Dugesia lugubris undD. polychroa im Zürichsee (Turbellaria: Tricladida)     

Annette Barkhausen  Jakob E. Walter 《Aquatic Sciences - Research Across Boundaries》1979,41(1):108-112

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Light-induced conversion of refractory,high molecular weight lake water constituents   总被引：4，自引：0，他引：4  

Dr. Annette Geller 《Aquatic Sciences - Research Across Boundaries》1985,47(1):21-26

High molecular weight DOM (apparent mol wt. ≥1500) was isolated from lake water, both in summer and in winter. Sephadex G-15 gel permeation chromatography with 0.02 M phosphate buffer yielded one peak. Elution with distilled water gave rise to distinct smaller sized subfractions. It was concluded that these compounds are weakly bound subunits of the macromolecules, which are liberated on elution with distilled water. The macromolecules were not stable in the dark. Exposing them to daylight in the laboratory and to sunlight, in quartz bottles enhanced conversion. During 6 weeks' exposure to weakly photolytic conditions (daylight >300 nm), organic carbon of the high molecular bulk substances decreased by 15% (winter) and by 25% (summer), while the concentrations of the apparent low molecular weight substances increased accordingly. Such a slow but continuous transformation may reduce also the <in situ> persistence of the macromolecules gradually.  相似文献   

Climate Change,Bushfire Risk,and Environmental Values: Examining a Potential Risk Perception Threshold in Peri-Urban South Australia     

Douglas K. Bardsley  Emily Moskwa  Delene Weber  Guy M. Robinson  Nicolette Waschl  Annette M. Bardsley 《社会与自然资源》2018,31(4):424-441

Striking a balance between the management of environmental risks and values is a challenge for decision-makers. If people perceive that environmental risks are increasing they may be willing to discount local values to manage those risks, so the identification of thresholds in risk perception in relation to specific behaviors could help to avoid policy failures. The complex relationships between perceptions of climate change and bushfire risks, environmental values and support for actions to mitigate local risks are presented for peri-urban regions in South Australia. The results of a household survey (N=988) suggest that a threshold of risk perception in relation to climate change and bushfire management has not been exceeded and people are broadly supportive of balanced management interventions. A minority of people still do not perceive that climate change is increasing bushfire risk, and are supportive of risk mitigation interventions even at the expense of local biodiversity. However, a larger group believe that climate change is a driver of bushfire risk, yet are still more likely to prioritize ecological values and are unwilling to discount those values for risk mitigation. Targeted communication could assist different groups to respond to gaps in knowledge and action to facilitate effective, differentiated interventions within forested landscapes on the margins of urban areas.  相似文献   

Outcrop analogue study of Permocarboniferous geothermal sandstone reservoir formations (northern Upper Rhine Graben,Germany): impact of mineral content,depositional environment and diagenesis on petrophysical properties     

Achim Aretz  Kristian Bär  Annette E. Götz  Ingo Sass 《International Journal of Earth Sciences》2016,105(5):1431-1452

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Combined effects of ethanol and cinnamaldehyde in the Japanese medaka embryo-larval assay (MELA)     

Haasch ML  Ford AW 《Marine environmental research》2004,58(2-5):175-179

The Japanese medaka (Oryzias latipes) was used in the medaka embryo-larval assay (MELA) to determine possible adverse developmental effects of ethanol and the spice component, cinnamaldehyde (CAD). Fish may be exposed to waterborne ethanol and a variety of natural products from non-point sources or leaks during ethanol use as a fuel and from point source processing plant effluents. Consumption of ethanol during human pregnancy is known to cause fetal alcohol syndrome (FAS), a collection of birth defects including craniofacial abnormalities thought to be caused by the generation of free radicals during ethanol metabolism by both alcohol and aldehyde dehydrogenase(s). Fish are also susceptible to FAS (Dasmahapatra et al., meeting abstract). The activity of aldehyde dehydrogenase is inhibited by CAD [Biochem. J. 282 (1992) 353-360; Biochem. Pharmacol. 45 (1993) 1621-1630], and CAD is known to cause developmental abnormalities in the rat [Food Chem. Toxicol. 27 (1989) 781-786]. Therefore, the combined effects of treatment with both ethanol and CAD would be expected to produce additive or greater than additive effects in the MELA assay. Medaka were exposed to ethanol at 100 mM, CAD at 10, 1.0, 0.67 or 0.50 mM, to ethanol and CAD combined, or were non-treated controls. Ethanol at 100 mM was without effect. CAD alone at 10 mM and 1.0 mM was lethal by 1 dpf. Embryos exposed to 100 mM ethanol and 0.67 mM CAD exhibited cardiovascular and pigmentation defects and delayed hatching. Embryos exposed to 0.50 mM CAD alone had less severe cardiovascular problems as compared to the combined ethanol and CAD treatment. Taken together the results indicate that the combined effects of ethanol and CAD are greater than the individual effects and indicate the need to monitor effluents in fish nursery areas to protect natural fish populations. Supported by PHS/NIH ES07929.  相似文献   

Estimation of spawning habitats of market squid (Doryteuthis opalescens) from field surveys of eggs off Central and Southern California     

Louis D. Zeidberg  John L. Butler  Darlene Ramon  Anthony Cossio  Kevin L. Stierhoff  Annette Henry 《Marine Ecology》2012,33(3):326-336

