OBJECTIVES:
(1) Determine sediment and contaminant (PAH, trace metal) "hot spots",
deposition zones, accumulation rates, and near surface residence times
in the Elizabeth River. (2) Determine the direction and magnitude of net
transport of particles and associated contaminants in the Elizabeth River,
as a function of particle properties and hydroynamic forcings.
METHODOLOGY:
We will conduct a geophysical survey and collect sediment grab samples
to identify prospective coring locations and contaminant "hot spots", and
a more extensive geochronological study to determine sediment and contaminant
accumulation rates. We will also conduct intensive field experiments during
spring and neap tidal cycles in both dry and wet seasons to evaluate particle
and associated contaminant resuspension and transport in the vicinity of
a previously identified "hot spot". Sediment cores and suspended
particle samples will be analyzed for particle properties such as organic
carbon and nitrogen content, as well as various PAHs and trace elements,
including those on the Chesapeake Bay Toxics of Concern list. Finally,
we will couple the sediment accumulation and particle transport mechanisms
to provide an understanding of short and long term sediment and associated
contaminant transport and deposition in the Elizabeth River.
RATIONALE:
Many contaminants in aquatic systems tend to associate with fine grained
sediments, thus the transport and fate of these particle-associated pollutants
are dictated by the processes mediating sediment transport within an aquatic
system. In highly channelized tidal environments such as the Elizabeth
River, fine sediment and associated pollutant transport and fate will be
governed predominantly by physical processes. Consequently, to understand
and model the processes controlling contaminant transport from Elizabeth
River sediments to the water column, and from historically contaminated
areas to lesser or nonpolluted sites, we must quantitatively evaluate particle
and associated contaminant resuspension and deposition in the estuary along
with likely mechanisms for physical transport.