Comparison of river and canal water dissolved organic matter fluorescence within an urbanised catchment

Recently, growing interest has been shown in the study of canal water quality, yet no research using continuous fluorescence monitoring to characterise dissolved organic matter (DOM) has been performed. This paper evaluated DOM characteristics at hourly resolution. A comparison was made between canal and nearby urban river fluorescence spectra, to emphasise the specific nature of canal water DOM. Results showed that canal water had a significant proportion of microbially derived DOM, while the urban river had a greater proportion of terrestrially derived fractions. The microbial character of canal water DOM originated from the low flow of water, the nutrients predominance and continuous DOM processing. Hence, DOM fluorescence is invariant over a timescale of days, and recreational navigation and precipitation events have no major influence on DOM characteristics. Our results are expected to be applicable to future research on highly regulated freshwater systems for DOM quantity estimation or for water quality models.