Modeling is inherent in every aspect of the project, both as a tool for understanding at discrete spatial and temporal scales, and as a method for integrating mass-balance calculations over time and space. This science plan is intended to serve as a rationale and guide for project participants and as a source of information about the project for managers and potential collaborators. The activities described in this plan will be carried to a level of detail that depends on funding, the project lifetime, and the development of arrangements for collaboration and review by non-USGS scientists. Essential goals of the project are testing the two central hypotheses, estimating whole-basin carbon budgets, and linking these estimates to the global CO 2 budget. Studies of carbon, sediment, and nutrient budgets in the Mississippi Basin will also provide valuable information relevant to many other problems associated with human land use.
Agricultural productivity is threatened by increasing erosion and declining fertility of soils.
Erosion and sedimentation are primary concerns in the management of water supplies and quality. Natural organic compounds play a critical role in the transport and storage of contaminants in waters and sediments. Carbon compounds account for most of the oxygen depletion associated with anoxia and eutrophication in lakes, streams, and coastal waters. An improved understanding of interactions between changes in the land surface and changes in the carbon cycle is essential to predicting and coping with global environmental change.