[Remediation of Three Oxidants on Polycyclic Aromatic Hydrocarbons in Coking Contaminated Soil and Its Response to Indigenous Microorganisms].

To explore the influences of chemical oxidation on the physiological and ecological functions of indigenous microorganisms during contaminated soil remediation, three oxidants, including KMnO4, Na2S2O8, and O3, were selected to investigate their remediation effects on PAHs and the responses to indigenous microorganisms under different liquid-solid ratios, in this study. The results showed that:when the ΣPAHs concentration was 679.1 mg·kg-1 and the dosage of KMnO4 and Na2S2O8 was 1%, the removal efficiency of ΣPAHs reached up to 96.9% and 95.7% under the liquid-solid ratio of 6:1; for the O3 treatment, the removal efficiency of ΣPAHs was the highest(82.3%) at the O3 dosage and the liquid-solid ratio of 72 mg·min-1 and 8:1, respectively. The removal efficiency of low ring(3-4 rings) PAHs was higher than that of high ring(5-6 rings) PAHs under different liquid-solid ratios. The highest removal efficiencies were observed for phenanthrene and acenaphthene, whereas for benzo[a]pyrene, only the KMnO4treatment provided an effective performance, showing the highest removal efficiency of 97.4%. The microbial quantity analysis indicated that the quantity of soil microorganisms in the soil dropped sharply after being treated with KMnO4, decreasing from 108 copies·g-1 to 105 copies·g-1, whereas it changed only slightly after being treated with Na2S2O8 and O3. The community structure analysis showed that Proteobacteria were predominant in the contaminated soil, with the relative abundance of 99.5%. The addition of KMnO4 and Na2S2O8 significantly increased the microbial diversity; in particular, the relative abundance of a variety of microorganisms(such as Ralstonia and Acinetobacter) that can degrade PAHs was remarkably increased. The analysis of microbial metabolic function pathways revealed that chemical oxidation could simultaneously increase the relative abundance of PAHs-degrading bacteria and improve the ability of organic metabolism. Overall, the KMnO4 treatment greatly altered the quantity of microorganisms and the structure of the microbial community and the relative abundance of PAHs-degrading microorganisms at the liquid-solid ratio of 6:1.

[Spatial Distribution of Perfluoroalkyl Acids and Transformation of Their Precursors in River Water Samples and Effluents of Wastewater Treatment Plans in a Typical Tourism City].

Perfluoroalkyl acids (PFAAs) are commonly detected in various environmental media and can cause potential risks to the ecological environment and human health. The levels and spatial distribution of 15 types of PFAAs and 3 types of PFAA precursors in the main river water and effluents of three sewage treatment plants (STPs) of Rizhao City were systematically investigated based on methods such as ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), solid phase extraction and enrichment, and hydroxyl radical (·OH) oxidation to explore the pollution characteristics of PFAAs and the contribution of their precursors to environmental pollution in different water bodies of typical tourist cities. The results of this study reveal that 15 types of PFAAs and only perfluorooctane sulfoneamide (FOSA) among the precursors are detectable in most of the water samples. The total concentration of PFAAs (∑PFAAs) in the river water and sewage effluents is 3.79-45.58 ng·L-1 and 54.04-105.64 ng·L-1, respectively. The predominant PFAAs are perfluorooctanesulfonic acid (PFOS), perfluorohexanesulfonic acid (PFHxS), perfluorooctanoic acid (PFOA), and perfluorononanoic acid (PFNA). The ∑PFAAs value of the river samples is notably lower than that of sewage treatment plant (STP) effluents. An increasing tendency was observed from the upstream to the downstream of the rivers. After hydroxyl radical oxidation treatment, the PFAA concentrations of rivers and STPs increase notably. The increased concentrations of perfluorinated carboxylic acids (PFCAs) with 4-12 perfluoroalkyl carbon chains (∑△PFCAC4~C12) in the STP effluents are much higher than those in the river, which might be induced by the degradation of precursors during the sewage treatment processes. The results of this research provide basic data and technical support for environmental pollution prevention of new emerging pollutants in tourist cities.

[Characteristics of gaseous pollutants distribution during remedial excavation at a volatile organic compound contaminated site].

Volatile and semi-volatile organic compounds (VOCs/SVOCs) are commonly identified contaminants in industrial contaminated sites in China. VOCs migrate easily in the environment due to their relatively high volatilities. When disturbed during excavation, for example, VOCs in the soil release to the air in high concentrations within relatively short period of time, joepodizing the health of the sorrounding population, if not appropriately protected. In this study, distribution of gas phase VOCs was monitored during excavation of a site remediation project, using a combined method of field testing instrument and gas phase sampling tubes. Monitoring results indicated that gas phase concentration decreased with distance, exhibiting an alternating peak-and-valley pattern in the down-wind direction. The monitoring results could be stimulated using Gaussian Puff Model. Remediation site health and safety zoning method was developed combining appropriate workplace health and safety air limits and site monitoring results. Personal protection measures deemed appropriated for each safety zone were proposed.