Apr 11, 2025
Repeated Pass Removal Survey for Estimating Land-Based Trash Abundance
- Rebecca M. Reynolds1,
- Yuki Floyd1,
- Trace Martin1,
- Colleen Ahern2,
- James Bae3,
- Phoenix Cook3,
- Paola Rangel Martinez3,
- Tina Tran1,
- Christopher L. Jerde4
- 1Bren School of Environmental Science and Management, University of California Santa Barbara;
- 2Department of Chemical Engineering, University of California Santa Barbara;
- 3University of California Santa Barbara;
- 4Marine Science Institute, Bren School of Environmental Science and Management, University of California Santa Barbara
Protocol Citation: Rebecca M. Reynolds, Yuki Floyd, Trace Martin, Colleen Ahern, James Bae, Phoenix Cook, Paola Rangel Martinez, Tina Tran, Christopher L. Jerde 2025. Repeated Pass Removal Survey for Estimating Land-Based Trash Abundance. protocols.io https://dx.doi.org/10.17504/protocols.io.kxygxyjozl8j/v1
License: This is an open access protocol distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Protocol status: Working
We use this protocol and it's working.
Created: October 11, 2024
Last Modified: April 11, 2025
Protocol Integer ID: 109732
Keywords: plastic, microplastic, land-based litter, litter survey, trash survey, trash assessment methodology, single pass survey, multi-pass survey, multiple pass survey, k pass survey, depletion survey, removal survey
Funders Acknowledgements:
California Tobacco-Related Disease Research Grants Program Office of the University of California
Grant ID: T32DT5235
National Science Foundation
Grant ID: 1953492
Abstract
Land-based litter negatively impacts human and ecosystem health, tourism and recreation, and the economy.1 Most terrestrial, aquatic, and marine litter consists of plastic items, and a majority of aquatic and marine litter comes from terrestrial sources.2, 3, 4 Yet, plastic litter in terrestrial systems remains understudied relative to litter in aquatic and marine environments.3, 5 Surveying is a common method for determining litter abundance in terrestrial systems. Single-pass litter surveys, in which a surveyor passes through a transect once by foot, bicycle, or car, serve as the established method for assessing the qualitative or quantitative abundance of land-based litter. Established single-pass survey methods include but are not limited to the Bay Area Stormwater Management Association On-Land Visual Trash Assessment, various Surfrider and Channel Keeper “Beach Clean Up” methods, the Southern California Coastal Water Research Program Southern California Bight Regional Monitoring Program Trash Surveys, the Keep America Beautiful National Visible Litter Survey, the National Oceanic and Atmospheric Administration Marine Debris Monitoring and Assessment Project, the Ocean Conservancy International Coastal Cleanup, 5 Gyres Plastic Beach and Plastic Ocean methods, the University of Washington Coastal Observation and Seabird Survey Team Marine Debris Survey, the State of California Surface Water Ambient Monitoring Program Rapid Trash Assessment, the Alliance for the Great Lakes Adopt-A-Beach Litter Monitoring method, and some United States Environmental Protection Agency Trash Free Waters Projects.6 Single-pass litter survey methods are useful given the time and cost constraints often associated with boots-on-the-ground surveying. However, there is a tradeoff: single-pass surveys underestimate litter abundance relative to multiple-pass surveys, and single-pass surveys lack measures of the variance in litter abundance. This is primarily because single-pass surveys involve variable levels of surveying effort, and do not always result in quantitative measures. Underestimation of litter abundance and knowledge gaps regarding the variation in litter abundance will result in inaccurate results when it comes to monitoring and predicting litter source, transport, and fate. Additionally, due to unmeasured variation in litter abundance, data acquired through single-pass trash assessment methods or clean-up events are difficult to compare without measures of effort. To address these issues, the Repeated Pass Removal Survey for Estimating Land-Based Trash Abundance aims to better estimate the number of visible and removable plastic litter items in the environment, with a quantification of the uncertainty around that estimate suitable for comparison between sites.
Materials
One team of three surveyors will need the following materials to survey one transect:
- 1 timer (watch or smartphone with timer)
- 1 camera (or smartphone with camera)
- 1 GPS unit (or smartphone with GPS capability enabled)
- 1 permanent marker
- 3 pairs disposable gloves
- 3 resealable bags or buckets of a minimum size of 1 gallon
- 2 flags, cones, or one piece of sidewalk chalk
Safety warnings
Safety Precautions:
- Wear gloves to protect skin while removing and counting trash. Avoid direct contact with trash at all times.
- Avoid any contact with dangerous litter items including but not limited to weapons and sharps. Note that the item was observed but not removed during your survey.
