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Occurrence And Distribution Of Contaminants In Bottom Sediment And Water Of The Barron River Canal, Big Cypress National Preserve, Florida, October 1998Ronald L. Miller and Benjamin F. Mcpherson RESULTS AND DISCUSSION:
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The range of concentrations for selected organochlorine pesticides in bed sediment from the Barron River Canal and Turner River sites, along with criteria for aquatic life, are given (Table 4). No pesticides were detected in sediment from the Barron River Canal and Turner River sites except for 2 concentrations of p,p-DDE at the two most northern canal sites (1.1 µg/kg south of the Panther Overpass and 3.4 µg/kg south of CR- 858), and one concentration of 1.5 µg/kg of p, p-DDD south of Wagon Wheel Road. Both of these compounds are degradation products of DDT, but DDD is also an insecticide. None of the detected pesticides exceeded aquatic-life criteria.
Although Grabe (1996) found 99 ppb ( µg/kg) of -BHC (a degradation product of lindane which is also called -BHC) in the Barron River Canal near CR-858, we did not detect (at detection limits of 1 - 4 µg/kg) lindane or the and isomers of BHC in any of our Barron River Canal samples collected in October 1998. Pesticides in the bottom sediments of the Barron River Canal were less frequently detected and occurred in lower concentrations than those measured at some other sites is south Florida in 1995-96 as part of the National Water-Quality Assessment Program. Haag and coworkers (1998) show site locations of these unpublished data. Nine pesticide compounds were detected (18 detections including estimated values) in water samples collected October 26-29, 1998, at four sites along the Barron River Canal (Table 5). Thirteen of the 18 detections were at the two northern sites and in most cases pesticide concentrations were highest at the two northern sites. The northern sites are within the citrus and vegetable growing areas near Immokalee. Samples for pesticides in water were also previously collected three times at the Barron River Canal site 1.1 km north of US-41 (Miller et al, 1999), and the following pesticides were detected: atrazine (0.004 µg/L) and propanil (0.006 µg/L) in August 1996; atrazine (0.003 µg/L), simazine (0.003 µg/L), and 2,4-D (0.15 µg/L) in June 1997. In August 1997, no dissolved pesticides were detected at that site. Miller and others (1999) also sampled two BICY sites along the Tamiami Trail that were 23 and 56 km east of the Barron River Canal and detected atrazine, desethylatrazine, tebuthiuron, and azinphosmethyl.
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