The practice of adding substances to make water safe to drink and its consequential effects on human health have been a contentious matter for a long time. In this study, the addition of fluoride in drinking water was evaluated after examining two different countries: Britain and Turkey. This study has used an independent and ethical approach taking into account the cautious but assertive dentists’ comments on the addition of fluoride for years. This research focuses on a comparative analysis of Britain, an advanced economy, and Turkey, a developing country, supported with tangential reference to worldwide practice in general. Drawing on ongoing studies, the research analyses empirical evidence and arguments to conduct an assessment of Turkey’s practices. The ethical argument about fluoridation focuses on the question of adequate evidence for its health benefits and the autonomy of the consumer. As the consumer is not fully consulted about this practice, it could be argued that the will of the consumer can be put to the test in the democratic process. Hence, the key to any policy has to be about both clarity of the national government intention and continued engagement with consumer groups at regional level. 相似文献
Alginates are natural polymers composed of mannuronic and guluronic acid residues. They are currently extracted from brown algae; however, alginate can also be synthesized by some species of Azotobacter and Pseudomonas. Alginates with different proportion of mannuronic and guluronic acids are known to have different characteristics and form gels at different extents in the presence of calcium ions. The aim of this work was to investigate the usefulness of alginate as a non-toxic coagulant used in purification of drinking water. This study utilized alginates from Azotobacter vinelandii having different guluronic acid levels. These were obtained partly by changing the cultivation parameters, partly by epimerizing a purified alginate sample in vitro using the A. vinelandii mannuronan C-5 epimerase AlgE1. The different alginates were then used for coagulation together with calcium. The results showed that turbidity removal capability was dependent on the content of guluronic acid residues. For the best performing samples, the turbidity decreased from 10 NTU to 1 NTU by the use of only 2 mg/L of alginate and 1.5 mM of calcium chloride.
Excessive doses of toxic metals such as cobalt may cause detrimental hazards to exposed organisms. Six groups of onion bulbs were formed to investigate the therapeutic effects of grape seed extract (GSE) against cobalt(II) nitrate (Co(NO3)2) exposure in Allium cepa L. root tips. Control group was irrigated with tap water, while the latter groups were exposed to 150 mg/L GSE, 300 mg/L GSE, 5.5 ppm Co(NO3)2, 5.5 ppm Co(NO3)2 + 150 mg/L GSE and 5.5 ppm Co(NO3)2 + 300 mg/L GSE, respectively. Co(NO3)2 treatment seriously inhibited the root growth, germination and weight gain of the bulbs. Mitotic index was significantly decreased, whereas the chromosomal aberrations and micronuclei incidence exhibited a remarkable increase. In addition, Co(NO3)2 induced a variety of anatomical disorders in onion roots. Lipid peroxidation levels of the cellular membranes were assessed measuring the malondialdehyde content (MDA). MDA amount in Co(NO3)2-treated group reached the highest level among all groups. Co(NO3)2 treatment enhanced the activity of superoxide dismutase and catalase. The addition of GSE to Co(NO3)2 solution substantially suppressed the negative effects of Co(NO3)2 in a dose-dependent manner by strengthening the antioxidant defence system and reducing the cytotoxicity. Moreover, there was a significant recovery in growth parameters following the grape seed addition to Co(NO3)2. GSE had a remarkable reduction in genotoxicity when treated as a mixture with Co(NO3)2. Overall data obtained from this investigation proved that GSE, as a promising functional by-product, had a protective effect on Allium cepa L. against the toxic effects of Co(NO3)2.
Environmental Science and Pollution Research - This study aims to test the effects of the number of tourist arrivals and tourism receipts on carbon emissions for the Mediterranean countries. The... 相似文献
The leather industry is an industry which generates a large amount of solid and liquid wastes. Most of the solid wastes originate from the pre-tanning processes while half of it comes from the fleshing step. Raw fleshing wastes which mainly consist of protein and fat have almost no recovery option and the disposal is costly. This study outlines the possibility of using the fleshing waste as an oil source for transesterification reaction. The effect of oil/alcohol molar ratio, the amount of catalyst and temperature on ester production was individually investigated and optimum reaction conditions were determined. The fuel properties of the ester product were also studied according to the EN 14214 standard. Cold filter plugging point and oxidation stability have to be improved in order to use the ester product as an alternative fuel candidate. Besides, this product can be used as a feedstock in lubricant production or cosmetic industry. 相似文献
The use of fuzzy multiple criteria analysis (MCA) in solid waste management has the advantage of rendering subjective and implicit decision making more objective and analytical, with its ability to accommodate both quantitative and qualitative data. In this paper a modified fuzzy TOPSIS methodology is proposed for the selection of appropriate disposal method and site for municipal solid waste (MSW). Our method is superior to existing methods since it has capability of representing vague qualitative data and presenting all possible results with different degrees of membership. In the first stage of the proposed methodology, a set of criteria of cost, reliability, feasibility, pollution and emission levels, waste and energy recovery is optimized to determine the best MSW disposal method. Landfilling, composting, conventional incineration, and refuse-derived fuel (RDF) combustion are the alternatives considered. The weights of the selection criteria are determined by fuzzy pairwise comparison matrices of Analytic Hierarchy Process (AHP). It is found that RDF combustion is the best disposal method alternative for Istanbul. In the second stage, the same methodology is used to determine the optimum RDF combustion plant location using adjacent land use, climate, road access and cost as the criteria. The results of this study illustrate the importance of the weights on the various factors in deciding the optimized location, with the best site located in Çatalca. A sensitivity analysis is also conducted to monitor how sensitive our model is to changes in the various criteria weights. 相似文献
In this study, Reactive Black 5 (RB5) was removed from synthetic wastewater using Fenton's oxidation (FO) process. Experiments were conducted on the samples containing 100 and 200 mg l(-1) of RB5 to remove the dye toxicity. Seventy-five milligram per litre of RB5 caused 25% toxicity on 24-h born daphnids whereas 100 mg l(-1) of RB5 displayed 100% toxicity on Daphnia magna. The study was performed in a systematic approach searching optimum values of FeSO(4) and H(2)O(2) concentrations, pH and temperature. Optimum pH and temperature for 100 mg l(-1) of RB5 were observed as 3.0 and 40 degrees C, respectively, using 100 mg l(-1) of FeSO(4) and 400 mg l(-1) of H(2)O(2) resulted in 71% chemical oxygen demand (COD) and 99% color removal. For 200 mg l(-1) of RB5, 84% COD removal was obtained using 225 mg l(-1) of FeSO(4) and 1000 mg l(-1) of H(2)O(2) yielding 0.05 molar ratio at pH 3.0 and 40 degrees C. Color removal was also more than 99%. The optimum conditions determined in accordance with the literature data. The H(2)O(2) requirement seems to be related to initial COD of the sample. FeSO(4)/H(2)O(2) ratios found were not changed for both concentrations. The temperature affected the COD removal significantly at high degrees. Toxicity was completely removed for each concentration of RB5 at optimum removal conditions. 相似文献