Mercury distribution in a polluted marine area. Concentrations of methyl mercury in sediments and some marine organisms

Methyl mercury concentrations were measured in various parts of Kastela Bay in the Central Adriatic, which is polluted with inorganic mercury. The values obtained, on a wet weight basis, for sediments were from 2 to 20 micrograms methyl mercury kg-1; for the mussel Mytilus galloprovincialis from 10 to 110 micrograms kg-1; and for various species of fish from 102 to 1448 micrograms kg-1. The methyl mercury content increases by three orders of magnitude going from sediment to fish. The distribution of methyl mercury in relation to the depth of the sediment and the different organs of the mussel is presented. On the basis of the results obtained, it may be concluded that non-migratory species of fish are more suitable for methyl mercury monitoring in the marine environment than are sediment and mussels.     

Field intercomparison studies for evaluation and validation of the AESminiSamplR technique for sampling and analysis of total particulate mercury in the atmosphere

This paper presents new data and reviews literature results from six field intercomparison studies to further evaluate and validate the AESminiSamplR [Anal. Chem., 70 (1998) 2403] technique for sampling and analysis of total particulate mercury in ambient air. The intercomparison studies were carried out at: two remote sites in the Arctic [Alert, Nunavut, Canada (82 degrees 28'N, 62 degrees 18'W) and Ny-Alesund, Svalbard (78 degrees 54'N, 11 degrees 53'E)], one site in Ann Arbor, MI, and three sites in Europe (one in Italy and two in Sweden). The AESminiSamplR was compared with five other methods using different materials, different flow rates, different sample treatment procedures, and/or different detection techniques. Four of the five methods compared were operated by different laboratories. When the compared methods were operated by different laboratories, a difference 相似文献   

The stability of particulate nitrate in the Los Angeles atmosphere

Simultaneous measurements of atmosphere particulate nitrate (NO₃^?) and its gas phase precursor nitric acid (HONO₂) were conducted in Los Angeles during severe smog episodes, and the results were compared to those predicted on the basis of thermodynamic data for the HONO₂ (g) + NH₃ (g) = NH₄ NO₃ (s) equilibrium. Over the wide range of conditions studied (four-hour averaged NO₃^? = 0.5?44.3 μg m^?3 HONO₂ = 1.4?36.0 μg m^?3, T = 10?33°C, humidity = 16?99%, ozone up to 460 ppb) the solid equilibrium model was found to be applicable to only about one-third of the total number of data sets. In this case good agreement was found between measured nitrate values and those expected from comparison of measured and equilibrium nitric acid concentrations. Samples collected at humidities above the deliquescent point of ammonium nitrate at the sampling temperature, for which the solid NH₄ NO₃ equilibrium no longer applies and solution chemistry must be considered, accounted for two-thirds of the data sets. For this subset, good agreement was also found between experimental results and theoretical considerations.     

Gas-phase mercury in the atmosphere over the southern Baltic Sea coast

Results of atmospheric total gaseous mercury (TGM) measurements performed at two Baltic Sea coastal stations, Peninsula Hel (Poland) and Preila (Lithuania), from June 16 to August 11, 1997, are presented. High time-resolution data were obtained by using automated atomic absorption mercury vapor analyzers (Model Gardis-1A). Analysis of TGM concentration data (directional distribution, correlation with meteorological parameters, diurnal variability) detected the Baltic sea, in particular its southern part and Gulf of Gdansk, as the main gaseous mercury source for the region during the summer months. The source seemed to be activated by solar radiation, air temperature, and, probably, wind.     

Total gaseous mercury in the atmosphere of Guiyang,PR China

Four measurement campaigns were carried out to monitor total gaseous mercury (TGM) at one site in the Guiyang City, PR China in the following periods: April 19-30, 2000; February 26-March 14, 2001; June 26-July 20, 2001; and October 9-November 22, 2001, respectively. High temporal resolved data were obtained by using automated mercury analyzers Gardis 1A and Tekran 2537A. TGM data from all measurement periods followed the typical log normal distribution pattern. The geometric mean of TGM from different seasons were 8.56, 7.45, 5.20 and 8.33 ngm(-3) in spring 2000, winter 2001, summer 2001 and autumn 2001, respectively. The overall average TGM covering the sampling periods was 7.39 ngm(-3), which is significantly elevated comparing to global background of approximately 1.5-2.0 ngm(-3). The major anthropogenic atmospheric mercury emission sources differed significantly among seasons, which caused the seasonal variability of TGM level. Distinct daily variability of TGM was observed among seasons. The daytime TGM concentrations were larger than that of nighttime in spring and winter seasons, while in summer and autumn the opposite daily TGM distribution pattern was observed.     

