模拟酸雨对福州平原稻田土壤细菌丰度及多样性的影响

为了探讨酸雨对稻田土壤细菌的影响,以福州平原某稻田为研究对象,测定和分析模拟不同酸度酸雨处理下早、晚稻土壤细菌群落组成及其丰度.结果表明：模拟酸雨处理提高了早稻土壤细菌的多样性,但却降低了晚稻土壤细菌的多样性;酸雨改变了稻田土壤细菌的丰度及群落结构,经模拟不同酸度的酸雨处理,稻田土壤细菌的优势菌属及其丰度并不一致;早稻pH3.5处理组与早稻对照组之间的物种多样性及群落结构差异最大,晚稻pH2.5处理组与晚稻对照组之间的物种多样性及群落结构差异最大;在酸雨作用下,溶杆菌属（Lysobacter）和产黄杆菌属（Rhodanobacter）的丰度明显升高,而马赛菌属（Massilia）的丰度则显著降低,说明溶杆菌属（Lysobacter）和产黄杆菌属（Rhodanobacter）为耐受酸雨的主要菌属,马赛菌属（Massilia）则为受酸雨影响最大的菌属;细菌属H16的相对丰度与土壤电导率（EC）呈极显著负相关（P<0.01）,Lysobacter的相对丰度与土壤pH值呈极显著负相关（P<0.01）,Arenimonas的相对丰度与土壤总有机碳（SOC）呈极显著正相关（P<0.01）.     

模拟酸雨对毛竹阔叶林过渡带土壤真菌结构及其多样性的影响

为探究酸雨对毛竹扩张形成的竹阔混交林土壤真菌群落的影响程度,于2017～2018年在浙江省杭州临安天目山国家级自然保护区开展酸雨模拟实验,选取T1(pH=4.0)和T2(pH=2.5)两个模拟酸雨梯度,并以CK(pH=5.5)对照,利用Illumina MiSeq高通量测序技术,分析不同强度酸雨胁迫下,土壤真菌群落多样性变化及影响因素.结果表明与对照相比,T1处理显著提高了真菌群落的OTU数量、Chao1指数和Ace指数(P0.05).竹阔混交林土壤主要由13个门类群的菌群组成,优势菌群包括子囊菌门(Ascomycota)、担子菌门(Basidiomycota)、被孢霉门(Mortierellomycota)和毛霉门(Mucoromycota).主坐标(PCoA)分析和相似性检验结果表明模拟酸雨改变了土壤真菌结构.Bifiguratu属、Geminibasidium属、Purpureocillium属和Oidiodendron属相对丰度变化显著,可作为酸雨胁迫下土壤真菌群落结构变化的指示种.冗余分析(RDA)和相关性分析表明,土壤pH和全氮对土壤真菌群落结构影响显著(P0.05).综上所述,酸雨提高了真菌群落多样性指数,改变土壤真菌群落结构.该研究结果有助于了解森林生态系统中的真菌群落,以及土壤真菌作为影响因子在预测环境变异中的作用.     

棉秆炭调控对碱性镉污染水稻根际土壤真菌群落结构和功能的影响

为研究棉秆炭对碱性镉污染水稻根际土壤真菌多样性、结构及功能的影响,采用室外水稻盆栽试验,在土壤中添加了0、 1和8 mg·kg~(-1)的镉和炭土质量比分别为0%、 1%和5%的棉花秸秆生物质炭,以水稻成熟期根际土壤为研究对象,借助Illumina HiSeq高通量测序手段分析棉秆炭与镉污染条件对碱性水稻根际土壤真菌群落多样性、结构及潜在功能的影响,探寻不同土壤环境因子与真菌群落结构间的关联性.结果表明:①施用棉秆炭显著提高了土壤pH、速效养分和有机质等指标,并降低土壤中可还原态镉的含量(P0.05).②水稻根际土壤真菌菌门分布主要为子囊菌门、Aphelidiomycota门和壶菌门,占所有菌门的57%.菌属分布主要为被孢霉属、链格孢属和镰刀菌属.各处理间真菌群落α-多样性差异显著(P0.05).未添加棉秆炭处理下(C0),镉浓度的增加降低了土壤中壶菌门、被孢霉属和链格孢属的相对丰度和真菌多样性指数(Shannon指数).在不同浓度镉处理下(Cd0、 Cd1和Cd8),增加棉秆炭会降低真菌群落丰富度指数(Chao1指数)和Shannon指数.镉污染导致土壤中壶菌门相对丰度增多,却使子囊菌门丰度下降,施用棉秆炭可显著提升壶菌门的相对丰度(P0.05).镉污染使被孢霉属和链格孢属丰度下降,但是施用棉秆炭可使链格孢属相对丰度增多.增加棉杆炭施用量,土壤中会存在更多的内生菌、植物病原体和腐生菌;而镉污染程度增加会减少土壤中内生菌、植物病原体和腐生菌.③影响真菌群落多样性及结构的主要环境因子有土壤速效钾、有机质和pH.水稻土壤镉含量中占比最大的可还原态镉与轮形动物门、Aphelidiomycota门和子囊菌门呈显著正相关(P0.05),但与其它菌门呈负相关(P0.05).研究结果说明棉秆炭在碱性镉污染土壤微生态调控方面具有一定的作用.     

