Factors controlling fluoride contents of groundwater in north-central and northwestern Sri Lanka

Chemical characterization has been made of groundwater bodies at 294 locations in four village districts in north-central and northwestern Sri Lanka, with special focus on fluorine contamination. High fluoride contents in groundwater are becoming a major problem in the dry zone of Sri Lanka, and dental fluorosis and renal failures are widespread. Field measurements of temperature, pH, and electrical conductivity were made during sampling. Chemical analyses of the water samples were later made using atomic absorption spectroscopy, spectrophotometry, and titration. Fluoride concentrations in the study area vary from 0.01 to 4.34 mg/l, and depend on pH and the concentrations of Na, Ca, and HCO₃ ⁻. Basement rocks including hornblende biotite gneiss, biotite gneiss, and granitic gneiss seem to have contributed to the anomalous concentrations of fluoride in the groundwater. Longer residence time in aquifers within fractured crystalline bedrocks may enhance fluoride levels in the groundwater in these areas. In addition, elevated fluoride concentrations in shallow groundwater in intensive agricultural areas appear to be related to the leaching of fluoride from soils due to successive irrigation.     

Possibilities of exchanging know-how, scientific partners and information between China Society of Geochemistry and Brazilian Association of Geochemistry-SBGq

The Brazilian Society of Geochemistry--SBGq founded in 1985, is located at Rio de Janeiro, Brazil, having more than 300 affiliates that represent most of the principal Brazilian universities. The main SBGq way of divulgation is an international magazine-Geochimica Brasiliensis and a site： www.sbgq.org.br/. Regular meeting of SBGq is realized in each two years in odd years The last meeting it has been realized together the Geochemistry of Portuguese Language Countries and Geochemistry Symposium of the MERCOSUL countries （Argentina, Brazil, Paraguay and Uruguay）. During the even years are realized specific meeting as Environmental Geochemistry in Tropical Countries. The SBGq is associated with other Brazilian scientific societies as Latin American Association of Organic Geochemistry--ALAGO. During its existence the SBGq has published approximately 3000 papers related to the environment, lithogeochemistry, isotopes, surface geochemistry, organic geochemistry, coastal environmental geochemistry, secondary environments, hydrogeochemistry, exploration geochemistry, magmatic geochemistry, rare earth geochemistry, geochemistry of carbonations, biogeochemistry, mineral geochemistry, geochemistry vs. geochronology and geochemistry of precious metals.     

Four types of relationships between rainfall and paddy production in Sri Lanka

Due to the absence of marked thermal differences in Sri Lanka, the paddy-climate relationship has been confined to rainfall alone in this study. Increase in total paddy production is highly attributed by the increase in paddy lands rather than yields, particularly in the drier parts, called Dry Zone. The effective rainfall period for the two principal cropping seasons in Sri Lanka, Maha and Yala, were determined according to the crop calendar of the Districts. The deviation values from the trend lines of 20 years (1961–1980) observations in sown, harvest and yield were well correlated with the deviations from the mean rainfall. The effects of rainfall on paddy production are well pronounced in the Dry Zone during the Maha season and in the Wet Zone during the Yala season. From the statictical analyses, four types of relationship, were observed: (1) Type I is the positive relationship, (2) Type II is the negative relationship, (3) Type III is the no realtionship and (4) Type IV a complex one which has a positive relationship below certain critical rainfall value and no or negative relationship above the critical rainfall value. The combination of Types I and IV shows the areas which need irrigation facilities with proper water management while the combination of the Types II and III indicates the areas which are prone to frequent floods and waterloggings.     

Forecasting of groundwater level in hard rock region using artificial neural network

In hardrock terrain where seasonal streams are not perennial source of freshwater, increase in ground water exploitation has already resulted here in declining ground water levels and deteriorating its’ quality. The aquifer system has shown signs of depletion and quality contamination. Thus, to secure water for the future, water resource estimation and management has urgently become the need of the hour. In order to manage groundwater resources, it is vital to have a tool to predict the aquifer response for a given stress (abstraction and recharge). Artificial neural network (ANN) has surfaced as a proven and potential methodology to forecast the groundwater levels. In this paper, Feed-Forward Network based ANN model is used as a method to predict the groundwater levels. The models are trained with the inputs collected from field and then used as prediction tool for various scenarios of stress on aquifer. Such predictions help in developing better strategies for sustainable development of groundwater resources.     

