Short-term effects of four tillage practices on soil physical properties, soil water potential, and maize yield

The area cultivated using conservation tillage has recently increased in central Spain. However, soil compaction and water retention with conservation tillage still remains a genuine concern for landowners in this region be- cause of its potential effect on the crop growth and yield. The aim of this research is to determine the short- term influences of four tillage treatments on soil physical properties. In the experiment, bulk density, cone index, soil water potential, soil temperature and maize (Zea mays L.) productivity have been measured. A field experiment was established in spring of 2013 on a loamy soil. The experiment compared four tillage methods (zero tillage, ZT; reservoir tillage, RT; minimum tillage, MT; and conventional tillage, CT). Soil bulk density and soil cone index were measured during maize growing season and at harvesting time. Furthermore, the soil water potential was monitored by using a wireless sensors network with sensors at 20 and 40 cm depths. Also, soil temperatures were registered at depths of 5 and 12 cm. Results indicated that there were significant differ- ences between soil bulk density and cone index of ZT method and those of RT, MT, and CT, during the growing season; although, this difference was not significant at the time of harvesting in some soil layers. Overall, in most soil layers, tillage practice affected bulk density and cone index in the order: ZT N RT N MT N CT. Regardless oftheentireobservationperiod,results exhibited that soils under ZT and RT treatments usually resulted in higher water potential and lower soil temperature than the other two treatments at both soil depths. In addition, clear differences in maize grain yield were observed between ZT and CT treatments, with a grain yield (up to 15.4%) increase with the CT treatment. On the other hand, no significant differences among (RT, MT, and CT) on maizeyieldwerefound.Inconclusion,the impact of soil compaction increase and soil temperature decrease,pro- duced by ZT treatment is a potential reason for maize yield reduction in this tillage method. We found that RT could be certainly a viable option for farmers incentral Spain,particularly when switching to conservation tillage from conventional tillage. This technique showed a moderate and positive effect on soil physical properties and increased maize yields compared to ZT and MT, and provides an opportunity to stabilize maize yields compared to CT.

Probabilistic assessment of risk from the exposure to mercury in artisanal gold mining communities in Colombia

Colombia is one the largest per capita mercury polluters as a consequence of its artisanal gold mining operations, which are steadily increasing following the rising price of this metal. Compared to gravimetric separation methods and cyanidation, the concentration of gold using Hg amalgams presents several advantages: the process is less time-consuming and minimizes gold losses, and Hg is easily transported and inexpensive relative to the selling price of gold. Very often, mercury amalgamation is carried out on site by unprotected workers. During this operation large amounts of mercury are discharged to the environment and eventually reach the fresh water bodies in the vicinity where it is subjected to methylation. Additionally, as gold is released from the amalgam by heating on open charcoal furnaces in small workshops, mercury vapors are emitted and inhaled by the artisanal smelters and the general population

Short-term response of the Ca cycle of a montane forest in Ecuador to low experimental CaCl2 additions

The tropical montane forests of the E Andean cordillera in Ecuador receive episodic Sahara- dust inputs particularly increasing Ca deposition. We added CaCl2 to isolate the effect of Ca deposition by Sahara dust to tropical montane forest from the simultaneously occurring pH effect. We examined components of the Ca cycle at four control plots and four plots with added Ca (2 × 5 kg ha?1 Ca annually as CaCl2) in a random arrangement. Between August 2007 and December 2009 (four applications of Ca), we determined Ca concentrations and fluxes in litter leachate, mineral soil solution (0.15 and 0.30 m depths), throughfall, and fine litterfall and Al con- centrations and speciation in soil solutions. After 1 y of Ca addition, we assessed fine-root bio- mass, leaf area, and tree growth. Only < 3% of the applied Ca leached below the acid organic layer (pH 3.5?4.8). The added CaCl2 did not change electrical conductivity in the root zone after 2 y. In the second year of fertilization, Ca retention in the canopy of the Ca treatment tended to decrease relative to the control. After 2 y, 21% of the applied Ca was recycled to soil with throughfall and litterfall. One year after the first Ca addition, fine-root biomass had decreased significantly. Decreasing fine-root biomass might be attributed to a direct or an indirect beneficial effect of Ca on the soil decomposer community. Because of almost complete association of Al with dissolved organic matter and high free Ca2+ : Al3+ activity ratios in solution of all plots, Al toxicity was unlikely. We conclude that the added Ca was retained in the system and had benefi- cial effects on some plants.

