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1.
Water and sediment samples collected from the Gomti River, a tributary of the Ganges River system, during the postmonsoon season have been analyzed to estimate major elemental chemistry. Water chemistry of the River Gomti shows almost monotonous spatial distribution of various chemical species, especially because of uniform presence of alluvium Dun gravels throughout the basin. The river annually transports 0.34×106 tonnes of total suspended material (TSM) and 3.0×106 tonnes of total dissolved solids (TDS), 69 percent of which is accounted for by bicarbonate ions only. Samples collected downstream of the city of Lucknow show the influence of anthropogenic loadings for a considerable distance in the river water. Na+, Cl–, and SO4
2– concentrations build up downstream. The bed sediment chemistry is dominated by Si (36 percent), reflecting a high percentage of detrital quartz, which makes up about 74 percent of the mineralogy of the bed sediments in the River Gomti. The average Kjeldahl nitrogen concentration (234 g/g) indicates indirectly the amount of organic matter in the sediments. The Hg concentration in sediments has been found to be higher (average 904 ppb) than the background value. The suspended sediments are well sorted, very finely skewed, and extremely leptokurtic, indicating a low energy condition of flow in the Gomti River. The influence of chemical loads in the Gomti has been found to be small or nonexistent on the Ganges River, perhaps because the water discharge of the Gomti (1.57 percent) to the Ganges is quite low. 相似文献
2.
The sediments of the estuaries and offshore Tuticorin along the southern coast of Tamil Nadu were studied for their textural variation. Ninety sediment samples were collected from three sectors (river, estuary, offshore) on the basis of prevailing energy conditions and oceanographic parameters. Frequency curves show unimodal to bimodal in nature. Offshore samples also fall in bimodal with medium and fine sand where sediment is additionally deposited by the Tamiraparani River. The mean values ranging from 1.69 to 2.01 φ with medium to fine sand. The fine sand in the riverine region indicates the depositional nature of the sediments. In pre-monsoon, the standard deviation ranges from 0.29 to 0.81 φ, which falls in the very well sorted to moderately well sorted. Estuary ranges from 0.63 to 1.30 φ, with moderately sorted, whereas in the marine sediments ranges from 0.4 to 1.01 φ, with moderately to moderately well- sorted and some patches of poorly sorted is observed. In both monsoons, the grain size variations are mostly influenced in river and offshore samples compared to the estuaries. The CM pattern indicates the deposition of sediments in graded suspension. In estuary, the sediments are medium sand with moderately to poorly sorted, fine skewed which are indicative of denudation processes taking place there. In marine, the sediments are medium-to-fine, moderately-to-well sorted, and fine skewed to very fine skewed sediments, probably as a result of the influence of palaeo-sediments deposited by rivers from inland as well as by waves and currents from offshore. Further, the marine samples also highlight depositional processes. 相似文献
3.
Heavy metals distribution in core sediments, different size fractions of bed sediments (>212 urn, 90-212 jam, 63–90 urn, 53–63 urn, < 53 urn), and suspended sediments (>30 urn, 20–30 m, 10–20 urn, 2–10 urn, <2 m) have been discussed. Pb, Zn, and Cr have been accumulating in recent years in the sediments. Si, Al, Fe, Ca, and Mg dominate the bed and suspended sediment composition. Metals show increasing concentrations in finer sediments. Applying multivariate analysis to sediment composition, metals have been grouped into different factors depending upon their source of origin. Chemical fractionation studies on suspended and bed sediments show Fe, Zn, Cu, and Pb are associated with the residual fraction and Mn with the exchangeable fraction. 相似文献
4.
The Oso Bay, Texas, sediments from nine sites were analyzed by GC-MS for organics to measure contamination in the bay. In most of the sites sediments contained tetrachloroethene (87–1433 g/kg), bis (2-ethylhexyl)phthalate (40–193 g/kg), and aliphatic hydrocarbons, C8-C13 (720–2491 g/kg). Sources of these contaminants include a landfill, military facilities, and municipal and industrial discharges. Size analysis of the sediments indicates they contain a high percentage of muddy sand (50–75 percent), which suggests that Oso Bay consists of common bay margin sediments. 相似文献
5.
