生物炭及其复合材料在土壤污染修复中的应用研究进展

人类活动产生的重金属与农药残留的有机污染物在土壤中的积累致使土壤遭受严重污染,引发了一系列生态问题。生物炭及其复合材料因其独特的表面结构使其可通过物理或化学等作用吸附土壤中的污染物,限制其在生态系统中的迁移与传递过程,进而改善土壤理化性质,因此生物炭在土壤污染治理方面的应用研究越来越多地引起关注,但多数研究局限于实验室水平。文章对近年来生物炭及其复合材料在自然土壤环境中的应用的相关研究进行了整理,从重金属与有机污染物两个方面切入,阐述了不同生物炭材料在污染土壤中对两类污染物的作用机理;介绍了生物炭的改性和复合方法及其应用优势,同时对生物炭材料在污染土壤修复中的研究重点进行了展望。复合材料可以显著增强生物炭对污染物的吸附性能。从吸附机理上看,生物炭及其复合材料对重金属污染多以静电作用、离子交换作用、表面官能团作用为主;对有机污染物则主要以分配作用、吸附作用、孔隙填充为主,但在实际应用过程中,这些机理往往共同发挥作用,只是贡献程度不同。另外,生物炭及其复合材料也可通过提高土壤质量间接增强土壤对污染物的抗性等。虽然纳米材料能够增强生物炭的性能,但其对土壤中微生物的毒性机理尚不完全清楚。综上所述,生物炭及其复合材料在自然土壤环境中的应用能显著降低污染物的毒性,但新型生物炭复合材料的作用机理有待进一步的研究和论证。     

生物炭对土壤中微生物群落结构及其生物地球化学功能的影响

生物炭是由生物质在完全或部分缺氧的情况下经热解炭化产生的一类高度芳香化难熔性固态物质,具有改善土壤理化性质、调控营养元素循环、防治重金属、多环芳烃等污染物迁移转化等功能,因此,在土壤改良与修复领域具有较好的应用前景。但是,生物炭的施用将对土壤中的微生物群落结构组成带来影响,从而改变整个生态系统的物质循环过程。本文综述了近年来国内外有关生物炭对土壤微生物分布影响的研究进展,探讨了生物炭对土壤微生物生长代谢的作用机制,阐述了生物炭对于微生物主导的土壤生物地球化学过程产生的影响作用。相关研究发现,土壤总微生物生物量在生物炭施用后或增加,或不变,或呈现下降趋势;不同种类微生物对于生物炭的响应非常复杂,从而呈现出各异的土壤微生物群落结构组成。生物炭对微生物生长代谢的影响源于改变p H环境、影响水分分布、调节养分循环等多种机制的协同作用,而生物炭在对环境物质的吸附以及对微生物的直接吸附方面扮演着重要角色。同时,生物炭对于土壤微生物群落结构组成的影响还会随着时间的推移而发生变化。生物炭对土壤中微生物分布的改变还会进一步影响微生物的生物地球化学功能,对温室气体排放、碳氮循环和有机污染物降解等生物地球化学过程产生重要影响。因此,有待开展更多关于生物炭对于土壤微生物分布及其生态功能的影响的深入研究,以期更全面地评价生物炭对土壤环境质量的影响作用,为生物炭的实际应用提供依据。     

生物炭对农业面源污染氮、磷流失的影响研究进展

综述了近年来国内外应用生物炭削减农田氮、磷养分流失的研究进展,从生物炭的作用机制和对土壤环境效应的影响2个方面出发,重点阐述了生物炭对土壤中氮、磷养分的吸附与转化,生物炭的作物效应以及生物炭对土壤淋溶过程的影响。生物炭不仅能够改善土壤环境,提高土壤氮、磷养分的有效性,促进作物的吸收和生长,而且由于其特殊的结构和理化性质,可以吸附土壤中未被作物利用的水分和养分,延缓养分释放,减弱其在土壤中的迁移转化能力,最终实现减少土壤氮、磷养分流失的目的。最后,着眼于当前相关研究的薄弱之处对今后研究重点和方向进行展望,供相关研究者参考。     

生物炭对土壤微生物的影响研究进展

生物炭是有机材料在厌氧条件下热解而成的产物。近年来,生物炭因在碳固定、土壤改良和作物产量提高等方面具有较大的应用潜力而引起国内外学者的广泛关注。作为一类新型的土壤改良剂,它能提高土壤有机碳含量及阳离子交换量(CEC),改善土壤保肥持水性能,有益于土壤微生物活动,同时还可吸附抑制对土壤微生物生长有毒的化感物质,为土壤微生物提供有利的栖息场所。但生物炭的效应与生物炭的特性、用量、土壤类型及肥力有关。笔者从生物炭对土壤微生物的影响及其作用机制出发,概述了不同生物质材料及热解温度对生物炭理化性质的影响及生物炭对土壤微生物丰度、群落结构和活性影响的研究进展。未来应重点从生物炭的特性、生物炭与微生物交互作用及生物炭的环境修复等方面深入研究,客观评价生物炭对土壤微生物的作用。     

土壤中微塑料的来源与其生态毒理效应研究进展

微塑料作为一种新兴的污染物，近年来由于其对环境的污染逐渐加剧而受到了学者的广泛关注.当前对微塑料的研究多集中于水环境中，而对土壤环境中微塑料的研究相对较少，由于其难以降解，会长期存在于土壤环境中，进而对土壤理化性质和物质循环、动植物以及微生物等造成严重的毒理效应.本文评述了土壤中微塑料的来源与其生态毒理效应，土壤中微塑料的来源主要有农用塑料薄膜的广泛使用、农业灌溉用水、污泥堆肥及施用、垃圾填埋和大气沉降.进而阐述了微塑料由于自身的颗粒效应、所含添加剂以及吸附土壤中其它污染物产生的复合污染，对土壤生态环境造成显著的毒理效应.微塑料进入土壤环境后会影响土壤的理化性质和物质循环，使土壤结构发生改变、土壤透气性和酶活性降低.还会影响土壤动植物生长发育以及微生物群落结构，使土壤动物产生肠道损伤、免疫反应、神经毒性、繁殖率降低，死亡率增加以及肠道内微生物群落结构改变等；影响植物种子发芽率、含水量、生殖过程、光合色素、酶活性以及植物生物量和外在特征等；改变微生物原有的群落结构，抑制微生物活性、降低微生物多样性，并使其繁殖发育受到影响.最后，在总结了国内外对微塑料生态毒理效应研究的基础上，对今后的研究...     

