Poly[potassium-μ-2-[2-(carboxymethyl)phenyl]acetato]

In the title salt, [K(C10H9O4)]n, the K+ ions are coordinated by six O atoms from three different anions, and there is a cation–π inter­action at ca 3.14 Å. The 2-[2-(carboxymethyl)phenyl]acetate anions are stabilized by intramolecular O—H⋯O hydrogen bonds, and the K+ cations are linked into one-dimensional coordination polymers running along the b axis; these are further inter­connected by weak C—H⋯O hydrogen bonds

Mapping and Estimation of Nitrogen and Sulfur Atmospheric Deposition Fluxes in Central Region of the Mexican Bajio

The objective of this study was to assess the spatial and temporal distribution of nitrogen and sulfur deposition and its relationship with meteorological conditions in the metropolitan area of León in Guanajuato, México. N and S atmospheric deposition was collected using passive samplers (IER) in 10 sites in León City during three climatic seasons in 2018. Nitrate, ammonium, and sulfate concentrations and deposition fluxes of N and S were determined. From wind and air-mass trajectories analysis, mechanisms and possible sources contributing to N and S deposition in the study area were assessed. Atmospheric deposition fluxes were compared to critical load values reported for sensitive ecosystems in Europe. It was found that mean deposition flux for N (5.82 Kg N ha−1 year−1) was within the range of values reported for sensitive ecosystems in Nuevo México, Europe, and California. On the other hand, the mean deposition flux for S (13.77 S Kg ha−1 year−1) exceeded the critical load values proposed for Europe, suggesting that current S deposition could be a risk for ecosystems and water bodies in the region

Mapping of the atmospheric deposition of sulfur and nitrogen during the dry season 2016 in the Metropolitan zone of Merida, Yucatan, Mexico

Abstract. Atmospheric deposition of sulfur and nitrogen was measured in the Metropolitan Area of Merida, Yucatan in Mexico during the dry season of 2016. Passive samplers type "throughfall" based on ion exchange resins were used to measure the hydrological flows in a total of 9 sampling sites distributed throughout the city. The ions retained in the resin were analyzed by turbidimetry and colorimetry to determine Ammonium, Nitrate and Sulfate. Deposition fluxes of S and N obtained were 6.25 and 5.19 Kg ha-1 yr-1. Both, sulfur and nitrogen atmospheric deposition fluxes were higher in urban sites, exceeding almost 2 times, the reference values proposed internationally for sensitive ecosystems. From the analysis of wind roses and air masses trajectories, it was possible to establish that during this climatic season, in addition to the local vehicular emissions, regional emissions generated upwind (from E-SE) contributed to atmospheric deposition of these ions. Finally, N and S deposition fluxes and their relationship with criteria pollutants were assessed, and maps for atmospheric deposition fluxes of Ammonium, Sulfate and Nitrate were generated using geo-statistical tools in order to identify critical deposition zones in this Metropolitan zone

Characterization and Sources of Aromatic Hydrocarbons (BTEX) in the Atmosphere of Two Urban Sites Located in Yucatan Peninsula in Mexico

Abstract:Benzene,toluene,ethylbenzene,p-xylene,O3,NOx,CO,PM2.5 andmeteorologicalparameters were measured in urban air of two sites in Merida, Yucatan, Mexico during 2016–2017. Samples were collected using 1.5 h time intervals at three different sampling periods before being analyzed by gas chromatographywithflameionizationdetection. ThehighestconcentrationsofBTEXoccurredduring midday and afternoon in spring and summer seasons. Mean concentrations of, BTEX for the Cholul and SEDUMA sites, respectively, were 40.91 µg/m3 and 32.86 µg/m3 for benzene; 6.87 µg/m3 and 3.29 µg/m3 for toluene; 13.87 µg/m3 and 8.29 µg/m3 for p-xylene; and 6.23 µg/m3 and 4.48 µg/m3 for ethylbenzene. The toluene/benzene and xylene/ethylbenzene concentration ratios indicated that BTEX levels at both sites were influenced by local and fresh emissions (vehicular traffic). Bivariate and multivariate analyses were performed in order to correlate BTEX concentrations with criteria air pollutants to infer their possible sources. Health risk assessment revealed that exposure to benzene exceeded the recommended value for the integrated lifetime cancer risk. These results suggest that Merida’s population is exposed to cancer risk, and changes in the existing environmental policies should therefore be applied to improve air quality. Keywords: volatile organic compounds; BTEX; tropospheric ozone; Merida; air pollutio

Short-term Effects of Air Pollution on Health in the Metropolitan Area of Guadalajara using a Time-series Approach

ABSTRACT This work have like purpose quantitative estimates of the short-term effects of air pollution on the health of residents of five municipalities of the Metropolitan Area of Guadalajara, Mexico from 2012 to 2015 using time-series approach. Air Quality was assessed for CO, NO2, SO2, O3 and PM10. Tlaquepaque had the highest mean concentrations for CO (0.88 ppm), NO2 (24.55 ppb), SO2 (0.0036 ppm) and PM10 (53.81 µg m–3), whereas, Zapopan registered the highest mean value for O3 (25.06 ppb). Only PM10 and Ozone exceeded the maximum permissible values established in the Mexican official standards. SO2 presented the highest RRI values in MAG, especially for Zapopan and Tonala, for the majority of the population: 0–59 years and > 60 years. Regarding to CO, excepting Guadalajara and Tlaquepaque, associations were not significant in the most of studied municipalities. The increase of risk as percentage for NO2 was 1.77% for 0–59 years in Guadalajara and Tlaquepaque, 1.87% by respiratory causes in Tlaquepaque, 1.73% > 60 years in Tonala, and 1.25% for 0–59 years in Zapopan. The association between daily mortality and increased O3 levels were significant, however, values were low for all studied municipalities. Finally, regarding to PM10, only Zapopan and Tonala showed statistical significance. This study cannot predict if reductions in criteria pollutants levels would have an important effect on a reduction in daily mortality, however, considering the large size of population exposed, even when observed associations were small but significant, RRI values found are of public concern. Keywords: Relative risk index; Mortality; Megacities; Criteria air pollutants; Mexico

