ALBERT

Description: Chromophoric dissolved organic matter (CDOM) is the photo-reactive fraction of the marine dissolved organic matter (DOM) pool. Changes in CDOM quality and quantity have impacts on marine microbial dynamics and the underwater light environment. One major source of CDOM is produced by marine bacteria through their alteration of pre-existing DOM substrates. In a series of microcosm experiments in controlled marine conditions, we explored the impact of polystyrene microplastics on the quality and quantity of microbial CDOM, observing an increased production of CDOM with changes in its molecular weight, which resulted from either an increased microbial CDOM production or an enhanced transformation of DOM from lower to higher molecular weight CDOM. This open dataset reports CDOM, bacteria, DOC and oxygen data collected in the series of microcosm experiments recently published. They refer to Experimental Set-up 1 and Experimental Set-up 2 (ES1, ES2). The CDOM data from the blank control experiment are also reported.

Description: These data accompany the perspective paper "Plastic Accumulation in the Sea Surface Microlayer: An Experiment-Based Perspective for Future Studies" authored by L. Galgani and S. A. Loiselle. The data reflect the results obtained from a small pilot laboratory experiment used to support the hypothesis that plastic accumulation in the sea surface microlayer (SML) might have effects on organic matter cycling in the surface ocean. Bacterial abundance, chromophoric dissolved organic matter (CDOM), and oxygen concentrations were measured.

Description: This dataset supports the recent publication "Microplastics increase the marine production of particulate forms of organic matter" by L. Galgani et al (2019) in ERL. It comprises all data presented in the manuscript and Supplementary Information. In the file, Control = mesocosm without plastic addition (1,2,3) and MP = mesocosm with plastic addition (1,2,3). The data proceed from the MESO-Plastic experiment in 2017 conducted at the Hellenic Center for Marine Research, a member of the European Aquacosm network of mesocosm facilities.

Description: The present dataset relates to an experiment studying the impacts of particles on chromophoric dissolved organic matter (CDOM) dynamics by comparing three scenarios: a particle-free environment, a particle-enriched system with polystyrene microplastics, and a particle-enriched system with inorganic particles (water insoluble SiO₂). In experimental part 1 of the experiment, natural marine organic matter was obtained by culturing a non-axenic strain of Chaetoceros socialis in 2 L flasks under each of three scenarios (1C = control, 2PS = polystyrene, 3S = silica). The first dataset reports cell numbers per each 2 L flask for experimental part 1. Subsequently, in experimental part 2, filtered samples from the three flasks containing dissolved organic matter and bacteria were incubated separately in the dark in separate cuvettes (4 replicates per each scenario) for 5 days to monitor changes in dissolved organic matter. In this phase, Chromophoric dissolved organic matter (CDOM), a bulk optical property, was monitored daily to examine changes in its quality and quantity and to compare degradation dynamics in the three systems (1C, 2PS and 3S). The dataset for part 2 reports CDOM absorption coefficient at 355 nm (a355, m^-1^), estimated Dissolved Organic Carbon (DOC, µM), as well as spectral slope parameters in different wavelengths as indicators of CDOM degradation processes and microbial activity: spectral slope Sbetween 302 and 322 nm (S302-322, nm^-1^), between 275 and 295 nm (S275-295, nm^-1^), and between 350 and 400 nm (S350-400, nm^-1^), as well as slope ratio SR, as SR = S275-295:S350-400. At the beginning of experimental part 2 (on day t7), oxygen concentrations were also measured in each cuvette of all of the three scenarios 1C, 2PS and 3S.

Description: The present dataset relates to a study that explored dissolved organic matter dynamics under three scenarios: a particle-free environment, a particle-enriched system with polystyrene microplastics, and a particle-enriched system with inorganic particles (water insoluble SiO₂). In part 1 of the experiment, natural marine organic matter was obtained by culturing a non-axenic strain of Chaetoceros socialis in 2 L flasks under each of three scenarios (1C = control, 2PS = polystyrene, 3S = silica). After the growth phase, filtered samples from the three flasks containing dissolved organic matter and bacteria were incubated separately in the dark in 4 replicates closed quartz cuvettes per treatment (total = 12 cuvettes, 28 mL capacity quartz cuvettes 10 cm path length, Hellma 120-QS, Quartz SUPRASIL, Hellma Analytics) at a temperature of of 20 °C ± 2 °C for 5 days. This dataset reports cell numbers measured by optical density in each of the three culturing flasks, three replicate measurements per flask..

Description: The present dataset relates to a study that explored dissolved organic matter dynamics under three scenarios: a particle-free environment, a particle-enriched system with polystyrene microplastics, and a particle-enriched system with inorganic particles (water insoluble SiO₂). In part 1 of the experiment, natural marine organic matter was obtained by culturing a non-axenic strain of Chaetoceros socialis in 2 L flasks under each of three scenarios (1C = control, 2PS = polystyrene, 3S = silica). Dissolved oxygen concentration was used as a proxy for bacterial activity. Oxygen was measured in each cuvette of all of the three scenarios 1C, 2PS and 3S with a FireSting Oxygen needle-type optical probe and temperature sensor, PyroScience® (Aachen, Germany), at the beginning of part 2 (day 7, t7).

Description: The present dataset relates to a study that explored dissolved organic matter dynamics under three scenarios: a particle-free environment, a particle-enriched system with polystyrene microplastics, and a particle-enriched system with inorganic particles (water insoluble SiO₂). In part 1 of the experiment, natural marine organic matter was obtained by culturing a non-axenic strain of Chaetoceros socialis in 2 L flasks under each of three scenarios (1C = control, 2PS = polystyrene, 3S = silica). After the growth phase, filtered samples from the three flasks containing dissolved organic matter and bacteria were incubated separately in the dark in 4 replicates closed quartz cuvettes per treatment (total = 12 cuvettes, 28 mL capacity quartz cuvettes 10 cm path length, Hellma 120-QS, Quartz SUPRASIL, Hellma Analytics) at a temperature of of 20 °C ± 2 °C for 5 days to monitor changes in CDOM. In this phase, Chromophoric dissolved organic matter (CDOM), a bulk optical property, was monitored daily to examine changes in its quality and quantity and to compare degradation dynamics in the three systems (1C, 2PS and 3S). The dataset for part 2 reports CDOM absorption coefficient at 355 nm (a355, m⁻¹) as well as spectral slope parameters in different wavelengths as indicators of CDOM degradation processes and microbial activity: spectral slope S between 302 and 322 nm (S302-322, nm⁻¹), between 275 and 295 nm (S275-295, nm⁻¹), and between 350 and 400 nm (S350-400, nm⁻¹), as well as slope ratio SR, as SR = S275-295:S350-400.OC was estimated estimated in each cuvette from CDOM absorbance by applying the approach developed by Fichot and Benner (Fichot, C.G.; Benner, R. Geophys. Res. Lett. 2011, 38, doi:10.1029/2010GL046152) using culture specific parameters previously calibrated (Galgani, L. et al., Sci. Rep. 2018, 8, doi:10.1038/s41598-018-32805-4).