Production and dissolution rates of earthworm-secreted calcium carbonate

Earthworms secrete granules of calcium carbonate. These are potentially important in soil biogeochemical cycles and are routinely recorded in archaeological studies of Quaternary soils. Production rates of calcium carbonate granules by the earthworm Lumbricus terrestris L. were determined over 27 days in a range of soils with differing chemical properties (pH, organic matter content, water holding capacity, bulk composition, cation exchange capacity and exchangeable cations). Production rate varied between soils, lay in the range 0–0.043 mmolCaCO3 (0–4.3 mg) earthworm−1 d−1 with an average rate of 8 × 10−3 mmolCaCO3 (0.8 mg) earthworm−1 d−1 and was significantly correlated (r = 0.68, P ≤ 0.01) with soil pH. In a second experiment lasting 315 days earthworms repeatedly (over periods of 39–57 days) produced comparable masses of granules. Converting individual earthworm granule production rates into fluxes expressed on per hectare of land per year basis depends heavily on estimates of earthworm numbers. Using values of 10–20 L. terrestris m−2 suggests a rate of 18– 3139 molCaCO3 ha−1 yr−1. Data obtained from flow-through dissolution experiments suggest that at near neutral pH, granule geometric surface areanormalised dissolution rates are similar to those for other biogenic and inorganic calcium carbonate. Fits of the data to the dissolution relationship r = k(1 − ˝)n where r = dissolution rate, k = a rate constant, ˝ = relative saturation and n = the reaction order gave values of k = 1.72 × 10−10 mol cm−2 s−1 and n = 1.8 for the geometric surface area-normalised rates and k = 3.51 × 10−13 mol cm−2 s−1 and n = 1.8 for the BET surface area-normalised rates. In 196 day leaching column experiments trends in granule dissolution rate referenced to soil chemistry corresponded to predictions made by the SLIM model for dissolution of limestone in soil. If soil solution approaches saturation with respect to calcium carbonate granule dissolution will slow or even stop and granules be preserved indefinitely. Granules have the potential to be a small but significant component of the biogeochemical cycling of C and Ca in soil.

Spectral design of temperature-invariant narrow bandpass filters for the mid-infrared

The ability of narrow bandpass filters to discriminate wavelengths between closely-separated gas absorption lines is crucial in many areas of infrared spectroscopy. As improvements to the sensitivity of infrared detectors enables operation in uncontrolled high-temperature environments, this imposes demands on the explicit bandpass design to provide temperature-invariant behavior. The unique negative temperature coefficient (dn/dT<0) of Lead-based (Pb) salts, in combination with dielectric materials enable bandpass filters with exclusive immunity to shifts in wavelength with temperature. This paper presents the results of an investigation into the interdependence between multilayer bandpass design and optical materials together with a review on invariance at elevated temperatures.

Terrestrial exposure of oilfield flowline additives diminish soil structural stability and remediative microbial function

Onshore oil production pipelines are major installations in the petroleum industry, stretching many thousands of kilometres worldwide which also contain flowline additives. The current study focuses on the effect of the flowline additives on soil physico-chemical and biological properties and quantified the impact using resilience and resistance indices. Our findings are the first to highlight deleterious effect of flowline additives by altering some fundamental soil properties, including a complete loss of structural integrity of the impacted soil and a reduced capacity to degrade hydrocarbons mainly due to: (i) phosphonate salts (in scale inhibitor) prevented accumulation of scale in pipelines but also disrupted soil physical structure; (ii) glutaraldehyde (in biocides) which repressed microbial activity in the pipeline and reduced hydrocarbon degradation in soil upon environmental exposure; (iii) the combinatory effects of these two chemicals synergistically caused severe soil structural collapse and disruption of microbial degradation of petroleum hydrocarbons.

Hydrocarbon biodegradation and soil microbial community response to repeated oil exposure

