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981.
R. J. Larson E. A. Bookland R. T. Williams K. M. Yocom D. A. Saucy M. B. Freeman G. Swift 《Journal of Polymers and the Environment》1997,5(1):41-48
The biodegradability (mineralization to carbon dioxide) of acrylic acid oligomers and polymers was studied in activated sludge
obtained from continuous-flow activated sludge (CAS) systems exposed to mixtures of low molecular weight (Mw < 8000) poly(acrylic
acid)s and other watesoluble polymers [poly(ethylene glycol)s] in influent wastewater. Dilute preparations of activated sludge
from the CAS units were tested for their ability to mineralize acrylic acid monomer and dimer, as well as a series of model
acrylic acid oligomers and polymers (Mw 500, 700, 1000, 2000, and 4500), as sole carbon and energy sources. Complete mineralization
of acrylic acid monomer and dimer was observed in low-biomass sludge preparations previously exposed to the polymer mixture,
based on carbon dioxide production and residual dissolved organic carbon analyses. Extensive (though incomplete) degradation
was also observed for the low molecular weight acrylic acid oligomers (Mw 500 and 700), but degradation dropped off sharply
for the 1000, 2000, and 4500 Mw polymers. Radiochemical (14C) data also confirmed the low degradation potential of the 1000, 2000, and 4500 Mw materials. Degradation of two commercial
poly(ethylene glycol)s at 1000 and 3400 Mw was complete and comparable to that of the acrylic acid monomer and dimer. Our
results indicate that mixed populations of activated sludge microorganisms can extensively metabolize acrylic acid oligomers
of seven units or less. Complete mineralization, however, could be confirmed only for the monomer and dimer material, and
carbon mass balance data suggested that the true molecular weight cutoff for complete biodegradation was significantly less
than the 500–700 Mw range tested. 相似文献
982.
Robert Johnson John Quinn Lisa Durham Gustavious Williams Albert Robbat 《补救:环境净化治理成本、技术与工艺杂志》1997,7(3):81-96
Adaptive sampling and analysis programs (ASAPs) provide a cost-effective alternative to traditional sampling program designs. ASAPs are based on field analytical methods for rapid sample turnaround and field-based decision support for guiding the progress of the sampling program. One common objective of ASAPs is to delineate contamination present in soils, either to support feasibility studies or remedial action designs. An ASAP based on portable gas chromatograph/ mass spectrograph (GC/MS) technologies developed at Tufts University combined with decision support tools created at Argonne National Laboratory was used to delineate explosives contamination in soils at Joliet Army Ammunition Plant, Joliet, Illinois. Tufts' GC/MS technologies provided contaminant-specific identification and quantification with rapid sample turnaround and high sample throughput. Argonne's decision support tools estimated contamination extent, determined the uncertainty associated with those estimates, and indicated where sampling should continue to minimize uncertainty. In the case of Joliet, per sample analytical costs were reduced by 75 percent as compared to the cost of off-site laboratory analyses for explosives. The use of an ASAP resulted in a much more accurate identification and delineation of contaminated areas than a traditional sampling program would have with the same number of samples collected on a regular grid. While targeting explosives contamination in soils at Joliet, the ASAP technologies used in this demonstration have much broader application. 相似文献
983.
Bahram Momen Larry W. Eichler Charles W. Boylen Jonathan P. Zehr 《Environmental management》1997,21(5):725-732
a (Chl a), silica (Si), and chloride (Cl) through the use of proper statistical techniques. Results indicate no statistically significant
changes in the concentrations of TP, Chl a, or Si in the spring or summer from 1981 to 1993. A significant temporal trend of increase in Cl concentration is, however,
detected. This is perhaps the strongest evidence that the development of the Lake George watershed has affected lakewater
chemistry. In spring, the concentrations of TP, Chl a, Si, and Cl, averaged over all 13 years, were higher in the south basin, but differences are not statistically significant
(i.e., P > 0.05). In summer, Si was slightly but significantly lower, and Cl was nonsignificantly higher in the south basin. Significant
interactions between temporal and spatial changes are detected based only on summer values of TP and Chl a, indicating differential trends of change for these two variables in the south and north basins during the last 13 years. 相似文献
984.
Charles S. ReVelle Justin C. Williams John J. Boland 《Environmental Modeling and Assessment》2002,7(2):57-59
Introduction
Introduction to the Special Issue 相似文献985.
Normality transformations for environmental data from compound normal-lognormal distributions 总被引:1,自引:0,他引:1
Larry G. Blackwood 《Environmental monitoring and assessment》1995,35(1):55-75
The combination of lognormally distributed quantities of interest with normally distributed random measurement error produces
data that follow a compound normal-lognormal (NLN) distribution. When the measurement error is large enough, such data do
not approximate normality, even after a logarithmic transformation. This paper reports the results of a search for a transformation
method for NLN data that is not only technically appropriate, but easy to implement as well. Three transformation families
were found to work relatively well. These families are compared in terms of success in achieving normality and robustness,
using simulated NLN data and actual environmental data believed to follow a NLN distribution. The exponential family of transformations
was found to give the best overall results.
