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Fate of Indicator Microorganisms Under Nutrient Management Plan Conditions
Author(s) -
Bradford Scott A.,
Segal Eran
Publication year - 2009
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2008.0428
Subject(s) - microorganism , coliphage , environmental science , fecal coliform , indicator bacteria , wastewater , nutrient , groundwater , indicator organism , environmental engineering , environmental chemistry , water quality , ecology , biology , chemistry , bacteria , escherichia coli , biochemistry , genetics , geotechnical engineering , bacteriophage , gene , engineering
Nutrient management plans (NMPs) for application of wastewater from concentrated animal feeding operations are designed to meet crop water and nutrient requirements, but implicitly assume that pathogenic microorganisms in the wastewater will be retained and die‐off in the root zone. A NMP was implemented on a field plot to test this assumption by monitoring the fate of several fecal indicator microorganisms ( Enterococcus , fecal coliforms, somatic coliphage, and total Escherichia coli ). When well‐water and wastewater were applied to meet measured evapotranspiration (ET), little advective transport of the indicator microorganisms occurred below the root zone and the remaining microorganisms rapidly died‐off (within 1 mo). Additional experiments were conducted in the laboratory to better quantify microorganism transport and survival in the field soil. Batch survival experiments revealed much more rapid die‐off rates for the bacterial indicator microorganisms in native than in sterilized soil, suggesting that biotic factors controlled survival. Saturated column experiments with packed field soil, demonstrated much greater transport potential for somatic coliphage than bacterial indicators ( Enterococcus and total E. coli ) and that the retention rates for the indicator microorganisms were not log‐linear with depth. A worst case transport scenario of ponded infiltration on a large undistributed soil column from the field was also initiated and indicator microorganisms were not detected in the column outflow or in the soil at a depth of 65 cm. All of these observations support the hypothesis that a NMP at this site will protect groundwater supplies from microorganism contamination, especially when applied water and wastewater meet ET.