Mercury in Baltic and North Sea waters

Improved determination methods for very low Hg concentrations in sea water using cold vapor AAS with pre-enrichment and purification on gold as well as a new sampling system (‘MERCOS’ PTFE water samplers) have been applied to extensive investigations for reactive and total Hg levels. The first research cruises concentrated on the southwestern Baltic Sea. Concentrations found in the surface water were around 2 ng L^?1 Since 1979, Hg has been regularly monitored in the German Bight of the North Sea as a part of German and international monitoring programs. Two investigations have been performed in the lower course of the river Elbe, from Hamburg to the sea. Results show that the Elbe is the predominant ‘point source’ for Hg in the German Bight. In a large multidisciplinary research project ‘ZISCH’, a closely spaced station network has been sampled twice, in 1986 and 1987, to survey the entire North Sea, i.a. for Hg. Over most of the area, the median of Hg values in the surface water was 0.5 ng L^?1; in a distinct field, however, extremely high levels were found, of more than 200 ng L^?1.     

Spatio-temporal associations between harbour porpoise Phocoena phocoena and specific fisheries in the German Bight

Interactions between cetaceans and fisheries are a major concern of cetacean conservation and fisheries management, as by-catch and resource competition occur as a result. To assess potential interaction between porpoises and fisheries in the German Bight, high-resolution spatial and temporal data were analysed in order to reveal association patterns between cetaceans and fisheries in the German Exclusive Economic Zone (EEZ) of the North Sea. To facilitate interpretation of resulting patterns, additionally, relationships of fish assemblages were analysed. Vessel monitoring system (VMS) data from 2006 and fisheries surveillance data from 2002 to 2006 were acquired to calculate fishing effort, aerial survey data from 2002 to 2006 to evaluate porpoise distribution, and trawl survey data from 2000 to 2007 to assess fish assemblage. Relationships were analysed in terms of seasonal association and overlap. Results showed that porpoise distribution was positively associated with sandeel fisheries in all seasons and with gillnet fisheries in summer. Overlaps for sandeel and gillnet fisheries were high in summer, while negligible in spring and autumn. In spring, high overlap was found for large beam trawlers targeting sole and plaice. In parallel, porpoise distribution was positively linked to fish assemblage components representing sandeel and poor cod in summer and flatfish in spring. Our results suggest that, especially in summer, resource competition between porpoises and industrial sandeel fisheries is likely and the risk of by-catch in gillnets is increased. In spring, interference with sole and plaice fisheries is to be expected.     

Mercury contamination in the Brazilian Amazon. Environmental and occupational aspects

Mercury (Hg) contamination of miners, riparian and Indian populations and fish in the Amazon region, due to gold extracting activities, has been studied. Samples of hair, urine, and blood of Indians and prospectors, and hair from riparian fish-eating population and fishes from Madeira river, respectively, were collected and analyzed by Cold Vapor, Atomic Absorption Spectrometry (CV-AAS) techniques. The results obtained showed that the aquatic food chains in the Amazonian ecosystems are contaminated by methylmercury (MeHg), exposing Indians, prospectors and riverines to thr risk of severe health hazard. The highest levels of contamination, based upon hair analysis, were found in riparian of the Madeira river, followed by Cuniã Lake population, Indians (Fresco river) and prospectors, in that order. Blood analysis showed 59% of the samples from Indians and 33% from prospectors with Hg contents above 10 ng mL^?1. Analysis of urine, on the other hand, showed 44% of Indians with Hg levels below the detection limit (d.l.), and 30% above 20 ng mL^?1, whereas 38% of the prospectors presented Hg concentrations over 20 ng mL^?1, and 20% below the d.l. These results prove that prospectors, who hardly ever eat fish but are badly exposed to inorganic Hg vapor, are ocupationally contaminated, while the rest of the populations under survey are exposed to environmental contamination by Hg, through polluted fish ingestion.     

