A hydrogeochemical survey of Kilimanjaro (Tanzania): implications for water sources and ages

Kilimanjaro, Tanzania, the highest mountain in Africa, has undergone extensive hydrologic changes over the past century in an area where water resources are critical. A hydrochemical and isotopic synoptic sampling program in January 2006 is used to characterize hydrogeology, hydrology, and water quality of the area. Samples were collected from the summit and southern side of Kilimanjaro and the Moshi region (Tanzania). Sample sources included four glaciers, seven groundwater wells, 12 rivers, 10 springs, precipitation, and a lake. Analyses included major ion chemistry, stable isotopes of water (¹⁸O and D); in addition, seven samples were analyzed for tritium. The samples generally have good water quality with the exception of three samples with elevated fluoride concentrations (>3 mg/L) and elevated nitrate concentrations (>2.5 mg/L NO₃ as N). There is a strong elevation control on stable isotopes, with an apparent elevation effect of – 0.1 ‰ δ¹⁸O per 100 m rise in elevation (R ² = 0.79). The results, including the tritium values, show that the hydrogeologic system is comprised of both local and regional flow systems, and that regional rivers are receiving significant inflow from shallow groundwater, and at very high elevations the hydrologic system is derived from groundwater, precipitation, and glacial melt water.     

Hydrogeological and hydrogeochemical characterization of a karstic mountain region

Karstic limestone formations in the Mediterranean basin are potential water resources that can meet a significant portion of groundwater demand. Therefore, it is necessary to thoroughly study the hydrogeology and hydrogeochemistry of karstic mountain regions. This paper presents a detailed hydrogeological and hydrogeochemical characterization of the Nif Mountain karstic aquifer system in western Turkey, an important recharge source for the densely populated surrounding area. Based on the geological and hydrogeological studies, four major aquifers were identified in the study area including the allochthonous limestone in Bornova flysch, conglomerate-sandstone and clayey-limestone in Neogene series, and the Quaternary alluvium. Physicochemical characteristics of groundwater were measured in situ, and samples were collected at 59 locations comprised of springs and wells. Samples were analyzed for major ions, isotopic composition, arsenic, boron and heavy metals among other trace elements. It was found that the hydrogeological structure is complex with many springs having a wide range of discharge rates. High-discharge springs originate from allochthonous limestone units, whereas low-discharge springs are formed at the contacts with claystone and limestone units. Using stable isotope analysis data, a δ¹⁸O-deuterium relationship was obtained that lies between the Mediterranean meteoric and mean global lines. Tritium analyses showed that low-discharge springs originating from contact zones had longer circulation times compared to the high-discharge karstic springs. Furthermore, hydrogeochemical data revealed that groundwater quality significantly deteriorated as water moved from the mountain to the plains. Heavy metal, arsenic and boron concentrations were generally within drinking-water quality standards with a few exceptions occurring in residential and industrial areas located at the foothills of the mountain. Elevated arsenic concentrations were related to local geologic formations, which are likely to contain oxidized sulfite minerals in claystones. It is concluded that Nif Mountain overall has a significant potential to provide high-quality water with a safe yield of at least 50 million m³/year, which corresponds to about 28% of the mean annual inflow to the Tahtali reservoir, a major water resource for the city of Izmir. An erratum to this article can be found at     

Evaluation of hydrogeochemical processes and groundwater quality for suitability of drinking and irrigation purposes: a case study in the Aosta Valley region,Italy

The present study aims to discuss the hydrogeochemical processes in the Aosta Valley region and assess the quality of its groundwater for suitability of drinking and irrigation purposes. One hundred twenty-two samples were collected from the Aosta Valley region in the years 2007 and 2008 (61 per year), and analysed for pH, electrical conductivity, total dissolved solids (TDS), total hardness, major cations and anions. The pH of the samples in both years indicated a near-neutral to alkaline nature of the groundwater. The cation and anion chemistry showed the general ionic abundance as: Ca²⁺ > Mg²⁺ > Na⁺ > K⁺ and HCO₃ ^?>SO₄ ^2?>Cl^?>NO₃ ^?>F^? in both years. Ca²⁺-Mg²⁺-HCO₃ ^? and Ca²⁺-Mg²⁺-Cl^?-SO₄ ^2? were the dominant hydrogeochemical facies. The computed saturation indices demonstrated that the groundwater was supersaturated with respect to dolomite and calcite in both years. The groundwater chemistry of the study area was mainly controlled by the dissolution of carbonate, sulphate and silicate minerals, as well as ion exchange processes. A comparison of the groundwater quality in relation to drinking water standards showed that most of the water samples were suitable for drinking and domestic uses. The computed water quality index (WQI) values of the study area groundwater ranged from 24 to 84 in the year 2007 and from 22 to 82 in the year 2008, and all the location fell under the Excellent to Good category. Quality assessment for irrigation uses revealed that the groundwater was good to permissible quality for irrigation; however, locally higher salinity, residual sodium carbonate (RSC) and magnesium hazard (MH) restricted its suitability for irrigation at a few sites. These results will be useful in implementing future measures in groundwater resource management at regional and national level.     

