黄河三角洲湿地土壤盐离子沿水盐梯度的变化特征

为了分析黄河三角洲滨海湿地土壤电导率及盐离子组成沿水盐梯度的分布规律,沿自黄河向海的方向选择了假尾拂子茅湿地、香蒲湿地、芦苇湿地、柽柳和盐地碱蓬混生湿地和盐地碱蓬湿地作为研究样地,于2014年在各类型湿地内采集0～50 cm的土壤,并测定土壤电导率和6种盐离子。结果表明,盐地碱蓬湿地0～50 cm土壤的电导率、钠离子、钾离子和氯离子显著高于其他湿地(P0.05),镁离子、钙离子和硫酸根离子的最高值则出现在柽柳和盐地碱蓬混生湿地。在剖面方向上,电导率和6种盐离子表现出不同的变化趋势。线性相关分析表明,土壤电导率和6种盐离子呈显著正相关关系(P0.05)。土壤电导率和盐离子在2014年均表现出强变异特征。研究表明,沿自河向海的水盐梯度,湿地土壤电导率、钠离子、钾离子、镁离子、钙离子、氯离子和硫酸根离子总体呈现逐渐上升的趋势,土壤电导率的变化主要受钠离子和氯离子含量变化的影响。

Variations in soil salt ions along a water and salinity gradient in the Yellow River Delta, China

Soil samples were collected to a depth of 50 cm in the Yellow River Delta Nature Reserve, including Calamagrostis pseudophragmites wetlands (S1), Typha orientalis wetlands (S2), Phragmites australis wetlands (S3), Tamarix chinensis and Suaeda salsa wetlands (S4) and Suaeda salsa wetlands (S5), along a gradient of water and salinity in four seasons of 2014. Soil electrical conductivity (EC) and the concentrations of six salt ions (Na⁺, K⁺, Ca²⁺, Mg²⁺, Cl^- and SO₄^2-) were analyzed to investigate the effects of water and salinity gradient on soil salinity. The results showed that soil EC, Na⁺, K⁺, and Cl^- in Suaeda salsa wetlands were significantly higher than those in the other wetlands (P<0.05), while the highest value of Mg²⁺, Ca²⁺, and SO₄^2- occurred in Tamarix chinensis and Suaeda salsa wetland soils. Along the 0~50 cm soil profile, soil EC and salt ions showed different trends. Soil EC was linearly and significantly positively correlated with six salt ions (P<0.05). Furthermore, strong variability was observed in soil EC and salt ions in five wetlands. Our results indicated that soil EC and six salt ions increased along the water and salinity gradient from the Yellow River to the sea, and soil EC was mainly affected by the changes of Na⁺ and Cl^-.