The groundwater ubiquity score (GUS) depends on which factors?

The groundwater ubiquity score (GUS) is a metric used to assess the potential for a chemical compound to contaminate groundwater. It combines factors that indicate how readily a chemical might leach through soil and persist in groundwater.

The soil half-life refers to the time it takes for the concentration of a substance in the soil to decrease by half due to processes like degradation or absorption. A longer soil half-life means that a compound is likely to persist longer in the ground, increasing its likelihood of reaching groundwater.

The sorption coefficient is a measure of how well a chemical binds to soil particles compared to how well it remains in solution. A high sorption coefficient suggests that the compound is tightly bound to the soil and is less likely to leach into groundwater, whereas a low sorption coefficient indicates a greater potential for leaching.

By combining these two factors—soil half-life and sorption coefficient—GUS provides insight into both the persistence of a chemical in the soil and its mobility. Hence, the correct answer reflects the key parameters that affect the potential for groundwater contamination by a chemical.