Low Concentrations Of Mercury Research Articles

Source and distribution of mercury in natural gas of major petroliferous basins in China

Based on the analysis of the natural gas samples of 146 wells from four major petroliferous basins of China, the source and distribution of mercury in natural gas in major petroliferous basins of China were identified. Studies have shown that the mercury concentration of natural gas in petroliferous basins of China varies widely, ranging from 0.01 to 4050 μg/m3. The gas well with the highest mercury concentration is in the Xushen gas field in the Songliao Basin. The mercury concentration in the craton basin is relatively low, and the secondary gas reservoir in the Tarim Basin has the lowest mercury concentration. In the rift basin, due to the presence of deep faults which cut the basement and mixing effects of deep fluids, the mercury concentration in natural gas may be abnormally high, e.g. the Xushen gas field in the Songliao Basin. In relatively stable basins where deep and large faults do not develop, mercury is primarily of organic origin. In rift basins where deep fluids are mixed with gas reservoirs, mercury in natural gas may mainly come from the deep fluids and is characterized by abnormally high mercury concentration and R/Ra values.

Sonochemical immobilization of MnO2 nanoparticles on NaP-zeolite for enhanced Hg (II) adsorption from water

MnO2 nanoparticles were loaded on NaP-zeolite sonochemically to assess their efficiency for mercury removal from water, and the substrate was synthesized via hydrothermal conversion of clinoptilolite. The ultrasonic waves supplied the reaction temperature and provided loading homogeneity. The influence of nanoparticle loading, concentration of potassium permanganate solution, and concentration of hydrochloric acid were investigated on the surface area and adsorption capacity of the product. The optimal synthesis conditions were obtained with ultrasonic waves, 15 wt% MnO2 loading, 0.05 mol.L−1 KMnO4 solution, and 36 wt% HCl concentration. The microscopic images showed that the ultrasonic-assisted method resulted in nano-sized (<10 nm) and uniformly distributed MnO2 particles on the surface of the substrate. Compared with conventional loading, the ultrasonic one resulted in 24.4 % and 8.5 % improvement in BET surface area and removal efficiency, respectively. The dynamics of adsorption from water at a very low initial concentration of mercury (10 μg.L−1) and the influence of competitive copper ions were investigated. The dual nature of ultrasonic waves helped synthesize a cost-effective adsorbent that fulfills the need for high quality drinking water at a large scale.

Prenatal exposure to legacy contaminants and visual acuity in Canadian infants: a maternal-infant research on environmental chemicals study (MIREC-ID)

BackgroundPrenatal exposure to environmental contaminants can have deleterious effects on child development. While psychomotor, cognitive and behavioural outcomes have been investigated in relation to chronic exposure, the associations with visual functions remains unclear. The present study’s aim was to assess the associations of prenatal exposure to legacy persistent organic pollutants and heavy metals with visual acuity in Canadian infants. The potential protective effects of selenium against mercury toxicity were also examined.MethodsParticipants (mean corrected age = 6.6 months) were part of the Maternal-Infant Research on Environmental Chemicals (MIREC) study. Concentrations of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), lead and mercury were measured in maternal blood during pregnancy, as well as in the cord blood. The Teller acuity card test (TAC) (n = 429) and the visual evoked potentials in a sub-group (n = 63) were used to estimate behavioural and electrophysiological visual acuity, respectively. Multivariable linear regression models were used to investigate the relationship between exposure to each contaminant and visual acuity measures, while controlling for potential confounders. Breastmilk selenium, which was available for about half of the TAC and VEP samples, was also taken into account in the mercury models as exploratory analyses.ResultsWe observed no significant associations between exposure to any contaminants and TAC. Analyses revealed a negative trend (p values < 0.1) between cord blood lead and mercury and electrophysiological visual acuity, whereas PCB and PBDE showed no association. When adding breastmilk selenium concentration to the mercury models, this association became statistically significant for cord concentrations (β = − 3.41, 95% CI = − 5.96,-0.86), but also for blood levels at 1st and 3rd trimesters of pregnancy (β = − 3.29, 95% CI = − 5.69,-0.88). However, further regression models suggested that this change in estimates might not be due to adjustment for selenium, but instead to a change in the study sample.ConclusionsOur results suggest that subtle, but detectable alterations of infant electrophysiological visual acuity can be identified in a population prenatally exposed to low mercury concentrations. Compared to behavioural visual acuity testing, electrophysiological assessment may more sensitive in detecting visual neurotoxicity in relation with prenatal exposure to mercury.

