Soil CO2 emission as related to incorporation of sugarcane crop residues and aggregate breaking after rotary tiller

Soil tillage is a process that accelerates soil organic matter decomposition transferring carbon to atmosphere, mainly in the CO2 form. In this study, the effect of rotary tillage on soil CO2 emission was investigated, including the presence of crop residues on the surface.Emissions were evaluated during 15 days after tillage in 3 plots: 1) non-tilled and without crop residues on soil surface (NTwo), 2) rotary tiller without the presence of crop residues on soil surface (RTwo), and 3) rotary tiller with the presence of crop residues in soil surface (RTw). Emissions from the RTw plot were higher than the other plots, (0.777 g CO2 m-2 h-1), with the lowest emissions recorded in the NTwo plot (0.414 g CO2 m-2 h-1). Total emission indicates that the difference of C-CO2 emitted to atmosphere corresponds to 3% of the total additional carbon in the crop residues in the RTw plot compared to RTwo. The increase in the RTwo emission in comparison to NTwo was followed by changes in the aggregate size distribution, especially those with average diameter lower than 2 mm. The increase in emission from the RTw plot in relation to RTwo was related to a decrease in crop residue mass on the surface, and its higher fragmentation and incorporation in soil. When the linear correlation between soil CO2 emission, and soil temperature and soil moisture is considered, only the RTw treatment showed significant correlation (p<0.05) with soil moisture.

Development of experimental structure and influence of high CO2 concentration in maize cro

Maize is a C4 plant that shows few or no response to high [CO2]. Thus, this study aimed to analyze the photosynthetic rate and yield of maize under high [CO2] and develop open-top chambers (OTC) to create an atmosphere enriched with CO2. The experiment was conducted between October 2008 and March 2009. The OTCs were developed in modular scheme. Measurement of photosynthetic rates, transpiration, stomata conductance, grain yield and dry matter were performed. The experimental design was randomized blocks with four replications and three treatments: P1 - plants grown in OTC with 700 ppm [CO2], P2 - plants grown in OTC with environmental [CO2], and P3 - control, cultivated in open field. The results were analyzed by ANOVA and Tukey's test (Pr< 0.05). The chambers can reduce by 25% the photosynthetically active radiation and increase the air and leaf temperatures. Plants under high [CO2] (P1) showed the highest photosynthetic rates and the lowest stomata conductance and transpiration. The total weight of grains (g) and dry mass of shoots (g) showed no increases for P1, despite their higher photosynthetic rates.

Crop residues on short-term CO2 emissions in sugarcane production areas

The proper management of agricultural crop residues could produce benefits in a warmer, more drought-prone world. Field experiments were conducted in sugarcane production areas in the Southern Brazil to assess the influence of crop residues on the soil surface in short-term CO2 emissions. The study was carried out over a period of 50 days after establishing 6 plots with and without crop residues applied to the soil surface. The effects of sugarcane residues on CO2 emissions were immediate; the emissions from residue-covered plots with equivalent densities of 3 (D50) and 6 (D100) t ha-1 (dry mass) were less than those from non-covered plots (D0). Additionally, the covered fields had lower soil temperatures and higher soil moisture for most of the studied days, especially during the periods of drought. Total emissions were as high as 553.62 �� 47.20 g CO2 m-2, and as low as 384.69 �� 31.69 g CO2 m-2 in non-covered (D0) and covered plot with an equivalent density of 3 t ha-1 (D50), respectively. Our results indicate a significant reduction in CO2 emissions, indicating conservation of soil carbon over the short-term period following the application of sugarcane residues to the soil surface.

