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71.
Lorne G. Everett Edward W. Hoylman L. Graham Wilson Leslie G. McMillion 《Ground Water Monitoring & Remediation》1984,4(1):26-32
Traditional monitoring methods using chemical analysis of ground water samples to detect pollutant migration are being superseded or used in conjunction with innovative approaches. A need to detect pollutants before they reach the water table has drawn interest to vadose (unsaturated) zone monitoring and brought together hydrogeologists, soil scientists and agricultural engineers who have been working on this subject for years.
Recent studies have identified over 50 different types of vadose zone monitoring devices and methods that have optimum utility in varying hydrogeologic settings. In general, measurements made in the vadose zone are trying to define storage, transmission of liquid waste in terms of flux and velocity, and pollutant mobility.
Criteria for the selection of alternative vadose zone monitoring methods are important for the development of site-specific systems. These criteria include: type of site; applicability to new, active, and abandoned sites; power requirements; depth limitations; multiple use capability; type of data collection system; reliability and life expectancy; degree of operational complexity; direct versus indirect methods; applicability to alternate media; effect on flow regime; and effect of hazardous waste on sampling or measurements. Application of the selection criteria is discussed in Everett et al. (1982a). 相似文献
Recent studies have identified over 50 different types of vadose zone monitoring devices and methods that have optimum utility in varying hydrogeologic settings. In general, measurements made in the vadose zone are trying to define storage, transmission of liquid waste in terms of flux and velocity, and pollutant mobility.
Criteria for the selection of alternative vadose zone monitoring methods are important for the development of site-specific systems. These criteria include: type of site; applicability to new, active, and abandoned sites; power requirements; depth limitations; multiple use capability; type of data collection system; reliability and life expectancy; degree of operational complexity; direct versus indirect methods; applicability to alternate media; effect on flow regime; and effect of hazardous waste on sampling or measurements. Application of the selection criteria is discussed in Everett et al. (1982a). 相似文献
72.
73.
The prediction of two cases of severe convection: implications for forecast guidance 总被引:1,自引:0,他引:1
Summary Severe convection in the Sydney basin regularly produces destructive winds, heavy rain or flash flooding, and damage from
large hail. Such convective activity is a major forecasting challenge for the Sydney basin, especially during the October
to April warm season. There presently is a need to provide timely, accurate and reliable numerical guidance to supplement
the current probabilistic convective outlooks, issued by the operational forecasters. Initial work has been carried out that
examines two cases of severe convection in the Sydney basin. The performance of a very high resolution (2 km) numerical weather
prediction (NWP) model is assessed in terms of how well it performed in providing guidance on heavy rainfall and hail, as
well as other key mesoscale phenomena such as low level convergence lines. The model results discriminated well between severe
convection that actually did occur in the first case (1 December, 2000) and the failure of severe convection to develop in
the second case (8 December, 2000). The operational forecasters predicted severe convection to occur in both cases. It is
now planned to take the next step of augmenting the quasi-subjective approach of the operational forecasters with the NWP
guidance to provide an enhanced capacity to forecast severe convection in the Sydney basin.
Received October 20, 2001 Revised December 28, 2001 相似文献
74.
K. Onder Cetin T. Leslie Youd Raymond B. Seed Jonathan D. Bray Rodolfo Sancio W. Lettis M. Tolga Yilmaz H. Turan Durgunoglu 《Soil Dynamics and Earthquake Engineering》2002,22(9-12):1083-1092
This paper presents a study of liquefaction-induced ground deformations at the Hotel Sapanca site during the 1999 Kocaeli (Izmit)—Turkey earthquake. The paper discusses: (1) observed ground deformations and displacements after the earthquake, (2) the results of field investigations by means of borings and in situ index tests including standard penetration tests (SPT), static cone penetration tests (CPT) and piezocone (CPTU) tests, (3) analyses of observed ground settlements and lateral deformations by a suite of methods, and (4) comparisons of observed and calculated ground movements. 相似文献
75.
Heidi E. Kretser Elliot Dale Leslie Karasin Liba Pejchar Sarah E. Reed 《社会与自然资源》2019,32(9):1021-1039
Conservation Development (CD) is a land-use tool to reduce the impacts of development on natural resources, yetthe use of CD is highly variable. We used a collaborative conservation model to examine factors influencing adoption and implementation to improve the future application of CD. We interviewed 2–3 individuals including planners, board members, and developers (n?=?46) from 16 rural communities in the intermountain west and northeast U.S. Motivations to preserve rural character or comply with state statutes drove adoption. Greater capacity such as outside expertise, model regulations, and iterative revisions of ordinances was associated with stronger ordinances. Adoption processes including ample dialog across diverse constituents, especially those overseeing subdivision development, facilitated higher rates of implementation. Concerns over open space management, lack of successful CD examples, and inexperience with CD posed barriers to implementation. Understanding social context revealed the strengths and shortcomings of CD and provided guidance for strategically engaging communities in private lands conservation. 相似文献
76.
