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N. Sanginga K. E. Dashiell J. Diels B. Vanlauwe O. Lyasse R. J. Carsky S. Tarawali B. Asafo-Adjei A. Menkir S. Schulz B. B. Singh D. Chikoye D. Keatinge R. Ortiz 《Agriculture, ecosystems & environment》2003,100(2-3):305
Sustainable resource management is the critical agricultural research and development challenge in sub-Saharan Africa. The accumulated knowledge on soil management gathered over the last 10 years, combined with solid crop improvement and plant health research at farmers’ level, has brought us to a stage where we can now address with confidence the intensification of cereal–grain–legume-based cropping systems in the dry savanna of West Africa in a sustainable and environmentally positive manner.Two sustainable farming systems that greatly enhance the productivity and sustainability of integrated livestock systems have been developed and implemented in the dry savanna of Nigeria. These are: (i) maize (Zea mays L.)–promiscuous soybean [Glycine max (L.) Merr.] rotations that combine high nitrogen fixation and the ability to kill large numbers of Striga hermonthica seeds in the soil; and (ii) miflet [Eleusine coracana (L.) Gaerth] and dual-purpose cowpea [Vigna unguiculata (L.) Walp.]. Improvement of the cropping systems in the dry savanna has been driven by the adoption of promiscuously nodulating soybean varieties (in particular TGx 1448-2E) and dual-purpose cowpea. The rate of adoption is very high, even in the absence of an efficient seed distribution system. The number of farmers cultivating the improved varieties increased by 228% during the last 3 years. Increased production of promiscuous soybean has been stimulated by increased demand from industries and home utilization. Production in Nigeria was estimated at 405,000 t in 1999 compared to less than 60,000 t in 1984. Economic analysis of these systems shows already an increase of 50–70% in the gross incomes of adopting farmers compared to those still following the current practices, mainly continuous maize cultivation. Furthermore, increases in legume areas of 10% in Nigeria (about 30,000 ha in the northern Guinea savanna) and increases of 20% in yield have translated into additional fixed nitrogen valued annually at US$ 44 million. This reflects, at the same time, an equivalent increase in land-use productivity, and with further spread of the improved crops, there are excellent prospects for additional economic and environmental benefits from a very large recommendation domain across West Africa. 相似文献
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Steve Caldwell Agnes Ortiz 《Journal of the Air & Waste Management Association (1995)》2013,63(6):801-807
The Comprehensive Environmental Response, Compensation, and Liability Act of 1980 required the federal government to establish criteria for setting priorities among releases of hazardous substances, pollutants, and contaminants. The U.S. Environmental Protection Agency responded by developing the Hazard Ranking System (HRS), which is a scoring system used to establish the National Priorities List (NPL). The Superfund Amendments and Reauthorization Act of 1986 required EPA to amend the HRS so it will more accurately assess relative risks and take into account certain specific elements of risk. On December 23,1988, EPA published in the Federal Register the proposed rule to revise the HRS.1 EPA expects to issue the final rule in 1990 after reviewing public comments. This paper describes the proposed revisions and summarizes major technical findings that support the revisions. As a result of the HRS revisions, there may be some changes in the types of sites that score high enough to be placed on the NPL. A projection of those changes is discussed. 相似文献
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Derek Vollmer Maíra Ometto Bezerra Natalia Acero Martínez Octavio Rodríguez Ortiz Ivo Encomenderos Maria Clara Marques Lina Serrano-Durn Isabelle Fauconnier Raymond Yu Wang 《Ambio》2021,50(4):870
Quantitative assessments have long been used to evaluate the condition of the natural environment, providing information for standard setting, adaptive management, and monitoring. Similar approaches have been developed to measure environmental governance, however, the end result (e.g., numeric indicators) belies the subjective and normative judgments that are involved in evaluating governance. We demonstrate a framework that makes this information transparent, through an application of the Freshwater Health Index in three different river basins in Latin America. Water Governance is measured on a 0–100 scale, using data derived from perception-based surveys administered to stakeholders. Results suggest that water governance is a primary area of concern in all three places, with low overall scores (Guandu-26, Alto Mayo-38, Bogotá-43). We conclude that this approach to measuring governance at the river basin scale provides valuable information to support monitoring and decision making, and we offer suggestions on how it can be improved.Electronic supplementary materialThe online version of this article (10.1007/s13280-020-01407-8) contains supplementary material, which is available to authorized users. 相似文献
