关键词: ICP-MS, ICP-MS, 云南农田土壤, 常量元素, 微量元素, 含量

Abstract: The yields of selenium sand melon is the major income source of the farmers in the Huanxiang Mountain region. The frost has caused huge damages to the selenium sand melon in the region. In order to develop effective technologies to prevent such losses, this paper presents a detailed analysis based on a half century climate records of frost of the Huangxiang Mountain region. Combining with the frost climate index, we analyzed the lowest temperature data collected from five meteorological stations including Zhongwei, Zhongning, Haiyuan, Tongxin and Xingren in the selenium sand melon growing regions in nearly 50 years. The basic climate characteristics and variation trends of frost in the Ningxia sand melon growing regions were obtained. The results showed that the date of the last frost gradually occurred early over the years. The variation trend of frost with temperature ≤2℃ was most significant, and followed by that of the frost with temperature ≤0℃. The frost with temperature ≤-2℃ had the slowest variation. The occurrences of mild, moderate and severe spring frost were gradually decreasing over the years. The mild spring frost had the least occurrence rate. The occurrence frequencies of the moderate and severe spring frost were very close and they both slowly reduced. The variation trend of the frost occurrence in recent 50 years was not obvious in the selenium sand melon growing regions. Though the study shows that the occurrence of the moderate and severe frost is gradually decreasing since 2006, it is still important to prevent the frost damage.