Accumulation of plastic wastes and veterinary drug residue is posing a serious threat to the Kuttanad wetland ecosystem in the wake of the floods that inundated the region last month, with long-term consequences for human health, a study conducted by the Kerala State Pollution Control Board (KSPCB) and the Cochin University of Science and Technology (CUSAT) has revealed.
The post-flood field survey carried out by researchers from the School of Marine Sciences, CUSAT at 40 locations found that intense turbidity had affected the water quality in most of the rivers including the Pampa, Manimala, Achencoil, Meeenachil, Periyar and Muvattupuzha.
“We recorded very high levels of faecal contamination and high soil acidity at many locations”, says Bijoy Nandan, Professor and Head, Department of Marine Biology, CUSAT who led the study.
Rise in BOD level
The research team noted a spike in the Biochemical Oxygen Demand (BOD) of water and a decline in the dissolved oxygen level, indicating heavy organic pollution and high stress on aquatic organisms. In some locations, the BOD levels were observed to be almost double the acceptable count for fresh water. The high turbidity of water was found to have affected phytoplankton productivity with a possible impact on aquatic biodiversity and fisheries. “What is especially worrying is the presence of microplastics, veterinary drugs and heavy metals, all of which could enter the food chain with deleterious long- term impact on human health,” says Dr. Nandan. While the metals and drugs bind to the soil and later enter the food chain through plants, microplastics are known to be ingested by fish and other aquatic organisms which are in turn consumed by humans.
Microplastics
In the wake of the floods, the team recovered more than 300 pieces of plastic waste from a 200 sq m plot in Kuttanad, indicating the extent of pollution and the gravity of the threat faced by ecosystem. Microplastic is the term used for tiny pieces of plastic that are accidentally eaten by fish.
“Our tests indicate an increase in the veterinary drug residue in the areas that were flooded. The presence of heavy metals like copper, zinc, lead and cadmium was also found to be high,” said Dr. Nandan.
The CUSAT team which has been surveying the Kuttanad-Vembanad wetland area in association with KSPCB over the last two years had recorded the presence of pharmaceuticals like Benzyl benzoate, Benzenepropanoic acid, Cyclic octatomic sulphur, Phenyl compounds and paracetamol derivatives in water sources. “Human and veterinary drugs end up in the environment through manufacturing waste, human or animal excretion, runoff from animal feeding operations or leaching from landfills,” explains Dr. Nandan. “They bind to the soil, adding toxicity to vegetation and crops and affecting the ecosystem”.
K.Sajeevan, KSPCB chairman, told The Hindu that the report would be submitted to the Environment Department with recommendations for further studies.