Bioremediation strategies continue to be developed to mitigate the environmental impact of petroleum hydrocarbon contamination. This study investigated the ability of soil microbiota, adapted by prior exposure, to biodegrade petroleum. Soils from Barrow Is. (W. Australia), a class A nature reserve and home to Australia’s largest onshore oil field, were exposed to Barrow production oil (50 ml/kg soil) and incubated (25 °C) for successive phases of 61 and 100 days. Controls in which oil was not added at Phase I or II were concurrently studied and all treatments were amended with the same levels of additional nutrient and water to promote microbial activity. Prior exposure resulted in accelerated biodegradation of most, but not all, hydrocarbon constituents in the production oil. Molecular biodegradation parameters measured using gas chromatography–mass spectrometry (GC–MS) showed that several aromatic constituents were degraded more slowly with increased oil history. The unique structural response of the soil microbial community was reflected by the response of different phospholipid fatty acid (PLFA) sub-classes (e.g. branched saturated fatty acids of odd or even carbon number) measured using a ratio termed Barrow PLFA ratio (B-PLFAr). The corresponding values of a previously proposed hydrocarbon degrading alteration index showed a negative correlation with hydrocarbon exposure, highlighting the site specificity of PLFA-based ratios and microbial community dynamics. B-PLFAr values increased with each Phase I and II addition of production oil. The different hydrocarbon biodegradation rates and responses of PLFA subclasses to the Barrow production oil probably relate to the relative bioavailability of production oil hydrocarbons. These different effects suggest preferred structural and functional microbial responses to anticipated contaminants may potentially be engineered by controlled pre-exposure to the same or closely related substrates. The bioremediation of soils freshly contaminated with petroleum could benefit from the addition of exhaustively bioremediated soils rich in biota primed for the impacting hydrocarbons.

Estudo geotécnico sobre a erodibilidade de solos residuais não saturados

A erodibilidade, particularizada como a susceptibilidade a erosão hídrica por fluxo superficial concentrado, é uma das propriedades de comportamento dos solos de maior complexidade pelo grande número de variáveis intervenientes. Estudada por diferentes áreas do conhecimento (Agronomia, Hidráulica, Geologia de Engenharia e Engenharia Geotécnica), tem no meio geotécnico a maior lacuna na sua quantificação e entendimento dos mecanismos envolvidos. O presente trabalho apresenta um estudo sobre a erodibilidade de solos residuais tropicais e subtropicais não saturados a partir de quatro perfis representativos dos processos erosivos e solos envolvidos na Região Metropolitana de Porto Alegre. Os solos dos principais horizontes de cada um destes perfis foram caracterizados física, química e mineralogicamente. As propriedades de resistência ao cisalhamento e colapsibilidade foram avaliadas por ensaios de cisalhamento direto convencionais e com controle de sucção e por ensaios de colapsibilidade em oedômetros, respectivamente. A erodibilidade foi avaliada em laboratório, diretamente por meio de ensaios de Inderbitzen e indiretamente por diferentes critérios e parâmetros baseados em outras características físicas e propriedades dos solos. A análise conjunta do comportamento dos solos em campo frente a erosão, da avaliação direta e indireta da erodibilidade e das propriedades geomecânicas investigadas conduziram à formulação de uma proposta de abordagem geotécnica para a erodibilidade dos solos residuais tropicais e subtropicais não saturados. Nesta proposta destaca–se a avaliação direta da erodibilidade por ensaios de Inderbitzen e a indicação de solos potencialmente erodíveis baseada no teor de finos, na plasticidade, no parâmetro K da USLE, na Razão de Dispersão de Middleton, na classificação e critério de erodibilidade MCT e na variação da coesão com a saturação pelo parâmetro variação de coesão (Δc) proposto. A proposta de abordagem geotécnica para a previsão da erodibilidade dos solos visa dotar o engenheiro geotécnico de uma ferramenta destinada à avaliação do potencial erosivo dos terrenos antes de uma iniciativa de ocupação urbana ou implantação de qualquer outra obra de engenharia. Esta avaliação é o passo inicial no direcionamento de medidas preventivas e que visem minimizar o impacto da obra ao meio físico natural, no que se refere a erosão hídrica por fluxo superficial concentrado.

Avaliação da correlação entre os parâmetros, carbono orgânico total e elementos tóxicos, em solo de um posto de serviço e revenda de combustíveis

Today a major responsibility for the contamination of soil and groundwater and surface water are establishments known as gas stations of fuel which has attracted increasing attention from both the general population as the state agencies of environmental control due to leaks in storage tanks and mainly to disruption of pipe corrosion of tanks and pumping. Other services, like oil changes and car wash are also causes for concern in this type of establishment. These leaks can cause or waste produced, and the contamination of aquifers, serious health problems and public safety, since most of these stations located in urban areas. Based on this, the work was to evaluate soil contamination of a particular service station and fuel sales in the city of Natal, through the quantification of heavy metals like Cd, Cu, Cr, Ni, Pb, Zn of total organic carbon (TOC) and organic matter using different techniques such as optical emission spectrometry with inductively coupled plasma source (ICP OES), Total Organic Carbon analyzer and gravimetric analysis respectively. And also to characterize the soil through particle size analysis. Samples were taken in 21 georeferenced points and collected in the same period. The soils sampled in sampling stations P3, P5, P6, P10, P11, P12, P13, P14, P15, P17, P18 and P20 showed the smallest size fractions ranging from fine sand to medium sand. The other study sites ranged from fine sand to medium sand, except the point P8 showed that only the type size medium sand and P19, indicating a particle size of the coarse type. The small correlation of organic matter with the elements studied in this work suggests that these are not of anthropogenic origin but geochemical support

