Increase In Mercury Concentration Research Articles

Hydroclimatic anomalies detected by a sub-decadal diatom oxygen isotope record of the last 220 years from Lake Khamra, Siberia

Abstract. Northern latitudes have been significantly impacted by recent climate warming, which has increased the probability of experiencing extreme weather events. To comprehensively understand hydroclimate change and reconstruct hydroclimatic anomalies such as drought periods, appropriate proxy records reaching further back in time beyond meteorological measurements are needed. Here we present a 220-year (2015–1790 CE), continuous, stable oxygen isotope record of diatoms (δ18Odiatom) from Lake Khamra (59.99° N, 112.98° E) in eastern Siberia, an area highly sensitive to climate change and for which there is a demand for palaeohydrological data. This high-resolution proxy record was obtained from a 210Pb–137Cs-dated sediment short core and analysed to reconstruct hydroclimate variability at a sub-decadal scale. The interpretation of the δ18Odiatom record is supported by meteorological data, modern isotope hydrology and geochemical analyses of the same sediment, which is indicative of the conditions in the lake and catchment. A comparison with meteorological data going back to 1930 CE revealed that the δ18Odiatom record of Lake Khamra is primarily influenced by regional precipitation changes rather than the air temperature. We identified winter precipitation, which enters the lake as isotopically depleted snowmelt water, as the key process impacting the diatom isotope variability. We related the overall depletion of δ18Odiatom in recent decades to an observed increase in winter precipitation in the area, likely associated with the global air temperature rise, Arctic sea ice retreat and increased moisture transport inland. Available palaeoclimate proxy records, including a fire reconstruction for the same lake, support the idea that the new record is a valuable hydroclimate proxy that is indicative of precipitation deficits and excludes solar insolation and air temperature as primary driving forces, even before the first meteorological recordings. We propose two possible hydroclimatic anomalies that were detected in the Lake Khamra δ18Odiatom record: one at the beginning of the 19th century and a second prominent event in the 1950s. Both are interpreted as prolonged dry periods associated with enriched δ18Odiatom values likely caused by reduced winter precipitation, which coincide with phases of reconstructed severe wildfires in the region. Despite the apparent pristine lake area, we observed a three- to fourfold increase in mercury concentrations and accumulation rates within the sediment record since the early 20th century, which is partly attributed to human air pollution.

Heavy Metal Bioaccumulation in Rabbit Organs and Chrysomya albiceps (Wiedemann, 1819) Larvae: Implications for Forensic Entomology

Background: A closer relationship has been established between entomology and toxicology, giving rise to a new field known as entomotoxicology, which focuses on the bioaccumulation of toxic substances in scavenging insects and other arthropods. Methods: This study investigates the impact of lethal doses of Mercury Chloride (HgCl2) and Cadmium Chloride (CdCl2) administered to male rabbits (Oryctolagus cuniculus Linnaeus) on the distribution of Mercury and Cadmium in rabbit organs and their subsequent accumulation in Chrysomya albiceps larvae. The experimental groups were subjected to oral administration of specific concentrations of HgCl2 and CdCl2, while a control group received distilled water. Organ dissection and subsequent larval feeding were followed by acid digestion for sample preparation and inductively coupled plasma torch spectrometry coupled with a mass spectrometer (ICP-MS) was employed for analysis. Result: Results indicate a significant increase in Mercury concentrations in treated rabbit organs, with the liver exhibiting the highest concentration. Cadmium showed diverse distribution among rabbit organs, with the highest concentrations in the kidneys. Ch. albiceps larvae, reared on rabbit organs, exhibited varied concentrations of both Mercury and Cadmium, with significantly higher levels in the treated group. These findings underscore the ecological implications of heavy metal exposure and the potential utility of insect larvae in forensic investigations as bioindicators of environmental contamination.