Influences of two CO2 concentrations and water availability on bean crop

This study was carried out to determine some physiological and phenological responses of the bean under high &#91;CO2&#93; and drought stress. The experiment was conducted from April to July 2009 in Vi��osa, Brazil. The open-top chambers were used to enrich the air with CO2, whereas the drought stress was applied between the flowering and the ripening. The randomized block design was used, with four replicates in the subplots. The following plots were &#91;CO2&#93; at 700ppm (F1) and &#91;CO2&#93; environmental (F2) and the subplots were well watering (S1) and drought stress (S2). The results were subjected to Anova and the Tukey test (P < 0.05). For the treatments F1S1 and F1S2 the photosynthetic rate showed increments of 59% and the transpiration reduction of 12%. The yield, leaf temperature and stomatal conductance were not significant different to high &#91;CO2&#93;, different from the dry matter, who showed increment of 20% (F1S1) and the water use efficiency who showed increase of 90% for high &#91;CO2&#93;. The osmotic potential was lower in plants under drought stress (F2S2 and F1S2), followed by plants under high &#91;CO2&#93; (F1S1). Despite the increment in photosynthesis, high &#91;CO2&#93; does not guarantee higher yield.

Emiss��o de CO2 do solo associada �� calagem em ��rea de convers��o de laranja para cana-de-a����car

A emiss��o de CO2 do solo (FCO2) em ��reas agr��colas �� resultante da intera����o de diversos fatores, sendo alterada pela pr��tica de manejos do solo e da cultura, al��m das condi����es edafoclim��ticas locais. Neste estudo, objetivou-se quantificar a FCO2 em fun����o da calagem e posi����o da aplica����o (antiga linha e entrelinha) da cultura da laranja em ��rea de convers��o para a cultura da cana-de-a����car, no munic��pio de Frutal-MG. Os tratamentos avaliados foram: Linha/CC (linha com aplica����o de calc��rio); Entrelinha/CC (entrelinha com aplica����o de calc��rio); Linha/SC (linha sem aplica����o de calc��rio), e Entrelinha/SC (entrelinha sem aplica����o de calc��rio). FCO2, temperatura do solo (Ts) e umidade do solo (Us) foram avaliadas durante 12 dias. O maior valor m��dio da FCO2 ao longo do per��odo de estudo foi observado no tratamento Linha/CC (9,63 ��mol m-2 s-1); e o menor, no tratamento Entrelinha/CC (5,92 ��mol m-2 s-1), segundo teste de Tukey. A FCO2 foi negativamente correlacionada �� Us na Linha/CC (r = - 0,56; p < 0,05) e na Linha/SC (r = - 0,66; p < 0,05). Entre a FCO2 e a Ts, verificou-se correla����o positiva e significativa na Linha/CC (r = 0,76; p < 0,001), na Linha/SC (r = 0,89; p < 0,001) e na Entrelinha/SC (r = 0,66; p < 0,05). Observou-se que a calagem e a posi����o de aplica����o (linha e entrelinha) influenciaram nas emiss��es de CO2 do solo.

Leaf concentrations of nitrogen and phosphorus in phaseolus vulgaris l. Plants under high CO2 concentration and drought stress

This study aims to evaluate the leaf concentration of nitrogen and phosphorus correlated to the production of photoassimilates in beans plants (Phaseolus vulgaris L.) under high &#91;CO2&#93; and drought stress. The experiment was conducted in Vi��osa (Brazil), during the period from April to July 2009, by using open-top chambers equipped with CO2 injection system. The drought stress was applied, through the irrigation suspension, during the period from flowering to maturation. The experimental design was randomized blocks in split-plot scheme with four replication, where the plots with plants grown in &#91;CO2&#93; of 700 mg L-1 and &#91;CO2&#93; environment of 380 mg L-1 and the subplots with plants with and without drought stress. The results were submitted to ANOVA and Tukey test (p < 0.05). In the plants under high &#91;CO2&#93; with and without drought stress, the photosynthetic rate increased by 59%, while the dry matter presented an increment of 20% in the plants under high &#91;CO2&#93; without drought stress. Reductions in &#91;N&#93; and &#91;P&#93; occurred in plants grown under high &#91;CO2&#93;, resulting in greater efficiency in nitrogen use for photosynthesis. The high &#91;CO2&#93; increase only the total dry matter and not the total mass of grains. The drought stress reduces the dry matter and mass of grain, even at high &#91;CO2&#93;.

