Fig 4. Extraction efficiency for different extraction procedures.

Experimental extraction efficiencies of polystyrene beads for different extraction procedures. (a) No H₂O₂ digestion, beads were extracted from soil with H₂O only (no biosolids could be extracted). Extraction efficiencies of control samples without beads were less than 0.5% (Table E in S1 Appendix). The no-soil treatment is extraction from beads in water only, without soil. (b) Beads extracted from water only with and without H₂O₂ digestion for 7 days. Note, the dark blue columns in (a) and (b) are the same data. Data represent mean and error bars are ± one standard deviation. Lowercase letters show the differences of extraction efficiencies among different size beads.