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为揭示季节性温度升高对消落带落干期土壤氮矿化的影响,分别采集三峡支流澎溪河消落带上游和下游两个水文断面,155 m(低)、165 m(中)和175 m(高)这3个水位高程表层土壤,结合落干期气温变化特点,在25℃和35℃两个温度下进行恒温培养.结果表明,消落带土壤总氮和硝态氮在上游断面和高水位高程含量更高,而下游和低水位高程含量更低,铵态氮分布与其相反.硝态氮是无机氮的主要存在形式,占无机氮的57.4%~84.7%.相同培养温度下,氨化、硝化、净氮矿化速率均表现为随水位高程增加,随流域断面由下至上而显著增加(P<0.05);总体上,在水位高程和流域断面上均表现为:温度升高使硝化速率和净氮矿化速率显著增加(P<0.05),而对土壤氨化速率无显著影响(P>0.05).
In order to reveal the effect of seasonal temperature increase on soil nitrogen mineralization in the declination zone, two hydrologic sections, 155 m (low) and 165 m (middle), upstream and downstream of the Pengxia River, And 175 m (height) of the upper water level, and combined with the characteristics of the air temperature during the drying-out period, the two kinds of soil were incubated at 25 ℃ and 35 ℃ .The results showed that total nitrogen and nitrate nitrogen The upstream section and high water level elevation content is higher, while the downstream and low water level elevation content is lower, and the distribution of ammonium nitrogen is the opposite.Nitrate is the main form of inorganic nitrogen, accounting for 57.4% -84.7% of inorganic nitrogen. Under the temperature, the rates of ammonification, nitrification and net nitrogen mineralization all increased with elevation of water level and increased significantly from bottom to top (P <0.05). On the whole, The temperature increased the nitrification rate and net nitrogen mineralization rate significantly (P <0.05), but had no significant effect on soil ammonification rate (P> 0.05).