Environmental Issues Test - 10

TCE and PCE are man-made chemicals and often used as solvent to remove grease and paints in dry cleaning. Acute exposure to TCE and PCE affects the central nervous system of human beings.

DDT, PCB and CFCs are long chain hydrocarbon that do not break down easily in the environment by biological action. Chlorinated and halogenated compounds are easily broken down into simpler forms.

Pollution can be controlled by a number of methods.

The most common use of fly ash is as a partial replacement for portland cement used in producing concrete. Replacement rates normally run between 20% to 30%, but can be higher. Fly ash reacts as a pozzolan with the lime in cement as it hydrates, creating more of the durable binder that holds concrete together.Fly ash generated on burning coal can be used to manufacture bricks.

The process of recycling is always equated with cost reduction and with lessening if not eliminating the wastes that go to landfills. Polyester fibers from recycled bottles are now used to cut down on manufacturing costs for textiles. Naturally, this will also mean cheap clothes for consumers. Bottles of soft drinks can also be used for making fibers for carpeting etc.

Heavy metals like Cadmium, Mercury, Lead and Arsenic are toxic and potential carcinogens, cancer causing substance. Azolla plant is used to absorb heavy metals in the ecosystem.

Bioaccumulation results from a dynamic equilibrium between exposure from the outside environment and uptake, excretion, storage, and degradation within an organism. The extent of bioaccumulation depends on the concentration of a chemical in the environment, the amount of chemical coming into an organism from the diet, water, or air, and the time it takes for the organism to acquire the chemical and then excrete, store, and/or degrade it. The nature of the chemical itself, such as its solubility in water and fat, affects its uptake and storage. Equally important is the ability of the organism to degrade and excrete a particular chemical. When exposure ceases, the body gradually metabolizes and excretes the chemical.

At each trophic level in a food chain concentration of pollutants is magnified in the food chain.

ECOSAN is a type of dry toilet most used in Kerala and Sri Lanka.

The important features of the ECOSAN toilet are:

• It is not polluting water or soil, because the faces are kept in the watertight chambers.
• Even if the ground around the toilet is flooded, faces will not get in connection with the water.
• It is improving environmental sanitation by converting faces to manure.
• It uses less water than other toilets. 2-3 litters of water per day are enough. The standard toilet requires 10 – 12 litters per day.
• A person can save up to 7000 litters of water per year. This is a big advantage when water is becoming scarce at various times of the year.
• Urine is separated at the time of defecation and will be mixed with the water from washing.
• All the water will be diverted to a soakage pit, to the kitchen garden or collected and used as urea for agriculture.
• The human waste is safely disposed of by the user of the toilet.
• There is no odor.
• The toilet is easy to clean.

Secondary Pollutants: These are those which are formed from the pri­mary pollutants by chemical interaction with some constituent present in the atmosphere. Examples are: Sulphur trioxide, nitrogen dioxide, alde­hydes, ketones, ozone etc.

Electronic waste" or "E-Waste" may be defined as discarded computers, office electronic equipment, entertainment device electronics, mobile phones, television sets, and refrigerators.

These are managed by buried in landfills or incinerated. These wastes produce harmful chemical and gases when burned in open.

Sanitary landfills are sites where waste is isolated from the environment until it is safe. It is considered when it has completely degraded biologically, chemically and physically.

In sanitary landfill, wastes are dumped in a depression or trench after compaction and covered with dirt every day. Sanitary land fill is better than open dump burning as burning causes air pollution.