苯噻草胺对土壤中过氧化氢酶活性及呼吸作用的影响

通过模拟实验研究了水稻除草剂苯噻胺对土壤中过氧化氢酶活性及对土壤呼唤作用强度的影响，并研究了其在不同条件下水解和光解的效果，结果表明，苯噻草胺的浓度对土壤中过氧化氢酶的活性有明显影响，浓度愈大，对土壤中过氧化氢酶活性的抑制愈大，苯噻草胺在实验条件下没有明显的水解和光解，苯噻草胺对土壤呼吸有明显的抑制作用，浓度愈高，土壤呼吸强度在初期抑制愈大，17d后各处理土样的呼吸强度基本恢复正常，试验结果还表明，苯噻草胺属于低毒或无明显实际危害的农药，对土壤微生物影响较小。     

除草剂苯噻草胺在土壤中的吸附

对除草剂苯噻草胺在6种不同土壤中的吸附行为进行了研究。结果表明,土壤对苯噻草胺有较强的吸附性。在试验浓度范围内,苯噻草胺的土壤吸附行为可用线性吸附模型表征。土壤有机质是影响苯噻草胺吸附行为的重要因素,其吸附系数有随土壤有机质含量增高而增大的趋势。通过在线性吸附系数（Kd)和土壤有机质含量（OM％）之间构建的回归方程：Kd=2.6120 OM% 1.0746,可以预测苯噻草胺的Kd值,其预测的可靠性通过蒙特卡洛模拟得以检验。     

水稻不同生育期土壤微生物区系对模拟Cr（Ⅵ）污水灌溉的响应

通过盆栽试验,分析模拟Cr(Ⅵ)污水灌溉对水稻不同生育时期土壤微生物区系特征的影响.结果表明:(1)土壤细菌数量在低浓度Cr(Ⅵ)(10 mg·L-1)灌溉条件下明显增加而在高浓度Cr(Ⅵ)(50 mg·L-1)灌溉条件下明显降低,土壤真菌、放线菌及钾细菌数量随着Cr(Ⅵ)灌溉浓度的增加而明显降低,而土壤磷细菌数量随着Cr(Ⅵ)灌溉浓度的增加而明显增加;(2)水稻不同生育时期土壤微生物对Cr(Ⅵ)处理的敏感性不同,土壤细菌敏感性生育前期高于生育后期,而土壤真菌及放线菌正好相反;(3)加Si处理对土壤细菌有明显的刺激作用,明显缓解高浓度Cr(Ⅵ)在水稻拔节期和抽穗期对土壤放线菌的抑制作用.与之相反,加Si处理使Cr(Ⅵ)对土壤无机磷细菌数量的刺激作用消失,甚至使抽穗期和成熟期无机磷细菌数量明显低于对照.     

吡嘧磺隆和苯噻酰草胺在水稻中的残留分析

本文建立了混合除草剂吡嘧磺隆和苯噻酰草胺在水稻上的残留分析方法,并研究了其在水稻中的消解动态和最终残留.样品经乙腈超声提取、二氯甲烷液-液分配和Pesticarb/NH2SPE净化后,通过HPLC-UVD检测.该方法对水稻植株、糙米、稻壳和土壤中的吡嘧磺隆最小检出量(LOD)为2.0×10-10g;田水中的吡嘧磺隆和苯噻酰草胺最小检出量(LOD)为1.0×10-10g.该方法对水稻植株、糙米、稻壳和土壤中的苯噻酰草胺最小检出量(LOD)为2.0×10-10g.试验结果显示,8%吡嘧·苯噻酰颗粒剂施药量分别为675 g(a.i.)·ha-1(其中吡嘧磺隆为42.2 g(a.i.)·ha-1)和1012.5 g(a.i.)·ha-1(其中吡嘧磺隆为63.3 g(a.i.)·ha-1),施药1次,2010年北京施药后120 d,安徽施药后92 d,湖南施药后70 d收获期糙米、植株、土壤和稻壳中吡嘧磺隆的残留量均低于0.01 mg·kg-1.     

