鄱阳湖典型湿地土壤微生物活性对季节性水位变化的响应

为探究湿地土壤微生物对季节性水位变化的响应关系,以鄱阳湖湿地土壤为研究对象,在2014年3、6、10及2015年1月4个季节采集了3个不同高程样带的土壤样品,对土壤微生物基础呼吸、生物量及胞外酶等活性进行了测定。研究结果表明:(1)季节性水位变化不仅显著改变了土壤有机碳、溶解性有机碳、有效磷等含量,也使得微生物量碳和4种水解酶β-葡萄糖苷酶、β-木糖苷酶、N-乙酰氨基葡萄糖苷酶、磷酸酶活性表现出夏冬季较高、秋季最低的动态变化,而2种氧化酶酚氧化酶和过氧化氢酶的表现正好相反。(2)水位高程和地上植被类型同样对土壤微生物产生了显著影响,表现为南荻样带有较高营养元素含量和微生物活性。(3)一些土壤理化指标(含水量、铵态氮、有机碳、有效磷等)与微生物活性(微生物量、基础呼吸、酶活)显著相关;季节水位变化对微生物活性的影响大于高程差异。研究结果表明水位波动对湿地土壤微生物活性产生了重要影响,鄱阳湖水文节律的改变将影响到湿地土壤的正常生态功能。     

典型矿冶区周边土壤微生物功能特征及影响因素

土壤微生物对重金属污染胁迫敏感,但在实际野外环境中,土壤微生物群落生态效应通常是污染胁迫和环境因素综合作用的结果。为探究重金属污染土壤中微生物群落生态效应发生变化的主控因素,本研究以湖南省某典型矿冶区周边不同土地利用类型土壤为研究对象,以土壤碳氮循环过程主要的微生物功能指标土壤微生物生物量碳(MBC)、基础呼吸(BR)、诱导呼吸(SIR)和硝化潜势(PNR)为生态效应终点,进行采样调查分析。结果表明: 土地利用类型对MBC、BR和SIR影响均不显著;研究区土壤微生物功能的主要影响因子包括CaCl₂提取态Pb(CaCl₂-Pb)含量与土壤有机质(SOM)含量。多元回归分析结果表明,在CaCl₂-Pb含量为0.004～13.14 mg·kg^-1及SOM含量为0.24%～4.34%的条件下,土壤CaCl₂-Pb和SOM含量可以共同解释土壤中BR、SIR和PNR总变异的39.8%～58.3%;中等含量下(SOM在1.70%～2.36%,CaCl₂-Pb在0.004～12.98 mg·kg^-1),土壤CaCl₂-Pb和SOM含量与BR、SIR和PNR的变化能够建立显著的暴露-效应关系,可以作为测定终点定量评价重金属污染对微生物群落功能的生态效应。     

兰州市空气微生物群落的碳代谢特征及功能多样性研究

应用Biolog ECO技术和RDA分析研究了兰州市不同功能区,即风景区(Scenic Area,SA)、交通干线(Main Traffic Line,MTL)、公共服务区(Public Service Area,PSA)、文教区(Culture and Education Area,CEA)空气微生物群落代谢功能多样性及其与环境因子的相关性。结果表明,不同功能区的AWCD值在培养192 h后进入稳定期,对碳源总体利用能力呈现显著的区域性差异,SAPSACEA≈MTL。受环境因素影响,Mc Intosh指数差异明显,SA和PSA物种均一度较高。兰州市空气微生物相对利用率较高的碳源类型是酯类、氨基酸类及醇类,与主成分1显著相关的碳源有10种,其中氨基酸类是导致兰州市空气微生物群落代谢功能区域性差异的主要分异类型。环境因子与空气微生物群落代谢功能密切相关,温度、风速是不同功能区存在差异的主导因子。     

