Levels Of Inorganic Mercury Research Articles

Redox Homeostasis Disclosed in the Saltmarsh Plant Halimione portulacoides upon Short Waterborne Exposure to Inorganic Mercury.

The saltmarsh plant Halimione portulacoides was shortly exposed to realistic levels of inorganic mercury (iHg) with the aim of investigating the adaptative processes of the roots and leaves regarding redox homeostasis, physiology, and Hg accumulation. Plants were collected at a contaminated (CONT) and a reference (REF) site to address the interference of contamination backgrounds. The influence of major abiotic variables (i.e., temperature and light) was also examined. Total Hg levels, antioxidant enzymes, lipid peroxidation (LPO), and photosynthetic activity were analyzed after 2 and 4 h of exposure. A poor accumulation of Hg in the roots was noticed, and no translocation to the stems and leaves was found, but plants from the CONT site seemed more prone to iHg uptake (in winter). Despite this, antioxidant modulation in the roots and leaves was found, disclosing, in winter, higher thresholds for the induction of enzymatic antioxidants in CONT leaves compared to REF plants, denoting that the former are better prepared to cope with iHg redox pressure. Consistently, CONT leaves exposed to iHg had remarkably lower LPO levels. Exposure did not impair photosynthetic activity, pinpointing H. portulacoides' ability to cope with iHg toxicity under very-short-term exposure. Biochemical changes were noticed before enhancements in accumulation, reinforcing the relevance of these responses in precociously signaling iHg toxicity.

Metal Exposure in Arica, Chile: Examining Toxic Elements.

Bioaccumulation of toxic metals in the population is associated with adverse health effects. Although some elements are essential for humans, high levels of exposure can be dangerous. To describe the levels of Inorganic Arsenic (AsIn), Cadmium (Cd), Chromium (Cr), and Mercury (Hg) in urine, and Lead (Pb) in blood in the population of Arica, Chile. Descriptive study. Beneficiaries of the Health Surveillance Program of Law 20.590 in sites of higher risk of exposure in the commune of Arica were considered eligible. The results of biological samples to measure their concentrations of AsIn, Cd, Cr, Hg in urine, and Pb in blood between August 2016 and May 2021 are described. 9520 samples from a population with a mean age of 40.5 years were studied. 4.21% of the adult population and 6.57% of the children had AsIn values above 35 μg/L, while at least 95 % of the total samples had levels below 33 μg/L. At least 90 % of the samples had Cd levels below 1.1 μg/L, and 8.44 % had Cd levels above 2 μg/L, higher in males (11.67%). There were no values above the reference in children. 99.77% and 99.33% had Cr and Pb values below the reference limit, respectively (using the lowest reference range established by Chile Ministry of Health (MINSAL) < 5 μg/L). Children did not present risk values for Cr, and 0.16% presented Pb concentrations between 5-10 μg/dL. All samples presented Hg concentrations below risk levels (< 10 μg/L). The results of this study suggest that a small percentage of the samples analyzed in the beneficiary population of Arica register metal concentration levels above national reference levels established by MINSAL, mainly AsIn, Cd, and Pb. It is essential to continue biomonitoring to reduce and prevent exposure to these metals, which can have harmful effects on human health.

Exposure of Mercury Species in Red Blood Cell and the Effects on Metabolites of Residents Living Near Coal-Fired Power Plants

BACKGROUND AND AIM: Coal-fired power plant is an important source of mercury for residents nearby. However, it’s still not clear for their exposure of different mercury species and the related health effects. Our study aims to assess the exposures of mercury species in residents near a coal-fired power plant and to clarify the effects of mercury species on metabolite profiles in human body. METHODS: Our study subjects were 152 adult residents living near a coal-fired power plant in central Taiwan, including 76 high-exposure group (HE) and 76 low-exposure group (LE), which were based on previous studies. We detected their inorganic mercury and methyl mercury levels in red blood cells by HPLC-ICPMS and analyzed the differences on levels and ratios between groups by SAS 9.4. The urinary and serum metabolites database of study subjects were established by previous study. MetaboAnalyst 4.0 was used to analyze and visualize the differences in metabolites profiles between the groups with high and low mercury species levels. RESULTS:The levels of inorganic mercury in red blood cells of HE group was significantly higher than those in LE group( 2.48 ± 0.48 µg / L and 1.13 ± 0.60 µg / L respectively) and there was no significant difference between two groups for methylmercury. The ratio of inorganic/total mercury levels were significantly higher in HE group when compared to LE group (12±13% and 7± 6% respectively). There was nine urinary and five serum metabolite profiles were significantly regulated by higher inorganic mercury levels of study subjects. There was no urinary and serum metabolite profiles significantly regulated by different methyl mercury levels. CONCLUSIONS:The levels of inorganic mercury in red blood cells were significantly higher among the residents living closer to the coal-fired power plant, and the higher inorganic mercury exposure might influence the expression of metabolites. KEYWORDS: Coal-fired power plant, Inorganic mercury, Methyl mercury, Metabolomics

Health Risk Assessment of Trace Metals Through Breast Milk Consumption in Saudi Arabia.