Modelling the Effect of mercury on the Growth Rate of an SDS-degrading Pseudomonas sp. strain Maninjau1

The SDS-degrading bacterium Pseudomonas sp. strain Maninjau1 experienced significant inhibition by mercury. Observations of bacterial growth at varying mercury concentrations revealed a sigmoidal pattern, with lag periods extending from 7 to 12 hours. Increasing mercury concentrations progressively impeded growth, with a concentration of 1.0 mg/L nearly halting bacterial activity. To analyze these effects, the modified Gompertz model was employed to determine growth rates across different mercury concentrations. These rates were then subjected to several models, including the modified Han-Levenspiel, Wang, Liu, Shukor, modified Andrews, and Amor models. Among these, the Amor model failed to appropriately fit the growth curves. Statistical analysis indicated that the Shukor model performed the best, evidenced by the lowest values for Root Mean Square Error (RMSE) and Akaike’s Information Criterion corrected (AICc), the highest adjusted correlation coefficient (adR2), and values of Accuracy Factor (AF) and Bias Factor (BF) closest to unity. The parameters obtained from the Shukor model, which are mmax (h-1) and Sm (mg L-1) and n which represent maximum growth rate, critical heavy metal ion concentration and empirical constant values were 0.187, 1.126 and 2.406, respectively. The Shukor model allows for the prediction of the critical heavy metals concentration which can completely inhibited bacterial growth. This robust modeling approach underscores the Shukor model's suitability for predicting the impact of mercury on the growth dynamics of Pseudomonas sp. strain Maninjau1 under toxic stress conditions.

Complex Life Histories Alter Patterns of Mercury Exposure and Accumulation in a Pond-Breeding Amphibian.

Quantifying how contaminants change across life cycles of species that undergo metamorphosis is critical to assessing organismal risk, particularly for consumers. Pond-breeding amphibians can dominate aquatic animal biomass as larvae and are terrestrial prey as juveniles and adults. Thus, amphibians can be vectors of mercury exposure in both aquatic and terrestrial food webs. However, it is still unclear how mercury concentrations are affected by exogenous (e.g., habitat or diet) vs endogenous factors (e.g., catabolism during hibernation) as amphibians undergo large diet shifts and periods of fasting during ontogeny. We measured total mercury (THg), methylmercury (MeHg), and isotopic compositions (δ 13C, δ15N) in boreal chorus frogs (Pseudacris maculata) across five life stages in two Colorado (USA) metapopulations. We found large differences in concentrations and percent MeHg (of THg) among life stages. Frog MeHg concentrations peaked during metamorphosis and hibernation coinciding with the most energetically demanding life cycle stages. Indeed, life history transitions involving periods of fasting coupled with high metabolic demands led to large increases in mercury concentrations. The endogenous processes of metamorphosis and hibernation resulted in MeHg bioamplification, thus decoupling it from the light isotopic proxies of diet and trophic position. These step changes are not often considered in conventional expectations of how MeHg concentrations within organisms are assessed.

Can a 16th Century Shipwreck Be Considered a Mercury Source in the 21st Century?—A Case Study in the Azores Archipelago (Portugal)

During the Spanish colonial era, ships frequently transported mercury across the Atlantic to the New World to be used in gold mining. As many of those eventually sank, shipwrecks may represent a local source of mercury contamination in the marine environment. In this context, evaluating mercury contamination in coastal sediments and mercury magnification in marine food webs is crucial for understanding mercury dynamics and estimating exposure to marine life in locations where shipwrecks occurred. This study investigated mercury concentration present in coastal sediments and biota from three distinct groups: macroalgae (Asparagopsis armata and Ulva lactuca), gastropods (Littorina striata and Patella candei gomesii) and crustaceans (Palaemon elegans and Pachygrapsus marmoratus) collected in the Azores Archipelago, Portugal (one site near a 16th-century shipwreck and others in locations further away). Mercury analyses indicated that the sediments and species from the shipwreck area had significantly higher mercury levels than the other areas. Fine sediments showed values above those established in sediment quality guidelines; however, considering the mercury concentration of the total sediment fraction, adverse biological effects are not expected to occur. Moreover, increased mercury concentration from primary producers to consumers reinforced the biomagnification potential of this metal.

