Assessment of multiple and interacting modes of soil loss in the karst critical zone, Southwest China (SWC)

Geomorphology ◽  
2018 ◽  
Vol 322 ◽  
pp. 97-106 ◽  
Author(s):  
Faming Zeng ◽  
Zhongcheng Jiang ◽  
Lina Shen ◽  
Wei Chen ◽  
Qiyong Yang ◽  
...  
Keyword(s):  
Soil Loss ◽  
Southwest China ◽  
Critical Zone

Tracer vertical movement and its affecting factors in karst soil profiles using the simulated leaching method

2021 ◽  
Author(s):  
Jianghu He ◽  
Keli Zhang ◽  
Zihao Cao ◽  
Qihua Ke
Keyword(s):  
Soil Erosion ◽  
Soil Loss ◽  
Southwest China ◽  
Vertical Movement ◽  
Karst Area ◽  
Affecting Factors ◽  
Tracer Movement ◽  
Traditional Research ◽  
Movement Distance ◽  
Karst Geomorphology

<p>Soil erosion is a severe issue in Southwest China due to complex karst geomorphology and excessive farming activities. It is also difficult to observe and evaluate using traditional research methods. Fortunately, as a supplement to traditional methods, the <sup>137</sup>Cs tracing technique has strong potential to monitor and evaluate soil loss in karst regions. However, <sup>137</sup>Cs might move downward with tiny particles under adequate rainfall conditions. This is critical because it directly affects accuracy of using the <sup>137</sup>Cs conversion model to evaluate soil erosion. Thus, in our study, in order to explore whether tracers actually moved vertically and to evaluate the movement distance and the factors influencing the movement, magnetic powder (Fe<sub>3</sub>O<sub>4</sub>) and rare earth oxides (CeO<sub>2 </sub>and La<sub>2</sub>O<sub>3</sub>) were used as the substitute tracers under different conditions (rainfall and leaching area) of a simulated leaching experiment, which possess similar properties as <sup>137</sup>Cs and have no toxicity problems in humans and the environment. The results showed that tracers moved downward 6 cm when water was added to simulate 1-10-year rainfall conditions and 8 cm when water was added to simulate 15-20-year rainfall conditions. The movement distance of tracers increased slowly with increasing water input, and the concentration of the tracers that moved related indirectly to the leaching area. Tracer movement at the edge of the simulated profile was affected by tracer type and concentration since there was no transition layer between soil and plastic column. Our field observations in two karst watersheds showed that ignoring the vertical movement of tracer can cause the overestimation of soil loss amount by 6.90% and 22.22% respectively. This study proved that in the karst area of Southwest China with abundant rainfall, <sup>137</sup>Cs would move vertically, and the soil loss will be overestimated if the vertical movement distance of the tracer is ignored.</p>

scholarly journals Soil organic carbon sequestration in soil aggregates in the karst Critical Zone Observatory, Southwest China

2019 ◽  
Vol 65 (No. 5) ◽  
pp. 253-259 ◽  
Author(s):  
Man Liu ◽  
Guilin Han ◽  
Zichuan Li ◽  
Qian Zhang ◽  
Zhaoliang Song
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Southwest China ◽  
Critical Zone ◽  
Soil Aggregation ◽  
Research Station ◽  
Land Uses ◽  
Farmland Abandonment ◽  
Critical Zone Observatory ◽  
Farmland Soils

Soil organic carbon (SOC) sequestration in aggregates under land use change have been widely concerned due to intimate impacts on the sink (or source) of atmospheric carbon dioxide (CO<sub>2</sub>). However, the quantitative relationship between soil aggregation and SOC sequestration under land uses change has been poorly studied. Distribution of aggregates, SOC contents in bulk soils and different size aggregates and their contributions to SOC sequestration were determined under different land uses in the Puding Karst Ecosystem Observation and Research Station, karst Critical Zone Observatory (CZO), Southwest China. Soil aggregation and SOC sequestration increased in the processes of farmland abandonment and recovery. SOC contents in micro-aggregates were larger than those in macro-aggregates in restored land soils, while the opposite results in farmland soils were obtained, probably due to the hindrance of the C-enriched SOC transport from macro-aggregate into micro-aggregate by the disturbance of agricultural activities. SOC contents in macro-aggregates exponentially increased with their proportions along successional land uses. Macro-aggregates accounted for over 80% on the SOC sequestration in restored land soils, while they accounted for 31–60% in farmland soils. These results indicated that macro-aggregates have a great potential for SOC sequestration in karst soils.