Joint assessment of water and agricultural policies: a Pan-European multidimensional modelling approach.

Sustainability and the food-water-environment nexus. Food-water linkages in global agro-economic models. The CAPRI water module. Potential to jointly assess food and water policies. Pilot case study. Further development.

Thermographic imaging: assessment of drought and heat tolerance in Spanish germplasm of Brachypodium distachyon.

The annual grass Brachypodium distachyon has been recently recognized as the model plant for functional genomics of temperate grasses, including cereals of economic relevance like wheat and barley. Sixty-two lines of B. distachyon were assessed for response to drought stress and heat tolerance. All these lines, except the reference genotype BD21, derive from specimens collected in 32 distinct locations of the Iberian Peninsula, covering a wide range of geo- climatic conditions. Sixteen lines of Brachypodium hybridum, an allotetraploid closely related to B. distachyon were used as reference of abiotic-stress well-adapted genotypes. Drought tolerance was assessed in a green-house trial. At the rosette-stage, no irrigation was applied to treated plants whereas their replicates at the control were maintained well watered during all the experiment. Thermographic images of treated and control plants were taken after 2 and 3 weeks of drought treatment, when stressed plants showed medium and extreme wilting symptoms. The mean leaf temperature of stressed (LTs) and control (LTc) plants was estimated based upon thermographic records from selected pixels (183 per image) that strictly correspond to leaf tissue. The response to drought was based on the analysis of two parameters: LTs and the thermal difference (TD) between stressed and control plants (LTs – LTc). The response to heat stress was based on LTc. Comparison of the mean values of these parameters showed that: 1) Genotypes better adapted to drought (B. hybridum lines) presented a higher LTs and TD than B. distachyon lines. 2) Under high temperature conditions, watered plants of B. hybridum lines maintained lower LTc than those of B. distachyon. Those results suggest that in these species adaptation to drought is linked to a more efficient stomata regulation: under water stress stomata are closed, increasing foliar temperature but also water use efficiency by reducing transpiration. With high temperature and water availability the results are less definite, but still seems that opening stomata allow plants to increase transpiration and therefore to diminish foliar temperature.

In-field assessment of batteries and PV modules in a large photovoltaic rural electrification programme

Assuring the sustainability of quality in photovoltaic rural electrification programmes involves enhancing the reliability of the components of solar home systems as well as the characterization of the overall programme cost structure. Batteries and photovoltaic modules have a great impact on both the reliability and the cost assessment, the battery being the weakest component of the solar home system and consequently the most expensive element of the programme. The photovoltaic module, despite being the most reliable component, has a significant impact cost-wise on the initial investment, even at current market prices. This paper focuses on the in-field testing of both batteries and photovoltaic modules working under real operating conditions within a sample of 41 solar home systems belonging to a large photovoltaic rural electrification programme with more than 13,000 installed photovoltaic systems. Different reliability parameters such as lifetime have been evaluated, taking into account different factors, for example energy consumption rates, or the manufacturing quality of batteries. A degradation model has been proposed relating both loss of capacity and time of operation. The user e solar home system binomial is also analysed in order to understand the meaning of battery lifetime in rural electrification.

Operational short term health impact assessment of air pollution modelling system over Europe

The last decade, scientific studies have indicated an association between air pollution to which people are exposed and wide range of adverse health outcomes. We have developed a tool which is based on a model (MM5-CMAQ) running over Europe with 50 km spatial resolution, based on EMEP annual emissions, to produce a short-term forecast of the impact on health. In order to estimate the mortality change (forecasted for the next 24 hours) we have chosen a log-linear (Poisson) regression form to estimate the concentration-response function. The parameters involved in the C-R function have been estimated based on epidemiological studies, which have been published. Finally, we have derived the relationship between concentration change and mortality change from the C-R function which is the final health impact function.

