干旱区绿洲土壤中重金属的形态分布及生物有效性研究

测定了Cd、Pb、Zn和Ni等重金属在不同处理土壤中的全量和各赋存形态,以及它们在盆栽试验油菜（Brassica cole）中的质量分数,并利用Pearson相关系数分析了该区土壤-油菜体系的生物有效性。结果表明,供试绿洲土壤原状土中,Cd、Pb、Zn和Ni均以稳定的残渣态形式存在;而在处理土壤中,重金属被钝化的量有限,Cd的存在形式主要以碳酸盐态为主,Pb、Zn和Ni则主要以铁锰氧化态为主。根据相关性分析,油菜根部和叶部的Ni质量分数均与土壤中Ni的各非残渣态分布系数有相关性,表明当土壤中Ni以非残渣态存在时,活动性Ni的质量分数较高,其被生物吸收利用的可能性也较大;油菜根部的Zn质量分数与土壤中Zn的碳酸盐结合态分布系数显著的正相关性;油菜各部位Cd和Pb的质量分数与土壤中Cd和Pb的各形态分布系数之间无显著相关关系。     

铜陵矿区土壤中镉存在形态及生物有效性

采取Tessier连续提取法，研究铜陵矿区不同功能区表层土壤中镉的化学形态分布和生物有效性。结果表明，各种土壤中的镉含量全部高于地区背景值，主要来源与矿业活动有关，部分样品还有矿体的风化富集叠加，土壤镉污染指数PCd为1．15～79。镉含量依次为矿体风化土壤→废矿堆下垫土→市郊菜地土→矿区铜草土、路边土和稻田土→其它土壤。其形态分布，酸性土壤中以Fe-Mn氧化态和可交换态为主，其余三态相对较低；碱性土壤中有机态和残渣态比例较高，碳酸盐态和可交换态所占的比例低。土壤中生物可利用态镉的含量较高，占土壤总镉的60．20%-98．3％，生物不可利用态仅占1．7％-39．2％。     

水稻不同生育期土壤砷形态分布特征及其生物有效性研究

采用田间原位试验和Tessier连续提取方法,在水稻（Oryza sativa L.）不同生育期研究了重金属复合污染高、中、低3个水平下的土壤砷的形态分布特征及其生物有效性。结果表明：在水稻不同生育期中,土壤各种形态的砷质量分数均表现为高污染水平土壤〉中等污染水平土壤〉低污染水平土壤;土壤中砷在水稻整个生育期均以残留态为主,占90%以上,交换态砷所占比例最低,不到0.5%;不同形态砷之间大都显著正相关,但是两种有效性较高的砷形态（交换态和碳酸盐结合态）与有机态砷之间的相关性较差;土壤砷的生物有效性表现为高污染水平土壤〉中等污染水平土壤〉低污染水平土壤,且随着水稻生育期的延长,土壤砷的生物有效性逐渐升高。     

典型菜地土壤汞在小白菜和胡萝卜可食部位的富集规律

对广东省蔬菜种植面积较大的10个城市典型菜地土壤和蔬菜（小白菜和胡萝卜）对应采样,分析217个蔬菜可食部位中重金属汞（Hg）质量分数及对应土壤中Hg全量和有效态质量分数,研究大田条件下小白菜和胡萝卜可食部位富集Hg的规律。结果表明,广东省菜地土壤存在一定的Hg污染,约20％的土壤超过国家土壤环境质量标准（GBl5618－1995）中二级标准值,但小白菜和胡萝卜中Hg质量分数较低,均值分别为0．0012和0．0013mg·kg-1,仅2个小白菜样品Hg质量分数超过国家食品卫生标准《食品中污染物限量》（GB2762-2005）中的限值0．01mg·kg-1。TGA提取的土壤有效态Hg质量分数与土壤Hg全量显著正相关,TGA提取Hg量仅占土壤总Hg质量分数的3％-4％。小白菜和胡萝卜对Hg的富集系数分别为0．90％和0．94％,表明土壤中绝大部分的Hg不易转化迁移、为蔬菜吸收。小白菜和胡萝卜可食部位Hg质量分数与土壤中Hg全量和有效态质量分数均存在显著的线性关系,其中蔬菜与土壤Hg有效态质量分数的关系优于其与土壤Hg全量的关系。依据国家食品卫生标准,通过拟合回归方程计算出的保障小白菜和胡萝b质量安全的菜地土壤Hg有效态质量分数临界值分别为O．038和0．063mg·kg-1。计算出的土壤Hg全量临界值远大于我国现行土壤环境质量标准的二级标准值,表明该标准值对于保障广东省小白菜和胡萝b质量安全来说可能过于严格。     

