六价铬污染土壤后形态变化及其对土壤脲酶活性的影响

采用室内模拟方法较为系统地研究了六价水溶态铬和总铬对土壤脲酶活性的影响。结果表明,六价铬进入土壤后,水溶态含量迅速降低,降幅随培养时间延长而减缓;水溶态铬含量与外源总铬的变化呈极显著正相关;六价铬抑制土壤脲酶活性,且脲酶活性与六价水溶态铬达到极显著负相关,揭示脲酶活性可作为土壤铬污染程度的指标之一;从土壤脲酶角度获得的红壤轻度和中度污染时临界浓度,土壤总铬和水溶态铬含量分别为17．07、85．37mg·kg-1和0．78、3．88mg·kg-1;随土壤肥力降低,土壤脲酶的ED10和ED50递减。     

柠檬酸/柠檬酸钠淋洗铬污染土壤效果及弱酸可提取态铬含量的变化

研究了用0.2 mol.L-1柠檬酸/柠檬酸钠（摩尔比为1∶1）复合淋洗剂对污染土壤中铬的淋洗效果,及淋洗过程中C（rⅥ）和C（rⅢ）以及弱酸可提取态的含量随淋洗时间的变化,污染土壤取自于沈阳市沈北新区铬渣堆放场地污染土壤。结果表明,在该复合淋洗剂的解吸附与络合的双重作用下,总铬的短时间去除效率较高,淋洗8 h和24 h的去除率分别为33.6%和36.0%,其中淋洗24h时C（rⅥ）和C（rⅢ）的去除率分别达到38.5%和30.0%。淋洗过程中土壤中铬的形态发生了重新分配,弱酸可提取态占总铬比例增加,从而有利于铬在土壤中的迁移。     

垃圾渗滤液对土壤铁锰有效性及地下水质的影响

受垃圾渗滤液影响，垃圾场周边土壤有机物含量增加。试验结果显示，随着土壤有机物含量的增加，土壤中有效态铁锰含量增大。垃圾场周边土壤中渗滤液有机物和金属铁锰共存时，大量的有机物质能活化土壤中的铁锰，增加其有效性，增强其在土壤中的迁移能力，从而造成垃圾场地下水较严重的铁锰污染。     

外源铬在土壤中的形态转化

本试验用逐级提取方法，研究了外源铬进入土壤后的形态转化，结果表明：添加到土壤中的Ｃｒ（Ⅵ）很快还原为Ｃｒ（Ⅲ）而失去其活动性，水溶态和变换态铬含量在培育６周后已恢复到对照水平，添加的Ｃｒ（Ⅲ）很快被土壤吸附和沉淀而固定，难以被Ｈ２Ｏ和ＮＨ４Ａｃ提取。添加的有机结合态铬能显土壤中水溶态和交换态铬含量，并能在较长时间内稳定存在于土壤中，添加污泥形式的铬进入土壤主要以残渣态、沉淀态和有机紧结合态铬为主     

垃圾堆肥对铬污染土壤的修复机理研究

运用二次通用旋转组合试验设计，通过模拟土培试验，研究垃圾堆肥对铬污染土训中有效铬含量的影响，铬的形态变化。结果表明，垃圾堆肥可显著减少铬污染土壤中有效铬含量，垃圾堆肥主要是促进水溶志铬向结晶形沉淀态铬转化；垃圾堆肥用于修复铬污染土壤是安全的。     

连二亚硫酸钠对铬污染土壤修复条件优化及生物有效性研究

选用连二亚硫酸钠作为修复药剂,通过正交试验,探讨了药剂量、水土比、养护时间及搅拌时间等4个因素对该药剂修复铬污染土壤效果的影响,并基于肠胃模拟方法,考察了修复前后土壤中铬的生物有效性变化,并评估其健康风险。结果表明,就铬污染土壤而言,药剂量对修复后土壤的六价铬浸出浓度影响最大,其他因素次之。达到较好修复效果的最佳修复条件为药剂量为8%、水土比为0.5、养护时间为1天、搅拌时间为15 min。药剂修复后土壤的六价铬生物有效性大幅降低,降幅为63.21%~84.67%,六价铬致癌风险降幅达81.7%,有效降低人体健康风险。     

