Study Progress in Remediation of Soil Contaminated by Heavy Metals and Its Application Prospect

Flax is an ideal crop for remedying soil contaminated by heavy metals. It has high tolerance to heavy metals and strong adsorption to heavy metals. Through properly using or adjusting external conditions such as regulator, moisture, fertilizer, microorganisms, and pH value, it is able to improve ability of flax to absorb, trans- fer, and accumulate heavy metals. To improve the ability of flax in remediating heavy metal contaminated soil, it is recommended to strengthen cultivation of flax varieties and screening of germplasm resources, actively carry out studies on tech- nologies of fax remedying heavy metal contaminated soil, implement large-scale and mechanized planting of flax, and promote control of heavy metal contaminated soil.

Comparative Study of the Efficacy of Metal Removal from Contaminated Aqueous Solutions by Solid Bidentate Ligands&Liquid Plant Materials

Heavy metal contaminated water sources pose serious health risks for humans,animals,and plants.Exposure to and ingestion of heavy metals have been associated to liver,kidney,and brain function.Objective:The aim of this research is to comparatively examine the metal removal efficacy of three solid bidentate chemicals and four plant materials.Study Design&Methods:Standard solutions of zinc(II)and lead(II)ions with concentrations of 1,000 ppm were respectively treated with OA(Oxalic Acid),dibasic bidentate ligands(sodium hydrogen phosphate and sodium carbonate).Then,the solutions were placed on a shaker for 15 h,centrifuged,and the supernatant was analyzed using ICP-AES(Inductively Coupled Plasma-Atomic Emission Spectrometry).Results:All the solid bidentate adsorbents were very effective in removing zinc and lead(>90%).However,more lead than zinc was removed across all adsorbents except for lemon where equal percent of zinc and lead(49%)were removed.OA and Na2HPO4 removed about equal amount of lead(>99%).The plant materials(SP(Spinach),bell pepper and GBP(Green Bell Pepper)),respectively and preferentially removed more lead(98.9%,98.3%,81.5%)than zinc(91.7%,46%,46%).Conclusion:Although plant materials have gained attraction for the remediation of heavy metal,however,some bidentate chemical ligands such as OA,sodium carbonate and sodium hydrogen phosphates are even more effective in removing these metals from contaminated water.Furthermore,heavier metals are preferentially removed than lighter metals.

Effects of Red Mud on the Remediation of Pb, Zn and Cd in Heavy Metal Contaminated Paddy Soil

[Objective] To study the remediation efficiency of red mud on Pb, Zn and Cd in the heavy metal contaminated paddy soil of mine area, to clarify its remediation mechanism and fertilizer efficiency on heavy metal contaminated soil. [Method] The soil incubation experiment was conducted to study the effect of red mud on the pH values and electrical conductivity （EC）, and the remediation efficiency of red mud on lead （Pb）, zinc （Zn） and cadmium （Cd） in heavy metal contaminated soil. [Result] Red mud addition reduced the content of exchangeable Pb, Zn and Cd in the soil significantly. Compared with the control, when incubated for 30, 60 and 90 d with the red mud dosage of 4% （W/W）, the exchangeable Pb content was decreased by 39.25%, 41.38% and 50.19%; exchangeable Zn content was decreased by 49.26%, 57.32% and 47.16%; and exchangeable Cd content was decreased by 19.53%, 24.06% and 25.70%, respectively. The application of red mud had significant impact on the share of Pb, Zn and Cd contents in five forms, and different amounts of red mud application all reduced the proportion of exchangeable Pb, Zn and Cd to the total Pb, Zn and Cd. In addition, the proportion of exchangeable Pb, Zn and Cd to total Pb, Zn and Cd decreased with the increasing amount of red mud addition. [Conclusion] The study provided references for reasonable application of red mud and reduction of heavy metal pollution in paddy soil.

