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排序方式: 共有236条查询结果,搜索用时 62 毫秒
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Thomas Mehner Susan Busch Catriona Clemmesen Ingeborg Palm Helland Franz H?lker Jan Ohlberger Myron A. Peck 《Marine Biology》2012,159(11):2583-2603
Systematic comparisons of the ecology between functionally similar fish species from freshwater and marine aquatic systems are surprisingly rare. Here, we discuss commonalities and differences in evolutionary history, population genetics, reproduction and life history, ecological interactions, behavioural ecology and physiological ecology of temperate and Arctic freshwater coregonids (vendace and ciscoes, Coregonus spp.) and marine clupeids (herring, Clupea harengus, and sprat, Sprattus sprattus). We further elucidate potential effects of climate warming on these groups of fish based on the ecological features of coregonids and clupeids documented in the previous parts of the review. These freshwater and marine fishes share a surprisingly high number of similarities. Both groups are relatively short-lived, pelagic planktivorous fishes. The genetic differentiation of local populations is weak and seems to be in part correlated to an astonishing variability of spawning times. The discrete thermal window of each species influences habitat use, diel vertical migrations and supposedly also life history variations. Complex life cycles and preference for cool or cold water make all species vulnerable to the effects of global warming. It is suggested that future research on the functional interdependence between spawning time, life history characteristics, thermal windows and genetic differentiation may profit from a systematic comparison of the patterns found in either coregonids or clupeids. 相似文献
176.
Anna Von Roenne Franz Von Roenne Sarah Kollie Yaya Swaray Egbert Sondorp Matthias Borchert 《Disasters》2010,34(1):16-29
The need to involve refugees in their own reproductive health (RH) services has long been recognised, but there is a lack of published examples describing how this can be achieved collaboratively between refugee initiatives, UNHCR, bilateral development organisations and international relief agencies. This paper outlines the work, outputs and lessons learnt of the Reproductive Health Group (RHG), an organisation of Liberian and Sierra Leonean refugee midwives and laywomen providing RH services to fellow refugees in Guinea's Forest Region between 1996 and 2000. Working as part of the Guinean health system, RHG midwives and community facilitators helped make the RH services in their region the most effective in Guinea at the time. Looking at RHG's achievements, the challenges it faced and partly overcame, it is argued that refugee organisations can plan and implement RH services for refugees where UNHCR and its international partners ensure that they receive funding and technical assistance. 相似文献
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Franz D. Oeste Rainer Haas Lothar Kaminski 《Environmental science and pollution research international》2000,7(1):5-6
We investigated a new kind of activated carbon named gaiasafe-Formstoff [1] as an agent for powerful heavy metal reduction. This activated carbon contains highly dispersed sulfide compounds. Our investigations with lead containing wastewaters showed an outstanding metal sulfide precipitation power of the new agent. The lead reduction rates are independent of wastewater parameters like lead concentration and complexing agent concentration. Contacted as powder or as a fixed bed with wastewater gaiasafe-Formstoff showed the best cleaning capacity in comparison to all other agents tested. Investigations with gaiasafe-Formstoff about its ability to reduce the contents of further heavy metals in wastewater are under way. The gaiasafe-Formstoff reaction products with wastewater represent an energy-rich and raw material-rich resource when fed to metallurgical processes. 相似文献
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Effects of Spatial Distribution of Prairie Vegetation in an Agricultural Landscape on Curve Number Values
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David J. Dziubanski Kristie J. Franz Matthew J. Helmers 《Journal of the American Water Resources Association》2017,53(2):365-381
The curve number (CN) method is used to calculate runoff in many hydrologic models, including the Soil and Water Assessment Tool (SWAT). The CN method does not account for the spatial distribution of land cover types, an important factor controlling runoff patterns. The objective of this study was to empirically derive CN values that reflect the strategic placement of native prairie vegetation (NPV) within row crop agricultural landscapes. CNs were derived using precipitation and runoff data from a seven‐year period for 14 small watersheds in Iowa. The watersheds were planted with varying amounts of NPV located in different watershed positions. The least squares and asymptotic least squares methods (LSM) were used to derive CNs using an initial abstraction coefficient (λ) of 0.2 and 0.05. The CNs were verified using leave‐one‐out cross‐validation and adjustment for antecedent moisture conditions (AMC) was tested. The asymptotic method produced CN values for watersheds with NPV treatment that were 8.9 and 14.7% lower than watersheds with 100% row crop at λ = 0.2 and λ = 0.05, respectively. The derived CNs produced Nash‐Sutcliffe efficiency values ranging from 0.4 to 0.7 during validation. Our analyses show the CNs verified best for the asymptotic LSM, when using λ of 0.05 and adjusting for AMC. Further, comparison of derived CNs against an area weighted CN indicated that the placement of vegetation does impact the CN value. Editor's note : This paper is part of the featured series on SWAT Applications for Emerging Hydrologic and Water Quality Challenges. See the February 2017 issue for the introduction and background to the series. 相似文献
180.
Assessing Satellite and Ground‐Based Potential Evapotranspiration for Hydrologic Applications in the Colorado River Basin
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Muhammad G. Barik Terri S. Hogue Kristie J. Franz Alicia M. Kinoshita 《Journal of the American Water Resources Association》2016,52(1):48-66
This study evaluates a remotely sensed and two ground‐based potential evapotranspiration (PET) products for hydrologic application in the Upper Colorado River Basin (UCRB). The remotely sensed Moderate Resolution Imaging Spectroradiometer product (MODIS‐PET) is a continuous, daily time series with 250 m resolution derived using the Priestley‐Taylor (P‐T) equation. The MODIS‐PET is evaluated against regional flux tower data as well as a synthetic pan product (Epan; 0.125°, daily) derived from the North American Land Data Assimilation System (NLDAS) and a Hargreaves PET derived from DAYMET variables (DAYMET‐PET; 1 km, daily). Compared to point‐scale PET computed using regional flux tower data, the MODIS‐PET had lower errors, with RMSE values ranging from 2.24 to 2.85 mm/day. Epan RMSE values ranged from 3.70 to 3.76 mm/day and DAYMET‐PET RMSE values ranged from 3.55 to 4.58 mm/day. Further investigation showed biases in temperature and radiation data contribute to uncertainty in the MODIS‐PET values, while bias in NLDAS temperature, downward shortwave (SW↓), and downward longwave (LW↓) propagate in the Epan estimates. Larger discrepancies between methods were observed in the warmer, drier regions of the UCRB, however, the MODIS‐PET was more responsive to landcover transitions and better captured basin heterogeneity. Results indicate the satellite‐based MODIS product can serve as a viable option for obtaining spatial PET values across the UCRB. 相似文献