Connecting microbial, nutrient, physiochemical, and land use variables for the evaluation of water quality within mixed use watersheds. (1st July 2022)

• Record Type: Journal Article
• Authors: Flood, Matthew T.; Hernandez-Suarez, J. Sebastian; Nejadhashemi, A. Pouyan; Martin, Sherry L.; Hyndman, David; Rose, Joan B.
• Is Part Of: Water research. Volume 219(2022)
• Publication Date: 2022-07-01
• Subjects: Microbial source tracking -- Watershed -- Land use -- Nutrients -- Fecal pollution -- Streamflow; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2022.118526
• Languages: English
• ISSNs: 0043-1354

Abstract

Highlights: MST markers were driven temporally by precipitation and spatially by land use (eg septic tanks). Spatial clustering of site data allowed for accurate analysis of water quality variables across diverse watersheds. Nutrients were primarily correlated with porcine MST marker. Abstract: As non-point sources of pollution begin to overtake point sources in watersheds, source identification and complicating variables such as rainfall are growing in importance. Microbial source tracking (MST) allows for identification of fecal contamination sources in watersheds; when combined with data on land use and co-occuring variables (e.g., nutrients, sediment runoff) MST can provide a basis for understanding how to effectively remediate water quality. To determine spatial and temporal trends in microbial contamination and correlations between MST and nutrients, water samples ( n = 136) were collected between April 2017 and May of 2018 during eight sampling events from 17 sites in 5 mixed-use watersheds. These samples were analyzed for three MST markers (human – B. theta; bovine – CowM2; porcine – Pig2Bac) along with E. coli, nutrients (nitrogen and phosphorus species), and physiochemical paramaters. These water quality variables were then paired with data on land use, streamflow, precipitation and management practices (e.g., tile drainage, septic tank density, tillage practices) to determine if any significant relationships existed between the observed microbial contamination and these variables. The porcine marker was the only marker that was highly correlated ( p value <0.05) with nitrogen and phosphorus species in multiple clustering schemes. Significant relationships were also identified between MST markers and variables that demonstrated temporal trends driven by precipitation and spatial trends driven by septic tanks and management practices (tillage and drainage) when spatial clustering was employed. Graphical abstract: Image, graphical abstract