分光光度法测定底质总磷的方法探讨

在一定条件下,用硫酸和过氧化氢进行消解,使不溶性磷酸盐和有机磷转化为正磷酸盐,待测液与钼酸盐反应生成磷钼杂多酸,加入还原剂抗坏血酸后转变成蓝色络合物,进行比色测定。实验表明,该方法回收率为93．4％～99．7％,检出限为0．009mg／L,RSD为4．0％。方法简便、可靠,能满足环境监测底质总磷分析的需要。     

城市污泥中总磷的测定方法研究

采用过硫酸钾法高压消解污泥样品,使污泥中舍磷化合物全部转化为可溶性的正磷酸盐,在酸性介质中,正磷酸盐与钼酸铵反应,在锑盐存在下生成磷钼杂多酸后,被抗坏血酸还原生成蓝色络舍物,在700nm波长下测定吸光度,求出污泥中的总磷含量。实验表明,采用过硫酸钾消解法污泥样品消解完全,平行性好,准确度高,能够满足城市污泥总磷的测定需要。     

流动注射分析法测定水中的总磷

应用LACHATQC8500型三通道流动注射分析仪,采用过硫酸钾在线紫外消解不同形态的磷,使其转化为磷酸盐。正磷酸盐与钼酸铵和酒石酸锑钾反应,生成磷钼化合物。此磷钼化合物被抗坏血酸还原,形成蓝色化合物,它在880nm处有吸收。仪器检出限为0.0012mg/L,线性范围为0.05～1mg/L(r>0.9990),加标回收率为95.0%～104%。与GB11893-89钼酸铵分光光度法比较,其结果无显著差异。实验结果表明,该方法简便、快速、准确,适用于水中总磷的测定。     

散装化肥和农药洗舱废水中总磷的测定

本文叙述了高氯酸硝酸消解分光光度法测定装有化肥、农药等含磷货物的船舶洗舱废水中总磷的方法。此法是将样品先用高氯酸—硝酸消解,使溶液中焦磷酸盐、偏磷酸盐、多磷酸盐和各种有机磷物质转化成正磷酸盐,在酸性介质中正磷酸盐与钼酸铵反应,生成物经还原生成一种蓝色的化合物,随后用分光光度法测定。溶液中的总磷浓度为0.09～0.64mg/l等,相对偏差为2～5%,回收率95%～105%,本方法检测限是0.022mg/l。经七个港口监测站进行方法验证,结果较满意。     

人工湿地常用生物陶粒基质LDHs覆膜改性及其除磷效果研究

分别利用3种二价金属化合物和3种三价金属化合物,采用水热共沉淀法在碱性条件下对人工湿地中常用的生物陶粒基质进行层状双金属氢氧化物(LDHs)覆膜改性,并将9种不同类型的LDHs覆膜改性生物陶粒基质和普通生物陶粒基质分别填充于10个垂直流人工湿地模拟实验柱中,进行除磷净化实验.结果表明,9种不同类型的改性生物陶粒基质均能有效提高磷素的净化效果;Zn系LDHs改性生物陶粒对总磷、溶解性总磷、磷酸盐均有很好的处理效果,其中Zn Fe-LDHs、Zn Co-LDHs和Zn Al-LDHs对总磷的平均去除率均在92%以上,对溶解性总磷和磷酸盐的平均去除率均超过95%;其对磷素的净化机理主要集中于物理化学作用,同时还应与其对微生物生长的促进作用有关.     

磷酸盐对土壤吸附一硫代砷的影响

通过设计批实验和表征分析,探究不同浓度的磷酸盐影响下,一硫代砷酸盐（MTA）在土壤上的吸附特征和机理.结果发现,Elovich动力学模型和Langmuir等温吸附模型可较好地拟合MTA在土壤中的吸附过程,相关系数R²分别为0.983和0.994,表明土壤吸附MTA发生在局部位置,吸附过程主要以非均相扩散为主,拟合所得最大单层吸附量为254.214mg/kg.MTA与磷酸盐共存时,随着溶液中磷酸盐初始浓度的增大,土壤对MTA的平衡吸附量逐渐下降,对磷酸盐的吸附量逐渐增大;SEM-EDS结果表明无论是否添加磷酸盐,反应后的土壤表面都能检测到少量As,但添加磷酸盐条件下土壤表面的As含量则相对较低,证实磷酸盐的存在降低了土壤对MTA的吸附;XRD结果表明MTA能与土壤中的铁铝矿物发生络合反应生成内球络合物－[2Al （H₂AsO₄）₃]、≡Al₂O₂AsO （SH）和－[2Fe （H₂AsO₄）₃],而磷酸盐会与土壤表面的羟基形成内球络合物,导致土壤对MTA的吸附能力减弱.     

硫酸亚铁结合电化学絮凝处理中水氨氮与总磷的研究

文章分别采用硫酸亚铁絮凝法、电化学法以及硫酸亚铁结合电化学法对中水中低浓度氨氮和总磷的处理效果进行了对比。研究了硫酸亚铁投加量、pH、通电时间和电压对氨氮和总磷去除率的影响。结果表明:采用硫酸亚铁絮凝法,硫酸亚铁投加量为6%,pH为6～7,氨氮去除率为95.45%,总磷去除率92.5%;采用电化学絮凝法,通电时间40 min,通电电压20 V,pH为6～7,中水中氨氮去除率为72.73%,总磷去除率为92.5%;硫酸亚铁结合电化学处理中水,通电电压为20 V,通电时间30 min,硫酸亚铁投加量7%时,中水中氨氮去除率99.09%,总磷去除率92.5%。因为氨直接在阳极失去3个电子被氧化成N2,阳极电解时生成的金属阳离子或其水合物与水中的磷酸盐形成沉淀。而硫酸亚铁通过空轨道吸附铵根中氮的孤对电子后被水解生成的含有Fe3+的羟基络合物絮凝沉淀,Fe2+和Fe3+也都可以与PO43-生成难溶性磷酸盐。     

