Stable isotopes reveal organic nitrogen pollution and cycling from point and non-point sources in a heavily cultivated (agricultural) Mediterranean river basin.

Autor: Matiatos I; Hellenic Centre for Marine Research, Institute of Marine Biological Resources and Inland Waters, 19013 Anavissos Attikis, Greece. Electronic address: i.matiatos@hcmr.gr., Lazogiannis K; Hellenic Centre for Marine Research, Institute of Marine Biological Resources and Inland Waters, 19013 Anavissos Attikis, Greece., Papadopoulos A; Hellenic Centre for Marine Research, Institute of Marine Biological Resources and Inland Waters, 19013 Anavissos Attikis, Greece., Skoulikidis NT; Hellenic Centre for Marine Research, Institute of Marine Biological Resources and Inland Waters, 19013 Anavissos Attikis, Greece., Boeckx P; Isotope Bioscience Laboratory-ISOFYS, Department of Green Chemistry and Technology, Ghent University, Belgium., Dimitriou E; Hellenic Centre for Marine Research, Institute of Marine Biological Resources and Inland Waters, 19013 Anavissos Attikis, Greece.
Jazyk: angličtina
Zdroj: The Science of the total environment [Sci Total Environ] 2023 Nov 25; Vol. 901, pp. 166455. Date of Electronic Publication: 2023 Aug 20.
DOI: 10.1016/j.scitotenv.2023.166455
Abstrakt: The Pinios River Basin (PRB) is the most intensively cultivated area in Greece, which hosts numerous industries and other anthropogenic activities. The analysis of water samples collected monthly for ∼1 ½ years in eight monitoring sites in the PRB revealed nitrate pollution of organic origin extending from upstream to downstream and occurring throughout the year, masking the signal from the application of synthetic fertilizers. Nitrate concentrations reached up to 3.6 mg/l as NO 3 - -N, without exceeding the drinking water threshold of ∼11.0 mg/l (as NO 3 - -N). However, the water quality status was "poor" or "bad" in ∼50 % of the samples based on a local index, which considers the potential impact of nitrate on aquatic biological communities. The δ 15 Ν-ΝΟ 3 - and δ 18 O-NO 3 - values ranged from +4.4 ‰ to +20.3 ‰ and from -0.5 ‰ to +14.4 ‰, respectively. The application of a Bayesian model showed that the proportional contribution of organic pollution from industries, animal breeding facilities and manure fertilizers exceeded 70 % in most river sites with an overall uncertainty of ∼0.3 (UI90 index). The δ 18 O-NO 3 - and its relationship with δ 18 O-H 2 O revealed N-cycling and mixing processes, which were difficult to identify apart from the uptake of nutrients by phytoplankton during the growing season and metabolic activities. The strong correlation of δ 15 Ν-ΝΟ 3 - values with a Land Use Index (LUI) and a Point Source Index (PSI) highlighted not only the role of non-point nitrate sources but also of point sources of nitrate pollution on water quality degradation, which are usually overlooked. The nitrification of organic wastes is the dominant nitrate source in most rivers in Europe. The systematic monitoring of rivers for nitrate isotopes will help improve the understanding of N-cycling and the impact of these pollutants on ecosystems and better inform policies for protection measures so to achieve good ecological status.
Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Elias Dimitriou reports financial support was provided by International Atomic Energy Agency.
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Databáze: MEDLINE
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