- Researchers from Mahatma Gandhi University, Kottayam have found high levels of heavy metal contamination in banana fields in 3 southern Indian states.
Highlights of the Report
- The report assessed the level of nutrient and toxic heavy metals in banana fields.
- The study covered three south Indian states, Kerala, Karnataka, and Tamilnadu.
- It is found that heavy-metal contamination in green revolution fields is due to decade –long use of chemical fertilizers or plant protective chemicals.
- 286 soil samples were used for sample analysis.
- The quantitative assessment of ten metals done in these soils included Calcium, Magnesium, Manganese, Zinc, Iron, Copper, Lead, Nickle, Chromium, and Cobalt.
- The amount of Cu observed in many fields was higher than the previous reports.
- The amount of Co observed in 25 fields was above its threshold levels expected for normal soils.
- The amount of Pb observed in all the soils appeared quite normal.
- The amount of Ni observed in 14 soil series exceeded the upper limit of contamination.
- Calcium levels were reaching the threshold levels.
- Cr was detected in all the samples.
- Magnesium content was found to be unusually high of about 900 mg/Kg.
- Normally magnesium content of soil in South Indian soil is known to be between 30 and 220 mg/Kg.
Causes of high contamination
- Decade-long use of chemical fertilizers without proper soil testing.
- Calcium is used to maintain the soil pH and over the years has accumulated in the soil.
- Manganese is a major component of pesticide used against fungal diseases like Fusarium wilt gets accumulated in the soil if overused.
- High Iron concentration is mainly due to the laterite-based soil of the Deccan Plateau.
About Heavy-Metals contamination
- Heavy metals are metallic elements with an atomic number greater than 20.
- They are trace elements having a density at least five times that of water.
- Some of these elements are necessary for growth, development and functioning of living organisms
- These include Copper, zinc, chromium, iron etc.
- Those which are unnecessary include cadmium, lead, mercury.
- However, beyond a certain limit all of them are toxic for plants, animals and humans.
- These elements penetrate the body by inhalation, ingestion and skin absorption.
- If heavy metals accumulate in body tissues faster than the body’s detoxification a gradual build-up of these toxins occurs.
- Vegetables provide the trace elements and heavy metals.
- Minor or trace elements are essential for good health if they come from an organic or plant source.
- In contrast, if they come from an inorganic or metallic source, they become toxic.
- Vegetables and fruits accumulate higher amounts of heavy metals because they absorb these metals in their leaves.
- The excessive amount of these metals in food is associated with:
- Cardiovascular, kidney, nervous, bone diseases
- Decreasing immunological defences
- Intrauterine growth retardation
- Impaired psychosocial faculties
- Disabilities associated with malnutrition
- Upper gastrointestinal cancer