Chemicals in environment toxic for aquatic life

According to researchers from Baylor University, dry conditions adversely affect the water quality, making some chemicals, like some pesticides more toxic and likelier to get accumulated in the fish.

Last Updated: Jun 29, 2011, 19:43 PM IST

Washington: A latest study has shown that drought conditions make some chemicals in the environment more toxic to fish and other aquatic life by intensifying the magnitude of the natural pH shifts in the water.

According to researchers from Baylor University, dry conditions adversely affect the water quality, making some chemicals, like some pesticides more toxic and likelier to get accumulated in the fish.

The study holds significance, as more than 75 pc of the essential drugs described by the World Health Organization and nearly one-third of modern pesticides have ionizable groups of compounds.

These ‘weak base’ compounds when dispersed in the environment can become more toxic to fish when surface pH levels are high, according to the scientists.

The researchers collected samples from 23 streams across the southern U.S. at different times over the course of two years and measured how ecosystem production and respiration, dissolved oxygen content, the amount of phosphorus and nitrogen and pH level changed over the course of a day.

It emerged that in the driest year on record, the fluctuations of the water``s pH level was extreme and coincided with increased toxicity to aquatic life.

“Future water scarcity associated with global climate change and altered precipitation patterns may profoundly impact in-stream flows in semiarid regions, which have direct implications for water resource management,” said Dr. Ted Valenti, a former Baylor doctoral student.

“Predicting the cumulative effects of climatic variability on the risk of contaminants may require a significant shift in the environmental assessment and management approaches for freshwater systems,” he added.

The study appear on-line in the journal Integrated Environmental Assessment and Management.

ANI