关键词: 土壤, 土壤, 重金属, 钝化, 水分调控

Abstract: The temporal and spatial evolution of lightning days is a applied value to the monitoring and prediction of disastrous weather and disaster prevention and mitigation in this region. Based on the daily year of lightning days from 13meteorological stations in Harbin from 1981 to 2018, The EOF and wavelet analysis were used to examine the temporal-spatial variation of lightning days in Harbin during the past 38 years. The results showed that it was a downtrend to lightning days in harbin, which decreased significantly at rates of 0.31d/10a. There were 3periodic changes of scales in lightning days, which were 28 years, 4 years and 9 years and non-significant cycle change. The three types spatial distribution of lightning days were mainly "hyperbolic paraboloid" shape and positive change trend, a line of the Shuangcheng-Acheng-Mulan and the middle of Tonghe-Yilan as the axis (southwest-northeast), the left paraboloid increased along the axis to the southwest, the right paraboloid decreased along the axis to the northeast, the range of left paraboloid was greater than the right paraboloid, and it was a closed low-value region with relatively dense contours. It can provide reference for lightning disaster management, prediction and prevention.