Comparability of Large-Scale Studies of Agricultural Chemical Contamination of Rural Private Wells   总被引：1，自引：0，他引：1  

Chittaranjan Ray  Susan C. Schock 《Ground Water Monitoring & Remediation》1996,16(2):92-102

Detection of agricultural chemicals in ground water has prompted numerous studies. Federal, state, and regional studies were conducted in the last 10 years in order to assess the occurrence of agricultural chemicals in ground water. The results of the studies present the number or percentage of samples with agricultural chemicals above the drinking water standard or health advisory levels as well as samples with detections of one or more compounds. Data comparison from one state or region to another are frequently referred to by regulatory and agency personnel involved in water quality and agriculture issues. Unless the history of pesticide use, method of chemical analyses, detection limits, statistical design of the sampling plan, well type, well depth, geology of the formation material, and typical land use around the wellhead are known, such comparisons can be misleading. Reporting the limitations or presenting a disclaimer should be a key element for a study so that "apples and oranges" are not compared.  相似文献   

Metamorphic history of the Jutogh Series in the Simla klippe,lower Himalayas     

K. Naha  S. K. Ray 《Contributions to Mineralogy and Petrology》1970,28(2):147-164

The metamorphic rocks of the Jutogh Series around Simla, structurally overlying the less metamorphosed rock groups along a thrust contact, have been involved in three phases of deformation and two episodes of metamorphism. The first metamorphism is in the albite-epidote-amphibolite facies in a major part of the area, reaching the amphibolite facies locally in the central part. This metamorphism is late-to post-kinematic with reference to the F ₁ movement, the thermal peak having been reached in a post-F ₁ pre-F ₂ static phase. The second metamorphism, syn-to post-tectonic with respect to F ₂ but preceding F ₃, is generally in the greenschist facies, and only locally in the albite-epidote-amphibolite facies in the higher structural levels. Metamorphic overprinting has caused widespread retrogression and disequilibrium assemblages. As the large scale recumbent folding and thrusting of F ₁ and F ₂ phases belong to the Tertiary Himalayan orogeny, the metamorphism in the Jutogh Series could not have been Precambrian in age.  相似文献   

Mineralogy,petrology, and chemistry of a Luna 16 basaltic fragment,sample B-1     

A.L. AlbeeA.A. Chodos  A.J. GancarzE.L. Haines  D.A. PapanastassiouL. Ray  F. TeraG.J. Wasserburg  T. Wen 《Earth and Planetary Science Letters》1972

Luna 16 sample B-1 was the largest fragment (62 mg) obtained in the sample exchange with the USSR. Petrologic, mineralogic, and chemical investigations have been made on this fragment in conjunction with Rb-Sr and⁴⁰Ar/³⁹Ar investigations by our colleagues. Sample B-1 is a fine-grained ophitic basalt but is distinguished from the Apollo samples by containing a single pyroxene, predominantly pigeonitic, an ilmenite content (7%) intermediate to that of the Apollo 11 and 12 samples, and subequal amounts of pyroxene (50%) and plagioclase (40%). Chemically it is distinguished by a high Sr content (437 ppm) and a high K/U value (4700). The K-content (1396 ppm) is higher than that of Luna 16 soil sample A-2.  相似文献   

Mapping of fault rupture of the 28 may 2004 iran earthquake (mw= 6.2) using satellite image     

M. Sharifikia  C. S. Dubey  B. K. Sharma  M. Chaudhry  P. K. Champati Ray 《Journal of the Indian Society of Remote Sensing》2006,34(4):423-430

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The Apoteri volcanic formation — tholeiitic flows in the North Savannas Graben of Guyana and Brazil     

Jevan P. Berrangé  Ray Dearnley 《International Journal of Earth Sciences》1975,64(1):883-899

Amygdaloidal tholeiitic flows, locally pillowed, have been mapped at intervals over a distance of 280 km along the margins of the North Savannas Rift Valley in southern Guyana and Brazil. The combined chemical and petrological evidence suggests that the formation represents an originally uniform continental tholeiitic sequence that has undergone variable secondary alteration involving increasing oxidation and ingress of soda, potash and water. The lavas are both spatially and temporally related to the rift faulting; field observations and K∶Ar age determinations on eleven samples from different localities indicate that the flows were erupted during the Early to Middle Jurassic (180-150 m. y.). It is shown that this tectono-magmatic event is synchronous with the initiation of the southern North Atlantic rift and the pan-Antarctic rift which resulted in fragmentation of the continents according to the scheme ofDietz &Holden (1970).  相似文献   

Coupled surface and ground water models for investigating hydrological processes     

Ray‐Shyan Wu  Dong‐Sin Shih  Ming‐Hsu Li  Chia‐Ching Niu 《水文研究》2008,22(8):1216-1229

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Comments on the size of the simulation box in cosmological N-body simulations     

J. S. Bagla  Suryadeep Ray 《Monthly notices of the Royal Astronomical Society》2005,358(3):1076-1082

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Solar modulation of galactic cosmic rays during 19–23 solar cycles     

