FT-ICR MS and environmental data for Tracking Spatiotemporal Variations in Porewater Dissolved Organic Matter in a Planted Mangrove Chronosequence using FT-ICR MS

This study applied a chronosequence approach across four mangrove plantations of different ages (10–18 years) in Thailand to investigate the spatiotemporal variability of DOC concentration and molecular composition using ultrahigh-resolution mass spectrometry (FT-ICR MS).We conducted our study in a mangrove plantation of the Bang Pu Recreation Center, located in the eastern part of Samut Prakan Province, central Thailand (13°31’ N, 100°39’ E). We conducted field sampling in early March 2023 during the dry season at low tide from four sites. These sites were named in ascending order of planting age as follows: Site 1 (10 years), Site 2 (12 years), Site 3 (14 years), and Site 4 (18 years). To account for potential variation in mangrove density and DOM composition along the land–sea gradient, we established sampling transects perpendicular to the shoreline, extending approximately 100 m from the seaward edge of the mangrove forest landward. Duplicate transects at each site were established to address local variability. We collected porewater at −5 (mudflat), 10, 30, 50, 70, and 90 m from the seaward edge (0 m) along duplicate transects at each site at approximately 10~20 m distance. We collected porewater using Rhizon samplers (Rhizon CSS, Rhizosphere Research Products) with a 5 cm porous section, which were inserted vertically into the sediment to span the depth from 5 cm to 10 cm below the surface.We measured environmental factors (salinity, water temperature, pH, and oxidation-reduction potential [ORP]) using portable meters (salinity: LAQUAtwin Salt, HORIBA, Japan; others: HI991003, HANNA, Romania) at a depth of 7.5 cm from the surface. Chemical (DOC, TDN, nutrients, FT-ICR MS) data were obtained as described in the paper. Included data files are:isotopexverifiedxplusxnetworkxmembersx_Bangpu_Sumioka_after_datafiltration_noisotopologue (FT-ICR MS data)env_Bangpu_poreWT (environmental data)