Dissolved organic matter (DOM) in soil is the fraction of organic material that is soluble and small enough to pass through a fine filter.
Understanding Dissolved Organic Matter (DOM)
Here's a more detailed explanation:
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Definition: According to the reference, DOM is defined as the organic matter in a solution that can pass through a 0.45 μm filter. This means it's the portion of organic compounds that are dissolved in water within the soil.
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Ubiquitous yet Minor: DOM is found in both land and water environments. However, it's important to note that DOM represents only a small proportion of the total organic matter found in soil. The majority of organic matter exists in larger, particulate forms.
Key Characteristics of DOM
| Characteristic | Description |
|---|---|
| Size | Small enough to pass through a 0.45 μm filter |
| Solubility | Soluble in water |
| Location | Found in both terrestrial and aquatic ecosystems |
| Proportion in Soil | Represents a relatively small fraction of the total soil organic matter |
Importance and Practical Insights:
- Nutrient Cycling: DOM plays a crucial role in the movement and cycling of nutrients within the soil ecosystem. It can be a source of carbon and other essential elements for soil microbes and plants.
- Water Quality: DOM can also affect water quality. In aquatic systems, it can contribute to the color and turbidity of water, as well as influence the availability of light and nutrients.
- Soil Health: DOM contributes to soil health by influencing its structure, water-holding capacity, and biological activity.
- Transport of Pollutants: DOM can transport pollutants, such as pesticides and heavy metals, through soil profiles, potentially contaminating groundwater.
Examples of DOM Components
- Humic substances: A major component of DOM, derived from decomposed plant and animal material.
- Carbohydrates, amino acids, lipids: Products of microbial activity and plant exudates.
- Organic acids: Produced by microorganisms and plant roots.
Conclusion
In summary, dissolved organic matter (DOM) is a specific, water-soluble fraction of the total organic matter in soil, characterized by its small size and ability to pass through a 0.45 μm filter. Despite representing a small proportion, it's vital for soil processes, nutrient cycling, and water quality.
