Monday, August 29, 2011

How the groundwater gets contaminated?

Groundwater is an important source of water supply throughout the world.


by


Dr. Nitish Priyadarshi




The circulation of water:

There is a continual movement of the earth’s water. The main reservoir is the ocean. From its surface water vapor is formed by the heat from the sun and carried up into the atmosphere by the air movement we called winds and breezes. The water vapor in the air is condensed to drops as the air rises and becomes visible as clouds. The contained moisture may then be precipitated as rain or snow or hail or mixture of these. The rain or snow which falls on the land may be partly re-evaporated, a part may flow into the streams and rivers and be returned to the ocean, and a part may sink into the ground where it supplies the moisture to the soil and also infiltrates downward into the rocks to form groundwater.

Water occupying openings, cavities, and spaces in rocks is commonly known as groundwater. There are two main sources of such water: Juvenile water, which rises from a deep, magmatic source, and meteoric water, which is due to rainfall having soaked into the underlying rocks. Water may be held in space between the grains of a rock (porosity) or in joints, cleavage, bedding planes etc.

Groundwater is an important source of water supply throughout the world. Its use in irrigation, industries, municipalities, and rural homes continue to increase. Cooling and air-conditioning have made heavy demands on groundwater because of characteristic uniformity in temperatures.

Groundwater pollution may be defined as the artificially or geologically induced degradation of natural groundwater quality. A large number of sources and causes can modify groundwater quality, ranging from septic tanks to irrigated agriculture. In contrast with surface water pollution, subsurface pollution is difficult to detect, is even more difficult to control, and may persist for decades. With the growing recognition of the importance of under groundwater, efforts are increasing to prevent, reduce, and eliminate groundwater pollution.

General mechanisms of groundwater contamination-

Contaminant releases to groundwater can occur by design, by accident, or by neglect. Most groundwater contamination incidents involve substances released at or only slightly below the land surface. Consequently, it is shallow groundwater which is affected initially by contaminant releases. In general shallow groundwater resources are considered more susceptible to surface sources of contamination than deeper groundwater sources. There are at least four ways by which groundwater contamination occurs: infiltration, direct migration, interaquifer exchange, and recharge from surface water.

Infiltration: contamination by infiltration is probably the most common groundwater contamination mechanism. A portion of the water which has fallen to the earth slowly infiltrates the soil through pore spaces in the soil matrix. As the water moves downward under the influence of gravity, it dissolves materials with which it comes into contact. Water percolating downward through a contaminated zone can dissolve contaminants, forming the leachate. Depending on the composition of the contaminated zone, the leachate formed can contain a number of inorganic and organic constituents. The leachate will continue to migrate downward under gravity’s influence until the saturated zone is contacted, horizontal and vertical spreading of the contaminants in the leachate will occur in the direction of groundwater flow.
Direct Migration: contaminants can migrate directly into groundwater from below ground sources (e.g. storage tanks, pipelines) which lie within the saturated zone. Storage sites and landfills excavated to a depth near the water table also may permit direct contact of contaminants with groundwater.
Interaquifer Exchange: contaminated groundwater can mix with uncontaminated groundwater through a process known as interaquifer exchange in which one water –bearing unit “communicates” hydraulically with another. This is most common in bedrock aquifers where a well penetrates more than one water-bearing formation to provide increased yield. Each water-bearing unit will have its own head potential, some greater than others. When the well is not being pumped, water will move from the formation with the greatest potential to formations of lesser potential. If the formation with the greater potential contains contaminated or poorer quality water, the quality of water in another formation can be degraded. Similar to the process of direct migration, old and improperly abandoned wells with deteriorated casings or seals are a potential contributor to interaquifer exchange.