Elevated mercury concentrations in biota despite reduced sediment concentrations in a contaminated coastal area, Harboøre Tange, Denmark

Metals sequestered in coastal sediments are normally considered to be stable, but this investigation shows – somewhat surprisingly – that mercury concentrations in a previously contaminated area, Harboøre Tange, Denmark, have decreased since the 1980s. Mercury concentrations were determined in sediment and benthic biota and present values were compared to values in the 1980s and values from areas without known; history of mercury contamination. Concentrations in both the upper 20 cm of the sediments and; biota are considerably lower now compared to latest monitoring (1980s). Sediment.concentrations at most locations have decreased from the 100–300 ng Hg g−1 dry weight (dw) level to levels below the Background Concentration (BC) of 50 ng Hg g−1 dw defined by Oslo-Paris Convention for the Protection of the Marine Environment of the North-East Atlantic; some stations are at the 2–10 ng Hg g−1 dw level characteristic of Danish coastal sediments with no known history of mercury contamination. Concentrations of mercury in the benthic biota along Harboøre Tange have also decreased since the 1980s but despite the lowered mercury concentrations in the sediments, concentrations in most samples of benthic invertebrate fauna still exceed those in uncontaminated coastal areas and also the Environmental Quality Standard (EQS) of 20 ng Hg g−1 wet weight (≈100 ng Hg g−1 dry weight) defined by the European Union’s Water Framework Directive. Concentration ranges in selected organisms are: (Harboøre Tange l980s/Harboøre Tange now/uncontaminated areas - given in ng Hg g−1 dw): Periwinkles Littorina littorea 9000/150–450/55-77, blue mussels Mytilus edulis up to 9000/300–500/40–170, cockles Cerastoderma edule up to 8000/400–1200/200, brown shrimp Crangon crangon 700–2200/150-450/47, eelgrass Zostera marina up to 330/25–70/12. The present results - together with a literature review - show that a simple and straight forward relationship between the concentrations of mercury in sediment and benthic organisms does not necessarily exist.

Wetland water-management may influence mercury bioaccumulation in songbirds and ducks at a mercury hotspot.

Mercury is a persistent, biomagnifying contaminant that can cause negative behavioral, immunological, and reproductive effects in wildlife and human populations. We examined the role of wetland water-management on mercury bioaccumulation in songbirds and ducks at Kellys Slough National Wildlife Refuge Complex, near Grand Forks, North Dakota USA. We assessed mercury concentrations in blood of wetland-foraging songbirds (80 common yellowthroats [Geothlypis trichas] and 14 Nelson's sparrows [Ammospiza nelsoni]) and eggs of upland-nesting ducks (28 gadwall [Mareca strepera], 19 blue-winged teal [Spatula discors], and 13 northern shoveler [S. clypeta]) across four wetland water-management classifications. Nelson's sparrow blood mercury concentrations were elevated (mean: 1.00 µg/g ww; 95% CL: 0.76-1.31) and similar to those reported 6 years previously. Mercury in songbird blood and duck eggs varied among wetland water-management classifications. Songbirds and ducks had 67% and 49% lower mercury concentrations, respectively, when occupying wetlands that were drawn down with water flow compared to individuals occupying isolated-depressional wetlands with no outflow. Additionally, songbirds within impounded and partially drawn-down wetland units with water flow had mercury concentrations that were 26-28% lower, respectively, than individuals within isolated-depressional wetlands with no outflow. Our results confirm that mercury concentrations in songbirds at Kellys Slough continue to be elevated and suggest that water-management could be an important tool for wetland managers to reduce bioaccumulation of mercury in birds.