Size Related Mercury Accumulations in Edible Marine Species from an Area of the Northern Tyrrhenian Sea

Mercury concentrations were studied in important edible species from an area of the northern Tyrrhenian Sea, near Mt. Amiata (Tuscany, Italy), affected by mercury contamination. The studied species were: Nephrops norvegicus (Norway lobster), Parapenaeus longirostris (pink shrimp), Merluccius merluccius(hake) and Eledone cirrhosa (horned octopus). From the results it was found that in N. norvegicus and M. merluccius the accumulation was exponential, while in the other two species it was linear. In females ofN. norvegicus, a sharper increase of Hg concentration beyond three centimetres of carapace length was observed and explained by the reduction in growth rate after sexual maturity. In M. merluccius, the metal concentration increased sharply after 40 cm of length, probably due to a reduction in growth rate over this size. In P. longirostris no statistically significant difference between the slope of the linear regressions of males and that of females was found. In Eledone cirrhosa nomercury accumulation difference between the two sexeswas found. The metal concentration was generally highin all the studied species, with a maximum of 4.2 μg g^-1 of fresh weight in N. norvegicus.     

Mercury content of soils in Western Britain with special reference to contamination from base metal mining

Mercury was determined in 51 soil samples from historic base metal mining areas of England and Wales, together with cadmium, copper, lead, zinc, pH and organic content. Background mercury was calculated as 0.093 ppm whence 51% of the samples were judged to be contaminated. A very strong statistical correlation between mercury and lead and weaker but significant correlations between mercury and copper and zinc were found. Highest levels of mercury (maximum, 1.78 ppm Hg) and other metals occurred in soils derived from the floodplain of a river which was at one time badly polluted by mine waste. In a profile pit near a lead mine in the west of England both mercury and lead were enriched in surface horizons. It is concluded that land contaminated by heavy metals, especially lead, in the historic metal mining areas of England and Wales is also likely to be contaminated by mercury.     

Distribution of Mercury and Other Heavy Metals in Core Sediments of the Northern Adriatic Sea

Seven sediment cores were collected along a transect about20 km off from the mouth of the Po River, in the northernAdriatic Sea (Italy). Cores were characterised by differentdepositional sequences associated with late Pleistocene-Holocene lowstand (LST), transgressive (TST) and highstand (HST) system tracts. Sediment samples were analysed for mercury, copper, nickel, chromium, manganese and iron, aswell as for total organic matter. Metal distributiongenerally showed vertical and spatial variability ascribed tograin size effects with no significant anthropogenicperturbation. Conversely, mercury showed vertical profilescharacterised by surface enrichment, with concentrations inthe upper layer (50–230 ng g^-1) exceeding 3–11 times the background value of 20 ng g^-1 determined in bottomcores. Surface maxima were attributed to anthropogenic mercurydelivered mainly by the Po River.     

Methanogenesis in saltmarsh soils of the North Sea coast of Germany

Temperate saltmarshes are a potential source of atmospheric methane. We have measured the concentration and emission of methane in typical saltmarsh soils (Salic Fluvisols) and humus-rich saltmarsh soils (Thionic Fluvisols) from the German North Sea coast. We also measured the methane production rates of the latter. The methane content of typical saltmarsh soils reached 12.0 μmol 1^?1, although values of 1–4 μmol 1^?1 were usual. The sulphate concentrations of the pore-water were about 10 mm , which means sulphate reduction is not limited and methanogenesis would be suppressed. Methane concentrations were generally largest in summer. Independent of the redox potential and the degree of soil development, methane concentrations were smallest in those soils poorest in humus. Methane emission rates were almost zero. In the humus-rich saltmarsh soils, methane concentrations were roughly a thousand times larger than those in typical saltmarsh soils, reaching values of 23 mmol 1^?1 The sulphate concentrations of the pore-water were often less than 1 mM, indicating limited sulphate reduction. Methane production was up to 80 μg cm^?3 day^?1 and was not inhibited when we added sulphate. Methane emission rates reached up to 190 μg m^?2 day^?1 in summer, with values up to 20 μg m^?2 day^?1 at other times. The two kinds of saltmarsh soil behave quite differently: the typical saltmarsh soils act as a sink for methane; the humus-rich saltmarsh soils are a source.     

