Iron-bound carbon increases along a freshwater−oligohaline gradient in a subtropical tidal wetland

IF 9.8 1区 农林科学 Q1 SOIL SCIENCE
Jing Bai , Min Luo , Yang Yang , Shuyao Xiao , Zhifeng Zhai , Jiafang Huang
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引用次数: 23

Abstract

Globally, a vast extent of tidal wetlands will be threatened by sea-level-rise-induced salinization. Because ferric (hydro)oxides [Fe(III)] play a crucial role in soil organic carbon (SOC) preservation, understanding the responses of the Fe-bound C pool to increasing salinity could assist in accurate prediction of the changes in C stocks in the tidal wetland soils facing imminent sea-level rise. In this study, we investigated pools of Fe-bound C and SOC, C-degrading enzyme activity, Fe species contents and Fe-cycling bacteria, and plant properties along a salinity gradient from freshwater (0.0 ± 0.1 ppt; part per thousand) to oligohaline (2.6 ± 0.6 ppt) in a subtropical tidal wetland. Overall, the belowground biomass and the content of root Fe(III) plaque (a proxy of root oxygen loss potential) rose with the increasing salinity. Along the salinity gradient, the abundance of Gallionella (Fe-oxidizing bacteria) increased, but the abundance of Geobacter (Fe-reducing bacteria) decreased. The Fe(II):Fe(III) ratios decreased as salinity increased, implying that more Fe(II) was oxidized and immobilized into Fe(III) closer to the sea. Fe sulfides contents also elevated close to sea. The co-existence of Fe(III) and Fe sulfides at the oligohaline sites implied a high spatial heterogeneity of Fe distribution. During the growing season, the SOC pool generally decreased with increasing salinity, probably due to a reduction in aboveground-C input and enhanced activity of the C-degrading enzyme. The Fe-bound C pool was positively affected by the amorphous Fe(III) content and negatively related to the activity of phenol oxidase. The Fe-bound C pool generally rose along the salinity gradient, with the importance of Fe-bound C to SOC increasing from 18% to 29%. Altogether, our findings implied that when the imminent sea-level-rise-induced salinization occurs, the total soil C stock may generally decrease, but Fe-bound C will become increasingly important in protecting the rest of the C stocks in tidal wetland soils.

Abstract Image

亚热带潮汐湿地铁结合碳沿淡水-寡盐梯度增加
在全球范围内,大量的潮汐湿地将受到海平面上升引起的盐碱化的威胁。由于铁(氢)氧化物[Fe(III)]在土壤有机碳(SOC)保存中起着至关重要的作用,了解铁结合的C库对盐度增加的响应有助于准确预测面临即将到来的海平面上升的潮汐湿地土壤中C储量的变化。在本研究中,我们研究了淡水盐度梯度(0.0±0.1 ppt;(千分之一)到低盐(2.6±0.6 ppt)在亚热带潮汐湿地。总体而言,随着盐度的增加,地下生物量和根系铁(III)斑块含量(代表根系氧损失势)增加。沿盐度梯度,铁氧化菌Gallionella丰度升高,铁还原菌Geobacter丰度降低。随着盐度的增加,Fe(II):Fe(III)比值降低,表明更多的Fe(II)在靠近海洋的地方被氧化并固定化成Fe(III)。靠近海洋的地方,硫化铁含量也有所上升。Fe(III)和Fe硫化物在低盐位点的共存表明铁的分布具有高度的空间异质性。在生长季节,有机碳库总体上随盐度的增加而减少,这可能是由于地上碳输入减少和c降解酶活性增强所致。铁结合C池与非晶态铁(III)含量呈正相关,与酚氧化酶活性负相关。铁结合C库沿盐度梯度总体呈上升趋势,铁结合C对有机碳的重要性从18%上升到29%。总之,我们的研究结果表明,当海平面上升引起的盐渍化发生时,土壤总碳储量可能普遍减少,但铁结合的碳在保护潮汐湿地土壤中剩余的碳储量方面将变得越来越重要。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Soil Biology & Biochemistry
Soil Biology & Biochemistry 农林科学-土壤科学
CiteScore
16.90
自引率
9.30%
发文量
312
审稿时长
49 days
期刊介绍: Soil Biology & Biochemistry publishes original research articles of international significance focusing on biological processes in soil and their applications to soil and environmental quality. Major topics include the ecology and biochemical processes of soil organisms, their effects on the environment, and interactions with plants. The journal also welcomes state-of-the-art reviews and discussions on contemporary research in soil biology and biochemistry.
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