Heavy metals and trace elements analysis in groundwater around Mahaoya hot water springs

Groundwater in and around Mahaoya thermal springs found in the Precambrian highgrade metamorphic terrain of Sri Lanka were investigated to assess their geochemical properties with compared to normal regional groundwater of particular area and to produce a data set to develop a model of identification of thermal springs or mixing of thermal and non-thermal ground water. The main objective is this study is to compare the geochemical parameters of thermal springs with nearby cold ground water and interprets the geochemical relationships among them.Samples of low temperature (<35 °C) groundwater from nearby springs, piezometers and open wells were also collected for comparison. All samples were analyzed for their major and trace element compositions using Atomic Absorption Spectrophotometer and standard methods.These waters showed low concentrations of selected trace elements and were comparable to that of geothermal groundwater. Major cation and anion concentrations of thermal springs are similar to nearby cold springs. Close matches of geochemical data from geothermal and dug wells waters confirm the hypothesis of a common source

An overview of heavy metal contamination in coastal sediments of Sri Lanka

Coastal sediments are often subjected to heavy metal contamination as they reside at the marginal environments of anthropological water releases. These sediments provide the habitat for marine aquatic life of seafood. Therefore, heavy metal contamination in coastal sediments is one of the major environmental concerns. The coastal belt of Sri Lanka is highly urbanized with high population (59% of Sri Lankan population) and is mostly depend on the sea. Therefore, anthropogenic inputs of pollutants in to the marine environments have been increased during last decades.  Heavy metal contamination of the coastal sediments of Sri Lanka has been discussed by several studies, focusing on selected coastal regions. In this article, previous studies have been reviewed in order to understand the contamination status and ecological risks due to heavy metal accumulations. Despite the sampling location, the elemental distribution of coastal lagoonal sediments shows similar trend indicating the dominance of natural elemental sources rather the anthropogenic influences. The concentrations of As and Cr in sediments are high compared to the upper continental crust values which is a characteristic feature in possible source rocks, soils and sediments of Sri Lanka. The results of the previous studies indicate that coastal sediments are low to moderately contaminated but not at ecological risk. However, anthropogenic activities are highly variable across the coastal regions. Since limited results of the previous studies is not enough to get an overview of the heavy metal concentrations around the island, urgent need for a spatial and temporal geochemical database for coastal sediments of Sri Lanka is emphasized.Keywords: Contamination, coastal, metals and sediment

Sedimentary signatures on the eastern coast of Sri Lanka: preliminary findings

Undisturbed sediment compiles are invaluable samples in the reconstruction of ancient depositional environments. Basically coastal sedimentation is significant as it preserves the eustatic and isostatic records as well as seasonal climate records. Present study concerns on sedimentology of recent sediments of a part of the eastern coastal lagoon area of Sri Lanka to interpret the depositional history. Spatial extent of sediments was studied by field mapping. Gradation analysis and morphology of sediments were used to identify the depositional history of sediments. The results revealed that the spatial extent of the recent sediment deposition is about 4km wide band from the present coast line including the lagoon environment that overlaid the weathered residual soil. Top sediments (up to 1m) are characterized by different layers with several depositional histories and did not indicate any remarkable clayey layer even though the locations are near to a river input and within the flood level. It can be said the inorganic input is prominent than the organic input in the eastern coastal sedimentation. The results need to be proved by other geochemical and age dating proxies

Qualitative mineralogical analysis of Barracuda exploration well in the offshore Mannar Basin (the Indian Ocean) using FTIR and XRD techniques

The Mannar Basin plays a vital role in petroleum exploration in Sri Lanka, and its Barracuda exploration well was drilled up to 4206 m in depth. The objective of the current study is to identify mineralogy using Fourier-transform infrared (FTIR) and X-ray diffraction (XRD) analyses. The FTIR and XRD analyses confirm the presence of quartz, feldspar, clay minerals (e.g., kaolinite, montmorillonite), calcite, and hematite in all marlstone and mudstone samples. These sedimentary rocks can be identified as potential petroleum source rocks in the Mannar Basin. Quartz, carbonate, and hematite cementations are directly reduced porosity and permeability, and thus primary migration of hydrocarbons from potential source rocks. Clay minerals act as a seal for hydrocarbon migrations in the Mannar Basin. A variety of dominant clay mineral assemblages allows the reconstruction of several paleoclimatic chronozones in warm/wet and arid climates. In contrast, feldspar dissolution promotes the primary migration of hydrocarbon from potential petroleum source rocks. Consequently, this study concluded that common minerals such as quartz, carbonate, and hematite are associated with the trapping and binding processes of hydrocarbons