衍生液注入控制-离子色谱法同时测定环境水样中的三价铬和六价铬

以2,6-吡啶二羧酸和1,5-二苯碳酰二肼为衍生试剂,采用柱前和柱后衍生的方式建立了离子色谱法同时测定环境水样中三价铬和六价铬的方法.通过六通阀控制1,5-二苯碳酰二肼注入系统的时间,避免了六价铬衍生液本底对三价铬测定的干扰,提高了三价铬检测的灵敏度,将三价铬的检出限由原来的0.17 mg·L-1降低至5.9μg·L-1.同时,对检测波长、淋洗液浓度、衍生液流速和定量环体积进行了选择优化.该方法对0.72 mg·L-1Cr(Ⅲ)和0.24 mg·L-1Cr(Ⅵ)峰面积测定值的相对标准偏差分别为0.34%和0.65%,六价铬的检出限为3.2μg·L-1.测定了含铬污染废水、电镀厂处理前后的废水和河水共9个样品中Cr(Ⅲ)和Cr(Ⅵ)的含量,并进行了加标回收实验.结果表明,在0.02—0.48 mg·L-1加标范围内,Cr(Ⅲ)的加标回收率在83.7%—117.0%;在0.02—0.24 mg·L-1加标范围内,Cr(Ⅵ)的加标回收率在96.0%—104.5%.     

气相色谱质谱法测定土壤中的阿特拉津

建立了索氏提取、弗洛里硅土固相柱净化,质谱法测定土壤中的阿特拉津,考察了进样口分流模式、柱升温程序、索氏提取时间对测定的影响,确定了最佳测定条件:无分流进样;流速:1.0 mL·min-1;柱升温程序:100℃(1 min),10℃.min-1到250℃(3 min);离子源温度:250℃;索氏提取:4 h.方法的线性范围良好,相关系数为0.9997,线性范围:5.0—100.0μg.kg-1,方法检出限(S/N=3)为0.38μg.kg-1,相对标准偏差1.1%,平均回收率100.1%.     

水体与底泥中有机氯和除草剂农药残留的气相色谱串联质谱同步测定方法

本研究建立了水体和底泥中8种有机氯农药和5种除草剂的气相色谱-串联质谱(GC-MS/MS)同步测定分析方法.水样以甲醇作为基体改进剂,利用官能化聚苯乙烯/二乙烯苯(PEP)固相萃取柱富集和净化;底泥样品加乙腈用超声波辅助提取,二氯甲烷反萃取,使用氟罗里硅土固相萃取柱净化.采用DB-5MS(30 m×0.25 mm×0.25μm)色谱柱对待测物进行分离,多反应监测模式(MRM)测定.方法的线性相关性均大于0.999.空白水样在低、中、高等3个加标水平下的平均回收率为71%—115%,相对标准偏差(RSD)为4.0%—12.6%,检出限(LOD)0.12—2.0 ng·L~(-1).底泥样品在低、中、高等3个加标水平下,平均回收率为73%—120%,RSD为4.1%—11.0%,检出限(LOD)0.011—0.20μg·kg~(-1).该方法选择性好、灵敏度高且准确可靠,适合于水体和底泥中常见有机氯农药和除草剂类农药的检测.应用该方法测定了东北地区养殖池塘及松花江的水体和底泥样品.结果表明,莠去津检出率最高(100%),水体中残留量在11.2—1671 ng·L~(-1)之间,底泥中残留量在0.35—21.8μg·kg~(-1)之间.有机氯β-六六六检出率80%,水体中残留量在ND—6.76 ng·L~(-1)之间,底泥中残留量在ND—4.74μg·kg~(-1)之间.底泥样品中滴滴涕农药的残留量未超过我国淡水养殖产地环境限量标准.     

高效液相色谱-质谱联用法测定饮用水中的五氯苯酚

建立了高效液相色谱-质谱联用法检测饮用水中五氯苯酚(PCP)。选用ZORBAXXDB-C18柱(50mm×2.1mm,3.5μm)为分析柱,流动相为V(甲醇):V(纯水)=88:12,流量为200μL·min-1;质谱条件选用气动辅助电喷雾离子源(ESI),检测方式为负离子多离子反应检测(MRM);PCP标准曲线线形范围为0.1～100μg·L-1;方法加标回收率达到90%以上;相对标准偏差为2.31%～2.92%(n=5);方法检测低限为0.1μg·L-1。结果表明该方法快速、简便、准确、灵敏、特异,适用于饮用水中PCP残留的测定。     

固相萃取-液相色谱/串联质谱法测定食品中噻酮磺隆的残留

建立了食品中噻酮磺隆残留的高效液相色谱-串联质谱分析方法.样品采用乙腈提取,C18固相萃取柱净化,经Hypersil GOLD C18色谱柱(150 mm×4.6 mm,5μm)分离,电喷雾串联四极杆质谱多反应离子监测方式测定.结果表明,噻酮磺隆在0.5—50 ng·m L-1范围内线性关系良好,相关系数均大于0.999.在5、10、50μg·kg-1加标水平下,平均加标回收率为73.4%—114.6%,相对标准偏差为4.38%—11.09%.该方法稳定、可靠,可满足食品中噻酮磺隆残留残留的检测与确证.     