山东省种植区地下水硝酸盐污染空间变异及分布规律研究

近年来,我国部分地区地下水硝酸盐污染态势十分严峻,特别是集约化种植区由于施用大量氮肥导致的硝酸盐污染更为严重。为控制污染,应掌握地下水硝酸盐污染的空间变异规律与分布特征。采用地统计学方法,对山东省种植区地下水硝态氮含量数据进行空间变异分析。结果表明,不同区域地下水硝态氮含量存在一定的差异,存在明显的趋势效应以及变异性,且含量随地下水深度增加而减少。通过相关性分析,获得与地下水硝态氮含量相关性最高的两个因子（土壤有机质含量和全氮含量）,并作为协克里金（Cokriging）插值方法中的协同因子,对山东省地下水硝酸盐污染进行插值。经比较分析,协克里金法比普通克里金法（Ordinary Kriging）的精度高,减少了80%的平均误差。协克里金法空间插值结果表明,空间分布规律表现在从西南到东北逐渐升高的方向性效应,而地下水硝态氮含量较高的区域主要分布在潍坊、青岛、烟台种植区,如青岛的平度、莱西,潍坊的寿光等农业较发达的种植区。     

菲不同污染方式对土壤酶活性的影响北大核心CSCD

菲作为多环芳烃类污染物的代表,正以低剂量叠加的方式在土壤中逐步累积,对土壤生态安全造成潜在威胁。本研究模拟菲在一次污染和累积污染方式下对土壤酶活性的影响及其与菲有效性之间的关系。结果表明,在菲累积和一次污染条件下,土壤菲可提取态和有效态含量随培养时间的延长呈现出前2周（1～14d）下降速率较快,3～8周（14～56d）逐渐减缓的趋势。与一次污染相比,累积污染的土壤菲可提取量和有效态含量均较低。在2种污染方式下,土壤脲酶,脱氢酶和蔗糖酶均存在不同程度的被抑制现象,并且酶活性在前2周被短时间抑制,3～8周酶活性被激活而增强。与一次污染相比,累积污染的土壤酶活性被抑制效应减弱。土壤脱氢酶对菲污染反应灵敏,并与土壤可提取态和有效态菲含量显著相关,最能反映菲在土壤中的环境风险。     

基于知识图谱分析的污染场地研究现状与发展趋势

为了解国内外污染场地相关研究状况,利用知识图谱工具VOSviewer、CiteSpace与HistCite对Web of Science核心合集数据库中发文的主要国家（地区）与机构、主要发文期刊、主要研究学者、重要文献和研究热点及其变化趋势等进行了计量分析。结果表明：（1）污染场地的研究涉及多个国家之间相互合作,发文机构中中国科学院、橡树岭国家实验室、滑铁卢大学、中国科学院大学与亥姆霍兹环境研究中心在该研究领域合作广泛。中国于近五年发文量超过美国,成为该领域发文最多的国家。（2）污染场地研究的主要发文期刊有Science of the Total Environment、Chemosphere、Environmental Science & Technology、Environmental Science and Pollution Research等,Naidu Ravi、Huang Guohe、Megharaj Mallavarapu等是该领域发文较多的研究学者。污染场地前十（TOP 10）的重要文献中,生物修复相关内容中占据了较高比例。（3）关键词聚类网络主要可分为污染场地生物毒理研究、土壤重金属及修复技术、污染物环境行为及水体修复、有机污染物生物修复等4类。（4）文献计量的结果分析表明土壤与地下水均为污染场地有害物质重要承载体,污染场地中土壤和地下水具有一体性,如果忽视了对地下水中污染的修复,则可能会导致场地的二次污染。重金属与多环芳烃是污染场地重点关注的污染物,我国目前重金属污染防治工作依然不容乐观,需要进一步加强和落实相应工作。寻求高效绿色的修复技术仍是解决污染场地问题的一个重点,提升微生物修复技术在有机污染场地修复中的应用价值,具有重要意义。     

