Publications by authors named "Xiaohang Xu"

29 Publications

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Occurrence of total mercury and methylmercury in rice: Exposure and health implications in Nepal.

Ecotoxicol Environ Saf 2021 Nov 22;228:113019. Epub 2021 Nov 22.

State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China.

Emerging studies have indicated that the consumption of rice could be the major methylmercury (MeHg) contributor to human mercury (Hg) exposure. Nonetheless, few studies are available on Hg in rice around the world, especially in countries with heavy rice diet. In this study, total Hg (THg) and MeHg levels in rice samples (n = 172) across Nepal were first investigated. The geometric mean THg was 7.05 ± 7.71 µg/kg with a range of 0.622 µg/kg to 158 µg/kg, and the maximum THg level was up to 791% of the Chinese National Standard Limit for THg in rice (20 µg/kg). The geometric mean MeHg was 0.820 ± 0.660 µg/kg with a range of 0.189 µg/kg to 8.59 µg/kg. Overall, the mean MeHg exposure (0.00445 ± 0.00477 µg/kg bw/day) and inorganic Hg (IHg) exposure (0.0360 ± 0.0739 µg/kg bw/day) were lower than the reference dose (RfD) of 0.1 µg/kg bw/day for MeHg and the provisional tolerable weekly intake (PTWI) of 0.571 µg/kg bw/day for IHg, respectively. Concerning different groups of vulnerable populations, the highest MeHg exposure (0.126 µg/kg bw/day) and IHg exposure (1.57 µg/kg bw/day) of preschoolers (37-50 months old) were approximately 126% of the RfD for MeHg and 275% of the PTWI for IHg. When the pregnant mothers eat the rice without awareness of the Hg content in rice, the mean and highest intelligence quotients (IQs) losses were 9554 and 118659 points, respectively, and the corresponding economic costs due to IQ loss could be 15.1 million USD and 188 million USD in Nepal. The results of rice THg and MeHg levels and corresponding exposure in populations highlighted the occurrence of rice THg and MeHg pollution issues in Nepal. More efforts should be made to protect younger groups in Nepal from high rice Hg exposure. CAPSULE: Owing to the high rice consumption rates relative to body mass, preschoolers (37-50 months) may meet the 126% reference dose (0.1 µg/kg bw/day) for MeHg and 275% provisional tolerable weekly intake (0.571 µg/kg bw/day) for IHg exposure in Nepal.
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http://dx.doi.org/10.1016/j.ecoenv.2021.113019DOI Listing
November 2021

Clinical Outcomes of Thoracolumbar Burst Fracture Treated by Trans-Kambin triangle versus Transpedicular Bone Grafting Combined with Posterior Internal Fixation.

World Neurosurg 2021 Dec 8;156:e130-e138. Epub 2021 Sep 8.

Department of Orthopedics, Northern Jiangsu People's Hospital, Clinical Medical College of Yangzhou University, Yangzhou, China. Electronic address:

Objective: The ideal management of thoracolumbar burst fracture (TLBF) remains controversial. We conducted this study to compare the effectiveness and safety of trans-Kambin triangle versus transpedicular bone grafting combined with posterior internal fixation (PIF) for TLBF.

Methods: Fifty-four patients were retrospectively analyzed and divided into 2 groups: the observation group (PIF combined with bone grafting via the Kambin triangle, n = 28) and the control group (PIF combined with bone grafting via transpedicular, n = 26). The anterior vertebral height ratio, sagittal Cobb angle, visual analog scale score, Oswestry Disability Index, bone healing rate, and neurologic complications were measured.

Results: All patients were followed up regularly for a mean period of 17.94 months (12 - 24 months). The anterior vertebral height ratio in the observation group was higher than that in the control group (93.93 ± 2.92 vs. 89.90 ± 5.54%, P = 0.006), and the loss of correction was lower (1.59 ± 1.20 vs. 3.00 ± 1.98%, P = 0.008). The observation group had lower sagittal Cobb angle at final follow-up (8.68 ± 3.75 vs. 11.33 ± 4.77 degrees, P = 0.046) and less correction loss (1.96 ± 1.32 ± 1.15 vs. 3.90 ± 2.39 degrees, P = 0.002). The visual analog scale score and Oswestry Disability Index in the observation group were lower (0.61 ± 0.43 vs. 0.92 ± 0.38, P = 0.016; 15.86 ± 4.11 vs. 19.18 ± 4.04, P = 0.010), while the fracture healing rate showed no significant difference (P > 0.05). No internal fixation failure or neurologic complications occurred in both groups during the follow-up.

Conclusions: Bone grafting via the Kambin triangle combined with PIF is a safe and effective technology for thoracolumbar burst fracture.
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http://dx.doi.org/10.1016/j.wneu.2021.09.008DOI Listing
December 2021

Biomagnification and trophic transfer of total mercury and methylmercury in a sub-tropical montane forest food web, southwest China.

Chemosphere 2021 Aug 24;277:130371. Epub 2021 Mar 24.

State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China. Electronic address:

Little is known about the bioaccumulation and trophic transfer of total mercury (THg) and methylmercury (MeHg) via food webs in terrestrial ecosystems, especially in subtropical forest ecosystems. In the present study, THg and MeHg were determined as well as the carbon (δC) and nitrogen (δN) isotope composition in samples of soils, plants, invertebrates, and songbird feathers to construct food webs in a remote subtropical montane forest in Mt. Ailao, southwest China and assess the bioaccumulation, biomagnification, and trophic transfer of Hg. Results showed that the trophic levels (TLs) of all consumers ranged from 0.8 to 3.3 and followed the order of songbirds > spiders > omnivorous insects > herbivorous insects > plants, and THg and MeHg exhibited a clear biomagnification up the food chain from plants-herbivorous/omnivorous insects-spiders-songbirds. The lowest MeHg concentration was observed in pine needles ranged from 0.104 to 0.949 ng g with only a 1.6% ratio of MeHg to THg (MeHg%), while the highest MeHg concentrations ranged from 425 to 5272 ng g in songbirds with MeHg% values of up to 96%. High values of trophic magnification slope (TMS) for THg (0.22) and MeHg (0.38) were observed in plant-invertebrate-songbird food chain, verifying the significant bioaccumulation of Hg, particularly MeHg, in the remote subtropical forest ecosystem. This study confirmed the production and efficient biomagnification of MeHg in remote subtropical montane forest and the significant bioaccumulation of MeHg in terrestrial top predators.
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http://dx.doi.org/10.1016/j.chemosphere.2021.130371DOI Listing
August 2021

MSF-Net: Multi-Scale Feature Learning Network for Classification of Surface Defects of Multifarious Sizes.