Atmospheric modelling of tritium forms transport: review of capabilities and R&D needs for the assessment of fusion facilities environmental impact

One of the key scrutiny issues of new coming energy era would be the environmental impact of fusion facilities managing one kg of tritium. The potential change of committed dose regulatory limits together with the implementation of nuclear design principles (As Low as Reasonably achievable - ALARA -, Defense in Depth -D-i-D-) for fusion facilities could strongly impact on the cost of deployment of coming fusion technology. Accurate modeling of environmental tritium transport forms (HT, HTO) for the assessment of fusion facility dosimetric impact in Accidental case appears as of major interest. This paper considers different short-term releases of tritium forms (HT and HTO) to the atmosphere from a potential fusion reactor located in the Mediterranean Basin. This work models in detail the dispersion of tritium forms and dosimetric impact of selected environmental patterns both inland and in-sea using real topography and forecast meteorological data-fields (ECMWF/FLEXPART). We explore specific values of this ratio in different levels and we examine the influence of meteorological conditions in the HTO behavior for 24 hours. For this purpose we have used a tool which consists on a coupled Lagrangian ECMWF/FLEXPART model useful to follow real time releases of tritium at 10, 30 and 60 meters together with hourly observations of wind (and in some cases precipitations) to provide a short-range approximation of tritium cloud behavior. We have assessed inhalation doses. And also HTO/HT ratios in a representative set of cases during winter 2010 and spring 2011 for the 3 air levels.

Assessment of oral bioaccessibility of arsenic in playground soil in Madrid (Spain): A three-method comparison and implications for risk assessment

Three methodologies to assess As bioaccessibility were evaluated using playgroundsoil collected from 16 playgrounds in Madrid, Spain: two (Simplified Bioaccessibility Extraction Test: SBET, and hydrochloric acid-extraction: HCl) assess gastric-only bioaccessibility and the third (Physiologically Based Extraction Test: PBET) evaluates mouth–gastric–intestinal bioaccessibility. Aqua regia-extractable (pseudo total) As contents, which are routinely employed in riskassessments, were used as the reference to establish the following percentages of bioaccessibility: SBET – 63.1; HCl – 51.8; PBET – 41.6, the highest values associated with the gastric-only extractions. For Madridplaygroundsoils – characterised by a very uniform, weakly alkaline pH, and low Fe oxide and organic matter contents – the statistical analysis of the results indicates that, in contrast with other studies, the highest percentage of As in the samples was bound to carbonates and/or present as calcium arsenate. As opposed to the As bound to Fe oxides, this As is readily released in the gastric environment as the carbonate matrix is decomposed and calcium arsenate is dissolved, but some of it is subsequently sequestered in unavailable forms as the pH is raised to 5.5 to mimic intestinal conditions. The HCl extraction can be used as a simple and reliable (i.e. low residual standard error) proxy for the more expensive, time consuming, and error-prone PBET methodology. The HCl method would essentially halve the estimate of carcinogenic risk for children playing in Madridplaygroundsoils, providing a more representative value of associated risk than the pseudo-total concentrations used at present

Geochemistry and risk assessment of street dust in Luanda, Angola, a tropical urban environment

A total of 92 samples of street dust were collected in Luanda, Angola, were sieved below 100 μm, and analysed by ICP-MS for 35 elements after an aqua-regia digestion. The concentration and spatial heterogeneity of trace elements in the street dust of Luanda are generally lower than in most industrialized cities in the Northern hemisphere. These observations reveal a predominantly “natural” origin for the street dust in Luanda, which is also manifested in that some geochemical processes that occur in natural soils are preserved in street dust: the separation of uranium from thorium, and the retention of the former by carbonate materials, or the high correlation between arsenic and vanadium due to their common mode of adsorption on solid particles in the form of oxyanions. The only distinct anthropogenic fingerprint in the composition of Luanda's street dust is the association Pb–Cd–Sb–Cu (and to a lesser extent, Ba–Cr–Zn). The use of risk assessment strategies has proved helpful in identifying the routes of exposure to street dust and the trace elements therein of most concern in terms of potential adverse health effects. In Luanda the highest levels of risk seem to be associated (a) with the presence of As and Pb in the street dust and (b) with the route of ingestion of dust particles, for all the elements included in the study except Hg, for which inhalation of vapours presents a slightly higher risk than ingestion. However, given the large uncertainties associated with the estimates of toxicity values and exposure factors, and the absence of site-specific biometric factors, these results should be regarded as preliminary and further research should be undertaken before any definite conclusions regarding potential health effects are drawn.

