Vertical distribution of copper in copper-contaminated coffee fields in Kilimanjaro, Tanzania

Taylor & FrancisSoils in coffee farms may be contaminated with copper (Cu) due to intensive and long-term use of Cu-based fungicides. This legacy of Cu contamination may pose risks for contaminating lower soil layers and underground water, or contamination of food crops cultivated on these soils. High concentrations of Cu, strongly exceeding international standard levels, were found within the top 30 cm of affected soils. There was only a limited mobility of Cu below 30 cm layers, suggesting a low risk of contaminating lower soil layers. The Cu mobility in fallow soils was more limited than in tilled soils. There was a positive correlation between silt content and the concentrations of Cu. Potentially mobile Cu fractions, which decreased with soil depth, were greater in contaminated soils than in uncontaminated soils and were greater in top layers than in lower layers, implicating greater Cu availability and consequently higher toxicity risks.Taylor & Franci