This study is dedicated to laboratory investigation of sorption behavior of polycyclic aromatic hydrocarbons in soils under equilibrium and non-equilibrium conditions. Six soils from Slovakia with different organic carbon fraction (fOC = 0.0048-0.0241), clay fraction (fCM = 0.006-0.372) and mineralogical composition of clays were used for determination of naphthalene, acenaphthene, fluorene, phenanthrene and pyrene sorption isotherms. Impact of sorption contact time on sorption behavior of studied PAHs was evaluated by measured distribution relationships S(t) vs. C(t) for naphthalene, phenanthrene and pyrene in one soil sample at contact time of 2 hours, 1 day, 2 days (3 for pyrene) and 21 days. The experimental sorption isotherms were nonlinear and fitted very well with the Freundlich adsorption isotherm: S = KFCe N over a range of used aqueous phase PAH concentrations. The more detailed analysis of results showed that soil organic carbon was predominant sorbent in the sorption of investigated polycyclic aromatic hydrocarbons from aqueous solution by soils, although it was found that sorption behavior of PAH compounds in soils was significantly affected by smectites when organic carbon/smectite ratio was roughly below 0.1 (fOC/fsmectite ~0.1). The results also showed that average distribution coefficient KD values and the normalized to organic car-bon content KOC of studied PAH compounds, despite observed nonlinear sorption, were comparable with their values earlier published in the literature and were dependent on their molecular properties: hydrophobicity expressed as KOW and water solubility SW. All observed distribution relationships for contact times used fitted to a power function reflecting non-equilibrium conditions: S(t) = kF(t)C(t) n(t) . The data indicate significant increase in sorption of naphthalene between 2 h and 1 d, phenanthrene between 2 h and 2 d and pyrene at interval of 2 h to 21 d. This observation suggests that more hydrophobic PAH compounds exhibit slower sorption kinetics than less hydrophobic compounds like naphthalene. Observed changes in sorption of PAHs studied as contact time increased indicate that literature KD and KOC values for many organic compounds can be significantly underestimated as were measured over short periods (≤ 1 d) because short periods not need always represent equilibrium conditions during realized batch experiments. and Štúdia sa venuje laboratórnemu výskumu sorpcie polycyklických aromatických uhľovodíkov v pôdach v rovnovážnych a nerovnovážnych podmienkach. Na stanovenie rovnovážnych sorpčných izoteriem naftalénu, acenafténu, fluorénu, fenantrénu a pyrénu sme použili šesť vzoriek pôd s rozdielnym podielom organického uhlíka (fOC = 0,0048-0,0241), ílovitej frakcie (fCM = 0,006-0,372) a odlišným mineralogickým zložením ílovitej frakcie. Vplyv času na sorpčné správanie študovaných PAU bol sledovaný pomocou experimentálne stanovených závislostí S(t) od C(t) pre naftalén, fenantrén a pyrén a jednu vzorku pôdy v čase 2 hodiny, 1 deň, 2 dni (3 pre pyrén) a 21 dní. V rozsahu použitých koncentrácií PAU vo vodnom roztoku mali získané rovnovážne sorpčné izotermy nelineárny tvar a veľmi dobre vyhovovali Freundlichovej adsorpčnej izoterme: S = KFCe N . Detailnejší rozbor dosiahnutých výsledkov ukázal, že organický uhlík má najväčší vplyv na rovnovážne sorbované množstvo jednotlivých PAU v pôdach, aj keď od určitého podielu ílovitej frakcie, zvlášť smektitov môže byť sorpčné správanie PAU výrazne ovplyvnené práve prítomnými smektitmi. Tento vplyv sa začína prejavovať pri hodnote pomeru organického uhlíka k smektitom približne 1 : 10 alebo pri pomere fOC/fsmektit ~0,1. Výsledky tiež ukázali, že aj napriek pozorovanej nelineárnej sorpcii priemerné hodnoty koeficientov rozdeľovacích (KD) a normalizovaných na podiel organického uhlíka KOC sú porovnateľné s hodnotami publikovanými v literatúre a záviseli od molekulových vlastností