Sensors (Basel) 2021 Jul 29;21(15). Epub 2021 Jul 29.

School of Electronic Information, Wuhan University, Wuhan 430072, China.

In the field of surface defect detection, the scale difference of product surface defects is often huge. The existing defect detection methods based on Convolutional Neural Networks (CNNs) are more inclined to express macro and abstract features, and the ability to express local and small defects is insufficient, resulting in an imbalance of feature expression capabilities. In this paper, a Multi-Scale Feature Learning Network (MSF-Net) based on Dual Module Feature (DMF) extractor is proposed. DMF extractor is mainly composed of optimized Concatenated Rectified Linear Units (CReLUs) and optimized Inception feature extraction modules, which increases the diversity of feature receptive fields while reducing the amount of calculation; the feature maps of the middle layer with different sizes of receptive fields are merged to increase the richness of the receptive fields of the last layer of feature maps; the residual shortcut connections, batch normalization layer and average pooling layer are used to replace the fully connected layer to improve training efficiency, and make the multi-scale feature learning ability more balanced at the same time. Two representative multi-scale defect data sets are used for experiments, and the experimental results verify the advancement and effectiveness of the proposed MSF-Net in the detection of surface defects with multi-scale features.
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http://dx.doi.org/10.3390/s21155125DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8348716PMC
July 2021

Distributions of Total Mercury and Methylmercury in Dragonflies from a Large, Abandoned Mercury Mining Region in China.

Arch Environ Contam Toxicol 2021 Jul 23;81(1):25-35. Epub 2021 May 23.

State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China.

Dragonflies (Order Odonata) often are considered to be biosentinels of environmental contamination, e.g., heavy metals and/or persistent organic pollutants (POPs). Dragonflies (n = 439) belonging to 15 species of 8 genera were collected from an abandoned mercury (Hg) mining region in China to investigate the bioaccumulation of total Hg (THg) and methylmercury (MeHg). THg and MeHg concentrations in dragonflies varied widely within ranges of 0.06-19 mg/kg (average: 1.5 ± 2.2 mg/kg) and 0.02-5.7 mg/kg (average: 0.75 ± 0.65 mg/kg), respectively. THg and MeHg were positively correlated with bodyweight (THg: r = 0.10, P = 0.000; MeHg: r = 0.09, P = 0.000). Significant variations were observed among species, with the highest MeHg value (in Orthetrum triangulare) was fivefold higher than the lowest (in Pantala flavescens). These variations were consistent with those of nitrogen isotope (δN) values, indicating that increased δN, i.e., trophic levels, may reflect increased exposure and uptake of biomagnifying MeHg in dragonflies. A toxicological risk assessment found hazard quotients for specialist dragonfly-consuming birds of up to 7.2, which is 2.4 times greater than the permissible limit of 3, suggesting a potential toxicological risk of exposure.
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http://dx.doi.org/10.1007/s00244-021-00854-yDOI Listing
July 2021

Wound infiltration of dexmedetomidine as an adjunct to local anesthesia in postoperative analgesia for lumbar surgery.

Minerva Anestesiol 2021 09 13;87(9):1034-1041. Epub 2021 May 13.

Department of Orthopedics, Clinical Medical College, Northern Jiangsu People's Hospital, Yangzhou University, Yangzhou, China -

Introduction: Most patients undergoing lumbar surgery experience varying degrees of incision pain, leading to prolonged postoperative recovery and poor satisfaction with treatment. The objective of this meta-analysis was to evaluate the efficacy and safety of dexmedetomidine as an adjunct to local anesthesia for postoperative pain control after lumbar surgery.

Evidence Acquisition: Two authors independently searched eligible random controlled trials in electronic databases, including PubMed, Embase, Cochrane Library, Web of Science, CNKI (China National Knowledge Infrastructure), CBM (The Chinese BioMedical database) using the search terms "dexmedetomidine," "infiltration," and "lumbar." The random-effect model was used to perform the meta-analysis based on deviance information criteria.

Evidence Synthesis: Six trials evaluating a total of 330 patients were included in this review. Wound infiltration with dexmedetomidine significantly reduced the postoperative VAS scores (4 hour static VAS scores (MD=-1.03; 95% CI: -1.58 to -0.47; P=0.0003); 24 hour static VAS scores (MD=-0.66; 95% CI: -0.91 to -0.40; P<0.00001); 6th hour dynamic VAS scores (MD=-1.84; 95% CI: -2.23 to -1.45; P<0.00001) and total supplemental analgesic consumption (SMD=-2.01; 95% CI: -3.04 to -0.98; P<0.00001), prolonged the median time to first rescue analgesia (SMD=3.53; 95% CI:2.31 to 4.76; P<0.00001), and reduced the incidence of nausea or vomiting (RR=0.40; 95% CI: 0.17 to 0.93; P<0.05).

Conclusions: Dexmedetomidine infiltration appears to be a promising and safe adjunct for postoperative pain control after lumbar surgery. However, more studies are needed to assess the prevalence of other side effects.
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http://dx.doi.org/10.23736/S0375-9393.21.15469-0DOI Listing
September 2021

Extremely Elevated Total Mercury and Methylmercury in Forage Plants in a Large-Scale Abandoned Hg Mining Site: A Potential Risk of Exposure to Grazing Animals.

Arch Environ Contam Toxicol 2021 Apr 19;80(3):519-530. Epub 2021 Mar 19.

State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, People's Republic of China.

