Removal of heavy metals by biosorption

Industrialization and urbanization have resulted in increased releases of toxic heavy metals into the natural environment comprising soils, lakes, rivers, groundwaters and oceans. Research on biosorption of heavy metals has led to the identification of a number of microbial biomass types that are extremely effective in bioconcentrating metals. Biosorption is the binding and concentration of adsorbate from aqueous solutions by certain types of inactive and dead microbial biomass. The novel types of biosorbents presently reviewed are grouped under fungal biomass, biomass of non-living, dried brown marine algae, agricultural wastes and residues, composite chitosan biosorbent prepared by coating chitosan, cellulose-based sorbents and bacterial strains. The reports discussed in this review collectively suggest the promise of biosorption as a novel and green bioremediation technique for heavy metal pollutants from contaminated natural waters and wastewaters.     

典型野生食用菌重金属含量及其人体健康风险评价

土壤重金属污染是影响生态环境、食品安全和人体健康的重要因素.云南省土壤重金属背景值较高,且矿产资源丰富、采矿活动频繁,导致土壤重金属含量较高.野生食用菌是高效重金属储积器,云南是中国野生食用菌最大产区.因此,本文以云南省8种典型野生食用菌为研究对象,探究其重金属含量(汞、镉、铅、锌、铜、砷)与分配特征,采用单因子污染指数对其进行重金属污染评价,利用概率方法(THQ指数)评估其对不同年龄人群(成人、儿童)的人体健康风险.研究结果表明,不同种类野生食用菌重金属含量存在显著差异(P<0.05).Hg、Cd、Pb、Zn、Cu浓度范围分别为0.5—7.2、0.3—15、0—26.8、47.7—214、56.7—428 mg·kg^-1 dw;As未检出.此外,Hg、Cd、Pb、Zn、Cu均主要分布于菌盖.除虫草花、白森、干巴菌中Hg未检出,其余重金属污染评价中单因子污染指数均>1,且同一元素在同种野生食用菌不同部位污染程度不同,其中,老人头菌盖受Cd污染最为严重.基于国家食品安全标准,本研究中98%野生食用菌Hg、Cd、Pb含量超标.然而,THQ指数表明,部分野生食用菌中Zn无风险(THQ<1),老人头菌盖、鸡枞菌盖中Cd、Hg、Pb、Cu具有人体健康风险(THQ>1),且风险值儿童>成人.     

Heavy metals and soil microbes

Heavy metal pollution is a global issue due to health risks associated with metal contamination. Although many metals are essential for life, they can be harmful to man, animal, plant and microorganisms at toxic levels. Occurrence of heavy metals in soil is mainly attributed to natural weathering of metal-rich parent material and anthropogenic activities such as industrial, mining, agricultural activities. Here we review the effect of soil microbes on the biosorption and bioavailability of heavy metals; the mechanisms of heavy metals sequestration by plant and microbes; and the effects of pollution on soil microbial diversity and activities. The major points are: anthropogenic activities constitute the major source of heavy metals in the environment. Soil chemistry is the major determinant of metal solubility, movement and availability in the soil. High levels of heavy metals in living tissues cause severe organ impairment, neurological disorders and eventual death. Elevated levels of heavy metals in soils decrease microbial population, diversity and activities. Nonetheless, certain soil microbes tolerate and use heavy metals in their systems; as such they are used for bioremediation of polluted soils. Soil microbes can be used for remediation of contaminated soils either directly or by making heavy metals bioavailable in the rhizosphere of plants. Such plants can accumulate 100 mg g^?1 Cd and As; 1000 mg g^?1 Co, Cu, Cr, Ni and 10,000 mg g^?1 Pb, Mn and Ni; and translocate metals to harvestable parts. Microbial activity changes soil physical properties such as soil structure and biochemical properties such as pH, soil redox state, soil enzymes that influence the solubility and bioavailability of heavy metals. The concept of ecological dose (ED₅₀) and lethal concentration (LC₅₀) was developed in response to the need to easily quantify the influence of pollutants on microbial-mediated ecological processes in various ecosystems.     

