Kopáček Jiří, Brahney Janice, Kaňa Jiří, Kopáček Marek, Porcal Petr, Stuchlík Evžen
Biology Centre CAS, Institute of Hydrobiology, Na Sádkách 7, 370 05 České Budějovice, Czech Republic; University of South Bohemia, Faculty of Science, CZ-370 05 České Budějovice, Czech Republic.
Utah State University, Department of Watershed Sciences and Ecology Center, 5210 Old Main Hill, Logan, UT 84322, USA.
Sci Total Environ. 2024 Nov 10;950:175363. doi: 10.1016/j.scitotenv.2024.175363. Epub 2024 Aug 6.
The ionic and nutrient composition of mountain lakes recovering from atmospheric acidification is increasingly influenced by climate change (increasing air temperature and frequency of heavy rainfall events). We investigated the evolution of organic nitrogen (ON), dissolved organic carbon (DOC) and phosphorus (P) concentrations in alpine lakes in the Tatra Mountains (Central Europe) between 1993 and 2023, resulting from changes in climate and the ionic composition of atmospheric deposition. Our results suggest that the decreasing acidity of precipitation and the climatically induced increasing frequency of heavy rainfall events and air temperatures fluctuating around the freezing point have the potential to increase ON concentrations in alpine lakes despite decreasing deposition of inorganic N. The increasing ON involves its allochthonous and autochthonous sources: (1) increased co-export of ON with DOC from soils in dissolved organic matter due to less acidic precipitation and more frequent heavy rainfall events and (2) increased in-lake primary productivity (chlorophyll a) associated with higher P availability. Based on our previous studies, we hypothesize that P availability has increased due to (i) reduced adsorption of phosphate in precipitation to the metal hydroxides in the soil-adsorption complex as a result of increasing pH in precipitation and soil water and (ii) increased P production by weathering due to climate-induced increased mechanical erosion of rocks in unstable scree areas. The extent of these changes was related to the percentage cover of scree areas and meadow soils in the lake catchments. In addition, our results suggest that ON (besides chlorophyll a) may be a more sensitive indicator of increasing productivity of oligotrophic alpine lakes under changing air pollution and climate than generally low P concentrations and their poorly detectable trends.
正从大气酸化中恢复的山区湖泊的离子和养分组成，越来越受到气候变化（气温上升和暴雨事件频率增加）的影响。我们研究了1993年至2023年期间，中欧塔特拉山脉高山湖泊中有机氮（ON）、溶解有机碳（DOC）和磷（P）浓度的变化情况，这些变化是由气候和大气沉降的离子组成变化所导致的。我们的研究结果表明，尽管无机氮的沉降量减少，但降水酸度的降低以及气候导致的暴雨事件频率增加和气温在冰点附近波动，有可能增加高山湖泊中的有机氮浓度。有机氮增加涉及到其外源和内源来源：（1）由于降水酸度降低和暴雨事件更频繁，溶解有机物中有机氮与溶解有机碳从土壤中的共同输出增加；（2）湖泊内初级生产力（叶绿素a）增加，这与更高的磷有效性有关。基于我们之前的研究，我们推测磷有效性增加的原因是：（i）由于降水和土壤水pH值升高，降水中的磷酸盐在土壤吸附复合体中与金属氢氧化物的吸附减少；（ii）由于气候导致不稳定碎石区域岩石机械侵蚀增加，风化作用产生的磷增加。这些变化的程度与湖泊集水区中碎石区域和草甸土壤的覆盖百分比有关。此外，我们的研究结果表明，在空气污染和气候不断变化的情况下，有机氮（除叶绿素a外）可能比通常较低的磷浓度及其难以检测的趋势，更能敏感地指示贫营养高山湖泊生产力的增加。
