Water quality and environmental wellness of mineral springs in the Uvs province based on diatom studies

: Fifty-eight diatom species belonging to 34 genera, 20 families, 11 orders, and one class are identified in the diatom survey of mineral springs near Uvs and Khyargas lakes in northwest Mongolia. The water quality of the mineral springs of Uvs Lake is fresh, and the mineral spring belonging to Khyargas Lake is fresh to brackish based on the diatom community. The environmental well-being of those springs is 78.5-83.5. Conservation management has to be based on aquatic diversity studies to restore these springs to nature. Conservation management of springs based on algae communities is an issue that is being raised for the first time in Mongolia.


INTRODUCTION
Spring ecosystems are unique due to their diverse characteristics and ecological significance [1,2,3].However, these invaluable ecosystems are under severe threat globally, with rampant ecological impairment reported in developed regions and declining trends in ecosystem conditions.Pollution and climate change significantly endanger the quality and quantity of spring water flow, highlighting the urgent need for sustainable management to protect the ecosystem services they provide.Additionally, springs offer cultural services, attract tourists, and provide health benefits, emphasizing their unique and multifaceted importance [4].
Natural water that has a medical effect on the human body or any organ is called a spring [5].Internationally, mineral water is defined as drinking water containing one or more unique components, such as dissolved substances, minerals, or gases, at concentrations of 1000 mg/dm3 or more that have a sanative effect on the human body [6].
In Mongolia, the distribution of hot and cold springs, their temperature, gas composition, geochemical characteristics, classification, and spring regions have been determined, and indications for spa treatment in spring were issued [7].
In Uvs province, the water chemistry of seven springs, such as Green Tsegee, Khavtal, Boom, Burgastain, Chandman Ulaan, Khar Termes, Urt Bulag, and Ikh Gol has been analyzed.However, no investigation into the diatom community has been conducted.However, with the development of mining, industry, and agriculture, the consequences of human activities, such as lowering water levels, drying, and pollution due to excessive groundwater use, continue [8].Protective concrete fences are sometimes built, increasing water temperature and catchment.Wrong protection management is involved in this case, requiring reestablishing environmental sanitation zones [9].They may show activity levels comparable to standard mineral springs, from slight bubbling to intermittent bursts to steady, violent boiling.So, local people call it a boiling spring.In other words, it is similar to boiling water.However, the water temperature during summer is between 16°C and 20°C.Diatoms are excellent water quality indicators in mineral springs due to their diverse nature and sensitivity to environmental changes [10].Research indicates that epilithic and bryophytic substrates can effectively be used for diatom-based water-quality biomonitoring in mesotrophic and eutrophic environments [11].Studies on karst springs highlight the importance of analyzing epilithic diatom assemblages to assess environmental quality, with various indices indicating good biotic integrity and water quality despite some organic contamination [12].Predictive models based on diatom communities have shown promising results in assessing water quality, with diatoms being particularly sensitive to changes in water chemistry, making them valuable for evaluating environmental conditions in lowland streams [13].In our country, diatom research has intensified since the 2000s and is widely used in water quality assessment.A diatom community was used to assess the water quality of lakes in western Mongolia [14].
There is no research material on water quality using aquatic organisms.The study aimed to evaluate the water quality and environmental wellness of two springs near the Uvs and Khyargas lakes based on the diversity and diatom community.This study will improve our knowledge of the diversity of diatoms in mineral springs and the protection management of springs in Mongolia.

MATERIALS AND METHODS
In June and July 2022, 11 algae samples were collected from mineral springs and springs near Uvs and Khyargas lakes.Table 1 summarises the study points.principles and taxonomic units.However, the groundwater accumulation zone depends on the groundwater accumulationfoot range of Quaternary and Neogene sediments [15].Uvs Lake is 759 m above sea level and is the lowest point in the depression of the Great Lakes of Central Asia.The spring is located 5 km from Uvs Lake, to the west of the lake.According to the category of water basins in Mongolia, Uvs Lake belongs to the Uvs Lake-Tes River basin.Khyargas Lake is located in a tectonic depression 1028 meters above sea level in the Great Lakes depression, in the southern part of the Khan Khokhi mountain range.It is the end of all the rivers flowing into the Great Lake Depression from the Altai Khangai mountains.The spring near Khyargas Lake is 500 m on the northern shore.The spring that was researched belongs to the Khyargas Lake -Zavkhan River basin.Survey points are shown in the following figure.

