Бидний тухай
Багш ажилтан
Meromictic lakes are lakes that do not have intermixed layers, and thus have unique physical, chemical, and biological properties. Lake Oigon is one lake with such a meromictic nature. However, a detailed study of the physico-chemical characteristics of Lake Oigon hasn’t been conducted. In this study, we investigated the physico-chemical characteristics of the water of Lake Oigon from the surface to bottom at one-meter depth intervals and compared parameter trends in summer and winter. The predominant hydrochemical type of lake water was Na-Cl-SO4. The salinity of the lake’s water was mesosaline to hypersaline. The concentrations of major ions (except sulphate) and microelements in summer were lower than that in winter. The suboxic layers (chemocline), and anoxic layer (monimolimnion) were often rich in nitrate, sulphide, ammonium, and phosphate despite the season. We hope that this study will show the characteristics of this meromictic lake and provide underlying information for future research on the chemical composition of Lake Oigon.
In recent years, climate change coupled with anthropogenic activities has led to monumental changes in saline lakes which are rapidly drying up across the globe and particularly in Central Asia. The landlocked country of Mongolia is rich in lakes which have remained primarily undisturbed by human impact, and many of these lakes have varying salinity regimes and are located across various geographical landscapes. In this study, we sampled 18 lakes with varying salinity regimes (hyperhaline, mesohaline, oligohaline, and polyhaline) covering 7000 km of western Mongolia and its various geographical landscapes (Gobi Desert, forests, and steppe). We identified that the bacterial communities that dominate these lakes are significantly influenced by salinity (p < 0.001) and geographical landscape (p < 0.001). Further, only five zOTUs were shared in all the lakes across the salinity regimes, providing evidence that both local and regional factors govern the community assembly and composition. Furthermore, the bacterial communities of hyperhaline lakes were significantly positively correlated with salinity (ANOVA, p < 0.001) and arsenic concentrations (ANOVA, p < 0.001), whereas bacterial communities of mesohaline and polyhaline lakes situated in forest and steppe landscapes were positively correlated with temperature (ANOVA, p < 0.001) and altitude (ANOVA, p < 0.001), respectively. Functional predictions based on the 16S rRNA gene indicated enrichment of KEGG Ontology terms related to transporters for osmoprotection and -regulation. Overall, our study provides a comprehensive view of the bacterial diversity and community composition present in these lakes, which might be lost in the future.