Removal of heavy metals from a contaminated soilusing tartaric acid

This study reports the feasibility of remediation of a heavy metal （HM） contaminated soil using tartaric acid, an environmentally-friendly extractant. Batch experiments were performed to test the factors influencing remediation of the HM contaminated soil. An empirical model was employed to describe the kinetics of riM dissolution/desorption and to predict equilibrium concentrations of HMs in soil leachate. The changes of HMs in different fractions before and after tartaric acid treatment were also investigated. Tartaric acid solution containing HMs was regenerated by chestnut shells. Results show that utilization of tartaric acid was effective for removal of riMs from the contaminated soil, attaining 50%-60% of Cd, 40%-50% of Pb, 40%-50% of Cu and 20%-30% of Zn in the pH range of 3.5-4.0 within 24 h. Mass transfer coefficients for cadmium （Cd） and lead （Pb） were much higher than those for copper （Cu） and zinc （Zn）. Sequential fractionations of treated and untreated soil samples showed that tartaric acid was effective in removing the exchangeable, carbonate fractions of Cd, Zn and Cu from the contaminated soil. The contents of Pb and Cu in Fe-Mn oxide fraciton were also significantly decreased by tartaric acid treatment. One hundred milliliters of tartaric acid solution containing HMs could be regenerated by 10 g chestnut shells in a batch reactor. Such a remediation procedure indicated that tartaric acid is a promising agent for remediation of HM contaminated soils. However, further research is needed before the method can be practically used for in situ remediation of contaminated sites.

Heavy Metal Contamination in Farmland Soil and Bioremediation Measures: A Case Study of the Mining Area in Shaoguan

With the rapid development of mining,the soil heavy metal contamination is increasingly serious in Shaoguan,directly affecting the production of crops. This paper analyzes the farmland soil heavy metal contamination in the mining area of Shaoguan and the causes of heavy metal contamination in recent years,brings forward the bioremediation measures to control soil heavy metal contamination,and points out the development direction of bioremediation in farmland soil heavy metal contamination in the mining area.

Lead Remediation of Contaminated Water by Charcoal, LA Red Clay, Spinach, and Mustard Green

Lead is a toxic and naturally occurring substance with documented neurotoxin, toxic, and long-lasting adverse health effects globally. Lead exposure can cause impaired physical and mental development in children. Exposure to high lead levels affects the intestinal tract, kidneys, joints and reproductive system in adults. This study evaluates the removal of 1500 PPM of lead from contaminated aqueous solution using Celite, Louisiana Red Clay, Charcoal, and supernatants from aqueous extracts of Mustard Green (Brassica juncea), and Spinach (Spinacea oleracea). After shaking triplicate reaction mixtures for each substrate for 22 hours at room temperature, lead removal by the five substrates were analyzed by EPA Method 6010, using Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES). Results suggest that the order of lead removal is Spinach (98%) > Charcoal (96%) > LA Red Clay (88%) > Mustard Green (87%) > Celite (4%). The study concludes that liquid substrates such as the supernatants from pureed spinach and mustard green can effectively remove lead from contaminated water.

An Evaluation of Edible Plant Extracts for the Phytoremediation of Lead Contaminated Water

There is a growing global concern for the environmental and health hazards posed by heavy metal contaminants, especially lead in the soil and ground water. The potential for plant and animal uptake, metabolism, and propagation into food-chain poses great health risks. World communities face a common need to a cheap, efficient, and effective technology to mitigate the growing problem of heavy metal contaminations. The present investigation was undertaken to evaluate the potential of using aqueous extracts of edible vegetables and fruits for the in-situ remediation of lead contaminated water (1300 PPM). The plants used in this study include Mustard Green (Brassica juncea), Spinach (Spinacea oleracea), Collard Green (Brassica Oleracea), Bitter leaf (Vernonia Amygdalina), Carrot (Daucus Carota Sativus), Red, Green, and Yellow Bell Pepper (Capsicum Annuum ), tomatoes (Lycopersicon esculentum), red and white grape (Vitis vinifera), and lime (Citrus aurantifolia). After shaking triplicate reaction mixtures lead contaminated water with each substrate for 22 hours at room temperature, lead removal by the substrates were analyzed by EPA Method 6010, using Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES). Results suggest that the order of lead removal is Collard Green (99.8%) >, Spinach (98.7%) > Mustard Green (98.2%) > Green Bell Pepper (97.8%) > Yellow Bell Pepper (97.75%) > White Grape (96.7%)> Carrot (95.5%) > Red Bell Pepper (94.28%) > Red Grape > 93.5% > Tomatoes (84%) > Bitter Leaf (61%). The study concludes that liquid substrates such as the supernatants from pureed edible tuberous, leafy, and fruity vegetables can effectively remove lead from contaminated water.

