关键词: 土壤, 土壤, 梯度浓度驯化法, 重金属污染, 水稻

Abstract: The surface humid index is calculated based on the precipitation, temperature, sunshine and other observation data of 8 meteorological stations in Qingyang from 1981 to 2016 and the potential evapotranspiration is estimated by the improved Thornthwaite formula, and the spatial and temporal change characteristics are analyzed. The results showed that: in the past 36 years, the spatial distribution characteristics of surface humid conditions and that of each period of Qingyang were drought in the north and wet in the south, and the humidity increased from northwest to southeast. The average surface humid index had a tendency of fluctuate decrease with the change of time, and the rate was 0.05/10 a, which indicated that Qingyang had an increasingly arid trend. The 1980s was the wettest period in Qingyang, during this period, the wet level was relatively high. The driest period was the 1990s, with the surface humid index below the 30 years’ average. After 2000, the wetness degree of Qingyang increased slightly, but the wet and dry distribution showed the characteristics of polarization, and the difference between wet and dry areas in the northwest and the southeast increased. Precipitation and potential evapotranspiration showed opposite characteristics over the time, the precipitation decreased with time while the potential evapotranspiration increased. Surface wetness index was strongly correlated with precipitation and potential evapotranspiration, followed by sunshine, and temperature was the weakest factor.