南京市城郊蔬菜生产基地有机氯农药残留特征

以网格法在南京市无公害蔬菜生产基地八卦洲采集70个土壤样品,用加速溶剂萃取、固相萃取柱净化后GC-μECD测定土壤中有机氯农药(α-HCH,β-HCH,γ-HCH和δ-HCH以及o,p'-DDT,p,p'-DDT,o,p'-DDE,p,p'-DDE 和p,p'-DDD)残留量.结果表明,土壤中有机氯农药残留总量在6.18～84.72 μg·kg-1之间,平均18.63 μg·kg-1.DDT残留量高于HCH,为3.36～74.19 μg·kg-1,平均12.61 μg·kg-1.土壤中HCH残留量为2.48～17.80 μg·kg-1,平均6.02 μg·kg-1.DDT同系物中以p,p'-DDE和p,p'-DDT为主,而HCH中δ-HCH含量较低,其他3种异构体含量水平相当.所有土样中DDT和HCH残留量均远远低于GB/T 18407 无公害蔬菜产地土壤标准限定值500 μg·kg-1,但大多数土样中DDT和HCH残留量远远高于荷兰无污染土壤标准.     

3种典型有机氯农药对锦鲤幼鱼的雌激素效应及其体内富集

为研究3种典型有机氯农药(%-六六六、p,p'-DDT和七氯)低浓度暴露对锦鲤幼鱼的雌激素效应及其体内富集效应,将锦鲤幼鱼暴露于有机氯农药的6个浓度组中进行20 d慢性毒性试验,测量血清中游离钙和蛋白结合磷含量及体内各组织有机氯农药残留。结果表明,在低浓度暴露20 d后,锦鲤幼鱼血清中游离钙和蛋白结合磷含量均随暴露浓度增加而呈先增后减之势,产生了明显的雌激素效应。p,p'-DDT在鱼体各组织中的富集能力远高于%-六六六和七氯;p,p'-DDT主要在鱼油中富集,其次为鱼肝、鱼鳃和鱼皮;%-六六六和七氯主要在鱼肝中富集,其次为鱼皮、鱼鳃和鱼油;3种有机氯农药在鱼肉中的富集相对较少。     

环鄱阳湖区水稻-土壤有机氯农药污染及健康风险评价

针对环鄱阳湖区水稻和土壤中有机氯农药的污染状况,从环鄱阳湖区11个县市采集水稻及土壤样品,利用GC-ECD对有机氯残留进行测定,并利用健康风险评价模型对该地区水稻中有机氯残留所致风险进行评价.结果表明,环鄱阳湖区水稻及土壤中六六六、滴滴涕、七氯、六氯苯、氯丹均有检出,其中DDTs和HCHs含量较高,土壤中二者平均含量分别为6.25μg·kg~(-1)和10.64μg·kg~(-1),水稻中二者平均含量分别为4.65μg·kg~(-1)和9.16μg·kg~(-1),DDTs和HCHs是主要的有机氯污染物;土壤有机氯的来源主要是由于历史上农药防治害虫的大量使用残留和工业生产带来的新的有机污染源的输入,工农业发达地区有机氯农药残留高于工农业欠发达地区,土壤中有机氯对水稻中p,p'-DDD、p,p'-DDE、o,p'-DDT、β-HCH、γ-HCH、环氧七氯、氯丹等有机氯含量的贡献很大,是水稻中有机氯残留的主要污染来源.健康风险评价结果显示,各类有机氯污染物对人体的健康风险较低,总风险为38.23×10~-(13)a~(-1),属于可接受水平.     

雷州半岛典型区域土壤有机氯农药污染探查研究

在雷州半岛典型区域共采集了74个表层土壤和4个剖面土壤,对土壤中有机氯农药残留及分布状况进行了研究。结果表明:有机氯农药检出率为100%,其中∑HCH(六六六)和∑DDT(滴滴涕)质量分数范围分别在nd～65.93μg·kg-1和0.04～52.00μg·kg-1之间,同国内外同类报道相比处于较低水平;按土壤中有机氯农药17种成分质量分数所占的比重排序,前五名分别为P,P'-DDE、β-HCH、硫丹硫酸盐、硫丹Ⅱ、艾氏剂;按不同利用类型土壤中有机氯残留质量分数由大到小排序为菜地→水田→果园→甘蔗地;有机氯农药残留质量分数随土壤深度的增加呈下降趋势,耕层(0~20cm)的有机氯农药残留质量分数都高于底下层次。     

