北京市场大米和小麦面粉中砷的含量及其形态分析

以湖南省某污染区大米为对照,分析了北京市场大米、小麦面粉中总砷的含量水平和部分米中砷的形态.北京市场大米总砷的含量范围从未检出至0.218μg·g-1,算术平均值为0.097μg·g-1.湖南省某污染区大米总砷的含量范围为0.157-2.885μg·g-1,算术平均值为0.415μg·g-1,4例湖南省某污染区大米以无机砷为主,平均含量为0.341μg·g-1.北京市场面粉总砷的含量范围从未检出至0.057μg·g-1,算术平均值为0.006μg·g-1.有17例面粉样品未检出砷,占总样品的45%.与《食品中砷限量指标》(GB2762-2005)的限量值(大米无机砷0.15μg·g-1,面粉无机砷0.1μg·g-1)相比,北京市场的大米和面粉均未超标.湖南省某污染区4例大米无机砷含量全部超过限量标准,为标准的1.2-4.8倍.以WHO最大日允许无机砷摄入量2.1μg·kg-1 bw·d-1为参照标准,普通成人每日通过北京市场大米和面粉摄入的无机砷相当于WHO最大日允许摄入无机砷量(MTDI)的13%和0.5%,通过湖南省某污染区大米摄入的无机砷则相当于MTDI的57%.     

液相色谱-电感耦合等离子体质谱法联用(HPLC-ICP-MS)测定乳制品的无机砷及其它砷形态

采用液相色谱-电感耦合等离子体质谱联用技术测定了乳制品中的无机砷及其它砷形态,各种砷形态的方法检出限(以砷计)分别为:三价砷As(Ⅲ)2.0ng·g-1,五价砷As(Ⅴ)3.0ng·g-1,一甲基胂MMA2.0 ng·g-1,二甲基胂DMA 1.0 ng·g-1,甜菜碱As B 1.0 ng·g-1,根据加标回收的方法评价了该方法的准确性,无机砷的加标回收率为89.9%-98.1%,相对标准偏差为1.09%-3.21%(n=6),根据所建立的方法,分析了市售的部分鲜奶、酸奶和奶粉样品,其中无机砷的含量均未超出国家标准限量.     

饮水型砷中毒病区人群砷暴露量及尿砷的季节变化

地下水高砷暴露的健康危害是环境与健康领域面临的巨大挑战。水砷含量及暴露人群饮水量参数的季节性变化可能影响饮水砷暴露评估的准确性。本研究选择内蒙古饮水砷中毒病区为研究区,测定丰水期(2013年5月)和枯水期(2013年12月)居民饮用水和尿液各形态砷(三价无机砷iAs~(3+)、五价无机砷iAs~(5+)、一甲基砷MMA~(5+)和二甲基砷DMA~(5+)+)含量,研究砷暴露量和尿砷的季节变化。结果表明,丰水期水砷含量(134.4±25.8)μg·L~(-1)显著低于枯水期的(163.2±38.1)μg·L~(-1),且丰水期水中iAs~(3+)的含量(58.9±51.2)μg·L~(-1)也显著低于枯水期的(100.1±49.0)μg·L~(-1)。研究人群丰水期通过饮水的摄砷量为313.1μg·d~(-1),低于枯水期的378.6μg·d~(-1)。此外,丰水期居民尿液总砷含量(218.6μg·L~(-1))显著低于枯水期(283.1μg·L~(-1))。丰水期女性居民尿液iAs、MMA~(5+)和总砷含量随当季饮水iAs~(5+)含量的升高而显著降低,枯水期女性尿液MMA5+含量随当季饮水iAs~(3+)及iAs含量的升高而显著升高。可见,病区居民饮水砷暴露量与尿砷含量具有明显的季节差异性,饮水砷与尿砷的关系受饮水砷形态、季节变化及性别等因素影响。     

饮水砷中毒病区水砷形态变化特征

水源水经水管传输后,其砷形态的含量及其百分比变化特征研究较少.因此,本文选择内蒙古某饮水型砷中毒病区为研究区,分析饮用的水源水日际和日内总无机砷含量(iAs)、以及水源水传输到用户端的末梢水和储存水的无机砷形态含量(iAs~Ⅲ、iAs~Ⅴ).结果发现,水源水iAs~Ⅲ、iAs~Ⅴ和iAs的平均含量分别为32.19、64.58、96.77μg·L~(-1),末梢水iAs~Ⅲ、iAs~Ⅴ和iAs的平均含量分别为100.11、63.09、163.21μg·L~(-1),而储存水iAs~Ⅲ、iAs~Ⅴ和iAs的平均含量分别为14.72、126.41、141.12μg·L_(-1).水源水的iAs~Ⅴ和iAs含量日内具有明显的变化,iAs含量在日际间无明显的差异,而iAs~Ⅲ和iAs~Ⅴ含量在日际间存在较为明显的变化.此外,水源水、末梢水和储存水的iAs~Ⅲ占总无机砷的比例分别为33.26%、61.33%和10.43%,而iAs~Ⅴ占总无机砷的比例分别为66.74%、38.67%和89.57%.该结果表明,饮水砷形态的转化可能受到水与空气接触时间、气温、气压和水温等因素的影响,且水源水在水管传输过程中可能导致末梢水和储存水的iAs含量增加.因此,饮水砷的暴露评估应关注不同形态的砷暴露以及饮水类型的砷暴露.     

