1721 research outputs found
Sort by
Artificially induced migration of redox layers in a coastal sediment from the Northern Adriatic
No full textLong-term experimental studies suggest that, under transient anoxic conditions, redox fronts within the sediment shift upwards, causing sequential rise and fall of benthic fluxes of reduced species (Mn(II), Fe(II) and S(-II)). Infaunal benthic organisms are associated with different redox fronts as micro-habitats and must be affected by such changes during natural hypoxia events. In order to document the geochemical evolution of the sediment during prolonged anoxia in the framework of an in situ experiment designed to
mimic natural conditions, benthic chambers were deployed on the seafloor of the Northern Adriatic and sampled after 9, 30 and 315 days of incubation. Oxygen and sulfide were measured continuously in the early stages (9 days) of the experiment.
High-resolution pore water profiles were sampled by DET probes and redox-sensitive species (S(VI), Mn(II)and Fe(II)) and alkalinity were measured. Starting oxygen saturation was about 80% within the chamber. After 7 days, anoxia was established in the bottom waters within the chambers. Mn(II) and Fe(II) started diffusing towards the anoxic water column until they reached the surficial sediment. Being reoxidized there, Mn and Fe reprecipitated, giving a rusty coloration to the seafloor. Infaunal species appeared at the sediment surface. After 20 days, all macro-organisms were dead. Decomposition of macroorganisms at the sediment–water interface generated S(-II) within the entire height of the chamber, leading to a downward flux of sulfides into the sediment, where they were quickly oxidized by metallic oxides or precipitated as FeS. S(-II) was below detection in the water column and pore waters at the end of the experiment. Our results suggest that S(-II) enrichment in the water column of coastal systems, which are episodically anoxic, is strongly controlled by the biomass of benthic macrofauna and its decay during anoxia, whereas its residence time in the water column is controlled by iron
availability (as solid oxides or as dissolved reduced cations) within the sediment, even without water circulation
Tree-ring chronology of pedunculate oak (Quercus robur) and its potential for development of dendrochronological research in Croatia
No full textWe present the local tree-ring chronology of pedunculate oak (Qercus robur) from Kobiljak near Zagreb, Croatia(16º09’ E, 45º49’ N, 140 m a.s.l.). The chronology is based on 17 trees and is 127 years long and covers the period of 1883-2009. The well replicated part of the residual version of the ARSTAN chronology with SSS>0.80(interval of 88 years, period 1922-2009 was used for dendroclimatological analysis, which showed that June precipitation has positive and temperature has negative effect on tree-ring variation. Comparison with 40 available oak chronologies from the surrounding countries confirmed its good teleconnection with 2 local oak chronologies from Austria, 2 from Hungary, and 3 from Slovenia. It also exhibits good heteroconnection, i.e. similarity with chronologies of beech (Fagus sylvatica), from various sites in Slovenia. The similarities can be ascribed to response to common climatic factors. The results indicate that the chronology could be a good reference point for constructing a longer regional chronology in Croatia and surrounding countries, which could be used for different purposes including dating of objects of cultural heritage
Determining density and moisture content of the European beech (Fagus sylvatica L.) coarse woody debris from the secondary virgin forest Rajhenavski Rog
No full textMeasuring density of wood samples with mercury volumemeter is a standard throughout the world. To find out the reliability of another less toxic density measuring technique, samples were measured in a mercury medium and in a water medium as well. This study is a revision of the previously published results (Finžgar et al., 2013), since the determination of decay phases was questionable and correct results are presented here. New data is also presented herewith. For water measurements, the MSA 323S scale (Sartorius, Germany) with YDK01 Density Determination Kit (Sartorius, Germany) was used for the first time in our labs. We measured density of coarse woody debris from the secondary virgin forest reserve Rajhenavski Rog, Slovenia. Results of the two methods employed were not comparable due to different density definitions. Also, lower densities in higher decay phases were not detected, although expected. Nevertheless, the scale MSA 323S proved to be a reliable method of measuring wood sample density in water. However, some optimizations will have to be considered in the future
The role of economics in forest planning and policy evaluation in Slovenia
No full textThis paper explores the current status of the forest sectors in Slovenia, identifies potential issues in the management and use of the forests, and discusses a means by which policy makers can identify opportunities to enhance the role played by forests and their related goods and services in Slovenia. Specifically, a framework is proposed to assess the relationships between the economic, social, and ecological aspects of Slovenia%s forests; effects of changes in economic conditions on forest demands and uses; economic impacts of ecological, social, and business conditions; effects of current or proposed policies; and opportunities for the sustainable economic development of wood-based and forest-dependent enterprises. Such a framework is critical for managing Slovenia's forests and forestry sector in such a manner to optimize the ecological and economic potential
Early Roman barge from the Ljubljanica River at Sinja Gorica
No full textPreventive underwater archaeological surveying in the bed of the Ljubljanica River, conducted at Sinja Gorica in
2008, revealed the remains of an Early Roman wooden barge from the beginning of the 1st century AD. Detailed documentation of the 4.5m long and 2.8m wide section of the boat followed in October 2012 and included photogrammetric
three-dimensional modelling. The construction characteristics and size revealed a boat of the Mediterranean shipbuilding tradition, with an elongated oval shape and a flat bottom and vertical sides, constructed using the shell-first technique and planks fastened with iron clamps, while the hull was reinforced with floor-timbers in a manner not yet published in the relevant literature. The barge, made mostly of beech wood, was built soon after AD 3 according to the dendrochronological analysis. The wood is very poorly preserved. The barge was presumably used to transport cargo between Nauportus and Emona