Mean Mercury Concentrations Research Articles

Lake acidity and mercury content of fish in Darwin National Reserve, Russia

Darwin National Reserve is a protected natural area on the north-west shore of the Rybinsk Reservoir, 350 km north of Moscow. In June 1989, six lakes in the Reserve and the reservoir were surveyed to assess lake acidity and the mercury content of perch, Perca fluviatilis. Five were seepage lakes with no permanent inlets or outlets and one was a drainage lake with both an inlet and an outlet. The seepage lakes were acidic (mean pH 4·6–4·8) and varied in colour from 20 to 200 Hazen units. The drainage lake and reservoir were alkaline (mean pH 8·0–8·1) and colour spanned a similar range. The mean mercury content of perch dorsal epaxial muscle ranged from 0·5 to 1·1 μg g −1 wet weight in the five acidic lakes and from 0·1 to 0·2 μg g −1 in the alkaline lakes. Fish mercury contentwas negatively correlated with lake pH ( r = −0·93, P = 0·002)if all waters were considered together, and positively correlated with apparent colour ( r = 0·91, P = 0·03) in the seepage lakes.

Mercury in muscle tissue of lesser-spotted dogfish ( Scyliorhinus caniculus L.) from the north-east Irish Sea

This paper reports concentrations of mercury in muscle tissue of lesser-spotted dogfish ( Scyliorhinus caniculus L.) from various locations within Liverpool Bay and the north-east Irish Sea. Concentrations of mercury in fish muscle showed distinct spatial variation, with values from the northern sectors of the Irish Sea significantly lower than those for the southern area, particularly sites in Liverpool Bay and around the mouth of the Mersey Estuary. The data support the hypothesis that there are several major populations of lesser-spotted dogfish within the study area, each of which remains quite distinct during seasonal movements. Consequently, exposure to environmental mercury is reflected in muscle concentrations of mercury. Regressions of mercury concentration against fish length showed significant relationships for the majority of sites, with the slope relating to distance from known sources of mercury contamination. Mean mercury concentrations were higher than in corresponding populations of flatfish from the same areas.

Effects of occupational exposure to mercury vapor on lymphocyte micronuclei.

For 26 chloralkali workers exposed to inorganic mercury and 26 age-matched, occupationally unexposed referents, the frequency and size distribution of micronuclei were determined in peripheral lymphocytes stimulated with either phytohemagglutinin or pokeweed mitogen. For the exposed workers the mean concentrations of mercury in urine, plasma, and erythrocytes were 16 nmol/mmol of creatinine, 48 nmol/l, and 78 nmol/l, respectively, and their mean exposure time was 10 years. Neither the frequency nor the size of micronuclei was significantly different in the two groups; nor were there any correlations to current mercury levels. However, in the exposed group, and with phytohemagglutinin as the mitogen, a statistically significant correlation between previous exposure to mercury (cumulative exposure or number of blood mercury peaks) and the frequency of micronuclei was found. This association was also present when the effects of age and smoking were allowed for, and it may indicate an accumulation of cytogenetic effects in T-lymphocytes.

Mercury contamination in Lake Xolotlán (Managua)

Total mercury was measured in different compartments of Lake Xolotlan's (Managua) ecosystemviz., sediments, water, fish and men. Sediments from 18 localities at 5 depths inside the sediment (5, 10, 15, 20 and 25 cm) contained an average concentration of 0.62 μg Hg.g−1±0.46 at the surface, with extreme values of 0.16 and 1.8 μg.g−1. The highest concentration was observed at 25 cm depth in front of the chlor-alkaly factory (ELPESA). This maximum is associated with the period of highest production of this factory. The highest mercury concentrations in water were also measured close to the discharge of ELPESA,viz. 787 μg.Hg−1 in January and 506 μg.g−1 in April. The mean mercury concentrations measured in the muscles of the most consumed fish were 0.63 μg.g−1±0.22 (extreme values 0.22 and 1.45) inCichlasoma managuense, and 0.07 μg.g−1±0.14 (extreme values 0.004 and 0.63) inC. citrinellum. The concentration in the liver was 0.79 μg.g−1±1.29 inC. managuense and 0.62 μg.g−1±0.44 inC. citrinellum. Human hairs (n=98) of fishermen and their families contained 5.03 μg.g−1±6.2 (extreme values 0.02 and 38.22). The mean concentration measured in men was 6.22 μg.g−1±6.34 (n=58), and in women 3.39 μg.g−1±5.7 (n=40). The average mercury concentration of hairs of workers of ELPESA was 91.24 μg.g−1±156.9 (extreme values 0.46 and 724.53; n=32). We conclude that total mercury levels in the various ecosystem compartments are very high and mercury contamination in the lake may be considered as dangerous for human health.

