PCBs in fish caught in Maryland from 1986 to 2021
Description
Historical dataset collected to establish fish consumption advisories represents a valuable source of information on contamination levels in the waterbodies and changes over time. Of particular interest to environmental managers is the extent to which current and future levels of persistent chemicals in fish reflect the expected response to completed remediation projects. In this study, PCB concentrations measured across 323 monitoring stations in Maryland over 3 decades were curated and used to perform spatial and temporal analysis. Five watersheds out of 25 were identified as highly impacted by PCBs including the Upper Chesapeake Bay. Known areas of contamination were better predictors of PCBs in fish than generic land use or toxic release information, but PCB transport across watersheds may also explain PCB levels in watersheds with little or no known PCB sources. Impacted watersheds showed slow nationally consistent natural attenuation rates ranging from 2% to 6% yr-1, except the Gunpowder-Patapsco near Baltimore MD, where no temporal trend was observed since 1996. The overall study showed that PCB source mitigation implemented across Maryland and surrounding States helped recoveries, but more efforts are needed to fully control all PCB sources (legacy or ongoing) that are still impacting the rivers and fish.
Files
Steps to reproduce
Data for fish caught in Maryland watersheds were collected from the EPA National Listing of Fish Advisories (1986-2000, n=588), UMCES Chesapeake Biological Laboratory internal database (2000-2009, n=757), the MDE water quality portal (WQP) (2008-2017, n=234), and UMBC Ghosh’s lab internal database (2008-2021, n=292), resulting in a total of 1,920 samples. Data collected included sample or composite ID, fish species, date of collection, catch location description, and when available fish weight and length, count of fish individuals per sample, fish processing and filleting method, station ID, lipid content, individual PCB congeners, homolog group and total PCB concentration, and method of analysis. The data repository was completed per sample with a watershed hydrological unit (HU) 8 and 10 based on catch location using USGS watershed boundary dataset (WBD), a waterbody ID, and a site ID based on composite ID and/or station ID to allow summary analysis per watershed, waterbody and per site over time. The collection season was also determined and reported in the data repository. Collection dates indicated on WQP were cross-checked against the internal chain of custody sheets (COC). GPS coordinates were cross-checked against station ID coordinates (if available) and/or catch location and flagged if inconsistencies were noted. Correction and/or update was performed as mentioned in the catch location comment column of the data repository.
Institutions
- University of Maryland Baltimore County
Categories
Funders
- Maryland Department of the Environment