title: Microbial contamination and chemical toxicity of the Rio Grande.
abstract: BACKGROUND
  The Rio Grande River is the natural boundary between U.S. and Mexico from El Paso, TX to Brownsville, TX. and is one of the major water resources of the area. Agriculture, farming, maquiladora industry, domestic activities, as well as differences in disposal regulations and enforcement increase the contamination potential of water supplies along the border region. Therefore, continuous and accurate assessment of the quality of water supplies is of paramount importance. The objectives of this study were to monitor water quality of the Rio Grande and to determine if any correlations exist between fecal coliforms, E. coli, chemical toxicity as determined by Botsford's assay, H. pylori presence, and environmental parameters. Seven sites along a 112-Km segment of the Rio Grande from Sunland Park, NM to Fort Hancock, TX were sampled on a monthly basis between January 2000 and December 2002.
  
  
  RESULTS
  The results showed great variability in the number of fecal coliforms, and E. coli on a month-to-month basis. Fecal coliforms ranged between 0-10(6) CFU/100 ml while E. coli ranged between 6 to > 2419 MPN. H. pylori showed positive detection for all the sites at different times. Toxicity ranged between 0 to 94% of inhibition capacity (IC). Since values above 50% are considered to be toxic, most of the sites displayed significant chemical toxicity at different times of the year. No significant correlations were observed between microbial indicators and chemical toxicity.
  
  
  CONCLUSIONS
  The results of the present study indicate that the 112-Km segment of the Rio Grande river from Sunland Park, NM to Fort Hancock, TX exceeds the standards for contact recreation water on a continuous basis. In addition, the presence of chemical toxicity in most sites along the 112-Km segment indicates that water quality is an area of concern for the bi-national region. The presence of H. pylori adds to the potential health hazards of the Rio Grande. Since no significant correlation was observed between the presence of H. pylori antigens and the two indicators of fecal contamination, we can conclude that fecal indicators cannot be used to detect the presence of H. pylori reliably in surface water.
authors.affiliation: Biology Department, El Paso Community College, P,O, Box 20500, El Paso, TX 79998, USA. joseme@epcc.edu
authors.forename: Jose
authors.initials: J
authors.lastname: Mendoza
authors.forename: James
authors.initials: J
authors.lastname: Botsford
authors.forename: Jose
authors.initials: J
authors.lastname: Hernandez
authors.forename: Anna
authors.initials: A
authors.lastname: Montoya
authors.forename: Roswitha
authors.initials: R
authors.lastname: Saenz
authors.forename: Adrian
authors.initials: A
authors.lastname: Valles
authors.forename: Alejandro
authors.initials: A
authors.lastname: Vazquez
authors.forename: Maria
authors.initials: M
authors.lastname: Alvarez
mesh_terms: D004926:Escherichia coli / Q000302:isolation & purification; D016480:Helicobacter pylori / Q000302:isolation & purification; D008800:Mexico; D045483:Rivers / Q000737:chemistry* / Q000382:microbiology*; D014481:United States; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014881:Water Supply
chemical_list: D014874:Water Pollutants, Chemical