Abstract
Increasing pollution levels in waters from remote mountain areas in northern Sweden have been observed. To support a sustainable water quality management, it is necessary to know which environmental and antrophogenic factors influence the water quality. The purpose of this study was to map the Escherichia coli prevalence in the catchment area of the upper part of a large northern Scandinavian river and investigate the controlling factors of microbial contamination. A total of 112 water samples were collected from various locations in the research area between July 2020 and December 2020. These samples were analyzed for microbial and chemical characteristics, and information about tourism and reindeer herding was compiled. Additionally, microbial and physicochemical water characteristics collected by Indalsälven Water Conservation Association (IWCA, 1993–2020) and Swedish Meteorological and Hydrological Institute (SMHI, 2004–2020) were analyzed. The results showed that E. coli enumerations ranged between 0 and 500 CFU/100 ml. There was generally no obvious relation between suspected point sources, e.g., sewage treatment plants at mountain stations, and E. coli levels at downstream sampling points. Principal component analysis showed that E. coli was correlated to coliforms, total heterotrophic count, river discharge, CODMn and river color. Since microbial analyses are time-consuming, expensive and difficult to perform in remote areas, it is important to find more easily extracted water parameters that can serve as a proxy for E. coli. In particular, river color and discharge are promising parameters that may serve as an early indication of bacterial outbreak and fecal contamination in mountain waters.
Highlights
An important factor to maintain healthy ecosystems is water quality
The naturally oligotrophic rivers in northern supported by the Knowledge Foundation (Sweden) are generally characterized by a low pollution level (SLU, 2021; van Dijk et al, 1994), and the water quality, in remote parts of the catchment areas, may still meet national standards (Swedish Food Agengy, 2015) for drinking water (i.e., ≤ 10 CFU/100 mL Escherichia coli (E. coli) in water not intended for commercial or public use) without further treatment (Jonsson & Agerberg, 2015)
Values for E. coli were proportional to the number of coliforms and total heterotrophic count (THC)
Summary
An important factor to maintain healthy ecosystems is water quality. Sufficiently high water quality is important to support the diversity of plants and wildlife, but is critical to the health and welfare of human society. The naturally oligotrophic rivers in northern Sweden are generally characterized by a low pollution level (SLU, 2021; van Dijk et al, 1994), and the water quality, in remote (upper) parts of the catchment areas, may still meet national standards (Swedish Food Agengy, 2015) for drinking water (i.e., ≤ 10 CFU/100 mL Escherichia coli (E. coli) in water not intended for commercial or public use) without further treatment (Jonsson & Agerberg, 2015). The occurrence of such clean surface waters.
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