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排序方式: 共有195条查询结果,搜索用时 46 毫秒
71.
The Watershed Flow and Allocation Model: An NHDPlus‐Based Watershed Modeling Approach for Multiple Scales and Conditions 下载免费PDF全文
Michele C. Eddy Fekadu G. Moreda Robert M. Dykes Brandon Bergenroth Aaron Parks James Rineer 《Journal of the American Water Resources Association》2017,53(1):6-29
The Watershed Flow and Allocation model (WaterFALL®) provides segment‐specific, daily streamflow at both gaged and ungaged locations to generate the hydrologic foundation for a variety of water resources management applications. The model is designed to apply across the spatially explicit and enhanced National Hydrography Dataset (NHDPlus) stream and catchment network. To facilitate modeling at the NHDPlus catchment scale, we use an intermediate‐level rainfall‐runoff model rather than a complex process‐based model. The hydrologic model within WaterFALL simulates rainfall‐runoff processes for each catchment within a watershed and routes streamflow between catchments, while accounting for withdrawals, discharges, and onstream reservoirs within the network. The model is therefore distributed among each NHDPlus catchment within the larger selected watershed. Input parameters including climate, land use, soils, and water withdrawals and discharges are georeferenced to each catchment. The WaterFALL system includes a centralized database and server‐based environment for storing all model code, input parameters, and results in a single instance for all simulations allowing for rapid comparison between multiple scenarios. We demonstrate and validate WaterFALL within North Carolina at a variety of scales using observed streamflows to inform quantitative and qualitative measures, including hydrologic flow metrics relevant to the study of ecological flow management decisions. 相似文献
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73.
Small-scale mining in China: Assessing recent advances in the policy and regulatory framework 总被引:1,自引:0,他引:1
This paper explores the background of a proposed revision to the Mineral Resources Law of China, why and how the law was amended in the past, its salient features and objectives. Of equal importance is an analysis of how this national law, with its attendant regulations and policies, formed the basis for the growth and continued development of China's small-scale mining industry. The Xiaoqingling Gold Mountain case study is shown to justify the necessity and feasibility for formalizing and consolidating small-scale mines in China, and to some extent, the success of the nation-wide ASM resource consolidation policy at a local level. 相似文献
74.
Uranium removal from groundwater via in situ biostimulation: Field-scale modeling of transport and biological processes 总被引:1,自引:0,他引:1
Yabusaki SB Fang Y Long PE Resch CT Peacock AD Komlos J Jaffe PR Morrison SJ Dayvault RD White DC Anderson RT 《Journal of contaminant hydrology》2007,93(1-4):216-235
During 2002 and 2003, bioremediation experiments in the unconfined aquifer of the Old Rifle UMTRA field site in western Colorado provided evidence for the immobilization of hexavalent uranium in groundwater by iron-reducing Geobacter sp. stimulated by acetate amendment. As the bioavailable Fe(III) terminal electron acceptor was depleted in the zone just downgradient of the acetate injection gallery, sulfate-reducing organisms came to dominate the microbial community. In the present study, we use multicomponent reactive transport modeling to analyze data from the 2002 field experiment to identify the dominant transport and biological processes controlling uranium mobility during biostimulation, and determine field-scale parameters for these modeled processes. The coupled process simulation approach was able to establish a quantitative characterization of the principal flow, transport, and reaction processes based on the 2002 field experiment, that could be applied without modification to describe the 2003 field experiment. Insights gained from this analysis include field-scale estimates of the bioavailable Fe(III) mineral threshold for the onset of sulfate reduction, and rates for the Fe(III), U(VI), and sulfate terminal electron accepting processes. 相似文献
75.
