Microbial communication during bioremediation of polyaromatic hydrocarbons

Human activity pollution has been shown to harm the environment,ecology,and health impacts.The polycyclic aromatic hydrocarbons(PAHs)produced by the industries such as tannery,distillery,pulp paper,and oil refineries are a major source of contaminant.PAHs are found all across the world,owing to long-term human pollution sources.PAHs'physico-chemical features,such as hydrophobicity and electrochemical stability,contribute to their environmental persistence and contribute to their carcinogenic and health effects.Numerous analytical and biological techniques for the qualitative and quantitative assessment of PAHs have been proposed.Bioaccumulation,adsorption,chemical oxidation,photolysis,volatilization,and microbiological degradation are the principal breakdown pathways of PAHs in the environment.Microbial populations,such as bacteria,fungi,and algae,play a crucial role in the biological elimination of PAHs.Oxidase,manganese peroxidases,lipases,and laccases are the enzymes involved in PAHs breakdown.The synthesis of surfactants by bacteria increases PAHs bioavailability and improves the elimination process of PAHs.Temperature,pH,aeration,moisture content,nutrition availability,absence of hazardous chemicals,and the kind and number of degrading microbial populations are all factors that influence PAHs decomposition.Microbial degradation mechanisms result in intermediate metabolites and carbon dioxide mineralization.The elimination of PAHs is improved by molecular approaches such as gene engineering and protein engineering.This review discussed the benefits of bioremediation strategies that were investigated for precise evaluation and were trusted at both the regulatory and scientific studies levels.

Molecular distribution and seasonal variation of hydrocarbons in PM_(2.5) from Beijing during 2006

Normal （n）-alkanes and polycyclic aromatic hydrocarbons （PAHs） in PM2.5 were collected from Beijing in 2006 and analyzed using a thermal desorption-GC/MS technique. Annual average concentrations of n-alkanes and PAHs were 282 ±96 and 125 ± 150ng/m^3, respectively： both were highest in winter and lowest in summer. C19-C25 compounds dominated the n-alkanes while benzo[b]fluoranthene, benzo[e]pyrene, and phenanthrene were the most abundant PAHs. The n-alkanes exhibited moderate correlations with organic carbon （OC） and elemental carbon （EC） throughout the year, but the relation- ships between the PAHs, OC and EC differed between the heating and non-heating seasons. The health risks associated with PAHs in winter were more than 40 times those in spring and summer even though the PM2.5 loadings were comparable. Carbon preference index values （〈1.5） indicated that the n-alkanes were mostly from fossil fuel combustion. The ratios of indeno[123-cd]pyrene to benzo[ghi]pyrelene in summer and spring were 0.58 ± 0.12 and 0.63 ± 0.09, respectively, suggesting that the PAHs mainly originated from motor vehicles, but higher ratios in winter reflected an increased infuence from coal, which is extensively burned for domestic heating. A comprehensive comparison showed that PAH pollution in Beijing has decreased in the past 10 years.