1. Dieldrin in Cyprinus Carpio from the Des Moines River: 1977-2003 The Des Moines River Water Quality Network (DMRWQN) is a long-term monitoring project sponsored by the Rock Island District COE and performed by ISU’s Department of Civil, Construction & Environmental Engineering. For more information visit http://www.cce.iastate.eduhttp://www.cce.iastate.edu METHODS Sampling Protocol Annual collections in May, June or July Target age class III Cyprinus carpio Fish length 312-351 mm 2 subsamples of 5 fish each per sample Smallest fish >75% of largest Std deviation of fish lengths <10% mean length Difference in fish lengths between subsamples <10% of mean Analytical Methods Grind, homogenize sample Extract with petroleum ether, concentrate Partition w/ acetonitrile, cleanup w/ Florisil, reconcentrate Analyze w/ gas chromatograph w/ electron capture detector Results on wet weight basis % fat (lipid)-gravimetric INTRODUCTION Dieldrin concentrations have been measured over a span of 26 years in common carp (Cyprinus carpio) from the Des Moines River below two reservoirs. Saylorville Reservoir is located 11 miles upstream from the city of Des Moines while Red Rock Reservoir is located 60 miles downstream. The Des Moines River watershed is primarily agricultural– corn and soybean cropland. RESULTS Uniformity of fish  Std deviation of sample fish lengths ranged from 3% to 5% of mean  Condition factor= weight(g)x10 5 / Length(mm) 3  Ave fillet fish condition factors: Saylorville1.23; Red Rock 1.29  Ave whole fish condition factors: Saylorville 1.26; Red Rock 1.30  Ave % fat in fillets: Saylorville 0.8%, Red Rock 0.9%  Ave % fat in whole fish: Saylorville 4.0%, Red Rock 3.7% Statistical Analysis Time Trends  Sen’s Slope  no time trend in whole fish data  significant (P=0.05) downward trend in fillet concentrations  Saylorville fillet concentration –0.77 ppb/yr  Red Rock fillet concentration –0.69 ppb/yr Parameter interaction: Dieldrin vs. Fish length, % fat, River Flow, Annual Precipitation Correlation  Correlation most significant for fillets: dieldrin vs % fat (0.65)  Correlation most significant whole fish: dieldrin vs precip (0.40) Linear Regression  Dieldrin vs % fat: Fillets r 2 =0.43  Dieldrin vs precipitation: Whole Fish: r 2 =0.16 Quick Facts on Aldrin & Dieldrin Aldrin (C 12 H 8 Cl 6 ) and Dieldrin (C 12 H 8 Cl 6 O) Organochlorine insecticides Persistent, Bioaccumulative and Toxic (PBT) pollutants Use History Agricultural use: Corn and cotton crops Prophylactic use and timber treatment for termites Early 1950s until 1989 when manufacture in US discontinued Peak use in 1966 Food crop use cancelled 1974 Last registered use termiticide, cancelled 1987-1989 Environmental Profile Aldrin converts rapidly to dieldrin by microsomal oxidation reaction Half-life of dieldrin in temperate soils, 5 years Solubility 0.01-0.11 mg/L, very soluble in organic solvents Partition Coefficients: Kow 6.2-6.5 (high potential for bioaccumulation) Koc 6.7-7.7 (immobile in soil) BCF aldrin - 3,140 in fish, 44,600 in snails; dieldrin 2,700 in fish, 61,657 in snails Aquatic LC 50 aldrin 1.3-89 ug/L, dieldrin 0.5-330 ug/L EPA RfD aldrin 3x10 -5, dieldrin 5x10 -5 mg/kg/day Water quality criteria dieldrin freshwater 0.24 ug/L, saltwater 0.71 ug/L human health water and organism, and organism only, both 1.4x10 -4 ug/L Fish Tissue Criteria FDA action level – aldrin + dieldrin cannot exceed 300 ppb EPA screening value – 2.5-3.07 ppb (recreational-subsistence fishers) Great Lakes WQ Agreement – 2.5 ppb DISCUSSION Note: 1993 fish were collected during high flow but before the record-breaking floods of 1993 Fillet Fish Data  Highest fillet conc. seen in 1977, then declined sharply until 1987, after which they leveled off  Fillet concentrations below Saylorville Dam (more urban) were higher than below Red Rock Dam  In general, concentrations are low, fillet conc. well below FDA action level  However, not until after 1993 were fillet conc. below EPA screening value for recreational fishers  In fillet samples after 1990, the variations in % fat, despite the uniformness of samples, attributed to variations in dieldrin concentrations Whole Fish Data  Trends are easier to distinguish in fillet vs whole fish samples because the %fat in whole fish varied more  Dieldrin in whole fish below Sayl Dam have been below 10 ppb since 1997  Dieldrin in whole fish below RR Dam have been more variable  Below RR Dam peaks in 1991 and 1998 were not explained by %fat data Dieldrin vs Annual Precipitation Significant Trends Dieldrin vs % Fat Data Summary