贵州碳酸盐岩风化壳主元素、微量元素及稀土元素的地球化学特征

选取贵州高原喀斯特地区的典型碳酸盐岩原生风化剖面为研究对象,研究主元素、微量元素及稀土元素在风化壳的迁移转化及其分布规律特征,为解释碳酸盐岩风化壳元素的地球化学变化提供依据。结果显示,从上陆壳标准化蛛网图可知,Pb、Co在剖面富集,而Na、K、Cr、Rb、Sr和Ba则亏损。风化壳∑REE的变化范围为167.4~1814.2μg/g,稀土元素从剖面下部往上逐渐减少,剖面中上部LREE比HREE淋滤程度大。稀土元素球粒陨石标准化后Ce正负异常,Eu轻微负异常。以风化前缘为分界,在风化前缘以下的土层,Ce负异常,风化前缘以上的土层,Ce正异常。此外,在风化壳岩土界面附近存在一个明显且突变的碱性障,岩土界面土样的元素含量较岩粉平均增加了21倍。我们的研究显示,风化剖面主元素和微量元素的变化波动特征较为一致,说明主元素和微量元素在风化过程中的地球化学行为较为一致。铁壳层中稀土元素的含量最低,与上陆壳稀土元素十分相近,为研究上陆壳与碳酸盐岩铁壳层之间的相互联系起到了一定的借鉴作用。     

Mean concentrations of volatile components,major and trace elements in magmatic melts in major geodynamic environments on Earth. I. Mafic melts

Mean concentrations of major components, trace elements, and volatile components in magmatic melts from Earth’s major geodynamic environments are estimated using our database (which comprises more than 1200000 analyses for 75 chemical elements—state for the beginning of 2016) on melt inclusions and quench glasses of rocks). The geodynamic environments are classified into (I) environments of oceanic plate spreading (mid-oceanic ridges), (II) areas affected by mantle plumes in oceanic plates (oceanic islands and lava plateaus), (III and IV) subduction-related environments (III are magmatic zones in island arcs, and IV are magmatic zones in active continental margins, in which magma-generating processes involve the continental crust), (V) continental rifts in areas with continental hotspots, and (VI) backarc spreading zones. The distribution of SiO₂ concentrations (>71000 analyses) in natural magmatic melts in all geodynamic environments is obviously bimodal, with maxima at 50–52 and 72–76 wt % SiO₂. Herein we discuss only mafic melts (40–54 wt % SiO₂). Mean concentrations and confidence levels are calculated for each geodynamic environment for the first time in three variants: from melt inclusions in minerals, from quench glasses in rocks, and from all data. Systematic variations in the mean compositions of melt inclusions and glasses in rocks are detected for all geodynamic environments. Primitive mantle-normalized multielemental patterns for mean concentrations of elements are constructed for magmatic melts from all geodynamic environments, and the mean ratios and their variations are calculated for trace incompatible and volatile components (H₂O/Ce, K₂O/Cl, La/Y, Nb/U, Ba/Rb, Ce/Pb, etc.) in melts from all environments.     

Composition of estuarine colloidal material: major and trace elements

Colloidal-sized material from the Patuxent River estuary, Maryland, was analyzed for more than 30 elements by instrumental neutron activation analysis. Sample data from stations ranging in salinity from 0.04 g/kg to 12 g/kg indicate that the winter colloidal material is dominated upstream by poorly crystallized clay minerals and iron oxide, but above a salinity of 10 g/kg, it consists primarily of carbonaceous material. Winter colloidal material decreases non-conservatively seaward from 29 to 0.6 mg/l. The summer colloidal material, however, is carbon-rich throughout the estuary and the amount of colloidal material in the upper water column does not change appreciably with increasing salinity. Many trace elements (Cs, Hf, Rb, Se, Th, V and the REE) covary with Al and probably are associated with the clay component. Other elements (As, Ba, Sb, Se, U and Zn) are considerably enriched relative to Al and may covary with the organic component. The results suggest that the freshwater winter colloidal system is a product of continental weathering processes, whereas the summer colloidal material is derived primarily from estuarine biological processes.     