Influence of local wind speed and direction on wind power dynamics - Application to offshore very short-term forecasting

Wind power time series usually show complex dynamics mainly due to non-linearities related to the wind physics and the power transformation process in wind farms. This article provides an approach to the incorporation of observed local variables (wind speed and direction) to model some of these effects by means of statistical models. To this end, a benchmarking between two different families of varying-coefficient models (regime-switching and conditional parametric models) is carried out. The case of the offshore wind farm of Horns Rev in Denmark has been considered. The analysis is focused on one-step ahead forecasting and a time series resolution of 10 min. It has been found that the local wind direction contributes to model some features of the prevailing winds, such as the impact of the wind direction on the wind variability, whereas the non-linearities related to the power transformation process can be introduced by considering the local wind speed. In both cases, conditional parametric models showed a better performance than the one achieved by the regime-switching strategy. The results attained reinforce the idea that each explanatory variable allows the modelling of different underlying effects in the dynamics of wind power time series.

Effect of short-term fasting prior to slaughter on welfare and meat quality or rainbow trout (Oncorhynchus mykiss)

El manejo pre-sacrificio es de vital importancia en acuicultura, ya que afecta tanto a las reacciones fisiológicas como a los procesos bioquímicos post mortem, y por tanto al bienestar y a la calidad del producto. El ayuno pre-sacrificio se lleva a cabo de forma habitual en acuicultura, ya que permite el vaciado del aparato digestivo de restos de alimento y heces, reduciendo de esta manera la carga bacteriana en el intestino y la dispersión de enzimas digestivos y potenciales patógenos a la carne. Sin embargo, la duración óptima de este ayuno sin que el pez sufra un estrés innecesario no está clara. Además, se sabe muy poco sobre la mejor hora del día para realizar el sacrificio, lo que a su vez está regido por los ritmos diarios de los parámetros fisiológicos de estrés. Finalmente, se sabe que la temperatura del agua juega un papel muy importante en la fisiología del estrés pero no se ha determinado su efecto en combinación con el ayuno. Además, las actuales recomendaciones en relación a la duración óptima del ayuno previo al sacrificio en peces no suelen considerar la temperatura del agua y se basan únicamente en días y no en grados día (ºC d). Se determinó el efecto del ayuno previo al sacrificio (1, 2 y 3 días, equivalente a 11,1-68,0 grados día) y la hora de sacrificio (08h00, 14h00 y 20h00) en trucha arco iris (Oncorhynchus mykiss) de tamaño comercial en cuatro pruebas usando diferentes temperaturas de agua (Prueba 1: 11,8 ºC; Prueba 2: 19,2 ºC; Prueba 3: 11,1 ºC; y Prueba 4: 22,7 ºC). Se midieron indicadores biométricos, hematológicos, metabólicos y de calidad de la carne. En cada prueba, los valores de los animales ayunados (n=90) se compararon con 90 animales control mantenidos bajo condiciones similares pero nos ayunados. Los resultados sugieren que el ayuno tuvo un efecto significativo sobre los indicadores biométricos. El coeficiente de condición en los animales ayunados fue menor que en los controles después de 2 días de ayuno. El vaciado del aparato digestivo se produjo durante las primeras 24 h de ayuno, encontrándose pequeñas cantidades de alimento después de 48 h. Por otra parte, este vaciado fue más rápido cuando las temperaturas fueron más altas. El peso del hígado de los animales ayunados fue menor y las diferencias entre truchas ayunadas y controles fueron más evidentes a medida que el vaciado del aparato digestivo fue más rápido. El efecto del ayuno hasta 3 días en los indicadores hematológicos no fue significativo. Los niveles de cortisol en plasma resultaron ser altos tanto en truchas ayunadas como en las alimentadas en todas las pruebas realizadas. La concentración media de glucosa varió entre pruebas pero mostró una tendencia a disminuir en animales ayunados a medida que el ayuno progresaba. En cualquier caso, parece que la temperatura del agua jugó un papel muy importante, ya que se encontraron concentraciones más altas durante los días 2 y 3 de ayuno en animales mantenidos a temperaturas más bajas previamente al sacrificio. Los altos niveles de lactato obtenidos en sangre parecen sugerir episodios de intensa actividad muscular pero no se pudo encontrar relación con el ayuno. De la misma manera, el nivel de hematocrito no mostró efecto alguno del ayuno y los leucocitos tendieron a ser más altos cuando los animales estaban menos estresados y cuando su condición corporal fue mayor. Finalmente, la disminución del peso del hígado (índice hepatosomático) en la Prueba 3 no se vio acompañada de una reducción del glucógeno hepático, lo que sugiere que las truchas emplearon una estrategia diferente para mantener constantes los niveles de glucosa durante el periodo de ayuno en esa prueba. En relación a la hora de sacrificio, se obtuvieron niveles más bajos de cortisol a las 20h00, lo que indica que las truchas estaban menos estresadas y que el manejo pre-sacrificio podría resultar menos estresante por la noche. Los niveles de hematocrito fueron también más bajos a las 20h00 pero solo con temperaturas más bajas, sugiriendo que las altas temperaturas incrementan el metabolismo. Ni el ayuno ni la hora de sacrificio tuvieron un efecto significativo sobre la evolución de la calidad de la carne durante los 3 días de almacenamiento. Por el contrario, el tiempo de almacenamiento sí que parece tener un efecto claro sobre los parámetros de calidad del producto final. Los niveles más bajos de pH se alcanzaron a las 24-48 h post