曝晒位置对纯铜热带海洋大气环境腐蚀性能的影响研究

目的研究不同离岸曝晒位置对纯铜热带海洋大气环境腐蚀性能的影响。方法通过对T2铜在三亚热带海滨离岸不同距离进行24个月的大气曝晒试验,结合大气Cl~-在相应位置的沉积量及湿度变化情况,并采用扫描电子显微镜、X射线能谱仪和XRD等对其腐蚀产物形貌、成分和物相进行分析。结果 T2铜热带海洋大气腐蚀以均匀腐蚀为主,其平均腐蚀速率随离岸距离的增加、曝晒时间的延长而下降。腐蚀产物为双层结构,外层为具有疏松结构的绿色Cu_2(OH)_3Cl,内层为致密的Cu_2O。随着离岸距离的增加、暴露时间的延长,试样表面电解液介质中Cl~-浓度越大,T2铜腐蚀产物中Cu_2(OH)_3Cl含量增加,但腐蚀产物生成主要以Cu_2O相为主。结论腐蚀速率与盐雾沉积量与离岸距离变化关系存在差异,盐雾沉积量先升后降,在离岸80 m处有最大值,由于大气相对湿度的影响,导致T2铜腐蚀速率在离岸0 m处有最大值,在离岸80 m处有极大值。     

D60钢在模拟海岛环境中腐蚀产物的红外光谱研究

目的以弹药金属元件的主要材料之一D60钢为样品,在模拟海岛环境的高湿、高盐雾条件下研究D60钢的腐蚀过程。方法利用红外光谱法(IR)对腐蚀产物进行表征。结果腐蚀层中含有吸附水,在腐蚀的初期,腐蚀产物主要有γ-Fe OOH和δ-Fe OOH,但是随着腐蚀的继续,产物中出现α-Fe OOH,同时δ-Fe OOH逐渐减少至完全消失,在腐蚀的后期出现了Fe3O4,有Cl-参与下的腐蚀,腐蚀产物主要有α-Fe OOH,γ-Fe OOH和部分少量的δ-Fe OOH。结论 Cl-的加入加速了基体金属的腐蚀。     

锌在模拟工业大气环境下的腐蚀行为研究

目的研究不同时间下锌在SO2环境中的腐蚀特性。方法采用室内加速试验法,向大气加速腐蚀箱中通入25 mg/L SO2气体,进行模拟工业大气环境下的加速腐蚀试验。对腐蚀后金属材料进行质量增量测量和电化学测试,通过XRD,SEM等表征锌腐蚀产物及腐蚀形貌,研究腐蚀特性。结果初期阶段锌在SO2环境中的腐蚀速率逐渐增加,到腐蚀后期逐渐降低,1/Rct值先增大后减小,锌的腐蚀产物中的元素包括Zn,O和少量的S,主要产物为Zn4SO4(OH)6。结论初期在锌表面生成的腐蚀产物疏松,SO2能够通过产物层到达基体,促进腐蚀,不具有保护性。到后期,产物增多并且致密使SO2与基体接触的概率降低,从而使腐蚀速率减缓。     

P265GH低合金钢在模拟污染大气环境中的腐蚀行为

目的研究P265GH钢在模拟污染大气环境中的腐蚀行为,探讨Na HSO3和Na Cl的协同作用对P265GH钢大气腐蚀影响。方法利用SEM,XRD和FTIR技术以及腐蚀质量损失分析。结果在Na HSO3存在的环境中,α-Fe OOH易于形成,而在Na Cl存在的环境中,γ-Fe2O3和Fe3O4易于形成,两者同时存在的环境中,P265GH钢腐蚀质量损失比单一腐蚀介质存在时的质量损失大。结论Na HSO3和Na Cl之间存在协同效应,腐蚀介质对P265GH钢腐蚀影响顺序为Na HSO3+Na Cl>Na HSO3>Na Cl。     

SO2在碳钢初期大气腐蚀中的作用

通过自建的模拟大气腐蚀系统,借助金相显微镜、扫描电镜(SEM/EDX)、X-射线衍射(XRD)和x-射线光电子能谱(XPS),研究了SO2对碳钢初期大气腐蚀行为的影响,并进一步用原子力显微镜从更微观的角度观察了在SO2环境中初期阶段腐蚀形貌变化.研究结果表明:在SO2污染大气环境中,随SO2浓度的升高碳钢腐蚀加快.在体积分数为5×10(-6)SO2的大气环境中,碳钢和耐候钢表面腐蚀主要以条状物生长,随着SO2浓度的升高,腐蚀产物的形貌发生改变,在体积分数为5×10(-5)SO2的大气环境中,条状锈和胞状锈同时生长.在锈层中S元素以FeSO4·4H2O的形式存在,腐蚀产物中还有γ-FeOOH.SO2在初期阶段加速了碳钢的腐蚀,降低了碳钢的耐蚀性.     

