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621.
622.
Anna Piotrowska-Długosz Edward Wilczewski 《Environmental monitoring and assessment》2014,186(12):8425-8441
The effect of the time of catch crop (field pea) incorporation [catch crop incorporated in the autumn (A) or in the spring (B) versus plots without a catch crop (C)] on the soil enzymes related to N transformation (urease – UR, protease – PRO, nitrate reductase – NR, arginine ammonification rate – AAR), the total N and mineral N as well as microbial biomass N (MBN) contents were investigated in a 3-year experiment. The catch crop was sown at the beginning of August and plowed in the autumn in 2008, 2009 and 2010 or left as mulch during the winter. Soil samples for microbial activity were taken from spring barley plots that were grown in 2009, 2010 and 2011 before sowing (March), during the tillering phase (May), shooting (June) and after the harvesting of spring barley (August). The use of catch crop significantly increased the soil mineral and MBN contents as well as the activities of PRO and NR as compared to the control soil. The spring incorporation of the field pea significantly increased the MBN content in contrast to the autumn application, while the activity of N-cycle enzymes were clearly unaffected (UR and AAR) regardless of the time of the incorporation of field pea or else the results were inconsistent (PRO and NR). When the catch crop was incorporated in the spring, a significantly higher content of mineral N as compared to autumn incorporation was noted on only two of the four sampling dates. The enzymatic activity (PRO and AAR) was about 1.3-2.8 times higher in May and June as compared with March and August. Both spring or autumn incorporation of catch crop can be a useful management practice to increase the soil mineral N content and enhance the soil biological activity. 相似文献
623.
Andrew J. Leidner M. Edward Rister Ronald D. Lacewell Allen W. Sturdivant 《Journal of the American Water Resources Association》2011,47(3):597-610
Leidner, Andrew J., M. Edward Rister, Ronald D. Lacewell, and Allen W. Sturdivant, 2011. The Water Market for the Middle and Lower Portions of the Texas Rio Grande Basin. Journal of the American Water Resources Association (JAWRA) 47(3):597‐610. DOI: 10.1111/j.1752‐1688.2011.00527.x Abstract: Regional water management on the United States’ side of the middle and lower portions of the Rio Grande basin of Texas has been aided by a functioning water market since the early 1970s. The water market operates over a region that stretches from the Amistad Reservoir to the Rio Grande’s terminus into the Gulf of Mexico. This article provides an overview of the organizations, institutions, policies, and geographic particulars of the region’s water‐management system and its water market. In recent years, this region has experienced high population growth, periodic droughts, and a reallocation of water resources from the area’s agricultural sector to the municipal sector. Demand growth for potable water and a relatively fixed supply of raw water are reflected in increasing prices for domestic, municipal, and industrial water rights. Rising prices in the presence of scarcity and the transfer of water from lower‐value to higher‐value uses indicate that the market is operating as suggested by economic theory. Reasons for the market’s functionality are presented and discussed. Finally, suggestions are presented which might mitigate potential complications to market operations from aquifer depletion and aid the management of instream river flows. 相似文献
624.
Determining the viability of marine protists using a combination of vital, fluorescent stains 总被引:1,自引:0,他引:1
Determining the viability of protists and small microzooplankton has long been a focus of studies in marine biology and ecology.
It is especially relevant in the issue of shipborne invasive species, and impending international guidelines and various national
regulations on the allowable concentrations of organisms in discharged ballast water have spurred the growth of an industry
that develops and manufactures ballast water management systems. The success of management systems and ability of ships to
meet ballast water discharge standards is determined by the number of viable organisms in treated water. Here, we propose
combining two vital, fluorescent stains (fluorescein diacetate [FDA] and 5-chloromethylfluorescein diacetate [CMFDA]) with
direct microscopic observation to enumerate viable organisms ≥10 and <50 μm in minimum dimension (nominally protists). This
approach was validated in four locations in the United States to determine the efficacy of the stains. Although the accuracy
of the stains varied by geographic location and the taxonomic composition of the planktonic assemblage, combining fluorescent
stains is a robust, powerful tool that can be optimized for the species present at each location. While this method was developed
for analyzing viable organisms in treated ballast water, it may also be used or adapted for any field of research that examines
a broad taxonomic range of autotrophic and heterotrophic plankton. 相似文献
625.
Repetitive flood victims and acceptance of FEMA mitigation offers: an analysis with community-system policy implications 总被引:1,自引:0,他引:1
Of all natural disasters, flooding causes the greatest amount of economic and social damage. The United States' Federal Emergency Management Agency (FEMA) uses a number of hazard mitigation grant programmes for flood victims, including mitigation offers to relocate permanently repetitive flood loss victims. This study examines factors that help to explain the degree of difficulty repetitive flood loss victims experience when they make decisions about relocating permanently after multiple flood losses. Data are drawn from interviews with FEMA officials and a survey of flood victims from eight repetitive flooding sites. The qualitative and quantitative results show the importance of rational choices by flood victims in their mitigation decisions, as they relate to financial variables, perceptions of future risk, attachments to home and community, and the relationships between repetitive flood loss victims and the local flood management officials who help them. The results offer evidence to suggest the value of a more community-system approach to FEMA relocation practices. 相似文献
626.
