Copper filtered by trees

Spill Response Expo blog post 1

A new study from Indonesia has discovered that mangrove trees are filtering copper out of the country’s soil and water.

Grey mangrove trees, Avicennia marina, remove heavy metals from the surrounding soil and water - with their leaf litter found to accumulate the most copper, followed by the leaves and then roots.

The copper concentration in a mangrove forest in Tapak Tuguerjo - along the northern coast of Java, Indonesia, and downstream from a river polluted by a nearby factory - was analysed by researchers from Universitas Diponegoro.

Seawater samples from the study area showed copper concentrations to range from 0.02 mg/L to 0.05 mg/L; almost six times the 0.008 mg/L level permissible for marine biota set by the Indonesian Ministry of Envi-ronment.  

Samples of water, soil, roots, young leaves and fallen leaves were gathered by the team over a 12-week period, and after drying and grinding down the plant material, its copper content was analysed using atomic absorption spectroscopy.

They discovered that copper concentrations were up to ten times more in the plant material than in the water samples. The highest concentration was found in the leaf litter, followed by live leaves and then roots.

The results back up findings from several other studies and demonstrate the tree’s ability to defend itself against contaminated environments by releasing copper via its leaves - which mangroves are able to do better than many other plant species due to their adaptation to living in coastal zones, where the tree absorbs and eliminates salt in a similar fashion.

While copper is reintroduced back to the soil and water when the leaf litter breaks down, the researchers believe the impact is minimal; with the estimated amount released being less than three and a half percent of the total absorbed, and spread across a large area.