场地土壤中有效态砷的稳定化处理及机理研究

分别以生石灰和亚铁盐作为辅助剂与稳定剂对2种砷污染的土壤进行稳定化处理,通过化学浸出、形态及结构研究,揭示土壤中有效砷的稳定效率和机理.结果表明,外源铁添加量与土壤砷含量(Fe/As)的物质的量比达到6:1~8:1,CaO投加比例为0.05%~0.1%(w/w)时,土壤中有效态砷的稳定效率超过85%.土壤有效砷的稳定化处理主要是将砷从非专性吸附态和专性吸附态转化为弱结晶的铁铝或铁锰水化氧化物结合态、结晶铁铝或铁锰水化氧化物结合态.稳定处理后2种污染土均有新物相羟砷铜矿(As2Cu5H4O12)生成.     

Sonochemical treatment of simulated soil contaminated with diesel

Sonochemical treatment has previously been shown to be an effective method to remediate soils contaminated with hydrocarbons. Ultrasonically induced desorption of the contaminants is based on the mechanisms of physical breakage of bonds by hot spots, quartz particle surface impingement, the fragmentation of long-chain hydrocarbons by microjets, as well as microstreaming generated by acoustic vortices in the media pores. In this investigation the effect of factors such as: slurry concentration; ultrasonic power intensity; duration of irradiation; particle size; diesel content; slurry pH; salinity; and surfactant concentrations on the desorption of diesel from quartz, is considered. A multistage sonochemical treatment process for the remediation of sand contaminated with diesel is consequently proposed and it is shown that this approach is more effective than high-speed mechanical agitation.     

油污土壤堆制处理实验研究

堆制处理工艺是处理油污土壤的一种强化的生物处理工艺 .通过实验室实验 ,结果表明 :原油降解菌剂投加量 6× 10 12个 (CFU) kg(土壤 )、营养物投加量为使土壤中C∶N∶P =10 0∶2 5∶0 2 5、土壤含水量为饱和含水量的 30 %— 70 %、通风量 14 0mL s为适宜处理条件 ,此时 ,处理 2个月 ,油去除率在 5 0 %以上 .在油污土壤中添加的降解菌和营养物种类、数量完全相同时 ,堆制处理效率明显高于生物耕翻处理效率 ;在相同处理时间内 ,堆制处理时油去除率可比生物耕翻处理时提高 10 %以上 .在处理过程中 ,原油中大部分饱和烃和芳香烃组份被降解     

水稻秸秆生物炭对镉、铅复合污染土壤中重金属形态转化的短期影响

用生物炭修复重金属污染土壤已有广泛研究.本文采用水稻秸秆在500℃下制成的生物炭,施入Pb、Cd复合污染的土壤中培养30 d,探讨重金属化学形态变化,以期为生物炭修复重金属污染土壤提供科学依据.结果表明:生物炭添加后,黄棕壤的pH升高,弱酸提取态、可还原态及可氧化态Pb含量降低,残渣态Pb含量极显著增加,土壤Pb活性降低;与未加生物炭处理相比,添加生物炭后高浓度Cd污染土壤中弱酸提取态Cd含量极显著降低,可氧化态Cd含量增加,而残渣态Cd含量变化不显著,表明添加生物炭可以促进弱酸提取态Cd向可氧化态Cd转化.Pb、Cd复合污染土壤中Pb-Cd交互作用极显著,添加生物炭减弱了交互作用对弱酸提取态Pb的影响.     

吸附材料对钒矿污染土壤重金属的稳定化效果

选用壳聚糖和活性炭两种吸附材料,分别以不同的质量比添加到供试土壤中,固化后进行毒性浸出实验,研究吸附材料对土壤中钒(V)、铬(Cr)的稳定化效果,并通过表征吸附材料的红外光谱(FTIR)和X射线光电子能谱(XPS)探究吸附材料对V、Cr的稳定化机理.结果表明,壳聚糖对V、Cr均有较好的稳定化效果,活性炭对V的稳定化效果不稳定,对Cr的稳定化效果很好.吸附材料添加量的改变对稳定化效果影响不大.稳定化30d时,0.5%壳聚糖对V、Cr的稳定化率分别为74.04%、46.77%;0.5%活性炭对V、Cr的稳定化率分别为1.86%、87.75%.FTIR和XPS表征结果表明,壳聚糖中含活性强的氨基和羟基较多,活性炭中含氨基、羟基较少.因此壳聚糖和活性炭可作为土壤重金属的稳定剂,使钒矿污染土壤得到修复.     

