Progress 01/01/03 to 12/31/03
Outputs
We had two activities under this project in 2003. We continued with visualization of colloids with the same characteristics and size as cryptosporidium. We also re-analyzed the data of Darnault et al presented in this dissertation and developed a model that could describe the movement of C parvum under preferential flow conditions. Since this article will only be published in 2004 in the Vadose Zone Journal the abstract is given below: As a result of Cryptosporidium parvum (C. parvum) in drinking water, several outbreaks of cryptosporidiosis have occurred in the last ten years. Although it is generally believed that movement of pathogens through the soil is minimal, recent research has shown that appreciable numbers of C. parvum oocysts may be transported via preferential or fingered flow to groundwater. The objective of the present research was to further investigate and model the transport of oocysts through preferential flow paths in the vadose zone under a
'worst-case' scenario. This was studied by adding calves feces containing C. parvum oocysts with a chloride (Cl) tracer to undisturbed silt loam columns and disturbed sand columns during a simulated steady state rain. The sand columns exhibited preferential flow in the form of fingers whereas macropore flow occurred in the undisturbed cores. In the columns with fingered flow, oocysts and Cl were transported rapidly with the same velocity through the columns. Although only 14 - 86 percent of the amount applied, the number of oocysts transported across the columns was several orders of magnitude above an infective dose. The macropore columns had only a very limited breakthrough of oocysts, which appeared several pore volumes after the Cl broke through initially. A simulation model for the transport of oocysts via preferential flow was developed on the basis of an existing preferential flow model for non-adsorbing solutes, with addition of a first-order sink term for adsorbance of the C.
parvum to the air/water/solid interfaces, and with velocity and dispersivity parameters derived from Cl transport. The breakthrough of C. parvum oocysts could be described realistically for the sand columns. However, the model could not describe oocyst transport in the columns with macropores.
Impacts
Groundwater is generally considered a safe source of drinking water because pathogens are presumably filtered out during their transport through unsaturated soils. Nevertheless, pathogen-contaminated groundwater has been the cause of many disease outbreaks in the last 10 years including cryptosporidiosis caused by the protozoan pathogen Cryptosporidium parvum. Standard chlorine disinfection is not effective at killing the pathogen.
Publications
- Collick, A. 2003. Evaluation of Solar Calf Housing for the Presence and Survival of Cryptosporidium parvum in the New York City Watershed . M.S. Thesis. Department of Biological and Environmental Engineering. Cornell University
- Darnault, C.J.G., P. Garnier, Y.-J. Kim, K.L. Oveson, T.S. Steenhuis, J.-Y. Parlange, M. Jenkins, W.C. Ghiorse, and P. Baveye. 2003. Preferential Transport of Cryptosporidium Parvum Oocysts in Variably-Saturated Subsurface Environments. Water Env. Res. 75:113-120.
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Progress 01/01/02 to 12/31/02
Outputs
In unsaturated porous media, sorption of bio and other colloids (such as Cryptosporidium Parvum oocysts) at the air-water interface is widely accepted as a mechanism controlling colloid retention and mobilization. However, limited actual pore scale observations of colloid attachment to the air-water interface have been made. To further investigate these processes, a real-time, visualization pore-scale visualization method was developed. The method builds on the light transmission technique for fingered flow studies with packed-sand infiltration chambers and combines it with high-resolution, electro-optical hardware and public-domain imaging software. Infiltration of dark blue latex microspheres showed that colloid sorption further refined the earlier findings of Wan and Wilson and showed that colloid attachment occurred where the air-water and the solid-water interfaces meet. The dissertation listed below has much of the detailed information.
Impacts
These findings will lead to a fundamental understanding about bio colloid movement and retention in unsaturated porous media. Two papers have been submitted for publication.
Publications
- Steenhuis, T.S., Darnault, C.J.G., Crist, J.T., Dittrich, T.M., Lyon, S., Zevi, Y., Gao, B., Peranginangin, N., Taylor, J.C., De Alwis, D., Kim, Y.-J., Marshall, A., Baveye, P.C., Parlange, J.-Y., McCarthy, J.F., and Garnier, P. 2002. Interaction of colloid transport and preferential flow. In: Rhizosphere, Preferential Flow and Bio-availability: A Holistic View of Soil-to-Plant Transfer. Abstracts. Int. Workshop, Centro Stefano Franscini, Monteverita, Ascona, Switzerland. Sept. 21-26, 2002. pp. 128-131.