Remediation Technology for Combined Pollution of Lead and Cadmium in Farmland Soil

At present,the problem of heavy metal pollution in farmland in southern China is serious. Especially,the cadmium and lead are two heavy metal elements with serious pollution and great harm to human body. This paper reviewed some common methods and materials used in the control of cadmium and lead pollution in farmland soil. Then,it discussed the problems in the repair of cadmium and lead pollution in farmland soil. It came up with the future research direction,to provide references for remediation of lead and cadmium pollution in farmland soil.

Comparative Study of Lead Removal by Extracts of Spinach, Coffee, and Tea

The use of tea and coffee for the removal of heavy metal from aqueous lead solutions has been reported. However, those studies were limited to expended dry biomass of coffee and tea and the lead concentration in those studies range from 10 - 100 ppm of aqueous lead solution. This study compared the effectiveness of aqueous extracts of instant coffee (IC), coffee ground (CG), coffee bean (CB), Lipton tea (Tea), and spinach puree (SP) in removing lead from 1300 PPM of aqueous lead solution. After 24 hr of agitation at room temperature followed by centrifugation, the lead concentration (in ppm) in the liquid from each reaction tube was analyzed using EPA Method 6010 (Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES)). The results suggest that the order of lead removal was Spinach (99%) > Instant coffee (95%) >Tea (91%), > CG (62%) > CB (59%). In comparing the brewed versus the boiled extracts, the results demonstrated that temperature of the aqueous extract affected the lead removal potential of coffee and tea in decreasing order: IC (95%:79%), > Tea (91%:88%) > CG (62%:53%) > CB (59%:53%).

Selection of Sugar Cane Varieties with a Low Heavy Metal Accumulation Ability for the Ecological Remediation of Contaminated Farmland

How to best use farmland contaminated with low to moderate levels of heavy metals remains a challenge in many parts of the world. Here, we screened sugar cane varieties to identify those with a low ability to accumulate heavy metals and with high tolerance. These trials were conducted in arsenic （As）, lead （Pb） and Cadmium （Cd） contaminated farmland in Huanjiang County, Guangxi Zhuang Autonomous Region, China. We tested seven varieties and found that cultivar Guiyin9 had the highest cane stem yield （187.5t ha-1 ） and sugar content （27t ha-1 ）. The concentrations of As, Pb and Cd in the cane juice of Guiyin9 were all below the maximum limit for contaminants in food. Because Guiyin9 showed low accumulation of the heavy metals tested here and produced a high cane stem yield, this cultivar could be planted as a valuable crop in large areas of southern China contaminated with low to moderate levels of heavy metals.

重金属-PAHs污染土壤植物微生物修复效果及机理

针对焦化厂等土壤中铬(Cr)、砷(As)重(类)金属和菲(Phe)、苯并[a]芘(BaP)等多环芳烃(PAHs)风险高、绿色低碳修复技术缺乏等突出问题,以黑麦草-玉米-食醚红球菌(Rhodococcus aetherivorans,BW2)开展植物微生物联合。结果表明,63 d后植物微生物联合修复组土壤中Cr、As、Phe和BaP浓度分别下降9.63%、5.28%、45.14%和26.87%,其中重金属的去除主要依赖于植物作用,而PAHs去除则在很大程度上取决于微生物与植物的共同作用;植物主要吸收可提取态重金属,63 d后不同修复组土壤中可交换态Cr平均下降2.19%,而As则由于降解作用使修复过程中可交换态增加;可交换态Cr和碳酸盐结合态Cr与土壤中放线菌门呈强正相关,2种形态As则与拟杆菌门、装甲菌门、FBP菌门和浮霉菌门呈正相关。污染物去除效率间存在明显的相互作用,同时受酶活性和不同功能微生物丰度的动态影响,反之土壤微生物群落结构和功能也在土壤污染物种类、浓度及理化性质等综合作用下发生改变。

Evaluation of remediation process with soapberry derived saponin for removal of heavy metals from contaminated soils in Hai-Pu, Taiwan

