Activated carbons with high nitrogen content by a combination of hydrothermal carbonization with activation

This paper reports the production of carbons materials with a nitrogen content around 8%(w/w) and a well-developed porous structure, with BET surface area and pore volume up to 2130 m2 g−1 and 1.12 cm3 g−1, respectively, produced by a combination of hydrothermal carbonization, an environmental friendly method in the production of sustainable tunable carbon materials, with traditional activation methods. The porosity was developed through an activation process according to different routes, namely activation with CO2 and chemical activation using CaCO3 and K2CO3. The successful production of activated carbons using chitosan as a nitrogen source revealed to be a good alternative to post-synthesis methods.

Biotic and abiotic parameters that distinguish types of temporary ponds in a Portuguese Mediterranean ecosystem

Temporary ponds are seasonal wetland habitats subjected to extreme and unstable ecological conditions. Some are classified as priority habitats for conservation by the European Union Habitats Directive. Our study area was the coastal plain of southwest Portugal, which spans across 100km north to south and hosts a large number of temporary ponds as a consequence of climatic and edaphic characteristics. Field sampling of floristic and edaphic data was carried out in 24 temporary ponds every spring between 2005 and 2008. We recorded a total of 174 plant species identified within visually homogeneous plots. We included the data in a geographic information system and classified ponds according to their floristic composition, using a biotic regionalization analysis based on species presence/absence, which is a practical and unambiguous criterion. We found three significantly different groups of ponds which corresponded to an eco-physiognomic pond typology: Mediterranean temporary ponds, marshlands, and disturbed ponds. For the first two pond types we defined characteristic or indicator plant species. We searched also for relationships between pond type and a series of large-scale climatic, geographic, and geological variables, as well as local-scale physical and chemical properties of the soil. Pond type was distinguished by a complex combination of some of these variables, including environmental energy, soil texture, nitrogen content of the soil and pH. A practical way of discriminating between different

MEDIDAS PARA MINIMIZAR A EMISSÃO DE AMÔNIA NA PRODUÇÃO DE FRANGOS DE CORTE: REVISÃO

The main sources of ammonia generation are in agricultural activities, with great representation of poultry, by using feed lot systems with adoption of deep bedding on floor to retain the manure. Ammonia produced in broiler systems production generates damages to animals, humans and environment. The main source of ammonia in the manure deposited on the bed is the excreted nitrogen. With the adoption of appropriate techniques of environmental management, through of adequate ventilation and bed management, control of pH, temperature and humidity are possible significant reductions in ammonia emission, as well as with the use of additives and control the appropriate nitrogen content that is provided in the rations.

Using Different Co-Adjuvant Activating Agents to Improve Activated Carbon Adsorption Capacities

Activated carbon (AC) has proved to be an effective adsorbent for the removal of an assortment of organic and inorganic pollutants from aqueous or gaseous media. However, the pursuit for more effective and cheaper AC is still very active and a diversity of textural and chemical treatments are described as a way to expand their applications. It is well known that the surface area and surface chemistry of AC strongly affect their adsorption capacity [1-3]. In particular, an increase in the nitrogen content has been related to an increase of the basic character and also to the development of the porous structure. In most published work this was achieved through an AC post treatment, including either a reaction with nitrogen containing reagents, such as ammonia, nitric acid, or a diversity of amines. However, the AC prepared directly from a nitrogen rich precursor through a physical or chemical activation is referred to as presenting the best characteristics, namely high nitrogen content, high basic character, low nitrogen leaching and also a good thermal stability [4]. To improve the AC adsorption capacities for acidic pesticide removal from the aqueous phase, we intend to improve the porous structure and introduce nitrogenated groups directly into the AC matrix, using different co-adjuvant activating agents as a nitrogen source, by chemical activation, with potassium hydroxide, of cork or poly(ethyleneterephthalate) (PET) precursors.

Effects of substrate type on plant growth and nitrogen and nitrate concentration in spinach

Abstract The effects of three commercial substrates (a mixture of forest residues, composted grape husks, and white peat, black peat and coir) on plant growth and nitrogen (N) and nitrate (NO3) concentration and content were evaluated in spinach (Spinacia oleracea L. cv. Tapir). Spinach seedlings were transplanted at 45 days after emergence into Styrofoam boxes filled with the substrates and were grown during winter and early spring in an unheated greenhouse with no supplemental lighting. Each planting box was irrigated daily by drip and fertilized with a complete nutrient solution. The NO3 content of the drainage water was lower in coir than in the other substrates. However, shoot NO3 concentration was not affected by substrate type, while yield and total shoot N and NO3 content were greater when plants were grown in peat than in the mixed substrate or the coir. Leaf chlorophyll meter readings provided a good indication of the amount of N in the plants and increased linearly with total shoot N. Keywords Spinacia oleracea; chlorophyll meter; coir; peat; soilless culture systems

