石河子市土壤环境磁学特征及空间分布研究

以干旱区新兴绿洲城市石河子市为研究区,采集80个(0~10 cm)表层土壤样品,运用环境磁学方法,对土壤磁性矿物的含量、组成和粒度等参数进行了详细测定和分析.结果表明,石河子市表层土壤磁性特征以亚铁磁性的多畴磁铁矿或磁赤铁矿为主导,同时伴有少量的不完全反铁磁性矿物;从空间分布来看,亚铁磁性矿物含量表现为北部新城区>中心城区>郊区农用地;而磁性矿物颗粒粒度大小依次为北部新城区>郊区农用地>中心城区.磁性矿物的高浓度区与大多数工厂的分布具有一致性;但重化工业集中区(N1~N7)却表现为磁性矿物浓度较低,同时磁性颗粒粒径较大.在研究区内质量磁化(χLF)、饱和等温剩磁(SIRM)和软剩磁(SOFT)是指示工业所在区的有效磁性参数指标,而在化工业集中区需结合磁性粒度参数χFD%进行判别.     

武汉市道路尘埃污染中磁学指标与重金属含量对比

对武汉市不同功能区的道路尘埃进行环境磁学和化学分析的综合研究.结果显示:尘埃中的磁性矿物含量在空间分布上具有较大的差异,平均磁化率为工业区(7.36×10~(-6)m~3/kg)交通沿线(5.38×10~(-6)m~3/kg)商业区(3.76×10~(-6)m~3/kg)开发区(2.26×10~(-6)m~3/kg)和风景区(2.48×10~(-6)m~3/kg).工业活动和交通因素是造成区域尘埃中磁性矿物含量升高的主要原因,地理位置和人口密度对尘埃中磁性矿物的含量也有一定的影响.岩石磁学研究结果表明:尘埃中的磁性载体以亚铁磁性矿物为主,部分样品中含有不完整反铁磁性矿物.扫描电镜和能谱分析显示:人类活动产生的磁性颗粒(铁的氧化物和铁的硅铝酸盐)一般呈球形,自然成土过程中形成的不规则状磁性颗粒(磁赤铁矿).污染负荷指数与磁化率(R~2=0.870)、饱和等温剩磁(R~2=0.665)等表征磁性矿物含量的参数呈显著正相关.因此,尘埃的磁学参数可以作为重金属含量的参考指标.     

天山北麓宁家河阶地上的黄土堆积及其磁学特征

本文报道了新疆地区天山北麓宁家河阶地上的黄土堆积。研究剖面的两层黄土为河流 砾石层所隔开,这在新疆地区较为少见。通过系统的岩石磁学和粒度测量,分析了该剖面两层 黄土的磁学特征,并初步探讨磁化率变化机制。结果表明：黄土中的主要磁性矿物为磁铁矿和 磁赤铁矿,并含有少量赤铁矿和针铁矿。亚铁磁性矿物主要以多畴（MD）、假单畴（PSD）颗 粒为主,反映了这一地区极弱的成土作用。砾石层上下两层黄土磁学性质存在着差异,表现为 上层黄土具有较高的磁性矿物含量、较粗的磁颗粒和相对含量较高的软磁性矿物。下层黄土受 到后期河水的改造可能是导致这些差异的原因。磁化率与粒度呈现较好的正相关关系,与黄土 高原的情况相反,说明干旱地区的黄土磁学性质主要受原生磁性矿物控制。搬运风力和源区变 化是磁化率变化的主导因素。     

新疆喀纳斯景区土壤剖面磁学特征研究

文章以新疆喀纳斯景区为研究区,采集4条深度为100 cm土壤垂直剖面,进行了土壤磁学特征分析。结果表明:研究区土壤磁性矿物含量整体较低,低矫顽力亚铁磁性矿物主导了样品的磁学特征,并含有少量不完整反铁磁性矿物,土壤磁性颗粒以多畴和稳定单畴粗颗粒为主;土壤磁性特征垂向变化为先增加后减少继而继续增加的趋势,表土层中存在较少的细黏滞性超顺磁性(SP)颗粒,随深度的增加,SP颗粒逐渐减少;景区土壤表土层反映了自然成土因素和人为因素2种来源的磁性特征,底土层磁性增强反映出基岩母质对土壤磁性的贡献。     

准噶尔盆地南缘黄土磁化率变化规律及影响因素

准噶尔盆地南缘柏杨河典型风成黄土剖面的岩石磁学与粒度研究结果指示该地区黄土磁 性矿物以亚铁磁性矿物为主,主要载磁矿物为粗粒原生强磁性矿物,同时含有少量细粒磁性矿物, 磁性矿物含量远低于黄土高原黄土。磁性矿物磁晶粒度以假单畴和多畴（PSD/MD）为主,后期 成壤过程对磁性矿物颗粒的改造作用很小。柏杨河黄土磁化率增强机制较为复杂,磁学与粒度 的曲线对比表明风动力强度对含磁性矿物较粗颗粒具有分选作用,是导致磁化率变化的重要因 素,但二者的低相关性又暗示了风动力强度在解释磁化率增强机制中的局限性。古尔班通古特 沙漠在末次间冰期以来的收缩与扩张导致的物源变化可能是影响磁化率变化的又一重要因素。     