Mercury contamination in hair of riverine populations of Apiacás Reserve in the Brazilian Amazon

Total and inorganic Hg in 55 samples of hair from riverines, mainly descended from Munduruku and Apiaká Indians, living along the rivers Teles Pires and Juruena have been determined. The sampled population represents 18% of the inhabitants of the region and they eat fish 6 or 7 days a week. Cold-vapor AAS and alkaline digestion with CdCl2/SnCl2 as reducing agent were employed to estimate total Hg in hair samples. A LDC Analytical, Mod. 1255, Mercury monitor was used for Hg determination. The mean value of total Hg was 34.2µg g-1, with an average of 87.2% of organic Hg Ninety-three per cent of the sampled population present levels of Hg above 10µg g-1, and 18% over 50µg g-1. A relationship between the mean value of Hg and age of the sampled population is presented. All women at child-bearing age present concentrations of Hg above 10µg g-1. Fifty-four per cent of them had levels over 30µg g-1, with a mean of 41.2µg g-1. For the children under ten years of age, 14% show Hg concentration above 50µg g-1. Comparison of these results with those obtained in 10 other Amazon surveys (n=1672) is shown. The results of the concentration of mercury in fish, mainly piscivorous (n=967) from Amazonian and Wetland (pantanal matogrossense) are also presented, with a mean of 726 ng mg-1. There appears to be a relationship between level of Hg in human and their food ingestion habits.     

Mercury contamination of fish in the Ojibwa diet: I. Walleye fillets and skin-on versus skin-off sampling

During the past two years, walleye (Stizostedion vitreum) have been collected and prepared into skin-off fillets and submitted for total mercury analysis. The survey included 105 fish from 18 lakes in 10 counties in northern Wisconsin and the upper peninsula of Michigan. Fourteen lakes yielded walleye fillets with greater than 0.5 ppm mercury, and six lakes yielded samples in excess of 1.0 ppm mercury. Fourteen fish were collected in the spring and prepared as fillets ground up as either skin-on or skin-off samples. The difference in Hg was significant (T₁₄=?3.26,p=0.006) with skin-on fillets, resulting in an approximately 10% decrease in mercury concentrations. Results of this study suggest that by leaving the skin on the sample, mercury concentrations will be reported 10% lower than if the skin is removed. Obviously, consumption advisories based on skin-off samples could provide more protection for Ojibwa people eating the spring harvest of walleye. In the fall, the difference in Hg samples between skin-on versus skin-off, was less and not statistically significant. However, removal of the skin would be expected to underestimate lipophilic organochlorine burdens and may not be appropriate for fish species where PCBs, DDT, and chlordanes are the major concern. Fall data for 67 fish from 26 lakes in 9 counties are also reported.     

Elemental composition of aircraft-sampled aerosols above the southern bight of the North Sea

During the period from September 1988 to October 1989, 23 flights were carried out over the Dutch Continental Shelf of the North Sea and a total of 108 aerosol filter samples were collected. The samples were analyzed for Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Br and Pb using both particle-induced X-ray emission (PIXE) and energy-dispersive X-ray fluorescence (EDXRF). The results from PIXE exhibited better precision and lower detection limits than those from EDXRF. Therefore the further discussion and interpretation was based on the PIXE data only. It was observed that Si, S, V, Mn, Ni, Cu and Pb were enriched with respect to the earth's crust. It was seen that winds from the sector Southeast-South contributed most significantly to the total aerosol concentration. The vertical profiles of several elements indicated that their concentration increases with proximity to the sea. Principal factor analysis on the data matrix containing elemental concentrations, height and wind direction parameters allowed us to identify 6 possible aerosol sources, namely, a composite of CaSO₄ and metallurgical activities, refuse incineration, residual oil combustion, quartz, soil dust and sea-salt aerosol.     

