Carbon-nitrogen isotope coupling of soil organic matter in a karst region under land use change, Southwest China

Han, Guilin; Tang, Yang; Zwieten, Lukas Van; Yang, Xiaomin; Yu, Changxun; Wang, Hailong; Song, Zhaoliang

doi:10.1016/j.agee.2020.107027

Cited by 120 publications

(65 citation statements)

References 62 publications

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“…Salinity is a prevalent environmental stressor with a great potential to affect C source and sink functions in coasts and estuaries (Morrissey et al., 2014; Qu et al., 2019; Stagg et al., 2017). Previous studies have revealed that SOM contents depend mainly on plant functional traits (Han et al., 2020; Jobbagy & Jackson, 2000). Commonly, decreases in plant productivity, species richness, and diversity (Molina et al., 2003; Tuxen et al., 2011; Wang, Li, et al., 2015), as well as differences in belowground biomass allocation (Pierfelice et al., 2017) and species composition (Amores et al., 2013) were observed, with all of vegetation distributions orienting along a salinity gradient (Table S1).…”

Section: Discussionmentioning

confidence: 99%

“…Salinity is a prevalent environmental stressor with a great potential to affect C source and sink functions in coasts and estuaries (Morrissey et al, 2014;Qu et al, 2019;Stagg et al, 2017). Previous studies have revealed that SOM contents depend mainly on plant functional traits (Han et al, 2020;Jobbagy & Jackson, 2000).…”

Section: Factors Controlling the Distribution Of Sommentioning

confidence: 99%

“…Furthermore, as organic matter decomposition strongly accelerates soil N turnover rates and losses, the residual N pool will also be enriched in the δ 15 N values (Amundson et al., 2003; Han et al., 2020), and thus the natural abundances of δ 15 N may be used as a decomposition indicator. Typical δ 15 N signatures of terrestrial C 3 plants ranged from 0‰ to 11‰ (Huygens et al., 2013; Ranjan et al., 2011), while the δ 15 N values of seagrass and marine microalgae were in the range of 6‰–12‰ and 0‰–4‰, respectively (Samper‐Villarreal et al., 2016).…”

Section: Introductionmentioning

confidence: 99%

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Distribution, sources, and decomposition of soil organic matter along a salinity gradient in estuarine wetlands characterized by C:N ratio, δ¹³C‐δ¹⁵N, and lignin biomarker

Xia

Song

et al. 2020

Global Change Biology

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Despite increasing recognition of the critical role of coastal wetlands in mitigating climate change, sea‐level rise, and salinity increase, soil organic carbon (SOC) sequestration mechanisms in estuarine wetlands remain poorly understood. Here, we present new results on the source, decomposition, and storage of SOC in estuarine wetlands with four vegetation types, including single Phragmites australis (P, habitat I), a mixture of P. australis and Suaeda salsa (P + S, habitat II), single S. salsa (S, habitat III), and tidal flat (TF, habitat IV) across a salinity gradient. Values of δ13C increased with depth in aerobic soil layers (0–40 cm) but slightly decreased in anaerobic soil layers (40–100 cm). The δ15N was significantly enriched in soil organic matter at all depths than in the living plant tissues, indicating a preferential decomposition of 14N‐enriched organic components. Thus, the kinetic isotope fractionation during microbial degradation and the preferential substrate utilization are the dominant mechanisms in regulating isotopic compositions in aerobic and anaerobic conditions, respectively. Stable isotopic (δ13C and δ15N), elemental (C and N), and lignin composition (inherited (Ad/Al)s and C/V) were not completely consistent in reflecting the differences in SOC decomposition or accumulation among four vegetation types, possibly due to differences in litter inputs, root distributions, substrate quality, water‐table level, salinity, and microbial community composition/activity. Organic C contents and storage decreased from upstream to downstream, likely due to primarily changes in autochthonous sources (e.g., decreased onsite plant biomass input) and allochthonous materials (e.g., decreased fluvially transported upland river inputs, and increased tidally induced marine algae and phytoplankton). Our results revealed that multiple indicators are essential to unravel the degree of SOC decomposition and accumulation, and a combination of C:N ratios, δ13C, δ15N, and lignin biomarker provides a robust approach to decipher the decomposition and source of sedimentary organic matter along the river‐estuary‐ocean continuum.

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Section: Discussionmentioning

confidence: 99%

Section: Factors Controlling the Distribution Of Sommentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Distribution, sources, and decomposition of soil organic matter along a salinity gradient in estuarine wetlands characterized by C:N ratio, δ¹³C‐δ¹⁵N, and lignin biomarker

Xia

Song

et al. 2020

Global Change Biology

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“…The enrichment of REEs in the processes of plant growth and decay can lead to the increasing ΣREE in the surface soils [ 53 ]. The organic matter contents of forest surface soil are generally higher than those of other types of soils, and REEs can be strongly complexed by the organic matter under neutral pH, which also improves the stability of REEs [ 54 , 55 ]. Generally, the content of soil organic carbon (SOC) in abandoned cropland is low, but it can increase slowly in a short time once the abandoned cultivation period is over [ 56 , 57 , 58 , 59 ].…”

Section: Resultsmentioning

confidence: 99%

Geochemical Behaviors of Rare Earth Elements (REEs) in Karst Soils under Different Land-Use Types: A Case in Yinjiang Karst Catchment, Southwest China

