一种水热稳定的金属有机骨架UiO-66高效捕获水中磷酸盐的性能及机理

本研究采用溶剂热法制备了一种水热性能稳定的金属有机框架UiO-66,并系统考察了其对水中磷酸盐的高效捕获性能.通过表征手段证实,合成的UiO-66具有良好的晶型结构和极大的比表面积,且稳定性良好. UiO-66吸附磷酸盐的过程受pH影响明显,最佳吸附pH值介于5.5—7.0. Langmuir吸附等温模型对吸附过程拟合更好,饱和吸附量可达43.066 mg·g^-1,且由于吸附过程为化学吸附,主要依靠羟基的配体交换作用,因此温度影响不大.与商用阴离子吸附剂D201相比,高浓度背景离子的加入对UiO-66吸附过程无明显影响,表明UiO-66对磷酸盐具有优异的吸附选择性和高效捕获性能.伪二级动力学模型可以很好地描述UiO-66对磷酸盐的吸附过程.经过6次循环吸附-脱附,UiO-66仍能有效去除水中磷酸盐,并可通过DMF溶液超声解吸实现有效再生.结果表明,UiO-66作为一种新兴的吸附剂有望实现磷酸盐在水中的深度高效去除.     

UiO-66(Zr)@多孔陶瓷复合材料的制备及对络合态重金属EDTA-Cu(Ⅱ)的去除

本文采用多孔陶瓷作为基体制备了锆基金属有机骨架UiO-66@多孔陶瓷复合材料.通过扫描电子显微镜(SEM)、粉末X射线衍射(PXRD)、氮气吸附和傅里叶变换红外光谱(FTIR)等表征手段对比了氢氧化钠脱硅和乙二胺表面改性等基体活化方式对UiO-66(Zr)在多孔陶瓷表面负载情况的影响.结果表明,经过乙二胺表面改性的多孔陶瓷对UiO-66(Zr)的负载更均匀,负载效果更好.以EDTA-Cu(Ⅱ)为考察对象,研究了UiO-66(Zr)@乙二胺表面改性多孔陶瓷复合材料对络合态重金属的净化效能.结果表明,UiO-66(Zr)@多孔陶瓷复合材料在较宽的酸碱条件下(pH=3—9)对络合态重金属EDTA-Cu(Ⅱ)均表现出良好的吸附性能,饱和吸附量为1.17 mg·g~(-1),并可通过NaOH解吸再生,从而实现材料的重复利用.     

磷酸盐在土壤中吸附与解吸研究进展

就国内外有关磷酸盐在土壤中的吸附与解吸的研究进行了简要的综述，重点是关于磷酸盐的吸附研究包括磷酸盐在土壤中吸附的数学模拟、土壤吸附磷酸盐的机制、影响磷酸盐吸附的土壤组分、磷酸盐在土壤中解吸及其与吸附的关系以及有机无机土壤改良剂对磷酸盐吸附的影响，并提出了有待进一步研究的问题。     

锆负载量对锆镁改性膨润土吸附水中磷酸盐的影响

制备了锆氧化物(ZrO_2)含量分别为2.98%、7.81%、13.73%和33.70%的4种锆镁改性膨润土,并考察了锆负载量对锆镁改性膨润土吸附水中磷酸盐的影响.结果表明,较高的吸附剂投加量有利于水中磷酸盐被锆镁改性膨润土所吸附去除.锆镁改性膨润土吸附水中磷酸盐的动力学过程符合准二级动力学模型.锆镁改性膨润土对水中磷酸盐的吸附等温行为可以采用Langmuir、Freundlich和Dubinin-Redushckevich (D-R)等温吸附模型进行描述.增加溶液pH值不会导致锆镁改性膨润土对水中磷酸盐吸附能力的下降.锆镁改性膨润土对水中磷酸盐的吸附能力随其锆含量的增加而增加.但是,从总体上,锆镁改性膨润土中单位质量ZrO_2对水中磷酸盐的最大吸附量则随其锆含量的增加而降低.研究结果说明,锆镁改性膨润土适合作为一种吸附剂去除水中的磷酸盐,较高的锆负载量有利于增强锆镁改性膨润土吸附水中磷酸盐的能力,而较低的锆负载量则有利于提高锆镁改性膨润土中单位质量ZrO_2对水中磷酸盐的吸附能力.     

模板法合成介孔硅酸钙及其对重金属离子的吸附性能

以硝酸钙和硅酸钠为原料,采用模板法制备了介孔硅酸钙.探讨了不同模板剂(十二烷基磺酸钠、十六烷基三甲溴化铵、P123和十六烷基三甲溴化铵-四甲基氢氧化胺)对介孔硅酸钙孔径和表面形貌的影响,通过X射线衍射(XRD)、扫描电镜(SEM)、BET表面分析和红外光谱(FT-IR)等对其结构进行了表征,考察其对含Pb~(2+)和Cu~(2+)模拟废水的吸附性能和解吸再生性能,并与活性炭的吸附性能进行比较.结果表明,采用十六烷基三甲溴化铵模板剂为模板合成的硅酸钙具有介孔结构,为狭缝孔,孔径主要介于4—50 nm之间,比表面积达158.13 m~2·g~(-1);在298 K下,对Pb~(2+)和Cu~(2+)的吸附容量分别为1.833 mmol·g-1和6.557 mmol·g-1,远比在相同吸附条件下活性炭的吸附容量高.介孔硅酸钙吸附重金属离子为放热反应,主要是表面羟基与重金属离子间配位化学作用.经过5次洗脱再生,对Pb~(2+)的平衡吸附量和吸附率仅分别降低了0.102 mmol·g-1和4.2%,表明其具有优良的吸附/再生性能,有望成为优良的重金属离子吸附材料.     

