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171.
Astrophysics and Space Science - The annular solar eclipse of the previous decade that occurred on December 26, 2019, was mostly visible from most Asian countries, including India. In this... 相似文献
172.
Waleed S. Shingaly Ali I. Al-Juboury Elias M. Elias 《Arabian Journal of Geosciences》2014,7(8):3163-3174
In the northeast of Zakho City, Northern Iraq, the host rocks of Pb–Zn deposits are composed predominantly of dolomites with subordinate dolomitic limestone intervals. This study is focused on the dolomites of the Bekhme Formation (Upper Campanian) carbonate-hosted Pb–Zn deposits. The amount of dolomites, however, increases toward the mineralized zone. Dolomites are dominated by replacement dolomite with minor dolomite cements. Petrography study allowed identification of six different dolomite textures. These are (1) fine crystalline, planar-s (subhedral) dolomite, RD1; (2) medium to coarse crystalline, planar-e (euhedral) to planar-s (subhedral) dolomites, RD2; (3) medium crystalline, planar-s (subhedral) to nonplanar-a (anhedral) dolomites, RD3; (4) coarse crystalline, planar-s (subhedral) to nonplanar-a (anhedral) dolomites, RD4; (5) planar (subhedral) void-filling dolomite cements, CD1; and (6) nonplanar (saddle) void-filling dolomite, CD2. The RD1, RD2, RD3, and RD4 dolomite textures are replacive in origin and are volumetrically the most important types, whereas CD1 and CD2 dolomites with sparry calcite are commonly cements that fill the open spaces. Although the dolomites of the Bekhme Formation are not macroscopically observed in the field, their different types are easily distinguished by petrographic examination and scanning electron microscopy. It was observed that the dolomites of the Bekhme Formation are formed in two different diagenetic stages: the early diagenetic from mixing zone fluids at the tidal–subtidal (reef) environments and the late diagenetic from basinal brines which partially mixed with hydrothermal fluids at the shallow-deep burial depths. The latter occurs often with sphalerite, galena, and pyrite within mineralized zone. These dolomite types are associated base-metal mineralization (Mississippi Valley type). 相似文献
173.
Amado LL da Rosa CE Leite AM Moraes L Pires WV Pinho GL Martins CM Robaldo RB Nery LE Monserrat JM Bianchini A Martinez PE Geracitano LA 《Marine pollution bulletin》2006,52(2):199-206
Biomarkers of exposure and effect of pollutants were analyzed in croakers Micropogonias furnieri (Teleostei: Sciaenidae) captured in winter and summer in a polluted and in a non-polluted site at the Patos Lagoon estuary (Southern Brazil). Catalase and glutathione S-transferase activities (exposure biomarkers) and lipid peroxidation (effect biomarker) were analyzed in liver samples. Other two effect biomarkers were also studied: blood cells DNA damage (through comet assay and micronucleus test) and respiratory burst measurements. In a broad view, results point to an important seasonal variation of the biochemical biomarkers analyzed. However, data obtained clearly indicate that croakers collected in winter at the polluted site were subjected to a level of clastogenic agents sufficient to generate irreversible genetic damages (mutations) and impair the fish immune system. 相似文献
174.
The deep wells drilled along the eastern escarpment of the Jordan Valley penetrate confined aquifers that produce thermal and mineralized artesian water. Uncontrolled flows from poorly constructed and uncapped artesian wells over the last 30 years have caused the deterioration of the quality of shallow groundwater and surface water. They also have been accelerating the discharge of saline water from deep aquifers and have caused the loss of shallow fresh groundwater resources through the downward percolation of fresh water to replace the extracted deep salty groundwater. A lack of adequate controls on the construction and maintenance of artesian wells is leading to widespread water quality problems in the region, which limits the ability of future generations to access high-quality water, a clear breach of the principle of intergenerational equity. 相似文献
175.
A water-chemistry evaluation was made of the available springs and wells in Amman and vicinity. Trihalomethanes (THM) were
found in all analysed samples with concentrations ranging from 0.2–31.88 μg/L. The probable sources of trihalomethanes in
the aquifers originate from three sources: (1) chlorinated Deir Alla surface water, (2) reaction of excess chlorine in the
leaky, corroded water-distribution network with organic matter in the vadose zone, and (3) sewage seepage from cesspools in
the area. Total organic carbon (TOC) ranged from 0.2–1.4 mg/L. Its probable source is either from the vadose zone or the treated
surface water at Deir Alla. It was found that TOC was of vital importance in the formation of THM in the presence of chlorine
from the water-distribution system.
Major ionic composition of the analysed samples reflected the limestone lithology of the aquifer in the investigated area.
Heavy-metal content was relatively low due to the high pH of the groundwater samples.
Electronic Publication 相似文献