Laura McFarlane Tranquilla April Hedd Chantelle Burke William A. Montevecchi Paul M. Regular Gregory J. Robertson Leslie Ann Stapleton Sabina I. Wilhelm David A. Fifield Alejandro D. Buren 《Estuarine, Coastal and Shelf Science》2010
Ocean climate change is having profound biological effects in polar regions. Such change can also have far-reaching downstream effects in sub-polar regions. This study documents an environmental relationship between High Arctic sea ice changes and mortality events of marine birds in Low Arctic coastal regions. During April 2007 and March 2009, hundreds of beached seabird carcasses and moribund seabirds were found along the east and northeast coasts of Newfoundland, Canada. These seabird “wrecks” (i.e. dead birds on beaches) coincided with a period of strong, persistent onshore winds and heavily-accumulated sea ice that blocked bays and trapped seabirds near beaches. Ninety-two percent of wreck seabirds were Thick-billed Murres (Uria lomvia). Body condition and demographic patterns of wreck murres were compared to Thick-billed Murres shot in the Newfoundland murre hunt. Average body and pectoral masses of wreck carcasses were 34% and 40% lighter (respectively) than shot murres, indicating that wreck birds had starved. The acute nature of each wreck suggested that starvation and associated hypothermia occurred within 2–3 days. In 2007, first-winter murres (77%) dominated the wreck. In 2009, there were more adults (78%), mostly females (66%). These results suggest that spatial and temporal segregation in ages and sexes can play a role in differential survival when stochastic weather conditions affect discrete areas where these groups aggregate. In wreck years, southward movement of Arctic sea ice to Low Arctic latitudes was later and blocked bays longer than in most other years. These inshore conditions corresponded with recent climate-driven changes in High Arctic ice break-up and ice extent; coupled with local weather conditions, these ice conditions appeared to be the key environmental features that precipitated the ice-associated seabird wrecks in the Low Arctic region. 相似文献
77.
The Nopal I uranium (U) deposit, in the Pefia Blanca District, Chihuahua, Mexico, has been identified as analogous in some regards to the candidate U.S. high-level waste (HLW) repository at Yucca Mountain, Nevada. Uranium transport at the Nopal I deposit has been studied to investigate mechanisms by which HLW components could be transported through silicic tuff over long time periods. This investigation focused on approximately 1400 m2 of essentially continuous bedrock outcrop spanning the Nopal I deposit and surrounding host tuff. Data collected document: (i) the distributions of U within and around the Nopal I deposit, (ii) the distribution and characteristics of the fracture network within and surrounding the deposit, and (iii) the transport of U away from the deposit mainly along fracture paths. Uranium-series isotopic measurements indicate mobilization of U along the margin of the deposit within the last 1 Ma and significant U transport at about 54 Ka. Transport of U away from the Nopal I deposit along a few relatively continuous mesofractures achieved maximum distances at least 20 times greater than transport through the general fracture network composed of thousands of less continuous microfractures within and surrounding the deposit. Uranium transport away from the deposit appears to be largely independent of variations in the general fracture network pattern. Transport of U away from individual micro- and meso-fractures into homogeneous, unfractured tuff matrix appears limited to distances less than 1 mm. At the Nopal I deposit, matrix diffusion does not appear to have been an important factor for retardation of U. This analysis suggests a ranking for U retention: (i) microfracture network retention mesofracture retention, and (ii) individual microfracture retention matrix retention. 相似文献
78.
Daniel G. Strawn Patrick Hickey Andrew Knudsen Leslie Baker 《Environmental Geology》2007,52(1):109-122
To remediate Pb contaminated soils it is proposed that phosphorus can be amended to the soils to transform the Pb into poorly
soluble Pb-phosphate mineral phases. However, remediation strategies must account for variable Pb speciation and site-specific
factors. In this study soil mineralogy and Pb speciation in soils from P-amended field trials at sites within the Coeur d’Alene
River Basin in Idaho, USA were investigated. The soils are contaminated from mining activities and are enriched with Fe and
Mn. Selective extraction of the soils indicated that the Fe oxides are poorly crystalline. XRD of the soil clay size fractions
identified quartz, muscovite, kaolinite, siderite, lepidocrocite, and chlorite minerals. Amendment with P fertilizer dissolved
the siderite. No Pb–phosphate minerals were detected by XRD. Electron microprobe analysis showed direct correlations between
Pb, Fe, and Mn in the unamended soils, and negative correlations between Pb and Si. Lead and Mn were strongly correlated.
In the amended soils Fe and P were strongly correlated. Results indicate that the Pb is associated with poorly crystalline
Fe and Mn oxides, and that added P is primarily associated with Fe oxide phases. Comparisons of pore water Pb concentrations
with chloropyromorphite and plumbogummite solubility suggest that in the phosphate-amended soils the pore waters are undersaturated
in these phases, whereas several of the control soil pore waters were oversaturated, indicating the added phosphate suppressed
the Pb solubility. Results from this research provide insight into the geochemistry occurring in the P-remediated soils that
will help in making management and remediation decisions. 相似文献
79.
80.