Average Mercury Concentration Research Articles

A Study of Mercury Pollution in Water, Sediment, and Lais (Kryptopterus) Fish in the Melawi Watershed

Mercury (Hg) is a heavy metal that is very dangerous and toxic. Melawi River, a river with a length of 471 m, passes through four districts namely Menukung, Ella Hulu, Ella Hilir, and Nanga Pinoh which are the main water transportation routes in Melawi regency. This research was aimed to determine the concentration of mercury in water, sediments and Lais (Kryptopterus) fish of mercury bioconcentration factors, and the safety level of consumption the contaminated Lais (Kryptopterus) fish. The mercury measurement using Atomic Absorption Spectroscopy (AAS) showed that the average concentration of mercury found in the water was 1.80×10 -4 ppm, sediments 1.33×10 -2 ppm, and Lais fish 0.291 ppm. Meanwhile, the average bioconcentration factor (BCF) of mercury in Lais fish was 1.677 ppm. The maximum daily consumption of Lais fish that were safe for the community consumption at the Melawi watershed was 0,026 kg /day for adults and 0.006 kg/day for the children.

Determination of Mercury Content in Surface Waters Using an Environmentally Non-Toxic Terminating Electrolyte

The paper presents results of the research on the dynamics of changes in the concentration of mercury in surface waters. The importance of mercury as an environmental pollutant results from specific properties of this metal, many sources of contamination, volatility, mobility, stability and high toxicity of its specific chemical forms. Samples of surface water collected from three rivers: the Bug, the Liwiec and the Muchawka were analysed. The Muchawka River flows into the Liwiec River, which in turn is a tributary of the Bug River. The technique of isotachophoresis was employed, using a solution of a biodegradable and environmentally non-toxic derivative of electrostatically stabilised silanates as the terminating electrolyte. The highest average mercury concentration of 0.89 μg/dm3 was determined in water samples collected from the Bug River in January, whereas the lowest concentration of 0.42 μg/dm3 was recorded in water collected from the Muchawka River in September.

Remediation of brownfields contaminated by organic compounds and heavy metals: a bench-scale test of a sulfur/vermiculite sorbent for mercury vapor removal.

In this study, we report for the first time a novel type of sorbent that can be used for mercury adsorption from the air-based off-gasses-vermiculite impregnated with alkali polysulfides and thiosulfates. In contrast to other sorbents, vermiculite exhibits superior thermal stability in air and low adsorption capacity for organic vapors. This allows for a more favorable design of the soil remediation unit-direct coupling of thermal desorber with catalytic oxidizer using air as a carrier gas. In the bench-scale test at 180 °C, the sulfur/vermiculite sorbent exhibited significantly higher efficiency for the adsorption of mercury vapor from the off-gasses than the commercial sulfur/activated carbon sorbent at its highest operating temperature (120 °C). The average mercury concentration in the adsorber off-gas decreased from 1.634 mg/m3for the sulfur/activated carbon to 0.008 mg/m3 achieved with impregnated vermiculite. The total concentration of organic compounds in the soil after thermal desorption was below the detection limit of the employed analytical method.

Spatiotemporal distribution and long-range transport of atmospheric speciated mercury at three remote islands in Taiwan Strait and South China Sea

This study investigated the spatiotemporal distribution and long-range transport of atmospheric speciated mercury at three remote islands in the Taiwan Strait and the South China Sea. The field measured speciated mercury in the atmosphere was then correlated with criteria air pollutants and meteorological parameters. Air mass trajectory simulation and global fire map were further used to explore potential source regions. Field measurement results showed that the yearly average concentration of gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM), and particulate mercury (PHg) in the target seas were 2.09±0.61 ng/m3, 20.93±7.81 pg/m3, and 150±70 pg/m3, respectively. The highest GEM, GOM, and PHg concentrations were always observed at the Penghu Islands in all seasons. Total gaseous mercury (TGM = GEM+GOM) was the dominant mercury species in the atmosphere, apportioned as 92.46– 96.17% TGM and 3.83– 8.70% PHg, respectively. The seasonal variation of GEM and PHg concentrations were ordered as: spring>winter>fall>summer, while GOM showed different seasonal trends. The lowest concentration of total atmospheric mercury (TAM) was observed in summer since clean air masses were blown mainly from the Pacific Ocean and the Philippines Islands. Air masses came mainly from Central China, North China, and Japan/Korea with the TAM concentrations of 2.90 ± 0.63, 2.68 ± 0.65, and 2.16 ± 0.45 ng/m3, and the frequencies of 19.3%, 18.3%, and 14.3%, respectively. Atmospheric speciated mercury positively correlated to O3, PM2.5, SO2, and NOx, implying that they were consistently emitted from anthropogenic sources in the upwind polluted regions. Overall, the concentrations of atmospheric speciated mercury measured at the three remote islands in the Taiwan Strait and the South China Sea were commonly higher than those in the United States and European countries, but lower than those in Asian countries, with the exception of Japan.

