Accumulation of total and methyl-Hg by mushrooms and earthworms was studied in thirty-four natural forest soils strongly varying in soil physico-chemical characteristics. Tissue Hg concentrations of ...both receptors did hardly correlate with Hg concentrations in soil. Both total and methyl-Hg concentrations in tissues were species-specific and dependent on the ecological groups of receptor. Methyl-Hg was low accounting for less than 5 and 8% of total Hg in tissues of mushrooms and earthworms, respectively, but with four times higher concentrations in earthworms than mushrooms. Total Hg concentrations in mushrooms averaged 0.96 mg Hg kg−1 dw whereas litter decomposing mushrooms showed highest total Hg and methyl-Hg concentrations. Earthworms contained similar Hg concentrations (1.04 mg Hg kg−1 dw) whereas endogeic earthworms accumulated highest amounts of Hg and methyl-Hg.
► Hg and MeHg concentrations in mushrooms and earthworms at unpolluted forest soils. ► Mushrooms and earthworms contained similar Hg concentrations. ► MeHg was present in traces but four times higher in earthworms than in mushrooms. ► Ecophysiological group influenced Hg and MeHg concentration in both receptors.
Accumulation of Hg and methyl-Hg by mushrooms and earthworms is species- and ecophysiological group dependent.
Low-cost sensors can be used to improve the temporal and spatial resolution of an individual's particulate matter (PM) intake dose assessment. In this work, personal activity monitors were used to ...measure heart rate (proxy for minute ventilation), and low-cost PM sensors were used to measure concentrations of PM. Intake dose was assessed as a product of PM concentration and minute ventilation, using four models with increasing complexity. The two models that use heart rate as a variable had the most consistent results and showed a good response to variations in PM concentrations and heart rate. On the other hand, the two models using generalized population data of minute ventilation expectably yielded more coarse information on the intake dose. Aggregated weekly intake doses did not vary significantly between the models (6-22%). Propagation of uncertainty was assessed for each model, however, differences in their underlying assumptions made them incomparable. The most complex minute ventilation model, with heart rate as a variable, has shown slightly lower uncertainty than the model using fewer variables. Similarly, among the non-heart rate models, the one using real-time activity data has less uncertainty. Minute ventilation models contribute the most to the overall intake dose model uncertainty, followed closely by the low-cost personal activity monitors. The lack of a common methodology to assess the intake dose and quantifying related uncertainties is evident and should be a subject of further research.
Understanding atmospheric mercury chemistry is the key for explaining the biogeochemical cycle of mercury and for improving the predictive capability of computational models. Increased efforts are ...being made to ensure comparable Hg speciation measurements in the air through establishing metrological traceability. While traceability for elemental mercury has been recently set, this is by no means the case for gaseous oxidized mercury (GOM). Since a calibration unit suitable for traceable GOM calibrations based on evaporation of HgCl
solution was recently developed, the purpose of our work was to extensively evaluate its performance. A highly specific and sensitive
Hg radiotracer was used for validation over a wide range of concentrations. By comparing experimental and calculated values, we obtained recoveries for the calibration unit. The average recoveries ranged from 88.5% for 1178 ng m
HgCl
gas concentration to 39.4% for 5.90 ng m
HgCl
gas concentration. The losses were due to the adsorption of oxidized Hg on the inner walls of the calibrator and tubing. An adsorption isotherm was applied to estimate adsorption enthalpy (ΔH
); a ΔH
value of -12.33 kJ mol
was obtained, suggesting exothermal adsorption. The results of the calibrator performance evaluation suggest that a newly developed calibration unit is only suitable for concentrations of HgCl
higher than 1 µg m
. The concentration dependence of recoveries prevents the system from being used for calibration of instruments for ambient GOM measurements. Moreover, the previously assessed uncertainty of this unit at µg m
level (2.0%, k = 2) was re-evaluated by including uncertainty related to recovery and was found to be 4.1%, k = 2. Calibrator performance was also evaluated for HgBr
gas calibration; the recoveries were much lower for HgBr
gas than for HgCl
gas even at a high HgBr
gas concentration (>1 µg m
). As HgBr
is often used as a proxy for various atmospheric HgBr species, the suitability of the unit for such calibration must be further developed.
