Mercury in freshwater, estuarine, and marine fishes from Southern Brazil and its ecological implication

In this study, we measured the mercury concentration in 27 different fish species with high commercial value. Samples were taken from a region characterized by the diversity of aquatic environments. Mercury concentration in marine fish species varied from 30.4 to 216 ng g^???1, while in estuarine species, it varied from 12.4 to 60.3 ng g^???1. Compared to mercury concentration in marine species, none of the specimens from estuarine environment has reached a mercury concentration of 100 ng g^???1. However, mercury concentrations in species from the freshwater Patos lagoon are remarkably higher (15.3 to 462 ng g^???1) than those from the estuarine or marine region. Even though mercury concentrations in these fish species did not exceed the maximum level (500 ng g^???1) allowed by WHO for human consumption, they represent the main food source for sea birds and mammals coming from South Pole during their migration period.     

Sediments and sediment-derived soils in Illinois: pedological and agronomic assessment

Dredging sediments from water bodies in Illinois is done topreserve reservoir capacity, maintain navigation and recreationchannels, and restore habitats, but the fate of the sediments is an issue. In anticipation of a major sediment dredging operationin Lake Peoria in the Illinois River, a retrospective study ofsediment placement operations was performed. Sedimentspreviously dredged from reservoirs and placed in retaining pondswere sampled along with adjacent upland soils which served asreferences. Sediments from the Illinois River above Peoria weresampled from islands, river bottom, and adjacent floodplain. Dredged sediment retention ponds initially support wetlandvegetation. After dewatering, the physical properties of sediments tend to become similar to upland soils and theretention basins are then able to support conventionalagriculture. Sediment organic matter content was similar to localreference surface soils, and soil pH of the sediments wasneutral or above. Sediment textures are dominated by silts and clays, with the Lake Peoria samples being most clayey. Calcium was the dominant cation in all the samples, and micronutrientsmeasured were in adequate supply for plant growth. However,because the Illinois River watershed includes industrial inputs,river sediments contained elevated levels of some metals, butthey were generally below levels of regulatory concern. Resultsindicated that properly handled dredge sediments could make highquality agricultural soils. In addition, sediment placement onpoor soils could improve their productivity.     

Mercury wet deposition in rural Korea: concentrations and fluxes

The characteristics of Hg wet deposition were investigated in a rural area of Korea from August 2006 to July 2008. The volume weighted mean (VWM) Hg(T) concentration and cumulative Hg(T) flux were 8.8 ng L(-1) and 9.4 μg m(-2) per year, respectively. The VWM Hg(T) concentration varied seasonally, similar to the seasonal pattern in atmospheric Hg(p) concentration. The enhancement of both VWM Hg(T) and atmospheric Hg(p) concentrations in spring and winter was likely caused by the long-range transport of Hg from China. Monthly VWM Hg(T) and atmospheric Hg(p) concentrations were well correlated (R(2) = 0.36); however, there was no correlation between VWM Hg(T) and RGM (reactive gaseous mercury) concentrations, suggesting that Hg(p) was responsible for the majority of the Hg in wet deposition at this site. The VWM Hg(T) concentration in snow was statistically higher than in rain. In addition, the atmospheric Hg(p) concentration appeared to be elevated for snow events as well. This suggests that both elevated Hg(p) concentrations and the enhanced scavenging efficiency of snow for Hg(p) were responsible for the elevated VWM Hg(T) concentrations measured during snow events.     

Use of preserved museum fish to evaluate historical and current mercury contamination in fish from two rivers in Oklahoma, USA

We examined the effects of a commonly used preservation technique on mercury concentration in fish tissue. After fixing fish muscle tissue in formalin followed by preservation in isopropanol, we found that mercury concentration in fish muscle tissue increased by 18%, reaching an asymptote after 40 days. We used formalin–isopropanol-preserved longear sunfish (Lepomis megalotis) from the Sam Noble Oklahoma Museum of Natural History to examine historical changes and predict current mercury concentrations in fish from two rivers in southeastern Oklahoma. Glover River was free-flowing, while Mountain Fork River was impounded in 1970 and a coldwater trout fishery was established upstream from the collection site in 1989. Mercury concentrations in longear sunfish from Glover River showed no historical changes from 1963 to 2001. Mercury concentrations in longear sunfish from Mountain Fork River showed no change from 1925 to 1993 but declined significantly from 1993 to 2003. We also compared mercury concentrations of the most recently collected longear sunfish in the museum to mercury concentrations of unpreserved fish collected from the rivers in 2006. Concentrations of mercury in museum fish were not significantly different from mercury concentrations in unpreserved fish we collected from the rivers. Our study indicates that preserved museum fish specimens can be used to evaluate historical changes and predict current levels of mercury contamination in fish.     