Spatial patterns in accumulation of mercury by fish from the NE Irish Sea

This paper reports concentrations of mercury in muscle tissue of three marine species of fish; plaice ( Pleuronectes platessa L.), dab ( Limanda limanda L.) and lesser-spotted dogfish ( Scyliorhinus caniculus L.), at various locations within Liverpool Bay and the North East Irish Sea. Mean concentrations of mercury in fish muscle within any one sampling area followed the order: lesser spotted dogfish⪢dab>plaice. Concentrations in lesser spotted dogfish were 5–10× higher than in flatfish from the same site. Regressions of mercury concentration against fish length showed significant relationships for the majority of species-site combinations, with the slope of the regression relating to distance from the Mersey Estuary.

Effect of three primary treatment sewage outfalls on metal concentrations in the fish Cheilodactylus fuscus collected along the coast of Sydney, Australia

Samples of muscle tissue from red morwong Cheilodactylus fuscus (Pisces: Cheilodactylidae) collected at 24 sites along the coast near Sydney Australia were analysed for total concentrations of mercury, arsenic, selenium, zinc, cadmium, lead, nickel and copper. The sites were equally spaced around each of the three major ocean disposal sewage treatment plants (STP) in Sydney located at North Head, Bondi and Malabar. The mean concentrations of mercury, arsenic and zinc were highest in fish caught off Sydney Harbour and Malabar STP. The proportion of fish in which cadmium was detected was also highest off Sydney Harbour and south of Malabar STP. Average selenium concentrations decreased from north to south with peak concentrations at each STP. Many individual values of copper, lead, and nickel were near or below the detection limits and no notable trends were observed for these metals. Mercury was the only metal whose overall mean concentration exceeded the National Health and Medical Research Council (NHMRC) Maximum Residue Limit (MRL).

Relation between Mercury Concentrations in Walleye (Stizostedion vitreum vitreum) and Northern Pike (Esox lucius) in Ontario Lakes and Influence of Environmental Factors

We examined the relation between mercury levels in walleye (Stizostedion vitreum vitreum) and northern pike (Esox lucius) in Ontario lakes. Walleye and northern pike occurred together in 79 of the 346 study lakes. The length-standardized mercury concentrations in coexisting walleye and northern pike in the 79 lakes were highly correlated (r2 = 0.60). The mean mercury concentrations in walleye and northern pike of standardized length from these lakes were 0.65 and 0.52 μg/g, respectively. Lacustrine characteristics associated with lake dystrophy (dissolved organic carbon and iron) were positively correlated with mercury levels in both species. Variables associated with acidity (pH and alkalinity) and hardness (calcium, conductivity, and magnesium) were negatively correlated with mercury concentrations in northern pike but not walleye.

Effects of mercury, selenium, and organochlorine contaminants on reproduction of Forster's terns and black skimmers nesting in a contaminated Texas Bay

Mean mercury (0.40 micrograms/g), and geometric mean DDE (1.6 micrograms/g) and polychlorinated biphenyl (PCB) (2.3 micrograms/g) concentrations in Forster's tern (Sterna forsteri) eggs from Lavaca Bay were higher than those in tern eggs from a reference area in San Antonio Bay, but residues were not correlated with hatching success. Nest success was similar between bays. Selenium levels in Lavaca Bay tern eggs (0.71 micrograms/g) were also comparable to those in eggs from the reference area (0.68 micrograms/g). Clutch size (3.1 to 3.4) of Lavaca Bay black skimmers (Rynchops niger) was no different than that (3.4) at a reference colony near Laguna Vista. Nest success was similar among three Lavaca Bay colonies, but success was lower at one Lavaca Bay colony (40%) than at Laguna Vista (65%). Mean mercury (0.46 micrograms/g) and selenium (0.75 micrograms/g) concentrations in skimmer eggs from Lavaca Bay were higher than those (0.19, 0.33 micrograms/g) from Laguna Vista; however, concentrations of neither contaminant were related to hatching success. DDE concentrations in Lavaca Bay skimmer eggs (3.4 micrograms/g) were similar to those from Laguna Vista (3.2 micrograms/g) and DDE was negatively correlated with hatching success. PCBs were higher in eggs from Lavaca Bay (1.3 micrograms/g) than Laguna Vista (0.8 micrograms/g). Organochlorine and metal contaminants in most eggs were below embryotoxic levels. Eggshell thinning in Forster's terns (7%) and black skimmers (5%) was below that associated with lowered reproduction. DDE and PCBs were detected in 9 Caspian tern (S. caspia) eggs; maximum concentrations were 4.7 and 5.4 micrograms/g. Caspian tern and least tern (S. albifrons) eggs contained low (less than or equal to 0.9 micrograms/g) concentrations of mercury and selenium.

