Plants Combat Water And Soil Pollution

plants-combat-water-and-soiSome time ago, after I began living in Delhi, I finally went to see our river, the Yamuna. What I saw was a black oily fetid sludge carrying plastic and other filth. I am sure if I put a finger into it , the finger would dissolve. But I eat the vegetables grown on its banks. Rs. 2000 crores were given to the State Government to clean it, laws have been made that forbid sewage and industry from pouring its filth into the river – but the money has long gone into bureaucrats’ children being sent to Yale and Harvard and the industrialist is on holiday in Europe.
India cannot cope with urbanisation. Clean water, clean soil, planned waste disposal – these are not on any voter’s agenda. While bureaucrats and politicians love solutions that involve buying machinery, there will have to be things that people can do themselves. Studies by UNICEF and Jadavpur University show that 29 districts in Bihar, Uttar Pradesh, Assam, Chattisgarh and Jharkhand have large-scale contamination of arsenic. In West Bengal and in Bangladesh arsenic-laden waters are far outstripping the damage caused by the radiation leak in Chernobyl or the chemical catastrophe in Bhopal. More than 112 million people are drinking water contaminated with arsenic. Transport exhaust has contaminated the roadside soils of most areas including the foothills of theHimalayas, the pristine Tarai area with lead.
Hyderabad sits on soil with high contents of lead, cadmium, nickel and chromium. Concentrations of chromium and cadmium in the groundwater of Aligarh, Uttar Pradesh are at toxic levels. Heavy metals, radioactive contaminants (“radionuclides”), pollutants caused by energy and fuel production, and industrial manufacturing taint every inch of India’s ground. Many sites are contaminated by spills and drainage from chemical plants. Sewage irrigated soils are equally infected.
To solve a problem of this magnitude, one needs a technology that is environmentally sustainable and economically viable. Scientists suggest a process that uses plants to remove, transfer, stabilise, or destroy contaminants in soil, sediment, and groundwater. This process is called Phytoremediation.. What essentially happens is that plants remove harmful chemicals from the ground when their roots take in water and nutrients from polluted soil, streams, and groundwater. Once inside the plant, chemicals can be stored in the roots, stems, or leaves changed into less harmful chemicals within the plant or changed into gases that are released into the air as the plant breathes. These plants can be harvested.
Wayne State University, Detroit and the University of Georgia’s Department of Genetics teams have made phytoremediation of arsenic possible. They inserted two genes from E. coli called arsC and ECS into the mustard family plant, Arabidopsis thaliana. The altered plants remove arsenic from the soil, and send it to their leaves which can be harvested or incinerated. These plants can clean up a contaminated site in just two years.
Currently, some 400 plants are known to act as vacuum cleaners A fern called Pityrogramma calomelanos, known as silver fern (powdery yellow with white undersides) can accumulate arsenic at very high levels and grows readily on arsenic-contaminated soils.
Cadmium, used in a large number of industrial applications like batteries, coating of stabilisers, paint, and alloys is toxic even at very low concentrations. One of the most promising plants for the extraction of heavy metals such as cadmium from contaminated sites is Brassica juncea commonly known as Indian mustard ( rai). Its roots help in removing zinc, lead, cromium, copper, selenium and nickel as well. In 1992 it was discovered that Bent grass (Agrostis tenuis) and Red Fescue (Festuca rubra) a common forage grass could remove lead , zinc and copper from contaminated soils. Sunflowers have been used successfully to remove radioactive contaminants like lead and uranium in Chernobyl, Ukraine. Poplars can clean up nitrates and heavy metals in soil and groundwater.
Lead contamination in industrial regions is worrying. The lead accumulating plant, Indian Sarsaparilla (Hemidesmus indicus ) known as anantamul could be grown all over the area. So could Ragweed (Ambrosia artemisiifolia), Hemp Dogbane or Indian hemp (Apocynum cannabinum) and Sunflowers (Helianthus annuus). Yellow oleander( Nerium) leaves accumulate lead upto 78 mg/g dry weight. Canna generalis, with the bright red and yellow flowers, also extracts lead. The Scented Geranium (Pelargonium. “Frensham)is extremely efficient in taking up large amounts of lead, cadmium and nickel in a short time.
The Pant University of Agriculture and Technology, Pantnagar has recommended the water hyacinth (Eichornia crassipes or Jalakumbhi), and channel grass (Vallisneria spiralis) to be used for cleaning lignin and acidic distillery effluents from pulp and paper mills. Pennywort (Hydrocotyle umbellata ) and duckweed (Lemna minor ) are aquatic species that can remove heavy metals from water. Water hyssop(Bacopa monnieri) known as barami or jalnim, can pull out Chromium. Salt-tolerant barley and sugar beets can extract Sodium chloride (common salt) to reclaim fields previously flooded by sea water. Barley (Hordeum vulgare ) and oat (Avena sativa ) take in metals such as Copper, Cadmium and Zinc.
There are many success stories in which plants help nature rectify the crimes of man. In Chemobyl, Ukraine, sunflowers showed 90 per cent reduction of strontium in 2 weeks while in Ashtabula in Ohio, they removed 95 per cent of uranium. Indian mustard, in New Jersey brought lead to below danger level in one season ! InDearing, Kansas where the lead smelters are, poplars were used to remedy soil filled with lead, zinc and cadmium. In Milan, canary grass, bulrushes which are wetland grasses with small brown spiklets and Erodias helped in removing 90 per cent of TNT and RDX from an ammunition plant site.
Spiny Amaranths (Amaranthus spinosus), Alligator weed (Alternanthera philoxeroides) the semi aquatic weed you see on most polluted rivers, grown on the sewage sludge of Musi river in Hyderabad have shown that they can concentrate cadmium, zinc and iron in their leaves. They can be used to restore sewage sludge contaminated sites. Cotton plants can contain Mercury, while Groundnuts control Copper levels. Brahmi ( Bacopa monnieri) mused in Ayurvedic medicines can also be used in containing Chromium.
Vetiver Grass (Chrysopogon zizanioides) or khas and Common Reed( Phragmitis karka) have shown good results in removing phosphates and nitrate. Plants can be used to clean up petrochemical sites and storage areas, ammunition wastes, fuel spills, chlorinated solvents, landfill leachates, and soil contaminated with agricultural chemicals like pesticides and fertilisers. It is cheaper than other treatments and is aesthetically pleasing.
Instead of waiting for Governments to develop civic responsibility , you should use this information for industry owners and your own colony water and soil. As one who roams barefoot most of the time, it bothers me to absorb cancer through my feet or to eat it in my tomatoes and grain.


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