Mercury contamination in the Carson River,Nevada: A preliminary study of the impact of mining wastes

From 1860 to 1890, approximately 7 100 metric tons of metallic mercury (Hg) were released into the Carson River-Lahontan Reservoir watershed as a by-product of Comstock Lode silver (Ag) and gold (Au) ore refining. Present-day Hg contamination is most severe in mine tailings, where total Hg concentrations can exceed several hundred µg/g. Hg-laden tailings were also dumped directly into the Carson River, and were subsequently transported downstream into the Lahontan Reservoir and the Stillwater Wildlife Management Area. The Hg, Ag and Au contents of sediments from the Carson River and the Lahontan Reservoir are well above local background levels, and both Ag and Au contents are positively correlated to Hg. Thus, tailings-derived Hg has been redistributed throughout the entire Carson-Lahontan watershed over the last century. Total Hg concentrations in water samples from the Carson River at seven localities show that: 1) elevated (e.g., >20 ng/L) Hg levels in Carson River waters first appear downstream from accumulations of mill tailings, 2) total Hg concentrations in unfiltered and filtered water from the Carson River increase downstream (i.e. away from the tailings piles), and 3) Hg concentrations in both the Carson River (downstream from the tailings piles) and the Lahontan Reservoir are among the highest known worldwide (100 to 1000 ng/L). Filtered water samples from the Carson-Lahontan system also have high Hg contents (up to 113 ng/L), and suggest that the >0.4 µm particle fraction constitutes over 60% of the total water-borne Hg.     

Mercury in the Aquatic Environment of the Village of Caimito at the Mojana Region,North of Colombia

During May–September 1999, several aquatic environmental samples were collected from the village of Caimito, in the San Jorge River basin area, state of Sucre (Colombia), and analyzed for total mercury (T-Hg). Mean T-Hg concentration in sediments from surrounded marshes was 0.155 ± 0.016 g Hg/g. Low Hg concentrations were found in the phytoplanktivorous fish species Prochilodus magdalenae (0.087 ± 0.01 g Hg/g), while four-fold greater concentrations were found in all the carnivorous species. In average, T-Hg concentrations for fish samples did not exceed the limit consumption level (0.5 g Hg/g). However, risk assessment based on the hazard index suggested that the consumption of 0.1 kg per day of carnivorous fish could increase the risk of mercury poisoning in local population.     

Mercury antagonists: protection of plants against vapor injury by thiamine and other compounds

Mercury vapor-induced abscission ofColeus cuttings was prevented by Thiamine, other organo-S (Se) compounds and selenite, but not by common sugar metabolites, amino acids, non-auxin growth regulators and selenate. Protection was also afforded to other plants including ferns and gymnosperms. Thus the compounds that protect plants against Hg intoxication correspond to the Hg antagonists known in animals including man.     

Mercury contamination of fish in the Ojibwa diet: II. Sensory evoked responses in rats fed walleye

The Ojibwa people of the upper Great Lakes in the United States have a long history of utilizing walleye caught by spear fishing as a major part of their diets. Walleye (Stizostedion vitreum) have been collected and prepared into fillets using traditional methods, submitted for total mercury (Hg) analysis, and fed to laboratory rats in standard neurotoxicity protocols to determine the human health risks associated with consuming these fish. Wisconsin officials recommend avoiding the consumption of fish containing more than 0.5 ppm Hg. Laboratory rodent neurotoxicity bioassays included blending composite fish samples of 0.8, 0.4, and 0.2 ppm total mercury and feeding it to 48 young adult female Long Evans rats for 90 days. Standard behavioral assessments included: clinical neurologic observations, motor activity, and accelerating rotarod. Twelve of the 48 rats were surgically implanted for electrodiagnostic evaluations using sensory evoked potentials with auditory and visual stimuli. Auditory (clicks) responses were relatively stable and unaffected by Hg laden diets. However, visual evoked responses at low flash intensities demonstrated a dose related slowing of brain visual processing activity. Methylmercury contamination is known to affect visual systems, and visual evoked brain potentials are apparently sensitive indicators of dietary Hg.     

Historical sedimentary trends of mercury and other trace elements from two saltmarshes of the Marano and Grado lagoon (northern Adriatic Sea)

Purpose

Previous research conducted in the Marano and Grado lagoon (northern Adriatic Sea) has shown that this environment has been affected by trace metal contamination, especially by mercury (Hg), from both industrial (the chlor-alkali plant) and mining activities (Idrija mine, Slovenia). Sediment cores were collected from two different saltmarshes of this lagoon environment to evaluate the degree of the anthropogenic enrichments and the geochronology of Hg accumulation.

