ABSTRACT
Studying the spatial distribution pattern of soil organic carbon and its influencing factors is essential for understanding the carbon cycle in terrestrial ecosystems. Soil samples from four active layers of typical vegetation types (Populus, subalpine shrubs, Picea crassifolia Kom, and alpine meadow) in the upper reaches of Shiyang River basin in the Qilian Mountains were collected to determine the soil organic carbon content and physicochemical properties. The results show the following: (1) There are significant differences in the vertical distribution of Soil organic carbon in the watershed, and the Soil organic carbon content decreases significantly with increasing soil depth. (2) Mainly affected by biomass, the organic carbon content of different vegetation types in different soil layers is as follows: Alpine meadow > Picea crassifolia Kom > Populus > Subalpine shrub, and the soil organic carbon content increases with increasing altitude. Under different vegetation types, the Soil organic content is the highest in the 0-30 cm soil profile, and the maximum value often appears in the 0-10 cm layer, then gradually decreases downward. (3) When soil organic carbon is determined in different vegetation types in the study area, the change of hydrothermal factors has little effect on soil organic carbon content in the short term.
ABSTRACT
Inland rivers play a key role in supplying water for domestic and agricultural purposes in Asian arid inland basin. This paper investigates the chemical composition of precipitation, river water, and groundwater, providing evidence for the influencing factors the water composition in the Shiyang River Basin. Water samples were collected and analyzed to determine the content of major cations (Ca2+, Mg2+, Na+, K+, and NH+ 4) and anions (HCO- 3, Cl-, NO- 3, NO- 2, F-, and SO2-4), total solid solubility, and pH values. The results showed that precipitation, surface water, and groundwater were mildly alkaline. Ca2+ and SO2-4 were the predominant ions. The content of inorganic ions varied largely in the different seasons, with the highest ion concentration observed in spring and the lowest in summer. The seasonal variations in groundwater were less considerable than those in surface water. Furthermore, anion concentrations increased substantially from upstream to downstream. Regional weathering of carbonates and evaporation were established as the major sources of these ions. In addition, we discovered that anthropogenic inputs had led to light pollution of water in some residential districts.