Mercury in the fish of New York's Great Lakes: A quarter century of near stability.

We collected 849 fish of 16 species from New York portions of Lake Erie, Lake Ontario and the intervening Niagara River and its tributary Cayuga Creek, and analyzed fillets from individual fish for total mercury. Concentrations ranged from 0.029 to 1.090 ppm wet weight, with 92% below the EPA tissue residue criterion of 0.3 ppm, and thus not posing an undue risk from human consumption. We compared these 2010-2017 results to historical data spanning 40 years to assess temporal changes. The temporal pattern was generally consistent among water bodies and species: Mercury concentrations differed little between the most recent collections and fish taken from 1999-2008 and 1988-1996, while concentrations in all three of these periods were generally lower than in 1970. Smallmouth Bass from Lake Ontario were an exception with a continued decline, likely due to diet change following the introduction of exotic prey. Overall, though, fish tissue mercury concentrations from these large water bodies, which integrate regional influences, appear to have changed little in the last quarter century. We also report a consistent spatial pattern for multiple species having lower mercury concentrations in Lake Erie than in Lake Ontario over the period of record.

Response mechanism of microbial community to the environmental stress caused by the different mercury concentration in soils.

Despite the toxicity of mercury for mammal has been widely studied in recent years, little is known on its impact on the soil microbiome. In this paper, the effects of mercury in soils microbial communities along a gradient of contamination from no to high concentration was assessed by the richness and diversity of microbial community using high throughput sequencing method. The richness of microbial community decreased gradually with the increase of culture time, while the low and medium concentration of mercury had little effect on the evenness of soil microbial community. Proteobacteria tolerated the mercury contamination, while Acidobacteria, Planctomycetes and Chloroflexi were sensitive to mercury pollution in phylum level. Omnitrophica and Ignavibacteriae microorganisms were very sensitive to mercury contamination and dead quickly when contaminated with mercury. Mercury contamination selected two mercury tolerance genuses which were Massilia and Burkholderia in genus level and at least 22 microorganisms such as Alkanindiges, Geothrix, Polycyclovorans and Sporichthya in genus which mainly from the Acidobacteria, Proteobacteria, Bacteroides, Chloroflexi and Omnitrophica phylum were sensitive to mercury. The bacteria tolerant to mercury in soil were Massilia and Burkholderia from Betaproteobacteria and Lysobacter, Luteimonas from Gammaproteobacteria, separately, they were Gram-negative bacteria with thin cell walls and complex ingredients that responded quickly to pollution stress.

Mercury exposure, risk factors, and perceptions among women of childbearing age in an artisanal gold mining region of the Peruvian Amazon

Recent studies from the Madre de Dios region of Peru report elevated mercury exposure among the general population. Our objective was to assess mercury exposure, risk factors, risk perceptions, and knowledge among women of childbearing age, a population of concern due to risks to infant and fetal health. We collected hair samples and administered a survey among 200 women aged 18–49 years residing in Madre de Dios. Hair total mercury (THg) concentrations were analyzed in accordance with EPA Method 7473. Associations between exposures and potential risk factors were analyzed using generalized linear mixed models. Geometric mean hair THg concentration (±standard deviation) for all participants was 1.62 ± 2.54 μg/g (range: 0.01–30.12 μg/g), and 67 participants (33.5%) had concentrations above the 2.2 μg/g reference dose established by the World Health Organization (WHO). Higher exposure was significantly associated with higher fish consumption (p = 0.03) and less mercury knowledge (p < 0.0001), but not with age or educational attainment. Most participants (86.2%) expressed concern about mercury contamination, but few (26.2%) had knowledge of the health risks associated with exposure. Many residents consumed fish species previously found to have low mercury concentrations, but more than 25% of participants reported consuming fish species with high mercury concentrations. We did not observe cross-sectional differences in fish intake among women who were pregnant or breastfeeding at the time of data collection.