Correla����o entre as press��es parciais de co2 no ar expirado e no sangue arterial, em porcas submetidas a pneumoperit��nio

OBJETIVO: As cirurgias realizadas por via laparosc��pica, que utilizam CO2 para realiza����o do pneumoperit��nio, cursam com hipercarbia. Esta altera����o pode ser estimada pela press��o parcial de CO2 no ar expirado. Este trabalho foi realizado com a finalidade de determinar se h�� correla����o entre press��o parcial de CO2 arterial e press��o parcial de CO2 no ar expirado nas cirurgias por via laparosc��pica. M��TODO: Distribu��ram-se 20 porcas em dois grupos: sem pneumoperit��nio e com pneumoperit��nio de 12 mmHg de press��o intra-abdominal. Foram medidas a press��o endotraqueal, satura����o arterial de O2, press��o parcial de CO2 no ar expirado, pH e press��o parcial de CO2 arteriais. RESULTADOS: Ap��s a realiza����o do pneumoperit��nio foi encontrado aumento significativo da press��o endotraqueal, da press��o parcial de CO2 no ar expirado e press��o parcial de CO2 arterial. CONCLUS��ES: Apesar de ter ocorrido aumento nas press��es parciais de CO2 tanto arterial quanto no ar expirado, n��o houve correla����o linear entre elas, n��o se podendo estimar em cirurgias por via laparosc��pica a press��o parcial de CO2 arterial pela press��o parcial de CO2 no ar expirado.

Avalia����o citom��trica dos adip��citos localizados no tecido subcut��neo da parede anterior do abdome ap��s infiltra����o percut��nea de CO2

OBJETIVO: Avaliar os efeitos da infiltra����o de di��xido de carbono em adip��citos presentes na parede abdominal. M��TODOS: Quinze volunt��rias foram submetidas a sess��es de infus��o de CO2 durante tr��s semanas consecutivas (duas sess��es por semana com intervalos de dois a tr��s dias entre cada sess��o). O volume de g��s carb��nico infundido por sess��o, em pontos previamente demarcados, foi sempre calculado com base na superf��cie da ��rea a ser tratada, com volume infundido fixo de 250 mL/100cm�� de superf��cie tratada. Os pontos de infiltra����o foram demarcados respeitando-se o limite eq��idistante 2cm entre eles. Em cada ponto se injetou 10mL, por sess��o, com fluxo de 80mL/min. Foram colhidos fragmentos de tecido celular subcut��neo da parede abdominal anterior antes e ap��s o tratamento. O n��mero e as altera����es histomorfol��gicas dos adip��citos (di��metro m��dio, per��metro, comprimento, largura e n��mero de adip��citos por campos de observa����o) foram mensurados por citometria computadorizada. Os resultados foram analisados com o teste t de Student pareado, adotando-se n��vel de signific��ncia de 5% (p<0,05). RESULTADOS: Encontrou-se redu����o significativa no n��mero de adip��citos da parede abdominal e na ��rea, di��metro, per��metro, comprimento e largura ap��s o uso da hipercapnia (p=0,0001). CONCLUS��O: A infiltra����o percut��nea de CO2 reduz a popula����o e modifica a morfologia dos adip��citos presentes na parede abdominal anterior.

