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1.
微生物菌群一直是活性污泥研究过程中的关键问题,近年来通过分子生物学等研究手段已经发现动胶菌是活性污泥微生物菌群中的优势细菌.本文以活性污泥微生物菌群为出发点,重点梳理了动胶菌属分类学研究历史和现状,并建议在前期命名过程中出现的垂(悬)丝状动胶菌和生枝动胶菌ATCC 19623株及ATCC 25935株不应再作为动胶菌属细菌对待.同时介绍了动胶菌属细菌的基本特性及其在活性污泥法处理废水中降解有机物、除磷脱氮和吸附重金属离子等方面的应用,以及动胶菌胞外多聚物的组成和动胶菌优良菌株的选育.我们及合作者最近分析了两个喜树脂动胶菌的基因组并鉴定出参与菌胶团形成的一个大型基因簇,也实现了基因定点敲除等遗传操作.今后研究应重点关注动胶菌分子遗传学、功能基因组学及胞外多聚物生物合成和菌胶团形成机理、化学结构和性质.  相似文献   

2.
选择太湖梅梁湾的表层沉积物作为实验对象,研究了水动力与表面活性剂协同作用下,双酚A吸附行为的变化特征.结果表明,当CTMAB(十六烷基三甲基溴化铵)浓度在1.0倍临界胶束浓度(CMC)以下时,切应力的改变对双酚A在沉积物上的吸附量基本无影响;其吸附量随CTMAB浓度的增大而增大,0.1倍CMC、0.5倍CMC和1.0倍CMC的CTMAB条件下,双酚A的吸附量较0 CMC分别增大了0.18倍、0.54倍和0.62倍;相对于Freundich模型,其吸附等温线更符合线性模型.当CTMAB浓度高于CMC时,双酚A在沉积物上的吸附量和吸附平衡时间均随切应力的增加而减小,在切应力和低浓度CTMAB共同作用时,以切应力促进吸附平衡作用为主;而当切应力和高浓度CTMAB共同作用时,以CTMAB的作用为主.水动力和CTMAB共同作用下的双酚A的吸附过程满足准二级吸附动力学方程.  相似文献   

3.
分析了Ⅰ-Ⅲ从动齿轮内孔变形的原因,提出了相应的对策.  相似文献   

4.
为了探讨镉对骨的影响及机制,选取7周龄C57BL/6J小鼠给予氯化镉2 mg.kg-1腹腔注射,每周2次,染毒4周后进行了骨力学参数的测量.结果显示,暴露组股骨的最大弯曲应力及弹性模量降低,骨灰干重比下降.体外结果显示,氯化镉(CdCl2)的暴露影响人成骨肉瘤细胞MG-63的细胞形态、活力及增殖,并且呈剂量依赖性.因此,氯化镉暴露可导致小鼠骨量下降和骨力学性能下降,并对成骨细胞有明显的毒性.  相似文献   

5.
本文从电磁场变换入手,举例说明感应电动势的大小及区分感生、动生电动势与参照系有关.  相似文献   

6.
隆德煤矿2-2煤层开采受顶板第四系沙层水和基岩裂隙水的威胁.采动影响破坏了地下水的原始水动力场,仅利用地下水动力学方法难以准确确定地下水来源.利用不同含水层水中环境同位素的差异,结合水化学分析可解释13C同位素异常的形成机制、识别隆德矿井涌水来源,为矿井涌水量预测、水害防治提供依据.与侏罗纪基岩裂隙水相比,第四系沙层水常规水化学成分差异不明显,但有高现代碳百分比(pMC)、氘(D)略微富集的特征.分析结果显示,1-1煤层开口疏放水、205采空区积水和203工作面顶板水为第四系沙层水与基岩裂隙水的混合产物,其中,砂层水混入比例分别为27.77%、23.8%和4.21%.表明同位素结合水化学因子分析是正确识别矿井涌水来源、混合比例的有效手段.  相似文献   