An assessment of temporal trends in mercury concentrations in fish

The importance of fish consumption as the primary pathway of human exposure to mercury and the establishment of fish consumption advisories to protect human health have led to large fish tissue monitoring programs worldwide. Data on fish tissue mercury concentrations collected by state, tribal, and provincial governments via contaminant monitoring programs have been compiled into large data bases by the U.S. Environmental Protection Agency's Great Lakes National Monitoring Program Office (GLNPO), the Ontario Ministry of the Environment's Fish Contaminants Monitoring and Surveillance Program (FMSP), and many others. These data have been used by a wide range of governmental and academic investigators worldwide to examine long-term and recent trends in fish tissue mercury concentrations. The largest component of the trend literature is for North American freshwater species important in recreational fisheries. This review of temporal trends in fish tissue mercury concentrations focused on published results from freshwater fisheries of North America as well as marine fisheries worldwide. Trends in fish tissue mercury concentrations in North American lakes with marked overall decreases were reported over the period 1972-2016. These trends are consistent with reported mercury emission declines as well as trends in wet deposition across the U.S. and Canada. More recently, a leveling-off in the rate of decreases or increases in fish tissue mercury concentrations has been reported. Increased emissions of mercury from global sources beginning between 1990 and 1995, despite a decrease in North American emissions, have been advanced as an explanation for the observed changes in fish tissue trends. In addition to increased atmospheric deposition, the other factors identified to explain the observed mercury increases in the affected fish species include a systematic shift in the food-web structure with the introduction of non-native species, creating a new or expanding role for sediments as a net source for mercury. The influences of climate change have also been identified as contributing factors, including considerations such as increases in temperature (resulting in metabolic changes and higher uptake rates of methylmercury), increased rainfall intensity and runoff (hydrologic export of organic matter carrying HgII from watersheds to surface water), and water level fluctuations that alter either the methylation of mercury or the mobilization of monomethylmercury. The primary source of mercury exposure in the human diet in North America is from the commercial fish and seafood market which is dominated (>90%) by marine species. However, very little information is available on mercury trends in marine fisheries. Most of the data used in the published marine trend studies are assembled from earlier reports. The data collection efforts are generally intermittent, and the spatial and fish-size distribution of the target species vary widely. As a result, convincing evidence for the existence of fish tissue mercury trends in marine fish is generally lacking. However, there is some evidence from sampling of large, long-lived commercially-important fish showing both lower mercury concentrations in the North Atlantic in response to reduced anthropogenic mercury emission rates in North America and increases in fish tissue mercury concentrations over time in the North Pacific in response to increased mercury loading.

A preliminary assessment of mercury in the feathers of migratory songbirds breeding in the North American subarctic.

Passerines appear to have a greater sensitivity to mercury than other avian orders, and little data exists for mercury exposure in songbirds breeding at high latitudes. In this preliminary study, we examined mercury exposure in 12 migratory songbird species breeding in Denali National Park & Preserve, in subarctic interior Alaska. Overall, we analyzed 343 feather samples collected in 2015-2017 for their total mercury content. Mercury levels found in feathers indicates exposure during the period of feather growth, which we assume largely took place on the breeding ground. In this limited sample of songbird feathers, mercury concentrations ranged from near zero to 6.34 μg/g. Most species sampled showed relatively low mercury, but some individuals had high enough concentrations to be subject to adverse physiological and behavioral effects. There was an indication that mercury concentrations of breeding songbirds may vary by diet composition, with non-invertivorous species possibly tending towards lower mercury concentrations. Overall, however, the degree of mercury exposure observed was low for songbirds breeding in the subarctic. Further examination would prove useful in clarifying mercury exposure and ecological relationships in this under-studied region.

Insect Life Traits Are Key Factors in Mercury Accumulation and Transfer within the Terrestrial Food Web.

