Mercury uptake

Kelly CA, Rudd JWM, Holoka MH. 2003. Effect of pH on mercury uptake by an aquatic bacterium implications for Hg cycling. Environ Sci Technol 37 2941-2946. 

Monson BA, Brezonik PL. 1999. Influence of food, aquatic humus, and alkalinity on methyl-mercury uptake by Daphnia magna. Environ Toxicol Chem 18 560-566. 

Slotton DG, Reuter JE, Goldman CR. 1995. Mercury uptake patterns of biota in a seasonally anoxic northern California Reservoir. Water, Air Soil Pollut 80 841-850. 

The average THg concentration of all tissue samples (n = 285) was 0.2482 0.2546 pg/g, wet weight, ww, ranging from 0.0148 to 0.8052 pg/g. The highest levels were found at the factory site, close to the waste dumping point, followed by the meander, wildlife reserve, and reference sites (Table 1). This fact indicates an important mercury uptake by zebra mussels at the hot spot and redistribution to areas located immediately downstream and near to the river bank opposite the dumping site. 

Mean concentration of THg in tissue pooled samples (n = 34) was 1.49 0.22 (ig/g dw, ranging from 0.056 to 3.11 pg/g. The highest level was found at the factory site, located close to the waste dumping site. This result indicates an important mercury uptake by the specimens located at the hot spot and a limited redistribution to other areas close to the opposite river bank. 

And finally, additional research is needed on mercury accumulation and detoxification in comparatively pristine ecosystems. Key uncertainties in understanding the process of mercury uptake in aquatic ecosystems, for example, include relations between water chemistry and respiratory uptake, quantitative estimates of intestinal tract methylation and depuration, and degree of seasonal variability in mercury speciation and methylation-demethylation processes (Post et al. 1996). 

Wright, D.A., P.M. Welboum, and A.V.M. Martin. 1991. Inorganic and organic mercury uptake and loss by the crayfish Orconectes propinquus. Water Air Soil Pollut. 56 697-707. 

Selenium lessens the toxicity of divalent mercury in animals, the protection being less at continuous mercury exposure. Selenium has been found to affect the distribution of mercuric mercury in mice [134], rats [135], rabbits [136, 137] and pigs [ 138]. Mercury forms a mercury-selenium protein complex with selenium with little biological activity [139]. Mercury is thus retained longer in the blood, liver and spleen and as a consequence lessens accumulation in the kidney. In fish, selenium pretreatment probably retarded mercury uptake rather than promoting mercury excretion [140]. 

Luoma, S. N. Physiological characteristics of mercury uptake by two estuarine species. Mar. Biol. 1, 269-273 (19TT). 

There remains an intriguing inconsistency between experiments related to the mechanisms for mercury removal. Many lab, field, and model efforts indicate that the lifetime of mercury in the atmosphere must be 1 -2 yr, but there exist a number of plausible removal mechanisms (such as foliar mercury uptake followed by litterfall) that suggest the flux from the atmosphere is more consistent with lifetimes that are less than 1 yr. The likely resolution of this problem hes in the observation that majority of the Earth s surface is covered by areas that are not temperate or boreal forests, including the open ocean and tropical regions. The deposition to the ocean is consistent with an atmospheric residence time in excess of 1 yr, while the mercury cychng within tropical forests is understudied. 

Geijersstam E, Sandborgh-Englund G, Jonsson F, Ekstrand J. Mercury uptake and kinetics after ingestion of dental amalgam. J Dent Res 2001 80 1793-6. 

Dental amalgam restorations leak small amounts of elemental mercury vapor into the oral cavity of the mouth. The released mercury can be taken up by the saliva and then distributed to various organs and compartments throughout the body. Daily mercury uptake rates from amalgam are estimated to range from 2 to 25 pg Hg/24 h with the worst case individual estimated to have an uptake of 70 pg Hg/24 h. Mercury is a known neurotoxicant and the off-gassing of mercury over time may cause dementia like conditions in some people. 

In a study of the absorption of inorganic mercury by the rat jejunum, Foulkes and Bergman (1993) found that while tissue mercury could not be rigorously separated into membrane-bound and intracellular compartments (as can the heavy metal cadmium), its uptake into the jejunum includes a relatively temperature-insensitive and rapid influx into a pool readily accessible to suitable extracellular chelators. A separate, slower and more temperature-sensitive component, however, leads to the filling of a relatively chelation-resistant compartment. Nonspecific membrane properties, such as surface charge or membrane fluidity, might account for mucosal mercury uptake (Foulkes and Bergman 1993). 

Eide and Wesenberg (1993) studied mercury concentrations in various organs and tissues in rats exposed to mercury vapor for approximately 2 months and proposed that human deciduous teeth may be useful indicators of chronic mercury exposure, as well as indicators of mercury uptake in organs such as the kidneys and the brain. 

Table 5-16. Estimates of Mean Daily Elemental Mercury Uptake from Dental...

Barregard L, Sallsten G, Jarvholm B. 1995. People with high mercury uptake from their own dental amalgam fdlings. Occup Environ Med 52 124-128. 

Magos L. 1967. Mercury-blood interaction and mercury uptake by the brain after vapor exposure. Environ Res 1 323-337. 

Wu, G. 1995. Screening of potential transport systems for methyl mercury uptake in rat erythrocytes at 5 degrees by use of inhibitors and substrates. Pharmacol. Toxicol. 77(3) 169-176. Yasutake, A., and K. Hirayama. 1988. Sex and strain differences of susceptibility to methylmercury toxicity in mice. Toxicology 51(l) 47-55. 

MacCrimmon hr. Wren CD and Gots BL (1983) Mercury uptake by lake trout, Salvelinus namay-cush, relative to age, growth, and diet in Tadenac Lake with comparative data from other PreCam-brian Shield lakes. Can J Fish Aquat Sci 40 114-120. 

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