7.
杉木生长对南方涛动的可能响应   总被引:3,自引:0,他引:3  
对杉木中心产区边缘杉木个体年轮生长规律进行了研究,分析了杉木年轮生长的特点,建立杉木个体年轮的时间模型,求算年轮指数,通过对20多年来南方涛动指数第一、第二主分量与杉木人工林生长关系的研究,探讨南方涛动对杉木生长的可能影响,以南方涛动第一、第二主分量为自变量,建立杉木人工林年轮生长模型,模拟精度达91.05%,说明南方涛动对杉木人工林胸径生长可能存在一定影响(α=0.05)。  相似文献   

8.
自然和生态旅游认定计划承认和奖励在澳大利亚真正的自然旅游和生态旅游经营方式.这是一个产业界椎动的志愿举措,是咨询了经营者、被保护地区的管理者和其他关键人士而开展起来的。本文讨论了NEAP的开展情况,它与其他计划的关系及其在国际环境中的地位.  相似文献   

9.
臭氧和基于臭氧的高级氧化工艺降解农药的研究进展   总被引:1,自引:0,他引:1  
刘超  强志民  张涛  张忠国 《环境化学》2011,30(7):1225-1235
由于农药的环境持久性以及毒性,饮用水源中的农药微污染日益受到水处理行业的关注.在众多水处理工艺中,由于其高效氧化去除有机污染物及控制嗅味等特点,臭氧及其相关高级氧化技术的应用已日趋广泛.本文综述了这些氧化技术对多类代表性农药(包括有机氯、有机磷、氨基甲酸酯、氯乙酰胺和三嗪等)的降解效能,详细讨论了农药的降解效率、反应动...  相似文献   

10.
为研究连通水体中浮游甲壳动物的群落结构,于2018年6月至2019年3月,对常德市柳叶湖、穿紫河和沅江常德市区河段组成的连通水体浮游甲壳动物和理化环境进行每季度一次的采样调查.共发现浮游甲壳动物27种,其中桡足类10种,枝角类17种.连通水体浮游甲壳动物丰度变化范围为1-132 ind./L,沅江常德市区河段浮游甲壳动...  相似文献   

11.
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.  相似文献   

12.
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.  相似文献   

13.
Protected areas (PAs) are often implemented without consideration of already existing PAs, which is likely to cause an overrepresentation of certain biophysical conditions. We assessed the representativeness of the current PA network with regard to the world's biophysical conditions to highlight which conditions are underprotected and where these conditions are located. We overlaid terrestrial and marine PAs with information on biophysical conditions (e.g., temperature, precipitation, and elevation) and then quantified the percentage of area covered by the PA network. For 1 variable at a time in the terrestrial realm, high temperature, low precipitation, and medium and very high elevation were underrepresented. For the marine realm, low and medium sea surface temperature (SST), medium and high sea surface salinity (SSS), and the deep sea were underrepresented. Overall, protection was evenly distributed for elevation across the terrestrial realm and SST across the marine realm. For 2 variables at a time, cold and very dry terrestrial environments had mostly low protection, which was also the case for low SST and low and medium SSS across most depths for marine environments. Low protection occurred mostly in the Sahara and the Arabian Peninsula for the terrestrial realm and along the Tropic of Capricorn and toward the poles for the marine realm. Although biodiversity measures are of prime importance for the design of PA networks, highlighting biophysical gaps in current PAs adds a frequently overlooked perspective. These gaps may weaken the potential of PAs to conserve biodiversity. Thus, our results may provide useful insights for researchers, practitioners, and policy makers to establish a more comprehensive global PA network.  相似文献   

14.
Summary The adaptation of defensive secretions to their target organisms was examined for the abdominal gland secretions ofBledius furcatus, B. spectabilis andB. arenarius. Therefore the target organisms of the secretion of theseBledius species (i.e. their predators) had to be identified. At the collection sites examined these were the earwigLabidura riparia, the antCataglyphis bicolor, the flyLispe candicans, different carabids of the generaPogonus, Dichirotrichus, Dyschirius, Bembidion andCalathus and the wading birdsHaematopus ostralegus andCalidris alba. The secretion of the abdominal glands contains the toxin ptoluquinone dissolved in either-dodecalactone and 1-undecene (B. furcatus andB. spectabilis) or in octanoic acid and octyloctanoate (B. arenarius). The ratio of these solvents is species-specific. Application experiments using some of the natural insect predators (L. riparia, C. bicolor, Pogonus, Di. gustavii, Dyschirius) revealed that these solvent ratios provided a more effective deterrent than other possible ratios. Thus by combining the solvents in certain ratios, the capability of cuticular penetration and therefore the effectiveness of the defensive secretions are adapted to their natural targets.  相似文献   

