Revista Eletrônica em Gestão, Educação e Tecnologia Ambiental

Evaluation of the impact on dams in the previous and current scenario in affected areas

Gabriela de Vargas Heinen, José Cardoso Sobrinho — Mon, 30 Dec 2024 00:00:00 -0300

Precision agriculture and irrigation improve yields and efficiency in agricultural activity. It is important to consider the impact of irrigation on the environment and adopt mitigation solutions. In this work, a regression equation model for remote prediction of environmental impact caused by the construction of irrigation dams in the micro watersheds of the Ijuizinho River/RS was developed through quantitative data. For this, 20 dams were selected in the study area, where a history of construction and maintenance was informed. Two buffers were drawn around the dams, considering the minimum PPA required for dams following current environmental legislation, Law Number 12.651/2012 and CONSEMA Resolution nº 323/2016. To carry out the spatial analysis of land use and occupation, images from the Sentinel-2A sensor were selected. The pre-processing of images was carried out following supervised classification to determine the land use classification. The information was used to obtain the proportion of each type of habitat present in the study area, namely: water, tillage, arboreal vegetation, damp areas, and undergrowth. For the analysis of environmental impact, equations of modeling were realized using multiple linear regression and Pearson’s correlation. Currently, there are no forms of prior analysis to define the environmental impact caused by the construction of an irrigation dam. Prior analysis of the environmental impact would be an important tool for decision-making on environmental licensing. The proposed methodology does not replace the other licensing steps but may justify their starts. Based on the present data set and statistical analyses applied, developing models to predict the environmental impact was not possible. Therefore, it is important to consider the peculiarities and importance of each habitat in the watershed. The suppression of a stable habitat for the construction of a dam, even with PPA recovery, will cause an environmental impact.

Synthesis and efficiency of cationic chitosan in the physical-chemical treatment of water

Tue, 26 Nov 2024 00:00:00 -0300

Water for human consumption must comply with legal potability standards, involving treatments that often use chemical agents that have impacts on the environment and human health. An alternative is to use organic polymers, such as chitosan, but in some situations, its structure should be modified to improve its applicability. This is achieved by adding reagents such as CHPTAC to make it cationic. This research aimed to create a cationic polysaccharide derived from chitosan using the CHPTAC reagent and apply it in water treatment, varying dosages and pH. The results showed that the synthesized chitosans achieved good efficiency in removing turbidity and color, in which some dosages were more effective. Furthermore, each flocculant performed better in a specific pH range, often in acidic pH. The research highlighted that both cationic and non-cationic chitosan are effective in water treatment, providing a viable alternative to commonly used inorganic coagulants.

Investigating the use of hybrid clones of Corymbia torelliana and Corymbia citriodora for the production of renewable bioreducers

Mon, 30 Dec 2024 00:00:00 -0300

Charcoal is of paramount importance in the steel industry, where it is used as a reductant and heat source in the combustion of iron ore and the production of pig iron. Research has been conducted to identify wood species that produce charcoal with superior physical, mechanical, and chemical characteristics compared to those currently used in the industry. This study aimed to characterize hybrid clones of Corymbia torelliana, Corymbia citriodora, and a clone of Eucalyptus urophylla at two final pyrolysis temperatures, 350°C and 550°C, to determine which is most suitable for use in the steel industry. Two hybrid clones of Corymbia torelliana and Corymbia citriodora and one clone of Eucalyptus urophylla were analyzed, with the latter serving as a comparison standard due to its prevalent use in charcoal production. The clones, seven years old and planted in Bom Despacho, Minas Gerais, Brazil, were subjected to laboratory pyrolysis at final temperatures of 350°C and 550°C, with a heating rate of 5°C.min^-1. The lignin and extractive contents of the species were measured, along with the gravimetric yields of the charcoal produced. The clones were characterized for apparent density, chemical analysis, higher, lower, and useful calorific values, energy density, and scanning electron microscopy (SEM) images. The Corymbia citriodora clone, at a pyrolysis temperature of 350°C, produced the best charcoal for steelmaking, evidenced by its high fixed carbon content (65.24%), energy density (1.26 Gcal.m⁻³), and a visually observed reduction in cracks and fissures. The hybrid clone of Corymbia citriodora presents a promising alternative, offering rapid growth and qualities that are comparable or superior to species currently used in the industry.

Does ultraviolet radiation affect the germination of Persian clover seeds?

Wed, 13 Nov 2024 00:00:00 -0300

This study aimed to evaluate the influence of ultraviolet light on the germination of Trifolium resupinatum L. seeds (Persian clover). The seeds were exposed to different times (doses) of exposure to UV-B and UV-C light with radiation intensity of 2.5 W m-2. Afterward, they were sown in gerbox boxes with germitest paper and stored in a Biochemical Oxygen Demand at 20°C. Tests such as germination, germination speed index, length and dry mass of seedling were performed. No significant differences were among UV-B light treatments. However, seeds exposed to 8 hours of UV-C light showed a reduction in the germination speed index when compared to control (from 92.5 to 88.7). Furthermore, the length of the seedlings increased by an average of 1.3 cm in relation to the control. Under the conditions of this study, it was concluded that Persian clover seeds exhibit relative tolerance to UV-B radiation while showing some sensitivity to UV-C radiation. The pelleting of the seeds associated with the tegument acted as a physical block, impeding the passage of UV light. The results contribute to our understanding of how Persian clover responds to UV radiation exposure.