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1.
J Environ Manage ; 288: 112304, 2021 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-33773210

RESUMO

Enhanced-efficiency nitrogen (N) fertilizers, such as those containing nitrification or urease inhibitors, can mitigate the carbon (C) footprint linked to the production of bioenergy crops through a reduction in direct nitrous oxide (N2O) emissions and indirect N2O losses. These indirect emissions are derived from ammonia (NH3) volatilization, which also have important environmental and health implications. The evaluation of the global warming potential (GWP) of different N sources using site-specific data of yield and direct and indirect emissions is needed for oilseed rape under rainfed semi-arid conditions, especially when meteorological variability is taken into account. Using urea as a N source, the N2O mitigation efficacy of the urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) alone or combined with the nitrification inhibitor 2-(3,4-dimethyl-1H-pyrazol-1-yl) succinic acid isomeric mixture (DMPSA) was evaluated under field conditions in a rainfed oilseed rape (Brassica napus L.) crop. Two additional N sources from calcium ammonium nitrate (CAN), with and without DMPSA, were included. The GWP of the treatments was estimated considering the emissions from inputs, operations and other direct and indirect emissions of greenhouse gases (GHGs), such as methane (CH4) and the volatilization of NH3. We also measured the abundance of key genes involved in nitrification and denitrification to improve the understanding of N2O emissions on a biochemical basis under the conditions of our study. The results show that due to the intense rainfall after fertilization and a rewetting event, N2O losses from fertilizers without inhibitors were greater than those previously reported under Mediterranean conditions, while NH3 losses were low and not affected by the urease inhibitor. The cumulative N2O emissions (which were greatly influenced by a rewetting peak three months after fertilization) from the urea fertilization were significantly higher than those from CAN. The presence of NBPT significantly reduced N2O losses by an average of 71%, with respect to urea. The use of DMPSA with CAN resulted in an abatement of N2O emissions (by 57%) and a significant increase in oil yield in comparison with CAN alone. All inhibitor-based treatments were effective in abating N2O emissions during the rewetting peak. The abundances of the nitrifier and denitrifier communities, especially ammonia-oxidizing bacteria (AOB), significantly decreased relative to the urea or CAN treatments as inhibitors were applied. Under the conditions of our study, the sustainability of a bioenergy crop such as oilseed rape can be improved by using inhibitors because they mitigated N2O emissions and/or enhanced the oil yield.


Assuntos
Brassica napus , Óxido Nitroso , Agricultura , Fertilizantes/análise , Aquecimento Global , Óxido Nitroso/análise , Solo
2.
Glob Chang Biol ; 24(10): 4505-4520, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-29995346

RESUMO

Fire is a major factor controlling global carbon (C) and nitrogen (N) cycling. While direct C and N losses caused by combustion have been comparably well established, important knowledge gaps remain on postfire N losses. Here, we quantified both direct C and N combustion losses as well as postfire gaseous losses (N2 O, NO and N2 ) and N leaching after a high-intensity experimental fire in an old shrubland in central Spain. Combustion losses of C and N were 9.4 Mg C/ha and 129 kg N/ha, respectively, representing 66% and 58% of initial aboveground vegetation and litter stocks. Moreover, fire strongly increased soil mineral N concentrations by several magnitudes to a maximum of 44 kg N/ha 2 months after the fire, with N largely originating from dead soil microbes. Postfire soil emissions increased from 5.4 to 10.1 kg N ha-1  year-1 for N2 , from 1.1 to 1.9 kg N ha-1  year-1 for NO and from 0.05 to 0.2 kg N ha-1  year-1 for N2 O. Maximal leaching losses occurred 2 months after peak soil mineral N concentrations, but remained with 0.1 kg N ha-1  year-1 of minor importance for the postfire N mass balance. 15 N stable isotope labelling revealed that 33% of the mineral N produced by fire was incorporated in stable soil N pools, while the remainder was lost. Overall, our work reveals significant postfire N losses dominated by emissions of N2 that need to be considered when assessing fire effects on ecosystem N cycling and mass balance. We propose indirect N gas emissions factors for the first postfire year, equalling to 7.7% (N2 -N), 2.7% (NO-N) and 5.0% (N2 O-N) of the direct fire combustion losses of the respective N gas species.