不同价态Ce-MOF衍生材料的吸附除磷性能及机理比较

通过在N_2气氛中的热处理,从Ce-MOF中衍生出一系列多级的微/纳米铈基复合材料.Ce-MOF在空气中完全分解形成二氧化铈,价态由三价转变为四价.而在N_2中较低温度(400℃或500℃)下煅烧会形成稳定的部分热解的Ce-MOF(N),具有较高的Ce(Ⅲ)含量.与完全分解的产物相比,虽然完全分解的产物具有较高的比表面积,但是部分分解的样品对磷酸盐的吸附效果是完全分解产物的2—4倍.这种差异证明铈基材料的不同价态对除磷性能有显著影响,相比于四价铈离子,三价铈在与磷酸盐结合中起主要作用.与Ce-MOF(A)相比,Ce-MOF(N)是一种高Ce(Ⅲ)含量的铈基纳米材料,其饱和吸附容量为187.2 mg·g~(-1),吸附速度快,pH适用范围极广,为pH 2—12,并且在竞争阴离子存在下也对磷酸盐具有很高的选择性.与此同时,相比于常用的金属盐吸附剂,Ce-MOF(N)在碱性条件下具有明显增强的磷酸盐吸附能力.这是因为表面Ce(Ⅲ)的部分水解带来了更多的羟基,增加了磷酸根离子交换的活性位点.此外,通过分析FTIR、XPS、XRD和Zeta电位,Ce(Ⅲ)样品对磷酸根的吸附机理主要为静电吸引,离子交换和表面沉积,而对于完全分解的铈基材料Ce-MOF(A)静电吸引是主要机理.     

生物炭对水溶液中肉桂酸的吸附机制研究

研究了不同温度(300—900℃)制备的杉木生物炭对水相中肉桂酸的吸附.所有温度下,生物炭对肉桂酸的吸附等温线都呈非线性关系,并以表面吸附为主.高比表面积是800—900℃生物炭吸附量较大的主要因素.为探明生物炭的化学组成对肉桂酸吸附的影响,将吸附量进行了比表面积标化分析,结果表明,300℃生物炭的高含量异质性原子和800—900℃生物炭表面高含量灰分占用了生物炭的吸附点位,导致它们对肉桂酸的标化吸附量明显小于400—700℃生物炭.此外,低pH抑制了600℃生物炭-水溶液中肉桂酸的解离,减少了生物炭表面—OH与解离肉桂酸之间以氢键结合的吸附量,导致400—700℃生物炭中600℃生物炭的标化吸附量最低.研究明确了生物炭的不同性质对肉桂酸吸附的影响及机制,为选择合适的生物炭作为土壤添加剂来降低肉桂酸化感作用提供了科学依据.     

层状双氢氧化物负载生物炭对磷酸盐的吸附性能研究进展

层状双氢氧化物负载生物炭（layered double hydroxides functionalized biochar, LDHs@BC）对水体中磷酸盐具有优异的吸附性能,近年来受到了广泛关注.本文详细介绍了LDHs@BC的制备方法以及制备条件对其理化性质的影响,探讨了LDHs@BC对水体中磷酸盐的吸附性能及机制,并且阐述了生物炭和层状双氢氧化物对磷酸盐吸附的协同作用及其机制,以期通过优化制备工艺参数定向调控LDHs@BC性能,显著提升LDHs@BC对磷酸盐的吸附效率.本文展望了LDHs@BC的应用前景,以期进一步推动LDHs@BC在水体修复中的应用和推广.     

纳米氧化铝/氧化锰-硅藻土复合物对磷酸根阴离子的吸附

为改善纳米金属氧化物颗粒在硅藻土表面的负载特性,在保留硅藻土大孔结构的同时提高纳米颗粒的分散性,本研究通过原位合成/负载法,制备出一种具有多级孔结构的纳米氧化铝/氧化锰-硅藻土复合物(Dt-Al-Mn).采用X射线衍射、扫描电子显微镜、透射电子显微镜和氮气吸脱附等温线分析等手段对其进行物相、形貌及孔结构等表征,并通过吸附实验来探究其对磷酸根离子的吸附特性.结果表明,硅藻土表面均匀负载了铝-锰双金属氧化物颗粒薄膜,该颗粒薄膜以无定形存在.Dt-Al-Mn不仅保留硅藻土的大孔结构,并且形成了大量的微孔和介孔结构,其比表面积和孔容为352.4 m~2·g~(-1)和0.535 cm~3·g~(-1),远高于硅藻土(Dt)和硅藻土负载氧化铝材料(DA).Dt-Al-Mn对磷酸根的最大吸附量为67.9 mg P·g~(-1),其吸附等温线较好地符合于Langmuir模型.综上所述,Dt-Al-Mn有望成为一种具有应用前景的富营养化水体修复材料.     

HDTMAB改性粉煤灰对水体中磷的吸附特性

制备了十六烷基三甲基溴化铵(HDTMAB)改性粉煤灰,研究了该改性粉煤灰对水体中磷的吸附特性,结果表明:①当HDTMAB负载量为10%时,改性粉煤灰吸附磷酸盐的效果最佳;②改性粉煤灰对磷酸盐的吸附速度很快,20min可达吸附平衡;③改性粉煤灰对磷酸盐的吸附行为能较好地符合Langmuir等温吸附模型和Freundlich等温吸附模型,但在Freundlich模式下表现为两个线性区;④pH对改性粉煤灰吸附磷酸盐的性能有显著影响,随着pH的升高对磷酸盐的吸附能力逐渐增加。     

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.     

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.     

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.     

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.     

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.     

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.