Source apportionment and suitability evaluation of seasonal VOCs contaminants in the soil around a typical refining-chemical integration park in China

Accurate source apportionment of volatile organic compounds(VOCs)in soil nearby petrochemical industries prevailing globally,is critical for preventing pollution.However,in the process,seasonal effect on contamination pathways and accumulation of soil VOCs is often neglected.Herein,Yanshan Refining-Chemical Integration Park,including a carpet,refining,synthetic rubber,and two synthetic resin zones,was selected for traceability.Season variations resulted in a gradual decrease of 31 VOCs in soil from winter to summer.A method of dry deposition resistance model coupling partitioning coefficient model was created,revealing that dry deposition by gas phase was the primary pathway for VOCs to enter soil in winter and spring,with 100 times higher fux than by particle phase.Source profiles for five zones were built by gas sampling with distinct substance indicators screened,which were used for positive matrix factorization factors determination.Contributions of the five zones were 14.9%,20.8%,13.6%,22.1%,and 28.6%in winter and 33.4%,12.5%,10.7%,24.9%,and 18.5%in spring,respectively.The variation in the soil sorption capacity of VOCs causes inter-seasonal differences in contribution.The better correlation between dry deposition capacity and soil storage of VOCs made root mean square and mean absolute errors decrease averagely by 8.8%and 5.5%in winter compared to spring.This study provides new perspectives and methods for the source apportionment of soil VOCs contamination in industrial sites.

Catalytic degradation of chlorinated volatile organic compounds(CVOCs)over Ce-Mn-Ti composite oxide catalysts

Developing industrially moldable catalysts with harmonized redox performance and acidity is of great significance for the efficient disposal of chlorinated volatile organic compounds(CVOCs)in actual exhaust gasses.Here,commercial TiO_(2),typically used for molding catalysts,was chosen as the carrier to fabricate a series of Ce_(0.02)Mn_(0-0.24)TiO_(x) materials with different Mn doping ratios and employed for chlorobenzene(CB)destruction.The introduction of Mn remarkedly facilitated the synergistic effect of each element via the electron transfer processes:Ce^(3+)+Mn^(4+/3+)■Ce^(4+)+Mn^(3+/2+)and Mn^(4+/3+)+Ti^(4+)■Mn^(3+/2+)+Ti^(3+).These synergistic interactions in Ce_(0.02)Mn_(0.04-0.24)TiO_(x),especially Ce_(0.02)Mn_(0.16)TiO_(x),significantly elevated the active oxygen species,oxygen vacancies and redox properties,endowing the superior catalytic oxidation of CB.When the Mn doping amount increased to 0.24,a separate Mn_(3)O_(4) phase appeared,which in turn might weaken the synergistic effect.Furthermore,the acidity of Ce_(0.02)Mn_(0.04-0.24)TiO_(x) was decreased with the Mn doping,regulating the balance of redox property and acidity.Notably,Ce_(0.02)Mn_(0.16)TiO_(x) featured relatively abundant B-acid sites.Its coordinating redox ability and moderate acidity promoted the deep oxidation of CB and RCOOH-intermediates,as well as the rapid desorption of Cl species,thus obtaining sustainable reactivity.In comparison,CeTiO_(x) owned the strongest acidity,however,its poor redox property was not sufficient for the timely oxidative decomposition of the easier adsorbed CB,resulting in its rapid deactivation.This finding provides a promising strategy for the construction of efficient commercial molding catalysts to decompose the industrial-scale CVOCs.

The main strategies for soil pollution apportionment:A review of the numerical methods

Nowadays,a large number of compounds with different physical and chemical properties have been determined in soil.Environmental behaviors and source identification of pollutants in soil are the foundation of soil pollution control.Identification and quantitative analysis of potential pollution sources are the prerequisites for its prevention and control.Many efforts have made to develop methods for identifying the sources of soil pollutants.These efforts have involved the measurement of source and receptor parameters and the analysis of their relationships via numerical statistics methods.We have comprehensively reviewed the progress made in the development of source apportionment methodologies to date and present our synthesis.The numerical methods,such as spatial geostatistics analysis,receptor models,and machine learning methods are addressed in depth.In most cases,however,the effectiveness of any single approach for source apportionment remains limited.Combining multiple methods to address soil quality problems can reduce uncertainty about the sources of soil pollution.This review also constructively highlights the key strategies of combining mathematical models with the assessment of chemical profiles to provide more accurate source attribution.This review intends to provide a comprehensive summary of source apportionment methodologies to help promote further development.

