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171.
The purpose of this study was to determine the hexavalent chromium (CrVI) biosorption capacities of several agricultural wastes from aqueous solutions. Samples were tested unaltered and after hydrochloric acid (HCl) treatment. Additional parameters tested include sample dose, contact time, particle size, mixing temperature, and the concentrations and pH of the CrVI solutions. Desorption studies were performed to determine if the removed CrVI could be recovered. In addition, tests were conducted to determine if the agricultural waste samples (AWS) could be reused for additional CrVI biosorption cycles. The results of this study demonstrate a wide range of CrVI biosorption proficiencies ranging from 13 to 98 percent removal. The parameters that resulted in higher CrVI removal include HCl treatment, higher sample dose, lower CrVI solution concentration, and lower mixing temperature. Desorption results showed an 8 to 25 percent CrVI recovery rate. Reused AWS were effective at removing CrVI during subsequent trials. Therefore, all AWS can be reused for additional CrVI biosorption cycles. Hence, these could reduce hazardous waste disposal inefficiencies and costs by avoiding disposing of spent AWS following each CrVI biosorption cycle. 相似文献
172.
Carol C. House J. Jeffery Goebel Hans T. Schreuder Paul H. Geissler William R. Williams Anthony R. Olsen 《Environmental monitoring and assessment》1998,51(1-2):451-463
A demonstration project in Oregon examined the feasibility of combining Federal environmental monitoring surveys. An integrated approach should remove duplication of effort and reduce the possibility of providing apparently conflicting information to policy makers and the public. Data collection teams made photo interpretation measurements and on-site soil/vegetation/animal observations at locations that were selected from the Forest Inventory and Analysis (FIA), National Forest System (NFS) Region 6, and National Resource Inventory (NRI) surveys in a six-county area in Northern Oregon. The project demonstrated the feasibility of conducting a combined FIA/NFS/NRI survey and suggests an approach that will preserve the utility of the critical historical information from these surveys. We suggest a framework for estimating the extent of forest and range land that explains FIA/NRI differences and provides a common basis for both surveys. We suggest indicator and protocol criteria that will allow consistent national and regional estimates over all vegetation types, and stress the importance of including measurement repeatability in the design of the combined survey. 相似文献
173.
Thomas A. Watson F. Anthony Barnett Stephen T. Gray Glenn A. Tootle 《Journal of the American Water Resources Association》2009,45(1):224-236
Abstract: Tree rings offer a means to extend observational records of streamflow by hundreds of years, but dendrohydrological techniques are not regularly applied to small tributary and headwaters gages. Here we explore the potential for extending three such gage records on small streams in the Wind River drainage of central Wyoming, United States. Using core samples taken from Douglas fir (Pseudotsuga menziesii), piñon pine (Pinus edulis), and limber pine (Pinus flexilis) at 38 sites, we were able to reconstruct streamflows for the headwaters of the Wind River back to 1672 AD or earlier. The streamflow reconstructions for Bull Lake Creek above Bull Lake; the Little Popo Agie River near Lander, Wyoming; and Wind River near Dubois, Wyoming explained between 40% and 64% of the observed variance, and these extended records performed well in a variety of statistical verification tests. The full reconstructions show pronounced inter‐annual variability in streamflow, and these proxy records also point to the prevalence of severe, sustained droughts in this region. These reconstructions indicate that the 20th Century was relatively wet compared to previous centuries, and actual gage records may capture only a limited subset of potential natural variability in this area. Further analyses reveal how tree‐ring based reconstructions for small tributary and headwaters gages can be strongly influenced by the length and quality of calibration records, but this work also demonstrates how the use of a spatially extensive network of tree‐ring sites can improve the quality of these types of reconstructions. 相似文献
174.
Gérard C Poullain V Lance E Acou A Brient L Carpentier A 《Environmental pollution (Barking, Essex : 1987)》2009,157(2):609-617
Community structure and microcystin accumulation of freshwater molluscs were studied before and after cyanobacterial proliferations, in order to assess the impact of toxic blooms on molluscs and the risk of microcystin transfer in food web. Observed decrease in mollusc abundance and changes in species richness in highly contaminated waters were not significant; however, relative abundances of taxa (prosobranchs, pulmonates, bivalves) were significantly different before and after cyanobacterial bloom. Pulmonates constituted the dominant taxon, and bivalves never occurred after bloom. Microcystin accumulation was significantly higher in molluscs from highly (versus lowly) contaminated waters, in adults (versus juveniles) and in pulmonates (versus prosobranchs and bivalves). Results are discussed according to the ecology of molluscs, their sensitivity and their ability to detoxify. 相似文献
175.
Total annual nutrient loads are a function of both watershed characteristics and the magnitude of nutrient mobilizing events.
We investigated linkages among land cover, discharge and total phosphorus (TP) concentrations, and loads in 25 Kansas streams.
Stream monitoring locations were selected from the Kansas Department of Health and Environment stream chemistry long-term
monitoring network sites at or near U.S. Geological Survey stream gauges. We linked each sample with concurrent discharge
data to improve our ability to estimate TP concentrations and loads across the full range of possible flow conditions. Median
TP concentration was strongly linked (R
2 = 76%) to the presence of cropland in the riparian zones of the mostly perennial streams. At baseflow, discharge data did
not improve prediction of TP, but at high flows discharge was strongly linked to concentration (a threshold response occurred).