Desenvolvimento de sistemas magnéticos com potencialidades terapêuticas para vetorização de fármacos

Magnetic targeting is being investigated as a means of local delivery of drugs, combining precision, minimal surgical intervention, and satisfactory concentration of the drug in the target region. In view of these advantages, it is a promising strategy for improving the pharmacological response. Magnetic particles are attracted by a magnetic field gradient, and drugs bound to them can be driven to their site of action by means of the selective application of magnetic field on the desired area. Helicobacter pylori is the commonest chronic bacterial infection. The treatment of choice has commonly been based upon a triple therapy combining two antibiotics and an anti-secretory agent. Furthermore, an extended-release profile is of utmost importance for these formulations. The aim of this work was to develop a magnetic system containing the antibiotic amoxicillin for oral magnetic drug targeting. First, magnetic particles were produced by coprecipitation of iron salts in alkaline medium. The second step was coating the particles and amoxicillin with Eudragit® S-100 by spray-drying technique. The system obtained demonstrated through the characterization studies carried out a possible oral drug delivery system, consisting in magnetite microparticles and amoxicillin, coated with a polymer acid resistant. This system can be used to deliver drugs to the stomach for treatment of infections in this organ. Another important finding in this work is that it opens new prospects to coat magnetic microparticles by the technique of spray-drying.

Compactação do solo no desenvolvimento radicular e na produtividade da soja

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

Nível crítico de fósforo no solo paraPanicum maximum Jacq. cv. Tanzânia

Foram avaliados os efeitos da aplicação de fósforo (P) em solo argiloso, de textura média e arenoso, sobre a produção de matéria seca de Panicum maximum Jacq. cv. Tanzânia. O ensaio foi conduzido em casa de vegetação, em vasos de plástico contendo 10 dm³ de solo, em esquema fatorial e delineamento inteiramente ao acaso. Após calagem para V = 70% e aplicação de 0, 35, 70, 105 e 140 mg/dm³ de P, o solo foi umedecido, e depois de 30 dias, secado e amostrado. O ensaio foi conduzido por 76 dias, a partir da emergência das plântulas, com o primeiro corte aos 48 dias, a 10 cm do solo, e o segundo, aos 76,rente ao solo. Com a aplicação de P houve aumento de produção de matéria seca, e o maior acréscimo ocorreu com a aplicação de 35 mg/dm³. A maior produção foi obtida no solo de textura média. O teor de P nas plantas estava adequado nos solos arenoso e argiloso. No de textura média, ele diminuiu com o aumento da produção,caracterizando efeito de diluição. Com aprodução relativa e o teor de P de cada solo, foi determinado o nível crítico de 38 mg/dm³ de P extraído por resina.

Condicionadores químicos do solo e seus efeitos sobre os Índices físicos

Dois condicionadores químicos, a carboximetilcelulose, nas dosagens de 0,1% e 0,25% em relação ao peso do solo seco, e o silicato de sódio, de relação sílica-álcali igual a 3,2, a 0,6% e 1,2% em peso, foram pesquisados quanto aos seus efeitos sobre os índices físicos dos solos argiloso e barro arenoso empregados neste trabalho. Os dados obtidos foram estatisticamente analisados e os resultados permitiram que se chegassem a algumas conclusões. O tratamento 0,25% de carboximetilcelulose diminuiu o peso específico aparente seco e aumentou, consequentemente, o índice de vazios e porosidade dos solos estudados. O efeito dos tratamentos 1,2% de silicato de sódio e 0,1% de carboximetilcelulose sobre o peso específico aparente seco dos solos argilosos e barro arenoso, respectivamente, foi semelhante ao do tratamento 0,25% de carboximetilcelulose.

