Mercury Levels Research Articles

Assessing the Risk of Heart Attack: A Bayesian Kernel Machine Regression Analysis of Heavy Metal Mixtures.

The assessment of heavy metals' effects on human health is frequently limited to investigating one metal or a group of related metals. The effect of heavy metals mixture on heart attack is unknown. This study applied the Bayesian kernel machine regression model (BKMR) to the 2011-2016 National Health and Nutrition Examination Survey (NHANES) data to investigate the association between heavy metal mixture exposure with heart attack. 2972 participants over the age of 20 were included in the study. Results indicate that heart attack patients have higher levels of cadmium and lead in the blood and cadmium, cobalt, and tin in the urine, while having lower levels of mercury, manganese, and selenium in the blood and manganese, barium, tungsten, and strontium in the urine. The estimated risk of heart attack showed a negative association of 0.0030 units when all the metals were at their 25th percentile compared to their 50th percentile and a positive association of 0.0285 units when all the metals were at their 75th percentile compared to their 50th percentile. The results suggest that heavy metal exposure, especially cadmium and lead, may increase the risk of heart attacks. This study suggests a possible association between heavy metal mixture exposure and heart attack and, additionally, demonstrates how the BKMR model can be used to investigate new combinations of exposures in future studies.

An Innovative Approach for Elemental Mercury Adsorption Using X-ray Irradiation and Electrospun Nylon/Chitosan Nanofibers.

A novel approach was proposed, utilizing an electrical field and X-ray irradiation to oxidize elemental mercury (Hg0) and encapsulate it within a nanofibrous mat made of Polyamide 6/Chitosan. The X-rays contributed significantly to the conversion of Hg0 into Hg+ by producing electrons through the photoionization of gas molecules. The positive and negative pole electrodes generated an electric field that exerted a magnetic force, resulting in the redirection of oxidized elemental mercury towards the negative pole electrode, which was coupled with a Polyamide 6/Chitosan nanofiber mat. The evaluation of the Polyamide 6/Chitosan nanofibers exposed to oxidized mercury showed that the mercury, found in the steam of a specially designed filtration device, was captured in two different forms. Firstly, it was chemically bonded with concentrations ranging from 0.2 to 10 ng of Hg in total. Secondly, it was retained on the surface of the Polyamide 6/Chitosan nanofibers with a concentration of 10 microg/m3 of Hg per minute. Nevertheless, a concentration of 10 microg/m3 of mercury is considered significant, given that the emission levels of mercury from each coal power plant typically vary from approximately 4.72 to 44.07 microg/m3. Thus, this research presents a viable approach to reducing mercury emissions from coal-fired power plants, which could result in lower operational expenses and less secondary environmental effects.

Mitigating the effects of PVC microplastics and mercury stress on rye (Secale cereale L.) plants using zinc oxide−nanoparticles

AbstractIn present years, the use of zinc oxide nanoparticles (ZnO‐NPs) has received great attention due to increase in the nutrient accumulation by plants for improving the capability of agronomic Zn biofortification. Although, the emergence of polyvinyl chloride (PVC) microplastics (MPs) as pollutants in agricultural soils is increasingly alarming, presenting significant toxic threats to soil ecosystems. The present work studied the impact of different levels of PVC‐MPs, namely 0 (no PVC‐MPs), 2, and 4 mg L−1, along with mercury (Hg) levels of 0 (no Hg), 10, and 25 mg kg−1 in the soil, while concurrently applying with ZnO‐NPs at 0 (no ZnO‐NPs), 50, and 100 μg mL−1 to rye (Secale cereale L.) plants. This study aimed to examine plant growth and biomass, photosynthetic pigments and gas exchange characteristics, oxidative stress indicators, and the response of various antioxidants (enzymatic and non‐enzymatic) and their specific gene expression, proline metabolism, the ascorbic acid–dehydroascorbic acid (AsA–GSH) cycle, and cellular fractionation in the plants. The research outcomes indicated that elevated levels of PVC‐MPs and Hg stress in the soil notably reduced plant growth and biomass, photosynthetic pigments, and gas exchange attributes. However, PVC‐MPs and Hg stress also induced oxidative stress in the roots and shoots of the plants by increasing malondialdehyde (MDA), hydrogen peroxide (H2O2), and electrolyte leakage (EL) which also induced increased compounds of various enzymatic and non‐enzymatic antioxidants, and also the gene expression and sugar content. Furthermore, a significant increase in proline metabolism, the AsA–GSH cycle, and the pigmentation of cellular components was observed. Although, the application of ZnO‐NPs showed a significant increase in plant growth and biomass, gas exchange characteristics, enzymatic and non‐enzymatic compounds, and their gene expression and also decreased oxidative stress. In addition, the application of ZnO‐NPs enhanced cellular fractionation and decreased the proline metabolism and AsA–GSH cycle in S. cereale plants. These results open new insights for sustainable agriculture practices and hold immense promise in addressing the pressing challenges of heavy metal contamination in agricultural soils.

