Biogeochemistry of nitrate in headwater streams and atmospheric deposition of the Dandenong Ranges

Anthropogenic activities have increased input ofreactive nitrogen to terrestrial and aquatic ecosystems to such an extent that eutrophication, acidification and reduction of biodiversity are becoming widespread environmental problems. Much research has been devoted to understanding how nitrogen species move within the landscape, through which small streams have been identified as important components ofthe aquatic nitrogen cycle. Not only are small streams major entry points for nitrogen from the terrestrial environment, but they can also be sites of enhanced biogeochemical activity that mitigate export of nitrogen to downstream ecosystems. This thesis investigated sources and transformations of nitrate in headwater streams and atmospheric deposition of the Dandenong Ranges (ca. 40 km east of Melbourne, Victoria, Australia) using natural abundance stable isotope measurements (8^N-NOf).