Another way plants are used to treat heavy metal contamination is called rhizofiltration (EPA, 2000). In this method, heavy metals are removed di- rectly from water by plant roots. The plants are grown directly in water or in water rich materials such as sand, using aquatic species or hydroponic methods.

In the US, rules on the use of heavy metals like cadmium, lead, and mercury vary state by state. According to the organization Safer States, New York, Connecticut, Illinois, Maryland, Minnesota, and California have restrictions or bans on the use of cadmium in children’s jewelry.

Absorption through the skin is not a significant route of cadmium entry; only about 0.5% of cadmium is absorbed by the skin (ATSDR 1999).

Apart from antioxidants and other bioactive compounds, coffee contains carbohydrates, lipids, nitrogen compounds, vitamins and minerals, including toxic elements such as cadmium (Cd) and lead (Pb) [12, 14, 15].

Ex situ remediation techniques, although expensive, have the basic advantage of removing high concentrations of heavy metals from polluted soils. These conventional remediation techniques include soil washing, landfilling and leaching, electrokinetic treatment, and soil immobilization.

Popular Answers (1) Brassica juncea (Indian mustard) and Eichhornia crassipes (water hyacinth) have the the highest tendency of absorbing heavy metals from soil and water, respectively.

Options for treating contaminated soil include:

1. Biological treatment/bioremediation uses bacteria to break down substances in the soil.
2. Chemical oxidation converts contaminated soils into non-hazardous soils.
3. Soil stabilisation involves the addition of immobilizing agents to reduce a contaminants’ leachability.

There are many methods of treating or cleaning-up contaminated soils/sediments including both in-situ (treating in the ground) and ex-situ (removal of soil to treat) remediation considerations.

However, it turns out that the best way to clean contaminated soil is to grow plants that have evolved mechanisms for decomposing and removing toxic residue from soils. These plants are called hyperaccumulators because they are able to take up 100 times more metals and petrochemicals than other plants.

Why area treatment is important for soil? Explanation: Area treatment in soil reduces the impact of raindrops on the soil. The treatment measures are to develop vegetation cover on non-arable land. It effects in minimum disturbance and displacement of soil particles.

Adding organic matter in the form of compost and aged manure, or using mulch or growing cover crops (green manures), is the best way to prepare soil for planting. Adding chemical fertilizers will replenish only certain nutrients and do nothing for maintaining good, friable soil.

The best compost is aged compost; it will be blackish brown in color, moist, crumbly, and uniform in texture; the vegetable matter in aged compost will not be recognizable. The nutrients in aged compost—often called humus—will be the most accessible to plant roots.