Austin K. Baldwin Steven R. Corsi Sherri A. Mason tabular digital data Reston, VA U.S. Geological Survey http://dx.doi.org/10.5066/F7ZC80ZP Austin K. Baldwin Steven R. Corsi Sherri A. Mason Journal publication: Environmental Science & Technology not yet available This dataset describes the quantity and morphology of floating microplastics in 29 Great Lakes tributaries in 6 states. Samples were collected in spring 2014 – spring 2015. Each tributary was sampled three to four times, capturing low-flow and runoff-event conditions. Sampling and analysis methods are described in the .xml metadata file. These data are interpreted in a journal article (cite journal article). Data were obtained in order to assess the occurrence of microplastics in Great Lakes tributaries. This study was funded by the Great Lakes Restoration Initiative. 20140408 20150512 ground condition Complete Not planned -92.823486328009 -74.32250976625 47.144599899062 40.596938415101 USGS Thesaurus nonpoint-source pollution surface water (non-marine) runoff river systems None microplastics USGS Metadata Identifier USGS:5748a29be4b07e28b664dd62 USGS Common Geographic Areas Great Lakes Minnesota Wisconsin Indiana Michigan Ohio New York none Austin Baldwin USGS mailing and physical

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Boise Idaho 83702 USA 208-387-1365 akbaldwi@usgs.gov US EPA Great Lakes Restoration Initiative No formal attribute accuracy tests were conducted Data have been checked for duplication, omission, and expected ranges. Data set is considered complete for the information presented, as described in the abstract. Users are advised to read the rest of the metadata record carefully for additional details. Sampling positions identified using USGS Station Identifiers with established locations. Sampling positions identified using USGS Station Identifiers with established locations. Reformating data from laboratory; Computation of concentrations using volume of water sampled and the microplastic counts from the lab 20160115 both The sampling methods and equipment were consistent with those previously used in the Great Lakes (Eriksen et al. 2013), with some modifications for the river setting. Samples were collected using a 1.5 m long neuston net with an opening of 100 cm wide x 40 cm high (Sea-Gear Corp., Miami, Florida, USA). The net mesh size was 333 µm, a commonly used size in microplastic studies (Eriksen et al. 2013; Free et al. 2014; Yonkos et al. 2014; McCormick et al. 2014; Cole et al. 2011; Masura et al. 2015). The net skimmed the surface and upper 20-35 cm, keeping a portion of the net opening above water. The amount of net submerged was monitored and recorded and an effort was made to maintain a consistent submersion depth throughout the sample duration. Sampling duration ranged from 5-82 minutes (median 15 minutes), and was dependent on the velocity of water entering the net and how quickly the net began to clog with organic material, especially algae. A flow meter (Sea-Gear Corp.) suspended in the net opening recorded the average velocity. The total volume of water filtered through the net was computed from the width and height of the submerged portion of the net, the sampling duration, and the average velocity. Samples were collected by boat, from a bridge, or by wading, depending on the river depth, velocity, and access at each location. For boat-collected samples the net was towed alongside the boat, held out beyond the bow wake using a metal pole fixed to the boat. For bridge-collected samples, the net was suspended from a bridge using a crane. For wading-collected samples, the net was held between and upstream of two people standing in the river, allowing the river current to flow through the net. Bridge and wading samples were collected from a fixed location at the center of the channel. After sample collection the net was hung and sprayed from the outside using a pressurized backpack sprayer with 8-15 liters of tap water or stream water filtered through a 333 µm mesh. Spraying the outside of the net washed the sampled material- plastics, organic debris, fine sediment, and other items- down into the detachable mesh cod end at the bottom of the net. The sample was then transferred to a glass jar using a stainless steel spoon and squirt bottle with tap water, and preserved with isopropyl alcohol. Three samples were omitted from results because flow meter malfunction precluded computation of the water volume sampled. An additional three samples were broken in transit or were spilt. One hundred and seven samples were successfully collected and analyzed. Samples were processed in a laboratory for isolation of plastic debris using a modified NOAA