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961.
目前对镍(Ni)生态风险评估和水质法规采用了基于机制的预测工具,如生物配体模型(BLMs)。然而,尽管有许多具体细致的研究,Ni对水生生物毒性的精确机制仍然难以确定。对Ni行为机制的不确定性导致了大家在一些管理设置中应用像BLM这样的工具时,有所顾虑。为了解决这一认知差距,作者使用了有害结局路径(AOP)分析,也是第一个用于金属的AOP分析,来确定Ni毒性的多种潜在机制以及它们与淡水水生生物的相互作用。在金属的分子起始事件(molecular initiating events)在分类群中可能存在的前提下,在许多不同种水生和陆生生物数据的基础上,考虑建立一种潜在的行为机制。通过分析,作者识别了Ni可能对水生生物产生毒性的5个潜在的分子起始事件:Ca2+体内平衡的破坏,Mg2+体内平衡的破坏,Fe2+/3+体内平衡的破坏,活性氧类物质引起的氧化损伤,以及呼吸上皮细胞的过敏反应。在生物组织的器官水平,这5个潜在的分子起始事件会分解成3个可能的途径:支持外骨骼、外壳和骨骼生长的Ca2+减少;呼吸受损;细胞毒性和肿瘤形成。在整个生物体的水平,器官水平的反应将可能导致生长、繁殖的降低和/或能量代谢的改变,并且在每个通路之间有几个潜在的反馈回路。总体来说,目前的AOP分析可指导Ni的毒性机制研究,并为其他金属开发AOPs提供了有效的参考。
精选自Brix, K. V., Schlekat, C. E. and Garman, E. R. (2017), The mechanisms of nickel toxicity in aquatic environments: An adverse outcome pathway analysis. Environmental Toxicology and Chemistry, 36: 1128–1137. doi: 10.1002/etc.3706
详情请见http://onlinelibrary.wiley.com/wol1/doi/10.1002/etc.3706/full 相似文献
962.
Kayhanian M Anderson D Harvey JT Jones D Muhunthan B 《Journal of environmental management》2012,95(1):114-123
This paper describes a study that used permeability measurement along with physical and hydrological characteristics of 20 pervious concrete pavements in parking lots throughout California. The permeability was measured at five locations: the main entrance, an area with no traffic, and three separate measurements within a parking space at each parking lot. Hydrological and physical site characteristics such as traffic flow, erosion, vegetation cover, sediments accumulation, maintenance practice, presence of cracking, rainfall, and temperature data were also collected for each parking lot. These data were used to perform detailed statistical analysis to determine factors influencing changes in permeability and hence assessing possible cause of clogging. In addition, seven representative core samples were obtained from four different parking lots with permeability ranging from very low to very high. Porosity profiles produced from CT scanning were used to assess the possible nature and extent of clogging. Results showed that there is a large variation in permeability within each parking lot and between different parking lots. In general, the age of the parking lot is the predominant factor influencing the permeability. Statistical analysis revealed that fine sediment (particles less than 38 μm) mass is also an important influencing factor. Other influencing factors with lower significance included number of days with a temperature greater than 30°C and the amount of vegetation next to the parking lot. The combined scanned image analysis and porosity profile of the cores showed that most clogging occurs near the surface of the pavement. While lower porosity generally appeared to be limited to the upper 25 mm, in some core samples evidence of lower porosity was found up to 100mm below the surface. 相似文献
963.
Gwynn-Jones D Jones AG Waterhouse A Winters A Comont D Scullion J Gardias R Graee BJ Lee JA Callaghan TV 《Ambio》2012,41(Z3):256-268
This study investigated the effects of long-term-enhanced UV-B, and combined UV-B with elevated CO(2) on dwarf shrub berry characteristics in a sub-arctic heath community. Germination of Vaccinium myrtillus was enhanced in seeds produced at elevated UV-B, but seed numbers and berry size were unaffected. Elevated UV-B and CO(2) stimulated the abundance of V. myrtillus berries, whilst UV-B alone stimulated the berry abundance of V. vitis-idaea and Empetrum hermaphroditum. Enhanced UV-B reduced concentrations of several polyphenolics in V. myrtillus berries, whilst elevated CO(2) increased quercetin glycosides in V. myrtillus, and syringetin glycosides and anthocyanins in E. hermaphroditum berries. UV-B?×?CO(2) interactions were found for total anthocyanins, delphinidin-3-hexoside and peonidin-3-pentosidein in V. myrtillus berries but not E. hermaphroditum. Results suggest positive impacts of UV-B on the germination of V. myrtillus and species-specific impacts of UV-B?×?elevated CO(2) on berry abundance and quality. The findings have relevance and implications for human and animal consumers plus seed dispersal and seedling establishment. 相似文献
964.
