ABSTRACT Atrazine is an herbicide used to remove weeds in agricultural crops; however, because it is considered toxic, options for removing it from the environment are needed. Adsorption on biochar is an efficient technique for removing organic contaminants. In this study, the atrazine adsorption capacities of two biochars (BCA400 and BCA700) produced from rice husks at different pyrolysis temperatures (400 and 700 °C) were compared by phenomenological modeling. The biochars were characterized by SEM, FTIR and BET. Experimental kinetic and equilibrium data were obtained to evaluate Langmuir, Freundlich and BET isotherms and to conduct intraparticle diffusion. In comparison to BCA400, BCA700 showed a higher adsorption capacity at a higher pyrolysis temperature, and the Freundlich isotherm best described its system. To describe the kinetic adsorption data for the biochars, a phenomenological model based on intraparticle diffusion was applied, and the model fit well to these data for each biochar. This model is slow and involves the transport of atrazine to the pores of the biochar. Thus, the predictive model can be scaled up to adsorption systems.

ABSTRACT Atrazine is a herbicide widely used in agriculture; however, because of its toxicity, alternatives are needed to remove this compound from the environment. In this study, we investigated the adsorption process and the atrazine-adsorbing ability of three biochars produced at different pyrolysis temperatures from byproducts of the wood industry. The biochars were characterized by Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), and their physical characteristics were evaluated by Brunauer-Emmett-Teller (BET) analysis. The biochar pyrolyzed at 350 °C (BM350) adsorbed 26.04% of the herbicide, showing the best performance among the three biochars tested, even though it had the lowest specific surface area (1.467 m2 g–1). It also had a greater quantity of organic functional groups, which may have influenced the adsorption. The kinetics of the adsorption process were best explained by the pseudo-first-order model and by the Freundlich isotherm model. However, the biochar is not suitable for the removal of the herbicide atrazine, having a lower adsorption capacity than those of others described in the literature.

ABSTRACT Seasonal changes in agricultural soil use due to agroclimatic conditions affect the water cycle in watersheds. This study aimed to understand the temporal variation of runoff inherent to the seasonal occupation dynamics of the agricultural soil in the basin that drains the upper valley of the Marrecas River, upstream of the urban perimeter of Francisco Beltrão, PR. The effects of runoff were verified through flow peaks simulated by the HEC-HMS model in twelve monthly soil use scenarios, under seven precipitation return periods. The results indicated a strong relationship between bare soil and flow peaks, temporally delimiting April and March as the largest runoff generators and January and August as the smallest ones. The ratio quantified by rates of increase in flow peaks ranging from 0.78 to 1.64 m3 s−1 per km2 of bare soil. In addition, the survey of historical precipitation data also warns of the generation of large runoff volumes in October. Therefore, the strong correlation between the increase in flow peaks and occupation by bare soil can be quantified with good precision, but it is also necessary to consider historical precipitation records to understand the temporal distribution of runoff and flood risks.

ABSTRACT Changes in the Brazilian Forest Code (BFC) have soften the criteria for recovery and conservation of permanent preservation areas (PPAs), enhancing processes related to surface runoff. The aim of this study is to understand the effects of changes in PPA classification criteria established by BFC of 2012 to the detriment of BFC from 1965 considering the surface runoff response in the basin draining the upper Marrecas River valley in the flow peaks. The HEC–HMS model was used to simulate flow peaks considering three land-use scenarios, representative of the current use, adapting it to PPAs fitted to the BFC of 1965 and 2012 and seven precipitation return periods. In the proposed scenarios, the use of BFC of 2012, to the detriment of that from 1965, would imply a PPA reduction from 44.5% to 13.7%, resulting in a 22.1% increase in the average flow peaks, not representing, however, a significant reduction in the flow peaks when compared to the scenario representing the current land use. Therefore, when compared to BFC of 1965, in the Brazilian new Forest Code PPAs were reduced by 69.2%, increasing peak flows by up to 30.7%, thus minimizing the legal possibilities of flood mitigation to the urban perimeter of Francisco Beltrão, Paraná State, Brazil.

