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: Hahn, Intaek
Project Period: January 1, 1996 through September 10, 1998
Project Amount: $102,000
RFA: STAR Graduate Fellowships (1996) RFA Text |  Recipients Lists
Research Category: Fellowship - Oceanography , Aquatic Ecosystems , Academic Fellowships


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.


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

Progress and Final Reports:

  • 1996
  • 1997
  • Final