Sponsor
This study is supported by the University of California San Diego, Division of Extended Studies in partnership with The Inamori Foundation and Girard Foundation as part of the development and implementation of “Futures” Life Sciences student research immersion program at the Boz Life Science Research and Teaching Institute.
Published In
Chemosphere
Document Type
Article
Publication Date
11-2023
Subjects
Estuary reserves -- Mexico, Pesticides -- pollution
Abstract
The Tijuana River Estuary (TRE) has been a public health hazard and point of contention between the United States and Mexico for decades, with sources of pollution on both sides of the border. The goal of our study is to determine the presence and dynamics of chemical contamination in the TRE. We sampled sediment from four TRE locations in the U.S. during stable dry conditions and immediately after a wet weather period. Organic chemicals were initially screened with non-targeted analysis using gas chromatography high-resolution mass spectrometry (GC/HRMS) that tentatively identified 6978 chemicals in the NIST 20 database. These tentative identifications were filtered using the USEPA CompTox database to guide quantitative targeted analysis at detection limits below 1 ng/g dry weight sediment. Quantitative targeted analysis of 152 organic pollutants and 18 inorganic elements via GC/HRMS revealed generally higher concentrations of contaminants in dry weather sediments compared to wet weather sediments. The highest concentrations of all chemical classes were detected at the site closest to the U.S.-Mexico border, followed by an urban area near Imperial Beach, California, U.S. All sites exhibited a mixture of petrogenic and pyrogenic polycyclic aromatic hydrocarbons (PAHs). Current-use pesticides were dominated by pyrethroid insecticides and the thiocarbamate herbicide s-Ethyl dipropylthiocarbamate (EPTC), while the U.S.-banned organochlorine pesticides were dominated by chlordanes, dieldrin, and dichlorodiphenyltrichloroethane (DDT) and its degradation byproducts. Polychlorinated biphenyl (PCB) concentrations were greatest at the site closest to the U.S.-Mexico border but in the low nanogram-per-gram range. Phthalates were only found at the same site, with relatively high concentrations of bis(2-ethylhexyl) phthalate. This study provides positive identification and quantitative concentrations for organic pollutants in TRE sediments. Our data suggest that there are multiple sources of chemical contamination in the estuary, including possible transboundary movement of pollutants from Mexico.
Rights
Copyright (c) 2023 The Authors
This work is licensed under a Creative Commons Attribution 4.0 International License.
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DOI
10.1016/j.chemosphere.2023.140749
Persistent Identifier
https://archives.pdx.edu/ds/psu/41033
Citation Details
McLamb, F., Feng, Z., Shea, D., Bozinovic, K., Vasquez, M. F., Stransky, C., ... & Bozinovic, G. (2024). Evidence of transboundary movement of chemicals from Mexico to the US in Tijuana River Estuary sediments. Chemosphere, 348, 140749.