EJPAU, 2020, Volume 23, Issue 1

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23(1) #01
02 Jan 2020
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Spartina pectinata Link (prairie cordgrass) is a plant that can grow in a wide range of environmental conditions. The aim of this study was to describe the development, morphological traits, dry mass accumulation and chemical composition of this plant in container cultivation under marshy conditions. The water level was at the same level as the ground surface. Based on the test results it can be concluded that Spartina pectinata can grow under wetlands and confined space conditions. However, such a research environment causes that the density of shoots per 1 m2 was at the end of vegetation from 155 to 888 units, and the diameter of shoots was around 3 mm. The appearance of new shoots was observed during the entire vegetation period. Prairie cordgrass produced more and more shoots and inflorescences every year, as well as more and more underground and aboveground mass of plants. The ratio of shoots to roots and rhizomes was 1:1.48.

23(1) #02
31 Jan 2020
Civil Engineering
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The paper shows that in order to increase the efficiency of hydraulic transport systems in mining the transportation of slurries with a high concentration of solids in the slurry flow. Experimental studies have shown that slurry tailings of gold-containing ore with mass concentration of more than 55% are viscoplastic fluids. Experiments on a rotational viscometer allowed us to establish the main rheological characteristics of the studied slurries. Experimental studies of hydraulic transport performed on a laboratory setup, confirmed the results obtained on a rotational viscometer. Curved mixture streams are inclined straight lines that cut off on the axis of the head the sections, which determine the initial hydraulic slope corresponding to the shear stress yield on the rheological curves. According to the results of the experiments, a method has been developed for calculating the hydraulic transport of highly concentrated slurries of tailings of gold-bearing ore. Head loss values increase with increasing concentration. A sharp increase in head loss occurs in the concentration range from 60 to 65% and above

23(1) #03
04 Feb 2020
Environmental Development
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Finnish soil temperature regimes have been pergelic, cryic, and frigid, where pergelic is coldest and unsuitable for agricultural use. The study monitored soil temperatures at a soil depth of 50 cm in 2010, 2013, 2016 and 2019 to look at how the soil temperature regimes have changed. Probably, as a result of climate warming the soil temperature regimes in Southern Finland in the Helsinki region at a latitude of 60–61°N have raised from cryic and pergelic to warmer mesic over a period of ten years.

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