Anthropogenic Contaminants and Histopathological Findings in Stranded Cetaceans in the Southeastern United States, 2012–2018

Anthropogenic contaminants in the marine environment often biodegrade slowly, bioaccumulate in organisms, and can have deleterious effects on wildlife immunity, health, reproduction, and development. In this study, we evaluated tissue toxicant concentrations and pathology data from 83 odontocetes that stranded in the southeastern United States during 2012–2018. Mass spectrometry was used to analyze blubber samples for five organic toxicants (atrazine, bisphenol-A, diethyl phthalates, nonylphenol monoethoxylate [NPE], triclosan), and liver samples were analyzed for five non-essential elements (arsenic, cadmium, lead, mercury, thallium), six essential elements (cobalt, copper, manganese, iron, selenium, zinc) and one toxicant mixture class (Aroclor1268). Resultant data considerably improve upon the existing knowledge base regarding toxicant concentrations in stranded odontocetes. Toxicant and element concentrations varied based on animal demographic factors including species, sex, age, and location. Samples from bottlenose dolphins had significantly higher average concentrations of lead, manganese, mercury, selenium, thallium, and zinc, and lower average concentrations of NPE, arsenic, cadmium, cobalt, and iron than samples from pygmy sperm whales. In adult female bottlenose dolphins, average arsenic concentrations were significantly higher and iron concentrations were significantly lower than in adult males. Adult bottlenose dolphins had significantly higher average concentrations of lead, mercury, and selenium, and significantly lower average manganese concentrations compared to juveniles. Dolphins that stranded in Florida had significantly higher average concentrations of lead, mercury, and selenium, and lower concentrations of iron than dolphins that stranded in North Carolina. Histopathological data are presented for 72 animals, including microscopic evidence of Campula spp. and Sarcocystis spp. infections, and results of Morbillivirus and Brucella spp. molecular diagnostic testing. Sublethal cellular changes related to toxicant exposure in free-ranging odontocetes may lead to health declines and, in combination with other factors, may contribute to stranding.

Mercury Pollution Linked To Gold Panning In DR Congo: Contamination Of Aquatic Systems And Health Impact On Residents

The interactions between selenium (Se) and mercury (Hg) were assessed on fish, crabs, and molluscs to assess the risks to public health associated with dietary exposure to mercury from their consumption. To this end, mass concentrations of mercury and selenium have been determined in the edible tissues of three species of fish, in crabs and molluscs taken from the rivers of the gold zones of Fizi in South Kivu in the Democratic Republic of Congo. We found values ​​greater than 1 µg/g Hg in all fish samples regardless of the river, but also that the Kimbi River was the most polluted with an average mercury content of about 5 µg/g. Crabs and molluscs also had Hg values ​​greater than 1.

