A novel technology of solarization and phytoremediation enhanced with biosurfactant for the sustainable treatment of PAH‑contaminated soil

Hydrocarbon-contaminated land has been a significant issue throughout Nigeria’s Niger Delta since the discovery of crude oil in 1956. This paper proposes a novel and sustainable technique involving soil solarization, phytoremediation and biosurfactant to treat polycyclic aromatic hydrocarbon (PAH) contamination. The treatment effect on PAH reduction, plant growth, rhizosphere microorganisms and their enzymatic activities were evaluated. Twenty-eight days of solarization was carried out before the introduction of Chromolaena odorata seedlings for an 84-day phytoremediation period using a 4 x 4 (vegetated) and 2 x 4 (non-vegetated) cell microcosms to simulate the Niger Delta’s sub-tropical conditions. Soil solarization resulted in significant PAH reduction (p≤0.01) of phenanthrene, fluoranthene and benzo(a)pyrene with means reduction of 60.0 %, 38.7 % and 36.1 % compared to their non-solarized counterparts with 18.0 %, 18.0 % and 18.8 % at 95 % CI (32.7, 51.3), (15.4, 26.1) and (8.0, 26.6) respectively. In post-solarization, all solarized and vegetated treatment groups significantly reduced (p≤0.01) PAHs compared to their respective counterparts, whilst biosurfactant contribution in this combination was negligible (p≥0.05). The growth parameters of C. odorata, total soil/rhizosphere heterotrophic microorganisms and their enzymatic activities of dehydrogenase and urease increased in all solarized treatments indicating essential biochemical processes. The novel and successful integration of soil solarization and phytoremediation using indigenous C. odorata as a combined technique to treat even the most recalcitrant form of hydrocarbons (PAHs) brings up new opportunities for a sustainable method of cleaning up contaminated land in Nigeria's oil-rich Niger Delta

Editorial: Microbial communities and functions contribute to plant performance under various stresses

Editorial on the Research Topic - Microbial communities and functions contribute to plant performance under various stresse

Combining phytoremediation with bioenergy production: developing a multi‑criteria decision matrix for plant species selection

The use of plants to extract metal contaminants from soils has been proposed as a cost-effective means of remediation, and utilizing energy crops for this phytoextraction process is a useful way of attaining added value from the process. To simultaneously attain both these objectives successfully, selection of an appropriate plant species is crucial to satisfy a number of important criteria including translocation index, metal and drought tolerance, fast growth rate, high lignocellulosic content, good biomass production, adequate calorific value, second generation attribute, and a good rooting system. In this study, we proposed a multi-criteria decision analysis (MCDA) to aid decision-making on plant species based on information generated from a systematic review survey. Eight species Helianthus annuus (sunflower), Brassica juncea (Indian mustard), Glycine max (soybean), Salix spp. (willow), Populus spp. (poplar), Panicum virgatum (switchgrass), Typha latifolia (cattails), and Miscanthus sinensis (silvergrass) were examined based on the amount of hits on a number of scientific search databases. The data was normalized by estimating their min–max values and their suitability. These criteria/indicators were weighted based on stipulated research objectives/priorities to form the basis of a final overall utility scoring. Using the MCDA, sunflower and silvergrass emerged as the top two candidates for both phytoremediation and bioenergy production. The multi-criteria matrix scores assist the process of making decisions because they compile plant species options quantitatively for all relevant criteria and key performance indicators (KPIs) and its weighing process helps incorporate stakeholder priorities to the selection process

Risk assessment at an informal e-waste recycling site in Lagos state, Nigeria

E-waste is referred to obsolete, broken electronic devices such as mobile phones, televisions, computer monitors, laptops, printers, scanners, and associated wiring (Luther, 2010). E-waste is generated in large quantities (Tang et al., 2010); the composition of the waste creates a major problem. E-waste contains more than 1000 different substances, many of which are toxic metals and organic pollutants (Robinson, 2009). These include lead and cadmium in circuit boards; lead oxide and cadmium in monitor cathode ray tubes (CRTs); mercury in switches and flat screen monitors; cadmium in computer batteries; polychlorinated biphenyls (PCBs) in older capacitors and transformers; and brominated flame retardants on printed circuit boards, plastic casings, cables and polyvinyl chloride (PVC) cable insulation that release highly toxic dioxins and furans when burned to retrieve copper from the wires (BAN, 2002). Also, polybrominated diphenyl ethers (PBDEs) are used as brominated flame retardants in electronic circuit boards (Wang et al., 2005). Activities carried out in the site of interest include dismantling of the different electronic waste, sorting out of various parts and burning of wires and other parts to get valuable metals.The complex composition of e-waste may pose a threat to the environment and human health if they are not disposed correctly

Chemistry and the environment

A report on three symposia in the ‘Energy, Water and Environmental Science’ programme at the International Union of Pure and Applied Chemistry (IUPAC) 46th World Chemistry Congress (in Sao Paulo, Brazil, 9-14 July, 2017). The symposia presented the latest advances concerning the environmental impact of emerging technologies and the fate of pollutants in the environment