柽柳生物炭对滨海盐渍土咸水入渗特征的影响研究

Effect of Tamarix ramosissima biochar on infiltration characteristics of saline water in coastal saline soil

由于生物炭具有较高的孔隙度和有机碳含量,故在盐渍化土壤改良方面潜力巨大。然而,利用盐生植物柽柳制备的生物炭改良盐渍化土壤以探究其对盐渍化土壤咸水入渗特征影响的研究尚少。本研究采用室内土柱模拟入渗的方法,研究柽柳生物炭添加量(质量分数为0、1.1%和3.3%)和不同矿化度咸水(0 g∙L^(−1)、5 g∙L^(−1)和10 g∙L^(−1))对盐渍土水分入渗特性及水盐分布规律的影响。研究表明:1)随生物炭添加量以及咸水矿化度的增加,湿润锋运移时间缩短34.40%~85.85%,入渗率增大6.71%~87.30%;添加生物炭对盐渍土水分入渗特性的影响程度大于咸水矿化度。2)生物炭的添加使水分入渗后0~10 cm土壤的含水量增加1.29%~9.23%。3)水分入渗后,0~40 cm土壤含盐量与初始土壤含盐量相比显著降低,且盐渍土含盐量随入渗咸水矿化度的增大有上升趋势,但不显著;含盐量在深度50~60 cm处达最高,且随生物炭含量以及咸水矿化度的升高而显著增加,与淡水入渗后未添加生物炭的对照相比增加5.21%~35.11%。综上,不同矿化度咸水入渗条件下,柽柳生物炭的添加可以加速盐渍化土壤的盐分淋洗,并随生物炭添加量的增加其淋洗效果明显增强,本研究中生物炭添加量为3.3%时的效果最优。此结果可为生物炭合理施用以及滨海地区咸水资源利用提供必要的理论依据。

Biochar has great potential for improving saline soil quality owing to its high porosity and organic carbon content.However,biochar was prepared from a halophyte(Tamarix ramosissima),which has rarely been used to improve saline soil quality,for exploring the characteristics of saltwater infiltration in saline soil.In this study,a soil column simulation method was used to study the effects of T.ramosissima biochar addition(mass fractions of 0,1.1%,and 3.3%)and saltwater with different salinities(0,5,and 10 g·L^(−1))on water infiltration characteristics and water and salt distribution in saline soil.The results showed the following.1)With an increase in the biochar addition amount and salinity of saltwater,the migration time of the wet front decreased by 34.40%-85.85%,and the infiltration rate increased by 6.71%-87.30%;moreover,the effect of biochar addition on the water infiltration characteristics of saline soil was greater than that of saltwater.2)The addition of biochar increased the water content of 0-10 cm soil by 1.29%-9.23%.3)After water infiltration,the soil salt content at 0-40 cm depth decreased significantly compared with the initial soil salt content,and the salt content in saline soil increased with the increase in salinity of saline water;however,no significant differ-ence was found.The salt content was highest at a depth of 50-60 cm,and it increased significantly with the increase in biochar addi-tion amount and salinity of saltwater,which increased by 5.21%-35.11%compared with the control group without biochar after fresh water infiltration.In conclusion,under different salinity saltwater infiltration conditions,T.ramosissima biochar addition can acceler-ate soil salt leaching,and its leaching effect noticeably increasing with an increase in the amount of added biochar.In this study,the effect was observed at an optimal addition of 3.3%of biochar.And the results for rational application of biochar and saltwater re-source utilization in coastal areas provide the necessary theoretical basis.