1.why do u think ecology is important?
2.think of some environmental issues their causes and solutions......
Why Ecology is important ?
Ans : Ecology is of utmost importance to all species including us. We, like all other animals depend on this earth for everything; food, water, shelter. Everything on this earth depends on something else but ecology is so dynamic that even the smallest perturbation can upset everything.
A good example is global warming. Many people think that 2 degrees over a decades is a small amount of time. NOTHING in Ecology is small, the repercussions are severe. Plants need a certain temperature to thrive, warming of the earth can upset this and also upset life and mating cycles. We depend on those animals to eat and certain animals also survive on those animals.
In addition, human interference with the ecology of certain places can also exacerbate the problem of natural disasters. When we log on mountainsides and hills, we destabilize soils and the topology of the landscape. Heavy rains which would originally cause some kind of erosion would now cause landslides that could engulf roads and cause hazards to villages or towns and people that live in those areas.
In addition, chapparal forests in California is a type of terrestrial biome. If we do not understand the fact that these trees will constantly be subjected to fires, then people will build luxurious houses in these areas (which they are already doing), and when wildfires rage through the area, they will want insurance and money to rebuild. The fact is, houses are not supposed to be built in those areas in the first place, and if they are, insurance companies should not be shelling out money to the rich and misinformed who choose to live in such a biome.
So you see, Ecology is important to us financially, aesthetically, and also for our simple survival on this planet. Hence, it should be taken with utmost importance not only for us but for our next generation.
Some environmental issues are :
1. Land degradation
Land degradation is a concept in which the value of the biophysical environment is affected by one or more combination of human-induced processes acting upon the land. It is viewed as any change or disturbance to the land perceived to be deleterious or undesirable. Natural hazards are excluded as a cause, however human activities can indirectly affect phenomena such as floods and bushfires.
Land degradation is a global problem, largely related to agricultural use. The major causes include:
-Land clearance, such as clearcutting and deforestation
-Agricultural depletion of soil nutrients through poor farming practices
-Livestock including overgrazing
-Inappropriate Irrigation  and overdrafting
-Urban sprawl and commercial development
-Land pollution including industrial waste
-Quarrying of stone, sand, ore and minerals
e main outcome of land degradation is a substantial reduction in the productivity of the land. The major stresses on vulnerable land include:
Accelerated soil erosion by wind and water
-Soil acidification and the formation of acid sulfate soil resulting in barren soil
-Soil alkalinisation owing to irrigation with water containing sodium bicarbonate leading to poor soil structure and reduced crop yields
-Soil salination in irrigated land requiring soil salinity control to reclaim the land 
-Soil waterlogging in irrigated land which calls for some form of subsurface land drainage to remediate the negative effects 
-Destruction of soil structure including loss of organic matter
2. Ozone depletion
Ozone depletion describes two distinct, but related observations: a slow, steady decline of about 4% per decade in the total volume of ozone in Earth's stratosphere (the ozone layer) since the late 1970s, and a much larger, but seasonal, decrease in stratospheric ozone over Earth's polar regions during the same period. The latter phenomenon is commonly referred to as the ozone hole. In addition to this well-known stratospheric ozone depletion, there are also tropospheric ozone depletion events, which occur near the surface in polar regions during spring.
The detailed mechanism by which the polar ozone holes form is different from that for the mid-latitude thinning, but the most important process in both trends is catalytic destruction of ozone by atomic chlorine and bromine. The main source of these halogen atoms in the stratosphere is photodissociation of chlorofluorocarbon (CFC) compounds, commonly called freons, and of bromofluorocarbon compounds known as halons. These compounds are transported into the stratosphere after being emitted at the surface. Both ozone depletion mechanisms strengthened as emissions of CFCs and halons increased.
CFCs and other contributory substances are commonly referred to as ozone-depleting substances (ODS). Since the ozone layer prevents most harmful UVB wavelengths (270-315 nm) of ultraviolet light (UV light) from passing through the Earth's atmosphere, observed and projected decreases in ozone have generated worldwide concern leading to adoption of the Montreal Protocol that bans the production of CFCs and halons as well as related ozone depleting chemicals such as carbon tetrachloride and trichloroethane. It is suspected that a variety of biological consequences such as increases in skin cancer, cataracts, damage to plants, and reduction of plankton populations in the ocean's photic zone may result from the increased UV exposure due to ozone depletion.
The ozone hole and its causes
The Antarctic ozone hole is an area of the Antarctic stratosphere in which the recent ozone levels have dropped to as low as 33% of their pre-1975 values. The ozone hole occurs during the Antarctic spring, from September to early December, as strong westerly winds start to circulate around the continent and create an atmospheric container. Within this polar vortex, over 50% of the lower stratospheric ozone is destroyed during the Antarctic spring.
As explained above, the primary cause of ozone depletion is the presence of chlorine-containing source gases (primarily CFCs and related halocarbons). In the presence of UV light, these gases dissociate, releasing chlorine atoms, which then go on to catalyze ozone destruction. The Cl-catalyzed ozone depletion can take place in the gas phase, but it is dramatically enhanced in the presence of polar stratospheric clouds (PSCs).
These polar stratospheric clouds(PSC) form during winter, in the extreme cold. Polar winters are dark, consisting of 3 months without solar radiation (sunlight). The lack of sunlight contributes to a decrease in temperature and the polar vortex traps and chills air. Temperatures hover around or below -80 °C. These low temperatures form cloud particles. There are three types of PSC clouds; nitric acid trihydrate clouds, slowly cooling water-ice clouds, and rapid cooling water-ice(nacerous) clouds; that provide surfaces for chemical reactions that lead to ozone destruction.
The photochemical processes involved are complex but well understood. The key observation is that, ordinarily, most of the chlorine in the stratosphere resides in stable "reservoir" compounds, primarily hydrochloric acid (HCl) and chlorine nitrate (ClONO2). During the Antarctic winter and spring, however, reactions on the surface of the polar stratospheric cloud particles convert these "reservoir" compounds into reactive free radicals (Cl and ClO). The clouds can also remove NO2 from the atmosphere by converting it to nitric acid, which prevents the newly formed ClO from being converted back into ClONO2.
The role of sunlight in ozone depletion is the reason why the Antarctic ozone depletion is greatest during spring. During winter, even though PSCs are at their most abundant, there is no light over the pole to drive the chemical reactions. During the spring, however, the sun comes out, providing energy to drive photochemical reactions, and melt the polar stratospheric clouds, releasing the trapped compounds. Warming temperatures near the end of spring break up the vortex around mid-December. As warm, ozone-rich air flows in from lower latitudes, the PSCs are destroyed, the ozone depletion process shuts down, and the ozone hole closes.
Most of the ozone that is destroyed is in the lower stratosphere, in contrast to the much smaller ozone depletion through homogeneous gas phase reactions, which occurs primarily in the upper stratosphere.
Nov 08, 2010 |
Computers & Internet