Search results for "Lag"
showing 10 items of 3124 documents
A review of soil carbon dynamics resulting from agricultural practices
2019
Abstract Literature related to the carbon cycle and climate contains contradictory results with regard to whether agricultural practices increase or mitigate emission of greenhouse gases (GHGs). One opinion is that anthropogenic activities have distinct carbon footprints – measured as total emissions of GHGs resulting from an activity, in this case, “agricultural operations”. In contrast, it is argued that agriculture potentially serves to mitigate GHGs emissions when the best management practices are implemented. We review the literature on agricultural carbon footprints in the context of agricultural practices including soil, water and nutrient management. It has been reported that the ma…
A shallow water SPH model with PML boundaries
2015
Abstract We focus on the study and implementation of Smoothed Particle Hydrodynamics (SPH) numerical code to deal with non-reflecting boundary conditions, starting from the Perfect Matched Layer (PML) approach. Basically, the method exploits the concept of a physical damping which acts on a fictitious layer added to the edges of computational domain. In this paper, we develop the study of time dependent shallow waves propagating on a finite 2D-XY plane domain and their behavior in the presence of circular and, more generic, rectangular boundary absorbing layers. In particular, an analysis of variation of the layer׳s thickness versus the absorbing efficiency is conducted. In our model, the m…
An economic, perception and biophysical approach to the use of oat straw as mulch in Mediterranean rainfed agriculture land
2017
[EN] Soil erosion is a key cause of land degradation in agriculture lands; and it is a worldwide threat that must be solved by means of nature-based strategies to be able to achieve sustainability. The use of mulches can be a solution, but there is a lack of information on long-term effects of the use of straw. Furthermore, little is known about the perception of farmers and the economic cost on the implantation of straw as a conservation measure. Eight paired plots were selected in Sierra de Enguera on an agriculture field to determine the effect of straw cover on soil erosion. Four plots were tilled three times per year (Control) and four plots were not ploughed and 0.125 kg m(-2) y(-1) o…
Long-term effects of contrasting tillage on soil organic carbon, nitrous oxide and ammonia emissions in a Mediterranean Vertisol under different crop…
2018
This 2-year study aimed to verify whether the continuous application of no tillage (NT) for over 20 years, in comparison with conventional tillage (CT), affects nitrous oxide (NO) and ammonia (NH) emissions from a Vertisol and, if so, whether such an effect varies with crop sequence (continuous wheat, WW and wheat after faba bean, FW). To shed light on the mechanisms involved in determining N-gas emissions, soil bulk density, water filled pore space (WFPS), some carbon (C) and nitrogen (N) pools, denitrifying enzyme activity (DEA), and nitrous oxide reductase gene abundance (nosZ gene) were also assessed at 0–15 and 15–30 cm soil depth. Tillage system had no significant effect on total NH e…
Two-stage anaerobic digestion of tomato, cucumber, common reed and grass silage in leach-bed reactors and upflow anaerobic sludge blanket reactors
2010
Abstract Anaerobic digestion of tomato, cucumber, common reed and grass silage was studied in four separate two-stage reactor configuration consisting of leach bed reactor (LBR) and upflow anaerobic sludge blanket reactor (UASB). LBR studies showed that COD solubilization for cucumber and grass silage was higher (50%) than tomato (35%) and common reed (15%). Results also showed that 31–39% of initial TKN present in tomato and cucumber was solubilized in the leachates and 47–54% of the solubilized TKN was converted to NH4-N. The corresponding values for common reed and grass silage were 38–50% and 18–36%, respectively. Biomethanation of the leachates in UASB reactors resulted in methane yiel…
The effect of organic loading rate and retention time on hydrogen production from a methanogenic CSTR.
2011
Abstract The possibility of shifting a methanogenic process for hydrogen production by changing the process parameters viz., organic loading rate (OLR) and hydraulic retention time (HRT) was evaluated. At first, two parallel semi-continuously fed continuously stirred tank reactors (CSTR) were operated as methanogenic reactors (M1 and M2) for 78 days. Results showed that a methane yield of 198–218 L/kg volatile solids fed (VS fed ) was obtained when fed with grass silage at an OLR of 2 kgVS/m 3 /d and HRT of 30 days. After 78 days of operation, hydrogen production was induced in M2 by increasing the OLR from 2 to 10 kgVS/m 3 /d and shortening the HRT from 30 to 6 days. The highest H 2 yield …
The use of mosses in biomonitoring of selected areas in Poland and Spitsbergen in the years from 1975 to 2014
2015
We have compared historical changes in concentrations of the heavy metals Mn, Ni, Cu, Zn, Cd and Pb accumulated in samples from the Polish woodlands of Beskidy and Karkonosze (S, SE Poland) and the north-east regions of the country, versus the relatively little polluted areas of Spitsbergen of the Svalbard Archipelago. We have combined the results from literature with new results from 2014. The regions of Beskidy and Karkonosze were the most exposed to heavy metals deposition. However, from 1975 to 2014 there was a considerable decrease of concentrations of Cu, Zn, Cd and Pb at all Polish sites, clearly signifying improvement of environmental quality. For example, the average Cd concentrati…
A legacy of contrasting spatial genetic structure on either side of the Atlantic-Mediterranean transition zone in a marine protist
2012
The mechanisms that underpin the varied spatial genetic structures exhibited by free-living marine microorganisms remain controversial, with most studies emphasizing a high dispersal capability that should redistribute genetic diversity in contrast to most macroorganisms whose populations often retain a genetic signature of demographic response to historic climate fluctuations. We quantified the European phylogeographic structure of the marine flagellate Oxyrrhis marina and found a marked difference in spatial genetic structure, population demography, and genetic diversity between the northwest Atlantic and Mediterranean Sea that reflects the persistent separation of these regions as well …
The Blue Flag Programme AS Pro-Environmental Behaviour Instrument for Coastal Destinations: Towards Municipal Coastal Governance and Communication
2021
The research focuses on evaluation of the Blue Flag programme implementation in Latvia since the year 1998, when the programme’s operations started. It includes analysis and an overview of both the national and local level impacts and the results of the programme implementation. With regard to national level, approach and experience, the overview focuses on effectiveness and the role of the Blue Flag programme as a supporting instrument for successful implementation of environmental legislation. This programme is also analysed as a communication instrument in promoting environmental policies within 500 km long of coastline areas, which in Latvia are announced the national interest territori…
A revision of the new world species of Polytrichophora Cresson and Facitrichophora, new genus (Diptera, Ephydridae)
2012
The New World species of Polytrichophora Cresson and Fascitrichophora new genus, are revised. Fifteen new species are described (type locality in parenthesis): Fascitrishophora atrella sp. n. (Costa Rica. Guanacaste: Murciélago [10°56.9’N, 85°42.5’W; sandy mud flats around mangrove inlet]), F. carvalhorum sp.n. (Brazil. São Paulo: Praia Puruba [23°21’S, 44°55.6’W; beach]), F. manza sp. n. (Trinidad and Tobago. Trinidad. St. Andrew: Lower Manzanilla (12 km S; 10°24.5’N, 61°01.5’W), bridge over Nariva River), F. panama sp. n. (Panama. Darien: Garachine [8°04’N, 78°22’W]), Polytrichophora adarca sp. n…