外源水溶性有机物对生菜积累重金属Pb、Cd的影响

以城市生活污泥及其蚓粪(蚯蚓处理过的污泥)中提取的水溶性有机物(DOM)为研究对象,研究了DOM对土壤吸持重金属Pb、Cd的影响,同时进行盆栽试验,研究污泥和蚓粪水溶性有机物存在下生菜对重金属Pb、Cd的积累。结果表明:与对照相比,外源DOM的加入可以降低土壤对重金属Pb、Cd的吸附能力。不同来源的DOM对土壤吸附重金属的影响存在差异,相同DOM浓度下,源于蚓粪的DOM比源于污泥的DOM更能抑制土壤对重金属Pb和Cd的吸附。外源DOM的加入可增强土壤重金属Pb、Cd的活性,促进植物对重金属的吸收与积累。     

污泥与猪粪作为培养基微生物去除垃圾焚烧飞灰中的重金属

以污泥或猪粪代替常规的无机盐(SM)作为A.ferrooxidans和A.thiooxidans复合菌株的培养基,利用微生物淋滤法去除垃圾焚烧飞灰中的重金属.结果表明,重金属去除率大小顺序为:污泥+菌液>SM+菌液>猪粪+菌液.污泥+菌液的处理中,经过15d的微生物淋滤,Cd、Zn、Cu去除率最高分别达到88.1%、78.7%、69.6%,而猪粪+菌液的处理,3种金属的去除率分别为82.4%、73.5%、60.0%.试验也表明,相同浓度的猪粪DOM对硫杆菌复合菌株的抑制作用远大于污泥DOM.当污泥DOM和猪粪DOM中水溶性有机碳浓度分别高于400mg/L和150mg/L时,就表现出对硫杆菌的不可修复的抑制作用.猪粪DOM中小分子量组分较多是造成这一现象的主要原因.     

水溶性有机物对土壤吸附-解吸菲的影响

以Tween-80为对照,有机物料猪粪(pig manure, PM)、绿肥(green manure, GM)和污泥(sewage sludge, SS)为水溶性有机物(dissolved organic matter, DOM)的提取原料,菲(Phe)为多环芳烃(PAHs)的代表,采用序批试验研究了不同来源DOM对土壤吸附与解吸Phe的影响.结果表明,供试DOM均能明显降低Phe在土壤上的吸附.在DOM试验浓度范围内（0～300 mg·L^-1）,土壤对Phe的吸附量与DOM浓度之间呈极显著负直线相关关系(r_PM>=-0.988?8,r_SS>=-0.982?6,r_Tween-80>=-0.974?3,r_GM>=-0.990?5).菲的吸附等温线可用Freundlich方程定量描述.供试3种DOM抑制土壤吸附Phe和促进土壤吸附Phe的解吸的强弱顺序为:猪粪DOM>污泥DOM>绿肥DOM.本研究结果表明,农业土壤中水溶性有机物能明显活化土壤中的PAHs,增强其在土壤中的移动性.     

垃圾渗滤液中溶解性有机物对土壤重金属吸附

垃圾渗滤液主要组分为重金属和大量的溶解性有机物(DOM). 选取我国北方具有代表性的褐土,通过不同pH(5～9)和温度 (15,25和35 ℃)下的等温吸附试验,研究了垃圾渗滤液中DOM对Cu, Cd, Pb和Zn 4种重金属在土壤中吸附行为的影响. 结果表明:DOM对Cu和Cd在土壤中的吸附促进作用较明显,对Pb有微弱的促进作用,对Zn的吸附影响不明显;改变pH,DOM对4种重金属在褐土中的吸附也表现出不同的影响,吸附平衡后土壤溶液pH变化差异明显;25 ℃下Cu在土壤中的吸附量高于15和35 ℃条件下;有DOM时,Cd, Zn和Pb在土壤中的吸附量随着温度的升高而增大.      

