烟气脱硫石膏对滨海盐渍土的改良效果

为研究烟气脱硫石膏对滨海盐渍土的改良效果，选取上海南汇东滩的滩涂盐渍土为研究对象，开展了两年的烟气脱硫石膏修复试验，研究不同施用量（0、15、30、45和60 t/hm2）烟气脱硫石膏对滨海盐渍土化学性质的改良效果和对绿化乔木生长特性的影响，以及烟气脱硫石膏作为滨海盐渍土改良剂的重金属安全性.结果表明:施加适量烟气脱硫石膏显著降低了滨海盐渍土的pH和ESP（碱化度），增加了对植物生长有利的Ca2+和SO₄2-含量，减少盐渍土中对植物生长有害的Na+和Cl-含量，降低了土壤速效磷和速效钾含量，增加了植物的株高和胸径.与对照处理相比，烟气脱硫石膏处理的土壤pH和ESP分别降低了5.7%~14.4%和16.7%~59.4%；土壤水溶性Na+和Cl-的含量降低了25.8%~64.4%和16.7%~59.5%，而土壤水溶性Ca2+和SO₄2-含量分别增加了4.08~31.30倍和9.83~23.33倍.施用烟气脱硫石膏2 a后，土壤速效氮与对照处理相比无显著差异，但土壤速效磷和速效钾含量分别较对照处理下降了35.6%~41.1%和21.9%~48.5%.烟气脱硫石膏施用量为60 t/hm2时，银杏和紫薇的株高分别增长了25.1%和34.7%，胸径分别增加了64.5%和35.2%.施用烟气脱硫石膏不会造成土壤重金属污染，不同处理下的土壤重金属含量均小于GB 15618—1995《土壤环境质量标准》二级标准.研究显示，烟气脱硫石膏应用于滨海盐渍土的改良，可以有效改善土壤质量和生态环境，为滨海城市贡献绿色耕地或绿化用地. 

Remediation Efficiency of Flue Gas Desulfurization Gypsum on Coastal Saline Alkali Soil

Saline alkali land restoration experiment carried out in the saline alkali soil of Nanhui District in Shanghai was conducted to assess the effect of application of flue gas desulfurization gypsum (FGD-gypsum) with different rates (0, 15, 30, 45 and 60 t/hm²) on chemical properties of saline soil and plant growth as well as the safety of FGD-gypsum as soil amendment. The results showed that soil pH and ESP could be decreased by appropriate rates of FGD-gypsum addition. The Ca²⁺ and SO₄^2- concentration in favor of plant growth increased, while Na⁺ and Cl^- concentration which could harmful on plants growth reduced. The contents of available phosphorus and available potassium in soil decreased, meanwhile plant height and DBH could be increased to promote plant growth. Compared with the control treatment, the soil pH and exchange sodium percentage (ESP) were reduced by 5.7%-14.4% and 16.7%-59.4%respectively with increasing FGD Gypsum rates. The Ca²⁺ and SO₄^2- concentrationwere increased by 4.08-31.30 times and 9.83-23.33 times respectively, and the Na⁺ and Cl^- were reduced by 25.8%-64.4% and 16.7%-59.5% respectively. The results also showed that the content of soil available phosphorus and available potassium were reduced by 35.6%-41.1% and 21.9%-48.5% respectively after using FGD-gypsum, but the soil available nitrogen had no significant difference compared with the control. The field experiments also showed that reduction of nutrient did not affect the plant growth. The plant height increased up to 25.1% and 34.7%, and the plan DBH were increased up to 64.5% and 35.2% at the rates of 60 t/hm². Moreover, the contents of the heavy metals in the soils well complied with the Environmental Quality Standard for Soils in China (GB 15618-1995), which implied that FGD-gypsum would not deteriorate the soil environmental quality. It''s expected that FGD-gypsum could be applied to the improvement of coastal saline land, which could effectively improve the quality and ecological environment of saline soil in coastal.