An overview of dissolved organic carbon in groundwater and implications for drinking water safety

Dissolved organic carbon (DOC) is composed of a diverse array of compounds, predominantly humic substances, and is a near ubiquitous component of natural groundwater, notwithstanding climatic extremes such as arid and hyper-arid settings. Despite being a frequently measured parameter of groundwater quality, the complexity of DOC composition and reaction behaviour means that links between concentration and human health risk are difficult to quantify and few examples are reported in the literature. Measured concentrations from natural/unpolluted groundwater are typically below 4 mg C/l, whilst concentrations above these levels generally indicate anthropogenic influences and/or contamination issues and can potentially compromise water safety. Treatment processes are effective at reducing DOC concentrations, but refractory humic substance reaction with chlorine during the disinfection process produces suspected carcinogenic disinfectant by-products (DBPs). However, despite engineered artificial recharge systems being commonly used to remove DOC from recycled treated wastewaters, little research has been conducted on the presence of DBPs in potable groundwater systems. In recent years, the capacity to measure the influence of organic matter on colloidal contaminants and its influence on the mobility of pathogenic microorganisms has aided understanding of transport processes in aquifers. Additionally, advances in polymerase chain reaction techniques used for the detection, identification, and quantification of waterborne pathogens, provide a method to confidently investigate the behaviour of DOC and its effect on contaminant transfer in aquifers. This paper provides a summary of DOC occurrence in groundwater bodies and associated issues capable of indirectly affecting human health.     

Integrated assessment of nonpoint source pollution of a drinking water reservoir in a typical acid rain region

Nonpoint source pollution generated by agricultural production and city construction has been studied for decades, but very few researches have been conducted on the regional assessment of nonpoint source pollution in the acid rain regions, particularly relating to the control of pollutant in the drinking water source areas. In this study, an integrated framework was applied to estimate nitrogen and phosphorous load in a typical acid rain influenced reservoir, China. The method comprised three separate steps: (1) a watershed model—soil and water assessment tools—was used to estimate nitrogen and phosphorous load from the upper stream watershed; (2) collection of acid rain samples, together with a GIS-based calculation to estimate the atmospheric deposition flux; (3) introduction of a simple export coefficient method. The case study indicated atmospheric deposition accounted for 56.75 % of total nitrogen load during the year, with the highest level of deposition load taking place during the wet season. Maximum phosphorous (93.37 %) was linked to the upstream runoff, originating from the upper watershed. Further analysis by watershed model and export coefficient method indicated forest exported most total nitrogen (27.72 %) and total phosphorous (58.78 %) in the upstream watershed. Results indicated that in the region influenced by acid rain, the nitrogen management should encompass the management of land use practices and the control of acid rain in catchments feeding into drinking water storage areas. It could be inferred that NOX emissions might cause both globe warming and eutrophication in the drinking water sources. This paper could provide a basis for water quality management in such regions.     

Assessment of hydrogeochemical processes in a coastal region: Application of multivariate statistical model

Hydrogeochemical studies have been carried out in a coastal region, using multivariate statistical model, for better understanding the controlling processes that influence the aquifer chemistry. Two principal components (PC1 and PC2) are extracted from the data set of chemical variables (pH, TDS, Ca²⁺, Mg²⁺, Na⁺, K⁺, HCO ₃ ^? , Cl^?, SO ₄ ^2? , NO ₃ ^? and F^?), which account for 79% of the total variation in the quality of groundwater. The PC1 (salinity controlled process) includes the concentrations of TDS, Mg²⁺, Na⁺, K⁺, Cl^?, SO ₄ ^2? and NO ₃ ^? , while the PC2 (alkalinity controlled process) comprises the concentrations of pH, HCO ₃ ^? and F^?. The spatial distribution of PC scores identifies the locations of high salinity and alkalinity processes. The first process corresponds to the influences of geogenic, anthropogenic and marine sources, and the second one to the influence of water-soil-rock interaction. Thus, the present study shows the usefulness of multivariate statistical model as an effective means of interpretation of spatial controlling processes of groundwater chemistry.     

