Subjects: Geosciences >> Atmospheric Sciences submitted time 2023-03-28 Cooperative journals: 《干旱区研究》
Abstract： The status of air pollution in China has been recognized as a serious health concern in numerous academic circles. Air quality is an important factor for defining air pollution, and main pollutants used to evaluate its quality, include PM2.5, PM10, SO2, NO2, CO, and O3. Hotan is one of the oasis cities with severe air pollution crisis. The located in the southwest edge of Taklimakan Desert in the southernmost part of the Northwest Xinjiang province in China. The soil structure in this area is loose, dust storms are frequent, and particles carried by dust storms are heavily deposited, which result in an increase in the concentration of pollutants. Therefore, the air Pollution caused by these particles results in severe challenges. Different types of air pollutants have varied hazards to human health, for example, PM2.5 and PM10, which are the main air pollutants in Hotan City, cause serious human respiratory tract infections, and their sources are extensive, hazardious, and difficult to eliminate. The rapid economic development in recent years and the accelerated urbanization have aggravated the deterioration of air quality in Hotan City, posing a great threat to the physical and mental health of local residents. Therefore, understanding the characteristics of air quality and its potential health effects in Hotan City is crucial for controlling urban air pollution and improving local ecological environment. This study used the historical air quality data in Hotan from 2016 to 2021 to analyze the distribution characteristics of pollutants, to determine the relationship between air quality and potential human health effects, and to evaluate the correlation between pollution levels and air pollutants, such as PM2.5, PM10, SO2, NO2, CO, O3-8H, and AQI. The results showed that between 2016 and 2021, the concentration of O3-8H in two air pollution monitoring points in Hotan had an inverted U-shaped trend, while the concentration of other pollutants showed a U-shaped curve distribution. PM2.5 and PM10 were detected as the main pollutants throughout the year, and their concentrations were relatively high in spring. In addition, concentrations of SO2 and NO2 were high in autumn and winter, while those of CO and O3-8H were high in winter and summer, respectively. During the study period, the concentration of PM2.5 and SO2 decreased, while that of PM10 increased, but the overall air quality did not show significant improvement. The AQI value of air quality index in Hotan City was higher than the national second class level, and its value during the“unhealthy”air quality period was much higher than that during the“healthy”air quality, which suggested a high harmful potential to the physical and mental health of residents.
Subjects: Biology >> Botany submitted time 2023-03-13 Cooperative journals: 《干旱区研究》
Abstract： Populus euphratica Oliv. is an indicator species of eco- environmental changes in arid areas and it plays an irreplaceable role in maintaining the stability of a regional fragile ecosystem. At present, relevant research on the hollow tree of P. euphratica is still lacking. In this paper, we investigated the hollow ratio, architecture trait differences in living trees with hollow and without hollow, and its variation among the different aged forests in the Tarim River National Positioning Observation Station of P. euphratica Forest Ecosystem. The results showed that the hollow ratio of P. euphratica living standing trees in the study area was 17% (about 78 trees·hm-2) and the hollow rate increased with the increasing forest age. The hollow rate was related to maturity as the hollow occurrence rate of mature trees was 4.3 times higher than that of immature trees. The degree of hollowing of living trees was significantly positively correlated with the diameter at breast height, tree height, crown width, and ulcer area (P < 0.05), while it negatively correlated with height-to-diameter ratio. No significant correlation of the degree of hollowing was observed with the crown loss and crown length. The hollow phenomenon did not cause an obvious disadvantage in tree growth. The architectural traits of the living standing trees of P. euphratica showed resource- conserving adaptation characteristics with the increase in standing age. and their hollowing was likely to be the adaptation strategy of P. euphratica to the extremely arid environment.
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