CHEEC Seed Grants: FY 2002

Cephalosporin Resistant E. coli in Iowa Waterways 
PL Winokur, M.D., Department of Internal Medicine, University of Iowa

The Fate of Metolachlor, Atrazine, and Pendimethalin During Phytoremediation with Prairie Grasses 
JB Belden, TA Phillips, JR Coats, Department of Entomology, Iowa State University

Pollutants of Emerging Concern in Iowa Air 
KC Hornbuckle, Department of Civil and Environmental Engineering, The University of Iowa

Exploratory Studies of Nitroso Compound Formation and Occurrence as a New Class of Disinfectant By-products in Drinking Water and Wastewater 
RL Valentine, Department of Civil and Environmental Engineering, The University of Iowa

Uptake and Metabolism of Acetanilide Herbicides by Hybrid Poplar Trees 
C Just and J Schnoor, Department of Civil and Environmental Engineering, M Wichman and J Vargo, The University Hygienic Laboratory, The University of Iowa

 


Cephalosporin Resistant E. coli in Iowa Waterways 
Investigator: PL Winokur, M.D., Department of Internal Medicine, University of Iowa 
Little is known about the environmental contamination risks associated with agricultural uses of antibiotics or the risks for spread of resistant organisms from agricultural sites to humans. Cephalosporin resistant CMY-2 E. coli have been identified in food animals and humans from Iowa. Preliminary studies suggest that waterborne transfer may play a role in transmission of this resistance. Sixty Iowa surface waterways will be sampled monthly and E. coli expressing CMY-2 will be identified. The associations between upstream agricultural, water treatment or industrial facilities and the effects of rainfall, temperature and stream flow will be analyzed. Sites repeatedly contaminated with CMY-2 E.coli will be intensively studied to pinpoint possible sites of contamination. Candidate contaminating facilities will be identified, and ground water, fecal waste and soil contamination will be analyzed. Studies will utilize microbiology, molecular epidemiology and molecular analyses to understand the epidemiology of CMY-2 E. coli in surface waterways.

The Fate of Metolachlor, Atrazine, and Pendimethalin During Phytoremediation with Prairie Grasses 
Investigators: JB Belden, TA Phillips, JR Coats, Department of Entomology, Iowa State University 
Prairie grasses are currently being used as biofiltration agents in removing pesticides from surface runoff and have been proposed as possible agents useful for phytoremediation of pesticide-contaminated soil. However, little research has been conducted on the fate of herbicides in prairie grass-soil environments. This study proposes to investigate the fate of metolachlor, atrazine, and pendimethalin in soil that has been planted with prairie grasses. Grasses grown in soil fortified with a radiolabeled herbicide will be placed in a sealed acrylic chamber. Volatile organic metabolites and CO2 will be analyzed throughout the experiment. In addition, plant and soil will be analyzed for total radioactivity, parent compounds and major metabolites after a remediation period. The proposed study will enhance our knowledge of the likelihood of the release of herbicides or possible bioactive metabolites back into the environment during and after biofiltration or phytoremediation. Additionally, insight will be obtained into the mechanisms of remediation, including the role of the plant.

Publication:  Belden J, T. Phillips T, Coats J; Effect of prairie grass on the dissipation, movement, and bioavailability of selected herbicides in prepared soil columns. Environ Toxicol Chem. 2004; 23(4):125-132

Pollutants of Emerging Concern in Iowa Air 
Investigator: KC Hornbuckle, Department of Civil and Environmental Engineering, The University of Iowa 
Atmospheric deposition of persistent organic pollutants (POPs) to agricultural crops is an important process in human exposure to POPs through the food chain. In order to quantify potential human exposure to these compounds, atmospheric monitoring is necessary. More than 100 air samples will be analyzed for trace level concentrations of potentially hazardous air pollutants of emerging concern. Analytical methods will be designed and tested for flame retardants, oil additives, current use pesticides, fragrance materials, plasticizers, and veterinary pharmaceuticals at trace levels in ambient air. The results of this study will be used to examine fate and transport of these pollutants in air, deposition and accumulation in crops; and risks to human and animal inhalation and ingestion.

Publication:  Hornbuckle K, Green M; The impact of an urban-industrial region on the magnitude and variability of persistent organic pollutant deposition to Lake Michigan. AMBIO. 2003; 32(6):406-411

Exploratory Studies of Nitroso Compound Formation and Occurrence as a New Class of Disinfectant By-products in Drinking Water and Wastewater 
Investigator: RL Valentine, Department of Civil and Environmental Engineering, The University of Iowa 
Until recently it was believed that the occurrence of nitroso compounds in drinking water and wastewater was due to contamination of the source water. Recent observations indicate that N-nitrosodimethylamine (NDMA), a particularly potent carcinogen, can be produced during water and wastewater treatment. Studies at Iowa have recently elucidated a novel formation pathway that involves reactions of chlorine, ammonia, and dimethylamine that support the hypothesis that NDMA is a new disinfectant by-product (DBP). We propose that NDMA is but one representative of a new class of disinfectant by-products, the nitroso compounds, many of which are of health concern. We hypothesize that other types of nitroso compounds are also formed by a similar mechanism in chlorinated and chloraminated drinking and waster. This project will investigate the formation mechanism and occurrence of several nitroso compounds (not NDMA). This information is important in making comprehensive risk assessments of disinfection practices.                                                                                                                                                                                                                                                                                                                      Publications:   Choi J, Valentine RL. A kinetic model of N-nitrosodimethylamine (NDMS) formation during water chlorination/chloramination. Water Sci Technol. 2002 46(3):65-71 

Choi J, Valentine RL. N-nitrosodimethylamine formation by free-chlorine-enhanced nitrosation of dimethylamine. Environ Sci Technol. 2003 37(21):4871-76.

Choi J, Duirk SE, Valentine RL. Mechanistic studies of N-nitrosodimethlamine (NDMA) formation in chlorinated drinking water. J Environ Monit 2002 4(2):249-52.

Uptake and Metabolism of Acetanilide Herbicides by Hybrid Poplar Trees 
Investigators: C Just and J Schnoor, Department of Civil and Environmental Engineering, M Wichman and J Vargo, The University Hygienic Laboratory, The University of Iowa 
Phytoremediation is the use of vegetation for in-situ treatment of contaminated soils, sediments and groundwater. Hybrid poplar trees have shown the ability to tolerate and metabolize many organic chemicals that have been assimilated into plant tissues through the roots. High-volume acetanilide herbicide use in the Midwest has resulted in both point source and non-point source contamination of shallow groundwater and surface waters. Engineered planting of hybrid poplar trees may be able to intercept and treat herbicide contaminated ground water. Laboratory studies involving hydroponic microcosms and isotopically labeled herbicides will determine plant toxicity and fate pathways for various herbicide mixtures. Mass balances will be completed and the identities of metabolites will be determined using a variety of analytical techniques. The project will test the efficacy of hybrid poplar tree use to remediate contaminated agrichemical facilities.

Publication:  Mezzari M, Walters K, JelÕnkova M, Shih M, Just C and Schnoor J; Gene expression and microscopic analysis of arabidopsis exposed to chloroacetanilide herbicides and explosive compounds: a phytoremediation approach. Plant Physiology. 2005;138(2):858-869