One of the primary goals of the U.S. Geological Survey's National Water Quality Assessment (NAWQA) Program is to determine the occurrence and distribution of contaminants in stream sediments and tissues of aquatic organisms (Crawford and Luoma, 1993). Metals and persistent organic contaminants are of principal concern.
Polycyclic aromatic hydrocarbons (PAHs) are a group of organic compounds that occur abundantly in the environment, are toxic and often carcinogenic to organisms, and could represent a long-term source of contamination. PAHs are metabolized and excreted by most higher vertebrates, particularly fishes, often making assessment of tissues concentrations impossible. Major sources of PAHs are the incomplete combustion of carbonaceous materials and oil spills.
The objectives of this fact sheet are to summarize the occurrence of water-borne PAHs in three urban streams in the Dallas- Fort Worth metropolitan area and to assess the use of semipermeable membrane devices (SPMDs) as PAH samplers. One site on each of three streams was selected for monitoring the occurrence of PAHs (fig. 1). The sites were chosen to reflect varied urban land uses and the influences of point- and nonpointsource pollution. The monitoring was done using SPMDs during a 30-day period in late May and June 1994.