As plants and associated insects are at the bottom of some terrestrial food webs, they are the primary contributors to mercury (Hg) fluxes in ecosystems. In addition to the trophic position of these organisms, factors related to their life traits have been hypothesized to influence their exposure to Hg. This study investigates the transfer of Hg in a soil-nettle-insect system and the insect-related factors affecting their Hg concentrations in a revegetated chlor-alkali landfill. Twenty-three insect species were identified and classified according to their life traits, their relationship with nettle, and their morphological characteristics. We observed low total mercury (THg) concentrations in nettles, with only 1% methylmercury (MeHg) being detected, while concentrations ranged from 5 to 3700 μg/kg dry wt. in insects with a MeHg percentage of up to 75%. The nettle-related insects were primarily exposed to Hg through the food web with significant biomagnification, particularly at the level of secondary predators. Within the nettle-unrelated group, the insect habitat was the most explanatory factor, with the highest enrichment being for the insects that spent part of their cycle in direct contact with Hg sources. Therefore, these insects require special attention because they are an essential vector of Hg transfer for terrestrial top predators.

On reference method development for traceability of measurements of the mercury content in gaseous media

To certify gas mixtures in the range of low (10 -3 -10 -8 g/m 3 ) mercury concentrations, we have proposed and tested a traceable method for measuring the mass concentration of mercury in gaseous media by inductively coupled plasma mass spectrometry (ICP/MS). The proposed method is based on a scheme that provides for the mass spectrometer calibration for saturated vapors (physical constant) of pure metallic mercury, dosed directly into the carrier gas stream - argon. The undoubted advantage of this method is its applicability to various gases and gas mixtures, which allows you to simulate any matrix medium that affects the measurement results of mercury content when analyzed by other methods. On this basis, «Methods of measuring the mass concentration of mercury in binary gas mixtures by ICP/MS» were developed and certified. The measurement range of mercury mass concentration is from 0,03 to 1000 pg/m 3 , the relative expanded uncertainty of measurements U- 4 %.

Show your beaks and we tell you what you eat: Different ecology in sympatric Antarctic benthic octopods under a climate change context

Sympatry can lead to higher competition under climate change and other environmental pressures, including in South Georgia, Antarctica, where the two most common octopod species, Adelieledone polymorpha and Pareledone turqueti, occur side by side. Since cephalopods are typically elusive animals, the ecology of both species is poorly known. As beaks of cephalopods are recurrently found in top predator's stomachs, we studied the feeding ecology of both octopods through the evaluation of niche overlapping and specific beak adaptations that both species present. A multidisciplinary approach combining carbon (δ13C) and nitrogen (δ15N) stable isotope signatures, mercury (Hg) analysis and biomaterials' engineering techniques was applied to investigate the beaks. An isotopic niche overlap of 95.6% was recorded for the juvenile stages of both octopod species, dropping to 19.2% for the adult stages. Both A. polymorpha and P. turqueti inhabit benthic ecosystems around South Georgia throughout their lifecycles (δ13C: −19.21 ± 1.87‰, mean ± SD for both species) but explore trophic niches partially different during adult life stages (δ15N: 7.01 ± 0.40‰, in A. polymorpha, and 7.84 ± 0.65‰, in P. turqueti). The beaks of A. polymorpha are less dense and significantly less stiff than in P. turqueti. Beaks showed lower mercury concentration relative to muscle (A. polymorpha - beaks: 0.052 ± 0.009 μg g−1, muscle: 0.322 ± 0.088 μg g−1; P. turqueti - beaks: 0.038 ± 0.009 μg g−1; muscle: 0.434 ± 0.128 μg g−1). Overall, both octopods exhibit similar habitats but different trophic niches, related to morphology/function of beaks. The high Hg concentrations in both octopods can have negative consequences on their top predators and may increase under the present climate change context.

Foraging habits and levels of mercury in a resident population of bottlenose dolphins (Tursiops truncatus) in Bocas del Toro Archipelago, Caribbean Sea, Panama

A small and genetically isolated bottlenose dolphin (Tursiops truncatus) population resides year-round in the Bocas del Toro Archipelago-Panama (BDT). Photo-identification and genetic data showed that this dolphin population is highly phylopatric and is formed exclusively by individuals of the “inshore form”. This study aimed to investigate the trophic ecology and mercury concentrations of bottlenose dolphins in BDT to assess their coastal habits. We collected muscle samples (n = 175) of 11 potential fish prey species, and skin samples from free-ranging dolphins in BDT (n = 37) and La Guajira-Colombia (n = 7) to compare isotopic niche width. Results showed that BDT dolphins have a coastal feeding habit, belong to the “inshore form” (δ13C = −13.05 ± 1.89‰), and have low mercury concentrations (mean = 1637 ± 1387 ng g−1dw). However, this element is biomagnified in the BDT food chain, showing a marginal dolphins health risk (RQ = 1.00). We call for a monitoring pollutant program and conservation strategies aimed to protect the dolphin population at BDT.

