丛枝菌根在退化土壤恢复中的生态学作用

土壤退化 (包括土壤侵蚀、贫瘠化、盐碱化、沙化、酸化 )不仅为全球所关注 ,而且是关系到我国农业可持续发展的重大问题。全球 1.3× 10 8ｋｍ2 的总土地面积中 ,因人为原因引起的退化面积为 2 0×10 7ｋｍ2 ,这些退化土壤中 ,耕地近 5× 10 8ｈａ ,约占总耕地面积的 1/ 3。我国南方丘陵区土壤退化问题也突出 (水土流失面积 8 0× 10 7ｈａ ,养分贫瘠化 1 9×10 7ｈａ ,污染土壤 3 2× 10 6ｈａ ,酸化土壤 3 2×10 6ｈａ) ,因而探讨恢复和重建退化土壤的途径已成为该地区农业持续发展的重要内容[5] 。菌根 (ｍｙｃｏｒｒｈｉｚａ)是土…     

太行山猕猴的肥满度

太行山猕猴自然保护区位于河南省西北部 ,已于 1 998年升格为国家级自然保护区。地理坐标为北纬 3 4°5 4′～ 3 5°2 0′,东经 1 1 0°0 2′～ 1 1 4°1 0′。保护区内生活有国家二级保护动物太行山猕猴约 1 5 0 0余只 ,现已成为我国乃至世界野生猕猴分布的最北限[1 ] 。该种群属华北亚种 (Ｍａｃａｃａｍｕｌａｔｔａｔｃｈｅｌｉｅｎｓｉｓ) ,为我国特产动物 ,不仅在生理、生态、行为、形态等方面与南方种群有明显差异 ,且具有独特的、其它地区猕猴无法替代的遗传多样性[2 ] 。近年来 ,由于环境恶化及诸多人为因素的影响 ,致使该区域猕猴…     

部分人体生理数据

1　细胞　成年人 ,整个身体总细胞数约为 1.8× 10 7亿个 ;水分 ,占体重 60 %。2　皮肤　表面积 1.4～ 1.6m2 ,占体重 16% ;汗孔 2 0 0万个 ;每平方厘米有痛点 10 0～ 2 0 0个 ,触点 2 5个 ,冷点12～ 13个 ,热点 1～ 2个 ;p H=5 .5 ,能再生。3　毛发　成人头发 8万～ 10万根 ,每天脱落 30～ 12 0根 ,每天生长 0 .4 mm,寿命 2～ 4年 ,每天分泌皮脂 15～4 0 g;指甲每天生长 0 .1mm,3～ 5个月更换一次。4　牙齿　由牙冠、牙颈、牙根三部分组成 ;有切牙 (门牙 )、尖牙 (犬齿 )、磨牙 (臼齿 ) 3种类型 ;人一生长 2次牙 ,乳牙 2 0颗 ,恒牙 2 8～ …     

黄河上游玛曲县生态环境问题与综合治理对策

1　自然地理条件概况玛曲县位于甘肃省西南部 ,10 0°4 5′4 5″～ 10 2°2 9′0 0″Ｅ ,33°0 6′30″～ 34°30′15″Ｎ ,土地总面积 1 0 19× 10 4 ｋｍ2 ,是黄河上游以藏民族聚居为主的纯牧业县。阿尼玛卿山、西倾山两大山系主脉形成的西部高山区、中南部阿尼玛卿山东南端和西倾山前山地带丘陵区及黄河沿岸河流阶地构成地形地貌格局[12 ] ,大部分区域海拔 35 0 0～ 380 0ｍ。玛曲属高原大陆性气候 ,年平均气温 1.1℃～2 .7℃ ,年平均降水量 5 0 1.6～ 6 15 .5ｍｍ ,主要集中于 5～ 9月 ,年蒸发量 10 0 0～ 15 0 0ｍｍ[5] 。年平均风速 2…     

