易悬浮和外源输入下原位覆盖对生物有效磷形成的影响

在有外源磷持续汇入的前提下,研究了底泥原位覆盖钙改性材料和锁磷剂被悬浮颗粒再覆盖后对沉积物生物有效磷(BAP)的影响.结果表明,与空白对照相比,底泥原位覆盖后,BAP平均下降34.30%,此外,上覆水及间隙水溶解性无机磷(DIP)的浓度分别平均下降了74.25%和47.48%(0～3 cm),说明覆盖材料可以有效减少水体DIP的浓度,促进易被生物利用态磷浓度的降低.然而,当覆盖材料受到悬浮颗粒影响后,BAP平均下降20.27%,其中,藻类可利用磷(AAP)、碳酸氢钠可提取磷(Olsen-P)和水溶性磷(WSP)的含量较未被悬浮颗粒覆盖组显著提高,分别增加了18.28%、17.41%和12.58%,说明覆盖材料受悬浮颗粒影响后不利于降低底泥磷的生物有效性.     

镁改性芦苇生物炭控磷效果及其对水体修复

将收割的芦苇制成生物炭,投加到底泥中以控制内源磷释放,是一种将芦苇资源化利用的新途径.将芦苇通过氯化镁浸渍改性,分别在300、 450和600℃条件下高温裂解,制得3种镁改性芦苇生物炭,通过等温吸附实验分析3种炭对磷酸盐的吸附特征,选择了对磷酸盐吸附效果较好的生物炭MBC-450作为研究材料.以某校园河道底泥和上覆水为研究对象,探讨镁改性芦苇生物炭在不同投加方式(混合和覆盖)下对上覆水磷酸盐的吸附作用及内源磷释放的控制效果.结果表明,混合和覆盖投加可有效降低上覆水DIP浓度,与对照组相比磷累积吸附量分别提高了17.3%和11.7%;混合投加对间隙水磷的控制效果更明显,与对照组相比,间隙水DIP从0～2 cm至4～6 cm分别降低了14.7%、 18.9%和35.36%,而覆盖投加对应分别降低了33.3%、-28.2%和12.9%.与对照组相比,生物炭混合和覆盖分别导致0～2 cm和2～4 cm底泥中NH₄Cl-P占TP的比例分别升高了15%、 15%(混合)和12%、 2%(覆盖),而BD-P占TP的比例分别降低了7%、 9%(混合)和6%、 3%(覆盖),Al-...     

扰动与钝化剂对水/沉积物系统中磷释放及磷形态的影响

考察了扰动与钝化剂对滇池重污染底泥的磷释放的影响.结果表明,钝化剂(PAM+聚铝)有显著的抑制沉积物的磷释放和捕捉上覆水中含磷颗粒的效果.加钝化剂后,上覆水的总磷(TP)、溶解性总磷(DTP)和溶解性无机磷(DIP)分别比未加钝化剂组低50.0%～89.8%,85.5%～97.9%和96.5%～100.0%.扰动促进了沉积物的磷释放,这是因为扰动导致泥水混合程度增加;扰动导致沉积物氧化还原状态的改变.5d后扰动组的磷开始释放,而未扰动组在第52d仍未释放.沉积物中释放的磷主要是磷酸盐.扰动促进了DIP的释放,扰动后DTP/TP、DIP/DTP及DIP/TP均增加.投加的铝盐的量在试验期间导致的上覆水中残余铝的含量在安全范围内.扰动对上覆水中残余铝的含量影响不大.     