We previously measured the levels of inorganic mercury, methylmercury, lead, cadmium, and manganese in the breast milk of 203 healthy Saudi mothers who participated in a cross-sectional study between 2011 and 2013. The current study aimed to (1) calculate reference values (RVs) for these metals in breast milk based on the 95th percentile of the metal and the corresponding 95% confidence interval following the approach of the German Human Biomonitoring Commission, and (2) assess the health risk associated with these metals (except lead) by determining the hazard quotient (HQ) and hazard index (HI) for breastfed infants. The risk characterization for the lead was applied using the margin of exposure (MOE) approach. Moreover, the cancer risk (CR) associated with lead was calculated. The RV95s (percentage of samples for which the value was higher than the set value) for inorganic mercury, methylmercury, total mercury, cadmium, lead, and manganese in breast milk (μg/L) were 1.5 (7.9%), 1.5 (5.4%), 2.8 (8.9%), 2.5 (8.4%), 53 (11.3%), and 22.3 (11.8%) μg/L, respectively. The methylmercury, lead, and manganese levels in the present study were higher than those reported previously. The HQ for methylmercury greater than 1 was found in 68.5% of the samples, indicating there may be a potential non-carcinogenic health risk of infant exposure to the toxic metal via breast milk consumption. Despite the high cadmium and manganese levels in breast milk, our results suggested no health risk (HQ < 1). The HI representing the combined non-carcinogenic health risk of four metals was > 1, with methylmercury (74%) being the major contributor. The estimated MOE mean value of 0.134, less than 1, indicates that our breastfed infants may be at increased risk of neurodevelopmental impairments. The CR for lead in two infants was higher than the acceptable level of 1 × 10-4. Although our results may suggest potential carcinogenic and non-carcinogenic risks of infant exposure to toxic metals through breast milk consumption, the benefits of breastfeeding are well recognized and outweigh the potential risks.

Socioeconomic and Mercury Exposure to The Goldsmiths in Manggal Subdistrict of Urban Artisanal Gold Mining (UAGM) Area in Makassar, South Sulawesi, Indonesia

People living in gold mining towns experience high inorganic mercury levels when mercury vapor is emitted during the burning of amalgam as well as gold dorè in gold shops. These activities occur in Makassar, Indonesia, where a group of urban people established an artisanal waste recycling industry, in which they use mercury to recover the fine gold particles contained in the waste from goldsmiths’ activities. The goldsmith in Manggala is one of UAGM activities to design and manufacture of the unique gold jewelry. Mercury exposure to the goldsmith was happened through gold refining process. The aims of this research are to characterize the socioeconomic and potential mercury exposure to the goldsmith workers. The socioeconomic characterization of goldsmith was obtained by questionnaire survey, in-depth interviews and mercury exposure in hair was analyzed by using Particle-induced X-ray emission (PIXE) from Iwate Medical University. The result showed that the goldsmith workers in Manggala sub district is better than the other gold workers in Makassar in term of income and education. The lower education was graduated from elementary school and the higher education was graduated from the university. The monthly income of goldsmiths are unskilled, skilled and owner, <US$ 376 (29%), US$ 376-751 (61%), >751 (11%), respectively. The goldsmiths were exposure by mercury through the refining process in the gold. Therefore, it’s found that the average mercury concentration in hair is 6.6 μg/g (min-max:1.6-47.7 μg/g). The concentration of mercury in human hair of goldsmith is 5.03 μg/g, for indirect exposed and 8.18 μg/g for direct exposed. This result indicate that the level of mercury is seriously problem according to HBM threshold limit. Therefore, mercury exposure from UAGM activities must be prevented before the greater impact on society.

Biomonitoring of metals in inhabitants of Northern Chile: implications of surveillance in areas with historical exposures

Background: The presence of toxic metals in human populations is strongly associated with chronic diseases and should be monitored especially in communities with a history of chronic exposures as occurs in northern Chile.Objective: to establish concentrations and prevalence of exposure to metals in residents of the city of Antofagasta, Chile, and its main risk factors.Methods: a cross-sectional study in Antofagasta was made. The sample (1203 adults) had populational representability at the city level. Sociodemographic information, health status, and sources of exposure to metals were collected in the participants. Urinary Inorganic Arsenic (InAs), Cadmium (Cd), Chromium (Cr) and Mercury (Hg) levels, and Lead (Pb) in blood were measured using NIOSH methodology by Inductively coupled plasma atomic emission spectroscopy (ICP-AES).Results:The sample had an average age of 42.7 years, with an average residence time in the city of 30 years, predominantly women (54.5%), high smoking (51.5%), high occupation rate in mining activities (22.6%).Using cutoff used by the health authorities (35µg /L for urinary InAs, the prevalence was 8% in adults and 12.3% in children. However, 75% of the population has levels below 21.9 µg / L. The main factors associated with high levels of urinary inorganic arsenic in adults were sex (β= 3.12, IC 95% 0.2-6.05 for males) and low schooling (β= 7.1, IC 95% 0.4-14.6 in people having less 8 y of education). People residing more than 500 meters from fixed sources had higher InAs levels. Other metals are below risk levels defined by health authorities.Conclusions It is urgent that in this city all the sources related to InAs must be verified and develop social interventions and environmental health surveillance in order to reduce involuntarily exposure to this metalloid.

