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Field and petrographic investigations, cathodoluminescence (CL) studies as well as microprobe analyses of major rock-forming minerals were conducted to establish the crystallization processes in the Eppawala carbonatites, Sri Lanka. The well preserved magmatic textures and crystal morphologies combined with the chemistry of apatite, calcite and dolomite indicate two major stages of crystal growth, which were accompanied by dynamic crystallization conditions. Initially, nucleation of apatite, ilmenite and possibly olivine was associated with rapid crystal growth during slow cooling of the carbonatite melt at depth. The heat loss through the roof and crystallization processes induced the development of turbulent convective currents, which in turn prevented further nucleation and growth of crystals and led to the dispersion of these earlier formed crystals within the magma chamber. Then, rapid upward movement of magma along structural weaknesses led to (i) the transport of mineral clusters, (ii) deformation of ilmenite, (iii) fracturing of apatite and (iv) the emplacement of the carbonatite melt as dykes. Here, the conditions were favourable for the simultaneous crystallization of magnetite, calcite and dolomite in a non-turbulent environment. Subsequent subsolidus alteration caused the hydrothermal overprint of the documented mineral assemblages, particularly along grain boundaries. The study demonstrates that detailed textural examinations of carbonatites combined with mineral chemical analyses and CL investigations can reveal the crystallization processes within carbonatite melts.

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 HCO 3 -. 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.

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A significant number of written sources report on the development of ancient dry zone water harvesting and water management systems in Sri Lanka. This paper attempts to address the lack of a systematic assessment of the information given by sources on the spatial-temporal development of the system, using methods of source criticism. After the removal of double entries, 255 text passages containing 837 different records on ancient irrigation were compiled as a database for the period from the fifth century BCE to the tenth century CE. The majority of the 625 analyzed records were derived from inscriptions, 212 records originated from chronicles. Geocoding was successfully performed for 40 records. It was possible to link 173 text passages to a specific king's reign. Altogether 362 records (43.2%) mention a tank or its construction. The categories "grants of irrigation" and "irrigation incomes" are represented with 276 records (33%) and 75 records (9%). Records on canals and irrigation management occur with a share of 8.2% and 6.2%, equaling 69 and 52 records. The spatial distribution of records in general largely corresponds to the extent of the Dry Zone and northern intermediate zone. With 490 records, Anuradhapura district shows the highest density of information on the ancient water harvesting and management system. The analyzed data are not equally distributed throughout the investigated period and show a distinct peak in the second century CE. In conclusion, the conducted analysis documents the potential of the analyzed source genres for the derivation of information on different aspects related to the spatial, temporal and administrative development of the ancient water management system in Sri Lanka.

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