电子受体及中间产物对厌氧氨氧化的影响

研究了厌氧氨氧化混合培养物对不同基质(硝酸盐、亚硝酸盐)的转化特性，确定了氨和硝酸盐、亚硝酸盐转化比例(物质的量)分别为1.085、0.897．亚硝酸盐转化成硝酸盐的比率为14.97％．在培养液中加入厌氧氨氧化的中间产物羟胺可以加速反应的进行．图3表2参9     

高氨氮废水处理系统中功能微生物的检测

利用16S rDNA分子检测技术对高氨氮废水处理系统中的氨氧化细菌、亚硝酸盐氧化细菌等难分离培养微生物进行了分析检测.从实验室处理高氨氮废水的生物流化床硝化系统生物膜中提取细菌总DNA,以其为模板,利用氨氧化细菌(AOB)和亚硝酸盐氧化细菌(NOB)的16S rDNA特异性引物进行多聚酶链式反应(PCR)扩增,获得AOB和NOB的特异片段.将特异片段与pGEM-T载体连接并转化到E.coli DH5α中获得重组子,对阳性重组子进行酶切分型,AOB可分为8种不同类型.选取AOB的8种类型代表以及随即选取8个NOB克隆进行测序.经GenBank搜索以及同源性分析,发现所获得的8个AOB类型来自不同的菌株,处理系统中以Nitrosomonas sp.和Nitrosococcus sp.为氨氧化细菌的优势菌属;8株NOB重组子中有7株来自不同的菌株,系统中Nitrobacter sp.和Afipia sp.为亚硝酸盐氧化细菌的优势菌属.图6表1参14     

土壤氨氧化细菌对大气CO2浓度增高的响应

摘要：利用FACE(free．aircarbondioxideenrichment，开放式空气CO2浓度增高)试验平台，研究大气CO2浓度增高对土壤氨氧化细菌的数量、优势菌群及其硝化活性的影响。结果表明，大气CO2浓度增高时，土壤氨氧化细菌的数量在常氮水平上趋于而在高氮水平上与对照没有差异。大气CO2浓度增高对土壤氨氧化细菌的优势菌群也产生明显影响。CO2浓度增高条件下，亚硝化球菌(Nitrosococcus sp.)和亚硝化弧菌(Nitrosovibrio sp．)是优势菌属；而在对照条件下，亚硝化单胞菌(Nitrosomonas sp．)和亚硝化球菌(Nitrosococcus sp．)是优势菌属。另外，CO2浓度增高条件下优势菌株的硝化活性也有不同程度的减弱。     

两株嗜热异养氨氧化细菌的鉴定及其氨氧化特性

为寻找适用于堆肥的嗜热异养氨氧化细菌,采用稀释涂布平板法和格里斯试剂显色法筛选嗜热异养氨氧化细菌,利用含NH4+培养基研究其最佳生长温度、pH条件以及其氨氧化特点和NO2-、NO3-的生成速率,并通过16S rDNA测序及Blast比对确定其种属.结果显示,从大理洱源热泉中分离了两株嗜热异养氨氧化细菌菌株NC8和NJ26;这两株菌的最适生长温度为55℃,最适生长pH为8.0;在最适生长条件下,NC8和NJ26菌株对NH4+的最大单位体积减少率分别为1 033.3mg/L和1 183.67 mg/L;对NO2-和NO3-最大单位体积产生率分别为23.79 mg/L、272.30 mg/L和33.81 mg/L、366.70 mg/L;种属鉴定表明,NC8和NJ26分别为Bacillus属的不同种.本研究表明,NC8和NJ26为异养型氨氧化细菌,能将NH4+氧化成NO2-和NO3-,以NO3-为主要积累产物,因此有望应用于堆肥过程中以减少氨气排放,同时提高堆肥中氮素的含量.     