Composition and variation of major and trace elements in Croatian bottled waters

Within the framework of the Pan-European project about the geochemistry of bottled mineral waters in Europe launched in 2007 by the European Geological Surveys (EGS) Geochemistry Expert Group fourteen brands of bottled natural waters from Croatia of both mineral and spring types were evaluated for getting more coherent spatial information about the natural variation of element concentration in bottled waters found at the European market. Results of chemical analysis show that not a single one out of fourteen analyzed bottled waters from Croatia exceeds the Croatian water standards sanctioning thereby their suitability for human consumption. Also, statistical tests performed for 41 analytes (including pH and EC) clearly show that the water chemistry is in a high degree of conformity with regional geology, depending on structural, stratigraphic and, above all, lithological diversity of aquifers. Thus Dinaric and Pannonian parts of Croatia differ largely with regard to their water types: Dinaric region is completely lacking mineral water types while, on the other side, in the Pannonian region even the spring waters show stronger mineralization in comparison with their Dinaric counterparts. Typically, all natural waters from Croatia bear the bicarbonate (HCO₃) signature. However, Ca–Mg cation pair combination is characteristic of spring waters while Na–K dominates in the mineral waters.     

Use of major and selected trace elements to describe mixing processes in a water reservoir

Data on temperature, major constituents and some trace elements, measured in the dissolved and particulate phases, were used to identify the hydrodynamics of a reservoir (the Bicaz reservoir, Romania). Results revealed that the reservoir experiences two thermal stratifications per year (summer and winter). However, the summer stratification is delayed by the high river inflow of June–July. Two layers were identified, a surface and a deep layer, whose location and impact vary with time. The surface layer originates from the river inflow (intrusion layer) and the deep current is produced by the outflow (velocity current). According to season, the river inflow either supplies the deep current or remains recordable up to the dam. Consequently, the structure of the water column, and thus the biogeochemical processes within it, are governed both by thermal stratification and by these layers.     

高铝粉煤灰中部分主微量元素的分布规律研究

本文旨在研究部分主微量元素在高铝粉煤灰中的分布规律,从而为其资源化利用提供科学依据。首先根据高铝粉煤灰的物相组成特点采用新的分离方法将之分离为三个相(或相组合):铁质微珠、莫来石-刚玉相以及玻璃相;然后分别用化学分析和ICP-MS测试主微量元素在高铝粉煤灰、铁质微珠以及莫来石-刚玉相中的含量,并结合相关数据计算出这些元素在玻璃相中的含量。结果表明,除Al、Mn外,其他元素均在玻璃相中有不同程度的富集;除Al外,其他元素则在莫来石-刚玉相中有不同程度的贫化;除Ti以外的铁族元素以及除Ga、Pb以外的金属成矿元素均在铁质微珠中富集,其他元素则在其中贫化。     

低熟煤中的孢粉与常量元素和微量元素的相关性初探

运用电离耦合等离子体原子发射光谱(ICP-AES)和X射线荧光光谱分析(XRF),对新疆八道湾煤矿中侏罗统西山窑组煤中的孢粉角质层进行了分析,测定了煤中的常量和微量元素。并对煤中孢粉和共伴生元素进行了回归分析,探讨了微量和常量元素的煤岩学及孢粉学属性,在微量元素与孢粉的煤相学应用方面作了初步尝试。结果表明,成煤的蕨类植物孢子和裸子植物花粉与某些常量元素和微量元素有着很高的相关性;蕨类植物孢子和裸子植物花粉的相对含量在煤中具有互补性,决定了它们与微量元素的关系也具有一定的互补性。     

Natural concentrations of major and trace elements in some Norwegian bedrock groundwaters

Twenty-eight groundwater samples have been collected from boreholes in bedrock aquifers in Nord Trøndelag (Central Norway), the Hvaler archipelago and other areas around Oslofjord (South-eastern Norway). A clear relationship is demonstrated between many chemical parameters and lithology or geographical location. The parameters electrical conductivity, Cl⁻, SO₄²⁻, F⁻, Na, Al, Fe, Be, Bi, Cd, Cu, La, Mo, Pb, Th, Tl, U, Y, Zn, Zr, B, Rn, and Si have generally higher values in the Iddefjord Granite of Hvaler, while pH, alkalinity, Ca, Mg, Cs, Rb, and Sr are highest in Trøndelag. Several parameters such as F⁻, Na, Fe, U, Rn and possibly Al exceed drinking water norms on Hvaler. Measured values of the analyzed parameters compare well (except F⁻) with the Dutch “A” (background) values, developed for assessment of anthropogenic contamination. The authors warn, however, against uncritical use of “norms” developed in countries with other dominant lithologies than Norway.     

