2007 Annual Report
Physical and Chemical Nonequilibrium Models for Colloid Transport: Colloid transport in natural subsurface environments is subject to a myriad of nonequilibrium processes, including chemical and physical nonequilibrium transport. To date coupled physical and chemical nonequilibrium models have not been used to study colloid transport, retention, and/or mobilization. Researchers for the USDA-ARS Salinity Laboratory and the University of California Riverside have developed an analytical model that considers equilibrium and kinetic retention of colloids in both “mobile” and “immobile” regions of the pore space. A sensitivity analysis was performed to study the influence of model parameters on the shape of the effluent concentration curve and the colloid deposition profile for colloids in a hypothetical porous medium, and this model was used to characterize representative colloid transport data that have appeared in the literature. This model and study provided useful information to better understand the coupled physical and chemical mechanisms of colloid retention in porous media. This research addresses NP-206 (Manure and Byproduct Utilization) components V.1 (Methods Assessment and Development), V.2 (Fate and Transport of Pathogens), and V.4 (Holistic Treatment Technologies for Nutrients, Pathogens and PACs).
Detection, quantification and characterization of pathogen survival in two contrasting soils: Survival of E. coli O157:H7 was greater in sandy soil than in clay soil during the first few weeks, but during a long term laboratory microcosm experiment (90 d) survival was higher in the clay soil. Survival of Escherichia coli O157:H7 in the environment is a major concern to growers and to the safety of fresh produce. Real-time polymerase chain reaction (PCR) and plate counts were used to quantify the survival of E. coli O157:H7 in two contrasting soils after fumigation with methyl bromide and methyl iodide during a 90 day experiment conducted by scientists at the USDA-U.S. Salinity Lab, Riverside, CA. This study showed that Escherichia coli O157:H7 can survive in soil for a long time and care must be taken to eliminate any potential sources of the pathogen coming in contact with field used for the growing of leafy greens. This research addresses NP-206 (Manure and Byproduct Utilization) components V.1 (Methods Assessment and Development), V.2 (Fate and Transport of Pathogens), and V.4 (Holistic Treatment Technologies for Nutrients, Pathogens and PACs).
Sources of nonpoint fecal pollution at the Santa Ana River Watershed by bacterial source tracking: The prevalence of pathogens associated with different sources of fecal pollution was determined in a 12-month study. Field studies were undertaken by scientists at the USDA-U.S. Salinity Lab in collaboration with scientists at the Orange County Water District to quantify the main sources of fecal pollution to Santa Ana River using specific gene markers. Results from this study showed that the Middle Santa Ana River watershed is affected by multiple sources of non-point microbial pollution and microbial contaminants may be reduced by implementation of different management strategies such as sub-surface constructed wetland to improve water quality from the source or surface flow constructed wetland to treat surface water from creeks. The overall long term impact of this project is the general improvement of ground and surface water quality within the middle Santa Ana River watershed. This research addresses NP-206 (Manure and Byproduct Utilization) components V.1 (Methods Assessment and Development), V.2 (Fate and Transport of Pathogens), and V.4 (Holistic Treatment Technologies for Nutrients, Pathogens and PACs).
This research is a component of ARS National Program 206 – Manure and ByProduct Utilization. The mission of NP 206 is to develop cost-effective management practices, technologies and decision aids that will allow producers to capture the value of manure and other byproducts without degrading environmental quality or posing a threat to human and animal health. Our research addresses the pathogen component of this program: Pathogens and pharmaceutically active compounds in manure can be transmitted to other animals and humans through food supplies and water. Production of fresh fruit and vegetables using manure or irrigating with wastewater could be mechanisms of pathogen transfer. Research is needed to determine survival, transport, and dissemination of manure pathogens and pharmaceutically active compounds in the environment to assess risks to human and animal health and to develop appropriate control measures. Methods for sensitive detection and accurate quantification of pathogens and pharmaceuticals in complex matrices such as manure and soil will be needed. This research addresses NP-206 (Manure and Byproduct Utilization) components V.1 (Methods Assessment and Development), V.2 (Fate and Transport of Pathogens), and V.4 (Holistic Treatment Technologies for Nutrients, Pathogens and PACs).
Bradford, S.A., Tadassa, Y.F., Jin, Y. 2006. Transport of coliphage in the presence and absence of manure suspension. Environmental Science and Technology. VOL 35:1692-1701
Bradford, S.A., Simunek, J., Bettahar, M., Van Genuchten, M.T., Yates, S.R. 2006. Significance of straining in colloid deposition: evidence and implications. Water Resources Research. VOL 42, W12S15
Bradford, S.A., Simunek, J., Walker, S.L. 2006. Transport and straining of E. coli O157:H7 in saturated porous media. Water Resources Research. VOL 42, W12S12
Bradford, S.A., Torkzaban2, S., Walker, S.L. 2007. Coupling of physical and chemical mechanisms of colloid straining in saturated porous media. Water Resources Research. Vol 41:3012-3024
Bradford, S.A., Toride, N. 2007. A stochastic model for colloid transport and deposition. Journal of Environmental Quality. Vol 36:1346-1356
Gargiulo, G., Bradford, S.A., Simunek, J., Vereecken, H., Klumpp, E. 2007. Transport and deposition of metabolically active and stationary phase deinococcus radiodurans in unsaturated porous media. Environmental Science and Technology. Vol 41:1265-1271
Gargiulo, G., Bradford, S.A., Simunek, J., Ustohal, P., Vereecken, H., Klumpp, E. 2007. Bacteria transport and deposition under unsaturated conditions: the role of the matrix grain size and the bacteria surface protein. Journal of Contaminant Hydrology. Vol 92:255-273
Ibekwe, A.M., Lyon, S.R., Leddy, M., Jacobson-Meyers, M. 2007. Impact of plant density and microbial composition on water quality from a free water surface constructed wetland. Journal of Applied Microbiology. 102:921-936
Ibekwe, A.M., Lyon, S.R. 2007. Microbial characteristics through drinking water aquifer sand material. Engineering in Life Sciences. 1:81-89
Pachepsky, Y.A., Sadeghi, A.M., Bradford, S.A., Shelton, D.R., Guber, A.K., Dao, T.H. 2006. Transport and fate of manure-borne pathogens: modeling perspective. Agricultural Water Management. Online-(doi:10.1016/j.agwat.2006.06.0l0.)
Simunek, J., He, C., Pang, L., Bradford, S.A. 2006. Colloid-facilitated solute transport in variably-saturated porous media: numerical model and experimental verification. Vadose Zone Journal. Vol 5:1035-1047
Wang, Q., Bradford, S.A., Zheng, W., Yates, S.R. 2006. Sulfadimethoxine degradation kinetics in manure as affected by initial concentration, moisture, and temperature. Journal of Environmental Quality. Vol 35:2162-2169
Yang, S., Zhang, Q., Chorkowski, A.O., Glick, B.R., Ibekwe, A.M., Cooksey, D.A., Yang, C.H. 2007. Global effect of indole-3-acetic acid biosynthesis on multiple virulence factors of erwinia chrysanthemi 3937. Applied and Environmental Microbiology. Feb 2007: 1079-1088
Ibekwe, A.M., Shouse, P.J., Grieve, C.M. 2006. Quantification of survival of Escherichia Coli 0157:H7 on Plants affected by Contaminated Irrigation Water. Engineering in Life Sciences. Vol. 6:566-572
Ibekwe, A.M., Grieve, C.M., Yang, C. 2007. Survival of Escherichia Coli O157:H7 in soil and on lettuce after fumigation. Canadian Journal of Microbiology. Vol. 53:623-635