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481.
D.?FattaEmail author Z.?Salem M.?Mountadar O.?Assobhei M.?Loizidou 《The Environmentalist》2004,24(4):227-236
As freshwater becomes increasingly scarce due to population growth, urbanisation and, probably, climate change, the use of wastewater in agriculture, aquaculture, groundwater recharge and in other areas will increase. In some cases, wastewater is the only water resource available to poor, subsistence-level farming communities. Although there are benefits to using wastewater in agriculture—such as better nutrition and food security for many households—uncontrolled use of wastewater is frequently associated with significant negative human health impacts. These health impacts can be minimized when good management practices are implemented. In this paper the existing situation, in relation to water resources availability, wastewater treatment and reuse in Morocco and Palestine, is presented. 相似文献
482.
Phosphorus losses to water from lowland rice fields under rice-wheat double cropping system in the Tai Lake region 总被引:10,自引:0,他引:10
To assess P losses to surface water by runoff during the rice season and by drainage flow during the winter wheat season, serial field trials were conducted in different types of paddy soils in the Tai Lake Region (TLR) during 2000 and 2001. Four P application rates were set as 0 (CK), 30, 150, and 300 kg P/hm2 for flooded rice trials and 0 (CK), 20, 80, 160 kg P/hm2 for winter wheat trials respectively. Field experiments were done in two locations with a plot size of 30 m2 and four replications in a randomized complete block design. A simplified lysimeter was installed for each plot to collect all the runoff or drainage flow from each event. Total P (TP) losses to surface water during rice season by runoff flow from four treatments were 150 (CK), 220 (T30), 395 (T150), 670 (T300) g P/ hm2 in year 2000, and 298, 440, 1828, 3744 g P/hm2 in year 2001 respectively in Wuxi station, here the soil is permeable paddy soil derived from loam clay deposit. While the losses were 102, 140, 210, 270 in year 2000, and 128, 165, 359, 589 g P/hm2 in year 2001 respectively in Changshu station, here the soil is waterlogged paddy soil derived from silt loam deposit. During the winter wheat season, total P lost from the fields by drainage flow in the four treatments were 253 (CK), 382 (T20), 580 (T89), 818 (T160) g P/hm2 in year 2000--2001, and 573.3, 709.4, 1123.2, 1552.4 g P/hm2 in year 2001--2002 at the Wuxi station. While these were 395.6, 539.1, 1356.8, 1972.1 g P/hm2 in year 2000--2001, and 811.5, 1184.6, 3001.2, 5333.1 g P/hm2 in year 2001--2002 at the Changshu station. Results revealed that P fertilizer application rates significantly affected the TP concentrations and TP loads in runoff during the rice season, and by drainage flow during the winter wheat season. Both TP loads were significantly increased as the P application rate increases. The data indicate that TP losses to surface water were much higher during the winter wheat season than during the rice season in two tested sites. The data also reveal that the annual precipitation and evaporation rate affected the soil P losses to surface water significantly. Year 2000 was relatively dried with higher evaporation thus P losses to water by both runoff and drainage flow were less than in year 2001 which was a relatively wet year with lower evaporation. Results indicate that texture, structure of the soil profile, and field construction (with or without ridge and deep drains) affected soil P losses to surface water dramatically. Annual possible TP lost to water at the application rate of 50 kg P/hm2 year tested in TLR were estimated from 97 to 185 tones P from permeable paddy soils and 109-218 tones P from waterlogged paddy soils. There was no significant difference of TP lost between the CK and the T50 treatments in both stations, which indicate that there is no more TP lost in field of normal P fertilizer application rate than in control field of no P fertilized. Much higher TP lost in runoff or drainage flow from those other P application rates treatments than from the T50 treatment, which suggest that P losses to surface water would be greatly increasing in the time when higher available P accumulation in plough layer soil in this region. 相似文献
483.
