Dioxin in Storm-Water Runoff in Houston, Texas.

Concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans in runoff were measured at 10 small flood control drainage channels in the Houston area. Total toxicity equivalent concentrations in runoff ranged from 0.01 to 0.11 pg/L for the dissolved phase and from 0.02 to 0.88 pg/L for the suspended phase. The dissolved concentrations were lower than their respective suspended concentrations, with average suspended/dissolved ratios between 5 and 152 for individual congeners. Average observed logs of organic-carbon (OC)-normalized suspended sediment-dissolved partitioning coefficients (log K_OC) varied between 5.47 and 7.83 L/kg OC. Dioxin concentrations in runoff were generally at the same level or lower than those measured in the receiving water body. Principal component analyses indicated that the signatures for dissolved runoff match those observed in dissolved ambient water in the channel, while the suspended-sediment runoff signatures are similar to those observed in dry air deposition in the Houston area. [ABSTRACT FROM AUTHOR]