典型稻田土壤真菌群落结构及多样性对比

为了解中国主要稻作区内不同母质发育的稻田土壤真菌群落结构和多样性差异,本研究选取由砖红壤、红壤、盐碱土、黑土和紫色土发育而来的5种中国典型稻田土壤为研究对象,利用高通量测序技术对土壤真菌群落组成及多样性进行对比分析.结果表明：5种典型稻田土壤的含水量、pH值、盐度及容重差异显著（P<0.05）;从Chao1指数来看,稻田土壤真菌群落丰度红壤型 > 黑土型 > 砖红壤型 > 紫色土型 > 盐碱土型.从ACE指数来看,群落丰度黑土型 > 红壤型 > 砖红壤型 > 紫色土型 > 盐碱土型.Shannon指数和Simpson指数均表现为群落多样性黑土型 > 紫色土型 > 红壤型 > 砖红壤型 > 盐碱土型;5种典型稻田土壤真菌门水平相对丰度最高的均是子囊菌门（Ascomycota）;砖红壤型和红壤型稻田土壤的优势真菌属为翅孢壳属（Emericellopsis）,紫色土型稻田土壤的优势真菌属为翅孢壳属、枝鼻菌属（Cladorrhinum）和柄孢壳属（Zopfiella）,黑土型稻田土壤的优势真菌属为翅孢壳属和明梭孢属（Monographella）,盐碱土型稻田土壤的优势真菌属为瓶头霉属（Phialocephala）;石黄衣属（Xanthoria）、Cyberlindnera、青霉菌属（Penicillium）和Westerdykella的相对丰度与土壤pH值呈显著负相关（P<0.05）,Ceroophora的相对丰度与土壤含水量呈极显著负相关（P<0.01）;帚枝霉属（Sarocladium）的相对丰度与可溶性有机碳呈极显著正相关（P<0.01）.以上研究表明,稻田真菌的群落结构和多样性受稻田开垦前土壤类型的影响,真菌物种丰度和优势菌种类型对土壤理化性质变化的响应较为敏感.     

模拟酸雨对毛竹入侵阔叶林缓冲区土壤细菌群落多样性的影响

为了分析酸雨对毛竹入侵阔叶林缓冲区土壤细菌群落多样性的影响,以浙江省天目山国家级自然保护区毛竹扩张形成的竹阔混交林为研究对象,选取T₁（pH=4.0）、T₂（pH=2.5）两个模拟酸雨梯度,并以pH=5.5为对照（CK）,应用Illumina MiSeq高通量测试技术分析不同强度酸雨胁迫下土壤细菌群落组成和多样性变化及其关键影响因素.结果表明:①随着酸雨强度增加,竹阔混交林土壤w（TN）（TN为总氮）、w（OC）（OC为有机碳）、C/N和w（AN）（AN为碱解氮）显著升高,而pH、w（DOC）（DOC为可溶性有机碳）、w（MBC）（MBC微生物量碳）和w（MBN）（MBN为微生物量氮）显著下降（P < 0.05）.②与CK相比,模拟酸雨处理（T₁、T₂）显著降低了细菌群落的OTUs数量、Chao1指数和Ace指数（P < 0.05）.③竹阔混交林土壤细菌包括34门96纲247目401科698属,其中变形菌门、酸杆菌门、绿弯菌门、放线菌门为3种处理下共有的优势菌门（相对丰度>1%）.变形菌门和放线菌门相对丰度在CK处理下最高,酸杆菌门和绿弯菌门相对丰度在T₂处理下最高.与CK相比,Arthrobacter属和Elsterales属相对丰度变化显著,可作为酸雨胁迫下土壤细菌群落结构变化的指示种.主坐标（PCoA）分析和相似性检验结果显示,模拟酸雨改变了土壤细菌群落结构.④冗余分析（RDA）和相关性分析表明,不同酸雨处理的竹阔混交林土壤细菌多样性与土壤pH、w（TN）密切相关（P < 0.05）.研究显示,不同模拟酸雨处理下土壤细菌群落结构和多样性有明显差异,主要可能受到土壤pH、w（TN）的影响.      