Determination of depleted uranium in environmental samples by gamma-spectroscopic techniques 总被引:1,自引:0,他引:1
Karangelos DJ Anagnostakis MJ Hinis EP Simopoulos SE Zunic ZS 《Journal of environmental radioactivity》2004,76(3):295-310
The military use of depleted uranium initiated the need for an efficient and reliable method to detect and quantify DU contamination in environmental samples. This paper presents such a method, based on the gamma spectroscopic determination of 238U and 235U. The main advantage of this method is that it allows for a direct determination of the U isotope ratio, while requiring little sample preparation and being significantly less labor intensive than methods requiring radiochemical treatment. Furthermore, the fact that the sample preparation is not destructive greatly simplifies control of the quality of measurements. Low energy photons are utilized, using Ge detectors efficient in the low energy region and applying appropriate corrections for self-absorption. Uranium-235 in particular is determined directly from its 185.72 keV photons, after analyzing the 235U-226Ra multiplet. The method presented is applied to soil samples originating from two different target sites, in Southern Yugoslavia and Montenegro. The analysis results are discussed in relation to the natural radioactivity content of the soil at the sampling sites. A mapping algorithm is applied to examine the spatial variability of the DU contamination. 相似文献
484.
Sansone U Belli M Jeran Z Kanivets VV Radojko J Riccardi M Voitsekhovitch OV 《Journal of environmental radioactivity》2002,59(3):257-271
Suspended particle adhesion on aquatic biota can significantly increase the apparent concentration of radionuclides above their endogenous value, leading to an overestimation of the uptake rate and concentration ratios. This study is an attempt to assess quantitatively the importance of suspended particle adhesion on periphyton samples (biological material coating submerged surfaces). The concentrations of 137Cs and stable Cs (133Cs) in periphyton, suspended particles and filtered water were measured to determine the net water-to-periphyton concentration ratios for 137Cs and stable Cs. The net amount of 133Cs (or 137Cs) taken up by periphyton was calculated by subtracting from the total amount of 133Cs (or 137Cs) on the collected material (periphyton + inorganic particles), the 133Cs (or 137Cs) due to the inorganic particles adhering to periphyton. The mass of suspended particles adhering to the periphyton surface was calculated using scandium as an indicator of the mineral fraction of the suspended particles. The relationship between the concentration ratios for 137Cs and stable Cs and suspended particle adhesion on periphyton external surfaces is discussed. 相似文献
485.
Ould-Dada Z Tucker S Webbe-Wood D Mondon K Hunt J 《Journal of environmental radioactivity》2002,59(3):273-291
This paper presents the method used by the UK Food Standards Agency (FSA) to assess the potential impact of proposed radioactive discharges from the Sellafield nuclear site on food and determine their acceptability. It explains aspects of a cautious method that has been adopted to reflect the UK government policy and uncertainties related to people's habits with regard to food production and consumption. Two types of ingestion doses are considered in this method: 'possible' and 'probable' doses. The method is specifically applied to Sellafield discharge limits and calculated possible and probable ingestion doses are presented and discussed. Estimated critical group ingestion doses are below the dose limit and constraint set for members of the public. The method may be subject to future amendments to take account of changes in government policy and the outcome of a recent Consultative Exercise on Dose Assessments carried out by FSA. Uncertainties inherent in dose assessments are discussed and quantified wherever possible. 相似文献
486.
Suitability of dye-clay complexes for removal of non-ionic organic compounds from aqueous solutions 总被引:2,自引:0,他引:2
Aqueous sorption of phenol, atrazine and naphthalene was measured on complexes formed from Na-montmorillonite (Fischer bentonite) and the organic cationic dyes crystal violet and rhodamine-B. Sorption isotherms were found to be non-linear. This agrees well with the rigid nature of the dye-clay organic coverage, which provides a finite surface for adsorption. High values of organic carbon-normalized distribution coefficients reached 20,000-25,000 for atrazine on rhodamine-B-montmorillonite, 7000 for atrazine on crystal violet-montmorillonite, and 1500 for phenol on crystal violet-montmorillonite. As such, dye-clays may significantly extend the variety of organoclay sorbents that effectively reduce aqueous concentrations of non-ionic organic compounds. 相似文献
487.
