Jan Milicka

Sedimentology and hydrocarbon habitat of the submarine-fan deposits of the Central Carpathian Paleogene Basin (NE Slovakia)

Abstract The Central Carpathian Paleogene Basin accommodates a subsiding area of the destructive plate-margin. The basin history comprises marginal faulting and alluvial fan accumulation (E 2 ); transgressive onlap by shoreface sediments and carbonate platform deposits (E 2 ); glacio-eustatic regression induced by cooling (Terminal Eocene Event); forced regression, tectonic subsidence and growth-fault accumulation of basin-floor and slope fans (E 3 ); decelerating subsidence, aggradation and sea-level rising during the mud-rich deposition (O 1 ); high-magnitude drop in sea-level (Mid-Oligocene Event), retroarc backstep of depocenters and lowstand accumulation of sand-rich fans and suprafans (O 2 –M 1 ); subduction-related shortening and basin inversion along the northern margins affected by backthrusting and transpressional deformation (O 2 –M 1 ). The basin-fill sequence has poor (TOC≤0.5%) to fair (TOC

Effect of soil and sediment composition on acetochlor sorption and desorption

Background, aim, and scopeHerbicide fate and its transport in soils and sediments greatly depend upon sorption–desorption processes. Quantitative determination of herbicide sorption–desorption is therefore essential for both the understanding of transport and the sorption equilibrium in the soil/sediment–water system; and it is also an important parameter for predicting herbicide fate using mathematical simulation models. The total soil/sediment organic carbon content and its qualitative characteristics are the most important factors affecting sorption–desorption of herbicides in soil or sediment. Since the acetochlor is one of the most frequently used herbicides in Slovakia to control annual grasses and certain annual broad-leaved weeds in maize and potatoes, and posses various negative health effects on human beings, our aim in this study was to investigate acetochlor sorption and desorption in various soil/sediment samples from Slovakia. The main soil/sediment characteristics governing acetochlor sorption–desorption were also identified.Materials and methodsThe sorption–desorption of acetochlor, using the batch equilibration method, was studied on eight surface soils, one subsurface soil and five sediments collected from the Laborec River and three water reservoirs. Soils and sediments were characterized by commonly used methods for their total organic carbon content, distribution of humus components, pH, grain-size distribution, and smectite content, and for calcium carbonate content. The effect of soil/sediment characteristics on acetochlor sorption–desorption was examined by simple correlation analysis.ResultsSorption of acetochlor was expressed as the distribution coefficient (Kd). Kd values slightly decreased as the initial acetochlor concentration increased. These values indicated that acetochlor was moderately sorbed by soils and sediments. Highly significant correlations between the Kd values and the organic carbon content were observed at both initial concentrations. However, sorption of acetochlor was most closely correlated to the humic acid carbon, and less to the fulvic acid carbon. The total organic carbon content was found to also significantly influence acetochlor desorption.DiscussionSince the strong linear relationship between the Kd values of acetochlor and the organic carbon content was already released, the corresponding Koc values were calculated. Considerable variation in the Koc values suggested that other soil/sediment parameters besides the total soil organic carbon content could be involved in acetochlor sorption. This was revealed by a significant correlation between the Koc values and the ratio of humic acid carbon to fulvic acid carbon (CHA/CFA).ConclusionsWhen comparing acetochlor sorption in a range of soils and sediments, different Kd values which are strongly correlated to the total organic carbon content were found. Concerning the humus fractions, the humic acid carbon content was strongly correlated to the Kd values, and it is therefore a better predictor of the acetochlor sorption than the total organic carbon content. Variation in the Koc values was attributed to the differences in distribution of humus components between soils and sediments. Desorption of acetochlor was significantly influenced by total organic carbon content, with a greater organic carbon content reducing desorption.Recommendations and perspectivesThis study examined the sorption–desorption processes of acetochlor in soils and sediments. The obtained sorption data are important for qualitative assessment of acetochlor mobility in natural solids, but further studies must be carried out to understand its environmental fate and transport more thoroughly. Although, the total organic carbon content, the humus fractions of the organic matter and the CHA/CFA ratio were sufficient predictors of the acetochlor sorption–desorption. Further investigations of the structural and chemical characteristics of humic substances derived from different origins are necessary to more preciously explain differences in acetochlor sorption in the soils and sediments observed in this study.

Geological model of Lobodice underground gas storage facility based on 3D seismic interpretation

Abstract The Lobodice underground gas storage (UGS) is developed in a natural aquifer reservoir located in the Central Moravian part of the Carpathian Foredeep in the Czech Republic. In order to learn more about the UGS geological structure a 3D seismic survey was performed in 2009. The reservoir is rather shallow, 400–500 m below the surface. This article describes the process workflow from the 3D seismic field data acquisition to the creation of the geological model. The outcomes of this workflow define the geometry of the UGS reservoir, its tectonics and the sealing features of the structure. Better geological knowledge of the reservoir will reduce the risks involved in the localization of new wells for increasing UGS withdrawal rates.