Seasonal and Spatial Variability of PM2.5 Concentration, and Associated Metal(loid) Content in the Toluca Valley, Mexico.

This study provides evidence of the seasonal and spatial variation of metal(lloid)s in particulate matter minor to 2.5 microns (PM2.5) in the Toluca Valley Metropolitan Area (TVMA), the fifth largest urban center in Mexico. Four sites were sampled between 2013 and 2014, which included urban and industrial areas, in the dry-cold (November-February) and dry-hot (March-May) seasons; PM2.5 was collected using high- and medium-volume samplers. Metal(lloid) concentrations in PM2.5 were analyzed using inductively coupled plasma‒mass spectrometry (ICP‒MS). The highest 24-hour PM2.5 concentration in the northern area was observed, and the PM2.5 concentrations were independent of the season. Five metal(lloid)s with a recovery percentage above 80% were considered to be reported (Co, Cr, Cu, Mn, and Sb). The maximum concentrations of metal(lloid)s were observed during the dry-cold season, and concentrations were up to one hundred or thousand fold with respect to the dry-hot season. The 24-hour PM2.5 and metal(lloid) concentrations exceeded national and international guidelines to protect population health.

Inferring pollution records in sediment cores from transitional environments of Marquelia coast, Guerrero, Mexico.

The vertical distribution pattern and concentrations of elements (Fe, Al, Ca, Mg, Mn, Cr, Cu, Ni, Co, Pb, Zn, and As) in the estuarine and lagoon region of Marquelia coast, Guerrero, Mexico, were studied to comprehend the origin and pollutant phases of geochemical elements. Henceforth, two sediment core samples [C1 (127 cm) and C2 (110 cm)] were collected to assess the pollution status using geochemical indices, namely anthropogenic factor (AF), enrichment factor (EF), and geoaccumulation index (Igeo). Additionally, the elemental concentrations were compared with the sediment quality guidelines (SQGs) to examine the potential risks to biota. Among the two depositional environments, the sediments of lagoon Apozahualco exhibited higher concentrations of elements. The granulometry characteristics of sediment grains also attested that the concentration and mobilization of metals are largely governed by the fine-grained fractions. Major elemental concentration and grain size changes were identified at several depths (30-40, 60-70, and 90-100 cm) revealing the internal hydrodynamic condition. The overall assessment of geochemical indices revealed that the sediments were unpolluted to moderately polluted. The anthropogenic factor indicated that the upper portion of the sediments were affected by anthropogenic influences. The comparison of trace element concentration with SQGs denoted that Cr, Ni, and As could pose potential adverse effect to the organisms that live in and near the sedimentary environment. Factor analysis revealed the origin and behaviour of the studied elements during transportation and deposition processes in both the ecosystems (i.e. estuary and lagoon). The results of this study provided an in-depth understanding of variations in elemental concentration and pollution status of sediment profile in coastal transitional environments that would aid in sustainable management.

Characterization of Pottery from Teotihuacan Using Laser-Induced Breakdown Spectroscopy and Inductively Coupled Plasma Optical Emission Spectroscopy.

Pottery sherds from Teotihuacan, Mexico, belonging to the Formative and Classic periods (150 BCE-700 CE) were investigated using laser-induced breakdown spectroscopy (LIBS) and inductively coupled plasma optical emission spectrometry (ICP-OES). LIBS results show that most of the investigated samples have primarily the same elemental composition. Nevertheless, there are also a few sherds that could be associated to foreign ceramic groups with characteristic concentrations of Na, K, Ca, Mn, Rb, and Sr. The relative elemental composition of red pigments applied on ceramic bodies was also analyzed through a LIBS depth profiling. Diverse hematite-based pigments were distinguished according to the detected iron content. Hematite was also combined with red soils with a high relative content of Mn, Sr, Ba, or Ti. The ICP-OES analysis of ceramic pastes is consistent with the emission intensities obtained using LIBS. Principal component analysis indicates that all samples identified as locals belong to a single chemical group. Moreover, locally made ceramics and the analyzed clays from the nearby area have the same elemental composition, which appears clearly differentiated from imported samples.

Bioactive compounds in tomato (Solanum lycopersicum) variety saladette and their relationship with soil mineral content.

The purpose of this study was to determine the relationship between the mineral composition of soils and the bioactive compound content present in tomatoes grown in three regions of Mexico: the state of San Luis Potosí and Tultitlán and Cuautitlán Izcalli from the State of México: Total phenolic compounds, lycopene, and rutin were higher in the Tultitlán tomatoes and were associated with the thallium and magnesium content in the soil. Chlorogenic acid and quercetin in the fruit from C.IZC were associated with molybdenum and nickel found in the soil. A principal component analysis showed that cupper, iron, sodium, manganese, and lead in the soil had a relationship with the antioxidant activity (AA), resveratrol, and naringin in the fruit from SLP. In the soil from TUL, a relationship between thallium with lycopene and rutin with magnesium was found. Some elements in the soil were related to the bioactivities of the fruit.