电镀锌镍合金与热渗锌涂层热带海洋大气环境腐蚀规律对比分析

目的 解决钢铁表面金属涂层在热带海洋大气环境中易腐蚀损伤或失效的问题,选择对热带海洋大气环境耐腐蚀性能优良的金属涂层,提高钢铁工件的使用寿命。方法 在某热带海域进行户外暴露试验,对钢铁试片电镀锌镍合金和热渗锌2种金属涂层的腐蚀规律进行研究。通过扫描电镜、X射线能谱仪、光学显微镜、划格试验等,对锌镍合金镀层和热渗锌涂层的表面形貌、化学成分、截面形貌、涂层厚度及附着力等分别进行观察与测试。结果 电镀锌镍合金镀层主要发生选择性腐蚀和点蚀,在720d内具有较好的腐蚀防护性能。热渗锌层以均匀腐蚀为主,涂层微裂纹促进了腐蚀,在90 d内基体无腐蚀,360～720 d涂层的腐蚀速率较快。结论 在采用的2种金属涂层工艺中,电镀锌镍合金镀层的耐腐蚀性能远优于热渗锌涂层。相对于该热渗锌涂层,电镀锌镍合金镀层更加适合作为钢铁工件金属涂层在该海域大气环境中长期使用。     

铝在红沿河核电厂地区的初期大气腐蚀表征

目的研究铝在辽宁红沿河核电厂地区的初期大气腐蚀行为。方法按GB/T 6464—1997,将制备好的试样在红沿河核电厂进行大气暴露试验,利用XRD,FTIR,SEM分析技术,对试验6个月和10个月的试样进行腐蚀产物观察与分析。结果铝在红沿河大气暴露腐蚀6个月和10个月样品表面均布满了点蚀坑、腐蚀产物及沉积物,腐蚀产物主要为Al2O3,Al OOH以及一些含氯和含硫的铝盐。腐蚀产物都较疏松,上下表面均有龟裂纹,相邻较近的点蚀坑已相互连接。随腐蚀时间延长,点蚀坑变深变大,朝地面点蚀坑深度已达上百微米。结论铝在红沿河核电厂大气环境中腐蚀以点蚀为主要特征,其腐蚀比普通大气环境中的严重,朝地面的腐蚀比朝天面严重,大气中氯离子及SO2参与铝的腐蚀过程并起促进作用。     

安徽省内电网设备常用钢材大气腐蚀试验研究

目的针对在安徽省内H1、R1及T28三个站点自然环境下暴露1年后的Q235、40Cr及镀锌钢,开展腐蚀速率、腐蚀产物及腐蚀层形貌的研究,探讨其大气腐蚀机理。方法采用称量法计算腐蚀质量损失,通过光学及电子显微镜法观察腐蚀层表面及截面形貌,用电子能谱仪测试微区成分,用X-射线衍射法测试腐蚀层的物相构成。结果 Q235、40Cr的大气腐蚀产物为Fe OOH、Fe3O4、Fe(OH)3及FeSO4,镀锌钢则为Zn O及Zn SO4。Q235、40Cr腐蚀层表面分布着绒球状的α-FeOOH及片状的γ-FeOOH,镀锌钢大气腐蚀层致密,但T28站点镀锌钢表面形成点状的腐蚀坑,腐蚀防护能力降低。结论同一站点三种钢腐蚀速率大小次序为40CrQ235镀锌钢,站点R1钢的腐蚀速率最大,站点T28的腐蚀速率最小。     

