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NWP Global Registry of Apprentice Ecologists - Elliots Beach, Besant Nagar, Chennai, India

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Elliots Beach, Besant Nagar, Chennai, India
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greenpeacelover



Registered: March 2012
City/Town/Province: Chennai
Posts: 1
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India has a number of rivers all of which are fed mainly by water from monsoon rains. The rivers in India drain a total area of 3.1 x 105 km2 and annually discharge 1650 km3 of water. This translates into a mean run off of about 500 mm yr for the entire India. The water discharge from India accounts for 4.5 per cent global river discharge.


Sources of Major Ions to Rivers


The river water is dictated by a number of sources. These include:


1. Rain/precipitation: The primary source of water for rivers is rainfall and snowmelt; which makes their composition an important component of river water chemistry.


It is their chemistry, which forms the base line for the evolution of river water composition. Rainwater composition is location dependent, near the coasts it is dominated by sea salt and in these regions the elemental ratios in rains are more similar to those in ocean. In inland regions, sea salt, continental dust, bioorganic and anthropogenic inputs contributes to chemistry of rains.


The relative significance of marine contribution to rain decreases with distance away from the coast and generally levels off to a constant low value inland. Na+ and CI" are the dominant components of coastal rains; this changes to Ca+2, HCO 3 and S04-2 in lands. Typical major ion chemistry of rains over select regions in India is given in derive most of their carbonic acid from this source.


In regions where vegetation is sparse, sue' as bare mountains or glaciated areas, atmospheric contribution of C02 to carbonic acid could be dominant.


2. Anthropogenic input: Major ion abundances in rivers can be modified by anthropogenic inputs such as discharge of sewage, industrial and mining effluents, and supply from fertilizers, etc.


This input can be an important source for Na, CI (NaCl in sewage, mining of sodium salts, solution of road salt, etc.), S04 (fertilizers, mining of pyrites, industrial wastes, atmospheric deposition from fossil fuel burning, etc.) and nutrients (nitrogen and phosphorus compounds, mainly from fertilizers).


It is estimated that on an average 30 per cent of Na, CI, S04 and nutrients can be of anthropogenic origin, for individual rivers, however, the contribution from this source can be significantly different from the mean.


In addition, there can be two other potential suppliers of major elements to rivers. One is organic matter, which during their growth incorporates elements such as N, P and K. Decay of organic matter can release these elements to rivers.


Among these, the nutrients (N and P) are recycled and are generally reconverted to organic matter by plant uptake. Potassium, concentrated in plant leaves is from weathering of silicates.


Another supplier of major elements to rivers is springs/ groundwater. Many rivers receive water from springs and groundwater, particularly during lean stages of their flow. The primary source of major ions to spring and ground waters is chemical weathering of aquifer rocks.


The importance of springs/groundwater on the abundances of major ions in rivers, though is recognized, it is difficult to quantify. More recently, Ge has been used as a tracer to estimate the water flow from springs to rivers in the Narayani basin of the Nepal Himalaya. Table 11.6 summarizes the various sources of major ions to rivers.


Rivers integrate the major ion contributions from the sources. Table 11.7 lists the chemical composition of select rivers. Several features are evident from the data. Total dissolved solids (TDS) show a range of over one order of magnitude, from 35 to 587 Mgl1. These values are within the range recommended for potable water18.


Among the various sources contributing major ions to rivers, supply from chemical weathering depends on the litho logy of the basin. River basins, particularly those of medium and large size rivers, are multi-litho logical comparing silicates/carbonates and lesser amounts of evaporate. Chemical weathering of river basins would supply major ions to solution from all these lithologies.


In the Himalayas, high TDS are in rivers of the Yamuna system particularly in its lower reaches and in the rivers from the plains. Some of these samples also have high CI and S04 indicative of major ion supply from weathering of evaporates alkaline/saline soils and anthropogenic inputs.


Water Pollution Control


The following measures can be taken to control water pollution:


1. Domestic and industrial wastewaters should be disposed off after treatment.


2. Proper sewage and industrial effluent systems can reduce incoming point source of pollution.


3. Bathing, washing etc. should be prohibited in the vicinity of sources.


4. Ponds, river, lakes etc. should be protected by suitable methods for the prevention of waste entry.


5. For domestic sewage Treatment plant should be designed.


6. Treated effluents from industries should be discharged into water source.


7. Ponds, lakes etc. should be regularly cleaned of aquatic weeds and plants.


8. Excess use of fertilizers and pesticides should be discouraged.


9. Public awareness regarding water pollution should be created.


10. Strict enforcement of pollution control laws should be more punitive.
· Date: April 1, 2012 · Views: 5455 · File size: 13.9kb, 65.7kb · : 720 x 540 ·
Hours Volunteered: 4
Volunteers: 15
Authors Age & Age Range of Volunteers: 13 to 21
Trash Removed/Recycled from Environment (kg): 100
Native Trees Planted: 50