Ninety-five wild forage plants (belonging to 22 species of 18 families) and their corresponding rhizosphere soil samples were collected from wastelands of a large-scale abandoned Hg mining region for total Hg (THg) and methylmercury (MeHg) analysis. The forage plant communities on the wastelands were dominated by the Asteraceae, Crassulaceae, and Polygonaceae families. The THg and MeHg concentrations in the forage plants varied widely and were in the range of 0.10 to 13 mg/kg and 0.19 to 23 μg/kg, respectively. Shoots of Aster ageratoides showed the highest average THg concentration of 12 ± 1.1 mg/kg, while those of Aster subulatus had the highest average MeHg concentrations of 7.4 ± 6.1 μg/kg. Both the THg and MeHg concentrations in the aboveground plant parts exhibited positive correlations with the THg (r = 0.70, P < 0.01) and MeHg (r = 0.68, P < 0.01) concentrations in the roots; however, these were not correlated with the THg and MeHg concentrations in their rhizosphere soils. The species A. ageratoides, A. subulatus, and S. brachyotus showed strong accumulation of Hg and are of concern for herbivorous/omnivorous wildlife and feeding livestock. Taking the provisional tolerable weekly intake (PTWI) values for IHg recommended by the Joint FAO/WHO Expert Committee on Food Additives (JECFA in Summary and conclusions of the seventy-second meeting of the joint FAO/WHO expert committee on food additives Rome, Italy, 2010) for human dietary exposure of 4 ng/g into account, the daily intake of IHg by a 65 kg animal grazing on 1.0 kg of forage (dry weight) would be between 190 and 13,200 μg, three to five orders of magnitude higher than the permitted limit, suggesting a potential risk of exposure.
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http://dx.doi.org/10.1007/s00244-021-00826-2DOI Listing
April 2021

FAR-Net: Feature-Wise Attention-Based Relation Network for Multilabel Jujube Defect Classification.

Sensors (Basel) 2021 Jan 8;21(2). Epub 2021 Jan 8.

School of Electronic Information, Wuhan University, Wuhan 430072, China.

In production, due to natural conditions or process peculiarities, a single product often may exhibit more than one type of defect. The accurate identification of all defects has an important guiding significance and practical value to improve the planting and production processes. Concerning the surface defect classification task, convolutional neural networks can be implemented as a powerful instrument. However, a typical convolutional neural network tends to consider an image as an inseparable entity and a single instance when extracting features; moreover, it may overlook semantic correlations between different labels. To address these limitations, in the present paper, we proposed a feature-wise attention-based relation network (FAR-Net) for multilabel jujube defect classification. The network included four different modules designed for (1) image feature extraction, (2) label-wise feature aggregation, (3) feature activation and deactivation, and (4) correlation learning among labels. To evaluate the proposed method, a unique multilabel jujube defect dataset was constructed as a benchmark for the multilabel classification task of the jujube defect images. The results of experiments show that owing to the relation learning mechanism, the average precision of the three main composite defects in the dataset increases by 5.77%, 4.07%, and 3.50%, respectively, compared to the backbone of our network, namely Inception v3, which indicated that the proposed FAR-Net effectively facilitated the learning of correlation between labels and eventually, improved the multilabel classification accuracy.
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http://dx.doi.org/10.3390/s21020392DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7826679PMC
January 2021

Cadmium exposure as a key risk factor for residents in a world large-scale barite mining district, southwestern China.

Chemosphere 2021 Apr 21;269:129387. Epub 2020 Dec 21.

State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China. Electronic address:

Cadmium (Cd) contamination is easily generated during the mining and manufacturing of barium (Ba). In this study, concentrations of both Ba and Cd in rice, vegetables, pork, fish, drinking water, and soil samples from an active barite mining district were determined. Daily intakes of Ba and Cd, as well as corresponding health risks, were evaluated. The average total daily exposure doses of Cd were 0.0035 and 0.0012 mg/kg BW/day (geometric mean) in the mining zone (MZ) and the chemical plant zone (PZ), respectively. These values significantly exceed the provisional tolerable monthly intake (25 μg/kg BW/month, equal to 0.00083 mg/kg BW/day). Based on the daily exposure doses, vegetable consumption was the most significant Ba exposure route for residents, contributing around 66.1% of the total exposure. In contrast, rice consumption was the major Cd exposure pathway, accounting for about 85.6% of the total exposure. Although the geometric mean (0.17) and 95th percentile (P95, 0.75) of the total hazard quotient (HQ) for Ba were below the acceptable level (1), suggesting that there were no significant health effects caused by Ba exposure, Cd exposure was associated with significant health risks, with the geometric mean of the HQ (1.7) and the P95 (21) well above the acceptable limit (1), indicating the unacceptable non-carcinogenic risk of Cd exposure. In summary, high Cd exposure risk, rather than Ba, was observed for populations living in a large-scale active Ba mining area.
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http://dx.doi.org/10.1016/j.chemosphere.2020.129387DOI Listing
April 2021

Digital Forensics of Scanned QR Code Images for Printer Source Identification Using Bottleneck Residual Block.

Sensors (Basel) 2020 Nov 5;20(21). Epub 2020 Nov 5.

School of Electronic Information, Wuhan University, Wuhan 430072, China.

With the rapid development of information technology and the widespread use of the Internet, QR codes are widely used in all walks of life and have a profound impact on people's work and life. However, the QR code itself is likely to be printed and forged, which will cause serious economic losses and criminal offenses. Therefore, it is of great significance to identify the printer source of QR code. A method of printer source identification for scanned QR Code image blocks based on convolutional neural network (PSINet) is proposed, which innovatively introduces a bottleneck residual block (BRB). We give a detailed theoretical discussion and experimental analysis of PSINet in terms of network input, the first convolution layer design based on residual structure, and the overall architecture of the proposed convolution neural network (CNN). Experimental results show that the proposed PSINet in this paper can obtain extremely excellent printer source identification performance, the accuracy of printer source identification of QR code on eight printers can reach 99.82%, which is not only better than LeNet and AlexNet widely used in the field of digital image forensics, but also exceeds state-of-the-art deep learning methods in the field of printer source identification.
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http://dx.doi.org/10.3390/s20216305DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7663918PMC
November 2020

Multi-pathway mercury health risk assessment, categorization and prioritization in an abandoned mercury mining area: A pilot study for implementation of the Minamata Convention.

Chemosphere 2020 Dec 10;260:127582. Epub 2020 Jul 10.