ВЛИЯНИЕ ПРИРОДНЫХ ФАКТОРОВ НА СОДЕРЖАНИЕ РТУТИ В ОЗЕРАХ СЕВЕРА ЗАПАДНОЙ СИБИРИ

Актуальность исследования обусловлена тем, что ртуть участвует в глобальном планетарном биогеохимическом цикле и входит в пищевые цепи с накоплением в организмах хищных видов животных и у коренного населения. В отношении к территории Западной Сибири информация о содержании ртути в озерах не достаточно полная, а обобщения сделаны на малых выборках, что делает актуальным фоновые изучения содержания ртути в среднетаежных озерах на репрезентативной выборке. Целью исследования является анализ и обобщение фоновых мониторинговых наблюдений, как за общим содержанием ртути донных отложений, так и её содержанием в поверхностных водах озер, в зависимости от природных факторов в условиях средней тайги в пределах Ханты-Мансийского автономного округа. Объект: фоновая концентрация растворенной Hg и ртути в донных отложениях озер. Изучено 95 озер, 322 пробы донных отложений, отобранных в разное время. Методы: атомно-адсорбционная спектрометрия (метод «холодного пара») определения ртути в аккредитованных лабораториях в соответствии с методическими рекомендациями. Использованы данные фонового экологического мониторинга с 2007 по 2011 гг. Результаты. Средняя фоновая концентрация ртути в донных отложениях составляет 0,046±0,012 мг/кг, растворенной ртути – 0,025±0,014 мг/кг. Наибольшая концентрация Hg выявлена в элювиальной и трансэлювиальной позициях, наименьшая – в супераквальных ландшафтах. Концентрация Hg имеет максимальное значение в озерково-грядово-мочажинном комплексе торфяных болот, а самое низкое – в донных отложениях озер на минеральных почвах. Наблюдается тенденция увеличения концентрации ртути в донных отложениях озер от зоны тундры, северной тайги до подзоны средней тайги. Но нарастает заболоченность территорий с юга на север, что способствует увеличению содержания ртути в донных отложениях озер (R=0,4). Отмечается увеличение растворенной ртути в озерах с запада на восток (по долготе) (R=0,6). Оценка динамики изменения содержания ртути в донных отложениях позволяет заключить, что в зимний период содержание ртути выше по сравнению с летним периодом. Концентрация растворенной ртути возрастает с запада на восток, но ртуть донных отложений этой закономерности не соответствует.

Assessment of Mercury Contamination in Perch Species in the Southern Caspian Sea.

Mercury is a heavy metal that has caused concern regarding the health of fish and of those who consume them. In this research, the concentrations of mercury in the muscle tissues of zander and European perch from Anzali were measured using a graphite furnace atomic absorption spectrometer (GFAAS). The average concentrations of mercury in the muscle of the zander and European perch were 244 and 105µg/kg dry weight, respectively. A nonsignificant positive correlation between morphological parameters and mercury values was observed for both species (P > 0.05). The concentrations of mercury accumulated in the two fish species were lower than the values recorded in most similar studies, and were below the permissible limit provided by the National Iranian Standards Organization, FAO, WHO, US EPA, EC, and US FDA. In addition, the HQ value was less than one. Therefore, in general, this research indicates that exposure to mercury does not threaten the health of these species and their consumers.

Elevated Mercury in the Water of the Angara River Source: A Response to Geodynamic Impacts and Strong Earthquakes

The mercury concentrations in the water of the Angara River Source (runoff of Lake Baikal) are compared to temporal distributions of earthquakes of various magnitudes that occurred at various distances from the water-sampling site. It is established that all significant mercury maxima in the water are preceded by strong geodynamic impacts in the Baikal Rift Zone. The predictive estimates of the average annual mercury concentration indicate a possible significant increase in its levels in local areas of fluid discharge of faults under an intense geodynamic impact. The opening of deep faults during strong movements is expected to lead to decompression with mercury degassing and rapid rise to the surface along the fault zones.

Total mercury and methylmercury in Chinese rice and dietary exposure assessment

ABSTRACT Total mercury levels and methylmercury levels were investigated for various grain parts (whole rice, rice husk, brown rice, polished rice, and bran) of 507 rice samples from 15 main rice-producing areas of China. The average total mercury contents in brown rice samples and polished rice samples were 4.2 and 3.3 μg/kg, respectively, the percentages exceeding the national standard limit were 0.59% and 0.39%, respectively. The average methylmercury levels were 2.9 and 2.4 μg/kg in brown rice and polished rice, respectively. The order of total mercury contents in different parts of rice was bran > brown rice > whole rice > rice husk > polished rice, and the order for methylmercury was bran > brown rice > whole rice > polished rice > rice husk. Total mercury intakes and methylmercury intakes were estimated for the Chinese population and the associated health risks were assessed.

Mercury accumulation in plants from contaminated arable lands in Eastern Slovakia.