Like many other loliginid squid, Doryteuthis (Loligo) opalescens deposits egg cases on the ocean floor. Depending upon temperature, egg cases may persist for 5–12 weeks before the paralarvae hatch. Because of this relatively long duration and squid’s pelagic life history, egg cases provide a practical life stage to survey. During 2001–2002, squid egg beds in Monterey Bay, Carmel Bay, and around the California Channel Islands were surveyed using a remotely operated vehicle with the goal of delineating the habitat of egg beds that are spawned during active commercial fishing. Egg cases were highly aggregated and densities reached 1338 capsules m⁻². Squid eggs were significantly shallower in Central California. Egg cases occurred between 20 and 93 m around the Channel Islands, and in Central California they were between 13 and 61 m. The temperatures in both regions were similar (10–12 °C), with some eggs in Southern California found up to 14.4 °C. Ninety-five percent of eggs were found on sand, suggesting that temperature and substrate are stronger behavioral cues than depth to stimulate spawning. Suitable spawning habitat was defined by three criteria: sandy benthic substrate, temperatures between 10 and 14.4 °C, and depths between 20 and 70 m when the first two criteria hold. Additionally, within this defined area, oxygen concentration is quantified. The greatest commercial landings of market squid occur in both Central and Southern California during a time of year when water temperatures of 10–12 °C are prevalent in the 20–70 m depth range.  相似文献   

Analysis of historical landslide time series in the Emilia‐Romagna region,northern Italy     

Mauro Rossi  Annette Witt  Fausto Guzzetti  Bruce D. Malamud  Silvia Peruccacci 《地球表面变化过程与地形》2010,35(10):1123-1137

A catalogue of historical landslides, 1951–2002, for three provinces in the Emilia‐Romagna region of northern Italy is presented and its statistical properties studied. The catalogue consists of 2255 reported landslides and is based on historical archives and chronicles. We use two measures for the intensity of landsliding over time: (i) the number of reported landslides in a day (D_L) and (ii) the number of reported landslides in an event (S_event), where an event is one or more consecutive days with landsliding. From 1951–2002 in our study area there were 1057 days with 1 ≤ D_L ≤?45 landslides per day, and 596 events with 1 ≤ S_event ≤ 129 landslides per event. In the first set of analyses, we find that the probability density of landslide intensities in the time series are power‐law distributed over at least two‐orders of magnitude, with exponent of about ?2·0. Although our data is a proxy for landsliding built from newspaper reports, it is the first tentative evidence that the frequency‐size of triggered landslide events over time (not just the landslides in a given triggered event), like earthquakes, scale as a power‐law or other heavy‐tailed distributions. If confirmed, this could have important implications for risk assessment and erosion modelling in a given area. In our second set of analyses, we find that for short antecedent rainfall periods, the minimum amount of rainfall necessary to trigger landslides varies considerably with the intensity of the landsliding (D_L and S_event); whereas for long antecedent periods the magnitude is largely independent of the cumulative amount of rainfall, and the largest values of landslide intensity are always preceded by abundant rainfall. Further, the analysis of the rainfall trend suggests that the trigger of landslides in the study area is related to seasonal rainfall. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Quantitative relationship between water-depth and sub-fossil ostracod assemblages in Lake Donggi Cona,Qinghai Province,China     

Steffen Mischke  Ulrich Bößneck  Bernhard Diekmann  Ulrike Herzschuh  Huijun Jin  Annette Kramer  Bernd Wünnemann  Chengjun Zhang 《Journal of Paleolimnology》2010,43(3):589-608

A calibration data set of 51 surface sediment samples from Lake Donggi Cona on the northeastern Tibetan Plateau was investigated to study the relationship between sub-fossil ostracod assemblages and water depth. Samples were collected over a depth range from 0.6 to 80 m. A total of 16 ostracod species was identified from the lake with about half of the species restricted to the Tibetan Plateau and its adjacent mountain ranges and poorly known in terms of ecological preferences, and the other half displaying a mainly Holarctic distribution. Living macrophytes and macroalgae were recorded in Lake Donggi Cona down to a depth of about 30 m, and bivalve (Pisidium cf. zugmayeri) and gastropod (Gyraulus, Radix) shells were found down to depths of 43 and 48 m, respectively. The ostracod-water-depth relationship was assessed by multivariate statistical analysis and ostracod-based transfer functions for water depth were constructed. Weighted averaging partial least squares (WA-PLS) regression provided the best model with a coefficient of determination r ² of 0.91 between measured and ostracod-inferred water depth, a root mean square error of prediction of 8% and a maximum bias of 10.6% of the gradient length, as assessed by leave-one-out cross-validation. Our results show the potential of ostracods as palaeo-depth indicators in appropriate settings. However, transfer-function applications using fossil ostracod assemblages for palaeo-depth estimations require a thorough understanding of the palaeolimnological conditions of lakes and therefore detailed multi-proxy analysis to avoid misinterpretation of ostracod-based inferences.  相似文献   

Sporadic hotspots for physico-chemical retention of aquatic organic carbon: from peatland headwater source to sea     

Sheila M. Palmer  Chris D. Evans  Pippa J. Chapman  Annette Burden  Tim G. Jones  Tim E. H. Allott  Martin G. Evans  Catherine S. Moody  Fred Worrall  Joseph Holden 《Aquatic Sciences - Research Across Boundaries》2016,78(3):491-504

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Science and User Needs for Observing Global Mass Transport to Understand Global Change and to Benefit Society     

Roland Pail  Rory Bingham  Carla Braitenberg  Henryk Dobslaw  Annette Eicker  Andreas Güntner  Martin Horwath  Eric Ivins  Laurent Longuevergne  Isabelle Panet  Bert Wouters  IUGG Expert Panel 《Surveys in Geophysics》2015,36(6):743-772

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