ABSTRACT The knowledge of pesticide residual concentrations in the environment is important to understand the threats to the environment and human health, especially when natural resources are used for human consumption. In this context, this study aimed to assess the potential ecological risk and respective sources of sediment contamination by organochlorine and organophosphorus pesticides. The study site was an urban lake located in Cascavel city, western Paraná state, Brazil, where the history of land use and occupation in the urban environment is typically agricultural. Surface sediment samples were collected every three months from April 2010 to June 2013 at five different collection points, totaling 65 samples. Analyses showed that contamination by organochlorine pesticides is related to agricultural activities in the past, with a low ecological risk to benthic organisms. Conversely, organophosphorus pesticides presented a recent and continuous contamination from urban activities, with a risk coefficient, especially for disulfoton, indicating a significant potential adverse effect on organisms. However, in general, the obtained results did not indicate an immediate risk to public health.

ABSTRACT: The use of animal-origin residues as a nutrient source without prior and proper investigations on their positive and negative impacts can affect the quality of agricultural soils and the environment into which they are inserted. In this sense, the aim of this study was to assess the impact of swine wastewater and mineral fertilization application on soil, soybean crop, and leachate characteristics. The experiment was developed in drainage lysimeters under field conditions. The following doses of swine wastewater were applied: 0, 100, 200, and 300 m3 ha−1, both with and without mineral fertilization. Swine wastewater application contributed to increasing soil nutrients; however, a special attention should be paid to Cu+ and Zn+ accumulation, which may interfere with soil quality in the long-term. In addition, Na+, K+, and N can be leached into groundwater and cause impacts on water quality. Wastewater supplied soybean crop requirements with some nutrients such as K+ and Zn2+, without the need for an additional mineral supplementation. Thus, once the above conditions are monitored, swine wastewater can be applied to soil.

ABSTRACT: Soil application of swine wastewater for nutrient cycling may represent a correct destination of these residues and reduction in production costs. However, when applied to soil, such residue may cause environmental impacts. This study aimed to analyze the chemical characteristics of the soil, corn, and leachate after successive swine wastewater applications associated with mineral fertilization. The experiment was developed in drainage lysimeters under field conditions. Wastewater doses applied were 0, 100, 200, and 300 m3 ha−1 with and without mineral fertilization. The results were submitted to analysis of variance and Tukey's test. After nine years of application, a special attention should be taken regarding water quality from a dose of 200 m3 ha−1 since some elements may leach into the soil. In addition, a synchronism between residue application and crop requirements needs to be taken into account. Doses of 200 and 300 m3 ha−1 are considered as satisfactory to meet corn nutritional requirements. Moreover, an increase in fertility characteristics was observed, but a caution regarding Cu and Zn contents should be taken since these elements produce a cumulative effect in the soil.

ABSTRACT Hog raising generates a large amount of residues that is commonly discarded into the soil as fertilizer even with environmental risks. In this context, the aim of this study was to assess the application effects of different doses of swine wastewater (SW) associated with mineral fertilization on the abundance and diversity of organisms of soil meso- and macrofauna in two soybean crops. Treatments consisted of four doses (0, 100, 200, and 300 m3 ha−1) of SW with or without mineral fertilization in two soybean crop, totaling 24 experimental units. Soil meso- and macrofauna were sampled using pitfall traps installed at each plot. Samples were sorted and the organisms were separated and identified. The highest abundances were found between groups of springtails and spider mites. Soil meso- and macrofauna differed between soybean crops influenced by soil physical and chemical parameters. Doses of swine wastewater between 0 and 300 m3 ha−1 and mineral fertilization do not have effects on ecological indices of soil meso- and macrofauna. However, periodic applications over time change soil physicochemical variables, which may lead to negative effects in the long term.