不同施肥条件下旱田养分淋溶规律实验研究

从当今世界范围看 ,每年转入陆地生态系统中的总Ｎ量约为 2× 10 8ｔ。其中来自工业肥料的Ｎ含量占 2 0 %。目前全世界的施肥量仍在增加 ,发展中国家的增加速率比发达国家高得多。目前 ,我国的大部分耕地都需要补充Ｎ素 ,一半以上的耕地需要补充磷肥 ,大约 1/3～ 1/4以上的耕地需要补充钾肥。然而 ,由于种种原因 ,我国农田土壤养分的利用率一直较低 ,损失率较大。旱地土壤Ｎ素 (尿素 )利用率仅为 2 0 %～ 4 0 %。Ｐ的利用率 15 %～ 30 %。这一方面提高了农产品的成本 ,另一方面 ,过多的使用肥料又造成了环境问题[1,2 ] 。其中 ,一部分养分沿…     

土壤因子对野生植物AM真菌的影响

1　引　　言关于生态因子对ＡＭ真菌发生和分布的影响 ,国内外均有报道[1,2 ,7] ,张美庆等[6] 比较系统地研究了我国东、南沿海七省ＡＭ真菌的生态分布 ;吴铁航[5] 报道了几种土壤因子对栽培作物根围内ＡＭ真菌分布的影响 .本文主要介绍土壤类型、质地、营养状况、ｐＨ等对野生植物根围ＡＭ真菌的侵染、孢子密度和种属分布的影响 .2　研究地区与研究方法2 1　研究地区概况山东省位于 33°2 5′～ 38°2 3′Ｎ ,114°36′～ 12 2°4 3′Ｅ之间 ,属暖温带大陆性季风气候 ,年平均气温 11～ 14℃ ,年平均降水量为 5 5 0～ 95 0ｍｍ .根据地貌不…     

HPLC法测定麻仁润肠丸大黄素、大黄酚的含量

采用KromacilC18(4 .6mm× 2 5 0mm ,5 μm)色谱柱 ,以甲醇 - 0 .1%磷酸溶液 (85∶15 )为流动相 ,流速为 1mL·min ,柱温为 30℃ ,检测波长为 2 5 4nm ,以外标法测定了麻仁润肠丸中大黄素、大黄酚的含量。大黄素在 8.992× 10 -3 ～ 116 .896× 10 -3 ,大黄酚在 2 1.376× 10 -3 ～ 2 77.85 8× 10 -3 范围内呈线性关系 ,其在制剂中的平均回收率 (n =6 )分别为 10 1.5 6 % (RSD =1.3% )、96 .78% (RSD =1.3% )。     

从社区林业的观点探讨西双版纳刀耕火种农业生态系统的演化

1　引　言西双版纳地处我国西南边陲 ,东、南、西三面分别与缅甸、老挝接壤。由于地处热带最北缘 ,是热带与亚热带的交汇地带 ,动植物资源非常丰富 ,一直被誉为“动植物王国的明珠”。近 2× 1 0 4 ｋｍ2(全国总面积的 0 .2 % )分布了我国 2 5%的植物。但是 ,由于几十年不合理的政策和技术指导 ,1 950～ 1 985年期间森林覆盖率从 63%降到 34% ,其中包括了大面积的人工林如橡胶林和其它热带经济林 ,即有林地面积为 6 67× 1 0 5ｈａ ,其中保护区2 0× 1 0 5ｈａ,约占 1 /3。其他国有林 (包括国营橡胶林 )占 1 /3多 ,集体林和自留山占 1 /3多…     

