Studies of environmental conditions have become more and more important for oUf knowledge about the complex processes resulting from natural and man-made influences on OUf environment. During recent years new analytical techniques have been developed that are mainly based on laser spectroscopy. They are not only more sensitive and reach lower detection limits but they also give more de tailed information on the species under investigation and their interactions with the environment. They therefore can considerably deepen OUf understanding of correlations between different processes and their...