Brent William Murray John Y. Wang Shih-Chu Yang John D. Stevens Aaron Fisk Jörundur Svavarsson 《Marine Biology》2008,153(6):1015-1022
Sleeper sharks are a poorly studied group of deep-sea sharks. The subgenus, Somniosus, contains three morphologically similar species: S. microcephalus found in the Arctic and North Atlantic; S. pacificus in the North Pacific; and S. antarcticus in the Southern Ocean. These sharks have been reported mainly in temperate to polar waters and occasionally in subtropical
locations. They have not been recorded in tropical waters. This study investigates the relationships among the accepted species
of Somniosus through analysis of mitochondrial cytochrome b sequence variation. Seventy-five samples were examined from four sampling locations in the North Pacific, Southern Ocean
and North Atlantic. Twenty-one haplotypes were found. A minimum spanning parsimony network separated these haplotypes into
two divergent clades, an S. microcephalus and an S. pacificus/antarcticus clade, strongly supporting the distinction of S. microcephalus as a separate species from the Pacific sleeper shark species. Analysis of genetic structure within the S. pacificus/antarcticus clade (analysis of molecular variance, allele frequency comparisons, and a nested clade analysis) showed limited or no differences
amongst three populations. Further examination of genetic variation at more variable mtDNA and nuclear markers is needed to
examine the species status of S. pacificus and S. antarcticus. 相似文献
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Aaron D. Spares Michael J. W. Stokesbury Ron K. O’Dor Terry A. Dick 《Marine Biology》2012,159(8):1633-1646
The influence of salinity, temperature and prey availability on the marine migration of anadromous fishes was determined by describing the movements, habitat use and feeding behaviours of Arctic char (Salvelinus alpinus). The objectives were to determine whether char are restricted to the upper water column of the inter-/subtidal zones due to warmer temperatures. Twenty-seven char were tracked with acoustic temperature/pressure (depth) transmitters from June to September, 2008/2009, in inner Frobisher Bay, Canada. Most detections were in surface waters (0–3 m). Inter-/subtidal movements and consecutive repetitive dives (maximum 52.8 m) resulted in extreme body temperature shifts (−0.2–18.1 °C). Approximately half of intertidal and subtidal detections were between 9–13 °C and 1–3 °C, respectively. Stomach contents and deep diving suggested feeding in both inter-/subtidal zones. We suggest that char tolerate cold water at depth to capture prey in the subtidal zone, then seek warmer water to enhance feeding/digestion physiology. 相似文献
78.
David J. Cornell Stacy L. Gnacinski Aaron Zamzow Jason Mims Kyle T. Ebersole 《International journal of occupational safety and ergonomics》2013,19(2):198-204
Aim. The purpose of this study was to examine the associations between various health and fitness measures and Functional Movement Screen? (FMS?) scores among 78 firefighter recruits. Methods. Relationships between FMS? scores and age, body mass index (BMI), sit and reach (S&R) distance, estimated maximal aerobic capacity (V˙O2max), estimated one-repetition maximum squat (1RM-Squatmax), and plank endurance (%Plankmax) were examined. Results. Total FMS? scores were significantly correlated with BMI (r?=??0.231, p?=?0.042), estimated 1RM-Squatmax (r?=?0.302, p?=?0.007), and %Plankmax (r?=?0.320, p?=?0.004). Multiple regression analyses indicated that this combination of predictors significantly predicted (F(3, 74)?=?5.043, p?=?0.003) Total FMS? score outcomes and accounted for 17% of the total variance (R2?=?0.170). In addition, logistic regression analyses indicated that estimated 1RM-Squatmax also significantly predicted (χ2?=?6.662, df?=?1, p?=?0.010) FMS? group membership (≤14 or ≥15). Conclusion. These results suggest that the health and fitness measures of obesity (BMI), bilateral lower extremity strength (estimated 1RM-Squatmax), and core muscular endurance (%Plankmax) are significantly associated with functional movement patterns among firefighter recruits. Consequently, injury prevention programs implemented among firefighter recruits should target these aspects of health and fitness. 相似文献
79.
80.
Cribb BW Stewart A Huang H Truss R Noller B Rasch R Zalucki MP 《Die Naturwissenschaften》2008,95(1):17-23
A number of arthropod taxa contain metals in their mandibles (jaws), such as zinc, manganese, iron, and calcium. The occurrence of zinc and its co-located halogen chlorine have been studied in relation to the mechanical properties and shown to be linked in a direct fashion with increasing concentration. Hardness along with elastic modulus (stiffness) has also been linked to zinc and halogen concentration in some marine polychaete worms. The metal appears to be incorporated within the biological matrix, possibly bonding with proteins. However, the comparative advantage of metal inclusion has not been tested. It is possible that without metals, alternative mechanisms are used to achieve hardness of equal value in similar 'tools' such as mandibles. This question has direct bearing on the significance of metal hardening. In the present article, we compare across mandibles from six termite species, including samples with major zinc concentration, minor manganese, and no metals. Nanoindentation, electron microscopy, and electron microanalysis are used to assess metal concentration, form, and mechanical properties. The data demonstrate that termite mandibles lacking metals when fully developed have lower values for hardness and elastic modulus. Zinc is linked to a relative 20% increase in hardness when compared with mandibles devoid of metals. The similar transition metal, manganese, found in minor concentrations, is not linked to any significant increase in these mechanical properties. This raises the question of the function of manganese, which is as commonly found in insect mandibles as zinc and often located in the same mandibles. 相似文献