Dragonfly larvae serve as biosentinels for mercury

wreaks havoc in freshwater ecosystems, but monitoring the risk to wildlife can be challenging. Researchers have now shown how dragonfly larvae act as biosentinels for toxic mercury. When inorganic mercury enters the food chain, it gets converted to methylmercury, a toxin that causes neurological damage. Because inorganic mercury levels don’t always correlate with bioaccumulation of methylmercury, researchers have to sample living animals to understand poisoning risk in the environment. “It’s very hard to find the same organism in water bodies across a broad landscape,” says Collin Eagles-Smith, an ecotoxicologist with the US Geological Survey. But dragonfly larvae—predators that accumulate mercury—are widely found in freshwater ecosystems across the continent. With the help of more than 4,000 citizen scientists over 10 years, Eagles-Smith and his team collected dragonfly larvae from 100 national parks ( 2020, DOI: ). They found that mercury levels detected in larvae correlated well with other organisms sampled at

Blood and Urine Inorganic and Organic Mercury Levels in the United States from 1999 to 2016

BackgroundMercury is an environmental hazard. Organic mercury is biologically more toxic than inorganic mercury. Therefore, we studied recent trends in the blood levels of organic and inorganic mercury in the United States. MethodsA total of 56,445 participants that had blood mercury and urine mercury measurements in National Health and Nutrition Examination Survey (NHANES) 1999-2016 were included. The organic mercury level was obtained by subtracting the inorganic mercury level from the total mercury level. Results were analyzed using SPSS complex sample module version 25. Pregnant women, children ages <20 years, and different ethnicities were analyzed as subgroups. ResultsBlood organic mercury level increased from (geometric mean [95% confidence interval]) 0.08 [0.07-0.10] to 0.17 [0.16-0.18] µg/L during 1999-2016. It increased significantly (P <0.001) from 0.03 [0.02-0.03] to 0.07 [0.06-0.07] µg/L in children ages <20 and from 0.14 [0.09-0.21] to 0.36 [0.16-0.83] µg/L in pregnant women in this period (P <0.001). In 2013-2016, non-Hispanic Asians had the highest blood organic mercury level among different ethnicities, 0.93 [0.82-1.05] µg/L (P <0.001). Blood inorganic mercury level decreased from 0.31 [0.31-0.31] in 1999-2000 to 0.21 [0.21-0.22] µg/L in 2015-2016 (P <0.001). Urine mercury level decreased from 0.75 [0.71-0.80] in 1999-2000 to 0.16 [0.16-0.17] µg/L in 2015-2016 (P <0.001). ConclusionBlood organic mercury increased over the period 1999-2016 in the US population, including children and pregnant women, whereas there was a steady decline in both blood inorganic mercury and urine mercury levels.

Role of PEPT1in the transport of cinnabar in Caco-2 cells

Cinnabar, a mercury-containing mineral medicine, has been used as an ingredient in Traditional Chinese Medicines for treatment of various diseases for thousands of years and is still widely used today. The toxicity of cinnabar is much less than other mercury-containing compounds. This study aimed to evaluate the possible role of oligopeptide transporter1 (PEPT1) in intestinal uptake of cinnabar. Thus, the Caco-2 cell model was employed to investigate the differential transport levels and the probable transporter involved in the transport of cinnabar, mercury sulfide (HgS) and mercury chloride (HgCl2). Cells were incubated with the same molar concentration of cinnabar, HgS or HgCl2 and then the inorganic mercury content of apical (AP), cellular and basolateral (BL) side of the cell was measured by ultra-high liquid chromatography-inductively coupled plasma mass spectrometry (UPLC-ICP/MS) after the treatment, respectively. Their transportation levels were also investigated when pH was changed to 5.5 in AP side to define the role of the H+ dependent transporter. Effects of cinnabar, HgS or HgCl2 on transporter mRNA and protein expression levels were assayed by RT-PCR and Western-blot method, respectively. The possible transporter involved in the transport was examined by siRNA silencing and chemical inhibition. The results showed that the levels of inorganic mercury in the BL side for cinnabar and HgS were 49.39% and 30.41% of that in HgCl2 group. The transport levels of cinnabar and HgCl2 were significantly increased when the pH was changed to 5.5 on the AP side as compared with the control group (pH 7.4). Cinnabar significantly decreased the mRNA and protein expression of PEPT1. Transport levels of cinnabar were significantly decreased by PEPT1-siRNA and chemical inhibition of PEPT1. The present study demonstrates that PEPT1 may be an important transporter in the entry of cinnabar into the intestinal epithelium, and intestinal transport levels of cinnabar and HgS was lower than that of HgCl2.