Assuntos
Incêndios , Nitrogênio/análise , Solo/química , Ecossistema , Florestas , Gases , Região do Mediterrâneo , Minerais/análise , Espanha
3.
Pediatr Int ; 59(11): 1194-1199, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28802081

RESUMO

BACKGROUND: The aim of this study was to analyze the relationship between creativity and physical fitness in elementary school children. METHOD: Data were collected from 308 primary school students in southern Spain, ranging in age from 8 to 12 years (mean, 9.72 ± 1.25 years). They completed a fitness test battery, and the Prueba de Imaginación Creativa para Niños (PIC-N; Creative Imagination Test for Children) to analyze creativity. RESULTS: Significant differences were found between the sexes. Boys had better physical fitness but there were no sex differences in creativity. On clusters analysis, the highly creative groups had better physical fitness. Creativity was correlated with physical fitness. Aerobic capacity was a predictor of creativity. CONCLUSION: There is an association between creativity and physical fitness in primary school children that may have important implications for academic achievement.


Assuntos
Criatividade , Aptidão Física , Índice de Massa Corporal , Criança , Estudos Transversais , Avaliação Educacional , Feminino , Humanos , Masculino , Instituições Acadêmicas/estatística & dados numéricos , Espanha , Estudantes/estatística & dados numéricos
4.
Geoderma ; 305: 336-345, 2017 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-29104306

RESUMO

Agricultural soils are a major source of nitric- (NO) and nitrous oxide (N2O), which are produced and consumed by biotic and abiotic soil processes. The dominant sources of NO and N2O are microbial nitrification and denitrification, and emissions of NO and N2O generally increase after fertiliser application. The present study investigated the impact of N-source distribution on emissions of NO and N2O from soil and the significance of denitrification, rather than nitrification, as a source of NO emissions. To eliminate spatial variability and changing environmental factors which impact processes and results, the experiment was conducted under highly controlled conditions. A laboratory incubation system (DENIS) was used, allowing simultaneous measurement of three N-gases (NO, N2O, N2) emitted from a repacked soil core, which was combined with 15N-enrichment isotopic techniques to determine the source of N emissions. It was found that the areal distribution of N and C significantly affected the quantity and timing of gaseous emissions and 15N-analysis showed that N2O emissions resulted almost exclusively from the added amendments. Localised higher concentrations, so-called hot spots, resulted in a delay in N2O and N2 emissions causing a longer residence time of the applied N-source in the soil, therefore minimising NO emissions while at the same time being potentially advantageous for plant-uptake of nutrients. If such effects are also observed for a wider range of soils and conditions, then this will have major implications for fertiliser application protocols to minimise gaseous N emissions while maintaining fertilisation efficiency.

5.
ISME J ; 17(5): 645-648, 2023 05.
Artigo em Inglês | MEDLINE | ID: mdl-36759553

RESUMO

In the first and limiting step of nitrification, ammonia (NH3) is oxidised to nitrite (NO2-) by the action of some prokaryotes, including bacteria of the Nitrosomonas genus. A potential approach to nitrification inhibition would be through the application of phages, but until now this method has been unexplored and no virulent phages that infect nitrifying bacteria have been described. In this study, we report the isolation of the first phage infecting some Nitrosomonas species. This polyvalent virulent phage (named ΦNF-1) infected Nitrosomonas europaea, Nitrosomonas communis, and Nitrosomonas nitrosa. Phage ΦNF-1 has the morphology of the Podoviridae family, a dsDNA genome of 41,596 bp and a 45.1 % GC content, with 50 predicted open reading frames. Phage ΦNF-1 was found to inhibit bacterial growth and reduce NH4+ consumption in the phage-treated cultures. The application of phages as biocontrol agents could be a useful strategy for nitrification inhibition without the restrictions associated with chemical inhibitors.


Assuntos
Bacteriófagos , Nitrosomonas europaea , Bacteriófagos/genética , Nitrosomonas , Bactérias , Nitritos , Amônia
6.
J Sports Sci Med ; 11(2): 312-21, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-24149205

