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Influence of sorbents on retention curve of contaminated fluvisol
Hnatajková, Eva ; Jačka, Lukáš (advisor) ; Pavlásek, Jiří (referee)
The thesis deals with the influence of sorbents on the retention curve of the contaminated alluvial soil (fluvisol). The retention curves of soil without sorbents (reference soil) are compared with the soils enriched by the following sorbents. Biochar (BC), amorphous manganese oxide (AMO) and combination of (AMO + BC). Soils sample were collected is specific uncultivated area in the valley of Litavka river (located in the central part of the Czech republic).
Two different types of samples were used for measurement of retention curves. First type of the samples were collected from the column experiments and second type were the samples collected in the field. All samples were extracted using in Kopecky rings (100 cm3). The measurement of the retention curves was performed by a direct method in the laboratory. For laboratory determination of the retention curves classical set of instruments were used (sandbox, sand-kaolin box and pressure apparatuses). The measured data were fitted using van Genuchten. Values compared are the bulk density, parameters of van Genuchten model (Thétas, ThétaR, Alfa, n), and values pF (0; 1.0; 2.0; 2.7; 3.0; 3.7; 4.18). The comparison of retention curves of differently treated soil was based on the average, standard deviation and the difference and ratio of the avarages.
According to presented findings sorbents affected shapes of the retention curves. Especially biochar influence water content for high pF values. We confirmed the hypothesis according to VERHEIJEN et al. (2010), that biochar tincrase the total retention of soil water, but does not increase the amoust of water avaible plants.
The influence of AMO on retention curve was negligible. Therefore sorbent AMO has a small influence on change of water retention in the tested soil. The effect of combined sorbent (AMO + BC) on the retention more significant than effect of using AMO sorbent only. This combination of sorbents affects the water retention depending on applied pF.
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Influence of biochar on saturated hydraulic conductivity of contaminated fluvisol
Tomáš, Tomáš ; Jačka, Lukáš (advisor) ; Pavlásek, Jiří (referee)
This thesis deals with the influence of biochar on saturated hydraulic conductivity (Ks) of contaminated fluvisol. Values of Ks are key inputs for modeling of water flow in soils. Contaminated fluvisol and this soil enriched by 2 and also 5% of biochar were studied in this thesis. These differently treated soils ware gauged to find out differences in Ks and changes of Ks time. Biochar improves sorption capacity and other soil properties. The influence of biochar application on Ks it not fully revealed. We used biochar which was made by pyrolysis of stalks of grapevine.
Measurements were made in two series since October to December in 2015. For both series, 10 samples, (5 in reference and 5 enriched by biochar) were measured. A total of 20 samples were measured in each series. Every sample was measured for 14 days in 10 time steps (10 recurrent measurements). Physical properties (bulk density, porosity, saturated water content) and particle size analysis using hydrometer method were also measured. Homogeneous soil mixtures of the soils were packed in Kopeckého sampling rings (100 cm3). In first series, 5 reference samples and 5 samples with 2% content of biochar were compared. Saturation of the samples was made gradually and slowly and takes 1 week. Measurement was made by laboratory permeameter (hydraulic gradient about 0.5).
For reference samples of first series, mean Ks value was 4,818.10-6 m.s-1. For samples enriched by 5% biochar mean Ks value was 2,254.10-6 m.s-1. For reference of second series, mean Ks value was 6,435.10-6 m.s-1. For samples enriched by 2% biochar mean Ks value was 4,211.10-6 m.s-1.
Application of biochar on tested soil decrease Ks in comparison with reference soil. Decrease of Ks value was more distinct for soil enriched 5% of biochar than for soil enriched by 2% of biochar. Application of biochar also decrease coefficient of variation of measured Ks. in most of the time steps. Reference samples exhibited larger differences of Ks among time steps than biochar enriched soils.
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