Understanding Particulate and Dissolved Material in the Penobscot River System: Abstract

Coastal regions are physically, biogeochemically, and therefore optically complex resulting from influences related to the coastal boundaries, and the commingling of terrestrial and freshwater ecosystems with marine ecosystems. Particulate and dissolved materials originating from the terrestrial environment are transported to river systems via run off. These materials vary in composition as a function of landscape cover and land use. Temporal variations in the delivery of these materials are associated either with variations in runoff or constituent concentrations, the latter of which is dependent upon the upstream activities. These inputs alter not only the biogeochemistry of the river water by mixing and reacting with natural particulate and dissolved materials, but also alter the optical characteristics of the riverine water entering the coastal margins, thereby increasing the optical complexity of the coastal waters, both spatially and temporally and often in a nonlinear manner. The interaction of terrestrial, riverine and coastal processes have major implications that complicate coastal water investigations, but also may lead to new insights regarding terrestrial processes, and the impacts to coastal ecosystems. The particulate and dissolved matter that flows into the coastal waters via rivers may contain biogeochemical information about upstream land use activities if it has observable, identifiable, unique, and conserved properties over appropriate time and space scales for observations.

The goal of this project is to identify regions of defined land use activities within a watershed, investigate the chemical and optical properties of the particulate and dissolved compounds that arise from each activity, identify whether those properties/compounds are unique to an activity, and thereby define observable proxies for that activity, and finally quantify the time and space scales over which the proxies can be identified. The focus of this investigation is the region encompassing the Penobscot River Watershed, Penobscot Bay and the surrounding coastal waters. The Penobscot River Watershed is relatively unimpacted by human activities. Those activities tend to be very regional and isolated which minimizes uncertainties that might arise in more developed regions where more than one land use activity might impact a tributary or stretch of river. There are distinct regions within the Penobscot watershed, with associated tributaries, that can be characterized uniformly as pristine woodlands with and without bogs or wetlands, harvested timber areas, pulp mills, plant agriculture, dairy agriculture, or as a populated urban area.

Read more about this study... June 2005 presentation