Mo6+对活性污泥系统反硝化性能的影响

采用对比实验的方法,在不同初始硝酸盐氮和COD质量浓度的条件下,对人工模拟的活性污泥系统投加不同质量浓度的Mo6 ,以此考察Mo6 对活性污泥系统反硝化性能的影响。结果发现,Mo6 的质量浓度小于5mg?L-1以下时能够促进硝酸盐氮的去除,质量浓度为1mg?L-1时促进效果最好。Mo6 的质量浓度在4mg?L-1以下时,可以使COD去除效率增加,质量浓度为2mg?L-1时有最佳促进作用。Mo6 的质量浓度小于1g?L-1时可提高反硝化活性污泥的TTC-脱氢酶活性,过高质量浓度则表现出抑制作用。综合Mo6 的对硝酸盐氮和COD去除的影响规律以及对活性污泥TTC-脱氢酶活性的影响,认为Mo6 在质量浓度为1mg?L-1时对反硝化的促进作用最强。     

螯台球菌TAD1在高温曝气生物滤池中的异养硝化-反硝化性能

初步实验证实螯台球菌(Chelatococcus daeguensis)TAD1在高温下具有异养硝化-反硝化的能力,为验证其可应用性,采用曝气生物滤池工艺,研究了TAD1在温度为50℃的异养硝化-反硝化性能.结果表明,TAD1在曝气生物滤池中可同时进行好氧反硝化和异养硝化.当分别以硝氮、氨氮及硝氮和氨氮为氮源时,12 h的氮去除率均达到100%,氮的去除能力分别为12.67 mg.L-.1h-1、3.62 mg.L-.1h-1及16.53 mg.L-.1h-1.虽然在脱氮过程中,亚硝盐在6 h迅速积累到76 mg.L-1(硝氮为氮源)和52.6 mg.L-1(硝氮和氨氮为氮源),但在随后的几个小时内又快速降低至0(检测限之外).因而,TAD1具有应用于高温生物脱氮工艺的能力和优势.     

氨氮在天然沸石上的吸附及解吸

研究了氨氮浓度、温度、时间、共存阳离子等对氨氮在天然沸石上吸附的影响 ,比较了HCl及NaCl溶液对氨氮解吸的效果 ,初步探讨了沸石吸附氨氮后自然硝化的规律 .结果显示 ,随着氨氮浓度的增大或温度的升高 ,沸石吸附量上升 ,最大可达 1 1 5mg·g- 1 ;沸石吸附的初始阶段 (0— 8h) ,沸石吸附量随时间显著上升 ,此后趋于平缓 ;在不同阳离子共存的情况下 ,K 可使沸石吸附量降低 5 0 %以上 ;HCl溶液对氨氮解吸的效果好于NaCl溶液 ,解吸率最高可达到 6 0 % ;沸石吸附的氨氮在硝化细菌作用下可转化为硝氮 ,溶液中硝氮浓度 1 2 0h后可达 9mg·l- 1 ,在总氮中比率达到 2 7% .     

低温下曝气生物滤池预处理污染河水的试验研究

采用两段曝气生物滤床串联工艺预处理入滇新运粮河河水,研究了其在冬天低温条件下对有机物和氨氮的去除效果,并考察了pH值的变化。结果表明,在进水流量为2.4 m3.d-1、水温为13-16℃、原水ρ（CODCr）为66.46-107.82 mg·L-1、ρ（氨氮）为22.15-30.68 mg·L-1的水质特征条件下,系统对CODCr和氨氮的去除率分别为36.08%-50.37%和76.98%-93.56%。其中,碳氧化段以去除有机物为主,硝化段以去除氨氮为主;系统中硝酸氮质量浓度明显升高,无亚硝氮的积累;装置对总氮的平均去除率为19.56%,可以认为总氮的去除是同步硝化反硝化的结果。系统中pH值有所变化但维持在7-8之间,其中碳氧化段pH值升高,硝化段pH值下降。系统对有机物和氨氮良好的去除效果为后续进一步的生物处理提供了条件。     

氨氧化木质素作为硝化抑制剂的研究

通过室内培养实验对氨氧化木质素(AOL)的硝化抑制作用进行了探讨。在相同条件下,分别加AOL和DCD处理的铵态氮质量分数都要比未加硝化抑制剂处理的高;相应地,在开始阶段硝态氮质量分数也要比未加硝化抑制剂处理的低。研究结果表明,AOL作为硝化抑制剂是有效果的。     