Production of Mg(OH)2 from Mg-silicate rock for CO2 mineral sequestration

Sequestration of carbon dioxide in mineral rocks, also known as CO2 Capture and Mineralization (CCM), is considered to have a huge potential in stabilizing anthropogenic CO2 emissions. One of the CCM routes is the ex situ indirect gas/sold carbonation of reactive materials, such as Mg(OH)2, produced from abundantly available Mg-silicate rocks. The gas/solid carbonation method is intensively researched at ��bo Akademi University (��AU ), Finland because it is energetically attractive and utilizes the exothermic chemistry of Mg(OH)2 carbonation. In this thesis, a method for producing Mg(OH)2 from Mg-silicate rocks for CCM was investigated, and the process efficiency, energy and environmental impact assessed. The Mg(OH)2 process studied here was first proposed in 2008 in a Master���s Thesis by the author. At that time the process was applied to only one Mg-silicate rock (Finnish serpentinite from the Hitura nickel mine site of Finn Nickel) and the optimum process conversions, energy and environmental performance were not known. Producing Mg(OH)2 from Mg-silicate rocks involves a two-staged process of Mg extraction and Mg(OH)2 precipitation. The first stage extracts Mg and other cations by reacting pulverized serpentinite or olivine rocks with ammonium sulfate (AS) salt at 400 - 550 oC (preferably < 450 oC). In the second stage, ammonia solution reacts with the cations (extracted from the first stage after they are leached in water) to form mainly FeOOH, high purity Mg(OH)2 and aqueous (dissolved) AS. The Mg(OH)2 process described here is closed loop in nature; gaseous ammonia and water vapour are produced from the extraction stage, recovered and used as reagent for the precipitation stage. The AS reagent is thereafter recovered after the precipitation stage. The Mg extraction stage, being the conversion-determining and the most energy-intensive step of the entire CCM process chain, received a prominent attention in this study. The extraction behavior and reactivity of different rocks types (serpentinite and olivine rocks) from different locations worldwide (Australia, Finland, Lithuania, Norway and Portugal) was tested. Also, parametric evaluation was carried out to determine the optimal reaction temperature, time and chemical reagent (AS). Effects of reactor types and configuration, mixing and scale-up possibilities were also studied. The Mg(OH)2 produced can be used to convert CO2 to thermodynamically stable and environmentally benign magnesium carbonate. Therefore, the process energy and life cycle environmental performance of the ��AU CCM technique that first produces Mg(OH)2 and the carbonates in a pressurized fluidized bed (FB) were assessed. The life cycle energy and environmental assessment approach applied in this thesis is motivated by the fact that the CCM technology should in itself offer a solution to what is both an energy and environmental problem. Results obtained in this study show that different Mg-silicate rocks react differently; olivine rocks being far less reactive than serpentinite rocks. In summary, the reactivity of Mg-silicate rocks is a function of both the chemical and physical properties of rocks. Reaction temperature and time remain important parameters to consider in process design and operation. Heat transfer properties of the reactor determine the temperature at which maximum Mg extraction is obtained. Also, an increase in reaction temperature leads to an increase in the extent of extraction, reaching a maximum yield at different temperatures depending on the reaction time. Process energy requirement for producing Mg(OH)2 from a hypothetical case of an iron-free serpentine rock is 3.62 GJ/t-CO2. This value can increase by 16 - 68% depending on the type of iron compound (FeO, Fe2O3 or Fe3O4) in the mineral. This suggests that the benefit from the potential use of FeOOH as an iron ore feedstock in iron and steelmaking should be determined by considering the energy, cost and emissions associated with the FeOOH by-product. AS recovery through crystallization is the second most energy intensive unit operation after the extraction reaction. However, the choice of mechanical vapor recompression (MVR) over the ���simple evaporation��� crystallization method has a potential energy savings of 15.2 GJ/t-CO2 (84 % savings). Integrating the Mg(OH)2 production method and the gas/solid carbonation process could provide up to an 25% energy offset to the CCM process energy requirements. Life cycle inventory assessment (LCIA) results show that for every ton of CO2 mineralized, the ��AU CCM process avoids 430 - 480 kg CO2. The Mg(OH)2 process studied in this thesis has many promising features. Even at the current high energy and environmental burden, producing Mg(OH)2 from Mg-silicates can play a significant role in advancing CCM processes. However, dedicated future research and development (R&D) have potential to significantly improve the Mg(OH)2 process performance.