Different sources of groundwater contamination-

Industrial sources:

1. Liquid wastes: Groundwater pollution can occur where industrial wastewaters are discharged into pits, ponds, or lagoons, thereby enabling the wastes to migrate down to the water table.
2. Tank and pipeline leakage: underground storage and transmission of a wide variety of fuels and chemicals are common practices for industrial and commercial installations. These tanks and pipelines are subject to structural failures so that subsequent leakage becomes a source of groundwater pollution. Petroleum and petroleum products are responsible for much of the pollution.
3. Mining activities: Mines can produce a variety of groundwater pollution problems. Pollution depends on the material being extracted and the milling process: coal, phosphate, and uranium mines are major contributors; metallic ores for production of iron, copper, zinc, and lead are also important. Heavy metal pollution is caused when such metals as arsenic, cobalt, copper, cadmium, lead, silver and zinc contained in excavated rock or exposed in an underground mine come in contact with water. Metals are leached out and carried downwards as water washes over the rock surface. Although metals can become mobile in neutral pH conditions, leaching is particularly accelerated in the low pH conditions such as are created by Acid Mine Drainage.


Agricultural Sources:

Irrigation return flows: Approximately one-half to two thirds of the water applied for irrigation of crops is consumed by evapotranspiration; the remainder, termed irrigation return flow, drains to surface channels or joins the underlying groundwater. Irrigation increases the salinity of irrigation return flow from three to ten times that of applied water. The degradation results from the addition of salts by dissolution during the irrigation process, from salts added as fertilizers or soil amendments.

Other sources.
1
Residential: Residential wastewater systems can be a source of many categories of contaminants, including bacteria, viruses, nitrates from human waste, and organic compounds. Injection wells used for domestic wastewater disposal (septic systems, cesspools, drainage wells for storm water runoff, groundwater recharge wells) are of particular concern to groundwater quality if located close to drinking water wells. Improperly storing or disposing of household chemicals such as paints, synthetic detergents, solvents, oils, medicines, disinfectants, pool chemicals, pesticides, batteries, gasoline and diesel fuel can lead to groundwater contamination. When stored in garages or basements with floor drains, spills and flooding may introduce such contaminants into the groundwater. When thrown in the household trash, the products will eventually be carried into the groundwater because community landfills are not equipped to handle hazardous materials. Similarly, wastes dumped or buried in the ground can contaminate the soil and leach into the groundwater.
2. Natural: groundwater contains some impurities, even if it is unaffected by human activities. The types and concentrations of natural impurities depend on the nature of the geological material through which the groundwater moves and the quality of the recharge water. Groundwater moving through sedimentary rocks and soils may pick up a wide range of compounds such as magnesium, calcium, and chlorides. Some aquifers have high natural concentration of dissolved constituents such as arsenic, boron, and selenium. The effect of these natural sources of contamination on groundwater quality depends on the type of contaminant and its concentrations.

Miscellaneous sources:

Stockpiles
Septic Tanks
Saline water intrusion.
Surface water.





Wednesday, August 10, 2011

8 Plant Species in Danger of Disappearing.

Source:


Plants don't get enough credit in our world. They're seen as lifeless decorations or a way to recycle cow manure. But plants have a magic all their own. A bouquet of flowers can patch up a couple after a fight, while a man-eating plant can play the villain in a movie or musical. Plus, they fill that minorly important role of producing food and oxygen. So while they help keep us alive, here are eight plant species that could probably use our help to survive.

1. Hawaiian gardenia

This small tree with white flowers is found on the islands of Lanai and Oahu in Hawaii and is also known as Nanu, though it probably has nothing to do with Mork. The trees grow to about 16 feet tall with shiny oval leaves, and the flowers have six petals. You've probably seen the flowers, or one of the other two types of gardenias in Hawaii, used in leis. There are thought to only be 15 or 20 trees left today, and those numbers are decreasing. Once common and found on all the main islands, the Hawaiian gardenia was used by Hawaiians for wood, dyes, and landscaping purposes.


