Department of Hydrochemistry and Ecosystem Modelling (HEM)
The Department of Hydrochemistry and Ecosystem Modelling (HEM) of the Institute of Hydrobiology of the Biology Centre CAS studies biogeochemical cycles and processes that control composition and quality of surface waters. This interdisciplinary research is focused on the structure, functions, problems and management of aquatic environments like reservoirs, natural lakes and their catchments.
The staff also provide lecturing of aquatic and environment sciences at the University of South Bohemia and are engaged in advisory services on water quality and aquatic ecosystem functioning for water policy and water management.
The main subjects of studies include:
- recovery of mountain lakes and their catchments after atmospheric acidification;
- eutrophication of water ecosystems as a result of external and internal nutrient loading;
- reconstruction and modelling of historical trends in biogeochemical cycling of the macronutrients in aquatic ecosystems;
- photochemical processes involved in the transport of macro- and micronutrients via dissolved organic matter from soils to aquatic systems;
- the role of sediments and organic matter in the internal cycling of nutrients in lakes;
- the environmental characteristics which can best explain the patterns of nutrient flux to waters in complex catchments.
Research projects
FERRO - Fostering European lakes Restoration by nutrient removal, RecOvery, and reuse: integrated catchment and in-lake scale approach
Project No.: 101157743
Coordinator: Helmholtz-Zentrum Fur Umweltforschung Gmbh - UFZ
Co-principal Investigator: Petr Porcal
Financial support: European Commission – program HORIZON-MISS-2023-OCEAN-01-04
Duration: 2024 - 2028
Eutrophication is a major problem causing poor ecological status of European lakes with its severe impacts being enhanced by climate change. However, at the same time, eutrophication could be the potential solution to the depletion of global phosphate (P) reserves, threatening global food security. A vast amount of P and other nutrients are lost from the catchment and transported into lakes, making most lakes a nutrient-rich reserve, as observed by the frequent occurrence of massive, devastating algal blooms in many lakes. FERRO bridges the nutrient enrichment problem to the depletion of P problem to create a sustainable solution to both challenges by circular management. We will develop a next-generation lake restoration approach by combining targeted restoration techniques with nutrient recovery and recycling to achieve multi-benefits: improved ecological status of lakes, support a circular economy, climate adaptation, support food production, promote biodiversity, and boost ecosystem services provision. The multiple environmental and socio-economic co-benefits extend beyond the scale of intervention, supporting wider sustainability and accounting for social and economic ambitions.
FERRO supports the natural recovery of lakes (after many years of nutrient enrichment) through four transdisciplinary pillars: 1) classification and prioritization of lakes for restoration (integrated in-situ and remote sensing-based techniques); 2) implementation of sustainable catchment-oriented solutions (biotechnology to prevent nutrient losses in agriculture and nutrient recovery at lake inflows and reuse in agriculture), 3) implementation of sustainable in-lake restoration solutions (nutrient recovery from lakes and reuse in agriculture); and 4) knowledge transfer. FERRO marks a major shift in how lake restoration will be done for ages.
Impacts of climate change on nutrient availability in soils and waters of mountainous areas
Project No.: LUAUS24268
Principal Investigator: Eva Kaštovská (JČU), co-PI: Jiří Kopáček
Financial support: INTER-ACTION-LUAUS24
Duration: 3/2024 - 12/2027
The project focuses on understanding the mechanisms causing the increase in nutrient concentrations, especially phosphorus (P) and nitrogen (N), as well as dissolved organic carbon (DOC) in the surface waters of natural, human-unaffected mountainous areas. Increased nutrient availability significantly contributes to the productivity growth of these naturally oligotrophic waters, reducing their biodiversity, landscape value, and usability as drinking water reservoirs. These undesirable changes are closely related to climate change, which has been escalating in the last decade and significantly affecting the functioning of ecosystems in mountainous areas of Europe and America.