影响厌氧氨氧化与甲烷化反硝化耦合的因素

氨氮、氮氧化物对产甲烷菌有一定的抑制作用,但可以通过驯化去除毒性.亚硝酸盐在厌氧氨氧化菌作用下与氨发生厌氧氨氧化反应.虽然厌氧氨氧化菌是自养菌,但具有异养代谢能力,并且NO2可提高厌氧氨氧化菌的活性.因此,通过特殊的反应器技术,将厌氧氨氧化菌与甲烷菌、反硝化菌复合在一个有利的微生态环境中,充分发挥它们之间的协同耦合作用,把有机物转化为清洁能源又同时脱氮,是极有前景的废水厌氧(缺氧)处理研究新方向.表1参31     

常温SBR厌氧-好氧反应器的短程硝化

短程硝化-反硝化是污水节能脱氮新技术之一,其关键在于实现短程硝化,而水温是控制短程硝化的主要因素。在生活污水氨氮浓度小于100mg/L的水质条件下,采用SBR厌氧-好氧反应器进行了常温短程硝化试验研究。研究结果表明,水温14．5℃～16．5℃的条件下,在好氧段可以实现短程硝化,亚硝化率达到了94．9%。亚硝化的程度还与曝气时间的长短有关,曝气时间短时,可以将氨氧化控制在亚硝化阶段,积累大量的亚硝酸盐,但是氨转化率比较低;曝气时间延长,氨氮去除率增加,同时部分亚硝酸氮会被进一步氧化成硝酸氮。该研究结果打破了只有在中高温条件下才能实现短程硝化的普遍看法,从而为在常温下实现短程硝化提供了新的依据。     

高温自养硝化反硝化工艺研究

利用筛选的耐高温亚硝化单胞菌结合适量的市政污水厂活性污泥,通过逐步提高温度进行曝气、驯化、挂膜,获得能够在38～47℃条件具有高氨氧化活性的硝化生物膜,在进水氨浓度120～180mg/L,氨氧化率达到90%～99.9%;将该生物膜回复常温硝化,显示其氨氧化活性较差,氨氧化率仅35%～70%.对其氨氧化产物分析发现,低于43℃时被氧化的氨氮为117～143mg/L,亚硝酸盐和硝酸盐积累较高,总浓度在115～135mg/L;但随着温度升高至44～45℃,亚硝酸盐积累显著下降到5.6～27.9mg/L,NO3--N低于2mg/L;至47℃稳定运行期间,NO2--N维持在10mg/L以下,NO3--N在2mg/L以下.对反应器中消耗的碱度的分析表明,当温度从43℃逐渐升高时,碱度消耗明显下降,由7.16～9.14mg(CaCO3)/mg(NH4+-N)降至4.08～5.19mg(CaCO3)/mg(NH4+-N).结合大量的NH4+-N被氧化且氨氧化产物中又只有少量的NO2--N和NO3--N,以及碱度消耗明显下降的特征,推测在高温条件下发生了自养硝化反硝化脱氮现象.     

近地层臭氧浓度升高对稻田土壤氨氧化与反硝化细菌活性的影响

利用中国唯一的稻麦轮作臭氧FACE（free-air O3 concentration enrichment,开放式空气臭氧浓度增高）试验平台,研究近地层臭氧浓度升高对稻田不同生育时期植株氮吸收量、土壤氮含量与脲酶活性、土壤氨氧化细菌与反硝化细菌数量以及成熟期土壤硝化与反硝化作用强度的影响。结果发现,臭氧浓度升高条件下,单株水稻（Oryza sativaL.）的氮吸收量趋于升高,土壤全氮含量趋于下降、脲酶活性趋于增强,在成熟期土壤全氮与对照相比平均下降9%,土壤脲酶活性与对照相比平均升高13%。在水稻整个生长季节,土壤氨氧化细菌和反硝化细菌的数量均呈现出先增多后减少的趋势,且均在开花期达到峰值,但臭氧熏蒸土壤与对照相比趋于升高;在水稻成熟期,土壤中单个氨氧化细菌和反硝化细菌的活性均趋于下降,土壤硝化强度和反硝化强度与对照相比也平均下降17%和24%。结果表明,近地层臭氧浓度升高条件下,稻田土壤氮素转化因为水稻氮素吸收增强而加快,土壤氨氧化细菌和反硝化细菌的数量均趋于增多,但它们的生理代谢活性均趋于下降。     