The dynamics of mercury around an artisanal and small-scale gold mining area, Camarines Norte, Philippines.

To elucidate the dynamics of mercury emitted and released by artisanal and small-scale gold mining (ASGM) activity and to estimate its impact on the ecosystems of the bay, the distribution of mercury in the atmosphere, soil, water, and sediment around Mambulao Bay, Camarines Norte, Philippines, was investigated. The ASGM operations use mercury to extract gold from ore and are located on the east shore side of the bay. Samplings were conducted in August 2017 and September 2018. The samples were used for determination of total mercury (T-Hg) and organic mercury (org-Hg) concentrations, total organic carbon (TOC) content, and chemical composition. The atmospheric mercury concentration on the east shore side, 6.1-25.8ngm-3, was significantly higher than the value of 1.4-9.9ngm-3 observed on the west shore side. The average concentrations of T-Hg in the forest soils of the west shore side and those of the east shore side were 0.081 ± 0.028mgkg-1 and 0.496 ± 0.439mgkg-1, respectively. In the vertical distribution of T-Hg in the soil of the east shore side, a higher concentration was observed near the surface. For the vertical variations in T-Hg in the marine sediment, higher values were observed near the estuary, and the vertical variations in core samples showed an increase in mercury concentration toward the surface. The highest concentration of T-Hg in sediment, 9.5mgkg-1, which was 2 orders of magnitude higher than the background levels of this area, was found near the river mouth. The T-Hg, org-Hg, and TOC levels showed a positive correlation, suggesting that the rivers are the main sources of T-Hg and org-Hg in the bay. Although the fish sample containing a mercury content higher than the regulatory level for fish and shellfish of 0.4mgkg-1 in Japan was only one of 42 samples, the percentage of org-Hg in fish samples was 91 ± 18%. Mercury released into the surroundings by the ASGM activities can be converted into methylmercury and affect the bay's ecosystem.

Highly mercury-resistant strains from different Colombian Amazon ecosystems affected by artisanal gold mining activities

Two sites of the Colombian Amazon region with different levels of human intervention and mercury pollution were selected for the collection of samples of river and lake water, sediments, and associated forest soils. The Tarapacá region, affected mainly by barrage mining, showed low mercury concentrations, whilst in the Taraira region, affected by underground mining, there were several points with high mercury pollution levels. A collection of 72 bacterial and 10 yeast strains with different levels of mercury resistance was isolated and characterized. Most of the highly resistant bacterial strains (MIC > 40 mg L−1 HgCl2) were isolated from soil and sediment samples and belonged to either Pseudomonas (60%) or Bacillus (20%). Most of highly resistant bacterial strains were positive for the presence of the merA gene, suggesting an active mercury resistance mechanism. This was confirmed in the two most resistant strains, Pseudomonas sp. TP30 and Burkholderia contaminans TR100 (MIC = 64 and 71 mg L−1 HgCl2, respectively), which in the presence of increasing mercury concentrations expressed the merA gene at increasing levels, concomitant with a significant mercury reduction activity. Analysis of the MerA sequences present in the different isolates suggested a high gene conservation within the taxonomic groups but also several horizontal gene transfer events between taxonomically distant genera. We also observed a positive correspondence between the presence of the merA gene and the number of antibiotics to which the strains were resistant to. The most resistant strains are good candidates for future applications in the bioremediation of mercury-contaminated sites in the Amazon.Key points• Amazon sediments affected by underground gold mining have higher Hg levels.• Highly Hg-resistant isolates belonged to Pseudomonas and Bacillus genera.• TR100 and TP30 strains showed remediation potential to be used in the Amazon region.Graphical abstract