Figure 1. Study points
The samples were collected from the bottom of the spring, from aquatic vascular plants, mud, and sand, and then stored in a container labeled with the collection label [16].A standard preparation for identifying diatoms at the species level was prepared accordingly [17].To completely clean the organic component from the collected sample, we cut a small part, put it in a glass beaker, added nitric acid to 30 ml of 70%, and gently heated it for about an hour on a hotplate in a laboratory chemical fume hood.After that, the preparation was cooled to room temperature and deacidified by passing it through distilled water 6 times for 6 hours.11 permanent slides were prepared by instilling the valve from the cleaned sample into the coverslip and evaporating, sticking it to the tray glass using Naprax balsam, and affixing the collection label with the same address as the number of raw sample in the right corner.All preparation was identified at the level of species under a light microscope with 1000x magnification immersion oil, using essential books [18][19][20][21] and websites https://www.algaebase.org/;https://diatoms.org/.The richness and relative abundance of each species were calculated using total abundance and individual species' abundance [22][23].The similarity of the species composition was calculated by the jaccard index.The diversity of diatom, evenness [24] and water quality index [25] were calculated, which were used for assessing the environmental wellness biodiversity level [26].The Shannon-Wiener diversity index (H) was employed in calculating environmental wellness and restoration level [26] and determining the evenness (E) of respective ecosystems.This approach, where (H) represents the Shannon-Wiener diversity Index and Pi denotes the relative proportion (n/N) of the individual of one particular species found, is crucial in our understanding of ecosystem health and balance.

Table 4. Water quality assessment using Van Dam Mertens, 1994 classification of ecological indicator value
The spring of Uvs Lake The spring of Khyargas Lake No dominant species exist in the mineral springs near Khyargas and Uvs lakes.Freshwater indicator genera species in the mineral springs near Uvs Lake are more widespread, while only in the spring near Khyargas Lake species belonging to the families Naviculaceae and Surirellaceae, which survive riparian soil erosion and nutrient pollution, were recorded.The diversity of species is more significant in the mineral spring of Khyargas Lake than in the mineral spring of Uvs Lake.When evaluating the water quality, the Uvs Lake mineral spring shows that the oxygen content is 100% oligo saprobe, oligotrophic or unpolluted, and very fresh.However, the mineral spring of Khyargas Lake is salty, the oxygen content is 75%, oligomesotrophic or secondary water, and the environment outside the reservoir is dry, indicating that the spring is affected by external influences.While collecting samples, we find large amounts of garbage left behind by people traveling and resting at the tourist camp sites near the mineral spring of Khyargas Lake.All garbage in this area is destroyed.It was felt that the water was taken from the spring by running a water suction pump which may have contributed to the pollution of the spring.On the other hand, during springtime, herdsmen of Zavkhan Soum pasture their domestic animals along the lake's northern shore or near the mineral spring.In summer, herders of Khyargas Sum pasture their livestock animals surrounding the lake, which causes soil erosion and damage due to the impact of livestock grazing.Local and climatic factors influence species distribution in thermal springs [27].The pasture has the greatest effect on spring diatom diversity [28].
Livestock grazing and mining activities are intensively implemented along the spring shores, increasing sediment accumulation [29].Diatoms have a silica valve and respond quickly to changes in the habitat, manifesting as changes in the structure of the community and the number of individuals.As riparian soil erosion increases, the relative abundance of mobile diatoms increases [30].This is also indicated by species that are less resistant to external nutrients and organic pollution in the algal community of the spring.The locals protected the source of the spring by pouring cement around it without the guidance of a professional organization, which may have contributed to the nature of the spring by blocking the outflow of water.
The key to the sustainable use of mineral water is to establish proper protection zones, reduce pollution sources, conduct water quality monitoring studies, and determine the quality of water treatment [31].Mongolia has the world's most minuscule renewable water resources [32][33].Therefore, we must conduct thorough research, analysis, laws, and regulations in underground water protection and disseminate knowledge to the public.Local authorities should issue policy documents and decisions on the protection of springs, empower environmental policy experts and conservationists in the field of algal studies, conduct regular water surveys in the area, and educate local people on water conservation and rehabilitation.It is necessary to take adequate measures to prevent animals from entering the lake, to provide local animal wash basins, to develop responsible tourism, and to improve waste management along the shores of the lake.The EWBL of the mineral spring of Uvs Lake is higher than Khyargas, and the mineral spring of Khyargas Lake should be restored by 21.47 percent.

CONCLUSIONS
The orders Naviculales, Cymbellales, and Fragilariales had the most species richness in our study.The mineral spring of Uvs Lake is richer in diatom species than the mineral spring of Khyargas Lake.Diversity of diatom and evenness are not significant between springs.However, It can be concluded that the water quality of the mineral spring of Khyargas Lake is fresh to brackish.Protecting springs, such as groundwater source, will be necessary in the future, but our results reveal the importance of aquatic biology investigations.The percentage of required restoration of their springs is 16.48-21.47based on diatom community.
It is likewise extremely important to establish the sanitary zone of the spring environment and introduce relevant protection management.