垃圾渗滤液中溶解性有机物对土壤重金属吸附行为的影响

垃圾渗滤液主要组分为重金属和大量的溶解性有机物(DOM).选取我国北方具有代表性的褐土,通过不同pH(5~9)和温度(15,25和35℃)下的等温吸附试验,研究了垃圾渗滤液中DOM对Cu,Cd,Pb和Zn 4种重金属在土壤中吸附行为的影响.结果表明:DOM对Cu和Cd在土壤中的吸附促进作用较明显,对Pb有微弱的促进作用,对Zn的吸附影响不明显;改变pH,DOM对4种重金属在褐土中的吸附也表现出不同的影响,吸附平衡后土壤溶液pH变化差异明显;25℃下Cu在土壤中的吸附量高于15和35℃条件下;有DOM时,Cd,Zn和Pb在土壤中的吸附量随着温度的升高而增大.     

污泥中的DOM对中国土壤中Cd吸附的影响Ⅰ.纬度地带性差异

研究了中国不同纬度地带土壤中水溶性有机质（DOM）对Cd的等温吸附行为影响的差异，并进一步探讨其作用机理。研究结果表明：在南方酸性土壤中，DOM对Cd吸附的影响以促进作用为主；而在北方的中性和碱性土壤中，主要表现为抑制作用。同一土壤中，DOM对A层土壤中Cd吸附的抑制作用大于B层，这与A层土壤TOC含量较高有关。DOM的酸碱缓冲作用和土壤对DOM的吸附作用是影响DOM对Cd吸附抑制作用的两个主要因素。     

农业常用有机物料中水溶性有机物的理化性质特征

以水稻土水溶性有机物(DOM)为对照,采用物理化学和光谱学实验研究了农业上常用有机物料:猪粪、绿肥和污泥DOM的理化性质差异.结果表明,水稻土、污泥、猪粪和绿肥DOM含量分别为122, 23793, 12904, 380560mgC/kg.若施用等量有机物料,带入土壤的DOM量最多的应是绿肥.不同有机物料DOM中大分子组分含量高低顺序为:水稻土(51.08%)>猪粪(41.25%)>污泥(23.33%)>绿肥(7.36%);而极性组分含量的顺序则相反,水稻土(10.71%)猪粪DOM(1.12)>污泥DOM(1.11)>绿肥DOM(0.98),紫外图谱也证实了这一点.     

溶解性有机质对芘在土壤中吸附解吸的影响

从腐解不同阶段的水稻秸秆提取溶解性有机质(DOM),用DAX-8树脂分组的方法分析了其亲疏水性,并研究了提取到的DOM对芘在土壤中吸附-解吸行为的影响.结果表明,随秸秆腐解时间的延长,产生DOM中亲水性组分减少,疏水性组分增多.在本试验所研究的吸附解吸实验条件下,芘在土壤中的吸附解吸均可用线性方程进行描述.加入DOM后,芘的吸附受到显著抑制(p0.01),并且随腐解时间延长,抑制作用增强;芘在土壤中存在解吸迟滞现象,加入DOM后迟滞现象减弱,促进了芘在土壤中的解吸.随腐解作用的进行,DOM促进芘解吸的作用增强,解吸迟滞系数减小.这是由于随秸秆腐解作用的进行,产生DOM中疏水性组分含量增多,其对芘的增溶作用增强所致.     

雌二醇在土壤/沉积物中的吸附特征及猪粪DOM对吸附的影响

天然类固醇雌激素如17β-雌二醇(E2)在极低质量浓度下(ng.L-1)即可干扰水生生物的生殖功能.为准确预测E2向水体迁移,通过摇床实验研究了E2在中国北方3种不同土壤/沉积物表面的吸附特征,同时探讨了猪粪及其堆肥可溶态有机质(DOM)对E2吸附的影响.结果发现,E2在土壤/沉积物表面吸附符合Freundlich等温吸附方程(R2>0.76),E2在河流沉积物、潮土、黑土皆表现为非线性,其中黑土吸附的非线性最强(n=0.74);吸附系数Kf介于26.2～57.5,并与有机质含量呈显著正相关(P<0.05).猪粪及其堆肥DOM显著抑制E2在土壤/沉积物表面的吸附,其中堆肥DOM的影响尤为显著.研究认为,有机质是土壤/沉积物中吸附E2的主要组分,共存猪粪DOM在较低浓度下可提高E2迁移性,增加E2向地表和地下水的迁移风险.     

