scholarly journals Total and dissolved soil organic and inorganic carbon and their relationships in typical loess cropland of Fengu Basin

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Tongping Lu ◽  
Xiujun Wang ◽  
Wenxi Zhang
Keyword(s):  
Organic Carbon ◽  
Soil Carbon ◽  
Loess Plateau ◽  
Soil Ph ◽  
Negative Correlation ◽  
Inorganic Carbon ◽  
Yellow River ◽  
The Yellow River ◽  
Hydrological Process ◽  
Complex Relationships

Abstract There is evidence of connections between soil organic carbon (SOC) and inorganic carbon (SIC) in dryland of north China. However, fractions of SOC and SIC and the relationship are not well understood in the Loess Plateau that undergoes profound erosion and redeposition. A study was conducted in low-elevation cropland of Loess Plateau across two distinctive basins: Linfen basin (LFB) with lower soil pH (< 8.4) and subject to erosion–redeposition, and Yuncheng basin (YCB) with higher soil pH (> 8.6) and under the influence of the Yellow River. Soil samples were collected from 30 sites over 100 cm. We determined SOC, SIC, dissolved organic carbon (DOC) and other properties. Above 100 cm, SOC stock is significantly higher in LFB (10.0 ± 2.6 kg C m−2) than in YCB (6.9 ± 1.5 kg C m−2), but SIC lower in LFB (14.0 ± 2.5 kg C m−2) than in YCB (17.0 ± 5.7 kg C m−2). We find a significantly negative correlation between SOC and SIC stocks in LFB, but no clear relationship in YCB. DOC:SOC ratio (an indicator for DOC desorption or SOC stability) is significantly higher below 40 cm in YCB (1.9%) than LFB (1.2%), indicating stronger DOC desorption in YCB that has stronger hydrological process due to the influence of the Yellow River. Overall, SOC has a negative correlation with SIC and soil pH, and DOC:SOC ratio has a significantly positive correlation with soil pH. Our analyses suggest that erosion/re-deposition of topsoil is partly responsible for the negative SIC-SOC relationship in LFB, and high soil pH and stronger hydrological processes are attributable to relatively lower levels of SOC in YCB. This study highlights that soil carbon fractions in the lowland of Loess Plateau are influenced by many drivers, which leads to complex relationships between major soil carbon pools.

scholarly journals Total and dissolved soil organic and inorganic carbon and their relationships in typical loess cropland of Fenggu Basin

2020 ◽  
Author(s):  
Tongping Lu ◽  
Xiujun Wang ◽  
Wenxi Zhang
Keyword(s):  
Organic Carbon ◽  
Soil Carbon ◽  
Loess Plateau ◽  
Soil Ph ◽  
Negative Correlation ◽  
Inorganic Carbon ◽  
Yellow River ◽  
The Yellow River ◽  
Hydrological Process ◽  
Complex Relationships

Abstract There is evidence of connections between soil organic carbon (SOC) and inorganic carbon (SIC) in dryland of north China. However, fractions of SOC and SIC and the relationship are not well understood in the Loess Plateau that undergoes profound erosion and redeposition. A study was conducted in low-elevation cropland of Loess Plateau across two distinctive basins: Linfen basin (LFB) with lower soil pH (<8.4) and subject to erosion-redeposition, and Yuncheng basin (YCB) with higher soil pH (>8.6) and under the influence of the Yellow River. Soil samples were collected from 30 sites over 100 cm. We determined SOC, SIC, dissolved organic carbon (DOC) and other properties. Above 100 cm, SOC stock is significantly higher in LFB (10.0±2.6 kg C m-2) than in YCB (6.9±1.5 kg C m-2), but SIC lower in LFB (14.0±2.5 kg C m-2) than in YCB (17.0±5.7 kg C m-2). We find a significantly negative correlation between SOC and SIC stocks in LFB, but no clear relationship in YCB. DOC:SOC ratio (an indicator for DOC desorption or SOC stability) is significantly higher below 40 cm in YCB (1.9%) than LFB (1.2%), indicating stronger DOC desorption in YCB that has stronger hydrological process due to the influence of the Yellow River. Overall, SOC has a negative correlation with SIC and soil pH, and DOC:SOC ratio has a significantly positive correlation with soil pH. Our analyses suggest that erosion/re-deposition of topsoil is partly responsible for the negative SIC-SOC relationship in LFB, and high soil pH and stronger hydrological processes are attributable to relatively lower levels of SOC in YCB. This study highlights that soil carbon fractions in the lowland of Loess Plateau are influenced by many drivers, which leads to complex relationships between major soil carbon pools.

scholarly journals Fractions of soil organic and inorganic carbon and their relationships in typical loess cropland of Fenggu Basin

2020 ◽  
Author(s):  
Tongping Lu ◽  
Xiujun Wendy Wang ◽  
Wenxi Zhang
Keyword(s):  
Organic Carbon ◽  
Soil Carbon ◽  
Loess Plateau ◽  
Soil Ph ◽  
Negative Correlation ◽  
Inorganic Carbon ◽  
Yellow River ◽  
The Yellow River ◽  
Hydrological Process ◽  
Complex Relationships

