9316133 Mackenzie The main goals of the proposed research are to evaluate responses of the coupled carbon, nitrogen, phosphorus and sulfur biogeochemical cycles to climate and global change in the land- coastal margin system on decadal to millennial time scales, and the contribution of this system to global environmental change. This system will be in the future one of the world's most disturbed because of human activities. Because of the great complexity of the land-coastal margin system, it is necessary that observational programs for individual ecosystems be complemented by data synthesis and modeling of behavior of the system on a global scale. Herein we propose a research program to "aid" in the accomplishment of this task. Carbon, nitrogen, phosphorus and sulfur are the four main building blocks (excluding oxygen and hydrogen) of organic matter, and they are incorporated within certain proportions, known as the Redfield ratios, by marine plankton and terrestrial vegetation. Thus, study of these elemental components of the Earth-surface system is important in the context of global change and biotic responses to change.
