本文選題：溫室氣體排放 + 降水變化　； 參考：《西北大學(xué)》2015年碩士論文

【摘要】：降水作為旱作農(nóng)田生態(tài)系統(tǒng)的主控因子,不僅影響著作物生產(chǎn)力的形成過程,同時(shí)對農(nóng)田溫室氣體(CO2、CH4和N2O)排放及相應(yīng)的綜合增溫潛勢具有重要影響。本研究以黃土高原冬小麥田生態(tài)系統(tǒng)為對象,基于人工降水模擬系列實(shí)驗(yàn),采用靜態(tài)箱-氣相色譜法田間原位系統(tǒng)研究了降水變化(降水量、降水頻率和季節(jié)分布)對土壤C02、CH4和N2O通量變化的影響規(guī)律,主要結(jié)果如下：1、不同降水量對土壤CO2和CH4排放的影響。試驗(yàn)設(shè)計(jì)在冬小麥拔節(jié)期和休閑期進(jìn)行人工模擬降水試驗(yàn),觀測降水后0-72h土壤CO2和CH4排放對不同降水量(1、3、8、16和32mm)的短期響應(yīng)。結(jié)果表明：降水后土壤CO2排放速率隨降水量的增大而增強(qiáng),1-16mm降水在降水后4h出現(xiàn)土壤CO2排放峰值,而32mm降水土壤C02排放峰值出現(xiàn)時(shí)間滯后了4h。土壤CO2排放速率(Rpi)脈沖強(qiáng)度隨降水量(P)增大呈指數(shù)增加(拔節(jié)期：Rpi=0.97P0.09, R2=0.5, P0.05;夏閑期：RPi=1.07P0.09, R2=0.98, P0.01).降水后72h土壤CO2累積釋放量(CO2-P)與降水量呈線性相關(guān)(拔節(jié)期：CO2-P=0.03P+5.99,R2=0.58, P0.05;夏閑期：CO2-P=0.11P+6.04, R2=0.86, P0.01)。土壤CO2排放溫度敏感性系數(shù)(Q10)和降水量之間存在二次曲線關(guān)系(拔節(jié)期：Q10=-0.005P2+0.18P+1.47,R2=0.37, P0.05;夏閑期：Q10=-0.007P2+0.21P+1.18,R2=0.95,P0.01)。與較小降水量相比,較大的降水量能增加土壤CO2排放但會推遲土壤CO2排放峰值出現(xiàn)時(shí)間。模擬降水后,低降水量(1-8mm)處理土壤CH4排放通量為波動變化,高降水量(16和32 mm)處理呈單峰型的變化。降水后72 h土壤CH4累積通量(CH4-C)與降水量(P)呈顯著線性正相關(guān)(冬小麥拔節(jié)期：CH4-C=2.45P-6.09, R2=0.92, P0.01;夏閑期：CH4-C=2.43P-4.73, R2=0.91, P0.01)。相關(guān)分析表明,降水后土壤CH4通量與土壤含水量和土壤微生物量碳含量顯著相關(guān),而與土壤溫度不相關(guān)。少量降水(1-8mm)可以在短期內(nèi)促進(jìn)旱作農(nóng)田土壤對CH4的吸收,加強(qiáng)土壤作為大氣CH4匯的強(qiáng)度,然而這種促進(jìn)作用也會隨降水量的增大和降水的下滲而削弱。較大降水(16和32 mm)可以刺激土壤產(chǎn)甲烷菌活性促進(jìn)CH4釋放,在短期內(nèi)使旱作農(nóng)田土壤由單一的匯功能轉(zhuǎn)變?yōu)閰R源雙重功能。2、夏閑期不同降水頻率對土壤CO2和CH4排放通量的影響。試驗(yàn)設(shè)計(jì)在冬小麥夏閑期(60天)模擬每隔5天(I5)、10天(I10)和20天(I20)三個(gè)降水頻率的降水,模擬降水總量(控制為240mm)不變,觀測了不同降水頻率降水后土壤CO2和CH4的通量特征。結(jié)果表明：不同頻率I5、I10和I20處理單次降水后土壤CO2排放速率是降水前的4-5倍表現(xiàn)出顯著的‘Birch effect".隨著降水次數(shù)的增加降水事件對土壤CO2排放的激發(fā)效應(yīng)被削弱,降水頻率越高削弱的越明顯,且I5和I10土壤CO2累積釋放量高于I20處理。土壤CO2通量和土壤水熱因子呈非線性的關(guān)系,土壤水分解釋了43%-76%的土壤CO2通量變化,且二者的相關(guān)性隨降水間隔的增加而增強(qiáng),Q10值隨降水間隔的增加而降低,說明高頻率降水處理土壤CO2通量的溫度敏感性更高。高頻率降水(I5處理)可以增強(qiáng)土壤氧化吸收大氣CH4的速率,增強(qiáng)大氣甲烷匯的功能。低頻率降水(單次降水量提高)可以使冬小麥田在短時(shí)間內(nèi)由大氣CH4的匯轉(zhuǎn)變?yōu)榇髿釩H4的源。旱地農(nóng)田土壤CH4通量強(qiáng)度受溫度和水分的共同影響,不同降水頻率的降水對土壤水分和溫度的影響改變了土壤吸收氧化和產(chǎn)生CH4的過程,甚至改變了土壤對大氣CH4的源匯功能。3、作物關(guān)鍵生育期增加降水對土壤溫室氣體排放和凈綜合增溫潛勢的影響。試驗(yàn)設(shè)計(jì)在自然降水的基礎(chǔ)上再分別在冬小麥生育關(guān)鍵時(shí)期拔節(jié)期(5月8日)和孕穗期(5月28日)增加0mm (10)、8mm (18)、16mm (116)、32mm (132)和64mm(I64)的降水,探討增加降水對土壤CO2、 CH4和N2O通量及其綜合增溫潛勢和作物產(chǎn)量的影響。試驗(yàn)結(jié)果表明：旱作冬小麥田為大氣CO2和N2O的排放源,是大氣CH4的匯。生育關(guān)鍵期增加降雨使CO2的排放量增加了2.50%-9.07%,N2O的排放量增加了4.33%-11.68%,對CH4的排放量無顯著影響。與IO相比,I8、I16、I32和I64處理冬小麥產(chǎn)量分別增加了24.46%、28.93%、31.70%和34.01%(p0.05),地上生物量分別提高了13.74%、18.99%、24.36%和25.11%。生育期增加降水降低了麥田NGWP和GHGI。增加降水不僅強(qiáng)化了土壤CO2和N2O源的特征,同時(shí)降水增強(qiáng)了土壤水分和養(yǎng)分有效性提高了作物產(chǎn)量,產(chǎn)生的補(bǔ)償效應(yīng)使麥田由溫室氣體的源轉(zhuǎn)為匯。
