海南北部滨海区不同土地利用模式下土壤DOM粒径分布与光谱特性

吴月颖; 吉恒宽; 吴蔚东; 吴治澎; 解钰; 符佩娇

文章摘要

海南北部滨海区不同土地利用模式下土壤DOM粒径分布与光谱特性

Size fractionation and optical properties of DOM under different land use types in the coastal area of northern Hainan Island

Received:January 08, 2020

DOI：10.13254/j.jare.2020.0016

中文关键词: 溶解态有机质(DOM)，土地利用模式，粒径分布，光谱特征

英文关键词: dissolved organic matter (DOM), land use type, particle size, spectral characteristics

基金项目:海南省自然科学基金项目（418QN208）；国家自然科学基金项目（41807326）

Author Name	Affiliation	E-mail
WU Yue-ying	College of Tropical Crops, Hainan University, Haikou 570228, China
JI Heng-kuan	College of Tropical Crops, Hainan University, Haikou 570228, China
WU Wei-dong	College of Tropical Crops, Hainan University, Haikou 570228, China
WU Zhi-peng	College of Tropical Crops, Hainan University, Haikou 570228, China	peter@hainanu.edu.cn
XIE Yu	Institute of Agricultural Environment and Soil, Hainan Academy of Agricultural Sciences, Haikou 571100, China
FU Pei-jiao	College of Tropical Crops, Hainan University, Haikou 570228, China

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中文摘要:

为研究海南热带滨海区不同土地利用模式对土壤溶解态有机质（DOM）含量组成及其分子粒径依赖性的影响，分别采集琼北滨海地区四种代表性土地利用模式下（水稻田、菜园、果园和橡胶园）土壤为研究材料，通过超滤技术对土壤水提液进行分级（所选滤膜孔径大小分别为0.7、0.45、0.2、0.1 μm和100、10、1 kDa），并对样品中DOM的碳、氮含量和光谱特性（紫外-可见吸收光谱、三维荧光光谱、傅立叶变换红外光谱）进行表征。结果表明，四种地类土壤溶解态有机碳（DOC）含量（<0.7 μm）为水稻土（171.9 mg·kg^-1）最高，胶园土（116.7 mg·kg^-1）最低；而C/N值则为胶园土（22.26）最高，菜园土（11.39）最低。在不同粒径中，4种地类土壤DOC含量为<1 kDa组分占比最高（45%以上），C/N值则在<1 kDa粒径中最高（31.43），10~100 kDa中最低（4.80）。紫外-可见吸收光谱和红外光谱表明了水稻土和菜园土DOM的分子芳香性（SUVA₂₅₄）、分子量大小（S_R）和疏水组分（SUVA₂₆₀）比例显著高于胶园土和果园土，且含有较多的醇、酚、芳香类物质。三维荧光光谱特征表明四种土地利用模式土壤DOM的来源均为土壤微生物活动产生的“内源”。由此可见，不同的土地利用模式和粒径大小会影响土壤DOM的含量和组成结构，人类活动干扰是引起地类间DOM差异显著的重要因素。

英文摘要:

To evaluate the size-dependent quantity and composition of DOM, soil samples of different land use types (paddy fields, vegetable gardens, orchards, and rubber plantation) were collected from a typical coastal area of northern Hainan. The samples were fractionated through ultrafiltration with membranes of different pore-sizes (0.7, 0.45, 0.2, 0.1 μm and 100, 10, 1 kDa) and the carbon and nitrogen content of DOM and their spectral characteristics (UV-Vis absorption spectrum, three-dimensional fluorescence spectrum, and Fourier transform infrared spectrum) were analyzed. The results showed that paddy soil had the highest DOC content (171.9 mg·kg^-1), whereas rubber-plantation soil had the lowest content (116.7 mg·kg^-1). The C/N ratio of DOC content was the highest in rubber-plantation soil (22.26) and the lowest in vegetable-garden soil (11.39). Among different particle sizes of DOM, the proportions of soil DOC content and C/N ratio were the highest in the <1 kDa fraction for all land use types, but the C/N ratio was the lowest in the 10~100 kDa fraction. The characteristics of UV-Vis spectra and FTIR spectra indicated that the molecular aromaticity (SUVA₂₅₄), molecular weight size (S_R), and hydrophobic component ratio (SUVA₂₆₀) of paddy soil and vegetable-garden soil were significantly higher than those of rubberplantation soil and orchard soil, and contained more alcohol, phenol, and aromatic substances. 3D-EEM fluorescence spectra indicated that the source of soil DOM in the four land use types was endogenous DOM generated via soil microbial activities. Thus, different land use types and particle sizes affect the content and composition of soil DOM, and the interference from human activities is an important factor causing the significant difference of DOM between land use types.

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