Destabilizing the identity–territory nexus: Rights-based discourse in Sri Lanka’s new political geography

This paper describes the changing discourses of territory in Sri Lanka and their utility in conflict relations. The primordial homeland has been at the center of Sri Lanka’s armed struggle, in which both Sinhalese and Tamil nationalisms have used claims of ancient and ethnically determined territories to justify their right to self-determination, territorial sovereignty, and armed struggle. This identity–territory nexus based on historical argument has been destabilized in Sri Lanka, however. Scholarly findings suggest that historical linkages between ethnicity and territory in Sri Lanka are highly problematic and are no longer effectual means for adjudicating territorial desires in Sri Lanka and producing stable homelands. I argue that rights-based territorial discourses have emerged to enhance the old historical justifications for territorial authority. New narratives based upon fulfilling or denying human rights have been put to work linking authority to territory based upon moral fitness and unfitness, political legitimacy and illegitimacy, and ultimately, upon which political actor deserves to rule the territorially bound population under its control. The first part of the paper examines historical narratives linking national homelands to identity as well as scholarly work that deconstructs this linkage. In part two, external sovereignty and political legitimacy are discussed as the starting point for understanding how rights-based discourses justify territorial claims. In part three, accusations related to human rights violations are described as an important vehicle for shaming political adversaries, undermining their legitimacy, and making and unmaking territorial claims in Sri Lanka.     

Conceptual model of the evolution of groundwater quality at the wet zone in Sri Lanka

 The evolution of groundwater quality at a wet zone in Sri Lanka was made clear using field investigation, chemical and isotopic analyses methods. In the wet zone, the concentrations of major ions and electrical conductivity (EC) in the groundwater are low with small seasonal change. Except for sodium, silica and chloride, the EC and other major ion concentrations increase along the groundwater flow direction. The contributions of bicarbonate and calcium ions to the increase in EC are the largest among the major ions. The groundwater quality shows calcium-bicarbonate type, the initial stage of the Chebotarev series. There is a seasonal change in isotopic composition. The isotopically lighter groundwater was found at the valley bottom in the rainy season. Under the very heavy precipitation conditions, the slope of the regression line between δD and δ¹⁸O and deuterium excess for groundwater are close to 8 and 10, respectively. In other cases, the slopes of the regression lines and deuterium excess are, less than 8 and 10, respectively. Received: 5 August 1998 · Accepted: 19 October 1998     

广东硇洲岛地下水化学演化及成因机理

地下水一直是广东硇洲岛唯一的水资源,但近年来许多地区地下水咸化趋势加剧,严峻威胁着岛上居民的用水安全,研究地下水化学演化及成因机理,对预防和减缓水质变咸意义重大。本文结合区域水文地质条件、地形地貌条件及水化学资料分析了整个岛屿地下水水质状况,在此基础上采用Piper三线图研究了水化学特征,并利用PHREEQC软件对水文地球化学演化规律进行模拟研究,结果表明:(1)海水入侵是造成地下水咸化的主要原因,咸化对水质的影响主要表现为Cl-的增加,Ca2+在区分该地区不同水体时反应灵敏,是良好的识别指标之一;(2)海水入侵的过程中,过渡带前缘不存在经受长期古海水演化而成的卤水与地下淡水的混合作用,地下水中Mg2+、Ca2+与Na+之间存在着强烈的离子交换,石膏、白云石及方解石处于不饱和状态;(3)浅层地下水与深层地下水之间无明显的水力联系,属于相对独立的地下水流系统。在全球变暖,海平面上升的总趋势下,海岛地下水开发必须合理规划、严格管理,以防引发大规模海水入侵灾害的发生。     

http://www.sciencedirect.com/science/article/pii/S1674987115000390

The demand for fresh water in Hambantota District, Sri Lanka is rapidly increasing with the enormous amount of ongoing development projects in the region. Nevertheless, the district experiences periodic water stress conditions due to seasonal precipitation patterns and scarcity of surface water resources.Therefore, management of available groundwater resources is critical, to fulfil potable water requirements in the area. However, exploitation of groundwater should be carried out together with artificial recharging in order to maintain the long term sustainability of water resources. In this study, a GIS approach was used to delineate potential artificial recharge sites in Ambalantota area within Hambantota. Influential thematic layers such as rainfall, lineament, slope, drainage, land use/land cover, lithology, geomorphology and soil characteristics were integrated by using a weighted linear combination method. Results of the study reveal high to moderate groundwater recharge potential in approximately 49% of Ambalantota area.     

