Soil Organic Carbon and Geochemical Characteristics on Different Rocks and Their Significance for Carbon Cycles

Soil organic carbon (SOC) is significant for soil quality and global carbon cycles. SOC was observed to be related to soil geochemistry, and soils originating from different bedrocks have different geochemical properties, but the effect of bedrock on SOC is still undefined. Soils overlying different bedrocks in Zhenxiong County and Weixin County were sampled. Specifically, soils in the mineral horizon, which are less affected by the external environment than surface soils, are focused on to reveal the effect of bedrock on SOC. Al/Ti, Fe/Ti, and Al/Fe indicate a soil–rock successive relationship. SOC contents in the mineral horizon are 0.19–2.74% (1.24% on average), and those in the surface horizon are 1.26–4.01% (2.63% on average). SOC contents in the surface and mineral horizons of the same bedrock are significantly positively correlated, implying that the bedrock is an important factor affecting SOC. SOC in the mineral horizon is related to the first transition metal ions. Significantly, positive correlations of SOC (p < 0.01) with Co, Cu, Ti, V, and Zn, and a positive correlation (p < 0.05) with Ni were observed in the mineral horizon. Organic transition metal complexation seems to play an important role in governing SOC in the mineral horizon. That is, the complexation maintains organic carbon stability, slows down its decomposition rate, and accumulates organic carbon. The Ca–SOC positive correlation in the mineral horizon exits because Ca also can complex with organic carbon. Co, Cu, and V–SOC positive correlations (p < 0.05) were also observed, but there were no significant positive correlations (p < 0.01) in the surface horizon because surface SOC had diversified sources. An SOC evolution model influenced by the bedrock was forwarded. Thus, the different soil geochemistry originating from different bedrocks should be noticed when SOC and global carbon cycles are discussed.

Download Full-text

Effects of vegetation restoration on soil organic carbon redistribution along the Loess slope

10.5194/egusphere-egu2020-2481 ◽

2020 ◽

Author(s):

Xiaoxia Zhang ◽

Xiang Li ◽

Yipeng Liang ◽

Tonggang Zha

Keyword(s):

Spatial Distribution ◽

Soil Erosion ◽

Organic Carbon ◽

Soil Organic Carbon ◽

Effective Means ◽

Vegetation Restoration ◽

Managed Forests ◽

Carbon Cycles ◽

Loess Slope ◽

The Impact

Soil organic carbon (SOC) redistribution along the Loess slope under the effect of soil erosion plays an important role in understanding mechanism of SOC spatial distribution and turnover, hence to its effects on global carbon cycle. Vegetation restoration has been taken as an effective method to alleviate soil erosion on the Loess Plateau, while little research focused on the impact of vegetation restoration on the redistribution processes, especially the spatial distribution and stability of SOC. Here, we quantified the SOC stock and pool distribution on the loess slopes along geomorphic gradients under naturally regenerating forests (NF) and artificial black locust plantation (BP), using corn field as a control (CK).The results were as follows: &#160;(1) vegetation restoration, especially NF, effectively slowed down the migration of SOC resulting from soil erosion and reduced the heterogeneity of SOC distribution. The ratios of topsoil SOC in the sedimentary area to the stable area were 109%, 143%, and 210% under the NF, BP, and CK, respectively. And (2) Vegetation restoration reduced the loss of labile organic carbon by alleviating the loss of dissolved organic carbon (DOC) and easily oxidized organic carbon (EOC) during migration. Both DOC/SOC and EOC/SOC ratios under NF and BP presented far less differences between the sedimentary and erosion zones than CK.A schematic diagram of SOC cycle patterns and redistribution along the loess slope under vegetation restoration based on our findings and discussions. The results suggested that vegetation restoration in the Loess slope, NF in particular, was an effective means for alleviating the redistribution and spatial heterogeneity of SOC and reducing soil erosion. Information from this study is useful for understanding the carbon cycles in restored ecosystems and evaluating the ecosystem services of natural and managed forests in soil erosion control and carbon sequestration.