The use of a biodegradable natural plant-based surfactant extracted from soapberry is proposed for the remediation of Ni, Cr and Mn from industrial soil site in Hai-Pu, Taiwan. Batch experiments were performed under variation of fundamental factors （saponin concentration, pH, and incubation time） for metal remediation. Removal of Ni and Mn were increased with increasing saponin concentration （0.015-0.150 g/L）, whereas the removal of Cr was increased upto 0.075 g/L saponin. The Ni, Cr and Mn were removed significantly （p 〈 0.05） at near to the neutral and slightly acidic （pH 5 to 8） conditions. Removal efficiency of Ni （99%） from the soil was found to be greater than that of Cr （73%） or Mn （25%） in the presence of saponin at a concentration of 0.150 g/L at pH 5. The removal percentage increased with incubation time where the removal of Ni was faster than that of Cr and Mn. The result indicates the feasibility of cco-friendly removal of heavy metal （Ni, Cr and Mn） from industrial soil by soil washing process in presence of plant derived saponin.

煤矿矿区土壤重金属及多环芳烃污染治理修复技术综述

土壤重金属和有机物污染是当前许多煤矿矿区及周边地区面临的严重问题,威胁居民健康,要采取有效措施予以解决。在对煤矿矿区周边土壤重金属和多环芳烃(PAHs)来源及危害分析的基础上,发现重金属元素在自然条件下难以降解,导致其在生物体中累积,并且PAHs具有致癌性、致畸性和诱变性。通过比较物理化学修复、植物修复和生物修复等方法在治理重金属及PAHs污染土壤的优缺点,发现植物修复和生物修复对气候和环境的依赖程度高,物理修复成本和能耗较高,因此提出矿区周边土壤污染的修复技术需要进一步创新,实现多领域、多学科协作发展的观点。通过持续的技术创新和多种修复方法的联合应用,达到有效治理煤矿矿区及周边重金属和PAHs污染的目的,实现土壤的重新利用,进而实现环境保护与经济可持续发展的良性互动。

天然矿物修复剂筛选及其对镉固持性能研究

对湖南省14个产地、4类矿物材料的镉固持性能进行对比,优选出4种天然高效镉修复材料(宁乡县喻家坳的石灰石、湘潭县楠木冲的低品位锰矿石、桃源县马宗岭的膨润土和石门县新岗的海泡石)。4种天然矿物材料对镉的固持动力学速率从快到慢排序为:膨润土>石灰石>海泡石>锰矿石。各矿物材料对镉的吸附量随着镉初始质量浓度增大而增大,镉质量浓度不高于10.0 mg/L时,各矿物材料对镉的吸附量从大到小排序为:石灰石>膨润土>锰矿石>海泡石;镉质量浓度高于10.0 mg/L时,各矿物材料对镉的吸附量从大到小排序为:膨润土>石灰石>锰矿石>海泡石。吸附行为均符合Langmuir吸附模型,膨润土、石灰石、锰矿石、海泡石对镉的最大吸附容量分别为29.38、14.51、9.67、5.27 mg/g。溶液pH=6~9时,各矿物材料对镉的去除效率排序为:石灰石>膨润土>锰矿石>海泡石。天然矿物材料对镉的固持效果与矿物的化学组分、初始镉质量浓度、pH值有关。

重金属污染土壤修复方法及资源化利用途径分析

面对土壤重金属污染问题,迫切需要采取措施来修复重金属污染土壤并将其资源化。通过文献调研,旨在阐明我国目前土壤重金属污染的状况,阐述了重金属污染土壤常见的修复方法,包括物理修复、化学修复、生物修复和联合修复等;并在此基础上,分析了目前重金属污染土壤资源化利用主要方向为土壤化利用、建材化处理及路基填筑,针对当前研究存在的问题提出建议,并对未来研究方向进行展望。

