Participatory Development of No-tillage Systems without Herbicides for Family Farming: The Experience of the Center-South Region of Paraná

It is currently estimated that 40 million hectares worldwide are cultivated through no-tillage systems (Derpsh, 1998). Small family farms account for less than 50,000ha, half of them located in South America's Southern Cone (Wall, 1998). Many hypotheses have been offered to explain why so few small farmers have adapted to this method. The most simplistic ones relate this limited adoption to small farmers' traditionalism and to their rejection of innovation. Others point to the low technological development of animal-drawn equipment needed for this technology or the low educational level of family farmers.Results of work done in the Center-South of Paraná, Southern Brazil, by AS-PTA¹ in partnership with the region's Forum of Family Farmers Organizations, challenge these hypotheses and draw attention to the need for new approaches and processes of research and extension if the goal is to disseminate and implement appropriate no-tillage systems among family farmers. One requisite is to lower production costs of this method through elimination of herbicides and using green manure and cover crops that shift the crop-weed balance in favor of crops.     

Assessment of mercury(II) bioavailability using a bioluminescent bacterial biosensor: Practical and theoretical challenges

Critical methodological challenges in the microbial biosensor approach to assessing Hg(II) bioavailability were evaluated from the perspective of analytical chemists. The main challenge stems from the fact that the chemical speciation of Hg(II) in natural waters exerts a major control on its bioavailability, yet its natural complexation equilibria are extensively altered during conventional bioassays. New data, obtained using a bioluminescent Hg(II)-biosensor, that illustrate these challenges are presented and potential solutions proposed.     

Evaluation of the effectiveness of red mud-supported catalysts in combination with ozone and TiO<Subscript>2</Subscript> in the treatment of solution containing benzene,toluene, and xylene

Ozone and a Fe²⁺/TiO₂-based catalyst were examined in the degradation of a synthetic solution of benzene toluene and xylene (BTX) in an advanced oxidation process (AOP). The catalyst beads were made from the slurry waste of aluminum production process, by inserting the TiO₂ content and subsequent calcination. The reduction of the BTX concentration load was monitored by the reduction of chemical oxygen demand (COD) and BTX concentration. Different levels were used on factors: pH, time of treatment, initial concentration of BTX, and percentage of TiO₂. The process was conducted in a bubble column reactor with the insertion of catalyst beads. A response surface methodology technique (CCD) was used to build a model based on COD reduction results. The model was optimized using the normal-boundary intersection (NBI) algorithm to maximize COD reduction and minimize the variance attributed to the process. Optimization led to COD reductions of 80% in 2 h of experiment. Correlation analysis of coefficient models from experimental data R²_adj was 0.9966, showing a good fit of model data. In the optimized conditions, the possible increase of the biodegradability ratio of the BTX solution, through the biochemical oxygen demand (BOD) and COD, was also analyzed. Under pre-treatment conditions, the BOD/COD ratio was 0.13. After the treatment, it increased to 0.56.

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Effect of the Incorporation of Lysozyme on the Properties of Jackfruit Starch Films

Jackfruit starch based biodegradable films containing lysozyme were characterized for their antimicrobial activity, thickness, solubility, water vapor permeability and mechanical properties. The biodegradable films had good appearance and antimicrobial activity against Micrococcus lysodeikticus. The thickness of the biodegradable films were not affected by the variation in pH, but the addition of lysozyme increased the thickness, the thickest films being those with the highest lysozyme concentrations. The variation in pH of the filmogenic solutions affected the solubility of the biodegradable films, water solubility being greatest at pH 7.0 and with the highest lysozyme concentration. The permeability of the biodegradable films was increased by incorporating lysozyme. The lysozyme concentration and pH variation caused changes in the mechanical properties. The addition of 8% lysozyme increased the tensile strength and Young’s modulus for all the pH values studied. With respect to the release of antimicrobial activity, the diffusion of lysozyme was shown to follow Fickian transport mechanism.     

