Time-resolved fluorescence measurements of dissolved organic matter (DOM) as a function of environmental parameters in estuarine waters.

Autor: de Bruyn WJ; Chemistry and Biochemistry Program, Schmid College of Science, Chapman University, One University Drive, Orange, CA, 92866, USA., Manickam D; Chemistry and Biochemistry Program, Schmid College of Science, Chapman University, One University Drive, Orange, CA, 92866, USA., Harrison AW; Department of Chemistry, Austin College, 900 N. Grand Ave., Sherman, TX, 75090, USA., Clark CD; Department of Chemistry, College of Science and Engineering, Western Washington University, 516 High Street, Bellingham, WA, 98229, USA. Catherine.Clark@wwu.edu.
Jazyk: angličtina
Zdroj: Environmental science and pollution research international [Environ Sci Pollut Res Int] 2025 Jan 03. Date of Electronic Publication: 2025 Jan 03.
DOI: 10.1007/s11356-024-35777-3
Abstrakt: Fluorescent lifetimes of dissolved organic matter (DOM) and associated physicochemical parameters were measured over 14 months in an estuary in Southern California, USA. Measurements were made on 77 samples from sites near the inlet, mid-estuary, and outlet to maximize the range of physicochemical variables. Time-resolved fluorescence data were well fit to a triexponential model with an intermediate lifetime component (τ 1 : 1 to 5 ns), a long lifetime component (τ 2 : 2 to 15 ns), and a short lifetime component (τ 3 : < 1 ns). The amplitude of the short-lived component dominated all measurements (60-70%). However, fractional contributions to steady-state fluorescence were dominated by the intermediate and long-lived components at most wavelengths. Lifetimes varied as a function of both excitation and emission wavelength suggesting structural differences in DOM fluorophores. Lifetimes decreased from the estuary inlet to the outlet and were positively correlated with absorbance and DOC concentrations and negatively correlated with salinity and spectral slope. Quenching experiments with halide ions demonstrated that fluorophores are quenched by heavy ions and that different fluorophores are quenched at different rates. However, concentrations of ions in seawater are not high enough for quenching to completely account for observed lifetime changes across the estuary. The observed variation in lifetimes between sites is instead primarily attributed to structural changes associated with DOM processing. Higher lifetimes are associated with less processed material at the inlet site.
Competing Interests: Declarations. Ethics approval: Not applicable. Consent to participate: Not applicable. Consent for publication: The authors give consent for publication. Competing interests: The authors declare no competing interests.
(© 2025. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)
Databáze: MEDLINE
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