Supplementary Materials: Plastic in the Urban Freshwater Environment

An Exploratory Study of Microplastics in the Upper Oconee Watershed via Community-Based Efforts

1 Documentation for Supplementary Files

Code and data files required to reproduce this analysis are available on GitHub

• “AmeliaFoley-MADA-project.Rproj” Establishes relative file paths
• “README.md” Provides brief order of scripts for reproducing; summarizes project parts
• “code” folder contains all code for processing and analysis
  • “analysis_code”
    • analysis.Rmd performs linear regression on single predictors and full predictor sets
    • exploration.Rmd contains the exploratory data analysis
    • land_model.Rmd contains statistical models on land cover data
    • modeling.Rmd is the main analysis file containing final models (LASSO)
    • subset_modeling.Rmd is an additional analysis file performing models on subsets of data; it is not used for the manuscript
  • “processing_code”
    • processing_code.Rmd is the master script for all processing. It combines all of the scripts from below, which have been moved to the ARCHIVE folder.
      • censusland_code.Rmd combines land cover data with microplastic data
      • censusprocessing.Rmd imports census tract population data
      • mpprocessing.R processes the original microplastic data file and saves cleaned data
      • uownprocessing.Rmd imports additional water quality data from UOWN.org
      • wrfprocessing.Rmd imports distance for nearest water reclamation facility
    • map_images.Rmd combines individual map images to produce a grid
  • “readme.md” provides an order and brief description of dependencies/outputs for processing code files
• “data” folder contains all raw and processed data
• “products” folder contains files to produce the Manuscript and Supplement
  • “manuscript” contains files for producing the manuscript
    • apa.csl optional format for citations
    • elsevier.csl optional format for citations
    • library.bib contains references
    • Manuscript.docx result of knitting the markdown
    • Manuscript.Rmd creates basic manuscript word document
    • style_template.docx placeholder to add special formatting to manuscript
    • Supplement.Rmd creates basic supplemental material word document
    • Supplement.docx result of knitting markdown file
• “results” folder contains all plots, tables, figures produced in data analysis

2 Reproducing results

Reproducing this project requires R, RStudio, and Microsoft Word. Files should be run in the following order.

In the code > processing_code folder:

1. processing_code.Rmd

In the code > analysis_code folder:

2. analysis.Rmd
3. modeling.Rmd
4. land_model.Rmd

In the code > processing_code folder:

5. map_images.Rmd

In the products folder

6. Manuscript.Rmd
7. Supplement.Rmd

3 Supplementary results

3.0.1 Distribution of Microplastic Concentration

Figure 3.1 shows a histogram of microplastic concentration observations. The minimum concentration is 16.67 particles/L and the maximum is 1193.33 particles/L. The mean concentration is 104.39 particles/L, and the median is 66.67 particles/L.

Figure 3.1: Distribution of Microplastic Concentration

Microplastic concentrations remained in similar ranges throughout the study period. Figure 3.2 shows a boxplot of concentrations by sample date.

Figure 3.2: Particles/L by Sample Date

There is some seasonal variation in concentration at each individual site. Figure 3.3 shows a plot of concentrations at each site.