Nitrogen requirements at bulb initiation for production of intermediate-day onions

Nitrogen requirements at bulb initiation for production of intermediate-day onions Article in Acta horticulturae · October 2016 DOI: 10.17660/ActaHortic.2016.1142.11 1st Rui Machado 16.44 · Universidade de Évora 2nd David R. Bryla 30.16 · United States Department of Agriculture Abstract Nitrogen requirements at bulb initiation for production of intermediate-day onions Authors: R.M.A. Machado, D.R. Bryla Keywords: Allium cepa, crop growth, nitrogen uptake, soil nitrate Abstract: The effect of nitrogen application on growth, nitrogen (N) uptake, yield, and quality of intermediate-day onion (Allium cepa 'Guimar') was evaluated in the field in southern Portugal. Plants were fertilized with 30 kg ha-1 N at transplanting, 10 kg ha-1 N at 29 days after transplanting (DAT) during early leaf growth, and with 0, 20, 40 and 60 kg ha-1 N at 51 DAT at the initiation of bulbing. The root system of plants in each treatment were concentrated in the top 0.1 m of soil and limited to 0.3 m depth but neither root length density nor rooting depth were affected by N application during later stages of bulb development. Leaf and bulb dry matter, on the other hand, increased linearly with N rate during bulb growth (85 DAT) and at harvest (114 DAT), respectively. Soil nitrate-N (NO3-N) at 0-0.3 m depth likewise increased linearly with N rate during bulb growth but declined from 15-30 mg kg-1 at bulbing to >10 mg kg-1 in each treatment by harvest. A substantial amount of N in the plants, which ranged from 302-525 mg, was taken up from the soil. Application of 60 kg ha-1 N resulted in luxury consumption. Yield (fresh bulb weight) increased from 0.19 kg plant-1 with no N at bulbing to as much as 0.28 kg plant-1 with 60 kg ha-1 N. Bulbs harvested from plants fertilized 40-60 kg ha-1 N averaged 8.2-8.5 cm in diameter, while those from plants with no N at bulbing averaged only 7.2 cm in diameter. Application of N fertilizer is thus recommended at bulbing to increase N uptake, yield, and bulb size of intermediate-day onions, particularly in dry Mediterranean climates where many onions are produced. Other components of quality, including neck diameter, bulb water content, total soluble solids, and juice pH, were not affect by N applied at bulbing.

Effects of substrate type on plant growth and nitrogen and nitrate concentration in spinach.

The effects of three commercial substrates (a mixture of forest residues, composted grape husks, and white peat, black peat and coir) on plant growth and nitrogen (N) and nitrate (NO3) concentration and content were evaluated in spinach (Spinacia oleracea L. cv. Tapir). Spinach seedlings were transplanted at 45 days after emergence into Styrofoam boxes filled with the substrates and were grown during winter and early spring in an unheated greenhouse with no supplemental lighting. Each planting box was irrigated daily by drip and fertilized with a complete nutrient solution. The NO3 content of the drainage water was lower in coir than in the other substrates. However, shoot NO3 concentration was not affected by substrate type, while yield and total shoot N and NO3 content were greater when plants were grown in peat than in the mixed substrate or the coir. Leaf chlorophyll meter readings provided a good indication of the amount of N in the plants and increased linearly with total shoot N.

Effects of nitrogen level on purslane antioxidant activity.

The high antioxidant activity of purslane, Portulaca oleracea L., gives it a high nutritional and functional value. The commercial production of purslane has increased in Portugal, making it necessary to know the effects of inputs, mainly nitrogen, on the antioxidant activity. The main goal of this study was to evaluate the influence of nitrogen application on purslane antioxidant activity. The experiment was carried out with for treatments: 30, 60 and 90 kg/ha of nitrogen. Plants of golden-leaf purslane were grown in Styrofoam-boxes filled with substrate and fertigated two times per week, over four weeks with ammonium nitrate solution (16.9% NO3-N and 16.7 NH4+-N). The increase in the nitrogen level decreased the water-soluble proteins content. However the ascorbate, phenols content as well as antioxidant activity measured by FRAP method was not affected by nitrogen level. Plants shoot antioxidant activity, measured by DPPH method decreased significantly in the treatment with 90 kg N/ha (26.20 g/g gallic acid). On the other hand, plant shoot antioxidant activity mediated by peroxidases was higher in treatment 30 kg N/ha (0.459 µmol min-1/mg prot.). Application of 60 kg N/ha allowed a vigorous plant growth without disturb its antioxidants and conservation properties.