marine debris protocol (Masura et al. 2015), briefly described here. Each sample was filtered through a series of 8-inch diameter Tyler sieves of 4.75 mm, 1.00 mm and 0.355 mm stainless steel mesh, separating the solid material into 3 size classifications (0.333-0.999 mm, 1.00-4.749 mm, and >4.75 mm). The solids in each size class were subjected to a wet peroxide oxidation (WPO), which digests labile organic material using 30% hydrogen peroxide in the presence of an iron (II) catalyst. Plastic debris is resistant to this WPO processing. After processing, samples were filtered and, using a 40x dissection microscope, all microplastic particles were removed, enumerated and categorized as fragments (broken down pieces of larger debris such as plastic bottles), pellets/beads (preproduction pellets and microbeads from personal care products and bead blasting), line/fiber (particles of fishing line and nets, and fibers from synthetic textiles), film (plastic bags and wrappers), or foam (foam cups, take-out containers, packaging). All plastic particles were saved for possible later analysis. MP particle concentrations, computed using the mean velocity of water entering the net, the duration of sampling, and the width and submerged depth of the net, are reported in particles per cubic meter. Five field blank samples were collected to assess the potential of the nets as sources of cross-contamination from one sample to another. Cleaned nets were hung and the outside of the nets were thoroughly sprayed with tap water from either a water hose or pressurized backpack sprayer, as was done with environmental samples. Any microplastic particles remaining in the net from previous environmental samples were washed down and captured in the detachable mesh cod end. The particles were then transferred to a glass jar, preserved, and analyzed using the same laboratory method as environmental samples. REFERENCES Cole, M., P. Lindeque, C. Halsband, and T.S. Galloway. 2011. “Microplastics as Contaminants in the Marine Environment: A Review.” Marine Pollution Bulletin 62 (12): 2588–97. doi:10.1016/j.marpolbul.2011.09.025. Eriksen, M., S. Mason, S. Wilson, C. Box, A. Zellers, W. Edwards, H. Farley, and S. Amato. 2013. “Microplastic Pollution in the Surface Waters of the Laurentian Great Lakes.” Marine Pollution Bulletin 77 (1–2): 177–82. doi:10.1016/j.marpolbul.2013.10.007. Free, C.M., O.P. Jensen, S.A. Mason, M. Eriksen, N.J. Williamson, and B. Boldgiv. 2014. “High-Levels of Microplastic Pollution in a Large, Remote, Mountain Lake.” Marine Pollution Bulletin 85 (1): 156–63. doi:10.1016/j.marpolbul.2014.06.001. Masura, Julie, Joel Baker, Gregory Foster, and Courtney Arthur. 2015. “Laboratory Methods for the Analysis of Microplastics in the Marine Environment: Recommendations for Quantifying Synthetic Particles in Waters and Sediments. NOAA Technical Memorandum NOS-OR&R-48.” McCormick, A., T.J. Hoellein, S.A. Mason, J. Schluep, and J.J. Kelly. 2014. “Microplastic Is an Abundant and Distinct Microbial Habitat in an Urban River.” Environmental Science and Technology 48 (20): 11863–71. doi:10.1021/es503610r. Yonkos, Lance T., Elizabeth A. Friedel, Ana C. Perez-Reyes, Sutapa Ghosal, and Courtney D. Arthur. 2014. “Microplastics in Four Estuarine Rivers in the Chesapeake Bay, USA.” Environmental Science & Technology. http://pubs.acs.org/doi/abs/10.1021/es5036317. Julie Masura 2015 document http://marinedebris.noaa.gov/sites/default/files/publications-files/noaa_microplastics_methods_manual.pdf USGS Station IDs (for information see http://waterdata.usgs.gov/nwis/si) Point Microplastics_in_29_Great_Lakes_tributaries_2014_15.csv Microplastics concentrations in water samples from 29 Great Lakes tributaries, 2014-15 Austin Baldwin USGS station ID USGS numeric identifier of sampling location U.S. Geological Survey USGS Station IDs U.S. Geological Survey Station name USGS name for sampling location U.S. Geological Survey USGS Station names U.S. Geological Survey Date date sample was collected producer defined date sample was collected Start time sample collection start time producer defined sample collection start time End time sample collection end time producer defined sample collection end time Sampling duration (hours:minutes) duration of sampling producer defined duration of sampling Net depth submerged, average (m) Average submerged depth of the sampling net, in meters, used for computation of microplastic concentrations. The net skims the surface of the water, with a portion of the net remaining above the water. The depth of the net in the water can vary, based on a number of factors such as the velocity of water entering the net. The submerged depth of the net is visually