Materials and methods

Core subsampling was performed by cutting 1-cm thick slices at discrete intervals. Mercury determination was done differently from the other parameters in that the two long cores were subsampled at 1-cm intervals to obtain continuous concentration profiles. Samples were completely decomposed, using a mixture of mineral acids in a closed microwave system before being analysed for trace metal content using ICP-OES. Total Hg content in the solid phase was determined by DMA-80. ¹³⁷Cs was measured via gamma spectrometry. ²¹⁰Pb activity was measured via alpha-counting of its daughter, ²¹⁰Po, assuming secular equilibrium between the two isotopes.

Results and discussion

In saltmarsh sediments, Fe, Co, Li, Sc and V show no enrichment at both sites thus suggesting that they are essentially lithogenic elements. Conversely, enrichments are minimal (EF = <2) for As, Cd, Cr, Ni, Pb and Zn and moderate (EF = 2–5) for Cu and Mn and also for Pb and Zn but only in some levels of the sedimentary sequences. An exception is Hg, as expected due to the long-term input proceeding from the historical mining activity which has especially affected the eastern sector of the lagoon.

Conclusions

The core collected from the saltmarsh in the eastern lagoon (Grado) displays a better time resolution during the last century although the Hg background level has not been reached. Conversely, the core collected in the western sector (Marano) has recorded a longer and more complete history of Hg contamination, from the beginning of the peak of Hg extraction activity at the Idrija mine (1850). Both saltmarshes still receive Hg inputs and the sediment accumulation rates in the upper section appear to have increased over the last 10–20 years (from 0.30 to 0.45 cm year^?1 at Marano and from 0.30 to 0.74 cm year^?1 at Grado). Many of these morphological structures suffer erosive processes thus representing a potential source of contaminants associated with sediments, in particular Hg. Conservation and monitoring of saltmarshes should be taken into consideration also from this environmental point of view.

     

Distribution and Accumulation of Mercury Derived from Gold Mining in Marine Environment and Its Impact on Residents of Buyat Bay, North Sulawesi, Indonesia

Buyat Bay (BB), North Sulawesi, Indonesia, was a submarine tailings disposal (STD) site for an industrial gold mine that extracted mercury (Hg)-containing ores from 1996 to 2004. To evaluate the distribution and influence of such a Hg release into the environment, particularly into BB, we quantified the total mercury (THg) and methyl mercury (MeHg) in the surface sediments (beach, river estuary, and marine) and biota of the bay, as well as the scalp hair of residents in the adjacent community. A nearby body of water, Totok Bay, polluted by Hg from artisanal gold mining, and a reference area of the Bajo Coast (Bajo) free of any anthropogenic sources of Hg were also sampled. Both THg and MeHg were detected in all samples measured showed concentrations to be highest at the artisanal mining site, intermediate at the STD site and at their lowest in the control area. THg and MeHg concentrations in marine biota and human hair increased with trophic levels and were significantly higher at the STD site than among the controls. Besides examining the source and distribution of Hg, its accumulation in biota, and its potential impact on humans, we also studied the role of the mine management so as to provide a recommendation for future actions.     

Aluminium contamination and other changes of acid soil solution isolated by means of porcelain suction-cups

Comparison was made between the chemical composition of soil solutions isolated by means of a suction method using porcelain cups and by centrifugation. The soil solutions were isolated from three depths of field plots, where the soil (Typic Haplohumod) had been subjected to various pretreatments.
The cups were made of mullite and corundum as shown by X-ray diffraction analysis. The material when powdered had a cation exchange capacity of about 10meq kg⁻¹. Solutions with similar ionic strengths were obtained by the two methods, but the cups were found to release substantial amounts of Al and to adsorb H, Ca, K, Na and organic matter.
After the cups had been placed in the soil for more than 7 months, calculations suggested that the Al activity in cup solutions was controlled by amorphous gibbsite. This amorphous material was probably produced by proton-induced decomposition of part of the cup material. It is concluded that such cups are improper for isolation of soil solution from acid soils.     

