Identifying sources of pollution in the River Ray
Background
The ADAS Biotechnology team and water research company WRc undertook a pilot study to investigate whether microbial source tracking could identify types and sources of faecal pollution in rivers.
Since 2021, only 14% of rivers in England achieved ‘good’ ecological status, with none receiving an overall ‘good’ classification from the Environment Agency. One major risk to river water quality is faecal pollution, originating from untreated sewage discharges, agricultural run-off, and urban drainage.
Identifying specific sources of faecal contamination can be difficult – current regulations on microbial indicators, such as E. coli, do not distinguish between human and animal faecal sources.
The project sought to confirm whether it was possible to pinpoint the specific host (i.e., humans, birds, or livestock) using microbial source tracking. Knowing the source would open up the opportunity for more targeted water quality management.
Actions taken
A team of water microbiologists at WRc designed, undertook, and analysed samples from the River Ray in Wiltshire. ADAS Biotechnology then extracted DNA from the water samples.
Using a DNA amplification technique known as quantitative polymerase chain reaction (qPCR), ADAS identified whether faecal matter was present. The qPCR was able to detect the human-specific marker HF183, which suggested faecal contamination from sewage discharges.
Results
The project proved it was possible to identify human faecal pollution in water samples using microbial source tracking. This in turn could help narrow down the source of the contamination.
Building on the success of the pilot study, microbial source tracking could be applied across various industries. Knowing that the presence of the HF183 marker is a sign of human-derived faecal pollution, future work could explore markers for other contamination sources. Identifying livestock faecal markers (ruminant-specific Bacteroidales markers) could help assess agricultural run-off and its impact on water quality.