覆膜对春小麦农田微生物数量和土壤养分的影响

研究了黄绵土区不同覆膜时期对旱作麦田土壤微生物数量及其与土壤碳、氮、磷含量的关系。丰水的 1 999年 ,土壤微生物数量增长早 ,延续时间长 ,覆膜 60 d微生物数量最高 (3 3 .93 8× 1 0 6 /g dry soil) ,其次为全程覆膜 (3 2 .2 5 9× 1 0 6 ) ;干旱的 2 0 0 0年微生物平均数量只有 1 999年的 3 6.5 % ,在后期有一定降水后微生物数量才出现高峰 ,以全程覆膜数量最高(1 4.83 6× 1 0 6 ) ,覆膜 60 d次之 (1 1 .5 2 9× 1 0 6 )。 1 999年各类群微生物数量同土壤有机碳之间均呈显著或极显著负相关。2 0 0 0年相关系数几乎全面下降 ,氨化细菌、硝化细菌和反硝化细菌 ,甚至微生物总量同土壤有机碳之间都已不再显著相关。 1 999年土壤全氮同氨化细菌、硝化细菌、亚硝化细菌、解磷细菌及微生物总量均呈显著或极显著负相关 ,2 0 0 0年只与氨化细菌、亚硝化细菌、微生物总数显著负相关。土壤速效磷含量在 1 999年与解磷细菌显著负相关 ,而在 2 0 0 0年相关已不再显著。两年试验结束后 ,全程覆膜处理有机质下降 2 1 .2 % ,覆膜 60 d处理下降 1 7.2 % ,覆膜 3 0 d和不覆膜处理下降相对较小 (4 .3 %和 6.7% )。由于施用化肥 ,土壤全氮有明显升高。速效磷在 1 999生长季和随后的休闲期都有升高 ,在干旱的 2 0 0 0     

第11届国际生物奥林匹克竞赛(2000)理论试题B答案

(续 2 0 0 2年第 1期第 58页 )49.牵张感受器心动加速中枢心动抑制中枢血管舒缩中枢兴奋抑制兴奋抑制兴奋抑制兴奋抑制××××心输出量小动脉增加减少收缩扩张××5 0 .删除5 1. .(1)　 .(3)　 .(2 )　 .(13)　 .(11)　 .(1)　 .(8)5 2 .呼吸商较高呼吸商较低底物的无氧呼吸×底物不完全氧化×CO2 固定如 Ca CO3 ×碳水化合物转变成脂肪×5 3. 　　 　　 　　 　　 5 4 .动脉的化学感受器呼吸速率兴奋抑制增加减少××肾脏中 H+ 的排泄 血液 CO2 分压增加减少增加减少××5 5 .3　 3　 1,2 ,3,4　 1,2 ,3,4　 1,2 ,3,45 6 .(1…     

有机污染土壤中菌根的作用

近年来,土壤有机污染问题日益突出,传统的修复方法存在局限性。菌根是植物根系与菌根真菌形成的共生体,能增强植物的逆境抗胁迫能力,对于促进有机污染物的降解和转化具有积极的作用。本文主要阐述了石油、多环芳烃、多氯联苯、农药和酞酸酯等几类典型的有机污染土壤中外生菌根和丛枝菌根的作用;旨在说明利用菌根技术修复有机污染土壤是生物修复的一项重要工具,具有广阔的发展前景,为进一步研究菌根的作用以及更好地运用菌根技术奠定基础。     

Bioremediation techniques–classification based on site of application: principles,advantages, limitations and prospects

Environmental pollution has been on the rise in the past few decades owing to increased human activities on energy reservoirs, unsafe agricultural practices and rapid industrialization. Amongst the pollutants that are of environmental and public health concerns due to their toxicities are: heavy metals, nuclear wastes, pesticides, green house gases, and hydrocarbons. Remediation of polluted sites using microbial process (bioremediation) has proven effective and reliable due to its eco-friendly features. Bioremediation can either be carried out ex situ or in situ, depending on several factors, which include but not limited to cost, site characteristics, type and concentration of pollutants. Generally, ex situ techniques apparently are more expensive compared to in situ techniques as a result of additional cost attributable to excavation. However, cost of on-site installation of equipment, and inability to effectively visualize and control the subsurface of polluted sites are of major concerns when carrying out in situ bioremediation. Therefore, choosing appropriate bioremediation technique, which will effectively reduce pollutant concentrations to an innocuous state, is crucial for a successful bioremediation project. Furthermore, the two major approaches to enhance bioremediation are biostimulation and bioaugmentation provided that environmental factors, which determine the success of bioremediation, are maintained at optimal range. This review provides more insight into the two major bioremediation techniques, their principles, advantages, limitations and prospects.     

