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41.
Nancy U. Schultz Albert Wilmarth 《Journal of the American Water Resources Association》1978,14(2):275-287
ABSTRACT: Section 208 of the Federal Water Pollution Control Act Amendments of 1972 has provided the Southwestern Illinois Metropolitan and Regional Planning Commission (SIMAPC) with a unique opportunity for comprehensive planning of the region's water quality. SIMAPC initiated the 208 study by researching available technology for the analysis of point and nonpoint sources of pollution and establishing criteria by which to judge the various technniques. This led to SIMAPC'S choice of continuous simulation of stream and reservoir water quality as the most appropriate analytical tool for their needs. A continuous simulation model was calibrated and verified on three basins in the SIMPAC region. It was then used to produce load source analysis, pollution event frequency analysis, and pollution event duration analysis for ten pollutants under existing stream conditions and then under alternative future conditions. These results enabled the weighting of pollutant sources, analysis of the effectiveness of control measures, and quantitative analysis of the marginal benefit of each alternative. 相似文献
42.
Albert Rango Arthur T. Anderson 《Journal of the American Water Resources Association》1974,10(5):1060-1081
ABSTRACT. The Spring 1973 Mississippi River flood was investigated using remotely sensed data from ERTS-1. Both manual and automatic analyses of the data indicate that ERTS-I is extremely useful as a regional tool for flood management. Quantitative estimates of area flooded were made in St. Charles County, Missouri and Arkansas. Flood hazard mapping was conducted in three study areas along the Mississippi River using pre-flood ERTS-1 imagery enlarged to 1:250,000 and 1:100,000 scale. The flood prone areas delineated on these maps correspond to areas that would be inundated by significant flooding (approximately the 100 year flood). The flood prone area boundaries were generally in agreement with flood hazard maps produced by the U. S. Army Corps of Engineers and U. S. Geological Survey although the latter are somewhat more detailed because of their larger scale. Initial results indicate that ERTS-1 digital mapping of flood prone areas can be performed at 1:62,500 which is comparable to some conventional flood hazard map scales. 相似文献
43.
A marked decline in the contribution by Marovo Lagoon to the annual total bêche-de-mer production of the Solomon Islands from
58% in 1989 to 17% in 2003 prompted investigation of their current biomass and diversity. We also assessed changes to critical
ecological services and the prospects for population recovery following a fisheries closure. Day time and nocturnal transects
revealed a mean abundance of 32.4 (SD = 5.3) low value species per ha (e.g. Holothuria atra, H. edulis, H. coluber and Thelenota anax) and 15.2 (SD = 2.7) high value species per ha (e.g. H. fuscogilva, Actinopyga lecanora, Stichopus hermanni and Thelenota ananas). Following a 17 month closure of the fishery (2005–2007), the abundance of bêche-de-mer was reported by local fisherman
to have increased; however, no scientific studies were conducted that can substantiate this community held belief. The current
study aimed to document the impact of re-opening the fishery in 2007 and documented a decline in high value species of 9%
over a 5 month period following the opening of the fishery, while low value species continued to increase in abundance by
11%, over the same period based on nocturnal surveys. Continued observation of the recovery, post closure, and any subsequent
harvest in Marovo will be required to properly understand population dynamics and provide a sustainable harvest plan for bêche-de-mer
in the future. 相似文献
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47.
The temporal pattern and dose-rate dependence of liver cancer in rats fed 2-fluorenylacetamide (2-FAA) was compared to analytical formulas derived from a specific model. The model was based on the idea that carcinogens have two distinct actions on cells: (1) transformation and (2) acceleration of progression. Transformed cells are by definition progressing toward cancer, but their rate of progression may depend on several factors, specifically, the amount of carcinogen. In the experiments the carcinogen was removed from the diet after various times and the rate of tumor progression was estimated from the time of tumor occurrence. The results were consistent with the idea that 2-FAA accelerated the progression of the cancers. The model provides a simple explanation of Druckrey's law in that the temporal occurrence of tumors induced by a carcinogen represents the acceleration of a naturally occurring disease progression. 相似文献
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49.
Heber AJ Ni JQ Lim TT Tao PC Schmidt AM Koziel JA Beasley DB Hoff SJ Nicolai RE Jacobson LD Zhang Y 《Journal of the Air & Waste Management Association (1995)》2006,56(10):1472-1483
Comprehensive field studies were initiated in 2002 to measure emissions of ammonia (NH3), hydrogen sulfide (H2S), carbon dioxide (CO2), methane (CH4), nonmethane hydrocarbons (NMHC), particulate matter <10 microm in diameter, and total suspended particulate from swine and poultry production buildings in the United States. This paper focuses on the quasicontinuous gas concentration measurement at multiple locations among paired barns in seven states. Documented principles, used in air pollution monitoring at industrial sources, were applied in developing quality assurance (QA) project plans for these studies. Air was sampled from multiple locations with each gas analyzed with one high quality commercial gas analyzer that was located in an environmentally controlled on-farm instrument shelter. A nominal 4 L/min gas sampling system was designed and constructed with Teflon wetted surfaces, bypass pumping, and sample line flow and pressure sensors. Three-way solenoids were used to automatically switch between multiple gas sampling lines with > or =10 min sampling intervals. Inside and outside gas sampling probes were between 10 and 115 m away from the analyzers. Analyzers used chemiluminescence, fluorescence, photoacoustic infrared, and photoionization detectors for NH3, H2S, CO2, CH4, and NMHC, respectively. Data were collected using personal computer-based data acquisition hardware and software. This paper discusses the methodology of gas concentration measurements and the unique challenges that livestock barns pose for achieving desired accuracy and precision, data representativeness, comparability and completeness, and instrument calibration and maintenance. 相似文献
50.
The location, nature, and size distribution of uranium-rich grains in sediment layers can be identified by sunbursts of etched particle tracks if each sample is pressed against a track detector, next irradiated with thermal neutrons, and the detectors then chemically etched to reveal fission tracks. The total track abundance from the sample is a measure of the 235U content; hence, if the bulk uranium (mostly 238U) has been measured, the two sets of results give the depletion or enrichment of the uranium. Sunbursts of tracks mark the locations of low-abundance, high-uranium grains allowing them to be singled out for further study. 相似文献