Contamination of soil by mercury poses several risks to human health through consumption of fruits and vegetables. In Slovakia, a high concentration of mercury is found in the soil of the Central Spiš region. The objective of the study is to measure the mercury concentrations in the parts of selected plant species and trees growing within 100 meters of a former ore processing facility. A total of 24 samples of plants, 20 samples of parts of needle-leaved trees and 9 samples of parts of broad-leaved trees were collected from soils with a high concentration of mercury. The concentration was measured by atomic absorption spectrometry in different parts of the plants: leaves - 18 species, roots - 15 species, stems - 11 species, flowers - 7 species), and different parts of trees (crust - 8 species, branches - 8 species, needles - 5 species, cones - 5 species, leaves - 3 species). The concentrations of mercury in the soils taken at a depth of 0.25 m exceeded the maximum allowed levels more than 50-times. Potatoes, parsley and carrots from these soils exceeded the maximum allowed mercury levels 6-times, 5-times and twice, respectively. The average concentrations of mercury in the roots of 2-year onions exceeded the limit more than 50-times. The flowers of cornflower contain 18.20 mg*kg -1 , leaves of dandelion 10.61 mg*kg -1 and roots of plantain 6.80 mg*kg -1 of mercury. Regarding trees, the highest concentrations were found in the branches of juniper and leaves of aspen - more than 1 mg*kg -1. The systematic monitoring of mercury is still very important, since it was found that the end of ore processing does not solve the issue of contamination in the Central Spiš region. Therefore, the consumption of fruits and vegetables from the areas of former ore processing facilities is not recommended.

Contaminación por mercurio en árboles de carpes (Carpinus betulus) en espacios verdes en el área del parque industrial (Irán)

El mercurio es un metal tóxico que puede acumularse en los órganos de las plantas en grandes cantidades ocasionando toxicidad a los humanos. Carpinus betulus es una especies de los bosques mixtos hircanos del Caspio. En esta investigación, se estudió la cantidad de mercurio que pueden absorber los árboles de carpes del ambiente. Veinticinco árboles fueron seleccionados al azar, las distancias entre árboles fueron de 10 a 15 m en un parque industrial en el norte de Irán. De cada árbol seleccionado, se cosecharon 15 g de hojas y 15 g de raíz con tijeras hortícolas, y 15 g de tierra a partir de 30 cm de profundidad. Se seleccionaron cuatro estaciones cerca de la fábrica de acero. Se seleccionó una estación de control ubicada a 2 km de la fábrica de acero y se ubicaron tres estaciones cerca de la fábrica de acero. Las muestras de hojas, tierra y raíces se prepararon y codificaron, se colocan en sobres de papel y se transfirieron al laboratorio. La cantidad de mercurio en las muestras de plantas se preparó mediante digestión en seco con espectroscopía de absorción atómica. Para comparar el efecto de la concentración de mercurio en la hoja y la raíz, se utilizó la prueba de Tukey. La concentración promedio de mercurio en el suelo fue de 0.96 mg/kg, en la raíz 0.551 mg/kg y en la hoja 0.28 mg/kg. Se observó que con el aumento de mercurio la cantidad de clorofila en la hoja disminuye. Se puede concluir que la cantidad de acumulación de metales mercurio en el árbol Carpinus betulus es adecuada para absorber la contaminación del mercurio de la contaminación del suelo.

Investigation of Mercury Concentration and Existence Form in River Waters in Niigata Prefecture

The mercury concentration of river waters in Niigata Prefecture was studied for regional distribution, fluctuation factors, and speciation. We investigated 11 rivers in Niigata Prefecture four times a year. As a result, average concentrations of total mercury (T-Hg), and dissolved T-Hg in the river waters were 1.7 ng/L, and 0.29 ng/L, respectively. The average ratio of dissolved alkyl mercury concentrations to dissolved T-Hg concentrations were about 15%. The dissolved T-Hg concentrations had no observable regional differences. On the other hand, the T-Hg concentration in suspended solids (SS) was highest in the Seki River. The average T-Hg concentration in SS (SS-Hg) in the Seki River was 0.34 μg/g, whereas those in the other rivers ranged from 0.11 to 0.23 μg/g. The factor that increased SS-Hg concentration in the Seki River is considered to be the sediment originated from volcano. We investigated long-term fluctuations of T-Hg concentration in the Shinkawa River during April 2017 to March 2019. As a result, the average concentrations of dissolved T-Hg and particulate T-Hg in the Shinkawa River were 0.40 ng/L and 2.3 ng/L, respectively. The particulate T-Hg concentration was highly correlated with SS concentration.

Mercury concentration in shark meat from traditional markets of Gyeongsangbuk-do, South Korea.

