Liu Man, Han Guilin, Zhang Qian
Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, China.
Institute of Earth Sciences, China University of Geosciences (Beijing), Beijing, China.
PeerJ. 2025 Sep 2;13:e19982. doi: 10.7717/peerj.19982. eCollection 2025.
Copper (Cu), a toxic trace element, has extensively accumulated in soils due to intensive human activities. Yet current knowledge on Cu sources and biogeochemical processes in Cambisols under varying land uses is scant. In this study, Cu contents, stable isotope compositions (δCu) and their correlations with soil physicochemical properties in soil profiles across different land uses were analyzed, including cropland, abandoned cropland and orchard, shrub-grass land, and secondary forest in a karst watershed of Southwest China. Soil Cu contents in cropland (mean 44.9 mg kg ) were significantly higher than those in abandoned cropland and orchard (mean 37.7 mg kg ), and much higher than those in natural lands (mean 26.3 mg kg ). In agricultural lands, cropland soils (mean -0.216‰) were significantly Cu-depleted compared to abandoned cropland and orchard (0.020‰), resulting from applying Cu-depleted fungicides. Soil δCu values in shrub-grass land and secondary forest land exhibited within a wide range, from -0.627‰ to 0.338‰, attributed to Cu isotope fractionations during pedogenic processes. Soil δCu values decreased with increasing soil depth and were positively correlated with soil organic carbon (SOC) contents, but negatively correlated with the chemical index of alteration (CIA), indicating the influences of clay mineral sorption, organic complexation, and leaching processes on soil δCu patterns. In different regions, δCu values in Cambisols increased in sub-humid climate, but decreased in humid climate with increasing annual precipitation. This study underscores the key roles of mineral sorption, organic complexation, and leaching processes in affecting δCu patterns in Cambisols.
铜（Cu）作为一种有毒微量元素，由于人类活动频繁，已在土壤中大量累积。然而，目前对于不同土地利用方式下 Cambisols 土壤中铜的来源及生物地球化学过程的了解还很匮乏。本研究分析了中国西南喀斯特流域不同土地利用类型（包括农田、弃耕地、果园、灌草地和次生林）土壤剖面中的铜含量、稳定同位素组成（δCu）及其与土壤理化性质的相关性。农田土壤铜含量（平均 44.9 mg/kg）显著高于弃耕地和果园（平均 37.7 mg/kg），且远高于自然土地（平均 26.3 mg/kg）。在农业用地中，农田土壤（平均 -0.216‰）与弃耕地和果园（0.020‰）相比，明显贫铜，这是由于施用了贫铜杀菌剂所致。灌草地和次生林土壤的 δCu 值变化范围较广，为 -0.627‰至 0.338‰，这归因于成土过程中的铜同位素分馏作用。土壤 δCu 值随土壤深度增加而降低，与土壤有机碳（SOC）含量呈正相关，但与化学蚀变指数（CIA）呈负相关，表明黏土矿物吸附、有机络合和淋溶过程对土壤 δCu 模式有影响。在不同区域，随着年降水量增加，Cambisols 土壤的 δCu 值在半湿润气候区升高，但在湿润气候区降低。本研究强调了矿物吸附、有机络合和淋溶过程在影响 Cambisols 土壤 δCu 模式中的关键作用。