- Steenhuis, T.S., Crist, J., Zevi, Y., De Alwis, D., Marshall, A., Dittrich, T., Lyon, S., Gao, B., Peranginangin, N., Taylor, J., Baveye, P., Parlange, J.-Y., and McCarthy, J. 2002. Determining (un)certainty in modeling colloid transport by visualization. AGU Fall Meeting. San Francisco, CA. Dec. 6-10, 2002.
- Crist, J. 2002. Pore-scale characterization of colloid transport in the unsaturated zone. Ph.D. dissertation, Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY.
- Crist, J.T., Zevi, Y., Taylor, J., Peranginangin, N., Gao, B., Lyon, S., Dittrich, T., Marshall, A.G., De Alwis, D., Baveye, P.C., Parlange, J.-Y., McCarthy, J.F., and Steenhuis, T.S. 2002. Visualization of colloidal transport in porous media. In: Colloids and Colloid-Facilitated Transport of Contaminants in Soils and Sediments, de Jonge, L.S., Jacobsen, O.H., and Moldrup, P. (Eds.) DIAS Report, Plant Production No. 80:31-38.
- Darnault, C.J.G., DiCarlo, D.A., Bauters, T.W.J., Steenhuis, T.S., Parlange, J.-Y., Montemagno, C.D., and Baveye, P. 2002. Visualization and measurements of multiphase flow in porous media using light transmission and synchrotron x-rays. Ann. NY Acad. Sci. 972:103-110.
- Deinert, M., Parlange, J.-Y., Steenhuis, T.S., Unlu, K., Selker, J., and Cady, K.B. 2002. Real-time measurement of water profiles in a sand using neutron radiography. In: Hydrology Days, Ramirez, J.A. (Ed.) AGU Pub. 22:56-61.
- Parlange, J.-Y., Steenhuis, T.S., Li, L., Barry, D.A. and Stagnitti, F. 2002. Column flow in stratified soils and fingers in hele-shaw cells: A review. In: Environmental Mechanics: Water, Mass and Energy Transfer in the Biosphere, Raats, P.A.C., Smiles, D. and Warrick, A.W. (Eds.) AGU Geophysical Monograph 129:79-85.
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Progress 01/01/01 to 12/31/01
Outputs
Chlorination is ineffective for killing Cryptosporidium parvum oocysts in drinking water and, consequently, outbreaks of Cryptosporidiosis has occurred several times. Although it is generally believed that movement of pathogens in the soil is minimal, recent research has shown that transport of oocysts through preferential or fingered flow to groundwater may occur. The objective was to further investigate and model the transport of Cryptosporidium parvum oocysts through preferential flow paths in the vadose zone under a 'worst-case' scenario. This was studied by adding feces of calves containing Cryptosporidium parvum oocysts with a chloride tracer to undisturbed silt loam columns and disturbed columns filled with sand during a steady state rain. The sand columns exhibited preferential flow in the form of fingers while the undisturbed cores had macropore flow. The fingered flow oocysts and chloride were transported rapidly at the same rate through the columns. The
amount of oocysts transported was on the average only 5 percent of the amount applied. The macropore columns had only a very limited breakthrough of oocysts and this appeared several pore volumes after the chloride broke through. A simulation model for the transport of oocysts was developed using an existing preferential flow model for non adsorbing solutes and adding a first order sink term for absorbance of the Cryptosporidium at the air/water interface. By using the velocity and dispersivity parameters derived from the chloride transport, the Cryptosporidium breakthrough could be described well with realistic values for the adsorption coefficient for the sand columns. Also, with additional funding we have been monitoring the occurrence and survivability of Cryptosporidium on the farm, mainly related to the calves. We will report the results in next year's progress report.
Impacts
Cryptosporidium in drinking water can cause death in immune deficient people. It is a threat in drinking water systems because the chlorine, which is the standard disinfectant, does not kill it. Understanding how Cryptosporidium enters the drinking water system is necessary before effective protective measurements can be taken.
Publications
- Darnault, C.J.G., Garnier, P., Kim, Y.-J., Steenhuis, T.S., Baveye, P., Jenkins, M., and Ghiorse, W.C. 2001. Influence of Gas-Water Interfaces on the Transport and Spatial Distribution of Cryptosporidium Parvum Oocysts in Model Porous Media. Proc. AWWA Annual Conf. and Exposition. Washington, DC. June 17-21, 2001.