Physical–chemical processes of sustainable materials’ production from hazardous toner waste,galvanic glass waste and spent foundry sand

Journal of Material Cycles and Waste Management - Several sustainable white ceramic composites were prepared from 3 to 7 wt.% of hazardous toner waste, 30–40% of spent foundry sand,...     

Evaluation of Noise Pollution in Urban Parks

The present study provides an evaluation of noise pollution in six Urban Parks located in the city of Curitiba, Brazil. Equivalent noise levels (L _eq) were measured in 303 points (each point measured during 3 min) spread throughout the Parks. Measured values were confronted with local legislation (Law 10625) allowed limits, and the Parks were thus classified as “acoustically polluted or unpolluted”. Measured values were also evaluated according to international legislation: Decree no. 12 of the City Council of Rome, DIN 18005 for German cities, the World Health Organization, and the United States Environmental Protection Agency. Urban parks in the downtown area of Curitiba, surrounded by roads of heavy traffic and in the midst of intense commercial activities, do not satisfy any of the standards used. The most noise-polluted parks in Curitiba were the Public Walk Park and the Botanical Garden Park, with measured L _eq of 64.8 dB(A) and 67 dB(A).     

Potential of carbon accumulation in no-till soils with intensive use and cover crops in southern Brazil

The area under no-till (NT) in Brazil reached 22 million ha in 2004-2005, of which approximately 45% was located in the southern states. From the 1970s to the mid-1980s, this region was a source of carbon dioxide to the atmosphere due to decrease of soil carbon (C) stocks and high consumption of fuel by intensive tillage. Since then, NT has partially restored the soil C lost and reduced the consumption of fossil fuels. To assess the potential of C accumulation in NT soils, four long-term experiments (7-19 yr) in subtropical soils (Paleudult, Paleudalf, and Hapludox) varying in soil texture (87-760 g kg(-1) of clay) in agroecologic southern Brazil zones (central region, northwest basaltic plateau in Rio Grande Sul, and west basaltic plateau in Santa Catarina) and with different cropping systems (soybean and maize) were investigated. The lability of soil organic matter (SOM) was calculated as the ratio of total organic carbon (TOC) to particulate organic carbon (POC), and the role of physical protection on stability of SOM was evaluated. In general, TOC and POC stocks in native grass correlated closely with clay content. Conversely, there was no clear effect of soil texture on C accumulation rates in NT soils, which ranged from 0.12 to 0.59 Mg ha(-1) yr(-1). The C accumulation was higher in NT than in conventional-till (CT) soils. The legume cover crops pigeon pea [Cajanus cajan (L.) Millsp] and velvet beans (Stizolobium cinereum Piper & Tracy) in NT maize cropping systems had the highest C accumulation rates (0.38-0.59 Mg ha(-1) yr(-1)). The intensive cropping systems also were effective in increasing the C accumulation rates in NT soils (0.25-0.34 Mg ha(-1) yr(-1)) when compared to the double-crop system used by farmers. These results stress the role of N fixation in improving the tropical and subtropical cropping systems. The physical protection of SOM within soil aggregates was an important mechanism of C accumulation in the sandy clay loam Paleudult under NT. The cropping system and NT effects on C stocks were attributed to an increase in the lability of SOM, as evidenced by the higher POC to TOC ratio, which is very important to C and energy flux through the soil.     

Disposal of dredged sediments in tropical soils: ecotoxicological effects on earthworms