DNA Damage and Immunological Responses in the Whiteleg Shrimp (Litopenaeus vannamei) Exposed to Sublethal Levels of Mercury.

Litopenaeus vannamei juveniles were exposed to sublethal levels (2.33-18.03µg/L) of inorganic mercury. Time of exposure (0, 24 and 168h) was a source of DNA damage. Mean comet tail length not changed significantly with mercury concentrations and exposure time, and this parameter cannot be used to assess DNA damage in this shrimp. Total hemocyte count showed a trend to decrease according to the increase of mercury concentrations, although no significant difference between treatments with mercury was observed. The phenoloxidase (PO) activity was not influenced by the time of exposure. At the end of the experiment, the PO in organisms exposed to 18.03µg/L was different from the control. The time of exposure has a more important influence in superoxide dismutase than the concentration of mercury. According to these results, a suitable criterion of water quality for long-term exposure of L. vannamei should be lower than 2µg/L of mercury.

Levels of Mercury in Fish-Eating Children, With and Without Amalgam Restoration.

Background:Mercury is a naturally occurring metal that exists in three forms: elemental (metallic), inorganic, and organic mercury. Amalgam, which is an alloy of inorganic mercury, is used as a restorative material in dentistry. Organic mercury gets ingested in the body mainly by the consumption of seafood. Mercury is also stated to cause various adverse health effects such as gastrointestinal disturbances, dermatitis, muscle weakness, and neurological disorders. In recent years, the use of amalgam has become a controversy stating the various adverse effects of mercury. Hence, the study was conducted to determine and compare the variation in levels of organic and inorganic mercury in fish-eating children before and after placement of amalgam restoration.Materials and Methods:Seventy-five subjects, 42 males (56%) and 35 females (44%) of age group ranging 7–13 years, living in South Canara district of Karnataka, India, were selected as a part of the study. Hair and urine samples were collected for estimation of organic and inorganic levels of mercury, respectively. Informed consent was collected from all the participating subjects.Results:On comparison between organic and inorganic mercury levels during the study period, the concentration of organic mercury in hair samples was greater irrespective of amalgam restorations present (1.172 and 0.085, respectively; P < 0.001).Conclusion:Thus inorganic levels of mercury do not seem to pose a threat as much as the organic levels observed in hair, which remain fairly constant for a longer period of time. Hence in a coastal region where this study was undertaken and fish being a staple food, the risk could probably be attributed to more of an organic toxicity than an inorganic one. Thus amalgam is relatively safe to be practiced and the controversy against it should be reevaluated.

Trends in and factors affecting the observed levels of urinary inorganic and total blood mercury among US children, adolescents, adults, and senior citizens over 2005–2012

Data from National Health and Nutrition Examination Survey (NHANES) for 2005–2012 were used to (i) study adjusted and unadjusted trends in the levels of urinary inorganic mercury (UIHG) and total blood mercury (TBHG) and (ii) factors that affect the observed levels of UIHG and TBHG among children aged 1–5 (CHLD15) and 6–11 (CHLD611) years, adolescents aged 12–19 years (ADOL), adults aged 20–64 years (ADLT), and senior citizens aged >=65 years (SNR). Decrease in adjusted levels of UIHG for each 2-year NHANES cycle for CHLD611 was 0.08114ng/L, 0.08379ng/L for ADOLs, and 0.12ng/L for ADLTs. Decreases in adjusted levels (AGM) of TBHG for each 2-year NHANES cycle were: 0.0632ng/L for CHLD15, 0.10239ng/L for CHLD611, 0.06424ng/L for ADOLs, and 0.056088ng/L for ADLTs. Among CHLD15 (0.34 vs. 0.39μg/L, p<0.01) and CHLD611 (0.42 vs. 0.44μg/L, p=0.04), males had lower AGMs for TBHG than females but among ADLTs (0.84 vs. 0.80μg/L, p<0.01) and SNRs (0.82 vs. 0.71μg/L, p<0.01) the reverse was true. For UIHG, for ADLTs (0.33 vs. 0.45μg/L, p<0.01) and SNRs (0.27 vs. 0.35μg/L, p<0.01) males had lower AGMs than females. Irrespective of age, those who were in unclassified race/ethnic group had the highest AGMs when compared with non-Hispanic whites, non-Hispanic blacks, and Mexican Americans and the differences, more often than not, were statistically significant (p<0.01). Irrespective of age, fish and shellfish consumption during the last 30days was associated with higher AGMs for both UIHG and TBHG than when fish and shellfish were not consumed and the differences were always statistically significant (p<0.01). Nonsmoker ADLTs (0.86 vs. 0.78μg/L, p<0.01) and SNRs (0.83 vs. 0.71μg/L, p<0.01) were found to have higher adjusted levels of TBHG than smokers. It is hypothesized that constituents in tobacco smoke may accelerate excretion of mercury from the body.