4种改良剂对土壤-黑麦草系统中镉行为的影响

以黑麦草（Lolium perenne L.）作为修复植物,开展了石灰、磷灰石、木炭、猪粪4种改良剂对重金属Cd污染土壤的田间原位修复试验研究。结果表明：改良剂提高了土壤pH值并促进土壤Cd从生物可利用性高的形态向迟效态转化,降低对生物和环境的直接毒害作用,促进黑麦草的生长。以黑麦草生物量和Cd富集量的增加作为评价指标,4种改良剂修复Cd污染土壤效果依次为：石灰〉磷灰石〉木炭〉猪粪。石灰处理中黑麦草Cd富集量为13.11 mg,与其他处理均呈现显著差异。污染土壤重金属Cd的化学形态与黑麦草对Cd的吸收密切相关。黑麦草地上部分Cd质量分数,与土壤B-2态Cd呈极显著正相关关系,相关系数为0.730。黑麦草地下部分Cd质量分数,与B-2、B-3态Cd均呈极显著正相关关系,相关系数分别为0.756、0.786;黑麦草地上部分和地下部分Cd质量分数均与B-4态Cd呈极显著负相关关系,相关系数分别为0.757和0.708。     

基于多表面形态模型的土壤镉在小白菜中的富集效应

基于土壤理化性质和热力学化学平衡的多表面形态模型(multi-surface speciation model,MSM)近年来已成功被应用于描述多种痕量元素在土壤固/液相间的分配,但在土壤-植物系统中的应用尚不多见.本文采用室内盆栽实验,调查了我国6种代表性土壤中Cd(Ⅱ)在小白菜中的生物富集情况,首先比较了5种化学提取方法(总Cd、CaCl_2、HNO_3、Mehlich-3和BCR)测定的有效态Cd与小白菜中Cd富集量之间的相关性,其次基于MSM预测土壤中溶解态Cd(Ⅱ)浓度并与Cd在白菜中富集量进行了相关性分析,同时考察了不同模型架构下模型对相关性的影响.结果表明,MSM预测的土壤中溶解态Cd浓度与小白菜中Cd富集量之间有较好的相关性,大部分模型架构下优于化学提取法,说明MSM一定程度上反映了土壤理化性质对Cd生物有效性的影响.由于MSM在计算过程中基于热力学参数,因此具有很好的外延性,说明其在土壤-植物系统中重金属生物有效性和风险评价方面具有较大的潜力.     

施硅对污染土壤中铬形态及其生物有效性的影响

关于硅对蔬菜重金属生物有效性和对菜田土壤重金属铬形态影响的问题的研究目前仍嫌较少,该文采用盆栽试验结果讨论了在铬污染菜田土壤上施不同量硅对铬形态和蔬菜生物有效性的影响作用.研究表明,在铬污染条件下,施可溶性硅酸盐,与对照相比,土壤的交换态铬含量降低,而沉淀态铬和残渣态铬含量提高,因而可降低铬的蔬菜生物有效性,使小白菜(Brassica chinensis)体内的铬含量明显降低.同时还可使小白菜的生物量显著提高.     