The upper limit concentrations of metals established by international legislations for dredged sediment disposal and soil quality do not take into consideration the properties of tropical soils (generally submitted to more intense weathering processes) on metal availability and ecotoxicity. Aiming to perform an evaluation on the suitability of these threshold values in tropical regions, the ecotoxicity of metal-contaminated dredged sediment from the Guanabara Bay (Rio de Janeiro, Brazil) was investigated. Acute and avoidance tests with Eisenia andrei were performed with mixtures of dredged sediment with a ferralsol (0.00, 6.66, 13.12, 19.98, and 33.30 %) and a chernosol (0.00, 6.58, 13.16, 19.74, and 32.90 %). Mercury, lead, nickel, chromium, copper, and zinc concentrations were measured in test mixtures and in tissues of surviving earthworms from the acute tests. While ferralsol test mixtures provoked significant earthworm avoidance response at concentrations ≥13.31 %, the chernosol mixtures showed significant avoidance behavior only at the 19.74 % concentration. The acute tests showed higher toxicity in ferralsol mixtures (LC50?=?9.9 %) compared to chernosol mixtures (LC50?=?16.5 %), and biomass increased at the lowest sediment doses in treatments of both test soils. Most probably, the expansive clay minerals present in chernosol contributed to reduce metal availability in chernosol mixtures, and consequently, the ecotoxicity of these treatments. The bioconcentration factors (BCF) for zinc and copper were lower with increasing concentrations of the dredged sediment, indicating the existence of internal regulating processes. Although the BCF for mercury also decreased with the increasing test concentrations, the known no biological function of this metal in the earthworms metabolism lead to suppose that Hg measured was not present in bioaccumulable forms. BCFs estimated for the other metals were generally higher in the highest dredged sediment doses.     

Evaluating the urban climate of a typically tropical city of northeastern Brazil

This study attempted to assess a bioclimate index and the occurrence of an urban heat island in the city of Campina Grande, northeastern Brazil, using data taken from mobile measurements and Automatic Weather Stations (AWS). The climate data were obtained during two representative months, one for the dry season (November 2005) and one for the rainy season (June 2006) at seven points in an urban area. Ten-minute air temperatures recorded by an AWS installed in urban areas were compared to those from a similar station located in a suburban area to assess the urban heat island (UHI). The data were collected using a 23X data logger (Campbell Scientific, Inc.) programmed for collecting data every second. The thermal discomfort level was analyzed by Thom’s discomfort index (DI), and an analysis of variance was applied for assessing if there was any statistically significant difference at the 1% and 5% significance level of thermal comfort among points. Mann–Kendall statistical test was used for identifying possibly significant trends in a time series for air temperature, relative humidity, and class A pan evaporation for the city of Campina Grande. The present study found UHI intensities of 1.48°C and ??0.7°C for the months taken as representative of the dry and rainy seasons, respectively. Summer in the city has partially comfortable conditions while the winter is fully comfortable. There are significant changes in DI hourly values between seasons. Only during the rainy season did all points of the city have a comfortable condition until 8:19 h, at which time they become partially comfortable for the rest of the day. Results indicated that there was a 1.5°C increase in air temperature and a 7.2% reduction in relative humidity throughout the analyzed time series. The DI also showed a statistically significant increasing trend (Mann–Kendall test, p?<?0.01) for the dry and rainy seasons and annual period of approximately 1°C in the last 41 years in the city of Campina Grande.     

Guidance on choosing a measuring instrument for indoor particle pollution studies

The possibility of acquiring real-time concentration data is leading many indoor air quality and health researchers to the use of particle measuring instruments instead of the classic filtration approach. This paper summarizes a checklist of characteristics that have to be considered on the selection of such instruments and checks the compliance of three air monitoring devices suitable for environmental exposure researches. An evaluation table with desirable instrument technical, economic, and logistics characteristics was summarized in a checklist, and spec sheets of three air monitoring devices suitable for environmental exposure researches were checked. Technical, economic, and logistics aspects have to be considered. Suitability, measurement range, accuracy, resolution, and robustness are indispensable metrological characteristics. Only one instrument was in comply with it. A popular air monitoring device among environmental exposure researchers was checked and it failed the accuracy check. When selecting a particle measuring instrument, technical, economic, and logistics aspects have to be considered. Suitability, measurement range, accuracy, resolution, and robustness are indispensable metrological characteristics. When selecting an instrument for a study, a lack of information on the quality of results is a strong indication that it should not be considered, as study's response may be compromised.