Total mercury and methyl mercury levels in British estuarine and marine sediments

Total mercury and methyl mercury levels in some British estuarine and marine sediments are presented. Results are compared for estuaries of the Rivers Clyde and Mersey. These, together with data from Irish Sea sediments, are discussed in comparison with other literature values. The use of the methyl mercury to total mercury ratio is examined.     

Measurements of mercury in the near-surface layer of the atmosphere of the Russian Arctic

A series of measurements of gaseous elemental mercury concentrations in near-surface air of the Russian Arctic Region were carried out from 1994 to 1997. The measurements were conducted in Murmansk at a stationary site in April-May 1994, on a cruise in Motovsky Bay and Kola Bay during May-June 1996, and along the Russian Northern Sea Route in April-May 1997 on board the nuclear icebreaker 'Soviet Union'. Silver absorption was used for trapping of mercury and the mass of mercury was determined by cold vapour atomic absorption spectrophotometery. Detection limits were approximately 0.3 ng/m(3) (+/- error 46%). Sixty samples were selected and analysed. Sample volumes were 2.2 m(3) ashore, and up to 6.6 m(3) over water. The meteorological conditions, including a wind speed and direction, during the sampling period were typical of the spring-summer period of year, and therefore the concentrations of atmospheric mercury are regarded as representative for this season. The mean concentrations of mercury ranged from 2.2 ng/m(3) for Murmansk city, 1.7 ng/m(3) for Kola Bay, 1.6 ng/m(3) for Motovsky Bay, 1.1 ng/m(3) for the eastern part of the Barents Sea and 0.7 ng/m(3) for the western part of the Kara Sea. The levels of mercury in Murmansk, and over Kola and Motovsky Bays were associated with a primary direction of a near-surface wind from the nearest sources of mercury emission located in the Russian North region. These are the non-ferrous metallurgical plants in Nickel in the case of Motovsky Bay and Murmansk garbage-disposal plant, for sampling points in Murmansk and over Kola Bay. These concentrations of mercury, measured in the spring-summer season, in near-surface air of the Russian North, are more than two-fold lower than the concentrations that are typical of continental background regions in western Russia, and are comparable to the concentrations measured in the Arctic regions of other countries.     

Volcanic emissions of mercury to the atmosphere: global and regional inventories

A comprehensive, time-averaged inventory of subaerial emissions of mercury from volcanoes that were active between 1980 and 2000 is derived based on the Hg/SO(2) ratios of the exhalations. Worldwide flux of mercury from volcanic eruptions is estimated to be 57 t/year while the flux from degassing activities is 37.6 t/year. After correcting for 'unmeasured' SO(2) emissions, the total global flux of Hg to the atmosphere is estimated to be 112 t/year. There are regional differences in average emissions during the 20-year period, with the estimated fluxes being 29 t/year in South and Central America, 27 t/year in Southeast Asia; 24 t/year in North America (including Hawaii), 4.1 t/year in Australia, 3.4 t/year in Japan and northern Asia, 3.1 t/year in Europe and western Asia and 2.3 t/year in Africa.     

Exchange of mercury between atmosphere and vegetation under contaminated conditions

Adsorption and desorption of mercury was studied under laboratory conditions using moss (Sphagnum girgensohnii) and Rye grass (Lolium perenne) at different temperatures. Desorption was also studied in a transplantation experiment. The adsorption was rapid and strong for both plant species at different temperatures (+10 to +60 degrees C) and exposure times (1 h, 1 month) while the evaporation was negligible. Also the leaching of adsorbed mercury was of minor importance. The results emphasise the importance of vegetation in removal of mercury from the atmosphere. They also confirm the suitability of moss and grass for biomonitoring purposes. The high retention of mercury in moss even at +60 degrees C indicates the possibility of using higher temperatures in pretreatment of samples for mercury analyses.     

