Analysis of elements in lake sediment samples by PIXE spectrometry

Bioprospecting for Novel Halophilic and Halotolerant Sources of Hydrolytic Enzymes in Brackish, Saline and Hypersaline Lakes of Romania

“…Based on water salinity, the investigated environments were of three types: brackish (AM and BA), saline (CB) and hypersaline (MM and BSL). Their alkaline pH (8-10) was slightly higher than previously reported [21][22][23][24][25][26][27], and the relatively elevated water temperatures (23-39 • C) were due to the shallow depths of these water bodies during the dry periods. Dissolved oxygen (DO) concentrations decreased with the increase in salt levels and were generally low (0.3-4.6 mg•L −1 ), with the only exception of AM where higher amounts (10-12.8 mg•L −1 ) were measured.…”

“…In this respect, it is interesting to note that halotolerant and moderately halophilic microorganisms dominated over the extremely halophilic ones even in the hypersaline lakes MM and BSL (Figure 2). This finding could have been related to the large salinity fluctuations periodically encountered in these environments [21][22][23][24][25][26][27]. Furthermore, considering the generally accepted statement that cultivable microorganisms represent only a small fraction of microbial communities [53], the results reported in the present study could have looked very different from a metagenomic perspective.…”

“…The five sampled lakes are highly dynamic ecosystems whose water chemistry and temperature fluctuate seasonally depending on climate conditions (i.e., rainfall, solar radiation intensity and water evaporation rate) [21][22][23][24][25][26][27]. The physicochemical parameters measured at the time of sampling (August 2019) are presented in Table 1.…”

“…The degree of mineralization of Lake Amara has varied over recent years between 6.5 and 31 g•L −1 , the dominant ion being sulfate, followed by chloride, sodium and small amounts of magnesium [21][22][23]. The salinity of the other four lakes has also fluctuated between 8.9 and 16 g•L −1 in Lake Balta Alba [21,24], 29 and 45 g•L −1 in Lake Caineni Bai [21,25], 57 and 150 g•L −1 in Movila Miresii Salt Lake [26,27] and 111 and 317 g•L −1 in Braila Salt Lake [22,24], the predominant ions being chloride and sodium, followed by sulfate and considerably lower quantities of magnesium.…”

Geochemical Responses to Natural and Anthropogenic Settings in Salt Lakes Sediments from North-Eastern Romanian Plain

“…The lacustrine (i.e., depositional) environment is under the shaping influence of a complex system of chemical factors, of which the most important are pH, redox potential (Eh), temperature, and salinity [6,12]. These factors-against the background of the influences exerted by the geographical location and the geology of the hydrographic and lacustrine basin, the interaction of the lake with the underground water, the geomorphological processes carried out on the surface of the hydrographic basin, the climate, the vegetation, and human activities-confer the lake sediments distinct chemical properties [13,14]. These can be evaluated by calculating several parameters, such as elemental chemical composition, organic substances (humic compounds, hydrocarbons, amino acids, pigments, etc.…”