Analysis of Cadmium, Mercury and Lead in oysters (Crassostrea virginica) in a protected area of southeastern Mexico associated with the risk to human health

BackgroundMetal pollution is a problem in many parts of the world. These metals can be harmful when they exceed the recommended limits. This study aimed to assess the levels of cadmium (Cd), mercury (Hg), and lead (Pb) in the tissues of oysters (Crassostrea virginica) within a protected area in southeastern Mexico. Additionally, the study aimed to conduct a risk analysis for human health associated with these metals. It is anticipated that the observed metal levels will be lower compared to prior studies, thereby not posing a significant risk to the local population. MethodsThe tissue of oyster samples was treated under the techniques of the Official Mexican Standards and analyzed using atomic absorption spectroscopy. The metal concentrations were used to calculate the estimated daily intakes (EDI), target hazard quotients (THQ), hazard index (HI), and target cancer risks (TR), for children and adults. ResultsMaximum values of Cd (1.99 μg g−1), exceeded the permissible limits of the Official Mexican Standards. Pb (0.99 μg g−1) and Hg (0.64 μg g−1) are within the recommended limits. The THQ and HI for Cd, Pb, and Hg were lower than the United States Environmental Protection Agency (US-EPA) criteria. ConclusionsBased on our results, whether oyster (Crassostrea virginica) consumption is recommended in adults and reducing consumption in children; to diminish the risk of exposure to Cd, Pb, and Hg.

Mercury in aquatic ecosystems of two indigenous communities in the Piedmont Ecuadorian Amazon: evidence from fish, water, and sediments

Mercury is a highly toxic element present in water, soil, air, and biota. Anthropogenic activities, such as burning fossil fuels, mining, and deforestation, contribute to the presence and mobilization of mercury between environmental compartments. Although current research on mercury pathways has advanced our understanding of the risks associated with human exposure, limited information exists for remote areas with high diversity of fauna, flora, and indigenous communities. This study aims to deepen our understanding of the presence of total mercury in water, sediments, and fish, within aquatic ecosystems of two indigenous territories: Gomataon (Waorani Nationality) and Sinangoé (Ai´Cofán Nationality) in the Ecuadorian Amazon. Our findings indicate that, for most fish (91.5%), sediment (100%) and water (95.3%) samples, mercury levels fall under international limits. For fish, no significant differences in mercury levels were detected between the two communities. However, eight species exceeded recommended global limits, and one surpassed the threshold according to Ecuadorian legislation. Piscivore and omnivore fish exhibited the highest concentrations of total mercury among trophic guilds. Only one water sample from each community’s territory exceeded these limits. Total mercury in sediments exhibited greater concentrations in Gomataon than Sinangoé. Greater levels of mercury in sediments were associated with the occurrence of total organic carbon. Considering that members of the communities consume the analyzed fish, an interdisciplinary approach, including isotopic analysis, methylmercury sampling in humans, and mercury monitoring over time, is imperative for a detailed risk assessment of mercury exposure in Amazonian communities.

