以西宁盆地北山地区小西沟流域为研究区,以区内硫酸盐渍土为研究对象,通过筛分试验得到了6组不同粒径(<0.075 mm、0.075~0.1 mm、0.1~0.25 mm、0.25~0.5 mm、0.5~1 mm、1~2 mm)的土壤试样,测试了不同含水率、含盐量(Na₂SO₄)和粒径的土壤试样表观电导率(EC_a),分析了EC_a与含水率、含盐量和粒径之间的关系,并采用灰色关联法得到了EC_a与含水率和含盐量之间的灰色关联度。结果表明:(1) EC_a随着含水率、含盐量和粒径的增加均呈增大的变化规律,当粒径为0.075~0.1 mm,含盐量为0.64%,含水率由5%增加至25%时,EC_a增大0.99 mS·cm^-1,增幅为2475%;当粒径为0.075~0.1 mm,含水率为10%,含盐量由0.18%增加至12.18%时,EC_a增大1.47 mS·cm^-1,增幅为864.71%;当含盐量为6.18%,含水率为10%,粒径由<0.075 mm增加至1~2 mm时,EC_a增大0.36 mS·cm^-1,增幅为38.71%。(2) 通过建立EC_a、含水率和含盐量之间的关系模型,得出在较高含水率(>15%)条件下,EC_a与含盐量之间的相关关系(P<0.05)显著于低含水率(≤15%)条件(P>0.05),即当含水率分别为10%和20%,含盐量由3.18%增加至12.18%时,EC_a增幅分别为56.41%和128.91%,说明高含水率条件下盐分对EC_a的灵敏度显著于低含水率。(3) 通过采用灰色关联分析法得到EC_a与含水率之间平均灰色关联度为0.80,与含盐量之间平均灰色关联度为0.68,说明当含水率为5%~25%,含盐量为0.18%~12.18%时,EC_a与含水率之间的发展态势一致性高于含盐量。该研究结果对于硫酸盐渍土导电特性和盐渍化程度评价具有参考价值。

This study first measured the sulfate saline soil in the Xiaoxigou basin of the Beishan area in the Xining Basin, China. Five groups of soil samples with different particle sizes (<0.075 mm, 0.075-0.1 mm, 0.1-0.25 mm, 0.25-0.5 mm, 0.5-1 mm, and 1-2 mm) were obtained through the screening test. The apparent electrical conductivity (EC_a) of the soil samples with different moisture contents, salt contents (Na₂SO₄), and particle sizes were then tested, and the relationship between EC_a and moisture content, salt content, and particle size were analyzed, and the gray correlation degree was obtained using the gray correlation method. The results showed that increased moisture content, salt content, and particle size resulted in an increasing change law for EC_a. For example, when the particle size was 0.075-0.1 mm, the salt content was 0.64%, and the moisture content increased from 5% to 25%, EC_a increased by 0.99 mS·cm^-1, an increase amplitude of 2475%. When the relationship model between EC_a, moisture content and salt content was established, it was concluded that under higher moisture contents (greater than 15%), the correlation between EC_a and salt content (P<0.05) was significantly higher than that of low moisture content conditions (less than 15%) (P>0.05). For example, when the moisture content was 10% or 20%, and the salt content increased from 3.18% to 12.18%, the increased amplitudes of EC_a were 56.41% and 128.91%, respectively, indicating that the sensitivity of salt to EC_a under high moisture content conditions was more significant than the low moisture content. The average gray correlation degree between EC_a and the moisture content was 0.80, and between EC_a and salt content was 0.68. This indicates that the consistency of the development trend between EC_a and moisture content was higher than that of the salt content, when the moisture content was 5%-25%, and the salt content was 0.18%-12.18%. These research results have reference value for the evaluation of the electrical conductivity and salinization degree of sulfate saline soil.