State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China. Electronic address:

This is a systematic study of human health risk assessment (HHRA) and risk categorization for inorganic mercury (IHg) and methylmercury (MeHg) in Hg mining areas. A multi-pathway exposure model coupled with Monte Carlo simulation was constructed for the Wanshan Hg mining area (WSMM), Southwestern China, with consideration of oral ingestion (foodstuffs, water and soil), dermal contact (water and soil), and inhalation (gaseous Hg and particulate Hg). The results show that dietary intake (food and water), gaseous Hg inhalation, oral ingestion of soil particles, dermal contact, and particulate Hg inhalation comprised 88.3-96.3%, 3.49-6.14%, 0.14-5.3%, 0.02%, and <0.01% of total IHg ingestion, respectively. As expected, rice consumption contributed the highest proportion (86.3-92.7%) of MeHg. The study shows that the elevated MeHg exposure risk is the most significant issue in Hg mining areas. In addition, Hg risk categorization and prioritization in the WSMM are established for the first time based on rice-based exposure doses of IHg and MeHg. Target areas for future treatment and/or remediation are characterized according to thresholds of reference dose and provisional tolerable weekly intake for exposure doses, as well as risk screening values and risk control values for contaminated soil. The proposed multi-pathway exposure model is strongly recommended for the HHRA of Hg-contaminated sites worldwide and helps facilitate the implementation of the Minamata Convention on Mercury.
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http://dx.doi.org/10.1016/j.chemosphere.2020.127582DOI Listing
December 2020

Dietary exposure assessment of cadmium, arsenic, and lead in market rice from Sri Lanka.

Environ Sci Pollut Res Int 2020 Dec 27;27(34):42704-42712. Epub 2020 Jul 27.

State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China.

Rice is frequently reported to be contaminated with heavy metals (HMs); thus, the human health risks from its consumption have received increasing attention. A total of 165 commercial rice samples from Sri Lanka were collected to determine their cadmium (Cd), arsenic (As), and lead (Pb) concentrations. The exposure risk for Sri Lankans from the estimated daily intakes (EDIs) of these toxicants was assessed. Simultaneously, non-carcinogenic and carcinogenic risks were evaluated using hazard quotients (HQs) and the hazard index (HI). The results revealed that the average levels of Cd, As, and Pb in commercial rice were 0.080 ± 0.130, 0.077 ± 0.040, and 0.031 ± 0.050 mg/kg, respectively, with ranges of 0.003-0.727, 0.019-0.217, and 0.001-0.345 mg/kg (expressed on a dry weight basis), respectively. The average EDIs of Cd, inorganic As (iAs), and Pb were 0.772, 0.490, and 0.306 μg/kg body weight (bw)/day, respectively; these were below provisional tolerable weekly intake (PTWI) values recommended by the Joint FAO/WHO Expert Committee on Food Additives (JECFA), but iAs was above the recommended reference doses (RfDs) recommended by the United States Environmental Protection Agency (USEPA). However, approximately 25% and 75% of the Cd and iAs HQs for the Sri Lankan population, respectively, were greater than 1, suggesting a potential health risk, whereas the HQs for Pb was less than 1. Considering the additive effect, HI values of the P90, P95, P97.5, and P99 percentiles would reach 4.773, 6.458, 8.392, and 11.614, implying that intake of the combined metals might result in potential health risks.
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http://dx.doi.org/10.1007/s11356-020-10209-0DOI Listing
December 2020

Total mercury and methylmercury in rice: Exposure and health implications in Bangladesh.

Environ Pollut 2020 Oct 16;265(Pt A):114991. Epub 2020 Jun 16.

State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China.

Rice methylmercury (MeHg) contamination has attracted global attention, especially in countries where rice is considered a staple food. The daily rice intake rate in Bangladesh ranks first in the world; however, no attention has been paid to rice MeHg contamination in Bangladesh. Total Hg (THg) and MeHg concentrations of commercial rice (n = 172) from Bangladesh were first analyzed to accurately evaluate both rice MeHg and inorganic Hg (IHg) exposure in different age-gender groups of Bangladeshis. The corresponding adverse health impacts and associated economic loss were also assessed. The results showed that THg concentration in all samples ranged from 0.42 to 14.4 ng/g, with an average of 2.48 ± 1.41 ng/g, while the MeHg concentration ranged from 0.026 to 7.47 ng/g, with an average of 0.83 ± 0.60 ng/g. The highest average MeHg and IHg were both recorded in rice from Chittagong. The highest mean MeHg and IHg exposures were observed in 2-5 years-old group and were 16.2% of the reference dose (RfD) of 0.1 μg/kg/day for MeHg and 7.09% of the provisional tolerable weekly intake (PTWI) of 0.571 μg/kg/day for IHg. Surprisingly, MeHg exposure of the 2-5 year-old children could be up to 93.7% of the RfD at a high percentile (P99.9). The total intelligence quotient reduction caused by rice MeHg exposure could be 54700 points, and the associated economic loss is approximately 42.5 million USD. To avoid high rice MeHg exposure, it was suggested that diet structure be improved. More attention should be paid to residents with long-term rice MeHg exposure, especially children in the 2-5 year-old group.
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http://dx.doi.org/10.1016/j.envpol.2020.114991DOI Listing
October 2020

Methylmercury and inorganic mercury in Chinese commercial rice: Implications for overestimated human exposure and health risk.

Environ Pollut 2020 Mar 16;258:113706. Epub 2019 Dec 16.

State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China. Electronic address:

China is the largest rice producer and consumer in the world, and mercury (Hg) levels, particularly methylmercury (MeHg), in rice and health exposure risks are public concerns. Total Hg (THg) and MeHg levels in 767 (domestic = 709 and abroad = 58) Chinese commercial rice were investigated to evaluate Hg pollution level, dietary exposures and risks of IHg and MeHg. The mean rice THg and MeHg levels were 3.97 ± 2.33 μg/kg and 1.37 ± 1.18 μg/kg, respectively. The highest daily intake of MeHg and IHg were obtained in younger groups, accounted for 6% of the reference dose-0.1 μg/kg bw/day for MeHg, 0.3% of the provisional tolerance week intake-0.571 μg/kg bw/day for IHg. Residents in Central China and Southern China meet the highest rice Hg exposure, which were more than 7 times of those in Northwest China. Lower concentrations than earlier studies were observed along the implementations of strict policies since 2007. This may indicate that a declining temporal trend of Hg in Chinese grown rice and associated exposures could be obtained with the implementations of strict policies. Though there exist Hg pollution in commercial rice, Hg levels in Chinese commercial rice is generally safe compared with Hg polluted sites. Populations dwelling in China have relatively a quite low and safe MeHg and IHg exposure via the intake of commercial rice. Strict policies contributed to the decrease in THg and MeHg levels in Chinese-grown rice. More attention should be paid to younger groups.
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http://dx.doi.org/10.1016/j.envpol.2019.113706DOI Listing
March 2020

Characteristics, speciation, and bioavailability of mercury and methylmercury impacted by an abandoned coal gangue in southwestern China.