Studies on the influence of CN on Hg methylation rates in aquatic systems draining gold mining (artisanal and small-scale) communities in Africa are rare. The study assessed the influence of CN on Hg ...methylation in aquatic sediments of two major river systems draining artisanal and small-scale gold mining (ASGM) communities of the Prestea-Huni Valley district, Southwestern Ghana. The miners extract gold (Au) through exclusive amalgam Hg-Au formation or cyanidation of Au-rich Hg-contaminated tailings, or a combination of both techniques. Hg water solubility and probable mercuric compounds in sediments of Hg-contaminated CN-loaded (River Aprepre) and Hg-contaminated non-CN (River Ankobra) aquatic systems within the district were investigated. THg was determined by CV-AAS after HF/HNO
3
/HCl digestion. MeHg in sediments were extracted with H
2
SO
4
/KBr/CuSO
4
-CH
2
Cl
2
; followed by aqueous-phase propylation, preconcentration-on-Tenax, and GC-CV-AFS. River Aprepre showed 4.58–14.83 ngMeHg/g as Hg (1.4–3.7% THg as MeHg), with 241–415 ngTHg/g, and 0.05–0.21 mgCN/kg. For River Ankobra, MeHg ranged 0.24–1.21 ngMeHg/g (0.08–0.35% THg as MeHg) with 162–490 ngTHg/g dw and CN < 0.001 mg/kg. There was positive correlation (
r
2
= 0.5974;
p
< 0.01) between MeHg and CN in River Aprepre. The water-soluble fraction of Hg in sediment from both rivers was < 1% of THg. Hg in sediments from River Aprepre were generally more soluble than that from River Ankobra, indicating that Hg in sediments from River Aprepre were potentially more bioavailable for methylation. Accordingly, the presence of CN in Hg-dominated river sediments potentially influences and enhances the solubility and mobility of Hg, resulting in increased Hg methylation rates.
The distributions of the total mercury (T-Hg), methylmercury (MeHg), and ethylmercury (EtHg) concentrations in soil and their relationship to chemical composition of the soil and total organic carbon ...content (TOC, %) were investigated. Core samples were collected from hill slope on the right and left riverbanks of the Idrija River. Former smelting plant is located on the right bank. The T-Hg average in each of the core samples ranged from 0.25 to 1650 mg kg−1. The vertical T-Hg variations in the samples from the left bank showed no significant change with depth. Conversely, the T-Hg varied with depth, with the surface, or layers several centimeters from the surface, tending to show the highest values in the samples from the right bank. Since the right and left bank soils have different chemical compositions, different pathways of mercury delivery into soils were suggested. The MeHg and EtHg concentrations ranged from n.d. (not detected) to 444 μg kg−1 and n.d. to 17.4 μg kg−1, respectively. The vertical variations of MeHg and EtHg were similar to those of TOC, except for the near-surface layers containing TOC greater than 20%. These results suggest that the decomposition of organic matter is closely related to organic mercury formation.
Display omitted
•The distributions of T-Hg, MeHg, and EtHg near the Idrija Hg mine were investigated.•The Hg values were compared to the chemical composition, TOC, and T-N of the soil.•The first data of EtHg in soil around the mine is reported.•The decomposition of organic matter is closely related to organic Hg formation.•Hg circulation among soil, air and plant with change of chemical forms was suggested.
Mercury is a neurotoxin, and limited prenatal exposure to it can affect long-term child neurodevelopment. However, results of epidemiologic studies of such exposure have been inconsistent. We ...examined the association of prenatal mercury exposure from maternal fish consumption with child neurodevelopment in northern Italy.
A population-based cohort of 606 children and their mothers was studied from pregnancy to age 18 months. Mercury levels were measured in maternal hair and blood during pregnancy and in umbilical cord blood and breast milk. Levels of polyunsaturated fatty acids (PUFAs) were measured in maternal serum. Maternal and child intakes of fish were assessed by using a food frequency questionnaire. The Bayley Scales of Infant and Toddler Development, Third Edition (BSID-III) was used to evaluate child neurodevelopment. Multivariate linear regression was used to examine the association of mercury exposure with BSID-III scores, after controlling for maternal fish intake, PUFAs during pregnancy, and several other confounders.
Mean weekly fish intake during pregnancy was less than 2 servings. Mercury concentrations in biological samples were low (mean, 1061 ng/g in hair) and moderately correlated with fish intake, particularly of carnivorous species. Maternal ω-3 PUFA concentrations were poorly correlated with fish intake. Maternal intelligence quotient (IQ) and child intake of fish were significantly associated with neurodevelopment scores. In multivariate models, the level of Hg exposure was not associated with neurodevelopmental performance at 18 months.
