脱硫石膏改良重度苏打盐化土的环境效应

为了解连续施用脱硫石膏改良苏打盐化土的持续效应及环境效应,以经过3a大田连续施用不同量脱硫石膏(0,15,22.5,30t/hm~2)改良的重度苏打盐化土为供试土壤,采用盆栽试验方法,研究2a盆栽试验后,脱硫石膏的持续效应对饲草玉米生长、土壤环境以及农作物中重金属累积的影响。结果表明:15t/hm~2用量的脱硫石膏可以显著提高饲草玉米的出苗率、株高、茎粗和生物量,较对照分别提高20.6%,16.8%,8.1%和10.1%,试验范围内改良效果最佳。脱硫石膏使土壤的pH、EC降低,Na~+减少,Ca~(2+)和SO_4~(2-)增加,且脱硫石膏用量越大,影响越大。土壤和饲草玉米地下部中的As、Hg、Ni含量随脱硫石膏用量的增加而增加,试验范围内土壤重金属含量均符合二级国家土壤环境安全标准(GB 15618—1995)。饲草玉米地上部重金属含量与脱硫石膏添加量无显著相关关系,根据饲料卫生标准(GB 13078—2001),各处理玉米中重金属含量均未超标。饲草玉米对重金属的富集作用地下部大于地上部,且对不同重金属富集能力CdHgAsNi。利用适量的脱硫石膏量改良苏打盐化土的持续效应良好,且对环境未造成不良影响。

Environmental Effect of the Amelioration of Heavy Soda Saline Soil Using Desulfurized Gypsum

To clarify the continuous and environmental effects of the amelioration of heavy soda saline soil using desulfurized gypsum,an outdoor pot experiment was conducted to study the growth situation of forage maize,physiochemical properties of the soil,and contents of heavy metals in plants when the soda saline soil was treated with different rates of desulfurized gypsum (0 t/hm2,15 t/hm2,22.5 t/hm2 and 30 t/hm2).The results showed that the amelioration effect of 15t/hm2 desulfurized gypsum was the best.It could significantly improve seedling emergence rate,plant height,stem diameter,and seedling biomass of forage maize,which was increased by 20.6％,16.8％,8.1％ and 10.1 ％ compared to the control,respectively.The pH,EC,and the content of Na+ in the soil were decreased,but the contents of Ca2+ and SO42-in the soil were increased.As the amount of desulfurized gypsum was increased,the effect of desulfurized gypsum became more obvious.The contents of As,Hg,and Ni in the soil and forage maize roots increased with increasing amount of desulfurized gypsum.According to the second grade of national environmental quality for the soils (GB 15618-1995),the contents of heavy metals (As,Hg,Cd,and Ni) in the tested soil were all complied with the Environment Quality Standard.The contents of heavy metals in forage maize shoots were not significantly correlated with the application rate of desulfurized gypsum,and the heavy metal contents in each treatment did not exceed the standard limits according to Hygienical standards for feeds (GB 13078-2001).The heavy metal contents in stems were less than those in shoots,and the accumulation rate of heavy metals was in the order of Cd＞ Hg＞As＞Ni.It can be concluded that the continuous effects of desulfurized gypsum to ameliorate the soda saline soil were good,and did not show any adverse impact on the environment.