2. Poke-me-boy
Though its name sounds like a Facebook come-on, the poke-me-boy is actually a spiny tree in the bean family found only on the British Virgin Islands, specifically on the island of Anegada. It produces fuzzy, yellow flowers between its long thorns. As the poke-me-boy's tiny island habitat becomes more developed for residences and tourism, the plant is suffering quick losses. Fire is often used to clear land, and the trees are continuously under threat of natural disasters. Hurricanes, earthquakes, and floods threaten the poke-me-boys, which live barely above sea level. There are also many roaming animals on the one-town island that often trample or graze on the plant

3. Cabbage on a stick
Cabbage on a stick is pretty much what it sounds like: a tuft of leaves that looks like a head of cabbage sitting on top of a thick stick. It's also known as alula. In the wild, this plant is only found on the Hawaiian island of Kauai and without the work of botanists, it would be extinct. Because the only insect that could pollinate the cabbage on a stick, a type of hawk moth, doesn't exist anymore, the plant species can only reproduce if humans hand-pollinate it. Botanists repelled down cliffs to reach the existing alula, pollinate it, and bring some back with them to grow in nurseries. Cabbage on a stick is still critically endangered in the wild, but can be found in plant conservatories around the world.
4. Mun ebony
Mun, or moon, ebony is from the same family as the black, shiny stuff that goes so well with ivory in song. But mun ebony is often striped and even more rare than black ebony. It's found in Vietnam and possibly Laos, and is just as dense as its famous cousin. Because of its heaviness and fine texture that allows it to be polished, it has been very popular to make instruments, tools, and sculptures from it. The export of mun ebony is now banned, and some parks are protecting the ebony within them, but it may not be enough to keep ebony from disappearing into the hands of merchants and woodworkers

5. Golden barrel

This plant is also known as mother-in-law's cushion, which would be sweet except that the golden barrel is a cactus. Even though this prickly sphere is one of the most popular kinds of cacti in cultivation, it is nearing extinction in the wild. It's found in Central Mexico, but its habitat was severely reduced in the '90s by the construction of a dam and reservoir. The golden barrel cactus is grown all over the world in nurseries, but people continue to take the cacti illegally from the wild. Experts estimate that this plant could be extinct in the wild within 30 years. And once it's gone, where will the in-laws sit?


6. Virginia round-leaf birch

This birch, the most endangered tree in North America, has already come back from the dead once. After it was first discovered in 1918, experts thought it had become extinct when they couldn't find any more, until more birches were discovered in 1975. The tree is found in Virginia, and while there are more than 900 found in the wild as of 2006, this birch is only known to have naturally reproduced once, in the '80s. This means the round-leaf birch is dependent on human aid to keep the species going. And humans are also a major threat to the tree; vandals and thieves have historically been attracted to the trees and seedlings, presumably because of their rarity. This is why we can't have nice things.


7. Large-leaved pitcher plant
When you first see the large-leaved pitcher plant, you might think it's just a vase of water conveniently growing in the jungle. But get too close and it could eat you — well, if you're a bug. The pitcher plant is one kind of carnivorous plant, and this is one of the largest versions, with the pitcher often growing more than a foot deep. It's only found on one mountain in Borneo, though, so this species faces the threat of extinction. Pitcher plants lure insects into their fluid-filled pitchers, where the insects drown and are ingested. Large-leaved pitcher plants were recently found to have the exact dimensions as tree shrews in the area, but even though the plants probably could trap and kill the rodents, it's more likely that they are engineered to catch the shrew's droppings for food. It'd be a pity to lose one of the only plants that gathers its own fertilizer.
8. Capa rose
The capa rose by any other name would probably not seem like a rose at all. It's actually part of a family of small trees that produce small, star-shaped flowers and bright purple berries. It only grows in Puerto Rico and has trouble reproducing naturally. Deforestation and development of land for agriculture are causing its habitat to shrink even further. The capa rose's habitat is under U.S. jurisdiction, and the Forest Service chose not to list its habitat as critical because they would have to publish details on the plant's location, basically providing a map for people who want to collect the plant illegally.

