准噶尔盆地南缘荒漠区土壤碳分布及其稳定同位素变化

发布时间：2018-03-10 03:14

  本文选题：土壤有机碳　切入点：土壤无机碳　出处：《新疆大学》2017年硕士论文　论文类型：学位论文

【摘要】：探讨干旱区土壤-植被生态系统碳来源与转化是干旱区碳循环研究的一个重要领域,该研究可进一步为干旱区碳资源的合理管理和保护提供参考。本研究以亚洲中部干旱区准噶尔盆地南缘荒漠区为研究区,根据荒漠距离绿洲的远近,分别在荒漠的边缘(距离绿洲约5 km)、荒漠中部(距离绿洲约45 km)和荒漠腹地(距离绿洲约70 km)设置三条样带,并采集200cm深的土壤剖面样品,研究土壤有机碳(SOC)、土壤无机碳(SIC)含量及其稳定碳同位素的分布,探讨土壤碳变化与距离绿洲远近的关系,探讨土壤碳及其同位素分布规律。研究表明,SOC含量随深度加深而减少,受距离绿洲远近的影响,SOC均值含量为荒漠边缘荒漠中部荒漠腹地。SOC的δ~(13)C值范围为-25.199‰~-17.418‰,随深度变化先增后减,80cm左右富集,由此推断准噶尔盆地南缘荒漠区地表植被以C3植物为主,但绿洲边缘又经历了从C3植物为主到C4植物为主的演替过程。受碳酸盐淀积作用影响,80%的采样点SIC累积量随深度加深而先变大后变小,80cm左右富集;SIC的δ~(13)C值随深度变化先变小后变大,底层富集,主要受原生碳酸盐含量和剖面土壤CO2的影响。土壤C同位素变化对植被演替过程和成土程度的强弱有一定的指示意义。利用克里金插值对研究区采样点各个深度有机碳同位素和无机碳同位素进行空间分析,探讨研究区碳及其同位素空间分布特征,找出其变化规律,这对其未来的变化趋势有一定的预测作用。研究表明在0~20cm土壤有机碳δ~(13)C值整体的空间分布大体呈西南高,东南低,变化相对较缓和。有机碳δ~(13)C值的较低值对应的面积比例逐渐增大即有机碳δ~(13)C值较低值所占面积百分比逐渐增大。在中部30~80cm范围内的有机碳δ~(13)C值变化较大,最大值重心也在不断的迁移,从最开始的西南迁移到西北地区,又迁移到东南地区,上下层变化差异较大,空间分布相对不稳定。80~200cm有机碳δ~(13)C值变化幅度最大,有机碳δ~(13)C值含量大体呈东北和东南区高,同时随着深度的加深,最大值向中部靠近并有向西蔓延的趋势,低值区面积相对较大。研究表明在0~20cm整体的空间分布与表层空间分布相似,无机碳δ~(13)C值含量大体呈西部高,东部低,但均值比表层大,变化相对较缓和,较低值对应的面积比例逐渐增大即无机碳δ~(13)C值较低值所占面积百分比逐渐增大。30~80cm范围内的无机碳δ~(13)C值变化较大,最大值重心也在不断的迁移,且面积不断增大,低值区不断向东南角蔓延,面积越变越小,仅占所有面积的5%,与有机碳δ~(13)C值分布趋势相反。80~200cm无机碳δ~(13)C值变化幅度较小,含量大体呈西南区高。
[Abstract]:The study of carbon source and transformation of soil-vegetation ecosystem in arid region is an important field in the study of carbon cycle in arid region. This study can be used as a reference for the rational management and protection of carbon resources in arid areas. In this study, the desert area of the southern margin of Junggar Basin in central Asia is taken as the study area, according to the distance from the desert to the oasis. Three samples were set up at the edge of the desert (about 5 km / m from the oasis), the middle part of the desert (about 45 km / m from the oasis) and the desert hinterland (about 70 km / m from the oasis), and the soil profile samples were collected at a depth of 200cm. The contents of soil organic carbon (SOC), inorganic carbon (sic) and the distribution of stable carbon isotopes were studied. The relationship between soil carbon change and the distance from oasis was discussed, and the distribution of soil carbon and its isotopes was also discussed. The results showed that the content of SOC decreased with the deepening of soil depth. Under the influence of the distance from oasis, the average content of SOC in the desert hinterland of desert center of desert margin was -25.199 鈥，

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