Rain water chemistry at Calypsobyen, Svalbard

Abstract

Measurements of pollutants scavenged from air masses over southern Svalbard in summer precipitation are presented. Rainfall was sampled in July and August 2002 at Calypsobyen, Bellsund. Specific conductivity (SpC) and pH were measured and ion con− centrations were determined by ion chromatography. Ions of marine origin were subtracted, assuming that all chlorides were of marine origin. The FLEXTRA trajectory model was ap− plied to discover the sources of air masses arriving at Svalbard and track the paths of pollut− ant transport. Average (v/w) rainfall pH was 4.94, mean SpC amounted to 34.8 μS cm−1. To− tal dissolved solids concentration (TDS) ranged from 12.6 to 67 mg L−1, with ions of marine origin (Cl−, Na+, Mg2+) prevailing. Rains with the highest percentage of marine salts oc− curred with winds from the East at above average velocities. Non−sea salt (nss) sulphate concentrations ranged from 0.5 μeq L−1 to 23 μeq L−1, (v/w) average was 17 μeq L−1. Nitrate concentrations ranged from 0 to 24 μeq L−1. The highest concentrations of nss−SO4 2− and NO3 − were measured on 25 August, when the highest rainfall occurred (27 mm) and pH was the lowest (4.65). Rainfall at Calypsobyen deposited 194 kg km−2 of acidifying anions and 263 kg km−2 of base cations over the recording period. The polluted air masses were mostly from northern and central Europe. Rainfalls scavenging air masses formed over Greenland and Norwegian Seas displayed similar concentrations, being probably polluted by SOx and NOx from ship emissions.