淮南燃煤电厂汞分配、富集与释放通量

汞是一种环境有害元素,燃煤汞排放业已成为当今中国最主要的汞污染源.有效的汞减排政策的制定需要准确了解煤中汞在煤炭燃烧过程中的分配规律及富集模式.本研究针对淮南燃煤电厂的原煤、飞灰、脱硫石膏和脱硫废水进行分析,研究发现,灰渣中的汞含量最低(9.8—27 ng·g~(-1)),其相对于原煤汞(约450 ng·g~(-1))的富集系数一般小于2.1%;飞灰中汞的含量相对较高(121—700 ng·g~(-1)),其富集系数介于9%—54%;而脱硫石膏中汞的浓度最高(1489—4589 ng·g~(-1)).通过物料平衡原理,计算出汞在各个燃煤产物中的分配如下:底灰占1%;飞灰占24%—32%;脱硫石膏及废渣液占7%—22%;大气排放占54%—64%.静电除尘器的脱汞效率为24%—32%,接近世界平均值;而脱硫装置的脱汞效率较低,为10%—29%.根据本研究的汞释放系数(0.24—0.29 g Hg·t~(-1)coal),计算出该电厂在2003—2010年的汞排放通量为1.8—7.3 t.本研究认为燃烧前原煤汞脱除,以及加大对现有脱硫装置的改造能够有效降低大气汞排放.     

华南某垃圾焚烧厂排放PCBs和PCNs的固气分布、同系物分布及毒性当量特征

以华南某城市生活垃圾焚烧厂一期(WI-A)和二期(WI-B)为研究对象,采集了飞灰和烟气样品,通过GC/MS对其中PCBs和PCNs的全部单体进行了测定,分析了PCBs和PCNs的固气分布(飞灰和烟气中的总量比例)、同系物分布以及毒性当量特征.结果表明,WI-A和WI-B焚烧单位垃圾产生的PCBs和PCNs总量分别为0.397 mg·t-1(湿基)和0.363 mg·t-1(湿基).活性炭喷射量对PCBs的固气分布特征和去除率影响较大,对PCNs则不明显.PCBs同系物在烟气中以低氯取代单体为主,在飞灰中以高氯取代单体为主.PCNs同系物在烟气中以五氯单体为主,在飞灰中以四氯、五氯单体为主.WI-A和WI-B排放的烟气总TEQ分别为0.051 ng TEQ·Nm-3和0.096 ng TEQ·Nm-3,WI-A烟气Co-PCBs和Dl-PCNs对总TEQ的贡献率分别为3.2%和0.13%,WI-B烟气Co-PCBs和Dl-PCNs对总TEQ的贡献率分别为5.3%和0.34%,提示垃圾焚烧排放烟气中的Co-PCBs和Dl-PCNs的毒性同样值得关注.     

上海浦东垃圾焚烧发电厂飞灰性质研究

研究了上海浦东新区垃圾焚烧发电厂烟气净化系统飞灰的物理和化学性质 .结果表明 :飞灰为含水率很低的灰色粉末 ,主要由Si,Al,Ca,Na ,K ,Mg ,Fe ,C和S组成 .飞灰中Pb的浸出浓度高于危险废物鉴别标准 ,为危险废物 .矿物组成主要为SiO2 ,Al2 SiO5,Na Cl,KCl,CaAl2 Si2 O8,Zn2 SiO4,CaCO3和CaSO4等 ;溶解盐含量高达 1 7 9%— 2 2 1 % ,酸中和能力约为 3 0meq·g- 1 — 6 0meq·g- 1 ,对环境pH变化的抵抗能力强 .     

贵州城市生活垃圾焚烧过程中重金属分布和迁移特征

为了探明城市生活垃圾焚烧过程中重金属分布和迁移特征,采集贵州遵义市3个城市生活垃圾焚烧场的进场垃圾、渗滤液、飞灰、底渣和烟气样品,采用ICP-AES分析了城市生活垃圾各组分中Cu、Pb、Zn、Ni、Cd、Cr和Hg重金属含量,研究其重金属的分布和迁移特征,为实现生活垃圾焚烧无害化处理提供基础数据。研究结果表明,(1)生活垃圾渗滤液中Zn、Ni、Cu和Pb含量较高,各重金属含量基本表现为垃圾场二垃圾场一垃圾场三,各组分重金属含量基本表现为ZnCuNiPbCrCdHg。(2)底渣中Cu、Zn、Cr含量较高,Cd和Hg含量较低,飞灰中Cu、Zn、Pb、Cr含量较高,Hg含量较低。(3)底渣和飞灰重金属浸出含量均未超标,其中Pb和Cu属于潜在污染,烟气排放含量低于0.2 mg·kg~(-1),Cr、Cu、Ni和Zn重金属在烟气中均无检出。(4)重金属向渗滤液的迁移相对较弱(低于1%),底渣、飞灰和烟气等与焚烧相关的产物是重金属的主要迁移途径,Cu、Ni、Cr、Zn主要迁移至底渣中,Pb和Cd主要迁移至底渣和飞灰中,Hg主要迁移至飞灰和烟气中(27.1%~34.6%随烟气排出),综上可知,生活垃圾中Hg的治理和脱毒仍需要进一步提高。     

协同处置废物水泥窑汞等非常规污染物分析与排放

近年来我国城市固体废物产生量逐年增加,水泥窑协同处置废物技术发展迅速.本研究选择1台规模为3200 t·d~(-1)的协同处置固废水泥窑,对烟气中汞等非常规污染物排放浓度进行现场测试,研究汞等非常规污染物分析与排放.研究表明,协同处置废物水泥窑窑尾烟气出口Hg~0占比79%,Hg~(2+)占比21%左右,烟气中Tl+Cd+Pb+As和Be+Cr+Sn+Sb+Cu+Co+Mn+Ni+V平均浓度为32.12μg·m~(-3)和10.54μg·m~(-3)均低于我国协同处置固体废物水泥窑窑尾允许排放限值1.0 mg·m~(-3)和0.5 mg·m~(-3),窑尾烟气中HF平均0.21 mg·m~(-3),HCl平均4.49 mg·m~(-3),PM_(2.5)窑尾和窑头袋式除尘后出口烟气浓度,窑尾排放浓度较窑头高.     

