高汞背景土壤中Hg在NaCl型融雪剂作用下迁移规律研究

Study on Hg Migration in Soil with High Mercury Background under the Action of NaCl Type Snowmelt Agent

冬季下雪天气,为保证交通畅达,使用融雪速度快、不必运输和处理积雪、交通恢复快等优点的融雪剂。综合考虑价格低廉、不易受环境温度影响、低温融雪效率较高等特点后氯盐型融雪剂被广泛应用。融雪剂的大量施用致使土壤结构破坏和肥力下降,形成盐碱化;土壤微生物种群和酶活性降低,土壤活力降低;增加和活化土壤重金属,造成重金属污染。通过汞在土壤中的迁移试验,研究了融雪剂对高背景汞地区土壤中汞的迁移规律。结果表明:土壤在NaCl作用下,以Langmuir方程求得的土壤对重金属吸附作用强弱的指标参数k1值由0.3降至0.03,说明Hg2+在土壤中的吸附能力降低。由淋溶实验数据得出,在NaCl作用下,流出液检测到汞离子的时间相差30小时,说明NaCl的加入使汞迁移提前。而土柱实验得出,Hg2+主要集中在土壤表层,随着土壤深度的增加其含量逐渐减小,随着淋滤液的增加,离子的浓度峰向土壤深处移动,并且在NaCl的作用下,离子迁移的速率加快,向下迁移能力增强。通过研究氯化钠对土壤中汞的迁移行为影响,对揭示在极端气候公路铺洒氯化钠型融雪剂对汞的迁移行为有重要意义。

In winter rain and snow weather, in order to ensure smooth traffic, the use of snow melting agent has the advantages of fast snow melting speed, no need to transport and deal with snow, and fast traffic recovery. In consideration of the characteristics of low price, not easy to be affected by ambient temperature and high low-temperature snow melting efficiency, chlorine salt type snow melting agent has been widely used. The large amount of application of snow melt agent results in the destruction of soil structure, the decline of soil fertility and the formation of salinization. Soil microbial population and enzyme activities decreased, and soil vitality decreased. Increase and activate soil heavy metals result in heavy metal pollution. The migration of mercury in soil by snowmelt agent in high background mercury area was studied. The results showed that under NaCl, the index parameter K1, which was calculated by Langmuir equation, decreased from 0.3 to 0.03, indicating that the adsorption capacity of Hg2+ in soil decreased. According to the data of leaching experiment, under the action of NaCl, the time difference between mercury ions detected in the outflow liquid was 30 hours, indicating that the addition of NaCl made mercury migration advance. The soil column experiment showed that Hg2+ was mainly concentrated in the soil surface, and its content gradually decreased with the increase of soil depth. With the increase of leachate, the concentration peak of ions moved to the depth of soil. Moreover, under the action of NaCl, the rate of ion migration was accelerated, and the downward migration ability was enhanced. The study of the effect of sodium chloride on mercury migration in soil is of great significance to reveal the effect of sodium chloride snowmelt on mercury migration in extreme weather highway.