Partha Chowdhury  B.N. Dwivedi  P.C. Ray 《New Astronomy》2011,16(7):430-438

We make a detailed analysis of cross-correlation and time-lag between monthly data of galactic cosmic rays (GCRs) intensity and different solar activity indices (e.g., sunspot number, sunspot area, green coronal Fe line and 10.7 cm solar radio flux) during 19–23 solar cycles. GCRs time-series data from Kiel neutron monitor station and solar data from the last 50 years period, covering five solar cycles (19–23), and alternating solar polarity states (i.e., five A < 0 and four A > 0) have been investigated. We find a clear asymmetry in the cross-correlation between GCRs and solar activity indicators for both odd and even-numbered solar cycles. The time-lags between GCRs and solar parameters are found different in different solar cycles as well as in the opposite polarity states (A < 0 and A > 0) within the same solar cycle. Possible explanations of the observed results are discussed in light of modulation models, including drift effects.  相似文献   

Evaluation of the intermediate-term periodicities in solar and cosmic ray activities during cycle 23     

Partha Chowdhury  Manoranjan Khan  P. C. Ray 《Astrophysics and Space Science》2010,326(2):191-201

In this paper we investigate the presence and temporal evolution of galactic cosmic rays (GCRs) time-series and three solar parameters, namely the daily sunspot number, the coronal green line and the 10.7 cm solar radio flux over the period 1996–2003 by the wavelet technique. A number of short- and intermediate-term quasi-periodicities were also detected in both GCR and solar parameters. For the short-term range, we have identified quasi-periods of 16–30 days, 40–55 days, 60–70 days, 80–90 days and 80–100 days. In the case of intermediate range, the significant periods were 120–140 days, 150–170 days, 190–210 days, 240–260 days, ≈1.09 yr. and ≈1.23 yr. The wavelet power spectra show that all the above-mentioned periods are intermittent in nature and occurred in different time-series in different intervals. The result exhibits that the well-known “Rieger period” of (150–160 days) was prominent in both GCR and solar data sets during the ascending phase of cycle 23. Possible reasons behind the observed periods were discussed with the help of previous results and existing numerical models.  相似文献   

In search of a hidden long-term isolated sub-chondritic Nd/Nd reservoir in the deep mantle: Implications for the Nd isotope systematics of the Earth     

David Thomas Murphy  Alan D. Brandon  Ray Burgess 《Geochimica et cosmochimica acta》2010,74(2):738-4475

Here we search for evidence of the existence of a sub-chondritic ¹⁴²Nd/¹⁴⁴Nd reservoir that balances the Nd isotope chemistry of the Earth relative to chondrites. If present, it may reside in the source region of deeply sourced mantle plume material. We suggest that lavas from Hawai’i with coupled elevations in ¹⁸⁶Os/¹⁸⁸Os and ¹⁸⁷Os/¹⁸⁸Os, from Iceland that represent mixing of upper mantle and lower mantle components, and from Gough with sub-chondritic ¹⁴³Nd/¹⁴⁴Nd and high ²⁰⁷Pb/²⁰⁶Pb, are favorable samples that could reflect mantle sources that have interacted with an Early-Enriched Reservoir (EER) with sub-chondritic ¹⁴²Nd/¹⁴⁴Nd.High-precision Nd isotope analyses of basalts from Hawai’i, Iceland and Gough demonstrate no discernable ¹⁴²Nd/¹⁴⁴Nd deviation from terrestrial standards. These data are consistent with previous high-precision Nd isotope analysis of recent mantle-derived samples and demonstrate that no mantle-derived material to date provides evidence for the existence of an EER in the mantle.We then evaluate mass balance in the Earth with respect to both ¹⁴²Nd/¹⁴⁴Nd and ¹⁴³Nd/¹⁴⁴Nd. The Nd isotope systematics of EERs are modeled for different sizes and timing of formation relative to ε¹⁴³Nd estimates of the reservoirs in the μ¹⁴²Nd = 0 Earth, where μ¹⁴²Nd is ((measured ¹⁴²Nd/¹⁴⁴Nd/terrestrial standard ¹⁴²Nd/¹⁴⁴Nd)−1 * 10⁻⁶) and the μ¹⁴²Nd = 0 Earth is the proportion of the silicate Earth with ¹⁴²Nd/¹⁴⁴Nd indistinguishable from the terrestrial standard. The models indicate that it is not possible to balance the Earth with respect to both ¹⁴²Nd/¹⁴⁴Nd and ¹⁴³Nd/¹⁴⁴Nd unless the μ¹⁴²Nd = 0 Earth has a ε¹⁴³Nd within error of the present-day Depleted Mid-ocean ridge basalt Mantle source (DMM). The 4567 Myr age ¹⁴²Nd-¹⁴³Nd isochron for the Earth intersects μ¹⁴²Nd = 0 at ε¹⁴³Nd of +8 ± 2 providing a minimum ε¹⁴³Nd for the μ¹⁴²Nd = 0 Earth. The high ε¹⁴³Nd of the μ¹⁴²Nd = 0 Earth is confirmed by the Nd isotope systematics of Archean mantle-derived rocks that consistently have positive ε¹⁴³Nd.If the EER formed early after solar system formation (0-70 Ma) continental crust and DMM can be complementary reservoirs with respect to Nd isotopes, with no requirement for significant additional reservoirs. If the EER formed after 70 Ma then the μ¹⁴²Nd = 0 Earth must have a bulk ε¹⁴³Nd more radiogenic than DMM and additional high ε¹⁴³Nd material is required to balance the Nd isotope systematics of the Earth.  相似文献