Citation:

MORALES, K. C., J. V. MACIAS ZAMORA, AND R. A. BURKE. DISSOLVED METHANE IN THE SILLS AREA, GULF OF CALIFORNIA, MEXICO. Presented at Workshop on Oxygen Minimum Systems in the Ocean: Distribution, Diversity and Dynamics , Concepcion, CHILE, October 24 - 26, 2006.

Impact/Purpose:

The overall objective of this task is to identify or develop useful indicators of organic waste enrichment in aquatic systems that are easily measured and based on basic underlying ecosystem processes so that they will be widely applicable. These activities will primarily contribute to an APG within Long Term Goal 2 of the Water Quality Research Program Multiyear Plan: the 2008 APG on equipping EPA Regions, States, and Tribes with knowledge, skills and tools to determine the causes of impairments for freshwater and coastal systems required in various regulations and will also contribute to EPA Strategic Plan 2003-2008 Sub-objective 2.2.2: Improve Coastal and Ocean Waters. Activities that address the 2008 Water Quality APG will focus primarily on small streams of the Georgia Piedmont, which receive human and agricultural waste inputs. The activities related to EPA Sub-objective 2.2.2 will focus on the nearshore marine ecosystem of the Pacific Ocean, which receives treated wastes from the approximately 15 million people who live in the coastal zone of southern California and northern Baja California, Mexico, and on the nearshore marine ecosystem of the Gulf of California, which receives little anthropogenic pollution. The indicators that will be evaluated or developed will include concentrations of trace gases (N2O, CH4, and CO2), dissolved oxygen (DO), nutrients, and dissolved organic matter (DOM), other key parameters such as temperature, conductivity or salinity, flow rate, alkalinity, and pH, rates of key processes such as denitrification and DO consumption, and stable isotope ratios of various pools and substrates such as plants, animals, sediments, and DO.

Description:

The northern part of the Gulf of California is physically separated from the rest of the Gulf by a series of sills and islands. Its waters are highly productive as several water masses interact with each other at the sills. One of the characteristics in the area is the presence of the Oxygen Minimum Zone located just south of the sills. Its chemical manifestation can probably be best observed by methane concentrations in the water column. We decided to measure the distribution of methane concentration in the water column in this area to serve as a tracer of mixing water masses.

Record Details: