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森林火灾(林火)指在林地上自由蔓延的火,是一种自然界中的常见干扰。林火通过消耗凋落物层、燃烧植被、分解土壤有机质和改变粘土矿物等方式,释放出存在于植被与土壤中的金属成分,从而对土壤及水体重金属水平产生一定影响。多数研究结果表明,林火过后土壤中Mn、Cr、Ni、Pb等金属元素浓度短期内存在上升趋势,但不同案例中元素上升程度不同。随着时间的推移,土壤中大多数金属元素浓度可恢复至火灾前的背景值水平。但不同金属元素类型随时间变化的情况也有所不同。形态方面,林火过后多数元素主要以氧化态和有机结合态存在于土壤中。土壤pH和电导率作为土壤火烧严重度的潜在指标,它们的变化与土壤重金属浓度变化是否具有相关性在不同研究中存在较大差异。林火过后,径流水体中大多数重金属浓度水平上升,表明林火增加水体中重金属的潜在生态风险。今后还应开展更多室内与野外控制实验,进一步揭示林火对土壤及水体重金属变化的影响机制,为林业管理和灾害应急管理方面提供更多数据支持。
Forest fire (forest fire) Fire that spreads freely on woodlands is a common disturbance in nature. Forest fires release metal components present in vegetation and soil by consuming litter layers, burning vegetation, decomposing soil organic matter and changing clay minerals, thereby affecting the levels of heavy metals in soil and water. Most research results show that Mn, Cr, Ni, Pb and other metal elements in the soil after the forest fire there is a short-term upward trend in the concentration, but the rise in different cases, different elements. Over time, the concentration of most metal elements in the soil can be restored to the background level before the fire. However, the different types of metal elements vary with time. Morphology, the majority of elements after the forest fire mainly in the state of oxidation and organic binding exist in the soil. Soil pH and conductivity as potential indicators of soil fire severity, and their changes in soil concentrations of heavy metals whether there is a correlation between different studies there is a big difference. After the forest fire, the concentration of most heavy metals in runoff water increased, indicating that fires increase the potential ecological risk of heavy metals in water. In the future, more experiments on indoor and outdoor control should be carried out to further reveal the impact mechanism of forest fire on the changes of heavy metals in soil and water, and provide more data support for forestry management and disaster emergency management.