Alongside the increase in average annual temperatures, there is a shortening of the winter period, during which microbial processes in alpine soils are limited by low temperatures, and a lengthening of the growing season, when intensive decomposition of organic matter and nutrient recycling occur in soils, significantly supported by plant activity. Additionally, the frequency of torrential rains and the possibility of summer droughts are increasing. These factors accelerate rock weathering and nutrient cycles in soils, leading to the subsequent leaching of mobile forms of N, P, and DOC into the surface waters of mountainous systems. In addition to the climate change manifestations described above, other factors contribute to the eutrophication of waters in mountainous systems. In the mountainous areas of Central Europe, this is primarily due to increased leaching of P and DOC from soils recovering from acidification. In the alpine areas of the USA (and southern Europe), the increasing concentration of P in mountain lakes is likely due to increased dust deposition resulting from drier and windier weather in recent years.
The project's goal is to study and quantify the actual impacts of the combined manifestations of climatic and environmental changes on the cycles of C, N, and P and their availability in soils, retention/leaching, and concentrations in alpine lakes along the altitudinal gradient in two different mountain ranges with different historical and geographical contexts. We selected the High Tatras (Slovakia) and Uinta (Utah, USA) mountain ranges, for which we have long-term climatic data, dust deposition data, and a 30-40 year series of water quality data for mountain lakes. We hypothesize that in the alpine zone of the High Tatras, the behavior of soils and water quality is influenced by the combination of an extraordinary (globally unique) decline in acidic deposition along with a significant increase in temperatures and the frequency of torrential rains, accelerating the mechanical weathering of rocks. In contrast, in the Uinta mountain range (Utah, USA), which has been affected by acidification to a low extent, we expect that changes in the availability of N and P and the mobility of DOC in alpine soils are primarily caused by increased dust deposition and the significant external input of P, in addition to rising temperatures.
Nitrogen fixation in polluted Czech peat bogs: Reconciling high N accumulation rates based on 210Pb dating with low 15N2 uptake and low P availability
Project No.: 24-12596S
Principal Investigator: Martin Novák (Czech Geological Survey), co-PI: Jiří Kopáček
Financial support: Czech Science Foundation
Duration: 2024 - 2026
Availability of reactive nitrogen (Nr) is a key control of carbon sequestration in wetlands. To complement the metabolic demands of Sphagnum in pristine bogs, diazotrophs supply additional Nr via biological nitrogen fixation (BNF). Since breaking the triple bond of atmospheric N2 is energy-intensive, it is reasonable to assume that high inputs of pollutant Nr will lead to BNF downregulation. Yet, recent work has documented measurable BNF rates in Sphagnum bogs also in N-polluted regions. Our study, performed at 3 highly polluted bogs in Central Europe and 1 pristine bog in Svalbard, will attempt to statistically tease apart the role of 10 parameters potentially controlling BNF. Special attention will be paid to phosphorus limitation, but also to sulfate and molybdenum availability. Excess N observed by us in 210Pb dated peat profiles will be attributed to BNF if BNF rates directly measured over 2 seasons and 3 depths by 15N2 experiments are high enough, and if we document immobility of 210Pb as a prerequisite of 210Pb dating at sites with fluctuating water table/redox conditions.
The rates of biological nitrogen fixation (BNF) estimated from excess N in accreting peat will be compared to BNF rates directly measured by 15N2 moss incubations and constrained by P availability. 10 parameters will be measured to statistically tease apart the strength of individual BNF controls.
Performance of mountain ecosystems along elevation gradients under changing environmental conditions
Project No.: 23-06379S
Co-Principal Investigator: Jiří Kopáček
Financial support: Czech Science Foundation
Duration: 2023 - 2025
Changes in the chemical and biological composition of mountain lakes are currently accelerating, being more pronounced at higher elevations. These trends reflect differences in not only nutrient pools and microbial biomass (decreasing with increasing elevation), but also in the increasing intensity of responses of terrestrial systems to environmental changes (recovery from acidification and climate) with elevation. Our study along the elevation gradient of the Tatra Mts. will evaluate the responses of different soil types (from forest, through alpine meadows, to till soils in scree) to current changes in temperature and precipitation regimes (differences in the rapidity and temperature sensitivity of microbial processes involved in C, N, and P cycling). Using field and laboratory experiments, we will identify differences in key processes of nutrient retention, mobilization, and leaching from soils. The leaching mechanisms will be used to understand long-term trends in chemical and biological composition of lakes and their current differences along the elevation gradient.