RESUMO Em longo prazo a água residuária da suinocultura pode oferecer benefícios à relação solo-planta, quando planejado o uso e monitorados possíveis impactos ambientais. O objetivo do trabalho foi investigar os efeitos da aplicação continuada de água residuária de suinocultura associada com adubação mineral após seis anos de manejo em plantio direto e sucessão de culturas (14 ciclos de produção) acerca das condições químicas do solo e da cultura do milho. As doses de água residuária foram 0, 100, 200, 300 m3 ha-1 durante o ciclo. Simultaneamente foram avaliados os efeitos da associação de adubação mineral na semeadura com água residuária de suinocultura. A água residuária da suinocultura na dose de 100 m3 ha-1 proporcionou disponibilidade e absorção de P, K+, Mg2+ e Zn2+ sem causar toxicidade às plantas ou danos ao solo constituindo viabilidade de reúso de água e fertilização alternativa de baixo custo ao produtor. Os nutrientes N, P, K+ e B devem ser complementados com adubação mineral. Atenção especial deve ser direcionada ao acúmulo de Zn2+ no solo, ao longo do tempo de aplicação de água residuária da suinocultura.

ABSTRACT In the long run, swine wastewater can provide benefits to the soil-plant relationship, when its use is planned and the potential environmental impacts are monitored. The objective of this study was to investigate the effects of continuous application of swine wastewater, associated with mineral fertilization, after six years of management in no-tillage and crop rotation (14 production cycles), on the chemical conditions of the soil and the corn crop. The doses of wastewater were 0, 100, 200, 300 m3 ha-1 during the cycle. The effects of the association between mineral fertilization at sowing and swine wastewater were evaluated simultaneously. Swine wastewater at the dose of 100 m3 ha-1 promoted availability and absorption of P, K+, Mg2+ and Zn2+ without causing toxicity to plants or damage to the soil, constituting a viable, low-cost alternative of water reuse and fertilization for farmers. The nutrients N, P, K+ and B must be complemented with mineral fertilization. Special attention should be directed to the accumulation of Zn2+ in the soil along the time of swine wastewater application.

RESUMO A disposição de água residuária da suinocultura é uma prática que se pode tornar viável à agricultura, por minimizar custos com fertilização e melhorar as condições do solo. Para tanto, é fundamental o estabelecimento de critérios que definam doses de aplicação adequadas do ponto de vista agronômico e ambiental. O objetivo do presente trabalho foi avaliar o efeito de doses de água residuária de suinocultura associada à adubação mineral no estado nutricional da planta e na qualidade fisiológica da semente da soja. O experimento, conduzido no ano agrícola 2010/2011, foi realizado em 24 lisímetros de drenagem, em delineamento em blocos casualizados em esquema fatorial 4 x 2, sendo quatro doses de água residuária da suinocultura, 0, 100, 200 e 300 m3 ha-1 aplicadas antes da semeadura, combinadas com a presença e ausência de adubação mineral em três repetições. Folhas em estádio de florescimento foram coletadas para a determinação de N, P, K+, Ca+2, Mg+2, Cu+2, Zn+2, Mn e Fe. Sintomas de toxicidade e deficiências nutricionais na cultura foram detectados. Além disto, o aumento da dose de água residuária da suinocultura propiciou menor qualidade fisiológica nas sementes de soja.

ABSTRACT Swine wastewater application is a practice that can become viable in agriculture, for minimizing fertilization costs and improving soil conditions. Therefore, it is essential to establish criteria that define appropriate application doses from the agronomic and environmental perspectives. The objective of this study was to evaluate the effects of swine wastewater doses associated with mineral fertilization on soybean nutritional status and physiological quality of seed. The experiment was conducted in the agricultural year of 2010/2011, using twenty-four drainage lysimeters in randomized block design in 4 x 2 factorial scheme, with four swine wastewater doses (0, 100, 200 and 300 m3 ha-1) applied before sowing, associated with presence and absence of mineral fertilization, in three replicates. Leaves at the flowering stage were collected for determinations of N, P, K+, Ca+2, Mg+2, Cu+2, Zn+2, Mn and Fe. Symptoms of toxicity and nutritional deficiency were observed in the crop. Furthermore, higher doses of swine wastewater caused lower physiological quality in soybean seeds.

The need for new materials to substitute injured or damaged parts of the human body has led scientists of different areas to the investigation of bioceramics since the 70's, when other materials in use started to show implantation problems. Bioceramics show some advantages like being the material that best mimics the bone tissue but also, present low mechanical strength due to its ceramic nature. This paper presents a general view about the topic.