Bednar AJ Russell AL Hayes CA Jones WT Tackett P Splichal DE Georgian T Parker LV Kirgan RA MacMillan DK 《Chemosphere》2012,87(8):894-901
The use of munitions constituents (MCs) at military installations can produce soil and groundwater contamination that requires periodic monitoring even after training or manufacturing activities have ceased. Traditional groundwater monitoring methods require large volumes of aqueous samples (e.g., 2-4 L) to be shipped under chain of custody, to fixed laboratories for analysis. The samples must also be packed on ice and shielded from light to minimize degradation that may occur during transport and storage. The laboratory’s turn-around time for sample analysis and reporting can be as long as 45 d. This process hinders the reporting of data to customers in a timely manner; yields data that are not necessarily representative of current site conditions owing to the lag time between sample collection and reporting; and incurs significant shipping costs for samples.The current work compares a field portable Gas Chromatograph-Mass Spectrometer (GC-MS) for analysis of MCs on-site with traditional laboratory-based analysis using High Performance Liquid Chromatography with UV absorption detection. The field method provides near real-time (within ∼1 h of sampling) concentrations of MCs in groundwater samples. Mass spectrometry provides reliable confirmation of MCs and a means to identify unknown compounds that are potential false positives for methods with UV and other non-selective detectors. 相似文献
965.
Tidal streams are ecologically important components of lotic network, and we identify dissolved oxygen (DO) depletion as a potentially important stressor in freshwater tidal streams of northern New Zealand. Other studies have examined temporal DO variability within rivers and we build on this by examining variability between streams as a basis for regional-scale predictors of risk for DO stress. Diel DO variability in these streams was driven by: (1) photosynthesis by aquatic plants and community respiration which produced DO maxima in the afternoon and minima early morning (range, 0.6-4.7 g/m(3)) as a product of the solar cycle and (2) tidal variability as a product of the lunar cycle, including saline intrusions with variable DO concentrations plus a small residual effect on freshwater DO for low-velocity streams. The lowest DO concentrations were observed during March (early autumn) when water temperatures and macrophyte biomass were high. Spatial comparisons indicated that low-gradient tidal streams were at greater risk of DO depletions harmful to aquatic life. Tidal influence was stronger in low-gradient streams, which typically drain more developed catchments, have lower reaeration potential and offer conditions more suitable for aquatic plant proliferation. Combined, these characteristics supported a simple method based on the extent of low-gradient channel for identifying coastal streams at risk of DO depletion. High-risk streams can then be targeted for riparian planting, nutrient limits and water allocation controls to reduce potential ecological stress. 相似文献
966.
Dylan Gwynn-Jones Alan G. Jones Alice Waterhouse Ana Winters David Comont John Scullion Rosie Gardias Bente J. Graee John A. Lee Terry V. Callaghan 《Ambio》2012,41(3):256-268
This study investigated the effects of long-term-enhanced UV-B, and combined UV-B with elevated CO2 on dwarf shrub berry characteristics in a sub-arctic heath community. Germination of Vaccinium myrtillus was enhanced in seeds produced at elevated UV-B, but seed numbers and berry size were unaffected. Elevated UV-B and CO2 stimulated the abundance of V. myrtillus berries, whilst UV-B alone stimulated the berry abundance of V. vitis-idaea and Empetrum hermaphroditum. Enhanced UV-B reduced concentrations of several polyphenolics in V. myrtillus berries, whilst elevated CO2 increased quercetin glycosides in V. myrtillus, and syringetin glycosides and anthocyanins in E. hermaphroditum berries. UV-B × CO2 interactions were found for total anthocyanins, delphinidin-3-hexoside and peonidin-3-pentosidein in V. myrtillus berries but not E. hermaphroditum. Results suggest positive impacts of UV-B on the germination of V. myrtillus and species-specific impacts of UV-B × elevated CO2 on berry abundance and quality. The findings have relevance and implications for human and animal consumers plus seed dispersal and seedling establishment. 相似文献
967.