Pengaruh Pestisida dari Aktivitas Pertanian Terhadap Konsentrasi Merkuri (Hg) pada Sungai Sumur Beremas Kota Sungai Penuh

Agricultural activities cannot be separated from the use of pesticides to control plant-disturbing organisms. The mercury (Hg) content in pesticides cannot be naturally degraded on agricultural land, so it will be carried off by run-off into the waters. Pesticide’s run-off from agricultural activity along the Sumur Beremas River has an effect in increasing mercury concentrations in the river. This study aims to analyze the effect of pesticide use on mercury concentrations in the Sumur Beremas River and to analyze the capacity of river pollution loads. The effect of pesticide on mercury concentrations was analyzed using Pearson correlation. The capacity of Sumur Beremas River's pollution loads against mercury was analyzed using mass balance method. The results showed that the use of pesticides had a significant effect on the increase in mercury concentrations in river water. The greatest correlation value occurs in downstream of irrigation, namely 0.977, which indicates the high run-off that occurs from agricultural area to the irrigation flow. The concentration of mercury based on the analysis of river pollution loads is 0.00242 ppm, exceeding the standard PP no. 82 of 2001 Class II, 0.002 ppm, which indicates that Sumur Beremas River is no longer able to accommodate the load of mercury pollution.

Hg(II) Ion-Selective Electrodes with PVC Membranes Based on Bis-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one

Abstract A new solid-state contact potentiometric membrane electrode was developed based on bis-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one (ionophore), which acts selectively towards the mercury(II) ion. The ionophore was synthesized by the treatment of an amino derivative with oxybis dibenzaldehyde. The potentiometric behavior of an electrode was investigated in the concentration range from 1.0 × 10−2 to 1.0 × 10−6 mol L−1 for mercury(II) ion. The electrode displayed a good linearity (R2 = 0.9997) with the detection limit of 1.2 × 10−7 mol L−1 and showed a very high selectivity against Hg(II) ion without being affected by the presence of interfering ions. The electrode exhibited a potential change of 62.0 ± 2.0 mV for each ten-fold increase in concentration of mercury(II) ion. Potentiometric response of the electrode was investigated in the pH range from 3.0 to 10.0. In addition to this electrode being used to determine mercury(II) in different water samples, it can also be used with EDTA as an indicator electrode in the potentiometric titration of mercury(II) ion. Since the developed electrode displayed good potentiometric performance, it has potential to be used in environmental and biological samples for detection of mercury(II) ions.

ELECTROCHEMICAL SYNTHESIS OF NICKEL HYDROXIDE Ni(OH)2 NANOPARTICLES SOLUTION FOR DETECTING MERCURY (Hg)

Nickel hydroxide Ni(OH) 2 nanoparticles were used as sensors for mercury (Hg) in water using a UV-Vis spectrophotometer instrument. The synthesis of Ni(OH) 2 nanoparticles was carried out by electrochemical method using nickel plates as anode and cathode and the process was operated at constant voltage of 25 V for 30 minutes. In this study, 2 variations of the concentration of Ni(OH) 2 nanoparticles were used, namely (5 mL and 4 mL) to detect mercury at concentrations of 0 ppm, 10 ppm, 20 ppm, 30 ppm, 40 ppm, and 50 ppm. Changes in the absorbance value of Ni(OH) 2 nanoparticles will be observed. From the observations, there was a decrease in the absorbance value of Ni(OH) 2 nanoparticles along with the increase in mercury concentration. The decrease in the absorbance value of Ni(OH) 2 nanoparticles is directly proportional to the amount of mercury concentration. The detection limit value was obtained at a volume of 5 mL and 4 mL are 42 ppm, and 75.8 ppm.

Investigation of Protein Biomarkers and Oxidative Stress in Pinirampus pirinampu Exposed to Mercury Species from the Madeira River, Amazon-Brazil.

