Abstract
Estuarine sediments are a reservoir for faecal bacteria, such as E. coli, where they reside at greater concentrations and for longer periods than in the overlying water. Faecal bacteria in sediments do not usually pose significant risk to human health until resuspended into the water column, where transmission routes to humans are facilitated. The erosion resistance and corresponding E. coli loading of intertidal estuarine sediments was monitored in two Scottish estuaries to identify sediments that posed a risk of resuspending large amounts of E. coli. In addition, models were constructed in an attempt to identify sediment characteristics leading to higher erosion resistance. Sediments that exhibited low erosion resistance and a high E. coli loading occurred in the upper- and mid-reaches of the estuaries where sediments had higher organic content and smaller particle sizes, and arose predominantly during winter and autumn, with some incidences during summer. Models using sediment characteristics explained 57.2% and 35.7% of sediment shear strength and surface stability variance respectively, with organic matter content and season being important factors for both. However large proportions of the variance remained unexplained. Sediments that posed a risk of resuspending high amounts of faecal bacteria could be characterised by season and sediment type, and this should be considered in the future modelling of bathing water quality.
Highlights
Estuarine sediments act as a reservoir for faecal bacteria that have been transported to the environment from both point and diffuse sources throughout the watershed
Sediments with a shear strength of
Within the monthly sampling campaign, sediment shear strength was greatest at the mixed sand (MS) site followed by mixed mud (MM) > sand (S) > mud (M)
Summary
Estuarine sediments act as a reservoir for faecal bacteria that have been transported to the environment from both point and diffuse sources throughout the watershed. Faecal bacteria in estuarine sediments do not usually pose significant risk to human health until they are resuspended into the water column, when sediments themselves become a source of contamination. This can be through (a) mass erosion where sediment beds are eroded during storm conditions, (b) small scale erosion from tidal or current shear forces. Public Health 2019, 16, 3255; doi:10.3390/ijerph16183255 www.mdpi.com/journal/ijerph
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have