Use of nanoparticle-coated bacteria for the bioremediation of organic pollution: A mini review.

Nanoparticle (NP)-coated (immobilized) bacteria are an effective method for treating environmental pollution due to their multifarious benefits. This review collates a vast amount of existing literature on organic pollution treatment using NP-coated bacteria. We discuss the features of bacteria, NPs, and decoration techniques of NP-bacteria assemblies, with special attention given to the surface modification of NPs and connection mechanisms between NPs and cells. Furthermore, the performance of NP-coated bacteria was examined. We summarize the factors that affect bioremediation efficiency using coated bacteria, including pH, temperature, and agitation, and the possible mechanisms involving them are proposed. From future perspectives, suitable surface modification of NPs and wide application in real practice will make the NP-coated bacterial technology a viable treatment strategy.

Combined effects of vehicles and waste incineration on urban air halogenated and parent polycyclic aromatic hydrocarbons.

Traffic emissions and waste incineration are the main sources of PAHs in urban atmosphere, but their spatially superimposed effects are currently unclear. This study assessed the spatial distribution of PAHs and HPAHs concentrations in the atmosphere of Shenzhen by simulating the spatial and temporal dispersion of PAHs and HPAHs emissions from on-road vehicles and municipal solid waste incinerators (MSWIs). Generally, the concentrations of PAHs and HPAHs were higher on workdays than on weekends due to higher traffic volumes, while the prevailing wind direction of the northeast could cause more widespread dispersion of PAHs and HPAHs within Shenzhen's atmosphere. After superimposing the spatial distribution of pollutants emitted by vehicles and MSWIs, PAHs within 1000 m downwind of MSWIs are mainly contributed by MSWIs and beyond 1000 m by vehicles. The cancer risk values induced by exposure to PAHs and HPAHs via inhalation in Shenzhen were below the acceptable risk level for males and females in each age group, while adults faced the highest cancer risk, followed by adolescents and children. However, spatially, the cancer risk values were above the priority risk level for adult males in localized high-traffic areas in Futian and Luohu districts.

Photodegradation of phthalic acid esters under simulated sunlight: Mechanism, kinetics, and toxicity change.

The photodegradation of two phthalic acid esters (PAEs), dimethyl phthalate (DMP) and di-n-octyl phthalate (DOP), under simulated sunlight in aqueous or organic phases (n-hexane (HEX) and dichloromethane (DCM)) was investigated. The mean photodegradation rates were ranked by half-lives as follows: DOP in DCM (3.77 h) < DMP in DCM (9.62 h) < DOP in H2O (3.99 days) < DMP in H2O (19.2 days) < DOP in HEX (21.0 days) < DMP in HEX (>30 days). Compound-specific stable isotope analysis (CSIA) combined with intermediate analysis was employed to explore the involved initial photoreaction mechanism. C-O bond cleavage, chlorine radical adduction to the aromatic ring, competing reactions of chlorine radical adduction to the aromatic ring and side chain, and a singlet oxygen-mediated pathway were mainly responsible for initial photodegradation mechanism of PAEs in H2O, DMP in DCM, DOP in DCM, and DOP in HEX, respectively. Furthermore, distinct isotope fractionation patterns of PAEs photodegradation open the possibility of using CSIA to differentiate the involved solvents in the field. More toxic and recalcitrant intermediates emerged during the photodegradation of DMP in DCM, while the risk to human health was reduced during the photochemical transformation of DOP in organic solvents.

Anthropogenic influences in a rapidly urbanizing area using linear alkylbenzenes and polycyclic aromatic hydrocarbons as tracers.

Environmental molecular markers can be used to understand the sources, transport, and fate of pollutants. Furthermore, they can also be applied to assess the influences of anthropogenic activities and elucidate urbanization from different perspectives. In this study, the potential of linear alkylbenzenes (LABs) and polycyclic aromatic hydrocarbons (PAHs) as chemical indicators of urbanization was examined first. Overall, the concentrations of LABs and PAHs ranged from 5.49-148 ng/g (mean: 15.6, median: 9.33) and 3.61-4878 ng/g (mean: 181, median: 71.3), respectively. Owing to the different sources and input methods of these two substances in soil, the area-weighted median values for LABs were more suitable to assess the magnitude of contamination on the administrative scale. For PAHs, the average values were more practical. LAB (consumption-induced pollutants) and PAH (production-induced pollutants) concentrations exhibited good correlations with some indices for residential daily life and industrialization, which indicated that soil can be utilized to reveal multidimensional urbanization-environment relationships. Two different patterns, the inverted U-shaped pattern and the upward pattern, were employed to simulate the environment-urbanization relationships in Shenzhen, China, which indicated that raising the standard of living or industrialization had created different soil pollution. The environmental quality demand was more difficult to meet by changing the energy structure than by improving infrastructure.