This project is beginning in the summer of 2016 and is funded by the NOAA Marine Debris Program.

Estimates of plastic debris in the worlds ocean vary widely from ~244,000 metric tons floating at the surface to 4.8-12.7 million metric tons loaded from terrestrial inputs annually. These estimates are based on open ocean surveys and plastic BaffinBayInsetconsumption/waste disposal data, not measurements of actual loads delivered to the ocean by terrestrial sources. To better understand the scale of this problem and develop mitigation strategies that lead to healthier global oceans, plastic debris inputs from major river sources must be quantified.

Rivers are the arteries of inland watersheds—transporting terrestrial materials to the ocean. Thus, they are large sources of plastic debris to the marine environment. Of particular concern are microplastics (<5 mm diameter), which represent 92% of total plastics at the ocean surface. A major source of these microplastics is wastewater effluent discharged in surface waters. In the U.S., the Mississippi River watershed is likely one of the largest sources of oceanic plastic debris. It is home to 72 million people, drains nearly half (40%) of the country (2.98 million km2) and receives final effluent from >7,400 wastewater treatment discharges. The Baltic Sea watershed has similar characteristics (85 million people spread across 2.13 million km2 in 14 countries) and it was recently estimated that 40 tons of polyethylene (PE) microplastics enter this watershed annually. This estimate only accounted for PE, not other plastic polymers or synthetic fibers. Due to these parallels and higher per-capita consumption rates, the Mississippi River likely has similar, if not higher, loads of microplastics.

These microplastic loads likely impact coastal ecosystem health in the Mississippi River delta, home to some of the most productive fisheries in the world. By quantifying and characterizing Mississippi River microplastic loads entering the Gulf of Mexico (GoM) and assessing potential ingestion by aquatic organisms, we will address NOAA’s long-term mission goal of maintaining “Resilient Coastal Communities & Economies,” specifically the objective for “Improved coastal water quality supporting human health and coastal ecosystem services” by “examining the transport and fate of chemicals… and marine debris in waterways.”

While the C-HaWQ lab is taking the lead on the project, Dr. Elizabeth Hasenmueller at St. Louis University, Dr. John R. White at Louisiana State University and Dr. Lisa Chambers at the University of Central Florida are co-PIs and will be conducting method development and sampling of the Mississippi River.

Dr. Jeremy L. ConkleDepartment of Physical & Environmental SciencesTexas A&M UniversityCorpus Christi, TX 78412