Sunohara MD Topp E Wilkes G Gottschall N Neumann N Ruecker N Jones TH Edge TA Marti R Lapen DR 《Journal of environmental quality》2012,41(4):1301-1314
This 5-yr study compared, via an upstream-downstream experimental design, nutrient and microbial water quality of an intermittent stream running through a small pasture (~2.5 animals ha) where cattle are restricted from the riparian zone (restricted cattle access [RCA]) and where cattle have unrestricted access to the stream (unrestricted cattle access [URCA]). Fencing in the RCA excluded pasturing cattle to within ~3 to 5 m of the stream. Approximately 88% (26/32) of all comparisons of mean contaminant load reduction for lower, higher, and all stream flow conditions during the 5-yr study indicated net contaminant load reductions in the RCA; for the URCA, this percentage was 38% (12/32). For all flow conditions, mean percent load reductions in the RCA for nutrients and bacteria plus F-coliphage were 24 and 23%, respectively. These respective percentages for the URCA were -9 and -57% (positive values are reductions; negative values are increases). However, potentially as a result of protected wildlife habitat in the RCA, the mean percent load reduction for for "all flow" was -321% for the RCA and 60% for the URCA; for , these respective percentages were -209% (RCA) and 73% (URCA). For "all flow" situations, mean load reductions for the RCA were significantly greater ( < 0.1) than those from the URCA for NH-N, dissolved reactive phosphorus (DRP), total coliform, , and . For "high flow" situations, mean load reductions were significantly greater for the RCA for DRP, total coliform, and . For "low flow" conditions, significantly greater mean load reductions were in favor of the RCA for DRP, total P, total coliforms, fecal coliforms, , and . In no case were mean pollutant loads in the URCA significantly higher than RCA pollutant loads. Restricting pasturing livestock to within 3 to 5 m of intermittent streams can improve water quality; however, water quality impairment can occur if livestock have unrestricted access to a stream. 相似文献
968.
Parvulastra exigua, a species that lacks a dispersive larva, is paradoxically one of the most widely distributed and abundant sea stars in Australia.
The potential that self-fertilization and successful development of self-generated progeny might contribute to population
maintenance in this species was investigated through induction of spawning in isolated individuals collected from five populations
near Sydney, New South Wales (34°S, 151°E), during the spawning period (August–October 2010, 2011). Evidence of selfing differed
significantly among the five populations but the level of selfing within individual egg masses did not. Overall, there was
a mean of 8.9% fertilization in egg masses with embryos. Some clutches developed to the juvenile stage while others arrested
development before hatching. The presence of miniscule testis tissue in gonads that appeared to be ovaries indicated that
hermaphroditism may be more common in some populations than indicated by anatomy. Mixed mating (selfing + outcrossing), pseudocopulation
during egg laying and developmental success of self-fertilized embryos may contribute to the ecological success of P. exigua. These might influence population genetic structure and would facilitate establishment of founder populations by a small
number of migrants. 相似文献
969.
970.
Diagnosing the processes that threaten species persistence is critical for recovery planning and risk forecasting. Dominant threats are typically inferred by experts on the basis of a patchwork of informal methods. Transparent, quantitative diagnostic tools would contribute much‐needed consistency, objectivity, and rigor to the process of diagnosing anthropogenic threats. Long‐term census records, available for an increasingly large and diverse set of taxa, may exhibit characteristic signatures of specific threatening processes and thereby provide information for threat diagnosis. We developed a flexible Bayesian framework for diagnosing threats on the basis of long‐term census records and diverse ancillary sources of information. We tested this framework with simulated data from artificial populations subjected to varying degrees of exploitation and habitat loss and several real‐world abundance time series for which threatening processes are relatively well understood: bluefin tuna (Thunnus maccoyii) and Atlantic cod (Gadus morhua) (exploitation) and Red Grouse (Lagopus lagopus scotica) and Eurasian Skylark (Alauda arvensis) (habitat loss). Our method correctly identified the process driving population decline for over 90% of time series simulated under moderate to severe threat scenarios. Successful identification of threats approached 100% for severe exploitation and habitat loss scenarios. Our method identified threats less successfully when threatening processes were weak and when populations were simultaneously affected by multiple threats. Our method selected the presumed true threat model for all real‐world case studies, although results were somewhat ambiguous in the case of the Eurasian Skylark. In the latter case, incorporation of an ancillary source of information (records of land‐use change) increased the weight assigned to the presumed true model from 70% to 92%, illustrating the value of the proposed framework in bringing diverse sources of information into a common rigorous framework. Ultimately, our framework may greatly assist conservation organizations in documenting threatening processes and planning species recovery. Inferencia la Naturaleza de las Amenazas Antropogénicas para los Registros de Abundancia a Largo Plazo 相似文献