RESUMO
Volatile organic compounds, VOCs, are air pollutants widely produced by biogenic and anthropogenic sources. This work quantitatively studied the presence of these gases in the internal and external environments of schools, comparing one in an urban area (La Salle School, Canoas, RS) and another in a rural area (Santa Cassia Farm School, Nova Santa Rita, RS). The aim of this study was to compare if this environmental differences (location) influence their gases concentration. Monitoring campaigns were conducted for 6 months, occurring every 2 weeks in both schools during class hours, 1 day indoors and 1 day outdoors. The results showed higher concentrations of total volatile organic compounds in the urban school external environment compared with the same rural school environment and, in the comparison between environments, the internal environments of the two schools obtained higher VOC concentrations than the external ones, except in November and December at the urban school.
Assuntos
Poluentes Atmosféricos/análise , Poluição do Ar em Ambientes Fechados/análise , Compostos Orgânicos Voláteis/análise , Brasil , Monitoramento Ambiental , HumanosRESUMO
The increase in demand for highly soluble fertilizers brings a global sustainability concern. Alternative sources for traditional fertilization are therefore needed. Rock powder use has been proposed as an alternative approach to soil remineralization. However, research on the agricultural potential of minerals and rocks as alternative sources of nutrients is limited to changes in soil chemical attributes or effects on crop yield. In this work, we report an experimental study addressing the dissolution of two silicate rock-derived powders (andesite and dacite) that were produced during mining activities in Southern Brazil. The rock powders were exposed to Milli-Q water at pH (7.4-8.8) range, in solutions of 0.1 mol L-1 citric acid at pH range 2.1-3.3, and Milli-Q water acidified with 0.5 mol l-1 acetic acid (pH 5-5.8), in a continuous mechanical rotatory shaker at room temperature. Dissolution kinetics were determined as a function of reaction times at 24 to 5760 h, and solution pH. Based on this kinetics, dissolution rates were determined for the individual powders and compared to expected values for aluminosilicates. Based on this comparison, it was shown that the application of andesite and dacite rock-derived powder to replace high soluble fertilizers is feasible due to high dissolution rates of their minerals. The average andesite dissolution rates in Milli-Q water, in citric acid solution, and in Milli-Q water acidified with acetic acid were 2.1 × 10-5, 1.92 × 10-1 and 6.3 × 10-4 mmol cm-2 s-1, respectively for Ca, being 183%, 22.6%, and 69.2% higher than for the dacite rock. This make andesite rock a potential substitute for carbonate-based liming. In contrast, the average dacite dissolution rates in Milli-Q water, in citric acid solution, and in Milli-Q water acidified with acetic acid were 1.05 × 10-5, 7.22 × 10-5, and 3.72 × 10-5 mmol cm-2 s-1, respectively for K, being 72.0%, 61.4%, and 73.6% higher than the andesite rock. This highlights its potential use as a K source for agriculture to replace highly soluble K-fertilizers.
RESUMO
Esse trabalho descreve o estudo da propagação de tolueno na zona não saturada do solo. Mostram-se o procedimento experimental desenvolvido em colunas de laboratório, os resultados experimentais obtidos, uma análise dos resultados aplicando-se modelagem matemática, a análise estatística aplicada ao denominado modelo de puffs de simulação da dispersão e uma discussão do prosseguimento desse trabalho.
This work describes the study of the propagation of toluene in the unsaturated zone of the ground. It is shown the experimental procedure in laboratory columns. The gotten experimental results and their analysis with a mathematical modeling are shown. Also is shown an analysis statistics applied to the called the puffs' models of the dispersion simulation and a quarrel of the continuation of this work.