采煤塌陷裂缝对沙蒿吸水来源影响试验研究

Effect of coal mining subsidence fractures on source of water absorption of Artemisia Desertorum

  • 摘要: 采煤塌陷引起的地裂缝不仅造成地质灾害,还会影响矿区植被的生长发育,破坏矿区生态系统。为深入探讨采煤塌陷裂缝对沙蒿吸水来源的定量影响,在神东矿区活鸡兔井田22312工作面选取了受采煤塌陷裂缝影响程度不同的3个试验区进行同位素标记水模拟降水试验。3个试验区根据沙蒿与裂缝的距离不同划分,其采煤塌陷情况分别为未开采区(试验样地内沙蒿距离裂缝大于50 m)、受采煤塌陷影响但无明显裂缝区(简称无明显裂缝区,试验样地内沙蒿距离裂缝大于5 m)以及裂缝区(试验样地内分布有宽度15 cm左右的裂缝通过,且距离沙蒿0~20 cm)。本次试验选择6株沙蒿作为研究对象,划分6个土壤剖面,采用液态水同位素分析仪LGR和Isoprime 100同位素比值质谱仪IRMS分别计算不同土层土壤水和植物样本木质部水的δ18O和δ2H同位素含量,并利用R脚本的MixSIAR贝叶斯混合模型量化降水后不同土层对沙蒿吸水的贡献,探讨土壤水分补给机制和植物水分来源。结果表明:(1) 裂缝区的优先流比例为18.2%;(2) 在未开采区,沙蒿吸收的59.7%的水分来自10~20 cm的土层;(3) 在无裂缝区,沙蒿主要从40~60 cm土层(46.6%)和0~10 cm土层(39.4%)吸水;(4) 在裂缝区,沙蒿吸收的85.9%的水分主要来自40~60 cm的土层。研究结果对揭示采煤塌陷裂缝区土壤水补给机制以及沙蒿吸水模式具有重要意义。

     

    Abstract: Ground fissures caused by coal mining subsidence are not only a serious geological hazard, but also affect the growth and development of vegetation in the mining area and damage the mining ecosystem. To investigate the quantitative influence of coal mining subsidence fractures on the source of water uptaken by Artemisia Desertorum, the simulated precipitation tests of isotopically-labeled water were conducted in three test areas influenced by coal mining subsidence fractures to different degrees on 22312-working face of Huojitu mine field in Shendong mining area. The three test areas were divided according to the distance between Artemisia Desertorum and the fractures, where the coal mining subsidence conditions were classified as the virgin zone (where the Artemisia Desertorum was over 50 m away from the cracks in the test area), the zone affected by coal mining subsidence without obvious fractures (hereinafter referred to as fracture-free zone, where Artemisia Desertorum was more than 5 m away from the fractures in the test area) and the fracture zone (where the fractures with a width of about 15 cm passed through the test area at 0-20 cm away from Artemisia Desertorum). In this test, six pieces of Artemisia Desertorum were selected as the research objects and divided into six soil profiles. Then, the δ18O and δ2H isotope contents of soil water and xylem water of plant samples in different soil layers were calculated with LGR liquid water isotope analyzer and Isoprime 100 isotope ratio mass spectrometer (IRMS) respectively. In addition, the contribution of different soil layers to the water uptaken by Artemisia Desertorum after precipitation was quantified with the MixSIAR Bayesian mixture model of R script, and to explore the mechanism of soil water recharge and the source of plant water. The results show that: (1) The proportion of preferential flow in the subsidence fracture zone is 18.2%, (2) 59.7% of water uptaken by Artemisia Desertorum comes from the 10‒20 cm soil layer in the virgin area, (3) 46.6% and 39.4% of water comes from the 40‒60 cm and 0‒10 cm soil layers in the fracture-free zone, respectively, and (4) 85.9% of water uptaken by Artemisia Desertorum is mainly derived from the 40-60 cm soil layer in the subsidence fracture zone. The research results are significant to reveal the mechanism of soil water recharge and the water uptake pattern of plants in subsidence fracture zone of coal-mining areas.

     

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