酸性矿山废水污灌区水稻土重金属的形态分布及生物有效性

通过野外采样调查和实验分析,对粤北大宝山矿山下游酸性矿山废水污灌区水稻土中重金属（Cd、Zn、Pb、Cu）的形态分布特征和生物有效性进行了研究.运用TCLP（toxicity characteristic leaching procedure）和BCR（community bureau of reference）连续提取法研究了土壤中重金属的生物有效性问题,并运用多元逐步线性回归分析进行对比.结果表明,酸性矿山废水污灌区水稻土中Cd以酸提取态和残渣态为主;Cu各形态含量的分配顺序为：残渣态>可还原态>酸提取态>可氧化态,以残渣态为主;Pb以可还原态和残渣态为主,占总量的86.54%;Zn主要以残渣态的形式存在、占总量的50%以上,各形态含量的分配顺序为：残渣态>酸提取态>可还原态>可氧化态.TCLP提取的重金属Cd、Cu、Pb和Zn含量分别为：0.17～0.89、 8.12～70.33、 3.16～90.33和10.24～106.85 mg·kg^-1,其平均值分别为0.41、 36.60、 15.97和50.78 mg·kg^-1.水稻籽粒中重金属Cd、Cu、Pb、Zn含量范围分别为：0.183～0.947、 3.542～5.997、 0.285～1.532和17.54～41.10 mg·kg^-1.参照卫生部颁布的食品中重金属元素限量卫生标准评价水稻籽粒重金属污染情况,其结果表明,Cu和Zn含量未出现超标现象,而Cd和Pb含量超标现象很严重,其超标率分别为87.50%和81.25%.逐步回归分析结果表明,水稻籽粒中的Cd和Zn含量显著地受到土壤中酸提取态Cd和Zn含量的影响,Cu含量显著地受到酸提取态和可氧化态Cu含量的影响,Pb含量显著地受到可还原态Pb和有机质含量的影响.水稻籽粒中重金属含量受到TCLP提取重金属含量的显著影响,重金属总量、pH和有机质对其的影响不显著.TCLP法适于对酸性矿山废水污灌区水稻土重金属生物有效性进行快速简单地评估.     

鄱阳湖湿地重金属形态分布及植物富集研究

研究了鄱阳湖湿地土壤中Cu,Zn,Pb和Cd形态与植物富集的关系. 结果表明:鄱阳湖土壤中Cu,Pb和Zn主要以有机态和残渣态为主,水溶态和离子交换态等生物有效性态含量很少;而Cd则主要以水溶态和离子交换态等生物有效性态为主,因此Cd的生态危害较大. 相关分析和偏相关分析均显示:植物中重金属含量与其生存环境中重金属水溶态或离子交换态含量直接相关,这与理论上植物只能吸收重金属水溶态相符. 植物对重金属的富集能力表现出Zn＞Cu＞Cd＞Pb的趋势. 用重金属水溶态或离子交换态进行植物富集研究,更具有可比性和科学性.      

湘江表层沉积物重金属的赋存形态及其环境影响因子分析

采用BCR三步分级提取法分析了湘江衡阳段与岳阳段表层沉积物中4种重金属（Cd、Pb、Cu、Zn）不同赋存形态的含量,阐述了重金属赋存形态及其环境影响因子的关系,评估了这4种重金属的生物有效性.结果表明,4种元素均以弱酸溶解态、可还原态和可氧化态3种可提取态为主,各元素生物有效性即可提取态含量排序为：Cd〉Pb〉Zn〉C...     

湖北省铜绿山矿区农业土壤重金属形态及生物有效性

以铜绿山矿区农业土壤为研究对象,采用BCR连续提取法提取并测定了土壤中Cu、Zn、Pb、Cd四种重金属的形态和含量,分析了重金属各形态、土壤p H和有机质之间的相关性;并对重金属分布特征和有效性进行了分析,探究土壤本身性质对矿区农业土壤重金属及其生物有效性的影响因子。结果表明:矿区农业土壤受到重金属不同程度的污染,重金属的污染程度大小为:CuZnPbCd;各重金属之间存在不同程度的相关性,Pb和Zn之间显著相关,二者可能属于同源污染物;四种重金属总量与土壤的p H和有机质不存在相关性;Pb与Cu、Zn和Cd有效态含量之间有显著相关性,表明矿区农业土壤中重金属Pb与Cu、Zn和Cd有效态含量之间相互促进、相互影响的作用较强;矿区农业土壤p H值与Pb_(可还原态)、Cd_(可还原态)、Cd_(弱酸提取态)、Cd_(可氧化态)之间均存在显著相关关系;有机质含量与Pb_(可还原态)、Pb_(残渣态)、Cu_(残渣态)、Cd_(弱酸提取态)、Cd_(可还原态)、Cd_(可氧化态)之间相关性显著,可见土壤的p H值、有机质都会对土壤中重金属的化学形态产生一定的影响;土壤中Pb、Cd的生物有效性主要受其全量、土壤p H和有机质的影响,而Zn和Cu受其全量、土壤p H和有机质的影响较小。     

