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Chemical Dumpsite Offshore Southern California
Scripps Institution of Oceanography conducts DDT Research to address key needs
Scripps Institution of Oceanography researchers, working with collaborators from UC Santa Barbara and San Diego State University, have been conducting research to assess the extent and scope of contaminant impacts and mitigation strategies for deep ocean dumping sites in Southern California.
Read below for further information on each project AND CLICK HERE TO EXPLORE THE SOUTHERN CALIFORNIA DDT+ RESEARCH PORTAL.
Surveying extent of dumping at Dumpsites 1 and 2
Carried out by Dr. Eric Terrill & Dr. Sophia Merrifield
The goal of this work is to characterize the debris field at the San Pedro dump site, map the extent of the dumping, and outline the bottom type and variability of the physical environment at the dump site. The researchers are applying modern robotic surveying techniques such as acoustic and optical imaging to survey the seafloor within and around Dumpsites 1 and 2.
Photo Credit: Eric Terrill & Sophia Merrifield
Surveying DDT+ beyond Dumpsites 1 and 2
Carried out by Dr. David Valentine
The goal of this work is to conduct chemical sediment mapping to determine the location and disposition of DDT+ wastes that were short dumped en route to Dumpsite 1, and the extent to which those wastes currently impinge on Catalina Island. Samples are being collected as sediment cores, divided into vertical sections, and then analyzed for DDT+ using standard U.S. Environmental Protection Agency (EPA) methods.
Photo Credit: David Valentine
Assessing whether DDT+ settles on the ocean floor or recirculates
Carried out by Dr. Uwe Send
The goal of this work is to quantify DDT+ exposure in the deep basin and on the continental slope resulting from sediment resuspension, and for the first time quantify release of dissolved DDT+ from the sediment. To achieve this, the team is deploying one mooring to continuously measure chemical properties, turbidity and currents near the seafloor, capture suspended sediment, and quantify accumulated DDT+. The data from these measurements will indicate DDT+ exposure risk as a function of time and demonstrate the frequency of natural sediment disturbance and flushing events.
Photo Credit: David Valentine
Validating a model assessing DDT+ transport and exposure
Carried out by Dr. Sarah Gille & Dr. Matthew Mazloff
The goal of this work is to validate a DDT+ exposure risk model against on-the-ground observations of the Southern California Bight to identify factors that could impact DDT+ exposure risks within the region. The team is developing ocean models to provide spatial information on the motion of bottom waters, extending beyond the reach of the mooring measurements and will explore variability over the planned 6-9 month mooring deployment period and beyond.
Photo Credit: Schmidt Ocean Institute
Identifying bottom-dwelling organisms at Dumpsites 1 and 2
Carried out by Dr. Gregory Rouse
The goal of this work is to archive representative benthic invertebrates from Dumpsites 1 and 2 into the Benthic Invertebrate Collection at Scripps. The animals will then be identified to the highest degree of accuracy and establish a specimen and DNA baseline to be used across the sites for this study and future studies. The team is sampling, sorting, and identifying the benthic invertebrates of San Pedro and Santa Monica Basins from barrels and core samples. Experts on various taxonomic groups are aiding the identifications and at least one species has been discovered to date.
Photo Credit: Gregory Rouse
Examining the role of bottom-dwelling marine organisms in spreading toxins
Carried out by Dr. Lisa Levin & Dr. Carlos Neira
The goal of this work is to characterize the benthic animals in the San Pedro Basin in relation to the distance from waste barrels and sediment concentrations containing DDX. This work aims to understand the effect of DDT+ contamination on the structure and function of the benthic biota, and to examine the potential roles of animals in contaminant redistribution and trophic transfer. To do this, the team is capturing the size, structure, density, distributions, diversity and taxonomic composition and life habits of the benthic biota.
Photo Credit: Gregory Rouse
Analyzing DDT+ accumulation in ocean ecosystem around Dumpsites 1 and 2
Carried out by Dr. Lihini Aluwihare, Dr. Anela Choy, & Dr. Eunha Hoh
The goal of this work is to create an inventory of DDT+ in both sinking and suspended particulate organic matter and biota. The team will examine the trophic transfer of DDT+ in and around the deep waters of Dumpsite 1 and 2. To assess trophic connections, the team is collecting samples of particles, zooplankton and micronekton from different depths, sorting the organisms by ecological traits (e.g., vertical distributions and migration, diet, size, feeding mode), and conducting targeted and non-targeted analyses on the samples.
Photo Credit: Anela Choy
Analyzing whether bacteria can reduce levels of DDT+ in the ocean
Carried out by Dr. Jack Gilbert and Dr. Paul Jensen
The goal of this work is to assess the remediation potential of microbes in the sediments of the San Pedro Basin. The team is trying to find microbes that can degrade DDT into less toxic chemical compounds, such as carbon dioxide, and in turn reduce DDT+ accumulation in wildlife destined for consumption. To achieve this, the team analyzes the resident microbial communities and employs metagenomics to identify DDT-degrading taxa. Using computational simulations the team defines microbial assemblages that can alter DDT breakdown products and determine whether the defined microbial assemblages can reduce the bioaccumulation of DDT+ in oyster tissue.
Photo Credit: Dr. Colleen Burge
Examining how DDT+ could end up in fish we eat
Carried out by Dr. Brice Semmens
The goal of this work is to assess the origin and fate of DDT+ in the marine food web of the Southern California Bight, with a focus on species that may be ecologically important indicators of deep-sea contamination and/or vectors of contamination to human consumers. The research team is sampling tissue and quantifying toxicant concentrations in fish species targeted by commercial, recreational, and subsistence fishers. Additionally, existing fish consumption data is being synthesized and analyzed to better assess the vulnerability of particular subgroups within California coastal communities.
Photo Credit: Johanna Gutleben
EXPERTS AT SCRIPPS
UC San Diego’s Scripps Institution of Oceanography has a variety of scientific experts on this issue. These scientists can provide expertise on methods to identify the scope and condition of the dumpsite, the processes that transport and alter composition of the dumped chemicals, biological pathways that may lead to human exposure these impacts, and more.
LOS ANGELES TIMES | Jan 5, 2024
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