液相色谱—原子荧光光谱法测定环境水体中甲基汞和乙基汞的方法研究

采用固相萃取法对地下水、地表水和生活污水中的甲基汞和乙基汞的进行富集,利用液相色谱—原子荧光光谱法对其进行定量测试.设计一系列验证实验对前处理和测试过程中的关键环节进行优化,确定了最优化的方法条件.结果显示:对甲基汞和乙基汞测定的方法检出限分别为0.16 ng/L和0.29 ng/L;重复测定的相对标准偏差分别为1.3...     

Mercury accumulation in caged Corbicula: rate of uptake and seasonal variation

The uptake and seasonal fluctuations of total mercury were followed in caged and uncaged Asiatic clams, Corbicula fluminea, over a 1-year period in South River, Virginia. Mercury was rapidly accumulated in clams transplanted from a nominally uncontaminated site into cages on the contaminated South River, reaching 0.99 μg g^???1 dry mass within the first month. Resident clams moved to cages had higher mercury contents after the first month (2.04 μg g^???1 dry mass) and at all subsequent times in the study. Large monthly fluctuations in mercury were noted for both resident caged and transplant caged clams with a notable peak occurring in early spring (4.31 μg g^???1 dry mass in resident caged clams). Tissue mass of caged clams steadily increased through the winter and early spring. Adjustment of mercury concentrations for tissue mass changes indicated that the changes in mercury contents were primarily due to uptake/release rather than changes in tissue mass (concentration/dilution). The present study demonstrates the utility of using caged Corbicula as mercury biomonitors and illustrates the importance of accounting for large, short-term changes of mercury content in Corbicula when designing long-term biomonitoring studies.     

Organochlorines and Mercury in Waterfowl Harvested in Canada

Samples of breast muscle from 32 species of waterfowl collected from 123 sites across Canada were analyzed for chlorobenzenes (CBz), chlordane-related compounds (CHL), hexachlorocyclohexanes (HCH), DDT, mirex, dieldrin, PCBs and mercury. ΣDDT, ΣCBz and ΣPCB were the compounds most frequently found above trace levels. ΣHCH and ΣMirex were detected the least often. Mercury was detected in all of the mergansers, over 50% of dabbling, bay and sea ducks, and in less than 2% of the geese analysed. The highest levels of contaminants were generally found in birds feeding at higher trophic levels such as sea ducks and mergansers. With the exception of a few samples of mergansers and long-tailed ducks from eastern Canada, which contained ΣPCB concentrations of 1.0–2.4 mg kg⁻¹, ΣPCB levels were less than 1 mg kg⁻¹ wet weight. Only one merganser from eastern Canada had a ΣDDT concentration (2.6 mg kg⁻¹ ww) which was greater than 1 mg kg⁻¹ ww. The highest ΣCHL (0.10 mg kg⁻¹ ww) was also found in mergansers from eastern Canada. Levels of total mercury in breast muscle were either low (< 1 mg kg⁻¹ ww) or below detection limits with the exception of a few samples of mergansers from eastern Canada which contained mercury concentrations of 1.0–1.5 mg kg⁻¹ ww. Health Canada determined that the organochlorine and mercury levels found in samples of breast muscle of ducks and geese analysed in this study did not pose a health hazard to human consumers and therefore these waterfowl were safe to eat.     

Mercury selection of allozymes in marine gastropods: Prediction and verification in nature revisited

Previous laboratory studies with mercury pollution revealed that the sensitive alleles are (S) for the phosphoglucose isomerase (PGI) locus in both Littorina punctata and L. neritoides and the allele (M+) for the amino peptidase (AP) locus in L. neritoides (Lavie and Nevo, 1986b). The present study tested the frequencies of these alleles at 8 sites along the Israeli Mediterranean shore. We found the frequencies of the sensitive alleles at the mercury polluted site at Akko to be lower than at all other seven sites. Therefore, we concluded that allozyme frequency distributions found in nature are consistent with survivorship patterns found in the laboratory. These results reinforce the suggestion (Nevo et al., 1980) that a monitoring system based on changes in population genetic structure is not only theoretically commendable but practically feasible in principle.     

