Over the last 3-4 decades, water of Lake Peipsi (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 only in site B), most likely due to combination of climate change and eutrophication , , . By use of a photochemical model , we predicted a statistically significant decrease in steady-state concentrations of the radicals ???OH and CO3?????? (site A, by 45% and 35%, respectively) and an increase of the triplet states of chromophoric dissolved organic matter (3CDOM*; site B, by about 25%). These species are involved in pollutant degradation , , but formation of harmful by-products is definitely less likely with ???OH than with 3CDOM*. Therefore, the natural ability of Lake Peipsi to photodegrade harmful xenobiotics probably underwent a decrease with time. This result would be linked to combined effects of climate change and eutrophication, while in other environments the ecosystem restoration policies would produce the additional advantage of enhancing sunlight-driven detoxification.
A MODEL APPROACH TO LINK INDIRECT PHOTOCHEMISTRY IN SURFACE WATERS WITH CLIMATE CHANGE AND HUMAN IMPACT: THE CASE OF POLYMICTIC LAKE PEIPSI (Estonia/Russia) OVER THE LAST THREE DECADES.
DE LAURENTIIS, ELISA;MINELLA, Marco;MAURINO, Valter;MINERO, Claudio;VIONE, Davide Vittorio
2013-01-01
Abstract
Over the last 3-4 decades, water of Lake Peipsi (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 only in site B), most likely due to combination of climate change and eutrophication , , . By use of a photochemical model , we predicted a statistically significant decrease in steady-state concentrations of the radicals ???OH and CO3?????? (site A, by 45% and 35%, respectively) and an increase of the triplet states of chromophoric dissolved organic matter (3CDOM*; site B, by about 25%). These species are involved in pollutant degradation , , but formation of harmful by-products is definitely less likely with ???OH than with 3CDOM*. Therefore, the natural ability of Lake Peipsi to photodegrade harmful xenobiotics probably underwent a decrease with time. This result would be linked to combined effects of climate change and eutrophication, while in other environments the ecosystem restoration policies would produce the additional advantage of enhancing sunlight-driven detoxification.
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