ORGANIC CONTAMINANTS IN WINYAH BAY, SOUTH-CAROLINA .1. PESTICIDES AND POLYCYCLIC AROMATIC-HYDROCARBONS IN SUBSURFACE AND MICROLAYER WATERS

The surface microlayer (top less-than-or-equal-to 1 mm of the water's surface) is a potential site of enrichment of hydrophobic organic compounds. Concentrations of pesticides and polycyclic aromatic hydrocarbons (PAHs) were assessed in the microlayer and subsurface waters of Winyah Bay and North Inlet, South Carolina. Microlayer samples were collected using a screen method every two months during 1990 at seven stations and analyzed using gas chromatography-mass spectrometry or electron-capture detection. Six pesticides were detected, simazine, atrazine, alachlor, malathion, alpha- and gamma-hexachlorocyclohexane. Of these, atrazine had the highest concentration, ranging up to 890 ng/liter in May 1990, and it was found throughout the year in Winyah Bay. Total PAH levels were generally in the nanogram per liter range, but were up to 2.9 mug/liter for one microlayer sample collected adjacent to urban Georgetown, SC. The dominant PAHs in both subsurface and microlayer samples were fluoranthene and pyrene. Pesticides found in this study did not greatly enrich in the microlayer. PAHs did concentrate in the microlayer, with an average of 18 times more total PAH than in subsurface samples.