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1.
Six sediment core samples collected from the innershelf of the east coast of India between Visakhapatnam and Kakinada were analyzed for major (Al & Fe) and trace metals (Cu, Co, Ni, Cd, Pb, Zn, Mn & Cr) to study the processes that regulate their concentrations in coastal sediments and to evaluate the metal contamination due to anthropogenic interference. High concentrations of Fe (5%-7%) are attributed mainly to the fine texture and its proximity to the source, maflc rocks. Positive correlation of Fe with Mn in all the cores indicates the influence of early diagenetic process. Positive correlations between Co, Ni, Zn and Cd among themselves and with Fe indicate their adsorption to ferromanganese oxides and involvement in geochemical processes. Further normalization of metals to Al indicates that the sediments are depleted in Mn & Zn and relatively enriched in Cd, Co, Ni, Pb & Cr, which also confirms that the origin of these sediments is of geological rather than biogenic importance. The Geo-accumulation (Igeo) values calculated for Ni, Pb, Co, Cd, Zn & Cr are more or less near to unity (Igeo≥1), indicating no industrial metal pollution. Pollution Load Index (PLI) values (1-2) calculated for the trace metals confirm the above findings.  相似文献   

2.
Stream water chemistry is dependent on the physical, chemical and biological processes occurring in the watershed. Understanding the governing mechanism of the stream water chemistry in a watershed is the first step for the water quality management. The study area drains a total catchment area of 1.46 km^2 and consists of forest (80%), upland (15%) and rice paddy field (5%). The studied area has two distinctive bedrocks, quartzite and schist. We periodically collected the stream water samples at mainstream and tributaries and the pH, electrical conductivity (EC), alkalinity and the concentrations of cations and anions of the collected stream water samples were determined in the field and laboratory. The all collected water samples were nearly neutral and the EC and concentrations of Na, K, Ca, Sr, Si and HCO3 of the stream water samples collected from the schist terrain had greater values than those from the quartzite terrain. The mainstream running along the boundary of schist and quartzite terrains had the intermediate values of the tributaries. The stream water samples collected in and near the upland showed a high concentration of NO3^- than those of forest regardless the lithology. The stream pathway was also directly reflected on the chemistry of stream water. The stream water drained in the forest of quartzite terrain had the lowest values of alkalinity, EC and concentrations of cations and anions but the stream water drain in the upland of schist terrain had the highest values of EC and concentrations of cations and anions, especially NO3^-.  相似文献   

3.
Although numerous papers have been published on nutrients in Great Lakes, estuaries, continental shelf areas and marines in the aspects of determination, sediment-water-interface exchange, fluxes and budget estimation, eutrophication and microbial processes as well as modeling study, the knowledge of river condition (especially urban river) is uncertain and simply considered as a contributor to eutrophication of estuary. After a series of determinations of nitrogen species corresponding to ammonia-N (AN), Kjeldahl-N (K-N), and total nitrogen (TN) by means of National Standards for China, the nitrate & nitrite (Nitr-N) and org-N were obtained by the difference of TN with K-N, and K-N with AN, respectively. Therefore, the behaviors of vertical distributions in overlying waters and porewaters in the Fu and Nan Rivers located in Chengdu City were achieved.  相似文献   

4.
The Sipadan island is the only oceanic island found in Malaysia, and is popularly known for its beautiful corals and diving activities. The aquifer of the island is affected by seawater intrusion associated with groundwater exploitation. Geologically, the aquifer is composed of several series of Quaternary bioherm facies, and its recharge merely depends on rainfall. This research attempts to understand the chemical changes of the groundwater attributed to the salinization processes based on major ion composition (Ca^2+, Mg^2+, Na^+, K^+, HCO, SO, Cl^-). The initial assessments were done in years 1993 - 1994, followed by subsequent assessment in years 2004-2005. Methods of analyses were adopted from APHA (1995). The hydrogeochemical saturation indices (SI) were computed using the PHREEQC program in order to assess the state of equilibrium between groundwater and the minerals present. The results of analyses indicated that the groundwater has been highly enriched in Na^+, SO and CI, reflecting an encroachment of saline water into the aquifer. The groundwater facies can be classified as sodium chloride (Na-Cl) water type. There are positive correlations (moderate to strong), except HCO3^-, between the studied parameters. The weak and inconsistent correlation of HCO3^- with the cations and anions related to dissolved salts suggests that saltwater intrusion has an insignificant impact on the chemistry of HCO3^- in the groundwater. Strong correlations (r 〉0.70) exist among the major elements (Na^+, Mg^2+, K^+, Cl^- and SO4^-) and salinity (EC). These relationships clearly identify the main elements contributing to the groundwater salinity and their tendency to depict a similar trend of salinization pattern. Chloride has a major influence on the salinity of groundwater based on the positive and strong correlation that exist between Cl^- and EC (r=0.97).  相似文献   

