CSTAP: An Event-Conditioned Protocol for Toxicological Activation Potential in Coastal Sediments

Coastal sediments can store contaminants for decades and become exposure sources when disturbance alters partitioning, transport, or biological contact. We propose the Coastal Sediment Toxicological Activation Protocol (CSTAP), a theoretical and empirically testable protocol for organizing event-conditioned toxicological activation potential in coastal sediments. The associated Coastal Sediment Toxicological Activation Index (CSTAI) is an exploratory, semi-quantitative score intended for hypothesis generation and future calibration, not a validated toxicity endpoint or regulatory threshold. The CSTAP separates chemical burden, effective bioavailability, mixture pressure, event activation, receptor vulnerability, evidence adequacy, uncertainty priority, and procedural integrity. The primary score alone assigns the exploratory class, whereas evidence adequacy, uncertainty priority, and forensic readiness qualify interpretation without changing the class. The protocol includes benchmark selection, information-source safeguards against double counting, route-resolved receptor weighting, event and mass-conservation checks, data-tier declarations, and validation logic. Limiting-case tests, a reproducible worked example, and illustrative Mediterranean case encodings show internal coherence and reporting structure. The CSTAP is intended to guide monitoring design, scenario comparison, and calibration with paired chemistry, exposure, bioassay, and ecological-effect datasets.