Effects of trifluralin on soil microbial populations and the nitrogen fixation activities 总被引:6,自引:0,他引:6
Hang M Zhongyun C Yuhua Z Meichi C 《Journal of environmental science and health. Part. B》2001,36(5):569-579
Effects of trifluralin on soil microbial populations and the nitrogen fixation activity of nitrogen-fixing bacteria Azotobacter chroococcum and Bradyrhizobium japonicum and the decomposition of trifluralin by soil microorganisms were studied. Trifluralin at lower concentrations from 0.5 mg microg(-1) dry soil to lower than 10.0 mg microg(-1) dry soil appeared to stimulate the growth of soil bacteria, actinomycetes, mould, and the pure cultures of Br. japonicum and A. chroococcum. Not only the colony amounts of these two species of nitrogen-fixing bacteria increased, grown on agar medium containing lower concentrations of trifluralin, but also these colonies also enlarged in size and appeared obviously in shorter formation time. However, trifluralin at higher concentrations would inhibit the development of microbial colonies both in amount and size. Trifluralin inhibited the activity of acetylene reduction of A. chroococcum when it was added at the same time of inoculation with A. chroococcum, but it showed a noteworthy stimulation to nitrogen fixation of A.chroococcum when it was put into culture after the cells of the nitrogen-fixing bacterium had grown well. The observation that soil microorganisms could use trifluralin as sole carbon and nitrogen resources for their growth, indicated that microorganisms could decompose trifluralin well. 相似文献
488.
One of the roles of the BIOMASS Theme 3 Fruit Working Group was to identify significant radionuclides to support its work programme. This paper provides a short review of radionuclide emissions to atmosphere together with comments on their relative dosimetric impacts to identify those radionuclides most relevant to the Fruit Working Group. Speciation of the identified radionuclides is also discussed to identify the most likely chemical forms to which fruits might be exposed. It is noted that no information currently exists on radionuclide speciation in regard to the uptake and retention of radionuclides in fruit crops. 相似文献
489.
An encapsulation system designed to give long-lasting effectiveness of the insect growth regulator (IGR) cyromazine (Neporex) against Culex pipiens (Culicidae) mosquito larvae was developed. The main thrust of the research was to develop a simple method for preparing controlled-release formulations by means of an extrusion technique in combination with a supplementary coating and to study the release characteristics and effectiveness of the formulations. A series of formulations were prepared with low-density polyethylene (LDPE 600) for the matrix and with polyurea or one of four types of polyurethane for the coating. The rate of release of the active material from the controlled-release formulations was determined in an in vitro dissolution system. The biological activity of the controlled-release formulations was tested in vivo against C. pipiens larvae. 相似文献
490.
Z Samaras T Zachariadis R Joumard D Hassel F J Weber R Rijkeboer 《Journal of the Air & Waste Management Association (1995)》2001,51(6):913-938
This paper provides an overview and the main results of a study aiming to evaluate current and alternative inspection and maintenance (I/M) programs to control emissions from in-use cars in Europe. For this purpose, a large number of passenger cars from five countries (France, Germany, Greece, the Netherlands, and the United Kingdom) were tested according to a common test protocol that included a variety of driving cycles and short tests, both legislative and specifically developed for this exercise. Evaluation of all test results was conducted with the objective of defining effective I/M test procedures and examining the potential of periodic I/M programs to reduce pollutant emissions and improve fuel economy of in-use cars. The results indicate that the current idle test used for catalyst-equipped cars in Europe is probably ineffective, while short transient loaded testing was found to offer higher potential in environmental terms. Regarding conventional gasoline cars, it is concluded that the idle test is sufficient, provided that the CO cut point is reduced and an HC test is added at high idle. Finally, the effectiveness of the free acceleration smoke test for diesels is questioned, while a transient cycle with continuous opacity measurement was found to be very promising. A companion paper further uses these results to analyze the likely cost-effectiveness on a per-country basis and discusses the possible effect of maintenance on emissions. 相似文献