Hydrochemical distribution patterns in stream waters, Trondelag, central Norway

A regional geochemical sampling program of stream waters has been carried o ut in the Nord-Trondelag region of central Norway. This area has hitherto b een little affected by regional anthropogenic sources of pollution. Hydroch emical trends appear to be dominated by interplay of two main factors: (i) input of sea salts via marine aerosols in precipitation: and (ii) geologica l sources (mineral weathering). Factor (i) results in a predominance of Na- Cl waters near the coast, and may also be partially responsible (via proton displacement from soil ion-exchange sites by marine cations) for lower pH values in near-coastal waters. Further inland, the importance of marine sal ts decreases and waters become dominantly Ca-(Na)-HCO3 Sub-regional anomali es in geochemical maps for, e.g. nitrate and copper may indicate anthropoge nic sources for these parameters from agriculture or mining activities. (C) 2001 Elsevier Science B.V. All rights reserved.