施用有机物料对污染土壤水溶性有机物和铜活性的动态影响

采用黑麦草盆栽研究施用绿肥、污泥和猪粪后，对Cu污染土壤水溶性有机物(DOM)和土壤Cu环境行为动态的影响．施用有机物料后土壤DOM含量比对照增加0.4—7.5倍，尤以绿肥和猪粪最明显．但随时间延长DOM降解明显，尤其在第一周内．污染土壤中水溶性Cu浓度随DOM的降解而相应减少研究发现，施用污泥有利于降低污染土壤中水溶性Cu浓度和黑麦草对Cu的吸收量，这是污泥固相有机质对Cu吸持使其活性降低和污泥DOM使Cu活性提高二者综合作用的结果．与此相反，施用绿肥和猪粪后，黑麦草体内的Cu含量却明显提高，其中潮土上提高1．4～2．1倍，红壤上提高1．4-1．6倍．因此．施用有机物料改良重金属污染地需格外谨慎。     

Toxic effects of acetochlor, methamidophos and their combination on nifH gene in soil

Toxic effects of two agrochemicals on nifH gene in agricultural black soil were investigated using denaturing gradient gel electrophoresis （DGGE） and sequencing approaches in a microcosm experiment. Changes of soil nifH gene diversity and composition were examined following the application of acetochlor, methamidophos and their combination. Acetochlor reduced the nifH gene diversity （both in gene richness and diversity index values） and caused changes in the nifH gene composition. The effects of acetochlor on nifH gene were strengthened as the concentration of acetochlor increased. Cluster analysis of DGGE banding patterns showed that nifH gene composition which had been affected by low concentration of acetochlor （50 mg/kg） recovered firstly. Methamidophos reduced nifH gene richness that except at 4 weeks. The medium concentration of methamidophos （150 mg/kg） caused the most apparent changes in nifH gene diversity at the first week while the high concentration of methamidophos （250 mg/kg） produced prominent effects on nifH gene diversity in the following weeks. Cluster analysis showed that minimal changes of nifH gene composition were found at 1 week and maximal changes at 4 weeks. Toxic effects of acetochlor and methamidophos combination on nifH gene were also apparent. Different nifH genes （bands） responded differently to the impact of agrochemicals： four individual bands were eliminated by the application of the agrochemicals, five bands became predominant by the stimulation of the agrochemicals, and four bands showed strong resistance to the influence of the agrochemicals. Fifteen prominent bands were partially sequenced, yielding 15 different nifH sequences, which were used for phylogenetic reconstructions. All sequences were affiliated with the alpha- and beta-proteobacteria, showing higher similarity to eight different diazotrophic genera.     

Arsenic uptake by arbuscular mycorrhizal maize （Zea mays L.） grown in an arsenic-contaminated soil with added phosphorus

The effects of arbuscular mycorrhizal (AM) fungus (Glomus mosseae) and phosphorus (P) addition (100 mg/kg soil) on arsenic (As) uptake by maize plants (Zea mays L.) from an As-contaminated soil were examined in a glasshouse experiment.Non-mycorrhizal and zero-P addition controls were included.Plant biomass and concentrations and uptake of As,P,and other nutrients,AM colonization,root lengths,and hyphal length densities were determined.The results indicated that addition of P significantly inhibited root colonization and development of extraradical mycelium.Root length and dry weight both increased markedly with mycorrhizal colonization under the zero-P treatments,but shoot and root biomass of AM plants was depressed by P application.AM fungal inoculation decreased shoot As concentrations when no P was added,and shoot and root As concentrations of AM plants increased 2.6 and 1.4 times with P addition,respectively.Shoot and root uptake of P,Mn,Cu,and Zn increased,but shoot Fe uptake decreased by 44.6%,with inoculation, when P was added.P addition reduced shoot P,Fe,Mn,Cu,and Zn uptake of AM plants,but increased root Fe and Mn uptake of the nonmycorrhizal ones.AM colonization therefore appeared to enhance plant tolerance to As in low P soil,and have some potential for the phytostabilization of As-contaminated soil,however,P application may introduce additional environmental risk by increasing soil As mobility.     

