Thursday, February 05, 2009

Contaminant cocktail toxic to frogs

This study involves testing 5 different herbicides and 5 different insecticides on frogs and tadpoles. Not surprisingly, while a single "cide" may not elicit any negative response, a mixture of "cides" can cause massive damage. All 10 of them applied together is especially deadly.

The point to ponder is many of our water standards (drinking water, effluent discharge, stream water) are based on concentration of a single component e.g. heavy metal, pesticide. Little is studied on the effects of mixtures. The water quality is technically sound if the concentration of every component is below the allowable limit. However, a combination of chemicals can involve synergistic effects which can make the water harmful even though it is legally "safe".

Projecting the future of nitrogen pollution

The effects of climate change are global. Expect to see the same thing happening here since some of our water bodies are already overgrown by algae stimulated by high nitrogen levels in water.

via ES&T Online News on 2/4/09

Heavier rainfall in the years to come coupled with the application of increasing amounts of fertilizer to farmlands could bump up nitrogen levels in rivers by as much as 24%, according to a new study.

Figure: "Green water" at Rochor Canal. The colour comes from algae likely caused by the high nutrient load in the water.

Europe’s clean and contaminated rivers

Not surprisingly, like USA, Europe also has persistent organic chemicals in its rivers. These include pharmaceuticals and personal care products. The cleanest rivers were found in relatively unpopulated areas.

It makes one wonder what will turn up in our own rivers and streams if a similar study were to be done. Unfortunately, no such study was performed so far and if there was, the results were not publicised.

via ES&T Online News on 2/4/09

A new survey documents levels of persistent organic pollutants among other compounds such as caffeine and drugs in European surface waters.