基于三维荧光光谱特征研究土壤腐殖质氧化还原特性

以国际腐殖质协会腐殖酸和实验室提纯腐殖酸为研究对象,发现被H2还原前后腐殖酸的三维荧光光谱明显不同,但有共同的变化趋势:还原态腐殖酸的三维荧光光谱图的波峰荧光强度均明显低于还原前,说明腐殖酸还原过程有类似π-π*化学键断开的结构变化.对苯醌是腐殖酸氧化还原醌基官能团的代表化合物,将其还原前后与腐殖酸还原前后的荧光光谱对比,发现两组变化趋势一致,这一发现是利用荧光特性量化腐殖质氧化还原官能团的基础.利用铁氰化钾测定腐殖酸的得失电子能力,发现不同土壤提纯的腐殖酸得失电子能力有一定差别:鹰潭土壤腐殖酸和桃源土壤腐殖酸在原态下对三价铁的还原能力都较弱,分别为0.998和0.465 meq.g-1C(原态转移电子数);但还原后得电子数(还原态转移电子数减原态转移电子数)分别为3.384 meq.g-1C(鹰潭土壤腐殖酸)和1.187 meq.g-1C(桃源土壤腐殖酸).鹰潭土壤腐殖酸具有较高的得电子数,与其具有较高荧光峰值这一结果互相支持.结合得失电子能力测定,利用光学分析方法,量化官能团,预测氧化还原反应进程,使三维荧光光谱法测定土壤有机质的氧化还原性在实际应用中具有广阔的前景.     

土壤腐殖质氧化还原电位及其相应电子转移能力分布

本实验以土壤提纯腐殖酸及国际标准腐殖酸(Pahokee Peat Humic Acid,PPHA)为研究对象,测定腐殖酸与3种不同氧化还原Eh的铁矿物(水铁矿(Ferrihydrite)Eh0'=0 m V,赤铁矿(Fe2O3)Eh0'=-287 m V,磁铁矿(Fe3O4)Eh0'=-314 m V及溶解性铁铁氰化钾Eh0'(Ferricyanide=+430 m V)的氧化还原反应,结合Eh-p H计的实验体系,分析腐殖质分子氧化还原官能团的分布规律.磁铁矿同时拥有二价和三价铁离子,具有与腐殖质发生氧化或者还原反应的条件.不同土壤腐殖酸与磁铁矿反应表现的还原/氧化能力不同,这是由于腐殖酸的不同Eh引起,在此基础上测量显示原态下腐殖酸Eh值大约为245 m V,H2还原后,Eh值降低至-620 m V,表明腐殖酸的氧化还原Eh是不同种类和数量的氧化还原官能团Eh叠加值.分析标准腐殖酸在不同氧化还原Eh下的氧化/还原能力显示原态下标准腐殖酸的氧化还原Eh分布比较均匀,还原态腐殖酸在Eh0范围存在易于被氢气还原的官能团,具有显著的还原能力.     

腐殖质氧化还原和电子转移特性研究进展

腐殖质在无氧和有氧条件下都具有一定的氧化还原能力,其氧化还原能力与氧化还原电势有关,而腐殖质的氧化还原电势受芳香度、取代基类型、取代位置等因素影响.除氧化还原能力外,腐殖质还能介导电子转移,其电子转移能力受腐殖质结构和所处环境两大因素影响.水体腐殖酸比土壤和沉积物腐殖酸具有相对较小的电子接受能力(EAC)和较大的提供电子能力(EDC);p H、温度、光照、氧气条件和微生物活动等因素均对腐殖质氧化能力和电子转移能力具有重要影响.腐殖质可以介导重金属和有机污染物的还原降解,不同重金属还原反应效率差异较大,其中Fe(Ⅲ)盐还原速率最高;有机污染物降解速率从大到小为六氯乙烷(HCE)>四氯化碳>三溴甲烷.目前在腐殖质氧化还原特性和电子转移能力研究中还存在诸多不足,需要广大学者做进一步探究.     