城市污泥改良矿山废弃土壤的试验研究

采用室内土壤培养模拟试验,在矿山废弃土壤中外源添加不同比例未经处理的城市污泥,探讨短期污泥处理对土壤中重金属赋存形态分布特征、土壤理化性质和土壤酶活性的影响,并对施污土壤中重金属的赋存形态与土壤的理化性质和酶活性进行了相关性分析,分析了施污土壤中不同重金属赋存形态含量的影响因素。结果表明:城市污泥的施加对矿山废弃土壤中重金属Cu和Pb有一定的钝化作用,施污土壤中重金属的生物有效性大小表现为ZnCuCdPb;城市污泥的施加可明显增加矿山废弃土壤中氮、磷、钾和有机质的含量,但降低了土壤的pH值,而土壤的pH值是影响施污土壤中各重金属可交换态含量的关键因素,土壤中有机质含量是影响施污土壤中可还原态Pb和Cd以及可氧化态Cu和Zn含量的主要因素;城市污泥的施加可增加矿山废弃土壤的酶活性,其中土壤的脲酶活性是影响施污土壤中各重金属可交换态以及可还原态和可氧化态Zn、Pb含量的主要因素,而土壤的磷酸酶和过氧化氢酶活性是影响施污土壤中残渣态Cu和Pb含量的主要因素。     

滇池内湖滨带沉积物中重金属形态分析

采用BCR3步分级提取法测定了滇池内湖滨带沉积物中4种重金属(Pb、Cd、Cu和Zn)不同形态的含量,初步评估了这4种重金属的生物有效性.结果表明,Cd和Zn主要以可提取态存在(即弱酸溶解态、可还原态和可氧化态),而Pb和Cu均以残渣态为主要存在形式.通过计算可提取态含量所占总量百分量大小,可知各金属的生物有效性大小排序为:Zn(53.06%)>Cd(50.84%)>Cu(34.62%)> Pb(28.65%).沉积物中总有机碳(TOC)与各金属不同形态间的相关性分析表明,可氧化态重金属与有机碳结合的趋势远大于弱酸溶解态和可还原态.表层沉积物中可提取态重金属的空间分布特征明显表现为草海>外海,除Cu外,大部分样点的可提取态Pb、Cd和Zn含量均随采样深度增加而减少.     

柘林湾海水养殖区底泥中重金属生物有效性及生态风险评价

采集柘林湾海水养殖区8个位点表层沉积物样品,考察了沉积物样品中重金属含量、生物有效性和形态分布,并分别利用基于总量的Hakanson指数法和基于形态的风险评价指数(RAC)评价了沉积物中重金属的生态危害风险.结果表明,柘林湾海水养殖区大部分位点沉积物中重金属含量符合海洋沉积物质量Ⅰ类标准限值,少数位点Zn和Pb含量超过Ⅰ类限值但低于Ⅱ类限值.沉积物中重金属的薄膜扩散梯度技术(DGT)测定浓度(C_(DGT))与间隙水中的浓度(C_(IW))对重金属生物可利用性评估状况基本一致,Zn、Ni和Pb生物可利用性较高.沉积物中Cr、Ni、Zn和Cu以残渣态为主,Cd和Pb以弱酸提取态为主.柘林湾沉积物中重金属总体存在轻度到中度生态危害风险,Cd和Pb生态危害风险较高.沉积物中Cr、Ni、Zn、Cu和Cd的C_(DGT)与其弱酸提取态含量明显正相关,重金属弱酸提取态能较好反映其生物可利用性.     

