煤矸石填充对沟道导排水性能和土壤肥力及重金属污染的影响

为探寻适合东北黑土区侵蚀沟复垦的技术方法,该文研究了一种基于复垦后导排水能力最大的侵蚀沟煤矸石填充复垦技术方法,通过模拟一定深度的沟道、应用响应曲面法探究覆土和煤矸石填充厚度的变化对于复垦沟道导排水性能的影响及最优厚度搭配组合预测。同时引入土工布并考察土工布对煤矸石淋溶过程中重金属的隔绝作用。选择一条用煤矸石填充复垦4 a后的侵蚀沟,在耕层(0～20 cm)进行土壤肥力以及重金属污染情况的调查研究。结果表明:1)土层厚度增加减弱沟道导排水能力,混合粒径、大粒径煤矸石层厚度增加增大沟道导排水能力,土层与大粒径煤矸石层组合存在交互作用。覆土、混合粒径及大粒径煤矸石层厚度分别为53.42、38.51、90 cm时,模拟2 m深沟道导排水能力最强。2)沟道复垦4 a后,容重增加、酸度改善、全磷含量持平于对照土壤,全氮、全钾及有机质含量显著低于对照土壤。综合肥力小于对照土壤,略高于黑龙江省第二积温带的土壤综合肥力。3)复垦土壤Pb含量持平于当地对照土壤及背景值,Cr、Cu含量高于当地对照土壤及背景值,但均未超过环境质量二级标准值,3种重金属存在轻度污染及富集现象。研究结果可为土地整理规划提供一定借鉴。

Effects of coal gangue filling on drainage performance, soil fertility and heavy metal pollution in erosion gully

Abstract: In order to explore the suitable technology for the reclamation of erosion gullies in the black soil area of the Northeast China. In this paper, Xinhua farm is selected as the research area which is located in Hegang City, Heilongjiang Province, China. Aiming at the cause of erosion gullies, a new technology of filling and reclamation erosion gully with coal gangue was introduced and the post effect of the new technology was studied, including, the technological process of filling and reclamation, the influence of the thickness change of reclamation filling materials on the drainage characteristics of the gully, the fertility status and heavy metals pollution degree in the reclaimed soil. This paper aimed to explore the feasibility and breakthrough points of the technology of filling erosion gullies with coal gangue. The results showed that: 1) The increase in soil layer thickness could weaken the drainage capacity of the gully, while the increase of mixed size coal gangue thickness and large size coal gangue could increase the drainage capacity of the gully in different degrees. The interaction between the soil layer thickness and large size coal gangue layer thickness obviously influenced the drainage capacity of the gully. When the thickness of soil layer, mixed size coal gangue layer and large size coal gangue layer were 53.42, 38.51, 90 cm respectively, the shortest outflow time was 145.129 s , the drainage capacity of simulated 2 m deep gully was the strongest in this mode. 2) After 4 years of gully reclamation, the soil bulk increased, the soil acidity improved, the content of total potassium was the same as CK, but the total nitrogen, total phosphorus and organic matter content were lower than CK. And then the comprehensive fertility of soil was less than CK, which is 66.71%-80.81% of CK, and the average level only reach to 72.75%. But it was slightly higher than that of the second accumulated temperature zone in Heilongjiang Province. 3) The content of Pb was basically the same as CK and background value of local control soil; however, as for Cr and Cu, they were higher than CK and background value of local control soil in the reclaimed soil of monitoring gully. But the content of Cr, Pb, Cu are not higher than the second level standard value of national environmental quality of China. . There are slight pollution and slight enrichment of heavy metals Cr, Pb and Cu in monitored gully reclamation soil, so coal gangue can be used as a material for filling erosion gully for reclamation. However, in the long term, attention should be paid to the problem of soil heavy metal enrichment during reclamation.