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1.
用气-质联用仪(GC-MS)监测厌氧条件下溶液中3,3’,4,4’-四氯联苯(BZ#77)被纳米级零价铁、Ni/Fe和Co/Fe双金属脱氯的情况,并尝试了用纳米级Co/Fe脱氯污染沙土中的四氯联苯,GC-MS结果表明:在3,3’,4,4’-四氯联苯浓度为10mg·l-1的乙醇/水体系中,纳米级Fe,Ni/Fe,Co/Fe的脱氯率分别为23.4%,68.6%和74.2%,其中,Co/Fe效果最好.溶液初始pH值为酸性时,纳米Co/Fe完全脱氯溶液中的3,3’,4,4’-四氯联苯可在几小时内实现,而溶液的离子强度对脱氯反应影响不大.对于模拟污染沙土含量为100mg·kg^-1的3,3’,4,4’-四氯联苯,10d后约11%的四氯联苯被纳米Co/Fe脱氯,添加乙醇可使脱氯率增加到25%,但不能完全脱氯.同位素实验证明,纳米Co/Fe脱氯3,3’,4,4’-四氯联苯是逐步进行的,氢取代苯环上的氯,氢原子源自反应介质中的水,最终脱氯产物为联苯.  相似文献   

2.
纳米Co/Fe脱氯3,3',4,4'-四氯联苯(BZ#77)   总被引:5,自引:2,他引:3  
用气质联用仪(GC-MS)监测厌氧条件下溶液中3,3',4,4'-四氯联苯(Fe和Co/Fe双金属脱氯的情况.并尝试了用纳米级Co/Fe脱氯污染沙土中的四氯联苯,GC-MS结果表明:在3,3',4,4'-四氯联苯浓度为10mg·1-1的乙醇/水体系中,纳米级Fe,Ni/Fe,Co/Fe的脱氯率分别为23.4%,68.6%和74.2%,其中,Co/Fe效果最好.溶液初始pH值为酸性时,纳米Co/Fe完全脱氯溶液中的3,3',4,4'-四氯联苯可在几小时内实现,而溶液的离子强度对脱氯反应影响不大.对于模拟污染沙土含量为100mg·kg-1的3,3',4,4'-四氯联苯,10d后约11%的四氯联苯被纳米Co/Fe脱氯,添加乙醇可使脱氯率增加到25%,但不能完全脱氯.同位素实验证明,纳米Co/Fe脱氯3,3',4,4'-四氯联苯是逐步进行的,氢取代苯环上的氯,氢原子源自反应介质中的水,最终脱氯产物为联苯.  相似文献   

3.
光电协同催化降解2-氯-4-甲氧基苯酚   总被引:3,自引:1,他引:2  
以2-氯-4-甲氧基苯酚作为模型物,以TiO2为催化剂,低压汞灯作为光源,采用外循环悬浮态多相光催化反应体系,考察紫外光与电场协同催化降解的影响因素,实验结果表明,2-氯-4-甲氧基苯酚初始浓度为0.0125mmol·l-1,TiO2用量250mg·l-1,循环流量20L·h-1,pH值为10,外加偏压3V,曝气,反应时间270min时,2-氯-4-甲氧基苯酚降解率可达到98.7%.  相似文献   

4.
利用共价三嗪有机框架材料(CTF-1)对4-氯酚(4-CP)、2,4-二氯酚(2,4-DCP)、2,4,6-三氯酚(2,4,6-TCP)和五氯酚(PCP)等4种不同氯原子取代数目的氯酚类污染物进行光催化降解研究,探讨了底物结构对氯酚脱氯降解效率的影响及机制.结果表明,氯酚脱氯降解过程明显受苯环氯原子取代数目的影响,氯原子数目越多,脱氯降解效率越高,氯原子数目与表观速率常数呈显著正相关,氯酚降解及脱氯速率均为:PCP>2,4,6-TCP>2,4-DCP>4-CP.对CTF-1光催化降解氯酚机制研究表明,活性物种在反应中不起作用,体系反应机制为针对氯酚上取代氯位点进行水解脱氯过程.本研究结果为深入揭示氯酚脱氯降解机制提供了理论依据,也为光催化技术处理卤代酚类废水提供了技术参考.  相似文献   

5.
二氧化钛催化下的氯代二苯并-对-二恶英光解反应   总被引:6,自引:0,他引:6  
本文利用中压汞灯作光源,研究了氯代二苯并-对-二恶英(CDDs,包括CDD,DCDD,PeCDD和OCDD)在二氧化钛催化下的光解反应,并讨论了二氧化钛浓度、pH值、反应温度以及取代氯原子数目等对反应速率的影响.结果表明,二氧化钛能有效地催化CDDs的光降解,在室温下,4h内DCDD,PeCDD,OCDD分别降解了87.2%,84.6%,91.2%,反应温度和二氧化钛浓度是控制该反应的主要因素.  相似文献   

