MICROPLASTIC POLLUTION IN URBAN SURFACE WATERS: A SHORT-TERM MONITORING STUDY ON A SMALL WATERSHED SCALE J A S M I N E K . S T O V A L L & S U S A N P . B R A T T O N
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MICROPLASTICS DEFINED • Microplastics (MP) are polymer-based particles ranging in size from 50 µm to 5 mm • MP may exist in two main forms: • Primary manufactured on the microscopic scale • Secondary formed as a result of the breakdown of primary macroplastics overtime 3 Image Source: Encounter Edu
SOURCES OF MICROPLASTICS MP can enter into and be transferred within aquatic systems via numerous pathways Improper waste management Industrial abrasives Surface, stormwater, & agricultural runoff WWTP discharge Fishing materials Aerial transport Industrial waste effluent 4
MICROPLASTICS IN THE LITERATURE • Marine MP studies began as early as the 2000’s • Ubiquitous MP presence throughout oceanic environments worldwide • Interactions between MP and marine organisms have been investigated • MP pollution in freshwater systems have only recently become of concern • Inland waters may be a source of origin for marine MP • A shift of focus in the literature to MP pollution in freshwater systems has recently occurred 5 Image Source: Royal Society of Chemistry
• Characterization and abundance of MP in freshwater systems remains largely understudied • Little to no small scale monitoring studies regionally • Urban, freshwater systems STATEMENT OF THE • Above and below sewage effluent PROBLEM comparisons • This research is in response to the lack of existing data and understanding pertaining to MP pollution in urban surface waters within the central Texas region and the Gulf of Mexico. 6
PURPOSE OF THE STUDY 1. Examine and compare MP pollution levels in urban freshwater systems above and below local point-source wastewater effluents 2. Investigate patterns in spatial distribution 3. Evaluate the influence that factors such as urbanization may have on the origin and transport of MP within small watersheds Microplastics defined as “artificial polymers (e.g. polyester or nylon), and manufactured products (i.e. manufactured natural and non-natural material), that range in size from 50 to 5000 μm” (Peters and Bratton, 2016). 7
STUDY LOCALES Wilson’s Creek Buena Vista San Marcos River General Waco Creek Proctor Springs (WsC) – Locale Pond (BVP) – (SMR) – Locale Descriptive (WC) – Locale #1 (PS) – Locale #3 #2 Locale #4 #5 Run-off, low High discharge Water Source Run-off Groundwater Run-off discharge spring spring No. of Sample 6 2 3 1 6 Sites No. of Sampling 7 4 5 4 3 Rounds Sept. 2017, Oct. July 2017, Mar. July 2017, Mar. July 2017, Mar. 2017, Mar. 2018, 2018, Apr. 2018, Apr. 2018, June Sampling Dates 2018, Apr. 2018 & 2018, Apr. 2018, Apr. 2018, June June 2018 & July 2018, & July 2018 June 2018 & June 2018 2018 & July 2018 2018 8
METHODS: PREPARATION AND COLLECTION • 779 surface water samples collected • Sample volume = 800-mL • 5 micro-habitat types • Two replicates at each sample site • Samples filtered through a 53 μm mesh filter • Covered with a 4-inch diameter glass round • Sealed in aluminum foil 9
METHODS: PREPARATION AND COLLECTION • Visual observation used to assess physical site characteristics • Depth, distance from the bank, plastic abundance and type of debris were measured where the sample was collected • Temperature, pH, conductivity, TDS, DO and current recorded at each sample site 10
METHODS: LABORATORY ANALYSIS • Filters visually analyzed via stereomicroscopy • MP extracted by hand, transferred to a microscope slide and sealed with cover slip • Particles characterized by form, color and condition 11
METHODS: QA/QC • Filters, glass covers, and foil wraps were triple rinsed with deionized water and visually examined via microscopy • The colors of each team member’s clothing and shoes were recorded • Samples were stored, transported, processed and analyzed with glass covers on at all times, with the exception of fiber extraction • Any occurrences of contamination in field from ambient air were considered part of the sample. 12
