LaTTE
-- LaGrangian Transport and Transformation Experiment
COLLABORTIVE RESEARCH: Lagrangian studies of the transport, transformation,
and biological impact of nutrients and contaminant metals in a buoyant
plume: A process study in an operational ocean observatory.
Robert Chant-1, John
Reinfelder-1, Scott
Glenn-1, Oscar
Schofield-1, John
Wilkin-1, Robert
Houghton-2, Bob
Chen-3, Meng
Zhou-3, Paul
Bissett-4, Mark
Moline-5, Tom
Frazer-6
1-Rutgers, 2-Lamont-Doherty, 3-U. Mass Boston, 4-FERI, 5-Calpoly,
6-U. Fla. Gainsville
We propose a coordinated program of field and numerical experiments
to examine processes that control the fate and transport of nutrients
and chemical contaminants in the Hudson River plume, a plume that
emanates from one of the nation’s most urban estuaries --
the New York/New Jersey Harbor complex. Urban estuarine plumes represent
a major pathway for the transport of nutrients and chemical contaminants
to the coastal ocean. However, the fate and transport of this material
is controlled not only by the plumes dynamics but also by biological
and chemical processes that are coupled to the dynamics of the plume.
By conducting a series of dye experiments featuring continuous underway
chemical and biological sampling with a state-of-the-art towed vehicle
within the well sampled framework of an operational ocean observatory,
we will be able to distinguish between physical processes that transport/mix
material in a buoyant plume from biological and chemical transformation
processes. This will allow us to quantify biological and chemical
interactions in a Lagrangian perspective, and provide a means to
assess their importance in determining the fate and transport of
nutrients and chemical contaminants in a buoyant plume.
This program will contrast the response of physical, biological,
and chemical processes in the Hudson plume during upwelling and
downwelling conditions. We hypothesize that cross-shelf transport
of material is determined not only by Ekman transport and diapycnal
mixing, but also by biological and chemical processes all of which
differ between upwelling and downwelling conditions. For example,
a vertically thin plume during upwelling conditions will have enhanced
light levels, thus promoting biological production and potentially
increasing the rate that chemical contaminants enter the food chain.
In particular, we will quantifiably relate (a) biological production
rates, (b) the bioavailability and bio-accumulation of metals, and
(c) chromophoric dissolved organic matter (CDOM) photobleaching
rates within the plume to the physical characteristics of the plume,
such as plume thickness, optical depth, and mixing rates.
An ocean observatory will facilitate interpretation of the dye study
by placing the Lagrangian surveys in context with shelf-wide observations
from satellite imagery, surface currents and far-field subsurface
hydrography. The observatory will be augmented by a cross shelf
array of moored instruments to provide detailed estimates of subtidal
circulation, stratification and Reynold stresses. Finally, data-assimilative
numerical simulations will provide high resolution and realistic
hindcasts of the coastal ocean during the field experiments. Modeling
will pioneer the assimilation of dye-tracer data into a 3-D coastal
circulation model and guide future efforts to assimilate other tracers
into circulation models with complex sources and sinks. Coupled
physical/biological model hindcasts will be used to interpolate
observations in space and time for interpretation, and to test turbulent
and biological parameterizations.
Our study will determine the geographic extent and biological impact
of contaminants in the plume along the New Jersey coast and Middle
Atlantic Bight. Results will improve our ability to predict the
fate and transport of contaminants and the rate that they enter
the base of the food chain in the coastal ocean. Quantifying contaminant
uptake into the base of the coastal ocean food chain is the first
step in predicting contaminant bioaccumulation at higher tropic
levels. Finally, episodic nutrient inputs from the plume have been
linked to coastal phytoplankton blooms and may drive recurrent low
dissolved oxygen levels in this region. Results from this study
could guide future strategies for sewage disposal for New York City.
This program will provide traditional research and thesis opportunities
for a state-funded Ph.D. program and NOAA-funded undergraduate internships.
Moreover, it will provide focus for the first 5 years a new Masters
in Operational Oceanography program initiated in 2002 by project
PI’s. Finally, ongoing collaboration with the Mid-Atlantic
Center for Ocean Science Education Excellence (COSEE) will be strengthened
by adding components on biological and chemical processes in buoyant
river plumes. COSEE integrates oceanographic research and education
programs to audiences that include coastal managers, K-12 teachers
and their students--especially underrepresented groups in the marine
science.
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