BackgroundAlthough unusually high levels of blood mercury have been reported in the North Gyeongsang Province (Gyeongsangbuk-do), mercury contents from shark meat distributed in this region have not been assessed yet. Thus, this study aims to identify the hazard by evaluating the mercury contents of the shark meat sold in the traditional market of Gyeongsangbuk-do.MethodsThe shark meat in the form of muscle meat was obtained from 15 traditional markets of Gyeongsangbuk-do in the summer and winter of 2013. Out of 105 samples in total, 49 were collected in the summer and 56 in the winter. The total mercury concentration was measured by the combustion-gold amalgamation method using an automatic mercury analyzer (Milestone DMA-80, Milestone).ResultsThe average mercury concentration of shark meat was 2.29 ± 1.77 µg/g, ranging between 0.06–8.93 µg/g with a geometric mean of 1.44 µg/g, which is higher than those reported in many countries. The mercury concentration in 77 of 105 shark meat samples exceeded 1 µg/g. Mercury concentration ranged between 0.09–8.93 µg/g (geometric mean: 1.45) in the summer and 0.06–6.73 µg/g (geometric mean: 1.48) in the winter.ConclusionsShark meat sold in the market contained a substantial amount of mercury. This suggests that it is difficult to reduce mercury intake by simply strengthening the standard level of mercury concentration in shark meat. Therefore, it is need to communication and awareness programs with consumers about hazardous effects of mercury inherent in shark meat.

Analysis of electrocardiogram and blood related indicators in workers occupationally exposed to mercury in Jiangsu Province from 2016 to 2018

Objective: To investigate the health status of occupational mercury workers and reveal the effects of mercury exposure on the cardiovascular system. Methods: In June 2019, a total of 2651 mercury workers participated in the occupational health examination between 2016-2018 from a thermometer manufacturing plant and a fluorescent lamp manufacturing plant were included in this study. Then, they were divided into a high-level mercury exposure group (425 workers whose urine mercury concentration >35 μg/g creatinine) and a low-mercury mercury exposure group (2226 workers whose urinary mercury concentration <35 μg/g creatinine) . Mercury concentration in the workplace was also detected. Finally, the results of electrocardiogram (ECG) , blood routine, blood biochemistry and other physical examinations were analyzed. The measurement data of age and exposure years were analyzed by test. Urinary mercury and blood parameters were analyzed by Mann-Whitney nonparametric test. Chi-square test was used for the analyses of gender, ECG abnormality rate and other categorical data. Results: The 8-hour weighted average allowable concentration (CTWA) of mercury in the workplace of high-exposure group was 0.002 2-0.152 mg/m(3). The abnormal rate of ECG in the high-exposed group (29.6%) was higher than that in the low-exposure group (10.1%) in 2018 (P<0.01) . Compared with the low-exposure group, the WBC of the high-exposure group from 2016 to 2018 was increased, with statistically significance (P<0.05) ; the RBC of the high-exposure group in 2016 and 2017 was decreased, with statistically significance (P<0.01) ; the total bilirubin concentration in the high-exposure group was decreased from 2016 to 2018, with statistically significance (P<0.05) . Conclusion: Long-term exposure to high concentration of mercury in the workplace may influence cardiovascular system. Therefore, engineering protection and individual protection should be implemented well.

Macrobrachium amazonicum (Crustacea, Decapoda) Used to Biomonitor Mercury Contamination in Rivers.

Open-air landfill's may be are considered as a potential source of human environmental exposure to chemical substances such as, polycyclic aromatic hydrocarbons and toxic metals. Due to possible availability of mercury in the environment caused by open landfill emissions, this study evaluates the spatiality and seasonality of macroinvertebrates, in particular shrimps (Macrobrachium amazonicum), exposure to mercury (Hg). Information regarding Hg accumulation in this crustacean may be important for the development of public policies aiming conservation and preservation of ecosystems surrounding landfills in Amazon, and around the world. Sampling occurred quarterly in the following months: November/2015; February/2016; May/2016 and; August/2016. In each of these months, three points were selected: P1, P2 and P3. The samples were processed via acid digestion and the quantification of metal was performed by inductively coupled plasma mass spectrometry. The average concentration of total mercury (T-Hg) was 24.565 ± 6.610µgkg-1 wet weight, with minimum and maximum limits of 12.742 ± 11.367 (P3) and 35.509 ± 14.761µgkg-1 wet weight (P1) in November/2015 and August/2016, respectively. The concentration of total mercury (T-Hg) in shrimps was different between points (p = 0.004) and months (p = 0.000). The T-Hg concentrations were significantly higher in May and August 2016, which corresponds to the dry season. The presence of landfills promotes large accumulation of T-Hg in the aquatic biota and represents a risk to human health. However, seasonal changes in T-Hg levels were observed. In the wettest period, bioconcentration factor levels decrease in aquatic organisms.