Temporal trends of cadmium and mercury in Greenland marine biota

Data for cadmium and mercury in Greenland marine biota (blue mussels, polar cod, shorthorn sculpin, glaucous gull and ringed seals) over a period of 20 years has been analysed in order to assess temporal changes. Most of the comparisons were conducted between tissue samples collected in the mid-1980s and mid-1990s. Cadmium data from a few time series obtained at reference sites during monitoring of mining activities were also included. No overall temporal trends in cadmium or mercury concentrations were found within the 20-year period assessed. However, cadmium concentrations in ringed seals tended to increase in the period from late-1970s to the mid-1980s. From the mid-1980s to the mid-1990s cadmium concentrations in ringed seals decreased again, whilst mercury concentrations showed a tendency to increase in the same period. The observed changes may reflect natural fluctuations caused by factors such as a shift in feeding behaviour, rather than changes in anthropogenic exposure.     

An assessment of selenium to mercury in Greenland marine animals

Information on mercury and selenium molar relation in muscle, liver and kidney tissue of Greenland marine animals is presented. In the majority of the samples selenium was present in a molar surplus to mercury. This was most clear in molluscs, crustaceans, fish and seabirds. A 1:1 molar ratio was found in tissues of marine mammals with high mercury concentrations (above approx. 10 nmol/g). This was most clearly demonstrated for liver and kidney tissue of polar bear and for ringed seal with high mercury concentration in the liver. These findings support previous results found in liver tissue of marine mammals, suggesting that methyl mercury is detoxified by a chemical mechanism involving selenium. If the anthropogenic release of mercury to the environment increases in the future due to increasing energy demands, species such as polar bears and seals with high tissue mercury concentrations should be monitored to elucidate whether this protective mechanism can be maintained in target organs.     

Polynuclear aromatic hydrocarbon content of particulate matter suspended in the atmosphere of La Plata, Argentina

Twelve polynuclear aromatic hydrocarbons (PAH) were evaluated by chromatographic procedures using a HPLC-UV detector and a GC-FID detector. The PAH were evaluated in airborne particulate matter collected in La Plata, Argentina, over a period of 2 years (with sampling periods of approximately 4 months). The samples were size fractionated, and the PAH in each fraction determined. The analytical procedure used was as follows: extraction in benzene, concentration at room temperature, clean-up in a silica gel column and, finally, evaluation by chromatographic procedures. The extraction recovery was 76.2 +/- 5.8% for naphthalene and 96.0 +/- 6.2% for chrysene. Clean-up recovery was 87.8 +/- 7.15% for phenanthrene and 98.1 +/- 8.3% for anthracene. The largest PAH load was present in the smallest fractions. The smallest particles were carbonaceous in nature. The concentration peak was associated both with the total mass of airborne particulate matter and the reduction in amounts of coarse particles. The PAH distribution could not be correlated with characteristic physicochemical properties such as water solubility or the octanol-water distribution coefficient. The PAH load was greater in fall and winter than in spring and summer. This could be attributed to the reduction of photochemical processes during the cold seasons.     

Chemical composition of precipitation in tropical marine atmosphere around Indian subcontinent

Precipitation samples collected on board Indian Naval ships over the oceans surrounding peninsular India during MONEX-79 experimental programme of GARP, were assayed for Na, Cl, Mg, Ca, K, Sb, Th, Fe, Zn, Sc, Cr, Co and SO₄ concentrations. The Na/Cl and Mg/Cl distribution is observed to be in the same ratio as that found in sea water. SO₄/Na ratio in rain water also lies very close to sea water ratio of 0.25, unlike that reported for marine aerosols. K and Ca levels indicate an enrichment with reference to Na. Samples collected far away from the coast suggest enrichment of Ca in the sea salt aerosol and that from nearer the coast also gave high Ca excesses indicative of its contribution from the land. Major source of Fe and Sc appears to be of soil origin, while continental derived elements of anthropogenic origin such as Zn and Sb correlate with Rn concentrations and are useful as tracers for air mass movements.     