Exploring the joint compositional variability of major components and trace elements in the Tellus soil geochemistry survey (Northern Ireland)

The complexity of modern geochemical data sets is increasing in several aspects (number of available samples, number of elements measured, number of matrices analysed, geological-environmental variability covered, etc), hence it is becoming increasingly necessary to apply statistical methods to elucidate their structure. This paper presents an exploratory analysis of one such complex data set, the Tellus geochemical soil survey of Northern Ireland (NI). This exploratory analysis is based on one of the most fundamental exploratory tools, principal component analysis (PCA) and its graphical representation as a biplot, albeit in several variations: the set of elements included (only major oxides vs. all observed elements), the prior transformation applied to the data (none, a standardization or a logratio transformation) and the way the covariance matrix between components is estimated (classical estimation vs. robust estimation). Results show that a log-ratio PCA (robust or classical) of all available elements is the most powerful exploratory setting, providing the following insights: the first two processes controlling the whole geochemical variation in NI soils are peat coverage and a contrast between “mafic” and “felsic” background lithologies; peat covered areas are detected as outliers by a robust analysis, and can be then filtered out if required for further modelling; and peat coverage intensity can be quantified with the %Br in the subcomposition (Br, Rb, Ni).     

Modelling of major elements in mantle-melt systems using trace element approaches

Major elements can be modelled in ways similar to the quantitative petrogenetic modelling used for trace elements. In contrast to modelling with trace elements, however, modelling with major elements is constrained by the stoichiometry of the solid phases. Within these constraints, the same equations for partial melting and crystallization which have been used to such advantage for trace elements may be used for major elements.Calculated MgO and FeO abundances in a mantle-melt system are used as an example of the modelling technique. Such modelling yields limited fields of permissible melts and residues for a given parent composition, but does not give the paths of melting. It does allow the temperature and extent of melting which gave rise to a melt to be determined from the MgO and FeO abundances of the melt or residual solid. Applying the results of the modelling to igneous rocks and ultramafic nodules leads to the following conclusions, which are subject to the uncertainties in the available distribution coefficients. Least differentiated basalt glasses from the ocean floor are derived from parent melts with less than 15.5 weight % MgO and 8.2 wt. % FeO. Komatiites may be derived by less than 60% melting of a pyrolite source leaving a residue of olivine and pyroxene. Many nodules from the subcontinental mantle appear to be residues of large fractions of melting (>30%) at high temperature and pressure, whereas ultramafic nodules from oceanic basalts appear to be residues of smaller fractions of melting (<30%) at lower temperatures and pressures.     

桂岭岩体稀土、微量元素地球化学特征研究

文章运用岩石地球化学方法,对桂岭岩体的构造环境和地球化学特征进行了研究,结果显示：桂岭岩体岩石平均LREE／HREE=7．68,（La／Yb）N-6．77,（La／Sm）N-4．65,（Gd／Yb）N-1．04,平均δEu=0．45〈1,表明轻重稀土轻度分异,轻稀土相对富集,轻稀土内部分馏明显,存在负铕异常;岩体明显亏损Nb、Sr、Ti,显示桂岭岩体的源区可能主要来自地壳,是地壳环境下壳源岩石发生部分熔融的产物;研究表明,桂岭岩体形成于挤压一伸展的大地构造环境。     

白钨矿晶体结构及微量元素替代机理

白钨矿是钨矿床中主要的载钨矿物,其独特的晶体结构使其富含微量元素,被广泛用于示踪钨成矿过程与流体源区。本文对南岭地区氧化型矽卡岩、还原型矽卡岩、黑钨矿-石英脉型、白钨矿-石英脉型、(矽卡岩-)云英岩型、(石英脉-)云英岩型钨矿床中白钨矿开展矿物组合和X-射线单晶衍射分析,实验结果显示：(1)白钨矿晶体结构存在一定差异,矽卡岩型钨矿中白钨矿Ca-O键长变化较大(0.0043 nm),石英脉型钨矿中白钨矿次之(0.0035 nm),云英岩型钨矿中白钨矿最小(0.0034 nm);(2) Ca-O键长的差异对最优替代稀土元素影响较大,氧化型矽卡岩钨矿中白钨矿从成矿早期到晚期,最优替代稀土元素从Pr-Nd(进变质阶段)、Pr-Sm(退变质阶段)转变为Nd-Sm(石英-方解石-萤石阶段),而(石英脉-)云英岩型钨矿中白钨矿呈现以Sm³⁺为中心(Nd-Gd)的最优替代元素;(3)矽卡岩型和云英岩型钨矿中白钨矿,稀土元素主要通过Nb⁵⁺耦合替代和空位替代进入白钨矿晶格,石英脉型钨矿的白钨矿中,稀土元素主要通过空位替代和Na⁺耦合替代进...     

