Response of coliform populations in streambed sediment and water column to changes in nutrient concentrations in water.
As sediments increasingly become recognized as reservoirs of indicator and pathogen microorganisms, an understanding of the persistence of indicator organisms becomes important for assessment and predictions of microbial water quality. The objective of this work was to observe the response of water column and sediment coliform populations to the change in nutrient concentrations in the water column. Survival experiments were conducted in flow-through chambers containing sandy sediments. Bovine feces were collected fresh and introduced into sediment. Sixteen days later, the same fecal material was autoclaved and diluted to provide three levels - 1×, 0.5×, and 0.1× of nutrient concentrations - spike in water column. Total coliforms, Escherichia coli, and total aerobic heterotrophic bacterial concentrations were monitored in water and sediment. Bacteria responded to the nutrient spike with initial growth both in the water column and in sediment. The response of bacterial concentrations in water column was nonlinear, with no significant changes at 0.1 and .5× spikes, but a substantial change at 1× spike. Bacteria in sediment responded to the spikes at all added nutrient levels. Coliform inactivation rates both in sediment and in water after the initial growth occurred, were not significantly different from the inactivation rates before spike. These results indicate that introduction of nutrients into the water column results in nonlinear response of E. coli concentrations both in water and in sediments, followed by the inactivation with the same rate as before introduction of nutrients.
Environmental Microbial and Food Safety Laboratory, Beltsville Agricultural Research Center, ARS-USDA, USA.
D R
DR
Shelton
Environmental Microbial and Food Safety Laboratory, Beltsville Agricultural Research Center, ARS-USDA, USA. Electronic address: yakov.pachepsky@ars.usda.gov.
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YA
Pachepsky
BlueWave Microbics, LLC, Columbia, MD, USA.
L A
LA
Kiefer
Environmental Microbial and Food Safety Laboratory, Beltsville Agricultural Research Center, ARS-USDA, USA.
R A
RA
Blaustein
Hydrology and Remote Sensing Laboratory, Beltsville Agricultural Research Center, ARS-USDA, USA.
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GW
McCarty
Environmental Management and Byproduct Utilization Laboratory Beltsville Agricultural Research Center, ARS-USDA, USA.
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TH
Dao
D000818:Animals; D002417:Cattle; D004755:Enterobacteriaceae / Q000187:drug effects* / Q000502:physiology; D005243:Feces / Q000382:microbiology; D019015:Geologic Sediments / Q000382:microbiology*; D010710:Phosphates / Q000737:chemistry / Q000494:pharmacology*; D045483:Rivers / Q000382:microbiology*; D014871:Water Microbiology; D014874:Water Pollutants, Chemical / Q000737:chemistry*
D010710:Phosphates; D014874:Water Pollutants, Chemical
E. coli (all potentially pathogenic types); Environmental/recreational water; Sediment; Water quality