- Parlange, J.-Y., Steenhuis, T.S., Li, L., Barry, D.A., and Stagnitt, F. 2001. Fingering as a Possible Mechanism of Efficient Water Transport in a Barkhane. Proc. 41th Annual Conf. of West African College of Surgeons. Nouakchott, Mauritania. Jan. 28-Feb. 4, 2001.
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Progress 01/01/00 to 12/31/00
Outputs
When they contaminate drinking water supplies, oocysts of the protozoan Cryptosporidium parvum, can cause outbreaks of cryptosporidiosis, a common waterborne disease. Among the different pathways by which oocysts can wind up in drinking water, one has received very little attention to date; because soils are often considered to be perfect filters, the transport of oocysts via the subsoil to groundwater is generally ignored. Recent experiments have shown that appreciable numbers of oocysts can migrate in soils in which preferential (finger or macropore) flow occurs, and that, within soils, oocysts seem to have a tendency to accumulate in the upper part of the capillary fringe, presumably because of adsorption at gas-water interfaces. The objective of the present research was to verify the influence of these interfaces in the region above the capillary fringe on the retention and transport of oocysts. Laboratory experiments were carried out with sand columns subjected
to simulated rainfall and at the surface of which the feces of contaminated calves were applied. The approach adopted to investigate the effect of gas-water interfaces was to modify the hydrodynamical conditions in the sand columns by varying the rainfall intensity or by making the sand water-repellent. In a third series of experiments, water-repellent barriers were artificially created at two different depths. Experimental results suggest a close relationship between oocyst retention and the extent of gas-water interfaces; sharp increases in oocyst numbers are consistently observed in regions of the sand where the water content has steep gradients and, therefore, where one expects capillary meniscii to have maximal extent. These observations imply that oocyst transport in the vadose zone is likely to be very limited in the absence of preferential flow. Variability in oocyst recovery rates among the different experiments makes it uncertain, however, to what extent the accumulation of
oocysts at gas-water interfaces is able to compensate for the efficiency of fingers to transport oocysts through the sand columns used in the experiments. In all cases, regardless of experimental conditions, oocyst numbers in the effluents were orders of magnitude higher than regulatory drinking water standards, confirming earlier indications that the transport of oocysts in the subsurface via preferential flow may create a significant risk of groundwater contamination in some situations. The results of the study have been written up and submitted for publication. The publications below deal with fingers in water repellent soils. Fingers form the main pathway in sandy and water-repellent soils
Impacts
Last year, a well at a fair north of Albany, NY on a sand and gravel soil near a river became polluted with pathogens and several people died. Although the official response was that the contamination was caused by water leaking along the well, it is not unlikely that the pathogens were transported through the soil via preferential flow paths from a cattle area near the well. Understanding the exact mechanism of pathogen movement through the soil is, therefore, important.
Publications
- Bauters, T.W.J., T.S. Steenhuis, D.A. DiCarlo, J.L. Nieber, L.W. Dekker, C.J. Ritsema, J.-Y. Parlange, and R. Haverkamp. 2000. Physics of Water Repellent Soils. J. Hydrol. 231-232:233-243.
- Bauters, T.W.J., D.A. DiCarlo, T.S. Steenhuis, and J.-Y. Parlange. 2000. Soil Water Content Dependent Wetting Front Characteristics in Sands. J. Hydrol. 231-232:244-254.
- Christophe J. G. D. 2000. Preferential Flow and Transport of Contaminants Through the Vadose Zone. Ph.D. Dissertation. Department of Agricultural and Biological Engineering. Cornell University. Ithaca, NY
- Nieber, J.L., T.W.J. Bauters, T.S. Steenhuis, and J.-Y. Parlange. 2000. Numerical Simulation of Experimental Gravity-Driven Unstable Flow in Water Repellent Sand. J. Hydrol. 231-232:295-307.