Associations of mixed metal exposure with chronic kidney disease from NHANES 2011–2018

Metals have been proved to be one of risk factors for chronic kidney disease (CKD) and diabetes, but the effect of mixed metal co-exposure and potential interaction between metals are still unclear. We assessed the urine and whole blood levels of cadmium (Cd), manganese (Mn), lead (Pb), mercury (Hg), and renal function in 3080 adults from National Health and Nutrition Survey (NHANES) (2011–2018) to explore the effect of mixed metal exposure on CKD especially in people with type 2 diabetes mellitus (T2DM). Weighted quantile sum regression model and Bayesian Kernel Machine Regression model were used to evaluate the overall exposure impact of metal mixture and potential interaction between metals. The results showed that the exposure to mixed metals was significantly associated with an increased risk of CKD in blood glucose stratification, with the risk of CKD being 1.58 (1.26,1.99) times in urine and 1.67 (1.19,2.34) times in whole blood higher in individuals exposed to high concentrations of the metal mixture compared to those exposed to low concentrations. The effect of urine metal mixture was elevated magnitude in stratified analysis. There were interactions between urine Pb and Cd, Pb and Mn, Pb and Hg, Cd and Mn, Cd and Hg, and blood Pb and Hg, Mn and Cd, Mn and Pb, Mn and Hg on the risk of CKD in patients with T2DM and no significant interaction between metals was observed in non-diabetics. In summary, mixed metal exposure increased the risk of CKD in patients with T2DM, and there were complex interactions between metals. More in-depth studies are needed to explore the mechanism and demonstrate the causal relationship.

Determination of Low Concentrations of Mercury Based on the Electrodeposition Time.

Soil plays a crucial role in human health through its impact on food and habitation. However, it often contains toxic heavy metals, with mercury being particularly hazardous when methylated. Currently, high-sensitivity, rapid detection of mercury is achievable only through electrochemical measurements. These measurements require pretreatment of the soil sample and the preparation of a calibration curve tailored to the sample's condition. In this study, we developed a method to determine the environmental standard value of mercury content in soil by significantly reducing the pretreatment process. Our approach involves analyzing current peaks from electrodeposition times using specific electrodes and solvent settings. This method demonstrates low error rates under low concentration conditions and can detect mercury levels as low as 0.5 ppb in soil leachate and reagent dilution series. This research facilitates the determination of low mercury concentrations in solutions containing various soil micro-compounds without the need for calibration curves.

Heavy metals in cigarette smoke strongly inhibit pancreatic ductal function and promote development of chronic pancreatitis.

Smoking is recognised as an independent risk factor in the development of chronic pancreatitis (CP). Cystic fibrosis transmembrane conductance regulator (CFTR) function and ductal fluid and bicarbonate secretion are also known to be impaired in CP, so it is crucial to understand the relationships between smoking, pancreatic ductal function and the development of CP. We measured sweat chloride (Cl-) concentrations in patients with and without CP, both smokers and non-smokers, to assess CFTR activity. Serum heavy metal levels and tissue cadmium concentrations were determined by mass spectrometry in smoking and non-smoking patients. Guinea pigs were exposed to cigarette smoke, and cigarette smoke extract (CSE) was prepared to characterise its effects on pancreatic HCO3 - and fluid secretion and CFTR function. We administered cerulein to both the smoking and non-smoking groups of mice to induce pancreatitis. Sweat samples from smokers, both with and without CP, exhibited elevated Cl- concentrations compared to those from non-smokers, indicating a decrease in CFTR activity due to smoking. Pancreatic tissues from smokers, regardless of CP status, displayed lower CFTR expression than those from non-smokers. Serum levels of cadmium and mercury, as well as pancreatic tissue cadmium, were increased in smokers. Smoking, CSE, cadmium, mercury and nicotine all hindered fluid and HCO3 - secretion and CFTR activity in pancreatic ductal cells. These effects were mediated by sustained increases in intracellular calcium ([Ca2+]i), depletion of intracellular ATP (ATPi) and mitochondrial membrane depolarisation. Smoking impairs pancreatic ductal function and contributes to the development of CP. Heavy metals, notably cadmium, play a significant role in the harmful effects of smoking. Smoking and cigarette smoke extract diminish pancreatic ductal fluid and HCO3 - secretion as well as the expression and function of CFTR Cd and Hg concentrations are significantly higher in the serum samples of smokers Cd accumulates in the pancreatic tissue of smokers.