Degradation of metabolites accumulated of benzo[a]pyrene by coupling Penicillium Chrysogenum with KMnO4

Several main metabolites of benzo[a]pyrene （BaP） formed by Penicillium chrysogenum, Benzo[a]pyrene-1,6-quinone （BP 1,6- quinone）, trans-7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene （BP 7,8-diol）, 3-hydroxybenzo[a]pyrene （3-OHBP）, were identified by high-performance liquid chromatography （HPLC）. The three metabolites were liable to be accumulated and were hardly further metabolized because of their toxicity to microorganisms. However, their further degradation was essential for the complete degradation of BaP. To enhance their degradation, two methods, degradation by coupling Penicillium chrysogenum with KMnO4 and degradation only by Penicillium chrysogenum, were compared; Meanwhile, the parameters of degradation in the superior method were optimized. The results showed that （1） the method of coupling Penicillium chrysogenum with KMnO4 was better and was the first method to be used in the degradation of BaP and its metabolites; （2） the metabolite, BP 1,6-quinone was the most liable to be accumulated in pure cultures; （3） the effect of degradation was the best when the concentration of KMnO4 in the cultures was 0.01% （w/v）, concentration of the three compounds was 5 mg/L and pH was 6.2. Based on the experimental results, a novel concept with regard to the bioremediation of BaP-contaminated environment was discussed, considering the influence on environmental toxicity of the accumulated metabolites.     

Impact of atrazine and nitrogen fertilizers on the sorption of chlorotoluron in soil and model sorbents

Sorption of chlorotoluron in ammonium sulfate, urea and atrazine multi-solutes system was investigated by batch experiments. The results showed application of nitrogen fertilizers to the soil could affect the behavior of chlorotoluron. At the same concentration of N, sorption of chlorotoluron decreased as the concentration of atrazine increased on the day 0 and 6 in soil, respectively. The sorption of chlorotoluron increased from 0 to 6 d when soils were preincubated with deionized water, ammonium sulfate and urea solution for 6 d. That indicated incubation time was one of the most important factors for the sorption of chlorotoluron in nitrogen fertilizers treatments. The individual sorption isotherms of chlorotoluron in rubbery polymer and silica were strictly linear in single solute system, but there were competition sorption between pesticides or between pesticides and nitrogen fertilizers. That indicated the sorption taken place by concurrent solid-phase dissolution mechanism and sorption on the interface of water-organic matter or water-mineral matter.     

Potential of plant polyphenol oxidases in the decolorization and removal of textile and non-textile dyes

In this study an effort has been made to use plant polyphenol oxidases; potato （Solanum tuberosum） and brinjal （Solanum melongena）, for the treatment of various important dyes used in textile and other industries. The ammonium sulphate fractionated enzyme preparations were used to treat a number of dyes under various experimental conditions. Majority of the treated dyes were maximally decolorized at pH 3.0. Some of the dyes were quickly decolorized whereas others were marginally decolorized. The initial first hour was sufficient for the maximum decolorization of dyes. The rate of decolorization was quite slow on long treatment of dyes. Enhancement in the dye decolorization was noticed on increasing the concentration of enzymes. The complex mixtures of dyes were treated with both preparations of polyphenol oxidases in the buffers of varying pH values. Potato polyphenol oxidase was significantly more effective in decolorizing the dyes to higher extent as compared to the enzyme obtained from brinjal polyphenol oxidase. Decolorization of dyes and their mixtures, followed by the formation of an insoluble precipitate, which could be easily removed simply by centrifugation.     

Effects of two sludge application on fractionation and phytotoxicity of zinc and copper in the soil

The potential harm of heavy metals is a primary concern in application of sludge to the agricultural land. A pot experiment was conducted to evaluate the effect of two sludges on fractionation of Zn and Cu in soil and their phytotoxicity to pakchoi. The loamy soil was mixed with 0%, 20%, 40%, 60% and 80% (by weight) of digested sewage sludge (SS) and composted sludge (SC). The additions of both sludges caused a significant raise in all fractions, resulting in that exchangeable (EXCH) and organic bound (OM) became predominance of Zn and organic bound Cu occupied the largest portion. There was more available amount of Zn and Cu in SS treatments than SC treatments. During the pot experiment, the concentration of Zn in EXCH, carbonate (CAR) and OM and Cu in EXCH and OM fractions decreased in all treatments, so their bioavailability reduced. Germination rate and plant biomass decreased when the addition rate was high and the best yield appeared in 20% mixtures at the harvest of pakchoi. The two sludges increased tissue contents of Zn and Cu especially in the SS treatments. Zn in pakchoi was not only in relationship to ΔEXCH and ΔCAR forms but also in ΔOM forms in the sludge-soil mixtures. Tissue content of Cu in pakchoi grown on SC-soils could not be predicted by ΔEXCH. These correlation rates between Zn and Cu accumulation in pakchoi and variation of different fractions increased with time, which might indicate that sludges represented stronger impacts on the plant in long-term land application.     

