Impact of COVID-19 restrictions on hourly levels of PM10, PM2.5 and black carbon at an industrial suburban site in northern Spain.

Due to the COVID-19 pandemic, lockdown restrictions were established around the world. Many studies have assessed whether these restrictions affected atmospheric pollution. Comparison between them is difficult as the periods of time considered are generally not the same and thus, different conclusions may be reached. Besides, most of them consider mean daily pollutant concentration, despite differences being observed according to the time of day. In this study, the hourly levels of PM10, PM2.5 and black carbon (BC) in an industrial suburban area in the north of Spain were analysed from May 2019 to June 2020 and compared with those from the literature, using the same period in each case. In general, the highest concentrations were reached when the wind direction came from the southwest (where a steelworks, a coal-fired power plant and other industries are located) and during the night-time, both before and during the lockdown. The highest concentrations of PM10, PM2.5 and BC were observed from December to February (on average: 45, 17 and 1.3 µg m-3, respectively). The decrease/increase in those pollutants levels during the lockdown were found to be highly dependent on the period considered. Indeed, PM10 can be found to decrease by up to 39% or increase by 12%; PM2.5 can decrease by 21% or increase by up to 36%; and BC, although it generally decreases (by up to 42%), can increase by 7.4%.

Impact of COVID-19 restrictions on the dry deposition fraction of settleable particulate matter at three industrial urban/suburban locations in northern Spain.

Ninety 24-h samples of the dry deposition fraction of settleable particulate matter (DSPM) were collected at one suburban industrial site ('EMA') and two urban industrial sites ('Lauredal' and 'Laboratory') in the western area of Gijón (North of Spain) from December 2019 to June 2020. The levels registered point to an environmental issue that should receive close attention from environmental authorities. Before lockdown restrictions due to COVID-19 were established, all samples collected at the EMA site exceeded 300 mg·m-2·d-1 (the Spanish limit value until 2002). Large amounts of DSPM were also registered at the Lauredal and Laboratory sites, maximum levels reaching 1039.2 and 672.7 mg·m-2·d-1, respectively. Seven metals were analysed in DSPM samples: Al, Ca, Fe, K, Mg, Mn and Na. Fe reached the highest values: 2473.4, 463.4 and 293.3 mg·m-2·d-1 (EMA, Lauredal and Laboratory sites, respectively). This study quantifies the reductions in the DSPM levels registered (on average, 97.2, 73.5 and 90.5% at the EMA, Lauredal and Laboratory sites, respectively) during the lockdown, which involved the restriction of population mobility and industrial activity. The influence of wind speed and its direction were also assessed to better understand the role of these restrictions in the observed reductions. The concentrations of all the metals in the DSPM were reduced by more than 75%, on average, except for K at the Laboratory and Lauredal sites. These decreases were much higher than those found by other authors for smaller fractions of the atmospheric particulate matter (PM10, PM2.5). The findings of the present study highlight the importance of DSPM in highly industrialized urban/suburban locations and indicate the direction that legal measures might take, given the influence of anthropogenic emissions.

Methane oxidation and attenuation of sulphur compounds in landfill top cover systems: Lab-scale tests.

In this study, a top cover system is investigated as a control for emissions during the aftercare of new landfills and for old landfills where biogas energy production might not be profitable. Different materials were studied as landfill cover system in lab-scale columns: mechanical-biological pretreated municipal solid waste (MBP); mechanical-biological pretreated biowaste (PB); fine (PBSf) and coarse (PBSc) mechanical-biological pretreated mixtures of biowaste and sewage sludge, and natural soil (NS). The effectiveness of these materials in removing methane and sulphur compounds from a gas stream was tested, even coupled with activated carbon membranes. Concentrations of CO2, CH4, O2, N2, H2S and mercaptans were analysed at different depths along the columns. Methane degradation was assessed using mass balance and the results were expressed in terms of methane oxidation rate (MOR). The highest maximum and mean MOR were observed for MBP (17.2gCH4/m2/hr and 10.3gCH4/m2/hr, respectively). Similar values were obtained with PB and PBSc. The lowest values of MOR were obtained for NS (6.7gCH4/m2/hr) and PBSf (3.6gCH4/m2/hr), which may be due to their low organic content and void index, respectively. Activated membranes with high load capacity did not seem to have an influence on the methane oxidation process: MBP coupled with 220g/m2 and 360g/m2 membranes gave maximum MOR of 16.5gCH4/m2/hr and 17.4gCH4/m2/hr, respectively. Activated carbon membranes proved to be very effective on H2S adsorption. Furthermore, carbonyl sulphide, ethyl mercaptan and isopropyl mercaptan seemed to be easily absorbed by the filling materials.

Removal of fluoride from coke wastewater by aluminum doped chelating ion-exchange resins: a tertiary treatment.