Mercury and Selenium Accumulation in the Tissues of Stranded Bottlenose Dolphins (Tursiops truncatus) in Northeast Florida, 2013-2021.

Bottlenose dolphins (Tursiops truncatus) are long-lived marine mammals, upper-level predators, and they inhabit near-shore environments, which increases their exposure to pollution. Mercury is a ubiquitous and persistent metal pollutant that can bioaccumulate and biomagnify up the food chain. Dolphins are known to accumulate mercury, and limited research has shown that mercury exposure can weaken the immune system of dolphins. The objectives of this study were to assess the mercury concentrations in the tissues (muscle, small intestine, liver) of stranded bottlenose dolphins and to compare the tissue mercury levels in dolphins that were stranded during the 2013-2015 morbillivirus Unusual Mortality Event (UME; immunosuppressed individuals) with the levels of those that were stranded at a normal rate (2016-2021). Selenium has been shown to reduce mercury toxicity in many animals; therefore, tissue selenium concentration and the molar ratio of selenium to mercury were also assessed. The tissue mercury (muscle, liver) and selenium (liver) concentrations increased with the age of the dolphins, with the liver accumulating the highest concentrations. No sex differences were observed in the mercury and selenium concentrations. While differences in tissue mercury concentrations were not observed due to the UME, the selenium accumulation profiles were significantly different between the two time periods. These results suggest that selenium may not have been as protective against mercury toxicity in the bottlenose dolphins that were stranded during the UME, possibly due to infection with morbillivirus.

Soil and Urine Mercury Levels in Secocha: A Case Study of Artisanal and Small-Scale Gold Mining in Peru

In recent decades, artisanal and small-scale gold mining (ASGM) has spurred population and economic growth in the small rural communities in which it is located, along with causing contamination of the soil, air, and water with grave effects on human health due to the uncontrolled use of mercury for gold processing activities. This study analyzes the levels of mercury in Secocha, an ASGM community in Arequipa, Peru. A total of 44 soil samples were taken from two ASGM commercial-extractive zones (n = 18) and non-processing urban zones (n = 26). Soil mercury analysis with atomic absorption spectrometry revealed average mercury levels of 86.11 mg/kg in commercial-extractive zone I, where ore processing has occurred for about 17 years, and mercury levels of 43.81 mg/kg in commercial-extractive zone II, where processing has occurred for about 7 years. In the urban zone, the average mercury level was 9.53 mg/kg. The average mercury concentrations for each zone exceed the relevant environmental quality standards established by the Peruvian Ministry of the Environment. In addition, urine samples were obtained from 15 miners and 15 people from the general urban population (non-miners). The average mercury level in the urine of miners was 7.04 µg/L, and in the urine of non-miners it was 0.49 µg/L. In both cases, the mercury urine level did not exceed the limits established by WHO and the Peruvian Ministry of Health, though miners’ elevated levels do raise concerns.