Mercury in breast milk from women in the Federal District, Brazil and dietary risk assessment for breastfed infants

Mercury is a toxic metal, ubiquitous in nature; it is excreted in breast milk from exposed mothers and may affect infant neuro-development. In this study, 224 breast milk samples provided by eight human milk banks in the Federal District of Brazil were analyzed for total mercury (THg), of which 183 were also analyzed for methyl mercury (MeHg), the most relevant form of this metal for the breastfed infants. Samples were acid digested in a microwave oven and THg determined by atomic fluorescence spectrometry (LOQ of 0.76 μg/L). Samples were lyophilized, ethylated and MeHg determined in a MERX automated system (LOQ of 0.10 μg/L). Inorganic mercury (IHg) levels were estimated from the THg and MeHg determined in the samples. Most of the samples were collected 1–2 months postpartum, with 38% during the first month. Over 80% of the samples had THg values above the LOQ, reaching a maximum of 8.40 μg/L, with a mean of 2.56 μg/L. On average, MeHg accounted for 11.8% of THg, with a maximum of 97.4%. Weekly intakes were estimated individually, considering the baby’s age and body weight at the time of milk collection. Mean weekly intake for MeHg was 0.16 ± 0.22 μg/kg bw, which represented 10% of the PTWI; in only one case, the intake exceeded 100% of the PTWI (1.90 μg/kg bw, 119% of PTWI). Mean intake for IHg was 2.1 ± 1.5 μg/kg bw, corresponding to 53% PTWI. These results indicate no health concern for the breastfed babies, a conclusion that can be extended to the consumers of breast milk donated to the milk banks, primarily immature and low weight babies.

Evaluation of the neurotoxic effects of chronic embryonic exposure with inorganic mercury on motor and anxiety-like responses in zebrafish (Danio rerio) larvae

Chronic exposure to mercury (Hg) can lead to cumulative impairments in motor and cognitive functions including alteration in anxiety responses. Although several risk factors have been identified in recent year, little is known about the environmental factors that either due exposure toward low level of inorganic mercury that may led to the developmental disorders. The present study investigated the effects of embryonic exposure of mercury chloride on motor function and anxiety-like behavior. The embryo exposed to 6 different concentrations of HgCl2 (7.5, 15, 30, 100, 125, 250nM) at 5hpf until hatching (72hpf) in a semi-static condition. The mortality rate increased in a dose dependent manner where the chronic embryonic exposure to 100nM decreased the number of tail coiling, heartbeat, and swimming activity. Aversive stimulus was used to examine the effects of 100nM interferes with the development of anxiety-related behavior. No elevation in both thigmotaxis and avoidance response of 6dpf larvae exposed with 100nM were found. Biochemical analysis showed HgCl2 exposure affects proteins, lipids, carbohydrates and nucleic acids of the zebrafish larvae. These results showed that implication of HgCl2 on locomotor and biochemical defects affects motor performance and anxiety-like responses. Yet, the potential underlying mechanisms these responses need to be further investigated which is crucial to prevent potential hazards on the developing organism due to neurotoxicant exposure.