AM真菌对重金属污染土壤生物修复的应用与机理

土壤重金属污染威胁人类健康和整个生态系统,而高效、低耗、安全的生物修复技术显示出了极大的应用潜力,特别是利用植物-微生物共生体增强生物修复效应的应用.丛枝菌根(Arbuscular Mycorrhizae,AM)真菌是一类广泛分布于土壤生态系统中的有益微生物,能与90％以上的陆生高等植物形成共生体.研究发现,AM真菌能够增强宿主植物对土壤中重金属胁迫的耐受性.当前,利用AM真菌开展重金属污染土壤的生物修复已经引起环境学家和生态学家的广泛关注.基于此,围绕AM真菌在重金属污染土壤生物修复作用中的最新研究进展,从物理性防御体系的形成、对植物生理代谢的调控、生化拮抗物质的产生、基因表达的调控等角度探究AM真菌在重金属污染土壤生物修复中的作用机理,以期为利用AM真菌开展重金属污染的生物修复提供理论依据,并对本领域未来的发展和应用前景进行了展望.     

镍污染对土壤微生物的生态效应

镍是高等植物和某些微生物必需的微量营养元素之一,在它们的生命活动中起着重要作用;但浓度较高时,也是一种极毒元素。大量的研究表明,镍污染土壤中微生物的生长、代谢、群落结构和种群多样性会受到不同程度的影响;微生物在长期受重金属威迫的环境中形成其适应性。利用微生物形成的这种适应机制,采用微生物技术治理重金属污染的土壤是可能的。本文还对镍污染土壤的微生物评价指标体系、土壤环境容量、微生物技术开发和综合治理技术开发等的进一步研究作了展望。     

同源重组法构建多功能农药降解基因工程菌研究

构建遗传稳定的多功能农药降解基因工程菌可以为农药污染的生物修复提供良好的菌种资源,然而,构建遗传稳定且不带入外源抗性的基因工程菌是一个难点。通过以受体菌的16S rDNA为同源重组指导序列、sacB基因为双交换正筛选标记构建同源重组载体,二亲结合的方法将甲基对硫磷水解酶基因（mpd）整合到呋喃丹降解菌Sphingomonas sp.CDS1染色体的16S rDNA位点,分别成功构建了含1个和2个mpd基因插入到rDNA位点且不带入外源抗性的基因工程菌株CDSmpd和CDS-2mpd。同源重组单交换的效率为3.7×10^－7～6.8×10^－7。通过PCR和Southern杂交的方法验证了同源重组事件。基因工程菌遗传稳定,能同时降解甲基对硫磷和呋喃丹。甲基对硫磷水解酶（MPH）的比活在各生长时期均高于原始出发菌株,比活最高达6.22 mu/μg。     

Synergistic plant-microbes interactions in the rhizosphere: a potential headway for the remediation of hydrocarbon polluted soils

