不同接触和淋洗时间下脱硫石膏对滨海吹填土理化性质的影响

为改善滨海吹填土的理化性质,加快提升吹填土在城市生态建设中的土地价值,开展脱硫石膏不同接触时间处理对滨海吹填土理化性质影响的试验研究。结果表明:滨海吹填土导水能力极弱,在整个淋洗过程中始终没有淋出液排出,2,5,10,50d脱硫石膏接触处理后土壤饱和导水率分别达到6.21,7.20,7.20,7.65mm/h,显著提升了滨海吹填土的导水能力。2,5,10,50d石膏接触处理分别经220,116,116,196h淋洗后,淋出液盐分均达到0.5dS/m以下,淋洗用水量分别为5.16,3.85,4.21,4.95L。淋洗后,土壤含盐量由处理前6.98dS/m下降到0.28～0.36dS/m,土壤中Cl-、Na+浓度分别由处理前的9.03,4.85g/kg下降到0.05～0.34g/kg和0.01～0.04g/kg,土壤钠吸附比(SAR)以及土壤碱化度(ESP)分别由处理前的27.89和28.15下降到0.18～0.8和0.02～0.28,已经为非碱化土,土壤的各理化指标均得到明显改善。综合各种因素与指标,脱硫石膏与吹填土5d接触处理效果最佳。

Effect of Desulfurizated Gypsum on Physic-chemical Properties of the Dredge Fill Under Different Contact and Leaching Time

In order to improve the physic-chemical properties and enhance the value of the land of the dredger fill in the urban ecological construction,the impacts of desulfruizated gypsum on physic-chemical properties were studied.The results showed that gypsum treatment significantly improve the salinity characteristics of the dredger fill after contacting and leaching.The leaching times for the contact time of 2 d,5 d,10 d,50 d four treatments were 220 h,116 h,116 h and 196 h respectively,when salt concentrations of the leachate were approaching 0.5 dS/m.A variety of physic-chemical indicators had significant improvement after testing,for example,soil salinity decreased from 6.98 dS/m to 0.28~0.36 dS/m,the contents of Cl-and Na+ ions in the soil reduced from 9.03 g/kg and 4.85 g/kg to 0.05~0.34 g/kg and 0.01~0.04 g/kg,ESP and SAR of the soil declined from 27.89 and 28.15 to 0.18~0.8 and 0.02~0.28 respectively after experiment.The saturated hydraulic conductivities of four treatments were also achieved 6.21,7.20,7.20,7.65 mm/h respectively and were significantly improved.Comprehensively considering indicators,the best contacting time between desulfurizated gypsum and the dredger fill was 5 d.