The aim of the project is to quantify (1) the effects of climate change on nutrient (C, N, P) cycles and microbial community in soils along a mountain gradient from forest to scree area, and (2) the effects of related changes in nutrient leaching on lake chemistry, biota and trajectories of their recovery from acidification.
Environmental changes caused by extraterrestrial impacts and volcanism: Evidence from lake sediments
Project No.: 23-06075S
Principal Investigator: Evžen Stuchlík
Financial support: Czech Science Foundation
Duration: 2023 - 2025
Impact events are potential triggers of abrupt environmental changes as their direct destructive power influences atmospheric and geochemical processes. A multiple evidence from many sites in both hemispheres of Earth shows that a major cosmic impact occurred 12,800 years ago and triggered the Younger Dryas cooling (YD). We propose an interdisciplinary study of lake sediments of YD onset age to evaluate (1) responses of lake-catchment ecosystems to this event. Our study sites are located in the Bohemian Forest (Czechia) and the Tatra Mts (Poland) which allows to disentangle effects of the impact from effects of the preceding eruption of the Laacher See volcano (13,000 years ago) that caused deposition of a volcanic ash in the Bohemian Forest. We will also focus on (2) testing of presence of extraterrestrial admixture in melt grains that we have found in lake sediments of YD onset age and on (3) developing a new method for identification of circannual cycles of sediment deposition. Such a method would considerably improve dating of environmental changes in non-varved lake sediments.
The aim of the project is to evaluate: (1) responses of lake-catchment ecosystems to the Younger Dryas (YD) onset including changes in pedogenesis; (2) presence of extraterrestrial admixture in melt grains of YD onset age; (3) a new method for identification on circannual sedimentation changes in nonvarved lake sediments.
Water scarcity hotspots in Central Europe based on the composition of water isotopesin lakes: hydrological, climatic, and socio economic determinants
Project No.: 23-07152S
Principal Investigator: Yuliya Vystavna
Financial support: Czech Science Foundation
Duration: 2023 - 2025
Climate change and water scarcity in Central Europe have a significant impact on the availability of water resources. The overall aim of the project is to develop a new approach to identify water scarcity hotspots in Central Europe and their determinants based on the isotopic composition of lakes and water balance model using isotopes. The project is focused on: (i) identification of best variables and methods of the data collection and treatment for use in isotope water balance in lake catchments and (ii) quantification of water scarcity using composition of water isotopes in lakes and isotope water balance modelling and assessment of hydrological, climatic and socio-economic determinants of water scarcity using machine learning tools (Random Forest, Gaussian Mixing Model). The novelty of the project relates to unresolved questions on the factors affecting water scarcity and the prediction of water scarcity based on a multidisciplinary approach including environmental and socio-economic variables.
The overall aim of the project is to develop a new approach to identify water scarcity hotspots in Central Europe and their determinants based on the isotopic composition of lakes, isotope- enabled water balance modelling, citizen science and machine learning tools.
Effects of nitrogen availability and forest status on soil microbiome, nutrient cycling, and biological recovery of acidified waters in mountain ecosystem
Project No.: 22-05421S
Principal Investigator: Jiří Kopáček
Financial support: Czech Science Foundation
Duration: 2022 - 2024
The dominant Norway spruce vegetation was to different extents disturbed by bark beetle infestation in the unmanaged Bohemian Forest (BF) catchments during the last two decades. All dead tree biomass remained on site and stands began to regenerate naturally, providing wide gradients of vegetation, soil properties, and surface water composition within individual catchments, as well as among them. We propose an integrated study in the BF catchment-lake systems on effects of natural forest regeneration on chemical and microbial soil composition and function, element (primarily N) cycles and leaching, and recovery of receiving waters from acidification. We plan to evaluate (1) effects of gradual decomposition of dead biomass on a cascade of compositional and functional changes in soil microbial communities, and element availability and leaching; (2) how their fluctuations are affected by density of regenerating trees and their growth rates (both related to microclimate conditions); and (3) how seasonality of postdisturbance element leaching affects biological recovery of waters.
The aims of the project are to evaluate links among (1) climate, soil properties, and spruce forest regeneration after disturbances in mountain catchments; (2) forest re-grow, soil microbiome composition and function, and element leaching; and (3) seasonality of water chemistry and biological recovery from acidification.