5.
The name Calabrian was introduced in the geological literature by the French stratigrapher Maurice Gignoux in 1910, and later described in his important monograph (633 pages) "Les formations marines pliocknes et quaternaires de l'ltalie du sud et de la Sicile "published in 1913. Detailed data were provided on several sections (Santa Maria di Catanzaro, Caraffa, Monasterace, Palermo) and on their fossil content. The Calabrian Stage has commonly been used for over fifty years as the oldest subdivision of the Qua- ternary, notably in the time scales of Berggren & van Cou- vering (1974) and Haq & Eysinga (1987). However, after the GSSP for the Pliocene/Pleistocene boundary (P/P) was approved by INQUA in 1982 and ratified by lUGS in 1984 at the Vrica section of Calabria, there was a decline in the usage of the stage name, and an increasing tendency by many Quaternary workers to question the boundary stratotype. This was because there was increasing evidence that it did not correspond to the beginning of the "ice age". In doing so, they were not complying with the recommendations presented at the 18th International Geological Congress (IGC) in London, 1948 (Oakley, 1950).  相似文献   

6.
The Nyiragongo volcano is located in the Virunga volcanic chain (Western Branch Rift, Eastern African Rift System). On January 17-18, 2002 a NS-oriented fracture network quickly propagated down-slope up to 16 km from the crater and two of the several lava flows emitted reached the city of Goma (about 500000 inhabitants). On May 2002 the volcanic activity resumed in the main crater with the formation of an active lava lake, which produced a volcanic plume mainly displaced west towards by the dominant winds. TOMS data suggest a release of SO2 of up to 60000 tons per day with relevant amounts of HF, HC1 and CO2. About 50000 people living in the villages around the western flank of Nyiragongo were forced to use rainwater, having no direct access to drinkable water Furthermore, crops and plants located in the western sector lie below the main direction of the volcanic plume. In order to evaluate the effects on the environment and public health caused by the Nyiragongo degassing system, rain waters, ashes, scorias and Pelee's hairs have been collected in a span of time of more than three years from different sites: (1) Nyiragongo crater;  相似文献   

7.
We report new petrological data and geochronological measurements of granulites from Vesleknausen in the highest-grade section of the Lützow-Holm Complex, part of the Gondwana-assembling collisional orogen in East Antarctica. The locality is dominated by felsic to intermediate orthogneiss (charnockite and minor biotite gneiss), mafic orthogneiss, and hornblende-pyroxene granulite, with deformed and undeformed dykes of metagranite and felsic pegmatite. Pseudosection analysis of charnockite in the system NCKFMASHTO, supported by geothermometry of mafic orthogneiss, was used to infer peak metamorphic temperatures of 750e850 ?C, approximately 150 ?C lower than those estimated for met-asedimentary gneisses from Rundv?gshetta, 6 km to the northeast. SHRIMP U-Pb analysis of zircons from feldspar-pyroxene gneiss, which corresponds to a partially molten patch around mafic orthogneiss, yielded a Concordia upper intercept ages of 2507.9 ? 7.4 Ma, corresponding to the time of formation of the magmatic protolith to the orthogneiss. Partial melting during peak metamorphism probably took place between 591 and 548 Ma, as recorded in rims overgrew around magmatic zircon. Our results suggest that Rundv?gshetta-Vesleknausen-Strandnibba region in southwestern Lützow-Holm Bay, where orthogneisses are dominant, consists of a single crustal block, possibly formed by ca. 2.5 Ga arc mag-matism. The Neoarchean magmatic terrane was tectonically mingled with other fragments (such as metasedimentary units in northern Lützow-Holm Bay) by subduction/collision events during the as-sembly of Gondwana supercontinent, and subsequently underwent w850 ?C granulite-facies meta-morphosed during Neoproterozoic to Cambrian final collisional event.  相似文献   