Using seabirds to monitor mercury in marine environments: The validity of conversion ratios for tissue comparisons

The ‘7:3:1 rule’ for converting mercury concentrations between feather, liver and muscle tissues was evaluated by measuring total and methyl mercury levels in liver, muscle and body feathers of a range of seabird species. Mean mercury concentrations were used to calculate feather: liver (both total and methyl) and feather: muscle ratios, the results obtained being compared with the predicted values of 2.3 and 7.0. Feather: liver ratios were found to approximate to 2.3 when liver methyl mercury concentrations were considered, but elevated inorganic mercury concentrations in the livers of some species resulted in greatly reduced feather: liver ratios for total mercury. Feather: muscle ratios varied from 3.8 to 15.3. Factors likely to affect the value of feather: liver and feather: muscle mercury concentration ratios, such as the predominant form of mercury present in the liver tissue, sampling date relative to the stage of the moult sequence and types of feather used for analysis, are discussed and we emphasize that the 7:3:1 conversion ratio used by a number of authors should be treated with caution.

Mercury content of Antarctic surface snow: Initial results

Surface snow from Windless Bight, Ross Ice Shelf, Antarctica has been analyzed for its Hg content. Ultra-clean techniques were used for field extraction of Hg onto gold-coated sand, followed by photo-acoustic analysis within 24 h. Results yield a mean mercury content of 2.7 pg g −1. However, the true level is probably < 1 pg g −1, as measured amounts decreased throughout the period of sampling, indicating that the first samples were probably contaminated and that later results are likely to be more accurate. Our results suggest that previous studies of Antarctic snow have suffered from major contamination problems. Refinement of techniques should allow historical trends in atmospheric Hg levels to be identified from a snow pit at a suitable remote site.

Dissolved mercury behaviour in the Saint Lawrence estuary

Dissolved mercury concentrations have been measured in the waters of the St Lawrence estuary. The typical concentration of the riverine end-member is 12·0±3·0 p m; the oceanic end-member samples exhibit a mean mercury concentration of 2·4 p m. The graphical pattern of the relationship between mercury concentration and salinity shows a departure from a dilution line. We suggest that a removal of mercury from the dissolved phase during the estuarine mixing is responsible for this observation. Based on the results, the actual input of dissolved mercury from the St Lawrence River to the Gulf is evaluated to be approximately 0·52 T a −1.

Mercury concentrations in edible tissues of Elasmobranchs, teleosts, crustaceans and molluscs from south-eastern Australian waters

Mean concentrations of total mercury in the axial muscle tissues from 4 species of elasmobranchs (1.33-3.15 �g g-1) and 14 species of teleosts (0.14-0.73�g g-1) from waters deeper than 75 m were generally higher than the mean concentrations in 23 different species of elasmobranchs (0.13- 1.70 �g g-1) and 30 different species of teleosts (0.01-0.29�g g-1) from shallower waters outside Port Phillip Bay. In 5 of the 11 species of teleosts from Port Phillip Bay, which is shallow, almost landlocked and drains a largely urbanized catchment, mean concentrations were 0.39-0.63�g g-; in the remaining 6 species, they were 0.04-0.27�g g-1. Differences in the diets and the longevity of the species are discussed as possible explanations of the variations in the mercury concentrations. Most of the results were similar to those from other studies undertaken on the same species collected from waters off Tasmania and New South Wales, but tended to be higher than the results for the same species collected from New Zealand waters. Mean concentrations of mercury in various soft tissues from eight species of molluscs were 0.01-0.11�g g-1 and in abdominal and thoracic muscle tissues from three species of crustaceans were 0.03-0.13�g g-1..