[Abstract]:As the main controlling factor of the drought cropland ecosystem, precipitation not only affects the formation process of crop productivity, but also has an important influence on the emission of greenhouse gases (CO2, CH4 and N2O) and the corresponding comprehensive temperature increasing potential. The effects of precipitation changes (precipitation, precipitation frequency and seasonal distribution) on the changes of soil C02, CH4 and N2O flux were studied by the state box gas chromatography in situ system. The main results were as follows: 1, the effects of different precipitation on the CO2 and CH4 emission of soil. Experimental design was designed in the jointing and leisure periods of winter wheat at the jointing and leisure periods. The short-term response of 0-72h soil CO2 and CH4 emission to different precipitation (1,3,8,16 and 32mm) was observed after precipitation. The results showed that the CO2 emission rate of soil increased with the increase of precipitation, and the CO2 emission peak of 4H appeared after precipitation in 1-16mm after precipitation, while C02 discharge time of 32mm precipitation soil lagged behind the velocity of 4h. soil. Rpi pulse intensity increased exponentially with the increase of water reduction (P) (jointing stage: Rpi=0.97P0.09, R2=0.5, P0.05; summer leisure period: RPi=1.07P0.09, R2=0.98, P0.01). The cumulative release amount of CO2 in 72h soil (CO2-P) was linearly correlated with precipitation after precipitation. 1). There are two curves between the temperature sensitivity coefficient of soil CO2 emission (Q10) and precipitation (jointing period: Q10=-0.005P2+0.18P+1.47, R2=0.37, P0.05; summer leisure period: Q10=-0.007P2+0.21P+1.18, R2=0.95, P0.01). Compared with the smaller precipitation, the larger precipitation can increase the soil CO2 emission but will delay the occurrence of the peak value of the soil CO2 emission. After simulated precipitation, low precipitation (1-8mm) treated soil CH4 emission flux was fluctuant, high precipitation (16 and 32 mm) showed a single peak change. The CH4 cumulative flux (CH4-C) in 72 h soil after precipitation was significantly linear and positive correlation with precipitation (P) (CH4-C=2.45P-6.09, R2=0.92, P0.01; summer leisure period: CH4-C=2.43P-4.73, R2=0.91, P0.01). The correlation analysis shows that the soil CH4 flux after precipitation is significantly related to soil water content and soil microbial biomass carbon content, but not related to soil temperature. A small amount of precipitation (1-8mm) can promote the absorption of CH4 in dry farmland soil in a short time, and strengthen the soil as the intensity of atmospheric CH4 sink, however, this effect will also follow. The precipitation (16 and 32 mm) can stimulate the activity of methanogenic bacteria in the soil to promote the release of CH4. In the short term, the soil from a single sink function is transformed from a single sink function to the dual function of.2, and the effects of different precipitation frequencies on the soil CO2 and CH4 flux in the summer leisure period are designed in winter wheat. The summer leisure period (60 days) simulated precipitation at three precipitation frequencies of 5 days (I5), 10 days (I10) and 20 days (I20). The total amount of simulated precipitation (240mm) was unchanged. The flux characteristics of CO2 and CH4 in soil after precipitation of different precipitation frequencies were observed. The results showed that