Response of Mercury Contamination in Fish to Decreased Aqueous Concentrations and Loading of Inorganic Mercury in a Small Stream

Approximately 250 000 kg of mercury was lost towater and soils at the U.S. Dept. of Energy Y-12 Plantin Oak Ridge, Tennessee in the 1950s and early 1960s. A creek originating within the plant receivedcontinuous inputs of waterborne mercury, predominantlyas dissolved inorganic mercury, from groundwater,streambed contamination, and sump and process waterdischarges to the contaminated storm sewer network.These produce aqueous total mercury concentrations of1–2 g L^-1 in the upper reaches of the stream,decreasing to about 0.1–0.2 g L^-1 in its lowerreaches. A program to reduce mercury concentrationsin the creek identified specific sources (buildingsumps, contaminated springwater seeps, foundationdrains, and contaminated piping) and rerouted wateraround contaminated portions of the drain system orcollected and treated mercury-contaminated waterbefore discharging it. As a result, waterbornemercury concentrations in the creek and total mercuryloading were reduced from 1.8 g L^-1 to0.6 g L^-1 and 100 to 20 g d^-1, respectively, in the last 5 yr.Mean mercury concentrations in fish nearest sourceareas in the creek headwaters decreased at roughly thesame rate as waterborne total mercury concentrationsover the past five years, but at the facility boundarydownstream the decline in mercury bioaccumulation wasmuch less. At sites 5–15 km farther downstream, nodecrease was evident. Dissolved methylmercury tendedto increase with distance downstream in a patterninverse to that noted for its dissolved inorganicmercury precursor.Improvements in water quality and modification ofweirs to allow the passage of fish have resulted inthe establishment of large populations of fish inmercury-contaminated headwater areas previously devoidof fish. It may be that the accumulation, retention,and eventual downstream transport of this reservoir ofbiologically incorporated methylmercury has acted tobuffer against expected reductions in mercury in fishat downstream sites.     

Mercury fate in ageing and melting snow: development and testing of a controlled laboratory system

A snow cover can modify when, to what extent, and in what form atmospherically deposited mercury is released to the underlying surface media and/or back to the atmosphere. Investigations of mercury transport and transformation processes in snow packs are hampered by the difficulty in controlling experimental and melt conditions and due to the huge variability in the composition and physical structure of environmental snow packs. A method was developed that allows the detailed mechanistic investigation of mercury fate in snow that is made, aged and melted under controlled laboratory conditions. A number of control samples established that mercury in indoor air, scavenged during the snow making process, constitutes the dominant source of mercury in the artificial snow. No addition of mercury is required. The amount of mercury in fresh snow was quantitatively (102 and 106% in two experiments) recovered in the dissolved and particulate fractions of the melt water and the vessel head space, confirming a mass balance for mercury and the absence of unquantifiable mercury sources and sinks in the experimental system. In snow made from unmodified tap water, more than half of the mercury present in the snowpack was recovered from the bottom of the snow vessel after all of the snow had melted. Such late elution is indicative of mercury being mostly associated with particles that are filtered by, and retained in, the shrinking snowpack. Addition of salt to the snow-making water at an environmentally realistic pH notably shifted the distribution of mercury in the snowpack from the particulate to the dissolved phase, resulting in more than 60% of the mercury eluting in the dissolved phase of early melt water fractions.     

Mercury concentrations in oligohaline wetland vegetation and associated soil biogeochemistry

Concentrations of mercury were determined in above- and below-ground tissues of dominant plant species, as well as soils, in the wetlands of Lake Maurepas, Louisiana. Indicators of wetland soil biogeochemical status, such as soil redox potential, pore-water nutrient concentrations, and pore-water total sulfides, were also determined. Total mercury concentrations in plant tissues were within the typical range for vegetation not exposed to mercury contamination. Similarly, total mercury concentrations in soils were typical of uncontaminated wetlands within this geographic region. Soil methyl mercury levels in this study are slightly lower than those reported in other studies of nearby wetlands. This may reflect the less extensive geographic sampling in this study, or the low water levels in the Lake Maurepas system immediately prior to and during this study, which would have altered soil biogeochemical status. This is corroborated by measurements of soil redox potential and soil pore-water nitrogen and sulfur constituents conducted during this study that suggest minimal sulfate reduction was occurring in surficial soils. This study indicates that the wetlands surrounding Lake Maurepas are typical of many uncontaminated oligohaline wetlands in the southeastern U.S. in regard to mercury concentrations.     

Contaminant concentrations in Asian carps, invasive species in the Mississippi and Illinois Rivers

Populations of invasive fishes quickly reach extremely high biomass. Before control methods can be applied, however, an understanding of the contaminant loads of these invaders carry is needed. We investigated differences in concentrations of selected elements in two invasive carp species as a function of sampling site, fish species, length and trophic differences using stable isotopes (delta (15)N, delta (13)C). Fish were collected from three different sites, the Illinois River near Havana, Illinois, and two sites in the Mississippi River, upstream and downstream of the Illinois River confluence. Five bighead carp (Hypophthalmichthys nobilis) and five silver carp (Hypophthalmichthys molitrix) from each site were collected for muscle tissue analyses. Freshwater mussels (Amblema plicata) previously collected in the same areas were used as an isotopic baseline to standardize fish results among sites. Total fish length, trophic position, and corrected (13)C, were significantly related to concentrations of metals in muscle. Fish length explained the most variation in metal concentrations, with most of that variation related to mercury levels. This result was not unexpected because larger fish are older, giving them a higher probability of exposure and accumulation of contaminants. There was a significant difference in stable isotope profiles between the two species. Bighead carp occupied a higher trophic position and had higher levels of corrected (13)C than silver carp. Additionally bighead carp had significantly lower concentrations of arsenic and selenium than silver carp. Stable isotope ratios of nitrogen in Asian carp were at levels that are more commonly associated with higher-level predators, or from organisms in areas containing high loads of wastewater effluent.     