汞在新建水库食物网中生物累积与风险评价研究进展

PDF HTML阅读 XML下载 导出引用 引用提醒 汞在新建水库食物网中生物累积与风险评价研究进展 DOI: 10.5846/stxb201407151442 作者: 作者单位: 水利部中国科学院水工程生态研究所 作者简介: 通讯作者: 中图分类号: X131.2 基金项目: 国家自然科学基金(51279112); 水利部"948"项目(200709) A review of the studies related to mercury bioaccumulation and risk assessment in the food web of newly constructed reservoirs Author: Affiliation: Key Laboratory of Ecological Impacts of Hydraulic-projects and Restoration of Aquatic Ecosystem,Ministry of Water Resources,Institute of Hydroecology,Ministry of Water Resources Chinese Academy of Sciences Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:汞是唯一参与全球循环的液态重金属。1974年,自美国学者Smith首次报道水库中鱼类总汞含量高于邻近自然湖泊以来,水库中鱼类汞升高的风险成为新建水库环境影响评价中的重要内容之一。汞在水库生态系统生物组分和非生物组分中含量升高的现象先后在世界各国报道,包括加拿大、美国、芬兰、泰国和巴西等。通过对系列的野外研究进行回顾,表明了水库形成后生态系统中汞的甲基化过程发生了变化。水库形成对汞在食物网中的鱼类、底栖生物、浮游生物的累积产生影响。水库中汞的生物累积、迁移转化主要与被淹没土壤和植物腐解过程有着直接或间接的关系。水库形成后,总汞、甲基汞和甲基汞比例在生态系统食物网各组分中的变化并不一致。蓄水后,水体中总汞变化较小,甲基汞和甲基汞比例上升明显;浮游生物尤其是浮游动物中总汞升高,但甲基汞和甲基汞比例升高更为明显;与浮游动物类似,底栖水生昆虫中总汞升高,甲基汞和甲基汞比例升高也更为明显;鱼类作为食物网顶级消费者,甲基汞比例一般在80%以上,在水库形成后鱼类总汞和甲基汞均明显升高,但甲基汞比例变化已经不大。这些变化揭示了水库形成后甲基汞在食物网传递的两个主要可能途径,一是微型生物食物网。通过悬浮颗粒物、浮游植物、浮游动物这一环节,甲基汞和甲基汞比例有明显的增加。第二个途径是底层生物食物网。通过悬浮颗粒物、细菌、碎屑食性底栖水生昆虫、肉食型底栖水生昆虫环节,甲基汞和甲基汞比例明显增加。这两种途径均能导致以水生昆虫、小鱼、甲壳类等为食的肉食性鱼类汞含量增加。水库形成后,生态系统中汞的甲基化发生了明显的"加速"过程。这种"加速"过程最直接的因素是成库后大量土壤淹没使得汞的甲基化平衡被打破。这个过程主要有两方面的影响。一方面是直接影响,被淹没土壤和植被在腐解过程中主动或被动地将甲基汞释放到水库生态系统中;另一方面是间接影响,被淹没土壤和植被的腐解使水库底部形成厌氧环境,有利于无机汞从被淹没土壤和植被中溶出,为甲基化反应提供充裕的、可供甲基化的无机汞,同时腐解产生的大量营养物质为微生物提供丰富食物来源,使硫酸盐还原菌大量繁殖,促进无机汞的甲基化。在我国,有关汞在新建水库食物网中生物累积和风险评价的研究有待进一步加强。 Abstract:Mercury is the only liquid metal in the global biogeochemical cycles. Since American scholar Smith first reported higher mercury concentrations in the muscle tissue of fish from reservoirs than in adjacent natural lakes in the USA, the risk of increased mercury levels in fish became a major issue in the assessment of an environmental impact of newly constructed reservoirs. Increased mercury concentrations in abiotic and biotic components of a reservoir ecosystem were reported in different countries, such as Canada, USA, Finland, Thailand, and Brazil. On the basis of the review of a series of field studies, it appears that the mercury methylation rate in an aquatic ecosystem changes after impoundment of the reservoir. Reservoir formation affects mercury bioaccumulation in fish, in benthic organisms, and plankton in the food web. Mercury bioaccumulation, migration, and transformation in a reservoir ecosystem are mainly related to the decomposition process in the flooded soil and vegetation directly or indirectly. After reservoir formation, total mercury concentrations, methylmercury concentrations, and the ratio of methylmercury to total mercury in the components of the food web of an aquatic ecosystem vary widely. After impoundment of the reservoir, methylmercury concentrations and the ratio of methylmercury to total mercury increase significantly while total mercury varies slightly in water. Total mercury concentrations increase while methylmercury concentrations and the ratio of methylmercury to total mercury increase more strongly in plankton (especially zooplankton). Similar results were also reported for benthic aquatic insects. Because fish are at the top of the food chain, the ratio of methylmercury to total mercury in fish has generally been above 80%. After reservoir formation, total mercury and methylmercury concentrations increase while the ratio of methylmercury to total mercury shows little or no change in fish. These results are indicative of two possible pathways of accumulation of methylmercury in the food web after reservoir formation. One is the plankton food web. Methylmercury bioaccumulates up from the suspended particulate matter, phytoplankton to zooplankton, and methylmercury concentrations and the ratio of methylmercury to total mercury increase. The other pathway is the benthic food web. Methylmercury bioaccumulates up from suspended particulate matter, from bacterial and detrivorous benthic aquatic insects to carnivorous benthic aquatic insects, whereas methylmercury concentration and the ratio of methylmercury to total mercury increase. Through these two pathways, methylmercury and the ratio of methylmercury to total mercury increase significantly in predatory fish that eat aquatic insects, small fish, and crustacean plankton. Mercury methylation in an aquatic ecosystem accelerates after reservoir formation. The balance of mercury methylation and demethylation changes and is affected by flooded soil and vegetation directly and indirectly. Methylmercury is released directly into a reservoir ecosystem during the process of microbial degradation of a flooded soil and vegetation. An anaerobic environment is formed via the degradation of the flooded soil and vegetation at the bottom of the water column of the reservoir. This process helps to dissolve inorganic mercury from the flooded soil and vegetation. The increased level of inorganic mercury is ready for methylation. Meanwhile, nutrients from the degradation serve as a food resource for microorganisms. Sulfate-reducing bacteria reproduce massively and contribute to methylation of inorganic mercury. In China, there is a need for more research on bioaccumulation and risk assessment of mercury in the food web of newly constructed reservoirs. 参考文献 相似文献 引证文献

Mercury speciation in seawater by liquid chromatography-inductively coupled plasma-mass spectrometry following solid phase extraction pre-concentration by using an ionic imprinted polymer based on methyl-mercury–phenobarbital interaction

