Revista Ambiente & Água - An Interdisciplinary Journal of Applied Science

1-12

Authors: Mateus Possebon Bortoluzzi; Paulo Ivonir Gubiani; Arno Bernardo Heldwein; Roberto Trentin; Jocélia Rosa da Silva; Astor Henrique Nied; Alencar Junior Zanon

The aim of this study was to derive a methodology for calculating a sequential water balance that accurately estimates the occurrence of excess water in soybeans cultivated in lowlands. We tested four calculation strategies of water balance associated with the simulation of soybean development, which differed on the calculation of rainfall and time of water drainage from the soil macropores. Data of volumetric moisture monitored in three soil layers throughout the soybean cycle in the 2014/15 agricultural year were used as a reference. Microporosity was used as a lower limit for the occurrence of excess water in the area. Excess water was considered to be whenever the daily volumetric soil moisture in the 0-100 mm layer was greater than 0.39 mm3 mm-3. Over the 111 days of measurement, soil moisture indicated the presence of excess water in 38 days. The traditional calculation strategy of water balance underestimated the occurrence of excess water, as well as the other strategies that considered effective precipitation in their formulas. The calculation strategy that considers that all the rainfall infiltrates in the soil and that the water from macropores is removed only by crop evapotranspiration exhibited good performance and indicated 35 days of excess water, being the most appropriate and recommended for determining excess water in lowland soybeans.

1-14

Authors: Simone Martini Salvador; Aline Aparecida Ludvichak; Dione Richer Momolli; Kristiana Fiorentin dos Santos; Catarine Barcellos Consensa; Mauro Valdir Schumacher ; James Stahl

Intensive management of forest stands can increase biomass production, as well as increase the removal of nutrients from the site. This study therefore sought to simulate different harvest intensities and to calculate the nutrient-use efficiency of Eucalyptus urograndis in different types of soil. The study was carried out in a plantation of seven-year-old hybrid E. urograndis in the city of Telêmaco Borba, Paraná, Brazil. The study site included two sub areas with sandy soil and clayey soil (Cambisols Inceptisol and Ferralsols Oxisols, respectively). Using biomass and nutrients stock data, nutrient removal was simulated under five different harvest scenarios. Nutrient-use efficiency was obtained from the relation between the amount of biomass and nutrients of each tree component. Harvesting the whole tree resulted in the removal of approximately 61% of the nutrients from the site in sandy soil, while in clayey soil 57% of the nutrients were removed. With harvesting of only the commercial stemwood, only 22% of the nutrients were removed from the sandy soil, and 21% from the clayey soil. Stemwood was the component that had the highest nutrient-use efficiency values for all the analyzed nutrients. In conclusion, to achieve nutritional sustainability of E. urograndis stands, the best harvesting system involves the removal of only commercial stemwood. For the production of stemwood, sandy soils have a greater biological efficiency of calcium and magnesium when compared to clayey soil.

1-13

Authors: Andressa Mendes Sene; Daniel Melo Rosa; Silvia Maria Millan Gutierre; Paulo Santos Pompeu

Brazil has experienced a rise in the use of agrochemicals in recent years, representing a potential threat to nearby ecosystems. The Volta Grande Reservoir (Minas Gerais/São Paulo, Brazil) has about 87% of its area surrounded by agricultural systems, and many compounds used in agriculture end up being carried into nearby water bodies. Given the potential ecological risk, our purpose was to assess pesticides in the reservoir. We collected specimens of two bivalves and three gastropods using bottom dredging and visual investigation in three different sites within the reservoir. The sampling sites were classified according to their distance from the dam, and all were close to agricultural lands. The samples were processed and frozen for qualitative toxicological analysis using mass spectrophotometry. Eight pesticides were identified, including four organochlorines (Aldrin, p,p’-DDE, Heptachlor epoxide, and Endrin) and organophosphates (Disulfoton, Malathion, Parathion- methyl, and Parathion-ethyl). All five studied species (Limnoperna fortunei, Corbicula fluminea, Melanoides tuberculata, Aylacostoma tenuilabris, and Pomacea aff. canaliculata) presented traces of pesticides in their bodies. Of the eight pesticides found in our analysis, six are illegal in Brazil, raising awareness about the continuous use of forbidden pesticides, and also the ecological risk in the Volta Grande Reservoir area. Our results suggest stricter control by environmental agencies regarding the use and commercialization of these illegal toxic compounds.

