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Phosphorus Cycling in the Gulf of Maine: A Multitracer Approach

EPA Grant Number: U914959
Title: Phosphorus Cycling in the Gulf of Maine: A Multitracer Approach
Investigators: Benitez-Nelson, Claudia R.
Institution: Massachusetts Institute of Technology
EPA Project Officer: Manty, Dale
Project Period: January 1, 1996 through September 10, 1998
Project Amount: $102,000
RFA: STAR Graduate Fellowships (1996)
Research Category: Fellowship - Oceanography , Academic Fellowships , Aquatic Ecosystems

Description:

Objective:

The objective of this research project is to utilize several naturally occurring, short-lived radionuclides (32P, 33P, 234Th) within the Gulf of Maine to quantify: (1) uptake and regeneration rates of nutrients in dissolved, suspended, and large particulate phases; (2) zooplankton grazing rates; and (3) export of carbon, nitrogen, and phosphorus from the euphotic zone.

Approach:

If the atmospheric input of cosmogenic 32P, 33P, and 7Be is known from direct measurement, the ratio of 32P and 33P to 7Be can be directly related to: (1) the known decay rates of these tracers; (2) the particle reactivity of 7Be; (3) physical mixing and advection; and (4) the uptake ratio of phosphorus into particulate pools (i.e., the biological cycle of nutrient uptake and remineralization). Essentially, 7Be is used as both a tracer of upper-ocean mixing and as a constraint on the input flux of the 32P and 33P isotopes. Additionally, if 234Th is measured, estimates of particle export can be obtained for 7Be, organic carbon, and the major nutrients. Seasonal sampling in Wilkinson Basin in the Gulf of Maine will enable accurate temporal resolution of nutrient turnover rates and export.

Supplemental Keywords:

fellowship, phosphorus, carbon, nitrogen, phosphorus cycling, Gulf of Maine, nutrient uptake, remineralization, nutrients. , Ecosystem Protection/Environmental Exposure & Risk, Scientific Discipline, RFA, Ecosystem/Assessment/Indicators, Oceanography, Ecology, Aquatic Ecosystems & Estuarine Research, Ecological Risk Assessment, Aquatic Ecosystem, Ecological Indicators, Ecological Effects - Environmental Exposure & Risk, Ecosystem Protection, Ecology and Ecosystems, Gulf of Maine, phosphorus, eutrophication, radionuclides, aquatic ecosystems, nitrogen, nutrient loading

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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