Our data suggest that on average 88% of the total load occurred during the 10% of the time with the greatest discharge. Modeled
reductions in peak discharges, representing increased hydrologic retention, predicted greater decreases in total annual loads
than reductions of ambient concentrations because high discharge and elevated phosphorus concentrations had multiplicative
effects. No measure of land use provided significant predictive power for concentrations when discharge was elevated or for
concentration rise rates under increasing discharge. These results suggest that reductions of baseflow concentrations of TP
in streams without wastewater dischargers may be managed by reductions of cropland uses in the riparian corridor. Additional
measures may be needed to manage TP annual loads, due to the large percentage of the TP load occurring during a few high-flow
events each year. 相似文献
176.
Ton Snelder Anthony Lehmann Nicolas Lamouroux John Leathwick Karin Allenbach 《Environmental management》2009,44(4):658-670
Numerical clustering has frequently been used to define hierarchically organized ecological regionalizations, but there has
been little robust evaluation of their performance (i.e., the degree to which regions discriminate areas with similar ecological
character). In this study we investigated the effect of the weighting and treatment of input variables on the performance
of regionalizations defined by agglomerative clustering across a range of hierarchical levels. For this purpose, we developed
three ecological regionalizations of Switzerland of increasing complexity using agglomerative clustering. Environmental data
for our analysis were drawn from a 400 m grid and consisted of estimates of 11 environmental variables for each grid cell
describing climate, topography and lithology. Regionalization 1 was defined from the environmental variables which were given
equal weights. We used the same variables in Regionalization 2 but weighted and transformed them on the basis of a dissimilarity
model that was fitted to land cover composition data derived for a random sample of cells from interpretation of aerial photographs.
Regionalization 3 was a further two-stage development of Regionalization 2 where specific classifications, also weighted and
transformed using dissimilarity models, were applied to 25 small scale “sub-domains” defined by Regionalization 2. Performance
was assessed in terms of the discrimination of land cover composition for an independent set of sites using classification
strength (CS), which measured the similarity of land cover composition within classes and the dissimilarity between classes.
Regionalization 2 performed significantly better than Regionalization 1, but the largest gains in performance, compared to
Regionalization 1, occurred at coarse hierarchical levels (i.e., CS did not increase significantly beyond the 25-region level).
Regionalization 3 performed better than Regionalization 2 beyond the 25-region level and CS values continued to increase to
the 95-region level. The results show that the performance of regionalizations defined by agglomerative clustering are sensitive
to variable weighting and transformation. We conclude that large gains in performance can be achieved by training classifications
using dissimilarity models. However, these gains are restricted to a narrow range of hierarchical levels because agglomerative
clustering is unable to represent the variation in importance of variables at different spatial scales. We suggest that further
advances in the numerical definition of hierarchically organized ecological regionalizations will be possible with techniques
developed in the field of statistical modeling of the distribution of community composition. 相似文献
177.
Climate Change and Climate Variability: Adaptations to Reduce Adverse Health Impacts 总被引:2,自引:0,他引:2
Global climate change is likely to have a range of consequences for human health as a result of disturbance or weakening of the biosphere's natural or human-managed life support systems. The full range of potential human health impacts of global climate change is diverse and would be distributed differentially spatially and over time. Changes in the mortality toll of heatwaves and changes in the distribution of vector-borne infectious diseases may occur early. The public health consequences of sea level rise and of regional changes in agricultural productivity may not occur (or become apparent) for several decades. Vulnerability is a measure of both sensitivity to climate change and the ability to adapt in anticipation of, or in response to, its impacts. The basic modes of adaptation to climate-induced health hazards are biological, behavioural and social. Adaptation can be undertaken at the individual, community and whole-population levels. Adaptive strategies should not introduce new health hazards. Enhancement of the acknowledged public health infrastructure and intervention programmes is essential to reduce vulnerability to the health impacts of climate change. In the longer-term, fundamental improvements in the social and material conditions of life and in the reduction of inequalities within and between populations are required for sustained reduction in vulnerability to environmental health hazards. 相似文献
178.
179.
Hung-Suck Park Eldon R. Rene Soo-Mi Choi Anthony S.F. Chiu 《Journal of environmental management》2008
The Korea National Cleaner Production Center (KNCPC) affiliated to the Korea Institute of Industrial Technology (KITECH) has started a 15 year, 3-phase EIP master plan with the support of Ministry of Commerce, Industry, and Energy (MOCIE). A total of 6 industrial parks, including industrial parks in Ulsan city, known as the industrial capital of South Korea, are planning projects to find the feasibility of shifting existing industrial parks to eco-industrial parks. The basic survey shows that Ulsan industrial complex has been continuously evolving from conventional industrial complexes to eco-industrial parks by spontaneous industrial symbiosis. This paper describes the Korean national policies and the developmental activities of this vision to drive the global trend of innovation for converting the existing industrial parks to eco-industrial parks through inter-industry waste, energy, and material exchange in Ulsan Industrial complexes. In addition, the primary and supportive components of the Ulsan EIP pilot project, which will be implemented for 5 years is elaborated with its schedules and economic benefits. 相似文献
180.