Fluxes of ecologically important solutes in the Plešné catchment–lake system from 2000–2017

0498101 - BC 2019 RIV CZ eng J - Journal Article
Kopáček, Jiří - Hejzlar, Josef - Kaňa, Jiří - Porcal, Petr - Turek, Jan
Fluxes of ecologically important solutes in the Plešné catchment–lake system from 2000–2017.
Silva Gabreta. Roč. 24, č. 1 (2018), s. 115-147. ISSN 1211-7420
R&D Projects: GA ČR GA17-15229S
Grant - others:TCP ERDF(CZ) 26
Program: Programu přeshraniční spolupráce Česká republika – Svobodný stát Bavorsko Cíl EÚS 2014 – 2020
Institutional support: RVO:60077344
Keywords : recovery from acidification * nitrogen * sulphur * organic carbon * aluminium
OECD category: Environmental sciences (social aspects to be 5.7)

Fluxes of major ions and nutrients were measured in the catchment–lake system of atmospherically acidified Plešné Lake between 2000 and 2017 hydrological years. The system has been recovering from acidification since the late 1980s. Bark beetle killed about 90% of mature Norway spruce trees in the catchment from 2004–2008 and all dead biomass was left in the catchment. The average water outflow from the system was 1087 mm/yr and the water residence time in the lake averaged 338 days during 2000–2017. The Plešné catchment was an average net source of protons (350 eq/ha/yr) throughout the study. The most important proton sources were net release of nitrate and sulphate (760 and 370 eq/ha/yr, respectively) and retention of ammonium in soils (410 eq/ha/yr), while terrestrial production of ionic aluminium (Ali) and base cations represented the most important proton sinks (530 and 780 eq/ha/yr, respectively). The maximum terrestrial proton production of 580 eq/ha/yr occurred after the tree dieback (an average for 2006–2010). The in-lake biogeochemical processes reduced the incoming proton by 65% (i.e., neutralized on average 2670 eq/ha/yr protons on a lake-area basis), and reached maximum values of 3590 eq/ha/yr on average from 2006–2010. The nitrate and sulphate reductions and photochemical and microbial oxidation of organic acid anions (A) were the most important proton neutralizing processes (3950, 250, and 1510 eq/ha/yr, respectively), while hydrolysis of Ali was the dominant proton generating process (2430 eq/ha/yr). The proton concentrations in the lake have started to decrease since 2009, because inputs of nitrate and A have remained high enough to neutralize protons by nitrate reduction and A oxidation, while proton production by Ali hydrolysis has decreased due to decreasing terrestrial Ali export. The changes in composition of tributaries after the tree dieback thus caused rapid pH increase to >5 and a reestablishment of the carbonate buffering system in Plešné Lake.
Permanent Link: http://hdl.handle.net/11104/0290536