焙烧层状氢氧化镁铝对水溶液中亚硝酸盐的吸附脱除

通过静态吸附实验,研究了焙烧层状氢氧化镁铝(Mg-Al CLDH)对水溶液中NO2-的吸附脱除性能,并用粉末X射线衍射对Mg-Al CLDH吸附前后的结构进行了表征.结果表明,Mg-Al CLDH可有效脱除水溶液中的业硝酸盐(NO2-),对NO2-的脱除是通过"结构记忆"效应实现的,当NO-2初始浓度高达15mgN·l-1时,经0.10g Mg-Al CLDH处理后,溶液中残余浓度小于lmgN·l-1.在293-323 K温度范围内,NO2-在Mg-Al CLDH上的饱和吸附量为17.24-29.94 mgN·g-1,吸附量明显高于其它吸附剂;吸附量随温度的升高而增大,表现为吸热吸附;吸附过程符合Langmuir线性等温方程式.吸附速率随温度的升高而迅速增大,伪二级动力学方程可用来描述其吸附动力学过程;吸附Ea为109.94 kJ·mol-1,Mg-Al CLDH对NO2-的吸附主要是化学吸附,Mg-Al CLDH对NO2-的脱除率基本不受溶液初始pH值的影响,吸附量随离子强度的增大而减小,正交实验结果显示溶液初始浓度是影响吸附量的最主要因素.     

层状氢氧化镁铝对染料酸性橙Ⅱ的脱色性能

分别用层状氢氧化镁铝(LDHs)和焙烧层状氢氧化镁铝(CLDH)作为吸附剂,吸附脱除水溶液中染料酸性橙Ⅱ,考察了Mg/Al物质的量之比、吸附剂的投加量、脱色时间、初始pH值等因素对脱色率的影响.结果表明,以Mg/Al物质的量之比为3制得的层状氢氧化镁铝对酸性橙Ⅱ溶液的脱色效果最好;室温下,3.0 g·L-1LDHs和1...     

焙烧态镁铝铁类水滑石对磷酸根离子的吸附

用共沉淀法制备了镁铝铁三元类水滑石(LDH),在不同温度下对其焙烧4 h,得到焙烧态类水滑石(CLDH).采用XRD、FT-IR对材料进行分析,研究其对水中磷酸根的吸附性能和机制.结果表明,铁的掺杂量过大会破坏类水滑石的层状结构,且随着铁含量的增大,类水滑石对磷酸根的吸附量逐渐减小.当Mg/Al/Fe物质的量之比为2∶0.9∶0.1,在300℃下焙烧时,CLDH吸附磷酸根能力最好,吸附容量约27.03 mg.g-1,为焙烧前的1.32倍.在pH 4—11范围内,在竞争离子存在的条件下,CLDH-0.1-300都能表现出较好的吸附性能,对实际废水中的磷也有较强的吸附能力.CLDH-0.1-300对磷酸根的吸附符合二级反应动力学模型,吸附等温线符合Langmuir等温式.用浓度为0.5 mol.L-1的NaOH溶液可以对吸附磷酸根后的类水滑石CLDH-0.1-300实现解吸再生,"吸附-再生-再吸附"循环3次后吸附容量仍接近初始值的60%.     

镧掺杂纳米材料合成及其高氟选择性吸附特性

采用共沉淀法制备了镧渗杂的纳米镁铝层状双氢氧化物材料(LDHs),获得了一类对氟具有选择性的新型吸附材料.实验表征了LDH、其焙烧产物(LDOs)以及吸附氟后的材料(F-LDHs)的微观形态、体相组成等性质的变化,通过批处理试验和吸附柱试验对其工艺特性及影响因素进行了深入分析.实验结果表明,材料经600℃焙烧10min,在含200mg·l~(-1)SO_4~(2-),氟浓度为10mg·l~(-1)的配水中投加0.1g LDOs吸附240min,最高除氟率可达93.53%;在含200mg·l~(-1)SO_4~(2-)的氟溶液中,镁铝铜LDOs吸附氟的容量高于镁铝LDOs;吸附柱实验中,14h时出水氟含量小于国家标准(1 mg·l~(-1));共存阴离子对材料的除氟干扰强度排序为:Co_3~(2-)>PO_4~(3-)>NO_3~->Cl~-.材料吸附氟后可用0.5mg·l~(-1)的Na_2CO_3洗脱,并经600℃焙烧10min再生,再生4次后选择性除氟效果稳定.     