PAU: od miery hydrofóbnej povahy vyjadrenej rozdeľovacím koeficientom v sústave n-oktanol-voda KOW a rozpustnosti vo vode SW. Všetky pozorované závislosti S(t) od C(t) v jednotlivých časoch vyhovovali rovnici mocninovej funkcie v tvare: S(t) = kF(t)C(t) n(t) . Namerané výsledky poukazujú na významný nárast v sorbovanom množstve naftalénu v intervale 2 hod až 1 deň, fenantrénu v čase medzi 2 hod až 2 dňami a pyrénu v intervale 2 hod až 21 dní. Toto zistenie naznačuje, že na dosiahnutie rovnováhy hydrofóbnejších PAU je potrebný dlhší čas ako u menej hydrofóbnych. Uvedená štúdia tiež ukazuje, že mnohé publikované hodnoty KD a KOC rôznych organických látok v literatúre môžu byť výrazne podhodnotené, pretože boli namerané v krátkom čase (≤ 1 deň), ktorý nemusí vždy reprezentovať rovnovážne podmienky počas realizácie sorpčných experimentov.
Adsorption procedure of two cationic surfactants hexadecyltrimethylammonium bromide (HDTMABr) and benzyldimethylhexadecylammonium chloride (BDHDACl) onto two samples of montmorillonite was studied. Infrared spectroscopy and X-ray diffraction proved intercalation of both quaternary cations into the interlayer space of montmorillonite. An aspect of time showed not to be important for the cations adsorption., Zuzana Navrátilová, Petr Wojtowicz, Lenka Vaculíková and Věra Šugárková., and Obsahuje bibliografické odkazy
A combined sorbent was prepared by impregnation of lignite mined in the South Moravian Coalfield, Czech Republic, with chitosan. Sorption performance of the combined sorbent and the untreated lignite was tested for Co(II), Cu(II), and Cd(II) in equilibrium sorption experiments with respect to pH and metal concentration. The amount of metal retained by the sorbent was determined by instrumental neutron activation analysis in the short time irradiation mode with epithermal neutrons. For pH~5, sorption isotherms were determined and fitted using the Langmuir and Freundlich models. The results have been compared with those obtained previously for similar combined sorbent based on naturally oxidized coal mined in the Sokolov Basin, Czech Republic. It has been shown that the effect of chitosan on sorption efficiency of the chitosan-doped coal sorbents strongly depends on solution pH, and type of coal and metal., Martina Havelcová, Jiří Mizera, Vladimír Machovič, Lenka Borecká, Oldřich Přibyl and Ivana Krausová., and Obsahuje bibliografii
Ritualizované souboje patří k nejnápadnějším interakcím samečků ještěrek čeledi Lacertidae. V případě ještěrky zelené mají tyto souboje více či méně stereotypní průběh a sestávají se z pěti základních fází. Tyto fáze jsou popsány a fotograficky dokumentovány v případě konkrétní populace ještěrek zelených z blízkého okolí Prahy. and Ritualised combats are the most remarkable male-male interactions in lacertid lizards. In the Lacerta viridis male-male combats run a more or less stereotypical course consisting of five basic phases. Individual combat phases are described and documented in the case of the wild population of L. viridis living in close vicinity to Prague.
Czech botanists have participated in research into the taxonomy, diversity and ecology of plants in the equatorial high Andes since the mid 90s. The results include a description of new species of vascular plants and lichens, a contribution to generic flora, one monography and publication of several dozen original papers. and Petr Sklenář.
The virgin forests of the Krkonoše Mts. have been transformed into less stable spruce monocultures due to economic activities in the past. The objective of the current management of forest ecosystems is to create a compact core area of a sufficient size capable of autoregulation processes. Surrounding areas should be managed in ways that protect and conserve native biodiversity. Conservation efforts should be coordinated between the Czech and Polish sides of the Krkonoše Mts. and Otakar Schwarz.