Areal distribution of sulphur and oxygen isotopes in sulphate of rain over eastern North America

Three summer rainfall events were sampled simultaneously across a network of 24 stations extending from the Mississippi River to the Atlantic seaboard and from the Gulf of Mexico to subarctic Canada. The chemical and isotopic compositions of the rain and its dissolved sulphate were measured on each sample. Each event was characterized by a different air mass back trajectory, suggesting a different source region for the transported sulphate. Two …