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See detail90Sr, 210Pb, 210Po and Ra isotopes in marine macroalgae and mussel Mytilus galloprovincialis from the Bulgarian Black Sea zone
Tosheva, Zornitza UL; Nonova, Tzvetana

in Journal of Radioanalytical & Nuclear Chemistry (2015)

90Sr, 210 Pb, 210Po and Ra isotopes were determined in macroalgae Ceramium rubrum, Cystoseira crinita, Ulva rigida, Cladophora vagabunda, Enteromor- pha intestinalis and in mussels Mytilus ... [more ▼]

90Sr, 210 Pb, 210Po and Ra isotopes were determined in macroalgae Ceramium rubrum, Cystoseira crinita, Ulva rigida, Cladophora vagabunda, Enteromor- pha intestinalis and in mussels Mytilus galloprovincialis collected from the Bulgarian Black Sea coast. Radio- chemical separation was made by a fast and reproducible procedure based on a calcium phosphate precipitation technique. The obtained results for macroalgae vary in the interval 0.23–0.85 Bq kg-1 for 90Sr, 2.2–10.6 Bq kg-1 for 210Pb, 1.2–9.7 Bq kg-1 for 210Po and 1.9–13.2 Bq kg-1 for Ra isotopes. Data obtained for mussels demonstrate similar abilities in the accumulation of 90Sr, 210Pb and Ra isotopes. [less ▲]

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See detailWater Chemistry and Hydrometeorology in a Glacierized Catchment in the Polar Urals, Russia
STACHNIK, Łukasz1; WAŁACH, Piotr; UZAROWICZ, Łukasz et al

in Journal of Mountain Science (2014), 11(5), 1097-1111

This study aims to determine the relationships between local meteorological conditions, proglacial river discharge and biogeochemical processes operating in a periglacial basin located in the Polar Ural ... [more ▼]

This study aims to determine the relationships between local meteorological conditions, proglacial river discharge and biogeochemical processes operating in a periglacial basin located in the Polar Ural mountain range, Russia. Fieldwork was conducted in the catchment of Obruchev Glacier (13 km2) during the summer peak flow period in 2008. River discharge was dominated by snowmelt and changed from 3300 l s-1 to less than 1000 l s-1. The mean daily air temperatures of stations situated in the mountain tundra and near Obruchev Glacier from July 11th to August 1st 2008 were 14.4°C and 10.3°C, respectively. The glacial river had low total dissolved solids varying from 4.5 to 9 mg l-1 and coefficients of correlation between Na+ and Cl-, K+ and Cl-, as well as NH4+ and Cl- were 0.94, 0.90 and 0.84, respectively. Rainfall events affected the snowmelt initiation and provided an essential part of the discharge during the intense snowmelt period, which occurred from July 11th to July 18th 2008. Data showed that Na+ and K+ in the surface water derived from snowmelt rather than chemical weathering of silicates. Also, it was obtained that NO3- derived from the melting snowpack, whereas ammonification occurring under the snowpacks was the primary source for NH4+. [less ▲]

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See detailCesium and strontium in Black Sea macroalgae
Nonova, Tzvetana; Tosheva, Zornitza UL

in Journal of Environmental Radioactivity (2014), 129

The trace level of metals and particularly radioactive ones should be monitored to evaluate the transfer along the trophic chain, assess the risk for biota and can be used for global changes assessment ... [more ▼]

The trace level of metals and particularly radioactive ones should be monitored to evaluate the transfer along the trophic chain, assess the risk for biota and can be used for global changes assessment. Plants respond rapidly to all changes in the ecosystem conditions and are widely used as indicators and pre- dictors for changes in hydrology and geology. In this work we represent our successful development and applications of a methodology for monitoring of stable and radioactive strontium and cesium in marine biota (Black Sea algae’s). In case of radioactive release they are of high interest. We use ED-XRF, gamma spectrometers and LSC instrumentation and only 0.25 g sample. Obtained results are compared with those of other authors in same regions. The novelty is the connection between the radioactive isotopes and their stable elements in algae in time and space scale. All our samples were collected from Bulgarian Black Sea coast. [less ▲]

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See detailIncrease of apatite dissolution rate by Scots pine roots associated or not with Burkholderia glathei PML1(12)Rp in open-system flow microcosms
Calvaruso, Christophe; Turpault, Marie-Pierre; Frey-Klett, Pascale et al

in Geochimica et Cosmochimica Acta (2013), 106

The release of nutritive elements through apatite dissolution represents the main source of phosphorus, calcium, and several micronutrients (e.g., Zn, Cu) for organisms in non-fertilized forest ecosystems ... [more ▼]

The release of nutritive elements through apatite dissolution represents the main source of phosphorus, calcium, and several micronutrients (e.g., Zn, Cu) for organisms in non-fertilized forest ecosystems. The aim of this study was to quantify, for the first time, the dissolution rate of apatite grains by tree roots that were or were not associated with a mineral weathering bacterial strain, and by various acids known to be produced by tree roots and soil bacterial strains in open-system flow microcosms. In addition, we explored whether the mobilization of trace elements (including rare earth elements) upon apatite dissolution was affected by the presence of trees and associated microorganisms. The dissolution rate of apatite by Scots pine plants that were or were not inoculated with the strain Burkholderia glathei PML1(12)Rp, and by inorganic (nitric) and organic (citric, oxalic and gluconic) acids at pH 5.5, 4.8, 3.8, 3.5, 3.0, and 2.0 was monitored in two controlled experiments: “plant–bacteria interaction” and “inorganic and organic acids”. Analyses of the outlet solutions in the “plant–bacteria interaction” experiment showed that Scots pine roots and B. glathei PML1(12)Rp produced protons and organic acids such as gluconate, oxalate, acetate, and lactate. The weathering budget alculation revealed that Scots pines (with or without PML1(12)Rp) significantly increased (factor > 10) the release of Ca, P, As, Sr, Zn, U, Y, and rare earth elements such as Ce, La, Nd from apatite, compared to control abiotic treatment. Scanning electron microscopy observation confirmed traces of apatite dissolution in contact of roots. Most dissolved elements were taken up by Scots pine roots, i.e., approximately 50% of Ca, 70% of P, 30% of As, 70% of Sr, 90% of Zn, and 100% of U, Y, and rare earth elements. Interestingly, no significant additional effect due to the bacterial strain PML1(12)Rp on apatite dissolution and Scots pine nutrition and growth was observed. The “inorganic and organic acids” experiment demonstrated that the apatite dissolution efficacy of organic acids was higher than for the inorganic acid and varied in function of the acids: oxalic acid > citric acid > gluconic acid > nitric acid for pH 63.5. In addition, apatite dissolution increased with increasing acidity for each acid. Only oxalic acid generated non-stoichiometric release of calcium and phosphorus from apatite in the solution at pH 63.5, due to the precipitation of Ca-oxalate crystals at apatite surfaces. Comparison of the experiments revealed that the apatite dissolution rate by Scots pines supplied with nutritive solution at pH 5.5 reached 2.0 10 13 mol cm 2 s 1 and Altogether our results highlight that, through the production of weathering agents, notably protons and organic acids, tree roots and root-associated microorganisms are able to significantly increase the release of macro- and micro-nutrients from apatite, thus maintaining high-nutrient conditions to support their growth. [less ▲]

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