太湖表层沉积物重金属赋存形态分析及污染特征

为了解太湖表层沉积物中重金属的污染状况,对太湖表层沉积物中4种重金属（Cd、Pb、Cu、Zn）的含量及空间分布分别进行了对比研究,并采用BCR三步分级提取法分析了太湖表层沉积物中4种重金属（Cd、Pb、Cu、Zn）不同赋存形态的含量,评估了这4种重金属的生物有效性,最后采用潜在生态危害指数法对重金属污染程度及潜在生态危害进行了评价.结果表明,太湖表层沉积物中4种重金属元素均有一定程度的富集,其中Cd的富集程度最为严重;赋存形态分析表明4种金属均主要以可提取态形式存在,各元素生物有效性即可提取态含量排序为：Cd〉Pb〉Zn〉Cu;潜在生态危害指数法评价结果表明,元素Cd为太湖表层沉积物中最主要的污染元素,且具有较强的生态危害.其次是Pb,Cu和Zn则较为轻微.4种重金属潜在生态危害由大到小排序为：Cd〉Pb〉Cu〉Zn.     

生物可降解的螯合剂EDDS提取城市污泥中Cu，Zn，Pb和Cd

研究了生物可降解的螯合剂EDDS对城市污泥中的Cu,Zn,Cd和Pb的提取效应.EDDS提取动力学研究表明,Cu,Zn,Cd和Pb达到最大提取量的时间分别为12,24,36和36 h.EDDS提取液pH效应研究表明,pH对4种重金属元素的释放没有显著的影响.4种重金属元素的EDDS提取率:Cu为23%～39%,Zn为41%～42%,Cd为18%～24%,Pb为24%～44%.对比EDDS和EDTA对重金属的提取率:Cu为EDDS＞EDTA;Zn为EDDS≈EDTA;Cd和Pb为EDTA＞EDDS.提取之后,用BCR连续提取法研究污泥中残留的重金属元素的形态分布表明,酸溶/可交换态、可还原态和可氧化态金属浓度明显降低.综合考虑运行成本、提取率和城市污泥资源化利用价值,建议EDDS提取城市污泥条件为pH中性、提取时间24 h,从而可以有效地降低城市污泥中有效态重金属元素含量.     

2种组配改良剂对稻田土壤重金属有效性的效果

为研究2种组配改良剂LS(碳酸钙+海泡石)和HZ(羟基磷灰石+沸石)对土壤重金属的生物有效性以及水稻吸收累积重金属的影响,在湘南某矿区附近污染稻田中施用了不同添加量(0,2,4,8g/kg)的两种组配改良剂,并进行了水稻种植的田间试验.结果表明,施用2~8g/kg组配改良剂LS和HZ均能使土壤pH值和CEC含量显著增加,有机质含量变化不明显,LS比HZ更能提高土壤pH值和CEC含量.施用2~8g/kg组配改良剂LS能使土壤中Pb、Cd、Cu和Zn的TCLP提取态含量分别降低25.7%~52.2%、12.7%~25.7%、6.4%~17.2%和8.6%~23.4%,施用2~8g/kg HZ使土壤中Pb、Cd、Cu和Zn的TCLP提取态含量分别降低57.6%~80.1%、7.0%~40.9%、2.3%~22.7%和4.5%~33.2%.两种组配改良剂能显著降低土壤中Pb、Cd、Cu和Zn的生物有效性,抑制水稻植株对Pb和Cd的吸收,土壤Pb、Cd和Cu的TCLP提取态含量与水稻根系和糙米中Pb、Cd和Cu的含量之间存在显著或极显著的正相关关系,TCLP提取态含量能较好的表示重金属在土壤中的生物有效性.     

Distribution and ecological effect of mercury in Laogang landfill, Shanghai, China

Laogang landfill near Shanghai is the largest landfill in China, and receives about 10000 t of daily garbage per day, Samples of topsoil and plants were analyzed to evaluate mercury pollution from the landfill. For topsoil samples, there were significant correlations among total mercury （HgT）, combinative mercury （Hgc） and gaseous mercury （HgG）, and content of total organic carbon （TOC）, but, no significantly relationship was found between Hg content and filling time. Hg content changes in vertical profiles with time showed that the average Hgv of profiles 1992, 1996, and 2000 was similar, but their average HgG was quite different. HgT was significantly correlated with Hgc in profile 1992 and 2000, and Hgv was significantly correlated with Hg6 in profile 1996. HgG/Hgv ratio in profile samples decreased in the order of （HgG,/HgT）1992〉（HgG/HgT）1996〉〉（HgG/HgT）2000. A simple outline of Hg release in landfill could be drawn： with increasing of filling time, degradation undergoes different biodegradation, accordingly, gaseous mercury goes through small, more, and small proportion to total mercury. Distribution of Hg in plants was inhomogeneous, following the order of leaf〉root〉stem. The highest value of leaf may be associated with higher atmospheric Hg from landfill. Ligneous plants （e.g. Phyllostachys glanca, Prunus salicina and Ligustrum lucidum） are capable of enriching more Hg than herbaceous plants.     

