Microplastic Biofilms Seed Marine Cloud Nuclei, Amplifying Regional Albedo Beyond Model Projections

Independent variable: Concentration of microplastic-associated biofilms (plastisphere) in ocean surface microlayer samples.

Dependent variable: Cloud condensation nuclei (CCN) density measured at 0.2% supersaturation above high-plastisphere ocean regions versus low-plastisphere controls.

Prediction: Plastisphere communities produce dimethyl sulfide (DMS) and isoprene at 3-8× the rate of equivalent free-living bacterioplankton assemblages. This excess volatile organic compound flux generates measurable CCN enrichment (>15% above baseline) in the marine boundary layer, producing a regional albedo forcing of −0.3 to −0.8 W/m² not captured in CMIP6 aerosol-cloud interaction parameterizations.

Falsification: If paired ship-transect measurements across plastic accumulation zone boundaries show <5% CCN difference after controlling for phytoplankton biomass and sea-surface temperature, the biofilm-CCN pathway is negligible.

What existing DMS flux datasets from subtropical gyres show the strongest signal here?