Environ Sci Pollut Res Int 2019 Dec 19;26(36):37001-37011. Epub 2019 Nov 19.

State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China.

During coal mining activities, a lot of coal gangue is produced, which usually contains high mercury (Hg) concentrations as well as the acid mine drainage (AMD) generator of pyrite. In the present study, the total mercury (THg) and methylmercury (MeHg) in gangue, water, sediment, paddy soil, and rice samples, collected from abandoned coal mining areas, were analyzed. Results showed that the THg concentrations ranged from 0.37 to 35 mg/kg (11 ± 8.4 mg/kg) and 0.15 to 19 mg/kg (2.0 ± 3.9 mg/kg) in gangue and sediments, respectively. For paddy soils, the THg concentrations and MeHg varied from 0.16 to 0.91 mg/kg and 0.71 to 11 ng/g, respectively. Rice samples exhibited wide concentration ranges of THg (3.0-22 ng/g) and MeHg (0.71-8.9 ng/g). Sequential extraction of Hg revealed that the nitric acid-extractable state Hg (F4) was the dominant Hg species in gangue and sediment, while humic acids state Hg (F3) was the dominant form in paddy soil. Compared with gangue, higher percentages of F3 and the residual state Hg (F5) in both sediment and soil samples implied the transformation of F4 to F3 and F5 during transportation. Soil n-HAs (the difference between the total organic carbon and humic acids) were positively correlated with both THg and MeHg in soil and rice, indicating that n-HAs enhance Hg bioavailability under acidic conditions. Further studies should be conducted to reveal the factors influencing the transformation of different Hg fractions, providing ideas on decreasing the bioavailability of Hg in coal mining areas.
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http://dx.doi.org/10.1007/s11356-019-06775-7DOI Listing
December 2019

Cadmium contamination in a soil-rice system and the associated health risk: An addressing concern caused by barium mining.

Ecotoxicol Environ Saf 2019 Nov 26;183:109590. Epub 2019 Aug 26.

State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China. Electronic address:

Cadmium (Cd) is associated with barite; however, its biogeochemical characteristics in environments impacted by barium (Ba) mining are not known. Here, we first revealed the characteristics of Cd concentrations, distributions, and chemical forms in the soil-rice system in Ba mining areas. The associated exposure and risk assessments of Cd via rice consumption were also conducted. Elevated levels of Cd with a wide range of 0.054-91 mg/kg were found in paddy soils, approximately 63% of which exceeded the national Grade II value for soil Cd levels in China (0.3 mg/kg). A significant positive correlation between the soil Cd and soil Ba demonstrated that large amounts of Cd were released into the environment from Ba mining. Cadmium accumulated remarkably in the rice grains (0.007-3.5 mg/kg). The chemical forms in the rice plants indicated that most of the Cd was in the pectate/protein fraction (F2, 92% in the grains and 61-71% in the other tissues), followed by the residual fraction (F3, 7.1% in the grains, 27-38% in the other tissues). A minor portion of Cd was in the soluble and aminophenol fraction (F1, 0.44% in the grains, 0.26-1.4% in the other tissues). The positive correlations observed between the grain Cd and F2 in the roots, stems and leaves suggested that Cd in the rice grain was mainly from F2. Similarly, the root F2 was also positively correlated with that in the stems/leaves, indicating the critical role of F2 in Cd migration in rice tissues. The estimated average hazard quotient (2.5) and annual excess lifetime cancer risk (21 × 10 a) were higher than the safety levels of 1 and 5.0 × 10 a, respectively, showing that the dietary intake of Cd via rice consumption posed high health risks to residents. Our study demonstrated that more concerns should be paid to Cd contamination in Ba mining areas.
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http://dx.doi.org/10.1016/j.ecoenv.2019.109590DOI Listing
November 2019

Dietary exposure assessment of total mercury and methylmercury in commercial rice in Sri Lanka.

Chemosphere 2020 Jan 3;239:124749. Epub 2019 Sep 3.

State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China. Electronic address:

Methylmercury (MeHg) in rice has attracted growing health concern over the past decade, due to the accumulation of high MeHg levels, which may pose potential health risk to humans. Rice is the staple food in Sri Lanka; nevertheless, the presence of micro pollutants, such as MeHg has been not investigated. Therefore, commercial rice samples from the Sri Lankan market (n = 163) were measured to reveal the total mercury (THg) and MeHg levels. THg (mean: 1.73 ± 0.89 ng/g, range: 0.21-6.13 ng/g) and MeHg concentrations (mean: 0.51 ± 0.37 ng/g; range: 0.03-3.81 ng/g) were low. Compared to the fish MeHg exposure, the rice MeHg exposure was generally lower in different consumption groups, suggesting that rice plays a less role than fish in MeHg exposure in Sri Lanka. Babies (infants and toddlers) at one year old may face fish MeHg exposure (0.17 μg/kg bw/day) higher than the reference dose for MeHg (RfD)-0.1 μg/kg bw/day, which was more than 5 times that of rice MeHg exposure (0.031 μg/kg bw/day). Future studies in Sri Lanka should focus on health impacts under long-term overexposure of MeHg, especially in vulnerable populations. Some diet changes should be made to mitigate MeHg exposure levels in Sri Lankans.
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http://dx.doi.org/10.1016/j.chemosphere.2019.124749DOI Listing
January 2020

Newly deposited atmospheric mercury in a simulated rice ecosystem in an active mercury mining region: High loading, accumulation, and availability.

Chemosphere 2020 Jan 24;238:124630. Epub 2019 Aug 24.

