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The impact of toxic elements (TEs) contaminating the root zone of Lupinus angustifolius L. on enzymatic activities, nitrification rate, and changes in the root system was evaluated. Lupine was cultivated in a pot experiment using two types of soil - control and contamination (with a high degree of arsenic (As), cadmium (Cd), lead (Pb), and zinc (Zn) contamination). After harvesting lupine biomass, enzyme activities (β-glucosidase, acid phosphatase, arylsulphatase, lipase, chitinase, cellobiohydrolase, alanine aminopeptidase, and leucine aminopeptidase) in soils were analysed. Enzyme activities decreased with TE soil contamination. According to our results, arylsulphatase was found to be the most sensitive soil enzyme to TEs. The nitrification rate is closely related to soil contamination and plant activity, as it stimulates microbial growth and multiplication through root exudates. The close correlations confirmed this relationship (r = 0.73-0.99). An increasing trend in TE contents in the roots was observed with soil contamination. Plant hormones are crucial in regulating root growth and development under stress conditions. The levels of determined phytohormones in our experiment (auxins, abscisic acid (ABA), salicylic acid (SA), and bioactive cytokinins (bCKs)) were lower in the contamination compared to the control. Correlations confirmed a significant negative relationship between the TE content in the roots and the contents of phytohormones (auxins: r = -0.96 to -0.97; ABA: r = -0.83 to -0.86; SA: r = -0.95 to -0.99, bCKs: r = -0.87 to -0.93). The ratios of these hormones (not their absolute values) appear to be the determining factor for regulating root development and protecting plants from oxidative stress. [ABSTRACT FROM AUTHOR]

Chemical compositions and mineral assemblages of tourmalines from the elbaite-subtype Manjaka pegmatite in the Sahatany Valley, central Madagascar, and its exocontact were examined using EPMA and LA-ICP-MS. Several textural, compositional and paragenetic types of tourmalines were recognized in the individual pegmatite units and in the zones located towards the host rock in the order: wall pegmatite unit → border pegmatite unit → contact zone → recrystallization zone; the latter zone evidently originated after the host Mg-rich calc-silicate rock (Di + Tr + Qz > Pl + Kfs ˃ Phl + Dol ˃ Cal). Zoned prismatic crystals from the border unit evolved from the core Tur Ia (dravite < Fe-rich elbaite), Tur Ib (Mn,Fe-rich to Mn-rich fluor-elbaite > elbaite), to the crystal rims Tur II (elbaite > darrellhenryite) via the substitutions: (1) 2YR2+ = YLiAl, (2) YMnWF = YFe2+WOH, (3) YLi0.5 WOH = YAl0.5 WO, and (4) YLiTAlWOH3 = YAlTSiWO3. The contact zone, ~2 mm thick, contains abundant Tur IV (Li,Fe,Al-enriched dravite > oxy-dravite), and the recrystallization zone, ~1.5 cm thick, common Tur V (fluor-uvite > dravite > fluor-dravite, magnesio-lucchesiite, uvite) via the substitutions: (1) 2YR2+ = YLiAl and (5) YR2+WOH = YAlWO, (6) XNaWOH = XCaWO and (7) XNaYAl = XCaYR2+. The chemical compositions of the individual types of tourmalines suggest that the mobility of elements between calc-silicate rock and pegmatite was low. Only weak influx of Mg, V and Cr into pegmatite and Li and Al from the pegmatite to the host rock - recrystallization zone, respectively, were observed. The existence of thin B-rich contact zone with dominant Tur IV suggests low influx of B into the host rock in early magmatic stage. High contents of F in Tur V from the recrystallization zone were very likely triggered by influx of B,F-enriched residual pegmatite fluids. Very high a(B2O3), but low a(H2O) and a(F) in the pegmatite melt constrained very low degree of external contamination of the pegmatite. Compositional evolution in tourmalines from Manjaka was compared with the pegmatites and their exocontact at Stoffhütte, Koralpe, Austria, and Bližná I, Moldanubian Zone, Czech Republic. [ABSTRACT FROM AUTHOR]

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Geological position, mineral assemblages, and compositional evolution of several types of mostly hydrothermal zeolite mineralizations were examined in the easternmost part of the Moldanubian Zone (Strážek Unit), Czech Republic, using EPMA and Raman spectroscopy. The zeolite mineralizations are related to the following geological processes: (A1) late magmatic to (A2, A3) hydrothermal crystallization (pseudomorphs, brittle tectonic fractures) in granitic pegmatites; (B) retrograde stages of the Variscan metamorphism - (B1) Alpine-type hydrothermal veins on ductile to brittle fractures with epidote, prehnite and zeolites, (B2) laumontite and (B3) natrolite veinlets; the latter two on thin brittle fissures; (C) hydrothermal zeolite veins with dominant stilbite-(Ca) + heulandite-(Ca) and sulfides on ductile to brittle fractures, and (D) thin brittle fissure-filling veinlets lined with harmotome ± calcite. The zeolite mineralizations include pollucite (A), analcime (A, B), phillipsite-(Ca) (A), harmotome (A, D), chabazite-(Ca) and chabazite-(K) (A, B), thomsonite-(Ca) (A), natrolite (A, B), laumontite (A, B, C), stilbite-(Ca) (B, C), scolecite (B), and heulandite-(Ca) (B, C). The individual zeolite mineralizations differ significantly in their regional distribution: (B) Alpine-type hydrothermal veins and laumontite and natrolite veinlets are widespread within almost the whole region, whereas zeolites in (A) granitic pegmatites and in (C, D) hydrothermal veins are concentrated along the eastern border of the Strážek Unit, the latter two assemblages restricted to the Rožná-Olší ore field. Fluids with variable composition and origin facilitated the formation of individual zeolite mineralizations. They evolved from moderate-T (~400 °C) to low-T (~50 °C) conditions characterized by the following extra-framework cations ± volatiles with dominant H2O: (A1) - Cs, Ba, Ca, Na ˃ K, (A2) - Ca, K, Ba ˃ Na, (A3) - Ca, Na, Ba (A: T ~400-50 °C); (B1) - Ca ± B, (B2) - Ca, (B3) - Na, Ca (B: T ~350-50 °C); (C) - Ca ˃ Na ± S, F (C: T ~240-50 °C); (D) - Ba, Ca ± CO2 (D: T ~100-50 °C). Sources of fluids include - residual fluids exsolved from pegmatite melt (A1) and external fluids derived from host rock (A2, A3); fluids related to retrograde stages of the Variscan metamorphism (A3?, B1, B2, B3, C?); likely post-Variscan fluids of various origin (C, D). The zeolite assemblages demonstrate that the PTX conditions suitable for their origin were attained in the late stages of distinctive geological processes. Zeolites may be used as a valuable indicator of alkaline to neutral and low-T to very low-T hydrothermal fluids with high activity of Ca, K, Na and/or Ba, and variable aSiO2 on tectonic fractures and fissures. [ABSTRACT FROM AUTHOR]

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