Particle-Size Distribution As Indicator for Fecal Bacteria Contamination of Drinking Water from Karst Springs

Abstract

Continuous monitoring of particle-size distribution (PSD), total organic carbon (TOC), turbidity, discharge and physicochemical parameters, together with analyses of fecal indicator bacteria, particularly Escherichia coli, made it possible to better understand the processes governing pathogen transport in karst groundwater and to establish PSD as indicator for possible microbial contamination of drinking water from karst springs. In the study area near Yverdon-les-Bains, Switzerland, tracer tests proved connection between a sinking stream draining agricultural land and several springs, 4.8–6.3 km away. Tracing and monitoring results demonstrate that (i) suspended particles (turbidity) in the spring water either originate from remobilization of sediments inside the aquifer (autochthonous) or from the sinking stream and land surface (allochthonous); (ii) allochthonous turbidity coincides with increased E. coli and TOC levels; (iii) PSD makes it possible to distinguish the two types of turbidity; (iv) a relative increase of finer particles (0.9–10 µm) indicates allochthonous turbidity and thus possible fecal contamination. The method permits to optimize water treatment and identify periods when the spring water must be rejected. Findings from other test sites confirm the feasibility of this approach.

Mobilisation or dilution? Nitrate response of karst springs to high rainfall events

“…But what karst features are most relevant for dilution and mobilisation processes? In the study of Pronk et al (2009), a sinking stream strongly impacts nitrate concentrations (and faecal bacteria) in spring water after storm events. The sinking stream points at the presence of a well-developed conduit system in the karst aquifer.…”

“…5a). Pronk et al (2007) observed that a stream draining into a swallow hole in an agriculture-dominated area contributes significantly to nitrate variations at the spring during storm events. Their interpretation is in line with the conceptual model of the present study, where mobilisation in the soil/epikarst and subsequent transport of nitrate via the conduit flow system occur, i.e.…”

Microbial communities in karst groundwater and their potential use for biomonitoring

“…The Moulinet spring consists of eight individ- Previous studies based on hydrochemical and isotope data showed that the spring water consists essentially of three different components: deep, clean, and warm groundwater; clean and cold groundwater from the Malm limestone karst aquifer infiltrating on the forested slopes of the Jura Mountains; and cold and frequently contaminated water from the swallow hole (Muralt 1999). Further, monitoring of natural parameters allowed two important conclusions to be drawn (Pronk et al 2006(Pronk et al , 2007 1. The swallow hole is the major source of nitrate, organic carbon and faecal indicator bacteria contamination occurring at the springs, particularly after heavy rainfall.…”

“…Particle-size distribution (PSD) measurements at karst springs have allowed distinguishing between autochthonous and allochthonous particles. A relative predominance of finer particles, for example, suggests an allochthonous origin and is often associated with faecal indicator bacteria contamination (Pronk et al 2007). Personné et al (2004) have studied bacterial colonisation of introduced substrates in a karst aquifer and concluded that enteric bacteria from periodical contamination with waste water were unlikely to persist in the system.…”

Development of Population and Technical Infrastructure in Municipalities of the Moravian Karst: Potential Influence on the Organic Pollution of Water

“…Jakékoliv kontaminace těchto zdrojů odpadní vodou, tedy i komunální odpadní vodou, bývá pro obyvatele těchto oblastí a turistických ruch velké ohrožení. Proto jsou v krasových oblastech státem podporovány výstavby ČOV, které mohou zásadním způsobem zlepšit kvalitu povrchových vod (Andreo et al, 2006;Pronk et al, 2007;Haakh, 2010;Goeppert a Goldscheider, 2011;Jiang, 2013). Jsou známé případy kontaminace této krasové vody např.…”