Trace levels of inorganic mercury, methyl-mercury and ethyl-mercury have been assessed in seawater by high performance liquid chromatography (HPLC) hyphenated with inductively coupled plasma-mass spectrometry (ICP-MS) after solid phase extraction (SPE) pre-concentration with a novel synthesized ionic imprinted polymer. The adsorbent material was prepared by trapping a non-vinylated chelating ligand (phenobarbital) via imprinting of a ternary mixed ligand complex of the non-vinylated chelating agent, the template (methyl-mercury), and the vinyl ligand (metacrylic acid, MAA). Ethylene dimetacrylate (EDMA) and 2,2′-azobisisobutyronitrile (AIBN) were used as cross-linker and initiator reagents, respectively; and the precipitation polymerization technique was used in a porogen of acetonitrile/water (4:1). The best retention properties for methyl-mercury, inorganic mercury and ethyl-mercury species from seawater were obtained when loading 200mL of sample adjusted to pH 8.0 and at a flow rate of 2.0mLmin−1 on a column-packed with 200mg of the material. Quantitative mercury species recoveries were obtained using 4mL of an eluting solution consisting of 0.8% (v/v) 2-mercaptoethanol and 20% (v/v) methanol (pH adjusted to 4.5) pumped at a flow rate of 2.0mLmin−1. Mercury species separation was achieved on a Kinetex C18 column working under isocratic conditions (0.4% (v/v) 2-mercaptoethanol, 10% (v/v) methanol, pH 2.5, flow rate 0.7mLmin−1). ICP-MS detection was performed by monitoring the mercury mass to charge ratio of 202. The limits of quantification of the method were 11, 6.7, and 12ngL−1, for inorganic mercury, methyl-mercury and ethyl-mercury, respectively (pre-concentration factor of 50); whereas, analytical recoveries ranged from 96 to 106%. The developed method was successfully applied to several seawater samples from unpolluted areas.

Mercury Exposure and Antinuclear Antibodies among Females of Reproductive Age in the United States: NHANES.

BackgroundImmune dysregulation associated with mercury has been suggested, although data in the general population are lacking. Chronic exposure to low levels of methylmercury (organic) and inorganic mercury is common, such as through fish consumption and dental amalgams.ObjectiveWe examined associations between mercury biomarkers and antinuclear antibody (ANA) positivity and titer strength.MethodsAmong females 16–49 years of age (n = 1,352) from the National Health and Nutrition Examination Survey (NHANES) 1999–2004, we examined cross-sectional associations between mercury and ANAs (indirect immunofluorescence; cutoff ≥ 1:80). Three biomarkers of mercury exposure were used: hair (available 1999–2000) and total blood (1999–2004) predominantly represented methylmercury, and urine (1999–2002) represented inorganic mercury. Survey statistics were used. Multivariable modeling adjusted for several covariates, including age and omega-3 fatty acids.ResultsSixteen percent of females were ANA positive; 96% of ANA positives had a nuclear speckled staining pattern. Geometric mean (geometric SD) mercury concentrations were 0.22 (0.03) ppm in hair, 0.92 (0.05) μg/L blood, and 0.62 (0.04) μg/L urine. Hair and blood, but not urinary, mercury were associated with ANA positivity (sample sizes 452, 1,352, and 804, respectively), after adjusting for confounders: for hair, odds ratio (OR) = 4.10 (95% CI: 1.66, 10.13); for blood, OR = 2.32 (95% CI: 1.07, 5.03) comparing highest versus lowest quantiles. Magnitudes of association were strongest for high-titer (≥ 1:1,280) ANA: hair, OR = 11.41 (95% CI: 1.60, 81.23); blood, OR = 5.93 (95% CI: 1.57, 22.47).ConclusionsMethylmercury, at low levels generally considered safe, was associated with subclinical autoimmunity among reproductive-age females. Autoantibodies may predate clinical disease by years; thus, methylmercury exposure may be relevant to future autoimmune disease risk.CitationSomers EC, Ganser MA, Warren JS, Basu N, Wang L, Zick SM, Park SK. 2015. Mercury exposure and antinuclear antibodies among females of reproductive age in the United States: NHANES. Environ Health Perspect 123:792–798; http://dx.doi.org/10.1289/ehp.1408751

Inorganic and Organic Mercury Levels in the United States National Health and Nutrition Examination Survey (NHANES) 2005-2010

Aims: Mercury is an environmental hazard. Therefore, we studied recent trends in the blood level of organic and inorganic mercury in the United States (US). Methodology: We analyzed newly available data on blood inorganic mercury levels in NHANES 2005-2010. Organic mercury level was calculated by subtracting inorganic mercury level from the total mercury level. As complex sampling was used in NHANES, appropriate weights were used to adjust for oversampling of minorities and sampling from the same location. Results: There were 8364, 8161 and 8727 participants in NHANES 2005-6, 2007-8 and 2009-10 respectively. Inorganic mercury levels (geometric mean [95% confidence intervals]) were 0.31 [0.30-0.32], 0.30 [0.30-0.31], 0.28 [0.27-0.28] µg/L and organic mercury levels were 0.24 [0.190.30], 0.19 [0.14-0.25], 0.27 [0.22-0.33] µg/L in 2005-6, in 2007-8, in 2009-10, respectively. Inorganic mercury levels showed a significant decreasing trend ( P<.05). Organic mercury levels were significantly lower in participants aged <20 compared to those ≥20 years. The adjusted proportion (mean±SE) of participants with a total mercury level ≥5.8µg/L was 3.0±0.2%, 3.5±0.6%,

Blood inorganic mercury is directly associated with glucose levels in the human population and may be linked to processed food intake.

