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101.
John Jansen Bassem Haddad Wayne Fassbender Patrick Jurcek 《Ground Water Monitoring & Remediation》1992,12(4):103-109
A frequency domain electromagnetic induction sounding survey (FDEM) was conducted on a landfill in northern Illinois to determine the depth of fill, locate areas of drum disposal, and locate areas of heavy metal sludge disposal. Sketchy information obtained from interviews of the site personnel identified specific exploration targets and areas of concern. The results of the geophysical survey verified much of the reported disposal history and identified areas suspected to contain hazardous waste.
Based on the results of the survey, the thickness of fill was estimated and two areas with highly conductive fill were located. These areas could represent leachate pockets or sludge disposal areas. An area in which the fill appears to be thicker than expected was identified. This area is thought to represent industrial sludge disposal in trenches excavated into the existing fill and underlying soils. An area with several linear in-phase, quadrature, and conductivity highs was detected. A subsequent magnetometer survey detected linear magnetic anomalies that are believed to be caused by parallel trenches filled with steel drums. This area is believed to be a previously unreported hazardous waste drum disposal cell excavated into the native soil.
As of this writing, the results of this survey have not been verified by traditional intrusive methods. When these investigations begin, we expect that information provided by the FDEM survey will reduce project costs by directing subsequent investigations, thereby reducing the number of borings and test pits required to characterize the site. While there is an unavoidable margin of error and uncertainty in remote sensing methods, the subsurface coverage provided by this geophysical survey could not have been reproduced by traditional methods without substantial expense. This paper presents the results of the survey and discusses application of the FDEM method on landfills. 相似文献
Based on the results of the survey, the thickness of fill was estimated and two areas with highly conductive fill were located. These areas could represent leachate pockets or sludge disposal areas. An area in which the fill appears to be thicker than expected was identified. This area is thought to represent industrial sludge disposal in trenches excavated into the existing fill and underlying soils. An area with several linear in-phase, quadrature, and conductivity highs was detected. A subsequent magnetometer survey detected linear magnetic anomalies that are believed to be caused by parallel trenches filled with steel drums. This area is believed to be a previously unreported hazardous waste drum disposal cell excavated into the native soil.
As of this writing, the results of this survey have not been verified by traditional intrusive methods. When these investigations begin, we expect that information provided by the FDEM survey will reduce project costs by directing subsequent investigations, thereby reducing the number of borings and test pits required to characterize the site. While there is an unavoidable margin of error and uncertainty in remote sensing methods, the subsurface coverage provided by this geophysical survey could not have been reproduced by traditional methods without substantial expense. This paper presents the results of the survey and discusses application of the FDEM method on landfills. 相似文献
102.
103.
Denis Lacelle Alfonso F. Davila Wayne H. Pollard Dale Andersen Jennifer Heldmann Margarita Marinova Christopher P. McKay 《Earth and Planetary Science Letters》2011,301(1-2):403-411
To date, studies of the stability of subsurface ice in the McMurdo Dry Valleys of Antarctica have been mainly based on climate-based vapor diffusion models. In University Valley (1800 m), a small glacier is found at the base of the head of the valley, and adjacent to the glacier, a buried body of massive ice was uncovered beneath 20–40 cm of loose cryotic sediments and sandstone boulders. This study assesses the origin and stability of the buried body of massive ice by measuring the geochemistry and stable O–H isotope composition of the ice and applies a sublimation and molecular diffusion model that accounts for the observed trends. The results indicate that the buried massive ice body represents an extension of the adjacent glacier that was buried by a rock avalanche during a cold climate period. The contrasting δ18O profiles and regression slope values between the uppermost 6 cm of the buried massive ice (upward convex δ18O profile and SD-18O = 5.1) and that below it (progressive increase in δ18O and SD-18O = 6.4) suggest independent post-depositional processes affected the isotope composition of the ice. The upward convex δ18O profile in the uppermost 6 cm is consistent with the ice undergoing sublimation. Using a sublimation and molecular diffusion model, and assuming that diffusion occurred through solid ice, the sublimation rate needed to fit the measured δ18O profile is 0.2 ? 10? 3 mm yr? 1, a value that is more similar to net ice removal rates derived from 3He data from cobbles in Beacon Valley till (7.0 ? 10? 3 mm yr? 1) than sublimation rates computed based on current climate (0.1–0.2 mm yr?1). We suggest that the climate-based sublimation rates are offset due to potential ice recharge mechanisms or to missing parameters, particularly the nature and thermo-physical properties of the overlying sediments (i.e., temperature, humidity, pore structure and ice content, grain size). 相似文献
104.
The patterns of concentration of dissolved free amino acids (DFAA) are different and more variable in pore water of soils from a Georgia salt marsh than in most surface waters. Elevated concentrations of DFAA (up to 8850 nmoles liter?1) and high relative levels of alanine and glutamic acid suggest that bacteria may produce these amino acids. In addition to the common protein amino acids, an unidentified compound was present and was the dominant free amino acid in some sections. This compound appeared to be specific to pore waters as it was not observed in surface waters or in hydrolysates of sediments, bacteria or plants from the marsk. 相似文献
105.