Effects of environmental conditions on historical buildings: lichens and NOx gases

Environmental conditions affect human life in various ways. One of the domains of environmental conditions is buildings, and amongst them, a major and important group is the historical buildings. To keep this inheritance alive, one needs to determine the effects of environmental conditions. In this work, effects of lichens and NOx on 7 historical buildings in Erzurum were investigated. Historical buildings are readily available for lichen growth, which takes a long time, and this growth was investigated as a sample of environmental effect that occurs through long periods of time. NOx, main source of which is traffic in Erzurum, were considered as the environmental effect of daily life.     

Crown condition surveys in Italian forests: issues in reporting findings

This study examines defoliation and discoloration findings collected throughout the Italian Level I network between 1997 and 2000. Prior to this period no Quality Assurance procedures had been implemented, so that earlier findings cannot be considered reliable. The aim of the study is to compare differentindices used in reporting findings, in order to determine the full potential and limitations of each. In international surveys,findings are normally expressed in terms of individual trees presenting a defoliation level greater than 2 %; this criterion,however, has been challenged since it is not based on scientificevidence. By analysing the distribution of defoliation values(grouped in 5% classes) relating to the main species (Fagus sylvatica, Quercus pubescens, Quercus cerris, Picea abies), the study examines the behaviour of statistical indices such as the median, the mode and the mean. Instead of using the traditional 25% threshold to determine the part of the population with the highest defoliation values, a procedureis suggested whereby a different threshold can be determined foreach species. It is established based on the 90° percentile of cumulative defoliation values recorded over the four-year period. Each index used to report findings possessesits own information potential, and the findings may at times appear contradictory. The use of a combined defoliation and discoloration index (Ilce = Lacking Crown Equivalent Index) is also proposed, but the results obtained do not differin substance from the results relating to defoliation alone. Thefunctional limitations of this index are due mainly to the way the data are collected: for this reason suggestions are made onhow to improve the procedure in future surveys.     

Persistent organic pollutants in Antarctica: current and future research priorities

As Antarctica's pivotal role in influencing global climate processes gains increasing attention so too does public and scientific interest in the general state of Antarctic ecosystem health as a function of multiple stressors, including contamination by anthropogenic chemicals. Persistent organic pollutant (POP) research internationally has sought to elucidate the impacts of an ever increasing diversity of POPs on the environment. The challenges of this research are compounded in the Antarctic context, by key gaps in historical data and our understanding of chemical behaviour in polar landscapes. In order to ensure maximum longevity and value of research outputs, efforts must be centred upon addressing these research gaps. Ultimately, Antarctic POP research will benefit from co-ordinated investment into spatially and temporally comprehensive research and monitoring efforts such as those responsible for the continued progress of this research field in the Arctic and other global regions.     

Silver and thallium historical trends in the Seine River basin

Records on pollution by metals of minor economic importance (e.g. silver and thallium) but which prove to be toxic are rarely documented in river sediment. This study used two sediment cores collected downstream of the Seine River to describe the temporal evolution of Ag and Tl concentrations in an urban catchment. Radionuclide analysis (i.e. Cs-137 and Pb-210) allowed dating sediment deposition within the cores (1933-2003). Ag concentration reached maximum values of 14.3-24.6 mg kg(-1) in the 1960s and 1970s, before gradually decreasing up to values which approximated 4 mg kg(-1) in 2003. In contrast, Tl concentrations remained roughly constant throughout the core (median value of 0.86 mg kg(-1)). Suspended solids was collected at upstream locations in the catchment to derive the background concentrations in Ag and Tl. Very high Ag concentrations were measured in the upstream Seine River sites (0.33-0.59 mg kg(-1)), compared to the values reported in the literature (0.055 mg kg(-1)). This suggests the presence of a widespread and ancient Ag pollution in the Seine River basin, as demonstrated by the very high Ag enrichment ratios recorded in the cores. Annual flux of particulate Ag in the Seine River was estimated at 1.7 t yr(-1) in 2003. In contrast, Tl concentrations remained in the same order of magnitude as the natural background signal (0.3-0.5 mg kg(-1)). This study suggests that the Seine River basin is free of Tl contamination. Future concerns should hence mostly rely on Ag contamination, in a context of increasing Ag uses and possible releases to the environment.