Trophodynamics of mercury and other trace elements in a pelagic food chain from the Baltic Sea

Mercury (Hg) and 13 other trace elements (Al, Ti, V, Cr, Fe, Mn, Co, Ni, Cu, Zn, As, Cd, and Pb) were measured in phytoplankton, zooplankton, mysis and herring in order to examine the trophodynamics in a well-studied pelagic food chain in the Baltic Sea. The fractionation of nitrogen isotopes (δ¹⁵N) was used to evaluate food web structure and to estimate the extent of trophic biomagnification of the various trace elements. Trophic magnification factors (TMFs) for each trace element were determined from the slope of the regression between trace element concentrations and δ¹⁵N. Calculated TMFs showed fundamental differences in the trophodynamics of the trace elements in the pelagic food chain studied. Concentrations of Al, Fe, Ni, Zn, Pb and Cd showed statistically significant decreases (TMF < 1) with increasing trophic levels and thus these trace elements tropically dilute or biodilute in this Baltic food chain. Cu, As, Cr, Mn, V, Ti and Co showed no significant relationships with trophic levels. Hg was unique among the trace elements studied in demonstrating a statistically significant increase (TMF > 1) in concentration with trophic level i.e. Hg biomagnifies in this Baltic food chain. The estimated TMF for Hg in this food chain was comparable to TMFs observed elsewhere for diverse food chains and locations.     

Atmospheric emissions estimation of Hg, As, and Se from coal-fired power plants in China, 2007

Over half of coal in China is burned directly by power plants, becoming an important source of hazardous trace element emissions, such as mercury (Hg), arsenic (As), and selenium (Se), etc. Based on coal consumption by each power plant, emission factors classified by different boiler patterns and air pollution control devices configuration, atmospheric emissions of Hg, As, and Se from coal-fired power plants in China are evaluated. The national total emissions of Hg, As, and Se from coal-fired power plants in 2007 are calculated at 132 t, 550 t, and 787 t, respectively. Furthermore, according to the percentage of coal consumed by units equipped with different types of PM devices and FGD systems, speciation of mercury is estimated as follows: 80.48 t of Hg, 49.98 t of Hg²⁺, and 1.89 t of Hg^P, representing 60.81%, 37.76%, and 1.43% of the totals, respectively. The emissions of Hg, As, and Se in China's eastern and central provinces are much higher than those in the west, except for provinces involved in the program of electricity transmission from west to east China, such as Sichuan, Guizhou, Yunnan, Shaanxi, etc.     

Ambient air total gaseous mercury concentrations in the vicinity of coal-fired power plants in Alberta, Canada

The Lake Wabamun area, in Alberta, is unique within Canada as there are four coal-fired power plants within a 500 km² area. Continuous monitoring of ambient total gaseous mercury (TGM) concentrations in the Lake Wabamun area was undertaken at two sites, Genesee and Meadows. The data were analyzed in order to characterise the effect of the coal-fired power plants on the regional TGM. Mean concentrations of 1.57 ng/m³ for Genesee and 1.50 ng/m³ for Meadows were comparable to other Canadian sites. Maximum concentrations of 9.50 ng/m³ and 4.43 ng/m³ were comparable to maxima recorded at Canadian sites influenced by anthropogenic sources. The Genesee site was directly affected by the coal-fired power plants with the occurrence of northwest winds, and this was evident by episodes of elevated TGM, NO_x and SO₂ concentrations. NO_x/TGM and SO₂/TGM ratios of 21.71 and 19.98 µg/ng, respectively, were characteristic of the episodic events from the northwest wind direction. AERMOD modeling predicted that coal-fired power plant TGM emissions under normal operating conditions can influence hourly ground-level concentrations by 0.46-1.19 ng/m³_. The effect of changes in coal-fired power plant electricity production on the ambient TGM concentrations was also investigated, and was useful in describing some of the episodes.     