Download Full-text

First Pan-Arctic Assessment of Dissolved Organic Carbon Concentration in Permafrost-Region Lakes

10.5194/egusphere-egu2020-8174 ◽

2020 ◽

Author(s):

Lydia Stolpmann ◽

Anne Morgenstern ◽

Julia Boike ◽

Michael Fritz ◽

Ulrike Herzschuh ◽

...

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Carbon Content ◽

Permafrost Region ◽

Organic Carbon Content ◽

Soil Organic Carbon Content ◽

Doc Concentration ◽

Deposit Type ◽

Relationship Of ◽

Global Carbon

Permafrost-region lakes are dynamic landscape systems and play an important role for climate change feedbacks. Lake processes such as mineralization and flocculation of DOC, one of the main carbon fraction in lakes, contribute to the global carbon cycle. These processes are in focus of climate research but studies have been limited in geographic extent. We synthesized published datasets and unpublished datasets from the author team totaling 1,691 water samples from 1,387 lakes across the Subarctic and Arctic in permafrost regions of Alaska, Canada, Siberia, and Greenland to provide first insights for linkages between DOC concentration to the basin. In our synthesis, we find regional differences in DOC concentration of permafrost-region lakes. We focussed on relations between lake DOC concentration and latitude, permafrost zones, ecoregions, lake surrounding deposit type, and ground ice classification of each lake basin. Additionally, we analysed the lake surrounding soil organic carbon content from 0-100 cm depth and 0-300 cm depth. Individual lake DOC concentrations of our dataset range from below detection limit assigned to 0 mg L-1 (North Slope, Alaska) to 1,130 mg L-1 (Yukon Flats, Alaska). We found regional median lake DOC concentrations of 18.8 mg L-1 (Greenland, n=25), 12.2 mg L-1 (Alaska, n= 1,135), 9.6 mg L-1 (Siberia, n=252), and 7.2 mg L-1 (Canada, n=279). Lakes in the isolated permafrost zone had the highest median DOC concentration compared to lakes in the sporadic, discontinuous, and continuous permafrost zones. Our synthesis shows increasing lake DOC concentration with decreasing latitude and, due to a larger availability of biomass and organic carbon, a significant relationship of lake DOC concentration and ecoregion of the lake. We found higher lake DOC concentrations in boreal permafrost sites compared to tundra sites. About 22 % of lakes in our dataset are located in regions with ice-rich syngenetic permafrost deposits (yedoma). Because yedoma contains large amounts of organic carbon, we assumed to find higher DOC concentrations in yedoma lakes compared to non-yedoma lakes. Our analysis shows a significant relationship of lake DOC concentration and surrounding deposit type but not a higher DOC concentration in yedoma lakes compared to non-yedoma lakes. Finally, we found a relationship of soil organic carbon content from 0-100 cm depth and lake DOC concentration. In contrast, a comparison of soil organic carbon content from 0-300 cm depth and lake DOC concentration shows no significant correlation. This was also found for ground-ice content and lake DOC concentration. Our dataset of lakes across the Arctic shows that the DOC concentration of a lake strongly depends on its environmental properties. This dataset will be fundamental to establish a pan-Arctic lake DOC pool for estimations of the impact of lake DOC on the global carbon cycle and further on climate change.

Download Full-text

Surface soil organic carbon in temperate and subtropical oriental oak stands of East China

Canadian Journal of Forest Research ◽

10.1139/cjfr-2015-0324 ◽

2016 ◽

Vol 46 (5) ◽

pp. 621-628 ◽

Cited By ~ 4

Author(s):