有机氯农药在太湖水体-沉积物中的交换特征

有机氯农药(OCPs)是一类重要的持久性有机污染物(POPs),具有半挥发性、持久性和高毒性,并能通过食物链富集,危害生态系统和人体健康。有机氯农药可以在不同的环境介质间迁移,并能在大气环境中进行远程输送,导致大范围乃至全球性的环境污染。最近的研究发现太湖地区的有机氯农药含量仍然非常高,为了了解太湖有机氯农药的来源以及环境行为,采用气相色谱质谱法对太湖竺山湾水体和沉积物样品中有机氯农药(OCPs)含量进行了测定,探讨了太湖水体和沉积物中有机氯农药的可能来源以及水体-沉积物之间的交换通量。研究结果表明:沉积物样品中的六氯苯的含量最高,为2.33ng·g-1(干质量,下同),其次为p,p’-DDT、p,p’-DDE和β-HCH,含量分别为0.67、0.64和0.37 ng·g-1。从水体中OCPs的组成来看,p,p’-DDT的含量最高为426.26 pg·L-1,其次是α-HCH和硫丹Ⅰ,含量分别为289.99和215.20 pg·L-1。采用α-HCH/γ-HCH比值对HCHs的来源进行分析,发现太湖水体中的γ-HCH污染来源于工业品六六六和林丹的使用,由交换模型得出HCHs的净交换通量为释放通量,表明HCHs的迁移方向是由沉积物到水中,沉积物的释放已成为太湖水体中HCHs的主要来源之一。水体中的p,p’-DDT/p,p’-DDE比值远大于1,而且由交换模型得出p,p’-DDT的净交换通量为沉降通量,说明了近期可能有新的污染源的输入。值得注意的是,硫丹Ⅰ的净交换通量同样为沉降通量,反映出太湖水体中硫丹Ⅰ可能存在新源的输入。     

辽东半岛海域鱼贝中有机氯农药残留及其风险评估

2011年1月-2012年5月间采集了辽东半岛海域11种鱼类和2种贝类样品,分析了其可食部位中22种有机氯农药的残留量,评估了其中DDTs和HCHs的残留对人体健康的风险。在所调查样品中HCB、HCHs和DDTs是主要的污染物,样品中OCPs残留量为57.12~546.15μg·kg-1。利用污染指数计算法评估,旅顺海域小黄鱼、鳙鱼、中国斗鱼和偏口鱼未受到HCHs的污染,棒花鱼受到HCHs轻度污染,其它鱼种样品均受到重度污染,而对于DDTs,只有鲫鱼未受到污染,其它鱼种样品均受到重度污染。大黄鱼、梭鱼、黑鱼和鳙鱼体内HCHs残留量明显高于国标再残留限值,DDTs残留量符合国标标准。α-HCH、γ-HCH、β-HCH、p,p'-DDE、p,p'-DDD和p,p'-DDT的致癌风险指数范围为0.32×10-6~49.57×10-6,均低于10-4,为可接受的致癌风险;α-HCH、γ-HCH、β-HCH、p,p'-DDE的接触风险指数ERI为0.01×10-3~153.28×10-3,均小于1,为可接受的接触风险,但2012年4月的黑鱼样品上述六种农药的CRI总值高于10-4,存在潜在的致癌风险,因此,建议黑鱼的日均食用量应控制在50 g以下较为安全。     

污灌水稻土有机氯农药残留分析的样品净化

研究了不同样品净化方法和方法组合在长年污灌的水稻土有机氯农药残留分析中的效果 .采取高纯铜粉净化、浓硫酸磺化、 1 0 %脱活氟罗里硅土层析等一系列净化步骤 .用该方法测定α BHC ,β BHC ,γ BHC ,δ BHC ,p,p DDE ,p,p DDD ,o,p DDT ,p,p DDT等 8种有机氯农药的回收率达 4 2 5 %— 84 8% ,检出限为 3 2 1× 1 0 - 6— 1 34× 1 0 - 5μg·ml- 1.且方法的重现性较好 .     

珠江三角洲典型区域蔬菜地土壤中有机氯农药的污染特征——以东莞市为例

近年来珠江三角洲经济迅速发展的同时所带来的土壤有机氯农药污染问题备受关注,着重调查研究了东莞蔬菜地土壤中17种有机氯农药的污染特征.2002年10-12月采集蔬菜地土壤样品37个,利用气相色谱分析有机氯农药的含量.研究结果表明,东莞蔬菜地土壤样品中均检出有机氯,其中DDE与艾氏剂的检出率为100.0%;17种有机氯农药总含量(∑17OCPs)范围为2.47～82.23 ng·g-1,均值为22.53 ng·g-1.含有7个Cl取代基的有机氯农药即七氯与环氧七氯的含量均显著低于其他有机氯农药的含量;尽管东莞市蔬菜地土壤中DDTs的含量明显低于省内外其他地区蔬菜地土壤DDTs含量,但东莞蔬菜地土壤中有机氯农药主要以毒性较强的六氯代有机化合物为主,因此东莞蔬菜地土壤中有机氯农药污染状况不容忽视.     