水动力条件下苦草对沉积物氮释放的影响

在浅水湖泊中,沉积物易受到水流的扰动释放出原本沉降于其中的氮营养盐。沉水植物一方面能够减少水动力的作用,一方面又能够吸收沉积物中的和已经释放到上覆水中的氮营养盐供其生长同时改善水质。因此,研究沉水植物对沉积物中氮营养盐释放的影响具有很重要的实际意义。借助自主开发的生态水槽,研究苦草（Vallisneria spiraslis L.）在动、静水条件下对沉积物氮的释放的影响。实验装置包括四组水槽,两组动水槽中的一组只铺沉积物,另一组在沉积物上种植苦草,两组静水槽也如此设置。在40 d的实验周期内,我们在实验始末采集沉积物样品,在每一个采样时间点（0、1、3、6、12、20、30、40 d）采集水样,并测定沉积物中总氮含量,原水样中的总氮含量以及过滤水样中的总氮、氨氮、硝氮和亚硝氮的含量。研究结果表明：没有苦草的实验组0～1 cm沉积物层总氮下降幅度较大,有苦草的实验组表面0～1 cm沉积物层氮含量较高。苦草从根系周围沉积物中吸收氮,1～4 cm沉积物层的吸收量多于4～8 cm沉积物层。各水槽上覆水中总氮含量在第1天就有较大的增加,从0.09 mg·L^-1分别升到0.60、0.50、0.379、0.36 mg·L^-1在水动力影响下的增加更显著,后缓慢上升。动水槽中进入到上覆水的氮中80%以上是以溶解态氮形式存在,静水槽中这个比例高达90%以上。苦草对溶解态和颗粒态氮的去除率最高可达27.6%和84.3%。3种氮形态中硝态氮的含量比重较大,在动水条件下,苦草对氨氮,硝氮和亚硝氮的去除率最高可达30.0%、25.0%和60.0%。但苦草对水中氮形态的比例的影响并不明显。以上结果说明水动力条件明显促进沉积物中氮的释放,沉水植物苦草通过保护表层沉积物,吸收下层沉积物中氮,去除进入上覆水中的氮,特别是颗粒态氮和溶解态中的亚硝态     

鄱阳湖沉积物与水界面氮的迁移特征及污染评价

通过现场采样及室内分析测试,在沉积物间隙水氮含量分析的基础上,探讨了鄱阳湖沉积物与水界面氮的迁移特征与扩散通量,并对鄱阳湖表层沉积物氮的污染状况进行了评价。结果表明,鄱阳湖表层沉积物间隙水中溶解性总氮的平均含量为1.32 mg·L~(-1),无机氮中以硝态氮含量最高,占总氮的45.4%以上。表层沉积物间隙水中氮的含量在空间分布上表现为北部站点(L6与L7)相对较高,且其浓度均高于上覆水中氮浓度,表明沉积物间隙水中氮有较强的释放趋势,其中溶解性总氮在间隙水与上覆水之间的扩散相对较强,其扩散通量略大于硝态氮,各站点平均扩散通量分别为0.91 mg·m~(-2)·d~(-1)和0.89mg·m~(-2)·d~(-1),且大部分站点沉积物表现为上覆水中氮的源。此外,鄱阳湖各站点总氮污染指数、有机指数、有机氮平均值分别为1.082%、0.161%、0.103%,总氮污染指数与有机指数为Ⅱ级标准,有机氮指数为Ⅲ级标准,但站点L2呈现出有机污染与有机氮污染,存在一定的安全风险,水体面临富营养化威胁。该研究可为鄱阳湖内源污染和富营养化防治提供一定的理论依据。     

一株假单胞菌WSH1001的脱氮特性

研究了假单胞菌WSH 1001(Pseudomonas sp.WSH 1001)对氨氮及硝态氮去除性能的影响因素以及WSH 1001在实际污水处理中的应用情况,并将其与市售硝化菌制剂的脱氮性能进行了比较.结果表明:菌株前培养方式对后续的氮去除性能影响较大,葡萄糖或柠檬酸钠是最适碳源;在20～35℃的范围内,温度对氨氮及硝态氮的去除率没有明显影响;溶氧浓度对氨氮及硝态氮的去除效率影响很大;金属离子Cu2+、Co2+和Zn2+极大地抑制了该菌株对氨氮及硝态氮的去除能力;菌株WSH 1001在6 h内对70 mg L-1的氨氮去除率高达99.64%,总氮去除率达94.94%,在8 h内对50 mgL-1的硝态氮去除率达到了87.69%,说明该菌株同时具备硝化和反硝化的能力;当菌株WSH 1001应用于实际污水(初始氨氮和COD浓度分别为44和113 mg L-1)、并额外添加3 g L-1的丁二酸钠作为外加碳源时,氨氮去除率在6 h时达到99.23%,较其它市售硝化菌制剂脱氮性能高.该研究表明假单胞菌WSH 1001在实际污水的处理上具有较好的应用潜能.     

