This study describes the design of a laboratory-scale flow-through incubation system as a tool for the rapid estimation of sediment respiration - widely used functional indicator in stream ecosystems. The measurements were compared with those obtained using an in situ closed chamber respiration method and the influence of sediment size on respiration rates was investigated. The study demonstrated that fine sediments ((5 mm) substantially contribute to heterotrophic respiration in the studied gravel-bed river and that the flow-through system is a promising tool for designing experimental set ups investigating stressor-indicator relationships.
COBISS.SI-ID: 4134223
The paper deals with surface water geochemistry and carbon cycling, which depend mainly on geological composition of the river catchment. The investigated surface waters in the river Pesnica catchment that are heavily hydromorphologicaly altered (reservoirs, channelization, land melioration systems) represent waters influenced by chemical weathering of carbonates and of mostly clastic rocks. The objectives of our study were to analyze hydrogeochemical and isotopic composition of dissolved (δ13CDIC) and particulate carbon (δ13CPOC) with characterization of suspended matter and evaluate biogeochemical processes in Pesnica River in Slovenia before and after the retention. Surface waters are generally close to saturation regarding calcite and dolomite, dissolved CO2 is 49 to 1000 times oversaturated relative to atmosphere. δ13CDIC was in the range from -14.8 to -4.2 ‰ and shows following biogeochemical processes in river system: degradation of organic matter, dissolution of carbonates and biological activity, which was confirmed with SEM microscopy and EDXS microanalysis. Results of SEM/EDXS showed that suspended matter is composed of K, Mg and Ca from locations Pesnica 1 and Pesnica 2 (above retention Perniško lake). Sample from Pesnica 3 (below retention) shows higher biological activity, while sample from Pesnica 4 (tributary of Pesnica, drainage channel Biš) contains a lot of particles of microporous structure and fiber structure, which are probably of anthropogenic origin. δ13CPOC is changing from -29.5 to-27.6‰ and showed different stages of degraded terrestrial material. More negative δ13CPOC are shown at location at drainage channel Biš and show higher terrestrial input in river system as locations 1, 2 and 3 Pesnica, which have higher δ13CPOC values. This first results about suspended matter in Pesnica watershed serve for evaluation of anthropogenic influences specially in relation with further influences and longer time planning of sustainable river water management.
COBISS.SI-ID: 30052903
We present review of biogeochemical processes studied in three Slovenian rivers (River Kamniška Bistrica, River Sava in Slovenia and River Idrijca), which represent an ideal natural laboratory for studying biogeochemical processes and anthropogenic impacts in catchments with high weathering capacity is presented. The River Kamniška Bistrica, the River Sava in Slovenia and the River Idrijca water chemistry is dominated by HCO3-, Ca2+ and Mg2+, and Ca2+/Mg2+ molar ratios indicate that calcite/dolomite weathering is the major source of ions to the river system. The Kamniška Bistrica River, the River Sava and River Idrijca and its tributaries are oversaturated with respect to calcite and dolomite. pCO2 concentrations were on average up to 25 times over atmospheric values for River Kamniška Bistrica, 20 times for River Sava and 13 times over atmospheric values for River Idrijca. δ13CDIC values ranged from -12.7 to -2.7 ‰ in River Kamniška Bistrica, from -12.7 to -6.3 ‰ in River Sava in Slovenia, from -10.8 to -6.6 ‰ in River Idrijca, respectively. In all investigated rivers we found out that carbonate dissolution is the most important biogeochemical process affecting carbon isotopes in the upstream portions of the catchment, while carbonate dissolution and organic matter degradation control carbon isotope signatures downstream, except for River Idrijca where both processes contribute equally from source to outflow to River Soča.
COBISS.SI-ID: 30481447
The paper presents the first assessment of sector-specific, spatially resolved global Hg releases into freshwater systems. Among other things, based on knowledge of processes that influence the transport of mercury from contaminated areas in the Idrijca catchemnt and the extent of contamination, a global assessment of such reelases for the category of contaminated sites is made. This is the first such assessment, which was created in cooperation with the UN Environment organization and serves as one of the expert bases for the Minamata Convention, which, in particular, addresses a problem with Hg contaminated sites in a special article.
COBISS.SI-ID: 30268455
The main objective of this paper was to find out which environmental factors affect the biofilm respiratory activity (i.e., respiratory electron transport activity - ETSA) in the Kamniška Bistrica riverbed sediment. To this end, we gathered all the available information on physicochemical properties of water, composition of riverbed sediment, channel morphology, catchment land use and nutrient inputs. The obtained dataset was then used to deepen the knowledge of the interactions between reach- and catchment-scale drivers affecting Kamniška Bistrica River metabolism and their relation to biofilm respiratory activity by applying one of the machine learning methods, namely induction of decision trees.
COBISS.SI-ID: 28933415