生物修复中有机污染物的生物可利用性

论述了土壤和地下水生物修复中有机污染物的生物可利用性。污染物的可利用性对生物修复速率和生物强化效率有重要影响。生物可利用性是指土壤和地下水中的微生物或其胞外酶对有机污染物的可接近性，它受土壤理化性质、污染物和微生物性质、污染接触时问等许多因素的综合影响。污染物的介质吸附、多相分配、老化和形成非水相基质，以及土壤微生物的吸附、过滤和沉降作用降低了污染物的可利用性。促进土壤中污染物和微生物的解吸附，增强非水相基质的溶解，加速土壤污染物与微生物之间的质量传递，可以增强污染物的可利用性和生物降解的速率。施用表面活性剂和电动力学方法可有效地增强污染物的生物可利用性。     

生物炭尺寸效应对土壤污染修复的差异调控

生物炭是一种富含碳的材料,可以由各种有机废物原料制备,例如木材废料、农业废物和城市污水污泥.生物炭因其碳含量高、阳离子交换容量高、比表面积大、结构稳定等特性而受到越来越多的关注.本文系统地分析和总结了生物炭的原料来源与性质及在污染土壤修复方面的应用.基于生物炭的理化性质差异,重点阐明了生物炭尺寸效应对土壤污染物的作用机理,并对其修复土壤污染物和改善土壤质量进行了深入讨论.此外,在将生物炭实际应用于环境修复时,应更加关注生物炭老化后性能的改变.综上所述,生物炭在环境修复中具有广阔的应用前景,尺寸效应差异调控土壤污染物的作用机理需要更深一步的研究.     

微塑料对农田土壤理化性质、土壤微生物群落结构与功能的影响

微塑料作为一种新污染物普遍存在于各类环境介质中,土壤环境中的微塑料污染已受到全球的广泛关注。该研究围绕农田土壤中微塑料污染这一主题,在总结分析国内外最新研究进展的基础上,综述了微塑料对农田土壤理化性质、土壤微生物生物量以及微生物群落结构与功能的影响。通过农业活动等途径进入农田土壤的微塑料会在非生物和生物作用下发生风化和降解,并对土壤理化性质、养分循环和污染物相互作用产生影响,进而影响微生物生物量、微生物群落结构与多样性、土壤酶活性,以及碳、氮循环和污染物降解等土壤生物地球化学过程,且微塑料对上述指标的影响与微塑料自身性质、土壤类型和暴露条件等多种因素有关。最后,对未来土壤微塑料的研究方向做了展望,以期为后续研究提供参考和思路。     

生物炭对土壤重金属化学形态影响的作用机制研究进展

生物炭作为一种新型的环境修复材料,可以利用其结构特性,通过静电吸附、离子交换、官能团络合以及沉淀等作用机制来直接吸附固定土壤重金属,同时还可以通过间接影响土壤理化性质,比如土壤pH值、有机质、氧化还原电位等,从而影响土壤中重金属形态。重金属形态在更大程度上影响着重金属的生物活性,从而产生不同的环境效应。该研究基于国内外相关文献,概述了不同类型生物炭对土壤重金属化学形态变化的影响,并从物理、化学和微生物3个角度,阐述了生物炭影响重金属化学形态的作用机制。未来的研究侧重于生物炭与微生物的相互作用对重金属形态的影响,通过多组学手段,深入分析两者相互作用影响土壤重金属形态的微生物作用机理。     

生物炭对土壤生境及植物生长影响的研究进展

生物炭是指由含碳量丰富的生物质在无氧或限氧的条件下低温热解而得到的一种细粒度、多孔性的碳质材料。近年来,生物炭作为一类新型环境功能材料引起广泛关注,其在土壤改良、温室气体减排以及受污染环境修复等方面都展现出应用潜力,已成为当前的研究热点。综述了生物炭对土壤生境以及植物生长方面的影响机制,并指出未来研究的主要方向。国内外最新的研究表明:生物炭的高孔隙度和表面面积,可以增加砂性土壤的田间持水量,但这种增加效应是有限度的;生物炭的碱性属性使其能够提高酸性土壤的pH值,这对喜碱作物的生长具有积极意义;生物炭能够抑制土壤氮磷养分淋失,提高肥料利用率;生物炭的添加会增加土壤微生物量,改变土壤微生物群落结构组成和土壤酶活性;生物炭的添加改善了土壤性质、养分状况以及土壤微生物性质,进而促进了植物生长。但生物炭对土壤生境和植物生长的影响效应要取决于土壤肥力和性质、植物种类、以及生物炭的特性和施用量等因素。因此,必须根据不同土壤的主要障碍因子,选择合适的生物炭,以期得到较好的土壤改良效果。今后应加强生物炭在林地土壤改良以及林木生长方面的研究与应用,进一步探索生物炭在土壤中发生的生物和化学反应机理,并且要对生物炭的施用效果进行野外长期定位研究。     

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.     

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.     

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.