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排序方式: 共有1031条查询结果,搜索用时 78 毫秒
931.
An acoustic Doppler velocity meter (ADVM) was deployed in the narrows between Namakan and Kabetogama Lakes in Voyageurs National Park, Minnesota, from November 3, 2010, through October 3, 2012. The ADVM can account for wind, seiche, and changing flow direction in hydrologically complex areas. The objectives were to (1) estimate discharge and document the direction of water flow, (2) assess whether specific conductance can be used to determine flow direction, and (3) document nutrient and chlorophyll a concentrations at the narrows. The discharge direction through the narrows was seasonal. Water generally flowed out of Kabetogama Lake and into Namakan Lake throughout the ice‐covered season. During spring, water flow was generally from Namakan Lake to Kabetogama Lake. During the summer and fall, the water flowed in both directions, affected in part by wind. Water flowed into Namakan Lake 70% of water year 2011 and 56% of water year 2012. Nutrient and chlorophyll a concentrations were highest during the summer months when water‐flow direction was unpredictable. The use of an ADVM was effective for assessing flow direction and provided flow direction under ice. The results indicated the eutrophic Kabetogama Lake may have a negative effect on the more pristine Namakan Lake. The results also provide data on the effects of the current water‐level management plan and may help determine if adjustments are necessary to help protect the aquatic ecosystem of Voyageurs National Park.  相似文献   
932.
933.
Many jurisdictions around the globe have well-developed regulatory frameworks for the derivation and implementation of water quality guidelines (WQGs) or their equivalent (e.g. environmental quality standards, criteria, objectives or limits). However, a great many more still do not have such frameworks and are looking to introduce practical methods to manage chemical exposures in aquatic ecosystems. There is a potential opportunity for learning and sharing of data and information between experts from different jurisdictions in order to deliver efficient and effective methods to manage potential aquatic risks, including the considerable reduction in the need for aquatic toxicity testing and the rapid identification of common challenges. This paper reports the outputs of an international workshop with representatives from 14 countries held in Hong Kong in December 2011. The aim of the workshop and this paper was to identify ‘good practice’ in the development of WQGs to deliver to a range of environmental management goals. However, it is important to broaden this consideration to cover often overlooked facets of implementable WQGs, such as demonstrable field validation (i.e. does the WQG protect what it is supposed to?), fit for purpose of monitoring frameworks (often an on-going cost) and finally how are these monitoring data used to support management decisions in a manner that is transparent and understandable to stakeholders. It is clear that regulators and the regulated community have numerous pressures and constraints on their resources. Therefore, the final section of this paper addresses potential areas of collaboration and harmonisation. Such approaches could deliver a consistent foundation from which to assess potential chemical aquatic risks, including, for example, the adoption of bioavailability-based approaches for metals, whilst reducing administrative and technical burdens in jurisdictions.  相似文献   
934.
935.
As pollution becomes one of the biggest environmental challenges of the twenty-first century, pollution of water threatens the very existence of humanity, making immediate action a priority. The most persistent and hazardous pollutants come from industrial and agricultural activities; therefore, effective treatment of this wastewater prior to discharge into the natural environment is the solution. Advanced oxidation processes (AOPs) have caused increased interest due to their ability to degrade hazardous substances in contrast to other methods, which mainly only transfer pollution from wastewater to sludge, a membrane filter, or an adsorbent. Among a great variety of different AOPs, a group of electrochemical advanced oxidation processes (EAOPs), including electro-Fenton, is emerging as an environmental-friendly and effective treatment process for the destruction of persistent hazardous contaminants. The only concern that slows down a large-scale implementation is energy consumption and related investment and operational costs. A combination of EAOPs with biological treatment is an interesting solution. In such a synergetic way, removal efficiency is maximized, while minimizing operational costs. The goal of this review is to present cutting-edge research for treatment of three common and problematic pollutants and effluents: dyes and textile wastewater, olive processing wastewater, and pharmaceuticals and hospital wastewater. Each of these types is regarded in terms of recent scientific research on individual electrochemical, individual biological and a combined synergetic treatment.  相似文献   
936.
937.
Feral swine are estimated to annually cost hundreds of millions of dollars in economic loss to property and agriculture in the USA, while their ecological consequences remain largely unmeasured. Using submeter-accurate Global Positioning System technology over a multiyear project, we are quantifying in a novel way the spatial and temporal attributes of swine rooting damage within 587 ha of ecologically sensitive wetland plant communities at Avon Park Air Force Range in south-central Florida. We delineated damage polygons from 0.0023 to 4,335 m2 and were able to document recurrent damage through time at most sites during each assessment. For each polygon, we also estimated the age of damage and assigned to it a severity index, qualities of the rooting in which we detected changes in proportions over time. Spatially explicit damage assessments at fine scales conducted over several years can assist land managers in determining effects of rooting on rare plant populations, and will allow investigators to hypothesize what factors are driving patterns of this disturbance across ecologically sensitive plant communities.  相似文献   
938.
New concerns about biodiversity, ecosystem services and human health triggered several new regulations increasing the need for sound ecotoxicological risk assessment. The PEER network aims to share its view on the research issues that this challenges. PEER scientists call for an improved biologically relevant exposure assessment. They promote comprehensive effect assessment at several biological levels. Biological traits should be used for Environmental risk assessment (ERA) as promising tools to better understand relationships between structure and functioning of ecosystems. The use of modern high throughput methods could also enhance the amount of data for a better risk assessment. Improved models coping with multiple stressors or biological levels are necessary to answer for a more scientifically based risk assessment. Those methods must be embedded within life cycle analysis or economical models for efficient regulations. Joint research programmes involving humanities with ecological sciences should be developed for a sound risk management.  相似文献   
939.
Previous academic research into how consumers evaluate advocacy advertising identified many possible paths involving potentially reflexive effects on how people perceive an advocacy advertising sponsor, the advocated issue and themselves. This paper has examined one possible scenario within this complicated phenomenon: that of advertising advocating a specific environmental consumer action, recycling. In the specific context of this study, structural equation modelling demonstrated clear causal relationships among consumer perceptions of the recycling advertisements’ sponsoring organization, consumer self-efficacy and perceived consumer effectiveness of complying with the advocated issue (recycling behaviour). These factors were shown to impact specific advocacy advertising goals (termed message effectiveness in this study) such as behavioural intention toward the advocated recycling issue and perceived changes in how consumers evaluate the sponsoring organization.  相似文献   
940.
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