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The optical properties of colored dissolved organic matter (CDOM) in surface waters are visible from space and observable throughout the water column in real time using in situ sensors. Due to their ease of measurement, CDOM optical properties are used as proxies for the quantity, quality and processing of dissolved organic matter (DOM) in natural waters. This talk will focus upon the use of these
The role of terrestrial organic carbon for recipient aquatic ecosystems is intensively researched. A multitude of studies now show that terrestrially-derived carbon supports a significant share (allochthony) of consumer biomass in many freshwaters. However, little is known about the mechanisms by which terrestrially-derived carbon is transferred to the level of metazoan zooplankton, and whether th
Many studies assume a respiratory quotient (RQ = CO2 produced per O2 consumed, by moles) of ~1 to calculate bacterial respiration from measured O2 consumption rates. However, the theoretical value of RQ varies with the elemental composition of the compound being decomposed. Photo-oxidation of DOC results in compounds of oxygen-rich organic acids which, theoretically, should result in elevated RQ.
Permafrost thaw can substantially increase the total export of dissolved organic carbon (DOC) to aquatic systems. The effects for bio- and photo-degradable DOC, however, are poorly known, because previous studies have mainly targeted lakes and streams which are indirectly affected by permafrost, while direct experimental work on permafrost thaw is lacking. We thus incubated permafrost cores from a
An important component of the carbon cycle is the lateral flow of dissolved organic carbon (DOC) from terrestrial ecosystems to streams and rivers. The fate of this carbon depends very much on the bioavailability of DOC (BDOC), which may determine whether DOC is returned to the atmosphere as CO2 or deposited in sediments. This study focuses on the linkages between stream DOC composition, optical c
Probing the dynamic control features of biological networks represents a new frontier in capturing the dysregulated pathways in complex diseases. Here, using patient samples obtained from a pancreatic islet transplantation program, we constructed a tissue-specific gene regulatory network and used the control centrality (Cc) concept to identify the high control centrality (HiCc) pathways, which mig
Subarctic ecosystems are predicted to experience the fastest responses to climate change on the planet, with dramatically altered vegetation patterns, frost dynamics and hydrological flow paths. The resulting change in dissolved organic carbon (DOC) export to river systems is poorly known, but reports of rising DOC in northern surface waters have led to widespread speculations on a possible climat
Dynamic ecosystem modelling offers potentially groundbreaking possibilities to reconstruct and project exports of Dissolved Organic Carbon (DOC) from land to surface water. However, the balance between production, degradation and export of soil DOC remains a challenge to model in boreal forests, partly because variability in soil DOC turnover is poorly understood. Here we determined the heterogene
In the classical plenary lecture ‘Global limnology’ (J.A. Downing, 2007, SIL in Montréal), a new holistic direction for freshwater science was pointed out, focused at upscaling of limnological processes to planet Earth. Since then, the literature on the global importance of freshwater networks, especially as routes for carbon degassing, burial and transport, has grown explosively. This has been re
In spite of substantial greenhouse gas emissions from photo-degradation of dissolved organic carbon (DOC), little is known about the variability in DOC photo-reactivity. It has been suggested that photo-reactivity depends on the degree of DOC pigmentation. However, recent evidence suggests that also non-colored fractions can be photo-reactive. Furthermore photo-degradation processes interact with
The contribution of terrestrially-derived carbon to micro-crustacean zooplankton biomass (i.e. allochthony) has been previously studied in lakes and reservoirs, but little is known about allochthony in rivers. We hypothesized that restricted selective grazing in turbulent environments such as rivers would decouple zooplankton from specific microbial and algal food resources, such that their alloch
Swedish alpine and subarctic areas undergo rapid transitions due to climate change, especially in relatively humid areas where the forest vegetation is expanding. It has been suggested that lakes in these areas are in transition from clearwater into brownwater state, because of the humus layer building up in surrounding soils, with negative consequences, e.g., for the biomass production of zooplan
Planktonic community respiration is an important carbon cycling process, typically quantified by converting measured values of dissolved oxygen consumption rates into carbondioxide production rates using a respiratory quotient of 1 (RQ = carbondioxide per oxygen by moles). However, the true variability in planktonic RQs between different aquatic ecosystems is poorly understood. We conducted in sit
The stable carbon isotope ratio (δ13C) is a key tool in tracing the source of carbon within and across ecosystems. In isotope mixing models dissolved organic carbon (DOC) from terrestrial sources is often assigned a fixed δ13C of roughly -28‰ to -27‰ in C3 plant-dominated areas. However, the claim of a uniform δ13C distribution for terrestrial DOC sources of different reactivity has seldom been te
What explains subnational policy choices over tax cut after decentralization? We test two different explanations in the context of the 2002 tax reform in Russia. A popular strand of literature suggests that decentralization induces more regional competition over investment, motivating subnational tax cuts. A second body of literature suggests that personal business interests of regional governors