15.
The politics of development includes subtexts of choice, as underpinned by community consensus (or lack of it), against the larger backdrop of a liberal democracy, with its intricate power structures that influence the choice of concepts and often lead to complicity rather than consent. A dilemma exists between the understanding of field-level practitioners and that of academics, whose understandings of progress differ. Progress can (and often does) imply long-term change across generations whereas development is often more a matter of crisis management and delivering tangible results to end-users. This makes it a bone of contention across political systems, irrespective of local or global dynamics. Development can emerge as a tool to be wielded for power and further political mileage at the expense of progress. Progress cannot be studied as a counterpoint to development as the sense of history is often missing in development interventions. Development tends to be piecemeal as its very logic often stems from the rationale of power. This is not to suggest, however, that development is only about politics; it is definitely more than the politics of everyday life and involves all of civil society that requires its critical and immediate attention. In this sense, it has become a priority for politicians with an underlying agenda designed to out-manouevre dissent and all statements of protest.  相似文献   

16.
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.  相似文献   

17.
As landscapes continue to fall under human influence through habitat loss and fragmentation, fencing is increasingly being used to mitigate anthropogenic threats and enhance the commercial value of wildlife. Subsequent intensification of management potentially erodes wildness by disembodying populations from landscape-level processes, thereby disconnecting species from natural selection. Tools are needed to measure the degree to which populations of large vertebrate species in formally protected and privately owned wildlife areas are self-sustaining and free to adapt. We devised a framework to measure such wildness based on 6 attributes relating to the evolutionary and ecological dynamics of vertebrates (space, disease and parasite resistance, exposure to predation, exposure to limitations and fluctuations of food and water supply, and reproduction). For each attribute, we set empirical, species-specific thresholds between 5 wildness states based on quantifiable management interventions. We analysed data from 205 private wildlife properties with management objectives spanning ecotourism to consumptive utilization to test the framework on 6 herbivore species representing a range of conservation statuses and commercial values. Wildness scores among species differed significantly, and the proportion of populations identified as wild ranged from 12% to 84%, which indicates the tool detected site-scale differences both among populations of different species and populations of the same species under different management regimes. By quantifying wildness, this framework provides practitioners with standardized measurement units that link biodiversity with the sustainable use of wildlife. Applications include informing species management plans at local scales; standardizing the inclusion of managed populations in red-list assessments; and providing a platform for certification and regulation of wildlife-based economies. Applying this framework may help embed wildness as a normative value in policy and mitigate the shifting baseline of what it means to truly conserve a species.  相似文献   

18.
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.  相似文献   

19.
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.  相似文献   

20.
Abstract: In the United States, as elsewhere, a growing debate pits national energy policy and homeland security against biological conservation. In rural communities the extraction of fossil fuels is often encouraged because of the employment opportunities it offers, although the concomitant itinerant workforce is often associated with increased wildlife poaching. We explored possible positive and negative factors associated with energy extraction in the Greater Yellowstone Ecosystem (GYE), an area known for its national parks, intact biological diversity, and some of the New World's longest terrestrial migrations. Specifically, we asked whether counties with different economies—recreation (ski), agrarian (ranching or farming), and energy extractive (petroleum)—differed in healthcare (gauged by the abundance of hospital beds) and in the frequency of sexual predators. The absolute and relative frequency of registered sex offenders grew approximately two to three times faster in areas reliant on energy extraction. Healthcare among counties did not differ. The strong conflation of community dishevel, as reflected by in‐migrant sexual predators, and ecological decay in Greater Yellowstone is consistent with patterns seen in similar systems from Ecuador to northern Canada, where social and environmental disarray exist around energy boomtowns. In our case, that groups (albeit with different aims) mobilized campaigns to help maintain the quality of rural livelihoods by protecting open space is a positive sign that conservation can matter, especially in the face of rampant and poorly executed energy extraction projects. Our findings further suggest that the public and industry need stronger regulatory action to instill greater vigilance when and where social factors and land conversion impact biological systems.  相似文献   

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