Adina Paytan ~ Multi-Scale Mentor

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Modulating Productivity

One of Dr. Adina Paytan's research areas in biogeochemical cycles focuses on the interactions between groundwater discharge, oceanic chemistry and living organisms. Of particular interest are nutrients - such as nitrate, phosphate, ammonium, and silicate - which impact the growth of organisms in aquatic environments, and trace metals, such as iron, which impact biological activity.

Several of Adina's research projects address coastal water quality. The project titled "Submarine groundwater discharge and nutrient loading in San Francisco Bay" studies the effects of agriculture and increased residential and industrial development on surface runoff and water quality into coastal ecosystems. In collaboration with the United States Geological Service, Lawrence Livermore National Labs, and University of California Berkeley, the work explores terrestrial and marine forces that drive subsurface flow into San Francisco Bay, and analyzes corresponding nutrient and heavy metal fluxes from each of these driving forces using naturally-occurring geochemical tracers.

Field work includes collecting and analyzing groundwater samples and measuring radium (a tracer for submarine groundwater discharge into the ocean), and calculating fluxes as groundwater mixes with seawater, looking at water quality issues associated with groundwater discharge at the land-sea interface.

A collaborative project with Monterey Bay Research Institute (MBARI), which has just been completed, looked at the sources and cycling of nitrogen through the use of sensors that provided continual sampling in offshore and nearshore locations. "If we learn about nitrogen sources and concentrations then we can start to understand how this nutrient modulates productivity," says Adina. "Too much nitrogen may have negative impacts, such as blooms of harmful algae."

Adina is also collaborating with MBARI on ocean acidification research in the tidal zone, growing organisms at different concentrations of carbon dioxide and seeing how that affects larval recruitment and growth rates.