Soil pollution has many causes. Contaminants can be directly introduced. Soil can be contaminated by air pollution when precipitation deposits acidic compounds such as sulfur dioxide and nitrogen oxide. Human activities such as mining can release acidic drainage, which can have widespread effects. Whatever the cause, soil pollution has negative effects on plants and flora as well as the organisms that depend upon them.
Acidic soils created by deposit of acidic compounds such as sulfur dioxide produce acidic environment that is not tolerated by micro-organisms, which improve the soil structure by breaking down organic material and aiding in water flow.
Soils polluted by acid rain have an impact on plants by disrupting the soil chemistry and reducing plants' ability to take up nutrients and undergo photosynthesis.
While aluminum occurs naturally in the environment, soil pollution can mobilize inorganic forms, which are highly toxic to plants and can potentially leach into ground water, compounding their effects.
Contaminated soils with high levels of nitrogen and phosphorus can leach into waterways, causing algal blooms, resulting in the death of aquatic plants due to depleted dissolved oxygen.
Acidic deposition into the soil can hamper its ability to buffer changes in the soil pH, causing plants to die off due to inhospitable conditions.