Wenjuan Yu ◽

Timothy J. Fahey ◽

Hongzhang Kang ◽

Pisheng Zhou

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Isotopic Composition ◽

Climatic Factors ◽

Soil Depth ◽

East China ◽

Clear Trend ◽

Mineral Horizon ◽

Forest Sites ◽

Surface Mineral

Forest ecosystems contain large amounts of soil organic carbon (SOC), which is a major component of biogeochemical cycles that may be sensitive to environmental change. We used a combination of nuclear magnetic resonance (NMR) spectroscopy and elemental and isotopic composition to examine the influence of soil properties and climatic factors on the quantity and degree of decomposition of SOC for organic and surface mineral horizons in seven oriental oak (Quercus variabilis Blume) forest sites arranged across a 11o latitudinal gradient in East China. Lacking Oa horizons, the two southernmost sites contained lower amounts of SOC in the forest floor horizon, but otherwise, latitudinal trends were not consistent. The SOC stock in the 0–10 cm mineral horizon exhibited no clear trend along the gradient and had a negative association with clay + silt content. Based on a higher alkyl/O-alkyl (A/O) ratio and alkyl/methoxyl (A/M) ratio, the SOC at the 0–10 cm depth appeared to be relatively more decomposed in three of the four southern subtropical sites. However, the degree of SOC degradation also decreased strongly with increasing soil pH (R2 = 0.90, P = 0.001). Soil organic carbon exhibited increases in δ13C and δ15N and decreases in the C/N ratio with depth for all the seven sites, indicating an increase in its extent of decomposition. Our analysis indicated that the A/M ratio from NMR provided the best indication of the extent of SOC degradation along the latitudinal transect, whereas the elemental and isotopic composition better reflected patterns with soil depth.

Download Full-text

Influence of altitudes of coffee plants on the alkaloids contents of green coffee beans

10.31221/osf.io/u6vqh ◽

2019 ◽

Author(s):

Chem Int

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Soil Ph ◽

Negative Correlation ◽

Green Coffee ◽

Positive Correlation ◽

Green Coffee Beans ◽

Coffee Beans ◽

Weak Negative Correlation ◽

Coffee Plants

The influence of altitude of coffee plant and soil pH and organic carbon on alkaloid contents of green coffee beans was evaluated. The alkaloids content of 54 green coffee beans samples collected from coffee plants in Sidama, Illubabor, Jimma, Wellega and Gedeo grown at different altitudes (1515-2220 masl) was determined by high performance liquid chromatography. The caffeine and trigonelline were found in the range of 0.68-1.74% (w/w) and 0.68-1.44% (w/w), respectively. Theobromine was detected in only 18 samples and ranged 0.0186-0.32% (w/w). Theophylline was not detected in any of the green coffee beans samples. A weak negative correlation (R = -0.222) was found between the caffeine contents and the altitude of the coffee plants while a very weak positive correlation (R = 0.072) was found between the trigonelline contents and the altitude of the coffee plants. A strong negative correlation (R = -0.775) was found between the trigonelline contents and the caffeine content. A weak negative correlation was found between the caffeine contents and the soil organic carbon (R = -0.279) and between the trigonelline contents and the soil organic carbon (R = -0.101) while a weak positive correlation was found between the caffeine contents and the soil pH (R = 0.173) and between the trigonelline contents and the soil pH (R = 0.358) at which the coffee plants were grown.

Download Full-text

Mobile Colloidal Organic Carbon: An Underestimated Carbon Pool in Global Carbon Cycles?

Frontiers in Environmental Science ◽

10.3389/fenvs.2018.00148 ◽

2018 ◽

Vol 6 ◽

Cited By ~ 4

Author(s):

Jing Yan ◽

Ronald Manelski ◽

Bruce Vasilas ◽

Yan Jin

Keyword(s):

Organic Carbon ◽

Carbon Pool ◽

Carbon Cycles ◽

Global Carbon

Download Full-text

Rethinking global carbon storage potential of trees. A comment on Bastin et al. 2019

10.1101/730325 ◽

2019 ◽

Cited By ~ 1

Author(s):