纳米零价铁去除垃圾渗滤液中铬(Ⅵ)的性能及机理研究

利用柠檬酸处理后的纳米零价铁(NZVI)对铬(Cr(Ⅵ))的去除进行了研究.NZVI对Cr(Ⅵ)的去除率受Cr(Ⅵ)初始浓度、pH值、反应温度和NZVI的浓度等因素影响,在Cr(Ⅵ)初始浓度为20mg·1-1、pH=5.0、NZVI投加量为1.0g·1-1和20℃条件下,Cr(Ⅵ)去处率达到了100%.腐殖酸(HA)与Cr(Ⅵ)可以形成稳定的HA-Cr螯合物,这种螯合物减少了溶液中有效的Cr(Ⅵ)浓度;同时,HA与NZVI的反应减少了NZVI的有效活性位点,HA的存在对NZVI去除Cr(Ⅵ)有竞争抑制的作用.     

腐殖质氧化还原官能团测定新方法

腐殖质是一种主要由碳、氢、氧、氮等元素构成的具有氧化还原活性的有机质,存在丰富的官能团,其中以酚基和羧基含量最为丰富.腐殖质的氧化还原能力与氧化还原官能团的数目和种类有关.一直以来醌基被认为是腐殖质最重要的氧化还原官能团,对于醌基的测定是研究氧化还原官能团的重点.对于腐殖质氧化还原官能团的研究以化学、电化学和微生物等基本方法为主.本文尝试将这些方法与光谱法(如三维荧光光谱法、红外光谱法、核磁共振光谱法和电子自旋共振波谱法)相结合,不仅可以量化腐殖质氧化还原能力,还能对腐殖质氧化还原官能团具体组成有完整的解释,以便全面了解腐殖质的氧化还原官能团和氧化还原活性.     

高锰酸盐复合剂对三卤甲烷生成形态的影响

研究了高锰酸盐复合剂(PPC)对腐殖酸氯化过程中三卤甲烷生成量及生成形态的影响.结果表明,高锰酸盐复合剂氧化增加了腐殖酸氯化过程中三卤甲烷生成量和水样的卤代活性,增加了腐殖酸氯化的反应速度,在PPC投加量为0.75mg·l~(-1)时,卤代活性由原来的18.1μg·mg~(-1)升至26.6μg·mg~(-1).Br~-的浓度对三卤甲烷生成量及生成形态影响较大,随着Br~-离子浓度增加,三卤甲烷生成量及溴代甲烷的相对含量升高.高锰酸盐复合剂氧化改变了水样加氯消毒时三卤甲烷的形态分布,降低了溴代甲烷在三卤甲烷中的含量.高锰酸盐复合剂与混凝工艺相结合时,可显著降低三卤甲烷的生成量,如高锰酸盐复合剂投量为1mg·l~(-1)时,可使THMs降低到26.3μg·l~(-1).     

水合二氧化锰界面特性及其除污染效能

研究了水合二氧化锰(δMnO2)的界面特性及其吸附性能.考察了δMnO2的比表面积、粒径分布、表面官能团及ζ电位;探讨了δMnO2对水中亚砷酸盐及腐殖酸的吸附去除效能.结果表明:δMnO2的比表面积为117.4m2·g-1,体积平均粒径为0.11μm;δMnO2表面具有丰富的表面羟基(Mn-OH);随着pH值由1.9升高至10.7,δMnO2的ζ电位由 22.7mV降低至53.5mV,其零电荷点在pH3.0附近.δMnO2对亚砷酸盐(As(III))及腐殖酸(HA)均表现出优良的吸附去除效能,其单位δMnO2质量的最大吸附量分别为137μgAs(III)·mg-1δMnO2和1.01mgTOC·mg-1δMnO2.亚砷酸盐与腐殖酸共存时,腐殖酸的存在使得亚砷酸盐的去除率下降10%—28%;而亚砷酸盐对腐殖酸的去除无明显影响.     