Sunday, August 7, 2011

My small journey on holy Ganga River in Varanasi city, India.


video


In spite of high pollution level river Ganga is still treated as holy river in India. This video is small travelling by me on boat on Ganga river in Varanasi city in India.

Saturday, August 6, 2011

वृक्ष कम होंगे तो कम होगा आक्सीजन .



झारखण्ड में प्रदुषण बढ़ने का भी खतरा होगा.
द्वारा
डा. नितीश प्रियदर्शी



आज पुरे विश्वा में जंगल का विनाश हो रहा हे. जंगल में लगी आग के रूप में या जंगल की कटाई के रूप में . वृक्ष हमारे वातावरण को संतुलित करते हैं. एवं जल चक्र को बनाये रखने में भी सहायक होता है. यह भू छरण को भी रोकता है. जंगल के विनाश से इनपर तो असर हो रहा हे किन्तु सबसे खतरनाक असर हमारे वातावरण में मौजूद प्राणवायु आक्सीजन पर दिख रहा है अब माना जाने लगा है की वृक्षों के कम होने से वायुमंडल में मौजूद आक्सीजन (२० %) में भी कमी होगी जो मनुष्य एवं दूसरे जंतुओं के लिये भी खतरनाक संकेत है. वृक्ष प्रकाश संश्लेषण की प्रक्रिया द्वारा वातावरण से कार्बन ड़ाइओक्सइड को लेकर आक्सीजन मुक्त करते है. इस आक्सीजन को जीव जीवित रहने के लिये ग्रहण करते है. पृथ्वी पर वृक्षों की यदि कमी होने लगेगी तो निश्चित रूप से इसका असर आक्सीजन की मात्र पर होगा.

वृक्ष के केवल कटने से ही नहीं; जंगल में आग लगने से भी आक्सीकरण की कमी हो सकती हे क्योंकि जलने से भी आक्सीजन का इस्तेमाल होता है. आज जिन पौधे या वृक्षों के बदौलत हमारे पृथ्वी पर आक्सीजन है हम उन्ही को कम करते जा रहे हैं. एक नए शोध से यह ज्ञात हुआ है कि १९८९ और १९९४ के बीच आक्सीजन कि मात्रा पृथ्वी पर २ भाग प्रति मिलियन प्रतिवर्ष के हिसाब से कम हुई है. कम होने कि गति काफी कम होने के कारण हम इसकी घटने कि गति पर नजर नहीं रख पा रहे हैं.

वृक्ष न केवल आक्सीजन देता हे बल्कि वातावरण को भी शुद्ध एवं ठंडा रखता है. अगर झारखण्ड की ही बात ले तो पिछले कुछ वर्षों मौसम में काफी बदलाव आ रहा है. वर्षा कभी औसत से कम या नहीं हो रही है. रांची जैसा शहर जो अपने मौसम के वजह से मशहुर था आज गर्म होते जा रहे है. इसका एक प्रमुख कारण है रांची के आस पास वृक्षों का कम होते जाना.

वर्षा के कम होने की वजह से यहाँ पेयजल के अस्तित्व पर भी खतरा पैदा हो गया है. वातावरण में कार्बन ड़ाइओक्सइड के बढ़ने का भी खतरा पैदा हो गया है. वृक्षों के कम होने से झारखण्ड के वातावरण में मौजूद आक्सीजन पर भी इसका बुरा प्रभाव हो सकता है जिसका असर आने वाले समय में दिख सकता है. अगर हमारे प्रदेश में आक्सीजन की मात्रा में जरा सा भी कमी आया तो ये कहने की जरुरत नहीं की हमारा क्या हाल होगा. प्रदुषण भी खतरनाक तरीके से बढ़ेगा वो अलग.