anoxia in narragansett bay can we predict it?
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Anoxia in Narragansett BayCan we predict it?
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Narragansett Bay Fixed-Site Water Quality Monitoring NetworkNarragansett Bay Fixed-Site Water Quality Monitoring Network
•Agencies: RIDEM-OWR, URI/GSO, NBNERR, NBC, NBNEP, & RWU
•Site Locations: West Passage, East Passage, Providence River, Seekonk River, West Greenwich Bay, & Mt. Hope Bay
•Funding: NOAA Bay Window Program, EPA Clean Water Act (sections 319 & 106), & NOAA National Estuary Program
North Prudence Bottom Oxygen Levels: 2001-2006
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Hypoxia Study Program Goals
• Predictive/modeling tools for decision makers
• Models that predict susceptibility to hypoxia
• Integrated parameterizations
• Transferability of results across systems
• Data to calibrate and verify models
Our approaches• Hybrid Ecological-Hydrodynamic Modeling
– Ecological model: simple• Few processes, few parameters• Parameters that can be constrained by measurements• Few spatial domains (~20), as appropriate to measurements available• Net exchanges between spatial domains: from hydrodynamic model
– Hydrodynamic model: full physics and forcing of ROMS• realistic configuration; forced by observed winds, rivers, tides, surface fluxes• Applied across entire Bay, and beyond, at high resolution• Passive tracers used to determine net exchanges between larger domains of
ecological model
• Empirical-Statistical Modeling– Input-output relations, emphasis on empirical fit more than mechanisms– Development of indices for stratification, hypoxia susceptibility– Learn from hindcasts, ultimately apply toward forecasting
An alternative approach? 4 state variables, 5 processes
N P
N
Land-use
Atmosphericdeposition
N P
Productivity
Temp, Light,Boundary Conditions
Chl, N, P, Salinity
Phytoplankton
Sedimentorganics
.
.
Physics
Surface layer
- - - - - - - - -
Deep layer
- - - - - - - - -
Bottom sediment
O2
Flux tobottom
Photic zoneheterotrophy
Benthicheterotrophy Denitri-
fication
O2 coupledstoichiometricallyBZI
ƒ(Chl10d)ƒ[Chl]
ƒ(OM,T) %
Processes of the model & basis for formulations:
mixing flushing
Field Work in Support ofEcological Models
Historical Hypoxia based on benthic foramsWater Column MetabolismSediment Oxygen DemandDenitrification RatesOxygen Surveys ( some with other funding)Survey of nutrient concentrations
AccomplishmentsPhysical model running.Ecological model started.Input output model started.One year of denitrification measurements.Historical foram survey completed.Half a year of metabolism measurements.Physical measurements made in the upper bay:
currents upper east and west passages.water column profiling.neap tide studies.
Intensive oxygen surveys conducted for two summers.Workshop conducted with environmental mangers.