Country School of Civil and Hydraulic Engineering, Ningxia University, Yinchuan, 750021, China.
Engineering Research Center of Efficient Utilization of Modern Agricultural Water Resources in Arid Regions, Ministry of Education, Yinchuan, 750021, China.
Sci Rep. 2023 Jan 25;13(1):1421. doi: 10.1038/s41598-023-27888-7.
The material basis for soil formation is rock weathering debris. Understanding the particle size composition characteristics of rock weathering debris and its impacts is important for improving the soil structure of dry farmland in the central dry zone of Ningxia,China. In this study, the particle sizes of weathered debris collected from grey-green slate after indoor simulations of freeze-thaw and dry-wet cycles tests were examined. The results were as follows: (1) Under 16 treatments, the weathering debris of grey-green slate contained about 10% or less very fine sand and coarse silt, while clay, fine silt, and fine sand were the most abundant sizes (at least 60% of the total). (2) Under each treatment, the average particle size of the grey-green slate weathered debris was 5.52Ф (silt grade). The overall skewness was high, but the symmetry was poor. The particle size frequency distribution curve had many broad peaks or multiple peaks. (3) The fractal dimension was associated with very fine silt but had a strong negative correlation with fine sand and medium-coarse sand. The results indicate that fractal dimension can reflect the grain size characteristics of weathered debris. The mineral element content of the grey-green slate somewhat affected the fractal dimension, and it positively correlated with environmental electrical conductivity (EC) and element-leaching amount; it negatively correlated with particle size, temperature, and pH. According to the findings, the fractal dimension can accurately represent the particle size distribution of weathered debris. The generation of grey-green slate weathering debris should be considered in the formation and development of local soil.
土壤形成的物质基础是岩石风化碎屑。了解岩石风化碎屑的粒径组成特征及其影响，对改善中国宁夏中部干旱区旱地土壤结构具有重要意义。本研究对室内冻融-干湿循环模拟试验后采集的灰绿色板岩风化碎屑的粒径进行了分析。结果表明：（1）在 16 种处理条件下，灰绿色板岩风化碎屑中粒径小于 0.075mm 的极细砂和粗粉砂含量均在 10%左右，而粒径为 0.002~0.05mm 的粘土、细粉砂和细砂含量最丰富（至少占总量的 60%）。（2）在每种处理条件下，灰绿色板岩风化碎屑的平均粒径均为 5.52Ф（粉粒级），偏度较高，峰态较差，粒径频率分布曲线多呈宽峰或多峰型。（3）分形维数与极细粉砂呈正相关，与细砂和中粗砂呈负相关。分形维数与矿物元素含量有关，与环境电导率（EC）和元素溶出量呈正相关，与粒径、温度和 pH 值呈负相关。分形维数可以准确地反映风化碎屑的粒径分布，能较好地反映灰绿色板岩风化碎屑的粒径特征。在局部土壤的形成和发育过程中，应考虑灰绿色板岩风化碎屑的产生。
