Recent studies have focused on the relationship between solute concentrations and discharge in streams, demonstrating that concentrations can vary little relative to changes in discharge (chemostatic behaviour). Chemostatic behaviour is dependent on catchment characteristics (e.g., lithology, geomorphology, and vegetation) and chemical characteristics of the solute (e.g., availability, reactivity, and mobility). An investigation of 3 springs and a stream near Los Alamos, NM, reveals that springs can behave in a chemostatic fashion as stream systems tend to do. Another unique finding of this study is that the anthropogenic contaminants barium and the high explosive RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) can also behave chemostatically.The chemostatic behaviour of a contaminant has important implications for the residence time of contaminants in a system as well as having a major control on contaminant flux and mass transport. Redox (reduction-oxidation) and biogeochemically sensitive analytes (e.g., Fe, SO 4 , and NO 3 ) display a combination of chemostatic and chemodynamic behaviour, showing the influence of temporally variable conditions on stream and spring chemistries.
This study demonstrates that containment of municipal and hazardous waste in arid and semiarid environments can be accomplished effectively without traditional, synthetic materials and complex, multi-layer systems. This research demonstrates that closure covers combining layers of natural soil, native plant species, and climatic conditions to form a sustainable, functioning ecosystem will meet the technical equivalency criteria prescribed by the U. S. Environmental Protection Agency.In this study, percolation through a natural analogue and an engineered cover is simulated using the one-dimensional, numerical code UNSAT-H. UNSAT-H is a Richards' equation-based model that simulates soil water infiltration, unsaturated flow, redistribution, evaporation, plant transpiration, and deep percolation. This study incorporates conservative, site-specific soil hydraulic and vegetation parameters. Historical meteorological data are used to simulate percolation through the natural analogue and an engineered cover, with and without vegetation.This study indicates that a 3-foot (ft) cover in arid and semiarid environments is the minimum design thickness necessary to meet the U. S. Environmental Protection Agency-prescribed technical equivalency criteria of 31.5 millimeters/year and 1 x 10 -7 centimeters/second for net annual percolation and average flux, respectively. Increasing cover thickness to 4 or 5 ft results in limited additional improvement in cover performance. 4This page intentionally left blank 5
This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, nor any of their contractors, subcontractors, or their employees, makes any warran@, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usehlness of any information, apparatus, product, or process disclosed, or represents that its use would not infkinge privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government, any agency thereof or any of their contractors or subcontractors. The views and opinions expressed herein do not necessarily state or reflect those of the United States Government, any agency thereof or any of their contractors.
A vegetation study was conducted in Technical Area 3 at Sandia National Laboratories, Albuquerque, New Mexico in 2003 to assist in the design and optimization of vegetative soil covers for hazardous, radioactive, and mixed waste landfills at Sandia National Laboratories/New Mexico and Kirtland Air Force Base. The objective of the study was to obtain site-specific, vegetative input parameters for the one-dimensional code UNSAT-H and to identify suitable, diverse native plant species for use on vegetative soil covers that will persist indefinitely as a climax ecological community with little or no maintenance.The identification and selection of appropriate native plant species is critical to the proper design and long-term performance of vegetative soil covers. Major emphasis was placed on the acquisition of representative, site-specific vegetation data. Vegetative input parameters measured in the field during this study include root depth, root length density, and percent bare area. Sitespecific leaf area index was not obtained in the area because there was no suitable platform to measure leaf area during the 2003 growing season due to severe drought that has persisted in New Mexico since 1999. Regional LAI data was obtained from two unique desert biomes in New Mexico, Sevilletta Wildlife Refuge and Jornada Research Station. structure; soft, very friable; many very fine and fine roots and interstitial pores; moderately alkaline; abrupt smooth boundaries. B Horizon10 to 33 cm: Brown sandy clay loam (in the general description of the B Horizon, the Madurez Series can also be heavy sandy loam, light clay loam, heavy fine sandy loam, or light sandy clay loam); weak, coarse, sub-angular blocky structure; hard, friable, sticky and plastic; many very fine and fine roots and interstitial pores; moderately alkaline; clear, smooth boundaries.33 to 53 cm: Light brown heavy fine sandy loam (in the general description of the B Horizon, the Madurez Series can also be heavy sandy loam, light clay loam, heavy fine sandy loam, or light sandy clay loam); weak, coarse, sub-angular blocky structure; hard, friable, sticky and plastic; common very fine and fine roots and interstitial pores; moderately calcareous; moderately alkaline; clear, smooth boundary. C Horizon53 to 89 cm: Pink heavy sandy loam (in the general description of the C Horizon, the Madurez Series can also be sandy clay loam, light clay loam, heavy fine sandy loam or light sandy clay loam); massive; hard, friable, sticky and plastic; few very fine roots and interstitial pores; moderately calcareous; moderately alkaline; clear smooth boundary.89 to 130 cm: Pinkish gray sandy loam (in the general description of the C Horizon, the Madurez Series can also be sandy clay loam, light clay loam, heavy fine sandy loam or light sandy clay loam); massive; hard, friable, slightly sticky and slightly plastic; strongly calcareous; moderately alkaline; gradual smooth boundaries.130 to 152 cm: Light brown sandy loam (in the general description of the C Horizon, the Madurez Series can ...
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