Influence of agricultural biomass burning on aerosol size distribution and dry deposition in southeastern Brazil

The size distributed composition of ambient aerosols is used to explore seasonal differences in particle chemistry and to show that dry deposition fluxes of soluble species, including important plant nutrients, increase during periods of biomass (sugar cane trash) burning in São Paulo State, Brazil. Measurements were made at a single site centrally located in the State's sugar cane growing region but away from the immediate vicinity of burns, so that the air sampled was representative of the regional background. Calculation of ion equivalent balances showed that during burning periods smaller particles (Aitken and accumulation modes) were more acidic, containing higher concentrations of SO(4)(2-), oxalate, NO(3)(-), HCOO(-), CH(3)COO(-), and Cl(-), but insufficient NH(4)(+) and K(+) to achieve neutrality. Larger particles showed an anion deficit due to the presence of unmeasured ions and comprised resuspended dusts modified by accumulation of nitrate, chloride, and organic anions. Increases of resuspended particles during the burning season were attributed to release of earlier deposits from the surfaces of burning vegetation as well as increased vehicle movement on unsurfaced roads. During winter months the relative contribution of combined emissions from road transport and industry diminished due to increased emissions from biomass combustion and other activities specifically associated with the harvest period. Positive increments in annual particulate dry deposition fluxes due to higher fluxes during the sugar cane harvest were 44.3% (NH(4)(+)), 42.1 % (K(+)), 31.8% (Mg(2+)), 30.4% (HCOO(-)), 12.8% (Cl(-)), 6.6% (CH(3)COO(-)), 5.2% (Ca(2+)), 3.8% (SO(4)(2-)), and 2.3% (NO(3)(-)). Na(+) and oxalate fluxes were seasonally invariant. Annual aerosol dry deposition fluxes (kg ha(-1)) were 0.5 (Na(+)), 0.25 (NH(4)(+)), 0.39 (K(+)), 0.51 (Mg(2+)), 3.19 (Ca(2+)), 1.34 (Cl(-)), 4.47 (NO(3)(-)), 3.59 (SO(4)(2-)), 0.58 (oxalate), 0.71 (HCOO(-)), and 1.38 (CH(3)COO(-)). Contributions of this mechanism to combined aerosol dry deposition and precipitation scavenging (inorganic species, excluding gaseous dry deposition) were 31% (Na(+)), 8% (NH(4)(+)), 26% (K(+)), 63% (Mg(2+)), 66% (Ca(2+)), 32% (Cl(-)), 33% (NO(3)(-)), and 36% (SO(4)(2-)).

Direct determination of arsenic in sugar by GFAAS with transversely heated graphite atomizer and longitudinal Zeeman-effect background correction

A method has been developed for the direct determination of As in sugar by graphite furnace atomic absorption spectrometry with a transversely heated graphite atomizer (end-capped THGA) and longitudinal Zeeman-effect background correction. The thermal behavior of As during the pyrolysis and atomization steps was investigated in sugar solutions containing 0.2% (v/v) HNO3 using Pd, Ni, and a mixture of Pd + Mg as the chemical modifiers. For a 60-muL sugar solution, an aliquot of 8% (m/v) in 0.2% (v/v)HNO3 was dispensed into a pre-heated graphite tube at 70 degreesC. Linear analytical curves were obtained in the 0.25 - 1.50-mug L-1 As range. Using 5 mug Pd and a first pyrolysis step at 600 degreesC assisted by air during 40 s, the formation of a large amount of carbonaceous residue inside the atomizer was avoided. The characteristic mass was calculated as 24 pg As and the lifetime of the graphite tube was around 280 firings. The limit of detection (L.O.D.) based on integrated absorbance was 0.08 mug L-1 (4.8 pg As) and the typical relative standard deviation (n = 12) was 7% for a sugar solution containing 0.5 mug L-1. Recoveries of As added to sugar samples varied from 86 to 98%. The accuracy was checked in the direct analysis of eight sugar samples. A paired t-test showed that the results were in agreement at the 95% confidence level with those obtained for acid-digested sugar samples by GFAAS.