Coke wastewater is one of the most problematic industrial wastewaters, due to its large volume and complex pollutant load. In this study, ion exchange technology was investigated with the objective of reducing the fluoride content of the effluent from a coke wastewater treatment plant (26.7 mg F-/L). Two Al-doped exchange resins with chelating aminomethyl-phosphonic acid and iminodiacetic groups were assessed: Al-doped TP260 and TP207 resins, respectively. The effect of resin dosage, varying from 5 to 25 g/L, was evaluated. F- removal was within the range 57.8-89.3% and 72.0-92.1% for Al-doped TP260 and TP207, respectively. A kinetic study based on a generalized integrated Langmuir kinetic equation fitted the experimental data (R2 > 0.98). The parameters of the said kinetics met the optimal conditions for the ion exchange process, which seemed to be more favorable with Al-doped TP260 resin than with Al-doped TP207 resin, using the same resin dosage. Furthermore, the experimental data were well described (R2 > 0.98) by Langmuir and Freundlich isotherm models, in agreement with the findings of the kinetic study: the maximum sorption capacity was obtained for the Al-doped TP260 resin.

Settleable matter in a highly industrialized area: Chemistry and health risk assessment.

Settleable particulate matter (SPM) was collected at two sampling points within an urban area highly affected by nearby industrial activities. Total deposition values up to 386 mg ·m-2·d-1 were registered, the majority of samples exceeding the limit value established in the legislation in force in Spain until 2002 (300 mg·m-2·d-1). Dry deposition values showed high variability (8.6-830.3 mg·m-2·d-1). Forty-one metals and metalloids were analysed in the dry fraction of SPM, the main being Fe and Ca (maximums: 304.4 and 68.6 mg·m-2·d-1, respectively), followed by Al, Mg, Na, K, Mn, Ti, P and Zn. Trace elements like As and Pb reached up to 7.3 and 76.3 µg·â€¯m-2·d-1, respectively. Strong correlations (r > 0.90, p-value < 0.05) between Fe and other elements (Ca, Mn and Pb) were found at both sampling sites. Scanning electron microscopy confirmed the presence of these particles rich in Fe and Ca, in addition to other components, whose morphologies pointed out to anthropogenic sources. These results combined with meteorology data suggest a common industrial source contributing to the levels of these metals. Furthermore, a human health risk study was carried out to assess the potential carcinogenic and non-carcinogenic risks of exposure to thirteen elements in these particles (Al, As, Cd, Co, Cu, Mn, Mo, Ni, Pb, Sb, Sr, V and Zn). The highest levels of risk seemed to be associated with the presence of As, Pb and Sb.

Relationship Between Exposure to Sulphur Dioxide Air Pollution, White Cell Inflammatory Biomarkers and Enzymatic Infarct Size in Patients With ST-segment Elevation Acute Coronary Syndromes.

Aims: To analyse the relationship among air pollutants, markers of inflammation and infarct size in patients with acute coronary syndrome (ACS). Methods: This was a prospective analysis of consecutive patients admitted to hospital because of ACS. Cardiac biomarkers were drawn. The daily mean values of the air pollutants from the day before until 7 days before admission were analysed. The study population was stratified according to infarct size, based on median peak troponin value. Results: Patients were divided into two groups of 108 subjects each, according to median peak troponin value. Patients with extensive MIs had a higher neutrophil:lymphocyte ratio and leukocyte and neutrophil counts than patients with smaller MIs. In addition, they were exposed to higher concentrations of sulphur dioxide (9.7 ± 4.1 versus 8.4 ± 3.1 µg/m3; p=0.009) and lower concentrations of ozone (33.8 ± 13.7 versus 38.6 ± 14.5 µg/m3; p=0.014). Multivariate analysis showed that sulphur dioxide levels (OR 1.12; 95% CI [1.031-1.21]; p=0.007) and neutrophil/lymphocyte ratio (OR 1.08; 95% CI [1.011-1.17]; p=0.024) were independent predictors of infarct size. Conclusion: Patients with extensive MIs had higher white cell inflammatory levels and had been exposed to higher sulphur dioxide concentrations in the ambient air.

Anthropogenic and meteorological influences on PM10 metal/semi-metal concentrations: Implications for human health.

There is growing interest in investigating the human health risk associated with metals in airborne particulate matter. The objective of this paper is the health risk assessment of Al, Be, Sb, Sn, Ti and Tl in PM10 under different advections of air masses. These metals/semi-metal were studied in samples collected in an area influenced by industrial activities in northern Spain with the aim of analysing the variations in PM10 metal/semi-metal. Elemental concentrations were assessed over a period of one year in terms of air mass origin by means of back trajectories (HYSPLIT), the conditional probability function, polar plots, PM concentration roses, aerosol maps (NAAPs) and receptor modelling. The mean concentrations of Al, Be, Sb, Sn, Ti and Tl were 254, 0.02, 1.30, 1.15, 15.3 and 0.20  ng/m3, respectively, and were within the usual range for suburban stations in Europe. The highest levels were recorded during conditions of regional air mass origin, highlighting the importance of sources not far from the station. Under these circumstances, the renovation of air masses was not produced. The main sources of metals were anthropogenic, mostly related to the use of coal and coke production. In general, the cancer and non-cancer risk values obtained in this study fell within accepted precautionary criteria in all trajectory groups. However, in order to improve air quality and reduce risks to human health, the impact resulting from the joint inhalation of Al, Be, Sb, Sn, Ti and Tl should not be ignored when air masses are fundamentally of regional origin.

