This dataset consists of the results from pore water geochemical analyses of sediment cores that were taken during the cruise AL534/2 in March 2020. The research areas were the coastal waters close to major river mounds off the coasts of Spain, Portugal, Belgium, Great Britain, the Netherlands and Germany. During this cruise, samples were collected for the JPI Oceans project HOTMIC. The research objective of HOTMIC is the investigation of distribution and transport of microplastic particles from the European coast to the garbage accumulations in the North Atlantic gyre. Sediment samples were taken with a mini multi corer and, in one case, with a mini box corer. Pore water from sliced cores was extracted with rhizones. Geochemical analyses include the quantification of major anions and cations using inductively coupled plasma atomic emission spectroscopy and ion chromatography, respectively.