This work was supported by the U.S. Department of Energy, Office of Environmental Restoration and Waste Management, under
DOE Idaho Field Office Contract DE-AC07-76ID01570. 相似文献
986.
James E. Davis Edwin R. Stevens Donald C. Staiff Larry C. Butler 《Environmental monitoring and assessment》1983,3(1):23-28
Applicators applying diazinon to yards were monitored to determine potential exposures received while using this commonly available pesticide around the home. Diazinon was applied to lawns and shrubs using compressed air or hose-end sprayers. Even with minimal clothing, the largest mean exposure received during any of the applications was estimated to be less than 0.2% of a lethal dose per hour. Exposure to the hands accounted for 85% or more of the total exposure, so simply protecting the hands would have essentially eliminated exposure. 相似文献
987.
Larry G. Blackwood 《Environmental monitoring and assessment》1992,21(3):193-210
The lognormal distribution has become a common choice to represent intrinsically positive and often highly skewed environmental data in statistical analysis. However the implications of its use are often not carefully considered. With an emphasis on radiological monitoring applications, this paper reviews what assuming lognormality means in terms of data analysis and interpretation. The relationship of using normal theory methods on log transformed data to multiplicative errors and hypothesis testing in the original scale is also discussed.Work performed under the auspices of the U.S. Department of Energy, DOE Contract No. DE-AC-07-76ID01570. 相似文献
988.
The use of phytotoxicity tests (common duckweed,cabbage, and millet) for determining effluent toxicity 总被引:2,自引:0,他引:2
The objective of this study was to use higher plants for detecting effluent toxicity. Eight effluent samples were obtained from three industrial sources prior to their entry into a sewer system. The tests were the duckweed reproduction test, and root growth tests using cabbage and millet. The results of repeated phytotoxicity tests were reproducible. Of the three industrial sources, the effluent samples from a specialty chemical industry were the most toxic. For two samples from this source, the IC50 values (the concentrations which caused 50% inhibitory effect) for duckweed were less than 1.6% effluent concentration. The samples from an agricultural product utilization plant were the least toxic. For these samples, root growth tests failed to obtain IC50 values while the duckweed tests showed IC50 values of 91 and 43% effluent concentration. Among the three types of tests conducted, the duckweed reproduction test showed the greatest sensitivity to effluent toxicity, while root growth tests using cabbage and millet had mixed results. Duckweed is recommended as a part of a battery of tests for effluent toxicity. 相似文献
989.
L. R. Williams R. W. Leggett M. L. Espegren C. A. Little 《Environmental monitoring and assessment》1989,12(1):83-96
There are thousands of properties in the United States on which the soil has been contaminated to some degree with uranium mill tailings. An effort is now underway by the United States Department of Energy to identify sites contaminated with tailings and to perform remedial action when 226Ra levels exceed current guidelines. Because of the large number of sites involved, it is imperative that sample collection be performed in a cost-effective manner. In this paper we describe the results of a study in which we compared the efficiencies of different methods of sample collection in order to determine an optimal method for estimating the mean 226Ra concentration in soil. The study involved a field experiment in which extensive sampling was performed on sites known to be contaminated with uranium tailings. The experiment was designed to identify the advantages and limitations of composite sampling, the relative merits of random and uniformly spaced sample collection, the use of field gamma measurements for supplementing and reducing soil sample collection, and practical levels of accuracy and precision that can be obtained. Conclusions regarding gamma measurements are unique to 226Ra contamination. On the other hand, conclusions concerning composite sampling and random versus uniformly spaced sampling may depend primarily on the way the contamination was spread by man and hence may not be unique to 226Ra.Research sponsored by the Department of Remedial Action Projects, Office of Terminal Waste Disposal, U. S. Department of Energy under contract DE-AC05-84OR21400 with the Martin Marietta Energy Systems, Inc.ORNL—Grand Junction Office, Grand Junction, Colorado. 相似文献
990.
McFarland CN Bendell-Young LI Guglielmo C Williams TD 《Journal of environmental monitoring : JEM》2002,4(5):791-795
Cadmium content was measured in kidney, liver and tarsus bones of western sandpipers (Calidris mauri) at a temperate migratory stopover site (Fraser Delta, British Columbia, Canada) and a wintering site (Playa el Agallito, Chitre, Panama) over a two year period. Cadmium content in liver and kidney was age and sex dependent. Adult females generally had lower kidney and liver cadmium than adult males (P < 0.05), but a sex difference was not detected in juveniles. Cadmium increased with age in kidney, liver and to a lesser extent in bone (P < 0.001) with average "steady-state" kidney and liver content being reached within the sandpipers first year. In general, tissue cadmium residues in adult males and females were independent of sampling location although for bone, site-specific differences did occur (P < 0.001). Bone cadmium was lower in females sampled from their wintering grounds as compared to temperate stopover sites suggesting that bone cadmium may be mobilized during periods of feather molt. Comparison of cadmium residues among sandpipers of increasing age suggest that exposure is occurring along the Pacific Coast, at stopover sites as the birds migrate north to Alaska and south to Panama. This study points to the importance of considering the ecology of the species (e.g., in this case migratory behavior) in interpreting trace metal residues. 相似文献