In recent decades, the scientific community has widely debated the contamination of fish in the Amazon region by mercury species. As the diet of riverside populations in the Amazon region is based mainly on fish, these populations are exposed to mercurial species that can cause serious and irreversible damage to their health. The risks of consuming fish exposed to mercurial species in the Amazon region have motivated toxicological investigations. However, the effect of mercurial species on protein and enzyme levels is still controversial. In this work, analytical and bioanalytical techniques Two-dimensional polyacrylamide gel electrophoresis [2D-PAGE] Graphite Furnace Atomic Absorption Spectrometry [GFAAS], and Mass Spectrometry in Sequence with Electrospray Ionization [ESI-MS/MS] were used to identify proteins associated with mercury (metal-binding protein) in muscle and liver tissues of the fish species Pinirampus pirinampu from the Madeira River, in the Brazilian Amazon. Enzymatic and lipid peroxidation analyses were also used to assess changes related to oxidative stress. Determinations of total mercury by GFAAS indicated higher concentrations in liver tissue (555 ± 19.0µgkg-1) when compared to muscle tissue (60 ± 2.0µgkg-1). The fractionation process of tissue proteomes by 2D-PAGE and subsequent mapping of mercury by GFAAS in the protein spots of the gels identified the presence of mercury in three spots of the liver tissue (concentrations in the range of 0.800 to 1.90mgkg-1). The characterization of protein spots associated with mercury by ESI-MS/MS identified the enzymes triosephosphate isomerase A, adenylate kinase 2 mitochondrial, and glyceraldehyde-3-phosphate dehydrogenase as possible candidates for mercury exposure biomarkers. The muscle tissue did not show protein spots associated with mercury. Enzymatic activity decreased proportionally to the increase in mercury concentrations in the tissues.

High-efficiency removal of low-concentration Hg(II) from aqueous solution by bentonite nanocomposite: Batch and fixed-bed column adsorption study

ABSTRACT A nanocomposite based on bentonite was synthesized. Its adsorption properties for Hg(II) were evaluated by batch and fixed-bed column adsorption experiments. The results showed that the nanocomposite was an efficient adsorbent for the treatment of wastewater containing low-concentration Hg(II). It removed more than 92% of Hg(II) from aqueous solution with a pH ranged from 4.00 to 12.00. Its adsorption capacity for Hg(II) increased linearly with the increase of mercury concentration. The nanocomposite had excellent reusability. HCl solution can be used to elute Hg(II) ions loaded. The developed Bohart–Adams model can be used for the design of adsorption column.

A scoping review of sources of mercury and its health effects among Pakistan's most vulnerable population.

Mercury and methyl mercury are poisonous to human body. In the recent times, exposure to mercury has been anthropogenic in nature. Within the past several decades, many incidences of mercury poisoning have been documented in several countries including Pakistan. Mercury has been ingested where it has been used to preserve crops, through the point and non-point source discharge into the surface water, and consequently entering the food chain. We conducted this scoping review of mercury and its health effects in Pakistan in order to raise the flag to a silent ongoing Minamata disease in the country. We conducted a systematic search of the available literature in Google Scholar, PubMed, and grey literature of unpublished theses and reports of various universities across the country. We found that in the northern Pakistan, suspended sediments were the major pathway of the riverine mercury transport. Sediments of Hunza and Gilgit River were found high in mercury concentrations. Gold mining leads to an increase in mercury concentration in soil and river waters flowing in this region. High concentrations up to 108ng/L were found in Shimsal River. It is suspected that that high level of mercury transport may be leading to accumulation of mercury in major water bodies and lakes downstream. Occupational exposure to mercury and other heavy metals is common in an unregulated private sector of the country. Goldsmiths burn the amalgamated gold without personal protective measures. Direct exposure to the fumes of mercury leads to respiratory, dermatological, systemic and neurological ailments specific to mercury poisoning. We found good evidence of bioaccumulation of mercury in fish and fish products in Pakistan. The untreated waste water discharge is responsible to not only afflicted the fish but also the birds which feed on this fish. Further, the same untreated waste water from factories and agriculture runoffs affect vegetables grown in it. Studies looking at the biomarkers for mercury in humans have shown increased and even toxic levels of mercury among the most vulnerable populations of the country. Other sources of mercury exposure included mercury in traditional medicines and cigarette products. Though no evidence was found for its presence in drinking water, its existence in the food chain and occupational exposure pose great threat to the humans as well as animals.