6.
白腐真菌降解五氯酚的初步研究   总被引:1,自引:1,他引:0  
曾斌  宁大亮  王慧 《环境化学》2008,27(2):181-185
研究了白腐真菌黄孢原毛平革菌在不同营养条件下对五氯酚的降解.采用土豆葡萄糖液体培养基,接种后第2天投加PCP,在胞外木质素降解酶活性极低的真菌反应体系中,五氯酚能够有效降解,4d内10mg·1-1五氯酚降解率达到98%;采用高氮培养基,接种后第6天投加五氯酚,在胞外木质素酶含量极低的真菌反应体系和不含胞外酶的菌丝体反应体系中,五氯酚均能有效降解,1d内降解率分别达到56%和22%;采用低氮培养基,接种后第6天投加五氯酚,在胞外木质素酶含量较高的真菌反应体系、胞外酶液反应体系和不含胞外酶的菌丝体反应体系中,五氯酚均能有效降解,1d内降解率分别达到86%,17%和46%.结果表明,黄孢原毛平革菌在非木质素降解条件下,依赖胞内酶能有效地降解PCP;在木质素降解条件下依赖胞外木质素降解酶和胞内酶降解五氯酚,降解效率高于非木质素降解条件.  相似文献   

7.
氯代多环芳烃(chlorinated polycyclic aromatic hydrocarbons, Cl-PAHs)是多环芳烃的氯代衍生物,其毒性与母体相当甚至高于母体,在各种环境介质中广泛存在且难以降解,对生态环境和人类健康具有一定的潜在威胁.微生物降解是环境中去除有机物的主要途径之一,本文以白腐真菌的模式菌种-黄孢原毛平革菌(Phanerochaete chrysosporium, Pc)为代表,优化了Pc菌对氯代蒽的降解条件、探究了降解效果以及降解动力学,并分析了可能的降解途径.结果表明,Pc菌对氯代蒽有一定的降解能力.当液体培养基的初始pH值为4.5,Pc菌接种量约为每毫升1×10~5个时,在35℃,120 r·min~(-1)的恒温摇床中培养6 d后,接入浓度为100 mg·L~(-1)的底物能够达到较高的降解效率.在此条件下降解16 d后9-ClAnt和9,10-Cl_2Ant的降解率分别达到了96.45%和92.83%.动力学分析表明,Pc菌降解氯代蒽的过程符合一级动力学方程.分析降解过程,检测到5种降解中间产物,结合生物催化反应的特点推测了氯代蒽可能的降解途径.  相似文献   

8.
生物样品中甲磺基多氯联苯的测定及手性拆分   总被引:1,自引:0,他引:1  
建立了一种生物样品中甲磺基多氯联苯(MeSO2-PCBs)及其手性对映体的分析测定方法.本方法利用索氏抽提对鱼肉组织进行提取,抽提液依次经凝胶渗透色谱柱、氧化铝硅胶复合柱和弗罗里硅土柱进行净化和分离,气相色谱-质谱联用仪进行分析.10个流程空白中,所有目标化合物都低于仪器检出限;17种MeSO2-PCBs在5个空白加标中的平均回收率在77.2%—98.2%之间;样品平行样中目标化合物含量相对标准偏差均小于15%;方法检测限为0.3—20.0 pg.g-1湿重.采用Cyclosil-B手性柱拆分5种MeSO2-PCBs手性对映体,分离度在0.671—2.543之间.  相似文献   

9.
热活化过硫酸盐降解水中的2-氯苯酚   总被引:1,自引:0,他引:1  
利用加入活化K2S2O8产生的硫酸根自由基(SO-4·)降解水中2-氯苯酚(o-chlorophenol),探讨了温度、pH、腐殖酸(HA)、无机离子对2-氯苯酚降解的影响.结果表明,增加溶液中过硫酸盐的浓度或提高溶液反应温度,可促进2-氯苯酚的降解,而且2-氯苯酚的降解符合准一级反应动力学规律,其反应表观活化能为4.32 kJ·mol-1.酸性条件下2-氯苯酚的降解效果明显好于碱性条件.2-氯苯酚的降解受到Cl-、CO2-3和腐殖酸的影响.其中,腐殖酸和CO2-3都对反应有明显的抑制作用.Cl-在酸性和中性条件下也会抑制2-氯苯酚降解,但在碱性条件对反应影响不大.2-氯苯酚在SO-4·的作用下会最终降解为乙酸等小分子有机物并最终矿化,有时会伴随有中间产物二聚物的生成.  相似文献   

10.
以电子加速器为辐照手段,在4-氯酚水溶液中添加TiO2纳米粒子,通过对溶液辐照前后4-氯酚浓度、GC/MS、总有机碳(TOC)、氯离子浓度、辐照前后的紫外-可见光谱过程和溶液pH值的测定分析,研究4-氯酚水溶液在TiO2纳米粒子存在下的辐照降解和矿化特性.结果表明,TiO2纳米粒子的加入对4-氯酚的辐照降解效果没有明显影响,但改变了4-氯酚的降解途径并可以较大地提高4-氯酚的矿化.  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.
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   

19.
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   

20.
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   

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