腐殖酸对U(Ⅵ)的吸附机理研究

通过静态吸附实验,研究了腐殖酸(HA)对U(Ⅵ)的吸附特征,考查了腐殖酸在不同试验条件对U(Ⅵ)吸附的影响.试验结果表明:吸附过程在1.5 h后达到动态平衡;最佳吸附剂用量为2.0 g·L~(-1);随着U(Ⅵ)的初始浓度增大,腐殖酸对U(Ⅵ)的吸附效果不断降低,最大K_d值在铀的初始浓度为20 mg·L~(-1)时获得;溶液中Ca~(2+)、CO■对U(Ⅵ)的吸附有很强的的抑制作用,影响程度随着离子浓度的增加而增大;腐殖酸对U(Ⅵ)吸附过程符合Langmuir等温吸附方程和准二级动力学模型.     

电化学开关表面活性剂对芘的可逆增溶作用

表面活性剂增强修复技术(SER)是目前行之有效的有机污染土壤修复技术,但SER技术存在表面活性剂与污染物分离困难、易导致二次污染、成本高等问题.基于此,提出采用具有电化学开关特性的表面活性剂(N,N-二甲基二茂铁甲基十二烷基溴化铵,Fc12)代替SER技术中的常规表面活性剂,发展基于开关表面活性剂的可逆增强修复技术(RSER).选取芘作为目标物,研究了Fc12在氧化和还原态对芘的增溶作用以及常见环境因素,如pH和温度对Fc12可逆增溶的影响.结果表明,相对于氧化态Fc12,还原态Fc12在其临界胶束浓度(CMC)以上时对芘表现出显著的增溶作用,且增溶能力随表面活性剂浓度增大而增强.温度对Fc12的增溶作用影响显著,例如,还原态Fc12在浓度为3 mmol·L~(-1)、25℃条件下时,芘的表观溶解度为0.779 mg·L~(-1),当温度增加到40℃时,芘的表观溶解度为0.971 mg·L~(-1),其表观溶解度增加了24.6%;但氧化态条件下,芘的表观溶解度仅增加了6.5%;芘的解吸率(芘在还原和氧化态Fc12的表观溶解度差值与还原态Fc12增溶芘的比值)由63.67%增加到71.27%.pH也显著影响Fc12的增溶,当pH值在6—10范围变化时,还原态Fc12的增溶作用呈现先增加后减小的趋势,且在pH 9附近增溶能力最强,而pH 8时芘的解吸果最好.     

蚯蚓生物处理对剩余污泥腐殖酸特性的影响

以城市污水处理厂产生的剩余污泥为对象,研究蚯蚓(赤子爱胜蚓)生物处理对剩余污泥腐殖酸相关性质的影响.结果表明,在水力负荷4.0 m3·m-2·d-1、有机负荷1.70 kgVSS·m-3·d-1的条件下,蚯蚓生物滤池对于剩余污泥具有良好的减量化效果,VSS平均减量率为55.2%.随着蚯蚓滤池反应器高度的增加,处理后污泥中腐殖酸的C/H值、E4/E6(465 nm与665 nm吸光度的比值)值逐渐降低,紫外光谱205—210 nm处最大吸收峰向近紫外区移动,腐殖酸分子量增大,芳构化明显,缩合程度加强,出泥腐殖化程度提高.荧光淬灭实验分析显示腐殖酸与重金属Cu(Ⅱ)的络合作用明显,蚯蚓滤池处理出泥腐殖酸的络合容量相对进泥有所增加,可溶性铜离子含量降低,可能减少被作物吸收的风险.     

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.     

Representation of the world's biophysical conditions by the global protected area network

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.     

Quantitative composition of the defensive secretion ofBledius species (Coleoptera: Staphylinidae: Oxytelinae) is adapted to naturally occurring predators

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.     

Democracy versus development: New urban debates

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.     

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.     

A framework to measure the wildness of managed large vertebrate populations

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.     

Sexual Predators,Energy Development,and Conservation in Greater Yellowstone

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.     

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.