染料化合物在改性介孔TiO_2上的吸附

以聚乙烯醇-碘复合物修饰的介孔TiO2纳米材料为吸附剂,研究了介孔TiO2对亚甲基蓝、甲基橙、茜素红和二甲酚橙染料化合物的吸附作用.考察了4种染料初始浓度和初始pH值对吸附的影响.实验结果表明,染料化合物的结构和性质影响介孔TiO2对它们的吸附平衡时间和吸附量.二甲酚橙、甲基橙、茜素红和亚甲基蓝有最佳吸附去除率的初始pH值分别为2.0、2.0、3.0和8.0;平衡吸附时间分别为100 min、10 min、100 min和60 min.介孔TiO2对亚甲基蓝、茜素红、二甲酚橙的饱和吸附量分别为80.32 mg·g-1、78.72 mg·g-1、71.64 mg·g-1,甲基橙的饱和吸附量超过200 mg·g-1.改性介孔TiO2对亚甲基蓝、茜素红、二甲酚橙的吸附符合二级动力学方程.     

铝镁氢氧化物溶胶吸附脱色性能的研究

对染料在具有永久正电荷的铝镁氢氧化物上的吸附,考察了铝镁比、染料类型、pH值等因素对吸附效果的影响,并进行了动力学、热力学研究结果表明,铝镁氢氧化物溶胶具有良好的脱色效果,铝镁比为1∶3的溶胶处理效果最佳;溶胶对大多数阴离子型染料的脱色率明显大于其它类型;染料的吸附量随pH值的增大而减小;溶胶对实验的各种阴离子型染料的饱和吸附量在961—3319mg·g-1之间;吸附量随温度升高而减小,说明吸附是放热过程     

水热合成silicalite-2分子筛及对对硝基苯酚的吸附与脱附性能

以硅溶胶为硅源、四丁基氢氧化铵(TBAOH)为模板剂,按1SiO2∶0.35TBAOH∶25H2O的物质的量之比,170℃下水热晶化48 h合成silicalite-2分子筛,并用XRD、SEM等方法对其进行了表征.考察了pH、温度、投加量、NaCl浓度对模拟的对硝基苯酚废水吸附效果的影响.结果表明,在对硝基苯酚废水浓度为20 mg·L-1,pH=4,投加量为0.3g·L-1,温度25℃,NaCl浓度580 mg·L-1时,吸附量为98.4 mg·g-1.采用1.44%氢氧化钠脱附剂对吸附饱和的silicalite-2分子筛进行脱附110 min,脱附率达到85%以上.     

复合铁铝氢氧化物对As(Ⅴ)的吸附作用

从吸附剂的组成、结构、表面性质、溶液的酸度及砷的存在形式等方面探讨了复合铁铝氢氧化物(Fe5Al2(OH)21.nH2O)对溶液中As(Ⅴ)的吸附.结果表明,该吸附剂具有微晶体的结构特征,孔径小,比表面积大,等电位点pH值为8.3;在pH为4-8的溶液中,对As(Ⅴ)的吸附能力很强,饱和吸附容量Qm分别为:0.7901(pH5),0.5981(pH7)和0.3033 (pH9)mol·kg-1, 常见共存离子不影响砷的吸附.Langmiur方程能很好地描述实验的吸附等温线.吸附态 As(Ⅴ)的解吸量随解吸剂pH值的升高而增大.     

表面接枝聚乙烯亚胺硅胶微粒对铬酸根的吸附特性

通过γ-氯丙基三甲氧基硅烷的偶联,将聚乙烯亚胺(PEI)偶合接枝在硅胶微粒表面,制得对铬酸根有强吸附作用的复合型吸附材料PEI/SiO2,并对其化学结构进行了表征; 采用静态法研究了PEI/SiO2对铬酸根的吸附性能及脱附性能.结果表明,凭借强烈的静电相互作用, 硅胶表面的聚胺大分子PEI对铬酸根阴离子可产生很强的吸附作用,饱和吸附量可达0.07 g·g-1(pH=6);等温吸附满足Langmuir吸附等温方程; 介质的pH值对吸附作用有很大的影响, pH值愈小,吸附容量愈大;升高温度吸附量减小,表明静电相互作用导致的吸附作用为一放热过程.以NaOH水溶液为洗脱液,吸附在PEI/SiO2表面的铬酸根阴离子很容易被解吸脱附,便于PEI/SiO2的重复使用.     

硅镁胶MgO·6SiO_2的制备及其对亚甲基蓝的吸附

以氯化镁和水玻璃为原料,采用水热法制备了氧化镁含量低于10%的新型硅镁胶MgO·6SiO2,讨论了体系pH值、水热时间和温度等因素对产物硅镁物质的量之比的影响,通过比表面积分析、电位滴定法对样品进行了表征,用亚甲基蓝溶液评价其吸附性能.结果表明,MgO·6SiO2的最佳制备条件为:调节pH值到9.5左右、水热12 h、水热温度110℃,pH为控制产物硅镁物质的量之比的决定性因素;硅镁胶MgO·6SiO2是多孔材料,比表面积为285 m2·g-1,表面零电荷点pHzpc为10.4;25℃时,对亚甲基蓝的最大吸附量可达151.52 mg·g-1,吸附过程符合Langmuir吸附模型.     