Before start
1. Use a random number generator to assign each surveyor to their respective pass number depending on how many passes are planned. At a minimum, three passes should be conducted at each transect. Therefore, a team of three surveyors is needed per transect.
2. Using a permanent marker, clearly label one resealable bag or bucket for each planned survey pass. Include the following information: survey date, survey site, transect ID, surveyor name, and pass number.
Surveying Land-Based Trash
Surveying Land-Based Trash
Identify the transect’s starting location, and note the latitude and longitude on the first-pass bag or bucket.
Take a picture facing down the transect from the transect’s starting location.
Use existing visual boundaries to communicate the width of the transect to all surveyors (i.e. the edges of a walking path, or one-arms-length from the centerline of a walking path).
The first surveyor should set a timer for 15 minutes, and mark the starting location of the transect using a cone, flag, or chalk.
The first surveyor should then don gloves, start the 15 minute timer, and walk down the transect collecting all observed and removable litter as safely as possible.
The first surveyor should stop immediately when the 15 minute timer sounds, and seal the bag or bucket containing the litter they removed.
The first surveyor should remove their gloves, then record the longitude and latitude of the ending location of the transect on the first-pass bag or bucket. The first pass surveyor should mark the end location of the survey transect using a second cone or flag, or chalk.
Subsequent surveyors may begin once there is approximately five to ten feet of space between them and the preceding surveyor.
All surveyors should make the same effort while surveying the transect.
Subsequent surveyors should maintain a distance of approximately five to ten feet from the surveyor ahead of them to help ensure a consistent pace across all survey passes.
Place all litter inside the appropriately labeled resealable bag or bucket.
Only collect litter that is observed within the boundaries of the transect.
Note any litter that was observed but not collected due to safety concerns or size. Communicate this to subsequent surveyors.
Treat the transect as a closed transect, meaning any litter that enters the transect after the survey has begun cannot be included in the dataset of counts. However, this litter can be removed and disposed of after the survey is complete.
With the exception of the first pass surveyor, all surveyors should be able to see and follow the path set by the surveyor ahead of them.
No surveyor should ever pass the surveyor(s) ahead of them.
All subsequent passes should cover the entire transect distance and width covered in the first survey pass.
Counting Land-Based Trash
Counting Land-Based Trash
Count the litter in a safe location. If sorting takes place indoors, perform sorting in a well-ventilated space.
Once counted, either sort and appropriately dispose of the litter, or store the litter in sealed bags or buckets in a dark, 4°C room if further study of the collected litter is desired.
Protocol references
- United States Environmental Protection Agency. (2024). National Strategy to Prevent Plastic Pollution: Part Three of a Series on Building a Circular Economy for All. Retrieved December 1, 2024, from https://www.epa.gov/system/files/documents/2024-11/final_national_strategy_to_prevent_plastic_pollution.pdf
- van Emmerik, T., Mellink, Y., Hauk, R., Waldschläger, K., & Schreyers, L. (2022). Rivers as Plastic Reservoirs. Frontiers in Water, 3, 786936. https://doi.org/10.3389/frwa.2021.786936
- Malizia, A., & Monmany-Garzia, A. C. (2019). Terrestrial ecologists should stop ignoring plastic pollution in the Anthropocene time. Science of The Total Environment, 668, 1025–1029. https://doi.org/10.1016/j.scitotenv.2019.03.044
- Xu, C., Zhang, B., Gu, C., Shen, C., Yin, S., Aamir, M., & Li, F. (2020). Are we underestimating the sources of microplastic pollution in terrestrial environment? Journal of Hazardous Materials, 400, 123228. https://doi.org/10.1016/j.jhazmat.2020.123228
- Schwarz, A. E., Lensen, S. M. C., Langeveld, E., Parker, L. A., & Urbanus, J. H. (2023). Plastics in the global environment assessed through material flow analysis, degradation and environmental transportation. Science of The Total Environment, 875, 162644. https://doi.org/10.1016/j.scitotenv.2023.162644
- Harris, Sydney, "Toward a standard trash assessment method" (2018). Salish Sea Ecosystem Conference. 332. https://cedar.wwu.edu/ssec/2018ssec/allsessions/332
Acknowledgements
This protocol was created as part of the community engagement plan for the study entitled Tobacco to Tap: Determination of Tobacco Waste in Groundwater, A Major Drinking Water Resource, funded by the California Tobacco-Related Disease Research Grants Program Office of the University of California (Award Number T32DT5235, PI Reynolds), with partial support from the University of California Santa Barbara’s NSF Field-based Undergraduate Engagement through Research, Teaching, and Education (FUERTE) Program (Award Number #1953492, PI Hofmann), and the University of California's Natural Reserve System Office of the President (PI Jerde).