Estimation of mercury emission from different sources to atmosphere in Chongqing, China

This investigation presents a first assessment of the contribution to the regional mercury budget from anthropogenic and natural sources in Chongqing, an important industrial region in southwest China. The emissions of mercury to atmosphere from anthropogenic sources in the region were estimated through indirect approaches, i.e. using commonly acceptable emission factors method, which based on annual process throughputs or consumption for these sources. The natural mercury emissions were estimated from selected natural sources by the dynamic flux chamber technique. The results indicated that the anthropogenic mercury emissions totaled approximately 8.85 tons (t), more than 50% of this total originated in coal combustion and 23.7% of this total emission in the industrial process (include cement production, metal smelting and chemical industry). The natural emissions represented approximately 17% of total emissions (1.78 t yr(-1)). The total mercury emission to atmosphere in Chongqing in 2001 was 10.63 t.     

Changes in the non-protein thiol pool and production of dissolved gaseous mercury in the marine diatom Thalassiosira weissflogii under mercury exposure

Two detoxification mechanisms working in the marine diatom Thalassiosira weissflogii to cope with mercury toxicity were investigated. Initially, the effect of mercury on the intracellular pool of non-protein thiols was studied in exponentially growing cultures exposed to sub-toxic HgCl₂ concentrations. T. weissflogii cells responded by synthesizing metal-binding peptides, named phytochelatins (PCs), besides increasing the intracellular pool of glutathione and γ-glutamylcysteine (γ-EC). Intracellular Hg and PC concentrations increased with the Hg concentration in the culture medium, exhibiting a distinct dose-response relationship. However, considerations of the PCs-SH:Hg molar ratio suggest that glutathione could also be involved in the intracellular mercury sequestration. The time course of the non-protein thiol pool and Hg intracellular concentration shows that PCs, glutathione and γ-EC represent a rapid cellular response to mercury, although their role in Hg detoxification seems to lose importance at longer incubation times. The occurrence of a process of reduction of Hg(II) to Hg° and subsequent production of dissolved gaseous mercury (DGM) was also investigated at lower Hg concentrations, at which the PC synthesis doesn't seem to be involved. The significant (P < 0.01) correlation between the cellular density in solution and the production of DGM suggests that this diatom is capable of directly producing DGM, both in light and dark conditions. This finding has been confirmed by the absence of DGM production in the culture media containing formaldehyde-killed cells. Finally, the relationship between these two different pathways of Hg detoxification is discussed.     

Do selenium and glutathione inhibit the toxic effects of mercury in marine lamellibranchs?

The effect of selenium (SeO2) and glutathione (GSH) on the bioaccumulation of mercury (HgCl2) and on the activities of lysosomal enzymes in four species of tropical estuarine lamellibranchs is reported. A definite correlation between mercury levels in the external medium and tissue uptake and physiological behaviour--opening and closing of shell valves, response to mechanical stimulus, mucus secretion, and incidence of bleeding--was evident. In the clams exposed to Hg (range 0.1-5.0 mg l-1), bioaccumulation was dependent on the ambient concentration of Hg. The highest bioaccumulation of Hg occurred during the initial 24 h exposure period. Further exposure of up to 7 days did not increase the body burden of Hg. Of the four bivalve species exposed to 0.1 mg Hg l-1, Perna viridis showed the highest levels of Hg (approximately 47 ppm) followed by Anadara granosa, A. rhombea (approximately 25 ppm) and Meretrix casta (approximately 9 ppm). The uptake of Hg by A. granosa was greatly reduced by GSH, whereas Se enhanced it by 50% when administered in combination with Hg. However, the presence of Hg did not influence the uptake of Se. Exposure to combined GSH and Hg resulted in almost complete inhibition of Hg uptake in all four bivalve species. Prior exposure to GSH, however, did not have the same influence on their uptake of Hg. Nevertheless, exposure of clams to GSH following initial exposure to Hg resulted in complete depuration of accumulated Hg. The activities of lysosomal enzymes--arylsulfatase, acid phosphatase, beta-galactosidase and beta-glucuronidase--varied considerably. Treatment with Hg and GSH, separately and in combination, significantly enhanced the levels of beta-galactosidase (P less than 0.05) and beta-glucuronidase (P less than 0.001) in the digestive gland after 96 h exposure. Although Se increased beta-glucuronidase activity (P less than 0.001), it had no effect on beta-galactosidase. On exposure to Hg + Se the activity of both enzymes decreased, except in P. viridis where it increased by 39%. The results show unequivocally that Se does not offer any protection against the toxic effects of mercury in marine lamellibranchs, whereas in many marine vertebrates it does. GSH, a thiol-rich tripeptide, on the other hand, completely nullifies the toxic effects of Hg, both in vivo and in vitro.     