Suburban air quality: Human health hazard assessment of potentially toxic elements in PM10.

PM10 samples were collected at two suburban locations in northern Spain, a traffic-industrial suburban (TIS) station located in the coastal city of Gijón and an industrial suburban (IS) station in Langreo, about 25 km inland. The aerosol samples were chemically analysed to determine ambient air concentrations of As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Se, V and Zn. The results showed that the mean levels of As, Co, Cu, Fe, Mn, Ni, Pb and Se recorded at the IS location were higher than those at the TIS station. Mean levels of Fe and Zn in PM10 were higher than all other species at both the TIS and IS sampling sites (467 and 353 ng Fe/m3 and 46 and 282 ng Zn/m3, respectively). Human exposure to these twelve potentially toxic elements through PM10 was assessed for both children and adults using the U.S.EPA method, considering three pathways: ingestion, dermal contact and inhalation. In general, the IS location presented higher non-cancer risks than the TIS site. However, at both suburban locations, cancer and non-cancer risk values were in the acceptable range for adults, some exceptions being found. Greater health risk was estimated in the case of children. For this sector of the population, ingestion, dermal contact and/or inhalation of As, Pb and Zn in PM10 may pose a health hazard owing to possible carcinogenic/non-carcinogenic effects.

Enrichment factors to assess the anthropogenic influence on PM10 in Gijón (Spain).

Thirty-two chemical species were determined in PM10 sampled at a suburban site on the north coast of Spain. Enrichment factors were applied to infer their soil/non-soil origin. The geochemical ratios were calculated using two databases: soil composition from locations in the surroundings of the sampling station and the Earth's average upper-crust composition. In the present study, dissimilarities were found between the enrichment factors obtained using these two databases. Al, Ti, La and Ce were taken as the reference elements to normalise the data, reaching analogous conclusions. Bi, Cd, Cu, Sb, Se, Sn and Zn were associated with predominantly non-soil apportionments. As the relevance of soil/non-soil sources for the other analysed elements was found to be variable, they were probably of mixed origin. Furthermore, pairs of elements showed strong relationships, thus pointing to a common origin. Na-Mg and Co-Ni, with Pearson correlation coefficients above 0.9, were respectively related to marine and industrial apportionments. Enrichment factors have proved to be a useful tool to distinguish the soil/non-soil origin of chemical species present in airborne particulate matter. However, the choice of the reference database for soil composition considerably determined the accuracy of the conclusions.

Influence of the ultrasound pretreatment on anaerobic digestion of cattle manure, food waste and crude glycerine.

To increase the production of methane, when cattle manure (CM) is digested, pretreatments can be applied and/or the manure can be co-digested with other wastes. In this research work, a mixture of CM, food waste (FW) and raw glycerine (Gly) in a proportion in weight of 87% CM, 10% FW and 3% Gly was digested, (a) without pretreatment and (b) with pretreatment by ultrasound, applying a sonication energy of 1040 kJ/kg total solids. Specific methane production was 290 L CH4/kg volatile solids (VS) without pretreatment and 520 L CH4/kg VS with pretreatment. With respect to the volumetric methane production, 1.07 L CH4/Lreactor.day was produced in the first case, and in the second case, 1.98 L CH4/Lreactor.day. We can conclude that the application of ultrasound pretreatment significantly improved the production of biogas.

Relationship between physico-chemical characteristics and potential toxicity of PM10.

PM10 was sampled at a suburban location affected by traffic and industry in the north of Spain. The samples were analysed to determine the chemical components of PM10 (organic and elemental carbon, soluble chemical species and metals). The aim of this study was to assess the toxicity of PM10 in terms of the bulk analysis and the physico-chemical properties of the particles. Total carbon, sulphates, ammonium, chlorides and nitrates were found to be the major constituents of PM10. The contribution of the last of these was found to increase significantly with PM10 concentration (Pearson coefficient correlation of 0.7, p-value < 0.001). Individual airborne particles were characterised morphologically and chemically via a combination of Scanning Electron Microscopy and Energy-Dispersive X-ray spectroscopy (SEM-EDX). The subsequent image analysis revealed C-rich particles with shapes that pointed to combustion processes. Moreover, carbonaceous particles seemed to act as vehicles for sulphur compounds and metals (S, Na, Fe, Ca, Mg, K, Al, Mn, Zn and Cu). Coarse particles were found to be mainly constituted by crustal material and marine and carbonaceous particles. Although most of the studied individual particles in PM10 samples (86.0%) had a diameter within the 0.1-2.5 µm range, 1.8% of them had sizes lower than 0.1 µm 40.2% of the total studied particles were estimated to be inhaled and deposited in the human respiratory tract; 12.3% of these particles would reach the deepest zones, thereby posing a major risk to human health.