mortem, con una lata variabilidad entre duraciones del ayuno (1, 2 y 3 días) en animales sacrificados a las 20h00, aunque no se pudo distinguir ningún patrón común. Por otra parte, la mayor rigidez asociada al rigor mortis se produjo a las 24 h del sacrificio. La capacidad de retención de agua se mostró muy estable durante el período de almacenamiento y parece ser independiente de los cambios en el pH. El parámetro L* de color se incrementó a medida que avanzaba el período de almacenamiento de la carne, mientras que los valores a* y b* no variaron en gran medida. En conclusión, basándose en los resultados hematológicos, el sacrificio a última hora del día parece tener un efecto menos negativo en el bienestar. De manera general, nuestros resultados sugieren que la trucha arco iris puede soportar un período de ayuno previo al sacrificio de hasta 3 días o 68 ºC d sin que su bienestar se vea seriamente comprometido. Es probable que con temperaturas más bajas las truchas pudieran ser ayunadas durante más tiempo sin ningún efecto negativo sobre su bienestar. En cualquier caso, se necesitan más estudios para determinar la relación entre la temperatura del agua y la duración óptima del ayuno en términos de pérdida de peso vivo y la disminución de los niveles de glucosa en sangre y otros indicadores metabólicos. SUMMARY Pre-slaughter handling in fish is important because it affects both physiological reactions and post mortem biochemical processes, and thus welfare and product quality. Pre-slaughter fasting is regularly carried out in aquaculture, as it empties the viscera of food and faeces, thus reducing the intestinal bacteria load and the spread of gut enzymes and potential pathogens to the flesh. However, it is unclear how long rainbow trout can be fasted before suffering unnecessary stress. In addition, very little is known about the best time of the day to slaughter fish, which may in turn be dictated by diurnal rhythms in physiological stress parameters. Water temperature is also known to play a very important role in stress physiology in fish but the combined effect with fasting is unclear. Current recommendations regarding the optimal duration of pre-slaughter fasting do not normally consider water temperature and are only based on days, not degree days (ºC d). The effects of short-term fasting prior to slaughter (1, 2 and 3 days, between 11.1 and 68.0 ºC days) and hour of slaughter (08h00, 14h00 and 20h00) were determined in commercial-sized rainbow trout (Oncorhynchus mykiss) over four trials at different water temperatures (TRIAL 1, 11.8 ºC; TRIAL 2, 19.2 ºC; TRIAL 3, 11.1 ºC; and TRIAL 4, 22.7 ºC). We measured biometric, haematological, metabolic and product quality indicators. In each trial, the values of fasted fish (n=90) were compared with 90 control fish kept under similar conditions but not fasted. Results show that fasting affected biometric indicators. The coefficient of condition in fasted trout was lower than controls 2 days after food deprivation. Gut emptying occurred within the first 24 h after the cessation of feeding, with small traces of digesta after 48 h. Gut emptying was faster at higher water temperatures. Liver weight decreased in food deprived fish and differences between fasted and fed trout were more evident when gut clearance was faster. The overall effect of fasting for up to three days on haematological indicators was small. Plasma cortisol levels were high in both fasted and fed fish in all trials. Plasma glucose response to fasting varied among trials, but it tended to be lower in fasted fish as the days of fasting increased. In any case, it seems that water temperature played a more important role, with higher concentrations at lower temperatures on days 2 and 3 after the cessation of feeding. Plasma lactate levels indicate moments of high muscular activity and were also high, but no variation related to fasting could be found. Haematocrit did not show any significant effect of fasting, but leucocytes tended to be higher when trout were less stressed and when their body condition was higher. Finally, the loss of liver weight was not accompanied by a decrease in liver glycogen (only measured in TRIAL 3), suggesting that a different strategy to maintain plasma glucose levels was used. Regarding the hour of slaughter, lower cortisol levels were found at 20h00, suggesting that trout were less stressed later in the day and that pre-slaughter handling may be less stressful at night. Haematocrit levels were also lower at 20h00 but only at lower temperatures, indicating that higher temperatures increase metabolism. Neither fasting nor the hour of slaughter had a significant effect on the evolution of meat quality during 3 days of storage. In contrast, storage time seemed to have a more important effect on meat quality parameters. The lowest pH was reached 24-48 h post mortem, with a higher variability among fasting durations at 20h00, although no clear pattern could be discerned. Maximum stiffening from rigor mortis occurred after 24 h. The water holding capacity was very stable throughout storage and seemed to be independent of pH changes. Meat lightness (L*) slightly increased during storage and a* and b*-values were relatively stable. In conclusion, based on the haematological results, slaughtering at night may have less of a negative effect on welfare than at other times of the day. Overall, our results suggest that rainbow trout can cope well with fasting up to three days or 68 ºC d prior to slaughter and that their welfare is therefore not seriously compromised. At low water temperatures, trout could probably be fasted for longer periods without negative effects on welfare but more research is needed to determine the relationship between water temperature and days of fasting in terms of loss of live weight and the decrease in plasma glucose and other metabolic indicators.

