Soil organic nitrogen variation shaped by diverse agroecosystems in a typical karst area: evidence from isotopic geochemistry.

Background: Soil organic nitrogen (SON) levels can respond effectively to crop metabolism and are directly related to soil productivity. However, simultaneous comparisons of SON dynamics using isotopic tracing in diverse agroecosystems are lacking, especially in karst areas with fragile ecology.

Methods: To better understand the response of SON dynamics to environmental changes under the coupling of natural and anthropogenic disturbances, SON contents and their stable N isotope (δN) compositions were determined in abandoned cropland (AC, = 16), grazing shrubland (GS, = 11), and secondary forest land (SF, = 20) from a typical karst area in southwest China.

Responses of soil organic carbon cycle to land degradation by isotopically tracing in a typical karst area, southwest China.

Background: The loss of soil organic carbon (SOC) under land degradation threatens crop production and reduces soil fertility and stability, which is more reflected in eco-sensitive environments. However, fewer studies simultaneously compared SOC variations and C compositions under diverse land uses, especially in karst areas.

Methods: Soil profiles from two agricultural lands and a secondary forest land were selected to analyze SOC contents and their stable isotope composition (C) in a typical karst area located in southwest China to understand the response of the SOC cycle to land degradation.

Hydrogeochemical characteristics and recharge sources identification based on isotopic tracing of alpine rivers in the Tibetan Plateau.

Alpine rivers originating from the Tibetan Plateau (TP) contain large amounts of water resources with high environmental sensitivity and eco-fragility. To clarify the variability and controlling factors of hydrochemistry on the headwater of the Yarlung Tsangpo River (YTR), the large river basin with the highest altitude in the world, water samples from the Chaiqu watershed were collected in 2018, and major ions, δH and δO of river water were analyzed. The values of δH (mean: -141.

Tracing Fe cycle isotopically in soils based on different land uses: Insight from a typical karst catchment, Southwest China.

Iron (Fe) isotopes can effectively unveil the Fe cycle mechanisms under redox and biological conditions during the weathering and pedogenic processes. Fe contents and Fe isotope compositions (defined as δFe) in the soil profiles under secondary forest land, abandoned cropland and shrubland were investigated in a typical karst area in Southwest China. The results showed that the Fe content ranged from 23.

Spatial distribution and ecological risk assessment of heavy metals in karst soils from the Yinjiang County, Southwest China.

Background: Soil heavy metals (HMs) under different land-use types have diverse effects, which may trigger the ecological risk. To explore the potential sources of HMs in karst soils, the spatial distribution and geochemical behavior of HMs based on different land-use types are employed in this study.

Methods: Soil samples ( = 47) were collected in three suites of karst soil profiles from the secondary forest, abandoned cropland and shrubland in Yinjiang, Southwest China.

Geochemical Behaviors of Rare Earth Elements (REEs) in Karst Soils under Different Land-Use Types: A Case in Yinjiang Karst Catchment, Southwest China.

The geochemical characteristics of rare earth elements (REEs) can be employed to identify the anthropogenic and natural influence on the distributions of REEs in soils. A total of 47 soil samples from the three soil profiles of the secondary forest land, abandoned cropland, and shrubland in the Yinjiang county of Guizhou province, southwest China, were collected to determine the contents and distribution of REEs in the soil environment. The total REEs (ΣREE) contents in different soil profiles are in the following sequence: secondary forest land (mean: 204.