根际土壤中Cd、Pb形态转化及其植物效应

采用根袋盆栽试验和连续形态分析方法研究根际土壤中Cd、Pb形态转化及其植物效应。结果表明，(1)在低Cd质量分数(≤1mg／kg)污染条件下，根际土壤中cd主要以残渣态存在；在较高cd质量分数(≥5mg／kg)污染条件下，cd主要以交换态和碳酸盐结合态存在，即根际土壤中Cd由残渣态向交换态和碳酸盐结合态转化，Cd活性增强。(2)Pb在根际土壤中主要以有机结合态和铁锰氧化物结合态存在，交换态质量分数很低，并随Pb污染水平的提高，其主要存在形态未改变。(3)土壤中Cd、Pb总质量分数及各形态质量分数(残渣态除外)与小麦根、茎叶中Cd、Pb质量分数呈正相关性，而与鲜质量呈负相关性；当w(Cd)添加量≥5mg／kg时，小麦鲜质量明显下降；当w(Pb)≥500mg／kg时，小麦鲜质量下降。     

湖南南部铅锌矿区铅锌富集植物筛选研究

在湖南省桂阳县铅锌矿区采用调查和室内分析相结合的方法,采集植物和土壤样品112个,分别测定了土壤和植物样品的铅锌含量,筛选铅锌富集植物。结果表明：矿区土壤铅锌污染十分严重,矿区土壤铅和锌的平均质量分数分别为：2177.22、3165.89 mg·kg^-1。植物样品根系的铅锌质量分数分别为：264.00、666.11 mg·kg^-1,地上部铅锌质量分数平均为165.56、363.87 mg·kg^-1,植物根系的铅锌含量与土壤的铅锌含量呈显著正相关。通过对比分析,以地上部铅质量分数大于450 mg·kg^-1、锌质量分数大于750 mg·kg^-1、转运系数大于1、植物地上部形态高大为筛选条件,筛选出5种铅富集植物分别是：糯米团（Hyrtanandra）、水蓼（Polygonum hydropiper）、酸模（RumexacetosaLinn）、毛叶堇菜（Viola verecumda A.Gray）、地榆（Garden Burnet Root）;3种锌富集植物分别是：鬼针草（Bidens pilosa L.）、博落回（Macleaya cordata（Willd.） R. Brown）和糯米团;糯米团茎叶的铅锌质量分数分别为635.48、919.51 mg·kg^-1,可作为铅锌复合污染土壤修复的备选植物品种。     

化工污染河流沿岸植物对砷、汞的累积作用比较

采集葫芦岛市五里河沿岸9种常见植物,测定植物及植物根土中的汞砷质量分数,研究了汞、砷在植物体内的分布特征,利用迁移系数、富集系数探讨了植物对砷、汞的吸收与富集作用以及可能的耐受机制.结果表明,植物对砷、汞的吸收与富集,因植物种类、部位、金属的类型以及距离污染源的远近而不同.植物根部砷、汞平均质量分数分别为2.434 mg·kg-1和0.583 mg·kg-1;植物叶部砷、汞平均质量分数分别为1.888 mg·kg-1,0.1 50 mg·kg-1.叶汞质量分数从高到低的顺序为:水蓼,芦苇,鬼针草,曼陀罗,三棱草,苍耳,稗草,滨藜,辽东蒿;根汞质量分数从高到低依次为:三棱草,曼陀罗,滨藜,稗草,辽东蒿,芦苇,鬼针草,苍耳,水蓼;叶砷质量分数从高到低的顺序为:水蓼,滨藜,鬼针草,苍耳,芦苇,三棱草,曼陀罗,稗草,辽东蒿.芦苇(Phragraites australis)、曼陀罗(Datura stramonium)、苍耳(.Xanthium sibiricum.Patr.)、鬼针草(Bidens bipinnata)、滨藜(Atriplex patens)对砷的吸收、富集效果较好;水蓼(Polygonum hydropiper)对汞的转移能力较强.芦苇、鬼针草、水蓼等植物向地上部转移As、Hg的能力较强,可选做植物提取方式的污染土壤修复.     

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.     

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.     

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.     

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.