RESUMO

Physical education is a favourable educational framework for the development of programmes aimed at increasing physical activity in children and thus reducing sedentarism. The progressive increase of overweight students demands global control and follow-up measurement of these behaviours in both in and out of school. The pedometer can be a useful tool in this field. It is easy to use and allow Physical Education (PE) departments to quantify their students' number of steps/day. The aim of this study was to determine the effect of a pedometer intervention on body fat and BMI levels in overweight teenagers. Besides, the effects of the programme are analysed according to two other variables: pedometer ownership and gender, distinguishing between out-of-school and school hours, weekdays and weekends. The sample comprises 112 overweight students (49 boys and 63 girls) from 5 secondary schools. Participants were asked to follow a physical activity programme consisting on a minimum of 12000 and 10000 steps/day for boys and girls, respectively. It also allowed them to get up to 2 extra points in their PE marks. Results were measured after 6 weeks of programme application as well as after 6 weeks of retention. Results revealed significantly reduced BMI in the teenagers with their own pedometer (p < 0.05). The difference observed in the number of steps/day between boys (12050) and girls (9566) was significant in all measured time periods (p < 0.05). Besides, both overweight boys and girls were observed to take 1000 steps/day less at weekends than in weekdays. Therefore, it is concluded that the proposal of 12000 and 10000 steps for overweight boys and girls, respectively, accompanied by a reinforcement programme in their final PE marks, seems sufficient to obtain significant BMI reductions. Besides, PE is shown a favourable framework for the proposal of pedometer-impelled weight loss programmes in overweight youth. Key pointsA programme of 12000 and 10000 steps for overweight boys and girls, respectively with reinforcement in physical education marks, the body mass index improves.Body mass index more reduced was in Spanish adolescent overweight that used their own pedometer.The steps/day between boys (12050) and girls (9566) with overweight was different (p < 0.05).Overweight boys and girls were observed to take 1000 steps/day less at weekends than in weekdays.In physical education is possible to apply a programme of steps in obese youth of secondary education schools.

7.
J Environ Qual ; 49(5): 1092-1109, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33016455

RESUMO

Adequately estimating soil nitrous oxide (N2 O) emissions using static chambers is challenging due to the high spatial variability and episodic nature of these fluxes. We discuss how to design experiments using static chambers to better account for this variability and reduce the uncertainty of N2 O emission estimates. This paper is part of a series, each discussing different facets of N2 O chamber methodology. Aspects of experimental design and sampling affected by spatial variability include site selection and chamber layout, size, and areal coverage. Where used, treatment application adds a further level of spatial variability. Time of day, frequency, and duration of sampling (both individual chamber closure and overall experiment duration) affect the temporal variability captured. We also present best practice recommendations for chamber installation and sampling protocols to reduce further uncertainty. To obtain the best N2 O emission estimates, resources should be allocated to minimize the overall uncertainty in line with experiment objectives. Sometimes this will mean prioritizing individual flux measurements and increasing their accuracy and precision by, for example, collecting four or more headspace samples during each chamber closure. However, where N2 O fluxes are exceptionally spatially variable (e.g., in heterogeneous agricultural landscapes, such as uneven and woody grazed pastures), using available resources to deploy more chambers with fewer headspace samples per chamber may be beneficial. Similarly, for particularly episodic N2 O fluxes, generated for example by irrigation or freeze-thaw cycles, increasing chamber sampling frequency will improve the accuracy and reduce the uncertainty of temporally interpolated N2 O fluxes.


Assuntos
Monitoramento Ambiental , Projetos de Pesquisa , Agricultura , Óxido Nitroso/análise , Solo
8.
Int J Sports Physiol Perform ; 15(7): 927-933, 2020 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-32163923

RESUMO

CONTEXT: Plyometric training promotes a highly effective neuromuscular stimulus to improve running performance. Jumping rope (JR) involves mainly foot muscles and joints, due to the quick rebounds, and it might be considered a type of plyometric training for improving power and stiffness, some of the key factors for endurance-running performance. PURPOSE: To determine the effectiveness of JR during the warm-up routine of amateur endurance runners on jumping performance, reactivity, arch stiffness, and 3-km time-trial performance. METHODS: Athletes were randomly assigned to an experimental (n = 51) or control (n = 45) group. Those from the control group were asked to maintain their training routines, while athletes from the experimental group had to modify their warm-up routines, including JR (2-4 sessions/wk, with a total time of 10-20 min/wk) for 10 weeks. Physical tests were performed before (pretest) and after (posttest) the intervention period and included jumping performance (countermovement-jump, squat-jump, and drop-jump tests), foot-arch stiffness, and 3-km time-trial performance. Reactive strength index (RSI) was calculated from a 30-cm drop jump. RESULTS: The 2 × 2 analysis of variance showed significant pre-post differences in all dependent variables (P < .001) for the experimental group. No significant changes were reported in the control group (all P ≥ .05). Pearson correlation analysis revealed a significant relationship between Δ3-km time trial and ΔRSI (r = -.481; P < .001) and ΔStiffness (r = -.336; P < .01). The linear-regression analysis showed that Δ3-km time trial was associated with ΔRSI and ΔStiffness (R2 = .394; P < .001). CONCLUSIONS: Compared with a control warm-up routine prior to endurance-running training, 10 weeks (2-4 times/wk) of JR training, in place of 5 minutes of regular warm-up activities, was effective in improving 3-km time-trial performance, jumping ability, RSI, and arch stiffness in amateur endurance runners. Improvements in RSI and arch stiffness were associated with improvements in 3-km time-trial performance.

