Treatment of Soil Pollution.

Not unexpectedly, soil contaminants can have significant deleterious consequences for ecosystems. There are radical soil chemistry changes which can arise from the presence of many hazardous chemicals even at low concentration of the contaminant species. These changes can manifest in and arthropods resident in a given soil environment. The result can be virtual eradication of some of the primary food chain, which in turn have major consequences for predator or consumer species. Even if the chemical effect on lower life forms is small, the lower pyramid levels of the food chain may ingest alien chemicals, which normally become more concentrated for each consuming rung of the food chain. Many of these effects are now well known, such as the concentration of persistent DDT materials for avian consumers, leading to weakening of egg shells, increased chick mortality and potential extinction of species.

Effects occur to agricultural lands which have certain types of soil contamination. Contaminants typically alter plant metabolism, most commonly to reduce crop yields. This has a secondary effect upon soil conservation, since the languishing crops cannot shield the Earth's soil mantle from erosion phenomena. Some of these chemical contaminants have long half-lives and in other cases derivative chemicals are formed from decay of primary soil contaminants.

Soil pollution at both former and present industrial sites represents a serious potential threat to human health, ecosystems and the economy. Because of the wide variety of soil pollutants and concentrations, impacts are imprecisely known. The potential effects of soil pollution are:

• release of contaminants to the land surface, groundwater or surface water;

• uptake of contaminants by plants;

• direct contact by humans with contaminated soil;

• inhalation of dust particles or volatile substances;

• fire or explosion of landfill gases;

• corrosion of underground pipelines and other building components;

• generation of hazardous, secondary waste streams;

• conflict with proposed land use.

The conventional methods of soil pollution are very time-consuming and very costly. EPA (Environmental Protection Agency) officials excavate the soil to dispose of it elsewhere – a band-aid for the problem, no doubt, but essential for toxic disasters in highly populated places. Soils can be aerated, heated up in a process called thermal remediation, contained with pavement or caps, extracted with an active electromechanical system or propagating the soil with microbes that will digest organic pollutants.

New processes are being developed to combat the problem in a natural, less laborious way. By studying plants that grew naturally in toxic mines, scientist Chen Tongbin discovered that certain plants loved to eat heavy metals like arsenic, bronze, lead, zinc, cobalt and cadmium. The contaminants can then be retrieved from the plant's leaves and used in industrial materials. This safe and effective method isn't perfect, but it's a start.

Prevention of Soil Pollution. Naturally, prevention is the best cure for soil pollution. Most states have enacted tougher legislation to stop illegal dumping. For instance, one can expect five years in jail and a fine of $100,000 for soil pollution in Texas. Educating consumers about the dangers of littering, while encouraging recycling programs, is a good way to ensure everyone does their part to keep debris where it belongs. Consumers can also make a concerted effort to buy organic foods to demand that chemical pesticides aren't used on their foods.

People who grow their own food can keep excess nitrogen and phosphorus out of the soil by choosing crops that do not need as many nutrients from the soil, by applying fertilizer during the growing season to replenish the soil, by shortening the grazing season / cattle density, by using organic compost, by keeping the surface moist and mulched, and by choosing fruiting crops like tomatoes, squash, peas and corn. Gardens should be situated away from old painted buildings and roadways. Outer leaves of lettuce should be discarded and all vegetables should be washed before eating.

Over the years, stronger and more indestructible bins were created to store hazardous materials. Researchers will continue to look for ways to improve manufacturing and agricultural processes to avoid the need for toxic byproducts. Business leaders, miners and community officials will work together to reduce wastefulness and contaminants to keep the world a clean place for future generations.

Cleanup options. Cleanup or remediation is analyzed by environmental scientists who utilize field measurement of soil chemicals and also apply computer models for analyzing transport and fate of soil chemicals. Thousands of soil contamination cases are currently in active cleanup across the U.S. as of 2006. There are several principal strategies for remediation:

· Excavate soil and take it to a disposal site away from ready pathways for human or sensitive ecosystem contact. This technique also applies to dredging of bay muds containing toxins.

· Aeration of soils at the contaminated site (with attendant risk of creating air pollution)

· Thermal remediation by introduction of heat to raise subsurface temperatures sufficiently high to volatize chemical contaminants out of the soil for vapour extraction. Technologies include ISTD, electrical resistance heating (ERH), and ET-DSPtm.

