重庆市垃圾焚烧飞灰粒径分布及重金属形态分析

采用筛分法研究了重庆市生活垃圾焚烧飞灰中的粒径分布,分析了各粒径颗粒中Pb、Cd、Zn、Cu、Mn、Ni和Cr等重金属的总量,并利用Tessier五步连续提取法对不同粒径飞灰中各重金属的化学形态进行了分析.结果表明,90%以上的飞灰粒径小于250 μm,其中粒径为149-250 μm的颗粒最多,约占总量的50%.除Ni之外,其它重金属的含量随粒径的减小呈先减小后增大的趋势.粒径小于250 μm颗粒中的重金属含量对飞灰中重金属含量的贡献率达到90%.飞灰中各重金属的形态分布随粒径变化规律不同,Zn、Cd、Pb、Cu的碳酸盐结合态含量略高,在重庆地区酸雨的淋溶下极易释放出来,对周围环境存在潜在威胁.     

中国城市公园灰尘的重金属空间分布特征及其影响因素

通过收集公开发表的中国城市公园灰尘重金属数据,分析公园灰尘中Cr、Cu、Zn、Pd、Ni和Cd等6种元素的空间分布特征及富集状况,并对其影响因素进行了探讨.结果 表明,Cr、Cu、Zn、Cd等4种重金属含量的空间分布具有相似性,东部地区为高值区,东北地区和西北地区为低值区;Pb和Ni具有相似的空间分布特征,东部和中部地...     

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。     

长江下游典型工农业交错区土壤重金属含量随时间变化特征

以长江下游八卦洲工农业交错区为研究区,研究了表层土壤2014年相对于2003年重金属等元素含量变化特征、富集机制与影响因素.结果表明,2014年研究区土壤Cd、Zn、Cu、Cr平均含量较2003年发生显著的增加,其增加率分别为32%、15%、14%和11%;Hg平均含量发生了显著的下降,下降率是20%;As、Pb和Ni含量未随时间呈现出显著变化.土壤Cu、Zn、Ni、Cr、Cd和As在大多采样点表现为含量的增加;Hg在大多数采样点表现为含量降低.分析表明,重金属富集范围和程度的变化主要受研究区周围工业分布以及调整的影响,大气沉降是土壤Cd、Cu、Zn、Cr、Ni等重金属富集加强最主要的贡献因子,而土壤Hg含量的降低主要与Hg的地球化学行为特性以及产业结构调整有关.土壤重金属富集不仅与外源物质输入有关,元素本身的地球化学性质和行为导向也是非常重要的影响因素.     

三峡库区地质高背景区土壤-油菜重金属迁移特征

三峡库区广泛分布的黑色岩系富含镉（Cd）、铬（Cr）、镍（Ni）、锌（Zn）等重金属元素,导致土壤重金属元素含量显著高于我国土壤背景值,成为典型的地质高背景区。本文选择三峡库区地质高背景区油菜种植地为研究对象,分析了土壤-油菜系统中砷（As）、Cd、Zn、铜（Cu)、铅（Pb）、Cr、Ni、汞（Hg）等重金属元素含量分布特征、富集迁移规律以及影响因素。研究结果表明,研究区油菜种植地土壤中Cd、Cr、Cu、Hg、Ni等重金属含量显著高于我国土壤背景值,单因子污染指数评价显示土壤As、Zn、Hg、Pb等重金属均属于无污染等级,Cu、Ni污染程度受到pH影响,Cd为重度污染和极高生态风险。不同重金属元素在油菜各部位含量差异明显,Pb、Cd、As等生物非必需元素更倾向进入茎、果荚,营养元素Cu和Zn则在油菜籽中含量较高,而Cr易在果荚中富集。研究区土壤中重金属元素含量、土壤p H、重金属元素间的拮抗作用以及油菜解毒机制可能是影响重金属元素在土壤-油菜各部位富集迁移的重要因素。     

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。     

淮河江苏段沉积物重金属的分布特征、来源解析及其生态风险

为了解淮河江苏段沉积物重金属的污染特征、空间分布及其生态风险,对其表层沉积物中重金属（Cd、Mn、Cu、Zn、As、Ni、Pb和Cr）的含量进行检测,利用相关性和主成分进行重金属来源分析,并采用富集系数与生物毒性不利影响对表层沉积物重金属进行污染评价.结果表明,除Cd与Cr外,Zn、Mn、As、Ni、Cu等重金属的含量均高于江苏土壤背景值.重金属含量空间分布差异明显,其中洪泽湖北部及围湖地区等地重金属污染状况最严重,来源可能来自城镇污水、工业废水等复合污染.富集水平排序为Zn>Mn>As>Ni>Cu>Pb>Cr>Cd,其中Mn、Zn富集程度最为明显.生物毒性不利影响评价总体处于中风险状态,主要贡献来源于Ni、Zn.除了Cu、Cd、Pb外,Ni、Zn、Cr、As重金属可能会对底栖动物产生危害作用.因此,淮河江苏段沉积物重金属整体表现为较重生态风险水平.     

