Sediment Quality Guideline

A sediment quality guideline (SQG) is a numerical threshold for a contaminant in marine or estuarine sediment used to judge the risk of adverse effects on bottom-dwelling organisms. The empirical North American framework pairs a threshold effects level (TEL) or effects range-low (ERL), below which effects are rarely observed, with a probable effects level (PEL) or effects range-median (ERM), above which effects are expected; concentrations between them carry intermediate risk. Guidelines cover metals (lead, mercury, cadmium), PAHs, PCBs, and organotins. They screen dredged-material disposal decisions under the London Convention and Protocol and rank contaminated sites for monitoring. SQGs are screening tools, not pass-fail standards.