Texture and geochemistry of the sediments of a tropical mangrove ecosystem,southwest coast of India 总被引：2，自引：0，他引：2
The textural and geochemical aspects of the sediments of a tropical mangrove ecosystem have been studied and discussed. The sediments are characterized by the abundance of silt and sand with minor amounts of clay. The mean size of the sediment ranges from 0.205 mm to 0.098 mm (fine to very fine grained sand). The sediments are very poorly sorted, negatively to very negatively skewed, and platy to extremely leptokurtic in nature. The organic carbon content of the sediments ranges from 0,33% to 4.93%, which is controlled by the particle size of the sediments. The CaCO3 content is five times the enrichment of organic carbon. This enhanced CaCO3 content of the mangrove sediments might be a result of the abundance of shell fragments in the sediments. The shell mining activities in the estuarine bed adjoining the Kumarakam mangroves also contribute a substantial amount of lime muds to the mangrove area, which in turn add CaCO3 to the sediments. The relative concentrations of heavy metals are Fe > Mn > Cr > Zn > Ni > Cu. All heavy metals other than Fe show an increase in concentration compared to the other parts of the estuarine bed. Cluster analysis indicates that the contents of organic C, Fe and Mn have a marked bearing on the Cr, Zn, Ni, and Cu levels of the mangrove sediments. 相似文献
6.
C. M. Barton 《Australian Journal of Earth Sciences》2013,60(2):191-204
Interseam “sands” of Morwell form part of a sequence of brown‐coal seams, sediments and volcanic rocks which, together, make up the Tertiary Latrobe Valley Coal Measures. A detailed investigation and computer analysis of the “sands” show that they are fluviatile deposits which accumulated within the tectonically stable Latrobe Valley Depression. On an inclusive‐graphic comparative scale, particle‐size analyses show that the sediments tend to be poorly sorted, positively skewed and mesocurtic with a mean size within the coarse‐sand range. Modal frequency peaks occur between –0.5 and –1 and between 1 and 2 phi. Presented evidence suggests that the coarser fraction represents a rolled grain population with fine‐medium sand reflecting parallel deposition from graded suspension. 相似文献
7.
辽西兴城地区上古生界沉积环境识别 总被引：2，自引：1，他引：1
以粒度分析结果为依据,结合地层的序列、结构、构造及岩性等方面的特征,在辽西兴城地区的上古生界中识别出四种沉积环境,每种环境均有独特的粒度特征:①曲流河环境:所在层位为本溪组与石盒子组中下部,沉积物平均粒径多集中在3φ附近,分选度较好,频率曲线多为微正偏的正态分布,概率累积曲线存在差异,河道为典型两段式,决口扇为低悬两段式;②三角洲平原环境,所在层位为太原组与山西组,其中平原沼泽沉积物粒度较细,集中在3.2φ之间,但分支河道粒度相对较粗,与曲流河类似,三角洲平原沉积物分选好,频率曲线正偏、负偏均存在,概率累积曲线存在差异,分支河道为低悬两段式而平原沼泽则为一段式,反映垂向加积特征;③辫状河环境,对应石盒子组上部层位,沉积物平均粒度2.5φ左右,分选中等至较好,频率曲线多为微正偏态,概率累积曲线介于典型两段式与高悬两段式之间;④冲积扇环境,所在层位为蛤蟆山组,平均粒径集中在2φ左右,分选中等,频率曲线为正偏态至很正偏态,表明沉积物以粗组分为主,概率累积曲线均为高悬两段式,代表很高的水动力条件。从水动力条件及沉积环境的演化趋势来看,本地区晚石炭世至中二叠世中期处于温暖湿润的濒海盆地环境,中二叠世后期开始,随着地壳抬升,本地区不断向内陆环境变化,至晚二叠世末期,已经进入干旱炎热的内陆盆地环境。 相似文献
8.
