Abstract:Precipitation sampling was took at Naqu of Tibet from June to October, 2013. Only two valid rainwater samples in June and July were got. With the experiments of droplets freezing, the average frozen temperature of droplets embedded with particulate matters (>0.22μm) of rainwater samples were tested. Meanwhile, the activity of ice nuclei in the original rainwater, filtered rainwater, rainwater added with protein denaturants, boiled rainwater had also been tested. The results indicated that the average freezing temperatures of original rainwater droplets in June and July were -13.3℃ and -8.7℃, respectively. As for samples with the average freezing temperatures above -10℃, it can be concluded that there were some biological ice nuclei in the original rainwater, which were sensitive to the protein denaturants and boiling. However, their nucleation activities were different for these two months. The biological ice nuclei played a major role in the freezing of droplets in July, but not in the June. The filtered rainwater still contained efficient biological ice nuclei, but the compositions were still unknown. Using the cloning and sequencing technology, the bacteria 16S rRNA gene and the fungi ITS1-5.8S-ITS2 gene that covered the two internal transcribed spacer and 5.8S rRNA gene were analyzed. The results indicated that the bacterial genus of Pseudomonas and the fungal genus of Fusarium were recovered in the rainwater and they were supposed to be two types of efficient biological ice nuclei.
杜鹏瑞, 杜睿, 路则栋, 梁宗敏. 西藏那曲地区夏季降水中生物冰核的分布特征[J]. 中国环境科学, 2015, 35(7): 1998-2006.
DU Peng-Rui, DU Rui, LU Ze-Dong, LIANG Zong-Min. Distribution of biological ice nuclei in the summer precipitations of Naqu in Tibet. CHINA ENVIRONMENTAL SCIENCECE, 2015, 35(7): 1998-2006.