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51.
Structural and Hydrogeological Controls on Hydrocarbon and Brine Migration into Drinking Water Aquifers in Southern New York
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Rebecca L. Kreuzer Thomas H. Darrah Benjamin S. Grove Myles T. Moore Nathaniel R. Warner William K. Eymold Colin J. Whyte Gautam Mitra Robert B. Jackson Avner Vengosh Robert J. Poreda 《Ground water》2018,56(2):225-244
Environmental concerns regarding the potential for drinking water contamination in shallow aquifers have accompanied unconventional energy development in the northern Appalachian Basin. These activities have also raised several critical questions about the hydrogeological parameters that control the naturally occurring presence and migration of hydrocarbon gases in shallow aquifers within petroliferous basins. To interrogate these factors, we analyzed the noble gas, dissolved ion, and hydrocarbon gas (molecular and isotopic composition) geochemistry of 98 groundwater samples from south‐central New York. All samples were collected ?1km from unconventional drilling activities and sample locations were intentionally targeted based on their proximity to various types of documented fault systems. In agreement with studies from other petroliferous basins, our results show significant correlations between elevated levels of radiogenic [4He], thermogenic [CH4], and dissolved ions (e.g., Cl, Br, Sr, Ba). In combination, our data suggest that faults have facilitated the transport of exogenous hydrocarbon‐rich brines from Devonian source rocks into overlying Upper Devonian aquifer lithologies over geologic time. These data conflict with previous reports, which conclude that hydrodynamic focusing regulates the occurrence of methane and salt in shallow aquifers and leads to elevated levels of these species in restricted flow zones within valley bottoms. Instead, our data suggest that faults in Paleozoic rocks play a fundamental role in gas and brine transport from depth, regulate the distribution of their occurrence in shallow aquifers, and influence the geochemistry of shallow groundwater in this petroliferous basin. 相似文献
52.
The Reviewed Event Bulletin (REB) of the International Data Center (IDC) has been used in order to investigate the seismicity of the Northwest Himalaya and its neighboring region for the time period June 1999 to March 2015 within the geographical coordinates 25–40° N latitude and 65–85° E longitude. We have used a very precisely located earthquake dataset recorded by the International Monitoring System (IMS) Network containing 7,583 events with body wave magnitudes from 2.5 to 6.3. The study area has been subdivided into six regions based on the Flinn-Engdahl (F-E) seismic and geographical regionalization scheme, which was used as the region classifications of the International Data Center catalog. The examined region includes NW India, Pakistan, Nepal, Xizang, Kashmir, and Hindukush. For each region, Magnitudes of completeness (Mc) and Gutenberg-Richter (GR) recurrence parameters (a and b values) have been estimated. The Gutenberg-Richter analysis is preceded by an overview of the seismotectonics of the study area. The obtained Mc values vary from 3.5 to 3.9. The lower value of Mc was found mainly in Xizang region whereas the higher Mc threshold is evident in Pakistan region. However, the b values vary from 1.19 to 1.48. The lowest b value is recorded in Xizang region, which is mostly related to the Main Karakoram Thrust (MKT) fault, whereas the highest b values are recorded in NW India and Kashmir regions, which are mostly related to the Main Frontal Thrust (MFT) fault. The REB for the selected period has been compared to the most renowned bulletin of global seismicity, namely that issued by the National Earthquake Information Center (NEIC) of the United States Geological Survey (USGS). A study of 4,821 events recorded by USGS in the study region indicates that about 36 % of seismic events were missed and the catalog is considered as complete for events with magnitudes ≥4.0. However, both a and b values are obviously higher than those of IMS catalog. The a and b parameters in the Gutenberg-Richter magnitude–frequency relationship have been utilized to forecast the probability of future earthquakes of different magnitudes and returned periods (recurrence intervals). 相似文献
53.
K. H. V. Durga Rao V. Bhanumurthy P. S. Roy 《Journal of the Indian Society of Remote Sensing》2009,37(4):587-600
Hydrological modelling of large river catchments is a challenging task for water resources engineers due to its complexity
in collecting and handling of both spatial and non-spatial data such as rainfall, gauge discharges, and topographic parameters.
In this paper an attempt has been made to use satellite-based rainfall products such as Climatic Prediction Centre (CPC)-National
Oceanic and Atmospheric Administration (NOAA) data for hydrological modelling of larger catchment where the limited field
rainfall data is available. Digital Elevation Models (DEM) such as Global DEM (1 km resolution) and Shuttle Radar Topography
Mission (SRTM) 3-arc second (90 m resolution) DEM have been used to extract topographic parameters of the basin for hydrological
modelling of the study area. Various popular distributed models have been used in this study for computing excess rainfall,
direct runoff from each sub-basin, and flow routing to the main outlet. The Brahmaputra basin, which is very complex both
hydraulically and hydrologically due to its shape, size, and geographical location, has been examined as study area in this
study. A landuse map derived from the satellite remote sensing data in conjunction with DEM and soil textural maps have been
used to derive various basin and channel characteristics such as each sub-basin and channel slope, roughness coefficients,
lag-time. Percentage of residual flows computed between observed flows and simulated flows using Global and SRTM DEMs are
discussed. It is found that the topographic parameters computed using SRTM DEM could improve the model accuracy in computing
flood hydrograph. Need of using better resolution satellite data products and the use of high-density field discharge observations
is discussed. 相似文献
54.