the rate of CO2 emission of soil CO2 was 4-5 times as high as that of I5, I10 and I20 at different frequencies after single precipitation. The results show a significant 'Birch effect'. With the increase of precipitation times, the effect of precipitation on soil CO2 emission is weakened, the higher the precipitation frequency is, the more obvious the weakening of the precipitation frequency, and the cumulative release of CO2 in the I5 and I10 soils is higher than that of I20 treatment. The soil CO2 flux has a non linear relationship with the soil water heat factor, and the soil moisture explains the 43%-76% soil. The CO2 flux of the soil increased with the increase of the precipitation interval, and the Q10 value decreased with the increase of the precipitation interval, indicating that the temperature sensitivity of the CO2 flux in the high frequency precipitation treatment was higher. The high frequency precipitation (I5 treatment) could enhance the rate of the oxidation absorption of the atmospheric CH4 and enhance the function of the atmospheric methane sink, and the low frequency drop. The water (increase of single precipitation) can make the winter wheat field change from the atmospheric CH4 sink to the source of CH4 in a short time. The CH4 flux intensity in the dry farmland soil is influenced by the temperature and water. The influence of precipitation on soil moisture and temperature at different precipitation frequency changes the process of soil absorption and oxidation and the production of CH4, or even the soil. The origin and sink function of the soil to the atmospheric CH4,.3, the effect of increasing precipitation on the greenhouse gas emission and the net comprehensive temperature increasing potential in the critical growth period of the crop. Based on the natural precipitation, the experimental design increased 0mm (10), 8mm (18), 16mm (116), 32mm (132) and 64mm in the jointing period (May 8th) and the booting stage (May 28th) of the winter wheat breeding. (I64) precipitation to explore the effect of increasing precipitation on soil CO2, CH4 and N2O flux and its comprehensive temperature increasing potential and crop yield. The experimental results show that the dry winter wheat field is the source of CO2 and N2O in the atmosphere and the sink of CH4 in the atmosphere. The increase of rainfall in the critical period of fertility increases the emission of CO2, and the emission of N2O increases by 4.33%-11.. 68%, there was no significant effect on CH4 emissions. Compared with IO, I8, I16, I32 and I64 increased the yield of Winter Wheat by 24.46%, 28.93%, 31.70% and 34.01% (P0.05). The aboveground biomass increased respectively in 13.74%, 18.99%, 24.36% and 25.11%. growth periods. At the same time, precipitation enhanced soil water and nutrient availability, and increased crop yield. The compensation effect resulted in the conversion of wheat field from greenhouse gas to sink.
【學(xué)位授予單位】：西北大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：S512.11;S154.1

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