blaCTX-M antibiotic resistance genes, fecal indicator organisms, general water characteristics and nutrient concentrations Lahn River

Concentrations of <i>bla</i>_CTX-Mantibiotic resistance genes, fecal indicator organisms <i>Escherichia coli</i>, intestinal enterococci and somatic coliphages as well as general water characteristics and nutrient concentrations were quantified weekly over a 12-month period in Lahn River surface water grab samples at two sampling sites (Nievern and Obernhof). Concentrations of <i>bla</i>_CTX-M antibiotic resistance genes were quantified using quantitative real-time PCR according to Marti et al. (2013). Data of fecal indicator organisms (i.e. <i>Escherichia coli</i>, intestinal enterococci and somatic coliphages), general water characteristics and nutrient concentrations were obtained from Herrig et al. (2015). <i>Escherichia coli</i>, intestinal enterococci and somatic coliphages were quantified according to standard methods ISO 9308-3, ISO 7899-2, and ISO 10705-2. General water characteristics including water temperature, specific conductivity, pH, turbidity, dissolved oxygen and chlorophyll-<i>a</i> were measured in situ with a YSI 6600 V2 multiparameter sensor (YSI, USA). Quantification of nutrient concentrations relied on spectrophotometric measurements (Xion 500, Hach-Lange, Germany) by ready-to-use cuvette tests (Hach-Lange, Germany).