scholarly journals Variations and Indications of δ13CSOC and δ15NSON in Soil Profiles in Karst Critical Zone Observatory (CZO), Southwest China

2019 ◽  
Vol 11 (7) ◽  
pp. 2144 ◽  
Author(s):  
Man Liu ◽  
Guilin Han ◽  
Qian Zhang ◽  
Zhaoliang Song
Keyword(s):  
Southwest China ◽  
Crop Productivity ◽  
Critical Zone ◽  
Soil Profiles ◽  
Agricultural Lands ◽  
Farmland Abandonment ◽  
Surface Soils ◽  
Soil Layers ◽  
Critical Zone Observatory ◽  
Karst Soils

Soil carbon and nitrogen storage and stabilization are the key to solving the problems of mitigation of global warming and maintaining of crop productivity. In this study, the contents of soil organic carbon (SOC) and soil organic nitrogen (SON) and their stable isotope compositions (δ13CSOC and δ15NSON) in soil profiles were determined in two agricultural lands (including a farmland and an abandoned farmland) and four non-agricultural lands (including two shrub-grass lands and two shrub lands) in the karst critical zone observatory (CZO), Southwest China. The contents of SOC and SON were used for research on the effects of land use on SOC and SON storage, and the change of δ13CSOC and δ15NSON values in soil profiles were used to indicate SOC and SON stabilization. The results showed that agricultural activities reduced SOC and SON storage in the whole soil layers of farmland compared to non-agricultural lands, and farmland abandonment slightly increased SOC and SON storage. Crop rotation between peanut (C3) and corn (C4) affected the δ13CSOC in surface soils of agricultural lands (−21.6‰), which were intermediate between shrub lands (−22.7‰) and shrub-grass lands (−19.6‰). 15N-depleted SON in surface soils in farmland compared to those soil in other lands possibly associated with synthetic N fertilizer application. In soil layers below 30 cm depth the δ13CSOC deceased with depth, while the δ15NSON displayed irregular fluctuation. The change in δ13CSOC and δ15NSON through soil profiles in karst soils were more intensive than those in semiarid grassland soils indicating the less stabilization of SOC and SON in karst soils.

Main controls on the denitrification rates during cropland revegetation in the southwest China Karst Critical Zone Observatory

2021 ◽  
Vol 308 ◽  
pp. 107228
Author(s):  
Dandan Li ◽  
Xinyu Zhang ◽  
Jennifer A.J. Dungait ◽  
Sophie M. Green ◽  
Xuefa Wen ◽  
...  
Keyword(s):  
Southwest China ◽  
Critical Zone ◽  
Critical Zone Observatory

scholarly journals Geochemical Characteristics of Rare Earth Elements in Soils from Puding Karst Critical Zone Observatory, Southwest China

2019 ◽  
Vol 11 (18) ◽  
pp. 4963 ◽  
Author(s):  
Qian Zhang ◽  
Guilin Han ◽  
Man Liu ◽  
Lingqing Wang
Keyword(s):  
Rare Earth ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Rare Earth Elements ◽  
Southwest China ◽  
Clay Content ◽  
Critical Zone ◽  
Fe Content ◽  
Local Soil ◽  
Critical Zone Observatory

Soil samples from eight soil profiles under different land-use types were collected at the Puding Karst Critical Zone Observatory, Southwest China, to investigate the distribution, fractionation, and controlling factors of rare earth elements (REEs). The total REEs contents in topsoil ranged from 149.97 to 247.74 mg kg−1, the contents in most topsoil were higher than local soil background value (202.60 mg kg−1), and the highest content was observed in topsoil under cropland. The REEs contents in surface soils from lower slopes sites were higher than that of middle and upper slope sites, and the highest contents were observed in cropland. The PAAS-normalized REEs pattern in soils showed MREEs significantly enriched relative to LREEs and HREEs, and HREEs were enriched relative to LREEs. The results showed that clay content, pH, soil organic carbon, total phosphorus, and Fe content were the main factors influencing the distribution of REEs in karst soils, and soil organic carbon (SOC), Fe content showed better linear relationship with REEs.