类芬顿试剂吸收去除气态元素汞

实验初步研究了类芬顿试剂为吸收剂对气态元素汞的脱除性能,考察了铁盐种类、pH、初始汞浓度、反应温度、卤素离子、甲酸添加量等因素对类芬顿试剂脱除气态元素汞性能的影响.结果表明,在pH 3.5条件下,以氯化铁为催化剂时,气态元素汞的脱除效率为76.4%;添加250μg.mL-1Cl-、150μg.mL-1Br-或5.0μg.mL-1甲酸均可以显著提高类芬顿反应体系对气态元素汞的脱除效果,最高脱除效率可达95%以上.     

冬季降雪过程对城市大气气态汞污染的影响

2009年降雪和非降雪期间对北京西北城区的气态总汞浓度进行了连续采样,比较了降雪期间、非降雪期间的气态总汞浓度日变化过程;降雪期间气态总汞浓度的降低和恢复过程。结果表明,降雪和非降雪期间大气气态总汞浓度的日均值有显著差异,降雪期间气态总汞的平均浓度为5．64ng·m^-3,非降雪期间的平均浓度为7．43ng·m^-3,前者约为后者的70％。降雪后约7h气态总汞浓度恢复到降雪前水平。研究中分析了气象因素（气压、风速、阵风速度、气温和相对湿度）对于气态总汞浓度的影响,结果表明：降雪期间主要受到风速（r=-0．527）和阵风速度（r=-0．574）的影响;非降雪期间主要受到风速（r=-0．691）,阵风速度（r=-0．726）和相对湿度（r=0．692）的影响,并且相对湿度的影响与风速的影响相近。降雪和非降雪期间气态总汞的日变化有所差异：非降雪期间气态总汞浓度在午夜和清晨较高,日变化趋势与相对湿度一致;降雪期间气态总汞的日变化没有明显规律。     

燃煤灰渣中微量元素分布规律的研究

研究了锅炉飞灰和底灰中１５种微量元素的含量和分布，探讨了煤炭燃烧后，微量元素在灰渣中的集散及其影响因素，飞灰和底灰中大多数元素高于全国土壤背景值，７种元素高于克拉克值，其余８种低于克拉克值，飞灰中多数元素的地球化学富集因子高于１，呈富集状态，而底灰中多数元素富集因子小于１，飞灰和底灰中微量元素含量与煤中微量元素含量呈线性关系，微量元素含量不仅与煤有关，还受锅炉燃烧方式等人为因素影响。     

电厂污泥掺烧过程中元素迁移特性研究

电厂污泥掺烧的重金属元素及其他有害元素被排放到大气中,会对大气环境质量和人体健康产生不利的影响。采用X射线荧光光谱仪对厦门集美区某污泥掺烧燃煤电厂掺烧入炉煤、污泥、飞灰和底灰4种固体样品中的元素水平进行测定,分析了样品中Na、Mg、Al、Si、Ca、Fe、S、K、Ti等9种常量元素,以及P、Zn、Cu、Mn、Ni、Cr、As、Pb等8种微量元素的含量,并对元素的迁移特性进行研究。结果表明,由于污泥中元素含量较普通燃煤高,导致污泥掺烧电厂飞灰及底灰中的元素含量普遍高于普通燃煤电厂。元素在飞灰及底灰中的相对富集系数也表明微量元素更容易富集在飞灰中。通过计算元素的年挥发量发现,以气体形式较大量挥发的有害元素有:S、P、Mn、Zn、Pb、Cu、Ni、As、Cr,其中Cr及S的排放浓度超过国家标准限值。这些元素的环境风险影响需引起高度重视。     

上海市公园绿地常见落叶树木叶片汞浓度时空特征及环境意义

植物叶片汞浓度与大气气态单质汞(GEM/Hg0)浓度的线性关系表明叶片汞浓度大小可用于指示植物生长区内GEM浓度的高低水平.通过分析上海市绿地公园(25座)中常见落叶树木樱花、水杉、法桐叶片汞浓度的时空变化特征,探究区域内GEM含量水平及分布特征.2017年5—10月对7座公园中这3种树木叶汞浓度进行连续监测,结果显示叶汞浓度与叶片生长时间呈显著线性正相关关系(P<0.01),表明叶片在生长期内不断吸收累积大气汞.而且在生长期内,3种树木叶汞浓度日累积速率(g·kg^-1·d^-1)具有相似的变化趋势,意味着不同树木叶汞的累积对外界环境的响应可能是一致的,除树种差异外.同年11月初,25座公园(包含上述7座)中樱花、水杉、法桐衰老叶片叶汞浓度为(54.2±12,31.8—76.7)μg·kg^-1、(42.0±9,23.5—67.9)μg·kg^-1、(36.1±11,21.4—60.3)μg·kg^-1(平均值,范围),有显著的种间差异(P<0.01),而在中心城区和郊区间无显著差异(P>0.05).空间插值分析结果初步表明衰老叶片叶汞浓度的空间梯度差异不大,且高值区域没有完全重合.这表明了利用衰老叶片叶汞浓度反映区域GEM浓度整体水平空间分布规律存在一定的不确定性,仍需进一步深入研究.     

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     

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.     

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.     

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.     

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.     

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.     

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.     

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.