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Accurate evaluation of groundwater chemistry, quality, and human health risk could provide detailed and robust evidence of groundwater utilization. Gaer County is an important residential area in western Tibet. A total of 52 samples were collected from the Shiquan River Basin in Gaer County in 2021. Principal component analysis, ratiometric analysis of major ions, and geochemical modeling were conducted to clarify the characteristics of hydrogeochemical compositions and the controlling factors. The groundwater chemistry type is dominated by HCO 3 -Ca, and its ion concentration from high to low is Ca 2+  > Na +  > Mg 2+  > K + and HCO 3 -  > SO 4 2-  > Cl -  > NO 3 -  > F - . The groundwater compositions were determined by calcite and dolomite dissolution with cation exchange reaction. The human activity causes nitrate contamination, while arsenic contamination is attributed to surface water recharge. According to the Water Quality Index, 99% of the samples meet the requirements of drinking water. Groundwater quality is affected by the arsenic, fluoride, and nitrate concentrations. According to the human health risk assessment model, the cumulative noncarcinogenic risk (HI Total ) values for children and the CR values of arsenic (CR Arsenic ) for adults are higher than 1 and 1E-6, respectively, which are unacceptable risk values. Therefore, appropriate remedial measures are recommended to reduce nitrate and arsenic concentrations in groundwater sources for protecting against further health risks. This study can provide theoretical support and effective groundwater management experience for ensuring groundwater safety in Gaer County and other similar regions around the world., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Three anamorphic, ascomycetous yeast strains isolated from plant samples collected in Linzhi District, Tibet, China, were revealed as representing two novel species by 26S rRNA gene D1/D2 domain sequence and physiological property comparisons. The names Candida tibetensis sp. nov. and Candida linzhiensis sp. nov. are proposed for these novel species, with XZ 41-6T (=AS 2.3072T=CBS 10298T) and XZ 92-1T (=AS 2.3073T=CBS 10299T) as the respective type strains. D1/D2 sequence analysis showed that C. tibetensis and C. linzhiensis are closely related to Candida caryicola and Candida sequanensis, respectively.