D. T. Jayawardana

Groundwater Quality in Different Climatic Zones of Sri Lanka: Focus on the Occurrence of Fluoride

The chemical and physical parameters of groundwater in some areas of dry and wet zones of Sri Lanka are described. Hydrochemical data from 114 water samples are used to evaluate water quality and to identify the processes that control fluoride levels in water. The results indicate that fluoride levels of groundwater in the dry zone are very high (< 8.0 mg/L) compared to those of the wet zone (< 0.8 mg/L). The measured nutrients (NO3- < 15 mg/L, PO43− < 5 mg/L) concentrations and chemical oxygen demand (< 18 mg/L) in both regions inferred that higher fluoride levels reported in the groundwater are not from anthropogenic sources. The pH-Eh stability diagrams show that nitrate, phosphate and iron does not co-exist with fluoride under prevailing redox condition. Physical parameters further show that fluoride values increase in slightly alkaline in pH (7.5-8.2), relatively low EC (1.0-2.5 mS/m) and highly oxidized water (50-200 mV). Groundwater movements of shallow regolith aquifers in the country are mainly controlled on joint and fault system in the partially weathered basement. This study observed that their variation in the dry and wet zones is a major parameter for the control fluoride levels in water. Thus less fractured rocks in the dry zone water discharge areas show higher values and may be due to lesser mixing of water with non-fluoride sources. Conversely, highly fractured rocks are predominant in the wet zone and hence mixing of fluoride poor and rich waters in both recharge and discharge regions in the zone results in low fluoride levels. 2

Effective use of iron-aluminum rich laterite based soil mixture for treatment of landfill leachate

Landfill leachate poses environmental threats worldwide and causes severe issues on adjacent water bodies and soil by direct discharge. The primary objective of this study is to analyze the efficient use of compost and laterite mixtures (0, 10, 20, 30 and 40 wt% compost/laterite) on leachate treatment and to investigate the associated removal efficiencies under different sorption processes. Therefore, in the experimental design, laterite is used for providing adsorption characteristics, and compost for activating biological properties of the filter. The filtering process is continued until major physical changes occur in the filter at approximately 100 days. The raw leachate used for the experiment shows higher average values for many analyzed parameters. Parameters for the experiment are selected based on their availability in raw leachate in the Sri Lanka. During filtering, removal efficiencies of BOD (>90%), COD (>85%), phosphate (>90%) and nitrate (75-95%) show higher values for all filters. These removals are mainly associated with biodegradation, which is activated by the added compost. Perhaps the removal of nitrate steadily increases with time, which indicates in denitrification by the added excess carbon from the leachate. The removal of total suspended solids (TSS) is moderate to high, but conversely, the electric conductivity (EC) is unsteady, indicating an association between iron exchange and carbonate degradation. A very high removal efficiency is reported in Fe (90-100%), and wide ranges of efficiencies in Mn (30-90%), Cu (45-85%), Ni (30-93%), Cd (37-98%), Zn (15-98%), and Pb (35-98%) involve heterogeneous sorption processes. Furthermore, the normalization of raw leachate by the liquid filtrate has apparent improvements. The differences (p > .05) in removal efficiencies between the filters are significant. It can be concluded that the filter with laterite mixed with 20% of compost has the optimum conditions. Further, the Fourier-transforminfrared (FT-IR) models for filter media conclude multiple sorptions and reveal evidence on vacant sites. X-ray diffraction (XRD) analyses indicate secondary minerals gibbsite, hematite, goethite and kaolinite as the major minerals that involved on the sorption process.

Direct impacts of landslides on socio-economic systems: a case study from Aranayake, Sri Lanka

BackgroundLandslides area controversial issue worldwide and cause a wide range of impacts on the socio-economic systems of the affected community. However, empirical studies of affected environments remain inadequate for prediction and decision making. This study aims to estimate the direct impact of a massive landslide that occurred around areas with Kandyan home gardens (KHGs)in Aranayake, Sri Lanka.ResultsPrimary data were gathered by structured questionnaire from residents of the directly affected regions; the questionnaire data were combined with spatial data to acquire detailed information about the livelihoods and hazards at the household level. Satellite images were used to find affected land use and households prior to the landslide. Further, secondary data were obtained to assess the recovery cost. A multiple regression model was established to estimate the economic value of the home gardens. Field surveys and satellite images revealed that land-use practices during the past decades have caused environmental imbalance and have led to slope instability.ConclusionsThe results reveal that 52% of household income is generated by the KHG and that the income level highly depends on the extent of the land (R2 = 0.85, p < 0.05). The extent of destroyed land that was obtained from the satellite images and the age of the KHG were used to develop a multiple regression model to estimate the economic loss of the KHG. It was found that the landslide affected region had been generating approximately US

