Short-term soil CO2 emission after conventional and reduced tillage of a no-till sugar cane area in southern Brazil

The impact of tillage systems on soil CO2 emission is a complex issue as different soil types are managed in various ways, from no-till to intensive land preparation. In southern Brazil, the adoption of a new management option has arisen most recently, with no-tillage as well as no burning of crops residues left on soil surface after harvesting, especially in sugar cane areas. Although such practice has helped to restore soil carbon, the tillage impact on soil carbon loss in such areas has not been widely investigated. This study evaluated the effect of moldboard plowing followed by offset disk harrow and chisel plowing on clay oxisolCO(2) emission in a sugar cane field treated with no-tillage and high crop residues input in the last 6 years. Emissions after tillage were compared to undisturbed soil CO2 emissions during a 4-week period by using an LI-6400 system coupled to a portable soil chamber. Conventional tillage caused the highest emission during almost the whole period studied, except for the efflux immediately following tillage, when the reduced plot produced the highest peak. The lowest emissions were recorded 7 days after tillage, at the end of a dry period, when soil moisture reached its lowest rate. A linear regression between Soil CO2 effluxes and soil moisture in the no-till and conventional plots corroborate the fact that moisture, and not soil temperature, was a controlling factor. Total soil CO2 loss was huge and indicates that the adoption of reduced tillage would considerably decrease soil carbon dioxide emission in our region, particularly during the summer season and when growers leave large amounts of crop residues on the soil surface. Although it is known that crop residues are important for restoring soil carbon, our result indicates that an amount equivalent to approximately 30% of annual crop carbon residues could be transferred to the atmosphere, in a period of 4 weeks only, when conventional tillage is applied on no-tilled soils. (c) 2005 Elsevier B.V. All rights reserved.

Fast chromatographic determination of polycyclic aromatic hydrocarbons in aerosol samples from sugar cane burning

Sugar cane burning in Brazil causes remarkable amounts of organic compounds to be emitted amongst which the polycyclic aromatic hydrocarbons (PAHs) represent serious health hazards. Therefore, 24-h aerosol samples (< 10 mum aerodynamic diameter) were collected in Araraquara city (São Paulo state) during the harvest season using a Hi-Vol sampler. PAHs were recovered using an Accelerated Solvent Extractor and analyzed by low-pressure gas chromatography-ion trap mass spectrometry (LP-GC-IT-MS). The fully automated extraction process was performed in less than 25 min with a solvent consumption of approximately 20 ml. The use of a deactivated 0.6 m x 0. 10 mm i.d. restrictor coupled to a 10 m wide-bore analytical column allowed most of the 16 PAHs in EPA's priority list to be identified and quantified in only 13 min. Concentrations of PAHs in Nraraquara aerosols ranged between 0.5 and 8.6 ng m(-3). (C) 2003 Elsevier B.V. All rights reserved.

Characterisation of sugar cane combustion particles in the Araraquara region, Southeast Brazil

Biomass burning is an important primary and secondary source of aerosol particles. The presence of carbonaceous particles in the respirable size range makes the study of this fraction important in view of possible health and climatic effects. The annual burning of sugar cane plantations causes emission of huge amounts of pyrogenic particles. Aerosol samples were collected in Araraquara city, São Paulo state, Brazil, during the harvest season for fine and coarse particles and bulk; they were analysed by electron-probe microanalysis, including facilities for low-Z element determination (low-Z EPMA) and by energy-dispersive X-ray fluorescence (EDXRF), in order to investigate the elemental composition of individual particles and bulk samples, respectively. Numerical analysis of the EPMA results by hierarchical clustering shows high contributions of carbonaceous particles that can be distinguished mainly in two different types: biogenic and carbon-rich. Additionally, two significant contributions of aluminosilicate particles were identified: as rather pure aluminosilicates or mixed with carbonaceous species. The EDXRF results are compatible with those of aerosol particles in Amazon, which is nowadays one of the main sources of biogenic particles in the world.

