Checking Pollution of Environment and Stabilizing Chemical Cycles

Ever since industrialization began, about two centuries ago mankind has altered earth’s chemistry drastically which may have staggering ecological and economical consequences within our lifetimes or those of our children. Three important out-comes of the changes in earth’s chemistry brought about by industrial societies are especially threatening and costly to the entire humanity. These are:

1. Diminishing food security from a changing climate.

2. Degeneration of forests and green cover and reduction in biodiversity.

3. Risk to humans from exposure to chemical pollutants of the environment.

(1) The Gravity of the Problem:

These out-comes have raised from day to day activities cumulative effect of which have reached the scale and pace sufficient to disrupt natural systems that evolved through millions of years. A large number of questions remain unanswered for each of these threats and more research is urgently needed to clear the uncertainties surrounding them. Waiting for a definite picture to emerge, could, however, be dangerous as by the time we reach any conclusion, the world will already be committed and disastrous effects inevitable and irreversible.

The troubling aspect of the environmental threat is that natural system – including human bodies, forests, climate etc. – may absorb the abuses inflicted by man for long time without much sign of degeneration. A point is finally reached – scientists call it threshold or inflection point – when the system collapses suddenly. It is difficult to pin point when this situation shall occur. As the scale and pace of human activity intensify the risk of overstepping this threshold rises. The wise strategy would be to avoid activities detrimental to the life support system right from the very beginning.

Only six elements, Hydrogen, Carbon, Oxygen, Nitrogen, Sulphur and Phosphorus form 95% of the mass of all living matter present on our planet. As the supplies of these elements is fixed life depends on recycling and re-use of these element through atmosphere, soil and rocks, water and living organisms of the biosphere – processes referred to as bio-geo-chemical cycles. Since 1860, we have introduced about 200 billion tons of carbon into the atmosphere.

Most of this carbon was earlier trapped in fossil fuels limestone and organic matter. The concentration of methane, another green­house gas has roughly doubled since its 1600 A.D. level. The amount of oxides of nitrogen added to the atmosphere by human activity roughly equals the total quantity of the N0₂ produced by all natural processes combined.

So is the quantity of sulphur dioxide added to the atmosphere which is about 100 million tons per year? These gases dissolve in droplets of water and come down as acid rains. The reactions of atmospheric gases, water vapour and other pollutants under intense solar radiations cause photochemical smog in the troposphere while high up in the stratosphere cause depletion of the vital ozone shield.

The concentration of manmade synthetic compounds like CFC or chlorofluorocarbon has risen so much as to produce significant impact on the atmosphere. They contribute to the global warming in the lower atmosphere while high up in the stratosphere they dissociate to produce chlorine atoms which destroy the vital ozone shield catalytically.

In addition to these gases, industrial activity has also turned many heavy metals and toxic trace elements into troublesome pollutants. In nature these substances occur in soils and rocks in forms and concentrations which pose little hazard. But with rapid rise in fossil fuel consumption, smelting, incineration and other high temperature processes the concentrations of these elements in the environment have increased remarkably.

Lead, Mercury, Cadmium and Zinc etc. are some of the metals which are being deposited at many places in concentrations toxic to man and other organisms. It is not only heavy metals and toxic trace elements but the concentration of manmade toxins such as DDT and other pesticides in various components of environment have reached such levels which is toxic to living beings. Nobody could anticipate that nearly two decades after the imposition of ban on DDT it would still be found in carrots and spinaches sold in the markets of San Francisco.

(2) Management Strategies:

There is little we can do about changes which have already occurred in chemistry of our environment – the nature shall take care of these abuses in its own way. In order to avoid further changes in the chemistry of our environment, we shall have to put restrictions on human activities which cause these changes. These activities are, however, our day to day activities which cannot be stopped altogether. In-order to moderate the adverse impact of human activity the following strategies are being followed:

1. Setting standards for effluents discharged in the environment.

2. Adopting more environment friendly technology.

3. Avoiding concentration of polluting industries and raising assimilative capacity of natural systems.

1. Setting standards for effluent to be discharged in the environment:

This approach provides statuary standards for each polluting unit – be it an automobile or an industry. These standards specify permissible limits in terms of different parameters of effluent quality and the polluting unit is required to ensure that the effluent it discharges are within the specified limits. These standards are based on evaluation of technical feasibility and economic viability.

A regular monitoring of each relevant parameter is done in order to ensure that the discharges are within the prescribed limits. For example, waste water from Tannery should not have a BOD higher than 30 mg/1 over 5 day period at 20°C. Tanneries are required to treat their liquid effluents in such a way that its BOD is reduced to levels below 30 mg/1 over 5 day period at 20°C. Thus, management based on standards distributes the responsibility of reducing the load of pollution to the polluting units.

2. Adopting more environment friendly technology:

A much better way to restrict the pollution of environment is adoption of more environment friendly technology. For example, of the three kinds of fossil fuels in common use these days, natural gas is the least polluting source of energy. Thus, the use of natural gas as source of energy shall be much friendlier to environment. This is true for a number of industries. Alternative process which cause much less pollution are available for a number of industries and where they are not available further research, and studies should be conducted to develop such methods and technology.

3. Avoiding concentration of polluting industries and raising assimilative capacity of natural systems:

Natural systems such as green cover, forests soils, and aquatic systems have a remarkable capacity to absorb, accumulate, assimilate and transform various pollutants of the environment. The adverse effects caused by smoke and waste gases from local industry can significantly be moderated by green cover surrounding the industry. We can inhance this capacity of the natural system by promoting green cover in areas surrounding the industry.

Barren land should be treated properly, provided fertilizers and water so that it turns into an eutrophic system – capable of supporting suitable plants and a variety of microbes so as to serve as an effective instrument of assimilation of waste material.

Avoiding concentration of polluting industry at a particular place is a much wise policy. Effluents from many industries add up and collectively place large burden of pollution on the system which exceeds its assimilative capacity. With little efforts and may be a little more cost these industrial units may be located away from each other so that their effluents do not collect and over­burden the surrounding environment.