Intraspecific differences in effects of co-contamination of cadmium and

A hydroponic experiment was carried out to study intraspecific differences in the effects of different concentrations of cadmium (Cd)(0-10 mg/L) and arsenate (As(V)) (0-8 mg/L) on the growth parameters and accumulation of Cd and As in six wheat varieties Jing-9428, Duokang-1, Jingdong-11, Jing-411, Jingdong-8 and Zhongmai-8. The endpoints of wheat seedlings, including seed germination,biomass, root length and shoot height, decreased with increasing the Cd and As concentrations. Significant differences in seed germination, biomass, root length, shoot height and the accumulation of Cd and As were observed between the treatments and among the varieties (p ＜ 0.05). The lethal dosage 50% were about 20, 80, 60, 60, 80 and 20 mg As/L for Jing-9428, Duokang-1, Jingdong-11,Jing-411, Jingdong-8 and Zhongmai-8, respectively, and the corresponding values for Cd were about 30, 80, 20, 40, 60 and 10 mg Cd/L, respectively. Among the six varieties, Duokang-1 was found to be the most resistant to Cd and As toxicity, and Zhongmai-8 was the most sensitive to Cd and As co-contamination. The resistance of the six varieties was found dependant on the seedling uptake of Cd and As. Duokang-1 was the most suitable for cultivation in Cd and As co-contaminated soils.     

Removal of heavy metals from sewage sludge by low costing chemical method and recycling in agriculture

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Isolation and preliminary characterization of a 3-chlorobenzoate degrading bacteria

A study was conducted to compare the diversity of 2-, 3-, and 4-chlorobenzoate degraders in two pristine soils and one contaminated sewage sludge. These samples contained strikingly different populations of mono-chlorobenzoate degraders. Although fewer cultures were isolated in the uncontaminated soils than contaminated one, the ability of microbial populations to mineralize chlorobenzoate was widespread. The 3- and 4-chlorobenzoate degraders were more diverse than the 2-chlorobenzoate degraders. One of the strains isolated from the sewage sludge was obtained. Based on its phenotype, chemotaxonomic properties and 16S rRNA gene, the organism S-7 was classified as Rhodococcus erythropolis. The strain can grow at temperature from 4 to 37℃. It can utilize several （halo）aromatic compounds. Moreover, strain S-7 can grow and use 3-chlorobenzoate as sole carbon source in a temperatures range of 10-30℃ with stoichiometric release of chloride ions. The psychrotolerant ability was significant for bioremediation in low temperature regions. Catechol and chlorocatechol 1,2-dioxygenase activities were present in cell free extracts of the strain, but no （chloro）catechol 2,3- dioxygenase activities was detected. Spectral conversion assays with extracts from R. erythropolis S-7 showed accumulation of a compound with a similar UV spectrum as chloro-cis,cis-muconate from 3-chlorobenzoate. On the basis of these results, we proposed that S-7 degraded 3-chlorobenzoate through the modified ortho-cleave pathway.     

Single and joint effects of pesticides and mercury on soil urease

The influence of two pesticides including chlorimuron-ethyl and furadan and mercury （Hg） on urease activity in 4 soils （meadow burozem and phaeozem） was investigated. The soils were exposed to various concentrations of the two pesticides and Hg individually and simultaneously. Results showed that there was a close relationship between urease activity and organic matter content in soil. Chlorimuron-ethyl and furadan could both activate urease in the 4 soils. The maximum increment of urease activity by chlorimuronethyl was up to 14%-18%. There was almost an equal increase （up to 13%-21%） in the urease activity by furadan. On the contrary, Hg markedly inhibited soil urease activity. A logarithmic equation was used to describe the relationship （P〈0.05） between the concentration of Hg and the activity of soil urease in the 4 tested soils. Semi-effect dose （ED50） values by the stress of Hg based on the inhibition of soil urease in the 4 soils were 88, 5.5, 24 and 20 mg/kg, respectively, according to the calculation of the corresponding equations. The interactive effect of chlorimuron-ethyl or furadan with metal Hg on soil urease was mainly synergic at the highest tested concentrations.