G. Santhiya C. Lakshumanan M. P. Jonathan M. Sundrarajan S. Srinivasalu S. Viveganandan B. Uma-Maheswari 《Journal of the Geological Society of India》2016,87(6):727-736
The present study was undertaken to examine the depositional and transportation pattern in the tourist beaches of Chennai in SE coast of India. Twenty four samples were analyzed for textural parameters, Linear discriminate function (LDF), C-M plots and heavy/light minerals from beach, berm and dune regions. Results of textural parameters indicate that they are coarse grained in the three regions. Majority of the samples indicate that they are moderately well sorted, symmetrically skewed and leptokurtic. The LDF analysis allowed in identifying areas that are characterized by: (1) beach, (2) shallow agitated environment and (3) fluvial deposits. C-M plots indicate that the sediments in the beaches were deposited from the near shore environment. Heavy mineral analysis suggests that the heavy and light minerals were in the range of 0.5 to 16.9% and 82.08 to 98.14% and the light/dark layers are controlled by the prevailing tidal conditions in the coastal region. It is observed that sand is accumulating from the shallow agitated environment, while the transportation and deposition of sediments is mainly due to the interaction of tidal activities at the same time. C-M plots suggest that the sediments fall in the graded suspension and the saltation activities in the region also facilitate to understand the hydrodynamics of the region suggesting that they are deposited by high-energy activities. 相似文献
9.
Suspended and bed sediments collected from the entire region of the Godavari River basin were analyzed for Fe, Mn, Cr, Cu, Ni, and Zn. There are pronounced temporal and spatial variations in the heavy metal distributions. The concentrations of heavy metals in the suspended sediments are significantly higher than the bed sediments.Throughout the basin heavy metals are enriched in the finer fractions (<2 µm) of the bed sediments. The average heavymetal composition of the sediments is higher when compared to the average Indian river sediments. Heavy-metal concentration in the two shallow cores collected shows, to some extent, the influence of urbanization. When compared to the other tropical Indian rivers such as the Krishna, the Godavari appears to be a significant contributor of heavy metals to the Bay of Bengal. Considering the enormous sediment load of the Godavari River—170 million tons/yr, the heavy metal fluxes to the Bay of Bengal is very significant. Except for the Pranhita, other tributaries of the Godavari do not contribute significant loads of heavy metals. All the metals show high correlation among themselves and the correlation is more pronounced in suspended sediments than in the bed sediments. The heavy-metal distribution, fractionation, and its relationship with total suspended sediments and depth in various parts of the basin are discussed in detail. 相似文献
10.
Suzanne L. Baldwin T. Mark Harrison John D. Fitz Gerald 《Contributions to Mineralogy and Petrology》1990,105(6):691-703
Isothermal, hydrothermal experiments were performed on two compositionally contrasting hornblendes from amphibolites in order to examine Ar diffusion behavior in metamorphic hornblendes. Ten experiments on sample RF were performed at temperatures of 750°C, 800°C, and 850°C and pressures of 1 kbar using measured grain radii of 158, 101, and 34 m. Eight experiments on sample 118576 were performed under the same conditions using measured grain radii of 145, 77, and 25 m. Minor (<5%) alteration was observed in high temperature runs. Diffusion coefficients were calculated from measured radiogenic 40Ar loss following treatment assuming a spherical geometry for the mineral aggregate. Diffusivities calculated for different grain sizes vary by up to an order of magnitude for a given temperature indicating that the effective diffusion radius was less than the measured grain radius. Diffusivities for RF and 118576 calculated for grain radii of 101 and 145 m, respectively, form a linear array on an Arrhenius diagram with slopes indicating activation energies of 60 kcal/mol. No correlation between Mg number (100 Mg/(Mg+Fe)) and activation energy was observed. Diffusivities calculated for these experiments are higher than previously reported results from similar experiments performed on hornblendes. A comparison of results for 34 m splits from these two studies indicates higher apparent diffusivities (by a factor of 5), which probably result from observed phyllosilicate inter-growths (chlorite) and/or exsolution lamellae that partition the metamorphic hornblendes into smaller subdomains. Diffusivities calculated for experiments performed on 65 m and 34 m splits of 40Ar/39Ar standard MMhb-1 at 800°C and 1 kbar are consistent with a previously reported activation energy of 65 kcal/mol. Arrhenius parameters which emerge from the empirical model of Fortier and Giletti (1989) agree with experimental results to within analytical uncertainty. Although results of these experiments support previously reported estimates of the activation energy of 40Ar in hornblende (60 kcal/mol), phyllosilicate intergrowths and/or microstructures such as exsolution lamellae within the two metamorphic hornblendes result in extremely small diffusion domains, which may lead to lower Ar retentivities and lower closure temperatures. The effective diffusion dimension for 40Ar in hornblende is not likely to be defined by dislocations but rather by some larger structure within the crystal. TEM and SEM studies may provide some insight into the effective diffusion dimension for 40Ar in amphiboles, thereby enabling better estimates of closure temperatures and more precise temperature-time reconstructions. 相似文献
11.