CO2 sparging for improving the filtration properties of iron ore slurries

Iron ore treatment processes are usually continuous and high tonnage and filtration equipment has to meet these requirements. In magnetite (Fe3O4) treatment process continuous rotary disc filters are often used for filtration. Carbon dioxide (CO2) treatment is a fairly novel and un-known filtration enhancing process. The interest to use CO2 is quite high because CO2 is a greenhouse gas that is abundant, readily available and capture and use of CO2 would be environmentally beneficial. The focus of this thesis was to investigate if CO2 could be used to enhance the filtration of magnetite with ceramic disc filter. Previous studies have suggested that CO2 could be used to enhance the filtration properties of different iron ores thus increasing the filtration capacity. In the literature part, the basic theory of filtration and the particle properties affecting filtration were discussed. The basic steps of a typical ore treatment process were presented. The reasons why CO2 might enhance the filtration properties of different ores were investigated. A literature survey of earlier studies of CO2 addition as a filter aid was presented and the basic chemical properties and reactions of CO2 were also discussed. The experimental part was done at the LUT Laboratory of Separation Technology using different magnetite samples from the industry. The filtration experiments indicated that CO2 had a positive influence on the filtration properties of magnetite slurry. Zeta potential of untreated and CO2 treated magnetite was measured and CO2 treated magnetite had lower zeta potential values than the untreated magnetite. The filtration capacity was increased while the cake moisture levels were only slightly increased.

Valmistusteknillinen n��k��kulma hitsattaessa ruostumattomia ter��ksi�� CO2-laserilla

T��m�� kandidaatinty�� on valmistuksellinen n��k��kulma ruostumattoman ter��ksen CO2-laserhitsauksen perusteisiin. Tavoitteena on perehdytt���� lukija ruostumattoman ter��ksen CO2-laserhitsauksen valmistusteknillisiin vaatimuksiin ja teollisuuden sovelluksiin.

Efeito da pressuriza����o com CO2 sobre o pH da ��gua

Durante a fase de desenvolvimento de novos produtos fitossanit��rios �� comumente utilizado o pulverizador a press��o constante, pressurizado com CO2. O g��s carb��nico pode provocar a acidifica����o da ��gua e afetar o comportamento do composto que est�� sendo avaliado. No presente trabalho, amostras de ��gua de 30 diferentes fontes foram pressurizadas com CO2 durante cinco minutos, at�� 275 kPa (40 lbf/pol.2), e o pH foi medido na ��gua que saiu do bico e na ��gua no inteior do tanque do pulverizador. Os resultados mostraram redu����o nos valores do pH em toda as amostras . Os valores do pH elevaram-se ligeiramente ap��s a sa��da da ��gua pelo bico do pulverizador. A redu����o, em alguns casos, foi marcante, atingindo 4,91 unidades de pH no caso mais dr��stico. Esses dados levam a recomendar cautela na interpreta����o dos resultados obtidos com o uso dos pulverizadores pressurizados com o g��s carb��nico.

Libera����o de CO2, biomassa microbiana e f��sforo dispon��vel em solo adicionado de mat��ria seca de poaia-branca

O presente experimento, inteiramente casualizado, foi desenvolvido em condi����es de laborat��rio no Departamento de Defesa Fitossanit��ria, FCA/UNESP - Botucatu, entre julho e setembro de 1992. Amostras de Areia Quartzosa equivalentes �� 40 g de terra seca �� 105 oC �� 2 com ou sem adi����o de 1,9 g de mat��ria seca de plantas de poaia-branca (Richardia brasiliensis), 0,19 g de nitrog��nio (NH4)2SO4 e 0,88 g de apatita de Arax��, foram incubadas no escuro a 25 o C �� 2 , com umidade mantida a 60% da capacidade de reten����o de ��gua. Durante a incuba����o, determinou-se o CO2 liberado, utilizando-se o m��todo de reten����o em NAOH seguida de titulometria com HCl; a biomassa microbiana, m��todo de fumiga����o-incuba����o; o pH e a quantidade de f��sforo extra��do por resina. A maior libera����o de CO2 ocorreu durante os dez primeiros dias de incuba����o, com 77% do total de carbono liberado nos tratamentos com adi����o de poaia, e 37% nos tratamentos sem adi����o da mesma. A libera����o de CO2 foi 57 vezes maior nos tratamentos com poaia em rela����o ao controle. A poaia tamb��m provocou aumentos na biomassa microbiana (m��dia de 8 vezes a biomassa do tratamento controle), e a adi����o de nitrog��nio e/ou fosfato de rocha junto �� poaia antecipou os picos de forma����o de biomassa de 20 para 10 dias de incuba����o. Os n��veis de f��sforo dispon��vel foram maiores no tratamento com adi����o de fosfato de rocha apenas. A poaia tamb��m alcalinizou o sistema, n��o permitindo desta forma, observar-se rela����o significativa entre pH e teor de f��sforo dispon��vel.

