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221.
222.
Sewage sludge from four publicly-owned treatment works was sampled and characterized in terms of parameters affecting transport at the 106-mile deep ocean disposal site as part of the US Environmental Protection Agency's site monitoring programme. Samples from treatment plants in Passaic Valley, Rahway, and Elizabeth, New Jersey and New York City were characterized in terms of dynamic size distribution, suspended solids and density. the transport characteristics of sludge particles were measured using a 2 metre computer-interfaced laboratory settling column. Experiments were conducted at constant salinity (35 ppt) while varying hydrodynamic mixing, sludge type and concentration using a modified factorial experimental design. Hydrodynamic power dissipation was varied so that the vertical dispersion and rms fluid shear rate ranged between 0-6 cm2S-1 and 0-30s-1 respectively. Results indicate that at least 80% of suspended sludge particles will eventually settle under mixed conditions. the average settling velocities ranged between 0.05-4.05 × 10-3 cm s-1. Shear rates above 15 s-1 inhibited sludge settling due to aggregate breakup and boundary effects, but at a lower shear rate, differential settling and fluid shear were the dominant transport mechanisms. Sludge dilution (1/500-1/5000) had a limited effect on the settling rate. Results from this study can be used to calibrate particle transport models to determine the fate of sludge disposed at an ocean disposal site. 相似文献
223.
224.
Hasan Yazicigil Rashid I. Al-Layla Remy L. de Jong 《Journal of the American Water Resources Association》1987,23(3):423-434
ABSTRACT: This paper describes the formulation and application of a ground-water hydraulic management model to determine the optimal development and operating policies of a regional aquifer in the Eastern Province of Saudi Arabia. The hydraulic response of the aquifer system is represented by a simulation model that is linked to an optimization management model using response functions. Yearly optimal ground-water extraction rates over a planning horizon of 15 years are determined for four scenarios, each reflecting alternative ground-water development policies. The results are presented in the form of tradeoff curves, relating drawdowns to optimal pumpage, which may enhance the decisionmaker's ability to select the best development policy from a set of alternatives. The results illustrate how various optimal management schemes can be devised to increase the total withdrawal from the aquifer while preventing excessive de-watering. 相似文献
225.
Frederick A. Armah Justice O. Odoi Genesis T. Yengoh Samuel Obiri David O. Yawson Ernest K. A. Afrifa 《Mitigation and Adaptation Strategies for Global Change》2011,16(3):291-306
Desertification, climate variability and food security are closely linked through drought, land cover changes, and climate
and biological feedbacks. In Ghana, only few studies have documented these linkages. To establish this link the study provides
historical and predicted climatic changes for two drought sensitive agro-ecological zones in Ghana and further determines
how these changes have influenced crop production within the two zones. This objective was attained via Markov chain and Fuzzy
modelling. Results from the Markov chain model point to the fact that the Guinea savanna agro-ecological zone has experienced
delayed rains from 1960 to 2008 while the Sudan savanna agro-ecological zone had slightly earlier rains for the same period.
Results of Fuzzy Modelling indicate that very suitable and moderately suitable croplands for millet and sorghum production
are evenly distributed within the two agro-ecological zones. For Ghana to adapt to climate change and thereby achieve food
security, it is important to pursue strategies such as expansion of irrigated agricultural areas, improvement of crop water
productivity in rain-fed agriculture, crop improvement and specialisation, and improvement in indigenous technology. It is
also important to encourage farmers in the Sudan and Guinea Savanna zones to focus on the production of cereals and legumes
(e.g. sorghum, millet and soybeans) as the edaphic and climatic factors favour these crops and will give the farmers a competitive
advantage. It may be necessary to consider the development of the study area as the main production and supply source of selected
cereals and legumes for the entire country in order to free lands in other regions for the production of crops highly suitable
for those regions on the basis of their edaphic and climatic conditions. 相似文献
226.
Mignucci-Giannoni AA Montoya-Ospina RA Jiménez-Marrero NM Rodr&íguez-López MA Williams EH Bonde RK 《Environmental management》2000,25(2):189-198
Trichechus manatus ) in Puerto Rico is mortality due to human activities. We assessed 90 cases of manatee strandings in Puerto Rico based on
historical data and a coordinated carcass salvage effort from 1990 through 1995. We determined patterns of mortality, including
type of event, condition of carcasses, spatial and temporal distribution, gender, size/age class, and the cause of death.
The spatial distribution of stranding events was not uniform, with the north, northeast, and south coasts having the highest
numbers. Six clusters representing the highest incidence included the areas of Fajardo and Ceiba, Bahía de Jobos, Toa Baja,
Guayanilla, Cabo Rojo, and Rio Grande to Luquillo. The number of reported cases has increased at an average rate of 9.6%/yr
since 1990. The seasonality of stranding events showed a bimodal pattern, from February through April and in August and September.
Most identified causes of death were due to human interaction, especially captures and watercraft collisions. Natural causes
usually involved dependent calves. From 1990 through 1995, most deaths were attributed to watercraft collisions. A reduction
in anthropogenic mortality of this endangered species can be accomplished only through education and a proactive management
and conservation plan that includes law enforcement, mortality assessment, scientific research, rescue and rehabilitation,
and inter- and intraagency cooperation. 相似文献
227.
Hagos Ftwi Y. Abd Aziz Abd Rashid Zainal Ezrann Zharif Mofijur M. Ahmed Shams Forruque 《Environmental Chemistry Letters》2022,20(1):263-281
Environmental Chemistry Letters - Globally, 150–170 billion cubic metres of gas are being flared annually from petroleum refineries, petrochemical industries and from landfills. In this... 相似文献
228.
Rashid Sajid Rashid Wajid Tulcan Roberto Xavier Supe Huang Haiou 《Environmental science and pollution research international》2022,29(29):43675-43689
Environmental Science and Pollution Research - The excessive use of pesticides is posing major threats to humans and the environment. However, the environmental exposure and impact of pesticides in... 相似文献
229.
Attri Shivani Kaur Prabhjot Singh Davinder Kaur Harneetpal Rashid Farhana Kumar Avinash Singh Balbir Bedi Neena Arora Saroj 《Environmental science and pollution research international》2022,29(12):17189-17208
Environmental Science and Pollution Research - Argemone mexicana(Pepaveraceae) is an important medicinal plant commonly known as ‘maxican prickly poppy’ and is traditionally used to... 相似文献
230.
Sarfo Isaac Shuoben Bi Beibei Li Amankwah Solomon Obiri Yeboah Yeboah Emmanuel Koku John Ernest Nunoo Edward Kweku Kwang Clement 《Environment, Development and Sustainability》2022,24(8):9851-9883
Environment, Development and Sustainability - This study assesses the spatiotemporal development of land use systems and climate variability in Southwestern Ghana over the past five decades using... 相似文献