苯噻菌酯在土壤中的降解、吸附和迁移特性

采用室内模拟试验方法,研究了苯噻菌酯在东北黑土、江西红壤和南京黄棕壤中的降解、吸附和迁移特性.结果表明,苯噻菌酯在3种不同土壤中的降解顺序为东北黑土南京黄棕壤江西红壤,半衰期分别为32.8、37.9、51.7 d,属于中等降解农药.随着土壤含水量(20%—80%)增加,苯噻菌酯的降解速率加快.苯噻菌酯在灭菌土壤中降解速率明显减慢,渍水条件下降解速率加快,说明土壤中微生物,特别是厌氧微生物是影响苯噻菌酯降解的重要因素.此外,土壤中有机质和氧化物能促进苯噻菌酯的降解.3种土壤对苯噻菌酯的吸附均较好地符合Freundich方程,吸附系数Kd值分别为171.33、102.41和135.89,属于较易吸附农药.苯噻菌酯在土壤中移动性较差,属于难淋溶农药.     

氟乐灵对土壤微生物和蚯蚓的影响

本文探讨了除草剂氟乐灵对土壤微生物的影响。结果表明:低浓度的氟乐灵对土壤细菌、放线菌和霉菌的生长有刺激作用,不仅数量增加,而且菌落明显增大,但对微生物种无明显选择性;氟乐灵能促进大豆根瘤菌和圆褐固氮菌的生长;在培养液中同时加入氟乐灵和圆褐固氮菌,可抑制固氮菌的乙炔还原活性;在生长良好的固氮菌培养液中,再加入氟乐灵,可明显刺激固氮菌的乙炔还原活性;土壤微生物可以氟乐灵为唯一碳源和氮源,加速氟乐灵降解;2.0ppm以上浓度的氟乐灵对蚯蚓有毒害作用。     

双氟磺草胺对麦田残留及土壤酶活性的影响

三唑并嘧啶磺酰胺类除草剂双氟磺草胺(Florasulam)主要用于冬小麦田防除杂草.为了解不同施用量的双氟磺草胺对麦田残留及其土壤酶活性的影响,设置5个不同施用量(对照CK和T1-T4分别为0、15、30、45、60 mL/667 m2)的双氟磺草胺处理,测定不同施用量的双氟磺草胺处理后的麦田残留及其土壤酶(过氧化氢酶、磷酸酶、脲酶、脱氢酶)活性.结果显示,不同施用量的双氟磺草胺在土壤中的残留量随着小麦生育期逐渐降低,但残留量微少,远远低于0.01 mg/kg.不同土层中的双氟磺草胺残留量随着土层厚度的增加而逐渐降低.不同施用量双氟磺草胺处理的土壤酶活性基本上表现为T3 T2 T1 CK T4,以T3为最高,T4会对土壤酶活性产生抑制作用.因此,在减少土壤污染和较低的双氟磺草胺残留的前提下,推荐双氟磺草胺的施用量为30-45 mL/667 m2,此结果可为双氟磺草胺的科学使用提供理论依据.     

除草剂苯噻草胺土壤滞留因子的蒙特卡洛模拟

采用简单随机抽样和拉丁超立方抽样两种不同方法对除草剂苯噻草胺的土壤滞留因子模型进行蒙特卡洛模拟。结果表明，不同的土壤条件下，苯噻草胺的滞留因子（R）的数值呈Beta分布，最大极值为176．5，最小极值为3．3，最可能的取值在20－30的范围内。结果还显示了采用拉丁超立方抽样方法能够显著降低抽样的不均匀性，进而能降低Beta分布拟合的不确定性。本文还通过色轴在4维图上形象地表征了R值的变化。     

中国新疆火焰山土壤环境及细菌群落结构北大核心CSCD

为评价火焰山地区土壤环境现状,并了解环境因子对土壤微生物数量和细菌群落结构的影响,测定了土壤理化性质和4种典型土壤酶活性,结合传统分离培养计数所得微生物数量进行主成分分析(Principal Component Analysis,PCA)和相关性研究,运用变性梯度凝胶电泳(Denaturing Gradient Gel Electrophoresis,DGGE)技术结合冗余分析(Redundance Analysis,RDA)解析影响细菌群落结构的关键因子.结果表明:(1)火焰山地区土壤肥力状况较差,主要特点为含水率低、养分贫瘠和盐碱化严重,其中盐分含量是限制土壤肥力水平的关键因素,脱氢酶活性可作为快速评价火焰山土壤肥力的重要指标,多酚氧化酶活性最能代表火焰山土壤系统内的肥力变异状况;(2)火焰山土壤微生物数量处于较低水平,细菌为绝对优势菌群(占98.13%),土壤水分是决定微生物数量的关键因子,但盐分含量与微生物数量的相关性不明显;(3)环境因子与土壤细菌群落多样性和结构分布的相关性密切,全氮含量和土壤水分是影响细菌群落多样性的关键因子,各环境因子对不同细菌群落的影响迥异,其共同作用决定了火焰山地区细菌群落结构分布.     