25 years recording of the long-base fluid tiltmeter installed at 2.850 m a.s.l. observatory of Pizzi Deneri on Etna volcano

Etna is a highly active volcano with frequent eruptions and is closely observed with different monitoring techniques. One of the monitoring methods is a network of short-base tiltmeters that provides continuous control of ground deformation. Since 1996, this network has been integrated with a long-base fluid tiltmeter installed in two 80 m long connected tunnels at the high-altitude (2850 m a.s.l.) volcanological observatory of Pizzi Deneri (PDN) located on the volcano’s summit. The instrumentation was devised with an innovative configuration composed of mercury, free to move along the entire length of the tiltmeter in response to the ground tilt, and laser sensors to measure the changes in the mercury levels. In this study, for the first time, we present the entire 25-year series of data recorded by this instrumentation. During this long interval, the Etna volcano was characterized by numerous major eruptions due to dyke intrusions. The tilt variations recorded in the short-term during the rapid intrusive phases are presented and discussed. These signals contributed both to the modeling of eruptive processes, and in particular in the case of the 2002–2003 eruption, to the real-time understanding of the ongoing eruptive phenomenon, supporting the correct hazard assessment. In the medium-long term (years to decades), we show and discuss that the PDN signal is mainly related to the marked sliding of the entire eastern sector of the volcano.Graphical

Measurement of lead, mercury, and cadmium in blood donors in Canada.

Fetal and neonatal exposure to lead is associated with irreversible adverse effects on neural development. There is no reliable threshold for lead effect, so limiting exposure is recommended. A significant correlation has been reported between post-transfusion blood lead level (BLL) in infants and lead levels in transfused RBC units. We measured levels of lead, mercury, and cadmium, in Canadian donor blood to investigate if concerning levels for neonatal transfusion exist. Whole blood samples from blood donors (n = 2529) were shipped cold within 7 days of donation. All permanent blood donation clinics across Canada were sampled. Twelve of these permanent clinics and 8 mobile clinics with a greater potential for having higher lead or mercury levels were oversampled. Heavy metals were measured by inductively coupled plasma mass spectrometry. Of all donations, 2.2% (lead) and 0.4% (mercury) had levels higher than the recommended thresholds for safe neonatal transfusion. BLLs were higher in males but there was no significant difference in the blood mercury levels of males versus females. Cadmium levels were higher in females. There was a positive correlation between donor age and levels of heavy metals, with lead having the strongest correlation (r = 0.47, p < .0001). Three clinics in close proximity to two lead-producing mines were among the clinics with the highest BLLs. Significantly higher blood mercury levels were observed in coastal clinics. Our data on donor blood heavy metal levels supports considering blood transfusion as an exposure source to heavy metals and encourages informed selection of blood units for transfusion to vulnerable groups.

Hair Mercury Levels in Pregnant Women: Fish Consumption as a Determinant of Exposure

The consumption of fish in food may contain mercury, a harmful element and dangerous chemical detrimental to human health. The purpose of this study was to determine the mercury level in the hair of pregnant women with different fish intakes in their diets. The concentration of total mercury in hair was determined using an atomic absorption spectrometer. In this study, 98 pregnant women were invited to participate (aged from 18 to 48 years). The mean content of mercury in the hair of pregnant women in Northwestern Russia was 0.428 mg/kg (ranging from 0.018 to 3.1 mg/kg). As a result, 22% of women had mercury values above 0.58 mg/kg, which is considered dangerous for the fetus. The hair mercury concentration in a village area was higher than that in a city area (i.e., 0.548 mg/kg and 0.326 mg/kg). Moreover, the maximum level of mercury was noted for a group of pregnant women who consumed more than 5 kg/month of fish and fish products. Furthermore, the consumption of freshwater fish in the diet leads to a higher mercury content in the hair of pregnant women than the consumption of marine fish.

Capillary Point Discharge-Optical Emission Spectrometer: field portable mercury analyzer

Environmental mercury pollution poses a serious threat to public health and ecosystems, underscoring the value of rapid and accurate on-site mercury measurement technologies. Therefore, a portable mercury analyzer was developed with capillary point discharge for excitation and cold vapor generation for sample introduction. A limit of detection (LOD) of 0.23 μg L−1 for mercury was achieved, relative standard deviations below 5 % were maintained in a 10-hour testing period. This method was successfully used for mercury determination of spiked water samples, fish meat, and laboratory wastewater. Powered by several power banks, it can be used to monitor mercury levels in water samples continuously over a working day. Compared with traditional technology, this one greatly reduces the size of the instrument, the consumption of working gas, and the construction cost, making it suitable for rapid field analysis of many types of samples for trace mercury.