Abstract There is evidence of connections between soil organic carbon (SOC) and inorganic carbon (SIC) in dryland of north China. However, fractions of SOC and SIC and the relationship are not well understood in the Loess Plateau that undergoes profound erosion and redeposition. A study was conducted in low-elevation cropland of Loess Plateau across two distinctive basins: Lingfeng basin (LFB) with lower soil pH (< 8.4) and subject to erosion-redeposition, and Yuncheng basin (YCB) with higher soil pH (> 8.6) and under the influence of the Yellow River. Soil samples were collected from 30 sites over 100 cm. We determined SOC, SIC, dissolved organic carbon (DOC) and other properties. Above 100 cm, SOC stock is significantly higher in LFB (10.0 ± 2.6 kg C m− 2) than in YCB (6.9 ± 1.5 kg C m− 2), but SIC lower in LFB (14.0 ± 2.5 kg C m− 2) than in YCB (17.0 ± 5.7 kg C m− 2). We find a significantly negative correlation between SOC and SIC stocks in LFB, but no clear relationship in YCB. On average, DOC:SOC ratio is significantly higher below 40 cm in YCB (1.9%) than LFB (1.2%), indicating stronger DOC desorption in YCB that has stronger hydrological process due to the influence of the Yellow River. Overall, SOC has a negative correlation with SIC and soil pH, and DOC:SOC ratio has a significantly positive correlation with soil pH. Our analyses suggest that erosion/re-deposition of topsoil is partly responsible for the negative SIC-SOC relationship in LFB, and high soil pH and stronger hydrological processes are attributable to relatively lower levels of SOC in YCB. This study highlights that soil carbon fractions in the lowland of Loess Plateau are influenced by many drivers, which leads to complex relationships between major soil carbon pools.

scholarly journals Organic carbon transport and impacts of human activities in the Yellow River

2012 ◽  
Vol 9 (10) ◽  
pp. 14365-14405 ◽  
Author(s):  
L. J. Zhang ◽  
L. Wang ◽  
W.-J. Cai ◽  
D. M. Liu ◽  
Z. G. Yu
Keyword(s):  
Organic Carbon ◽  
Loess Plateau ◽  
Human Activities ◽  
Yellow River ◽  
The Yellow River ◽  
The Loess Plateau ◽  
Water And Sediment ◽  
Poc Flux ◽  
Reservoir Construction ◽  
Carbon Transport

Abstract. Based on four field investigations during 2003 and 2009 along the Yellow River mainstream, we examined the distributions, seasonal variations and transport features of organic carbon, with a focus on the impacts of human activities (reservoir construction and regulation scheme). The results showed that organic carbon transport processes in the Yellow River were different from other major rivers. Particulate organic carbon (POC) dominated in the Yellow River and it mainly originated from the Loess Plateau. POC levels in suspended sediment (POC %) ranged between 0.25% and 2.20% and more than 80% of POC concentrated in the particles with grain size smaller than 16 μm. On time scale, dissolved organic carbon (DOC) correlated negatively with discharges, indicating the influence of dilution effect. Along the river on spatial scales, DOC in the Qinghai-Tibet Plateau was closely related with temperature while DOC in the Loess Plateau showed the concentration effect, due to the abundant human input and the high ratio of evaporation to precipitation. Organic carbon in the Yellow River was very refractory and about 90% of POC and 70% of DOC cannot be degraded. Due to the high turbidity, the Yellow River suffers more impacts from the reservoirs in the transport of total suspended solids (TSS) and organic carbon. Ratios of DOC/POC ranged between 2.0 and 12 in the reservoirs and organic carbon was mainly in the dissolved from. POC deposited in the reservoirs of the Yellow River achieved 0.0033 Gt a−1, about 8 times its annual POC flux discharged to the ocean. During the 2008 Water and Sediment Regulation (WSR) period, DOC and POC fluxes was as high as 1.1 × 1010 g and 2.2 × 1011 g respectively, accounting for 35% of annual DOC flux and 56% of the annual POC flux to the ocean. Discharges and material fluxes to the ocean decline sharply due to the reservoir construction while large amounts of water and sediment are transported to the ocean in such a~short WSR period. These two human disturbances totally altered the processes of substance transport in the Yellow River, and may change the water chemical characteristics in the coastal zones.

scholarly journals Effects of Wetland Restoration and Conservation Projects on Soil Carbon Sequestration in the Ningxia Basin of the Yellow River in China from 2000 to 2015

2020 ◽  
Vol 12 (24) ◽  
pp. 10284
Author(s):  
Xiaoyan Bu ◽  
Dan Cui ◽  
Suocheng Dong ◽  
Wenbao Mi ◽  
Yu Li ◽  
...  
Keyword(s):  
Carbon Sequestration ◽  
Soil Carbon ◽  
Wetland Restoration ◽  
Yellow River ◽  
C Sequestration ◽  
Soil Carbon Sequestration ◽  
The Yellow River ◽  
Wetland Soil ◽  
Landsat 8 ◽  
Conservation Projects

The long-term use of wetlands stresses wetland ecosystems and leads to degradation and C loss. This study explored an optimal remote sensing-multivariate linear regression model (RS-MLRM) for estimating wetland soil organic carbon (SOC) by using a combination of the measured SOC and above ground biomass (AGB) from 273 samples, textural features, spectral information, and a vegetation index calculated from Landsat-8 images using the Ningxia Basin of the Yellow River as the study area. To derive the optimal predictor model for SOC, these variables were regressed against the measured SOC. These were used to predict SOC and evaluate the contribution of wetland restoration and conservation projects to soil carbon sequestration and sinks on the Ningxia Basin of the Yellow River in early (2000 and 2005), intermediate (2010), and recent (2015) years. The results show that from 2000 to 2015, the project-induced contribution to C sequestration was 20.49 TC, with an annual sink of 1.37 TC. This accounted for 54.06% of the total wetland ecosystem C sequestration on the Ningxia Basin of the Yellow River. Moreover, there was a significant success of restoration and conservation projects regarding C sequestration. These restoration and conservation projects have substantially contributed to CO2 mitigation in the arid area.

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