湖滨带典型植物不同器官营养盐分配及生态效应

以太湖胥口湾湖滨带芦苇、香蒲和菖蒲等典型挺水植物为研究对象,通过分析这3种挺水植物不同生长阶段器官中营养元素含量,结合其单位面积生物量以及分布面积,估算水生植物收割的氮(TN)、磷(TP)去除效应。结果表明:湖滨湿地沉积物中TN含量在生长期和衰老期分别为1373.0～2919.8和2240.6～3923.4 mg·kg^-1,TP含量分别为437.1～687.3和556.0～790.7 mg·kg^-1;3种植物在生长期和衰老期不同器官的TN、TP含量差异显著(P<0.05),且均表现为叶>根>茎;由生长期到衰老期,3种挺水植物叶和茎中TN和TP含量下降,而根部则增加;3种挺水植物器官中总碳含量表现为根≈茎>叶,且受植物生长期影响较小;在3种挺水植物中,芦苇叶中TN含量最高,香蒲茎中TN含量最高,三者根中TN含量相当;香蒲叶、茎、根中TP含量最高,而芦苇叶、茎、根中总碳含量最高;衰老期间,收割3种优势挺水植物可有效去除TN 21.8 t(18.47 g·m^-2)、TP 1.6 t(1.36 g·m     

西太湖河网区恢复与退化河岸带湿地生态及水环境功能比较

对西太湖平原河网区严重退化的河岸带湿地进行恢复的基础上,开展了恢复后湿地和退化湿地内植物群落物种多样性,生物量,植物干物质体内氮、磷含量,湿地水体中悬浮物含量、氮、磷营养物质浓度以及恢复后湿地内反硝化作用等湿地生态和水环境功能方面的比较研究。结果表明:(1)已恢复湿地群落结构趋于完整,物种多样性指数值较高,一般在1.7～3之间,均匀度在0.5～0.9之间波动。退化湿地物种丰富度低,多样性指数值较低,分别在0.3～1.5(H′),0.15～0.65(J)之间波动。在水花生(Alternanthera philoxeroides)入侵的群落内,种类稀少,且分布极不均匀,仅在0.3～1(H′)和0.1～0.3(J)之间波动,群落结构严重退化。(2)在植物生长旺盛期,1m2湿地内的芦苇(Phragmites communis)、香蒲(Typha orientalis)及茭草(Zizania latifolia)分别为42,18株和17株。其在湿地内的生物量分别为:4692,5142kg和2182kg;(3)上述物种单位干物质中的氮、磷平均含量分别达到2.88mg/g和2.09mg/g;沉水植物作为滨岸带湿地群落结构的重要组成部分,不仅具有高的生物量,而且吸收氮磷能力强,单位干物质氮、磷含量分别达到7.27mg/g和4.14mg/g;(4)植物对水体及沉积物中可溶性氮、磷的有效吸收以及颗粒态磷的自然沉降作用,使得上游来水中的总氮浓度流经湿地时,降至0.15～0.89mg/L之间,平均下降了85%;总磷浓度则由进水时的0.248～0.598mg/L,降至出水时的0.002～0.083mg/L;(5)滨岸带湿地对河水中悬浮物的有效拦截、滞留和吸附作用,使得入湖河水中的悬浮物含量降低了90%以上;(6)在高温缺氧的环境中,滨岸带湿地表现出较强的反硝化作用,且由河心向河岸逐渐增强的趋势。近河心处测定的N2O通量为0.034～0.068之间,到河岸处升至0.046～0.089。反硝化作用是削减水体中氮负荷的有效途径。     

狗娃花叶片生态化学计量特征及功能性状对坡向的响应

坡向对植物叶片生态化学计量特征及功能性状有显著影响。研究不同坡向上植物叶片生态化学计量特征与功能性状有助于了解植物对环境变化的响应及适应。以兰州地区狗娃花叶片为研究对象,分析其生态化学计量及功能性状随坡向的变化特征。结果显示:阳坡叶片C含量(408.12 g·kg^-1)、C∶P(348.61)与N∶P(29.71)均显著高于阴坡(其值分别为400.75 g·kg^-1、196.69和16.60),N含量(34.81 g·kg^-1)和C∶N(11.72)与阴坡无显著差异(其值分别为34.07 g·kg^-1和12.24),而P含量(1.67 g·kg^-1)显著小于阴坡(2.56 g·kg^-1);阳坡比叶面积及叶片含水量(10.55 cm2·g^-1、59.06%)与阴坡(9.70 cm2·g^-1、60.65%)无显著差异,叶干物质含量(0.14 g·g^-1)和叶面积(0.31 cm2)均显著低于阴坡...     