Growth responses of selected freshwater algae to trace elements and scrubber ash slurry generated by coal-fired power plants

In laboratory studies, the freshwater algae Ankistrodesmus falcatus, Scenedesmus obliquus, Selenastrum capricornutum, and Microcoleus vaginatus were exposed to potential pollutants from coal-fired power plants, and their growth responses were evaluated. Using a modification of the EPA Algal Assay Procedure Bottle Test, algae were incubated in media containing As(V) as Na₂HAsO₄ · 7H₂O, Cd(II) as CdSO₄, Hg(II) as HgSO₄, Se(VI) as Na₂SeO₄, in solution, and scrubber ash slurry generated at a western U.S. coal-fired power plant complex. First significant inhibition levels as well as algistatic-algicidal levels are reported. The median effective concentration (EC50) values for the potential pollutants ranged from 0.048–30.761 mg l⁻¹ (0.00064–0.41058 M) As(V), 0.005–0.019 mg l⁻¹ (0.00004–0.00017 M) Cd(II), 0.033–0.253 mg l⁻¹ (0.00016–0.00126 M) Hg(II), 0.033–8.511 mg l⁻¹ (0.00042–0.10779 M) Se(VI), and 3.048–15.417% scrubber ash slurry extract (SASE).     

Export of mercury downstream from reservoirs

Environmental effects monitoring at the La Grande hydroelectric complex (Québec, Canada) revealed important increases in mercury levels in fish caught downstream from reservoirs. A study was carried out in 1997 immediately below the Caniapiscau Reservoir to identify by which components mercury is transported downstream from reservoirs and to assess the amount of mercury being exported. Stomach contents of lake whitefish (Coregonus clupeaformis) captured immediately below the Caniapiscau Reservoir were examined to determine which components transfer mercury from lower trophic levels to fish. The analyses of water samples and drifting organisms collected below the reservoir indicate that the dissolved fraction (< 0.45 microm) and the suspended particulate matter (0.45-50 microm) are the major components by which methylmercury is transferred downstream of reservoirs, accounting for 64 and 33%, respectively, of the total amounts exported. Drifting organisms such as plant debris, benthic invertebrates, fish, phytoplankton and zooplankton are much less important pathways for mercury export because of their very low biomass per water volume coming out of the generating station, as opposed to the high biomass of suspended particulate matter. However, zooplankton is the major component by which methylmercury is directly transferred to non-piscivorous fish downstream.     

Distribution of trace elements in organs of six species of cetaceans from the Ligurian Sea (Mediterranean), and the relationship with stable carbon and nitrogen ratios

Mercury (total and organic), cadmium, lead, copper, iron, manganese, selenium and zinc concentrations were measured in different organs of 6 different cetacean species stranded in an area of extraordinary ecological interest (Cetaceans' Sanctuary of the Mediterranean Sea) along the coast of the Ligurian Sea (North-West Mediterranean). Stable-isotopes ratios of carbon ((13)C/(12)C) and nitrogen ((15)N/(14)N) were also measured in the muscle. A significant relationship exists between (15)N/(14)N, mercury concentration and the trophic level. The distribution of essential and non-essential trace elements was studied on several organs, and a significant relationship between selenium and mercury, with a molar ratio close to 1, was found in the cetaceans' kidney, liver and spleen, regardless of their species. High selenium concentrations are generally associated with a low organic to total mercury ratio. While narrow ranges of concentrations were observed for essential elements in most organs, mercury and selenium concentrations are characterised by a wide range of variation. Bio-accumulation and bio-amplification processes in cetaceans can be better understood by comparing trace element concentrations with the stable-isotopes data.     

