Hydrogeochemistry of the groundwater flow system in a crystalline terrain: a study from the Kurunegala district,Sri Lanka

Water samples collected from dug wells and tube wells from the Kurunegala District of Sri Lanka have been studied for their major hydrogeochemical parameters to understand the chemical quality of water in the terrain. The region is composed of Precambrian metamorphic rocks where groundwater is only available in the regolith and along weak structural discontinuities. The study of the major chemical constituents of groundwater revealed several relationships with the aquifer lithology. Groundwater from mafic rocks have high dissolved solids, while quartzose metaclastic rocks yield water with low dissolved solids. The study area displays very low SO₄ ²⁻ contents of the groundwater. The chloride content is higher in the dry regions and in terrains underlain by pink granite and marble/calc gneiss while areas with marble, as expected, show high concentrations of Ca and Mg ions. The waters in the region can be classified into non-dominant cations to Na + K dominant and Cl⁻ and HCO₃ ⁻ dominant types. Water from charnockite-bearing areas tends to have non-dominant cations and more CO₃ ²⁻ + HCO₃ ⁻ types. Effects such as soluble salts in the regolith, fracture intensity and climatic variations play a significant role in the behavior of the hydrogeochemistry in the area.     

Application of Rb-Sr ratios to gem exploration in the granulite belt of Sri Lanka

The geochemical distribution of rubidium and strontium in the central granulite belt of Sri Lanka, where many of the gem deposits are found, was studied. The Rb-Sr ratios, particularly in the stream sediments, were found to be useful in delineating gem-bearing areas from the non gem-bearing or low potential areas. Among the main gem minerals that are mined at present are corundum, spinel, zircon and tourmaline. It was observed that higher Rb-Sr ratios correspond to high gem potential and, even within areas of good potential, barren areas could be delineated using these ratios. During pegmatite formation, Rb is enriched, and there is a marked depletion of Sr yielding a high Rb-Sr ratio. Pegmatites, granites and other magmatic bodies are associated with gem formation under granulite facies conditions and, when used in conjunction with geology, structure, and mineralogy, the Rb-Sr ratio could be used effectively to delineate target areas for further exploration.     

Evaluation of fixed wavelength fluorescence and synchronous fluorescence spectrophotometry as a biomonitoring tool of environmental contamination

A field study was carried out to investigate whether polyaromatic hydrocarbon (PAH) contamination in shore crabs (Carcinus maenas) could be measured using fluorescence spectrometry. Crabs were collected as part of an integrated study to assess PAH contamination in Southampton Water, UK. Urine was collected from crabs via a non-destructive technique and analysed using fixed wavelength fluorescence (FF) and synchronous fluorescence spectrophotometry (SFS) in order to determine the presence of PAH metabolites, indicative of PAH exposure. By scanning at wavelength pairs specific to a variety of PAH groups the fluorescence of metabolites was analysed and attributed to the following PAH groups; naphthalenes, pyrenes and benzo[a]pyrene (BAP). Naphthalene-type, pyrene-type and BAP-type metabolites were detected using FF and SFS techniques and two distinct parameters were measured; Peak Intensity and Peak Area. Results showed that crabs obtained near a petroleum refinery, a point source of PAH discharge, exhibited significantly higher PAH metabolites for all PAH groups, than at sites sampled along the estuary (ANOVA, p<0.05). This study highlights the effectiveness of using FF and SFS as a rapid and cost-effective biomonitoring tool for detecting PAH contamination.     

Ecosystem management bioindicators: the ECOMAN project--a multi-biomarker approach to ecosystem management

The ECOMAN project was initiated from an awareness of the complexity of the functioning of coastal marine systems and the clear need for more pragmatic environmental assessment techniques linking environmental degradation with its causes. The aim of the project is to develop a suite of easy to use, cost effective and environmentally valid biological responses (biomarkers) to assess the general health of coastal systems, including estuaries. To achieve this aim, various sublethal endpoints are being measured and evaluated from a range of common coastal organisms showing different feeding types (filter feeding, grazing and predation) and habitat requirements (estuary and rocky shore) and at different levels of biological response (cellular, physiological and behavioural). This holistic integrated approach is essential to identify the full impact of chemical contamination on organisms, and enables the sensitivity of organisms to be ranked and key sentinel species for specific habitats to be identified.     