Contamination risk and drinking water protection for a large-scale managed aquifer recharge site in a semi-arid karst region,Jordan

Karst aquifers in semi-arid regions are particularly threatened by surface contamination, especially during winter seasons when extremely variable rainfall of high intensities prevails. An additional challenge is posed when managed recharge of storm water is applied, since karst aquifers display a high spatial variability of hydraulic properties. In these cases, adapted protection concepts are required to address the interaction of surface water and groundwater. In this study a combined protection approach for the surface catchment of the managed aquifer recharge site at the Wala reservoir in Jordan and the downstream Hidan wellfield, which are both subject to frequent bacteriological contamination, is developed. The variability of groundwater quality was evaluated by correlating contamination events to rainfall, and to recharge from the reservoir. Both trigger increased wadi flow downstream of the reservoir by surface runoff generation and groundwater seepage, respectively. A tracer test verified the major pathway of the surface flow into the underground by infiltrating from pools along Wadi Wala. An intrinsic karst vulnerability and risk map was adapted to the regional characteristics and developed to account for the catchment separation by the Wala Dam and the interaction of surface water and groundwater. Implementation of the proposed protection zones for the wellfield and the reservoir is highly recommended, since the results suggest an extreme contamination risk resulting from livestock farming, arable agriculture and human occupation along the wadi. The applied methods can be transferred to other managed aquifer recharge sites in similar karstic environments of semi-arid regions.     

Chemical analysis of drinking water from some communities in the Brong Ahafo region

This study consisted of the determination of the trace metals and some physiochemical properties in drinking water samples from the Brong Ahafo region of the Republic of Ghana, where drinking water samples are not treated before it is consumed. The purpose was to ascertain the quality of water from these sources. Samples were taken from fifteen sampling points and analyzed for the following parameters Fe, Cu, Mn, Zn, Al, NO₃ ^?, NO₂ ^?, SO₄ ², PO₄ ^2?, and F^? using the procedure outline in the palintest photometer method. The data showed the variation of the investigated parameters in samples as follows: pH 5.57-7.54, conductivity (EC) 35-1216 us/cm, turbidity 3.25-72.50 NTU,PO₄ ^2?1 0.32-9.30 mg/L,F 0.32-1.05 mg/L,NO₃ ^? 0.09-0.99 mg/L,NO₂ ^? 0.006-0.114 mg/L, SO₄ ^2? 3.33-8.02 mg/L, Cu 1.19-2.75 mg/L Fe 0.05-0.85mg/L, Zn 0.04-0.15 mg/L, Mn 0.003-0.011 mg/L and Al 0.05-0.15 mg/L. The concentrations of most of the investigated parameters in the drinking water samples from Brong Ahafo region were within the permissible limits of the World Health Organization drinking water quality guidelines. There were no correlations between metal concentrations in the drinking water samples.     

High resolution regional hydrogeochemical baseline mapping of stream water of Wales,the Welsh borders and West Midlands region

The stream water hydrogeochemical database, produced by the Geochemical Baseline Survey (GBASE) of the British Geological Survey, has recently been enhanced in the light of experimental pilot studies in North Wales, to meet a wider range of economic and environmental objectives which require modern, integrated and strategic geochemical surveys for their implementation. Hydrogeochemical data are therefore now collected, in conjunction with geochemical data for stream sediments, soil samples and mineral concentrates. The density of sampling, based on the collection of stream water at near-baseflow conditions during the late summer period each year, has been increased to one site per 1.75 km² and a broader spectrum of geochemical determinants introduced. Provisional regional datasets are being prepared for an extensive region covering Wales, the Welsh Borders, and part of the West Midlands representing over 17 000 sample sites. Bedrock geology and base metal sulphide mineralisation are particularly well reflected in the stream water chemistry at the regional scale. The influence of secondary factors, such as geomorphology, atmospheric controls, and anthropogenic contamination due to agriculture, urban, industrial and military developments, can also be readily distinguished.The data obtained by systematic high resolution sampling of first and second order streams, vary in concentration over three or four orders of magnitude for many of the analytes studied here. This compares with a range of only one or two orders of magnitude for many of the analytes in stream sediment samples. The extended range in values for stream water is an important factor in the gridding, plotting and production of relatively stable maps. They are relatively unaffected either by short temporal changes in stream water flow, which are attributable either to storm events noted during the sampling campaign, or by annual differences between wet and dry summers in different years. This has enabled a series of robust surface hydrogeochemical maps to be prepared for analytical data collected during the summer sampling campaigns conducted annually from 1989 to 1994. These maps provide a unique source of synoptic baseline information for a wide range of economic and environmental applications especially, when combined with other geoscience datasets in a GIS environment.     

