Schreder Stefanie, Sommaruga Ruben, Psenner Roland, Chimani Barbara, Ganekind Manfred, Koinig Karin A
Department of Ecology, Universität Innsbruck, Technikerstr. 25, 6020 Innsbruck, Austria.
Department of Ecology, Universität Innsbruck, Technikerstr. 25, 6020 Innsbruck, Austria; Present address: eurac Research, Drususalle 1/Viale Druso 1, 39100 Bolzano/Bozen, Italy.
Sci Total Environ. 2023 Dec 20;905:167750. doi: 10.1016/j.scitotenv.2023.167750. Epub 2023 Oct 12.
Climate change has strongly affected lakes around the world, but the relative effects of warmer air temperatures and changing precipitation on the water chemistry of alpine systems are not well understood. Here we tested the effect of monthly and seasonal climate on the water chemistry of six high mountain lakes located in the Alps. From 1982 to 2020, water samples were collected annually from different depths during the autumn mixing. We observed a simultaneous increase in electrical conductivity, ionic content, and pH with air temperature. In lakes with rock glacier influence, the increase in conductivity, ionic content, and especially in sulfate was even more pronounced, but accompanied by a strong decrease in pH. These differences are attributed to the direct influence of acidic meltwater from active rock glaciers in catchments with acidic bedrock. We then analyzed changes in lake chemistry, taking into account seasonal trends in air temperature and precipitation, using redundancy analysis. Temperature increase significantly affected water chemistry in five of the six lakes, especially at times of ice breakup. Increasing warming explained 17% to 32% of the changes in electrical conductivity, alkalinity, pH, major ions, and nitrogen. In contrast, precipitation had little effect on the changes of those parameters. Nevertheless, late spring snowfall and high snowfall in early fall, which result in prolonged ice cover, had a dampening effect on the impact of climate warming on lake chemistry. Our results confirm that climate warming remains a major driver of chemical changes in alpine lakes, but provide new evidence that late spring temperatures are the most important triggers.
气候变化对全球湖泊产生了重大影响，但气温升高和降水变化对高山系统水化学的相对影响尚未得到充分了解。在此，我们测试了月度和季节气候对阿尔卑斯山六个高山湖泊水化学的影响。1982年至2020年期间，每年秋季水体混合时从不同深度采集水样。我们观察到电导率、离子含量和pH值随气温同时升高。在受岩石冰川影响的湖泊中，电导率、离子含量，尤其是硫酸盐的增加更为明显，但同时pH值大幅下降。这些差异归因于基岩呈酸性的集水区中活跃岩石冰川产生的酸性融水的直接影响。然后，我们利用冗余分析，考虑气温和降水的季节性趋势，分析了湖泊化学的变化。气温升高对六个湖泊中的五个湖泊的水化学产生了显著影响，尤其是在冰层破裂时。升温加剧解释了电导率、碱度、pH值、主要离子和氮变化的17%至32%。相比之下，降水对这些参数的变化影响很小。然而，春末降雪和初秋大雪导致冰盖期延长，对气候变暖对湖泊化学的影响起到了抑制作用。我们的结果证实，气候变暖仍然是高山湖泊化学变化的主要驱动因素，但提供了新的证据表明春末气温是最重要的触发因素。