EDTA-enhanced phytoremediation of lead contaminated soil by Bidens maximowicziana

Phytoremediation is a potential cleanup technology for the removal of heavy metals from contaminated soils.Bidens maximowicziana is a new Pb hyperaccumulator,which not only has remarkable tolerance to Pb but also extraordinary accumulation capacity for Pb.The maximum Pb concentration was 1509.3 mg/kg in roots and 2164.7 mg/kg in overground tissues.The Pb distribution order in the B. maximowicziana was:leaf>stem>root.The effect of amendments on phytoremediation was also studied.The mobility of soil Pb and the Pb concentrations in plants were both increased by EDTA application.Compared with CK(control check),EDTA application promoted translocation of Pb to overground parts of the plant.The Pb concentrations in overground parts of plants was increased from 24.23-680.56 mg/kg to 29.07-1905.57 mg/kg.This research demonstrated that B.maximowicziana appeared to be suitable for phytoremediation of Pb contaminated soil,especially,combination with EDTA.     

Decomposition of alachlor by ozonation and its mechanism

Decomposition and corresponding mechanism of alachlor, an endocrine disruptor in water by ozonation were investigated. Results showed that alachlor could not be completely mineralized by ozone alone. Many intermediates and final products were formed during the process, including aromatic compounds, aliphatic carboxylic acids, and inorganic ions. In evoluting these products, some of them with weak polarity were qualitatively identified by GC-MS. The information of inorganic ions suggested that the dechlorination was the first and the fastest step in the ozonation of alachlor.     

Enzymatic oxidation of aqueous pentachlorophenol

The influence of the nonionic surfactant Tween 80 on pentachlorophenol （PCP） oxidation catalyzed by horseradish peroxidase was studied. The surfactant was tested at concentrations below and above its critical micelle concentration （CMC）. Enhancement of PCP removal was observed at sub-CMCs. The presence of Tween 80 in the reaction mixture reduced enzyme inactivation which occurred through a combination of free radical attack and sorption by precipitated products. A simple first-order model was able to simulate time profiles for enzyme inactivation in the presence or absence of Tween 80. At supra-CMCs, the surfactant caused noticeable reductions in PCP removal, presumably through micelle partitioning of PCP which precluded the hydrophobic PCP molecule from interacting with the enzyme.     

基于综合水质标识指数和对应分析法的校园河道水质评价

以三峡大学的校园河道求索溪为研究对象,利用综合水质标识指数法确定求索溪水质类别,分析其水质时空变化规律,并利用对应分析法得出求索溪中不同监测点的主要污染因子.研究结果表明:求索溪整体的综合水质标识指数为7.423,整体水质为劣V类(地表水环境质量标准GB 3838-2002)且黑臭.从时间变化来看,求索溪4月份的水质最差,5月份次之,4、5月份所有监测点的水质都劣于V类且黑臭;8月份水质最好,水质为Ⅳ类;从空间分布来看,8个监测点综合水质标识指数均超过6.0,水质为劣V类,其中6号监测点的水质相对最好,监测点3号的水质相对最差;对应分析法得出求索溪的整体水体污染程度受总氮因子的影响最大,其次为总磷.该研究拟为求索溪及类似校园河道的水环境治理研究提供基础依据和参考.     

Effects of chitosan on growth of an aquatic plant (Hydrilla verticillata) in polluted waters with different chemical oxygen demands

Effects of chitosan on a submersed plant, Hydrilla verticillata, were investigated. Results indicated that H. venicillata could prevent ultrastructure phytotoxicities and oxidativereaction from polluted water with high chemical oxygen demand (COD). Superoxide dismutase (SOD) activity and malondialdehyde (MDA) contents in H. verticillata treated with 0.1% chitosan in wastewater increased with high COD (980 mg/L) and decreased with low COD (63 mg/L), respectively. Ultrastructural analysis showed that the stroma and grana of chloroplast basically remained normal. However, plant cells from the control experiment (untreated with chitosan) were vacuolated and the cell interval increased. The relict of protoplast moved to the center, with cells tending to disjoint. Our findings indicate that wastewater with high COD concentration can cause a substantial damage to submersed plant, nevertheless, chitosan probably could alleviate the membrane lipid peroxidization and ultrastructure phytotoxicities, and protect plant cells from stress of high COD concentration polluted water.     