1-16

Authors: Maria Lidia Carra; Vitória Teodoro Gonçalves; Tiago Palladino Delforno; Valéria Maia de Oliveira; Ariovaldo José da Silva

Effluent from a fish tank with Nile tilapia (Oreochromis niloticus) was treated in a system of two parallel fixed-bed anaerobic reactors followed by a suspended stirred, anoxic reactor for solids, organic matter and nitrogen removal. Microbial community structure was compared between the reactors and an enriched anammox culture originated from anaerobic sludge by using the PCR (Polymerase Chain Reaction) and DGGE (Denaturing Gradient Gel Electrophoresis) techniques. DGGE analysis revealed three large microbial clusters, namely, the biomass in the inoculum, the biomass growing in the reactors, and the enriched anammox culture. The similarity between the microbial community recovered from the anaerobic reactors and the anammox community was considered low (32.7%), suggesting differentiation of the bacterial community as a function of the selection of specific anammox groups. The last step in the anoxic reactor had worsened the effluent quality. The potential of organic matter and ammonia removal in a single anaerobic reactor was demonstrated.

1-14

Authors: Bruna da Silveira Guimarães ; Kepler Borges França

This study aimed to statistically prove the influence of salinity on growth kinetics and intracellular lipid accumulation in microalgae. The species Chlorella sp., Scenedesmus acuminatus, Nannochloropsis sp., Monoraphidium contortum and Pediastrum tetras were studied, which were isolated in the Brazilian semi-arid region and cultivated in synthetic media with the addition of NaCl. From the crops, growth kinetics, dry biomass production and lipid content were analyzed, using the experimental planning for one factor as a tool, with the NaCl concentration as an independent variable. The kinetic parameters maximum growth speed (µmax) and generation time (tg), as well as lipid concentration were the response variables studied. The results showed that, in the species Scenedesmus acuminatus, Nannochloropsis sp. and Pediastrum tetras, salt stress contributed to the increase in µmax and the consequent decrease in tg. The highest levels of lipid accumulation were obtained in Nannochloropsis sp. (62.04%), in the medium with the highest salinity and Pediastrum tetras (54.04%) in the lowest. Dry biomass production was higher in Scenedesmus acuminatus (1,941.37 mg.L-1) and Nannochloropsis sp. (1237.05 mg.L-1), both at a concentration of 4.0 g.L-1. Therefore, saline stress acted directly on the cell growth and lipid content of the species, which can be used as a device to enhance lipid production for the purpose of producing biofuels.

1-15

Authors: Ariane Mendonça; Katrini Guidolini Martinelli; Carolina Dutra Degli Esposti; Lorrayne Belotti ; Karina Tonini dos Santos Pacheco

This study investigated the demographic, socioeconomic, and municipal health indicators related to the quality of water fluoridation. An ecological study was carried out in Espirito Santo state (ES), based on data from the Drinking Water Quality Surveillance Information, from 2014 to 2017. The non-parametric Mann-Whitney and Spearman tests were applied to compare municipal indicators with the availability of information and the quality of fluoridation, respectively. Fluoridation quality was calculated to define the percentage of fluoride concentration values in each municipality within the range of the optimal level corresponding to the maximum benefit for preventing dental caries and minimum risk for the occurrence of dental fluorosis. The proportion of 80% or more samples were defined as a compliance criterion. In 2014, 62.8% of the municipalities had information available, and 16.7% performed analyses of fluoride concentration. The percentage of available data increased about 30%, in 2017, with 3.8% referring to fluoride. The quality of fluoridation remained high (> 80%) in ES in almost every year, except in 2014. The municipalities with the largest population, the highest GDP per capita, and the lowest coverage of the oral health team exhibited a greater availability of information about fluoride (p <0.05). The child mortality rate showed a strong negative correlation with the quality of fluoridation. The findings reinforce the importance of directing public policies that ensure the correct practices for monitoring and maintaining the quality of fluoridation.

1-16

Authors: Arnulfo Antonio Tarón Dunoyer; Rafael Emilio González Cuello; Fredy Colpas Castillo

Coagulants can be extracted from vegetal material and applied in the treatment of wastewater. These coagulants are derived from seeds, leaves, bark, roots and fruits. This study focuses on the use of the mucilaginous extract of Stenocereus griseus (known as Cardón Guajiro) for removal of biochemical oxygen demand (BOD5), chemical oxygen demand (COD), total solids, turbidity and color in domestic wastewater from a pumping station in the city of Cartagena (Colombia). The optimal dose of S. griseus extract was determined by a pitcher test employing an E&Q F6-300 digital flocculator. All physicochemical tests were carried out following the specifications of the standard methods for wastewater (APHA). When 1400 mgL-1 of natural coagulants were used in the sewage treatment, the turbidity obtained was 29.57 TNU, representing removal of 67.24%, considering the initial turbidity. This parameter decreases until 68.61 PCU, for a 72.12% removal at the same coagulant dosage regarding the color. It must be noted that significant statistical differences were found between all tested doses of the coagulant. The mucilaginous extract of S. griseus exhibited useful properties in the primary treatment of domestic wastewater.