恩诺沙星对土壤细菌数量及微生物生物量碳的影响

为了评价兽药恩诺沙星(Enrofloxacin,ENR)对土壤微生物的影响,采用平板计数法和熏蒸浸提法研究了不同含量恩诺沙星(wENR)对土壤细菌数量和土壤微生物生物量碳(MBC)含量的影响.结果发现,添加药物组细菌数量和土壤微生物生物量碳含量均低于对照组,且药物含量越高,细菌数量和土壤微生物生物量碳含量越低;较低含量的恩诺沙星(wENR<0.1μg·g-1,细菌数量;wENR<1μg·g-1,MBC)对细菌数量和微生物生物量碳含量影响不显著(与对照组比较,p>0.05),而较高含量的恩诺沙星(wENR≥0.1μg·g-1,细菌数量;wENR≥1μg·g-1,MBC)则影响显著(与对照组比较,p<0.05).以上结果表明恩诺沙星残留可显著影响土壤细菌数量和微生物生物量碳含量,进而可能影响土壤特性和土壤的一些生态过程。     

丁草胺污染对高产水稻土微生物区系的影响

土壤微生物多样性是表征土壤质量最有潜力的指标,与农田生态系统的稳定性和生产力密切相关。云南永胜涛源乡是保持我国水稻小面积超高产纪录的特殊生态区,常年施用丁草胺作为选择性芽前除草剂,因此,了解丁草胺对其土壤微生物物种多样性的影响意义重大。采用平板菌落计数法,研究了模拟条件下不同丁草胺剂量（有效成分质量分数0.15、0.30和1.5 mg·kg^-1）对高产水稻土中好氧细菌（aerobic bacteria）、放线菌（actinobacteria）和真菌（fungi）,以及功能微生物自生固氮菌（nitrogen fixing bacteria）、磷酸盐溶解菌（phosphate solubilizing bacteria）和硅酸盐细菌（silicate dissolving bacteria）数量的影响。结果表明：施药7 d,中、高质量分数（0.30和1.50 mg·kg^-1）丁草胺处理好氧细菌数量比CK分别高出78.6%和153.8%,而后数量逐渐下降,表现出先刺激生长、后抑制活性的作用,低质量分数（0.15 mg·kg^-1）丁草胺对好氧细菌的生长和增殖影响不明显;施药7 d,高质量分数处理放线菌数量超过CK 75.1%,表现出明显的刺激作用;施药15 d,中等质量分数处理放线菌数量比 CK 高出125.0%,丁草胺浓度越高,刺激作用越迅速,低浓度丁草胺对放线菌则主要表现为抑制作用。低浓度丁草胺对真菌的生长和增殖基本没有影响,中等浓度有先抑制后刺激的作用,施药30 d后其真菌数量超过CK 56.9%,高浓度丁草胺则表现为抑制作用,施药7、30和45 d其真菌数量始终显著低于CK;不同浓度处理丁草胺均能刺激自生固氮菌的数量显著增加,施药7 d,低、中、高质量分数处理自生固氮菌数量分别高出CK 237.1%,179.9%和138.1%,刺激作用显著,但随培养时间延长,高浓度开始表现出抑制作用;不同浓度丁草胺均能抑制磷酸盐溶解菌的生长和增殖,低浓度处理抑制作用微弱,中、高浓度处     

Impact of anaerobically treated and untreated (raw) distillery effluent irrigation on soil microflora, growth, total chlorophyll and protein contents of Phaseolus aureus L