富炭硅肥对水稻土铁还原菌群落特征的影响

为了探究富炭硅肥施加处理对稻田土壤铁还原菌相对丰度、多样性及群落结构的影响,以福州平原稻田为研究对象,分别设置对照组及3种不同剂量（300,600和900kg/hm²）富炭硅肥施加处理组.研究结果表明：施加富炭硅肥有助于土壤铁还原菌的生长和繁殖,其中600kg/hm²施加处理对铁还原菌的生长影响最为显著（P<0.05）.由Shannon指数可知,3种施加处理均使晚稻拔节期土壤铁还原菌多样性有所下降,以300kg/hm²施加处理组多样性指数降低最为明显,较对照组降低了29.4%.在早、晚稻拔节期土壤中共鉴定出5个菌门,其中变形菌门（Proteobacteria）、拟杆菌门（Bacteroidetes）和厚壁菌门（Firmicutes）的占比之和平均高达95%以上,是稻田土壤中的优势菌门.施加富炭硅肥后,早稻拔节期土壤中拟杆菌属（Bacteroides）的相对丰度显著提高（P<0.05）,而厌氧粘细菌属（Anaeromyxobacter）的相对丰度则有所降低.此外,环境因子与稻田土壤铁还原菌的相对丰度具有相关性,Desulfovibrio的相对丰度与土壤pH值呈显著正相关（P<0.05）,Anaeromyxobacter的相对丰度与土壤温度（ST）呈显著正相关（P<0.05）.     

粪肥和有机肥施用对稻田土壤微生物群落多样性影响

为探究典型粪肥施用对稻田土壤微生物的影响,开展崇明岛稻田粪肥施用现场实验.采用高通量测序技术分析对照组(CK)和鸡粪(CM)、猪粪(PM)和有机肥(OF)施用稻田土壤微生物群落组成及多样性.结果表明,与CK相比,施用有机肥可提高土壤有机质(SOM),施用鸡粪可显著提高土壤氨氮(NH~+_4-N)和总氮(TN)含量(P0.05).PM组土壤微生物多样性显著高于CK组(P0.05),OF组土壤微生物群落丰富度显著高于CM组(P0.05).pH值、总磷(TP)、总氮和Pb是影响稻田土壤微生物群落组成的重要因素,CM组微生物群落结构与其他3组差异较大.与CK相比,OF组增加了硝化螺菌属(Nitrospira)的相对丰度,CM组显著降低了反硝化细菌Ignavibacteriae的相对丰度(P0.01),达40.56%,但显著增加了硝化细菌陶厄氏菌属(Thauera)的相对丰度(P0.05),达203.00%; PM组显著增加了氨化细菌Armatimonadetes的相对丰度(P0.05),达57.51%,还增加了厌氧绳菌属(Anaerolinea)的相对丰度,达102.00%.施用鸡粪和猪粪分别显著增加致病菌假单胞菌属(Pseudomonas)和黄杆菌属(Flavisolibacter)的相对丰度(P0.05),而有机肥施用则降低了黄杆菌属的相对丰度.粪肥的施用增加了参与稻田土壤氮循环过程细菌的丰度,对调节稻田土壤氮平衡起着正向作用,然而鸡粪和猪粪的直接施用会导致病原菌增多,对稻田土壤健康有一定的胁迫.     