Mercury Content in Central and Southern Adriatic Sea Sediments in Relation to Seafloor Geochemistry and Sedimentology.

Mercury contents were determined in surface sediments from the Central and Southern Adriatic Sea to gain insight into the processes, factors, and variables affecting its distribution. Mercury concentration was measured by thermal decomposition amalgamation atomic absorption spectrometry in samples collected by box-corer from Ancona to Santa Maria di Leuca during the CNR-PERTRE cruise (16/9-4/10/2016). Sediments were also evaluated for chemical-physical parameters (pH, Eh), biogeochemical composition (total carbon, inorganic carbon, total organic carbon, organic matter) and grain size. The average mercury concentration in the Adriatic Sea sediment was 0.053 mg/Kg (d.w.), range 0.011–0.12 mg/Kg (d.w.). Mercury content was mainly affected by grain size and organic matter (OM) distribution, whereas anthropic factors exerted a limited influence. Concentrations followed the distribution of sediment types (clay > silt > sand) due to Adriatic Sea hydrodynamics and were well below the regulatory limits in all samples.

The “Mercury breathing” of the Baikal rift zone according to the study of tree annual rings (on the example of Tunkinskaya depression)

The work evaluates the general distribution of mercury in the rings of trees of the Tunkinskaya depression (the Republic of Buryatia, the national park “Tunkinsky”).The used methods of dendrochronology and dendrogeochemistry allow us to estimate the contribution of different factors affecting the quality of the environment and ascertain the history of natural components pollution. In this research, the phenomenon of natural degassing of mercury in the Baikal Rift Zone (BRZ) according to the study of annual tree rings is considered. The BRZ covers 13 large parallel lobes separated from each other by high mountain ridges and bridges. Geodynamic activity of the zone is shown by contrast relief transformation and high seismicity. High tectonic and seismic activity causes the “output” of mercury to the surface. The dynamics of Hg concentration changes in the Tunkinskaya lobe for more then half a century was observed. The average mercury content in the sample was 7 ng/g, the max – 35ng/g. The max concentration is detected in areas of the territory associated with free tectonic faults. The connection between the peaks of high mercury concentration in wood and periods of major earthquakes was detected.

Studying absorbance properties and mercury remediation capabilities of gold–graphene oxide–iron oxide (Au–GO–Fe3O4) nanoparticle systems

Mercury pollution is a rampant problem in many economically significant Philippine freshwater ecosystems. Communities dependent on these freshwater sources are therefore at risk for exposure to harmful levels of mercury. Various formulations of a novel gold–graphene oxide–iron oxide (Au–GO–Fe3O4) hybrid nanoparticle system were created and subjected to UV–Vis spectroscopy to determine optimal formulations that would best serve as potential substrates for Surface-Enhanced Raman Spectroscopy (SERS) detection of mercury. Optimal formulations of Au–GO–Fe3O4 were also introduced into mercury-polluted environments to evaluate its ability to remove mercury from both water and biological tissues. Spectroscopic analysis revealed that Fe3O4-rich formulations of Au–GO–Fe3O4 had the greatest potential to boost Raman signal intensities of mercury due to red shifting of absorbance peaks and overall increased absorbance across visible wavelengths resulting in the inclusion of greater areas underneath absorbance peaks. Mercury remediation experiments likewise demonstrated Au–GO–Fe3O4 to significantly reduce average concentrations of mercury from 1.67 to 0.82 ppm in polluted water samples – corresponding to a mercury removal efficiency of 50.9% and a mercury adsorption capacity of 5.89 mg/g. The results highlight the viability of Au–GO–Fe3O4 to function as both substrate for SERS detection of mercury and as effective adsorbent for mercury remediation.

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

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-3 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-2 y-1 and 10 t y-1, 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-1) in soil were observed in February. Concentrations as high as 643 μg kg-1 THg and 13 μg kg-1 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.