Hydrogeologic assessment of escalating groundwater exploitation in the Indus Basin, Pakistan

Groundwater development has contributed significantly to food security and reduction in poverty in Pakistan. Due to rapid population growth there has been a dramatic increase in the intensity of groundwater exploitation leading to declining water tables and deteriorating groundwater quality. In such prevailing conditions, the hydrogeological appraisal of escalating groundwater exploitation has become of paramount importance. Keeping this in view, a surface water–groundwater quantity and quality model was developed to assess future groundwater trends in the Rechna Doab (RD), a sub-catchment of the Indus River Basin. Scenario analysis shows that if dry conditions persist, there will be an overall decline in groundwater levels of around 10 m for the whole of RD during the next 25 years. The lower parts of RD with limited surface water supplies will undergo the highest decline in groundwater levels (10 to 20 m), which will make groundwater pumping very expensive for farmers. There is a high risk of groundwater salinization due to vertical upconing and lateral movement of highly saline groundwater into the fresh shallow aquifers in the upper parts of RD. If groundwater pumping is allowed to increase at the current rate, there will be an overall decline in groundwater salinity for the lower and middle parts of RD because of enhanced river leakage.     

Restoring groundwater levels after tunneling: a numerical simulation approach to tunnel sealing decision-making

Tunneling is often unpopular with local residents and environmentalists, and can cause aquifer damage. Tunnel sealing is sometimes used to avoid groundwater leakage into the tunnel, thereby mitigating the damage. Due to the high cost of sealing operations, a detailed hydrogeological investigation should be conducted as part of the tunneling project to determine the impact of sealing, and groundwater modeling is an accurate method that can aid decision-making. Groundwater-level drawdown induced by the construction of the Headrace water-conveyance tunnel in Sri Lanka dried up 456 wells. Due to resulting socio-environmental problems, tunnel sealing was decided as a remedy solution. However, due to the expectation of significant delays and high costs of sealing, and because the water pressure in the tunnel may prevent groundwater seepage into the tunnel during operation, there was another (counter) decision that the tunnel could remain unsealed. This paper describes groundwater modeling carried out using MODFLOW to determine which option—sealed or unsealed tunnel—is more effective in groundwater level recovery. The Horizontal Flow Barrier and River packages of MODFLOW were used to simulate sealed and unsealed tunnels, respectively. The simulation results showed that only through tunnel sealing can the groundwater level be raised to preexisting levels after 18 years throughout the study area. If the tunnel remains unsealed, about 1 million m³/year of water conveyed by the tunnel will seep into the aquifer, reducing the operational capacity of the tunnel as a transport scheme. In conclusion, partial tunnel sealing in high-impact sections is recommended.

     

The geochemistry of beryllium and fluorine in the gem fields of Sri Lanka

A study of the abundance of Be in the gem sediments of Sri Lanka shows that Be is found in the range of 1–13 ppm. Be shows an irregular distribution among sediments. It occurs in the silicate form and due to the proximity to the beryllium bearing rocks, namely granites and pegmatites of the Highland and Southwest Groups of Sri Lanka, very little decomposition of the Be-bearing minerals had taken place. This is further aided by the high resistance to weathering of the beryllium minerals, particularly beryl and chrysoberyl.The beryllian granites and pegmatites of the Precambrian of Sri Lanka are presumed to have been formed due to the magmatic activity associated and related to charnockitic rocks abundant in the main gem bearing areas of Sri Lanka.Fluorine is found in the range of 400–2,000 ppm and the F/Be ratios for all the areas studied show a range of 54–441. The analysis of the averages of these ratios do not show any particular anomaly in any of the areas studied. The narrow ranges of the F/Be ratios indicate the similar conditions under which weathering and geochemical transportation had taken place in the gem fields of Sri Lanka.     

Evolution of coastal sandy aquifer system in Kalpitiya peninsula,Sri Lanka: sedimentological and geochemical approach

The study on the evolution of groundwater sources has arisen because of growing concern about deterioration of groundwater resources due to overexploitation. The chemical nature of a coastal aquifer depends on the initial composition of aquifer media, internal geochemical processes and external chemical inputs. Therefore, geochemical characteristics of an aquifer can be used as indicative components on elaborating the origin of aquifer media and its evolutionary processes. This study was aimed at understanding the evolution of Quaternary coastal aquifers of the Kalpitya area, Sri Lanka, by studying groundwater quality and aquifer media. The textural, mineralogical and chemical characteristics of aquifer media and chemical nature of groundwater of the area imply that the aquifer media may not have been derived from marine processes and paleo coastal formations of the western coast but are indicative of a fluvial origin due to past strong fluvial processes. Fluviatile sand depositions had taken place initially and with the gradual sea level rise, deposits were transported, sorted and then re-deposited to form barrier islands parallel to the coast. These have evolved to the present state during the Quaternary period. Intermittent climatic changes caused several changes in the depositional pattern of the aquifer material and the chemical nature of the aquifer. Present day groundwater geochemistry indicates an evolution of a fresh water aquifer with relics of ionic constituents showing paleo geochemical processes that were active during the evolution. In addition, anthropogenic activities have also significantly altered the geochemical nature of groundwater in the present aquifer system.     