Trace Metal Content and Health Risk Assessment of PM10 in an Urban Environment of León, Mexico

Trace metal concentrations in PM10 were measured in an urban–industrial site in León, Mexico in three different seasons. PM10 were collected in quartz fiber filters of 47 mm diameter using low volume equipment operating with a controlled flow of 5 L min−1 over 24 h. Mass concentrations were gravimetrically determined and it was found that PM10 samples showed values in excess of the Mexican standard and the established values by WHO during cold dry and warm dry seasons. Morphology of selected particles was studied by SEM-EDS analysis, and the elemental composition was determined. Collected samples were analyzed by atomic absorption spectrometry in order to quantify ambient air concentrations of some trace metals (Cu, Co, Zn, Cd, Fe, Mg, and Mn). Median concentrations of trace metals showed the maximum value for iron (3.079 μgm−3) and the minimum value for Cd (0.050 μgm−3) over the entire period. From the meteorological analysis, it was found that sources located SW and ESE of the sampling site contributed to the levels of trace metals in PM10 in the studied site. The health risk assessment found that the population of León is at increased lifetime risk of experiencing cancer because of exposure to these concentrations of PM10 and their trace metal content

Atmospheric Levels of Benzene and C1-C2 Carbonyls in San Nicolas de los Garza, Nuevo Leon, Mexico: Source Implications and Health Risk

Atmospheric benzene and carbonyls were studied in San Nicolas de los Garza, Nuevo Leon, during 2011 and 2012. The relative abundance for measured VOCs was the following: formaldehyde (9.06 µg m−3) > acetaldehyde (8.06 µg m−3) > benzene (0.65 µg m−3). All measured VOCs had a clear seasonal trend with higher values of concentration during summer. Benzene and formaldehyde had a marked diurnal trend with the highest levels during morning, whereas acetaldehyde did not show a clear diurnal pattern. Meteorological analysis showed that the dominant winds came from NNE and ENE, suggesting that sources located in these directions contribute to the VOC levels. Principal component analysis (PCA) analysis revealed that photochemical activity influenced benzene and carbonyl levels during summer and that benzene was associated with vehicular traffic emissions during autumn and winter, showing good correlation with CO. Meteorological data showed that measured VOCs were influenced by regional sources. A health risk assessment showed that local exposure to carbonyls and benzene exceeded 1 × 10−6 for integrated lifetime cancer risk. People living in San Nicolas de los Garza, thus, have a probable risk of suffering cancer in their lifetime. It is, therefore, necessary to improve environmental policies for controlling VOC levels in this area

Characterization and sources of aromatic hydrocarbons (BTEX) in an urban site of Tijuana, Baja California, Mexico

Benzene, toluene, ethylbenzene, p-xylene, O3, NOx, CO, PM2.5and meteorological parameters were measured in urban air of one site in Tijuana, Baja California, Mexico during winter 2016-2017. Samples were collected using 1.5 h time intervals at four different sampling periods (B1: 07:30-09:00 h, B2: 12:00-13:30 h, B3: 15:00-16:30 h, B4: 18:00-19:30 h) before being analyzed by gas chromatography with flame ionization detection. The highest concentrations of BTEX occurred during the morning (B1) and afternoon (B4) sampling periods. Mean concentrations of BTEX were 32.40 μg/m3for benzene; 13.28 μg/m3for toluene; 17.16 μg/m3for p-xylene; and 7.02 μg/m3for ethylbenzene. The toluene/benzene, xylene/ethylbenzene concentration ratios and meteorological analysis indicated that BTEX levels were influenced by local and fresh emissions (vehicular traffic). Bivariate (Pearson correlation) and multivariate analyses (Principal Component Analysis) were performed in order to correlate BTEX concentrations with criteria air pollutants and meteorological parameters to infer their possible sources. These results suggest that changes in the existing environmental policies should therefore be applied to improve air quality

Health Risk Assessment of the Levels of BTEX in Ambient Air of One Urban Site Located in Leon, Guanajuato, Mexico during Two Climatic Seasons

Levels of BTEX (benzene, toluene, ethylbenzene, and p-xylene) were determined in ambient air of an urban site located at the center of Mexico (Leon City in Guanajuato State) during two climatic seasons of 2018 (summer and autumn). Ethylbenzene (11.86 µg m−3) and toluene (11.85 µg m−3) showed the highest median concentrations during the study period. BTEX concentrations did not show a diurnal pattern but a seasonal trend was observed for benzene and toluene at a significant level of α = 0.05. Bi-variate and multivariate analysis showed significant positive correlations (at α = 0.05) among BTEX (excepting benzene), indicating common sources for toluene, ethylbenzene, and p-xylene and a different origin for benzene. A meteorological study was also conducted in order to determine the origin of air masses that could influence the BTEX concentrations in the study site. Finally, it was found that all BTEX species presented hazard quotient values (HQs) <1, indicating that there is no risk of non-cancer during the studied period. Lifetime cancer risk due to benzene exposure for the adult and child populations studied were estimated to be 7 in 1,000,000 and 1 in 100,000, respectively