627.
Edward Alexander Morgan Deanna Chantal Cristina Grant-Smith 《Journal of Environmental Planning and Management》2015,58(10):1770-1788
Although science is generally assumed to be well integrated into rational decision-making models, it can be used to destabilise consultative processes, particularly when emotions are involved. Water policies are often seen as debates over technical and engineering issues, but can be highly controversial. Recycled water proposals, in particular, can create highly emotive conflicts. Through a case study regarding the rejection of recycled water proposals in the south-east Queensland, Australia, we explore the influence of science and emotions in contemporary water planning. We highlight the dangers inherent in promoting technical water planning issues at the expense of appropriate consideration of citizen concerns. Combining the science–policy interface and stakeholder engagement literatures, we advocate for collaborative decision-making processes that accommodate emotions and value judgements. A more collaborative stakeholder engagement model, founded on the principles of co-learning, has the potential to broaden the decision-making base and to promote better and more inclusive decision-making. 相似文献
628.
Didac Pascual Jonas kerman Marina Becher Terry V. Callaghan Torben R. Christensen Ellen Dorrepaal Urban Emanuelsson Reiner Giesler Dan Hammarlund Edward Hanna Annika Hofgaard Hongxiao Jin Cecilia Johansson Christer Jonasson Jonatan Klaminder Jan Karlsson Erik Lundin Anders Michelsen David Olefeldt Andreas Persson Gareth K. Phoenix Zofia Rczkowska Riikka Rinnan Lena Strm Jing Tang Ruth K. Varner Philip Wookey Margareta Johansson 《Ambio》2021,50(2):375
Arctic and subarctic ecosystems are experiencing substantial changes in hydrology, vegetation, permafrost conditions, and carbon cycling, in response to climatic change and other anthropogenic drivers, and these changes are likely to continue over this century. The total magnitude of these changes results from multiple interactions among these drivers. Field measurements can address the overall responses to different changing drivers, but are less capable of quantifying the interactions among them. Currently, a comprehensive assessment of the drivers of ecosystem changes, and the magnitude of their direct and indirect impacts on subarctic ecosystems, is missing. The Torneträsk area, in the Swedish subarctic, has an unrivalled history of environmental observation over 100 years, and is one of the most studied sites in the Arctic. In this study, we summarize and rank the drivers of ecosystem change in the Torneträsk area, and propose research priorities identified, by expert assessment, to improve predictions of ecosystem changes. The research priorities identified include understanding impacts on ecosystems brought on by altered frequency and intensity of winter warming events, evapotranspiration rates, rainfall, duration of snow cover and lake-ice, changed soil moisture, and droughts. This case study can help us understand the ongoing ecosystem changes occurring in the Torneträsk area, and contribute to improve predictions of future ecosystem changes at a larger scale. This understanding will provide the basis for the future mitigation and adaptation plans needed in a changing climate.Electronic supplementary materialThe online version of this article (10.1007/s13280-020-01381-1) contains supplementary material, which is available to authorized users. 相似文献
629.
Lawrence J.H. Schulze David Goldstein Anupam Patel Edward Stanton James Woods 《International journal of occupational safety and ergonomics》2013,19(3-4):109-118
Opening and closing valves in industrial facilities often requires operators to use bars and wrenches as levers (cheaters) in order to overcome initial actuation forces. In order to determine more appropriate operational specifications, the maximum torque production capability was measured when 12 male participants used 4 different valve handwheels at 3 different heights and 2 different angles (in relationship to the coronal plane). The results indicate that the participants produced significantly greater torque when the largest of the 4 wheels (40.6 cm diameter) was used than when the medium (22.9 cm), small (20.3 cm), and handled (17.8 cm) handwheels were used. Although the main effect of heights was found to be statistically significant, post-hoc analyses between the heights found them to be, essentially, equal. In addition, the vertical and horizontal wheel orientations were not found to be different. The results are applicable to all industries where handwheels are used and applicable to valve manufacturers for designing operational torque specifications below the values found in this study. 相似文献
630.
Lawrence J.H. Schulze Edward Stanton Anupam Patel Maurizio Cheli 《International journal of occupational safety and ergonomics》2013,19(1-2):31-40
Hand cranks are used in a variety of industries to actuate valves and in other gear-operated applications. In order to evaluate these types of operations and their compatibility with operator strength capabilities, a rotational dynamometer was used to measure torque production capability of operators using a hand crank at different heights and angles (with respect to the coronal plane). The tests were conducted for both clockwise and counterclockwise rotations using the dominant arm of each test participant. A total of 18 tests were completed by each of five male right-handed test participants. A 0° declination angle, counterclockwise operation, and both 40.65 cm and 60.96 cm heights were found to be associated with the greatest torque production capabilities. 相似文献