UHPLC-MSMS测定环境水中的联苯胺

建立了一种使用超高效液相色谱仪和三重四极杆质谱仪联用(UHPLE-MSMS)测定环境水中联苯胺的方法.该方法为直接进样法,样品经0.22μm滤膜过滤后直接进行定量分析.对联苯胺的线性、仪器精密度、方法检出限(MDL)、定量限(LOQ)和加标回收率进行验证.联苯胺的线性良好,相关系数为0.9999;0.5μg.L-1、2μg.L-1和10μg.L-1标准溶液重复6份测试结果显示,其峰面积和保留时间的相对标准偏差分别在0.10%—0.17%和1.01%—4.87%之间,仪器精密度良好;MDL为0.08μg.L-1;LOQ为0.31μg.L-1;加标回收率为89.9%—103.8%.     

采用超高效液质联用法测定水体中十二烷基硫酸钠

采用离线固相萃取(SPE)对水体样品中的十二烷基硫酸钠进行了富集浓缩,同时,采用超高效液相色谱与质谱联用仪(UHPLC-MS)对样品进行了准确定性与快速分析.结果表明,该方法的线性回归方程为y=752.1x-5.97,相关系数r=0.995,线性范围为0.05—50μg·m L~(-1),方法定量限为0.05μg·m L~(-1).采用该方法对浦东某区域水体3份样品进行了分析,结果显示水体中十二烷基硫酸钠的含量为未检出—0.011μg·m L~(-1)之间,样品基质加标回收率为67.0%—105.0%,RSD值为5.8%.     

离子色谱法同时测定北京市不同区域水体6种阳离子

建立离子色谱法测定不同区域水体Li⁺、Na⁺、NH₄⁺、K⁺、Ca²⁺、Mg²⁺等6种阳离子的方法,以及验证方法在实际应用的可行性.以ICS1000型离子色谱仪配有DionexIonPac CG12A阳离子保护柱(4 mm×50 mm)和CS 12A阳离子分离柱(4 mm×250 mm),CSRS 300型抑制器(4 mm),甲基磺酸为淋洗液,流量为1.0 mL·min^-1,6种阳离子的质量浓度在0.01—0.50 mg·L^-1到5.0—100.0mg·L^-1范围内线性较好,相关系数> 0.9995,方法检出限为0.002—0.020mg·L^-1,与有证标准溶液相对误差-2.50%—4.38%(n=6),不同环境水样加标回收率90.7%—107.5%.利用以上色谱条件分析北京市不同区域地表水阳离子分布特征,结果显示城乡结合部、城区和郊区水体p...     

吸附反应时间对除草剂阿特拉津吸附行为的影响

采用批量动态实验方法,对潮土中阿特拉津吸附特征随吸附反应时间变化进行了研究。结果表明,土壤吸附的阿特拉津量随反应时间的变化符合双曲线函数关系。在50μg·L-1～2000μg·L-1浓度系列下,在48h内,土壤颗粒对阿特拉津的吸附属于快反应,土壤吸附的阿特拉津量随吸附反应时间呈指数上升,为吸附实验结束(168h)时土壤吸附阿特拉津总量的58%到90%。当吸附反应时间超过48h后,随反应时间增加,土壤吸附阿特拉津量差异变化不显著。阿特拉津在潮土颗粒和土壤溶液中的相分配可用Freundlich方程描述。吸附容量因子Kf与吸附反应时间之间有极显著的线性正关系(r2=0.9063**,p<0.0001)。无量纲的非线性因子n与吸附反应时间之间也具有显著的线性负关系(r2=0.5666*,p=0.0192)。     

离子色谱-质谱联用测定瓶装水中的高氯酸盐和溴酸盐

以高容量、强亲水性的IonPac AS20(2mm)为分析柱,ESI-MS-MS串联质谱为检测器,同时测定瓶装水中的高氯酸盐和溴酸盐.该方法对高氯酸盐和溴酸盐的检出限(S/N=3)分别为0.01μg·l-1和0.1μg·l-1,线性相关系数分别是r＝0.9990(0.05-100μg·l-1)和r＝0.9998(0.5-100μg·l-1).对某样品连续进样7次,高氯酸盐和溴酸盐的相对标准偏差(RSD)分别为1.2%和0.9%.运用该方法测定瓶装水,并加标回收,高氯酸盐和溴酸盐的加标回收率分别在101.0%-116.5%之间和87.5%-118.9%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.     

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     

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).