小麦阿拉伯木聚糖的益生功能及对肠道微生态的调节

病原体的耐药性日渐增大,替代抗生素的益生元成为近年来研究的热点问题。小麦阿拉伯木聚糖（AX）及水解产物阿拉伯低聚木糖（AXOS）作为一种新型益生元,对人和动物肠道益生菌有特异性增殖效果。此外,与菊粉等益生元相比,降解后的小麦AX显著提高小鼠结肠和盲肠短链脂肪酸的含量及其抗肿瘤免疫活性。最新研究表明,添加GH11木聚糖酶（50mg EP/kg）能够溶解和降解麦麸AX,并产生可通过盲肠微生物群发酵的低平均聚合度（avDP值为4~8）的AXOS,丁酸水平增加2mmol（P<0.05）,产丁酸的细菌属柔嫩梭菌和肠单胞球菌显著增加,而拟杆菌的水平显著降低,导致微生物群移位并对体外跨上皮耐药性有益。本文主要介绍近年来关于小麦AX、AXOS益生功能及对肠道微生态的研究,为小麦产品及饲粮的有效利用与开发提供科学依据。     

博斯腾湖湖滨带水盐梯度下植物功能性状及生态化学计量特征分析

湖滨湿地植物叶片功能性状和叶片生态化学计量特征的分析对掌握植物的生长速率及植物对土壤养分的吸收和利用效率具有重要意义。为探讨不同水盐环境对植物功能性状及其生态化学计量特征的影响, 该研究以博斯腾湖西岸湖滨带湿地为研究区, 以该地区优势植物及土壤环境因子为研究对象, 阐明该地区植物适应环境的策略。设置18个样地进行植物多样性的调查, 共调查到植物24种, 其中灌木8种, 草本16种。采用冗余分析法对植物叶片功能性状与土壤环境因子间的关系进行分析, 通过分析植物功能性状在不同水盐环境下的变化特征及其对植物功能性状的影响, 发现: 随着水盐含量的增加, 不同植物叶片功能性状变化较大, 其中叶绿素含量(SPAD)、叶片厚度(LT)和比叶面积(SLA)在低水低盐环境下最大; 叶片含水量(LWC)、叶干物质含量(LDMC)和叶干质量(LDM)在中水中盐、高水高盐环境下较大; 植物叶片碳(C)、氮(N)、磷(P)含量及其化学计量比变化较大, C:N范围为9.35-26.51, C:P的范围为50.13-228.95, N:P的范围为2.31-11.99, 其中C:P的变化范围最大; 叶片C含量与LT、LDMC、LDM均显著正相关, 叶片N含量与SPAD、LT显著正相关, 叶片P含量与LWC显著正相关, C:N、C:P均与LDMC显著正相关, 而N:P与叶片功能性状指标均不相关, SLA与叶片生态化学计量特征均不相关; 对环境因子与优势植物叶片功能性状的相关性分析发现, 影响种间植物功能性状的环境因子不同且各有差异。     