9.
Environ Pollut ; 245: 199-207, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30423534

RESUMO

Fertilized cropping systems are important sources of nitrous oxide (N2O) and nitric oxide (NO) to the atmosphere, and biotic and abiotic processes control the production and consumption of these gases in the soil. In fact, the inhibition of nitrification after application of urea or an ammonium-based fertilizer to agricultural soils has resulted in an efficient strategy to mitigate both N2O and NO in aerated agricultural soils. Therefore, the NO and N2O mitigation capacity of a novel nitrification inhibitor (NI), 2-(3,4-dimethyl-1H-pyrazol-1-yl) succinic acid isomeric mixture (DMPSA), has been studied in a winter wheat crop. A high temporal resolution of fluxes of NO and NO2, obtained by using automatic chambers for urea (U) and urea with DMPSA, allowed a better understanding of the temporal net emissions of these gases under field conditions. Seventy-five days after fertilization, the effective reduction of nitrification by DMPSA significantly decreased the production of NO with respect to the treatment without it, giving net consumption of NO in the soil (-61.72 g-N ha-1) for U + DMPSA in comparison to net production (227.44 g-N ha-1) for U. The explanation of NO deposition after NI application, due to biotic and abiotic processes in the soil-plant system, supposes a challenge that needs to be studied in the future. In the case of N2O, the addition of DMPSA significantly mitigated the emissions of this gas by 71%, though the total N2O emissions in both fertilized treatments were significantly greater than those of the control (43.69 g-N ha-1). Regarding the fertilized treatments, no significant effect of DMPSA in comparison to urea alone was observed on grain yield nor bread-making wheat quality. To sum up, we got a significant reduction of N2O and NO with the addition of DMPSA, without a loss in yield and quality parameters in wheat.


Assuntos
Poluentes Atmosféricos/análise , Óxido Nítrico/metabolismo , Nitrificação/efeitos dos fármacos , Óxido Nitroso/metabolismo , Succinatos/farmacologia , Triticum/metabolismo , Agricultura/métodos , Fertilizantes/análise , Gases/análise , Nitrificação/fisiologia , Solo/química , Ureia/metabolismo
10.
PLoS One ; 14(9): e0222872, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31550296

RESUMO

This study aimed to evaluate the concurrent validity of two different inertial measurement units for measuring spatiotemporal parameters during running on a treadmill, by comparing data with a high-speed video analysis (VA) at 1,000 Hz. Forty-nine endurance runners performed a running protocol on a treadmill at comfortable velocity (i.e., 3.25 ± 0.36 m.s-1). Those wearable devices (i.e., Stryd™ and RunScribe™ systems) were compared to a high-speed VA, as a reference system for measuring spatiotemporal parameters (i.e. contact time [CT], flight time [FT], step frequency [SF] and step length [SL]) during running at comfortable velocity. The pairwise comparison revealed that the Stryd™ system underestimated CT (5.2%, p < 0.001) and overestimated FT (15.1%, p < 0.001) compared to the VA; whereas the RunScribe™ system underestimated CT (2.3%, p = 0.009). No significant differences were observed in SF and SL between the wearable devices and VA. The intra class correlation coefficient (ICC) revealed an almost perfect association between both systems and high-speed VA (ICC > 0.81). The Bland-Altman plots revealed heteroscedasticity of error (r2 = 0.166) for the CT from the Stryd™ system, whereas no heteroscedasticity of error (r2 < 0.1) was revealed in the rest of parameters. In conclusion, the results obtained suggest that both foot pods are valid tools for measuring spatiotemporal parameters during running on a treadmill at comfortable velocity. If the limits of agreement of both systems are considered in respect to high-speed VA, the RunScribe™ seems to be a more accurate system for measuring temporal parameters and SL than the Stryd™ system.


