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United States Department of Agriculture

Agricultural Research Service

Research Project: REUSE OF TREATED MUNICIPAL WASTE WATER FOR IRRIGATION Title: Presence and Transport of Escherichia Coli and Salmonella Spp. in Soils of a Municipal Park Irrigated with Reclaimed Wastewater

Authors
item McLain, Jean
item Rock, Channah
item Williams, Clinton

Submitted to: Southwest Hydrology
Publication Type: Abstract Only
Publication Acceptance Date: January 11, 2007
Publication Date: N/A

Technical Abstract: Increasing demands on limited water resources have made wastewater reclamation for municipal irrigation an attractive option for extending available water supplies. However, there remain public health concerns about the potential risks of human contact with irrigated turf areas. We are monitoring soil and water quality in a municipal city park in Maricopa, Arizona, where turf has been irrigated with reclaimed water since the opening of the park in September 2006. Sampling of the soil and irrigation water allows us to identify the biological changes in irrigated areas that are directly related to the reclaimed water quality. The presence and transport of E. coli and Salmonella in soils and irrigation water are being monitored using Quantitative Real-Time PCR (Q-PCR). Over the first six months of the study, the presence of Salmonella in the irrigation water was correlated (r = 0.78) to air temperature, decreasing from 380 CFU mL -1 in September to 150 CFU mL-1 in December. During the same time period, Salmonella increased from 14 CFU g-1 to nearly 600 CFU g-1 in surface soils (0-5 cm) and increased in deeper soils (10+ cm) from 1 CFU g-1 to 130 CFU g-1. This may indicate that Salmonella are surviving in soil after application, and that some bacterial transport downward in the soils may be occurring. Q-PCR and Bacteroides-specific primers are being used to both quantify and differentiate sources of bacteria (human vs. bovine vs. other) in the irrigation water and soils. By identifying the sources of bacteria and the environmental factors controlling E. coli and Salmonella survival and transport within the parkland, this work will reveal potential impacts, including ecological benefits, of using reclaimed water for municipal irrigation.

Last Modified: 10/22/2014
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