海洋大气环境下TRC加固RC梁受弯时变性能

为预测海洋大气环境下纤维编织网增强混凝土（textile reinforced concrete,TRC）加固RC梁剩余受弯承载力,对TRC加固RC梁受弯时变性能进行研究。基于材料时变性能,建立了TRC加固RC梁受弯承载力时变计算模型,在验证此模型可靠性基础上,通过9根TRC加固RC梁进行参数分析,研究TRC厚度（25、35、45 mm）、钢筋直径（12、14、16 mm）、纤维编织网层数（1~3层）等因素对TRC加固RC梁起锈时间、开裂时间、剩余受弯承载力的影响规律。结果表明：海洋大气环境下TRC加固RC梁受弯承载力随服役时间增加非线性降低,但是其退化速率小于普通RC梁的;增加TRC厚度可以有效延迟起锈时间和减少承载力降低幅度,当TRC厚度由35 mm增加至45 mm时,TRC加固RC梁的起锈时间分别为23.9 a和39.5 a,承载力降低幅度分别为27.48%和15.57%（服役60 a）;钢筋直径对起锈时间无影响,对开裂时间的影响也较小;当钢筋直径分别为12、14、16 mm时,经过60 a服役期后TRC加固RC梁剩余受弯承载力均较接近;增加纤维编织网层数可减小加固梁锈蚀后受弯承载力退化。     

海洋大气区预应力混凝土结构氯离子侵蚀模型分析

结合已有预应力混凝土结构氯离子侵蚀模型,提出应力水平和环境因素(包括温度和湿度等)对在海洋大气区自由氯离子扩散的影响作用。利用连云港港区环境资料和码头预应力混凝土横梁氯离子浓度检测结果,得出服役39年后的预应力混凝土结构内的氯离子浓度分布状况及扩散参数。该地区氯离子浓度分布出现两个波峰,对应氯离子浓度峰值mmax1mm ax2。在第二个波峰后,自由氯离子浓度分布曲线平滑下降,同时验证了该改进模型适用于现场实际工程。     

Bioaccumulation of polybrominated diphenyl ethers and hexabromocyclododecane in the northwest Atlantic marine food web

Seven species of teleost fishes comprising major prey of northwest Atlantic harbor seals were analyzed for polybrominated diphenyl ethers (PBDEs). PBDE concentrations in whole fish samples (n = 87) were compared with those measured previously in harbor seal blubber to evaluate the transfer of PBDEs from prey to predator. Hexabromocyclododecane (HBCD) concentrations were measured in three fish species to provide an initial estimation of HBCD contamination in this ecosystem. HBCD was detected in 87% of the fish samples at concentrations ranging from 2.4 to 38.1 ng/g, lw (overall mean 17.2 ± 10.2 ng/g, lw). ∑PBDE concentrations in fish ranged from 17.9 to 94 ng/g, lw (overall mean 62 ± 34 ng/g, lw). ∑PBDE concentrations in the harbor seals were two orders of magnitude higher than levels in the fish. Biomagnification factors (BMFs) from fish to seals averaged from 17 to 76, indicating that tetra- to hexa-BDEs are highly biomagnified in this marine food web. BDE-47 was the dominant congener in all samples, suggesting exposure to the penta-BDE mixture. The presence of higher brominated congeners including BDE-209 at measurable levels in fish and seal tissue, along with the very high biomagnification of BDE-153, as well as − 155, and − 154, suggests recent exposure to the octa- and deca-BDE formulations in this US coastal marine food web, as well as the additional contribution of BDE-209 debromination in fish to the loading of persistent PBDEs in the seals. This is the first study to report the occurrence of BDE-209 and other higher BDEs in commercially important marine fishes from the northwest Atlantic.