炉渣与生物炭施加对稻田土壤细菌多样性及群落组成的影响

以福州平原稻田为试验基地,通过设置对照组、炉渣施加组、生物炭施加组、炉渣与生物炭混施组,探究它们对稻田土壤细菌相对丰度、多样性、群落组成的影响.结果发现,在晚稻生长期,废弃物施加处理条件下细菌群落多样性有所提高,与对照相比,生物炭、炉渣处理组细菌多样性指数分别提高了2.55%、3.21%.早稻混施组与早稻对照组之间的群落结构差异最大,晚稻生物炭施加组与晚稻对照组之间的差异最大.废弃物施加处理均提高了早稻芽孢杆菌属（Bacillus）相对丰度,降低了晚稻芽孢杆菌属（Bacillus）相对丰度,但晚稻中Bacillus占比始终高于早稻.环境因子对稻田土壤细菌相对丰度有显著影响,其中,芽孢杆菌属（Bacillus）相对丰度与稻田土壤pH值呈极显著正相关（P<0.01）.建议在晚稻生长期可进行表层废弃物单独施加管理,以通过微生物多样性的增加,改良土壤、提高土壤肥力并达到增产的效果,而对于早稻未来可尝试废弃物深施方式,并探讨其生态影响.     

生物炭对褐土理化特性及真菌群落结构的影响

为了探讨生物炭施用对土壤理化及生物学特性的影响,在田间条件下研究了不同用量(0、10、20、40 t·hm~(-2))生物炭施用3a后植烟褐土真菌的群落结构特征,并分析了其与土壤环境因子的关系.结果表明,土壤添加生物炭3 a后显著提高了土壤pH、含水率、总有机碳(TOC)和总氮(TN)含量,而降低了土壤容重和溶解性有机碳(DOC)含量.Illumina Mi Seq测序结果表明,生物炭的添加对土壤真菌α多样性影响不大,但能显著改变真菌群落结构.物种注释结果表明,所有样本中真菌优势菌群均为子囊菌门(Ascomycota)、接合菌门(Zygomycota)和担子菌门(Basidiomycota),其相对丰度之和占所有可注释真菌丰度的90%以上.生物炭提高了子囊菌门和担子菌门的相对丰度,降低了接合菌门的相对丰度.在属水平上,生物炭增加了链格孢属(Alternaria)、锥盖伞属(Conocybe)和曲霉属(Aspergillus)真菌的相对丰度,降低了放射毛霉(Actinomucor)和赤霉菌(Gibberella)的相对丰度.冗余分析(RDA)及Mantel检验结果说明,土壤DOC、pH和含水率是影响褐土真菌群落结构的主要环境因子.综上,生物炭施用3 a后对土壤理化特性有显著的影响,这些环境因子的改变驱动了土壤真菌群落的生态演替.     

模拟酸雨对福州平原水稻田土壤化学结合态有机碳含量的影响

为阐明酸雨对水稻田土壤化学结合态有机碳含量的影响,以福州平原水稻田为研究对象,在早稻和晚稻生长期中,设置对照(CK)、模拟pH=2.5、pH=3.5、pH=4.5酸雨处理,对酸雨影响下福州平原水稻田土壤化学结合态有机碳含量进行了测定与分析.结果表明,酸雨作用下早、晚稻土壤有机碳(SOC)含量介于13.40～20.17 g·kg~(-1),与土壤全氮(TN)含量显著正相关(p0.01);各处理下早稻田SOC含量均低于晚稻田,且早稻田土壤各处理间SOC含量差异不显著(p0.05),其中,晚稻CK、pH=2.5和pH=3.5处理的SOC含量与早稻差异显著(p0.05),酸雨处理均高于CK(p0.05).早、晚稻土壤Ca-SOC含量介于0.31～0.42 g·kg~(-1),早稻期间pH=2.5处理中Ca-SOC含量与其他处理差异明显(p0.05).早、晚稻土壤Fe(Al)-SOC含量介于2.90～4.64 g·kg~(-1),早稻各处理间差异不显著(p0.05),而晚稻各处理间差异显著(p0.05).相比之下,晚稻残渣态-SOC含量显著高于早稻(p0.05),酸雨处理显著高于CK(p0.05),且pH=2.5处理含量最高,均值为(15.21±0.37) g·kg~(-1),而早稻各处理残渣态-SOC含量差异不显著(p0.05).此外,早、晚稻SOC与Fe(Al)-SOC、残渣态-SOC之间均具有显著正相关关系(p0.01),早稻残渣态-SOC、晚稻Fe(Al)-SOC与土壤TN显著正相关(p0.01).综上所述,酸雨通过提高晚稻SOC和Fe(Al)-SOC含量,进而增强土壤碳库稳定性,促进有机碳的积累.     