Assuntos
Teste de Esforço/instrumentação , Marcha/fisiologia , Corrida/fisiologia , Análise Espaço-Temporal , Dispositivos Eletrônicos Vestíveis , Adulto , Feminino , Humanos , Masculino , Gravação em Vídeo , Adulto Jovem
11.
Sci Total Environ ; 624: 1202-1212, 2018 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-29929233

RESUMO

Nitrification inhibitors (NIs) such as dicyandiamide (DCD) and 3,4-dimethylpyrazole phosphate (DMPP) provide an opportunity to reduce losses of reactive nitrogen (Nr) from agricultural ecosystems. To understand the fate and efficacy of these two inhibitors, laboratory-scale experiments were conducted with 14C-labelled DCD and DMPP to determine the relative rates of mineralization, recovery in soil extracts and sorption in two agricultural soils with contrasting pH and organic matter content. Concurrently, the net production of soil ammonium and nitrate in soil were determined. Two months after NI addition to soil, significantly greater mineralization of 14C-DMPP (15.3%) was observed, relative to that of 14C-DCD (10.7%), and the mineralization of both NIs increased with temperature, regardless of NI and soil type. However, the mineralization of NIs did not appear to have a major influence on their inhibitory effect (as shown by the low mineralization rates and the divergent average half-lives for mineralization and nitrification, which were 454 and 37days, respectively). The nitrification inhibition efficacy of DMPP was more dependent on soil type than that of DCD, although the efficacy of both inhibitors was lower in the more alkaline, low-organic matter soil. Although a greater proportion of DMPP becomes unavailable, possibly due to physico-chemical sorption to soil or microbial immobilization, our results demonstrate the potential of DMPP to achieve higher inhibition rates than DCD in grassland soils. Greater consideration of the interactions between NI type, soil and temperature is required to provide robust and cost-effective advice to farmers on NI use.

12.
Sci Total Environ ; 636: 427-436, 2018 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-29709860

RESUMO

There is an increasing concern about the negative impacts associated to the release of reactive nitrogen (N) from highly fertilized agro-ecosystems. Ammonia (NH3) and nitrous oxide (N2O) are harmful N pollutants that may contribute both directly and indirectly to global warming. Surface applied manure, urea and ammonium (NH4+) based fertilizers are important anthropogenic sources of these emissions. Nitrification inhibitors (NIs) have been proposed as a useful technological approach to reduce N2O emission although they can lead to large NH3 losses due to increasing NH4+ pool in soils. In this context, a field experiment was carried out in a maize field with aiming to simultaneously quantify NH3 volatilization and N2O emission, assessing the effect of two NIs 3,4­dimethilpyrazol phosphate (DMPP) and 3,4­dimethylpyrazole succinic acid (DMPSA). The first treatment was pig slurry (PS) before seeding (50 kg N ha-1) and calcium ammonium nitrate (CAN) at top-dressing (150 kg N ha-1), and the second was DMPP diluted in PS (PS + DMPP) (50 kg N ha-1) and CAN + DMPSA (150 kg N ha-1) also before seeding and at top-dressing, respectively. Ammonia emissions were quantified by a micrometeorological method during 20 days after fertilization and N2O emissions were assessed using manual static chambers during all crop period. The treatment with NIs was effective in reducing c. 30% cumulative N2O losses. However, considering only direct N2O emissions after second fertilization event, a significant reduction was not observed using CAN+DMPSA, probably because high WFPS of soil, driven by irrigation, favored denitrification. Cumulative NH3 losses were not significantly affected by NIs. Indeed, NH3 volatilization accounted 14% and 10% of N applied in PS + DMPP and PS plots, respectively and c. 2% of total N applied in CAN+DMPSA and CAN plots. Since important NH3 losses still exist even although abating strategies are implemented, structural and political initiatives are needed to face this issue.

