Unscientific disposal of sewage and pesticide residue from farmlands have contributed to organic pollution and chemical contamination of surface and groundwater resources in four river basins across the State, namely Valapattanam in Kannur, Kallada in Kollam, Keecheri-Puzhakkal in Thrissur, and Chandragiri in Kasaragod district.
An environmental monitoring programme on water quality conducted by the Kerala State Council for Science, Technology and Environment (KSCSTE) revealed that water pollution was higher in downstream areas due to anthropogenic activities. Chief Minister Oommen Chandy released the report of the study here on Wednesday.
The programme seeks to create a database on water quality and use the derived information for the management of water resources and their utilisation. A team of scientists led by P.S. Harikumar, Head, Chemical Sciences Division, Centre for Water Resources Development and Management (CWRDM), analysed surface and ground water samples to assess water quality.
The report noted that almost all sampling stations in the Valapattanam river basin had higher index for total coliform and faecal coliform. All the surface water samples were found to be contaminated with E.Coli during the monsoon while 21 per cent of them showed the presence of E.Coli during the pre-monsoon season and 53 per cent in the post-monsoon period.
Residues of pesticides
Residues of the pesticides endosulfan, aldrin, and dieldrin were detected in samples collected from five locations. Ground water samples indicated high total coliform and faecal coliform bacteria count. E.coli was detected in samples collected from five locations.
Biological analysis of water showed the impact of agrochemicals at select locations while organic content was high near townships.
Kallada river basin
Analysis of surface water samples from the Kallada river basin revealed the presence of aldrin and dieldrin. Maximum microbial contamination was reported during the pre-monsoon season. The study showed that 92 per cent of water samples had marginal quality and eight per cent had poor quality. All the ground water samples were found bacteriologically contaminated during the pre-monsoon season. The report said sewage effluents and agricultural activities downstream had stressed the local biological communities in the river basin.
Pesticide results of the Keecheri river basin revealed the presence of aldrin and endosulfan at three locations. Maximum microbial contamination was reported from the Puzhakkal river. Maximum bacteriological pollution was reported in the Keecheri river during the post-monsoon period. Sediment samples collected from the Keecheri-Puzhakkal basin were polluted with heavy metals.
Aquatic life under stress
Aquatic life was found to face greater stress in the downstream areas and discharge sites. Agrochemical residues also had an impact on the water quality.
In the Chandragiri, pesticide analysis of surface water samples indicated the presence of aldrin and endosulfan.
All the samples were contaminated with E.Coli during the pre-monsoon and post-monsoon seasons and with total coliform and faecal coliform in the monsoon. Ground water samples also showed high level of bacteriological contamination.
Source:The Hindu 7 June 2013