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陕北采煤沉陷区不同沉陷年限黄土坡面土壤可蚀性的变化规律

Variation of soil erodibility on loess slope under various subsidence years in coal mining subsidence area located Northern Shaanxi

  • 摘要: 土壤可蚀性不仅可以定量刻画土壤自身抗侵蚀能力,还能反映人类活动产生的水土流失效应,研究煤炭采动损害对土壤可蚀性的影响有利于煤矿区生态环境保护。以陕北煤矿区沉陷年限分别为1~5、6~10 a的典型沉陷坡面土壤(垂直深度20 cm以浅)为研究对象,分别用MS2000激光粒度仪和总有机碳分析仪测定了土壤机械组成和有机质含量,并以此为基础利用EPIC模型计算土壤可蚀性K值,阐明了土壤机械组成和有机质的空间变化特征,揭示了沉陷坡面的水土流失效应。研究结果表明:① 陕北煤矿区开采沉陷不会改变土壤质地类型,但随沉陷年限增加坡顶部位土壤砂化程度加剧,坡中部位土壤砂化程度减缓,坡脚部位土壤砂粒含量下降趋势、黏粒含量增加趋势日趋明显。沉陷1~5 a的坡顶部位10~20 cm土层土壤物理结构恶化最为严重,沉陷6~10 a内的坡脚部位10~20 cm土层物理结构改善最为明显;② 开采沉陷会产生降低坡顶、坡中部位土壤有机质含量的效应,平均降幅为20.8%~55.3%。随着沉陷年限的增加,坡顶部位土壤有机质含量降幅加剧,坡中部位土壤有机质含量降幅减缓。沉陷6~10 a的坡顶部位0~10 cm土层土壤化学结构恶化最为严重,而对坡脚部位土壤有机质含量的影响不明显;③ 陕北煤矿区开采沉陷会产生提高周围土壤的可蚀性的效应,随着沉陷年限的增加,坡顶、坡中、坡脚部位土壤可蚀性K值增幅均有所减缓。沉陷1~5 a的坡顶部位0~10 cm土层土壤可蚀性K值增幅最显著,而沉陷6~10 a的坡中部位以及不同沉陷年限下坡脚部位0~10 cm土层土壤可蚀性K值变化不明显。开采沉陷会显著扩大坡顶部位两层土壤可蚀性的差异,缩小坡中、坡脚部位2层土壤可蚀性的差异;④ 陕北煤矿区沉陷坡顶土壤可蚀性K值较大,土壤抗侵蚀能力较差,应着重考虑人工措施如土壤结构改良、施肥等进行水土流失精准防控,坡脚、坡中部位则应着重考虑自然措施。该结果可为黄河流域中游煤矿区水土流失精准防控和生态环境保护与高质量发展提供科学依据。

     

    Abstract: Soil erodibility can not only quantitatively describe the anti erosion ability of soil,but also reflect the effect of soil erosion caused by human activities. Studying the impact of coal mining damage on soil erodibility is conducive to the protection of ecological environment in coal mining areas. Taking the typical subsidence slope soil (shallow with vertical depth of 20 cm) with subsidence years of 1-5 a and 6-10 a in Northern Shaanxi coal mine area as the research object,the soil mechanical composition and organic matter content were measured by MS2000 laser particle sizer and total organic carbon analyzer respectively. On this basis,the soilerodibility K-value was calculated by EPIC model. The spatial variation characteristics of soil mechanical composition and organic matter are clarified,and the effect of soil and water loss on subsidence slope is revealed. The results show that:① The mining subsidence in Northern Shaanxi coal mining area can not change the soil texture type. With the increase of settlement years,the degree of soil desertification at the top of the slope intensifies,the degree of soil desertification at the middle of the slope slows down,and the decreasing trend of soil sand content and the increasing trend of clay content at the foot of the slope are becoming more obvious. The deterioration of soil physical structure of 10-20 cm soil layer at the top of the slope for 1-5 a is most serious,and the improvement of soil physical structure of 10-20 cm soil layer at the foot of the slope for 6-10 a is most obvious;② The mining subsidence can reduce the content of soil organic matter at the top and middle of the slope,with an average decrease of 20.8%-55.3%. With the increase of subsidence years,the decline of soil organic matter content at the top of the slope intensifies,and the decline of soil organic matter content in the middle of the slope slows down. The deterioration of soil chemical structure of 0-10 cm soil layer at the top of the slope subsided for 6-10 a deteriorated most seriously,but the effect on the content of soil organic matter at the foot of the slope was not obvious;③ Mining subsidence in Northern Shaanxi coal mining area have the effect of improving the erodibility of surrounding soil. With the increase of subsidence years,the increase of soil erodibility K-value at the top,middle and foot of slope slows down. The increase of soil erodibility K-value of 0-10 cm soil layer at the top of the slope for 1-5 a is the most significant,the change of soil erodibility K-value of 0-10 cm soil layer at the middle of the slope for 6-10 a and at the foot of the slope after different subsidence years is not obvious. The mining subsidence significantly expand the difference of soil erodibility between the two layers at the top of the slope and reduce the difference of soil erodibility between the two layers at the middle and foot of the slope; ④ The 8-value of soil erodibility at the top of subsidence slope in Northern Shaanxi coal mine area is large and the soil anti-corrosion ability is poor. Artificial measures such as soil structure improvement and fertilization should be considered for accurate prevention and control of soil erosion,and natural measures should be considered at the foot and middle of slope. The results can provide scientific basis for accurate prevention and control of soil erosion,ecological environment protection and high-quality development in coal mining areas in the middle reaches of the Yellow River Basin.

     

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