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271.
An inhibitor of urease activity effectively reduces ammonia emissions from soil treated with urea under Mediterranean conditions 总被引:4,自引:0,他引:4
Alberto Sanz-Cobena Thomas H.Misselbrook Augusto Arce Juan I. Mingot Jose Antonio Diez Antonio Vallejo 《Agriculture, ecosystems & environment》2008,126(3-4):243-249
Urea is an important source of ammonia (NH3) emissions to the atmosphere from agricultural soils. Abatement strategies are necessary in order to achieve NH3 emission targets by reducing those emissions. In this context, a field experiment was carried out on a sunflower crop in spring 2006 with the aim of evaluating the effect of the N-(n-butyl) thiophosphoric triamide (NBPT) in the mitigation of volatilized NH3 from a urea-fertilised soil. Ammonia emission was quantified, using the integrated horizontal flux (IHF) method, following application of urea with and without the urease inhibitor NBPT. Urea and a mixture of urea and NBPT (0.14%, w/w) were surface-applied at a rate of 170 kg N ha−1 to circular plots (diameter 40 m). The soil was irrigated with 10 mm of water just after the application of urea to dissolve and incorporate it into the upper layer of soil. Over the duration of the measurement period (36 days) three peaks of NH3 were observed. The first peak was associated with hydrolysis of urea after irrigation and the others with the increase of ammonia in soil solution after changes in atmospheric variables such as wind speed and rainfall. The total NH3 emission during the whole experiment was 17.3 ± 0.5 kg NH3–N ha−1 in the case of urea treated soils and 10.0 ± 2.2 kg NH3–N ha−1 where NBPT was included with the urea (10.1 and 5.9%, respectively, of the applied urea–N). The lower NH3 emissions from plots fertilised with urea + NBPT, compared with urea alone, were associated with a reduction in urease activity during the first 9 days after inhibitor application. This reduction in enzymatic activity promoted a decrease in the exchangeable NH4+ pool. 相似文献
272.
Delesposte Jamile Eleutério Rangel Luís Alberto Duncan Meiriño Marcelo Jasmim Narcizo Ramon Baptista Alencar Junior André Armando Mendonça de 《The Environmentalist》2021,41(4):501-522
Environment Systems and Decisions - Sustainable innovation has gained prominence in recent years, due to the demands imposed by global competition, social pressures and the needs of consumers and... 相似文献
273.
Alberto Fonseca Patricia Fitzpatrick Mary Louise McAllister 《Natural resources forum》2013,37(4):211-220
The socio‐economic fabric of single‐company mining towns needs to be carefully considered by both Government and companies in sustainability policymaking. Policy design and effectiveness in such towns are significantly impacted by the city's economic dependence on a single company. This paper explores the perceived effectiveness of government and voluntary private sector mining policies for pursuing sustainability in the historic mining town of Itabira, Brazil over a period of 20 years. Itabira serves as a worthwhile case study because it allows for an in‐depth and longitudinal analysis that can reveal valuable lessons to policymakers of different sectors and jurisdictions located elsewhere. Based on extensive face‐to‐face interviews and literature reviews, study results indicate that changes to the state environmental licensing policies in the 1990s led to significant socio‐environmental improvements in the area. The globalization of the mining company also contributed to an increase in the quantity and quality of voluntary industry policies. Recent technological improvements in the beneficiation processes of the mining company promises to extend the life of the mine to 2050. Although there are significant incremental socio‐environmental policies and programmes, sustainability remains an elusive vision in Itabira, with no clear objectives or monitoring and accountability mechanisms. The paper concludes by recommending a more formal integrated policymaking framework. 相似文献
274.
Microwave and Fenton's reagent oxidation of wastewater 总被引:16,自引:0,他引:16
J.?Sanz J.?I.?Lombra?aEmail author A.?M.?De Luis M.?Ortueta F.?Varona 《Environmental Chemistry Letters》2003,1(1):45-50
We compared two H2O2 oxidation methods for the treatment of industrial wastewater: oxidation using Fenton's reagent [H2O2/Fe(II)] and microwave irradiation. Both methods were applied to the treatment of synthetic phenol solutions (100 mg L−1) and of an industrial effluent containing a mixture of ionic and non-ionic surfactants at high load (20 g L−1 of COD). The effects of initial pH, initial H2O2 concentration, Fenton catalyst amount and irradiation time were assessed. According to the oxidation of phenol, it has been
found that the oxidation by Fenton's reagent is dependent on the pH, contrary to the microwave system, which is not influenced
by this parameter. For both systems, a limiting amount of oxidant has been found; above this point the oxidation of phenol
is not improved by a further addition of peroxide. The oxidation of the industrial surfactant effluent has only been successful
with the Fenton's reagent. In this case, large amounts of ferrous ions are necessary for the precipitation of the ionic surfactants
of the effluent, followed by the oxidation of the non-ionic constituents of the solution.
Electronic Publication 相似文献
275.
276.
277.
