农田土壤剖面溶解性有机碳分子转化特征  

Molecular Transformation Characteristics of Dissolved OrganicCarbon in Farmland Profile Soil

作　　者：吴浩然 张志远 贾琳娜 辛佳[1,2] Wu Haoran;Zhang Zhiyuan;Jia Linna;Xin Jia(College of Environmental Science and Engineering,Ocean University of China,Qingdao 266100,China;The Key Laboratory of Marine Environmental Science and Ecology,Ministry of Education,Ocean University of China,Qingdao 266100,China)

机构地区：[1]中国海洋大学环境科学与工程学院,山东青岛266100 [2]中国海洋大学海洋环境与生态教育部重点实验室,山东青岛266100

出　　处：《中国海洋大学学报（自然科学版）》2024年第12期90-100,共11页Periodical of Ocean University of China

基　　金：国家自然科学基金项目(42177053)资助。

摘　　要：溶解性有机碳(Dissolved organic carbon,DOC)是农田土壤碳库中最重要的活性碳组分。DOC可为土壤微生物提供必需的营养元素,也会诱导复杂的环境效应。本研究以中国青岛市大沽河农业区为研究对象,利用室内培养实验,并结合傅里叶变换离子回旋共振质谱(Fourier transform ion cyclotron resonance mass spectrometry,FT-ICR MS),从分子水平阐明不同氧化还原条件下土壤剖面中DOC转化的内在规律。研究发现:深层土壤的DOC来源以上层淋溶为主。土壤DOC的平均m/z、芳香指数(Aromatic index,AI)、O/C和双键当量(Double bond equivalent,DBE)随土壤深度的增加而减小。随着土壤深度的增加,反应过程中被降解的DOC分子DBE范围明显缩小(从0~18缩减至0~9),说明土壤对DOC的降解能力随着深度的增加有明显的下降。有氧培养后的DOC分子比无氧培养后的DOC分子具有更高的分子量、芳香性和不饱和度,且脂质的相对丰度比无氧组更低而木质素的相对丰度比无氧组更高,说明有氧条件可同步促进DOC分子的降解和生成。Dissolved organic carbon(DOC)is the major active carbon component in the carbon pool of Farmland soil,which can provide essential nutrients for soil microorganisms and induce complex environmental effects.In this study,soil samples were collected from the Dagu River agricultural area in Qingdao,China,and we established an incubation experiment combined with Fourier transform ion cyclotron resonance mass spectrometry(FT-ICR MS)to elucidate the molecular level of DOC transformation under different redox conditions.The study found that the source of DOC in deep soil was mainly from upper soil leaching.The average m/z,aromatic index(AI),O/C and double bond equivalent(DBE)of soil DOC decreased with increasing soil depth.The range of DBE degraded during the reaction was significantly reduced(from 0~18 to 0~9)with increasing soil depth,indicating that the degradation capacity of soil for DOC decreased significantly with increasing depth.The DOC molecules after aerobic incubation had higher molecular weight,aromaticity and unsaturation than those after anaerobic incubation,and the relative abundance of lipids was lower,while the relative abundance of lignin was higher than that of the anaerobic group,suggesting that aerobic conditions can promote both degradation and generation of DOC molecules.

关 键 词：溶解性有机碳 深层土壤 氧化还原条件 傅里叶变换离子回旋共振质谱 

分 类 号：X53[环境科学与工程—环境工程]