The concentrations and particle size relationships of selected trace elements in fly ashes from U.K. coal-fired power plants and a refuse incinerator

Fly ash samples from 11 coal-fired power plants and a refuse incinerator in the U.K. were analyzed for total arsenic, cadmium, lead and selenium. Enrichment factor (EF) values calculated with respect to crustal abundance (EF_crust) were highest for cadmium and lead in refuse fly ash, with EFs of 2500 and 740, respectively. Enrichment factors for selenium were similar in both fly ash types; only arsenic was more enriched in coal fly ash compared with refuse fly ash. Despite the high EF_crust values of certain elements in the two fly ash types, the same elements showed EF values of about unity when expressed with respect to the starting material. Both materials displayed an inverse relationship between particle size and extent of enrichment for all the elements studied, but the degree of enrichment on the finest particles was lower than reported for coal fly ash by other workers. The EF_crust values estimated for arsenic, lead and selenium in suspended particulates from a refuse incinerator were similar to those calculated for the urban atmospheric aerosol, whereas cadmium was 10 times more enriched in the suspended particulates.Scanning electron microscopy revealed a marked contrast in the morphological features of the two fly ash types. Coal fly ash was almost entirely composed of cenospheres of < 20 μm diameter, whereas refuse fly ash consisted mostly of amorphous particles of < 50 μm diameter; some cenospheres were, however, noted in the refuse fly ash.     

常规燃煤电厂超低排放技术路线分析

通过标准对照、超低排放技术应用研究,结合某电厂300 MW机组环保提效调控实际,按照充分挖潜环保设施现有潜力后再对瓶颈环节实施充分利旧改造的思路,对常规燃煤电厂达到燃气电厂排放标准的技术路线进行了探讨分析,为燃煤电厂实现超低排放提供参考。     

Comparison of Models used to Estimate Parameters of Organic Emissions from Materials Tested in Small Environmental Chambers

Two models, one physical and the other empirical, have been applied to the characterization of emission data of thin film products tested in small environmental chambers and have been compared in temts of emission results and m e of use. The physical model, being based on equations with coefficients bearing a physical meaning, is, in principle, more informative than the empirical one. However, it is uncertain whether it always gives accurate and unambiguous results. Moreover, in orakr to be exploited in a reasonable amount of time, it requires the use of non-linear regression routines, e.g. those fom SAS Institute Inc., implemented on mainframes and, even then, it is often quite diffiult to handle. The empirical model does not rely explicitly on physical effects. Although by definition it can only describe but not interpret the experimental data, it does estimate parameters describing the emission with an accuracy comparable to that of the physical model. It is easier to handle than the latter as it can employ non-linear regression routines such as those used on personal computers.     

Release of toxic metals and metalloids from Los Rueldos mercury mine (Asturias, Spain)

The abandoned mercury mining works of "Los Rueldos" are located 20 km from Oviedo, along the northwestern border of the Asturian Central Coal Basin, in an area with intense tectonization. Hg mainly appears as cinnabar, but occasionally metacinnabar and native Hg are present; associated with Hg ore appear As-rich minerals (arsenopyrite, As-rich pyrite, realgar and scorodite). In the spoil heap, Hg content ranges from 14 to 2224 mg kg(-1), and As from 4746 to 62,196 mg kg(-1). Mine drainage and spoil heap leachates show acidic conditions (pH: 2.43-2.50), 2900-4600 mg l(-1) sulphate, 1.4-9.2 mg l(-1) As, 0.03-0.48 mg l(-1) Pb, and 3.6-14 microg l(-1) Hg. According to the analytical data and characteristics of the site, the application of corrective measurements to avoid the dispersion of contaminants in the environment must be considered.     

Influence of operating conditions on the ammonia electro-oxidation rate in wastewaters from power plants (ELONITA technique)

Power plants, like many other industries, are confronted with the need to reduce the nitrogen content of their wastewaters. Indirect electro-oxidation, through hypochlorite formation, is a possible answer to an ammonia-nitrogen problem, through converting it into gaseous nitrogen. Several parameters affect the ammonia oxidation rate: current density, chloride concentration and the presence of oxygen-containing anions, mainly SO(4)(2-), CO(3)(2-) and PO(4)(3-). pH values between 5.5 and 10 have been found to have no effect on the ammonia oxidation rate. However, at higher pH values (above 11), the oxidation slows down and chlorate ions appear. A model can be fitted from the experiments to predict the ammonia oxidation rate based on four main parameters: pH, current density, sulfate concentration and chloride concentration. The average difference between the predicted oxidation rates and the experimental measures is only 6.5%. This model confirms that the optimal operating conditions are a high chloride concentration (7 gl(-1)), no sulfate and a high current density (1200 Am(-2)).     