Achieving Open Access to Conservation Science

Conservation science is a crisis discipline in which the results of scientific enquiry must be made available quickly to those implementing management. We assessed the extent to which scientific research published since the year 2000 in 20 conservation science journals is publicly available. Of the 19,207 papers published, 1,667 (8.68%) are freely downloadable from an official repository. Moreover, only 938 papers (4.88%) meet the standard definition of open access in which material can be freely reused providing attribution to the authors is given. This compares poorly with a comparable set of 20 evolutionary biology journals, where 31.93% of papers are freely downloadable and 7.49% are open access. Seventeen of the 20 conservation journals offer an open access option, but fewer than 5% of the papers are available through open access. The cost of accessing the full body of conservation science runs into tens of thousands of dollars per year for institutional subscribers, and many conservation practitioners cannot access pay‐per‐view science through their workplace. However, important initiatives such as Research4Life are making science available to organizations in developing countries. We urge authors of conservation science to pay for open access on a per‐article basis or to choose publication in open access journals, taking care to ensure the license allows reuse for any purpose providing attribution is given. Currently, it would cost $51 million to make all conservation science published since 2000 freely available by paying the open access fees currently levied to authors. Publishers of conservation journals might consider more cost effective models for open access and conservation‐oriented organizations running journals could consider a broader range of options for open access to nonmembers such as sponsorship of open access via membership fees. Obtención de Acceso Abierto a la Ciencia de la Conservación     

Some polyphagous Homoptera gain protection from their natural enemies by feeding on the toxic plantsSpartium junceum andErythrina corallodendrum (Leguminosae)

Summary Interactions were studied among alkaloid-containing legumes (Erythrina corallodendrum andSpartium junceum) and non-toxic plants (Citrus sinensis, Cucurbita moschata andEuphorbia tirucalli), several polyphagous homopterans,Aphis craccivora (Aphididae),Icerya purchasi, I. aegyptiaca (Margarodidae),Lepidosaphes ulmi (Diaspididae) andPlanococcus citri (Pseudococcidae), and some major natural enemies of these homopterans. Significant reductions in survival due to negative effects of alkaloid containing as compared with non-alkaloidal plants were recorded for the predatorsRodolia cardinalis andChilocorus bipustulatus, but not forCryptolaemus montrouzieri (Coleoptera: Coccinellidae),Chrysoperla carnea (Neuroptera: Chrysopidae) andSympherobius sanctus (Neuroptera: Sympherobiidae). The development time of the larvae or pupae ofR. cardinalis, C. carnea andS. sanctus was longer on the toxic plants than on the non-toxic ones. The percentage of parasitism ofA. craccivora collected from the non-alkaloidal plantsVicia palaestina andMelilotus albus was much higher than that onS. junceum. The parasitoid complexes ofA. craccivora differed between both plant groups. The nutritive value of honeydew ofI. purchasi andA. craccivora, as expressed by the life span ofEncyrtus infelix (Hymenoptera: Encyrtidae) adults, was also investigated. Life spans were significantly longer when the wasps fed on honeydew produced on non-alkaloidal plants (C. sinensis andPittosporum tobira) than on alkaloid containing plants whenI. purchasi — but notA. craccivora — was the producer. It is suggested that the chemical defense ofE. corallodendrum andS. junceum is exploited by polyphagous phytophages to reduce predation. In nature, population growth and density of four of the investigated homopterans are conspicuously high when they developed on the alkaloid containing plant species, and very low on non-alkaloid plants. The efficiency of their natural enemies may be reduced by sequestration of alkaloids (or other toxic plant compounds) or their transfer into excreted honeydew. Therefore it is assumed that a generalist phytophagous homopteran may be protected from its natural enemies, although at different rates of efficiency, if it can safely sequester the host allelochemical when it develops on toxic species within its host range.     

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.     

Sequestration of cucurbitacin analogs by New and Old World chrysomelid leaf beetles in the tribe Luperini

Summary Two South American polyphagous leaf beetles,Diabrotica speciosa andCerotoma arcuata, selectively accumulated the bitter tasting compound 23,24-dihydrocucurbitacin D in their body after ingesting root tissues of cucurbit plants. Similarly, three Asian Cucurbitaceae-feeding specialists in the genusAulacophora were found to sequester the same compound. Cucurbitacin analogs were shown to deter feeding by a bird predator, indicating an allomonal role for these compounds in cucurbitacin-associated chrysomelid leaf beetles both of New and Old Worlds. The strong affinity to cucurbitacins, selective sequestration of the analogs and consequent protection from predators suggested an ecological adaptation mechanism developed in common among these two geographically isolated subtribes in the Luperini.     