Environmental effect and genetic influence: a regional cancer predisposition survey in the Zonguldak region of Northwest Turkey

The Cretaceous-Eocene volcano-sedimentary units of the Zonguldak region of the western Black Sea consist of subalkaline andesite and tuff, and sandstone dominated by smectite, kaolinite, accessory chlorite, illite, mordenite, and analcime associated with feldspar, quartz, opal-CT, amphibole, and calcite. Kaolinization, chloritization, sericitization, albitization, Fe–Ti-oxidation, and the presence of zeolite, epidote, and illite in andesitic rocks and tuffaceous materials developed as a result of the degradation of a glass shards matrix, enclosed feldspar, and clinopyroxene-type phenocrysts, due to alteration processes. The association of feldspar and glass with smectite and kaolinite, and the suborientation of feldspar-edged, subparallel kaolinite plates to fracture axes may exhibit an authigenic smectite or kaolinite. Increased alteration degree upward in which Al, Fe, and Ti are gained, and Si, Na, K, and Ca are depleted, is due to the alteration following possible diagenesis and hydrothermal activities. Micromorphologically, fibrous mordenite in the altered units and the presence of needle-type chrysotile in the residential buildings in which cancer cases lived were detected. In addition, the segregation pattern of cancer susceptibility in the region strongly suggested an environmental effect and a genetic influence on the increased cancer incidence in the region. The most likely diagnosis was Li-Fraumeni syndrome, which is one of the hereditary cancer predisposition syndromes; however, no mutations were observed in the p53 gene, which is the major cause of Li-Fraumeni syndrome. The micromorphology observed in the altered units in which cancer cases were detected may have a role in the expression of an unidentified gene, but does not explain alone the occurrence of cancer as a primary cause in the region.     

U/Th dating of fissure ridge travertines from the Kirsehir region (Central Anatolia Turkey): structural relations and implications for the Neotectonic development of the Anatolian block

Travertines exposed in several locations in Central Anatolia are the important lithological product for the interpretation of local neotectonics. The fissure-type travertines provide significant information about stress orientation during deposition. Two travertine masses cropping out in the Kirsehir region have been studied and dated by the U-series method to obtain new chronological constraints, determine dilation rates and contribute to studies on the recent tectonic evolution of the area. The Kusdili and Kayabasi travertine masses are located on the hanging wall of the Kirsehir Fault, similar to numerous fissure ridge banded travertine deposits which are inactive today in the region. While individual fissures of the Kusdili travertine mass (Late Pleistocene-Holocene) have been dilated at rates of between 0.303 and 0.386 mm yr–1 during deposition, the Kayabasi travertine mass (Late Pleistocene) produced measured dilation rates of between 0.136 and 0.187 mm yr–1. The central fissures, filled by banded travertine, roughly follow the ridge crests. While the ridge crest has a NNE-SSW trend in the Kayabasi travertine mass, the ridge crest of the Kusdili travertine mass shows a NE-SW trend. This difference may be related to the clockwise rotation of the stress tensors from Late Pleistocene to Late Pleistocene-Holocene in the region.     

