Impact of seasonal climate change on optical and molecular properties of river water dissolved organic matter by HPLC-SEC and UV-vis spectroscopy

Abstract

Background: The change in the optical parameters of dissolved organic matter (DOM) from natural water samples of Pirita River in Estonia were studied during 2 years of winter-spring season. At present, the relative quantitative and qualitative composition of DOM components leached from soils to water, in relation to air and water temperatures and water level fluctuations, has not been estimated in Estonia. The aim was to characterise and fractionate DOM using high-performance size-exclusion chromatography with multiple wavelength detection (DAD) and ultraviolet-visible (UV-vis) spectroscopy. Changes in several chromatographic/molecular and spectroscopic/optical parameters were investigated. Results: The experimental data indicated that the optical and molecular properties of DOM depend on the climate conditions, but the effect can be diverse. In cold climates, the concentration of DOM in river water can be lower (2013) or higher (2014) than in warmer climate conditions. Optical properties indicate that the quantity of humic substances (HS) is minimal under an ice cover and DOM contains more microbial-derived peptide-like constituents. Conclusions:The results point out the usefulness of HPLC-SEC and UV-vis spectroscopy for climate change-related DOM studies in real environmental conditions. Used methods enable detailed monitoring of humic molecules dissolved from the catchment soil, as well as microbial constituents (peptide-like components of DOM). The used approach can be additionally applied for monitoring the changes of raw water quality and thus for the design and optimisation of drinking water process technology.

Long‐term fertilization alters microbial community but fails to reclaim soil organic carbon stocks in a land‐use changed soil of the Tibetan Plateau

“…The contents of the total (TOC) and POxC in the air‐dried WSA and bulk soil were determined using the H 2 SO 4 –K 2 CrO 7 oxidation method (Perrier & Kellogg, ) and the KMnO 4 oxidation method (Blair, Lefroy, & Lisle, ), respectively. DOC was extracted with deionized water in a 1:5 soil/water ratio and detected on a TOC analyzer (multi C/N 2100, Germany; Carrillo‐Gonzalez, Gonzalez‐Chavez, Aitkenhead‐Peterson, Hons, & Loeppert, ; Lepane, Depret, Väli, & Suursööt, ). The isolation and determination of soil FOC were conducted using 1.8 g cm −3 NaI solution according to the procedure described by Elliott and Cambardella ().…”

Compositional and chemical characteristics of dissolved organic matter in various types of cropped and natural Chinese soils

“…A higher proportion of peptide-like substances in the cropped cinnamon soils and a higher proportion of tryptophan-like substances in the cropped red soils were also found in comparison with the corresponding natural soils. This may be due to a lower input and a faster decomposition of the SOM in the cropped soils [53,54]. The removal of above-ground biomass of crops by harvesting reduced the input of plant residues, and therefore, DOM in the cropped soil relied more on allochthonous sources [16].…”

A Characteristic Interval Modeling Method for Simultaneous Detection of Multiple Metal Ions

“…3) The instrument has the advantages of simple structure, low maintenance cost and low repetition rate, and is suitable for on-line analysis ( Attimarad 2012 ; Merás et al, 2002 ). However, due to the coexistence of multiple heavy metal ions in the same period in zinc smelting industrial wastewater, their chemical characteristics are similar, their mutual influence is serious ( Rastogi et al, 2015 ), their absorption spectra overlap seriously ( Lambert et al, 2017 ), and the full spectra information contains a lot of redundant non characteristic information ( Fedenko et al, 2017 ), resulting in low accuracy and large prediction error of ultraviolet visible spectral analysis model ( Lepane et al, 2015 ; Lee et al, 2017 ). Therefore, the traditional multivariate linear analysis method based on full band information modeling is difficult to accurately detect the concentration of polymetallic ions in zinc smelting wastewater ( Rote and Bari, 2009 ; Khan et al, 2020 ).…”