Shawn D. Taylor ◽

Sergio Marconi

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Carbon Storage ◽

Canopy Cover ◽

Tree Cover ◽

Empirical Relationships ◽

Storage Potential ◽

Global Carbon ◽

Global Datasets ◽

Potential Carbon

AbstractKey MessageBastin et al. 2019 used flawed assumptions in calculating the carbon storage of restored forests worldwide, resulting in a gross overestimate.ContextBastin et al. 2019 use two flawed assumptions: 1) that the area suitable for restoration does not contain any carbon currently, and 2) that soil organic carbon (SOC) from increased canopy cover will accumulate quickly enough to mitigate anthropogenic carbon emissions.AimsWe re-evaluated the potential carbon storage worldwide using empirical relationships of tree cover and carbon.Methods and ResultsWe use global datasets of tree cover, soil organic carbon, and above ground biomass to estimate the empirical relationships of tree cover and carbon stock storage. A more realistic range of global carbon storage potential is between 71.7 and 75.7 GtC globally, with a large uncertainty associated with SOC. This is less than half of the original 205 GtC estimate.ConclusionThe potential global carbon storage of restored forests is much less than that estimated by Bastin et al. 2019. While we agree on the value of assessing global reforestation potential, we suggest caution in considering it the most effective strategy to mitigate anthropogenic emissions.

Download Full-text

Modeling soil organic carbon as a function of topography and forest characteristics

10.21203/rs.3.rs-52265/v1 ◽

2020 ◽

Author(s):

Rajesh Malla ◽

Prem Raj Neupane ◽

Michael Köhl

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

National Level ◽

Basal Area ◽

Crown Cover ◽

Independent Variable ◽

Terrain Elevation ◽

A Minor ◽

Forest Carbon Pools ◽

Global Carbon

Abstract BackgroundThe soil organic carbon (SOC), an important carbon pool among the five forest carbon pools, plays a crucial role in global carbon cycling. However, it is affected by various factors like topography and climate. Some studies conducted for smaller areas have shown a dependence of the SOC on altitude, but do not allow a general statement for larger regions. Nepal, which has the world's most dynamic terrain elevation, is ideally suited for studying the dependence of the SOC on altitude. ResultsWe found a significant correlation between SOC and altitude (r=0.81). In our study, altitude alone can explain about 66 percent of the variability of the SOC. On the basis of our data, we developed a model which, with altitude as the only independent variable, can predict around 61 percent of the SOC. ConclusionsOnly altitude has been found to be a sound predictor of SOC at the national level. Other factors with potential impacts on SOC predictors such as crown cover, slope or basal area have only a minor contribution to the improvement of prediction accuracy of the model.

Download Full-text

First pan-Arctic assessment of dissolved organic carbon in lakes of the permafrost region

Biogeosciences ◽

10.5194/bg-18-3917-2021 ◽

2021 ◽

Vol 18 (12) ◽

pp. 3917-3936

Author(s):

Lydia Stolpmann ◽

Caroline Coch ◽

Anne Morgenstern ◽

Julia Boike ◽

Michael Fritz ◽

...

Keyword(s):

Climate Change ◽

Organic Carbon ◽

Soil Organic Carbon ◽

Carbon Cycle ◽

Dissolved Organic Carbon ◽

Significant Relationship ◽

Global Carbon Cycle ◽

Doc Concentration ◽

Global Carbon ◽

Permafrost Regions

Abstract. Lakes in permafrost regions are dynamic landscape components and play an important role for climate change feedbacks. Lake processes such as mineralization and flocculation of dissolved organic carbon (DOC), one of the main carbon fractions in lakes, contribute to the greenhouse effect and are part of the global carbon cycle. These processes are in the focus of climate research, but studies so far are limited to specific study regions. In our synthesis, we analyzed 2167 water samples from 1833 lakes across the Arctic in permafrost regions of Alaska, Canada, Greenland, and Siberia to provide first pan-Arctic insights for linkages between DOC concentrations and the environment. Using published data and unpublished datasets from the author team, we report regional DOC differences linked to latitude, permafrost zones, ecoregions, geology, near-surface soil organic carbon contents, and ground ice classification of each lake region. The lake DOC concentrations in our dataset range from 0 to 1130 mg L−1 (10.8 mg L−1 median DOC concentration). Regarding the permafrost regions of our synthesis, we found median lake DOC concentrations of 12.4 mg L−1 (Siberia), 12.3 mg L−1 (Alaska), 10.3 mg L−1 (Greenland), and 4.5 mg L−1 (Canada). Our synthesis shows a significant relationship between lake DOC concentration and lake ecoregion. We found higher lake DOC concentrations at boreal permafrost sites compared to tundra sites. We found significantly higher DOC concentrations in lakes in regions with ice-rich syngenetic permafrost deposits (yedoma) compared to non-yedoma lakes and a weak but significant relationship between soil organic carbon content and lake DOC concentration as well as between ground ice content and lake DOC. Our pan-Arctic dataset shows that the DOC concentration of a lake depends on its environmental properties, especially on permafrost extent and ecoregion, as well as vegetation, which is the most important driver of lake DOC in this study. This new dataset will be fundamental to quantify a pan-Arctic lake DOC pool for estimations of the impact of lake DOC on the global carbon cycle and climate change.

