Deposition and leaching of tebuthiuron on sugar cane straw applied with and without alkyl polyglycoside adjuvant

A laboratory experiment was carried out aiming to study the effects of an alkyl polyglycoside adjuvant (APG) on deposition and leaching of the herbicide tebuthiuron applied on sugar cane straw. Tebuthiuron, at concentration of 1200 mg L(-1), was applied separately and in tank mix with the APG adjuvant, at concentrations of 0.07 and 0.09% (wt v(-1)), using a spraying volume of 204 L ha(-1). A precipitation equivalent to 20 mm of rain was simulated, 24 h after the applications, to evaluate the herbicide leaching. The quantification of tebuthiuron was carried out by the high performance liquid chromatography (HPLC). It was observed that the addition of APG adjuvant at 0.07% (wt v(-1)) provided an increase of 11.5% in the deposition of tebuthiuron on straw, reduction of 50.4% in the drift of the herbicide and it did not affect significantly the leached amount (68.5%), when compared with the treatment where tebuthiuron was applied alone (70.8%). At the concentration of 0.09% (wt v(-1)), the APG adjuvant caused an increase of 22.7% in the deposition; it reduced the drift of the herbicide by 99.9% and reduced the leached amount by 7.6% thereby increasing the retention of the herbicide by straw.     

Euglena gracilis as a model for the study of Cu2+ and Zn2+ toxicity and accumulation in eukaryotic cells

We have observed the effect of copper and zinc on the biology of Euglena gracilis. The cells displayed different sensitivities to these metals, as the apparent LC50 for Cu2+ was 0.22 mM, and for Zn2+ it was 0.88 mM. While Zn2+ was able to increase cell proliferation even at 0.1 mM, the minimal CuCl2 concentration tested (0.02 mM) was sufficient to impair cell division. Higher concentrations of these metals not only inhibited cell division in a concentration-dependent manner, but also interfered with the metabolism of E. gracilis. A higher accumulation of proteins and lipids per cell was observed at the DI50 concentration for metal-treated cells. These results suggest that the test concentration of both metals leads to a failure in completing cell division. Ultrastructural analysis indicated a chloroplast disorganization in copper-treated cells, as well as the presence of electron dense granules with different shapes and sizes inside vacuoles. Microanalysis of these granules indicated an accumulation of copper, thus suggesting a detoxification role played by the vacuoles. These results indicate that E. gracilis is an efficient biological model for the study of metal poisoning in eukaryotic cells. They also indicate that copper and zinc (copper being more poisonous) had an overall toxic effect on E. gracilis and that part of the effect can be ascribed to defects in the structure of chloroplast membranes.     

Selectivity of the herbicide flazasulfuron applied after postemergence in sugarcane (Saccharum spp. L.) crop

The selectivity of the herbicide flazasulfuron was evaluated when applied at two rates (50 and 100 g/ha) with and without surfactants (Aterbane or Agral at 0.2% v/v). The treatment was applied at early (three leaves) and late (five to six leaves) stages of the postemergence of sugarcane plants (var. RB845257) grown in two soils (sandy and clay) with good moisture status before and after application. Despite the toxicity symptoms, especially at the late stage with the higher rate of application in the sandy soil, the herbicide did not affect the growth nor the stalk yield. The presence of the surfactants had no effect on the toxicity symptoms.     

Variations in circulating hemocytes are affected by age and caste in the stingless bee <Emphasis Type="Italic">Melipona quadrifasciata</Emphasis>

The insect immune system faces various challenges; particularly in social bees, caste system and age polyethism expose individuals to numerous environmental and working conditions. However, little is known about how cellular defenses in social bees may be organized to respond to a variety of immune challenges. Here, we describe the morphological features and the total and differential counts of hemocytes in different female classes (newly emerged workers, nurses, foragers, and virgin queens) of the eusocial stingless bee Melipona quadrifasciata. Granulocytes and prohemocytes were, respectively, the most and the least abundant cells among all classes of females. Furthermore, there were more prohemocytes in virgin queens than in foragers. The total number of hemocytes was smaller in foragers, whereas the largest number was observed in nurse workers. This reduced amount of hemocytes in foragers might allow energy savings to perform colony activities such as foraging and defense. Foragers also had the biggest hemocytes (either prohemocytes, granulocytes, or plasmatocytes) in comparison to the other classes of females, which might have arisen as a compensation for the reduction in number of these cells during aging. These results suggest that profiles of hemocytes of M. quadrifasciata vary according to the caste and age of this eusocial bee.     