State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academic of Sciences, Guiyang, 550081, PR China. Electronic address:

Mercury (Hg) mining activities are an important anthropogenic source of atmospheric Hg. The Xunyang Hg mine located in Shaanxi Province is the largest active Hg producing centre in China. To understand the biogeochemical processes of atmospheric Hg through Hg mining activities, six groups of experimental pots were carefully designed to investigate the effect of Hg mining activities on Hg contamination from atmospheric deposition in the local surface soils. Based on the variations of Hg in the soil from the experimental pots, the deposition flux and loading of Hg in the Xunyang Hg mining district were investigated. The results showed that the average concentration of total gaseous mercury (TGM) as high as 193 ± 122 ng m was observed in the ambient air, which was orders of magnitude higher than that in remote areas. The average deposition flux and annual loading of atmospheric Hg were 72 mg m y and 10 t y, respectively. The dominant atmospheric Hg deposition is within a distance range of 6.0-12 km from the Hg retorting facility, accounting for approximately 85% of the total Hg loading. After 14 months of exposure, total mercury (THg) concentrations in the soil from the experimental pots increased 0.35-9.5 times, and the highest concentrations of methylmercury (MeHg) (3.7 ± 2.9 μg kg) in soil were observed in February. Concentrations as high as 643 μg kg THg and 13 μg kg MeHg in rice were observed in the second experimental year. Elevated concentrations of both THg and MeHg in rice indicated that the newly deposited atmospheric Hg was bioavailable, readily methylated, and taken up by rice, suggesting that the ongoing Hg mining activities cause serious Hg contamination in the soil-rice ecosystem and posed a threat to local residents in the Xunyang Hg mining area.
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http://dx.doi.org/10.1016/j.chemosphere.2019.124630DOI Listing
January 2020

Impacts of selenium supplementation on soil mercury speciation, and inorganic mercury and methylmercury uptake in rice (Oryza sativa L.).

Environ Pollut 2019 Jun 25;249:647-654. Epub 2019 Mar 25.

State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China. Electronic address:

Rice grain is known to accumulate methylmercury (MeHg) and has been confirmed to be the major pathway of MeHg exposure to residents in mercury (Hg) mining areas in China. Selenium (Se) supplementation has been proven to be effective in mitigating the toxicity of Hg. To understand how Se supplementation influences soil Hg speciation, a wide range of Se (0-500 mg/kg) was applied to Hg polluted paddy soils in this study, which decreased MeHg concentration in soil from 2.95 ± 0.36 to 0.69 ± 0.16 μg/kg (or 77%). After Se addition, humic acid state Hg (F4) was transformed into strong-complexed state Hg (F5), indicating that Hg bound up to the non-sulfur functional groups of humic acid (non-RSH) was released and reabsorbed by strong binding Se functional group (F5). As a result, inorganic Hg (IHg) was reduced by >48%, 18%, and 80% in root, stem, and grain, respectively, however, the reduction was not apparent in leaf. Substantial reductions were also found for MeHg in grain and root, but not in stem and leaf. Soil is suggested to be the main source of both MeHg and IHg in rice grain. Such a finding may provide an idea for improving Hg-polluted paddies through controlling soil IHg and MeHg. Further research on the molecular structure of the strong-complexed Hg in F5 should be conducted to elucidate the mechanism of Hg-Se antagonism.
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http://dx.doi.org/10.1016/j.envpol.2019.03.095DOI Listing
June 2019

New insights into the chemical forms of extremely high methylmercury in songbird feathers from a contaminated site.

Chemosphere 2019 Jun 14;225:803-809. Epub 2019 Mar 14.

State Key laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China. Electronic address:

The chemical forms of mercury (Hg), particularly methylmercury (MeHg), in songbird feathers from an abandoned mining region were analyzed via X-ray absorption near-edge structure analysis (XANES). In feathers, proportions of MeHg as total mercury (75.6-100%) quantified by the XANES were directly comparable to the chemical extraction values (74.1-95.9%). Most of MeHg were bound with cysteine (Cys) and reduced glutathione (GSH), whereas inorganic mercury (IHg) was mainly bound with GSH. These results were consistent with those found in fish muscles and human hairs of both fish consumers and occupational Hg exposure populations. Our study suggested that chemical forms and speciation of Hg were highly dependent on the exposure sources and food consumption, respectively. Bird feathers were able to selectively accumulate MeHg due to their special binding ways. However, detailed mechanisms of Hg accumulation in bird feathers remain to be further elucidated.
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http://dx.doi.org/10.1016/j.chemosphere.2019.03.060DOI Listing
June 2019

Effects of Selenium on Mercury Bioaccumulation in a Terrestrial food Chain from an Abandoned Mercury Mining Region.

Bull Environ Contam Toxicol 2019 Mar 14;102(3):329-334. Epub 2019 Jan 14.

Guangxi Key Laboratory of Forest Ecology and Conservation, College of Forestry, Guangxi University, Nanning, 530004, Guangxi, China.

Few reports of the relationship exist between mercury (Hg) and selenium (Se) from locations of severe Hg contamination in terrestrial environments. Here, we report the concentrations of Hg and Se as well as Se:Hg molar ratios in biotic samples collected from a region with a long history of Hg mining. Nitrogen isotopes (δN) were analyzed to confirm the trophic levels. Results showed that bird feathers at the top trophic level exhibited the highest Hg concentrations, while the lowest concentrations were found in herbivorous insects, demonstrating a significant biomagnification across the food chain. In contrast, herbivorous insects of different types (generalists vs. specialized rice pests) exhibited both the highest and the lowest concentrations of Se, indicating a lack of biomagnification. Indeed, Se was correlated positively with Hg when Se:Hg ratios were greater than one, suggesting Se:Hg molar ratios can be a controlling influence on Hg in terrestrial organisms.
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http://dx.doi.org/10.1007/s00128-019-02542-zDOI Listing
March 2019

Atmospheric deposition of antimony in a typical mercury-antimony mining area, Shaanxi Province, Southwest China.

Environ Pollut 2019 Feb 1;245:173-182. Epub 2018 Nov 1.

