Effect of cooking on arsenic concentration in rice

This study assessed the effect of rinsing and boiling on total content of As (tAs) and of its inorganic and organic forms in different types of rice (polished and brown) from Spain and Ecuador. Rice was subjected to five different treatments. The results showed that the treatment consisting of three grain rinsing cycles followed by boiling in excess water showed a significant decrease in tAs content compared with raw rice. Regarding As species, it is worth noting that the different treatments significantly reduced the content of the most toxic forms of As. The estimated lifetime health risks indicate that pre-rinsing alone can reduce the risk by 50%, while combining it with discarding excess water can reduce the risk by 83%; therefore, the latter would be the preferable method.Universidad de las Fuerzas Armadas-ESPE through Project 2015- PIC-017, Xunta de Galicia-Consellería de Educación, Universidades e Formación Profesional, Plan Galego IDT, Consolidation of competitive research groups (ref. ED31C2018/12), and Cross-Research in Environmental Technologies (CRETUS, AGRUP2015/02, ref. 2018-PG100). XLOP is grateful for the financial support from the Proyecto PROMETEO (SENESCYT Ecuador).info:eu-repo/semantics/publishedVersio

Bioaccesibilidad del arsénico y metales pesados en arrozales de Ecuador y riesgo para la salud humana

Esta tesis doctoral analiza la variabilidad espacial del contenido de arsénico, formas químicas de arsénico y metales pesados en arrozales ubicados en Ecuador, otros países de Latinoamérica y de la Península Ibérica. Se analizaron muestras de arroz comercial, planta de arroz y suelos de las zonas de cultivo. También se investigó el efecto del lavado y la cocción sobre el contenido de arsénico total y sus formas orgánicas e inorgánicas. Las concentraciones medias de As y metales pesados en grano de arroz de Ecuador y de los otros países, no sobrepasan los valores umbral, exceptuando unas pocas muestras de Brasil (Cr y Pb) y tAs en muestras de España, no obstante, la concentración de iAs y los valores del cociente de peligrosidad (TQHi) para iAs y metales pesados, así como el valor del riesgo de cáncer determinado para el iAs indican que no hay riesgo para la salud humana

Toxic elements in soil and rice in Ecuador

The concentration of trace toxic metals (Cr, Zn, As, Pb, Cd, Cu, and Ni) in soil and rice plants, including the stems, leaves, and grain, from the main rice-producing provinces in Ecuador, was determined. Additionally, the soils were analyzed to determine their properties, composition, total content, bioavailable fraction, and geochemical fractions of toxic elements. Approximately 30% of soil samples in the case of Cr and Cu and 10% of samples in the case of Ni exceeded the legal thresholds for Ecuador. Moreover, for Cr and Cu, approximately 4% and 13% of samples, respectively, exceeded the threshold value of 100 mg kg−1 proposed for these two elements in several international regulations. Concentrations of As, Pb, and Cd in the soils were below the threshold values established both by Ecuadorian laws and by other countries. The concentrations of metals in rice plants did not correlate linearly with the total metal concentrations in the soil, nor with their bioavailability. However, the bioconcentration factors for As, Cd, Cu, Ni, and Zn could be predicted from bioavailability by a power law with exponents ranging from −0.724 to −1.625, which is typical of accumulator plants, where trace metal homeostasis plays an important role.info:eu-repo/semantics/publishedVersio

Assessment of variations in air quality in cities of Ecuador in relation to the lockdown due to the COVID-19 pandemic

This study analyzes the effect of lockdown due to COVID-19 on the spatiotemporal variability of ozone (O3), sulfur dioxide (SO2), and nitrogen dioxide (NO2) concentrations in different provinces of continental Ecuador using satellite information from Sentinel - 5P. The statistical analysis includes data from 2018 to March 2021 and was performed based on three periods defined a priori: before, during, and after lockdown due to COVID-19, focusing on the provinces with the highest concentrations of the studied gases (hotspots). The results showed a significant decrease in NO2 concentrations during the COVID-19 lockdown period in all the study areas: the Metropolitan District of Quito (DMQ) and the provinces of Guayas and Santo Domingo de los Ts & PRIME;achilas. In the period after lockdown, NO2 concentrations increased by over 20% when compared to the pre-lockdown period, which may be attributable to a shift towards private transportation due to health concerns. On the other hand, SO2 concentrations during the lockdown period showed irregular, non-significant variations; however, increases were observed in the provinces of Chimborazo, Guayas, Santa Elena, and Morona Santiago, which could be partly attributed to the eruptive activity of the Sangay volcano during 2019-2020. Conversely, O3 concentrations increased by 2-3% in the study areas; this anomalous behavior could be attributed to decreased levels of NOx, which react with ozone, reducing its concentration. Finally, satellite data validation using the corresponding data from monitoring stations in the DMQ showed correlation values of 0.9 for O3 data and 0.7 for NO2 data, while no significant correlation was found for SO2.info:eu-repo/semantics/publishedVersio

Analysis of total arsenic content in purchased rice from Ecuador

Natural and anthropogenic sources contribute to arsenic contamination in water and human food chain in Andean countries. Human exposure to arsenic via rice consumption is of great concern in countries where this crop is the dominant staple food, and limited information is available on the arsenic contamination on rice in Ecuador. This work was to contribute to the lack of knowledge analysing total arsenic by hydride generation-atomic absorption spectrometry in the samples of white, brown and parboiled rice purchased in Ecuadorian markets and produced in the two main rice wetlands in Ecuador, Guayas and Los Ríos, were carried out. For the samples from Guayas, arsenic concentration in white, brown and parboiled rice were 0.174 ± 0.014, 0.232 ± 0.021, and 0.186 ± 0.017 mg/kg respectively, whereas samples of white rice from Los Ríos showed a total arsenic level of 0.258 ± 0.037 mg/kg. This last arsenic concentration exceeds recommended maximum permissible limit by the FAO/WHO. Obtained data have available to estimate the Ecuadorian dietary exposure revealing serious health risk for population.S

Reutilización de Ripios de perforación en base agua como material de construcción

The growing petroleum activity in Ecuador has intensified the extraction of crude oil, generating substantial volumes of drill cuttings which, by their physicochemical characteristics, are not reincorporated in the process turning them into scrap. Given this, the objective was to determine the potential for reuse of water-based drill cuttings as a building material. This investigation obtained representative samples of cuttings that were disposed of in hazardous waste pits from January 2009 to August 2012 by the Public Company Petroecuador, operating in Shushufindi. The mechanical, physical, and chemical properties were analyzed in the laboratory for determining the material as a soil-cement alternative or for use in fabricating bricks. In both cases unconfined compressive strength and leaching was carried out and concluded that, for use as a soil-cement alternative there should be the addition of 10% cement with economic onsiderations. Brick design required no other raw materials and gave an average compressive strength of 22.6MPa. Leaching tests showed reduction in the concentration of total petroleum hydrocarbons (TPH), barium, chromium, cadmium and nickel, allowing for practical manufacturing of bricks in small production with an average compressive strength of 19MPa and 22% moisture absorption. These bricks would be useful for walls with low exposure to humidity