Baseline models of trace elements in major aquifers of the United States

Trace-element concentrations in baseline samples from a survey of aquifers used as potable-water supplies in the United States are summarized using methods appropriate for data with multiple detection limits. The resulting statistical distribution models are used to develop summary statistics and estimate probabilities of exceeding water-quality standards.The models are based on data from the major aquifer studies of the USGS National Water Quality Assessment (NAWQA) Program. These data were produced with a nationally-consistent sampling and analytical framework specifically designed to determine the quality of the most important potable groundwater resources during the years 1991–2001.The analytical data for all elements surveyed contain values that were below several detection limits. Such datasets are referred to as multiply-censored data. To address this issue, a robust semi-parametric statistical method called regression on order statistics (ROS) is employed.Utilizing the 90th–95th percentile as an arbitrary range for the upper limits of expected baseline concentrations, the models show that baseline concentrations of dissolved Ba and Zn are below 500 μg/L. For the same percentile range, dissolved As, Cu and Mo concentrations are below 10 μg/L, and dissolved Ag, Be, Cd, Co, Cr, Ni, Pb, Sb and Se are below 1–5 μg/L.These models are also used to determine the probabilities that potable ground waters exceed drinking water standards. For dissolved Ba, Cr, Cu, Pb, Ni, Mo and Se, the likelihood of exceeding the US Environmental Protection Agency standards at the well-head is less than 1–1.5%. A notable exception is As, which has approximately a 7% chance of exceeding the maximum contaminant level (10 μg/L) at the well head.     

Compositional characteristics and Existing Forms of Major,Trace and Rare—earth Elements in Cassiterite,Dupangling Tin Ore Field,Guangxi

Trace elements in cassiterite,including Ta,W,Fe,Mn,Ti,Zr,V,Sc,Si,Al,In,Ga,Ge,Be,Bi,Ag,Sb,As,Cu,Pb,Zn,Co and REE,have been studied by many workers (Shan Zhenhua etal.,1998;Huang Zhou Tianren et al.,1987;Wu Qingsheng et al.,1988;Hu Zening,1988,Li Zhong-qing 1988 Mingzhei et al.,1988;Wang Lihua et al.,1988;Liu Kanghuai,1990).Up to now,however,most of the previous studies are concerned with trace-element variations in cassiterites of different occurrences and colors from different types of ore deposits,Data concerning the modes of occurrence of these trace elements are rare,except for the contention that Nb-Ta,Fe^2 -Mn-Fe^3 and W-Fe^3 may substitute isomorphously for Sn as pointed out by Zhou Tianren et al.(1987) and Moller et al.(1988).In this paper we are concerned with the compositional characteristics as well as the modes of occurrence of trace elements in cassiterites from quartz veins and greisens in the Dupangling tin field,Guangxi,based on multivariate statistical analyses.Tin mineralization in the Dupangling area is found associated with the medium-to fine-grained protolithionite-albite granite(γ5^2b) and its outer contacts.Cassiterite occurs,with wolframite,both in quartz veins in the contact and in greisens within the granite.^1) Spatially,greisens become dominant over quartz veins in the contact andin greisens with the granite.^1)Spatialy,gresens become dominant over quartz veins in going from the contact to the interior of the granite and with increasing depth.The greisens are of various shapes.The vein-shaped and the sheet-shaped greisens at the top of the granie are rich in quartz and the chambered greiens always constitute rich ores and contain abundant topaz or mica.Genetically,Sn,W mineralizations associated with the protolithionite-albite granite(γ5^2b) are considered to have been formed from fluid melt derived from the ore-forming magma responsible for the granite(γ5^2b).     