Organochlorines and Mercury in Eggs of Coastal Terns and Herons in California, USA

-In San Francisco Bay, California, USA, concentrations of DDE and mercury in eggs differed among Caspian Tern, Forster's Tern, Black-crowned Night-Heron, and Snowy Egret in 1982. Geometric mean DDE concentrations were higher (P <0.05) in Caspian Tern eggs (6.93 ppm, wet weight) than in eggs of other species (1.92 2.84 ppm). Mean mercury concentrations were significantly greater in Caspian Tern (1.25 ppm) and Forster's Tern (0.90 ppm) eggs than in night-herons (0.41 ppm), but night-heron eggs contained higher concentrations of mercury than did the eggs of Snowy Egrets (0.21 ppm). There were no significant differences among species for mean concentrations of trans-nonachlor or PCBs; other organochlorines occurred in fewer than half of the samples, so means were not compared. Caspian Tern eggs from San Francisco Bay had higher PCB concentrations (4.85 ppm) than did eggs of this species from San Diego Bay, California (1.70 ppm) or Elkhorn Slough, California (1.83 ppm), but we detected no significant differences in mean concentrations of other organochlorines. DDE concentrations in 5 of 47 (10.6%) nightheron eggs from San Francisco Bay exceeded 8 ppm, a level associated with impaired reproduction in this species. DDE concentrations were negatively correlated with eggshell thickness in night-herons and egrets.

Mercury in neonatal scalp hair

Total mercury levels (TML) were determined in 141 samples of maternal head and pubic hair and neonatal scalp hair. The mean mercury contents of maternal head and pubic hair were 1.88 and 1.10 mg kg −1, respectively, while the mean TML of neonatal hair was 0.11 mg kg −1. A statistically significant correlation was found between TMLs in neonatal and maternal hair. Significant inverse correlation was observed between the mercury concentration in the hair of a newborn and its birth weight. Reported findings provide evidence that the neonatal scalp hair mercury level may be a useful indicator of intrauterine exposure to mercury.

Mercury and selenium concentrations in sharks from northern Australian waters

Total mercury, alkyl mercury and selenium concentrations in the muscle tissue of 15 carcharhinid (Carcharhinus sp., C. limbatus, C. sorrah, C. fitzroyensis, C. amblyrhynchoides, C. melanopterus, C. cautus, C. amboinensis, C. macloti, C. dussumieri, C. brevipinna, Rhizoprionodon acutus, R. taylori, Galeocerdo cuvieri, Negaprion acutidens) and three hammerhead (Sphyrna lewini, S. mokarran and S. blochii) sharks from northern Australian waters are reported. Total mercury concentrations ranged widely with maximum individual concentrations exceeding 1.5 mg kg-1 wet weight in 11 species and values of over 3.0 mg kg-1 in Carcharhinus sp., C. amblyrhynchoides, C. melanopterus, C. amboinensis and S. mokarran. Much of the variability in total mercury concentration was attributable to differences in length. Total mercury was adequately correlated with fork length by the power function relationship. There were signficiant differences in these relationships for males and females of six species: males had higher concentrations of mercury than females of the same size. Weighted mean mercury concentrations were calculated using species and size composition data from commercial feasibility fishing trials. Weighted means for species other than C. sorrah, C. macloti, C. brevipinna and C. dussumieri were greater than 0.5 mg kg-1 and the value for the combined catch of all species was 1.22 mg kg-1. Alkyl mercury comprised over 80% of the total mercury content in the muscle tissue. Maximum individual selenium concentrations were greater than 1.0 mg kg-1 in nine species and the maximum concentration recorded was 3.4 mg kg-1 for C. dussumieri. There were no obvious or consistent relationships between selenium concentration and fork length or between selenium and mercury concentrations.

Mercury in human hair: a study of residents in Madrid, Spain.

The mercury content in hair of the population in Madrid (chosen randomly) was in the range of 1.29-129.47 micrograms/g (geometric mean = 7.96 micrograms/g). The mean mercury content in hair of occupationally exposed workers was 12.70 micrograms/g (range = 2.91-65.43 micrograms/g). The highest means, which were found in two families (i.e., 67.89 micrograms/g and 92.47 micrograms/g, Families A and B, respectively), probably resulted from external factors. No statistically significant variations in the mercury concentrations in hair were found with regard to sex, age, or dental fillings. A significant correlation (r = 0.785; P less than .01) was found between the concentration of the total mercury found in nursing infants and their mothers.