Influence of sugar cane burning on aerosol soluble ion composition in Southeastern Brazil

Seasonal variability in the major soluble ion composition of atmospheric particulate matter in the principal sugar cane growing region of central São Paulo State indicates that pre-harvest burning of sugar cane plants is an important influence on the regional scale aerosol chemistry. Samples of particulate matter were collected between April 1999 and February 2001 in coarse (> 3.5 mum) and fine (< 3.5 mum) fractions, and analysed for HCOO-, CH3COO-, C2C42-, SO42- . Results indicated that the principal sources of the aerosols investigated NO3-, Cl-, Na+, K+, NH4+, Mg2+ and Ca2+ were local or regional in nature (scale of tens to a few hundreds of km), and that differences between air masses of varying origins were small. Fine particles were typically acidic, containing secondary nitrates, sulphates and organic species. Coarse fraction concentrations were mainly influenced by physical parameters (wind speed, movement of vehicles and surface condition) affecting rates of re-suspension, although secondary nitrate and sulphate were also present in the larger particles.Concentrations of all measured species except sodium and chloride were higher during the burning season. Although concentrations were lower than often found in polluted urban environments, the massive increases during much of the year, due to a single anthropogenic activity (sugar cane burning) are indicative of a very large perturbation of the lower troposphere in the region relative to the natural condition. These aerosols are suspected of promoting respiratory disease. They also represent an important mechanism for the tropospheric transport of species relevant to surface acidification (sulphates, nitrates, ammonium and organic acids) and soil nutrient status (potassium, nitrogen, ammonium, calcium), so their impact on fragile natural ecosystems (following deposition) needs to be considered. (C) 2004 Elsevier Ltd. All rights reserved.

Sustainability and CDM projects in the Brazilian sugar cane sector: a discussion on the economic-financial aspects

The study discusses how the revenue from the sale of Certified Emission Reductions (CERs) can contribute to the attractiveness of investment in projects of bagasse-based cogeneration. It was observed that revenue from CERs is probably not enough to make these investments acceptable in the economic and financial aspect. However, this study speculates that Clean Development Mechanism projects will be strategic to build a positive image concerning the social responsibility and sustainability of the business in the Brazilian sugar cane sector.

The Archipelago of Fernando de Noronha: An Intriguing Malformed Toad Hotspot in South America

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Influence of sugar cane vinasse on the sorption and degradation of herbicides in soil under controlled conditions

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Skin water uptake and renal function in the toad

1. 1. Water balance in the toad Bufo marinus ictericus was studied by evaluating cutaneous water uptake and renal excretion. 2. 2. The permeability of the skin to water was 78 ± 6 nl min -1 cm -2 atm -1 in 60 toads anaesthetized by chloralose and preincubated in water for 3 hr. Injection of Ringer's solution did not reduce the water uptake by the skin, while hemorrhage, or injection of vasopressin, or oxytocin approximately doubled the rates of water transport. In vivo values of skin water permeability were similar to those observed in vitro. 3. 3. The renal parameters of the water balance were significantly reduced by hemorrhage and by injection of vasopressin. Injection of Ringer's solution promoted a significant increase of the urinary flow and osmolar clearance. 4. 4. It is suggested that the fight against water deprivation could proceed initially by the triggering of the urinary mechanisms of water retention, while the increase of the skin water permeability would occur in a later stage. © 1981.

The in vivo electrical parameters of toad skin

1. 1. Open-circuit voltage (PD) and short-circuit current (SCC) across toad skin were studied in in vivo conditions. An improved technique for fastening a lucite chamber on the abdominal region of the animal was developed. 2. 2. Saline bridges (230 mM Nacl in 4% agar solution) were placed subcutaneously to make the connections between the extracellular fluid and the half-cells. 3. 3. A clear relationship was observed between the electrical parameters and sodium transport by the skin, since PD and SCC were related to the sodium concentration of the bathing solution, and abolished by the presence of amiloride-a specific sodium transport inhibitor in epithelia. 4. 4. The initial control values of SCC in vivo were higher than those in vitro, which was attributed to hormonal stimulation. However, these high initial control values of SCC in vivo fell with time, reaching steady levels after a 2 hr period. 5. 5. Vasopressin failed to increase SCC in vivo when the external sodium concentration was 115 mM, being effective only when the sodium concentration was low (5 mM). 6. 6. On the other hand, in isolated preparations vasopressin significantly promoted an increase in both PD and SCC. © 1983.

Influence of the diet on in situ disappearance of dry matter, organic matter, and neutral detergent fiber of hydrolysed sugar cane bagasse

The effects of two diets based on hydrolysed sugarcane bagasse (HSB) and whole cottonseed (WCS), with or without oat hay, were analyzed for the in situ disappearance of dry matter (DM), organic matter (OM) and neutral detergent fiber (NDF) of HSB. Six mature castrated rams with a permanent T ruminai cannula were used in a complete randomized split plot design. The incubation times were 3, 6, 9, 12, 24, 48 and 72h. The diet with oat hay showed higher disappearance indexes for the NDF fraction. Furthermore, the maximum degradation of HSB constituents was reached around 48h of incubation. The diets were T1=64% hydrolyzed sugarcane + 36% whole cottonseed and T2=14% hydrolyzed sugarcane bagasse + 36% cottonseed + 50% oat hay.