A review of combinations of electrokinetic applications

Anthropogenic activities contaminate many lands and underground waters with dangerous materials. Although polluted soils occupy small parts of the land, the risk they pose to plants, animals, humans, and groundwater is too high. Remediation technologies have been used for many years in order to mitigate pollution or remove pollutants from soils. However, there are some deficiencies in the remediation in complex site conditions such as low permeability and complex composition of some clays or heterogeneous subsurface conditions. Electrokinetic is an effective method in which electrodes are embedded in polluted soil, usually vertically but in some cases horizontally, and a low direct current voltage gradient is applied between the electrodes. The electric gradient initiates movement of contaminants by electromigration (charged chemical movement), electro-osmosis (movement of fluid), electrolysis (chemical reactions due to the electric field), and diffusion. However, sites that are contaminated with heavy metals or mixed contaminants (e.g. a combination of organic compounds with heavy metals and/or radionuclides) are difficult to remediate. There is no technology that can achieve the best results, but combining electrokinetic with other remediation methods, such as bioremediation and geosynthetics, promises to be the most effective method so far. This review focuses on the factors that affect electrokinetic remediation and the state-of-the-art methods that can be combined with electrokinetic.     

Isolation and identification of fungi tolerant to polycyclic aromatic hydrocarbons and coal tar from different habitats in Lithuania

A group of 36 fungal strains, belonging to the Lithuanian mycobiota, was collected and isolated from different locations, habitats, and matrices, including creosote-treated wood in storage yards for crosstie wastes. The eight most perspective strains selected according to preliminary assessment of tolerance to coal tar were subsequently identified combining taxonomical evaluation and molecular techniques. The tolerance of the eight identified fungal species (five basidiomycetes and three ascomycetes) to the presence of various concentrations of coal tar, and for the four most perspective fungal strains (Pleurotus sp., Schizophyllum sp., Irpex lacteus, Bjerkandera adusta) to polycyclic aromatic hydrocarbons was evaluated. The ligninolytic enzymatic activity assay of the isolated strains resulted in a good correspondence between the tolerance to pollutants and the capability to produce ligninolytic enzymes indicating that this group of white-rot fungi is perspective for further investigation and eventual usage for mycoremediation of polycyclic aromatic hydrocarbons polluted substrates.     

Microorganisms for remediation of cadmium-contaminated soils

An alternative to the cleaning-up of agricultural soil contaminated by heavy metals is to avoid their transfer from soil to plant by inoculating soil with selected microorganisms able to biosorb heavy metals. Here, four bacteria species and a fungus isolated from contaminated soils revealed their ability to grow in the presence of high cadmium level. We tested their growth capacity related to pH and Cd concentration on synthetic and soil extract media. The comparison of their growth rate, the biosorbed cadmium rate and the specific biosorption allowed to select the most efficient microorganism to be used in bioremediation.     

土壤原位修复技术研究与应用进展

土壤原位修复技术是指不经挖掘,直接在污染场地就地修复污染土壤的土壤修复技术,具有投资低,对周边环境影响小的特点,是土壤修复的研究热点。土壤原位修复技术主要有淋洗,气相抽提（SVE）,多相抽提（MPVE）,气相喷射（IAS）,生物降解,原位化学氧化（ISCO）,原位化学还原,污染物固定,植物修复等。淋洗法主要用于治理高渗透性土壤中的重金属和难挥发降解的有机物。土壤气相抽提和喷射技术适用于处理土壤中的易挥发污染物,并有常与加热技术,生物处理技术等联用,可以起到促进污染物挥发,增氧促分解的作用。多相抽提法主要用于治理存在大量非水相流体的污染场地,可将土壤中有机相污染物直接抽出。生物降解有生物好氧降解、生物厌氧降解、生物还原降解多种,降解方式由污染物种类和地质条件决定。化学方法可将污染物氧化或还原为低毒无毒物质,周期一般较短。固定污染物可以直接加入药剂反应生成沉淀,也可制造合适条件使微生物生成可沉淀重金属的离子。植物修复主要用于富集重金属,成本低廉,但富集了重金属的植物体的有效利用尚待进一步研究。土壤原位修复需要因地制宜,灵活结合工期、污染情况、地质条件、地面设施等,得出最经济实用的修复方法,并在辅助提高技术上展开更多研究,使原位修复技术更经济有效。     