沉水植物对水-沉积物界面各形态氮含量的影响

在室内模拟条件下研究沉水植物对水-沉积物界面的上覆水、不同层次的间隙水和沉积物中不同形态氮含量的影响.结果表明:总体上,上覆水和间隙水中不同形态氮含量的顺序为有机氮＞氨氮＞硝态氮;沉积物中可交换态无机氮以氨氮为主,沉水植物的存在并没有改变这一格局.不同处理不同层次的间隙水中,各形态氮含量均为下层＞中层＞上层,但沉积物中氨氮和硝态氮含量变化规律不明显.水-沉积物界面氨氮和硝态氮含量呈现明显季节性变化.总之,水-沉积物界面氨氮是沉积物向上覆水扩散的主要氮组分,沉水植物降低了氨氮和硝态氮的扩散通量.     

电极生物膜自养脱氮系统中的电化学作用

设计构建三维电极生物膜反应器,成功启动后稳定运行,在全自养条件下能较好地处理低碳氮比含氮废水.结果表明,在进水不含有机碳源,电流强度为30 mA,电流密度为0.012 mA·cm-2,运行周期24 h的实验条件下,反应器处理进水氨氮浓度为30 mg·L-1的废水时,氨氮转化率达到了90.3%,总氮去除率为70.0%;处理进水硝态氮浓度为30 mg·L-1的废水时,硝态氮去除率达到了82.7%.在考察电极生物膜反应器脱氮性能的同时,探讨系统中纯电化学作用的脱氮能力.结果显示电极生物膜处理氨氮废水的系统中,纯电化学脱氮作用为系统总脱氮能力的10%左右;而处理硝态氮废水的电极生物膜系统中,无电化学还原去除NO-3-N作用.     

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.     

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     

Potential for Electropositive Metal to Reduce the Interactions of Atlantic Sturgeon with Fishing Gear

Atlantic sturgeon (Acipenser oxyrhynchus) populations have been declared either endangered or threatened under the U.S. Endangered Species Act. Effective measures to repel sturgeon from fishing gear would be beneficial to both fish and fishers because they could reduce both fishery‐associated mortality and the need for seasonal and area closures of specific fisheries. Some chondrostean fishes (e.g., sturgeons and paddlefishes) can detect weak electric field gradients (possibly as low as 5 Μv/cm) due to arrays of electroreceptors (ampullae of Lorenzini) on their snout and gill covers. Weak electric fields, such as those produced by electropositive metals (typically mixtures of the lanthanide elements), could therefore potentially be used as a deterrent. To test this idea, we recorded the behavioral responses of juvenile Atlantic sturgeon (31–43 cm fork length) to electropositive metal (primarily a mixture of the lanthanide elements neodymium and praseodymium) both in the presence and absence of food stimuli. Trials were conducted in an approximately 2.5 m diameter × 0.3 m deep tank, and fish behaviors were recorded with an overhead digital video camera. Video records were subsequently digitized (x, y coordinate system), the distance between the fish and the electropositive metal calculated, and data summarized by compiling frequency distributions with 5‐cm bins. Juvenile sturgeon showed clear avoidance of electropositive metal but only when food was present. On the basis of our results, we conclude that the electropositive metals, or other sources of weak electric fields, may eventually be used to reduce the interactions of Atlantic sturgeon with fishing gear, but further investigation is needed. El Potencial del Metal Electropositivo para Reducir las Interacciones del Esturión Atlántico con Instrumentos de Pesca Bouyoucos, Bushnell & Brill 13–003     

The role of time and species identities in spatial patterns of species richness and conservation

