Conclusion

The study on heavy metal concentrations in vegetables grown near Varthur lake, Bangalore, has shown significant accumulation of heavy metals in vegetables that correlated well with its soil and lake water concentrations. The prolonged irrigation of vegetables using such contaminated lake water has led to soil contamination, which ultimately resulted in contamination of vegetables due to the uptake and accumulation of heavy metals in edible portions of vegetables. The heavy metal content in vegetables exceeded the safe limits in India. Thus, urgent attention is needed to devise and implement appropriate means of regular monitoring of these toxic heavy metals from domestic sewage and industrial effluent and provide proper advice and support for the safe and productive use of wastewater for irrigation purposes in order to prevent excessive build-up of heavy metals in the food chain. The higher SAR is another important factor that highlights the lake water is unsuitable for irrigation purposes.

RECOMMENDATIONS

• Treating sewage at decentralized levels to prevent eutrophication of water bodies;
• Ensuring zero discharge of industrial effluents;
• Removal of heavy metals (through adsorption) and recovery (desorption)
• Development of a self-sustaining bioremediation-based wetland systems are;

1. Nutrient removal through select wetland plants, preferably native species (such as Alternanthera sp., Ludwigia sp.) for efficient wastewater treatment and resource recovery.
2. Removal of heavy metals dual-mode cation/anion-based natural resins at the treatment locations or through natural porous beds with high cation exchange capacity.
3. Further screening of macrophytes to check their efficiencies in nutrient and heavy metal removal.
4. Design of a suitable treatment to treat municipal and agro-industrial wastewater.
5. Regular de-sludging of algal ponds for maintaining critical depths for optimal algal photosynthesis.