耐性细菌的分离鉴定及重金属污染修复初步研究

清远市是中国最大的电子废弃物拆解基地之一,小作坊生产模式已经进行了20多年,大量无法回收的电子废料和处理残渣等被倾倒在田地、沟渠和山谷中,致使周边土壤长期受到重金属Cd、Cu、Pb污染。近年来国内外对拆解区周边的土壤重金属污染现状分析、健康风险评价等相关报道较多,但针对电子废弃物复合重金属污染生物修复技术的研究却并不多见。通过富集、驯化、分离,从清远市电子废弃物拆解区污染土壤中得到4种耐性菌株,经菌落形态、扫描电镜分析以及16S rDNA技术鉴定得出,菌株HS-01、JH-02、YB-03、JY-04分别为海水芽孢八叠球菌（Sporosarcina aquimarina）、佐吕间湖生芽孢八叠球菌（Sporosarcina saromensis）、巨大芽孢杆菌（Bacillus megaterium）、甲基营养型芽孢杆菌（Bacillus methylotrophicus）。由生长特性实验得到,细菌HS-01与JY-04生长周期相同,在0～8 h为调整期,8～12 h为对数期,12～24 h为稳定期,24～32 h为衰亡期。而细菌JH-02与YB-03生长周期相同,在0～4 h为调整期,4～12 h为对数期,12～24 h为稳定期,24～32 h为衰亡期。细菌HS-01、JH-02、JY-04的最适温度与pH分别为30℃和8,而YB-03则为35℃与7.5。生物吸附实验结果显示,随着重金属离子质量浓度的升高,4种耐受细菌对重金属离子的吸附量也逐渐升高,但吸附量增长率以及吸附率却逐渐降低,这4种细菌对Cd2＋、Cu2＋、Pb2＋最大吸附量分别达到了2.25、2.05、2.28、2.25 mg,8.19、4.95、8.53、11.78 mg和10.84、10.59、7.66、9.02 mg。最大吸附率则分别达到了94.4、99.2、100、93.3%,86.1、90.8、88.6、87.3%和88.9、82.2、81.2、86.7%。其中细菌HS-01、YB-03、JY-04吸附Cd2＋能力较强,而细菌JY-04对Cu2＋以及HS-01、JH-02对Pb2＋吸附能力最强。上述结果显示了4种耐性细菌均具有较好的修复复合重金属污染水体的应用潜力,但对     

螯合剂和表面活性剂辅助金福菇修复重金属污染土壤

通过温室大棚盆栽试验,研究螯合剂和表面活性剂单独或复合处理辅助金福菇修复重金属污染土壤的效果.结果表明,单独添加EDTA(乙二胺四乙酸)时,高浓度的EDTA(E2,5 mmol kg-1)使金福菇的生物量比对照降低26%,子实体Pb、Cu和Cd的浓度分别比对照提高15～88倍、0.8～3.3倍和0.5～0.6倍.单独添加表面活性剂时,各处理生物量与对照没有显著差异,且重金属浓度变化幅度没有单独添加EDTA的处理大.低浓度的表面活性剂对金福菇吸收各种重金属的影响较小,而高浓度则影响较大,但与表面活性剂及重金属种类有关.共同添加EDTA和表面活性剂时,只有当EDTA和CTAB(溴化十六烷基三甲铵)共同添加时,EC2(EDTA:CTAB=1:1)和EC3(EDTA:CTAB=2:1)的生物量显著降低,其余处理与对照差异不明显.EC3的子实体Pb和Cu浓度达到所有处理中的最大值,分别为(1 533.61±131.34)、(1 786.11±328.33)mg kg-1.EDTA和SDS(十二烷基磺酸钠)浓度比为2:1(ES3)时,子实体Cd浓度达到最大值,为(50.56±11.55)mg kg-1.此外,还分析了不同处理的重金属总积累量和富集系数.结果显示,在螯合剂和表面活性剂辅助下,金福菇修复复合重金属污染土壤具有很大的潜能.     