Application of an Isotope Binary Mixing Model for Determination of Precise Mercury Isotopic Composition in Samples with Low Mercury Concentration.

An isotope binary mixing model was applied for high precision measurement of mercury isotope ratios in samples with low mercury concentrations by multicollector inductively coupled plasma mass spectrometry (MC-ICPMS). Standard addition was used to evaluate the precision and accuracy of the isotope composition calculations resulting from the isotope binary mixing model. A high, steady 202Hg signal of approximately 2.13 V was achieved, with the mercury concentration reaching 3 ng/mL. The isotopic composition of three standards (NIST SRM 1646a; NIST SRM 1575a; BCR 482) and natural samples were precisely determined. The standards and natural samples were diluted to low mercury concentrations (low to 0.90 ng/mL) and mixed with standard solutions (NIST SRM 3133) with high mercury concentrations (50 ng/mL); the isotopic compositions of low mercury concentration samples were calculated using an isotope binary mixing model after the isotopic compositions of the mixing solutions were measured. The results showed that the uncertainty of the calculated mercury isotopic compositions was in an acceptable range and the calculation isotope data were in good agreement with direct measurements. Our method allows the precise determination of mercury isotope composition in mercury solutions of concentrations (0.90 ng/mL) below the detection limit of the current system (3.00 ng/mL).

Tracking legacy mercury in the Hackensack River estuary using mercury stable isotopes.

Spatial redistribution of legacy mercury (Hg) contamination in the Hackensack River estuary (New Jersey, USA) was evaluated using mercury stable isotopes. Total Hg varied from 0.06 to 3.8 μg g-1 in sediment from the tidal Hackensack River and from 15 to 154 μg g-1 near historically contaminated sites in upper Berry's Creek, a tributary of the Hackensack River. δ202Hg values for total Hg from Berry's Creek and Hackensack River estuaries varied over a fairly narrow range (-0.44‰ to -0.21‰), but were highest for sediment from upper Berry's Creek. Isotope mixing plots show that residual legacy mercury from upper Berry's Creek is partially diluted by a low concentration and low δ202Hg pool of mercury associated with low organic matter content sediments similar to those in Newark Bay. Based on an isotope mixing model, we estimate that upper Berry's Creek contributes 21%-82% of the mercury in sediments in the Hackensack River estuary and its tidal tributaries, including upstream marsh habitats far from the primary source. Our results show that mercury stable isotopes can be used to track the redistribution of mercury in tidal ecosystems and highlight the potentially large areas which may be affected by legacy mercury contamination in estuaries.

Potential of Soil Bacteria as Mercury Bioremediation Agent in Traditional Gold Mining

Mandor Village has developed as a tradisional gold mining area since years ago. It involved activities that have led to extreme land condition and the release of mining residues, i.e., mercury, to the soils. The study examined the potential of soil bacteria as mercury bioremediation agent based on their population and activity in former mines with different ages. The bacterial population was measured by isolating soil bacteria on solid media using the pour plate method, and the colonies were enumerated during the incubation. The Nutrient Agar (NA) medium was used to obtain the total population, whereas the Salt Base Solution (SBS) was to determine the presence of mercury-tolerant bacteria. The addition of HgCl2 affected the number of the colonies. The colony only grew until the concentration of HgCl2 reached 5 mg/l, and the total colony was larger in older mines. The observation of bacterial activity showed that biotransformation performance was lower when the concentration of mercury was the same as its natural presence in soils (0.1-0.5 mg/l) compared with higher mercury level (1 mg/l). The research showed that lower mercury concentrations in nature reduced the natural ability of bacteria to transform pollutants. This study provides information that can assist the development of a technological approach to control mercury pollution in former traditional gold mines in an environmentally friendly manner using indigenous soil bacteria.