Effects of Controlled Fire and Livestock Grazing on Bird Communities in East African Savannas

Abstract: In East Africa fire and grazing by wild and domestic ungulates maintain savannas, and pastoralists historically set fires and herded livestock through the use of temporary corrals called bomas. In recent decades traditional pastoral practices have declined, and this may be affecting biodiversity. We investigated the effects of prescribed fires and bomas on savanna bird communities in East Africa during the first and second dry seasons of the year (respectively before and after the rains that mark the onset of breeding for most birds). We compared abundance, richness, and community composition on 9‐ha burned plots, recently abandoned bomas, and control plots in the undisturbed matrix habitat over a 3‐year period. Generally, recently burned areas and abandoned bomas attracted greater densities of birds and had different community assemblages than the surrounding matrix. The effects of disturbances were influenced by interactions between primary productivity, represented by the normalized difference vegetation index, and time. Bird densities were highest and a greater proportion of species was observed on burned plots in the months following the fires. Drought conditions equalized bird densities across treatments within 1 year, and individuals from a greater proportion of species were more commonly observed on abandoned bomas. Yearly fluctuations in abundance were less pronounced on bomas than on burns, which indicate that although fire may benefit birds in the short term, bomas may have a more‐lasting positive effect and provide resources during droughts. Several Palearctic migrants were attracted to burned plots regardless of rainfall, which indicates continued fire suppression may threaten their already‐declining populations. Most notably, the paucity of birds observed on the controls suggests that the current structure of the matrix developed as a result of fire suppression. Traditional pastoralism appears critical to the maintenance of avian diversity in these savannas.     

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.     

What Every Conservation Biologist Should Know about Economic Theory

Abstract: The last century has seen the ascendance of a core economic model, which we will refer to as Walrasian economics. This model is driven by the psychological assumptions that humans act only in a self‐referential and narrowly rational way and that production can be described as a self‐contained circular flow between firms and households. These assumptions have critical implications for the way economics is used to inform conservation biology. Yet the Walrasian model is inconsistent with a large body of empirical evidence about actual human behavior, and it violates a number of basic physical laws. Research in behavioral science and neuroscience shows that humans are uniquely social animals and not self‐centered rational economic beings. Economic production is subject to physical laws including the laws of thermodynamics and mass balance. In addition, some contemporary economic theory, spurred by exciting new research in human behavior and a wealth of data about the negative global impact of the human economy on natural systems, is moving toward a world view that places consumption and production squarely in its behavioral and biophysical context. We argue that abandoning the straightjacket of the Walrasian core is essential to further progress in understanding the complex, coupled interactions between the human economy and the natural world. We call for a new framework for economic theory and policy that is consistent with observed human behavior, recognizes the complex and frequently irreversible interaction between human and natural systems, and directly confronts the cumulative negative effects of the human economy on the Earth's life support systems. Biophysical economics and ecological economics are two emerging economic frameworks in this movement.     

Effects of Coffee Management on Deforestation Rates and Forest Integrity

Knowledge about how forest margins are utilized can be crucial for a general understanding of changes in forest cover, forest structure, and biodiversity across landscapes. We studied forest‐agriculture transitions in southwestern Ethiopia and hypothesized that the presence of coffee (Coffea arabica)decreases deforestation rates because of coffee's importance to local economies and its widespread occurrence in forests and forest margins. Using satellite images and elevation data, we compared changes in forest cover over 37 years (1973–2010) across elevations in 2 forest‐agriculture mosaic landscapes (1100 km² around Bonga and 3000 km² in Goma‐Gera). In the field in the Bonga area, we determined coffee cover and forest structure in 40 forest margins that differed in time since deforestation. Both the absolute and relative deforestation rates were lower at coffee‐growing elevations compared with at higher elevations (?10/20% vs. ?40/50% comparing relative rates at 1800 m asl and 2300–2500 m asl, respectively). Within the coffee‐growing elevation, the proportion of sites with high coffee cover (>20%) was significantly higher in stable margins (42% of sites that had been in the same location for the entire period) than in recently changed margins (0% of sites where expansion of annual crops had changed the margin). Disturbance level and forest structure did not differ between sites with 30% or 3% coffee. However, a growing body of literature on gradients of coffee management in Ethiopia reports coffee's negative effects on abundances of forest‐specialist species. Even if the presence of coffee slows down the conversion of forest to annual‐crop agriculture, there is a risk that an intensification of coffee management will still threaten forest biodiversity, including the genetic diversity of wild coffee. Conservation policy for Ethiopian forests thus needs to develop strategies that acknowledge that forests without coffee production may have higher deforestation risks than forests with coffee production and that forests with coffee production often have lower biodiversity value. Efectos de la Administración Cafetalera sobre las Tasas de Deforestación y la Integridad de los Bosques     

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.