Sensory Characterization of Emissions from Materials

Abstract The exposure-response relationship between the concentration of air pollutants and perceived air quality was studied for eight materials often found indoors and for a mixture of three of the materials. Samples of the materials were placed in a ventilated test chamber. The exhaust air from the test chamber was diluted with different rates of unpolluted air to obtain five different concentrations of polluted air. A sensory panel assessed the perceived quality of the five concentrations of polluted air. The exposure-response relationship differed between the materials and also from the corresponding relationship for human bioeffluents. The exposure-response relationships can be described by straight lines in a log-probit plot and be defined by two constants characteristic for each material. Determination of the two constants characterizing each material requires sensory assessments at least at two pollution concentrations. The sensory pollution load for a material may change with the pollution concentration in the air. The use of a simple measurement method based on a dilution system connected to a ventilated small-scale test chamber is proposed to characterize the emissions from materials in sensory and chemical terms.     

Mercury emissions from coal-fired power stations: The current state of the art in the Netherlands

About 30% of the electricity produced in the Netherlands is generated by coal, all of which is imported. At the same time, the co-combustion of biomass is becoming increasingly important. For the last 25 years, the fate of the elements/trace elements in general and of mercury in particular has been studied in great detail. It appears that on average 50% of the mercury is removed in the ESP (particulate control) and 50% of the remainder is removed in the flue gas desulphurization (FGD), resulting in a total mercury removal of 75%. If a high dust selective catalytic reduction (SCR for NO(x) reduction) is present, the total removal can be up to 90%. The results indicate that on average the removal of mercury during the co-combustion of biomass is similar to that found for full coal-firing. The conclusion is that a modern coal-fired power station with the above-mentioned flue gas cleaning equipment also removes mercury up to 90%. These cleaning devices are being installed to reduce the emission of particulates, sulphur dioxide and nitrogen oxides. This means that mercury abatement can be increased while meeting the EU regulation for SO(2) and NO(x). The application of Best Available Technique (BAT) for coal-fired installations by 1-1-2008 will lead to a further increase in the construction and operation of FGD and DeNO(x) installations.     

Health and environmental implications of trace metals released from coal-fired power plants: an assessment study of the situation in the European Community

In the European Community (EC) the anticipated increased use of coal for power production will lead to an increase in the release of trace metals into the environment. This release seems unlikely to cause toxicological effects through the food chain, but there may be a possibility of a direct impact on man through inhalation. There are, however, many areas of uncertainty which need to be clarified by further research before a definitive assessment can be made.     

Speciation of selected trace elements in three Ethiopian Rift Valley Lakes (Koka, Ziway, and Awassa) and their major inflows

The Ethiopian Rift Valley Lakes (ERVLs) are water resources which have considerable environmental, economic and cultural importance. However, there is an increasing concern that increasing human activities around these lakes and their main inflows can result in increased contamination of these water bodies. Information on total concentrations of some trace elements is available for these lakes and their inflows; however, data on the trace element speciation is lacking. Therefore, the objective of this study was to determine the low molecular mass (LMM) trace element species and also, evaluate the influence of flooding episodes on the LMM trace element fractions. At-site size and charge fractionation system was used for sampling of water from the lakes Koka, Ziway and Awassa and their main inflows during the dry and wet seasons. The results showed that chromium (Cr), manganese (Mn), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), and lead (Pb) in Lake Koka and its inflows as well as in Lake Ziway were predominantly present as HMM (high molecular mass, i.e., > 10 kDa) forms, while arsenic (As), selenium (Se), cadmium (Cd) were more mobile during the dry season. In Lake Awassa, all except Cr and Mn were predominantly found as LMM species (low molecular mass, i.e. < 10 kDa) which can be attributed to the high concentrations of LMM DOC (dissolved organic carbon). During the wet season, results from the Lake Koka and its inflows showed that all trace elements were predominantly associated with HMM forms such as colloids and particles, demonstrating that the mobility of elements was reduced during the wet season. The colloidal fraction of elements such as Cr, Ni, and Cd was also correlated with dissolved Fe. As the concentration of LMM trace element species are very low, the mobility, biological uptake and the potential environmental impact should be low.     