Impact of distillery effluent (untreated and treated) irrigation on soil microflora of the pots used for growing Phaseolus aureus L. was investigated. The growth of the P. aureus plants as affected by distillery effluent irrigation was also evaluated. The irrigation of the pots by 1-10% distillery effluent (anaerobically treated) stimulated the growth of the soil microflora (increased number of bacteria, fungi and actinomycetes) and P. aureus plants (increased shoot and root lengths, biomass, chlorophyll and protein contents). Further, 15-20% distillery effluent (anaerobically treated) had toxic effect on soil micro flora as indicated by reduced number of bacteria, fungi and actinomycetes. Reduction in shoot, root, lengths, biomass, chlorophyll, protein contents of P. aureus was also observed when irrigated by 15-20% treated distillery effluent. All the concentrations of raw distillery effluent reduced the bacterial population. However, the treated distillery effluent concentrations <10% had stimulatory effect on fungal and actinomycetes population. However, raw effluent concentrations >5% reduced the same. Raw distillery effluent was more toxic to P. aureus than treated distillery effluent as concentrations >5%, had reduced the growth (shoot, root length and biomass) of the test plant. Raw distillery effluent had adverse effect to total chlorophyll contents and all the test concentrations reduced the total chlorophyll level. However, untreated (raw) distillery effluent stimulated the protein content initially. It has been concluded from-present study that lower concentrations of the raw distillery effluent (1-5%) and treated distillery effluent (1-10%) had stimulated the growth of P. aureus and soil microflora except soil bacteria (inhibited by all the concentration of the raw effluent). However, higher concentrations (raw effluent: 10-20%; treated effluent 15-20%) had toxicity to test parameters.     

The influence of introducing soft-shelled turtle on soil nitrogen-fixing microorganisms in paddy field北大核心CSCD

Soil microorganisms are an important part of the soil ecosystem, but studies on the structure of the soil bacterial community, especially the related genes, is lacking. This study aimed to investigate the structure of soil microorganisms and the connection between the soil microorganisms and different farming systems. We used the Illumina Genome Analyzer IIx to compare root soil bacteria (nifH gene) diversity characteristics between the rice-turtle co-culture system (R-T) and rice monoculture system (R-M), aiming to reveal the structural characteristics of soil microorganisms, and the connection between the soil microorganisms and different farming systems. The results of High Throughput Sequencing of nitrogen-fixing bacteria showed that the main nitrogen-fixing bacteria were classified as Bradyrhizobium, Geobacter, Anaeromyxobacter, Desulfovibrio, Sideroxydans, Desulfuromonas, Halorhodospira, Azotobacter, Desulfobulbus, Methylomonas, Pseudacidovorax, and Azospirillum. The diversity index of nitrogen-fixing bacteria in the root soil of R-T was higher than that of R-M, which was 6.85-0.07. The difference of soil nitrogen-fixation bacteria in the root soil of rice paddy was 23.86% among the different farming systems, and the difference in the different rice growth period was 16.97%. In summary, the rice growth period and different farming systems both have an influence on the nitrogen-fixation bacteria in paddy soil; the influence of the growth period on the nitrogen-fixation bacteria in the paddy soil was greater. © 2018 Science Press. All rights reserved.     

污泥用作农肥处置及其环境影响

本文概述国内外污泥用作农肥处置的现状,全面分析了农田施用污泥产生的重金属积累,水处理凝聚剂及有害有机物的影响,过剩氮、磷的二次污染,恶臭及病原菌等问题,并提出相应的防治对策。加强管理,恰当处置,农田施用污泥是实现污泥资源化,解决污泥出路的好办法。     

不同栽培措施对水稻田甲烷释放、甲烷产生菌和甲烷氧化菌的影响

本文报导不同栽培措施下水稻田甲烷释放的特性和甲烷产生菌、甲烷氧化菌的数量、种类。结果表明,水稻田的甲烷释放,无论是早稻还是晚稻,成活期每天的释放量较少,随着生长逐渐增加,至分蘖期达到最高,随后又逐渐减少,长期淹水和施用高量氮肥或有机肥可以明显地增加水稻田的甲烷释放量。水稻田土壤中产甲烷细菌的数量湿灌溉少氮处理少于其他各处理,其他各处理间无明显差异。早稻生长前期较后期土壤中的产甲烷菌数量低2—3个数量,晚稻生长中期略高于生长前期和后期。甲烷氧化菌数量在早稻生长期间从10~3～10~4/g干土增加到生长后期的10~8/g干土。在晚稻生长期间维持在10~8/g干土。产甲烷细菌的种类主要为甲烷杆菌属(Methanobacterium)和甲烷八叠球菌属(Methanosarcina)的种。甲烷氧化菌主要为杆状,除甲烷外还能利用其他基质的兼性异养型甲基营养型细菌。     

