上海临港园林绿化吹填土盐基离子分布特征

Distribution Characteristics of Salt Ions in Dredger Fill of Shanghai Lingang Landscape Greening Soil

选取上海临港地区滴水湖东侧人为干扰较少的吹填土为研究对象,对吹填土剖面中8种主要的盐基离子含量及其分布特征进行了调查和分析。结果表明:临港地区吹填土的盐基离子以Cl^(-)、Na^(+)和SO_(4)^(2-)为主,盐基离子分布具有较大的变异性,其中CO_(3)^(2-)和Cl^(-)属于强变异,其余离子均为中等变异。吹填土盐渍化类型为氯化物型,Cl^(-)/SO_(4)^(2-)当量浓度比在2.6~98.1之间。在不同深度土层中,盐基离子总量无显著差异。土壤全盐量与Cl^(-)、K^(+)、Na^(+)含量呈显著正相关,土壤pH值与CO_(3)^(2-)和HCO_(3)^(-)呈显著正相关、与Ca^(2+)呈显著负相关,吹填土盐基离子主要来源于氯化物和硫酸盐。主成分分析表明:各点位盐碱化的主要胁迫因子并不完全一致,有些点位以中性盐基离子Cl^(-)、K^(+)、Na^(+)的盐渍化胁迫为主,有些点位以碱性盐基离子CO_(3)^(2-)和HCO_(3)^(-)的碱化胁迫为主。上海临港地区吹填土盐基离子以Cl^(-)和Na^(+)为主,属于氯化物型盐渍土,呈典型滨海岸带盐渍土特征。全盐量在剖面上呈均匀分布,Cl^(-)和Na^(+)决定了吹填土的含盐量,CO_(3)^(2-)和HCO_(3)^(-)决定了吹填土的碱度。不同点位在土壤全盐量过高和碱化上胁迫程度不一,在进行吹填土改良时可分别采取脱盐和降pH值的改良措施,进行精准调控。

The dredger fill in the east of Dishui Lake in Shanghai Lingang area was selected as the research object,and the content and distribution characteristics of eight salt ions of the dredger fill profile were investigated and analyzed.The results showed that Cl^(-),Na^(+)and SO_(4)^(2-)were the main ones,and the salt ion distribution was quite variable,among which CO_(3)^(2-)and Cl^(-)were strong variation,and the other ions were moderate variation.The salinization type of dredger fill was the chloride type,with the Cl^(-)/SO_(4)^(2-)equivalent concentration ratio ranging between 2.6 and 98.1.There was no significant difference in the total amount of salt ions in the different deep soil layers.The total soil salt content was significantly and positively correlated with Cl^(-),K^(+)and Na^(+)content,while the soil pH was significantly and positively correlated with CO_(3)^(2-)and HCO_(3)^(-),negatively correlated with Ca^(2+).The dredger fill salt ions were mainly derived from chloride and sulfate.Principal component analysis showed that the main stress factors of salinization were not completely consistent,and some were mainly affected by Cl^(-),K^(+)and Na^(+),while some were mainly affected by CO_(3)^(2-)and HCO_(3)^(-).The dredger fill salt ions in Shanghai Lingang area are mainly Cl^(-)and Na^(+),which belong to the chloride type saline soil and are typical of the coastal saline soil.Total salt was evenly distributed on the profile.Cl^(-)and Na^(+)determine the salt content of the dredger fill,and CO_(3)^(2-)and HCO_(3)^(-)determine the alkalinity of the dredger fill.Different places have different barriers to soil salinization.The improvement measures of desalination and pH reduction can be adopted respectively to conduct precise regulation.