新疆天山天池景区道路土壤磁学特征及其环境意义

为验证利用环境磁学方法监测旅游景区道路土壤污染的可行性,以新疆天山天池景区为研究区,采集不同道路土壤样品72件,并对其进行系统的磁学特征分析.结果表明:景区道路土壤样品磁性矿物含量适中,以亚铁磁性矿物(磁铁矿)为主,同时伴有少量不完全反铁磁性矿物;土壤磁性颗粒以多畴(MD)和稳定单畴(SSD)粗颗粒为主,且含有少量超顺磁性细颗粒(SP);从双因素方差分析结果看,不同位置道路土壤样品的磁性参数(χ_(LF)、SIRM、SOFT、χ_(FD)、SIRM/χ_(LF))和距离道路不同距离土壤样品的磁性参数(χ_(LF)、SIRM、SOFT、S_(-ratio))之间均存在显著性差异;景区旅游交通流量和距离道路远近、自然成土过程等人为和自然因素是影响景区道路土壤磁性特征变化的关键因素.     

西北干旱区农田土壤磁性特征及其环境意义

为探究环境磁学方法在西北干旱区农田土壤污染监测中的可行性,以典型绿洲农业区张掖市(临泽县、甘州区、民乐县和山丹县)为研究区域,采集农田土壤样品102份并对其进行系统的环境磁学分析.结果表明,张掖市农田土壤磁性特征以亚铁磁性的磁铁矿为主导,磁晶颗粒主要为粗粒假单畴(PSD)和多畴(MD),颗粒等效粒径介于0.2~1μm之间;样品磁化率(χlf)变化范围为22.27×10~(-8)~188.36×10~(-8)m~3·kg~(-1),平均值为63.85×10~(-8)m~3·kg~(-1),磁性矿物含量总体较少但空间变化较大;磁参数空间分布表明,磁性矿物含量在甘州区、民乐县和山丹县高于临泽县,并在甘州区的中部、民乐县的西南边和山丹县的西边呈现相对高值;甘州区中部的磁性高值主要受控于工业生产等人类活动,民乐县西南边和山丹县西边的磁性高值主要与较强的自然成土作用有关.综合多种磁学参数的系统分析能够有效区分和划定农田土壤人为污染范围,为农田土壤污染防治工作提供依据.     

兰州市街道尘埃磁学特征及其环境意义

兰州市是全球大气污染最为严重的城市之一,为城市颗粒物污染研究的理想场所.分析了兰州市街道尘埃样品的磁学参数(包括磁化率、无磁滞磁化率、等温剩磁、磁滞回线和热磁曲线)变化特征.结果表明,兰州市街道尘埃中磁性矿物含量较高,主要磁性矿物是铁磁矿、磁赤铁矿和赤铁矿,并伴有少量顺磁性矿物;磁性矿物粒度主要是准单畴（PSD）;市区污染春季较夏季严重,春季高频率的强沙尘暴可能带来了更多的磁性矿物;兰州市污染物的沉积和分布在很大程度上受到气象条件和地形地貌格局的影响,市区每个盆地东端高于其它地区;兰州市污染以人为活动产物为主,人为活动贡献约为81.9%,其中包含交通约22.6%的贡献,自然降尘贡献约为18.1%;特殊的地形和气象条件,使得兰州市区的大气环境容量比平原城市的环境容量小得多,进而导致严重的大气污染.     

兰州市城区河道表层沉积物磁性特征研究

通过系统的环境磁学测定,分析了兰州市城区河道表层沉积物的磁学性质及其对城市污染的指示意义.结果表明,兰州市城区河道表层沉积物样品磁性特征以亚铁磁性矿物的磁铁矿为主导,同时存在少量赤铁矿和针铁矿贡献.根据参数χFD、χARM、χFD/MS和χARM/MS所指示的人为活动排放物对不同河段沉积物的贡献量将兰州市河流分为3类:末端集中型(排洪沟、寺儿沟、鱼儿沟、水磨沟),源头集中型(七里河、烂泥沟),影响较小型(罗锅沟、大沙沟).与有机质测量结果比较发现,兰州市河道沉积物样品有机质含量与超顺磁颗粒及单畴晶粒具有十分显著的正相关关系,说明了细颗粒磁性矿物对有机碳的富集作用,显示了超顺磁颗粒及单畴颗粒含量作为兰州市城区河道表层沉积物有机质含量的代用指标具有良好的指示意义.     

克拉玛依城市土壤的环境磁学特征研究

对克拉玛依市土壤环境磁学特征进行研究,并探讨土壤磁性增强的机制。结果表明:低频质量磁化率(χLF)在不同用地上依次表现为:交通运输用地商业用地林地公共设施用地未建设用地居住用地。交通运输用地、公共设施用地较居住用地、非建设用地的土壤以低矫顽力的亚铁磁性矿物含量较高和少量不完全反铁磁性矿物,且磁性颗粒以多畴(MD)颗粒为主,含少量的单畴(SP)颗粒和稳定单畴(SSD)颗粒,与交通运输用地、公共设施用地受到汽车尾气和其他人为活动产生的污染物中含有大量的粗颗粒亚铁磁性矿物密切相关。     

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.