International Day of Action for Rivers – Antlers detect lead pollution

Today is the International Day of Action for Rivers! In Europe, many rivers suffer from pollution, whether through chemicals, nutrients or plastics. A big culprit is the mining industry, which contaminates water bodies with heavy metals used in processing activities. In the Harz Mountains of Northern Germany for example, historical industrial activity is still affecting the Innerste River even though the last mining took place in 1992. Heavy metals accumulate in floodplains through flooding events, so their ecosystems are at high risk of exposure. By contaminating the water and soil, the chemicals can easily find their way into organisms. Heavy metals such as lead can be lethal or at least have serious effects on health, ranging from infertility to brain damage.

A new technique to monitor river pollution

Researchers from the University of Hildesheim collected antlers from roe deer culled around the Innerste River. The antlers can accumulate a lot of lead and therefore act as a natural measuring unit for pollution in the area. The animals were likely exposed to the metal from consuming plants and soil along the river. Antlers from deer that foraged around the floodplain still contained high lead levels, despite the fact that the last mining activity in the Harz was in 1992. Further tests concluded that the lead came from ore extraction sites in the Harz Mountains. In comparison, lead concentrations of antlers found in areas not exposed to flooding have been declining for decades. This indicates that floodplain ecosystems are more vulnerable to heavy metal pollution.

How to protect floodplain ecosystems

As a result of climate change, heavy rainfall and flooding are becoming more frequent. This means that even metal from old mines can find its way into floodplain ecosystems. So mitigating the effects of climate change by burning fewer fossil fuels is the best long-term solution for reducing river pollution by metals.

There are also ways to remove metal contaminants from waterways, such as stabilising metals in the soil. Certain chemicals can be added to the soil which react with the metal to form less toxic minerals. This contains the metal in a form where it cannot be absorbed by organisms. Another solution is growing more plants onsite. They can reduce soil erosion and stop contaminants from leaking into waterways. In addition, plants such as alfalfa or juniper can concentrate lead in their tissues and “suck” it out of the environment. Of course, there is a danger of animals eating the toxic plants, so proper disposal is necessary for this to be an effective management strategy.

Of course, metal pollution is only one of several problems rivers in Europe face today. Conserving wetlands on a large scale is therefore vital. This year, the European Wilderness Society is participating in the brand new ALFAwetlands project. This is a HORIZON project aimed at restoring wetlands across Europe and increasing their ability to sequester carbon. If you would like to support this work, you can donate below!

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