Spatial variations of mercury in sediment of Minamata Bay, Japan

Mercury-contaminated effluent was discharged into Minamata Bay from a chemical plant over a period of approximately 40 years until 1968. In October 1977, the Minamata Bay Pollution Prevention Project was initiated to dispose of sedimentary sludge containing mercury concentrations higher than 25 mg kg(-1). In March 1990, the project was completed. In an effort to estimate current contamination in the bay, the vertical and horizontal distributions of mercury in sediment were investigated. Sediment core samples were collected on June 26, 2002 at 16 locations in Minamata Bay and Fukuro Bay located in the southern part of Minamata Bay. The sediment in Fukuro Bay had not been dredged. The total mercury concentration in surface sediment was 1.4-4.3 mg kg(-1) (2.9+/-0.9 mg kg(-1), n=9) for the dredged area of Minamata Bay and 0.3-4.8 mg kg(-1) (3.6+/-1.6 mg kg(-1), n=4) for Fukuro Bay. In the lower layers of long cores taken from both areas, the total mercury concentration decreased with depth and finally showed relatively uniform low values. These values can be considered to represent the background concentration absent of anthropogenic influence, which was estimated for the study area to be 0.068+/-0.012 mg kg(-1) (n=10). From the surface, the total mercury concentration in Fukuro Bay increased with depth and reached a maximum at 8-14 cm. In Minamata Bay, several centimeters from the surface the total mercury concentration did not change significantly having considerably higher values than the background level. At six stations, the methylmercury concentration was determined. Although the vertical variations were similar to those for total mercury, Fukuro Bay sediment showed a higher concentration of methylmercury than Minamata Bay sediment.     

Phylogenetic consistencies among chondrichthyan and teleost fishes in their bioaccumulation of multiple trace elements from seawater

Multi-tracer experiments determined the accumulation from seawater of selected radioactive trace elements (Mn-54, Co-60, Zn-65, Cs-134, Am-241, Cd-109, Ag-110m, Se-75 and Cr-51) by three teleost and three chondrichthyan fish species to test the hypothesis that these phylogenetic groups have different bioaccumulation characteristics, based on previously established contrasts between the carcharhiniform chondrichthyan Scyliorhinus canicula (dogfish) and the pleuronectiform teleost Psetta maxima (turbot). Discriminant function analysis on whole body: water concentration factors (CFs) separated dogfish and turbot in two independent experiments. Classification functions grouped the perciform teleosts, seabream (Sparus aurata) and seabass (Dicentrarchus labrax), with turbot and grouped the chondrichthyans, undulate ray (Raja undulata; Rajiformes) and spotted torpedo (Torpedo marmorata; Torpediniformes), with dogfish, thus supporting our hypothesis. Hierarchical classificatory, multi-dimensional scaling and similarity analyses based on the CFs for the nine radiotracers, also separated all three teleosts (that aggregated lower in the hierarchy) from the three chondrichthyan species. The three chondrichthyans were also more diverse amongst themselves compared to the three teleosts. Particular trace elements that were more important in separating teleosts and chondrichthyans were Cs-134 that was elevated in teleosts and Zn-65 that was elevated in chondrichthyans, these differences being due to their differential rates of uptake rather than loss. Chondrichthyans were also higher in Cr-51, Co-60, Ag-110m and Am-241, whereas teleosts were higher only in Mn-54. These contrasts in bioaccumulation patterns between teleosts and chondrichthyans are interpreted in the context of both proximate causes of underlying differences in physiology and anatomy, as well as the ultimate cause of their evolutionary divergence over more than 500 million years before present (MyBP). Our results and interpretation point to the possibility that radiation exposure regimes may be influenced by phylogeny, with implications for the adequacy of the marine reference organism approach in marine environmental protection.     

