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目前,关于不同盐含量及外源CH_4浓度对盐碱土壤CH_4吸收的影响机制尚不清楚.因此,本研究通过室内培养实验,设定大气外源CH_4浓度((2.5±0.1)μL·L-1)和高外源CH_4浓度((6451.6±2.9)μL·L-1),并调节盐碱土壤盐含量,探究不同盐碱程度土壤CH_4吸收潜力的变化趋势.结果表明,两种外源CH_4浓度条件下,无外源盐添加的不同盐碱程度土壤SA1(轻度盐化土壤)、SB1(强度盐化土壤)、SC1(盐土)均表现为随盐碱程度增加,CH_4累积吸收量降低的趋势,即SA1>SB1>SC1;不同外源CH_4浓度下,CH_4累积吸收量表现为:高外源CH_4浓度(4.10×104μg·kg~(-1))远远大于大气外源CH_4浓度(6.85μg·kg~(-1)).此外,通过实时荧光定量PCR技术检测与计算得到不同盐碱程度土壤甲烷氧化菌丰度、甲烷氧化菌比活性.3种不同盐碱程度条件下,随着盐含量增加,土壤甲烷氧化菌比活性降低,CH_4累积吸收量亦降低,盐含量较高的土壤(SB1、SC1)加入外源盐后,会明显降低CH_4吸收.因此,两种外源CH_4浓度条件下,不同盐碱程度土壤甲烷氧化菌比活性越高,CH_4累积吸收量越大;盐碱土壤甲烷氧化菌比活性变化量越大,CH_4累积吸收变化量越高.说明在两种不同外源CH_4浓度下,土壤甲烷氧化菌比活性是不同盐碱程度土壤CH_4吸收潜力的根本原因.
At present, the mechanism of CH4 uptake in saline-alkali soils with different salt content and exogenous CH4 concentration is still unclear.Therefore, in this study, the concentration of exogenous CH4 ((2.5 ± 0.1) μL·L- 1) and high concentration of exogenous CH4 ((6451.6 ± 2.9) μL·L-1), and to adjust the salt content in saline-alkali soils to explore the change tendency of soil CH 4 uptake potential under different salinities.The results showed that two exogenous CH_4 Under different concentrations of salinity, SA1 (slightly salinized soils), SB1 (salinity soils), and SC1 (saline soils) with no salinity added showed that with the increase of salinity, the accumulation of CH_4 decreased (SA1> SB1> SC1). Under different concentrations of CH4, the cumulative uptake of CH4 was as follows: high concentration of exogenous CH4 (4.10¡Á104μg¡¤kg ~ (-1)) was far greater than the concentration of exogenous CH4 6.85μg · kg ~ (-1)) .In addition, the abundance of methanotrophs and the activity of methanotrophs in soil with different salinities were detected and calculated by real-time fluorescence quantitative PCR With the increase of salt content, the specific activity of soil methanotrophs was decreased, and the cumulative absorption of CH_4 also decreased. Soil with higher salt content (SB1, SC1) significantly reduced the CH4 uptake, therefore, under the two exogenous CH4 concentrations, the higher the specific activity of methane oxidizing bacteria was, the higher the CH4 uptake was. The higher the change of specific activity of bacteria, the higher the change of cumulative absorption of CH_4, indicating that the specific activity of soil methane oxidizing bacteria is the fundamental reason for the CH_4 uptake potential of soils with different salinities at two different concentrations of exogenous CH_4.