Fig. 4: Scatter plots between log-transformed MP concentrations (log(MP)) and sediment predictors.

Log(MP) versus (a) mud fraction of the clastic sediment and (b) organic-matter content estimated through LOI₅₅₀. Red data points are outer bend samples, blue data points all other samples. Blue dots with a dark gray border are (sandier) inner bend or thalweg samples, those with a light gray border are (muddy) samples from the south bend pool zone or straight section slopes. Linear regressions (blue solid line) through blue datapoints with 2 σ range in blue shading. Linear regressions of previously published datasets in dashed and dotted lines (legend in lower right corner). c Linear regressions through log-transformed corrected environmental MP concentrations (log(ceMP)) for full 1–5000 µm MP size range; for this study (blue solid line) and previously published datasets (gray dashed and dotted lines) in marine and lacustrine environments. Green and red shaded bands indicate zones where grain-size normalized contamination levels are one or more orders of magnitude lower and higher than in this study, respectively. a and b share the same vertical scale; a and c share the same horizontal scale.