Optimization of colorimetric DET technique for the in situ, two-dimensional measurement of iron(II) distributions in sediment porewaters

► An optimized DET method for measuring iron(II) in sediment porewaters is reported. ► Colorimetric analysis allows 2D distributions to be represented at 1 mm2 resolution. ► The measurement range is 4.1-2000 μmol L−1 iron(II).