塔里木柯坪地层区中-上奥陶统萨尔干组碳酸盐岩微相和古地理

塔里木板块西北柯坪地层区中-上奥陶统萨尔干组的分布和相变受控于当时西浅东深的海底深度差异。萨尔干组的厚度10米左右,为富含有机物的黑色页岩并夹少量灰岩薄层或透镜体。位于研究区西南的伽师西克尔剖面缺失大部分奥陶纪地层,上奥陶统铁热克阿瓦提组碎屑岩不整合于下-中奥陶统鹰山组灰岩之上,中-晚奥陶世的大部分时段属于暴露海面的剥蚀区;北部乌什的亚科瑞克剖面无萨尔干组岩性单元,为红色居多且粒度偏粗的碎屑岩夹白云岩薄层,属于近岸带碎屑岩为主的沉积区。西克尔向东北延伸150km至柯坪羊吉坎亦无萨尔干组,与萨尔干组同期沉积的地层在此表现为大湾沟组上部浅海灰岩的相变,且与上奥陶统桑比阶坎岭组偏深水相的红色薄层含泥瘤状灰岩之间呈整合接触;由西向东出露于柯坪苏巴什沟、柯坪大湾沟、阿克苏四石厂3个剖面的萨尔干组黑色泥页岩指示典型的滞流盆地相,而夹含于萨尔干组下部和上部的薄层灰岩之微相特征差异甚为显著,表现为该组下部可见数层密集砂屑颗粒形成泥粒状灰岩或颗粒灰岩,可解释为西部相邻的浅海碳酸盐岩台地区灰岩经重力流搬运后的再沉积;而该组上部含生屑泥状灰岩则属滞流盆地相区类似于黑色页岩环境的正常沉积。从羊吉坎灰岩台地到苏巴什沟滞流盆地相之间距离仅20余千米,坡度偏大是导致重力流形成的主要原因。     

Source reduction of the landfill leachate strength in a functional layer embedded landfill (FLEL)

In order to reduce the leachate strength from landfill at source, a novel landfill, functional layer embedded landfill, was developed through the introduction of the functional layers, and a comparative study was conducted between the functional layer embedded landfill (FLEL, R1) and the conventional landfill (CL, R2). It was found that the pollutant in leachate effluent from R1 was 20-50%, 14-43% and 33-75% of that from R2, in terms of COD, TN and NH₃-N. The cumulative movement of waste settlement was about 16.4 and 13.1 cm in R1 and R2 under the test period of 1 years, resulting in 13.7% and 10.9% of the original landfill height. Therefore, FLEL could save the land area and the cost of the leachate treatment process due to the reduction of leachate strength, and more waste could be disposed in landfill through the acceleration of the MSW degradation process, comparing to the CL.     

Transformation of carbon tetrachloride in an anaerobic packed-bed reactor without addition of another electron donor

Carbon tetrachloride (52 M) was biodegraded for more than 72% in an anaerobic packed-bed reactor without addition of an external electron donor. The chloride mass balance demonstrated that all carbon tetrachloride transformed was completely dechlorinated. Chloroform and dichloromethane were sometimes also found as transformation products, but neither accumulated to significant levels in comparison to the amount of carbon tetrachloride transformed. Transformation of carbon tetrachloride in the absence of an added electron donor suggests that carbon tetrachloride itself is the source of energy for the biological reaction observed, and possibly the source of carbon for cell growth. No such mechanism is yet known. The pathway of carbon tetrachloride transformation is not clear; it may be dehalogenated by hydrolytic reduction to carbon monoxide or formic acid which are electron demanding transformations. Carbon monoxide or formic acid may be further utilized and serve as electron donor. Complete dechlorination of carbon tetrachloride according to this pathway is independent of a second electron donor or electron acceptor, as with a fermentation process. Vancomycin, an inhibitor of gram positive eubacteria, severely inhibited carbon tetrachloride transformation in batch incubations with an enrichment culture from the reactor, indicating that gram positive eubacteria were involved in carbon tetrachloride transformation. Batch experiments with bromoethanesulfonic acid, used to inhibit methanogens, and molybdate, an inhibitor of sulfate reduction in sulfate reducing bacteria, demonstrated that neither methanogens nor sulfate reducers were involved in the complete dechlorination of carbon tetrachloride.     