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。     

废水生物脱氮中N2O和NOx的产生和作用

废水生物脱氮中N2O和NOx来源于硝化、反硝化、厌氧氨氧化和化学反硝化等过程．电子受体和供体浓度、pH、缓冲剂类型、有机负荷、微生物种类及其相互作用等都会影响这些气态中间产物的产生．NO2能够氧化氨和强化好氧和厌氧氨氧化，NO能够阻止C2H2对好氧氨氧化活性的抑制，两者对好氧氨氧化活性的恢复至关重要．所有这些表明，废水生物脱氮的气态中问产物N2O和NOx在氮的生物转化中具有重要的正面作用，甚至必不可少．基于NO2曝气技术和Brocadia anammoxidans与Nitrosomonas协同作用的废水生物脱氮新技术开发是今后一段时间的重要研究方向．图4参35     

Rapid,recurring, structured survey versus bioblitz for generating biodiversity data and analysis with a multispecies abundance model

A bioblitz inexpensively and quickly generates biodiversity data, but bioblitzes are often conducted with haphazard, unreplicated sampling. Results tend to be taxonomically, geographically, or temporally biased, lack metadata, and consist of lists of observed taxa that do not enable further analyses or correction for imperfect detection. A rapid, recurring, structured survey (RRSS) uses a structured sampling design and temporal and spatial replication to survey randomly selected sites on a conservation property. We participated in a loosely structured bioblitz and a subsequent RRSS at Big Canoe Creek Nature Preserve in Springville (St. Clair County), Alabama (USA) to compare observed richness derived from the 2 survey approaches. The RRSS data structure enabled us to fit models that accounted for imperfect detection to estimate abundances, occupancy probabilities, and habitat associations. The loosely structured bioblitz data could not be used in such models. We present a new integrated multispecies abundance model that we applied to avian RRSS data. Our model extension enables estimation for the community, employs data augmentation to estimate the number of undetected species, and incorporates covariates. The RRSS generated a more comprehensive and less biased list of observed taxonomic richness than the loosely structured bioblitz (e.g., 73 vs. 45 bird species and 104 vs. 63 insect families from the RRSS vs. loosely structured bioblitz, respectively). Models fit to the RRSS data identified seasonal patterns in avian community composition and allowed for estimation of habitat–occupancy relationships for insect taxa. The RRSS protocol has potential for broad transferability as a standardized, quick, and inexpensive way to inventory biodiversity and estimate ecological parameters while providing an outreach opportunity.     

Compliance with and ecosystem function of biodiversity offsets in North American and European freshwaters

Land-use change via human development is a major driver of biodiversity loss. To reduce these impacts, billions of dollars are spent on biodiversity offsets. However, studies evaluating offset project effectiveness that examine components such as the overall compliance and function of projects remain rare. We reviewed 577 offsetting projects in freshwater ecosystems that included the metrics project size, type of aquatic system (e.g., wetland and creek), offsetting measure (e.g., enhancement, restoration, and creation), and an assessment of the projects’ compliance and functional success. Project information was obtained from scientific and government databases and gray literature. Despite considerable investment in offsetting projects, crucial problems persisted. Although compliance and function were related to each other, a high level of compliance did not guarantee a high degree of function. However, large projects relative to area had better function than small projects. Function improved when projects targeted productivity or specific ecosystem features and when multiple complementary management targets were in place. Restorative measures were more likely to achieve targets than creating entirely new ecosystems. Altogether the relationships we found highlight specific ecological processes that may help improve offsetting outcomes.     

A palaeo-hydrogeological model for arsenic contamination in southern and south-east Asia

An argument is presented in which areas of natural arsenic contamination of modern groundwaters throughout Asia have a common origin. Arsenic originally accumulated in oceanic ferro-manganoan sediments of the eastern Palaeo-Tethys. This was further concentrated through oceanic crustal extinction in what later became the south-east Chinese accreted mineralised terrain. Proto-Himalayan uplift of this area created the palaeo-drainage systems of the Ganges – Brahmaputra, Irrawaddy, Mekong, and Red Rivers, with consequent headwater erosion of arsenic-rich sediments. Their downstream deposition as immature and easily redistributed Neogene sandstones, silts, and iron-rich clays has created secondary and tertiary reservoirs of adsorbed and authigenic arsenic, from which the current arsenic-rich groundwaters have evolved. Considering river basins within the above palaeo-hydrogeological framework provides a basis for assessing the risk of arsenic in groundwater basins of south and south-eastern Asia.     