State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550002, PR China. Electronic address:

Mercury-antimony (HgSb) mining activities are important anthropogenic sources of Hg and Sb to the local environment. The Xunyang HgSb mine situated in Shaanxi Province is an active Hg mine in China. To understand the emission, transportation, and deposition of Sb through HgSb mining activities, current study systematically monitored the Sb concentration in precipitation in the Xunyang HgSb mining district. Five groups of experimental pots were carefully designed to further investigate the influence of HgSb mining activities on the Sb contamination in the local surface soil. Based on the overtime increasing of the Sb concentrations in soil from experimental pots, for the first trial, we estimated the atmospheric deposition flux/mass of Sb in the Xunyang HgSb mining district. Our results showed that the concentrations of Sb in precipitation in the Xunyang HgSb mining district ranged from 0.71 μg L to 19 μg L (mean = 4.2 ± 4.5 μg L), which was orders of magnitude higher than that at the control site. As expected, the concentration of Sb in precipitation was highly elevated near of the HgSb smelter and gradually decreased with distance from the smelter. After 12 months exposure, Sb concentrations in soil of experimental pots were increased by 1.2-8.5 times. The average atmospheric wet and dry deposition flux of Sb in the Xunyang HgSb mining district were 7.2 ± 6.9 μg m day and 2.1 ± 4.7 mg m day, respectively; the annual wet and dry deposition mass of Sb through HgSb mining activities were estimated to be 1.6 t y and 158 t y, respectively, indicating that dry deposition was the dominant pathway (98 ± 1.2%) for the removal of Sb from the atmosphere. Our results confirmed that the ongoing HgSb mining activities resulted to serious Sb contamination to terrestrial ecosystems, posing a potential threat to local residents in the Xunyang HgSb mining district.
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http://dx.doi.org/10.1016/j.envpol.2018.10.125DOI Listing
February 2019

Weir building: A potential cost-effective method for reducing mercury leaching from abandoned mining tailings.

Sci Total Environ 2019 Feb 12;651(Pt 1):171-178. Epub 2018 Sep 12.

Norwegian Institute for Water Research, Gaustadalleen 21, 0349 Oslo, Norway.

To mitigate mercury (Hg) pollution and reduce Hg downstream transportation, a weir was designed by a river system that had been inflicted by leachate from the slagheap of the Yanwuping Hg mine in Wanshan Hg mining area. A whole year monitoring of Hg species was conducted, and the efficiency of Hg reduction by the weir application was evaluated. The Hg concentrations in the river water were significantly higher in the wet season than in the dry season. Waterflow was confirmed to be the main driving factor for Hg mobilization and transportation, and an episode study revealed that most Hg was released in times of storms. Increased monitoring and preventive maintenance measures need to be taken on barriers in advance of storms. A large proportion of the total Hg (THg) and methylmercury (MeHg) is associated to particles. During the study period, approximately 412 g THg and 4.04 g total MeHg (TMeHg) were released from the YMM slagheap, of which 167 g THg and 1.15 g TMeHg were retained by the weir. Annually, 40.4% THg and 38.4% TMeHg was retained by the weir. Weir construction is considered as a potential cost-effective measure to mitigate Hg in river water and should be promoted and extended in the future after optimization.
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http://dx.doi.org/10.1016/j.scitotenv.2018.09.150DOI Listing
February 2019

Total mercury and methylmercury accumulation in wild plants grown at wastelands composed of mine tailings: Insights into potential candidates for phytoremediation.

Environ Pollut 2018 Aug 2;239:757-767. Epub 2018 May 2.

State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, PR China. Electronic address:

Total mercury (THg) and methylmercury (MMHg) were investigated in 259 wild plants belonging to 49 species in 29 families that grew in heavily Hg-contaminated wastelands composed of cinnabar ore mine tailings (calcines) in the Wanshan region, southwestern China, the world's third largest Hg mining district. The bioconcentration factors (BCFs) of THg and MMHg from soil to roots ([THg]/[THg], [MMHg]/[MMHg]) were evaluated. The results showed that THg and MMHg in both plants and soils varied widely, with ranges of 0.076-140 μg/g THg and 0.19-87 ng/g MMHg in roots, 0.19-106 μg/g THg and 0.06-31 ng/g MMHg in shoots, and 0.74-1440 μg/g THg and 0.41-820 ng/g MMHg in soil. Among all investigated species, Arthraxon hispidus, Eremochloa ciliaris, Clerodendrum bunge, and Ixeris sonchifolia had significantly elevated concentrations of THg in shoots and/or roots that reached 100 μg/g, whereas Chenopodium glaucum, Corydalisedulis maxim, and Rumex acetosa contained low values below 0.5 μg/g. In addition to the high THg concentrations, the fern E. ciliaris also showed high BCF values for both THg and MMHg exceeding 1.0, suggesting its capability to extract Hg from soils. Considering its dominance and the tolerance identified in the present study, E. ciliaris is suggested to be a practical candidate for phytoextraction, whereas A. hispidus is identified as a potential candidate for phytostabilization of Hg mining-contaminated soils.
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http://dx.doi.org/10.1016/j.envpol.2018.04.105DOI Listing
August 2018

Microbial community structure with trends in methylation gene diversity and abundance in mercury-contaminated rice paddy soils in Guizhou, China.

Environ Sci Process Impacts 2018 Apr;20(4):673-685

Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6036, USA.

Paddy soils from mercury (Hg)-contaminated rice fields in Guizhou, China were studied with respect to total mercury (THg) and methylmercury (MeHg) concentrations as well as Bacterial and Archaeal community composition. Total Hg (0.25-990 μg g-1) and MeHg (1.3-30.5 ng g-1) varied between samples. Pyrosequencing (454 FLX) of the hypervariable v1-v3 regions of the 16S rRNA genes showed that Proteobacteria, Actinobacteria, Chloroflexi, Acidobacteria, Euryarchaeota, and Crenarchaeota were dominant in all samples. The Bacterial α-diversity was higher in samples with relatively Low THg and MeHg and decreased with increasing THg and MeHg concentrations. In contrast, Archaeal α-diversity increased with increasing of MeHg concentrations but did not correlate with changes in THg concentrations. Overall, the methylation gene hgcAB copy number increased with both increasing THg and MeHg concentrations. The microbial communities at High THg and High MeHg appear to be adapted by species that are both Hg resistant and carry hgcAB genes for MeHg production. The relatively high abundance of both sulfate-reducing δ-Proteobacteria and methanogenic Archaea, as well as their positive correlations with increasing THg and MeHg concentrations, suggests that these microorganisms are the primary Hg-methylators in the rice paddy soils in Guizhou, China.
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http://dx.doi.org/10.1039/c7em00558jDOI Listing
April 2018

Chemical characterization and sources of PM at 12-hr resolution in Guiyang, China.