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.     

Distribution and ecological effect of mercury in Laogang landfill, Shanghai, China

Laogang landfill near Shanghai is the largest landfill in China, and receives about 10000 t of daily garbage per day, Samples of topsoil and plants were analyzed to evaluate mercury pollution from the landfill. For topsoil samples, there were significant correlations among total mercury （HgT）, combinative mercury （Hgc） and gaseous mercury （HgG）, and content of total organic carbon （TOC）, but, no significantly relationship was found between Hg content and filling time. Hg content changes in vertical profiles with time showed that the average Hgv of profiles 1992, 1996, and 2000 was similar, but their average HgG was quite different. HgT was significantly correlated with Hgc in profile 1992 and 2000, and Hgv was significantly correlated with Hg6 in profile 1996. HgG/Hgv ratio in profile samples decreased in the order of （HgG,/HgT）1992〉（HgG/HgT）1996〉〉（HgG/HgT）2000. A simple outline of Hg release in landfill could be drawn： with increasing of filling time, degradation undergoes different biodegradation, accordingly, gaseous mercury goes through small, more, and small proportion to total mercury. Distribution of Hg in plants was inhomogeneous, following the order of leaf〉root〉stem. The highest value of leaf may be associated with higher atmospheric Hg from landfill. Ligneous plants （e.g. Phyllostachys glanca, Prunus salicina and Ligustrum lucidum） are capable of enriching more Hg than herbaceous plants.     

EDTA-enhanced phytoremediation of lead contaminated soil by Bidens maximowicziana

Phytoremediation is a potential cleanup technology for the removal of heavy metals from contaminated soils.Bidens maximowicziana is a new Pb hyperaccumulator,which not only has remarkable tolerance to Pb but also extraordinary accumulation capacity for Pb.The maximum Pb concentration was 1509.3 mg/kg in roots and 2164.7 mg/kg in overground tissues.The Pb distribution order in the B. maximowicziana was:leaf>stem>root.The effect of amendments on phytoremediation was also studied.The mobility of soil Pb and the Pb concentrations in plants were both increased by EDTA application.Compared with CK(control check),EDTA application promoted translocation of Pb to overground parts of the plant.The Pb concentrations in overground parts of plants was increased from 24.23-680.56 mg/kg to 29.07-1905.57 mg/kg.This research demonstrated that B.maximowicziana appeared to be suitable for phytoremediation of Pb contaminated soil,especially,combination with EDTA.     

Decomposition of alachlor by ozonation and its mechanism

Decomposition and corresponding mechanism of alachlor, an endocrine disruptor in water by ozonation were investigated. Results showed that alachlor could not be completely mineralized by ozone alone. Many intermediates and final products were formed during the process, including aromatic compounds, aliphatic carboxylic acids, and inorganic ions. In evoluting these products, some of them with weak polarity were qualitatively identified by GC-MS. The information of inorganic ions suggested that the dechlorination was the first and the fastest step in the ozonation of alachlor.     

Enzymatic oxidation of aqueous pentachlorophenol

The influence of the nonionic surfactant Tween 80 on pentachlorophenol （PCP） oxidation catalyzed by horseradish peroxidase was studied. The surfactant was tested at concentrations below and above its critical micelle concentration （CMC）. Enhancement of PCP removal was observed at sub-CMCs. The presence of Tween 80 in the reaction mixture reduced enzyme inactivation which occurred through a combination of free radical attack and sorption by precipitated products. A simple first-order model was able to simulate time profiles for enzyme inactivation in the presence or absence of Tween 80. At supra-CMCs, the surfactant caused noticeable reductions in PCP removal, presumably through micelle partitioning of PCP which precluded the hydrophobic PCP molecule from interacting with the enzyme.     

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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