monitored throughout the duration of sampling using increments on each side of the net’s frame. producer defined 0.11 0.4 meters Sampling method Location from which the sample was collected: from a boat, bridge, or while wading producer defined boat boat producer defined bridge bridge producer defined wading wading producer defined blank a field quality control sample (a field blank) producer defined Velocity measurement method the instrument used to record the velocity of water entering the net producer defined the instrument used to record the velocity of water entering the net Velocity, average (m/s) average velocity, in meters per second, of water entering the net; used for computation of microplastic concentrations producer defined 0.04 3.05 meters per second Water conditions notes on water clarity, floating debris, high suspended sediment, ice, or other notable conditions producer defined notes on water clarity, floating debris, high suspended sediment, ice, or other notable conditions Field comments notable comments about the sample producer defined notable comments about the sample Tow length, computed (m) computed tow length, in meters, based on average water velocity and sampling duration; used for computation of microplastic concentrations producer defined 34 2844 meters Volume sampled (m3) total volume of water filtered through the net, in cubic meters producer defined 6 768 cubic meters Hydrologic condition runoff-event (hydrologic flow above normal base-flow conditions due to rain or snow melt) or low-flow (base-flow) conditions during sampling producer defined runoff-event hydrologic flow above normal base-flow conditions due to rain or snow melt producer defined low-flow base-flow producer defined Particle size category size fraction of microplastic particles in the sample producer defined total_all total of all size fractions producer defined greaterthan4.75mm > 4.75 mm producer defined 1mm_4.75mm 1 mm - 4.75 mm producer defined 0.333mm_1mm 0.333 mm - 1 mm producer defined Count of fragments number of microplastic fragments in the sample producer defined 0 2594 count Count of pellets/beads number of microplastic pellets and beads in the sample producer defined 0 95 count Count of fibers/lines number of microplastic fibers and lines in the sample producer defined 0 1119 count Count of films number of microplastic films in the sample producer defined 0 260 counts Count of foams number of microplastic foams in the sample producer defined 0 1474 count Count total number of all microplastic particles in the sample (sum of fragments, pellets/beads, fibers/lines, films, and foams) producer defined 0 4464 count Concentration fragments/m3 fragments per cubic meter of water producer defined 0 18.6 number per cubic meter Concentration of pellets/beads/m3 pellets/beads per cubic meter of water producer defined 0 7.57 number per cubic meter Concentration fibers/lines/m3 fibers/lines per cubic meter of water producer defined 0 22.82 number per cubic meter Concentration films/m3 films per cubic meter of water producer defined 0 2.82 number per cubic meter Concentration foams/m3 foams per cubic meter of water producer defined 0 9.72 number per cubic meter Concentration total/m3 total particles per cubic meter of water producer defined 0 33.32 number per cubic meter U.S. Geological Survey - ScienceBase mailing and physical

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Denver CO 80225 USA 1-888-275-8747 sciencebase@usgs.gov The data have been approved for release and publication by the U.S. Geological Survey (USGS). Although the data have been subjected to rigorous review and are substantially complete, the USGS reserves the right to revise the data pursuant to further analysis and review. Furthermore, the data are released on the condition that neither the USGS nor the U.S. Government may be held liable for any damages resulting from authorized or unauthorized use. Although the data have been processed successfully on a computer system at the USGS, no warranty expressed or implied is made regarding the display or utility of the data on any other system, or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. The USGS or the U.S. Government shall not be held liable for improper or incorrect use of the data described and/or contained herein. Users of the data are advised to read all metadata and associated documentation thoroughly to understand appropriate use and data limitations. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. none 20200820 Austin K. Baldwin USGS Hydrologist mailing and physical

230 Collins Rd

Boise Idaho 83702 USA 208-387-1365 akbaldwi@usgs.gov Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998