THERMOTOLERANCE BEHAVIOR IN SUGAR-CANE SYRUP FERMENTATIONS OF WILD-TYPE YEAST STRAINS SELECTED UNDER PRESSURES OF TEMPERATURE, HIGH SUGAR AND ADDED ETHANOL

The selected yeast strains were examined for their ability lo grow, to retain cell viability and to ferment diluted sugar cane juice (15% total sugar, w/v) to ethanol at 40-degrees-C. The degree of agitation (aeration) affects the thermotolerance while the method used for isolation of the strains appears to have no significant effect. The yeast isolated are aerobically fermentative with increased levels of fermentation and growth resulting from agitation (aeration), the exact level of these increases being dependent on the strain used.

Lignin from sugar cane bagasse: Extraction, fabrication of nanostructured films, and application

Four lignin samples were extracted from sugar cane bagasse using four different alcohols (methanol, ethanol, n-propanol, and 1-butanol) via the organosolv-CO2 supercritical pulping process. Langmuir films were characterized by surface pressure vs mean molecular area (Pi-A) isotherms to exploit information at the molecular level carrying out stability tests, cycles of compression/expansion (hysteresis), subphase temperature variations, and metallic ions dissolved into the water subphase at different concentrations. Briefly, it was observed that these lignins are relatively stable on the water surface when compared to those obtained via different extraction processes. Besides, the Pi-A isotherms are shifted to smaller molecular areas at higher subphase temperatures and to larger molecular areas when the metallic ions are dissolved into the subphase. The results are related to the formation of stable aggregates (domains) onto the water subphase by these lignins, as shown in the Pi-A isotherms. It was found as well that the most stable lignin monolayer onto the water subphase is that extracted with 1-butanol. Homogeneous Langmuir-Blodgett (LB) films of this lignin could be produced as confirmed by UV-vis absorption spectroscopy and the cumulative transfer parameter. In addition, FTIR analysis showed that this lignin LB film is structured in a way that the phenyl groups are organized preferentially parallel to the substrate surface. Further, these LB films were deposited onto gold interdigitated electrodes and ITO and applied in studies involving the detection of Cd+2 ions in aqueous solutions at low concentration levels throughimpedance spectroscopy and electrochemical measurements. FTIR spectroscopy was carried out before and after soaking the thin films into Cd+2 aqueous solutions, revealing a possible physical interaction between the lignin phenyl groups and the heavy metal ions. The importance of using nanostructured systems is demonstrated as well by comparing both LB and cast films.

Modelling and optimization of the cephalosporin C production bioprocess in a fed-batch bioreactor with invert sugar as substrate

Cephalosporin C production process optimization was studied based on four experiments carried out in an agitated and aerated tank fermenter operated as a fed-batch reactor. The microorganism Cephalosporium acremonium ATCC 48272 (C-10) was cultivated in a synthetic medium containing glucose as major carbon and energy source. The additional medium contained a hydrolyzed sucrose solution as the main carbon and energy source and it was added after the glucose depletion. By manipulating the supplementary feed rate, it was possible to increase antibiotic production. A mathematical model to represent the fed-batch production process was developed. It was observed that the model was applicable under different operation conditions, showing that optimization studies can be made based on this model. (C) 1999 Elsevier B.V. Ltd. All rights reserved.

Solid-phase extraction of sugar cane soot extract for analysis by gas chromatography with flame ionisation and mass spectrometric detection

The incomplete combustion of biomass is one of the most important sources of emissions of organic compounds into the atmosphere, like polycyclic aromatic hydrocarbons (PAHs) which show genotoxic activity. Since environmental samples generally contain interferents and trace amounts of PAHs of interest, concentration and clean-up procedures are usually required prior to the final chromatographic analysis. This paper discusses the performance of Sep-Pak cartridges (silica gel and RP18) on clean-up of sugar cane soot extract. The best results were obtained with a silica Sep-Pak cartridge. The recoveries ranged from 79% (benzo[b]fluoranthene) to 113% (benzo[e]pyrene). (C) 2000 Elsevier B.V. B.V. All rights reserved.