RESULTS • 1,198 MP were recovered across all five study locales • Fibers (95.0%) and fragments (5.0%) • ~57% of all samples were contaminated with MP 100% 90% 80% Present Absent Percent of Particles 70% 60% Study Locale Frequency Percent Frequency Percent 50% 40% Waco Creek 251 59.8 169 40.2 30% Wilson’s Creek 49 62.0 30 38.0 20% Buena Vista Pond 10% 17 42.5 23 57.5 0% Wilson's Proctor Buena Vista San Marcos Waco Creek Creek Springs Pond River Proctor Spring 43 71.7 17 28.3 Microbead 0 0 0 0 0 San Marcos River Fragment 33 7 19 0 1 86 47.8 94 52.2 Fiber 630 98 185 39 186 Microplastic Particle Form Fiber Fragment Microbead 13
Microplastics vs. Sample Site Waco Creek 2.5 San Marcos River* 3 Mean No. of Microplastics Per Sample Mean No. of Microplastics Per Sample 2 2.5 R 2 =0.5449 2 1.5 R² = 0.3042 1.5 1 1 0.5 0.5 0 0 Site 1 - SSP Site 2 - PT Site 3 - SC Site 4 - STP Site 5 - RVP Site 6 - SWP Site 1 - BSB Site 2 - BB Site 3 - CC Site 4 - BHP Site 5 - FC Site 6 - BD Sample Site Sample Site 14 * Indicates significance
Microplastics vs. Sewage Effluent Waco Creek San Marcos River* 2 2.5 1.8 1.6 2 Mean No. of Microplastics Per Sample Mean No. of Microplastics Per Sample 1.4 1.2 1.5 1 0.8 1 0.6 0.4 0.5 0.2 0 0 Aboove Effluent Below Effluent Above Effluent Below Effluent 15 * Indicates significance
Waco Creek* 3.5 Wilson’s Creek* 3 Mean No. of Microplastics Per Sample 3 2.5 Mean No. of Microplastics Per Sample 2.5 2 2 1.5 1.5 1 1 0.5 0.5 0 0 Sept. 2017 Sept. 2017 Oct. 2017 Mar. 2018 Apr. 2018 Jun. 2018 Jul. 2018 Jul. 2017 Mar. 2018 Apr. 2018 Jun. 2018 Sampling Interval (Date) -0.5 Sampling Interval (Date) Proctor Springs* San Marcos River 16 2.5 Mean No. of Microplastics Per Sample 14 Mean No. of Microplastics Per Sample 2 12 10 1.5 8 6 R² = 0.9869 1 4 2 0.5 0 Jul. 2017 Mar. 2018 Apr. 2018 Jun. 2018 Jul. 2018 -2 0 Apr. 2018 Jun. 2018 Jul. 2018 -4 Sampling Interval (Date) Sampling Interval 16 * Indicates significance
Microplastic Frequency vs. Study Locale 180 4 160 3.5 140 Mean No. of Microplastics Per Sample 3 120 2.5 Frequency 100 2 80 60 1.5 40 1 20 0.5 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 >25 0 Number of Particles Per Sample Waco Creek Wilson's Creek Proctor Springs Buena Vista Pond San Marcos River Study Locale Waco Creek Wilson's Creek Proctor Springs Buena Vista Pond San Marcos River 17
Microplastics Hue Classification 35 30 25 % of Samples 20 15 10 5 0 Transparent Purple-blue Blue Purple Red-purple Red Other Hue Waco Creek Wilson's Creek Proctor Springs Buena Vista Pond San Marcos River 3.5 3 2.5 % of Samples 2 1.5 1 0.5 0 Munsell Color System Image Source: kisspng Hue 18 Waco Creek Wilson's Creek Proctor Springs Buena Vista Pond San Marcos River
WC2 “Hot spots” SM4 PS3 WC5 Highly urbanized lower watershed WC4 WC1 WC3 WC6 SM6 Upper WS2 watershed WS1 BV1 PS1 Springs PS2 SM1 SM2 High recreation SM3 SM5 19
CONCLUSIONS • Widespread pollution throughout the systems • Localized effects of land use and human activity drive subtle changes in MP influx levels • Hot spotting at high traffic recreational sites show that similar land use type may result in analogous input sources, plastic types and colors • Seasonality, land use and the associated local human activity have a stronger influence on overall microplastic frequency within the system • Actual spatial positioning within the watershed likely influences particle color and form • More research, effective mitigation practices, governmental attention and public awareness are still very much urgent needs. 20
FUTURE RESEARCH • Projects focusing more on temporal variables and seasonal events rather than spatial variables • Chemical analysis and polymer ID of recovered MP • Investigating possible relationships between chemical characteristics of stream and chemical properties of MP within the system 21
ACKNOWLEDGEMENTS • Thesis Advisor • Undergraduate Research Assistants • Dr. Susan P. Bratton • Funding Support • Jessica Bateman • Hannah Dye • Baylor University Research Committee • Lauren Medlin • Baylor University Graduate School • Madison Ohler • Baylor University Department of • Jonah Salazar Environmental Science • Rafael Sandoval • Jordan Vanderpool • City of Waco Water Department 22
23 Image Source: Orb Media
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