珠江三角洲地区大气中有机氯农药的被动采样观测

利用PUF被动采样装置,对珠江三角洲地区大气中有机氯农药(OCPs)进行监测.结果显示,广东省大气中有机氯农药主要是滴滴涕(DDTs)、六六六(HCH)及氯丹(Chlordane),其中DDTs约占总OCPs的54.5%;香港大气中农药残留主要是氯丹和DDTs,氯丹约占总含量的51.3%.珠三角地区大气中有机氯农药空间分布差异明显(580-5500pg·m-3),香港平均浓度远远低于广东省.另外,广东省仍有工业DDT在使用,造成广东省大气中有"新"的工业DDT输入;而三氯杀螨醇是香港大气中DDT高含量的重要来源;广东省和香港HCH主要源于林丹使用的残留,香港的Eastern及Tsuen Wan源于工业六六六使用的残留;珠江三角洲所有采样点的HCB含量较低,大气中HCB少量残留可能是HCB作为药物中间体的化学合成及HCB在大气中长距离传输的结果.     

太原市污灌区地表土中有机氯农药分布特征

为了研究太原市污灌区地表土中有机氯农药(OCPs)分布特征,本文在太原小店区共采集了31个地表土样,应用气相色谱-电子捕获检测器(GC-ECD)检测土壤中OCPs的含量.结果表明,研究区地表土中OCPs污染较轻,总OCPs浓度范围为2.01—47.20 ng.g-1(平均值为16.76 ng.g-1).其中总滴滴涕(∑DDT)浓度范围为0.27—37.93 ng.g-1(平均值为8.38 ng.g-1),总六六六(∑HCH)浓度范围为0.18—11.89 ng.g-1(平均值为3.37 ng.g-1),最高浓度均没有超过《土壤环境质量标准》(GB15618—1995)中的Ⅱ级标准(农业土地).不同灌溉区OCPs浓度平均值顺序为:污灌区>清灌区>背景点,表明污水回灌对OCPs浓度分布具有一定的影响,同时通过比较各采样点中OCPs各异构体的组成发现,该区域HCHs、DDTs和硫丹农药主要来自于历史残留,部分区域曾使用林丹和三氯杀螨醇农药.对比各有机氯农药浓度地理分布特征,表明OCPs浓度分布与污水灌溉存在一定的联系.     

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.     

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     

Potential for Electropositive Metal to Reduce the Interactions of Atlantic Sturgeon with Fishing Gear

Atlantic sturgeon (Acipenser oxyrhynchus) populations have been declared either endangered or threatened under the U.S. Endangered Species Act. Effective measures to repel sturgeon from fishing gear would be beneficial to both fish and fishers because they could reduce both fishery‐associated mortality and the need for seasonal and area closures of specific fisheries. Some chondrostean fishes (e.g., sturgeons and paddlefishes) can detect weak electric field gradients (possibly as low as 5 Μv/cm) due to arrays of electroreceptors (ampullae of Lorenzini) on their snout and gill covers. Weak electric fields, such as those produced by electropositive metals (typically mixtures of the lanthanide elements), could therefore potentially be used as a deterrent. To test this idea, we recorded the behavioral responses of juvenile Atlantic sturgeon (31–43 cm fork length) to electropositive metal (primarily a mixture of the lanthanide elements neodymium and praseodymium) both in the presence and absence of food stimuli. Trials were conducted in an approximately 2.5 m diameter × 0.3 m deep tank, and fish behaviors were recorded with an overhead digital video camera. Video records were subsequently digitized (x, y coordinate system), the distance between the fish and the electropositive metal calculated, and data summarized by compiling frequency distributions with 5‐cm bins. Juvenile sturgeon showed clear avoidance of electropositive metal but only when food was present. On the basis of our results, we conclude that the electropositive metals, or other sources of weak electric fields, may eventually be used to reduce the interactions of Atlantic sturgeon with fishing gear, but further investigation is needed. El Potencial del Metal Electropositivo para Reducir las Interacciones del Esturión Atlántico con Instrumentos de Pesca Bouyoucos, Bushnell & Brill 13–003     

The role of time and species identities in spatial patterns of species richness and conservation

