You are here:
USE OF δ13C, δ15N AND CARBON TO NITROGEN RATIOS TO EVALUATE THE IMPACT OF SEWAGE DERIVED PARTICULATE ORGANIC MATTER ON THE BENTHIC COMMUNITIES OF THE SOUTHERN CALIFORNIA BIGHT
Citation:
RAMIREZ-ALVAREZ, N., J. V. MACIAS-ZAMORA, R. A. BURKE, AND L. V. RODRIGUEZ-VILLANUEVA. USE OF δ13C, δ15N AND CARBON TO NITROGEN RATIOS TO EVALUATE THE IMPACT OF SEWAGE DERIVED PARTICULATE ORGANIC MATTER ON THE BENTHIC COMMUNITIES OF THE SOUTHERN CALIFORNIA BIGHT. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY. Society of Environmental Toxicology and Chemistry, Pensacola, FL, 26(11):2332-2338, (2007).
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:
We present stable isotope (δ13C and δ15N) measurements of particulate organic matter (POM) sources and benthic organic matter (OM) compartments, and sediment C/N ratios from the coastal area of the southern end of the Southern California Bight (SCB). We use the isotopic values to evaluate the relative importance of the major POM sources to the sediment and two benthic macroinvertebrates. Application of a simple model to sediment δ13C values suggests that sewage derived POM (SDPOM) supplies an average of 48% of the organic carbon to study area sediments. Application of a similar model to Spiophanes duplex δ13C values suggests that SDPOM from wastewater treatment plants discharging into the SCB could supply up to 28 % of the C assimilated by this important benthic macroinvertebrates in areas as far away as 26 km from SDPOM inputs. The Amphiodia urtica stable isotope data are more difficult to interpret because of the complex feeding habits of this organism.