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481.
This paper examines the rate of degradation of food waste in a leach bed reactor (LBR) under four different operating conditions. The effects of leachate recirculation at a low and high flow rate are examined with and without connection to an upflow anaerobic sludge blanket (UASB). Two dilution rates of the effective volume of the leach bed reactors were investigated: 1 and 6 dilutions per LBR per day. The increase in dilution rate from 1 to 6 improved the destruction of volatile solids without connection to the UASB. However connection to the UASB greatly improved the destruction of volatile solids (by almost 60%) at the low recirculation rate of 1 dilution per day. The increase in volatile solids destruction with connection to the UASB was attributed to an increase in leachate pH and buffering capacity provided by recirculated effluent from the UASB to the leach beds. The destruction of volatile solids for both the low and high dilution rates was similar with connection to the UASB, giving 82% and 88% volatile solids destruction respectively. This suggests that the most efficient leaching condition is 1 dilution per day with connection to the UASB. 相似文献
482.
Walter W. Heck Allen S. Heagle 《Journal of the Air & Waste Management Association (1995)》2013,63(2):97-99
With newly developed monitoring techniques, investigators used the sensitive tobacco variety, Bel-W3, as a monitor for photochemical air pollution at different locations within 75 miles of Cincinnati, Ohio. Observations during the summers of 1966 through 1968 revealed almost daily injury to monitoring plants, fairly uniform total seasonal injury at all locations, and a marked variation in both oxidant and injury from one season to another within the city. The relationship between oxidant level and injury was not found to be consistent. 相似文献
483.
In Florida, more than half of the state’s sandy beach coastlines are designated as critical erosion areas by the Florida Department
of Environmental Protection (FDEP 2008). At the same time, the economic contribution of coastal construction is being confounded by the fiscal peril facing Florida
(Bird in Ann Geomorph 57:1–9, 1985, Pew Center on the States 2009, U.S BEA 2009). It is therefore an opportune time for an evaluation of coastal erosion policy response which specifically addresses coastal
construction. Furthermore in Florida, an increasing coastal population requiring the provision of structural development necessitates
an improved understanding of how legislative intent which avoids the cumulative impacts of development is translated through
quantified policy response. This study characterizes how coastal development trends in Florida have responded to critical
erosion designation. Using spatial and temporal analysis of coastal construction permitting data from 1987 to 2007, three
coastal counties in northwest Florida were selected for this study. This selection was based on proximity to the designated
ecologically sensitive Apalachicola National Estuarine Research Reserve (ANERR). This study has indicated that clusters of
development have not been reduced or redirected by critical erosion designation in certain areas of the study counties. Therefore
this study has implications for the regulatory framework governing coastal development permitting in Florida, which is of
timely relevance for sea-level rise adaptation. 相似文献
484.
485.
486.
Xiaobin Liao Joshua M. Allen Caroline O. Granger Susan D. Richardson 《环境科学学报(英文版)》2022,34(7):264-275
Halogenated disinfection byproducts (DBPs) are an unintended consequence of drinking water disinfection, and can have significant toxicity. XAD resins are commonly used to extract and enrich trace levels of DBPs for comprehensive, nontarget identification of DBPs and also for in vitro toxicity studies. However, XAD resin recoveries for complete classes of halogenated DBPs have not been evaluated, particularly for low, environmentally relevant levels (ng/L to low µg/L). Thus, it is not known whether levels of DBPs or the toxicity of drinking water might be underestimated. In this study, DAX-8/XAD-2 layered resins were evaluated, considering both adsorption and elution from the resins, for extracting 66 DBPs from water. Results demonstrate that among the 7 classes of DBPs investigated, trihalomethanes (THMs), including iodo-THMs, were the most efficiently adsorbed, with recovery of most THMs ranging from 50%-96%, followed by halonitromethanes (40%-90%). The adsorption ability of XAD resins for haloacetonitriles, haloacetamides, and haloacetaldehydes was highly dependent on the individual species. The adsorption capacity of XAD resins for haloacetic acids was lower (5%-48%), even after adjusting to pH 1 before extraction. Recovery efficiency for most DBPs was comparable with their adsorption, as most were eluted effectively from XAD resins by ethyl acetate. DBP polarity and molecular weight were the two most important factors that determine their recovery. Recovery of trichloromethane, iodoacetic acid, chloro- and iodo-acetonitrile, and chloroacetamide were among the lowest, which could lead to underestimation of toxicity, particularly for iodoacetic acid and iodo-acetonitrile, which are highly toxic. 相似文献
487.
The Gulf Coast Aerosol Research and Characterization Study ([GC-ARCH], also known as the Houston Fine Particulate Matter [PM] Supersite) examined the spatial and temporal variability in fine PM source contributions and composition and the physical and chemical processes that govern PM formation and transformation in southeastern Texas. This was accomplished through the analysis of data collected in a 16-month field sampling program (August 2000 through November 2001). Three core sites and approximately 15 peripheral sites, jointly operated by the study team and the Texas Commission on Environmental Quality (TCEQ), were used. Key scientific findings related to spatial and temporal variability in fine PM concentrations, sizes and composition of the fine PM, the strength of primary emission sources and causes of secondary fine PM formation are reported. 相似文献
488.
Edwards R Smith KR Kirby B Allen T Litton CD Hering S 《Journal of the Air & Waste Management Association (1995)》2006,56(6):789-799
In developing countries, high levels of particle pollution from the use of coal and biomass fuels for household cooking and heating are a major cause of ill health and premature mortality. The cost and complexity of existing monitoring equipment, combined with the need to sample many locations, make routine quantification of household particle pollution levels difficult. Recent advances in technology, however, have enabled the development of a small, portable, data-logging particle monitor modified from commercial smoke alarm technology that can meet the needs of surveys in the developing world at reasonable cost. Laboratory comparisons of a prototype particle monitor developed at the University of California at Berkeley (UCB) with gravimetric filters, a tapered element oscillating microbalance, and a TSI DustTrak to quantify the UCB particle monitor response as a function of both concentration and particle size and to examine sensor response in relation to changes in temperature, relative humidity, and elevation are presented here. UCB particle monitors showed good linearity in response to different concentrations of laboratory-generated oleic acid aerosols with a coarse (mass median diameter, 2.1 microm) and fine (mass median diameter, 0.27-0.42 microm) size distributions (average r2 = 0.997 +/- 0.005). The photoelectric and ionization chamber showed a wide range of responses based on particle size and, thus, require calibration with the aerosol of interest. The ionization chamber was five times more sensitive to fine rather than coarse particles, whereas the photoelectric chamber was five times more sensitive to coarse than fine. The ratio of the response between the two sensors has the potential for mass calibration of individual data points based on estimated parameters of the size distribution. The results demonstrate the significant potential of this monitor, which will facilitate the evaluation of interventions (improved fuels, stoves, and ventilation) on indoor air pollution levels and research on the impacts of indoor particle levels on health in developing countries. 相似文献
489.
At the new Marais des Cygnes National Wildlife Refuge in Linn County, Kansas, and Bates County, Missouri, USA, we evaluated
long-lived contaminants before acquisition of the land for the refuge. We sampled sediments at 16 locations and fish at seven
locations. The samples were analyzed for metals and for chlorinated hydrocarbon compounds. Selected sediment samples also
were analyzed for aliphatic hydrocarbons. Arsenic concentrations in sediment samples from six locations were elevated compared
to US norms, but arsenic was not detected in any fish composite. Mercury concentrations in largemouth bass from two locations
were comparable to the 85th percentile concentrations in nationwide fish collections. Most sediment concentrations of other
metals were unlikely to have detrimental effects on biota. No chlorinated hydrocarbons were detected in any sediment sample.
Chlordane compound concentrations in fish composites from two sites at the eastern end of the sampling area were 0.127 and
0.228 μg/g wet weight, respectively, which are high enough to cause concern. Most aliphatic hydrocarbons detected were found
at low concentrations and probably were natural in origin. We concluded that there are no serious contaminants concerns within
the project area, but past use of arsenical pesticides may mean a legacy of elevated soil arsenic levels in parts of the area
and some use of banned pesticides such as chlordane and DDT likely is still occurring near the refuge. 相似文献
490.