Carbon dots as rapid assays for detection of mercury(II) ions based on turn-off mode and breast milk.

In this research, nitrogen co-doped carbon dots were synthesized by solid thermal method with citric acid used as the precursor of carbon, and melamine as nitrogen source. Such carbon dots show high quantum yield of 44%. Furthermore, the native fluorescence of CDs can be reduced by mercury(II), while other metals had no significant influence on fluorescence intensity. During the study, the optimal parameters were selected, such as pH or time for incubation with analyte. Under the optimal conditions, quenching effect caused by mercury ions was evaluated. It was observed that with increasing mercury concentration, the fluorescence of the carbon dots decreased proportionally. The response was characterized by linearity within the range from 2 to 14μM. Moreover, the limit of detection was 0.44μM. It was the first time that human milk was used as a real sample to test the applicability of carbon dots. The study results demonstrated good recovery in the 74-111% range (RSD<6%) As a novel carbon material, CDs show promise for broader applications in analyzing complicated biological samples.

Association of Fish Consumption and Mercury Exposure During Pregnancy With Metabolic Health and Inflammatory Biomarkers in Children

The balance of mercury risk and nutritional benefit from fish intake during pregnancy for the metabolic health of offspring to date is unknown. To assess the associations of fish intake and mercury exposure during pregnancy with metabolic syndrome in children and alterations in biomarkers of inflammation in children. This population-based prospective birth cohort study used data from studies performed in 5 European countries (France, Greece, Norway, Spain, and the UK) between April 1, 2003, and February 26, 2016, as part of the Human Early Life Exposome (HELIX) project. Mothers and their singleton offspring were followed up until the children were aged 6 to 12 years. Data were analyzed between March 1 and August 2, 2019. Maternal fish intake during pregnancy (measured in times per week) was assessed using validated food frequency questionnaires, and maternal mercury concentration (measured in micrograms per liter) was assessed using maternal whole blood and cord blood samples. An aggregate metabolic syndrome score for children was calculated using the z scores of waist circumference, systolic and diastolic blood pressures, and levels of triglyceride, high-density lipoprotein cholesterol, and insulin. A higher metabolic syndrome score (score range, -4.9 to 7.5) indicated a poorer metabolic profile. Three protein panels were used to measure several cytokines and adipokines in the plasma of children. The study included 805 mothers and their singleton children. Among mothers, the mean (SD) age at cohort inclusion or delivery of their infant was 31.3 (4.6) years. A total of 400 women (49.7%) had a high educational level, and 432 women (53.7%) were multiparous. Among children, the mean (SD) age was 8.4 (1.5) years (age range, 6-12 years). A total of 453 children (56.3%) were boys, and 734 children (91.2%) were of white race/ethnicity. Fish intake consistent with health recommendations (1 to 3 times per week) during pregnancy was associated with a 1-U decrease in metabolic syndrome score in children (β = -0.96; 95% CI, -1.49 to -0.42) compared with low fish consumption (<1 time per week) after adjusting for maternal mercury levels and other covariates. No further benefit was observed with fish intake of more than 3 times per week. A higher maternal mercury concentration was independently associated with an increase in the metabolic syndrome score of their offspring (β per 2-fold increase in mercury concentration = 0.18; 95% CI, 0.01-0.34). Compared with low fish intake, moderate and high fish intake during pregnancy were associated with reduced levels of proinflammatory cytokines and adipokines in children. An integrated analysis identified a cluster of children with increased susceptibility to metabolic disease, which was characterized by low fish consumption during pregnancy, high maternal mercury levels, decreased levels of adiponectin in children, and increased levels of leptin, tumor necrosis factor α, and the cytokines interleukin 6 and interleukin 1β in children. Results of this study suggest that moderate fish intake consistent with current health recommendations during pregnancy was associated with improvements in the metabolic health of children, while high maternal mercury exposure was associated with an unfavorable metabolic profile in children.