A total of 42 aquatic particulate sample:, (suspended matter and < 63 m surficial sediments) was collected from 11 large rivers in eastern China. Contents of both major elements (Al, Si, Ca, Mg, K, Na, Ti, Fe, Mn) and trace elements (Cu, Pb, Zn, Cd, Cr, Co, Ni, V) in the particulate samples were analyzed. The geographic variations of river particulate compositions were studied. The results showed that the Yellow River particulates contained a notably high content of Ca and a low content of Al. Except for the Yellow River, A1 contents in particulates increased from the northern rivers to the southern rivers, while K and Na decreased. Trace elements were relatively enriched in the southern river particulates. The geographic variations seemed to be related to the weathering types and geological background within the river basins. The average composition of river particulates in China was then estimated. Based on the Chinese river data from this paper, as well as on the literature data for other main world rivers, a new estimation of the global average particulate composition was reported. Since the earlier estimations in the literature were not concerned with or at best concerned only with few of the Chinese rivers which contribute a major proportion to the global load of river particulates, this new estimation may be more reasonable. 相似文献
12.
John W. Morse Dwight K. Gledhill Karen S. Sell Rolf S. Arvidson 《Aquatic Geochemistry》2002,8(1):3-13
In sediments from the continental slope of the Northern Gulf of Mexico, generally,the degree of iron pyritization (DOP) is low (<0.1) and dissolved sulfide is belowdetection limits (5 M), whereas dissolved Fe is typically about 50 to100 M. Therefore, the dissolution of kinetically reactive iron minerals generallydominates over the rate of sulfide production in sediments throughout this region.However, in sediments where hydrocarbons have been added via seepage from thesubsurface, dissolved-Fe is undetectable, DOP can approach 1, and high concentrationsof dissolved sulfide (up to 11 mM) are commonly present. Even though thesesediments have high total reduced sulfide (TRS) concentrations (typically 150 to370 mol gdw-1), their average C/S ratio is about 4 times that of normal marine sediments reflecting the major input of hydrocarbons. DOP is significantly (20%) higher when calculated using reactive-Fe extracted by citrate dithionite than by cold 1N HCl. This difference is primarily due to the greater extraction efficiency of the cold HCl method for silicate-Fe. TRS tends to rise to a maximum, and remains close to constant even at high (mM) dissolved sulfide concentrations. These TRS concentrations, therefore, represent the size of the ``kinetically' reactive-Fe pool during early diagenesis. 相似文献
13.
Suspended and bed sediments collected from the entire region of the Krishna River and its major tributaries were analyzed for heavy metals (V, Cr, Mn, Fe, Co, Ni, Cu, Zn, and Pb) by the thin-film energy dispersive x-ray fluorescence technique. There is considerable variation in the concentration of elements towards downstream, which may be due to the variation in the subbasin geology and various degrees of human impact. Suspended particles are enriched in heavy metals throughout the basin relative to bed sediments. The heavy metals are enriched in coarse size fractions (10–90 µm) throughout the Krishna River except its tributary Bhima, where finer fractions (2 µm) dominate. Transition elements correlate very well with each other. There is a striking similarity between the bed sediments of Krishna River and the Indian average. When the annual heavy metal flux carried by the Krishna River was estimated, and viewed in relation to the other major riverine transport, the Krishna is seen to be a minor contributor of heavy metals to the Bay of Bengal. 相似文献
14.