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Ricardo Ortiz Kenji Enya Kazuhiko Sekiguchi Kazuhiko Sakamoto 《Atmospheric environment (Oxford, England : 1994)》2009,43(2):382-388
An annular denuder and filter-pack system was tested in combination with the use of the in-tube and on-fiber O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA)-derivatization technique to simultaneously sample and measure gaseous and particulate concentrations of semivolatile bifunctional carbonyl compounds in the atmosphere. Ozone was denuded from the sampling air to avoid oxidation and PFBHA was used as the sorbent by coating the sampling denuders and impregnating the filters. The collection efficiency of the system was evaluated under different conditions in photochemical smog chamber experiments and in field samplings of urban and suburban atmospheres. The effects of concentration level, temperature, and humidity on the collection efficiency were assessed. The system showed average collection efficiencies in one denuder from 81% for pyruvic acid and 82% for glyoxylic acid to 87% for hydroxyacetone and dihydroxyacetone. The capacity of the filters to collect the gaseous fraction that cannot be collected in the denuders was also evaluated, and the system allows a correction for this artifact. The application of this method to chamber experiments and field samplings offers an easy-to-apply technique with good results that can be used to evaluate the partition mechanisms of these compounds in the atmosphere. 相似文献
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Transport of simazine in unsaturated sandy soil and predictions of its leaching under hypothetical field conditions 总被引:2,自引:0,他引:2
Suárez F Bachmann J Muñoz JF Ortiz C Tyler SW Alister C Kogan M 《Journal of contaminant hydrology》2007,94(3-4):166-177
The potential contamination of groundwater by herbicides is often controlled by processes in the vadose zone, through which herbicides travel before entering groundwater. In the vadose zone, both physical and chemical processes affect the fate and transport of herbicides, therefore it is important to represent these processes by mathematical models to predict contaminant movement. To simulate the movement of simazine, a herbicide commonly used in Chilean vineyards, batch and miscible displacement column experiments were performed on a disturbed sandy soil to quantify the primary parameters and processes of simazine transport. Chloride (Cl(-)) was used as a non-reactive tracer, and simazine as the reactive tracer. The Hydrus-1D model was used to estimate the parameters by inversion from the breakthrough curves of the columns and to evaluate the potential groundwater contamination in a sandy soil from the Casablanca Valley, Chile. The two-site, chemical non-equilibrium model was observed to best represent the experimental results of the miscible displacement experiments in laboratory soil columns. Predictions of transport under hypothetical field conditions using the same soil from the column experiments were made for 40 years by applying herbicide during the first 20 years, and then halting the application and considering different rates of groundwater recharge. For recharge rates smaller than 84 mm year(-1), the predicted concentration of simazine at a depth of 1 m is below the U.S. EPA's maximum contaminant levels (4 microg L(-1)). After eight years of application at a groundwater recharge rate of 180 mm year(-1) (approximately 50% of the annual rainfall), simazine was found to reach the groundwater (located at 1 m depth) at a higher concentration (more than 40 microg L(-1)) than the existing guidelines in the USA and Europe. 相似文献
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Experiments were carried out to evaluate the use of some agroindustrial wastes as supports in solid state cultures for the biodegradation of crude oil Maya in static column reactors over 15-20 days periods. Spent compost and cane bagasse wastes showed superior qualities over peat moss waste as support candidates with the advantage that they contain appreciable densities of autochthonous microorganisms in the order of 10(2) cfu g(-1). Mercuric chloride (2%) was able to completely inhibit growth of these microfloras. Biodegradation was enhanced in the presence of the IMP consortium and highest when microflora from cane bagasse only was the bioaugmentation partner (180.7 mg kg(-1) day(-1)). Combination of these waste materials (3:1 ratio, respectively) was observed to significantly biodegrade the crude oil by approximately 40% in 15 days from an initial concentration of 10,000 mg kg(-1) with a four order of magnitude increase in microbial density during this period. Spent compost and cane bagasse wastes are veritable solid support candidates for use in the biodegradation of crude oil polluted systems. 相似文献