Over the last 3–4 decades, Lake Peipsi water (sampling site A, middle part of the lake, and site B, northern part) has experienced a statistically significant increase of bicarbonate, pH, chemical oxygen demand, nitrate (and nitrite in site B), due to combination of climate change and eutrophication. By photochemical modelling, we predicted a statistically significant decrease of radicals OH and CO 3 (site A, by 45% and 35%, respectively) and an increase of triplet states of chromophoric dissolved organic matter (3CDOM⁄; site B, by 25%). These species are involved in pollutant degradation, but formation of harmful by-products is more likely with 3CDOM⁄ than with OH. Therefore, the photochemical self-cleansing ability of Lake Peipsi probably decreased with time, due to combined effects of climate change and eutrophication. In different environments (e.g. Lake Maggiore, NW Italy), ecosystem restoration policies had the additional advantage of enhancing sunlight-driven detoxification, suggesting that photochemical self-cleansing would be positively correlated with lake water quality.

Modelling lake-water photochemistry: Three-decade assessment of the steady-state concentration of photoreactive transients (°OH, CO3-° and 3CDOM*) in the surface water of polymictic Lake Peipsi (Estonia/Russia)

MINELLA, Marco;DE LAURENTIIS, ELISA;MAURINO, Valter;MINERO, Claudio;VIONE, Davide Vittorio
2013

Abstract

Over the last 3–4 decades, Lake Peipsi water (sampling site A, middle part of the lake, and site B, northern part) has experienced a statistically significant increase of bicarbonate, pH, chemical oxygen demand, nitrate (and nitrite in site B), due to combination of climate change and eutrophication. By photochemical modelling, we predicted a statistically significant decrease of radicals OH and CO 3 (site A, by 45% and 35%, respectively) and an increase of triplet states of chromophoric dissolved organic matter (3CDOM⁄; site B, by 25%). These species are involved in pollutant degradation, but formation of harmful by-products is more likely with 3CDOM⁄ than with OH. Therefore, the photochemical self-cleansing ability of Lake Peipsi probably decreased with time, due to combined effects of climate change and eutrophication. In different environments (e.g. Lake Maggiore, NW Italy), ecosystem restoration policies had the additional advantage of enhancing sunlight-driven detoxification, suggesting that photochemical self-cleansing would be positively correlated with lake water quality.
90
2589
2596
Surface-water photochemistry, Lake Peipsi, Long-term trends, Sensitised photolysis
Marco Minella; Elisa De Laurentiis; Olga Buhvestova; Marina Haldna; Külli Kangur; Valter Maurino; Claudio Minero; Davide Vione
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/141144
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