砷污染场地土壤的稳定化技术工程应用研究

基于3种砷污染水平的场地土壤(WSL、WSX及FZ)进行稳定化小试试验,比较Fe^Ⅱ/Mg复配型(F2M)、Ca/Fe复配型(CF)及MetaPro^©-ani(As)系列修复材料(MPA)对土壤中砷污染的稳定化效果,进一步分析了修复材料用量对稳定化效果的影响,并选择稳定化效果较优的材料进行工程化施工验证(基于FZS土壤样品),WSL、WSX、FZ及FZS土壤样品的砷污染程度依次为FZ>FZS>WSX>WSL。结果表明:对于低/中浓度砷污染土壤样品WSL和WSX,F2M和CF复配型修复材料在较低投加比条件下可达到较好的稳定化效果;对于高浓度砷污染土壤样品FZ,MPA系列修复材料的稳定化效果明显优于前2种复配型修复材料;对于高浓度砷污染土壤实际施工样品FZS,MPA系列修复材料在开放性施工条件下,可达到较理想的稳定化效果,其中,以MPA-Ⅰ型材料修复效果最佳。     

上海浦东某氯代烃场地地下水污染现状调查

氯代烃曾经广泛用作工业清洗剂,由于过度使用和储存不当,造成严重的土壤和地下水污染.本研究选取上海浦东某1,1,1-三氯乙烷(1,1,1-TCA)污染场地作为研究对象,连续5年观测了75个监测井的地下水样品氯代烃分布.采用吹扫捕集和气相色谱联用法检测了地下水样品中氯代烃的种类和浓度,运用GMS软件构建了污染场地水文地质模型和氯代烃污染羽分布图.结果表明,氯代烃污染羽主要分布在5个区域,面积达5000 m2左右,深度主要在地下4~8 m的粘土层中,污染土壤和地下水总量为50000 m3左右;2号区域的污染情况最为严重,氯代烃浓度范围为10~1700 mg·L~(-1),发现50 m3左右的自由相(DNAPL).研究结果将为揭示该场地污染物迁移转化规律,为后续的人体健康风险评估和制定修复方案提供数据支撑.     

Fenton氧化处理爆炸物污染土壤的实验研究

采用摇瓶和玻璃柱试验考察了Fenton氧化处理爆炸物污染土壤中2,4-DNT、2,6-DNT以及COD等的去除效果及其最佳参数.当3%H2O2投加量达到26.46mmol、FeSO4和H2O2的物质的量之比约为1∶73.56时,2,4-DNT和2,6-DNT均可被完全氧化,COD去除率可达到87%.对于2,4-DNT和2,6-DNT,反应时间只需要2h,但要同时去除其它芳香族硝基化合物,则反应时间需要超过8h.土壤直接Fenton氧化的效果并不理想,而对洗出液进行Fenton氧化可以取得很好的效果.通过反应动力学分析和丙酮抑制试验得出,2,4-DNT比2,6-DNT容易氧化.GC-MS分析结果表明,不仅土壤中的2,4-DNT、2,6-DNT可被氧化,其它的硝基芳香族有机化合物也可被氧化去除.     

热处理修复方式对污染土壤性质及生态功能的影响

因为具有良好的处理效果和较短的施工周期,热处理是目前污染场地修复领域应用的热点技术之一,厘清热处理对土壤性质及功能的综合影响对于评价土壤价值具有重要意义。在分析了大量相关研究与应用案例的基础上,总结了热处理修复技术对土壤有机质、pH、营养组分等理化性质的影响,阐述了热处理对土壤微生物、动物以及植物的生态影响,分析了热处理过程对土壤污染物的衍生物产生以及复合污染修复效果的影响,探讨了热处理对土壤的综合影响及其对实际修复工程的指导意义,并对未来热处理在污染场地修复应用中的研究重点和方向提出了展望。     