Cost‐effective conservation of an endangered frog under uncertainty

How should managers choose among conservation options when resources are scarce and there is uncertainty regarding the effectiveness of actions? Well‐developed tools exist for prioritizing areas for one‐time and binary actions (e.g., protect vs. not protect), but methods for prioritizing incremental or ongoing actions (such as habitat creation and maintenance) remain uncommon. We devised an approach that combines metapopulation viability and cost‐effectiveness analyses to select among alternative conservation actions while accounting for uncertainty. In our study, cost‐effectiveness is the ratio between the benefit of an action and its economic cost, where benefit is the change in metapopulation viability. We applied the approach to the case of the endangered growling grass frog (Litoria raniformis), which is threatened by urban development. We extended a Bayesian model to predict metapopulation viability under 9 urbanization and management scenarios and incorporated the full probability distribution of possible outcomes for each scenario into the cost‐effectiveness analysis. This allowed us to discern between cost‐effective alternatives that were robust to uncertainty and those with a relatively high risk of failure. We found a relatively high risk of extinction following urbanization if the only action was reservation of core habitat; habitat creation actions performed better than enhancement actions; and cost‐effectiveness ranking changed depending on the consideration of uncertainty. Our results suggest that creation and maintenance of wetlands dedicated to L. raniformis is the only cost‐effective action likely to result in a sufficiently low risk of extinction. To our knowledge we are the first study to use Bayesian metapopulation viability analysis to explicitly incorporate parametric and demographic uncertainty into a cost‐effective evaluation of conservation actions. The approach offers guidance to decision makers aiming to achieve cost‐effective conservation under uncertainty.     

Threats to intact tropical peatlands and opportunities for their conservation

Large, intact areas of tropical peatland are highly threatened at a global scale by the expansion of commercial agriculture and other forms of economic development. Conserving peatlands on a landscape scale, with their hydrology intact, is of international conservation importance to preserve their distinctive biodiversity and ecosystem services and maintain their resilience to future environmental change. We explored threats to and opportunities for conserving remaining intact tropical peatlands; thus, we excluded peatlands of Indonesia and Malaysia, where extensive deforestation, drainage, and conversion to plantations means conservation in this region can protect only small fragments of the original ecosystem. We focused on a case study, the Pastaza‐Marañón Foreland Basin (PMFB) in Peru, which is among the largest known intact tropical peatland landscapes in the world and is representative of peatland vulnerability. Maintenance of the hydrological conditions critical for carbon storage and ecosystem function of peatlands is, in the PMFB, primarily threatened by expansion of commercial agriculture linked to new transport infrastructure that is facilitating access to remote areas. There remain opportunities in the PMFB and elsewhere to develop alternative, more sustainable land‐use practices. Although some of the peatlands in the PMFB fall within existing legally protected areas, this protection does not include the most carbon‐dense (domed pole forest) areas. New carbon‐based conservation instruments (e.g., REDD+, Green Climate Fund), developing markets for sustainable peatland products, transferring land title to local communities, and expanding protected areas offer pathways to increased protection for intact tropical peatlands in Amazonia and elsewhere, such as those in New Guinea and Central Africa which remain, for the moment, broadly beyond the frontier of commercial development.     

