Toxicity levels of heavy metals are well within permissible limits, according to new study

  • Results of 18-month, Rs.1.6 crore research project
  • Silt formation has reduced lake spread, depth
  • The lake's 14 island-villages vulnerable to marooning
  • `Catch per unit effort' of fish, prawns, crabs down

    Chennai: A water body that bore the brunt of industrial pollution a decade ago, the Pulicat lake, north of Chennai, has today made an ecological turnaround, recording toxicity levels well within permissible limits.

    The change has been documented by an 18-month research study, `Community-Based Disaster Preparedness, Vulnerability Studies and Enhancement of Sustainable Livelihood for the inhabitants of Pazhaverkadu (Pulicat),' by Loyola College and the Pazhaverkadu Action Network (PAN), in partnership with CORDAID (Catholic Organisation for Relief and Development Aid - The Netherlands, which concluded last month.

    The Rs. 1.6 crore-project was aimed at creating disaster preparedness for the 28 villages in Pulicat through scientific research and collation of data on bio-diversity and the population profile.

    S. Vincent, Reader, Department of Zoology, Loyola College, said that the bio-diversity survey collected details on pH levels (a measure of acidity/alkalinity), salinity, temperature conductivity, dissolved oxygen and toxicity and plankton organisms.

    "We anticipated that the lake would record negative parameters, but the results were much better than we imagined. This reflects the higher awareness among the neighbouring industries in checking pollution levels," he said.

    Water samples collected from 24 stations at three levels in the lake over seven to eight times were tested, and the quality levels were found to be constant.

    The levels of important heavy metals including magnesium, lead, zinc, nickel, cadmium, aluminium and copper and chemicals such as ammonia, sulphate and fluoride were well within permissible levels.

    M. Selvanayagam, Director, Loyola Institute of Frontier Energy, said due to silt formation the 450 sq. km area of the historic lake has now been reduced to 356 sq. km and the original depth of four metres has reduced to one to 1.5 metres.

    Following the increase in number of fishing boats after the tsunami, the `Catch Per Unit Effort' of fish, prawns and crabs has declined from 1000 tonnes to around 700 tonnes. "A hydrological study should be done to scientifically deepen the lake," he said.

    He pointed out if the water-holding capacity was reduced, it would directly affect the algal growth, which in turns reduces the food for fish and other organisms.

    The five-member team recommended that the Government take immediate steps to construct a bridge connecting the islands to the mainland. "The 14 island-villages are vulnerable to marooning in the event of a cyclonic flood," L. Selvanathan, senior lecturer in the History department said.

    He undertook the socio-cultural aspects of research along with M. Arulraj Senior Lecturer, Social Work.

    Vulnerability data

    The vulnerability data from the population profile says the greatest number of children from zero to six years is at Annamalaichery, which along with Santhankuppam, also houses the most number of children between six to 14 years, widows and pregnant women.

    The highest number of handicapped persons was in Kulathumedu.