复合材料对砷污染土壤稳定化处理及机理研究

通过投加FeS、电石渣、菌渣及其复配组合对砷污染土壤进行稳定化处理,根据稳定效率对稳定材料进行筛选,并分析处理前后土壤中砷的生物有效性、赋存形态及土壤物相成分,探索稳定机理.结果表明:单因素实验中,FeS对砷的稳定效率最高,当FeS投加量为n(Fe)/n(As)=20时,砷的稳定效率达84.69%;复配实验中,FeS投加量为n(Fe)/n(As)=15,电石渣投加量为0.5%(质量分数),菌渣投加量为6%(质量分数)时,砷的稳定效率高达90.53%.机理研究表明:稳定处理后,土壤中有效态砷和有机体内砷的可给量分别降低80.14%和92.86%;土壤中易溶态砷占总砷的比例降低了18.61%,铁型砷和钙型砷占总砷的比例分别提高了10.36%和5.81%,易溶态砷主要转化为铁型砷和钙型砷;稳定处理后土壤中矿物成分新增了Ca Al_2Si_2O_8·4H_2O(斜方钙沸石)、Ca_3Fe_4(AsO_4)_4(OH)_6·3H_2O(菱砷铁矿)、Fe_2(AsO_4)(SO_4)OH·5H_2O(砷铁矾矿)、(Al,Fe~(3+))_3AsO_4(OH)_6·5H_2O(砷铁铝矿)4种矿物,稳定处理使土壤中的砷生成了难溶性铁-砷、钙-砷矿物质.     

Ecological compensation mechanism for urban green land and its application in Shanghai,China

Urban green land compensation plays an important role in county development, ecological environment management and many other fields. The concept, methods and principles of urban green land are introduced in this paper. According to the pay fee method, the value and ecological function of various types of urban green land were analyzed. The cost-benefit analysis method (CBAM) was used to estimate different external diseconomy benefits caused by green land loss. The authors applied CBAM to estimate such benefits in the case of Shanghai, China, and calculated the actual compensation value for green land. Results indicated that in 2002, the compensation value for the green land of Shanghai was RMB 8.58 × 10⁵ Yuan/hm². Translated from Urban Environment & Urban Ecology, 2006, 19(3): 4–6, 11 [译自: 城市环境与城市生态]     

受多氯代有机化合物污染土壤的植物修复初探

采用种植植物的方法,对受以HCB、pp'-DDT及γ-BHC为代表的PCOPs污染土壤的植物修复进行了初步研究.结果表明,种植黑麦草和大蒜都能不同程度降低土壤中PCOPs的含量,0～60 d时下降速率较快,60 d后下降速率减慢.植物修复能力的大小与植物种类、生育时期以及土壤受PCOPs的污染程度有关:黑麦草对受PCOPs污染土壤的修复能力略优于大蒜;在植物生育过程的前期和中期(0～60d),植物对PCOPs的吸收能力较强;对受较高浓度PCOPs污染的土壤,植物修复能力相对较强.土壤中的过氧化氢酶活性、pH值和有机质含量初步反映了土壤生物的变化情况,种植植物能促进土壤生物对PCOPs的吸收和利用.受污染土壤中减少的PCOPs有1.11%～10.25%被植物直接吸收,其它则可能是由于植物降解或种植植物后土壤环境的改变导致PCOPs被微生物降解.     

Eco-toxicity of petroleum hydrocarbon contaminated soil

Total petroleum hydrocarbons (TPH) contaminated soil samples were collected from Shengli Oilfield of China. Toxicity analysis was carried out based on earthworm acute toxicity, plant growth experiment and luminescent bacteria test. The soil was contaminated bypetroleum hydrogcarbons with TPH concentration of 10.57%. With lethal and sub-lethal rate as endpoint, earthworm test showed that the LD50 (lethal dose 50%) values in 4 and 7 days were 1.45% and 1.37% respectively, and the inhibition rate of earthworm body weight increased with higher oil concentration. TPH pollution in the soil inhibited seed germination in both wheat and maize experiment when the concentration of petroleum was higher than 0.1%. The EC50 (e ective concentration 50%) for germination is 3.04% and 2.86% in maize and wheat, respectively. While lower value of EC50 for root elongation was to be 1.11% and 1.64% in maize and wheat, respectively, suggesting higher sensitivity of root elongation on petroleum contamination in the soil. The EC50 value in luminescent bacteria test was 0.47% for petroleum in the contaminated soil. From the experiment result, it was concluded that TPH content of 1.5% is considered to be a critical value for plant growth and living of earthworm and 0.5% will a ect the activity of luminescent bacteria.     