The hydrogeochemical characterization of groundwater in Gafsa-Sidi Boubaker region (Southwestern Tunisia)

Gafsa region is one of the most productive artesian basins in Southern Tunisia. It is located in the southwestern part of the country, and its groundwater resources are developed for water supply and irrigation. Proper understanding of the geochemical evolution of groundwater is important for sustainable development of water resources in this region. A hydrogeochemical survey was conducted on the Plio-Quaternary shallow and on the Complex Terminal aquifers system using major (Ca, Mg, Na, SO₄, Cl, NO₃ and HCO₃) and minor (Sr) elements, in order to evaluate the groundwater chemistry patterns and the main mineralization processes occurring in this system. Hydrochemical and isotopic data were used in conjunction with hydrogeological characteristics to investigate the groundwater composition in these aquifers. It has been demonstrated that groundwaters acquire their mineralization principally by water–rock interaction, i.e. dissolution of evaporites (halite/gypsum, pyrite, etc.) and return flow of irrigation waters, and by anthropogenic activities due to the use of nitrogen (N) fertilizers–pesticides in agriculture. The isotopic study of “stable isotopes, radiocarbon and tritium” (Yermani 2002) shows that a paleoclimatic recharge is corroborated by the relatively low carbon-14 activities (5–25.3%) of the referred groundwater group samples, which were interpreted as recharge occurring during the late Pleistocene and the early Holocene periods. The water feedings of these aquifers are mainly provided by infiltration of precipitations, infiltration of irrigation water, lateral feeding from Cretaceous relieves from the South and the North and along recent and fossil drainage networks that constitute major freshwater sources in groundwater tables (Hamed et al., J Environ Protect 1:466–474, 2010a).     

Activation and regeneration of a soil sorbent for defluoridation of drinking water

Geomaterials can be cost-effective sorbents for use in water treatment. In this study, a heavily-weathered Tertiary soil from Xinzhou, China was used as a sorbent for defluoridation of high-fluoride drinking water. The soil is composed of quartz, feldspar, illite and goethite, with an Fe oxide content of 6.75%. Batch and column experiments were done to characterize the F⁻ removal properties and to develop an optimal activation and regeneration procedure. The soil can be regenerated following a simple base-acid rinsing procedure. This can be performed in situ, i.e., by passing the rinsing solutions directly through the treatment column. The same regeneration procedure can be used to activate the pristine soil. Fluoride sorption is described by a Freundlich isotherm model and the bulk of the uptake occurs within 1.5 h. Iron oxide coatings on soil particles and perhaps ≡FeOH surface groups at particle edges of illite grains are likely responsible for the soil's F-sorption property. As collected in the field, the soil has a low permeability and is thus unsuitable for direct use in a flow-through column. Heat-treatment at 400–500°C for 2 h, however, produces a granular and permeable sorbent. Although the soil's sorption capacity (150 μg/g ) is about a quarter of the low end range of values reported for commercially-available activated alumina, the sorption for F⁻ is specific. A batch sorption experiment in the presence of Cl⁻, SO₄²⁻ and HCO₃⁻ shows little or no competition from these other anions.     

Fluoride hydrogeochemistry and its occurrence in drinking water in Morappur region of Dharmapuri District,South India

Groundwater is the major source of freshwater in region devoid of surface water resources. Once such region is the Morappur area, Dharmapuri district of Tamilnadu, wherein groundwater is major source of water for all purposes. The area is reported to be severely affected by fluorosis due to excessive Fluoride in groundwater. The area comprises of rocks of Archaean age, namely Charnockite, Epidote Hornblende Gneiss and ultramafic rocks. The area has experienced numerous tectonic disturbances in which numbers of vertical joints have developed and are filled with quartz/feldspathic veins, and highly mineralised. Two aquifer systems have been identified in the area, namely the weathered aquifer and fractured aquifer. In order to understand the factors controlling high Fluoride concentration in groundwater, 149 groundwater samples were collected during pre and post-monsoon period. Analytical results indicate that 35% groundwater samples show Fluoride concentration more than 1.5 ppm (permissible limit). Results indicate that both the aquifer units are affected by high Fluoride and deeper aquifers are more affected. Biotite and Hornblende minerals present in the area and interact with groundwater to release Calcium, Magnesium along with Fluoride. Further chloro-alkaline indices indicate that calcium ions are replaced by sodium due to reverse ion exchange, leading to high concentration of Fluoride along with high concentration of Sodium. Government has taken measures to provide Fluoride-free drinking water from distant surface water sources. However, it is important to follow certain water management methods to improve the groundwater quality.     

双辽市北部地区地方性氟中毒与饮水氟质量浓度关系研究

本文在调查搜集双辽市氟中毒病情基础上,结合对饮用水氟质量浓度的实际检测数值,对其北部氟中毒与饮水氟质量浓度之间的关系进行了分析与探讨,确定了两者之间关系及其规律。