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1.
报道了经恒定气相浓度N,N-二甲基甲酰胺(DMF)蒸汽曝露的雄性SD大鼠血液中以S-(N-甲基氨基甲酰)谷胱甘肽(SMG)为代表的N-甲基氨基甲酸硫酯的代谢生成及体内消长.实验所用封闭曝露系统内DMF蒸汽恒定浓度分别为φ=24×10-6(直至48h);φ=84×10-6及φ=213×10-6(均为72h).经(φ=24×10-6)×24h处理后,大鼠血清中N-甲基氨基甲酸硫酯达到稳态浓度47μmol/L,当DMF稳态蒸汽浓度φ=84×10-6时,体内血清N-甲基氨基甲酸硫酯稳态浓度为227μmol/L,在环境蒸汽浓度φ<84×10-6时,大鼠体内N-甲基氨基甲酸硫酯稳态浓度与环境中DMF蒸汽浓度呈线性关系.所产生的N-甲基氨基甲酸硫酯类物质体内半衰期在2.2~2.8h之间,体内半衰期值主要是由其生成速率决定的.高浓度DMF(φ=213×10-6)的曝露并未导致体内产生可检出水平的N-甲基氨基甲酸硫酯类物质,这可能是由于体内高浓度的DMF对其本身代谢的抑制作用所致.  相似文献   

2.
一株高浓度苯胺降解菌的分离   总被引:7,自引:0,他引:7  
通过驯化培养,从含苯胺的化工废水处理厂生化曝气池污泥中分离出一株高效苯胺降解菌 H62 ,在苯胺浓度低于3 000 mg/ L 的无机盐培养基中均可生长. H62 利用苯胺的最适温度为30 ℃,最适p H 为8 .0 ,当苯胺浓度在600 mg/ L 以下时,对该菌不表现出明显抑制作用.在含苯胺800 mg/ L 的无机盐溶液中,通气量为0 .4 L/min ,30 ℃,培养15 小时可使苯胺去除率达100 % .经鉴定,该菌株为不动杆菌属( Acinetobactersp .) .  相似文献   

3.
不同消毒剂对水中脊髓灰质炎病毒灭活的比较   总被引:4,自引:1,他引:3  
将脊髓灰质炎病毒( Polio V) 及不同消毒剂投加到模拟水样中,按不同接触时间1 ,3 ,10 ,30 min 取样,空斑定量. 当模拟水有机质含量 C O D 为20 mg/ L,病毒浓度n( P F U) ≈1 ×105 m L- 1 时,分别投加氯制剂有效氯ρ( Cl)16 mg/ L,接触30 min ;ρ( Cl O2) = 8 .0 mg/ L,30 min ; Cl+ Cl O2 联合消毒剂(5 .0 + 5 .0) mg/ L,30 min ;ρ( O3) = 1 .22 mg/ L,10 min 时;可使病毒彻底灭活. 它们使 Polio V 达到99 .99 % 灭活的浓度时间乘积( ρ×t) 值分别是662 .5 ,129 .5 ,200 .0 和3 .2 mg L- 1 min . 消毒效果( 顺序) 为 O3 > Cl O2 > Cl+ Cl O2 > Cl. 联合消毒灭活 Polio V 的效果为 Cl 的3 .3 倍,表明将 Cl 与 Cl O2 联合应用具有协同效应,优于传统的单一加氯消毒方式  相似文献   

4.
炼油废水中乳化态石油的生物处理可行性研究   总被引:1,自引:0,他引:1  
对炼油废水中乳化态石油进行了生物除油研究.分离筛选了一组降解石油的微生物,并培养形成性能良好的活性污泥菌剂,在2 L的好氧反应器中用6 ~10 h 时间把废水中140 mg L- 1 的乳化态石油降解到30 mg L- 1 以下,同时去除60 % 左右 C O D;整个处理过程不产渣、不排泥,处理效果良好.本研究为生物除油代替絮凝浮选除油提供了实用方法和科学依据  相似文献   

5.
本文介绍了利用美达棉纤维持载生物摸法处理石化废水中油的试验结果。当废水在柱内停留时间为6.3h,废水中油的处理效果是令人满意的。在同一含停留时间下入流水的CODcr从420mg/L变到1832mg/L时,出流水的CODcr在168.5mg/L以下。  相似文献   