焦化厂PAHs污染土壤中微生物群落多样性特征

土壤中微生物在多环芳烃(PAHs)的降解过程中起着重要作用。以华北某焦化厂土壤为研究对象,在5个采样点(每个点分6层)采集30个土壤样品,分析土壤环境因子(理化性质和PAHs浓度)、微生物丰度及群落结构,探讨土壤中微生物组成与环境因子间的关系。结果表明:土壤中细菌丰度为5.33~8.89,与土壤深度呈显著负相关(P<0.01),与土壤PAHs、有机碳、全氮浓度呈正相关(P<0.05);土壤中优势细菌类群(门)为变形菌门(Proteobacteria),其相对丰度占比最高达90%,其次是绿弯菌门(Chloroflexi)、放线菌门(Actinobacteria)、厚壁菌门(Firmicutes)和酸杆菌门(Acidobacteria),其占门水平分类细菌数量的64%~97%;细菌类群与环境因子冗余分析表明,焦化厂土壤中细菌群落结构特征是PAHs污染和环境因子共同作用的结果,其中土壤pH与速效钾、PAHs、全氮浓度对土壤细菌群落组成影响明显,PAHs潜在降解菌Proteobacteria丰度与PAHs、全氮、有效磷、速效钾、有机碳浓度呈正相关。     

Removal of heavy metals from a contaminated soil using 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.     

铅污染土壤修复工艺技术研究

近年来,随着城市建设进程的加快,污染企业遗留下来的污染场地引起越来越多的关注,企业对土壤的污染产生很大不良的环境问题。自土壤重金属污染防治被关注开始,土壤污染的修复是很困难的,污染物处理费用非常昂贵,需要快速而有效的技术来加速修复土地的污染区。在本文中,选取一个典型铅污染土壤为研究方向,论述铅蓄电池中铅酸污染地块的修复工艺技术,对受污染场地土壤特性和环境风险进行评估,确定修复的可行性和修复的价值,通过土壤修复清洗技术,优化土壤修复基本参数,测试分析得出土壤修复最优工艺技术。     

石油污染土壤的原位修复技术

本文主要介绍了治理石油污染土壤的土壤气相抽提、生物修复和生物通风三种原位修复方法的基本原理及影响因数     

基于静态箱的污染土壤释放挥发性有机物特性研究

静态箱法是测定土壤中气态污染物释放通量的常用方法.为了阐明静态箱内污染土壤释放挥发性有机物（VOC）的特性,本文考察了 土壤中VOC种类、含量、气温和箱体内空气扰动对VOC释放通量的影响.研究发现,静态箱内VOC浓度可在5 min内达到平衡或开始衰减,前30 s的VOC浓度变化可用于计算土壤的VOC释放通量.静态箱内土壤的VOC释放通量与其lgK_ow值和分子量呈显著负相关.土壤VOC含量越高,其VOC释放通量越大.同时,静态箱内污染土壤的VOC释放通量与室外气温呈正相关,表明在实际测定VOC释放通量时应考虑气温的影响.对比静态箱内设置不同风扇个数时VOC的释放通量,发现设置1个风扇时测得的VOC释放通量最大,表明在该条件下实现静态箱内污染物 混匀是较适宜的.本研究揭示了静态箱内土壤VOC释放通量的主要影响因素,可为科学评价污染土壤的VOC释放能力并进行风险管控提供科学支撑.     

典型焦化污染场地多技术联用治理工程应用案例分析

典型焦化污染场地具有明显的多环芳烃和重金属复合污染特征,单一修复技术往往难以完成治理。多技术联用修复焦化污染场地土壤已开展了应用实践,但联用技术适用的场地污染特征和工程技术问题还鲜有报道。焦化场地多环芳烃和重金属主要分布在浅层土壤中,复合污染普遍,但2类污染物互相作用影响小,适合采用以土壤淋洗为核心的联用修复技术,其具有节省修复周期和成本的工程应用优势,二次污染防治是其技术难点,未来可发展土壤淋洗+化学氧化+生物修复联用技术,进行绿色修复。

     

Microwave enhanced stabilization of copper in artificially contaminated soil

Microwave processing was used to stabilize copper ions in soil samples. Its effects on the stabilization efficiency were studied as a function of additive, microwave power, process time, and reaction atmosphere. The stabilization efficiency of the microwave process was evaluated based on the results of the toxicity characteristic leaching procedure (TCLP) test. The results showed that the optimal experimental condition contained a 700W microwave power, 20 min process time and 3 iron wires as the additive, and that the highest stabilization efficiency level was more than 70%. In addition, the different reaction atmospheres showed no apparent effect on the stabilization efficiency of copper in the artificially contaminated soil. According to the result of the Tessier sequential extraction, the partial species of copper in the contaminated soil was deduced to transform from unstable species to stable states after the microwave process.