title: Unraveling the size distributions of surface properties for purple soil and yellow soil.
abstract: Soils contain diverse colloidal particles whose properties are pertinent to ecological and human health, whereas few investigations systematically analyze the surface properties of these particles. The objective of this study was to elucidate the surface properties of particles within targeted size ranges (i.e. >10, 1-10, 0.5-1, 0.2-0.5 and <0.2 μm) for a purple soil (Entisol) and a yellow soil (Ultisol) using the combined determination method. The mineralogy of corresponding particle-size fractions was determined by X-ray diffraction. We found that up to 80% of the specific surface area and 85% of the surface charge of the entire soil came from colloidal-sized particles (<1 μm), and almost half of the specific surface area and surface charge came from the smallest particles (<0.2 μm). Vermiculite, illite, montmorillonite and mica dominated in the colloidal-sized particles, of which the smallest particles had the highest proportion of vermiculite and montmorillonite. For a given size fraction, the purple soil had a larger specific surface area, stronger electrostatic field, and higher surface charge than the yellow soil due to differences in mineralogy. Likewise, the differences in surface properties among the various particle-size fractions can also be ascribed to mineralogy. Our results indicated that soil surface properties were essentially determined by the colloidal-sized particles, and the <0.2 μm nanoparticles made the largest contribution to soil properties. The composition of clay minerals within the diverse particle-size fractions could fully explain the size distributions of surface properties.
authors.affiliation: Chongqing Key Laboratory of Soil Multi-Scale Interfacial Process, College of Resources and Environment, Southwest University, Chongqing 400715, China; Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China. Electronic address: ty881012@163.com.
authors.forename: Ying
authors.initials: Y
authors.lastname: Tang
authors.affiliation: Chongqing Key Laboratory of Soil Multi-Scale Interfacial Process, College of Resources and Environment, Southwest University, Chongqing 400715, China. Electronic address: lihangswu@163.com.
authors.forename: Hang
authors.initials: H
authors.lastname: Li
authors.affiliation: Chongqing Key Laboratory of Soil Multi-Scale Interfacial Process, College of Resources and Environment, Southwest University, Chongqing 400715, China.
authors.forename: Xinmin
authors.initials: X
authors.lastname: Liu
authors.affiliation: Chongqing Key Laboratory of Soil Multi-Scale Interfacial Process, College of Resources and Environment, Southwest University, Chongqing 400715, China.
authors.forename: Hualing
authors.initials: H
authors.lastname: Zhu
authors.affiliation: Chongqing Key Laboratory of Soil Multi-Scale Interfacial Process, College of Resources and Environment, Southwest University, Chongqing 400715, China.
authors.forename: Rui
authors.initials: R
authors.lastname: Tian
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry*; D001546:Bentonite / Q000737:chemistry*; D003102:Colloids / Q000737:chemistry; D004784:Environmental Monitoring / Q000379:methods*; D010316:Particle Size; D012987:Soil / Q000737:chemistry*; D055672:Static Electricity; D013499:Surface Properties; D014961:X-Ray Diffraction
chemical_list: D000538:Aluminum Silicates; D003102:Colloids; D012987:Soil; D001546:Bentonite; C003760:vermiculite; C011934:mica
keywords: Clay minerals; Particle size distribution; Soil colloids; Specific surface area; Surface charge number