水溶性有机物在土壤中的化学行为及其对环境的影响

Behavior and environmental impact of soil dissolved organic matter

  • 摘要: 水溶性有机物(Dissolved organic matter,DOM)是能够溶解于水的有机化合物的统称。尽管目前对于陆地生态系统中DOM的研究尚不完善,对其性质、组成和分类方法等问题的看法还没有达成一致,但现有研究结果已经表明DOM是一种十分活跃的重要化学组分。DOM进入土壤后将发生吸附、解吸、迁移、转化等一系列化学过程,进而对土壤及环境产生一系列重要影响:一方面,DOM可以与土壤胶体结合,形成有机无机结合体,从而改善土壤性质,DOM还可以通过其自身的分解产生养分离子,从而提高土壤肥力;另一方面,DOM也可能亲合土壤中原来与土壤胶体结合的养分,使之与DOM一起进入土壤溶液,从而增加土壤中养分离子被淋失的风险,并造成土壤养分的损失以及水体的富营养化,DOM还有可能活化土壤中重金属离子,增加土壤中重金属离子的毒性,并使土壤中的重金属离子向地下水迁移。由于其对土壤和环境的多种效应,水溶性有机物近年来已经逐渐成为土壤学、环境科学、生态学等学科的研究热点之一。

     

    Abstract: Dissolved organic matter(DOM) is defined as organic matter that becomes absorbed in water. Irrespective of the fact that considerable disagreements remain on the character,composition and classification of DOM in terrene ecosystems, research has nonetheless proven that DOM is an active and important chemical component of natural systems.Once DOM enters the soil, chemical processes such as adsorption,desorption,transfer, transformation, etc. occur and consequently induce significant impact on the soil and environment. On the one hand, DOM combines with soil colloids to form organic-inorganic combos which sequentially improve soil quality. On the other hand, DOM aggregates with nutrients and metal ions and combines with original soil colloids, making them more easily releasable into soil solutions. Besides, DOM produces nutrient ions through decomposition and thus enhances soil fertility. These processes do not only result in nutrient leaching risk causing loss of soil nutrients and water eutrophication, but also enhance heavy metal eluviation by DOM activation effect on heavy metal ions in the soil and consequently exacerbate soil heavy metal toxicity. Therefore, DOM has increasingly become the research focus in the fields of agrology,environmental science,ecology, etc. in recent years due to its myraid effects on soil and the environment.

     

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