Oil spills at sea remain a serious threat to coastal settlements and sensitive ecosystems. Although the impacts of spills are contingent upon a variety of environmental factors and the chemical composition of the oil itself, spill effects can be long lasting in the pelagic zone with broad impacts on sensitive bacterial, microbial, plant, and animal communities. Efforts to contain, deflect, protect, and mitigate the effects of oil are increasingly important, given the massive social, economic, and environmental fallout connected to large spills. The purpose of this paper is to provide geographic perspective for protecting coastal areas with exclusion booms during oil spill events. Specifically, we introduce a generalized, extendable, spatial optimization model that simultaneously minimizes spill effects on vulnerable shorelines and the total costs associated with dispatching booms. The multiobjective model is solved with a weighting method to produce a Pareto optimal curve that reveals how the costs and protection operations change under different priorities. A simulated tanker spill near Mobile Bay, AL, USA, is used as an illustrative example.
The New England Governors and Eastern Canadian Premiers (NEG/ECP) adopted the Acid Rain Action Plan in June 1998, and issued a series of action items to support its work toward a reduction of sulfur dioxide (SO2) and nitrogen oxide (NOx) emissions in northeastern North America. One of these action items was the preparation of an updated critical load map using
data from lakes in the NEG/ECP area. Critical load maps provide a more complete index of the surface water sensitivity to
acidification. Combined sulfur and nitrogen critical loads and deposition exceedances were computed using Henriksen's Steady-State
Water Chemistry (SSWC) model. Results show that 28% of all 2053 lakes studied have a critical load of 20 kg/ha/year or less,
making them vulnerable to acid deposition. Emission reductions, and more specifically SO2 emission reductions have proven beneficial because critical loads were exceeded in 2002 for 12.3% of all studied lakes. Those
lakes are located in the more sensitive areas where geology is carbonate-poor. Of these lakes, 2.9% will never recover even
with a complete removal of SO4 deposition. Recovery from acidification for the remaining 9.4% of the lakes will require additional emission SO2 reductions. 相似文献
Urban ecosystems are increasingly influenced by residential yard care decisions. This had led researchers to focus on homeowner education programs when it comes to yard care. Typically, the success of programs designed to influence yard care is based on whether the target subject changes his or her behavior in a more environmentally conscious manner. This threshold, however, fails to consider if individuals share this information with their friends and neighbors, thus having a possible spillover effect. In this paper, we focus on the transmission of new lawn management information among neighbors and consider (1) if individuals discuss information they learned in a short-term educational program, (2) what factors are associated with diffusion, (3) what information individuals share, and (4) what barriers to transmission exist. In the Minneapolis–St. Paul metropolitan area, we used data from a mailed survey, group discussions, and mailed information exchanges. Results indicate that best management practices for yards can diffuse through the neighborhood (approximately 34 % shared information with their neighbors in a one-month period). In addition, factors such as (1) attending a group discussion, 2) individual social connectedness, (3) length of home ownership, and (4) the presence of children in the household were found to be positively related to increased sharing of information. Also, for lawns, the content of information shared tended to be about increasing grass height and reducing fertilizer applications. Finally, we find barriers to sharing ideas based on spatial, temporal, or perception factors but overcoming some of these barriers is possible. 相似文献
An extensive site-characterization project was conducted at a large chlorinated-solvent contaminated Superfund site in Tucson, AZ. The project consisted of several components, including traditional site-characterization activities, tracer tests, laboratory experiments conducted with core material collected from the site, and mathematical modeling. The primary focus of the work presented herein is the analysis of induced-gradient contaminant elution tests conducted in a source zone at the site, investigation of the potential occurrence of immiscible liquid in the saturated zone, characterization of the relationship between mass flux reduction and mass removal, and evaluation of the impact of source-zone management on site remediation. The results of the present study, along with those of prior work, indicate that immiscible liquid is likely present in the saturated zone at the site source zones. Extensive tailing and rebound was observed for the contaminant-elution tests, indicating nonideal transport and mass-transfer behavior. The elution data were analyzed with a source-zone-scale mathematical model, and the results indicated that nonideal immiscible-liquid dissolution was the primary cause of the observed behavior. The time-continuous relationship between mass flux reduction and mass removal associated with the plume-scale pump-and-treat operation exhibited an initial large drop in mass flux with minimal mass removed, followed by a period of minimal mass flux reduction and a second period of large reduction. This behavior reflects the impact of both source-zone and aqueous-plume mass removal dynamics. Ultimately, a greater than 90% reduction in mass flux was achieved for a mass removal of approximately 50%. The influence of source-zone management on site remediation was evaluated by conducting two predictive simulations, one for which the source zones were controlled and one for which they were not. A plume-scale model was used to simulate the composite contaminant concentrations associated with groundwater extracted with the pump-and-treat system, which were compared to measured data. The information generated from this study was used to enhance the site conceptual model, help optimize operation of the pump-and-treat system, and evaluate the utility of source-zone remediation. 相似文献