Background:The goals of the study were (1) to determine the impact of inorganic mercury exposure on glucose homeostasis; and (2) to evaluate the effectiveness of two community-based interventions in promoting dietary changes among American Indian college students to reduce risk factors for Type-2 Diabetes including fasting glucose, insulin, and mercury levels, weight, and body mass index.Methods:To accomplish goal one, the National Health and Nutrition Examination Survey (NHANES) dataset was analyzed using a previously published method to determine if there is a relationship between inorganic blood mercury and fasting glucose. To accomplish goal two, ten college students were recruited and randomly assigned to a group receiving the online macroepigenetics nutrition course and the support group for eliminating corn sweeteners. Participants in both groups were assessed for diet patterns, weight, body mass index (BMI), fasting glucose, insulin, and mercury levels. The interventions were implemented over a 10-week period.Results:Analysis of the NHANES data (n=16,232) determined a direct relationship between inorganic mercury in blood and fasting glucose levels (p<0.001). The participants who took the online macroepigenetics nutrition intervention course significantly improved their diets (p<0.01), and fasting blood glucose levels (p<0.01) while having lower levels of inorganic mercury in their blood compared to the subjects in the group who eliminated corn sweeteners from their diet and participated in the support group. The trend in lower blood inorganic mercury was strong with p=0.052. The participants in the support group who eliminated corn sweeteners from their diet achieved significant weight loss (p<0.01) and reduced their body mass index (p<0.01).Conclusion:Total blood mercury levels may be influenced by dietary intake of highly processed foods and lower inorganic mercury levels are associated with lower fasting glucose levels. Alternative community-based interventions emphasizing the role food ingredients and toxic substances play in gene modulation and the development of diseases can result in significant dietary improvements and reductions in risk factors associated with type-2 diabetes. A healthier diet can be promoted among community members using a novel online nutrition course. Consumption of corn sweeteners may be a risk factor in the development of obesity.

Albatross as Sentinels of Heavy Metal Pollution: Local and Global Factors

Heavy metal pollution in the Pacific Ocean has garnered significant attention in recent years, especially with regard to rising mercury emissions from Asia. Uncertainty exists over the extent to which mercury in biota may have resulted from increases in anthropogenic emissions over time. Albatrosses, including those inhabiting the North Pacific, are wide-ranging, long-lived, keystone, avian predators. Consequently, they serve as ideal sentinel species for investigating the effects of historical and contemporary pollution as well as local and global factors related to heavy metal exposure, bioaccumulation, and ecotoxicological risk. To date, high levels of mercury and lead have been documented in albatross species throughout the Pacific. To address biotic exposure to these multiple stressors, here we synthesize and conduct meta-analyses of total mercury, methylmercury, and lead exposure data in Black-footed albatross (Phoebastria nigripes) and Laysan albatross (Phoebastria immutabilis). Our approach includes data from the field and literature, and for total mercury and methyl mercury, we use measurements from museum feathers spanning the past 130 years for Black-Footed albatross. We discuss the use and application of stable isotopes (δ15N and δ13C) as a way to control for temporal changes in trophic structure and diet and we demonstrate the importance of conducting speciation analyses for mercury to account for historical, curator-mediated, inorganic mercury contamination of specimens. Our data showed higher levels of inorganic mercury in older specimens of Black-Footed albatross as well as two non-pelagic species (control samples) lacking historical sources of bioavailable mercury exposure, which suggests that studies on bioaccumulation should measure methylmercury rather than total mercury when utilizing museum collections. Changes in methylmercury levels in Black-Footed albatross were consistent with historical global and recent regional increases observed among published estimates and proxies of anthropogenic mercury emissions. At the local scale, previous research has also reported that lead paint exposure from buildings was also an important environmental stressor for Laysan albatross. Thus, albatross species face heavy metal exposure threats at both local (lead) and global scales (mercury, and potentially heavy metals in plastics). Specific types of plastic pollution entering marine environments have been documented to contain heavy metals at levels, which if bio-available, may present a non-localized source of lead exposure in albatross species known to ingest (and regurgitate to their young) large amounts of marine plastic. Heavy metal toxicity along with other stressors may undermine current and future reproductive outcomes in these seabird species, although unraveling effects from specific metals in the context of a complex metal mixture presents some challenges. Collectively, our findings and review of the literature suggest that albatrosses in this region may be an effective marine flagship species and raising the profile of these organisms likely would successfully support broader biodiversity conservation efforts in the North Pacific.