13.
Artigo em Inglês | MEDLINE | ID: mdl-30287725

RESUMO

The number of donors and organs available has not increased at the same rate as the inclusion of new patients in the waiting lists. The aim of the present study was to analyze the quality of the detection process of potential brain-dead organ donors at the Hospital of León. For this, a cross-sectional prospective study was developed on a retrospective cohort of patients who were admitted or died by catastrophic brain damage with the potential for organs donation. Data were collected for six months using hospital records of admissions and exitus. For the statistical analysis, the free distribution software Epi Info 3.5.4 was employed. A total of 627 patients were studied: 550 were discharged and 77 died as potential donors. Of the potential donors, 65 died in asystole, but 60 of them had an absolute contraindication to donation and 20 died after limitation of life support therapy. Five cases with donor criteria in controlled asystole were detected. The analysis found that the detection process conformed to the regulatory framework stablished by the National Transplant Organization. However, population aging leads to a high rate of absolute contraindications among detected potential donors. The donation capacity of the hospital could therefore be increased with the implementation of a donor protocol in controlled asystole.


Assuntos
Morte Encefálica , Hospitais , Doadores de Tecidos , Obtenção de Tecidos e Órgãos/métodos , Idoso , Idoso de 80 Anos ou mais , Estudos Transversais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos
15.
Sci Total Environ ; 566-567: 512-520, 2016 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-27235901

RESUMO

No tillage (NT) has been associated to increased N2O emission from poorly drained agricultural soils. This is the case for soils with a low permeable Bt horizon, which generates a perched water layer after water addition (via rainfall or irrigation) over a long period of time. Moreover, these soils often have problems of acidity and require liming application to sustain crop productivity; changes in soil pH have large implications for the production and consumption of soil greenhouse gas (GHG) emissions. Here, we assessed in a split-plot design the individual and interactive effects of tillage practices (conventional tillage (CT) vs. NT) and liming (Ca-amendment vs. not-amendment) on N2O and CH4 emissions from poorly drained acidic soils, over a field experiment with a rainfed triticale crop. Soil mineral N concentrations, pH, temperature, moisture, water soluble organic carbon, GHG fluxes and denitrification capacity were measured during the experiment. Tillage increased N2O emissions by 68% compared to NT and generally led to higher CH4 emissions; both effects were due to the higher soil moisture content under CT plots. Under CT, liming reduced N2O emissions by 61% whereas no effect was observed under NT. Under both CT and NT, CH4 oxidation was enhanced after liming application due to decreased Al(3+) toxicity. Based on our results, NT should be promoted as a means to improve soil physical properties and concurrently reduce N2O and CH4 emissions. Raising the soil pH via liming has positive effects on crop yield; here we show that it may also serve to mitigate CH4 emissions and, under CT, abate N2O emissions.

17.
Sci Total Environ ; 508: 85-94, 2015 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-25459752

RESUMO

Conservation agriculture that includes no tillage (NT) or minimum tillage (MT) and crop rotation is an effective practice to increase soil organic matter in Mediterranean semiarid agrosystems. But the impact of these agricultural practices on greenhouse gases (GHGs), such as nitrous oxide (N2O) and methane (CH4), is variable depending mainly on soil structure and short/long-term tillage. The main objective of this study was to assess the long-term effect of three tillage systems (NT, MT and conventional tillage (CT)) and land-covers (fallow/wheat) on the emissions of N2O and CH4 in a low N input agricultural system during one year. This was achieved by measuring crop yields, soil mineral N and dissolved organic C contents, and fluxes of N2O and CH4. Total cumulative N2O emissions were not significantly different (P>0.05) among the tillage systems or between fallow and wheat. The only difference was produced in spring, when N2O emissions were significantly higher (P<0.05) in fallow than in wheat subplots, and NT reduced N2O emissions (P<0.05) compared with MT and CT. Taking into account the water filled pore space (WFPS), both nitrification and denitrification could have occurred during the experimental period. Denitrification capacity in March was similar in all tillage systems, in spite of the higher DOC content maintained in the topsoil of NT. This could be due to the similar denitrifier densities, targeted by nirK copy numbers at that time. Cumulative CH4 fluxes resulted in small net uptake for all treatments, and no significant differences were found among tillage systems or between fallow and wheat land-covers. These results suggest that under a coarse-textured soil in low N agricultural systems, the impact of tillage on GHG is very low and that the fallow cycle within a crop rotation is not a useful strategy to reduce GHG emissions.