Assessment of irrigators’ preferences for different water supply risk management tools: option contract and insurance.

Irrigators face the risk of not having enough water to meet their crops’ demand. There are different mechanisms to cope with this risk, including water markets (option contracts) or insurance. A farmer will purchase them when the expected utility change derived from the tool is positive. This paper presents a theoretical assessment of the farmer’s expected utility under two different option contracts, a drought insurance and a combination of an option contract and the insurance. We analyze the conditions that determine farmer’s reference for one instrument or the other and perform a numerical application that is relevant for a Spanish region.

Bioaccessibility of metals and human health risk assessment in community urban gardens

Pseudo-total (i.e. aqua regia extractable) and gastric-bioaccessible (i.e. glycine + HCl extractable) concentrations of Ca, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn were determined in a total of 48 samples collected from six community urban gardens of different characteristics in the city of Madrid (Spain). Calcium carbonate appears to be the soil property that determines the bioaccessibility of a majority of those elements, and the lack of influence of organic matter, pH and texture can be explained by their low levels in the samples (organic matter) or their narrow range of variation (pH and texture). A conservative risk assessment with bioaccessible concentrations in two scenarios, i.e. adult urban farmers and children playing in urban gardens, revealed acceptable levels of risk, but with large differences between urban gardens depending on their history of land use and their proximity to busy areas in the city center. Only in a worst-case scenario in which children who use urban gardens as recreational areas also eat the produce grown in them would the risk exceed the limits of acceptability