Assessing over decadal biomass burning influence on particulate matter composition in subequatorial Amazon: literature review, remote sensing, chemical speciation and machine learning application.

A study on aerosols in the Brazilian subequatorial Amazon region, Tangará da Serra (TS) and Alta Floresta (AF) was conducted and compared to findings in an additional site with background characteristics (Manaus, AM). TS and AF counties suffer from intense biomass burning periods in the dry season, and it accounts for high levels of particles in the atmosphere. Chemical characterization of fine and coarse particulate matter (PM) was performed to quantify water-soluble ions (WSI) and black carbon (BC). The importance of explanatory variables was assessed using three machine learning techniques. Average concentrations of PM in AF and TS were similar (PM2.0, 17±10 µg m-3 (AF) and 16±11 µg m-3 (TS) and PM10-2.0, 13±5 µg m-3 (AF) and 11±7 µg m-3 (TS)), but higher than the background site. BC and SO4 2- were the prevalent components as they represented 27%-68% of particulates chemical composition. The combination of the machine learning techniques provided a further understanding of the pathways for PM concentration variability, and the results highlighted the influence of biomass burning for key sample groups and periods. PM2.0, BC, and most WSI presented higher concentrations in the dry season, providing further support for the influence of biomass burning.

Seletividade de herbicidas para pinhão manso em condições de casa de vegetação e campo / Selectivity of herbicides for pinhão manso in conditions terms of greenhouse and field

Objetivou-se avaliar a seletividade de herbicidas para plantas de pinhão manso. O trabalho foi dividido em dois experimentos realizados em casa de vegetação e campo. Nos dois experimentos foram avaliados os mesmos tratamentos químicos, dispostos em delineamento experimental de blocos casualizados, com cinco repetições. Estudaram-se dezoito herbicidas: bentazon (0,72 kg i.a. ha-1), atrazine (4,00 kg i.a. ha-1), nicosulfuron (0,06 kg i.a. ha-1), oxyfluorfen (1,44 kg i.a. ha-1), isoxaflutole (0,15 kg i.a. ha-1), sethoxydim (0,37 kg i.a. ha-1), glyphosate + imazethapyr (0,53 + 0,09 kg i.a. ha-1), imazethapyr (0,10 kg i.a. ha-1), mesotrione (0,19 kg i.a. ha-1), acifluorfen + bentazon (0,25 + 0,60 kg i.a. ha-1), glyphosate (1,80 kg i.a. ha-1), imazamox (0,04 kg i.a. ha-1), diuron (3,20 kg i.a. ha-1), ametryn (3,00 kg i.a. ha- 1), amicarbazone (1,40 kg i.a. ha-1), profoxydim (0,17 kg i.a. ha-1), bentazon + imazamox (0,60 + 0,03 kg i.a. ha-1) e flumioxazin (0,03 kg i.a. ha-1), além das testemunhas (arranquio manual das plantas daninhas e sem manejo). Para a aplicação dos tratamentos em casa de vegetação, as plantas apresentavam de 4 a 6 folhas desenvolvidas, enquanto no experimento a campo apresentavam de 10 a 12 folhas desenvolvidas. Foram avaliados as notas de fitointoxicação, a altura da planta e o diâmetro do caule aos 7, 14, 21, 28 e 35 dias após a aplicação (DAA) dos herbicidas, em casa de vegetação e campo. Com base nos resultados obtidos concluiu-se que, independentemente do experimento, os tratamentos com glyphosate e diuron e ametryn causaram danos tóxicos severos às plantas de pinhão manso até aos 35 DAA. Por outro lado, evidenciou-se a seletividade dos herbicidas profoxydim, imazamox, mesotrione, acifluorfen + bentazon, sethoxydium, oxyfluorfen, sethoxydim e nicosulfuron, com potencial para utilização na cultura do pinhão manso.

Objective to evaluate the selectivity of herbicides to pinhão manso plant. The work was divided into two experiments realized in the greenhouse and field. In two experiments we evaluated the same chemical treatments, arranged in a randomized block design, with five repetitions. Eighteen herbicides were studied: bentazon (0,72 kg i.a. ha- 1), atrazine (4,00 kg i.a. ha-1), nicosulfuron (0,06 kg i.a. ha-1), oxyfluorfen (1,44 kg i.a. ha-1), isoxaflutole (0,15 kg i.a. ha-1), sethoxydim (0,37 kg i.a. ha-1), glyphosate + imazethapyr (0,53 + 0,09 kg i.a. ha-1), imazethapyr (0,10 kg i.a. ha-1), mesotrione (0,19 kg i.a. ha-1), acifluorfen + bentazon (0,25 + 0,60 kg i.a. ha-1), glyphosate (1,80 kg i.a. ha-1), imazamox (0,04 kg i.a. ha-1), diuron (3,20 kg i.a. ha-1), ametryn (3,00 kg i.a. ha-1), amicarbazone (1,40 kg i.a. ha-1), profoxydim (0,17 kg i.a. ha-1), bentazon + imazamox (0,60 + 0,03 kg i.a. ha-1) and flumioxazin (0,03 kg i.a. ha-1), beyond the controls (manual uprooting of weeds and without management). For the application of treatments in the greenhouse, the plants presented of 4 to 6 developed leaves, while in the field experiment presented 10 to 12 developed leaves. We evaluated the notes phytointoxication, plant height and stalk diameter at 7, 14, 21, 28 and 35 days after application (DAA) of herbicides in greenhouse and field. Based on the results obtained it was concluded that, independently of the experiment, treatments with glyphosate and diuron and ametryn damage caused severe toxic damage to plants of pinhão manso to 35 DAA. On the other hand, revealed the selectivity of herbicides profoxydim, imazamox, mesotrione, acifluorfen + bentazon, sethoxydium, oxyfluorfen, sethoxydim and nicosulfuron, with potential use in the pinhão manso culture.

Genotoxicity and composition of particulate matter from biomass burning in the eastern Brazilian Amazon region.

In the present study Tradescantia pallida micronucleus (Trad-MCN) bioassay was used to assess the genotoxicity of particulate matter with a mass median aerodynamic diameter less than 10 µm (PM10) in Tangara da Serra (MT), a Brazilian Amazon region that suffers the impact of biomass burning. The levels of PM (coarse and fine size fractions) and black carbon (BC) collected were also measured. Furthermore, the alkanes and polycyclic aromatic hydrocarbons (PAHs) were identified and quantified in the samples taken during the burning period by gas chromatography with flame ionization detection (GC-FID). The PM and BC results for both fractions indicate a strong correlation (p < 0.001). The analysis of alkanes indicates an anthropic influence. Retene was the most abundant PAH found, an indicator of biomass burning, and 12 other PAHs considered to be potentially mutagenic and/or carcinogenic were identified in this sample. The Trad-MCN bioassay showed a significant increase in micronucleus frequency during the period of most intense burning, possibly related to the mutagenic PAHs that were found in such extracts. This study demonstrated that Trad-MCN was sensitive and efficient in evaluating the genotoxicity of organic compounds from biomass burning. It further emphasizes the importance of performing chemical analysis, because changes in chemical composition generally have a negative effect on many living organisms. This bioassay (ex situ), using T. pallida with chemical analysis, is thus recommended for characterizing the genotoxicity of air pollution.