Assessment of a portable UV–Vis spectrophotometer's performance for stream water DOC and Fe content monitoring in remote areas

Abstract

Quantification of dissolved organic carbon (DOC) and iron (Fe) in surface waters is critical for understanding the water quality dynamics, brownification and carbon balance in the northern hemisphere. Especially in the remote areas, sampling and laboratory analysis of DOC and Fe content at a sufficient temporal frequency is difficult. Ultraviolet–visible (UV–Vis) spectrophotometry is a promising tool for water quality monitoring to increase the sampling frequency and applications in remote regions. The aim of this study was (1) to investigate the performance of an in-situ UV–Vis spectrophotometer for detecting spectral absorbances in comparison with a laboratory benchtop instrument; (2) to analyse the stability of DOC and Fe estimates from UV–Vis spectrophotometers among different rivers using multivariate methods; (3) to compare site-specific calibration of models to pooled models and investigate the extrapolation of DOC and Fe predictions from one catchment to another. This study indicates that absorbances that were measured by UV–Vis sensor explained 96% of the absorbance data from the laboratory benchtop instrument. Among the three tested multivariate methods, multiple stepwise regression (MSR) was the best model for both DOC and Fe predictions. Accurate and unbiased models for multiple watersheds for DOC were built successfully, and these models could be extrapolated from one watershed to another even without site-specific calibration for DOC. However, for Fe the combination of different datasets was not possible.

Keywords

Water quality; UV-Vis spectrophotometer; Spectral absorbance; Dissolved organic matter; Ferric iron

Published in

Talanta
2021, Volume: 224, article number: 121919

SLU Authors

• Laudon, Hjalmar

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    

Sustainable Development Goals

SDG6 Clean water and sanitation


UKÄ Subject classification

Oceanography, Hydrology, Water Resources


Publication identifier

DOI: https://doi.org/10.1016/j.talanta.2020.121919

Permanent link to this page (URI)

https://res.slu.se/id/publ/109622