石灰用量对污染红壤和黄泥土中有效态铜锌含量的影响

采用外源加入重金属铜锌硝酸盐的方法,制成铜、锌单一及复合污染的三级污染红壤和黄泥土（Cu 200mg/kg、Zn 400 mg/kg）,稳定一个月,施入低（0.50 g/kg）、中（1.50 g/kg）和高（2.50 g/kg）3种不同用量的石灰,稳定两个月后测定土壤有效态铜、锌含量和pH值,以阐明石灰用量对不同污染土壤中重金属有效态含量的影响。结果表明,随石灰用量的增加,复合污染红壤中有效态铜含量较对照依次降低31%、76%和87%;而石灰用量对黄泥土中有效态铜影响的差异不显著;两种土壤中有效态锌含量均随石灰用量的增加而显著减少;复合污染较单一污染相比,有效态铜及有效态锌的含量差异不显著。在复合污染下,低、中量石灰使黄泥土中有效态铜含量较红壤减少89%和63%,有效态锌减少27%和65%。但加入高量石灰,两种土壤差异不显著。石灰能够降低单一与复合污染铜、锌有效态的含量,但其效果因土壤类型而异,在红壤上选择施用高量石灰而在黄泥土上则适宜施用低中量石灰,以取得最佳的修复效果和效益。     

Soil and water contamination by arsenic from A tannery waste

The pollution of soil by arsenic contained in tannery waste is reported. Over 81 years of operation, a variety of arsenical compounds including sodium arsenite were used as pesticides at the tannery, the arsenic finding its way to the site in question as liquid waste which was disposed of either by burial or spray issigation. X-ray Fluorescence Spectrometry (XRF) was used to determine the levels of arsenic in the soil. Concentrations recorded were comparable to those in soils polluted by agricultural use of arsenical pesticides or by contamination from mining activities. In contrast to arsenic pollution from other sources however, contamination extends to a considerable depth through the soil profile. Analysis of soil water by hydride generation atomic absorption spectrometry showed evidence of arsenic movement through this medium although penetration had not extended to the groundwater. Batch leaching of soil samples with distilled water confirmed the potential mobility of arsenic.     

On-site remediation of chromium-contaminated sediments by combination of sediment washing and stabilization with magnesium oxide/limestone mixtures

Goal, Scope and Background  The remediation of heavy-metalcontaminated soils and sediments is of significant value to industrial areas around the world. The spread of such pollutants can result in a potential risk of entering the groundwater system and being transported to potential receptors. Leaching techniques can be an effective treatment option for the metal removal from soils and sediments. This approach consists of washing or leaching the contaminated soil with an appropriate reagent and the subsequent treatment of the leaching in an above-ground installation (on-site treatment) where metals can be removed and concentrated into a smaller volume. Among the heavy metals, chromium is a commonly identified soil contaminant, particularly in sites with intensive economic activities including agriculture, industrial, mining and mineral,processing. Objective  The objective of this work was the evaluation and development of a leaching process for the remediation of soils and sediments polluted with chromium at laboratory scale. Chromium soil pollution was generated after the breakdown of a channel containing chromium wastes from a tannery plant. The pollution extension has been estimated to be on the order of thousands of tonnes of soil to be treated, with chromium contents ranging from 500 to 17,000 mg kg^-1 soil. Methods  The whole process investigated in this study integrates three stages; a) chromium leaching from a sediment using a diluted sulphuric acid solution, b) treatment of the leaching effluents with a magnesium oxide/limestone mixture for the precipitation of chromium hydroxide after acidity neutralisation, and c) polishing step to remove the eventual remaining chromium by adsorption onto natural zeolite. The amount of contaminated sediment treated ranged from 0.5 to 2 kg with chromium contents of between 2000 and 17,000 mg kg^-1. Results and Discussion  The paper describes results on the performance of the process and the optimisation of steps including influence of acid sulphuric concentration, chromium removal efficiency as well as alkaline reactive mixture proportions. Effluents from the leaching cells showed a significant decay on the chromium concentration with the increase of leaching runs and a high content of acidity (pH values close to 0.5). The treatment of these effluents in a second cell containing magnesium oxide/ limestone mixtures resulted in a high efficiency in neutralisation of acidity (pH values around 7) and chromium removal (concentrations below 5 mg 1^-1). The passage through a third compartment containing zeolite as an adsorbent decreased the chromium concentration below 0.5 mg 1^-1, Conclusions  From the results obtained on the chromium leaching and immobilisation with magnesium oxide/limestone mixture at a laboratory scale, it could be pointed out that: (a) diluted sulphuric acid solutions (3%) demonstrated a high efficiency on chromium removal from sandy polluted soils on the kilogram scale, (b) mixtures of magnesium oxide/limestone demonstrated a high capacity to neutralise the residual high acidity present on the effluents and to remove chromium by precipitation and (c) between the limestone and caustic magnesia mixtures, those containing more than 60% of caustic magnesia provide the higher efficiency. Recommendation and Outlook  Future work would be directed to the evaluation of the integrated process of leaching and chromium precipitation on column at a scale of 100 to 1000 kg.     

