Aggregation of marine organic matter by bubbling

Dissolved organic matter (DOM) can be partially converted into particulate organic matter via aggregation. Although surface coagulation by bubbles is known to be an aggregation process, a few studies have tested its efficacy for aggregating natural DOM. In the research described here, we tested surface coagulation by bubbles using natural seawater collected from different locations, and achieved organic matter aggregation (OC agg ) at the concentrations up to 0.619 μM. In addition, the test using seawater enriched with nutrient showed that OC agg was 0.559 μM. We also evaluated aggregation in mesocosm through 40 days. The OC agg concentrations increased after nutrient depletion (0.858–1.34 μM), and the OC agg /DOC ratio reached its maximum on day 18 (1.24 ± 0.19%).