广州市居民食品砷摄入的健康风险评价

从暴露途径来看,食物是人体砷暴露的主要途径之一。从饮食结构来看,广州市居民膳食主要来源于谷类食品,同时鱼虾类总体平均摄入量约为全国总体平均摄入量的2倍。因此,在分析广州市市场大米和海鲜这2种典型食品中砷含量的基础上对广州市居民食品砷摄入的健康风险进行了评价。分析了广州市场上的26种不同品牌的大米中的总砷含量,其含量范围为0.082～0.171μg·g~(-1),平均浓度为(0.127±0.027)μg·g~(-1),满足绿色食品大米标准(≤0.40μg·g~(-1))。在14种鱼虾蟹贝类海鲜中的砷含量分析基础上,计算得出广州市场上鱼类中总砷的平均含量为0.488μg·g~(-1),虾蟹贝类中总砷的平均含量为3.44μg·g~(-1),相比较国内外,广州市场鱼虾蟹中砷的含量整体处于中间水平。最后综合文献调研中其他主要食品中砷的含量,计算得出广州市成人通过食品每日摄入总砷的量为5.08μg·kg~(-1)BW·d~(-1)。建议日常饮食需要特别控制每日海鲜的摄入量,尤其是砷含量较高的濑尿虾、红虾及红蟹、花蟹。     

ICP-MS法测定电子电器材料中的有害元素铅、镉、砷、铬

建立了电感耦合等离子体质谱测定不同基体的电子电器材料中铅、镉、铬、砷四种有害元素的方法.对仪器的参数、测试稳定性等作了系统研究,优化了对不同基体样品中铅、镉、铬、砷元素分析的前处理条件,探讨了各种材料中基体元素与其它共存元素对待测元素的影响.方法检出限为0.0024-0.46μg·g-1,对标准物质的测定值与参考值相符,相对准偏差为0.6%-5.8%.     

陕西省潼关采金地区汞污染的初步研究

对采金地区水样、沉积物、土壤及部分水藻和苔藓的分析表明 :潼关采金地区已经受到严重的汞污染 .水体总汞浓度最高达 2 5 8 62 μg·l- 1 ,且水样中的汞以颗粒态为主 ,大都占 5 0 %以上 ,而活性汞和溶解态汞的平均浓度分别为 0 1 82± 0 2 4 2 μg·l- 1 和 0 72± 0 79μg·l- 1 ;沉积物中平均汞浓度为 34 98± 2 5 39μg·g- 1 ,最高达 1 1 96μg·g- 1 ;而土壤中汞的浓度最高也只有 1 9 5 0 μg·g- 1 .     

福建闽南沿海养殖僧帽牡蛎中汞和砷的时空分布特征及风险评价

通过2009—2014年对福建闽南沿海的湄洲湾、大港湾、泉州湾、围头湾、厦门湾、佛昙湾、旧镇湾、东山湾、和诏安湾养殖的僧帽牡蛎中总汞和总砷含量的调查监测,对养殖僧帽牡蛎体中总汞和总砷含量的分布和食用风险进行探讨.结果表明,近6年9个湾海区养殖僧帽牡蛎体中总汞平均质量浓度(0.007—0.018 mg·kg~(-1)):湄洲湾泉州湾厦门湾诏安湾围头湾=旧镇湾=大港湾=东山湾佛昙湾;总砷平均质量浓度(1.40—2.02 mg·kg~(-1)):泉州湾厦门湾大港湾湄洲湾诏安湾东山湾围头湾旧镇湾佛昙湾.湄洲湾、泉州湾、厦门湾大部分海水养殖僧帽牡蛎体中总汞和总砷含量明显高于其他海区养殖僧帽牡蛎.福建闽南沿海养殖僧帽牡蛎体未受到汞的污染,98.1%的样品受砷的污染.根据FAO/WHO/JECFA(联合国粮农组织和世界卫生组织下的食品添加剂联合专家委员会)提出的PTWI(暂定每周耐受摄入量)汞为5μg·kg~(-1)bw、无机砷为15μg·kg~(-1)bw.食用闽南沿海僧帽牡蛎中汞的EWI(每周评估摄入量)值均远小于PTWI,仅占PTWI的1.1%—1.4%;无机砷的EWI值均小于PTMI,占PTWI的7.0%—11.3%,总体处于安全水平.     

超声萃取气相色谱法测定植物样中邻苯二甲酸酯

建立了二氯甲烷超声萃取、氧化铝柱层析分离、带电子捕获毛细管气相色谱测定植物样品中痕量邻苯二甲酸酯(PAEs)的方法.方法具有较好的精密度(RSD≤10%)、较低的检测限(MDLDBP=0.4ng·g-1,MDLDEHP=0.5ng·g-1)和较高的回收率(RDBP=87.3%,RDEHP=92.1%).用该法测定了太湖沉水植物中的PAEs含量,其中DBP在0.009-0.013μg·g-1,DEHP在0.026-0.106μg·g-1.     

固相萃取-高效液相色谱-串联质谱法同时测定蔬菜中8种磺胺类抗生素

建立了固相萃取-高效液相色谱-串联质谱同时测定蔬菜中8种磺胺类抗生素(SAs)的分析方法.以10 mL乙腈(添加2 g无水硫酸钠、0.1 g乙酸钠、0.1 g Na2EDTA)进行提取,HLB柱净化富集.采用RESTEKPinnacleⅡC18色谱柱,以水(含0.1%甲酸)和乙腈(含0.1%甲酸)为初始流动相进行梯度洗脱.在电喷雾-多反应检测离子模式下,进行定性定量分析.SMZ的方法定量限为0.2μg·kg-1,其它7种化合物的定量限均为0.1μg·kg-1.不同加标浓度(5—100μg·kg-1)下8种SAs的回收率大部分约在70%以上,相对标准偏差(RSD)多数小于10%,表明该方法能够满足实际样品的分析要求.利用该方法对某无公害蔬菜基地进行分析,蔬菜中检出3种以上磺胺类抗生素,含量在0.20—17.43μg·kg-1(干重)之间,总含量在2.42—27.60μg·kg-1之间.     

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