خيارات البحث
النتائج 1 - 10 من 1,997
Heavy Metal Pollution from Dental Clinics–Part 1:Annual Emissions Assessment
2020
Benaïssa, A. | Madjram, M. S. | Taouk, B. | Abdelouahed, L.
This study aimed to evaluate the concentration of heavy metals in liquid effluents and to quantify the mercury content in dental amalgam waste generated by dental clinics. Three neighbouring cities in Northeast Algeria were considered in this study (Constantine, Skikda, and Annaba). Heavy metals, such as Hg, Cu, Zn, Fe, Ni, Mn, Cr, Cd, and Pb, were analysed in wastewater and then compared with acceptable standard values. Special attention was given to mercurybecause of its dangerous effects. The results collected indicated the presence of heavy metal contamination in dental wastewater. Heavy metal concentrations were significantly high for all heavy metals and exceeded the allowed concentrations. However, Pb and Cr were shown to have acceptable concentrations. This study highlights the possible contamination of the environment by mercury and heavy metals generated by dental clinics. This study also demonstrates an order of magnitude of the concentration of these heavy metal in a large agglomeration with a population of 2.5 million people.
اظهر المزيد [+] اقل [-]Synthesis of Activated Carbon from Sugarcane Bagasse and Application for Mercury Adsorption
2019
Javidi Alsadi, k. | Esfandiari, N.
With the growth and development of chemical plants, the amount of mercury released in wastewater has increased. Mercury in wastewater contains harmful compounds which are hazardous to the human health and living organisms. Therefore, its removal from wastewater is significant. There are various techniques or methods available for removing mercury from aqueous solutions. This study focused upon the removal of mercury from aqueous solution with commercial activated carbon and activated carbon from sugarcane bagasse. Activated carbon produced from sugarcane bagasse was used as adsorbent. This adsorbent was used to remove mercury from aqueous solution. For this purpose, first, the optimal mercury solution pH for mercury removal was obtained. Effective parameters such as contact time, initial concentration of mercury, adsorbent dose and agitation speed were investigated. The mercury adsorption was increased when the mass of activated carbon was increased. Increasing the initial mercury concentration leads to decrease in mercury adsorption efficiency. The results of experiments indicated that the speed of the stirrer was not considered to be an effective factor in the mercury adsorption. Experiments were also carried out on a commercial activated carbon. Adsorption results obtained for sugarcane bagasse activated carbon were compared with commercial activated carbon. The adsorption efficiency was increased as the contact time was increased. Finally, the experiment was carried out on water samples released from South Pars platforms. In addition to the mercury removal, other heavy metals removal such as lead and cadmium were also carried out.
اظهر المزيد [+] اقل [-]Trends in organochlorine and mercury levels in gannet eggs.
1990
Newton I. | Haas M.B. | Freestone P.
Organochlorine and heavy metal contamination in non-viable eggs and its relation to breeding success in a Spanish population of lesser kestrels (Falco naumanni).
1993
Negro J.J. | Donazar J.A. | Hiraldo F. | Hernandez L.M. | Fernandez M.A.
Levels of polychlorinated biphenyls, organochlorine pesticides, mercury, cadmium, copper, selenium, arsenic, and zinc in the harbour seal, Phoca vitulina, in Norwegian waters.
1990
Skaare J.U. | Markussen N.H. | Norheim G. | Haugen S. | Holt G.
Historical changes of soil metal background values in select areas of China.
1991
Li J. | Wu Y.
Mercury antagonists: loss of phototactic response in the brine shrimp Artemia and its prevention by thiamine.
1986
Yaeger E. | Siegel B.Z. | Siegel S.M. | Lasconia M. | Correal T.
Factors affecting mercury concentrations in two oceanic cephalopods of commercial interest from the southern Caribbean
2021
Barcia, Laura Garcia | Pinzone, Marianna | Lepoint, Gilles | Pau, Cédric | Das, Krishna | Kiszka, Jeremy | FOCUS - Freshwater and OCeanic science Unit of reSearch - ULiège
peer reviewed | Mercury (Hg) concentrations have significantly increased in oceans during the last century. This element accumulates in marine fauna and can reach toxic levels. Seafood consumption is the main pathway of methylmercury (MeHg) toxicity in humans. Here, we analyzed total Hg (T-Hg) concentrations in two oceanic squid species (Ommastrephes bartramii and Thysanoteuthis rhombus) of an increasing commercial interest off Martinique, French West Indies. Stable isotope ratios reveal a negative linear relationship between δ15N or δ13C in diamondback squid samples. No significant trend was observed between δ34S values and T-Hg concentrations, contrasting with the sulfate availability and sulfide abundance hypotheses. This adds to a growing body of evidence suggesting Hg methylation via sulfate-reducing bacteria is not the main mechanism driving Hg bioavailability in mesopelagic organisms. All squid samples present T-Hg levels below the maximum safe consumption limit (0.5 ppm), deeming the establishment of a commercial squid fishery in the region safe for human consumption.
اظهر المزيد [+] اقل [-]Absence of selenium protection against methylmercury toxicity in harbour seal leucocytes in vitro
2016
Das, Krishna | Dupont, Aurélie | De Pauw-Gillet, Marie-Claire | Debier, Cathy | Siebert, Ursula | MARE - Centre Interfacultaire de Recherches en Océanologie - ULiège
peer reviewed | Previous studies described high concentrations of mercury (Hg) and selenium (Se) in the blood of harbour seals, Phoca vitulina from the North Sea. In the present study, we evaluated the in vitro potential protective effects of sodium selenite (Na2SeO3) and selenomethionine (SeMet) on cell proliferation of harbour seal lymphocytes exposed to MeHgCl 0.75 µM. In vitro exposure of ConA-stimulated T lymphocytes resulted in severe inhibition of DNA synthesis, likely linked to severe loss of mitochondrial membrane potential at 0.75 µM. Neither selenite nor SeMet showed a protective effect against MeHg toxicity expressed at the T lymphocyte proliferation level for harbour seals. Selenite and SeMet did not show negative effects regarding lymphocyte proliferation and mitochondrial membrane potential. To conclude, our results clearly demonstrated that MeHg affected in vitro immune cells exposure with no protective effects of selenium at a molar ratio Hg:Se of 1:10 in harbour seals from the North Sea.
اظهر المزيد [+] اقل [-]