River is a 'chemical cocktail'

A study showed contamination from heavy metals, pharmaceuticals and banned pesticides

- Sheree Bega

Every drop of river water tells a story about the kinds of medicine we take, the chemicals we use and the lifestyle choices we make, says scientist Shaskia John and it's not just about nature.

"What we consume, we excrete and the wastewater plants will reflect that ... Our rivers are lifestyle markers," John, an aquatic ecologist, told the Mail & Guardian on the sidelines of the recent Oppenheimer Research Conference where she presented on legacy and emerging contaminants in the Crocodile River catchment.

Now in its 14th year, the conference brought together researchers, policymakers and conservation leaders to advance African-led solutions to the biodiversity and climate crisis.

John examined seasonal shifts in water quality, testing chemical loads in surface water and fish muscle tissue. She screened for 22 metals, 274 pesticides and 21 pharmaceuticals — uncovering alarming levels in the ecologically critical river catchment.

"Rivers are the veins of ecosystems. They sustain livelihoods, they sustain biodiversity - but the Crocodile River catchment is slowly becoming a chemical cocktail."

The Crocodile River rises near Dullstroom, flows through the Nelspruit industrial area, feeds the Lowveld's farms and winds through the Kruger National Park to Mozambique.

"The agricultural, industrial and urban areas bring in chemicals, pharmaceuticals and pesticides as well as fertilisers into the river."

The river is ecologically important as it supports two key zones in its lower portion — the Krokodilpoort Nature Reserve and forms the southern border of the Kruger National Park — while sustaining farms, industries and expanding towns.

"It's one of the most used rivers in South Africa. It's a transboundary river," John added. "That means we have an international obligation to maintain certain water standards because the water supports communities and ecosystems downstream."