U-Pb isotopic analyses of eight single and multi-grain zircon fractions separated from a syenite of the Diana Complex of the
Adirondack Mountains do not define a single linear array, but a scatter along a chord that intersects the Concordia curve
at 1145 ± 29 and 285 ± 204 Ma. For the most concordant analyses, the207Pb/206Pb ages range between 1115 and 1150 Ma. Detailed petrographic studies revealed that most grains contained at least two phases
of zircon growth, either primary magmatic cores enclosed by variable thickness of metamorphic overgrowths or magmatic portions
enclosing presumably older xenocrystic zircon cores. The magmatic portions are characterized by typical dipyramidal prismatic
zoning and numerous black inclusions that make them quite distinct from adjacent overgrowths or cores when observed in polarizing
light microscopy and in backscattered electron micrographs. Careful handpicking and analysis of the “best” magmatic grains,
devoid of visible overgrowth of core material, produced two nearly concordant points that along with two of the multi-grain
analyses yielded an upper-intercept age of 1118 ± 2.8 Ma and a lowerintercept age of 251 ± 13 Ma. The older age is interpreted
as the crystallization age of the syenite and the younger one is consistent with late stage uplift of the Appalachian region.
The 1118 Ma age for the Diana Complex, some 35 Ma younger than previously believed, is now approximately synchronous with
the main Adirondack anorthosite intrusion, implying a cogenetic relationship among the various meta-igneous rocks of the Adirondacks.
The retention of a high-temperature contact metamorphic aureole around Diana convincingly places the timing of Adirondack
regional metamorphism as early as 1118 Ma. This result also implies that the sources of anomalous hightemperature during granulite
metamorphism are the syn-metamorphic intrusions, such as the Diana Complex. 相似文献
106.
Carlos E. Canosa-mas Mark L. Flugge Dina Shah Alison Vipond Richard P. Wayne 《Journal of Atmospheric Chemistry》1999,34(1):153-162
A discharge-flow tube coupled with resonance fluorescence and chemiluminescence detection has been used to investigate the reactions IO + HO2 products (1) and IO + O(3P) I + O2(2), at T = 296 ± 1 K and P = 1.7 - 2 Torr. The rate constants k-1 and k2 have been found to be (7.1 ± 1.6) × 10-11 cm3 molecule-1 s-1 and (1.35 ± 0.15) × 10-10 cm3 molecule-1 s-1, respectively. 相似文献
107.
108.
Measurement of sediment resuspension rates in Long Island Sound 总被引:1,自引:0,他引:1
Resuspension rates have been measured on Long Island Sound sediments (New York/Connecticut, USA) under an oscillating grid,
using a flume, and in place, using high frequency acoustics, transmissometers, and sediment traps. Despite differences, the
results compare favorably. The methods all provide an order-of-magnitude estimate of the resuspension rate and increases under
storm conditions can be estimated. 相似文献
109.
Mark J. McCarthy Karen S. McNeal John W. Morse Wayne S. Gardner 《Estuaries and Coasts》2008,31(3):521-531
Bottom-water hypoxia effects on sediment–water interface nitrogen (N) transformations in Corpus Christi Bay (TX, USA) were
examined using continuous-flow intact sediment core incubations. Sediment cores were collected from three sites in August
2002 (summer hypoxia) and April 2003 (normoxia). Oxygen (O2) and hydrogen sulfide (H2S) depth profiles were generated with microelectrodes. Membrane inlet mass spectrometry was used to measure sediment O2 demand and net N2 flux and combined with isotope pairing to determine potential denitrification and N fixation. Potential dissimilatory nitrate
reduction to ammonium (DNRA) was measured using high-performance liquid chromatography. Sediment O2 penetration depths ranged from 5 to 10 mm. H2S ranged from being present in overlying water and throughout the sediment column in August to not detectable in overlying
water or sediment in April. Sediment O2 demand was higher during bottom-water normoxia conditions versus hypoxia. Sediments were a significant source of
\textNH\text4\text + {\text{NH}}_{\text{4}}^{\text{ + }} to overlying water during hypoxia but not during normoxia. Net N2 fixation was observed at one station in August and all stations in April. Denitrification rates were significantly higher
during hypoxia at two of three sites. Potential DNRA was observed during both oxic states, but rates were significantly higher
during hypoxia, which may reflect sulfide enhancement and absence of cation exchange with
\text14 \textNH\text4\text + ^{{\text{14}}} {\text{NH}}_{\text{4}}^{\text{ + }} . DNRA may contribute to formation and maintenance of bottom-water hypoxic events in this system. These results show that
N transformation pathways and rates change when bottom-water O2 concentrations drop to hypoxic levels. Since south Texas is a semiarid region with few episodic runoff events, these results
indicate that Corpus Christi Bay sediments are a N source most of the year, and denitrification may drive N limitation between
episodic runoff events. 相似文献
110.