冀北花岗岩地区坡积冲洪积型污染耕地土壤治理比较研究

土壤是农业生态系统重要的组成部分,耕地土壤重金属污染会影响农产品质量安全。本研究选取冀北花岗岩地区坡积物母质区和冲洪积物母质区的弱酸性农田土壤为研究对象,依托钝化修复和植物提取(玉米和龙葵为植物修复材料)两种修复技术,探究了不同成土母质类型和修复技术对耕地土壤重金属的修复效果影响。研究结果表明:(1)坡积物和冲洪积物母质区土壤的有机质、速效钾、有效磷和pH值存在显著差异,坡积物母质区土壤pH显著低于冲洪积物母质区土壤,两区成土母质均具有较高的Pb背景值;(2)钝化修复后,冲洪积物母质区玉米籽粒Cd和Pb含量显著降低,玉米籽粒增产19.10%~33.00%,较坡积物母质区显示出更好的修复效果;(3)坡积物母质区采用龙葵和玉米间作模式,植物修复每年每公顷中提取Cd、Pb和Cu分别为167.25、208.35和555.05 g,Cd、Pb和Cu的去除率分别为2.727%、0.043%和0.234%,较冲洪积物母质区显示出更好的修复效果;(4)龙葵和玉米的间作模式优于单一种植模式,间作可以提高土壤中重金属的生物可利用性和植物吸收效率;(5)制定土壤污染修复策略时,需考虑土壤特性、成土母质及不同农作物的影响,选用合适的修复技术和种植模式。本研究可为地质异常区域农田土壤安全利用与修复提供参考依据。

植物-电动耦合修复重金属污染土的效能及其强化机制

重金属污染土壤的净化效果直接影响修复后土体的再利用。以Cd、Cu、Ni、Zn、Pb污染土壤为研究对象,采用改进环绕式电极布置,以植物-电动耦合修复下土壤的净化度及土壤性质为重点,厘清关键因素,揭示耦合强化修复机制。结果表明:植物-电动耦合修复下不同重金属的去除率均较单一修复有所提高,重金属赋存形态及植物对重金属的响应是影响修复效果的关键因素。改进环绕式电场的施加能积极调动更大范围土壤中的重金属向植物根系迁移聚集,解决了植物修复中重金属可及性和生物活性低的问题;植物修复的协助有利于改善电动修复对土壤性质的不利影响,解决聚焦效应和高能耗问题。植物-电动耦合修复联合了重金属的空间分布改善、重金属生物利用度提升、植物生长代谢强化及土壤微生物生命活动调节等作用机制,有效提高了重金属污染土壤的净化度,修复后土体可维持稳定的pH值(6.27~7.91)、电导率(108~159μs/cm)及低能耗(13.76~18.81 kW·h/m3),有助于推进污染土壤的可持续利用。

复合菌群去除石油类污染物研究进展

以微生物群落的结构特征为依据,综述了复合菌群技术去除油污染的研究现状。提出特异性纯培养菌群已逐步发展成新的研究方向,其结构设计应建立在对天然菌群作用机制的认知上,以微生物间的效应关系以及底物特征为依据,针对性构建具有协同效应的外源菌群。随着对复合菌群技术认识的不断深入,外源菌群强化修复技术将得到长足发展。

生物有机肥对土壤镉形态及玉米镉积累的影响

为探究生物有机肥治理镉污染土壤的可行性及对土壤重金属污染修复的效果,采集河南省淅川县2种镉污染土壤,分别设置6种施肥处理:CK(不施用任何物料)、NPK(常规施NPK肥)、NPK+0.5%OF(常规施肥+0.5%商品有机肥)、NPK+1%OF(NPK+1%商品有机肥)、NPK+0.5%BF(NPK+0.5%生物有机肥)和NPK+1%BF(NPK+1%生物有机肥),测定种植前后土壤全镉含量、土壤各化学形态镉、玉米植株根系及籽粒镉含量。结果显示,以添加1%生物有机肥的治理效果最佳,NPK+1%BF处理下2种土壤有效态镉含量相较于NPK+1%OF降幅分别为19.74%、7.09%;施用有机物料降低土壤弱酸提取态镉含量,提高残渣态镉含量,NPK+1.0%BF弱酸提取态镉含量相比CK下降11%、残渣态镉上升16%;施用有机物料各处理玉米植株根系、籽粒镉含量显著降低,以NPK+1.0%BF处理效果最佳,相比NPK处理,土壤Ⅰ的玉米根系、籽粒镉含量降幅达34.41%、31.59%。综上,在镉污染土壤中施用生物有机肥,可显著降低土壤有效态镉含量,促进土壤弱酸提取态镉向残渣态镉转化,降低镉危害;玉米根系及籽粒镉含量均显著下降,综合治理效果表现为生物有机肥优于商品有机肥。