15.
Amy Townsend-Small Michael E. McClain Jorge L. Noguera Jay A. Brandes 《Geochimica et cosmochimica acta》2008,72(3):732-740
Few studies have examined the dynamics of sediments and suspended organic matter and their export from headwater basins in the Andes Mountains to the Amazon River, despite the fact that the Andes are the primary source of sediments to the lower Amazon basin. We measured river discharge as well as the concentration, δ15N, δ13C, %N, and %OC of coarse and fine suspended sediments (CSS and FSS) in the Chorobamba River, located in the central Andean Amazon of Peru. Samples were taken at least weekly over an entire year (July 2004-July 2005), with additional sampling during storms. Concentrations of particulate organic matter (POM) were generally low in the study river, with concentrations increasing by up to several orders of magnitude during episodic rain events. Because both overall flow volumes and POM concentrations increased under stormflow conditions, the export of POM was enhanced multiplicatively during these events. We estimated that a minimum of 80% of annual suspended sediment transfer occurred during only about 10 days of the year, also accounting for 74% of particulate organic carbon and 64% of particulate organic nitrogen transport. Significant differences occurred between seasons (wet and dry) for δ13C of coarse and fine POM in the Chorobamba River, reflecting seasonal changes in organic matter sources. The time series data indicate that this Andean river exports approximately equal amounts of fine and coarse POM to the lower Amazon. The observation that the vast majority of sediments and associated OM exported from Andean rivers is mobilized during short, infrequent storm events and landslides has important implications for our understanding of Amazon geochemistry, especially in the face of incipient global change. 相似文献
16.
A Greek lignite fly ash was selected because of its hydraulic properties and was pulverized to produce a specific surface of 8300 cm2/g, and a gradation with D15, D50, and D85 equal to 1.3 m, 6 m and 20 m, respectively. The pulverized fly ash suspension properties were optimized by adding a suitable superplasticizer and a suitable accelerator at optimum dosages. The experimental evaluation of suspension properties included sedimentation tests, viscosity'measurements, rheological properties, setting times and development of strength with time. Groutability and effectiveness were evaluated by injecting selected suspensions into clean sands. Pulverization improves remarkably the behavior of fly ash suspensions. Suspensions with water to solids ratios of 1.5:1 and 2:1 by weight and containing additives, behave as Bingham fluids, have apparent viscosity lower than 70 cP, bleed capacity lower than 5%, initial setting time lower than 24 h, and can be injected into relatively coarse sands. These characteristics are comparable to those obtained for ordinary and microfine cement suspensions, showing that pulverized fly ash suspensions can be used for permeation grouting. 相似文献
17.
With a mean annual flow of 5.9×1011m3yr–1 and sediment load of 1600x1012gyr–1 the Ganges river ranks second and third, respectively, in terms of water flow and sediment load among the world's rivers. Considering the enormous sediment transport by Ganges to the Bay of Bengal, a study was conducted on the size distribution and mineral characteristics of the suspended sediments of the Ganges river and is reported here. Most of the sediment load has a size range between <4–5.75 ). The sediments are mostly medium to coarse silt and are poorly sorted. Mica dominates among the clay minerals, followed by chlorite, vermiculite, kaolinite, and smectite. Due to differences in geology, smectite becomes a major clay mineral in downstream rivers. At Calcutta, the clay mineral transport in millions of tons per year is 18,464, 8000, and 2147, for mica, smectite, and chlorite, respectively. 相似文献
18.
