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V. K. Sharma K. B. Rhudy J. C. Cargill M. E. Tacker F. G. Vazquez 《Environmental Geology》2000,39(6):698-704
This paper deals with the problem of increased heavy metal constituents in agricultural soils due to the expanded use of
fertilizers and elevated atmospheric deposition. It discusses the extent of contamination in soil and establishes an environmental
monitoring program in the chosen area of concern in the southern coastal region of Texas. Grain size, pH, and metals (Cu,
Cd, Zn, Pb, Ni, Ba, As, Cr, Mn, and Fe) were determined in soils of the middle Rio Grande basin. The soils were mainly of
sand texture and alkaline in character. Fine sand constituted the major proportion of the soil, and clay and silt ranged from
8–30% of the soil. Correlations of metal concentrations to grain size and iron contents were performed. Metals, except Cd
and Pb, gave positive to negative relationships with decreases in grain size. Silt gave no relationship with metal content
while clay and silt had a positive relationship. All these metals had a positive correlation with iron in the soil. The results
indicate metals are associated with coarse sand, clay, and iron hydroxides surfaces of the soil. The comparison of metal content
in soil of the middle Rio Grande basin with metals from other areas of the world suggests that it is relatively uncontaminated.
Received: 14 December 1998 · Accepted: 19 Jaunuary 1999 相似文献
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We report an unusual case of a two-ribbon flare associated with an umbral brightening in a magnetically unipolar region. 相似文献
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Mariano J. Albano Carlos Rumbold Ignacio L. Chiesa Guadalupe Vazquez Eduardo D. Spivak Sandra M. Obenat 《新西兰海洋与淡水研究杂志》2019,53(1):15-32
We report the occurrence of the invasive amphipod Monocorophium acherusicum in Mar del Plata port, Argentina, using morphological and molecular analysis and estimated mean abundance to detect monthly variations of this population. We compared M. acherusicum morphology with that of M. insidiosum and Crassicorophium bonelli, the two most similar locally occurring species, to establish the diagnostic characteristics for the correct identification of them; moreover, we provide some taxonomic notes about others corophiids regionally distributed. M. acherusicum were collected in a subtidal biofouling community and its mean abundance was maximum in summer. In the molecular analysis, the maximum-likelihood tree showed that specimens from Mar del Plata were clustered with M. acherusicum specimens from GenBank and Boldsystems. We support and confirm the species identity in Mar del Plata port using DNA barcoding and with taxonomic methods. 相似文献
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D. R. Lorimer K. M. Xilouris A. S. Fruchter I. H. Stairs F. Camilo A. M. Vazquez J. A. Eder M. A. McLaughlin M. S. E. Roberts J. W. T. Hessels S. M. Ransom 《Monthly notices of the Royal Astronomical Society》2005,359(4):1524-1530
We present the results of a 430-MHz survey for pulsars conducted during the upgrade to the 305-m Arecibo radio telescope. Our survey covered a total of 1147 deg2 of sky using a drift-scan technique. We detected 33 pulsars, 10 of which were not known prior to the survey observations. The highlight of the new discoveries is PSR J0407+1607, which has a spin period of 25.7 ms, a characteristic age of 1.5 Gyr and is in a 1.8-yr orbit about a low-mass (>0.2 M⊙ ) companion. The long orbital period and small eccentricity ( e = 0.0009) make the binary system an important new addition to the ensemble of binary pulsars suitable to test for violations of the strong equivalence principle. We also report on our initially unsuccessful attempts to detect optically the companion to J0407+1607, which imply that its absolute visual magnitude is >12.1. If, as expected on evolutionary grounds, the companion is an He white dwarf, our non-detection implies a cooling age of least 1 Gyr. 相似文献
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A minimum of angular velocity is not found at the equator as suggested by Gilman, but at a latitude of 6° in both hemispheres. 相似文献
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The temporal and spatial behaviour of the Ki7699 line profile is investigated. In particular we have measured the asymmetries of the line profile at several residual intensities using the bisector method. We find, in the bisector of the mean line profile, similar shapes as those obtained before for different positions on the solar disk. However the strong variations of the bisector found with time and geometry of input aperture, warns us against the use of the mean or integrated profiles (either in time or space). Moreover, we find an anticorrelation between the asymmetry in the line profile at different residual intensities and the shift, found as the distance to a terrestrial line, for any position observed on the solar disk. No limb effect for this line is found, within errors. 相似文献