GEOCHEMISTRY OF GROUNDWATER IN A REGION AFFECTED BY BALKAN ENDEMIC NEPHROPATHY

Balkan Endemic Nephropathy (BEN) is a chronic tubulointerstitial nephritis whose distribution throughout the Balkans has not changed significantly since initial description. The environmental hypothesis suggests that the spatial distribution of BEN is related to the biogeochemistry of the environment (e.g., soils, water and food). Little is known about the hydrogeochemistry of groundwater from such regions. Therefore, samples of well, tap, and spring waters were collected from BEN and non-BEN areas in Bulgaria (Vratza region). Samples were analyzed for major, minor, and trace solutes. Clean techniques were used. Graphical (e.g., x-y plots, Piper), geochemical (PHREEQC) and statistical (common, multivariate) techniques were used. Selected results indicate that: 1) regional water is Ca-HCO3, 2) most dissolved chemical concentrations in both area are not enriched above “background” concentrations; 3) molybdenum and arsenic concentrations are typically higher in BEN than non-BEN samples; 4) uranium concentrations are elevated in well and spring water (above WHO suggested limits) perhaps by complexation (UO2(HPO4)2-2), but are not elevated in soils; 5) nitrate levels are highest in wells (above WHO limits) and lowest from taps (a few above WHO limits); 6) nitrate is higher in BEN springs than non-BEN springs; 7) Cl:Na ratios reflect halite as a source. These results are interpreted to indicate differences between BEN and non-BEN environments; human influences on water quality that might play a role in health, and potential flow and transport differences between BEN and non-BEN environments. It should be noted that the differences between BEN and non-BEN areas can not necessarily be interpreted to be the cause of the distribution of BEN at this time.