Assessment of the Pollution from Tannery Effluents upon Waters and Soils in and Around Kula Vicinity, Turkey

More than 50 tanneries are operated in Kula, Turkey which is located on highly permeable geological units. The untreated effluents from the tanneries discharged onto the ground surface may cause pollution in surface waters, in groundwater, and in soil. Since the water resources of the region are used for drinking, agricultural, and industrial purposes, the quality assessment of groundwaters and surface waters is completed in the content of this study. Additionally, the surface soil samples are analyzed for their heavy metal content to describe the size of the pollution. The results obtained from the analysis of the water samples show that the concentrations are mostly within drinking water limits. But, concentrations are expected to increase in the next years as no effective effluent collection and treatment is present in the tanneries. Although the concentrations of K, SO₄, Mg, Na, and Cl exceed the permissible limits for drinking water in some cases, they may not directly be caused by tannery activities. Nevertheless, they should be assessed as an indicator of the beginning of groundwater pollution. Also, soil samples collected near the tannery district are extremely polluted. This paper discusses the assessment of the geochemical dispersals of Cr and other pollutants derived from the tannery activities within soil and water in Kula.     

Human and ecological risks of metals in soils under different land-use types in an urban environment of Bangladesh

Trace metal contamination in soil is of great concern owing to its long persistence in the environment and toxicity to humans and other organisms.Concentrations of six potentially toxic trace metals,Cr,Ni,Cu,As,Cd,and Pb,in urban soils were measured in Dhaka City,Bangladesh.Soils from different land-use types,namely,agricultural field,park,playground,petrol station,metal workshop,brick field,burning sites,disposal sites of household waste,garment waste,electronic waste,and tannery wast,and construction waste demolishing sites,were investigated.The concentration ranges of Cr,Ni,Cu,As,Pb,and Cd in soils were 2.4–1258,8.3–1044,9.7–823,8.7–277,1.8–80,and 13–842 mg kg^-1,respectively.The concentrations of metals were subsequently used to establish hazard quotients(HQs)for the adult population.The metal HQs decreased in the order of As>Cr>Pb>Cd>Ni>Cu.Ingestion was the most vital exposure pathway of studied metals from soils followed by dermal contact and inhalation.The range of pollution load index(PLI)was 0.96–17,indicating severe contamination of soil by trace metals.Considering the comprehensive potential ecological risk(PER),soils from all land-use types showed considerable to very high ecological risks.The findings of this study revealed that in the urban area studied,soils of some land-use types were severely contaminated with trace metals.Thus,it is suggested that more attention should be paid to the potential health risks to the local inhabitants and ecological risk to the surrounding ecosystems.     