Fluoride in Quaternary groundwater aquifer,Nile Valley,Luxor, Egypt

The occurrence of fluoride in ground water is the focus of the public and has attracted the attention of many scientists all over the world due to its importance in public health. Deficiency or increase of fluoride uptake is considered a public health problem due to the narrow permissible limit which should not exceed 1.5 mg/l according to the World Health Organization (WHO). The range of fluoride tolerance and toxicity is narrow. Deviation from the optimal levels therefore results in dental health effects such as caries and fluorosis. Many studies have found fluorosis to be invariably associated with high concentrations of fluoride in drinking water. Fluorosis is a considerable health problem in many areas of the world including Brazil, China, East Africa, Ghana, India, Kenya, Korea, Malawi, Mexico, Pakistan, South Africa, southeastern Korea, Spain, Sri Lanka, Sudan, Taiwan, Tanzania, and Turkey. Fluoride in groundwater of Quaternary aquifer of the Nile Valley, Egypt, does not gain the attention of the authors in the Nile Valley which makes the public health status of fluoride is not certain. The present work aims at investigating the fluoride concentration of Quaternary groundwater aquifer at Luxor as a representative area of the Nile Valley to be a base line for subsequent studies and criteria for public health. Ground water samples were collected from Quaternary groundwater aquifer at Luxor area, Egypt and analyzed for the purpose of investigating fluoride content. The results showed that fluoride concentration in the study area ranges between 0.113 and 0.452 with an average of 0.242 mg/l. Sources of fluoride in the study area can result from the natural dissolution from fluoride-rich minerals, fertilizers and from groundwater recharge. It is worth mentioning that low fluoride content in the study area is considered a public health threat specially limited growth, fertility, and dental caries. Corrective measures should be taken to avoid the public health impacts of fluoride deficiency at Luxor area as well as similar areas in the Nile Valley. A public health program should be initiated to account for the deficiency of fluoride in groundwater and deal with the other supplementary fluoride sources in food or fluoridation of drinking water supplies.     

Sri Lanka - India Intraplate Tectonics - Precambrian to Present

The tectonic history of Sri Lanka - India can be traced from the Precambrian to the present. On the basis of the geological record, plate tectonic processes have operated for example, the Highland Group of Sri Lanka may have represented a Precambrian plate tectonic suture. Tectonic models of these Precambrian events may be presented by spreading, collision, subduction, shearing or in situ jostling. The recent tectonic history of Sri Lanka and India relates to the evolution of the Indian Ocean since at least the Cretaceous. Although Sri Lanka is considered to be a part of the larger Indo - Australian plate, it may have had a local independent history as a block within the larger crustal unit of India. There is evidence that the separation of Sri Lanka from India was in part controlled by Precambrian structures and a history of translational, rotational and vertical adjustments to the Indian Ocean developmental plate tectonic stresses still operating.     

Management and environmental constraints to rice yield within a village irrigation system — A case study from Sri Lanka

Management and environmental constraints to rice yield in a paddy tract (lowland rice field) was studied within a village irrigation system in Sri Lanka. The relative importance of water coverage during the critical period and soil fertility variables on the yield variations were analysed. For the upper part of the paddy tract having adequate water supply, environmental and management factors seemed to explain the large variations in yield. For the middle and lower parts, with a shortage of water, water coverage was the only significant explanatory factor.For efficient use of a scarce water supply farmers allocated water first to the upper part, which resulted in water deficiency further down. An alternative strategy for water allocation, where the lower more fertile part of the paddy tract is favoured, would not avoid the risk of water scarcity for the individual farmer but there would be a potential for increase in the total production.     

Fahien reconsidered: Pleistocene exploitation of wild bananas and Holocene introduction of Musa cultivars to Sri Lanka

A recent publication on the phytolith assemblage at Fahien rockshelter, Sri Lanka (Premathilake and Hunt) is argued to represent: the exploitation of wild Musa acuminata and M. balbisiana during the Late Pleistocene; the introduction of edible diploid cultivars from the Southeast Asia–New Guinea region during the early to mid‐Holocene; the generation and cultivation of triploid banana hybrids on Sri Lanka before 6194–5994 cal bp ; and the subsequent spread of derived triploid cultivars to mainland India and westward to Africa. A careful review of the archaeobotanical research presented by Premathilake and Hunt, in the context of broader multidisciplinary evidence (agronomy, archaeobotany, genetics and linguistics) for the domestication and spread of banana cultivars, indicates that three main aspects of their argument are problematic: the lack of clarity in the characterization of banana domestication in the past; the methods used to discriminate phytoliths into banana taxa; and the promotion of Sri Lanka as a source region rather than a recipient of banana cultivars. Following reconsideration, the Fahien evidence is consistent with previous interpretations for the origins of diploid and significant triploid cultivars outside of Sri Lanka and dispersal to that island. © 2019 John Wiley & Sons, Ltd.     