Han

2021

IJERPH

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The geochemical characteristics of rare earth elements (REEs) can be employed to identify the anthropogenic and natural influence on the distributions of REEs in soils. A total of 47 soil samples from the three soil profiles of the secondary forest land, abandoned cropland, and shrubland in the Yinjiang county of Guizhou province, southwest China, were collected to determine the contents and distribution of REEs in the soil environment. The total REEs (ΣREE) contents in different soil profiles are in the following sequence: secondary forest land (mean: 204.59 mg·kg−1) > abandoned cropland (mean: 186.67 mg·kg−1) > shrubland (mean: 139.50 mg·kg−1). The ratios of (La/Gd)N and (Gd/Yb)N ranged from 0.62 to 1.00 and 1.18 to 2.16, which indicated that the enrichment of the medium rare earth elements (MREEs) was more obvious than that of the light rare earth elements (LREEs) and the heavy rare earth elements (HREEs). The phenomenon could be attributed to the preferential absorption of MREEs by fine particles and the substitution of Ca2+ by MREEs. Most soil samples were characterized by the negative Ce anomalies (anomalies values: 0.30–1.10) and positive Eu anomalies (anomalies values: 0.43–2.90). The contents of REEs in the profiles of secondary forest land and shrubland were mainly regulated by soil pH and Fe contents while clay content and agricultural activities were the main controlling factors in the soil profile of abandoned cropland. This study highlights the role of agricultural activities in affecting the distributions of REEs in karst soils, which could provide some insights for the protection of the soil environment.

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“…Accelerating chemical weathering can be the reason. A rainstorm can accelerate the erosion of the rock and soil [87]; meanwhile, rainwater falling into the river also increases the amounts of ions in water. As shown in Figure 7, the United States salinity laboratory diagram (USSL) and Wilcox diagrams are used to indicate the potential salinity hazard in the TGR.…”

Section: Potential Risks To Water Quality From Chemical Weatheringmentioning

confidence: 99%

Major Elements in the Upstream of Three Gorges Reservoir: An Investigation of Chemical Weathering and Water Quality during Flood Events

Wang

Han

et al. 2021

Water

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Rivers transport terrestrial matter into the ocean, constituting a fundamental channel between inland and oceanic ecosystem and affect global climate change. To reveal chemical weathering processes and environmental health risks during flood periods, water samples were collected in the upper reaches of Three Gorges Reservoir (TGR) in 2020. HCO3− and Ca2+ were the most abundant anions and cations of the river water, respectively. The range of HCO3− concentration was between 1.81 and 3.02 mmol/L, while the mean content of Ca2+ was 1.03 mmol/L. The results of the Piper diagram and element ratios revealed that the river solutes were mainly contributed by carbonate weathering and gypsum-rich evaporite dissolution. A mass balance model indicated that the contribution order of sources to cations in the main channel (Yibin-Luzhou) was evaporites > carbonates > atmospheric input > silicates. The order in the Chongqing—Three Gorges Dam was carbonates > atmospheric input > evaporites > silicates. These results showed a lithologic control on hydrochemical characteristics. Most sampling sites were suitable for agricultural irrigation according to the water quality assessment. However, indexes sodium adsorption ratio (SAR) and soluble sodium percentage (Na%) were higher than 1.0 in Yibin-Luzhou and 30% in Yibin–Chongqing, respectively, suggesting a potential sodium hazard. In addition, except Tuojiang River and Shennong River, the risk of sodium hazard in tributaries was relatively low. High Na+ concentration in irrigation water can damage soil structure and function and ultimately affect agricultural production. Water quality in the upstream of a Piper diagram should attract enough attention.

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Carbon-nitrogen isotope coupling of soil organic matter in a karst region under land use change, Southwest China

Cited by 120 publications

References 62 publications

Distribution, sources, and decomposition of soil organic matter along a salinity gradient in estuarine wetlands characterized by C:N ratio, δ¹³C‐δ¹⁵N, and lignin biomarker

Distribution, sources, and decomposition of soil organic matter along a salinity gradient in estuarine wetlands characterized by C:N ratio, δ¹³C‐δ¹⁵N, and lignin biomarker

Geochemical Behaviors of Rare Earth Elements (REEs) in Karst Soils under Different Land-Use Types: A Case in Yinjiang Karst Catchment, Southwest China

Major Elements in the Upstream of Three Gorges Reservoir: An Investigation of Chemical Weathering and Water Quality during Flood Events

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Carbon-nitrogen isotope coupling of soil organic matter in a karst region under land use change, Southwest China

Cited by 120 publications

References 62 publications

Distribution, sources, and decomposition of soil organic matter along a salinity gradient in estuarine wetlands characterized by C:N ratio, δ13C‐δ15N, and lignin biomarker

Distribution, sources, and decomposition of soil organic matter along a salinity gradient in estuarine wetlands characterized by C:N ratio, δ13C‐δ15N, and lignin biomarker

Geochemical Behaviors of Rare Earth Elements (REEs) in Karst Soils under Different Land-Use Types: A Case in Yinjiang Karst Catchment, Southwest China

Major Elements in the Upstream of Three Gorges Reservoir: An Investigation of Chemical Weathering and Water Quality during Flood Events

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Distribution, sources, and decomposition of soil organic matter along a salinity gradient in estuarine wetlands characterized by C:N ratio, δ¹³C‐δ¹⁵N, and lignin biomarker

Distribution, sources, and decomposition of soil organic matter along a salinity gradient in estuarine wetlands characterized by C:N ratio, δ¹³C‐δ¹⁵N, and lignin biomarker