PFAS Reach Bracketing Tool

Machine-readable reach experiment analysis with multiple imputation — runs entirely in your browser

Contact: Dr. Gehendra Kharel (g.kharel@tcu.edu) · Texas Christian University
© 2025–2026 Dr. Gehendra Kharel. All rights reserved.
PFAS Results CSV Required
One row per analyte per sample. Contains measured concentration, detection status, and reporting limit for each PFAS compound at each site/campaign.
Columns: site_id, campaign, analyte_std, result_value, detect_flag, rl
⬇ CSV template
Sites Metadata CSV Optional
One row per site. Adds coordinates for the map, reach groupings, and bracket roles (upstream, tributary, downstream). Auto-detected from PFAS file if omitted.
Required: Site ID | Optional: Lat, Lon, Reach_group, Bracket_role
⬇ CSV template
Reach Experiment CSV Optional
One row per bracketing experiment. Defines upstream/tributary/downstream sites. Use pipe "|" for multiple sites. Enables ΔΣPFAS contrasts and mixing fractions.
Columns: experiment_id, experiment_type, downstream_site, upstream_sites, tributary_sites, all_sites
⬇ CSV template
Upload PFAS CSV (minimum) or click "Run with demo data"
© 2025–2026 Dr. Gehendra Kharel, Texas Christian University. All rights reserved.
PFAS Reach Bracketing Tool · g.kharel@tcu.edu · All computation runs locally in your browser — no data is uploaded anywhere.
References & Methodological Citations
[1] Helsel, D.R. (2012) Statistics for Censored Environmental Data Using Minitab and R, 2nd ed. John Wiley & Sons. — Foundation for censored data methods (MI, substitution, distributional approaches).
[2] Rubin, D.B. (1987) Multiple Imputation for Nonresponse in Surveys. John Wiley & Sons. — Theoretical basis for MI framework.
[3] Lubin, J.H. et al. (2004) Epidemiologic quantification of exposure to environmental pollutants with left-censored data. Environ. Health Perspect. 112(17), 1691–1696. — MI for left-censored environmental data.
[4] Helsel, D.R. (2006) Fabricating data: How substituting values for nondetects can ruin results. Chemosphere 65(11), 2434–2439. — Limitations of RL/2 and other substitution methods.
[5] Antweiler, R.C. & Taylor, H.E. (2008) Evaluation of statistical treatments of left-censored environmental data. Environ. Sci. Technol. 42(10), 3732–3738. — Comparison of censoring methods for water quality data.
[6] US EPA (2024) Method 1633: Analysis of per- and polyfluoroalkyl substances (PFAS) in aqueous, solid, biosolids, and tissue samples by LC-MS/MS. EPA-821-R-24-002.
[7] Spearman, C. (1904) The proof and measurement of association between two things. Am. J. Psychol. 15(1), 72–101. — Rank correlation used in MI vs RL/2 sensitivity.
[8] Woodward, D.S. et al. (2024) Time-of-travel synoptic survey with concurrent streamflow measurement for PFAS stream loading. ACS ES&T Water 4(10), 4356–4367. — Synoptic PFAS loading methodology.