层状双金属氢氧化物覆膜改性人工湿地无烟煤基质除磷

分别选取MgCl2、ZnCl2、CaCl2、CoCl3、FeCl3、AlCl3等6种金属化合物合成9种不同类型层状双金属氢氧化物(LDHs),利用其对垂直流人工湿地无烟煤基质进行LDHs覆膜改性;构建模拟基质试验柱,对改性前后的无烟煤基质进行模拟垂直流人工湿地净化污水试验.结果表明:相对于原始无烟煤基质,各种LDHs覆膜改性基质对总磷、溶解性总磷、颗粒态磷和磷酸盐的去除率均有不同程度的提高;Zn2+参与合成的改性基质对总磷、溶解性总磷、颗粒态磷和磷酸盐均有很好的去除效果,其中ZnCo-LDHs和ZnAl-LDHs改性基质对总磷和溶解性总磷的平均去除率超过95%,对磷酸盐平均去除率达到98%以上.     

洪泽湖表层底质营养盐的形态分布特征与评价

为揭示洪泽湖底质的营养盐空间分布特征,于2008年6月采集了该湖具有代表性的10个点位的表层底质,测定了其有机质、总氮、有机氮、氨氮、硝氮、总磷、无机磷、铁铝-磷、钙-磷等的含量.结果表明,底质中的有机质和总氮有很好的相关性,且有机氮约占总氮的90%,说明碳、氮有同源性;底质中的无机磷约占总磷的70%,而其中钙-磷占无机磷的比重较大;洪泽湖底质有机质与总氮,有机氮,总磷的空间分布特性极为相似,属洪水冲刷型堆积模式(Turbidity Flood Model方式);通过C/N域值得知沉积物中有机物主要来源为生物沉降.通过用有机指数评价法和有机氮评价法对洪泽湖表层底质的分析表明,洪泽湖底质除局部区域如龙集乡北表现为一定程度的有机氮污染外,整体处于清洁至尚清洁范畴.     

长江中下游浅水湖泊沉积物对磷的吸附特征

研究了长江中下游浅水湖泊1 1个沉积物对磷的吸附等温线及其吸附动力学,并分析了沉积物理化特征对磷吸附特征的影响,研究发现:①沉积物对磷酸盐的吸附主要在前1 0h内完成,在0.5h内吸附反应十分迅速,并逐渐达到吸附平衡;②沉积物本底吸附态磷与其有机质、CEC、总磷、无机磷、有机磷、Fe/Al 磷和总氮显著正相关;对磷酸盐的最大吸附量与其CEC和无机磷、有机质和总磷呈显著负相关;而总最大吸附磷量与其有机质、CEC、总磷、无机磷、有机磷、Fe/Al 磷和总氮含量呈显著正相关;③就目前长江中下游浅水湖泊的水质而言,其沉积物存在解析;沉积物对磷酸盐的吸附 解吸平衡浓度与其有机质,CEC ,总氮,总磷以及各形态磷含量均有显著的正相关关系.本研究条件下,即使是污染较为严重的湖泊,其沉积物也具有向上覆水体释磷酸盐的趋势.     

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.     

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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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.     

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.     

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.     

Sorption of 1-naphthol by plant cuticular fractions

The contribution of aliphatic-rich plant biopolymer to sorption of hydrophobic organic compounds is significantly important because of their preservation and accumulation in the soil environment,but sorption mechanism is still not fully understood.In this study, sorption of 1-naphthol by plant cuticular fractions was examined to better understand the contributions of respective fraction.Toward this end,cuticular materials were isolated from the fruits of tomato by chemical method.The tomato cuticle sheet consisted of waxes (6.5 wt%),cuticular monomer (69.5 wt%),and polysaccharide (24.0 wt%).Isotherms of l-naphthol to the cuticular fractions were nonlinear (N value (0.82-0.90)) at the whole tested concentration ranges.The KodKow ratios for bulk cuticle (TC1),dewaxed cuticle (TC2),cutin (TC4),and desugared cuticle (TC5) were larger than unity,suggested that tomato bulk cuticle and cutin are much powerful solption medium.Sorption capability of cutin (TC4) was 2.4 times higher than the nonsaponifiable fraction (TC3).The 1-naphthol interactions with tomato cuticular materials were governed by both hydrophobic-type interactions and polar (H-bonding) interactions. Removal of the wax and polysaccharide materials from the bulk tomato cuticle caused a significant increase in the sorption ability of the cuticular material.There was a linear negative trend between K_(oc) values and the amount of polysaccharides or fraction's polarities ((N O)/C);while a linear positive relationship between K_(oc) values and the content of cutin monomer (linear R~2=0.993) was observed for present in the cuticular fractions.Predominant sorbent of the hydrophobic organic compounds (HOCs) in the plant cuticular fraction was the cutin monomer,contributing to 91.7% of the total sorption of tomato bulk cuticle.     

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.     

Seed selections for crystallization of calcium phosphate for phosphorus recovery

Seed induces and promotes the crystallization of calcium phosphate, and acts as carrier of the recovered phosphorus （P）. In order to select suitable seed for P recovery from wastewater, three seeds including Apatite （AP）, Juraperle （JP） and phosphate-modified Juraperle （M-JP） were tested and compared. Batch and fixed-bed column experiments of seeded crystallization of calcium phosphate were undertaken by using synthetic wastewater with 10 mg/L P phosphate. It shows that AP has bad enduring property in the crystallization process, while JP has better performance for multiple uses, and M-JP is a hopeful seed for P recovery by crystallization of calcium phosphate.