Avalia����o da decomposi����o de plantas aqu��ticas no solo atrav��s da libera����o de CO2

O objetivo deste trabalho foi avaliar a decomposi����o de tr��s esp��cies de plantas aqu��ticas imersas, incorporadas ao solo, provenientes do controle mec��nico, em reservat��rios de usinas hidrel��tricas. O estudo foi realizado em casa de vegeta����o, localizada no N��cleo de Pesquisas Avan��adas em Matologia (NUPAM) da FCA/Unesp-Botucatu. A avalia����o foi conduzida em vasos contendo 14 kg de solo, com tr��s incorpora����es de 50 e 100 t MF de plantas ha-1, sob duas condi����es de solo: seco e ��mido. Com a simula����o de descarte da biomassa coletada e incorporada ao solo, p��de-se conhecer, atrav��s da libera����o de CO2, a degrada����o de tr��s esp��cies de macr��fitas aqu��ticas submersas. Para quantifica����o do CO2 liberado, em cada vaso foi acondicionado um frasco com solu����o de NaOH, sendo, logo ap��s, lacrados e incubados por 24 horas; em seguida, foram titulados com HCl. Para ajuste e interpola����o dos dados, estes foram analisados seguindo modelo de Mitscherlich, com algumas modifica����es. As libera����es acumuladas em solo ��mido foram de 1.294 e 1.582 kg CO2 ha-1, sendo 6,2 e 5,6 vezes superiores ao ocorrido em solo seco, para 50 e 100 t MF ha-1, respectivamente, observando-se que cerca de 55% da libera����o de CO2 ocorreu nos primeiros 30 dias. Pode-se concluir que o solo seco �� a melhor condi����o para descarte e incorpora����o da biomassa, por��m dever�� existir um sistema de irriga����o para que o processo de degrada����o da biomassa incorporada seja acelerado.

Evolu����o de CO2 e atividades enzim��ticas em amostras de solo tratado com herbicidas

Os efeitos dos herbicidas bentazon, metolachlor, trifluralin, imazethapyr, imazethapyr+lactofen, haloxyfop-methyl, glyphosate e chlorimuron-ethyl, testados em duas concentra����es (duas e dez vezes a dose m��dia recomendada por hectare), sobre a atividade microbiana foram estudados em amostras de solo que nunca haviam recebido tratamento com pesticidas. Como bioindicadores, utilizou-se a respira����o microbiana, quantificando a emiss��o de CO2 aos 2, 4, 8, 12, 16, 20 e 24 dias ap��s incuba����o, a atividade da enzima desidrogenase e a hidr��lise de diacetato de fluoresce��na (FDA), aos 8 e 28 dias. Bentazon e a mistura de imazethapyr+lactofen na maior concentra����o e o haloxyfop-methyl nas duas concentra����es apresentaram efeitos inibit��rios na respira����o ed��fica, embora diferentes em ��poca e dura����o do efeito. Nenhum dos tratamentos herbicidas afetou a hidr��lise da FDA. A atividade da desidrogenase foi inibida, o que foi verificado em an��lise realizada aos oito dias,nas amostras de solo com alta concentra����o de bentazon e imazethapyr; no entanto, foi estimulada nos tratamentos com baixa concentra����o de metolachlor e imazethapyr e na maior concentra����o de glyphosate. A respira����o basal e a atividade da desidrogenase mostraram maior sensibilidade na detec����o de efeitos dos herbicidas sobre a microbiota do solo que as determina����es da hidr��lise de FDA. Apenas foi encontrada correla����o significativa entre a atividade da desidrogenase e a respira����o basal aos oito dias de incuba����o. Os resultados destacam a import��ncia da considera����o de m��ltiplos indicadores na avalia����o dos efeitos de herbicidas na microbiota do solo.