关键词: 名茶, 高山, 生态气候, 黄河三角洲, 土壤盐渍化, 空间变异, 地形地貌, 氯离子, 地下水

Abstract:

To understand the main controlling factors of the soil salinity in the Huanghe River Delta, multi-layer soil samples, phreatic water samples and typical vadose column were collected in this study. Spatial distributions of the content of Cl^- were analyzed by using traditional statistics and geostatistical method. Results show that: 1) ranges of the content of Cl^- at the soil depths of 0-20 cm, 30-50 cm and 50-100 cm were 0.08-35.23, 0.04-15.22 and 0.07-11.67 g/kg, respectively. Random variations at these three soil depths were 50.0%, 24.0% and 60.4% respectively. The content of Cl^- at 30-50 cm depth was mainly affected by structural factors or non-human factors (e.g., vegetation, climate and topography). The content of Cl^- at other soil depths was influenced by both random factors (e.g., management practices) and structural factors. The spatial pattern of the content of Cl^- at each soil depth showed a substantial plaque-strip-plaque shape, which indicates the continuity and direction to some extent. It is also noted that the content of Cl^- in soils positively correlated with that in phreatic water. 2) the groundwater level (0.50-2.50 m) was relatively shallow in the study area, while the groundwater level was generally less than 1.0 m in the coastal inshore. Due to the fact that the embedded depth of the groundwater did not change much, the spatial variation of groundwater level was significantly weaker than that of the content of Cl^- in phreatic water. In that case, with respect to the key factor of the content of Clin phreatic water, difference of soil salinity caused by embedded depth of groundwater can be ignored to some extent. Under the condition of little changes in groundwater depth, similar the lithology and structure of the vadose zone, and roughly similar phreatic aquifer permeability, water in the phreatic zone was easy to transport to the vadose zone due to the plant transpiration and the water potential gradient in the unsaturated zone. Therefore, the pattern of the content of Cl^- in phreatic water driven was similar to that of Cl^- in soils; and 3) the average value of the content of Cl^- in surface soils was smallest for the higher fluvial highlands (0.09) and flood land highlands (0.26 g/kg). However, the average value of the content of Cl^- in surface soils was as high as 4.34 g/kg for coastal lowland. Through the redistribution of water, gas and heat, Topography controlled the direction of the migration of Cl^- in the unsaturated zone and enrichment region. As a result, the content of Cl^- in soils varied with the topography. Hydro-geology condition was the internal factor that determines salt migration and enrichment between the groundwater and the vadose zone. In addition, topography was the external factor that plays a key role of controlling in the Huanghe River Delta.

Key words: The famous tea growing, High mountains, Ecologic climate, chloride ion, groundwater, topography and geomorphology, the Huanghe River Delta, soil salinity, spatial variability