María Oliveira Rosa M. Crujeiras Alberto Rodríguez-Casal 《Environmental and Ecological Statistics》2014,21(1):143-159
Smoothing methods and SiZer (SIgnificant ZERo crossing of the derivatives) are useful tools for exploring significant underlying structures in data samples. An extension of SiZer to circular data, namely CircSiZer, is introduced. Based on scale-space ideas, CircSiZer presents a graphical device to assess which observed features are statistically significant, both for density and regression analysis with circular data. The method is intended for analyzing the behavior of wind direction in the atlantic coast of Galicia (NW Spain) and how it has an influence over wind speed. The performance of CircSiZer is also checked with some simulated examples. 相似文献
278.
Patricia N. Pochelon Teresa Lopes da Silva Alberto Reis Antonina dos Santos Henrique Queiroga Ricardo Calado 《Marine Biology》2011,158(12):2825-2833
The present study investigated the existence of inter-individual and within-brood variability in the fatty acid (FA) profile
of developing embryos of Nephrops norvegicus. In all surveyed females (n = 5), the quantitatively most important FAs were as follows: 22:6n-3 (20.8 ± 3.9% average of total FA ± standard error),
18:1n-9 (19.5 ± 2.0%), 16:0 (15.2 ± 3.4%), 20:5n-3 (10.2 ± 1.4%), 16:1n-7 (8.9 ± 1.6%), and 18:1n-7 (5.7 ± 1.3%). Differences
in FA profiles of embryos in the same clutch were assessed using brooding chamber side (left and right) and pleopod (1st and
2nd, 3rd and 4th, and 5th) as predictive factors. There were no significant differences in the FA composition of embryos sampled
from both sides of the brooding chamber in 4 of the 5 surveyed females. However, all females exhibited significant differences
in the FA profiles of embryos sampled from different pleopods. Both saturated FA (SFA) and highly unsaturated FA (HUFA) present
in developing embryos exhibited marked differences along the breeding chamber. Overall, FA reserves appeared to vary significantly
within broods, which can ultimately be reflected on early larval survival. A potential cause for the within-brood variation
recorded in the FA profile of developing embryos include (1) differential female investment during ovarian maturation, mainly
due to variation in food quality/availability; (2) differential lipid catabolism during the incubation period of developing
embryos, as a consequence of embryos position within the female’s brooding chamber; or (3) differential female investment
during ovarian maturation amplified by differential lipid catabolism during the incubation period. 相似文献
279.
The crucial role of the accessible area in ecological niche modeling and species distribution modeling 总被引:4,自引:0,他引:4
Narayani BarveVijay Barve Alberto Jiménez-Valverde Andrés Lira-NoriegaSean P. Maher A. Townsend Peterson Jorge SoberónFabricio Villalobos 《Ecological modelling》2011,222(11):1810-1819
Using known occurrences of species and correlational modeling approaches has become a common paradigm in broad-scale ecology and biogeography, yet important aspects of the methodology remain little-explored in terms of conceptual basis. Here, we explore the conceptual and empirical reasons behind choice of extent of study area in such analyses, and offer practical, but conceptually justified, reasoning for such decisions. We assert that the area that has been accessible to the species of interest over relevant time periods represents the ideal area for model development, testing, and comparison. 相似文献
280.
Marmolejo-Rodríguez AJ Sánchez-Martínez MA Romero-Guadarrama JA Sánchez-González A Magallanes-Ordóñez VR 《Journal of environmental monitoring : JEM》2011,13(8):2182-2189
Extensive waste deposits (tailings) and ash from the ignition oven of the abandoned gold mine of mining district El Triunfo (MD-ET) in Baja California Sur, Mexico have released trace elements into the sediments of the Hondo-Las Gallinas-El Carrizal arroyo, which connects to the Pacific Ocean through an evaporitic basin. Migration of these elements through the arroyo is mainly caused by winds or tropical hurricanes that occur sporadically during the summer and cause the otherwise dry arroyo to overflow. To evaluate the concentration and distribution of the elements As, Hg, Pb, and Zn along the 48 km arroyo, surface sediments were collected from 26 sites, ranging from close to the MD-ET to the mouth of the arroyo at the Pacific Ocean. Concentrations in tailings and ash were for As 8890 and 505?000 mg kg(-1); for Hg 0.336 and 54.9 mg kg(-1); for Pb 92,700 and 19,300 mg kg(-1); and for Zn 49,600 and 1380 mg kg(-1). The average of the Normalized Enrichment Factor (Av-NEF) in surface sediments, calculated using background levels, indicates that the sediments are severely contaminated with As and Zn (Av-NEF = 22), Pb (Av-NEF = 24) and with a moderate contamination of Hg (Av-NEF = 7.5). The anthropogenic influence of those elements is reflected in the arroyo sediments as far as 18 km away from the MD-ET, whereas the samples closest to the discharge into the Pacific Ocean show a natural to moderate enrichment for As and Zn and low or no enrichment for Hg and Pb. A principal components analysis identified four principal components that explained 90% of the total variance. Factor 1 was characterized by a high positive contribution of the anthropogenic source elements, especially As, Pb, and Zn (37%), whereas Factor 2 was strongly correlated with the oxy-hydroxides of Fe and Mn (27%). Factor 3 was correlated with Li (16%) and Factor 4 with Al (10%), which indicates more than one source of lithogenic composition, though they played a minor role in the distribution of the elements. 相似文献