镇江市古运河河岸沉积物重金属分布特征及潜在生态风险评价

对镇江市古运河河岸7个表层沉积物中重金属As、Cu、Pb、Cd、Zn、Cr含量进行测定,并通过富集系数、地累积指数法、潜在生态风险评价以及主成分分析等对沉积物重金属的分布特征进行综合分析与评价.结果表明:(1)古运河河岸带沉积物Cr、Cu、Zn、As、Pb和Cd元素的含量平均值分别为45.07、41.70、254.06、19.67、45.88、0.75 mg·kg-1,p H平均值为7.98.对比《国家土壤环境质量标准》可知,沉积物中Cu、Zn、Pb、As属于超一级标准,而Cd属于超二级标准.(2)6种重金属的富集系数表现为:AsCdPbZnCuCr,且综合富集系数在空间上表现为:G2G5G1G4G3G7G6;(3)古运河河岸表层沉积物地累积指数表现为AsCdPbCuZnCr,6种重金属中As富集量最大,Cr的富集量最小.(4)单项潜在生态危害系数结果表明,Cr、Cu、Zn、Pb均为轻微生态危害程度,As和Cd处于中等生态危害程度.从RI值判断,古运河河岸沉积物总体处于轻微生态危害.(5)相关性和主成分分析结果表明,Pb、Cu、Cr、Cd是决定第一主成分的4个主要因子,且Cu与Pb、Cd以及Pb与Cd元素具有相同的污染源.As、Zn在第二主成分中具有较高的载荷值,且As与Zn之间的相关性较弱,表明这两种重金属并非来自同一污染源.     

煤炭资源型城市街尘重金属富集与时空变化特征:以宿州市为例

为研究煤炭资源型城市街尘中重金属富集与时空变化特征,以宿州市为例,选取23个采样点进行了1 a连续采样。利用X射线荧光光谱分析仪对采集的276个街尘样品进行了Cr、Cu、Zn和Pb等含量检测,并分别用富集因子法和Origin等高线图对重金属富集和时空分布特征进行了研究。结果表明,Cr、Cu、Zn和Pb含量均值分别为112.9、27.5、225.3和45.2 mg·kg~(-1),分别是安徽省土壤背景值的1.7、1.3、3.6和1.7倍,与研究区其他环境介质(土壤和沉积物)的对比分析表明,街尘Cr和Zn含量相对较高。富集因子分析结果表明,Zn为中度富集,Cr、Cu和Pb均为轻度富集。4种重金属季节变化总体不明显,其中Cr含量夏季高于春季;Cu含量表现为春季高于夏、秋季,冬季高于秋季;Zn含量表现为夏季高于秋季;而Pb含量无显著季节差异。空间分布结果分析表明,Cr高值区主要位于新工业区附近及采煤矿区方向,而Cu、Zn和Pb高值区多分布在人为活动较频繁的交通运输区和中心城区。结合数理分析发现,Cr可能主要来自工业活动,而Cu、Zn和Pb可能主要与交通活动有关。冬季燃煤以及区域风向、风速对重金属的空间分布有重要影响。     

常州市道路两侧户外灰尘重金属分布、形态及环境风险

在常州市城区、城郊和农村20个道路断面50 m范围内采集140个户外灰尘样品,测定Cu、Zn、Pb、Cd、Ni、Cr和Mn等重金属的含量,分析其区域差异、垂直分布和化学形态特征,进行富集系数和污染系数分析,并构建了涵盖灰尘重金属含量、形态和毒性的环境风险指数.结果表明,以上各重金属含量平均值分别为173.51、952.66、444.50、3.16、115.64、132.44、801.59 mg·kg-1.随着楼层的升高,城区灰尘中Pb、Mn和Cr的含量呈递减趋势,Cd、Cu和Zn含量没有显著变化,Ni含量呈上升趋势.Cu和Cr主要为残渣态,Zn、Pb和Cd主要为可还原态,Ni主要为酸可提取态.Cd的环境风险等级为严重,Pb为重或严重,Cu和Zn为较低或中,Ni为中,Cr和Mn为低.     

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.     

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.     

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.     