Mercury Exposure and Altered Parental Nesting Behavior in a Wild Songbird.

Methylmercury is a neurotoxin and endocrine disruptor and may impair avian reproduction directly through embryotoxicity or by altering parental care behaviors. We studied mercury exposure and incubation behavior of free-living tree swallows ( Tachycineta bicolor) nesting in artificial nest boxes. Using small temperature dataloggers, we measured incubation constancy (the proportion of each day the female spent incubating eggs), the number of incubation recesses taken per day, and the duration of incubation recesses. We also assessed maternal mercury exposure by measuring mercury concentrations in both blood and eggs. Females with higher mercury concentrations exhibited lower incubation constancy, took more frequent and shorter incubation recesses, and were more likely to take incubation recesses that caused nest temperature decreases that were likely to slow embryonic development. Overall, females that laid eggs with the highest observed mercury concentration (0.53 μg/g fww) spent an average of 12% less time incubating their eggs over the 14-day incubation period than females that laid eggs with the lowest mercury concentration (0.07 μg/g fww). Because less time spent incubating can lower egg temperatures, slow embryonic development, and potentially lengthen the incubation period, these results suggest that environmentally relevant mercury concentrations may negatively influence reproduction by altering parental nesting behaviors of wild songbirds.

Impacts of land use on an insectivorous tropical bat: The importance of mercury, physio-immunology and trophic position

Deforestation, agricultural intensification, and habitat homogenization are critical threats to biodiversity in Southeast Asia. Limited information is available on the trophic and physiological responses of tropical animals to these environmental changes. The wrinkle-lipped free-tailed bat Chaerephon plicatus is a cave roosting species that is experiencing population declines across Southeast Asia, where landscapes have been drastically modified. In our study site in central Thailand, we tested the hypothesis that wrinkle-lipped free-tailed bats living in landscapes that contrast in heterogeneity and land-use differed in mercury contamination, trophic position and physio-immunological status. Bats from less heterogeneous landscapes (dominated by rice crops, absence of large forest patches) occupied a lower trophic position than conspecifics from more heterogeneous landscapes (including large forest patches). Additionally, bats from these habitats had lower concentrations of mercury in erythrocytes, lower body mass, higher antioxidant superoxide dismutase (SOD), lower antioxidant glutathione peroxidase (GPx) and lower values of the GPx/SOD ratio than bats from more heterogeneous landscapes. Individual bat mercury concentrations were positively correlated with body mass and two immune markers (lysozyme and immunoglobulin) but were negatively correlated with plasma non-enzymatic antioxidant capacity. Our results suggest various links among landscape heterogeneity, mercury exposure/accumulation, and health status of wildlife in Southeast Asian countries.

Insights into the anodic stripping voltammetric behaviour of copper film electrodes for determination of trace mercury

New insights into the attractive stripping voltammetric performance as well as scope and limitations of the in-situ formed copper film electrode (CuFE) for measuring low concentrations of mercury are presented. Several main operational parameters were investigated and optimised. These include the composition of measurement solution, the concentration of Cu(II), accumulation potential and time. The CuFE showed excellent sensitivity accompanied with well-defined and reproducible signals for Hg(II), and very low background contribution in the presence of dissolved oxygen. It displayed wide linear response in the examined concentration range of 5–120 μg L−1 along with a remarkably low limit of detection, i.e. 0.3 μg L−1 after 300 s accumulation, and excellent repeatability with RSDs of 1.8%. CuFE was tested for measuring trace mercury in real sea water sample using standard addition method with 98% recovery and was compared with a standard ICP-MS method. CuFE was compared with other most frequently used metal film electrodes and several solid carbon substrate materials were evaluated for its preparation. Measurements were also performed in the presence of various potential inorganic and organic interferences. The CuFE revealed very promising electroanalytical characteristics.