In this Italian population, neurodevelopment at 18 months was associated with child intake of fresh fish and maternal IQ rather than with mercury exposure. The expected beneficial effect of maternal fish intake (from maternal ω-3 PUFAs) was not found.
Despite located far from point sources of Hg pollution, high concentrations were recorded in plankton from the deep oligotrophic Lake Nahuel Huapi, located in North Patagonia. Native and introduced ...top predator fish with differing feeding habits are a valuable economic resource to the region. Hence, Hg and Se trophic interactions and pathways to these fish were assessed in the food web of this lake at three sites, using stable nitrogen and carbon isotopes.
As expected based on the high THg in plankton, mercury did not biomagnify in the food web of Lake Nahuel Huapi, as most of the THg in plankton is in the inorganic form. As was observed in other aquatic systems, Se did not biomagnify either.
When trophic pathways to top predator fish were analyzed, they showed that THg biomagnified in the food chains of native fish but biodiluted in the food chains of introduced salmonids. A more benthic diet, typical of native fish, resulted in higher THg bioaccumulation than a more pelagic or mixed diet, as in the case of introduced fish.
Se:THg molar ratios were higher than 1 in all the fish species, indicating that Se might be offering a natural protection against Hg toxicity.
Display omitted
•Total Hg and Se did not biomagnify in Lake Nahuel Huapi food web.•Mercury bioaccumulation in top predator fish was habitat-dependent.•Native and introduced fish had different Hg and Se bioaccumulation patterns.•Se:Hg molar ratios were >1 in all organisms.
Despite a 15-year long effort to define the “safety” of fish intake during pregnancy, there remains still uncertainty on this important public health issue. The evaluation of the toxic effects of ...contaminants, particularly mercury (Hg) in fish-eating populations is complicated by the fact that sea-food is also rich in beneficial nutrients, such as selenium (Se). There is toxicological plausibility of an antagonistic effects between Se and Hg, and some theoretical support for the inclusion of the Se–Hg interaction to better assess the risk linked with fish intake. To assess the effects of exposure to low-level Hg through fish consumption on the developing brain and the interaction between Hg and Se, we conducted an analysis at age 40 months in Italian children, enrolled in a prospective mother-child cohort, comparing additive and multiplicative models.
Participant subjects were the 470 children born within the Northern Adriatic Cohort II (NAC-II) cohort who were tested by using the Bayley Scales of Infant and Toddler Development third edition (Bayley-III) (BSID-III) at age 40. Family demographic and socioeconomic information, pregnancy and delivery history, parental and child medical history and food consumption were assessed through questionnaires. Maternal blood samples were collected during pregnancy, cord blood at birth and maternal milk 1 month after delivery. As other exposures of interest, we considered the level of Se in maternal and cord blood and in breast milk and the potential Se–Hg antagonism. Se and inverse of THg (1:THg) concentrations were categorized according to the tertiles of their distributions, in low, medium and high levels of exposure. The lower end of the composite cognitive score distribution closest to 20% was defined as suboptimal development. Multiple logistic regression were applied to assess the association between the dichotomized composite cognitive score and the categorized exposure to Se and 1:THg, and the antagonism between Se and 1:THg.
In the recruiting period, 900 pregnant women were enrolled in the cohort; 767 of these remained in the study at delivery and 470 children at 40 months. After excluding preterm births, 456 children were used in the final analyses. The larger difference in risk for suboptimal neurodevelopment was observed for the category with High THg and Low Se with OR = 2.55 (90% CI 1.02; 6.41) under the multiplicative and OR = 1.33 (90% CI 0.80; 1.87) under the additive model. The category High THg and High Se showed a very slightly better fit of the additive model (OR = 1.07, 90% CI 0.65; 1.50) versus the multiplicative (OR = 1.66, 90% CI 0.73; 1.77). A negative – antagonistic – interaction term for this category was estimated under the multiplicative model giving an OR = 1.17 (90% CI 0.42; 3.28).
Although this evidence of the effects of the Se–Hg antagonism on the children neuro-development needs to be confirmed, if Se can counterbalance Hg toxicity, the evaluation of the effect on human health of fish consumption, should also consider the diverse ratios between Se and Hg concentration in different fish species.
•The effects of exposure to low-level mercury (Hg) through fish consumption on the developing brain is unclear.•Fish is also rich in beneficial nutrients such as selenium (Se).•There is toxicological plausibility of interaction between Se and Hg.•A prospective mother-child cohort followed for 40 months.•Evidence of Se–Hg antagonism on the children neuro-development.