The association of major,minor and trace inorganic elements with lignites. I. Experimental approach and study of a North Dakota lignite

Lignites resemble peats, the precursors of coals, in containing many carboxylic acid and other functional groups. Consequently much of the relatively small amount of inorganic matter in lignites is present as cations in carboxylates and in chelated coordination complexes, and not only as distinct mineral phases. Consequently the distribution of inorganic matter in lignites will be influenced by the structure of the organic matter, as well as by microbial processes in peats and the geochemical processes involving erosion of rocks and transport of mineral grains and cations in solution. The objective of this study was to seek information on the distribution of major, minor and trace elements in different forms of combination, and in particular to document organic/inorganic interactions in coal formation. Study of the first of five lignites is reported here. The coal (from the Hagel seam in North Dakota) was separated into five fractions by float/ sink methods, and the fractions were further separated into an ammonium acetate extract, an HCl extract and an insoluble residue. Analysis of the fractions (by atomic absorption, plasma arc emission, emission spectroscopy and neutron activation) was found to give much information on how elements were combined in the coals. Results of the fractionation indicate that Ca, Mg, Na, K, Sr, Ba and Mn were present largely or partly in ion-exchangeable form; appreciable amounts of K (illite), Ba (sulfate, carbonate) and Mn were also present in mineral phases. Some Al appeared to be present in organic association. Ti often occurs in sediments by substitution in clays, but we infer that substantial amounts are present here in both acidsoluble and acid-insoluble organic chelates. The considerable enrichment of a number of elements in the fractions of lowest specific gravity suggests that Be, Sc, Cr, Y, Yb, V, Ni, Cu and Zn are associated primarily or partly with the organic matter. The extent to which these elements are associated with the organic matter in this lignite is much greater than it is with the bituminous coals studied by others.     

Distribution of major and trace elements in La Luna Formation, Southwestern Venezuelan Basin

The La Luna Formation (Maraca section), Maracaibo Basin, was studied by means of V and Ni analysis of the bitumen, total organic carbon (TOC), total sulfur (St), major elements (Si, Al, Fe, Mg, Mn, Ca, Ti, Na, K, P), trace elements (V, Ni, Co, Cr, Cu, and Zn), and electron microprobe analysis (EPMA) of the whole rock, and St, major elements (Si, Al, Fe, Mg, Mn, Ca, Ti, Na, K, P), trace elements (V, Ni, Co, Cr, Cu, Zn, Mo, Ba, U, Th) and rare earth elements (La, Ce, Nd, Sn, Eu, Th, Yb, Lu) of the carbonate-free fraction. The results are discussed based on the organic and inorganic association of trace elements and their use as paleoenvironmental indicators of sedimentation. An association between V and organic matter is suggested by means of correlation between V and Ni vs. TOC, the use of EPMA (whole rock) and V and Ni concentrations (carbonate-free fraction), whereas Ni is found in the organic matter and the sulfide phase. Fe is present as massive and framboidal pyrite, whereas Zn precipitates into a separate phase (sphalerite), and Ni, Cu and, in some cases, Zn, can be found as sulfides associated with pyrite. Concentrations of V and Ni (bitumen), TOC, St, V, Ni, Cr, Cu and Zn (whole rock), U, Th, Mo (carbonate-free fraction) are indicative of changes in the dysoxic sedimentation conditions in the chert layers (TOC, St, V, Ni, Cu and low Zn and V/Cr <4) to euxinic anoxic conditions in the argillaceous limestone (TOC, St, V, Ni, Cu and high Zn and V/Cr >4). In the sequence corresponding to the argillaceous limestone, variations in the concentrations of TOC, St, V, Ni, Zn, Cu and Cr (whole rock) can be observed, also suggesting variable sedimentation conditions. The following is proposed: (i) sedimentation intervals under euxinic conditions associated with high contribution and/or preservation of organic matter, allowing a high concentration level of V and Ni in the organic phase and the accumulation of Cu, Zn and Ni (in a smaller proportion) in the sulfide phase; (ii) sedimentation intervals under anoxic conditions and in the presence of relatively lower H₂S, which allowed lower concentrations of V and Ni in the organic phase and higher concentrations of Cu, Zn, and Ni in the sulfide phase. Rare earth elements (REE) concentrations exhibit a marked increase in Ce, Nd, Sm, Eu, Y and Lu for the QM-3 interval, relative to Post-Archean Average Shale (PAAS). REE enrichment in shales has been related to the presence of phosphate minerals such as monazite or apatite. However, these minerals were not detected through XRD or EPMA in the whole rock or in the carbonate-free fraction. The association of REE with organic matter is suggested due to the absence of phosphate minerals, although assessment of these elements require further analysis.     