影响土壤中铬, 锰的氧化还原反应的环境因素

Disposal of chromium(Cr) hexavalent form,Cr(VI),in soils as additions in organic fertilizers,liming materials or plant nutrient sources can be dangerous since Cr(VI) can be highly toxic to plants,animals,and humans.In order to explore soil conditions that lead to Cr(VI) generation,this study were performed using a Paleudult(Dystic Nitosol) from a region that has a high concentration of tannery operations in the Rio Grande do Sul State,southern Brazil.Three laboratory incubation experiments were carried out to examine the influences of soil moisture content and concentration of cobalt and organic matter additions on soil Cr(VI) formation and release and manganese(Mn) oxide reduction with a salt of chromium chloride(CrCl 3) and tannery sludge as inorganic and organic sources of Cr(III),respectively.The amount of Cr(III) oxidation depended on the concentration of easily reducible Mn oxides and the oxidation was more intense at the soil water contents in which Mn(III/IV) oxides were more stable.Soluble organic compounds in soil decreased Cr(VI) formation due to Cr(III) complexation.This mechanism also resulted in the decrease in the oxidation of Cr(III) due to the tannery sludge additions.Chromium(III) oxidation to Cr(VI) at the solid/solution interface involved the following mechanisms:the formation of a precursor complex on manganese(Mn) oxide surfaces,followed by electron transfer from Cr(III) to Mn(III or IV),the formation of a successor complex with Mn(II) and Cr(VI),and the breakdown of the successor complex and release of Mn(II) and Cr(VI) into the soil solution.     

Impact of Past Mining Activity on the Quality of Water and Soil in the High Moulouya Valley (Morocco)

Physical and chemical properties and the total content of potentially toxic metals (PTMs) in waters and soils were studied from the High Moulouya Valley (Morocco) in order to assess the impact of the past mining activity on their quality and to lay the foundations of a potential reclamation of the area. Surface water and groundwater samples were collected from the Moulouya River and mine pit lakes; tailings and soils were sampled inside and outside the mine sites of Zeïda, Mibladen, and Aouli. Both waters and soils were alkaline, due to the limestone environment, and contained Pb and Zn as main metallic contaminants. Pollution levels were highest within the Mibladen mining site, and soil pollution was mainly restricted to the areas where activities of metal concentration were carried out. Tailings and soils from these areas besides Pb and Zn were also polluted by As, Cd, and Cu showing clay fraction highly enriched in metal contaminants. At the time of study, all soils and wastes (including the highly polluted tailings) were in advanced stage of spontaneous herbaceous and arbustive revegetation. It is concluded that, in the High Moulouya Valley, the processes governing PTM transfer from the element-rich sites to the nearby environment are strongly influenced by pH, carbonate content, and semi-arid climate reducing metal mobility from the mining waste impoundments by dissolution. The transfer by wind and water erosion of metal-enriched fine waste particles is likely to be a much more important vector for metal dispersion. In this perspective, among a range of land remediation techniques available, natural and oriented revegetation could represent a low-cost and possible permanent solution.     

不同价态铬的土壤碱性磷酸酶效应模拟研究

铬是环境中四大污染元素之一,其不同价态间对生物的生态毒性差异较大。采用模拟方法对Cr3＋和Cr6＋的土壤碱性磷酸酶效应进行了研究。结果表明,铬显著抑制了土壤碱性磷酸酶活性,其中Cr3＋的抑制作用远强于Cr6＋,土壤轻度Cr3＋和Cr6＋污染时的临界浓度分别为151和1132mg·kg-1,二者相差6.5倍;碱性磷酸酶活性及动力学特征参数Vmax、k等与Cr浓度间达显著或极显著负相关,揭示土壤磷酸酶活性及Vmax、k可作为土壤Cr污染的监测指标之一;模型U=β0（/β1×C＋1）揭示酶与铬间的机理为完全抑制,动力学则进一步细化为非竞争性抑制;计算获得的抑制常数Ki为Cr3＋     

南通市城市边缘带土壤重金属污染现状及评价

通过对不同土地利用方式下的7个样区进行系统的采样测定,对南通城市边缘带土壤重金属富集与污染状况进行了分析与评价。结果显示,研究区土壤未发生明显的重金属污染。但3个样区的土壤有轻度的重金属污染现象,Zn是发生富集最普遍的元素,约76%的样点土壤Zn富集指数>1,18%的样点土壤出现Zn的轻度污染。Cu、Pb等重金属元素导致的污染也在零星样点被发现。方差分析表明,土地利用方式不是导致研究区土壤重金属含量空间差异的主要因素,而土壤类型、样区空间环境与土壤重金属含量及富集、污染有相对密切的关系。