I-P2O5 diagrams as an indicator of depositional environment in marine sediments: preliminary findings (Sri Lanka)

160,000 annually from their home gardens toward the GDP of the country. This study found that almost all houses in the area were at risk of further sliding, and all of them were partially or entirely affected by the landslide. Among the affected households, 60% (40 houses) had completelycollapsed, whereas 40% (27 houses) were partially damaged. Because of these circumstances, the government must provide US

Fourier Transform Infrared (FTIR) Spectroscopic Analysis of Soil Organic Matter in an Alluvial Type Gem Deposit in Pelmadulla, Sri Lanka

40,369 to recover the fully and partially damaged households. Finally, a lack of awareness and unplanned garden cultivation were the main contributing factors that increased the severity of the damage.

Geochemical evidence for the accumulation of vanadium in soils of chronic kidney disease areas in Sri Lanka

The concentrations of Br and I in marine sediments have been used to categorize the sedimentary environments of different coastal regions of the world with respect to organic matter contents. The present study uses the concentrations of Br, I and P2O5 of different marine settings as a new proxy to interpret the depositional environments. A total of 150 coastal lagoon sediment samples (suspended sediments, surface sediments and sediment cores) were analyzed for Br, I and P2O5 concentrations by X-ray fluorescence spectrometry. They were compared with the Br, I and P2O5 concentrations of the 2004 Indian Ocean tsunami sediments. Sediments from various sources are separately clustered in I–Br plot and a trivial negative correlation is found for the whole plot. A similar correlation pattern exists in the I–P2O5 diagram. This correlation is explained by the distribution of marine plants (higher and lower) in different sedimentary environments of the coastal profile. Therefore, the concentration of I and its relation to P2O5 can be used as a tool to identify sediment depositional environments in marine settings.

Assessment of soil geochemistry around some selected agricultural sites of Sri Lanka

Organic matter is one of the most important and fundamental constituent in soil, which usually present in transported sediments. Therefore a wide spectrum of physically and chemically different organic matter can be expected in alluvial type sedimentary gem deposits. Composition of soil organic matter is very important, because it is tightly link with environmental issues such as mine gas poisoning, carbon budget and bioavailability of toxic elements in the soils. This study was conducted to identify the composition, distribution and impacts of the soil organic matter in the sedimentary profile of an alluvial gem deposit in Pelmadulla, Sri Lanka. Seventy seven soil samples were collected along the sedimentary profile in three different locations using auger drilling method. Chemical bonding structure of the each soil sample was analyzed in the mid IR region of FTIR spectroscopy. Total organic matter (TOM) and the total organic carbon (TOC) contents of the of each soil sample were measured using loss on ignition and the Walkley-Black wet oxidation methods respectively. In addition, selected basic physical and chemical parameters of the soil such as pH, oxidation-reduction potential, moisture content, and elution conductivity were also tested. Results indicate pH is in slightly acidic in nature and soil elution conductivity is higher in the peat layer of the bottom alluvial deposit. FTIR spectroscopic analysis proved the presence of several organic functional groups/bonds such as saturated aliphatic (2950-2970 cm-1, 2860-2880 cm-1), unsaturated aliphatic (2915-2935 cm-1, 2845-2865 cm-1), alcoholic (3200-3645 cm-1), carbonyl (1680-1820 cm-1), aryl (1450-1615 cm-1), disulfides (570-705 cm-1) and ether (2815-2850 cm-1). Some of those functional groups such as carbonyl and disulfide in organic matter may cause for the poisonous gas emissions. The ratio of TOC/TOM is slightly higher in the top and the bottom of the alluvial deposit. This indicates the high-carbon organic matters are present in the top and the bottom most layers. Conversely, carbon content of the middle layers in the deposit is less due to the intermediate level of organic matter degradation. In addition, middle region of the alluvial deposit is consisting of sandy nature, which reflects the dry climatic formation in the past thus the organic matter content is low. High soil elution conductivity in the bottom of the deposit indicates that the soluble ions were leached to the bottom and accumulate in the peat layer. Keywords: FTIR spectroscopy, Soil organic matter, Alluvial gem deposits, Geochemistry