Mercury concentrations of the axial muscle tissues of some marine fishes of the continental shelf adjacent to Tasmania

The mercury concentrations of 35 commercial and potentially commercial fish species from Tasmanian waters were determined. Four species had mean total mercury concentrations above 0.5 mg kg-1 wet weight and in all four there were individuals with concentrations above 1.5 mg kg-1 wet weight. Two species of shark, Parascyllium ferrugineum and Cephaloscyllium laticeps (with sample sizes of 4 and 1, respectively), had total mercury concentrations above the limit of a mean of 1.0 mg kg-1 wet weight set by the Tasmanian Public Health regulations. Concentrations in the species were compared with published data. Organic mercury concentrations in different species ranged from 40 to 96% of the total mercury concentrations. In fewer than half the species were total mercury concentration and total length or weight significantly correlated, indicating that neither total length nor weight could be used as a universal management tool to control human mercury intake from fish consumption.

Total mercury concentrations in human hair from 13 countries in relation to fish consumption and location

Five hundred and fifty nine samples of human head hair from 32 locations in 13 countries were analysed for mercury. Tests of different techniques for cleaning and storing samples showed that at ambient air mecury concentrations contamination of samples is undetectable. Arithmetic mean mercury concentrations for people who ate fish 1–4 times each month were: Australia, 2.5 ppm; Canada, 1.2 ppm; China, 0.9 ppm; West Germany, 0.5 ppm; Hong Kong, 3.0 ppm; Italy, 1.5 ppm; Japan, 3.9 ppm; Monaco, 1.7 ppm; New Zealand, 1.3 ppm; Papua New Guinea, 1.8 ppm; South Africa, 1.9 ppm; U.K., 1.6 ppm and USA, 2.4 ppm. The differences are believed to be due to diet and environment. Mean hair mercury concentrations were significantly different for the group that ate fish once or less a mont (1.4 ppm) once a fortnight (1.9 ppm) once a week (2.5 ppm) and once or more a day (11.6 ppm). Simplified models of mercury pathways in the environment and man are presented. Hair mercury concentrations measured here and those reported in the literature suggested that the weighted mean hair mercury concentration of people living in both northern and southern hemispheres at latitudes 40° had hair mercury concentrations which were significantly lower than at other latitudes, even in industrialized countries. It is suggested that lower soil temperatures could retard mercury volatilization and inhibits its movement into pathways which get back to man.

Mink and otter as indicators of mercury in Manitoba waters

Tissues of mink (Mustela vison) and river otter (Lutra canadensis) from several Manitoba drainage basins were analyzed for total mercury. Results were compared among drainage basins and with published data. With some variations, mercury concentrations followed similar patterns in both species. Levels were highest in the samples from Winnipeg River and Burntwood River; these were significantly (p &lt; 0.05) higher than in samples from Duck Mountain that were comparable to background levels reported in the literature. Mean concentrations of mercury in samples from all areas were well below the reported acutely toxic levels. Mink and otter accumulated about 10 times more mercury than did predatory fishes from the same drinage areas. Monitoring of environmental mercury levels through mink and otter is a viable method, and these furbearers can serve as sensitive indicators of mercury even at very low levels of environmental contamination.

Contributions from coal and industrial materials to mercury in air, rainwater and snow

The mean mercury level in some British coals was 0.97 (range 0.13–2.28) ppm. Mean values of 0.01–3.3 ppm have been reported for coals elsewhere in the world with maxima up to 300 ppm. Release of mercury from coal used all over the world lies in the range 0.14−2.72 × 10 9 g yr −1 depending on mean mercury concentrations in the coal and amount of mercury trapped by precipitators before release from chimney stacks. The amount released from cement manufacture is estimated to be 2.5 × 10 8 g yr −1. Iron ores had 0.09 (range 0.02–0.28) ppm, minerals 0.31 (range 0.01–0.73) ppm, the ingredients used in cement contained between 0.03–0.46 ppm, rainwater 16.7 (range 6–30) ng 1 −1, snow 13 (range 4–21) ng 1 −1 and air levels were 18.9 (range 1–66) ng m −3. Proposals to burn more coal for energy are discussed in relation to (i) the mercury released from it, (ii) the mercury already present in the environment which is constantly being revaporized and redistributed, and (iii) the mercury washed out of the atmosphere into permanent sinks such as marine sediments.