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Progress 01/01/99 to 12/31/99
Outputs
Laboratory experiments were carried out in vertical, 18 to 50 cm-long columns filled with glass beads and two grades of silica sand, under conditions known to foster fingered flow. Other experiments involved undisturbed, macroporous soil cores subjected to lateral flow. Artficial rain was applied. After steady state was reached, feces of contaminated calves were applied at the surface, along with KCl to serve as a tracer, and rainfall was continued at the same rate. The breakthrough of oocysts and Cl-, monitored in the effluent, demonstrate the importance of preferential flow on the transport of oocysts. Peak oocyst concentrations were not appreciably delayed, compared to Cl-, and in some cases, occurred even before the Cl- peak. Recovery rates in drainage water for oocysts ranged from 0.1 to 10.4 percent of the oocysts originally applied on the columns. After dissecting the columns, high oocyst concentrations were consistently observed at the surface and just above
or in the capillary fringe. Oocysts concentration in the drainage water are orders of magnitude higher than the infective dose. The research implies that oocyst transport in the vadose zone is likely to be very limited in the absence of preferential flow.
Impacts
(N/A)
Publications
- Darnault, C.J.G., P. Garnier, T.S. Steenhuis, J.-Y. Parlange, P.C. Baveye, M. Jenkins, and W.C. Ghiorse. 1999. Role of Preferential Flow for the Subsurface Transport of Cryptosporidium Parvum Oocysts Through the Vadose Zone. (Abstract.) 1999 International Symposium on Subsurface Microbiology. Vail, CO. August 22-27, 1999.
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Progress 01/01/98 to 12/31/98
Outputs
Public health problems due to pollution by microorganisms is an important issue in our world today. Microbial contamination of water and soil by land application of manure and other liquid wastes is a potential non-point source of pollution. One of today's most spreading pollution is due to a protozoa, Cryptosporidium parvum. Cryptosporidium parvum is a pathogen which is resistant to chlorination and causes waterborne cryptosporidiosis, a gastrointestinal disease. Cryptosporidium is transported into the environment with water in the form of oocysts. Infected farm animals, as well as domestic and wild animals are the source. Our objective was to assess the risk of contamination of aquifers by Cryptosporidium. It is known that the soil acts as a living filtering membrane with physical, chemical, and biological processes that reduce microbial concentrations. However, preferential flow paths facilitate the transport of the contaminant in the subsurface. The goal of this
research was to study the hydrologic transport of Cryptosporidium through the vadose zone and to analyze the role of preferential flow such as fingering and macropore flow. Laboratory experiments using simulated rainfall on disturbed and undisturbed soil columns were performed to characterize subsurface transport of Cryptosporidium by correlating oocysts concentrations with dissolved constituents. The breakthrough curves and the distribution of the concentration inside the columns of both Cryptosporidium and chloride (a tracer) were compared to evaluate the transport behavior. The viability of the oocysts was also assessed. It was demonstrated that some of the Cryptosporidium can flow rapidly through preferential flow paths (fingering and macropore flow) and may cause contamination of the groundwater and/or surface water.
Impacts
(N/A)
Publications
- No publications reported this period
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Progress 01/01/97 to 12/31/97
Outputs
Cryptosporidium parvum is a pathogen which is resistant to chlorination and causes waterborne cryptosporidiosis, a gastro-intestinal disease. Cryptosporidium is transported in the environment with water in the form of oocysts. Infected farm animals, as well as domestic and wild animals are the source. Our objective was to assess the risk contamination of >aquifers by Cryptosporidium. In particular, the goal of this research was to study the transport and fate of Cryptosporidium through the vadose zone. Laboratory experiments using simulated rainfall at different application rates on disturbed and undisturbed soil columns were performed to characterize subsurface transport of Cryptosporidium by correlating oocysts concentrations with dissolved constituents. The breakthrough curves and the distribution of the concentration inside the columns of both Cryptosporidium and chloride (a tracer) were compared to evaluate the specific transport behavior and to assess the
viability of the oocysts. It was shown that the highest concentration of Cryptosporidium occurred before the chloride peak and that it did not adsorb on the solid particle surfaces. Cryptosporidium can flow rapidly in the soil through preferential flow paths and cause contamination of the groundwater.
Impacts
(N/A)
Publications
- GARNIER, P., C.J.G. DARNAULT, T.S. STEENHUIS, J.-Y. PARLANGE, M. JENKINS, and W.C. GHIORSE. 1998. Role of Preferential Flow in the Transport of Cryptosporidium Parvum Oocysts in the Vadose Zone. (Poster.) AGU Spring Meeting. Boston,
- GARNIER, P., T.S. STEENHUIS, D. DICARLO, J.-Y. PARLANGE, and P. BAVEYE. 1997. Transport of Cryptosporidium Parvum in Different Porous Media. (Poster.) AGU Spring Meeting. Baltimore, MD. May 27-30, 1997.
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