Soil pollution is an unavoidable evil; many crude-oil exploring communities have been identified to be the most ecologically impacted regions around the world due to hydrocarbon pollution and their concurrent health risks. Several clean-up technologies have been reported on the removal of hydrocarbons in polluted soils but most of them are either very expensive, require the integration of advanced mechanization and/or cannot be implemented in small scale. However, “Bioremediation” has been reported as an efficient, cost-effective and environment-friendly technology for clean-up of hydrocarbon”s contaminated soils. Here, we suggest the implementation of synergistic mechanism of bioremediation such as the use of rhizosphere mechanism which involves the actions of plant and microorganisms, which involves the exploitation of plant and microorganisms for effective and speedy remediation of hydrocarbon”s contaminated soils. In this mechanism, plant”s action is synergized with the soil microorganisms through the root rhizosphere to promote soil remediation. The microorganisms benefit from the root metabolites (exudates) and the plant in turn benefits from the microbial recycling/solubilizing of mineral nutrients. Harnessing the abilities of plants and microorganisms is a potential headway for cost-effective clean-up of hydrocarbon”s polluted sites; such technology could be very important in countries with great oil producing activities/records over many years but still developing.     

Fate of Pesticides in the Environment and its Bioremediation

The present paper is an overview of the presence and fate of pesticides as persistent organic pollutants in the environment as well as of the potential for their detoxification, also combined with chemical and physical treatment. It contains information gathered from a range of currently available sources. The fate of pesticides in the environment is analyzed considering the processes that determine their persistence and mobility, grouped into transport, transfer and transformation processes. Few pesticide characteristics such as persistence, mobility and biodegradability are emphasized. The fate of a pesticide and the potential for its persistence and mobility from the site of application are considered to be affected by the chemical and physical properties of the pesticide, site characteristics such as soil and groundwater individuality, climate and local weather conditions, biological population, and the handling practices of the pesticide user. Bioremediation, as one of the most environmentally‐sound and cost‐effective methods for the decontamination and detoxification of a pesticide‐contaminated environment is discussed especially considering the factors affecting the biodegradability of pesticides such as biological factors and the characteristics of the chemical compounds. In situ and ex situ bioremediation as possible types of bioremediation activities are weighted up. Also, the paper includes some considerations for developing strategies regarding the choice of bioremediation technology, as well as advantages and disadvantages of the bioremediation of environmental components polluted with pesticides.     

Comparison of efficiencies of oil-oxidizing Dietzia maris strain and stimulation of natural microbial communities in remediation of polluted soil

Two approaches to bioremediation of oil-polluted soils are compared: use of active degrader strain Dietzia maris AM3 and stimulation of natural microflora. Introduction of D. maris AM3 to soil freshly polluted with oil accelerated its remediation twofold within the first month in comparison with the stimulation. After three months, the purification degrees were approximately equal. By the end of bioremediation, the soil with the introduced strain had higher dehydrogenase and catalase activities. In soil with multiyear pollution, introduced strain D. maris AM3 did not affect the rate of oil product degradation, and no significant differences between the two bioremediation methods were detected in purification degree and biological activity of soil after three months.     

Time-series metagenomic analysis reveals robustness of soil microbiome against chemical disturbance

Soil microbial communities have great potential for bioremediation of recalcitrant aromatic compounds. However, it is unclear which taxa and genes in the communities, and how they contribute to the bioremediation in the polluted soils. To get clues about this fundamental question here, time-course (up to 24 weeks) metagenomic analysis of microbial community in a closed soil microcosm artificially polluted with four aromatic compounds, including phenanthrene, was conducted to investigate the changes in the community structures and gene pools. The pollution led to drastic changes in the community structures and the gene sets for pollutant degradation. Complete degradation of phenanthrene was strongly suggested to occur by the syntrophic metabolism by Mycobacterium and the most proliferating genus, Burkholderia. The community structure at Week 24 (∼12 weeks after disappearance of the pollutants) returned to the structure similar to that before pollution. Our time-course metagenomic analysis of phage genes strongly suggested the involvement of the ‘kill-the-winner’ phenomenon (i.e. phage predation of Burkholderia cells) for the returning of the microbial community structure. The pollution resulted in a decrease in taxonomic diversity and a drastic increase in diversity of gene pools in the communities, showing the functional redundancy and robustness of the communities against chemical disturbance.