Download Full-text

Study on spatial-temporal change of soil organic carbon and impact factors in Gudao Forestry Farm of Dongying

E3S Web of Conferences ◽

10.1051/e3sconf/201911803014 ◽

2019 ◽

Vol 118 ◽

pp. 03014

Author(s):

Shengnan Zhang ◽

Zhanhong Liu ◽

Luo Fang ◽

Baolin Wu ◽

Yurui Li ◽

...

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Significant Positive Correlation ◽

Lower Layer ◽

Soil Layer ◽

Impact Factors ◽

Forest Types ◽

Forest Land ◽

Positive Correlation ◽

Bare Land

Soil organic carbon (SOC) is one of the important properties to evaluate soil quality, which can indirectly reflect the effect of afforestation on saline-alkali land. In this study, 4 different forest types in Gudao Forestry Centre were selected as experimental plots, and bare land was set as blank group. Spatial differentiation and impact factors of SOC between different forest types were studied by field investigation and laboratory experiment. The results show that (1) SOC content in the study area is lower than 1%. SOC content in forest land is higher than that in bare land. In the upper soil layer, the SOC content of Robinia Pseudoacacia forest is lower, and mixed forest is higher. SOC content of bare land is higher than that of forest land in the lower layer. (2) SOC has a significant positive correlation with available nutrients (P<0.05), and has a weak correlation with pH and water content. There are different correlations with conductivity and bulk density in different soil layers, and they all showed a negative correlation at the upper layer, and a significant positive correlation at the lower layer (P<0.05).

Download Full-text

Spatiotemporal Differentiation of Soil Organic Carbon of Grassland and Its Relationship with Soil Physicochemical Properties on the Northern Slope of Qilian Mountains, China

Sustainability ◽

10.3390/su12229396 ◽

2020 ◽

Vol 12 (22) ◽

pp. 9396

Author(s):

Le Yang ◽

Wenxiong Jia ◽

Yang Shi ◽

Zhiyuan Zhang ◽

Hui Xiong ◽

...

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Carbon Cycle ◽

Physicochemical Properties ◽

Soil Depth ◽

Global Carbon Cycle ◽

Qilian Mountains ◽

Forest Steppe ◽

Northern Slope ◽

Global Carbon

The soil organic carbon pool is an important part of the global carbon cycle, and its accumulation and decomposition affect the balance of the global carbon cycle. It is important to understand scientifically the temporal and spatial variation of soil organic carbon (SOC) and its influencing factors, which could aid further understanding of the accumulation and decomposition of SOC. In order to reveal the relationship between soil organic carbon and soil’s physicochemical properties, six plots were selected on the east, middle and west of forest steppes and typical grasslands on the northern slope of Qilian Mountains during two consecutive growing seasons from 2013 to 2014. Soil samples under 0–30 cm were used to study the spatiotemporal differentiation of SOC and its relationship with the soil’s physicochemical properties in the grassland of the study area. The results show that the content of SOC in the grassland in 2013 was higher than that in 2014, and that it decreased gradually from east to west. The content of SOC is significantly different between the soil layer of 0–10 cm and the soil layers of 10–20 cm and 20–30 cm (p < 0.05), and it decreases with increases in soil depth. The SOC content on forest steppe is higher than that on typical grassland. Significant positive correlations appear between SOC with soil water content and soil nutrients (alkaline nitrogen, available phosphorus, available potassium) (p < 0.01), but there are significant negative correlations between SOC and soil temperature, soil pH, and soil electrical conductivity (p < 0.01).

Download Full-text