羟基磷灰石对沉积物中重金属释放特性的影响

以羟基磷灰石掺杂前后模拟重金属污染沉积物为研究对象,利用混匀释放实验及化学连续萃取法分析沉积物中重金属的释放特征及形态分布特性,考察了羟基磷灰石对重会属污染沉积物中Cu、zn、Pb、Cd稳定性的影响.结果表明不同来源模拟污染沉积物中松花江沉积物中的重金属最易重新释放,而伊通河沉积物中的重金属释放量最小;同时伊通河沉积物中残渣态重金属的比例较其它沉积物高很多,而可交换态和碳酸盐结合态的重金属比例较其它沉积物低很多,说明同时进入沉积物中的重金属,伊通河沉积物中的重金属相对稳定一些.羟基磷灰石的掺杂不同程度降低了沉积物中重金属的释放能力,促使沉积物中的重金属由较不稳定结合态向较稳定结合态转化,减小了沉积物中重金属的生物可利用性,增强了重金属的稳定性.     

废弃铅锌冶炼厂重金属污染场地的健康风险评价

通过对广西某废弃铅锌冶炼厂区进行布点采样、监测分析,选取Cu、Pb、Zn、Cd、Cr、As六种重金属元素作为评价因子,对污染场地进行健康风险评价.结果显示,指数评价法表明厂区污染状况为废渣＞＞建筑垃圾＞土壤,Cd ＞Zn ＞As ＞Pb ＞Cu＞ Cr,土壤受到中度污染,废渣和建筑垃圾受到重度污染.健康风险评价法表明土壤、废渣和建筑垃圾的危害商分别为2.032、13.891、2.975,非致癌危害废渣＞＞建筑垃圾＞土壤;Cu、Zn、Cr、Cd、As的危害商分别为0.053、0.118、0.184、7.001、11.542,非致癌危害As ＞Cd ＞Cr＞Zn ＞Cu.土壤、废渣和建筑垃圾的致癌风险分别为5.387E-04、7.954E-04、2.455E-04,致癌危害废渣＞土壤＞建筑垃圾;As、Cd、Cr的致癌风险分别为5233E-04、2.400E-05、1.032E-03,致癌危害Cr＞As ＞Cd.综上,人体健康危害废渣＞建筑垃圾＞土壤,主要危害元素为As、Cd、Cr.     

蚯蚓对垃圾与底泥中镉的富集现象

通过蚯蚓处理垃圾及纳污河流底泥实验研究发现蚯蚓可选择吸收并富集垃圾及底泥中的镉，但对其他重金属元素铅、铜、锌等并无此种富集吸收现象。     

Electrochemistry: as cause and cure in water pollution—an overview

This article reviews both the pollution by the electrochemical industry and the use of electrochemistry to clean water. Main pollutants include Pd, Cd, Ni, Hg and other metals and cyanide as well as organic pollutants. The cause for water pollution by electrochemistry is due to the effluents from different electrochemical industries such as mercury from chlor-alkali industry; lead, cadmium and mercury from battery industry; heavy metals and organic contaminants from electroplating wastes; contaminants from corrosion processes; and persistent organic pollutants from the synthesis and use of pesticides, dyes and pharmaceuticals. Most pollutants can be successfully eliminated or converted to non-toxic materials by methods based on the electrochemical principles. Electrochemical depolluting methods are mainly electrodialysis, electrocoagulation, electroflotation, anodic processes, cathodic processes and electrochemical advanced oxidation processes.     