8.
In developing countries, large amounts of wastes are dumped daily in open dumping sites without proper management. This practice usually causes enhanced concentration of metallic ions in environmental media within and beyond the vicinity of such dumps with attendant adverse environmental and health risks. Hence the aim of this study is to assess and elucidate the physico- and metallic ions concentrations in three environmental media (soils, sediments and waters) around active (Ojota) and abandoned (Isolo) dumpsites in Lagos and also to do a comparative study with reference to possible environmental and health impacts. A total of eighty samples comprising water, sediments and topsoils were collected around the two dumpsites. The soil and sediment were dried, disaggregated and sieved to 〈75 μm fraction for analysis of the metallic ions using aqua-regia digestion technique and Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The analysis of metallic ions and cations in water was carried out using Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) while unacidified water samples were analyzed for anions concentrations using the DIONEX DX-120 Ion Chromatography techniques. Analytical results show that pH, NO3, Fe, Mn and Na in most of the water samples are above WHO and EPA standards. Also there are relatively strong correlations between NO3 and Cl, SO4, Coliform, TDS and EC which are an indicator of water contamination especially in the direction of groundwater flow. The mean values of the significant metallic ions present in the water samples include Cu (16.29 and 38.0), Zn (535.71 and 667.0), A1 (0.27 and 0.19), Ba (42.86 and 55.0), Sr (80.0 and 136.0) and B (118.7 and 160.2) for active (Ojota) and abandoned (Isolo) dnmpsites respectively. Soil samples revealed varied concentrations with the estimated average contamination factors of 3.86 and 5.71 (As), 1.60 and 1.93 (Mo), 3.41 and 4.24 (Zn), 0.93 and 2.23 (Cu), 7.71 and 12.64 (Pb), 8.71 and 9.21(Cd) for both active and abandoned sites respectively. All these metals with Ag are also significant and follow the same trend in the sediments. Ag, Bi, Sb, Ga, Sc, Mn, Ga and La in soil samples are only significant for samples close to the dnmpsites while Bi, Be, Sb, Co, Cu, La and Cr are significant for sediments taken downstream. Most of the metallic ions show significant enrichment in both soil and sediments while A1, B, Ba and Sr are only significant in water.  相似文献   

9.
Separation technology of rare earth elements (REEs), as the critical step in the separation process, had long been fraught with technical difficulty. A research project conducted by Baotou Shibo Rare Earth Extraction & Equipment Co. Ltd., Baotou REE Research Institute, and Baotou Steel & REE Group Hi-Tech Co. Ltd (Inner Mongolia), has successfully solved the problem using a centrifugal extractor and advanced techniques to achieve a key breakthrough.  相似文献   

10.
The black shale formed under anoxic conditions usually contains high concentrations of many metals. Weathering of such black shale might cause the emission of many metals. Moreover, soils derived from black shale (SBS) are believed to be affected by black shale weathering. In recent years, many studies such as Lee et al. (2002), Woo et al. (2002), Fang et al. (2002), Pasava et al. (2003), and Peng et al. (2004) have approached the heavy metal contaminations of SBS, but systematical geochemical study is rare. Presently, the SBS and its corresponding black shales (CBS) were both sampled from central Hunan (China), and analyzed for a large number of elements, using an Elan6000 ICP-MS/AES machine at Guangzhou Institute of Geochemistry, CAS. In this paper, some preliminary results are reported. The analytical results show that the SBS in central Hunan contains very high concentrations of heavy metals such as Co, Cu, Hg, Mo, Pb, Zn, U, Th, Sb, T1, Cd, Cr, Sc, V, Sn, As, Se, and Ni.  相似文献   

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