Summary Mineral chemistry and petrological data of chromites from chromitite bands in the N–S trending schist belt of Nuggihalli (southern
Karnataka, India), belonging to the Dharwar craton of South India, are presented in this paper. Crystal chemical data indicate
a komatiitic affinity of the chromitite. P–T calculations of the chromite-hosting peridotites yielded a pressure range of 13 to 28 kbar and temperatures ranging from
775 to 1080 °C; the oxygen fugacity (log fO2) varies from +0.5 to +1.6 above the QFM buffer. The P, T and fO2 data indicate that Nuggihalli chromitites crystallized in an environment akin to the upper mantle. The studied samples also
show partial resetting; the lower temperatures ranging from 515 to 680 °C are ascribed to subsequent metamorphism of the area. 相似文献
55.
Application of the time-predictable model in Peninsular India for future seismic hazard assessment 总被引:1,自引:0,他引:1
It has been the belief among Earth scientists that the Peninsular Shield is aseismic, as the region attained stability long
ago. However, the earthquake at Koyna (10 December 1967), Bhadrachalam (13 April 1969), Broach (23 March 1970), Hyderabad
(30 June 1983), Khillari (30 September 1993), Jabalpur (22 May 1997), Gujarat (26 January 2001), and additional ones of smaller
magnitudes, altered this concept. This area has experienced many widely distributed shallow earthquakes, some of them having
large magnitudes. It is now widely accepted that seismic activity still continues with moderate events. Therefore, a need
has arisen to take into consideration recent seismological data to assess the future seismic status of Peninsular India. Earthquake
generation model has been studied to develop the statistical relations with surface wave magnitude (M
S
≥ 4.5). Five seismogenic sources showing clustering of earthquakes and including at least three main shocks of magnitude
4.5 ≤ M
S
≤ 6.5 giving two repeat times, have been identified. It is mainly based on the so-called “regional time-predictable model”.
For the considered region it is observed that the time interval between two consecutive main shocks depends on the preceding
main shock magnitude (M
p
) not on the following main shocks magnitude M
f
suggesting the validity of time predictable model in the region. 相似文献
56.
Ines Hoog Subir K. Mitra Karoline Diehl Stephan Borrmann 《Journal of Atmospheric Chemistry》2007,57(1):73-84
In laboratory experiments the interactions of ammonia with ice crystals were studied within the temperature range between
0 and −20°C. In a first series of experiments dendritic ice crystals were grown from water vapor in presence of ammonia gas
in various concentrations between 4 and 400 ppbv. In a second series of experiments pure ice crystals were exposed to a humidified
ammonia–air mixture inside a horizontal flow tube. The influence of temperature, ammonia gas concentration (0.6, 1.5, and
10 ppmv), exposure time, and the presence of impurities such as sulfate on the ammonia uptake by the ice surface was investigated
by determining the ammonium content in the melt water of the ice crystals by ion chromatography. During the growth of ice
crystals significant amounts of ammonia (around 200 μg/l) were taken up even at small gas concentrations. In contrast, even
at high gas concentrations the uptake of ammonia by non-growing ice crystals was lower by approximately one order of magnitude.
The presence of sulfate on the ice surface affected an enhanced uptake of ammonia by a factor of 5–10. A model is presented
which describes the uptake of ammonia by ice considering the chemical processes occurring in the ice surface layer and simultaneous
diffusion of ammonia into bulk ice. Even the increased uptake of ammonia by growing ice is rather small compared to the uptake
by water droplets; thus, the major process for scavenging of ammonia from the atmosphere via the ice phase might not be the
direct uptake by ice crystals but the riming involving super-cooled droplets containing ammonia. 相似文献
57.
58.
59.
The combination of dispersion measures of pulsars, distances from the model of Cordes & Lazio (2002) and emission measures from the WHAM survey enabled a statistical study of electron densities and filling factors of the diffuse ionized gas (DIG) in the Milky Way. The emission measures were corrected for absorption and contributions from beyond the pulsar distance. For a sample of 157 pulsars at |b | > 5. and 60° < ℓ < 360°, located in mainly interarm regions within about 3 kpc from the Sun, we find that: (1) The average volume filling factor along the line of sight and the mean density in ionized clouds are inversely correlated: ( ) = (0.0184 ± 0.0011) –1.07 ± 0.03 for the ranges 0.03 < < 2 cm–3 and 0.8 > > 0.01. This relationship is very tight. The inverse correlation of and causes the well‐known constancy of the average electron density along the line of sight. As (z ) increases with distance from the Galactic plane |z |, the average size of the ionized clouds increases with |z |. (2) For |z| < 0.9 kpc the local density in clouds n c(z ) and local filling factor f (z ) are inversely correlated because the local electron density n e(z ) = f (z )n c(z ) is constant. We suggest that f (z ) reaches a maximum value of >0.3 near |z | = 0.9 kpc, whereas n c(z ) continues to decrease to higher |z |, thus causing the observed flattening in the distribution of dispersion measures perpendicular to the Galactic plane above this height. (3) For |z | < 0.9 kpc the local distributions n c(z ), f (z ) and (z ) have the same scale height which is in the range 250 < h ≲ 500 pc. (4) The average degree of ionization of the warm atomic gas (z ) increases towards higher |z | similarly to (z ). Towards |z | = 1 kpc, (z ) = 0.24 ± 0.05 and (z ) = 0.24 ± 0.02. Near |z | = 1 kpc most of the warm, atomic hydrogen is ionized. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献