Mercury in four common fishes sold in Algeria and associated humans risk

ABSTRACT This study aimed to analyse the concentrations of mercury in fish samples available in the Algerian market and evaluate the potential health risks associated with their consumption. A total of 135 fish samples, representing the species Sardina pilchardus, Merluccius merluccius, Sparus aurata and Auxis rochie, were collected and analysed. Mercury levels were determined using thermal decomposition amalgamation Atomic Absorption Spectrophotometry. Health risks were evaluated by calculating hazard quotients. The overall mean concentration was 0.19 ± 0.11 mg/kg across all species. Individual species concentrations were recorded as 0.17 ± 0.08 mg/kg for Sardina pilchardus, 0.26 ± 0.19 mg/kg for Merluccius merluccius, 0.27 ± 0.18 mg/kg for Sparus aurata and 0.23 ± 0.13 mg/kg for Auxis rochei. Hazard quotients were below 1, indicating low health risk for fish consumers. Nevertheless, it is recommended to conduct periodic monitoring of heavy metal levels in fish, coupled with ongoing risk assessments, to ensure continued consumer protection.

No evidence of an association between size and levels of four per- and polyfluorinated substances (PFAS) in perch (Perca fluviatilis)

It was assessed how the size of perch (Perca fluviatilis) is related to levels of four per- and polyfluorinated substances (PFAS) in its muscle tissue. These were PFOS, PFNA, PFOA, and PFHxS, for which the sum, denoted as ΣPFAS4, has a tolerable intake derived by the European Food Safety Authority. The results indicate that, in contrast to, e.g., mercury levels, ΣPFAS4 levels in perch muscle do not increase with increasing weight of the fish, which implies that consuming larger perch does not increase the risk of exceeding the TWI of ΣPFAS4, in relation to consuming smaller perch. Therefore, for risk assessment, analyzing samples of smaller perch is sufficient, demanding less effort to catch. The credibility of the results was strengthened by applying the same statistical model to mercury levels in the same samples. As expected, larger fish had generally higher levels than small fish for mercury.

Association of aquatic food consumption, long-chain polyunsaturated n-3 fatty acid intake, and blood mercury levels with cognitive function in middle-aged and older adults

Background & aimsAquatic food is rich in nutrients which benefit the human brain and cognitive health; however, concerns about heavy metal accumulation in aquatic food remain. This study evaluated the associations between aquatic food consumption, long-chain n-3 polyunsaturated fatty acids (LC n-3 PUFAs) intake, and blood mercury levels with cognition in middle-aged and older adults. MethodsThis cross-sectional study used baseline data from the Lifestyle and Healthy Aging of Chinese Square Dancer Study. Aquatic food consumption and LC n-3 PUFAs intake were obtained from a food frequency questionnaire. Blood mercury levels were measured using inductively coupled plasma mass spectrometry. A composite z-score was developed to represent global cognition by averaging the z-scores for each cognitive domain. Participants with mild cognitive impairment (MCI) were diagnosed according to Petersen’s criteria. Multivariate linear and logistic regression models were used to examine the association between the exposure factors and cognitive performance including cognitive scores and MCI. ResultsOf 2621 middle-aged and older adults, the mean (SD) age was 63.71 (5.15) years, and 85.73% were females. Compared with the lowest quartile, those in the highest quartile for aquatic food consumption were associated with higher composite z-scores (β=0.156, 95% CI: 0.088–0.225) and lower MCI odds (OR=0.598, 95% CI: 0.425–0.841). A similar positive relationship between LC n-3 PUFAs intake and composite z-score and an inverse association between LC n-3 PUFAs intake and MCI were also observed. In addition, the participants in the highest quartile for blood mercury levels had higher composite z-scores than those in the lowest quartile. ConclusionsIn this cross-sectional study, higher aquatic food consumption, LC n-3 PUFAs intake, and blood mercury levels were related to better cognitive function. Further studies in Chinese populations are required to confirm these findings.

