Linking bioavailability and toxicity changes of complex chemicals mixture to support decision making for remediation endpoint of contaminated soils

Abstract

A six-month laboratory scale study was carried out to investigate the effect of biochar and compost amendments on complex chemical mixtures of tar, heavy metals and metalloids in two genuine contaminated soils. An integrated approach, where organic and inorganic contaminants bioavailability and distribution changes, along with a range of microbiological indicators and ecotoxicological bioassays, was used to provide multiple lines of evidence to support the risk characterisation and assess the remediation end-point. Both compost and biochar amendment (p = 0.005) as well as incubation time (p = 0.001) significantly affected the total and bioavailable concentrations of the total petroleum hydrocarbons (TPH) in the two soils. Specifically, TPH concentration decreased by 46% and 30% in Soil 1 and Soil 2 amended with compost. These decreases were accompanied by a reduction of 78% (Soil 1) and 6 % (Soil 2) of the bioavailable hydrocarbons and the most significant decrease was observed for the medium to long chain aliphatic compounds (EC16-35) and medium molecular weight aromatic compounds (EC16-21). Compost amendment enhanced the degradation of both the aliphatic and aromatic fractions in the two soils, while biochar contributed to lock the hydrocarbons in the contaminated soils. Neither compost nor biochar affected the distribution and behaviour of the heavy metals (HM) and metalloids in the different soil phases, suggesting that the co-presence of heavy metals and metalloids posed a low risk. Strong negative correlations were observed between the bioavailable hydrocarbon fractions and the ecotoxicological assays suggesting that when bioavailable concentrations decreased, the toxicity also

Exploring the effect of composting technologies on the recovery of hydrocarbon contaminated soil post chemical oxidative treatment

“…Composting has been a successful bioremediation strategy in soils contaminated with PAHs, as well as with other pollutants, by providing organic substrates that stimulate the growth of potential microbial degraders and enhancing soil properties and quality (Antízar-Ladislao et al, 2006;Scelza et al, 2008;Covino et al, 2016;Jednak et al, 2017;Cipullo et al, 2019;Liu et al, 2019). However, few studies have considered composting or the addition of organic matter amendments to stimulate the microbial soil community, as a bioremediation strategy applied after the oxidative step (Satapanajaru et al, 2017).…”

Characterization and Physicochemical Properties of Wood Sawdust in Niger Area, Nigeria

“…From the result presented in Table 2 revealed that iroko is more acidic than other and the magnitude order of acidicity is D > A > C > B. The results of present study revealed that the characterization and examination of physicochemical properties of functional components that control is helpful in monitoring, predicting and determination quality of respected area Cipullo et al, 2019;Frick et al, 2019;He et al, 2019;Kalhor et al, 2019;López-Vizcaíno et al, 2019;Mobbs et al, 2019;Rocha et al, 2019;Sivagami et al, 2019;Song et al, 2019;Ye et al, 2019), for the improvement of unwanted condition of contaminant in soil environment.…”

Recent advances in biochar engineering for soil contaminated with complex chemical mixtures: Remediation strategies and future perspectives

“…A similar trend is also observed in many other studies which employ total concentration of contaminants for risk assessment and management of contaminated land, as well as exposure risks. Total concentration does not address partitioning and associated toxicological effects of the partitioned fractions, such as the bioavailable fraction, and therefore can be misleading in terms of risk assessment and contaminant management (Cipullo et al, 2019). Table 2 below shows some main advantages and advantages of using biochar, hydrogel, digestate and bioaugmentation for remediation purposes.…”