Effects of road-deicing salt (NaCl) and saline water on water quality in the Urmia area,northwest of Iran

Increased application of road salt for winter maintenance has resulted in increased concentration of deicer constituents in the environment. The runoffs from the deicing operation have a deteriorating effect on water quality. The existence of salt super saturated Urmia lake and easy access to it, causes Urmia municipality to over use the super saturated water of this lake and salt (NaCl) during winter for snow melting, freezing prevention and traffic load facilitation. The aim of this study was investigation of surface and groundwater contaminations in consequence of salt (NaCl) and saline water usage in Urmia city and its surroundings. Studying the chloride ion concentration as a tracer in runoff result snowmelts during winter shows that its amount is differential with respect to time and place sampling. Results indicate that runoff result of snowmelts effected groundwater, soil and plant growth. The contamination of groundwater in study area by road salt and saline water is a slow process and directly related to the amount of road salt and saline water applied.     

Integrating Monte Carlo and hydrodynamic models for estimating extreme water levels by storm surge in Colombo,Sri Lanka

The prediction of high extremes in sustained water level is very important for coastal engineering design and planning. The recorded historical water level datasets in Colombo, Sri Lanka, are not long enough for the traditional frequency analysis in predicting extreme water levels, such as 50-, 100- and 200-year extreme water levels. In this study, the integrated ADCIRC + SWAN hydrodynamic model and Monte Carlo model have been applied to predict extreme water level in Colombo station of Sri Lanka. The meteorological driving forces of cyclone storm surge are simulated by Monte Carlo stochastic model. The calibrated ADCIRC model with SWAN wave model is used to simulate the potential surge setups with the driving forces generated by Monte Carlo model. By ranking the maximum high water levels in each storm surge procedure, the estimation on extreme high water levels for the desired return period is proposed in this study. The estimated extreme high water levels with return period of 50, 100 and 200 years are 1.28, 1.40 and 1.50 m correspondingly. The estimated extreme high water levels are recommended for engineering design and planning.     

地下水质量影响因素识别与定量评价——以广西桂林会仙湿地为例

近年来,在人类活动强烈的干扰下,湿地地下水环境日益恶化。传统的地下水质量评价方法因未区分天然高背景和人为污染的影响,评价结果不能全面、真实、可靠地表示出水质的实际状态。笔者等选取地下水主要超标指标进行因子分析,并根据各因子的得分和方差贡献率计算各采样点得分,并最终计算因子影响下的综合得分。综合评价结果表明,研究区地下水主要有3个影响因子,因子1主要为天然高背景引起的高铁(TFe),锰(Mn)和铝(Al),因子2为农业及生活污水影响导致的NH⁺₄、高锰酸钾指数(COD_Mn)和NO^-₂超标,因子3为天然与人为复合影响导致的I^-污染。计算得出的综合影响程度与传统的水质评价结果吻合,综合影响程度得分图不仅可以得出地下水质信息,还可根据确定的因子得出天然与人为对地下水质的影响。     

Locational specificities of fertility transition in Sri Lanka

Sri Lanka has one of the lowest fertility rates among poor countries of the world. The fertility decline which began in the 1950s has held steady during the last four decades, despite low levels of economic development. Widespread use of contraception is the primary cause of the fertility decline. However, there is no one single homogenous body of people that can be characterized as a ‘modern’ contracepting population through which new methods of family planning have spatially diffused. There is evidence that the overall fertility decline began even before the establishment of the modern family planning program in Sri Lanka. Our analysis showed four broad regional regimes of fertility transition with considerable social and place-to-place differences in method-specific rates of contraception among them. Non-modern ‘traditional techniques’ of contraception which are widely used are an important part of fertility regulation. Sterilization is the most common method of modern contraception in all regions. Less than a tenth of the protected couples use methods such as the pill and the IUD; moreover, these methods are often discontinued after initial use. Traditional methods are an important part of the contraceptive mix in Sri Lanka, and it would be inadvisable to discourage the use of such practices. This revised version was published online in August 2006 with corrections to the Cover Date.