Display omitted
•17% and 20% APOE ε4 carriers were identified among mothers and new-borns.•Mothers carrying APOE ε4 had higher Hg, As in venous and cord blood.•Mothers carrying APOE ε4 allele had ...higher Se in venous blood and plasma.•Statistical models confirmed maternal APOE ε4 and venous plasma Se association.•Seafood, ever-smoking, and parity had strong influence on studied associations.
We investigated the relationship between lipid binding glycoprotein apolipoprotein E (apoE; gene APOE) polymorphisms (ε4 allele carriers versus no carriers = ε4+/ε4−) and trace elements (TEs) (e.g., (methyl)mercury, arsenic, lead, cadmium, selenium, manganese, copper, and zinc) in mothers (N = 223) and their new-borns (N = 213) exposed to potentially toxic metal(loid)s from seafood consumption. The apoE isoform encoded by the ε4 allele is believed to have beneficial effects in early life but represents a risk factor for age-associated diseases. Under certain conditions ε4 carriers are more susceptible to oxidative stress and metal(loid) toxicity. DNA from Croatian pregnant women (N = 223, third trimester) and their new-borns (N = 176), was genotyped for APOE by TaqMan® SNP assay – rs429358 and rs7412. Seafood intake data and TE levels in maternal urine, milk, hair, peripheral venous blood, mixed cord blood, and new-borns’ urine were available from previous studies. We compared TEs between ε4+ and ε4− carriers using Mann-Whitney U tests and applied multiple linear regression models to analyse the TE’s dependence on the presence of allele ε4 (genotypes ε3/ε4, ε4/ε4) in combination with other explanatory variables. We identified 17% (n = 37) and 20% (n = 35) ε4 allele carriers in mothers and new-borns, respectively. The Mann-Whitney U test showed that mothers with the ε4 allele had significantly higher mean levels of (methyl)mercury in peripheral venous blood, cord blood, and hair; arsenic in urine and cord blood; and selenium in peripheral venous blood and plasma. However, taking confounders into account, only the maternal plasma selenium remained statistically significant in the linear regression models (ε4 carriers vs non-carriers: 62.6 vs 54.9 ng/mL, p < 0.001). Literature suggestions of possible ε4 allele impact on Hg levels were not observed, while superior selenium status observed in healthy pregnant women carrying allele ε4 could be linked to the proposed APOE ε4 beneficial effects early in life.
Dissolved gaseous mercury (DGM) was studied in surface and deep waters of the Mediterranean Sea over the last 15years during several oceanographic cruises on board the Italian research vessels Urania ...and Minerva Uno, covering the Western and Eastern Mediterranean Basins as well as Adriatic Sea as its northernmost part. DGM was measured together with other mercury species (RHg - reactive Hg, THg - total Hg, MeHg - monomethyl Hg and DMeHg - dimethylmercury), and with water quality parameters in coastal and open sea deep water profiles. DGM represents a considerable portion of THg (on average 20%) in Mediterranean waters. Spatial and seasonal variations of measured DGM concentrations were observed in different identified water masses. DGM was the highest in the northern Adriatic, the most polluted part of the Mediterranean Sea as a consequence of Hg mining in Idrija and heavy industry in northern Italy, and near the Gulf of Lion. Generally, average DGM concentration was higher in the West and East Mediterranean Deep Waters (WMDW and EMDW) and Levantine Intermediate Water (LIW) than in overlaying Modified Atlantic Water (MAW); however, it was the highest in N Adriatic Surface waters (NAdSW) and consequently in outflowing Adriatic Deep Waters (AdDW). In deep water profiles the portion of DGM typically increased at depths with oxygen minimum and then towards the bottom, especially in areas with strong tectonic activity (Alboran Sea, Strait of Sicily, Tyrrhenian Sea), indicating its bacterial and/or geotectonic origin. During oceanographic cruises in 2011 and 2015 in the Tyrrhenian Sea, novel methods for continuous DGM determination in surface waters (Wangberg and Gardfeldt, 2011, Begu et al., 2016) were applied and compared to the standard method, and showed good agreement.
Display omitted
•Dissolved gaseous mercury (DGM) was studied in surface and deep waters of the Mediterranean Sea.•DGM represents a considerable portion of THg (average 20%) in Mediterranean waters.•Novel methods for continuous DGM determination in surface waters were applied and compared to standard method
PDF