河蚬或藻存在下组合扰动对内源磷迁移的影响

为阐明河蚬(Corbicula fluminea)或铜绿微囊藻(Microcystis aeruginosa)存在下,物理和摇蚊幼虫组合扰动对内源磷再生和迁移转化的影响,以太湖梅梁湾上覆水和沉积物为研究对象,分析了上覆水、间隙水、沉积物中不同形态磷的变化规律.结果表明,与摇蚊幼虫扰动和组合扰动相比,河蚬或藻类的出现都会使得上覆水中不同形态磷(总磷、溶解性总磷、溶解性磷酸盐、颗粒态磷)显著增加.河蚬或藻类均导致间隙水DIP明显降低,并致使DIP峰值区域向更深处迁移(3~4cm变为4~5cm),而对照试验则相反.与对照试验相比,河蚬或藻存在下组合扰动均导致0~4cm沉积物NH₄Cl-P含量及其占总磷百分比降低,Fe/Al-P含量及其占总磷百分比增加,并且河蚬或藻对NH₄Cl-P降低和Fe/Al-P增加的影响基本一致.在多种扰动因素存下,摇蚊幼虫对上覆水中DTP和DIP贡献最大,后者可能源于摇蚊幼虫显著降低了间隙水中DIP含量及沉积物中NH₄Cl-P含量.这暗示了在组合扰动基础上叠加河蚬或者藻类,均进一步促进了内源磷再生和迁移.     

静止和水动力扰动状态下锆改性沸石添加对河道底泥磷迁移转化的影响

通过底泥培养实验,并采用磷形态分级提取方法对底泥进行分析,研究了静止和水动力扰动这2种状态下锆改性沸石添加对不同深度处底泥中磷迁移和形态转化的影响.结果表明,无论是在静止还是在水动力扰动状态下,锆改性沸石添加均不仅降低了上覆水中溶解态活性磷(SRP)质量浓度,而且降低了不同深度处间隙水中SRP的质量浓度,并且还降低了底泥-上覆水界面SRP扩散通量.此外,当不存在和存在水动力扰动作用时,向表层底泥(0～10 mm)中添加锆改性沸石,不仅促使添加层中氧化还原敏感态磷(BD-P)和盐酸提取态磷(HCl~-P)向金属氧化物结合态磷(Na OH-rP)和残渣态磷(Res-P)极大转变,降低了添加层中潜在可移动态磷(Mobile-P)含量,而且还降低了添加层下方底泥(10～20 mm)中Mobile-P含量.与静止状态相比,水动力扰动状态下锆改性沸石添加对河道底泥磷迁移转化的影响规律存在一定的差异.水动力扰动虽然可以增强锆改性沸石添加对表层底泥间隙水中SRP的钝化效果,以及对底泥-上覆水界面SRP扩散通量的削减效应,但是却会略微降低锆改性沸石添加控制底泥中磷向上覆水体中释放的效率.表层底泥中潜在可移动态磷含量、不同深度处间隙水中SRP的质量浓度以及底泥-水界面SRP扩散通量的下降,对于锆改性沸石改良技术控制底泥磷向上覆水体释放至关重要.以上结果说明,无论是在静止还是在水动力扰动状态下,锆改性沸石添加均可以有效地控制河道底泥中磷向上覆水体的释放.     

几种不同稳定剂抑制河流底泥释磷效果的初步研究

以上海苏州河支流——蒲汇塘的富磷底泥为试验对象,研究高锰酸钾、双氧水、过氧化钙和硝酸钙4种稳定剂对底泥中磷元素释放的抑制效果。结果表明:高锰酸钾和双氧水对磷的抑制作用持续时间较短,过氧化钙能够快速将底泥的NaOH-P转化为永久性HCI-P,而硝酸钙对磷的转化速度相对较为缓慢;投加过氧化钙可以将孔隙水中正磷酸根的浓度从2.815 mg/L降低至0.003mg/L.硝酸钙也可将其值从2.813 mg/L降至0.094mg/L;经过氧化钙和硝酸钙处理后,上覆水总磷含量分别可达到0.029mg/L和0.028mg/L,能够满足国家地表Ⅱ类水质要求。因此,过氧化钙和硝酸钙可以作为抑制底泥磷释放的稳定剂使用。     

稳定剂控制底泥中磷元素释放的机理性研究

以河流富磷底泥为试验对象,研究4 种稳定剂对底泥磷元素释放的抑制效果和机理.结果表明,高锰酸钾和过氧化氢控制底泥释磷的持续性较差,投加高锰酸钾后底泥孔隙水的正磷酸根含量比对照高出0.344mg/L,过氧化钙和硝酸钙能够稳定地抑制底泥中磷的释放,可将孔隙水磷酸盐浓度分别降低至0.003,0.094mg/L.高锰酸钾和过氧化氢不能有效地降低底泥中NaOH-P 含量,过氧化钙和硝酸钙主要通过提高HCl-P 含量来控制磷的释放.     