植物修复土壤重金属污染中外源物质的影响机制和应用研究进展

重金属进入土壤后难以被降解,并通过食物链在生物体内富集,长此以往会导致中毒、癌症、畸形、突变,严重影响了人类生产活动及地球生态系统的稳定。植物修复技术是一种经济有效的重金属污染修复技术,其依靠超富集植物强大的自身抗性机制,从土壤中提取或稳定重金属,达到污染治理的目的。然而修复土壤重金属污染的超富集植物通常生长缓慢、生物量低,其抗性机制也会受到植物本身对重金属胁迫的阈值限制,当胁迫超过这个阈值,植物修复的效率就会大大降低甚至失去修复功能。文章在解析植物重金属相互作用机制的基础上,综述了添加外源物质对重金属毒害植物的缓解效应以及其在强化植物修复土壤重金属污染中的应用研究进展;介绍了应用外源物质调控植物吸收转运重金属的3种途径,分别为提高土壤重金属生物利用度、促进植物生长以及增强植物耐性。提出了应用外源物质作为强化植物修复措施的潜力及今后的研究方向,其未来的研究应着重于以下方面:明确外源物质的应用浓度、时期、方式与植物吸收转运重金属之间的关系;从植物内源激素及信号分子间的互作、抗逆基因表达、内生及根际微生物等不同层面上揭示外源物质对植物积累重金属的调控机理;开展外源物质与其他植物修复强化技术的联合应用研究。这些研究可为土壤重金属污染的植物修复技术及其强化措施研究提供科学依据,同时也对植物修复工程技术的发展实践具有一定的指导意义。     

Effective remediation of organic-metal co-contaminated soil by enhanced electrokinetic-bioremediation process

• A new EK-BIO technology was developed to decontaminate e-waste contaminated soil. • Adding sodium citrate in electrolyte was a good choice for decontaminating the soil. • The system has good performance with low cost. This work investigates the influence of electrokinetic-bioremediation (EK-BIO) on remediating soil polluted by persistent organic pollutants (POPs) and heavy metals (mainly Cu, Pb and Ni), originated from electronic waste recycling activity. The results demonstrate that most of POPs and metals were removed from the soil. More than 60% of metals and 90% of POPs in the soil were removed after a 30-day EK-BIO remediation assisted by citrate. A citrate sodium concentration of 0.02 g/L was deemed to be suitable because higher citrate did not significantly improve treatment performance whereas increasing dosage consumption. Citrate increased soil electrical current and electroosmotic flow. After remediation, metal residues mainly existed in stable and low-toxic states, which could effectively lower the potential hazard of toxic metals to the surrounding environment and organisms. EK-BIO treatment influenced soil microbial counts, dehydrogenase activity and community structure.     

珠江三角洲地区典型菜地土壤与蔬菜重金属分布特征研究

通过对珠江三角洲地区的广州市、佛山市、江门市和惠州市典型菜地土壤和蔬菜中重金属（Pb、Cr、Cd、As和Hg）含量及其土壤中有效态（Pb、Cr、Cd）含量的调查,分析蔬菜重金属污染状况与土壤重金属含量的相关性,探讨了土壤重金属含量、有效态含量与土壤理化性质的相关性。结果表明,菜地土壤主要受Pb、Cd、Hg污染。Pb、Cd主要以轻度污染为主;而Hg污染在广州市菜地土壤以轻度污染和重度污染为主,佛山市菜地土壤以中度污染和重度污染为主,江门市和惠州市菜地土壤以轻度污染为主。蔬菜主要受Pb、Cd、Hg污染,少数蔬菜受到Cr污染,但并未检测出蔬菜受As污染。蔬菜中重金属含量与土壤中Pb、Cr、Cd的总量、有效态含量之间呈显著正相关关系,与土壤中As、Hg的总量无显著相关性。土壤中Pb、Cr含量与土壤有机质含量、黏粒含量、粉粒含量均达到显著相关。土壤中有效Pb与有效锰含量呈显著负相关关系,土壤中有效Cr含量与土壤粘粒含量、有效铁含量呈极显著正相关关系。     

