[Hydrochemical Characteristics and Transformation Relationship of Surface Water and Groundwater in the Plain Area of Bortala River Basin, Xinjiang].

The geological conditions of the Bortala River basin are complex, and the transformation of surface water and groundwater is frequent. It is great significance to study the hydrochemical characteristics and transformation relationship of surface water and groundwater for the reasonable development and allocation of water resources in the basin. Based on 15 surface water samples and 39 groundwater samples collected in April and May 2021, the APCS/MLR model and the combination of stable hydrogen and oxygen isotopes with hydrochemistry were used in this study to analyze the hydrochemical types and the distribution characteristics of hydrogen and oxygen isotopes, the source contribution of chemical components, and the transformation relationship between surface water and groundwater. The results showed that the surface water was mainly HCO3·SO4-Ca type and HCO3-Ca type, and the groundwater was mainly HCO3·SO4-Ca·Na type, HCO3-Ca type, and HCO3·SO4-Ca type. The contribution rates of the dissolution-migration-enrichment factor, human activities factor, environment factor, and native geological factor to the chemical components were 28.8%, 17.7%, 12.0%, and 6.5%, respectively. Bortala River water D and 18O was enriched along the distance, and groundwater D and 18O in the north bank was generally more enriched than groundwater in the south bank as a whole. Under the control of geological conditions such as geological structure and hydrogeological conditions, the transformation of river water and groundwater was concentrated in the middle reaches of the Bortala River, which was generally manifested in both unconfined groundwater and spring overflow in the sides of the recharge river water, and the recharge proportion ranged from 1.0% to 70.9%.

[Clonal water integration contributes to more survival advantages for Populus euphratica young ramets in the hyper-arid habitat]. / å ‹éš†æ°´åˆ†æ•´åˆæœ‰åŠ©èƒ¡æ¨æ— æ€§ç³»å¹¼æ ªåœ¨æžç«¯å¹²æ—±ç”Ÿå¢ƒä¸‹ä¿æŒæ›´é«˜ç”Ÿå­˜ä¼˜åŠ¿.

The proposed investigation was carried on the characteristics of clonal water integration between the Populus euphratica mother tree and its young ramets, as well as its effects on the phy-siological traits of young ramets at the lower reaches of Tarim River. The results showed that there was obvious water integration characterized by acropetal water transport between P. euphratica mother tree and its young ramets. The mean daily flow by water integration from the mother tree to its young ramets was three times as the seedlings with similar growth status at the same habitat by getting water by itself roots. Compared with the P. euphratica seedlings, the young ramets could take much more water from relatively deeper soil layers just like their mother tree. It indicated the young ramets maintained a better water acquisition ability due to clonal water integration. There was obviously higher leaf water content of young ramets than seedlings, and especially the water potential in the predawn and midday was increased by 10.0% and 29.7%, respectively. The advantaged water status of young ramets made the photosystem 2 electron transport rate and actual photochemical efficiency of photosystem 2 in light-adapted leaves increase by 23.4% and 11.5% than seedlings, respectively, and also made the young ramets maintain a significantly lower excess excited energy in photosystem 2 and a lower risk of photoinhibition than seedlings. All of the above cha-racteristics would impel the P. euphratica young ramets had higher survival advantages than seedlings at hyper-arid habitats.

[Analysis of carbon flux of soil and its related factors from Tamarix spp. community in the middle and lower reaches of Tarim River].

This study utilized LI-8100 automated soil CO2 flux system to monitor the day change of carbon flux of soil from Tamarix spp. community in the middle and lower reaches of Tarim River. The influence of temperature, groundwater, and soil water on Carbon flux of soil were analyzed. The study show that the curves of day change of soil respiration have a simple peak value, but the maximum flux normally appear until 12 o'clock noon to 16 o'clock differently. Because of influence of cloud cover and wind speed in that time, difference of the day change of carbon flux of soil are obvious. The relations between the soil respiration and underground water, temperature and soil water content in every depth are close; the relations between carbon flux of soil and underground water are extremely prominent, suitable for Cubic model curve. The relations between carbon flux of soil and air temperature and air temperature near the ground surface, ground surface temperature become positively correlated, suitable for Exponent models curves. However, the relations between carbon flux of soil and soil temperature in the 15 cm, 20 cm, 25 cm, 30cm are negatively correlated, suitable for Cubic model curve. At last, this study analyzed the relations between carbon flux of soil and temperature and soil water content by multi- regression, which explain 67% of the changes in carbon flux of soil.