Life-cycle flow of mercury and recycling scenario of fluorescent lamps in Japan

A greenhouse pot experiment was conducted to evaluate the feasibility of using biosolids and Lolium perenne for the phytostabilization of copper mine tailings and to evaluate the patterns of metal accumulation and translocation in plants. Biosolids were applied either on the surface or mixed with the tailings at rates of 0, 6, and 12% w/w. All pots were seeded with L. perenne and after six months, the plants were harvested and separated into roots and shoots for metal concentrations analyses as well as some physiological characteristics of the plants. In order to correlate the metal content in plant tissues with some chemical properties, the pore-water of the substrates was analyzed for metals, pH and dissolved organic carbon. Results showed that biosolids application increased the dry biomass production of L. perenne and the shoot concentrations of N and chlorophyll. On the other hand, biosolids increased the concentration of Cu and Zn in the pore-water and in plant tissues. Despite this, there were no evident symptoms of phytotoxicity and the concentration of metals was within the normal ranges described for plants and below the maximum tolerable level for animals. In addition, plant tissue analysis showed that the application of biosolids could significantly reduce Mo uptake and shoot accumulation in plants. The metals were taken up by plants in the following order: Cu>Zn>Mo>Cd. The distribution patterns of metals in plants showed that metals were mainly accumulated in the roots and only a small amount of them were transported to the shoots. These results suggest that mixed application of biosolids (6%) and the use of L. perenne could be appropriate for use in programs of phytostabilization of copper mine tailings. However, these results should be tested under field conditions in order to confirm their efficacy under semi-arid Mediterranean climate conditions.     

电厂脱硝改造中锅炉钢结构节点的加固设计分析

山西某电厂由于环保要求,需对其锅炉进行烟气脱硝改造.在安装脱硝设备后,将改变其部分使用功能,需对锅炉尾部烟道及相关锅炉钢结构进行检测、鉴定、加固,以满足现有使用功能的要求.火力发电厂结构因其工艺等原因,具有很强的行业特点.为在加固过程中尽量减少对其生产的影响,将对其钢结构节点进行负载下加固.本文主要针对不同加固方法进行对比分析,找出最优的加固设计方法,为以后的钢结构电厂加固提供依据与参考.     

Assessing the effects of the Prestige oil spill on the European shag (Phalacrocorax aristotelis): trace elements and stable isotopes

The Prestige oil spill resulted in the mortality of several seabird species on the Atlantic NW coast of Spain. Shag casualties were particularly relevant, since populations are resident in the area the whole year round and because of several features which make them highly vulnerable to environmental hazards. Ecological catastrophes give us the opportunity of collecting samples which, otherwise, would be difficult to obtain. We examine the potential of shag corpses as bioindicators of inorganic pollution and the possible factors of variability, such as biological traits (sex, age) or nutrition status. We determined trace elements (Hg, Se, Cr, Pb, Zn and Cu) and isotopic signatures (¹⁵N, ¹³C) in soft tissues (muscle, liver) and in primary feathers formed at different times (before and after the Prestige) in individuals of known sex and age, collected at the time of the Prestige disaster. These were compared with data from another group of shags trapped accidentally in fishing gear in 2005.Our results did not seem to be affected by sex or age on any of the analysed variables. The higher nitrogen isotopic signatures in the soft tissues of the Prestige shags may be related to the nutrition stress caused by a poorer body condition, which is also reflected in increasing levels of some metals in the liver. This isotopic enrichment was also observed in newly forming feathers when compared to the old ones. On the other hand, the lower δ¹⁵N and Hg values in shag feathers from 2005 point to a shift in feeding resources to prey of lower trophic levels. We found that feather features (being an inert tissue and having a conservative composition), if combined with careful dating and chemical analysis, offer a very useful tool to evaluate temporal and spatial changes in seabird ecology in relation to pollution events.