Browsing by Subject "Minerals"

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  • Jokinen, Kari; Salovaara, Anna-Kaisa Johanna; Wasonga, Daniel; Edelmann, Minnamari; Simpura, Ilkka; Mäkelä, Pirjo (2022)
    Leafy vegetables like lettuce (Lactuca sativa L.) naturally have high nitrate content and the European Commission has set maximum level for nitrate in lettuce. Glycinebetaine is an organic osmolyte alleviating plant stress, but its role in leaf nitrate accumulation remains unknown. The uptake of glycinebetaine by lettuce roots, and its potential to regulate lettuce nitrate content and improve plant quality were investigated. Two hydroponic lettuce experiments were conducted with different glycinebetaine application rates (Exp1 : 0, 1, 7.5, and 15 mM; Exp2: 0, 1 + 1 + 1, 1 + 10, and 4 mM). Plants were analyzed at varying time points. Root application resulted in glycinebetaine uptake and translocation to the leaves. Glycinebetaine concentrations > 7.5 mM reduced leaf nitrate up to 40% and increased leaf dry matter content. Glycinebetaine showed a positive effect on leaf mineral and amino acid composition. Thus, glycinebetaine could be a novel strategy to reduce the nitrate content in hydroponic lettuce.
  • Nenonen, Ville; Dick, P.; Sammaljärvi, Juuso; Johansson, B.; Voutilainen, Mikko; Siitari-Kauppi, Marja (EAGE, 2019)
    The porosity distribution and mineralogical changes in a clay-rich fault core from the Tournemire underground research laboratory are analyzed to determine the mechano-chemical processes in a small-scale vertical strike-slip fault. The results display significant spatial variations in porosity and mineralogy along different gouge zones due to a polyphased tectonic history combined with complex paleo-fluid migrations. Porosity values increase from the center of the gouges to their borders indicating diffusive sealing/healing effects and past hydrothermal activities. The healing and thus the strengthening of the fault is marked by an increase of calcium content, which is concurrent with lower porosities around the gouge zone. Chemical mapping in the gouges reveal clay alteration, iron zonality and the presence of zinc sulphide as well as barium sulphate inside the gouge, further suggesting past hydrothermal activity. Finally, even though the observed porosity variations only occur in subcentimeter-thick gouge bands, the higher porosity sections are pathways for fluid flow during fault activity. © 5th International Conference on Fault and Top Seals 2019. All Rights Reserved.
  • Li, Xiaodong; Puhakka, Eini; Ikonen, Jussi; Söderlund, Mervi; Lindberg, Antero; Holgersson, Stellan; Martin, Andrew; Siitari-Kauppi, Marja (2018)
    The sorption behavior of Se(IV) on Grimsel granodiorite and its main minerals, plagioclase, K-feldspar, quartz and biotite, were investigated in Grimsel groundwater simulant in a large Se concentration range (from 1.66 x 10(-10) M to 1 x 10(-3) M). Experimental results show that the distribution coefficients (K-d values) of Se (IV) on the rock and mineral samples increased with the decreasing of Se(IV) concentration. The sorption of Se (IV) on biotite has the largest K-d value in low concentration area (<10(-7) M) stabilizing between 0.0595 +/- 0.0097 m(3)/Kg and 0.0713 +/- 0.0164 m(3)/Kg. The Kd value of Se(IV) on K-feldspar was the second largest (0.0154 +/- 0.0019 m(3)/Kg in 10(-9) M) while the sorption on quartz was negligible. The sorption behavior of Se(IV) on Grimsel granodiorite followed the same trend as plagioclase, the most abundant mineral in Grimsel granodiorite, with K-d values of 0.0078 +/- 0.0010 m(3)/Kg for Grimsel granodiorite and 0.0085 +/- 0.0016 m(3)/Kg for plagioclase, when Se(IV) concentration was 10(-9) M. HPLC-ICP-MS results show that all the Se(IV) remained in + IV oxidation state after more than 1 month experimental time and speciation modelling proved that the main species in Grimsel groundwater simulant were HSeO3- and SeO32-. Multi-site surface complexation modelling was performed by PHREEQC with the help of molecular modelling techniques which was performed with the CASTEP code implemented into Materials Studio. The modelling results predict that there are three kinds of sorption sites on the surface of biotite mineral, with sorption site densities differing in three magnitudes.