过氧化钙(CaO2)联合生物炭对河道底泥的修复

底泥内源污染是导致河道黑臭反复的主要因素.为防止河道黑臭现象反复,以无锡市滨湖区某一河道为实验地点,采用CaO₂联合生物炭原位覆盖技术修复黑臭河道底泥,研究了该技术对泥水水质、底泥酸挥发性硫化物(AVS)和磷形态以及微生物的影响,探究该技术对黑臭底泥修复效果.结果表明, CaO₂联合生物炭覆盖可显著提高泥水体系溶解氧(DO)浓度和氧化还原电位(ORP),其中上覆水DO浓度和ORP分别保持在2 mg·L^-1和50 mV以上.间隙水氨氮(NH⁺₄-N)、化学需氧量(COD)和总磷(TP)去除率分别达到了43.40%、 41.18%和50.97%.底泥AVS去除率达到了37.03%,高通量测序表明,底泥厌氧微生物相对丰度明显降低,出现热单胞菌属(Thermomonas)、Dechloromonas、变形菌属(Proteus hauser)、脱硫微菌属(Desulfomicrobium)和硫杆菌属(Thiobacillus)等脱氮除硫菌群.底泥中磷转化为稳定的铁铝结合态磷和钙结合态磷....     

太湖竺山湾污染底泥环保疏浚深度的推算

根据颜色、气味、粒径、黏稠度等理化指标,将太湖竺山湾柱状底泥样品由上至下依次分为氧化层(A)、污染层(B)、污染过渡上层(C1)、污染过渡下层(C2)和健康层(D).通过对底泥中氨氮、总磷、总氮和烧失量垂直分布规律的分析,结合柱状底泥各分层氮、磷吸附/解吸实验,推算出竺山湾污染底泥环保疏浚层及其深度.结果表明,底泥中氨氮、总磷、总氮和烧失量含量随深度的增加呈下降趋势.A层和B层中污染物含量明显高于其他层;无机磷吸附/解吸平衡浓度随深度的增加而下降,在C1层与C2层间出现拐点;而氨氮的吸附/解吸平衡浓度变化趋势较复杂.结合上覆水中无机磷与氨氮浓度,推算出竺山湾底泥环保疏浚层次为C1层,疏浚平均深度为0.40~0.70m.     

灼烧净水污泥投加方式对磷吸附和磷形态的影响

以灼烧净水污泥为研究对象,探讨在其不同投加方式(混匀和覆盖)下,各底泥对外源磷的吸附效果以及间隙水和底泥中各形态磷的数量分布.结果表明,相比未灼烧净水污泥,灼烧净水污泥对磷的吸附能力显著改善,磷最大吸附量(Smax)提高了43.7%、底泥磷平衡浓度(EPC0)降低69.1%、磷饱和度(DPS)降低54.4%.混匀和覆盖对上覆水中磷消失的贡献率几乎一致,但明显高于对照实验.但如果考虑灼烧净水污泥与上覆水的接触几率,则混匀条件下,单位净水污泥对磷的吸附量为覆盖条件下的2.3倍.覆盖条件下,间隙水(1~2 cm)中溶解性磷酸盐浓度是混匀条件的33.17倍(平均值),这主要源于覆盖导致溶解氧渗透深度明显降低.混匀条件下,外源磷更易形成Ca-P,而覆盖条件下,易释放的NH_4Cl-P和Fe/Al-P占比更多,这暗示了混匀对底泥微环境的改造更有利于外源磷的吸附和内源磷的持留.     

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.