Lipid peroxidation and covalent binding in the early functional impairment of liver Golgi apparatus by carbon tetrachloride

The onset of the lipoprotein secretory block provoked by CCl4 in the whole animal was monitored after purification of liver Golgi membranes. Both lipid transit through the apparatus and hexosylation of the lipoprotein are markedly inhibited 5-15 min after poisoning. Pre-treating the animal with alpha-tocopherol, shown to prevent lipid peroxidation without modifying the covalent binding due to CCl4 metabolites, affords little protection against lipid accumulation in the Golgi, but total preservation of galactosyl transferase activity. While haloalkylation therefore appears to be the major mechanism of damage in the early phases of CCl4-induced derangement of lipid secretion, lipid peroxidation is probably more involved later; this is indicated by the marked, though never complete, protection against fatty liver afforded at 24 h after CCl4 poisoning by supplementation of the membrane with alpha-tocopherol.     

In vivo and in vitro evidence concerning the role of lipid peroxidation in the mechanism of hepatocyte death due to carbon tetrachloride

Isolated rat hepatocytes exposed to CCl₄ showed a stimulated formation of malonaldehyde after only 30–60 min incubation. Conversely, the onset of hepatocyte death was a relatively late event, being significant only after 2–3 h of treatment. A cause–effect relationship between the two phenomena has been demonstrated by using hepatocytes isolated from rats pretreated with alpha-tocopherol. Comparable results were obtained in vivo where supplementation with alpha-tocopherol 15 h before CCl₄ dosing induced a partial or complete protection against the drug's necrogenic effect, depending on the concentration of the haloalkane used. Moreover, the vitamin supplementation prevented the CCl₄-induced increase of liver total calcium content, probably by blocking alterations in the liver cell plasma membranes due to lipid peroxidation.     

基于土地利用/覆被变化的荒漠绿洲碳储量动态评估

以典型的荒漠绿洲区为研究对象,基于不同时期土地利用/覆被类型图,运用Bookkeeping模型,结合土壤、植被碳密度基础资料及调查数据,评估了近30年临泽绿洲土地利用/覆被变化特征及其对碳储量的影响。结果表明:(1)临泽荒漠绿洲区的土地利用/覆被变化特征主要表现为:居民及建设用地、耕地、林地呈增加趋势,增幅分别为90.2%、75%、46.5%;盐碱地、水体、沙地、荒漠草地则呈减少趋势,减幅分别为73.9%、67.8%、46.2%、5.5%。(2) 30 a耕地面积增加了269.38 km~2,其中耕地开垦面积为372.57 km~2,开垦主要来源于盐碱地、荒漠草地和沙地,分别占耕地开垦面积的24.7%、24.4%和21.05%。耕地转变为其他土地覆被类型的面积为103.19 km~2,转变后的主要去向分别是居民及建设用地、盐碱地和荒漠草地,分别占耕地转变为其他土地覆被类型面积的32.78%、17.8%和15.37%。(3)土地利用/覆被变化导致总碳储量增加5.89×10~5t,其中土壤碳储量增加量为4.02×10~5t,植被碳储量增加量为1.86×10~5t;耕地变化使碳储量增加4.91×10~5t,其中使碳储量增加的转变分别是荒漠草地-耕地、沙地-耕地、盐碱地-耕地、耕地-林地,相反的转变则使碳储量减少。总体来看,临泽荒漠绿洲土地利用/覆被面积和结构均发生了变化,耕地开垦为最主要的土地利用/覆被变化,土地利用/覆被变化导致碳储量总体呈增加趋势,耕地变化是影响碳储量变化的主要因素。     

甲烷及三氯乙烯驯化对垃圾填埋场覆盖土细菌群落结构的影响

对典型垃圾填埋覆盖土进行CH₄原位富集和三氯乙烯(TCE)驯化,研究了其生物氧化能力和微生物群落结构变化.覆盖土CH₄氧化速率为0.20～0.87 μmol·g^-1 soil·h^-1,TCE降解速率为0.009～0.013 mg·L^-1·h^-1,其中山东垃圾填埋场覆盖土土样甲烷氧化活性高于广东、上海和重庆地区土样.通过Illumina MiSeq测序技术分析了α多样性和驯化前后微生物菌群结构变化规律.结果表明: 在所有被注释的操作分类单元聚类结果中,细菌OTUs分配为39个门,85个纲,562个属,富集驯化后变形杆菌门、拟杆菌门、绿弯菌门和酸杆菌门仍为各土样的优势菌群,所占比例之和高于77.4%;γ-变形杆菌纲、β--变形杆菌纲、α-变形杆菌纲、放线菌纲和酸杆菌纲所占比例之和高于26.5%.嗜甲基菌属、厌氧绳菌属、节杆菌属和假单胞菌属经TCE驯化后,其相对丰度呈增加趋势.表明在覆盖土氯代烃生物降解过程中,除了被广泛认可的甲烷氧化菌异养共代谢机制以外,还存在非甲烷共代谢机制和氯代烃自养降解机制.     

