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DETERMINING HOT SPOTS OF FECAL CONTAMINATION IN A TROPICAL WATERSHED BY COMBINING LAND-USE INFORMATION AND METEOROLOGICAL DATA WITH SOURCE-SPECIFIC ASSAYS
Jent, J. R., H. Ryu, C. Toledo-Hernandez, J. Santo Domingo, AND L. Yeghiazarian. DETERMINING HOT SPOTS OF FECAL CONTAMINATION IN A TROPICAL WATERSHED BY COMBINING LAND-USE INFORMATION AND METEOROLOGICAL DATA WITH SOURCE-SPECIFIC ASSAYS. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 47(11):5794-5802, (2013).
Microbial source tracking (MST) assays have been mostly employed in temperate climates. However, their value as monitoring tools in tropical and subtropical regions is unknown since the geographic and temporal stability of the assays has not been extensively tested. The objective of this study is to map the hot spots, i.e. areas and hosts that are likely sources of fecal contamination of surface water, by combining knowledge of environmental, geomorphologic and anthropologic factors in the Río Grande de Arecibo (RGA) watershed in Puerto Rico with information provided by MST. We evaluated the use of several MST assays for the identification of primary sources of pollution in a Puerto Rico watershed by combining marker detection with information on several hydrological and land-use variables. Water samples were tested for the presence of human and bovine markers in addition to fecal indicator bacteria, and correlated against several land uses and the density of septic tanks, sewers, and latrines. Specifically, human sources were positively correlated with developed and barren land uses, the density of septic tanks, and the proximity to WWTPs. Agricultural land, the number of upstream NPDES facilities, and density of latrines were positively associated with the bovine marker. Using this information we provide hot spot maps that show areas that should be closely monitored for fecal contamination. The results indicate that additional bovine assays may be needed to better track such sources in tropical regions. Moreover, landscape data is needed to better predict the performance of MST markers and therefore identify the importance of fecal sources in environmental waters.
The objective of this study was to couple landscape information with the occurrence of MST markers in a tropical watershed. This approach has never been used in tropical watersheds and we show that is useful at identifying hot spots associated with human and cattle fecal pollution.
Record Details:Record Type: DOCUMENT (JOURNAL/PEER REVIEWED JOURNAL)
Organization:U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
NATIONAL RISK MANAGEMENT RESEARCH LABORATORY
WATER SUPPLY AND WATER RESOURCES DIVISION
MICROBIAL CONTAMINANTS CONTROL BRANCH