Monitoring the impact of fertilizers on soil leachates using sequential injection analysis for multiparametric determination

info:eu-repo/semantics/publishedVersio

Análise estrutural de aduela prefabricada em betão reforçado com fibras para o revestimento de túneis

A presente comunicação descreve a investigação desenvolvida no âmbito da análise estrutural de aduelas prefabricadas em betão reforçado com fibras (BRFA), com comportamento melhorado ao fogo, para os casos de carga a que estão sujeitas durante a sua vida útil. Os ensaios necessários à caracterização das propriedades do BRFA desenvolvido são descritos e os resultados obtidos são apresentados

Biomass production of Piatã grass (Brachiaria Brizantha cv. Piatã) on different degree days in Brazilian Northeast.

Brachiaria brizantha cv. Piatã was released from a Brazilian breeding program of Brachiaria genus to be a new option of forage plant for use in grasslands. This cultivar has been presented interesting strategy to persist on higher temperatures and water stress and can be useful for systems when water is not available in high quantity. For this reason this trial aimed quantifies biomass production on different degree days in Brazilian Northeast. This research was carried out in cultivate irrigated Brachiaria pasture at Embrapa Goats and Sheep (3º 41'S e 40º 20'W). Four experimental treatments were evaluated: 250ºC, 500ºC, 750ºC and 1,000ºC of degree days. Experimental design used was block complete randomized, with subplots and four repetition by plot. Degree days were obtained from temperature data collected in automatic station, daily. When amount of degree days was get in each treatment, grasses were cut and taken weight to estimate total biomass (kg/ha). Part of forage was dried in oven (55ºC) to get dry matter perceptual and another part was separate in stems, leaves and death material. Parameters evaluated were total biomass production (TBP) in kg/ha, leaves biomass (LB) in kg/ha, stem biomass (SB) in kg/ha and death material (DM) kg/ha. Data was collect for four cycles during dry season in 2012. Data was submitted to variance analysis (F test, p<0.05) and regression. There were significant effects (p<0.05) from treatment to biomass total, leaves biomass and death material. All parameter presented a linear pattern (YTBP= 1.26x + 23.95; R²= 0.99; YLB=0.94 x + 82.91; R2 =0.98; YDM= 0.04x ? 3.51; R²= 0.84). There were significant effect of interaction cycle and treatment to steam production during cycles two (C2) (YC2SB= -54.49 + 0.18x e R²= 0.73) and three (C3) (YC3SB = -206.28 + 0.76x e R²= 0.85). Most biomass produced was 1,284 kg/ha in 1,000ºC. This result occurred about 30 days. During a complete dry season in Northeast Region estimated a total biomass production from Piatã grass about 10.3t/ha while in native vegetation is less than 2t. Small cultivate areas with Brachiaria Piatã can produce forage sufficient to reduce grazing pasture in large native areas especially during dry season. 80% of forage total produced was basically leaves. Leaves are most nutritive part of plant. Piatã grass presented a high capacity to produce leaves in dry and high temperature environments. Most stem production during cycle two was 125.51 kg/ha while cycle three was 553.72kg/ha. During cycle three was observed increase cloudiness, probably affected stem production. Finally, There was produced just 36,5kg/ha death material in 1,000ºC. There is a linear effect of degree day on biomass production until 1,000ºC in Brazilian Northeast

Production of ornamental sunflower irrigated with oilfield produced water in the Brazilian semiarid region.

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Single flow-based system for the automatic multiparametric nutrients (NPK & Fe) assessment in soil leachates

A multiparametric sequential injection system for the determination of phosphate, nitrite, nitrate, potassium, and iron(III) in a single manifold was developed. The main goal of the proposed method was to develop an efficient tool to assess a number of essential chemical compounds in soils, providing the corresponding information on soil fertility and, additionally, information on possible groundwater contamination. The method was applied for the quantification of the aforementioned parameters in simulated leachates produced in laboratory-scale core columns. The relative standard deviations of ten replicate analyses of a standard were: 6% for phosphate; 2% for nitrite; 2% for nitrate; 5% for potassium; and 6% for iron(III). The limits of detection and quantification were: 2.15 and 7.18 μmol/L for phosphate determination; 0.22 and 0.73 μmol/L for nitrite determination; 3.42 and 8.00 μmol/L for nitrate determination; 39 μmol/L (limit of detection) for potassium determination; and 0.46 and 1.85 μmol/L for iron(III) determination. The sequential injection system was successfully applied for the quantification of multiple soil chemical components (PO43−, NO2−, NO3−, K+, and Fe3+) in soil leachates. The analysis of a sample, involving all the analytes, has a duration of 28 min.info:eu-repo/semantics/publishedVersio

Stokes' Drift of linear Defects

A linear defect, viz. an elastic string, diffusing on a planar substrate traversed by a travelling wave experiences a drag known as Stokes' drift. In the limit of an infinitely long string, such a mechanism is shown to be characterized by a sharp threshold that depends on the wave parameters, the string damping constant and the substrate temperature. Moreover, the onset of the Stokes' drift is signaled by an excess diffusion of the string center of mass, while the dispersion of the drifting string around its center of mass may grow anomalous.Comment: 14 pages, no figures, to be published in Phys.Rev.