6.
泥炭净化含油污水的技术和方法   总被引:3,自引:0,他引:3  
泥炭比重小,重量轻,富含有机质,是一种吸附能力很强的吸油。本文通过大量试验论述了泥炭净化含油污水的实验条件和方法。结果表明,泥炭经热加工处理后,由原来的亲水性变成疏水性,在含油污水中实现吸油而不吸水;采用不同的净化方式效果不同,静态方式泥炭可吸附其自身重量的5-10倍的油,动态吸油高达10倍以上。藓类泥炭,草本泥炭及木本泥炭对油的吸附效果不同,分别可吸附油6L/kg-9.5L/kg,4L/kg-8  相似文献   

7.
测定了由光合细菌 P9479 株与酵母 Y9407 株经原生质融合构建的跨界融合子 Foaz 及其亲株在净化豆制品废水反应中0 、0 .1 、5 .0 、10 .0 、100 .0 mg/ L Fe3 + 质量浓度和0 、150 、300 、400 、800 mg/ L Mg2 + 质量浓度下的β-类胡萝卜素色素含量及 B O D5 去除效率.结果表明, Fe3 + 对融合子 Foaz 及光合细菌中β- 类胡萝卜素的合成有明显的促进作用,当ρ( Fe3 + ) 为5 .0 mg/ L 时,融合子 Foaz 及光合细菌中β- 类胡萝卜素的质量分数w 达到最高水平,分别为4 .9 mg/g 和2 .4 mg/g .而 Mg2 + 对融合子及其亲株中β- 类胡萝卜素的合成有一定抑制作用  相似文献   

8.
生物滤池对气相与液相中污染物质的净化   总被引:4,自引:0,他引:4  
通过实验室研究探讨了生物滤池同时处理废水和废气的可行性。试验结果表明:在25℃-37℃条件下,甲苯废气的流量为90L/h,甲苯浓度为500mg/m^3;废水的流量为0.4L/h,CODcr浓度为400-750mg/L,甲苯与CODcr的去除率分别是70%-72%和86%-89%。  相似文献   

9.
原生质体转化构建有机磷农药降解工程菌   总被引:5,自引:0,他引:5  
降解有机磷农药甲胺磷、敌敌畏和对硫磷的菌株地衣芽孢杆菌 P12( Bacilluslicheniformis) 经溶菌酶处理获得原生质体,加入降解乐果的供体菌 G1 D N A,经ρ( P E G6 000) = 300 g L- 1 诱导,在液体再生培养基中振荡培养t= 20 h ,使其恢复细胞壁后,离心收集菌体,涂布于含乐果的基础培养基上,经筛选得一转化子 J P Z.其菌落形态明显不同于出发菌株,乐果平板连续传代10 次,性状保持稳定.在θ= 30 ℃,100 r/min 的培养条件下,3 d 内对ρ( 甲胺磷) = 0 .5 g L- 1 ,ρ( 敌敌畏) = 0 .2 g L- 1 ,ρ( 对硫磷) = 0 .1 g L- 1 ,ρ( 乐果) = 0 .3 g L- 1 的降解率分别为 Rd = 79 .1 % ,46 .7 % ,29 .4 % 和46 .4 % .  相似文献   

10.
TCC&TCS对废水生物处理中原生动物的毒性研究   总被引:2,自引:0,他引:2  
本文研究了TCC(2,2,4’—Trichlorocarbanilide)、TCS(2,2,4’—Trichloro-2-hydroxydiphenyl)对废水生物处理中的原生动物的急性毒性作用,结果表明:(1)TCC对原生动物的48hLC50为25000μg/L,TCS48hLC50为23000μg/L;TCC&TCS浓度与原生动物的半数致死时间LT50呈明显的负相关。(2)TCC&TCS对原生动物的最大无作用浓度分别为15mg/L和11mg/L,这提示污染源排放的废水到达曝气池时TCC&TCS的含量应低于15mg/L和11mg/L。  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.
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   

14.
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   

15.
Parasitic wasps orient to green leaf volatiles   总被引:12,自引:0,他引:12  
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  相似文献   

16.
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  相似文献   

17.
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.  相似文献   

18.
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.  相似文献   

19.
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.  相似文献   

20.
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