In the last two decades bioremediation technologies have become ever more important as a sustainable alternative to traditional remediation techniques. In particular, there has been an increasing attention on rhizoremediation techniques, employing plant roots and their associated microorganisms to enhance the degradation of organic contaminants in soil. Many short-term laboratory/greenhouse experiments and long-term field trials have been conducted to investigate the most suitable plant species and environmental conditions that stimulate and favour microbial activities in the degradation of Polychlorinated Biphenyls (PCBs). Recently, an attempt to extrapolate rhizoremediation half-lives (rhizo-HLs) for the ten PCB families from these studies has been made (Terzaghi et al., 2018) providing important data for multimedia fate models that aim to predict the time needed to achieve regulatory thresholds in a PCB contaminated site where rhizoremediation techniques are applied and therefore to draw up its remediation plan. However, many of the studies available in the literature (more than the 80%) were not correctly set up to allow the calculation of PCB rhizo-HLs and could not be considered. In particular the main pitfalls in the experimental design referred to the type of chemicals (single congeners vs. mixture), contamination (spiked vs. aged) and experiment (greenhouse vs. field), the experimental time, the set-up of appropriate controls and replicates as well as the analytical and microbiological techniques adopted. The present work aims to 1) list and discuss the main pitfalls in the experimental design of previous and current rhizoremediation experiments and 2) propose guidance to perform appropriate experiments to obtain comparable, accurate and useful data for rhizo-HLs calculation. Moreover rhizo-HLs will be presented and compared with those obtained with other approaches.
Are PCB half-lives obtained in rhizoremedition experiments reliable? Pitfalls in experimental design and suggested guidelines for conducting the experiments
E. Terzaghi;E. Zanardini;C. Morosini;G. Raspa;A. Di Guardo
2018-01-01
Abstract
In the last two decades bioremediation technologies have become ever more important as a sustainable alternative to traditional remediation techniques. In particular, there has been an increasing attention on rhizoremediation techniques, employing plant roots and their associated microorganisms to enhance the degradation of organic contaminants in soil. Many short-term laboratory/greenhouse experiments and long-term field trials have been conducted to investigate the most suitable plant species and environmental conditions that stimulate and favour microbial activities in the degradation of Polychlorinated Biphenyls (PCBs). Recently, an attempt to extrapolate rhizoremediation half-lives (rhizo-HLs) for the ten PCB families from these studies has been made (Terzaghi et al., 2018) providing important data for multimedia fate models that aim to predict the time needed to achieve regulatory thresholds in a PCB contaminated site where rhizoremediation techniques are applied and therefore to draw up its remediation plan. However, many of the studies available in the literature (more than the 80%) were not correctly set up to allow the calculation of PCB rhizo-HLs and could not be considered. In particular the main pitfalls in the experimental design referred to the type of chemicals (single congeners vs. mixture), contamination (spiked vs. aged) and experiment (greenhouse vs. field), the experimental time, the set-up of appropriate controls and replicates as well as the analytical and microbiological techniques adopted. The present work aims to 1) list and discuss the main pitfalls in the experimental design of previous and current rhizoremediation experiments and 2) propose guidance to perform appropriate experiments to obtain comparable, accurate and useful data for rhizo-HLs calculation. Moreover rhizo-HLs will be presented and compared with those obtained with other approaches.
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
