The outstanding economic and industrial growth that post-colonial India witnessed has resulted in unplanned urbanization and growing population pressure. This is bound to have its effects on the environment. Air, water and noise pollution from emissions, industrial activity and transportation has considerably damaged natural surroundings. Inadequate waste management and industrial effluence have made the country's rivers major carriers of chemical and water-borne diseases. This has left not only humans at risk, but also the continent's biodiversity, as virtually, every day, one species or the other faces the threat of extinction.

Urban India is among the most polluted places on the Earth. With economic liberalization and middle-class prosperity, the number of commercial and personal vehicles has gone up drastically, leading to excessive emissions and air pollution. While in metropolitan areas, checks and regulations for vehicle and industrial emission of greenhouse gases are normally enforced, they are non-existent in other major towns.

Unmanageable human and industrial wastes are the main causes of surface water pollution. While many rural areas lack even the most basic sanitation facilities, even the urban areas, which have them, generate sewage that goes untreated into water bodies. A greater risk comes from industrial effluents—hazardous chemicals that are simply dumped into rivers. Excessive use of pesticides and fertilizers also pollutes the groundwater from which much of the drinking water is drawn. Waste disposal also causes great pollution of stagnant water bodies, such as lakes and ponds, rendering them unfit for use.

In recent times, noise pollution level has also increased tremendously owing to indiscriminate distribution of industries, unplanned high degree of urbanization and dense transportation systems across the country.

Such widespread air, water and noise pollution causes considerable risk to human health. Air pollution is the main cause of respiratory diseases, while water pollution poses a more serious health hazard due to reasons like Arsenic and Mercury poisoning. The consequence of noise pollution is undoubtedly a delayed one, but more serious.

The current issue includes case studies that present up-to-date and basic information about the major types of environmental pollution—water, noise, solid and hazardous waste, radiation, thermal, and oil pollution and their adverse effects on man and the environment.

Remote sensing and Geographic Information System (GIS) are now being extensively used throughout the world to understand the coastal processes for its synoptivity and deliver information to inaccessible regions. In the first article, "Land Degradation in Coastal Areas and Its Impact: A Study Using Remote Sensing and GIS", D Mitra has studied the problem of saltwater intrusion in the Gulf of Cambay and made an attempt to find out the number of villages and the population affected by high chlorine content in drinking water.

It is well-known that secondary treatment of sewage reduces pollutants considerably. Conventional extended aeration activated sludge process is generally adopted for secondary treatment of municipal sewage. In the second article, "Monitoring the Removal of Pollutants in Municipal Sewage by Secondary Treatment at Kalpakkam Urban System", A Yudhistra Kumar and M Vikram Reddy have reported the percentage reduction of various contaminants present in municipal sewage at each phase of the sludge process. It was found that the reduction in pollutants at aeration tank and secondary clarifier showed considerable temporal variation across different seasons.

The oil refinery effluent development at Mathura and contiguous regions resulted in a great concern with reference to water pollution and soil contamination. Soil contamination with effluent showed undesirable physico-chemical and microbiological characteristics. In the third article, "Management of Oil Refinery Effluent Contaminated Soil Using Composted Rice Husk", Alok Bharadwaj and Ashok K Agarwal have studied the usage of rice husk, the naturally available organic material, in varying concentration dosages with the oil refinery effluent contaminated soil of Mathura to assess its efficacy in restoration of poor soil health status of such problem soil.

In the fourth article, "Interaction of Radio-Frequency and Microwave Radiation with the Human Body", Padmanabhan Krishnan has discussed the health hazard posed by the non-ionizing radio-frequency and microwave radiation to human body. Standards and safety regulations of the developed countries and the acceptable levels of exposure are outlined, along with some ground realities on the actual levels of exposure.

Pseudomonads are the best-known overproducing bacterial strains, capable of utilizing hydrocarbons as carbon and energy sources and producing rhamnolipid biosurfactants at a very high level. In the fifth article, "A Comparison of Production of Rhamnolipid Biosurfactant by Two Different Strains of Pseudomonas aeruginosa Using Various Economical Nutrient Sources", Ch Rajani, N Rambabu, V Himabindu and Y Anjaneyulu discuss the study conducted by them to develop economical methods for higher yield of rhamnolipid by suggesting the use of low-cost raw materials.

In the sixth article, "Railway Noise in a Residential Area: A Case Study", Chan Jia Wei, Wan Nor Azmin Sulaiman and Mohd. Armi Abu Samah present the findings of the case study on noise pollution conducted in Serdang Lama, Selangor, Malaysia. This study consists of acoustic measurement and social survey to determine the level of noise pollution experienced and its corresponding impact on the community exposed.

- G S Brahma
Consulting Editor