山西应县护驾岗冲沟阶地地层形成于66.46～33.62 ka,根据该剖面地层的粒度分布特征对该地区冲沟阶地的沉积环境进行了探讨。护驾岗冲沟阶地剖面的粒度分布特征显示:(1)剖面地层总体表现为自下而上由粗到细的正韵律沉积特征,结合野外观察将其分为4段(A—D段);(2)A段粒度分布特征变化不大,均以细砂为主,频率曲线为不对称单峰,概率累积曲线为2段式,以跃移搬运为主,分选相对较好,水动力较强,沉积环境稳定;(3)B—C段粒度分布特征变化较大,以粉砂和细砂为主,频率曲线为不对称双峰,概率累积曲线为2段式,以跃移搬运为主,分选较差,水动力较强,沉积环境不稳定;(4)D段粒度分布特征变化不大,以粉砂为主,频率曲线为不对称单峰,概率累积曲线为2段式,以悬移搬运为主,分选相对较好,水动力较弱,沉积环境稳定。总体来说,冲沟阶地形成于河流沉积环境,顶部为河漫滩沉积环境。粒度分布特征与古里雅冰芯氧同位素变化基本一致,因此护驾岗冲沟阶地粒度特征与沉积环境的变化归因于气候变化。 相似文献
19.
A. Kamarianos Dr. X. Karamanlis Dr. S. Dellis S. Kilikidis Dr. Th. Kousouris G. Foties 《GeoJournal》1992,28(1):73-80
This paper refers to the morphometric and hydrological conditions, as well as to the physical and chemical characteristics of the Kerkini reservoir (N Greece) and determines the trophic status. The flushing rate, and the residence time of the water show clearly the dominance of the riverine system upon the lacustrine circulation pattern. The shallowness of the reservoir, the inflow of river Strimon, and the nearly continuous functioning of the dam throughout the year should be considered as the factors influencing the circulation of the water in the reservoir. Phosphorous mean annual value, mean annual and maximum values of chlorophyll-a were found 106.6 g P 1–1, 18.4 g 1–1, 29.7 g 1–1 respectively. There is a tendency of the reservoir to decline into a hypertrophic state from a eutrophic one. River Strimon contributes significantly to the overloading of the reservoir by nitrogenous agricultural effluents. 相似文献
20.
Gerald L. Crow Marlin J. Atkinson Benny Ron Shannon Atkinson Arleene D. K. Skillman George T. F. Wong 《Aquatic Geochemistry》1998,4(3-4):469-480
Captive whitetip reef sharks, Triaenodon obesus,at Sea Life Park (SLP) Hawaii, Waimanalo, Hawaii develop goitre, whereas, T. obesus at the Waikiki Aquarium (WAQ), Honolulu,Hawaii do not develop goitre. To determine theeffects of natural concentrations of iodine on thereduction of goitre, two sharks from SLP with goitrewere placed in an enclosed coastal lagoon with naturalseawater. Using ultrasound measurements the twogoitres were initially 11.4 cm and 14.6 cm in depthand after 3 months decreased to 4.7 cm and 5.7 cm. Radioimmunoassay analysis of the thyroid hormoneT3 sera concentrations were initially 0.22 ng/mland 0.33 ng/ml and increased to 1.84 ng/ml after beingplaced in the lagoon. Sera T4 were initially0.93 ng/ml and 0.99 ng/ml and increased dramaticallyto 17 ng/ml and 56 ng/ml. Over the six month samplingperiod, two resident sharks in the lagoon with normalthyroids had sera T3 concentrations from 0.89ng/ml to 1.1 ng/ml, and sera T4 concentrationsfrom 3.1 ng/ml to 7.9 ng/ml. The hypothyroidcondition in the SLP goitred-sharks is likely linkedto the low environmental iodide (<0.005 M), andhigh nitrate (111 M) of SLP water. The WAQwell-water facility was characterized by anoxic waterwith high iodide (0.60 M), total iodine (1.90M), and typical nitrate (24.6 M)concentrations of interstitial groundwater. Thedifference of iodide concentration of SLP and WAQ tankwater (<0.005 M versus 0.60 M) wasdirectly related to the hydrogeology of the well-watersources. To avoid goitre in marine aquarium systems,we recommend maintaining iodide concentrations of atleast 0.15 M. 相似文献