Human Influence and Classical Biogeographic Predictors of Rare Species Occurrence

Biogeographic theory predicts that rare species occur more often in larger, less‐isolated habitat patches and suggests that patch size and connectivity are positive predictors of patch quality for conservation. However, in areas substantially modified by humans, rare species may be relegated to the most isolated patches. We used data from plant surveys of 81 meadow patches in the Georgia Basin of Canada and the United States to show that presence of threatened and endangered plants was positively predicted for patches that were isolated on small islands surrounded by ocean and for patches that were isolated by surrounding forest. Neither patch size nor connectivity were positive predictors of rare species occurrence. Thus, in our study area, human influence, presumably due to disturbance or introduction of competitive non‐native species, appears to have overwhelmed classical predictors of rare species distribution, such that greater patch isolation appeared to favor presence of rare species. We suggest conservation planners consider the potential advantages of protecting geographically isolated patches in human‐modified landscapes because such patches may represent the only habitats in which rare species are likely to persist. Influencia Humana y Predictores Biogeográficos Clásicos de la Ocurrencia de Especies Raras     

Seasonal dynamics of macro-algae in the South Lake of Tunis

The macro-algae communities observed in the south lake of Tunis are characterized by the predominance of nitrophilous algae which are in the order of biomass importance:Ulva, Cladophora andEnteromorpha. We have noted seasonal changes of alga distribution. The wind appears to be one of the most important factors influencing this distribution. The total biomass reaches a maximum in the spring. Rapid decomposition of the biomass leads to a severe ecological imbalance, resulting in crises of anoxia and fish death. A restoration project has already started. It aims at removal of contaminated muds and the introduction of a new circulation system. The main objectives of this work were to collect information on the distribution and biomass of the phytobenthic communities as a first step in the constitution of a database for further comparison.     

Patterns and biases of climate change threats in the IUCN Red List

International Union for Conservation of Nature (IUCN) Red List assessments rely on published data and expert inputs, and biases can be introduced where underlying definitions and concepts are ambiguous. Consideration of climate change threat is no exception, and recently numerous approaches to assessing the threat of climate change to species have been developed. We explored IUCN Red List assessments of amphibians and birds to determine whether species listed as threatened by climate change display distinct patterns in terms of habitat occupied and additional nonclimatic threats faced. We compared IUCN Red List data with a published data set of species’ biological and ecological traits believed to infer high vulnerability to climate change and determined whether distributions of climate change‐threatened species on the IUCN Red List concur with those of climate change‐threatened species identified with the trait‐based approach and whether species possessing these traits are more likely to have climate change listed as a threat on the IUCN Red List. Species in some ecosystems (e.g., grassland, shrubland) and subject to particular threats (e.g., invasive species) were more likely to have climate change as a listed threat. Geographical patterns of climate change‐threatened amphibians and birds on the IUCN Red List were incongruent with patterns of global species richness and patterns identified using trait‐based approaches. Certain traits were linked to increases or decreases in the likelihood of a species being threatened by climate change. Broad temperature tolerance of a species was consistently related to an increased likelihood of climate change threat, indicating counterintuitive relationships in IUCN assessments. To improve the robustness of species assessments of the vulnerability or extinction risk associated with climate change, we suggest IUCN adopt a more cohesive approach whereby specific traits highlighted by our results are considered in Red List assessments. To achieve this and to strengthen the climate change‐vulnerability assessments approach, it is necessary to identify and implement logical avenues for further research into traits that make species vulnerable to climate change (including population‐level threats).     

Parasitic wasps orient to green leaf volatiles

Summary Undamaged plants emit low levels of green leaf volatiles (GLVs), while caterpillar-damaged and artificially damaged plants emit relatively higher levels of certain GLVs. Female braconid parasitoids,Microplitis croceipes, oriented to both damaged plants and to individual GLVs in no-choice tests in a wind tunnel, but seldom oriented to undamaged plants. Female ichneumonid parasitoids,Netelia heroica, also oriented to individual GLVs in a wind tunnel. Males of both wasp species failed to orient to the GLVs. These data show that leaf-feeding caterpillars can cause the release of GLVs, and that parasitic wasps can respond to these odors by flying upwind (chemoanemotactic response), which brings the wasps to their caterpillar hosts. This supports the hypothesis that plants communicate with members of the third trophic level,i.e., plants under herbivore attack emit chemical signals that guide natural enemies of herbivores to sites of plant damage. In this interaction, the GLVs serve as tritrophic plant-to-parasitoid synomones. That parasitoids from two different wasp families oriented to GLVs suggests that the response may be widespread among the Hymenoptera.Mention of a commercial or proprietary product does not constitute an endorsement by the U.S. Department of Agriculture