Mercury levels in Nile perch fillets in processing industries in Uganda

ABSTRACT Mercury levels of Nile perch fillets to be exported from selected fish processing industries in Uganda were determined by hot digestion in strong acids, followed by analysing the extracts with Inductive Coupled Plasma-Mass Spectroscopy (ICP-MS). There was a clear link between atmospheric mercury and methylmercury accumulation in fish tissues, thus exposing a possible threat for human health. A quantitative cross-sectional study design was undertaken from two fish processing factories around Kampala city. Simple random sampling was utilised where ten fish products were picked for analysis. The results obtained from the analysis of samples from both factories presented mercury levels far below the FAO/WHO guideline level of 0.5 mg/kg for mercury in fish. The mercury levels for both factories were higher than the oral daily recommended dose of 0.001 mg/kg body weight for the vulnerable population raising eyebrows for the general population, since fish is a major contributor to mercury intake for consumers.

Process of mercury accumulation in urban strip river artificial wetland ecosystems: a case study of Changchun, a typical industrial city in Northeast China.

Mercury (Hg), as a global pollutant, is persistent, migratory, insidious, highly biotoxic and highly enriched, and is widely distributed in the atmosphere, hydrosphere, biosphere and lithosphere. Wetland ecosystems, as active mercury reservoirs, have become the most important sources and sinks of heavy metal mercury. Distinguished from natural wetlands, artificial wetlands located in urban sections of rivers face problems such as diverse urban pollution sources and complex spatial and temporal changes. Therefore, in this study, five intermittently distributed artificial wetlands were selected from the upstream to the downstream of the Changchun section of the Yitong River, a tributary of the Songhua River basin in the old industrial base of Northeast China. The mercury levels in the water bodies, sediments and plants of the artificial wetlands were collected and tested in four quarters from April 2023 to analyse the spatial and temporal distribution characteristics of total mercury. The results showed that the mercury levels in the water bodies, sediments and plants of the five wetlands showed a fluctuating trend with the river flow direction and had certain spatial and temporal distribution characteristics. This phenomenon was attributed to the sinking of external mercury pollution sources. In general, the wetland ecosystems showed a decreasing trend in the total Hg output of the downstream watershed. This may be due to the retention of particulate matter by aquatic plants in artificial wetlands to regular salvage of dead aquatic plants. At the same time urbanization and industrialization affect mercury levels in aquatic environments, so the risk of residential exposure needs to be looked at.

Distribution of mercury contamination on paddy fields in various levels of soil depth in gold mine area at Sub-District Hutabargot, Mandailing Natal Regency, Indonesia

Unauthorised Gold Mining in Mandailing Natal Regency could serious problems for the environment and human health. It is because waste from the amalgamation process contains mercury released into the waterways that are irrigation sources. The main damage impact from the mercury waste released into irrigation canals would be seen on the paddy field. For this reason, it is necerssary to tests and studies to see the contaminated level of mercury on paddy fields. This research was conducted from June to July 2023 in Sub-District Hutabargot, Mandailing Natal Regency by took soil sampling in the 0-10 cm, 11-20 cm, 21-20 cm, 31-40 cm, 41-50 cm, 51-60 cm, 61-70 cm, 71-80 cm, 81-90 cm, and 91-100 cm on soil depth in 7 sampling points. The resulting study obtained at least 170 amalgamation points that the waste released into the waters. The mercury content on the paddy soil in Sub-District Hutabargot which is irrigation irrigated by amalgamation process exceeding the threshold. There is an increase of mercury content in the 30 cm soil depth and then decreases with increasing soil depth. For a depth of more than 60 cm, the mercury content on the paddy soil is under the threshold.