Ecosystem management bioindicators: the ECOMAN project – a multi-biomarker approach to ecosystem management

The ECOMAN project was initiated from an awareness of the complexity of the functioning of coastal marine systems and the clear need for more pragmatic environmental assessment techniques linking environmental degradation with its causes. The aim of the project is to develop a suite of easy to use, cost effective and environmentally valid biological responses (biomarkers) to assess the general health of coastal systems, including estuaries. To achieve this aim, various sublethal endpoints are being measured and evaluated from a range of common coastal organisms showing different feeding types (filter feeding, grazing and predation) and habitat requirements (estuary and rocky shore) and at different levels of biological response (cellular, physiological and behavioural). This holistic integrated approach is essential to identify the full impact of chemical contamination on organisms, and enables the sensitivity of organisms to be ranked and key sentinel species for specific habitats to be identified.     

Esterase activities in the bivalve mollusc Adamussium colbecki as a biomarker for pollution monitoring in the Antarctic marine environment

Marine environments are continuously being threatened by a large number of xenobiotics from anthropogenic sources. Even in sparsely populated and relatively pristine areas, such as Antarctica, hazardous chemicals can pose a serious environmental problem. The main aims of the present study were to (1) validate and optimize an analytical technique utilizing a microtitre-plate photometer to ascertain background levels of esterase activities in the Antarctic bivalve Adamussium colbecki, (2) carry out in situ monitoring of esterase activities to assess any potential environmental impacts of the Italian Scientific Antarctic Base "Terra Nova Bay" on the surrounding marine area. Results showed the presence of organophosphorous-sensitive cholinesterase (ChE) and carboxylesterase (CbE) activities in the gills of A. colbecki and optimal assay conditions were comparable with those found for bivalve species from temperate areas. A higher sensitivity of ChE versus acetylthiocholine activity in A. colbecki to chlorpyrifos compared to species from temperate areas may also be inferred. The in situ study indicated no differences in the environmental quality of the three study sites located around the Italian Base.     

Spatial variation of isotope composition in precipitation in a tropical environment: a case study from the Deduru Oya river basin,Sri Lanka

The stable isotope composition (¹⁸O and ²H) in the tropical precipitation collected from 18 locations throughout the Deduru Oya river basin in Sri Lanka, has been studied during August and September 2001, in order to characterize the isotopic composition of precipitation in the dry and intermediate climatic zones of Sri Lanka. The isotope compositions are described with respect to the distance from the coast and the altitude. The analyses show that δ¹⁸O vary from ? 5·11 to 1·39‰ and δD vary from ? 35·71 to 12·55‰. The d‐excess values range from ? 0·65 to 13·17 with an average value of ～7. Regression for the δ¹⁸O ? δD is y = 6·8x + 4·9 (R² = 0·9) which is compatible with the precipitation in other tropical regions. The lower slope in the regression line and the lower d‐excess value indicate high temperature events which were possibly aided by concentration through successive evaporation within the atmosphere. The spatial variation of isotope composition indicates two different cloud contributions for the rain events, of which one may be linked to the Indian Ocean contribution and the other to the high altitude condensation. Copyright © 2008 John Wiley & Sons, Ltd.     

Seasonal differences in the physiology of Carcinus maenas (Crustacea: Decapoda) from estuaries with varying levels of anthropogenic contamination

This study reports the seasonal variability in aspects of the physiology of the shore crab Carcinus maenas from three estuaries in South-west England, each with varying anthropogenic inputs: Avon Estuary (‘relatively low’ impact), Yealm Estuary (‘intermediate’ impact) and Plym Estuary (‘relatively high’ impact). Crabs collected over 12 months from the Avon had a significantly ‘lower’ physiological condition in winter and spring compared to summer and autumn; in particular, haemocyte phagocytic capability (a general indicator of immune function) was significantly higher in winter and spring compared to summer and autumn, and total haemolymph antioxidant status (an indicator of oxidative stress) was significantly lower in winter compared to the remainder of the year. Potentially, shore crabs may be more susceptible to the effects of contaminant exposure, such as increased immunotoxicity (thus, reduction of immune function) and/or oxyradicals (or reactive oxygen species) exposure) especially in seasons of increased susceptibility i.e. summer/autumn (lower phagocytic capability) and winter (lowest antioxidant function). As the Avon was taken to represent the ‘reference’ site, this pattern is considered to reflect the ‘normal’ seasonal variability in shore crab physiology. Shore crab physiological condition from the ‘relatively high’ impact estuary (Plym) revealed increased cellular viability and antioxidant status in autumn and winter compared with that of the ‘standard’ pattern (Avon) However, crabs from the intermediate impact estuary (Yealm) only demonstrated significant physiological differences in summer as shown by a lower cellular viability. All crabs had been exposed to PAHs (confirmed by the presence of PAH metabolites in their urine) which may account for the observed differences in shore crab physiology. In conclusion, to aid understanding of the potential contaminant impacts on biota it is imperative that the ’normal’ seasonal variability of physiological condition be established. Biological effects-based monitoring studies should therefore be employed seasonally to potentially highlight ‘windows of sensitivity’ to contaminant impact.