矿粮复合区煤累积对土壤团粒结构的影响

为理解煤对土壤结构的影响,以土壤煤累积现象普遍的焦作矿粮复合区为研究区,选取3种不同程度的煤累积土壤(低累积、中累积和高累积)为研究对象,不含煤的土壤为对照,通过测定0—40 cm土层深度范围的水稳性团聚体组成,并采用分形维数(D)、平均重量直径(MWD)、几何平均直径(GMD)和大团聚体破坏率(PAD)作为团粒结构的评价指标,探讨煤累积对土壤团聚体组成与稳定性的影响。结果表明:煤在土壤中累积可以促进水稳性微团聚体向大团聚体转化,降低团聚体的分形维数,提高团聚体稳定性。深层(20—40 cm)土壤水稳性大团聚体含量的增幅高于表层(0—20 cm)土壤。土壤团聚体稳定性随着煤累积程度的增高表现出先增加后降低的趋势。土壤团聚体的稳定性主要取决于>2 mm粒级水稳性团聚体的含量。总体上,煤在土壤中的累积改善了土壤的团粒结构性状。此外,根据本研究结果,研究区长期运煤、堆煤、洗煤和矿井水灌排等活动导致的黑土现象并不能视作煤污染。

Effect of Coal Accumulation on Soil Aggregate Structure in the Mine-crop Overlapped Zone

In order to understand the effect of coal accumulation on soil structure, three different levels of coal accumulation soils samples (low accumulation, moderate accumulation and high accumulation) were collected from the Jiaozuo mine-crop overlapped zone, and the coal-free soil was taken as the control. Soil samples were collected in the 0-10 cm, 10-20 cm, 20-30 cm and 30-40 cm soil layers. Water-stable aggregate fractions were measured, and fractal dimension (D), mean weight diameter (MWD), geometric mean diameter (GMD) and macroaggregate destruction rate (PAD) were used as evaluation indicators to evaluate the effects of coal on the composition and stability of soil aggregates. The results showed that coal accumulation in the soils promoted the transformation of soil water stable microaggregates to macroaggregates, reduced the D value and increased soil aggregate stability. The increase amplitude of water stable macroaggregate content in deep soil layer (20-40 cm) was higher than that in surface soil layer (0-20 cm). Soil aggregate stability showed a trend of increase firstly and then decrease with the increasing of coal accumulation. It was also found that soil aggregate stability depended mainly on the content of water stable aggregates that greater than 2 mm. Our results suggested that coal accumulation in soils obviously improved soil structure. In addition, according to the results of this study, the black soils phenomenon due to long-term transportation, dumpling and washing of coal and mine water drainage and irrigation in the study area should not be considered as coal pollution.