Determination of Soil Loss Tolerance of an Entisol in Southwest China

2009 ◽  
Vol 73 (2) ◽  
pp. 412-417 ◽  
Author(s):  
Gangcai Liu ◽  
Lan Li ◽  
Laosheng Wu ◽  
Genxu Wang ◽  
Zhonghao Zhou ◽  
...  
Keyword(s):  
Soil Loss ◽  
Southwest China ◽  
Soil Loss Tolerance ◽  
Loss Tolerance

Soil enzyme activity and stoichiometry along a gradient of vegetation restoration at the Karst Critical Zone Observatory in Southwest China

2019 ◽  
Vol 30 (16) ◽  
pp. 1916-1927 ◽  
Author(s):  
Zhiming Guo ◽  
Xinyu Zhang ◽  
Sophie M. Green ◽  
Jennifer A.J. Dungait ◽  
Xuefa Wen ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Southwest China ◽  
Soil Enzyme ◽  
Critical Zone ◽  
Vegetation Restoration ◽  
Soil Enzyme Activity ◽  
Critical Zone Observatory

scholarly journals Hydrogeochemical Dynamics and Response of Karst Catchment to Rainstorms in a Critical Zone Observatory (CZO), Southwest China

2020 ◽  
Vol 2 ◽  
Author(s):  
Caiqing Qin ◽  
Hu Ding ◽  
Si-Liang Li ◽  
Fu-Jun Yue ◽  
Zhong-Jun Wang ◽  
...  
Keyword(s):  
Surface Water ◽  
Southwest China ◽  
Critical Zone ◽  
Karst Water ◽  
Agricultural Activities ◽  
Carbonate Weathering ◽  
Hydrogeological Conditions ◽  
Surface Water And Groundwater ◽  
Critical Zone Observatory ◽  
Karst Catchment

Karst water is vital for local drinking and irrigation but is susceptible to contamination. Hydrochemistry, which is highly related to carbonate weathering in karst catchments, can affect water quality and respond rapidly to climate change. In order to explore hydrogeochemical sources, dynamics, and their responses to rainstorms, rainwater, throughfall, hillslope runoff, surface water, and groundwater were sampled synchronously during rainstorms at a karst Critical Zone Observatory (CZO), Southwest China. Results showed that the total dissolved solids (TDS) concentration in throughfall increased by 30.1 ± 8.0% relative to rainwater, but both throughfall and rainwater contributed little to TDS in surface water and groundwater compared with terrestrial sources. Hydrochemistry in surface water and groundwater was diluted by rainstorms but displayed chemostatic responses with different intensities to increasing discharge. This is possibly regulated by hydrogeological conditions, available sources of various solutes, and the difference between solute concentrations before and after rainstorms. Ca2+ and Mg2+ dynamics were mainly regulated by carbonate weathering, gypsum dissolution, and gypsum-induced dedolomitization (geological sources), which also affect Ca2+, Mg2+, and SO42- in deep confined groundwater draining a gypsum stratum. For HCO3-, CO2 from respiration and microbiologic activities is one dominant contributor, especially for spring. The chemostatic behaviors of NO3-, Cl−, and K+ were related to agricultural activities, especially in surface water. These controls on hydrochemistry may already exist as hillslope runoff occurs, which has be further demonstrated by principle component analysis (PCA). The heterogeneous permeability of epikarst can affect the mixture of groundwater from different sources and flowing pathways, enabling hydrochemistry at different hydrogeological conditions to display discrepant responses to rainstorms. The epikarst aquifer with high permeability is susceptible to changes in external environment, such as rainstorms and agricultural activities, increasing the potential risk of water environment problems (chronic pollution of nitrogen and high hardness of water) during a certain period. Drinking water safety thus deserves consideration in the agricultural karst catchment.

Sediment sources, soil loss rates and sediment yields in a Karst plateau catchment in Southwest China

2020 ◽  
Vol 304 ◽  
pp. 107114
Author(s):  
Qianyun Cheng ◽  
Shijie Wang ◽  
Tao Peng ◽  
Le Cao ◽  
Xinbao Zhang ◽  
...  
Keyword(s):  
Soil Loss ◽  
Southwest China ◽  
Sediment Sources ◽  
Sediment Yields ◽  
Loss Rates
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