Search

Total mercury and methylmercury concentrations were measured in sediments and marine organisms from the Taranto Gulf to understand their distribution and partitioning. Sediment concentrations ranged from 0.036 to 7.730 mg/kg (mean: 2.777 mg/kg d.w.) and from 1 to 40 μg/kg (mean: 11 μg/kg d.w.) for total mercury (THg) and methylmercury (Me-Hg), respectively. In mollusks THg ranged from n.d. to 1870 μg/kg d.w. while in fish from 324 to 1740 μg/kg d.w. Me-Hg concentrations in fish ranged from 190 to 1040 μg/kg d.w. and from n.d. to 1321 μg/kg d.w. in mollusks. THg exceeded the maximum level fixed by the European Commission (0.5 mg/kg w.w.) only in gastropod Hexaplex t. The calculated weekly intake was in many cases over the Provisional Tolerable Weekly Intake established by EFSA for all edible species. These results seem to indicate that dietary consumption of this seafood implicates an appreciable risk for human health., (Copyright © 2011 Elsevier GmbH. All rights reserved.)

Total mercury (THg) and methylmercury (Me-Hg) concentrations were determined in mussels (Mytilus galloprovincialis) from 10 stations located in the Mar Piccolo of Taranto (Ionian Sea, Taranto Gulf) an important semi-enclosed basin in Italy, devoted to mussel culture activities. The obtained results show that THg and Me-Hg concentrations ranged from 0.236 to 0.559 μg g(-1) d.w. and from 0.066 to 0.155 μg g(-1) d.w., respectively. Consequently, the Me-Hg/THg ratios ranged from 17% to 49%. The dietary intake of THg and Me-Hg were studied among children and adults from Taranto (Southern Italy). The estimated weekly intake for THg and Me-Hg was below the Provisional Tolerable Weekly Intake (PTWI) established by European Food Safety Autority (EFSA) for all sampled mussels, though their consumption provides a THg intake in children near the PTWI., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Optimization of acid digestion method for mercury determination in marine biological samples (dolphin liver, fish and mussel tissues) using a closed vessel microwave sample preparation is presented. Five digestion procedures with different acid mixtures were investigated: the best results were obtained when the microwave-assisted digestion was based on sample dissolution with HNO3-H2SO4-K2Cr2O7 mixture. A comparison between microwave digestion and conventional reflux digestion shows there are considerable losses of mercury in the open digestion system. The microwave digestion method has been tested satisfactorily using two certified reference materials. Analytical results show a good agreement with certified values. The microwave digestion proved to be a reliable and rapid method for decomposition of biological samples in mercury determination.

Selected toxic and essential metals (mercury, Hg; cadmium, Cd; and zinc, Zn) were determined in the liver and in the kidney collected from 13 dolphins (Stenella coeruleoalba and Tursiops truncatus) stranded along the southern coasts of Italy from 1991 to 1999. Liver samples were also analysed for their methyl mercury (MeHg) and selenium (Se) contents. For subcellular fractionation, liver and kidney samples were homogenized in Tris-HCl buffer; after centrifugation, the supernatant (cytosol) was separated from pellets (insoluble fraction), heated at 80 degrees C for 10 min and centrifuged in order to separate the precipitate containing the thermolabile high molecular weight proteins. The cytosol heat-stable fraction, including metallothionein-like proteins (MTLPs), was then purified by gel filtration chromatography on Sephadex G-75 column. The three subcellular fractions collected (insoluble fraction, thermolabile fraction and purified heat-stable fraction) were analysed for their Hg, Cd and Zn contents. The analytical results confirm previous similar studies on toothed whales in showing that: (1) in the liver, as well as in the kidney, Hg was mainly found in the insoluble fraction, therefore, metallothioneins seem to have no role in the Hg detoxification; (2) in the liver, the molar ratio between Se and inorganic Hg was very close to 1; this suggests that the final compound of MeHg detoxification could be HgSe (tiemannite); (3) in almost all the samples, Cd and Zn were detected in the purified heat-stable fraction (including MTLPs). The mechanism of Cd detoxification and Zn homeostasis is also discussed.

Tissues and organs from Stenella coeruleoalba stranded along the Apulian coasts (southern Italy) during the period April-July 1991 were analyzed for their mercury and selenium content. Analysis showed considerable variations in the mercury concentration in the examined organs and tissues. The highest concentrations of mercury were found in the liver (from 2.27 to 374.50 microg g(-1) wet wt.). After the liver, lung, kidney, muscle and brain were the most contaminated, while the lowest mercury contamination was found in the melon. As mercury, the liver also showed the highest selenium levels. Liver samples were also analyzed for their methyl mercury contents. The role of selenium in detoxification process of methyl mercury has been discussed. Mercury concentrations related to geographic variations and pollution of the marine environment have been examined. The possible implications between mercury accumulation and dolphin death have also been discussed.