Dynamics of porewater organic carbon in an agricultural soil exposed to two climatic conditions Dissolved organic carbon of the pH 6.3 soil was characterized with LC-FT-ICR-MS at selected time points (days 3, 12, 35, 67). A Weighted average mass over charge (m/z) ratio, (B) weighted average aromaticity index, and (C) corresponding CO2 emissions for the pH 6.3 soil with a low (154 ± 44 µg kg⁻¹ dry soil) and moderate (486 ± 12 µg kg⁻¹ dry soil) Cd content. D Clustering of key molecular features (n = 640) based on standardized mass peak intensities and Euclidian distances. Cluster I (n = 78) contains features of low molecular weight and variable polarity (represented by the RP-LC retention time), Cluster II (n = 230) and III (n = 332) are molecules with higher mass but contrasting polarity and NOSC. E–G Temporal trends of clusters from (D) using summed intensities of key features according to their polarity. In each panel the summed intensities are normalized to 1 for each segment at the first sampling day. Soils were exposed to ambient (430 ppmv CO2 and ambient temperature) and future (800 ppmv CO2 and +4 °C in atmospheric temperature respective to the ambient setup) climatic conditions. Averaged data represents the mean ± standard error of 3 biological replicates or minimum-maximum levels when 2 biological replicates are taken.