Fostering coastal resilience to climate change vulnerability in Bangladesh,Brazil, Cameroon and Uruguay: a cross-country comparison

This paper describes a comparative study of four different cases on vulnerability, hazards and adaptive capacity to climate threats in coastal areas and communities in four developing countries: Bangladesh, Brazil, Cameroon and Uruguay. Coastal areas are vulnerable to sea-level rise (SLR), storm surges and flooding due to their (i) exposure, (ii) concentration of settlements, many of which occupied by less advantaged groups and (iii) the concentration of assets and services seen in these areas. The objective of the paper is twofold: (i) to evaluate current evidence of coastal vulnerability and adaptive capacity and (ii) to compare adaptation strategies being implemented in a sample of developing countries, focusing on successful ones. The followed approach for the case evaluation is based on (i) documenting observed threats and damages, (ii) using indicators of physical and socioeconomic vulnerability and adaptive capacity status and (iii) selecting examples of successful responses. Major conclusions based on cross-case comparison are (a) the studied countries show different vulnerability, adaptive capacity and implementation of responses, (b) innovative community-based (CBA) and ecosystem-based adaptation (EbA) and (c) early warning systems are key approaches and tools to foster climate resilience. A recommendation to foster the resilience of coastal communities and services is that efforts in innovative adaptation strategies to sea-level rise should be intensified and integrated with climate risk management within the national adaption plans (NAPAs) in order to reduce the impacts of hazards.     

Persistence of desertified ecosystems: Explanations and implications

Studies of rainfall partitioning by shrubs, responses of shrub-dominated ecosystems to herbicide treatment, and experiments using drought and supplemental rainfall were conducted to test the hypothesis that the shrub-dominated ecosystems that have replaced desert grasslands are resistant and resilient to disturbance. Between 16 and 25% of the intercepted rainfall is channelized to deep soil storage by stemflow and root channelization. Stemflow water is nutrient enriched and contributes to the islands of fertility that develop under desert shrubs. Drought and rainfall augmentation experiments during the growing season after 5 consecutive years of summer drought found that (1) growth of creosotebushes, Larrea tridentata, was not significantly affected, (2) perennial grasses and forbs disappeared on droughted plots, (3) nitrogen mineralization increased in the short term, and (4) densities and biomass of spring annual plants increased on the droughted plots. Doubling summer rainfall for 5 consecutive years had less-significant effects. Coppice dunes treated with herbicide in 1979 to kill mesquite (Prosopis glandulosa) had the same frequency of occurrence of the shrub as the untreated dunes when remeasured in 1993. These data indicate that the shrub-dominated ecosystems persist because they are resistant and resilient to climatic and anthropogenic stresses.Notice: The U.S. Environmental Protection Agency (EPA), through its Office of Research and Development (ORD), partially funded and collaborated in the research described herein. This paper has been subjected to EPA's peer review and has been approved as an EPA publication. The U.S. Government has a nonexclusive, royalty-free license in and to any copyright covering this article.     

Sugarcane straw management for bioenergy: effects of global warming on greenhouse gas emissions and soil carbon storage

Mitigation and Adaptation Strategies for Global Change - Global warming can intensify the soil organic matter (SOM) turnover, damaging soil health. Crop residues left on the soil are important to...     

Investigation and proposal for reuse of effluents from beneficiated bentonite products

This work is intended to show the characterization of three effluents (X, Y, and Z) derived from laboratory analyses conducted in the quality control department of a beneficiated bentonite products factory in order to present alternatives for their treatment and final disposal according to Brazil's National Solid Waste Policy (Política Nacional de Resíduos Sólidos – PNRS, Law 12,305/2010, Brazil). Analyses to identify the characteristics of the effluents revealed that the pH, salinity, electroconductivity, and total dissolved solids were in agreement with the organic and mineral nature of the effluent constituents: solvent, clay minerals, water, and activating agent. To assess reuse proposals, the effluents were subjected to the following tests: (a) swelling characteristic with effluent X, (b) petrochemical characterization of Y, and (c) swelling characteristic using commercial solvent and activated clay produced with effluent Z. Preliminary results indicate that each of these effluents can be reused variously in the laboratory, as a fuel, or in the original analysis/process.     

Determination of plate waste in primary school lunches by weighing and visual estimation methods: A validation study

The aim of this study was to validate the visual estimation method for aggregated plate waste of main dish at Portuguese primary school canteens. For this purpose plate waste at school lunch was measured for 505 individual servings, using weighing individual servings and plate waste and visual estimation method by a 6-point scale, as developed by Comstock et al. (1981). A high variability of initial serving weights was found with serving sizes ranging from 88.9 to 283.3 g and with a coefficient of variation ranging from 5.5% to 24.7%. Mean plate waste was 27.5% according to the weighing method. There was a significant bias in the conversion of the visual waste estimations to actual waste, being overestimated by an average of 8.0 g (ranging from ?12.9 g to 41.4 g). According to Bland and Altman plot, the mean difference between methods was of 8.0 g and the amplitude interval was 102.6 g. The study showed that the visual estimation method is not as accurate as the weighing method in assessing nonselective aggregated plate waste at primary school canteens. Our findings are thus very important on considering plate waste assessment, since the wide variation on initial servings introduces a relevant bias when considering standard portions or a random sample of initial servings. Although, greater convenience, time-saving and the possibility to monitor plate waste of large groups, make the visual estimation method an important method to assess plate waste at school canteens, these results highlighted the need of portions standardization and control of initial servings to allow for its use.