Acta Geochimica 2018 ;37(2):334-345

State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China.

The increasing emission of primary and gaseous precursors of secondarily formed atmospheric particulate matter due to continuing industrial development and urbanization are leading to an increased public awareness of environmental issues and human health risks in China. As part of a pilot study, 12-hr integrated fine fraction particulate matter (PM) filter samples were collected to chemically characterize and investigate the sources of ambient particulate matter in Guiyang City, Guizhou Province, southwestern China. Results showed that the 12-hr integrated PM concentrations exhibited a daytime average of 51 ± 22μg·m (mean ± standard deviation) with a range of 17-128μg·m and a nighttime average of 55 ± 32μg·m with a range of 4-186 μg·m. The 24-hr integrated PM concentrations varied from 15 to 157 μg·m-3, with a mean value of 53 ± 25 μg·m, which exceeded the 24-hr PM standard of 35μg·m set by USEPA, but was below the standard of 75μg·m, set by China Ministry of Environmental Protection. Energy-dispersive X-ray fluorescence spectrometry (XRF) was applied to determine PM chemical element concentrations. The order of concentrations of heavy metals in PM were iron (Fe) > zinc (Zn) > manganese (Mn) > lead (Pb) > arsenic (As) > chromium (Cr). The total concentration of 18 chemical elements was 13 ± 2 μg·m, accounting for 25% in PM, which is comparable to other major cities in China, but much higher than cities outside of China.
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http://dx.doi.org/10.1007/s11631-017-0248-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6800720PMC
January 2018

Barium concentrations and speciation in surface waters collected from an active barium mining area in Guizhou Province, southwestern China.

Environ Sci Pollut Res Int 2018 Mar 28;25(8):7608-7617. Epub 2017 Dec 28.

State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, 99 Lincheng West Rd., Guiyang, 550081, People's Republic of China.

Barium (Ba) is a toxic element and can cause serious health effects. Humans have experienced increased exposure to Ba due to its intensive usage in industrial areas and daily life. Anthropogenic activities of Ba mining and the manufacture of Ba containing products introduce the element into surrounding areas, posing environmental concerns. Concentrations of total Ba (TBa) and dissolved Ba (DBa) in water samples collected from active Ba mines in Tianzhu, east Guizhou Province, southwestern China were measured to show the regional dispersion of Ba contamination. Aqueous Ba species in water were calculated using the PHREEQC program. The results showed that TBa and DBa concentrations ranged from 6.7 to 483.1 μg/L and from 7.5 to 222.7 μg/L, respectively. TBa concentrations presented a high average value of 126.6 μg/L and greatly exceeded the reported common value of 10 μg/L Ba in surface water set by the Ministry of Environment Protection of China. PHREEQC results indicated that Ba species in water were present as Ba, BaSO, BaHCO, BaCO, and BaOH. The distribution of Ba species in water is controlled by pH and total organic carbon (TOC), and the lower pH (pH < 7) the higher the dissolved fractions. The log K values (K , dissolved-particulate distribution coefficients) varied from 2.41 to 6.32. Significant correlations were observed among Ba and K, Na, Cl, NO, with Pearson correlation coefficients of 0.425, 0.531, 0.853, 0.612, and 0.329, respectively (p < 0.01). Elevated Ba concentrations in water indicated that the Ba contamination and its distribution pattern in local aquatic ecosystems are derived from Ba mining sites in the Tianzhu area.
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http://dx.doi.org/10.1007/s11356-017-0963-5DOI Listing
March 2018

The local impact of a coal-fired power plant on inorganic mercury and methyl-mercury distribution in rice (Oryza sativa L.).

Environ Pollut 2017 Apr 28;223:11-18. Epub 2017 Jan 28.

State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China. Electronic address:

Emission from coal-fired power plants is one of the major anthropogenic sources of mercury (Hg) in the environment, because emitted Hg can be quickly deposited nearby the source, attention is paid to the effects of coal-burning facilities on levels of toxic methyl-mercury (MeHg) in biota near such sources. Since rice is an agricultural crop that can bio-accumulate MeHg, the potential effects of a large Hg-emitting coal-fired power plant in Hunan Province, China on both inorganic Hg (Hg(II)) and MeHg distributions in rice was investigated. Relatively high MeHg (up to 3.8 μg kg) and Hg(II) (up to 22 μg kg) concentrations were observed in rice samples collected adjacent to the plant, suggesting a potential impact of Hg emission from the coal fired power plant on the accumulation of Hg in rice in the area. Concentrations of MeHg in rice were positively correlated with soil MeHg, soil S, and gaseous elemental Hg (GEM) in ambient air. Soil MeHg was the most important factor controlling MeHg concentrations in rice. The methylation of Hg in soils may be controlled by factors such as the chemical speciation of inorganic Hg, soil S, and ambient GEM.
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http://dx.doi.org/10.1016/j.envpol.2016.11.042DOI Listing
April 2017

Epidemiology and Risk Factors of Functional Constipation in Pregnant Women.

PLoS One 2015 24;10(7):e0133521. Epub 2015 Jul 24.

Department of Gynaecology and Obstetrics, Tongji Hospital, Tongji University, Shanghai, China.

Aim: To understand the prevalence of functional constipation in pregnant women and to analyze the impact of its risk factors.

Methods: We searched hospital databases for women who were 37-41 weeks pregnant (1698 cases) from July 2012 to January 2014 in four hospitals in Shanghai. We reviewed factors including general data, living and eating habits, psychological history, past history of defecation in the 6 months before pregnancy and defecation after pregnancy. Data were analyzed using SPSS software.

Results: Pregnant women who were more than 35 years old, with a pre-pregnancy body mass index >24, who were highly educated and employed in a sedentary occupation, showed a higher prevalence of functional constipation. Multivariate logistic regression analysis indicated that the prevalence of functional constipation among pregnant women was related to age, pre-pregnancy body mass index, diet, exercise, occupation, psychological factors, threatened abortion in early pregnancy and constipation history.

Conclusion: The prevalence rate of functional constipation in pregnant women was significantly higher than in the general population.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0133521PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4514689PMC
May 2016
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