A study was conducted to determine the concentrations of algal-available P (Paa) in unfractionated samples and size-classified separates of soil eroded from wheat stubble plots during a simulated rainfall experiment conducted in Warren County, Indiana, U.S.A. Run-off samples were collected, concentrated, dispersed by sonification, separated according to size and incubated with algal cells (Selanastrum capricornutum) in P-free nutrient medium for 2 weeks. Algal-available P in soil separates was determined by decreases in sediment inorganic P (Pi) over the incubation period. The initial concentrations of dissolved molybdate-reactive Pi (DMRP), Pi extractable with NaOH (NaOH-Pi), Pi extractable with HCl (HCl-Pi), organic P (Po, and total P increased with decreasing particle size. A higher proportion of Pi was HCl-extractable in fractions > 2 μm than in clay-size separates. The level of Paa in samples increased with decreasing particle size. Available P concentrations in separates < 0.2, 0.2–2, 2–50, > 50 μm and unfractionated samples averaged 447, 282, 113, 26 and 261 μg g?1, respectively. From 42 to 69% of the Pi and 20–37% of the total P in unfractioned samples was Paa. A lower proportion of Pi in the > 50 μm fraction was Paa than in the other size fractions (34 vs. 50%). There was no relationship between particle size and the proportion of total P that was available. The majority (> 84%) of Paa originated in the Pi fraction extractable with NaOH, whereas HCl-Pi only contributed small amounts of Paa. The proportion of initial NaOH-Pi assimilated by algae in 2 weeks ranged between 43 and 77%, whereas an average of 16% of HCl-Pi in separates was Paa. On average, a greater proportion of NaOH-Pi was assimilated by algae in samples from no-till plots as compared to those from chisel-plowed plots. 相似文献
We studied the effects of long-term exposure (nine years) of birch (Betula papyrifera) trees to elevated CO(2) and/or O(3) on reproduction and seedling development at the Aspen FACE (Free-Air Carbon Dioxide Enrichment) site in Rhinelander, WI. We found that elevated CO(2) increased both the number of trees that flowered and the quantity of flowers (260% increase in male flower production), increased seed weight, germination rate, and seedling vigor. Elevated O(3) also increased flowering but decreased seed weight and germination rate. In the combination treatment (elevated CO(2)+O(3)) seed weight is decreased (20% reduction) while germination rate was unaffected. The evidence from this study indicates that elevated CO(2) may have a largely positive impact on forest tree reproduction and regeneration while elevated O(3) will likely have a negative impact. 相似文献
Halogenated 1'methyl-1,2'-bipyrroles (MBPs) have been identified worldwide in marine mammals. Here we present the tentative identification of previously undetected MBP congeners in Delpinus delphis blubber using gas chromatography/electron capture negative ion mass spectrometry (GC/ECNI-MS) and comprehensive two-dimensional gas chromatography/time of flight mass spectrometry (GCxGC/TOF-MS). This is the first report of 26 congeners. The presence of numerous partially halogenated congeners suggests that they are either biosynthesized concomitantly with their perhalogenated counterparts or that their dehalogenation products can also bioaccumulate. The newly found compounds fit the geographic trend that has been previously noted. That is, samples from the Atlantic Ocean are dominated by the more brominated congeners while those from the Pacific are dominated by the more chlorinated congeners. 相似文献
Benzene is a carcinogenic and genotoxic pollutant which mainly affects the people health through the inhalation. Nevertheless,
this pollutant is not frequently measured by air-quality networks. To solve this problem, some models have been published
to estimate benzene concentrations in the atmosphere. However, the lack of measures makes difficult the application of complex
models in order to get a detailed spatio-temporal analysis, namely in urban areas. In this work was developed a simple semi-empirical
model to predict benzene concentrations based on the ratio of benzene and carbon monoxide concentrations in order to predict
the concentrations of this pollutant in large areas and periods with lack of benzene measurements but with higher impact in
the human health. The model was applied to an urban area, the Metropolitan Area of Oporto, for a period of 12 years (1995–2006).
Monthly correlations between benzene and carbon monoxide concentrations at Custóias air-quality station are significant (p = 0.01) and higher in winter (rs > 0.7) than in summer (0.3 > rs > 0.7). Estimate of the monthly ratio of the concentration of these two pollutants range between 199 and 305. The methodology
validation shows good results (rs = 0.81) which allow, assuming the availability of carbon monoxide data, the use of this tool for areas with low benzene recorded
data. The application of this methodology in the study area shows an annual average trend decrease of benzene concentrations
during the study period, which may be linked to a general trend decrease of benzene emissions in European urban areas, including
the study domain. 相似文献
The release of radioactivity into the atmosphere from the damaged Fukushima Daiichi nuclear power plant started on March 12th, 2011. Among the various radionuclides released, iodine -131 ((131)I) and cesium isotopes ((137)Cs and (134)Cs) were transported across the Pacific Ocean and reached the United States on 17-18 March 2011. Consequently, an elevated level of fission products (131)I, (132)I, (132)Te, (134)Cs and (137)Cs were detected in air, water, and milk samples collected across the United States between March 17 and April 4, 2011. The continuous monitoring of activities over a period of 25 days and spatial variations across more than 100 sampling locations in the United States made it possible to characterize the contaminated air masses. For the entire period, the highest detected activity values ranged from less than 1 m Bq m(-3) to 31 m Bq m(-3) for the particulate (131)I, and up to 96 m Bq m(-3) for the gaseous (131)I fraction. 相似文献