Influência do estresse hídrico e salino na germinação de urochloa decumbens e urochloa ruziziensis

Studies of the germination response of seeds subjected to artificial stresses are provided tools for better understanding of the survivability and adaptation of these species in natural stress conditions such as drought or saline soils, common in agricultural and forest regions, contributing significantly to the development of management strategies. Thus, the purpose of this study was to evaluate the possible effects of water and salt stress on germination of Urochloa decumbens and Urochloa ruziziensis. The test was conducted at the Faculty of Technology of São Paulo, campus of Capon Bonito. The seeds were sown with four replicates of 50 seeds in paper soaked in solutions with the potentials of 0.0, -0.2, -0.4 and -0.8 MPa, induced with polyethylene glycol (PEG 6000) and NaCl. The germination test was conducted at 25 degrees C in the presence of light, evaluating the first test score at seven days after sowing, and weekly germination (normal seedlings) until 35 days. We calculated the index of germination rate. The results allowed the conclusion that water stress causes a greater reduction in force, speed of germination and cumulative germination of seeds of U. decumbens and U. ruziziensis than salt stress. The species U. decumbens showed higher tolerance to water and salt stresses.

Estado nutricional e componentes da produção de plantas de pimentão conduzidas em sistema de fertirrigação durante indução de estresse salino em cultivo protegido

O uso das técnicas de fertirrigação em ambiente protegido vem aumentando no Brasil devido à praticidade de condução e redução dos custos de produção. Apesar dessas vantagens, salienta-se que esta prática também pode trazer riscos, principalmente pelo acúmulo de sais na superfície do solo e na região periférica do bulbo radicular. em caso de salinização do solo pelo manejo incorreto do sistema podem ocorrer alterações na disponibilidade de nutrientes, com conseqüências fisiológicas no desenvolvimento das plantas. Neste trabalho, utilizou-se o pimentão (Capsicum annuum L.) como planta-modelo para estudos da interferência da salinidade na nutrição das plantas, pela alteração da condutividade elétrica (CE) na solução do solo. Os resultados revelaram indícios de antagonismo entre nutrientes, notadamente entre as formas catiônicas em razão do aumento da concentração de KCl nos tratamentos com alta CE. A suplementação do solo com adubo orgânico não atenuou os efeitos do aumento da concentração salina e os valores extremos de CE interferiram drasticamente na produção.

Influência de atividades antrópicas sobre a salinização da água em área de dunas no Município de Guamaré RN

The municipality of Guamaré is located on the north coast of RN, Salineira zone, with a land area of 259 km2 and a population of approximately 12,500 inhabitants (IBGE, 2010). Presents strong morphological instability caused mainly by the influence of human activities in the region. The present study aims to assess the existing levels of salts in the springs of the region, by evaluating the electrical conductivity, pH, salinity, chlorides, hardness, calcium, magnesium and heavy metals in the water. The collection and analysis methods adopted in the survey are based on APHA (2005). The electrical conductivity, salinity and chloride behaved similarly throughout the study. Some points suffered the direct effect of the salt ponds and others. Given the existence of a drainage ditch between the saline and monitored region, there was little change in the environment, including the native vegetation. The opposite situation occurred in farms where the region is fully committed local vegetation and water holes and wells used in the past for domestic use are practically disabled (high salt content). In Rio Miassaba formation of an estuary is reversed, with the farther out from the sea showing higher salt concentracions, which may be associated with the discharge of organic matter and natural evaporation rate. In periods of no rainfall had a few points higher than the levels of salts found in seawater and may be associated with high evaporation in the region. Detected a positive factor is the high resilience and reducing salt, after periods of rainfall incidence

Respostas morfológicas em Guibourtia hymenifolia (Moric.) J. Leonard (Fabaceae) e Genipa americana L. (Rubiaceae), submetidas ao estresse por deficiência nutricional e alagamento do substrato

Foram estudadas as respostas plásticas em duas espécies nativas. em G. hymenifolia, não foram verificadas modificações morfológicas significativas, exceto quanto ao conteúdo de amido de reserva, que foram menores nos lotes capacidade de campo desnutrido (CCD) e alagamento desnutrido (ALD). em Genipa americana os indivíduos do lote (CCN - capacidade de campo nutrido) exibiram raízes adventícias com aerênquima distinto, mais freqüentes nas plantas do lote controle submetidas ao alagamento (ALN - alagado nutrido). Nessa última espécie, nos lotes ALN, verificou-se o surgimento de aerênquima lisógeno no caule, além da hipertrofia lenticelar. A diversidade de respostas às condições de alagamento, aliada à uma larga ocorrência de populações de Genipa americana em áreas sazonalmente inundadas, como por exemplo no Pantanal de Miranda-MS, sugere um complexo de interações entre caractes adaptativos morfológicos e fisiológicos, sendo o potencial gênico fundamental neste tipo de resposta.

Aplicação de métodos geofísicos no monitoramento de área contaminada sob atenuação natural

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)