Removal of cadmium using MnO2 loaded D301 resin

MnO2 loaded weak basic anion exchange resin D301 （Anion exchange resin, macroreticular weak basic styrene） as adsorbent has been prepared and applied to the removal of cadmium. The adsorption characteristics have been investigated with respect to effect of pH, equilibrium isotherms, removal kinetic data, and interference of the coexisting ions. The results indicated that the Cd^2＋ could be efficiently removed using MnO2 loaded D301 resin in the pH range of 3-8 from aqueous solutions with the co-existence of high concentration of alkali and alkaline-earth metals ions. The saturate adsorption capacity of the Cd^2＋ was 77.88 mg/g. The adsorption process followed the pseudo first-order kinetics. The equilibrium data obtained in this study accorded excellently with the Langmuir adsorption isotherm.     

Effect of coagulation pretreatment on the fouling of ultrafiltration membrane

The purpose of this study is to understand the effect and mechanism of preventing membrane fouling, by coagulation pretreatment, in terms of fractional component and molecular weight of natural organic matter （NOM）. A relatively higher molecular weight （MW） of hydrophobic compounds was responsible for a rapid decline in the ultrafiltration flux. Coagulation could effectively remove the hydrophobic organics, resulting in the increase of flux. It was found that a lower MW of neutral hydrophilic compounds, which could remove inadequately by coagulation, was responsible for the slow declining flux. The fluxes in the filtration of coagulated water and supernatant water were compared and the results showed that a lower MW of neutral hydrophilic compounds remained in the supernatant water after coagulation could be rejected by a membrane, resulting in fouling. It was also found that the coagulated flocs could absorb neutral hydrophilic compounds effectively. Therefore, with the coagulated flocs formed on the membrane surface, the flux decline could be improved.     

Penetration analysis of elements and bioleaching treatment of spent refractory for recycling

Acidithiobacillus ferrooxidans ATCC23270 and Acidithiobacillus thiooxidans TM-32 were used for bioleaching of spent refractories of aluminium and copper melting furnaces for their recycling.Firstly,penetration of elements into aluminium melting furnace refractory was investigated and it was found that up to 7 cm from surface was contaminated.Comparison on leaching efficiency by the strains ATCC23270 and TM-32 found that the strain ATCC23270 could treat larger amount of the refractories than the strain TM-32 could do.In the experiment of bioleaching of spent refractory aluminium melting furnace by the strain ATCC23270,high leaching efficiency were obtained on Al,Si,and Ca,and extremely low leaching performance was,however,shown on the rest of elements i.e.,Na,Mn,and Zn.Under the strain TM-32 use,relatively high leaching performance was recognized on Al,Si,Ca,Na,Mn,and Zn.In the experiment of bioleaching for spent refractory copper melting furnace,almost the same leaching trends were shown on Cu,Zn,Al,and Si under the strains ACTT23270 and TM-32 uses.     

Evaluation of phytoextracting cadmium and lead by sunflower, ricinus, alfalfa and mustard in hydroponic culture

Soil contaminated with heavy metals cadmium(Cd)and lead(Pb)is hard to be remediated.Phytoremediation may be a feasible method to remove toxic metals from soil,but there are few suitable plants which can hyperaccumulate metals.In this study,Cd and Pb accumulation by four plants including sunflower(Helianthus annuus L.),mustard(Brassica juncea L.),alfalfa(Medicago sativa L.), ricinus(Ricinus communis L.)in hydroponic cultures was compared.Results showed that these plants could phytocxtract heavy metals, the ability of accumulation differed with species,concentrations and categories of heavy metals.Values of BCF(bioconcentration factor)and TF(translocation factor)indicated that four species had dissimilar abilities of phytoextraction and transportation of heavy metals.Changes on the biomass of plants,pH and Eh at different treatments revealed that these four plants had distinct responses to Cd and Pb in cultures.Measurements should be taken to improve the phytoremediation of sites contaminated with heavy metals,such as pH and Eh regulations,and so forth.