Clover nodule bacteria as bioindicators of soils contaminated with heavy metals

The article presents the results of a study of vital activity of nodule bacteria of Trifolium praténse, Trifolium hibridum, Trifolium alexandrinum and Trifolium incarnatum as environmentally friendly bioindicators in soil toxicity assessment. The study focused on the number of nodules and their stain with leghemoglobin. The materials were taken from the plots artificially contaminated with heavy metals (lead (Pb), arsenic (As), mercury (Hg), fluorine (F), zinc (Zn) and cobalt (Co)). The results of the experiments showed that environmental distress occurs when the nitrogen-fixing nodules are stained pink or red in the range of 8-15%, which indicates that the lead content in the soil exceeds the threshold limit value (TLV) by 1.2-1.5 times. A significant decrease in nodule activity and weak or no stain were observed with an increase in mercury concentration by 1.1 times. It was found that the mass of rhizobium or the supply of organic nitrogen obtained by plants from fixation from the air is directly dependent on the grass density. At high concentrations of heavy metals in the soil, the nodule bacteria lose the amount of leghemoglobin, therefore the stain of bacteria is disrupted, so this indicator can be used as a bioindicator in soil toxicity assessment.

Mercury concentrations in biota in the Mediterranean Sea, a compilation of 40 years of surveys

The Mediterranean Region has a long lasting legacy of mercury mining activities and a high density of sub-marine volcanoes that has strongly contributed to its mercury budget. In the last forty years, there have been recorded increases in mercury concentrations in biota that have spurred a growing number of research activities to assess the impact of mercury pollution on human health and environment. Field investigations that quantify mercury concentrations in marine biota have led to a large amount of experimental data scattered in many peer-reviewed publications making it difficult for modelling applications and regional environmental assessments. This paper reviews existing peer-reviewed literature and datasets on mercury concentration in marine flora and fauna (Animal, Plants and Chromista Kingdoms) in the Mediterranean basin. A total of 24,465 records have been retrieved from 539 sources and included in Mercury in Mediterranean Biota (M2B). Well-defined specimens account for 24,407 observations, while a few records include generic plankton and unidentified fish species. Among all considered species, we selected Diplodus sargus, Sardina pilchardus, Thunnus thynnus and Xiphias gladius to show trends of mercury concentration against WHO and EU limits. Few notes on how M2B is intended to support the implementation of the Minamata Convention on Mercury by a user-driven Knowledge Hub are finally reported.

Constraints on the volume and rate of Deccan Traps flood basalt eruptions using a combination of high-resolution terrestrial mercury records and geochemical box models