Human Influence and Classical Biogeographic Predictors of Rare Species Occurrence

Biogeographic theory predicts that rare species occur more often in larger, less‐isolated habitat patches and suggests that patch size and connectivity are positive predictors of patch quality for conservation. However, in areas substantially modified by humans, rare species may be relegated to the most isolated patches. We used data from plant surveys of 81 meadow patches in the Georgia Basin of Canada and the United States to show that presence of threatened and endangered plants was positively predicted for patches that were isolated on small islands surrounded by ocean and for patches that were isolated by surrounding forest. Neither patch size nor connectivity were positive predictors of rare species occurrence. Thus, in our study area, human influence, presumably due to disturbance or introduction of competitive non‐native species, appears to have overwhelmed classical predictors of rare species distribution, such that greater patch isolation appeared to favor presence of rare species. We suggest conservation planners consider the potential advantages of protecting geographically isolated patches in human‐modified landscapes because such patches may represent the only habitats in which rare species are likely to persist. Influencia Humana y Predictores Biogeográficos Clásicos de la Ocurrencia de Especies Raras     

Seasonal dynamics of macro-algae in the South Lake of Tunis

The macro-algae communities observed in the south lake of Tunis are characterized by the predominance of nitrophilous algae which are in the order of biomass importance:Ulva, Cladophora andEnteromorpha. We have noted seasonal changes of alga distribution. The wind appears to be one of the most important factors influencing this distribution. The total biomass reaches a maximum in the spring. Rapid decomposition of the biomass leads to a severe ecological imbalance, resulting in crises of anoxia and fish death. A restoration project has already started. It aims at removal of contaminated muds and the introduction of a new circulation system. The main objectives of this work were to collect information on the distribution and biomass of the phytobenthic communities as a first step in the constitution of a database for further comparison.     

Patterns and biases of climate change threats in the IUCN Red List

International Union for Conservation of Nature (IUCN) Red List assessments rely on published data and expert inputs, and biases can be introduced where underlying definitions and concepts are ambiguous. Consideration of climate change threat is no exception, and recently numerous approaches to assessing the threat of climate change to species have been developed. We explored IUCN Red List assessments of amphibians and birds to determine whether species listed as threatened by climate change display distinct patterns in terms of habitat occupied and additional nonclimatic threats faced. We compared IUCN Red List data with a published data set of species’ biological and ecological traits believed to infer high vulnerability to climate change and determined whether distributions of climate change‐threatened species on the IUCN Red List concur with those of climate change‐threatened species identified with the trait‐based approach and whether species possessing these traits are more likely to have climate change listed as a threat on the IUCN Red List. Species in some ecosystems (e.g., grassland, shrubland) and subject to particular threats (e.g., invasive species) were more likely to have climate change as a listed threat. Geographical patterns of climate change‐threatened amphibians and birds on the IUCN Red List were incongruent with patterns of global species richness and patterns identified using trait‐based approaches. Certain traits were linked to increases or decreases in the likelihood of a species being threatened by climate change. Broad temperature tolerance of a species was consistently related to an increased likelihood of climate change threat, indicating counterintuitive relationships in IUCN assessments. To improve the robustness of species assessments of the vulnerability or extinction risk associated with climate change, we suggest IUCN adopt a more cohesive approach whereby specific traits highlighted by our results are considered in Red List assessments. To achieve this and to strengthen the climate change‐vulnerability assessments approach, it is necessary to identify and implement logical avenues for further research into traits that make species vulnerable to climate change (including population‐level threats).     

Parasitic wasps orient to green leaf volatiles

Summary Undamaged plants emit low levels of green leaf volatiles (GLVs), while caterpillar-damaged and artificially damaged plants emit relatively higher levels of certain GLVs. Female braconid parasitoids,Microplitis croceipes, oriented to both damaged plants and to individual GLVs in no-choice tests in a wind tunnel, but seldom oriented to undamaged plants. Female ichneumonid parasitoids,Netelia heroica, also oriented to individual GLVs in a wind tunnel. Males of both wasp species failed to orient to the GLVs. These data show that leaf-feeding caterpillars can cause the release of GLVs, and that parasitic wasps can respond to these odors by flying upwind (chemoanemotactic response), which brings the wasps to their caterpillar hosts. This supports the hypothesis that plants communicate with members of the third trophic level,i.e., plants under herbivore attack emit chemical signals that guide natural enemies of herbivores to sites of plant damage. In this interaction, the GLVs serve as tritrophic plant-to-parasitoid synomones. That parasitoids from two different wasp families oriented to GLVs suggests that the response may be widespread among the Hymenoptera.Mention of a commercial or proprietary product does not constitute an endorsement by the U.S. Department of Agriculture