Geochemical factors controlling accumulation of major and trace elements in Greenland coastal and fjord sediments

 The major (Al, Ti, Ca, Mg, Fe, Mn, Si) and trace element (Cd, Cr, Cu, Hg, Li, Ni, Pb, V, Zn) concentrations in surficial (<20 cm) sediments from fjords and open coastal waters around Greenland have been determined. Regionally, high concentrations of Fe, Ti, Mg, Cr, Cu, Ni, and V occur in some west and east coast sediments, but they appear to be natural in origin, as there is no indication of anthropogenic influence. Chemical partition indicates that most of the heavy metals are structurally bound in various silicate, oxide, and sulfide minerals. These host minerals occur more or less equally in the coarse and fine sediment fractions (material >63 μm and <63 μm) and have accumulated at the same rate as other detrital clastic material. Provenance and glaciomarine deposition are the main factors controlling the abundance and distribution of the major and trace elements. The chemical composition reflects the mineralogical differences in the provenance of glacial marine material deposited by water and ice adjacent to Greenland. The main source of the sediments enriched in Ti, Fe, Mg, Cr, Cu, Ni, and V appears to be material derived from the volcanic rocks of the Mesozoic-Tertiary Provinces of Greenland by glacial erosion. Received: 26 June 1995 · Accepted: 11 August 1995     

Chemical partitioning of trace and major elements in soils contaminated by mining and smelting activities

Soils from historical Pb mining and smelting areas in Derbyshire, England have been analysed by a 5-step sequential extraction procedure, with multielement determination on extraction solutions at each step by ICP-AES. Each of the chemical fractions is operationally defined as: (i) exchangeable; (ii) bound to carbonates or specifically adsorbed; (iii) bound to Fe–Mn oxides; (iv) bound to organic matter and sulphides; (v) residual. The precision was estimated to be about 5%, and the overall recovery rates were between 85 and 110%. The carbonate/specifically adsorbed and Fe–Mn oxide phases are the largest fractions for Pb in soils contaminated by both mining and smelting. Most of the Zn is associated with Fe–Mn oxide and the residual fractions. Cadmium is concentrated in the first 3 extraction steps, particularly in the exchangeable phase. The most marked difference found between soils from the mining and smelting sites is the much higher concentrations and proportions of metals in the exchangeable fraction at the latter sites. This indicates greater mobility and potential bioavailability of Pb, Zn and Cd in soils at the smelting sites than in those in the mining area. The most important fraction for Fe and Al is the residual phase, followed by the Fe–Mn oxide forms. In contrast, the Fe–Mn oxide fraction is the dominant phase for Mn in these soils. In the mining area, most of the Ca is in the carbonate fraction (CaCO₃), while the exchangeable and residual phases are the main fractions for Ca at the smelting sites. Phosphorus is mainly in the residual and organic fractions in both areas. The exchangeable fractions of Pb, Zn and Cd in soils were found to be significantly related to the concentrations of these metals in pasture herbage.     

Migration and contamination of major and trace elements in groundwater of Madras city,India

Groundwater samples collected from both open and bore wells in an area of about 270 km² from Madras City, India, have been analyzed for major ions (HCO₃, Cl, Si, Na, Ca, and Mg) and trace elements (As, Se, B, V, Cr, Fe, Co, Pb, Cu, Zn, Cd, Mn, Ni, Mo, and Ba). The study reveals that the quality of potable water has deteriorated to a large extent. Seawater intrusion into the aquifer has been observed in nearly 50 percent of the study area. The toxic elements (As and Se) have already exceeded the maximum permissible limits of drinking water in almost the entire city. A positive correlation of As and Se with other toxic metals such as V, Cr, Fe, B, etc., indicates that all these elements are anthropogenic in origin. Applying multivariate analysis, the source for trace elements in groundwater has been grouped into two major factors: pollution and mobilization factors. The groundwater in the study area is largely contaminated by organic effluents and reflects the intensity of pollution caused by the overlying soil sediment and rapid infiltration of the pollutants.