer) and sediment cores (0–75 cm depth), respectively, and that the residual fraction was the main form of nickel. Simultaneously, through a semivariogram model, strong spatial dependence among pH, TOC, and the oxidizable fraction was revealed, whereas total nickel, exchangeable and the weak acid soluble fraction, reducible fraction, and residual fraction showed moderate spatial dependence. The vertical distribution revealed that nickel accumulated mainly in the bottom 5 cm (70-75 cm) of the sediment layer and that the pH was higher there, whereas TOC was concentrated mainly in the top 5 cm of sediment. Using geoaccumulation and a potential ecological risk index, moderate nickel pollution and moderate risk levels were found in most surface sediments, but moderate nickel pollution and high risk levels were observed in most sediment cores. In addition, pH and TOC were found to have a strong effect on the distribution and concentration of nickel and its fractions in the small plateau lake. In summary, nickel posed a certain degree of pollution and ecological risk, which deserves attention in the sediments of small plateau lakes.

     

Heavy metal binding by the polymeric organic fractions of sewage sludges

Organic complexes in sewage sludge play an important role in the speciation and transformation of metals into potentially more toxic and bioavailable forms. Two organic fractions, bacterial extracellular polymer and fulvic acid, were extracted from mixed liquor and digested sewage sludge by methods established as the most appropriate. The homogeneity of the extracts was verified using gel permeation chromatography. Conditional stability constants and complexation capacities of the organic fractions from the sludges with copper, cadmium, nickel and zinc have been determined using equilibrium dialysis titration. Organic fractions extracted from digested sludge demonstrated a greater capacity to complex metals over mixed liquor extracts. Copper formed stronger complexes than nickel with the mixed liquor biomass and cadmium exhibited the greatest affinity for digested sludge organic matter.     

Chelator induced phytoextraction and in situ soil washing of Cu

In a soil column experiment, we investigated the effect of 5 mmol kg(-1) soil addition of citric acid, ethylenediamine tetraacetate (EDTA), diethylenetriamine-pentaacetate (DTPA) and [S,S]-stereoisomer of ethylenediamine-disuccinate (EDDS) on phytoextraction of Cu from a vineyard soil with 162.6 mg kg(-1) Cu, into the test plant Brassica rapa var. pekinensis. We also examined the use of a horizontal permeable barrier, composed of layers of nutrient enriched sawdust and apatite, for reduction of chelator induced Cu leaching. The addition of all chelators, except citric acid, enhanced Cu mobility and caused leaching of 19.5-23% of initial total Cu from the soil column. However, Cu plant uptake did not increase accordingly; the most effective was the EDDS treatment, in which plant Cu concentration reached 37.8 +/-1.3 mg kg(-1) Cu and increased by 3.3-times over the control treatment. The addition of none of the chelators in the concentration range from 5 to 15 mmol kg(-1) exerted any toxic effect on respiratory soil microorganisms. When EDDS was applied into the columns with horizontal permeable barriers, only 0.53 +/- 0.32% of the initial total Cu was leached. Cu (36.7%) was washed from the 18 cm soil layer above the barrier and accumulated in the barrier. Our results indicate that rather than for a reduction of Cu leaching during rather ineffective chelate induced Cu phytoextraction, horizontal permeable barriers could be more effective in a new remediation technique of controlled in situ soil washing of Cu with biodegradable chelates.