Powdered activated carbon added biological treatment of pre-treated landfill leachate in a fed-batch reactor

Biological treatment of landfill leachate usually results in low treatment efficiencies because of high chemical oxygen demand (COD), high ammonium-N content and also presence of toxic compounds such as heavy metals. A landfill leachate with high COD content was pre-treated by coagulation-flocculation followed by air stripping of ammonia at pH = 12. Pre-treated leachate was biologically treated in an aeration tank operated in fed-batch mode with and without addition of powdered activated carbon (PAC). PAC at 2 g l^–1 improved COD and ammonium-N removals resulting in nearly 86% COD and 26% NH₄-N removal.     

新疆地震断裂带次生植物根际土壤微生物碳源利用

利用BIOLOG技术研究了新疆富蕴地震断裂带6种次生植物对根际土壤微生物碳源利用的影响.结果表明:多数植物根际土壤养分显著高于对照.6种根际土壤的平均颜色变化率差异显著,且均高于对照.次生植物不影响根际土壤微生物碳源利用的丰富度,但改变了其优势度和均匀度.不同处理根际土壤微生物碳源利用存在差异,主要体现在对糖类、氨基酸类、羧酸类的利用上.断裂带上次生植物的出现使土壤微生物利用碳源的类型由酚类向糖类、羧酸类转变.土壤速效钾含量与土壤微生物对聚合物(r=-0.84)、胺类(r=-0.83)的利用呈负相关.新疆地震断裂带的次生植物能显著增强土壤微生物的碳源利用能力,改变碳源利用类型.密刺蔷薇和蓍在提高土壤微生物碳源利用能力和改善土壤养分方面效果最佳.     

Protective effects of ascorbic acid on hepatotoxicity and oxidative stress caused by carbon tetrachloride in the liver of Wistar rats

This study was planned to investigate the protective effect of l (+)‐ascorbic acid (Vit C) on CCl₄‐induced hepatotoxicity and oxidative stress in the liver of Wistar rats (Rattus Norvegicus, strain Wistar). Twenty‐four adult male Wistar rats were fed with standard rat chow diet for 10 days and randomly were divided into four groups of six each as follows: (1) control, (2) CCl₄, (3) “CCl₄ + Vit C”, (4) Vit C groups. CCl₄ was applied to rats belonging to CCl₄ and “CCl₄ + Vit C” groups subcutaneously at 1 mg kg^?1 dose CCl₄ for 3 days. Vit C applied to “CCl₄ + Vit C” and “Vit C” group rats intraperitoneally at 300 mg kg^?1 dose for 3 days. All rats were sacrificed and livers were quickly removed on the fourth day of the experiment. MDA, total glutathione (T.GSH) levels and superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH‐PX) activities were measured in the liver of all groups of rats and also serum alanine amino transferase (ALT) and aspartate amino transferase (AST) activities were detected to determine liver functions in all groups of rats. Histopathological changes were evaluated by light and transmission electron microscopes. In “CCl₄ + Vit C” group, MDA level was significantly decreased (p < 0.05) and SOD, CAT, GSH‐PX activities were significantly increased (p < 0.005, 0.01, 0.05) respectively, T.GSH level was significantly increased (p < 0.005) and serum ALT and AST activities were significantly decreased (p < 0.01, 0.05), respectively, when compared with CCl₄ group. These results show that Vit C has a highly protective effect on hepatotoxicity and oxidative stress caused by CCl₄. Copyright © 2009 John Wiley & Sons, Ltd.