Organic amendment and plant growth improved aggregation in Cu/Pb-Zn tailings

Improving aggregation in base metal mine tailings is an important step in stimulating the formation of technosols for successful phytostabilization. The present study aimed at evaluating the effects of organic amendments and the growth of pioneer plant species on aggregation of Cu/Pb-Zn tailings under glasshouse conditions. The tailings were amended with sugarcane (Saccharum officinarum L.) residue (SR) and its compost (SC) at 5% (w/w), and were incubated with or without red flinders (Iseilema vaginiflorum Domin) growth in a pot-culture experiment for 40 d. The organic amendments mainly stimulated tailings microaggregation through organo-mineral interactions, due to increased aggregate-associated organic C (OC) contents. The plant colonization in the amended tailings further induced macroaggregation. Organic functional groups involved in the aggregation were identified as amine, carboxylic, and hydroxylic groups in the SR and SC. The SC contained higher levels of these groups than the SR, resulting in its greater effects on microaggregation. The addition of organic matters (OM) and plant colonization increased the contents of microbial biomass and poorly crystalline Fe in the rhizosphere, which were correlated well with the aggregate stability. As a result, both OMs containing functional groups and pioneer plant culture were found to stimulate aggregation and the development of technosols in Cu/Pb-Zn tailings