Evaluation of Cu-toxicity in agricultural topsoil contaminated by different sources in central Chile

Abstract

Abstract The primary fruit production zone in Chile lies in the lowland areas of the central region, which has a history of soil copper pollution due to both copper mining (in the highlands) and the use of copper-based pesticides in agriculture. This study assessed the phytotoxic effect of copper in agricultural topsoil contaminated by different sources in the region. A total of 13 agricultural sites, including polluted soils and a background unpolluted soil, were sampled, and a toxicity bioassay was conducted using Lolium perenne. Multiple linear regression models revealed that copper has a significant negative impact on plant growth, whereas soluble zinc, organic matter, available nitrogen, and clay have positive effects and mitigate copper toxicity (p < 0.001). The effective concentration at 50% (EC50) of the total soil copper was 1030 mg kg− 1 for shoot length and 1084 mg kg− 1 for shoot dry mass. These results correspond with the EC50 values reported in previous studies that also used real-world contaminated soils. Moreover, the findings are noteworthy as only six studies have estimated copper toxicity thresholds for plants grown in contaminated soils. Overall, the results highlight the complex nature of copper toxicity in plants grown in soils contaminated by different sources and underscore the importance of considering multiple factors when assessing the impact of contaminants on plant growth in soils contaminated by various metals besides copper.