Direct and simultaneous determination of As, Cu, and Pb in Brazilian sugar cane spirits by graphite furnace AAS using Tungsten permanent modifier with Co-injection of Pd/Mg(NO3)(2)

A method was developed using the multi-element graphite furnace atomic absorption spectrometry technique for the direct and simultaneous determination of As, Cu, and Pb in Brazilian sugar cane spirit (cachaqa) samples. Also employed was the end-capped transversely heated graphite atomizer (THGA) with platforms pre-treated with W permanent modifier and co-injection of Pd/Mg(NO3)(2). Pyrolysis and atomization temperature curves were established in a cachaqa medium (1+1; v/v) containing 0.2% (v/v) HNO3 and spiked with 20 mu g L-1 As and Pb and 200 mu g L-1 Cu. The effect of the concentration of major elements usually present in cachaqa matrices (Ca, Mg, Na, and K) and ethanol on the absorbance of As, Cu, and Pb was investigated. Analytical working solutions of As, Cu, and Pb were prepared in 10% (v/v) ethanol plus 5.0 mg L-1 Ca, Mg, Na, and K. Acidified to 0.2% (v/v) HNO3, these solutions were suitable to build calibration curves by matrix matching. The proposed method was applied to the simultaneous determination of As, Cu, and Pb in commercial sugar cane spirits. The characteristic mass for the simultaneous determination was 16 pg As, 119 pg Cu, and 28 pg Pb. The pretreated tube lifetime was about 450 firings. The limit of detection (LOD) was 0.6 mu g L-1 As, 9.2 mu g L-1 Cu, and 0.3 pig L-1 Pb. The found concentrations varied from 0.81 to 4.28 mu g L-1 As, 0.28 to 3.82 mg L-1 Cu and 0.82 to 518 mu g L-1 Pb. The recoveries of the spiked samples varied from 94-112% (As), 97-111% (Cu), and 95-101% (Pb). The relative standard deviation (n=12) was 6.9%, 7.4%, and 7.7% for As, Cu, and Pb, respectively, present in a sample at 0.87 mu g L-1, 0.81 mg L-1, and 38.9 mu g L-1 concentrations.

NEW YEAST STRAINS FOR ALCOHOLIC FERMENTATION AT HIGHER SUGAR CONCENTRATION

New yeast strains for alcoholic fermentation were isolated from samples collected from Brazilian alcohol factories at the end of the sugar cane crop season. They were selected by their capacity of fermenting concentrated sugar cane syrup as well as high sucrose concentrations in synthetic medium with a conversion efficiency of 89-92%. The strains were identified as Saccharomyces cerevisiae.

Identification of polycyclic aromatic hydrocarbons in sugar cane soot by gas chromatography mass spectrometry

Fly soot samples collected in the sugar cane fields after the process of burning were extracted in a Soxhlet apparatus (methylene chloride:methanol 4:1). The extracts were fractionated on silica gel Sep-Pak cartridges into three fractions. A gas chromatographic-mass spectrometric study of the fly soot extracts allowed the identification of the PAH with mutagenic and carcinogenic properties. Large amounts of aliphatic hydrocarbons, fatty acid esters and some PAHs were identified by GCMS in full scan mode. GC-MS in the selective ion monitoring mode (SIM) was suitable for the determination of many PAHs, which are often present in the burnt biomass. 31 PAHs and 7 thiophens derivatives were identified. The presence of these compounds should be regarded as a caution to workers and the general population to avoid exposure to the fly soot.

Thermodynamic analysis of the cogeneration system expansion in a sugar-alcohol factory

In this work it was performed energetic and exergetic analyses of three thermal plants to assessment a cogeneration system in expansion of a sugar-alcohol factory. The initial configuration considered is constituted by a low pressure steam generator, single stage steam turbines for electricity generation and crusher, shredder and mills with mechanical driving. In the intermediary configuration, the low pressure steam generator was substituted by another which generates steam at higher pressure and higher temperature, the steam turbines for electricity generation were substituted by a multiple stages extraction-condensation turbine and the other steam turbines were maintained. The final configuration consists in the substitution of these last turbines by electrical motors. Thermodynamic analyses were performed to evaluate the equipment and the overall plants efficiencies to permit a comparison among the plants. Besides of this, some important parameters of the sugar-alcohol factories were calculated.

Prediction and spatial variability of soil dynamic properties in sugar cane fields of São Paulo State Brazil

The objective of this work was to model and diagnose the spatial variability of soil load support capacity (SLSC) in sugar cane crop fields, as well as to evaluate the management impact on São Paulo State soil structure. The investigated variables were: pressure preconsolidation (sigma(p)), apparent cohesion () and internal friction angle (). The conclusions from the results were that the models and spatial dependence maps constitute important tools in the prediction and location of the mechanical internal strength of soils cultivated with sugar cane. They will help future soil management decisions so that soil structure sustainability will not be compromised.