Assuntos
Agricultura/métodos , Poluentes Atmosféricos/análise , Conservação dos Recursos Naturais/métodos , Metano/análise , Dióxido de Nitrogênio/análise , Produtos Agrícolas/crescimento & desenvolvimento , Monitoramento Ambiental , Fertilizantes/análise , Rotação , Triticum/crescimento & desenvolvimento
18.
Sci Total Environ ; 490: 880-8, 2014 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-24908647

RESUMO

Drip irrigation combined with split application of fertilizer nitrogen (N) dissolved in the irrigation water (i.e. drip fertigation) is commonly considered best management practice for water and nutrient efficiency. As a consequence, its use is becoming widespread. Some of the main factors (water-filled pore space, NH4(+) and NO3(-)) regulating the emissions of greenhouse gases (i.e. N2O, CO2 and CH4) and NO from agroecosystems can easily be manipulated by drip fertigation without yield penalties. In this study, we tested management options to reduce these emissions in a field experiment with a melon (Cucumis melo L.) crop. Treatments included drip irrigation frequency (weekly/daily) and type of N fertilizer (urea/calcium nitrate) applied by fertigation. Crop yield, environmental parameters, soil mineral N concentrations and fluxes of N2O, NO, CH4 and CO2 were measured during 85 days. Fertigation with urea instead of calcium nitrate increased N2O and NO emissions by a factor of 2.4 and 2.9, respectively (P<0.005). Daily irrigation reduced NO emissions by 42% (P<0.005) but increased CO2 emissions by 21% (P<0.05) compared with weekly irrigation. We found no relation between irrigation frequency and N2O emissions. Based on yield-scaled Global Warming Potential as well as NO cumulative emissions, we conclude that weekly fertigation with a NO3(-)-based fertilizer is the best option to combine agronomic productivity with environmental sustainability. Our study shows that adequate management of drip fertigation, while contributing to the attainment of water and food security, may provide an opportunity for climate change mitigation.


Assuntos
Irrigação Agrícola/métodos , Poluentes Atmosféricos/análise , Poluição do Ar/prevenção & controle , Óxido Nitroso/análise , Poluição do Ar/estatística & dados numéricos , Dióxido de Carbono/análise , Mudança Climática , Fertilizantes/análise , Fertilizantes/estatística & dados numéricos , Efeito Estufa
19.
Acta Otorrinolaringol Esp ; 64(1): 72-4, 2013.
Artigo em Espanhol | MEDLINE | ID: mdl-22000484

RESUMO

The Ramsay-Hunt syndrome is the association of facial palsy and varicella-zoster virus infection with involvement of the ear canal and eardrum. It may be associated with deafness, tinnitus and dizziness. It can sometimes affect the lower cranial nerves. A case of an immunocompetent patient with affectation of the VII, VIII and X cranial nerves is presented.


Assuntos
Herpes Zoster da Orelha Externa/complicações , Herpes Zoster da Orelha Externa/diagnóstico , Paralisia das Pregas Vocais/etiologia , Idoso , Humanos , Masculino
20.
Chemosphere ; 89(3): 310-8, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-22583784

RESUMO

Urea is considered the cheapest and most commonly used form of inorganic N fertilizer worldwide. However, its use is associated with emissions of ammonia (NH(3)), nitrous oxide (N(2)O) and nitric oxide (NO), which have both economic and environmental impact. Urease activity inhibitors have been proposed as a means to reduce NH(3) emissions, although limited information exists about their effect on N(2)O and NO emissions. In this context, a field experiment was carried out with a barley crop (Hordeum vulgare L.) under Mediterranean conditions to test the effectiveness of the urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) on reducing these gaseous N losses from surface applied urea. Crop yield, soil mineral N concentrations, dissolved organic carbon (DOC), denitrification potential, NH(3), N(2)O and NO fluxes were measured during the growing season. The inclusion of the inhibitor reduced NH(3) emissions in the 30 d following urea application by 58% and net N(2)O and NO emissions in the 95 d following urea application by 86% and 88%, respectively. NBPT addition also increased grain yield by 5% and N uptake by 6%, although neither increase was statistically significant. Under the experimental conditions presented here, these results demonstrate the potential of the urease inhibitor NBPT in abating NH(3), N(2)O and NO emissions from arable soils fertilized with urea, slowing urea hydrolysis and releasing lower concentrations of NH(4)(+) to the upper soil layer.


Assuntos
Poluição do Ar/prevenção & controle , Amônia , Inibidores Enzimáticos/farmacologia , Óxido Nítrico , Óxido Nitroso , Compostos Organofosforados/farmacologia , Urease/antagonistas & inibidores , Fertilizantes/efeitos adversos , Hordeum , Ureia/efeitos adversos
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