Many conservation actions are justified on the basis of managing biodiversity. Biodiversity, in terms of species richness, is largely the product of rare species. This is problematic because the intensity of sampling needed to characterize communities and patterns of rarity or to justify the use of surrogates has biased sampling in favor of space over time. However, environmental fluctuations interacting with community dynamics lead to temporal variations in where and when species occur, potentially affecting conservation planning by generating uncertainty about results of species distribution modeling (including range determinations), selection of surrogates for biodiversity, and the proportion of biodiversity composed of rare species. To have confidence in the evidence base for conservation actions, one must consider whether temporal replication is necessary to produce broad inferences. Using approximately 20 years of macrofaunal data from tidal flats in 2 harbors, we explored variation in the identity of rare, common, restricted range, and widespread species over time and space. Over time, rare taxa were more likely to increase in abundance or occurrence than to remain rare or disappear and to exhibit temporal patterns in their occurrence. Space–time congruency in ranges (i.e., spatially widespread taxa were also temporally widespread) was observed only where samples were collected across an environmental gradient. Fifteen percent of the taxa in both harbors changed over time from having spatially restricted ranges to having widespread ranges. Our findings suggest that rare species can provide stability against environmental change, because the majority of species were not random transients, but that selection of biodiversity surrogates requires temporal validation. Rarity needs to be considered both spatially and temporally, as species that occur randomly over time are likely to play a different role in ecosystem functioning than those exhibiting temporal structure (e.g., seasonality). Moreover, temporal structure offers the opportunity to place management and conservation activities within windows of maximum opportunity.     

Main nutrient compounds in food bodies of Mexican <Emphasis Type="Italic">Acacia</Emphasis> ant-plants

Summary. Myrmecophytic plants use obligate ant mutualists as a constitutive indirect defence mechanism. These plants often produce cellular food bodies (FBs) to nourish their resident ants. Lipids, proteins, and even highly specialised compounds such as glycogen have been reported from FBs, but detailed chemical analyses of FB composition have so far been presented only for Southeast Asian Macaranga and Central American Piper myrmecophytes. Here we report the chemical composition of FBs of five myrmecophytic Acacia (Fabaceae) species from Mexico using HPLC (carbohydrates and proteins) and GC-MS (lipids). Feeding experiments revealed no hints on any use of external food sources by the inhabiting Pseudomyrmex ants. These ants obviously rely completely on FBs and extrafloral nectar provided by their hosts. The total content of nutrients in Acacia FBs was 15-25% of FB dry mass, being much lower than in Macaranga or Piper FBs. Proteins were dominating (8-14 % dm) in Acacia FBs and thus were present in higher amounts than in Macaranga FBs, yet in lower amounts than in Piper. Lipids contributed 1-9 % of dry mass, showing a lower proportion than in FBs of Macaranga or Piper. Carbohydrates made up 3-11 % dm, reaching in most Acacia species the same range as observed in Macaranga and in Piper FBs. Water content was 18-24 % of FB fresh mass, and structural tissue obviously made up a much higher proportion in Acacia FBs than in Macaranga or Piper FBs. Both characters might represent an adaptation to producing FBs unprotected at the leaf tips under dry conditions. Acacia FBs contain all amino acids and all fatty acids that are considered essential for insects, and their contents of lipids and proteins are higher than in the leaves from which they are ontogenetically derived. This indicates a putatively adaptive enrichment of nutritionally valuable compounds in structures functioning as ant-food.     

Examining the uncertain origin and management role of martens on Prince of Wales Island,Alaska

Conservation biologists are generally united in efforts to curtail the spread of non‐native species globally. However, the colonization history of a species is not always certain, and whether a species is considered non‐native or native depends on the conservation benchmark. Such ambiguities have led to inconsistent management. Within the Tongass National Forest of Alaska, the status of American marten (Martes americana) on the largest, most biologically diverse and deforested island, Prince of Wales (POW), is unclear. Ten martens were released to POW in the early 1930s, and it was generally believed to be the founding event, although this has been questioned. The uncertainty surrounding when and how martens colonized POW complicates management, especially because martens were selected as a design species for the Tongass. To explore the history of martens of POW we reviewed other plausible routes of colonization; genetically and isotopically analyzed putative marten fossils deposited in the late Pleistocene and early Holocene to verify marten occupancy of POW; and used contemporary genetic data from martens on POW and the mainland in coalescent simulations to identify the probable source of the present‐day marten population on POW. We found evidence for multiple routes of colonization by forest‐associated mammals beginning in the Holocene, which were likely used by American martens to naturally colonize POW. Although we cannot rule out human‐assisted movement of martens by Alaskan Natives or fur trappers, we suggest that martens be managed for persistence on POW. More generally, our findings illustrate the difficulty of labeling species as non‐native or native, even when genetic and paleo‐ecological data are available, and support the notion that community resilience or species invasiveness should be prioritized when making management decisions rather than more subjective and less certain conservation benchmarks.