Environmental impact and health risk assessment of volatile organic compound emissions during different seasons in Beijing

Volatile organic compounds(VOCs)are major contributors to air pollution.Based on the emission characteristics of 99 VOCs that daily measured at 10 am in winter from 15 December 2015 to 17 January 2016 and in summer from 21 July to 25 August 2016 in Beijing,the environmental impact and health risk of VOC were assessed.In the winter polluted days,the secondary organic aerosol formation potential(SOAP)of VOC(199.70±15.05 mg/m^3)was significantly higher than that on other days.And aromatics were the primary contributor(98.03%)to the SOAP during the observation period.Additionally,the result of the ozone formation potential(OFP)showed that ethylene contributed the most to OFP in winter(26.00%and 27.64%on the normal and polluted days).In summer,however,acetaldehyde was the primary contributor to OFP(22.00%and 21.61%on the normal and polluted days).Simultaneously,study showed that hazard ratios and lifetime cancer risk values of acrolein,chloroform,benzene,1,2-dichloroethane,acetaldehyde and 1,3-butadiene exceeded the thresholds established by USEPA,thereby presenting a health risk to the residents.Besides,the ratio of toluene-to-benzene indicated that vehicle exhausts were the main source of VOC pollution in Beijing.The ratio of m-/p-xylene-toethylbenzene demonstrated that there were more prominent atmospheric photochemical reactions in summer than that in winter.Finally,according to the potential source contribution function(PSCF)results,compared with local pollution sources,the spread of pollution from long-distance VOCs had a greater impact on Beijing.

Determination of hexabromocyclododecanes in sediments from the Haihe River in China by an optimized HPLC–MS–MS method

Hexabromocyclododecanes（HBCDs）,a new type of persistent organic pollutants widely used as brominated flame retardants,have attracted wide attention due to their increasing level and toxicity. A method based on high-performance liquid chromatography mass spectrometry（HPLC–MS–MS）in electrospray ionization mode has been developed by optimization of various parameters,which effectively improved the separation degree and responsive intensity of α-,β-and γ-HBCD isomers. The concentrations and distribution profiles of three HBCD isomers were investigated in sediments from the Haihe River in China.It was observed that the concentrations of HBCDs varied in the range of 0.4–58.82 ng/g,showing a decreasing trend along the flow direction,possibly due to attenuation and biodegradation along the flow direction of the Haihe River. The distribution profile of α-,β-,γ-HBCD was 7.91%–88.6%,0–91.47%,and 0.62%–42.83%,respectively. Interestingly,α-HBCD dominated in most sample sites. This was different from the distribution profile in commercial industrial products,which might be attributed to the inter-transformation and different degradation rates of the three HBCD isomers. The potential ecological risk of HBCDs in sediment was characterized under the two-tiered procedure of the European Medicines Evaluation Agency for environmental risk assessment. Although the HBCDs in the selected section of the Haihe River presented ＂no risk＂ in the sediment compartment,its risk in sediment cannot be neglected since sediment is one of the important sinks and reservoirs of pollutants.

Distribution of polychlorinated naphthalenes(PCNs) in the whole blood of typical meat animals

The concentrations and distribution of polychlorinated naphthalenes（PCNs） in the whole blood of eight typical terrestrial meat animals（chicken, duck, rabbit, pig, cattle, sheep,horse and donkey） consumed daily in our life were investigated. The total concentrations（on a liquid volume basis） of PCNs were in a range from 305 to 987 pg/L. Donkey blood contained the highest PCN concentrations. Mono-CNs were the dominant homolog group,accounting for 38%–71% PCNs. Apart from the mono-CNs and tri-CNs homolog groups, two hepta-CNs（mean： 9.5%） contributed most, followed by tetra-CNs（mean： 6.5%）. The congeners CN1, 5/7, 24/14, 27/30, 52/60, 66/67, and 73 were the most abundant congeners or congener groups. The highest toxicity equivalencies（TEQs） were observed in cattle blood（117.4 fg TEQ/L） then chicken blood（117.1 fg TEQ/L）. CN73 contributed 65% to total TEQs,followed by CN70（20%） and CN66/67（14%）. The dietary intakes of PCNs were also estimated.Chicken meat, which forms the second largest component of meat product consumption in China, contributed most to the total TEQs（61%）, followed by beef（27%） and pork（5.9%）. The consumption of chicken might pose the highest risk from exposure to PCNs than other types of meat to populations who prefer to eat chicken meat.