30CrMnSiA高强钢在工业和海洋大气环境中的腐蚀行为研究

目的为30CrMnSiA高强钢的大气腐蚀防护设计、应用范围扩展和开发新钢种提供有益的借鉴和参考。方法采用腐蚀质量损失、XRD和SEM研究了30CrMnSiA高强钢在工业和海洋大气环境暴露60个月的大气腐蚀行为。结果 30CrMnSiA高强钢在工业和海洋大气环境中腐蚀质量损失随暴露时间变化的双对数函数分别是lgΔw=2.245+0.387lg t和lgΔw=2.822+0.637lg t。纤铁矿和针铁矿是两种大气环境中形成的腐蚀锈层的主要成分,除了纤铁矿和针铁矿外,在海洋大气环境形成的锈层中还发现了四方纤铁矿。随着暴露时间的延长,在海洋大气环境中形成的锈层呈现逐渐剥落的趋势。结论 30CrMnSiA高强钢在海洋大气环境中表现出较高的腐蚀敏感性,在工业大气环境中表现出较低的腐蚀敏感性。     

氯化铵盐粒导致的铜初期大气腐蚀行为研究

目的研究在氯化铵存在条件下,铜的大气腐蚀行为。方法采用扫描电子显微镜(SEM)、能谱(EDS)、傅里叶红外光谱(FT-IR)、X射线衍射(XRD)、滴定法和电化学等方法来确定铜的大气腐蚀过程和腐蚀产物。结果随着暴露时间的延长,铜的腐蚀质量损失变大,平均腐蚀速率变小。在氯化铵存在条件下,铜表面生成了Cu_2O、Cu_2(OH)_3Cl和Cu_2(OH)_2CO_3,其中Cu_2O为主要腐蚀产物,其质量占腐蚀产物总质量的97%以上。结论氯化铵的存在会对铜造成很强的腐蚀,随着暴露时间的延长,铜的腐蚀变得严重,但是暴露后期腐蚀速率将会减缓。     

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.     

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.     

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.     

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.     

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.     

Organochlorine pesticides in soils under different land usage in the Taihu Lake region, China

A field study was conducted in the Taihu Lake region, China in 2004 to reveal the organochlorine pesticide concentrations in soils after the ban of these substances in the year 1983. Thirteen organochlorine pesticides (OCPs) were analyzed in soils from paddy field, tree land and fallow land. Total organochlorine pesticide residues were higher in agricultural soils than in uncultivated fallow land soils. Among all the pesticides, ΣDDX (DDD, DDE and DDT) had the highest concentration for all the soil samples, ranging from 3.10 ng/g to 166.55 ng/g with a mean value of 57.04 ng/g and followed by ΣHCH, ranging from 0.73 ng/g to 60.97 ng/g with a mean value of 24.06 ng/g. Dieldrin, endrin, HCB and α-endosulfan were also found in soils with less than 15 ng/g. Ratios of p,p'-(DDD DDE)/DDT in soils under three land usages were: paddy field ＞ tree land ＞ fallow land, indicating that land usage inlfuenced the degradation of DDT in soils. Ratios of p,p'-(DDD DDE)/DDT ＞1, showing aged residues of DDTs in soils of the Taihu Lake region. The results were discussed with data from a former study that showed very low actual concentrations of HCH and DDT in soils in the Taihu Lake region, but according to the chemical half-lives and their concentrations in soils in 1980s, the concentration of DDT in soils seemed to be underestimated. In any case our data show that the ban on the use of HCH and DDT resulted in a tremendous reduction of these pesticide residues in soils, but there are still high amounts of pesticide residues in soils, which need more remediation processes.     

Alterations of organ histopathology and metallolhionein mRNA expression in silver barb, Puntius gonionotus during subchronic cadmium exposure

Common silver barb,Puntius gonionotus,exposed to the nominal concentration of 0.06 mg/L Cd for 60 d,were assessed for histopathological alterations(gills,liver and kidney),metal accumulation,and metallothionein(MT)mRNA expression.Fish exhibited pathological symptoms such as hypertrophy and hyperplasia of primary and secondary gill lamellae,vacuolization in hepatocytes,and prominent tubular and glomerular damage in the kidney.In addition,kidney accumulated the highest content of cadmium,more than gills and liver.Expression of MT mRNA was increased in both liver and kidney of treated fish.Hepatic MT levels remained high after fish were removed to Cd-free water.In contrast,MT expression in kidney was peaked after 28 d of treatment and drastically dropped when fish were removed to Cd-free water.The high concentrations of Cd in hepatic tissues indicated an accumulation site or permanent damage on this tissue.