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


Agricultural groundwater with high nitrates and dissolved salts given to pregnant mice alters brain development in the offspring

This new paper, at the interface between environment and health, shows that groundwater contaminated by agricultural inputs from the Indian site of Berambadi (M-TROPICS observatory), significantly impacts the brain development of mice when given to pregnant or lactating mice: fewer neurons, fewer astrocytes (white blood cells in the brain), and more dead cells in the […]



The M-TROPICS CZO releases long-term meteorological, hydrological, sedimentary geochemical, and land use datasets in Cameroon, Lao PDR, and India

The CZO M-TROPICS (Multiscale TROPIcal CatchmentS) investigates the response of tropical catchments to global change based on long-term collection of meteorological, hydrological, sedimentary, geochemical, and land use data in partnership with academic and governmental institutions in various tropical countries. M-TROPICS includes in particular the experimental watersheds of Nyong in Cameroon (1994-), Houay Pano in Lao […]



Experimental and modelling evidence of splash effects on manure borne Escherichia coli washoff

In tropical montane South-East Asia, recent changes in land use have induced increased runoff, soil erosion and instream suspended sediment loads. Land use change is also contributing to increased microbial pathogen dissemination and contamination of stream waters. Escherichia coli (E. coli) is frequently used as an indicator of faecal contamination. Field rain simulations were conducted […]