Deccan Traps continental flood basalt eruptions spanned the Cretaceous-Paleogene mass extinction, erupting over a million cubic kilometers of basalt over a total duration of approximately a million years. The environmental consequences of flood basalt eruptions depend on the timing and amount of volatile release; eruption rates are thus needed to evaluate their potential to cause climate change. Radioisotopic dates are not currently sufficient to resolve sub-ten thousand year eruptive tempos, necessary for constraining the effects of short-lifetime volatiles including sulfur dioxide. Recent studies have demonstrated that increases in mercury concentration in sedimentary records correlate with flood basalt eruptions under some circumstances. However, mercury concentrations have primarily been used to show the presence or absence of flood basalt eruptions. We show that this proxy can be used to quantitatively estimate eruptive rates using a mercury geochemical cycle framework. We illustrate this using new mercury chemostratigraphic records from terrestrial Cretaceous-Paleogene boundary sections in eastern Montana, USA, with multiple high-resolution chronologic constraints. We estimate that Deccan eruptions lasted on the order of centuries and released 500–3000 megagrams (Mg) of mercury per year, corresponding to ∼50–250 km3/a of lava. The box model framework highlights the importance of carefully accounting for differences in sedimentation rate and sampling resolution when comparing mercury records from different locations and depositional environments. While there are uncertainties in the box model estimates due to possible variation in flood basalt mercury emissions and sedimentation rates, they provide a useful framework to quantitatively evaluate the global mercury budget change indicated by changing concentration in sedimentary records. Eruptions of the estimated size would have released enough SO2, if it reached the stratosphere, to cause significant cooling for the duration of the eruption. However, given our constraints on the duration of individual eruptions, these colder periods are likely too brief to be clearly visible in most existing paleoclimate records.

Evaluation of the cytogenotoxic activity of mercury by analyzing chromosomal aberrations in wheat root meristem cells

The work evaluates the cytogenotoxic effect of mercury by performing a primary screening on a plant object. The authors determined the qualitative and quantitative characteristics of a cytogenotoxic effect depending on the exposure time and the dose of mercury nitrate (Hg (NO3)2) in anaphase and telophase of mitosis on wheat apical meristem cells of the Memory of Aziev variety. In the process of primary screening to assess the cytogenotoxic effect of the test substance, the nature and diversity of chromosomal abnormalities in the wheat meristem cells of the presented variety were studied. The frequency of occurrence of various types of chromosomal aberrations was analyzed. The complex shows the effect of mercury salts on viability indices and chromosomal instability of wheat. The cumulative pathology curves for different exposures of (Hg (NO3)2) are presented. A significant increase in the number of pathologies was shown in accordance with the increase in mercury concentration in anaphase of mitosis. A similar pattern was observed in the change in the total number of chromosome aberrations in accordance with the increase in the soaking time of seed material. The results of the study of the cytogenotoxic activity of mercury make it possible to assess the toxicity of mercury (Hg (NO3)2) for plant objects and recommend the object used in the experiment as an adequate model of test systems for studying xenobiotics.

A 2000-year sediment record reveals rapidly changing sedimentation and land use since the 1960s in the Upper Mara-Serengeti Ecosystem

The Mara River basin is a trans-boundary basin of international importance. It forms the headwaters of the Nile River and serves as the primary dry season water source for an estimated 1.1 million rural people and the largest remaining overland migration of 1.4 million wildebeest in the Serengeti-Mara Ecosystem. Changes throughout the basin are impacting the quantity and quality of the Mara River, yet the historical context of environmental conditions in the basin is not well known. We collected sediment cores throughout the wetland at the mouth of the Mara River, and we used isotopic dating methods and a suite of analyses to examine historical patterns of sediment quantity and source, mercury contamination, and carbon and nutrient loading. Our results show that ecological conditions in the Mara River basin were fairly stable over paleoecological time scales (2000–1000 years before present), but there has been a period of rapid change in the basin over the last 250 years, particularly since the 1960s. A shift in the source and quantity of sediments in the river began in the late 1700s and became much more pronounced in the 1950s and 1960s, coincident with increasing mercury concentrations. The quantity of sediment from the Upper Mara increased, particularly since 1960, but the proportion of total sediment from this region decreased as the Talek and Middle Mara portions of the basin began producing more sediment. The decadal oscillation in sediment accumulation was congruent with known periods of extreme precipitation events. Carbon and nitrogen loading also increased since the 1960s, and the shift in the isotopic ratio of nitrogen provides evidence for increased anthropogenic loading. Altogether, these data likely reflect patterns of change also experienced in other basins throughout East Africa.