Chemical composition and trophic state of shallow saline steppe lakes in central Asia (North Kazakhstan)

Abstract

The purpose of this study was to identify the prevailing chemical composition and trophic state of the shallow saline steppe lakes of North Kazakhstan along a wide size range (<1−454 km 2 ) and salinity gradient (2−322 g L −1 ) on a large spatial scale (1000 km), taking into account the potential effects of human disturbances. Water depth, Secchi disc transparency, temperature, pH, electric conductivity, major ions, total dissolved solids, total organic carbon, total nitrogen and phosphorus, nitrate, soluble reactive phosphorus and chlorophyll a were measured. The equivalent percentage of major ions, Spearman rank correlation, multivariate analyses, equilibrium state of lakes and spatial GIS autocorrelation were calculated. The impact of human disturbances (settlements, farms and mines) on total organic carbon, nitrogen, phosphorus, and chlorophyll a were tested by Kruskal-Wallis ANOVA.The most common combinations of dominant ions were Na-Cl>SO4 and Na-Cl (n=16; 64%), the Ca, Mg, HCO3, and SO4 ions precipitate with increasing salinity (2−322 g L −1 ), and ion composition shifts from Na>Mg-Cl>SO4, to Na-Cl. The most of the chemical variables positively, but chlorophyll a negatively correlated with total dissolved solids, and the total phosphorus had no significant correlation with any variables. The trophic state of these lakes in most cases exceeded the hypertrophic level. The increase in salinity causes change in chemical composition and effects on the phytoplankton development independently from the size of water surface, and the human disturbances had negligible effect on the trophic state of shallow saline lakes in this region of Kazakhstan.

Chemical, biochemical, and bioactivity studies on some soda lakes, Wadi El-Natrun, Egypt

“…In terms of dissolved anions, Cl − came first with an equivalent percentage > 71%. Thus, the water of El-Hamra Lakes is of the chloride type (Arnuk et al, 2023 ; Boros et al, 2017 ).

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A review of the defining chemical properties of soda lakes and pans: An assessment on a large geographic scale of Eurasian inland saline surface waters

“…China ( N = 20) [ 26 , 29 ]. Kazakhstan ( N = 30) [ 30 – 32 ] and in S1 Table ( N = 7). Mongolia ( N = 26) [ 15 ] and in S1 Table ( N = 12).…”

Saline lakes as barriers against pollution: a multidisciplinary overview

“…The existing literature on the study of saline lakes is extensive and focuses particularly on classical limnological studies to address human impacts (Stenger-Kovács et al, 2014;Ogato et al, 2015;Stenger-Kovács et al, 2018;Şuteu et al, 2021). Also, several studies have focused on the geochemical aspects of saline lakes in connection with such impacts (Stojanovic et al, 2009;Boros et al, 2017;Corrales-González et al, 2019;Kolpakova et al, 2019;among others). Others have highlighted the relevance of microorganisms in saline lakes, with a sharp increase over in the last years, as new analytical methodologies have been developed (Post, 1977;Abed et al, 2012;Casamayor et al, 2013;Grant & Jones, 2016;among others).…”