· Bioremediation, involving microbial digestion of certain organic chemicals. Techniques used in bioremediation include landfarming, biostimulation and bioaugmentating soil biota with commercially available microflora.

· Extraction of groundwater or soil vapor with an active electromechanical system, with subsequent stripping of the contaminants from the extract.

· Containment of the soil contaminants (such as by capping or paving over in place).

Before you read Texts 3 and 4

· What are the noise pollution effects you feel almost every day?

· What do you think is necessary to do to reduce noise pollution?

· What are the most common sources of noise pollution?

Text 3. Noise Pollution.

The Causes and Sources.

The word noise is derived from the Latin term nausea meaning seasickness. Noise is defined as unwanted sound, a potential hazard to health and communication dumped into the environment with regard to the adverse effect it may have on unwilling ears. Sound, which pleases the listeners, is music and that which causes pain and annoyance is noise. At times, what is music for some can be noise for others. Noise pollution (or environmental noise) is displeasing human-, animal- or machine-created sound that disrupts the activity or balance of human or animal life.

Noise pollution is a type of energy pollution in which distracting, irritating, or damaging sounds are freely audible. As with other forms of energy pollution (such as heat and light pollution), noise pollution contaminants are not physical particles, but rather waves that interfere with naturally-occurring waves of a similar type in the same environment. Thus, the definition of noise pollution is open to debate, and there is no clear border as to which sounds may constitute noise pollution. In the most narrow sense, sounds are considered noise pollution if they adversely affect wildlife, human activity, or are capable of damaging physical structures on a regular, repeating basis. In the broadest sense of the term, a sound may be considered noise pollution if it disturbs any natural process or causes human harm, even if the sound does not occur on a regular basis.

Decibel is the standard unit for measurement of sound. Usually 80 db (decibel) is the level at which sound becomes physically painful. And can be termed as noise. Humans, animals, plants and even inert objects like buildings and bridges have been victims of the increasing noise pollution caused in the world. Be it human or machine-created, noise disrupts the activity and balance of life. While traffic dons the cap of being the largest noise maker throughout the world, there are many others that add to it, making our globe susceptible to its effects. The effect of noise pollution is multi-faceted and inter-related.

Causesand Sources of noise Pollution. Noise can arise from several sources: domestic noise (loud music, barking dogs); commercial or industrial premises (pubs, clubs, factories); noisy equipment (alarms, ventilation fans, refrigeration units); outdoor events; vehicles (car alarms, ice cream chimes); construction work (from DIY to major projects).

The source of most outdoor noise worldwide is transportation systems, including motor vehicle noise, aircraft noise and rail noise. Traffic noise is the main source of noise pollution caused in urban areas. With the ever-increasing number of vehicles on road, the sound caused by the cars and exhaust system of autos, trucks, buses and motorcycles is the chief reason for noise pollution. Poor urban planning may give rise to noise pollution, since side-by-side industrial and residential buildings can result in noise pollution in the residential area.

With the low flying military aircrafts soaring over the national parks, wasteland and other vacant areas, the level of noise pollution has drastically increased in these previously unaffected zones. People living beside railway stations put up with a lot of noise from locomotive engines, horns and whistles and switching and shunting operation in rail yards. This is one of the major sources of noise pollution.

To meet the demands of the basic necessity of living, the construction of buildings, highways and city streets causes a lot of noise. Pneumatic hammers, air compressors, bulldozers, loaders, dump trucks and pavement breakers are the major sources of noise pollution in construction sites.

Though not a prime reason, industrial noise adds to the noise pollution. Machinery, motors and compressors used in the industries create a lot of noise which adds to the already detrimental state of noise pollution. Plumbing, boilers, generators, air conditioners and fans create a lot of noise in the buildings and add to the prevailing noise pollution.

Household equipments, such as vacuum cleaners, mixers and some kitchen appliances are noisemakers of the house. Though they do not cause too much of problem, their effect cannot be neglected. Other sources of indoor and outdoor noise pollution are car alarms, emergency service sirens, office equipment, factory machinery, construction work, groundskeeping equipment, barking dogs, appliances, power tools, lighting hum, audio entertainment systems, loudspeakers, and noisy people.