The Impact of Atmospheric Deposition of Non-Acidifying Substances on the Quality of European Forest Soils and the North Sea

In the pilot study ESQUAD the impact of atmospheric deposition of three heavy metals (cadmium, copper and lead) and two persistent organic pollutants (benzo(a)-pyrene and lindane) on the quality of European soils and seawater has been calculated. Calculations have been made of atmospheric transport and deposition using a detailed emissions database for Europe. This enabled deposition maps to be produced to a resolution of approximately 50 km. The distribution of pollutant concentrations in forest soils was calculated for each grid cell using a database of soil property parameters in Europe. For the North Sea, a model was used to map long-term concentrations in water and sediment, which are due to atmospheric deposition and other, non-atmospheric sources. The model calculations allowed detailed comparisons of deposition fluxes and concentrations of the substances studied with critical loads and environmental quality threshold values, including critical loads. Although significant uncertainties were identified, the study gives insight in how threshold exceedance rates in Europe relate to pollutant type, threshold type, environmental compartment and chemophysical phase (adsorbed, dissolved). For all pollutants and for all compartments exceedances were calculated for at least some of the quality thresholds that were chosen.     

Abundance and conservation status of the Yangtze finless porpoise in the Yangtze River, China

The Yangtze finless porpoise (Neophocaena phocaenoides asiaeorientalis) is endemic to the middle and lower reaches of the Yangtze River, China. It is the only freshwater population of porpoises in the world and is currently listed as Endangered by IUCN. In November and December 2006 we used two boats and line transect methods to survey the entire current range of the population, except for two lakes (Poyang and Dongting). Sighting results were similar for both boats, so we pooled all data and analyzed them using two line transect models and a strip transect model. All models produced similar estimates of abundance (1111, 1225 and 1000). We then added independent estimates of the number of porpoises from the two lakes for a total estimate of approximately 1800 porpoises. Our findings indicate that the population continues to decline and that its distribution is becoming more fragmented. Our current estimate in the main river is slightly less than half the estimate from surveys between 1984 and 1991 (which was probably an underestimate). We also found an apparent gap in the distribution of porpoises between Yueyang and Shishou (∼150 km), where sightings had previously been common. Continued threats to Yangtze finless porpoises include bycatch in unregulated and unselective fishing, habitat degradation through dredging, pollution and noise, vessel strikes and water development. Immediate protective measures are urgently needed to ensure the persistence of finless porpoises in the Yangtze River. The survey design and analytical methods developed in this study might be appropriate for surveys of cetaceans in other river systems.     

Mercury exposure in humans through food consumption from the Everglades of Florida

In March 1989, The Florida Department of Health and Rehabilitative Services (HRS) issued a Health Advisory recommending the limited consumption of several fish species caught from the Everglades region of South Florida due to elevated methylmercury (MeHg) levels (average 2–3 ppm in fish meat). There were no reports of clinical MeHg poisoning in humans in Florida, although deaths of Florida panthers were attributed to mercury (Hg). poisoning. This study evaluated the extent of MeHg exposure in persons eating contaminated fish in the Everglades region. Populations at risk were identified including sport fishermen, Everglades Residents and subsistence fishermen. Over 1700 individuals were approached; those who had eaten fish or wildlife from the contaminated areas at least once/month for the prior three months were asked to participate. Three hundred and fifty (350) participants completed a brief questionnaire and provided a hair sample for Hg analysis. In 119 (36%) of individuals with levels above the limits of detection, the mean total Hg in hair was 3.62±3.0μg/g [± standard deviation] with a range of 1.28 – 15.57. The most at risk populations identified with respect to Hg levels were Blacks and men. Although the majority of the participants had fished in the Everglades for many years (>15 years), they reported relatively low intake of fish and had low hair Hg levels compared with similar populations in prior studies of other populations at risk. Although 71% of participants knew of the State Health Advisories concerning ingestion of Hg contaminated fish from the Everglades, this did not change their consumption habits. In addition, Blacks, individuals of lower income and of lower education levels were less likely to know about the Health Advisories. Given recent studies of neurologic effects from relatively low in utero MeHg exposure, the continuation of the Mercury Health Advisories and wildlife monitoring in the Everglades are warranted, especially for women of childbearing age and children. However, public education must be targeted for the populations at risk identified in this study in order to reach these populations more effectively.