水稻土中半胱氨酸分解产生含硫气体的研究

在室内培养条件下,测定了水稻土中含硫气体的释放．结果表明,该土壤中有硫化氢(Ｈ２Ｓ),羰基硫(ＣＯＳ),二甲基硫(ＤＭＳ)三种气体释放．当土壤中加入半胱氨酸后,ＣＯＳ和Ｈ２Ｓ气体的浓度有了明显增加,并有ＣＳ２和ＣＨ３ＳＨ测出,而ＤＭＳ的浓度变化不大．这些结果表明半胱氨酸的分解可能是 ＣＯＳ,Ｈ２Ｓ,ＣＳ２和 ＣＨ３ＳＨ的产生源之一．在好氧(正常大气)条件下,Ｈ２Ｓ,ＣＯＳ,ＣＳ２和ＣＨ３ＳＨ的释放量低于厌氧(氮气氛围)条件下的释放量,ＤＭＳ则高于厌氧条件下．这表明水稻土中半胱氨酸分解产生 Ｈ２Ｓ,ＣＯＳ,ＣＳ２和 ＣＨ３ＳＨ需较强的还原条件,产生这四种气体的微生物需要严格的厌氧条件．产生ＤＭＳ的微生物则比前者需要高一些的含氧量．在光照条件下,各含硫气体的释放量普遍高于无光照条件下的释放量．释放含硫气体的大多数微生物适宜的含水率为５０%且对土壤的ｐＨ值有一定要求．     

禾草灵对水稻生长和典型土壤酶活性的影响

禾草灵是一种广泛使用的除草剂,在土壤中大量残留,对非靶标生物产生危害。为探究除草剂对环境生物的毒性作用,本研究模拟水稻自然生长的环境,评估禾草灵对水稻及土壤微生物的影响。研究结果表明,低浓度禾草灵(200μg·L-1)处理4d对土壤微生物量没有显著影响(P0.05);8 d时,水稻生长没有明显变化,但土壤微生物量较对照组显著升高(P0.05)。高浓度禾草灵(1 000μg·L-1)处理4 d后,土壤脲酶、酸性磷酸酶和过氧化氢酶的活性显著下降(P0.05),下降幅度分别为8.9%,16.6%和10.2%;处理8 d后,水稻幼苗鲜重显著降低(P0.05),叶绿素a和叶绿素b含量分别下降了13.5%和13.3%。本研究证实高浓度的禾草灵残留会对植物和土壤微生物产生不良的影响。     

转基因毛白杨外源基因转移的环境风险分析

以8年生转Bt基因败育毛白杨雄株为实验材料,分离其体内、体外、根际土壤、蛀干桑天牛(Apripona germari Hope)排泄物中可培养的细菌和真菌,利用特异引物对获得的微生物进行转Bt基因败育毛白杨雄株外源基因PCR检测.实验发现,381株次细菌中有6株PCR检测阳性;307株次真菌中有4株PCR检测阳性.     

Carbon sequestration and soil microbes in purple paddy soil as affected by long-term fertilization

Soil organic carbon (SOC) sequestration impacts on food security and climate change and may be affected by soil microbes in fertilized croplands. A 12-year field experiment under the rice–wheat system was used to evaluate the effect of the long-term fertilization on the SOC accumulation, culturable soil microbes, and their interaction in purple paddy soil. Results showed that varied fertilizations resulted in a significant increase of the SOC content and stock in the plow layer, as well as rise in populations of major soil microbes, including bacteria, actinomycetes, and fungi compared with no fertilization. Soil with combined application of chemical NPK fertilizer and organic amendment (pig manure or rice straw return) on average had the highest organic carbon content and stock, amounts of bacteria, actinomycetes, and fungi, which were 7.8%, 5.8%, 75.8%, 130.5%, and 16.2% higher than the NPK fertilization alone. Fertilization differentially altered populations of the functional anaerobic bacteria in paddy soil. With the combined application of chemical NPK fertilizer and organic amendment, soil displayed higher amounts of anaerobic cellulolytic bacteria, anaerobic fermentative bacteria, hydrogen-producing acetogen, methanogenic bacteria, denitrifying bacteria, and sulphate-reducing bacteria than that with the NPK fertilization alone or no fertilization. Populations of all three major soil microbes showed significantly positive correlations with the SOC content, indicating their interaction was of mutual promotion. Data suggest that the combined application of the NPK fertilizer with organic amendment especially by the rice straw return is recommended to sustain the soil biological fertility and mitigate the emission of the greenhouse gas by the SOC sequestration in purple paddy soil.