Many conservation actions are justified on the basis of managing biodiversity. Biodiversity, in terms of species richness, is largely the product of rare species. This is problematic because the intensity of sampling needed to characterize communities and patterns of rarity or to justify the use of surrogates has biased sampling in favor of space over time. However, environmental fluctuations interacting with community dynamics lead to temporal variations in where and when species occur, potentially affecting conservation planning by generating uncertainty about results of species distribution modeling (including range determinations), selection of surrogates for biodiversity, and the proportion of biodiversity composed of rare species. To have confidence in the evidence base for conservation actions, one must consider whether temporal replication is necessary to produce broad inferences. Using approximately 20 years of macrofaunal data from tidal flats in 2 harbors, we explored variation in the identity of rare, common, restricted range, and widespread species over time and space. Over time, rare taxa were more likely to increase in abundance or occurrence than to remain rare or disappear and to exhibit temporal patterns in their occurrence. Space–time congruency in ranges (i.e., spatially widespread taxa were also temporally widespread) was observed only where samples were collected across an environmental gradient. Fifteen percent of the taxa in both harbors changed over time from having spatially restricted ranges to having widespread ranges. Our findings suggest that rare species can provide stability against environmental change, because the majority of species were not random transients, but that selection of biodiversity surrogates requires temporal validation. Rarity needs to be considered both spatially and temporally, as species that occur randomly over time are likely to play a different role in ecosystem functioning than those exhibiting temporal structure (e.g., seasonality). Moreover, temporal structure offers the opportunity to place management and conservation activities within windows of maximum opportunity.     

Main nutrient compounds in food bodies of Mexican <Emphasis Type="Italic">Acacia</Emphasis> ant-plants

Summary. Myrmecophytic plants use obligate ant mutualists as a constitutive indirect defence mechanism. These plants often produce cellular food bodies (FBs) to nourish their resident ants. Lipids, proteins, and even highly specialised compounds such as glycogen have been reported from FBs, but detailed chemical analyses of FB composition have so far been presented only for Southeast Asian Macaranga and Central American Piper myrmecophytes. Here we report the chemical composition of FBs of five myrmecophytic Acacia (Fabaceae) species from Mexico using HPLC (carbohydrates and proteins) and GC-MS (lipids). Feeding experiments revealed no hints on any use of external food sources by the inhabiting Pseudomyrmex ants. These ants obviously rely completely on FBs and extrafloral nectar provided by their hosts. The total content of nutrients in Acacia FBs was 15-25% of FB dry mass, being much lower than in Macaranga or Piper FBs. Proteins were dominating (8-14 % dm) in Acacia FBs and thus were present in higher amounts than in Macaranga FBs, yet in lower amounts than in Piper. Lipids contributed 1-9 % of dry mass, showing a lower proportion than in FBs of Macaranga or Piper. Carbohydrates made up 3-11 % dm, reaching in most Acacia species the same range as observed in Macaranga and in Piper FBs. Water content was 18-24 % of FB fresh mass, and structural tissue obviously made up a much higher proportion in Acacia FBs than in Macaranga or Piper FBs. Both characters might represent an adaptation to producing FBs unprotected at the leaf tips under dry conditions. Acacia FBs contain all amino acids and all fatty acids that are considered essential for insects, and their contents of lipids and proteins are higher than in the leaves from which they are ontogenetically derived. This indicates a putatively adaptive enrichment of nutritionally valuable compounds in structures functioning as ant-food.     

Examining the uncertain origin and management role of martens on Prince of Wales Island,Alaska

Conservation biologists are generally united in efforts to curtail the spread of non‐native species globally. However, the colonization history of a species is not always certain, and whether a species is considered non‐native or native depends on the conservation benchmark. Such ambiguities have led to inconsistent management. Within the Tongass National Forest of Alaska, the status of American marten (Martes americana) on the largest, most biologically diverse and deforested island, Prince of Wales (POW), is unclear. Ten martens were released to POW in the early 1930s, and it was generally believed to be the founding event, although this has been questioned. The uncertainty surrounding when and how martens colonized POW complicates management, especially because martens were selected as a design species for the Tongass. To explore the history of martens of POW we reviewed other plausible routes of colonization; genetically and isotopically analyzed putative marten fossils deposited in the late Pleistocene and early Holocene to verify marten occupancy of POW; and used contemporary genetic data from martens on POW and the mainland in coalescent simulations to identify the probable source of the present‐day marten population on POW. We found evidence for multiple routes of colonization by forest‐associated mammals beginning in the Holocene, which were likely used by American martens to naturally colonize POW. Although we cannot rule out human‐assisted movement of martens by Alaskan Natives or fur trappers, we suggest that martens be managed for persistence on POW. More generally, our findings illustrate the difficulty of labeling species as non‐native or native, even when genetic and paleo‐ecological data are available, and support the notion that community resilience or species invasiveness should be prioritized when making management decisions rather than more subjective and less certain conservation benchmarks.