Effect of macro-and micro-plastics in soil on growth of Juvenile Lime Tree (Citrus aurantium)
Andrew Wirnkor Verla, Christian Ebere Enyoh, Isiuku Beniah Obinna, Evelyn Ngozi Verla, Wang Qingyue, Md. Akhter Hossain Chowdhury, Emmanuel Chinedu Enyoh, Tanzin Chowdhury
Abstract
Plastics in agricultural soils are of current concern to environmental scientist due to potential effects on soil-plant system and food security. In this study, the effect of macro- and micro- sized plastic types of low density polyethylene (LDPE), polypropylene (PP) and polystyrene (PS) in soil on growth of juvenile lime tree were studied using a pot experiment under ambient field conditions. To determine the effect, seven exposure patterns (single: LDPE, PP, PS and mixture: LDPE+PP, LDPE+PS, PP+PS, LDPE+PP+PS) in soil was tested. The results showed that macro- and micro- plastic residues affected the plant during vegetative growth with LDPE single exposure had the strongest negative effects (inhibition of 0.26%). However, LDPE+PP+PS had some positive effects by improving growth higher than the control. Overall, microplastics showed more negative effects than macroplastics, but the lime tree showed strong tolerance (with tolerance index > 70 %) to the different treatments. Without doubt, more research is urgently needed in order to fully understand the effect and mechanism of macroplastics and microplastics in soil-plant system. When understood remediation methods could be formulated to minimize the effects of plastics which are now ubiquitous in the environment.