Decay Rate of Escherichia coli in a Mountainous Tropical Headwater Wetland

Fecal indicator bacteria like Escherichia coli (E. coli) are widely used to assess water contamination, but their behavior in tropical ecosystems is poorly documented. The main objectives of this study led by Paty Nakhle, PhD student at GET in collaboration with iEES Paris, were to: (i) evaluate decay rates (k) of the total, particle-attached and free-living E. coli; (ii) quantify the relative importance of solar radiation exposition and suspended particles deposition on k; and (iii) investigate E. coli survival in the deposited sediment. Using mesocosms installed across the main headwater wetland of the Houay Pano catchment, northern Lao PDR, the study showed that decay rates ranged from 1.43 ± 0.15 to 1.17 ± 0.13 day−1 for sediment deposition treatments (light and dark), and from 0.50 ± 0.15 to -0.14 ± 0.37 day−1 for sediment resuspension treatments (light and dark). Deposition processes accounted for an average of 92% of E. coli stock reduction. The sampling of E. coli by temporary resuspension of the deposited sediment showed k values close to zero, suggesting potential survival or even growth of bacteria in the sediment.

The paper was published open access in the Water journal.

More news

Exploring the nexus between hydroclimatic variability, population growth, land use land cover change, and long-term upper Nyong Basin River chemistry (Central Africa rainforest)

Hydrological and hydrogeochemical functioning of rivers depends on the relationship between climatic variability, land use and land cover change (LULCC), and population dynamics. However, there is a scientific gap on this relationship in the humid tropical zone of Central Africa. This study, led by David Eric Komba, aims to fill this gap by examining the […]

A float-controlled self-contained laser gauge for monitoring river levels in tropical environments

In this paper Dr Pierret and colleagues present the design, construction and performance of a self-contained float-controlled water level gauge for monitoring water levels in streams and small rivers. This device is inexpensive (cost of about EUR 220), easy to build (no electronics skills or specialized tools required; assembled in a few hours) and straightforward […]

Reuse of bottom sediment from reservoirs to cropland is a promising agroecological practice that must be rationalized

In semi-arid areas, intermittent streams are often equipped with small reservoirs to store water for irrigation and/or groundwater recharge, and to capture sediments lost through erosion. These reservoirs must be periodically desilted to maintain their storage capacity. While bottom sediments are generally considered waste, their reuse in agricultural fields is a centuries-old practice in India. […]

Search