贵、重金属的生物吸附

采矿业和工业废水中常含有大量的重金属离子 ,严重污染环境 ,危害人类健康 .因此 ,治理重金属污染的技术受到极大重视 .贵金属是指钌 (Ｒｕ)、铑 (Ｒｈ)、钯 (Ｐｄ)、银 (Ａｇ)、锇 (Ｏｓ)、铱(Ｉｒ)、铂 (Ｐｔ)、金 (Ａｕ)等 8种金属 ,由于其特殊性能 ,广泛应用于航天航空、电子和石油化工等工业 .随着工业的发展 ,贵金属的应用愈加广泛 ,但贵金属资源稀少 ,冶炼困难 .因此 ,从含贵金属的废料、废液和废水等“二次资源”中回收贵金属具有重要的经济和社会意义 .从废液、废水中去除重金属或回收贵金属 ,传统的方法有化学沉淀法、电解法、离…     

甘肃某冶炼厂区土壤重金属铅、镉污染特征及其对微生物群落结构的影响

长期受到重金属铅(Pb)和镉(Cd)污染的土壤生态危害指数较高,土壤微生物群落结构容易受到重金属的影响,重金属对土壤微生物的毒性与重金属的生物利用度直接相关。以白银市重金属污染土壤为样本,分析了土壤的理化性质、重金属Pb和Cd的污染状况及土壤微生物群落结构,探究它们之间的关联性。样本采自距离污染中心由近及远的4个位置(分别命名为S1、S2、S3和S4)。采用Hakanson指数法来评估该地重金属生态风险;选用改进的BCR顺序提取法分析Pb与Cd的组分分布情况;利用SPSS和Canoco 4.5对土壤性质、重金属和细菌群落进行相关性分析和冗余分析,探究微生物群落结构与土壤性质和重金属污染之间的相关性。结果表明:白银市该处重金属污染场地3 km以内的土壤均受到严重的Pb、Cd污染。Pb主要以弱酸可提取态和可还原态的形式存在于土壤中,Cd则以弱酸可提取态为主;土壤重金属的危害生态指数均已经达到极高污染风险程度,且危害程度S1>S3>S2>S4;微生物丰度和多样性可能受到土壤性质及重金属的共同影响,与Pb、Cd的污染程度大致呈负相关(S2相似文献   

土地利用/覆被变化（LUCC）与土壤重金属积累的关系研究进展（Research Review of the Relationship between Land Use/Cover Change and Heavy Metal Accumulation in Soil）

土壤重金属污染是世界性环境问题之一.土地利用/覆被变化(LUCC)是最主要的环境演变驱动因子之一.为明晰LUCC对土壤重金属积累和污染的影响,根据前人研究,从场地、县域和流域/区域尺度总结了LUCC和土壤重金属污染的关系.研究发现,三个尺度上土地利用方式和覆被类型/格局是控制土壤重金属空间积累和分布的重要因子,土地利用/覆被可以直接吸纳或吸附重金属,亦能通过改变土壤物理、化学和生物性质从而控制重金属在土壤中的移动性和活性,造成土壤中重金属的积累直至污染.此外,论文阐明了LUCC在土壤重金属污染风险预测、规避和污染土壤修复中的重要作用,最后提出了在实践中通过调整土地利用/覆被类型进行污染土壤修复的建议.寓景观生态学思想于土壤重金属污染防治过程是一种新的有效途径.     

Accumulation of lead, cadmium and chromium in some plants cultivated along the bank of river Ribila at Odo-nla area of Ikorodu, Lagos state, Nigeria

Heavy metal in soil samples and in washed and unwashed samples of Telfaria occidentalis (ugwu) and Talinum triangulare (waterleaf) cultivated on the bank of river Ribila in Odo-nla village were determined. The soil was moderately polluted with cadmium when compared with Federal Environmental Protection Agency standards. The difference between the unwashed and washed plant samples revealed that metal pollutants exist as superficial contaminants on the foliage surface which is the edible portion and if the foliage portion is washed thoroughly it may be safe for dietary consumption. There is no doubt that continuous discharge of effluent and gaseous emissions from the industries located in this area and dumping of domestic wastes into the river may lead to higher concentrations of these heavy metals in the soil and in the tissue of the leafy vegetables cultivated on the river bank over time. This can eventually lead to pollution of the soil and the cultivated plants, which are ready source of food for the people and other organisms in the food chain.