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The application of analytical chemistry to the exploration of the World Cultural Heritage represents a major challenge in that most protocols and strategies are invasive and require micro-sampling. We report a novel methodology for harvesting material deposited on the surface of ancient documents while avoiding their damage or contamination. The technology here described relates to the capture of metals on these specimens. It is based on the use of plastic films (ethylene vinyl acetate, EVA) impregnated with different metal chelators (sodium 2,3-dimercapto-1-propanesulfonate, DMPS, meso-2,3-dimercaptosuccinic acid, DMSA and ethylene diamino tetra acetic acid, EDTA, as calcium salt), for harvesting from surfaces of different supports potential traces of metals therein deposited. The EVA film technology has been used to explore the pages of a manuscript written by Kepler concerning the movements of the moon and catalogued under the title "Hipparchus" at the Archives of the Russian Academy of Sciences (St. Petersburg branch). The EVA-based chelating diskettes were able to capture very significant amounts of different metals, namely: Au, Ag, Hg, As, Pb, suggesting that Kepler, well known as astronomer, astrologist, mathematician and Lutheran theologian, might have started practicing alchemy, a pseudo-chemical science he had learned from his colleague Tycho Brahe in Prague. Image 1 • The EVA film technology for monitoring traces of past life in manuscripts. • An Eva diskette with chelating agents for harvesting metals. • As, Pb, Ag, Au, Hg metal quantitation discovers potential Kepler's work on alchemy. • Four types of EVA films expand our ability of exploring the World Cultural Heritage. [ABSTRACT FROM AUTHOR]

We examined the temporal variation of heavy metals in different sexes of three brackish water shrimp species with emphasis on the relationship between Fulton's K condition indices and metal pollution index (MPI). Zn was the most abundant metal followed by Sn, though levels were below the admissible limits (irrespective of gender). Temporal variation of Zn and Pb was significant (p < 0.01). Drier weather conditions influenced Pb accumulation. Temporal variation of Sn was insignificant (p > 0.05), but temporal variation of Hg was significant only in Penaeus monodon (p < 0.0001). However, the relationship between temporal variation of the above-mentioned metals and gender was insignificant except in Penaeus semisulcatus for Pb (p < 0.02) and Sn (p < 0.04) despite no consistent higher bioaccumulation pattern by one particular sex. There were no significant negative correlations between the Fulton's K condition indices and MPI values in the different sexes. MPI values between the two sexes were insignificant. Any differences in the MPI values between the three species were insignificant. Only Penaeus semisulcatus exhibited significant differences (p < 0.022) in Fulton's K condition indices in relation to gender. Fulton's K condition indices are unreliable indicators of metal-induced stress levels in shrimps. [ABSTRACT FROM AUTHOR]

Mercury is a potent neurotoxin. Its main source of entry into the human body is the consumption of fish and seafood. Within the past few decades a new species of crab has appeared in the food web of the southern Baltic: Rhithropanopeus harrisii. The aim of the present study was to estimate the level of total and labile mercury concentrations in this species collected from the southern Baltic Sea. Analyses were performed using the thermodesorption method. The share of organic mercury fraction, as well as the Hgtot, increased with the size class of the crabs. Due to the increasingly common occurrence of R. harrisii and the low Hg TOT concentration in its body, and assuming that it is bound to become a more and more common component of the diet of fish, it can be supposed that the load of toxic mercury entering the food web is likely to decrease. • Hg in the non-native Harris mud crab from southern Baltic was at a low level. • Younger Rhithropanopeus harrisii have less toxic forms of mercury. • R. harrisii as a food introduces smaller load of Hg into food chain. [ABSTRACT FROM AUTHOR]

Anomalously cold conditions in the tropical Pacific, related to a strong La Niña event, affected numerous countries in 2010. Several areas in Colombia were severely impacted, including agricultural fields in La Mojana floodplain that were completely flooded for almost 2 years. This study assesses the effects of flooding on the levels, spatial distribution, and sources of trace metals in 222 agricultural topsoils of this floodplain. Our results show that mean concentrations of Cu 48.4 mg kg−1 (11–103 mg kg−1), Zn 79.2 mg kg−1 (6–207 mg kg−1), Ni 58.1 mg kg−1 (17–101 mg kg−1), Pb 3.2 mg kg−1 (0.13–14 mg kg−1), Cd 0.56 mg kg−1 (0.05–1.4 mg kg−1), Mn 411 mg kg−1 (55–1,277 mg kg−1), and Hg 0.10 mg kg−1 (0.05–0.22 mg kg−1) were higher than the world's averages. Topsoils revealed different degrees of pollution depending on the metal, of which Pb was the most problematic element, with 82% of the soil samples classified as heavily contaminated. Principal component analysis suggests that soil contamination was primarily derived from poor agricultural practices and contaminated river overflows from upstream mining areas. Our results show that an extreme flood event might increase the bioavailability of metals (especially Pb) for crops in most (66%) of the agricultural soils, posing a potential threat to human health. [ABSTRACT FROM AUTHOR]

The spatiotemporal trends of mercury (Hg) are crucial for the understanding of this ubiquitous and toxic contaminant. However, uncertainties often arise from comparison among studies using different species, analytical and statistical methods. The long-term temporal trends of Hg exposure were reconstructed for a key sentinel species, the white-tailed eagle (Haliaeetus albicilla). Body feathers were sampled from museum collections covering 150 years in time (from 1866 to 2015) from West Greenland (n = 124), Norway (n = 102), and Sweden (n = 87). A significant non-linear trend was observed in the Norwegian subpopulation, with a 60% increase in exposure occurring from 1866 to 1957 followed by a 40% decline until 2015. In the Swedish subpopulation, studied at a later period, the Hg exposure showed a drastic decline of 70% from 1967 to 2011. In contrast, no significant trend could be observed in the Greenland subpopulation. The additional analysis of dietary proxies (δ 13C and δ 15N) in general increased performance of the temporal trend models, but this was dependent on the subpopulation and study period. The downward trend of Hg coincided with the decreasing δ 13C and δ 15N in the Norwegian subpopulation, suggesting a potential dietary mitigation of Hg contamination. Hg exposure in both the Greenland and Norwegian subpopulations was consistently below the suggested threshold for adverse health effects (40.0 μg g−1), while the maximum exposure in the Swedish subpopulation was distinctively elevated (median: 46.0 μg g−1) and still remains well above natural background concentrations (maximum 5.0 μg g−1). Unlabelled Image • 150 y of Hg exposure using feathers were reconstructed for white-tailed eagle. • Significant trends in feathers of Norwegian and Swedish eagles were observed. • For Greenland individuals had higher concentrations recently. • Distinctively higher concentrations were present in the Swedish subpopulation. • Decreasing Hg, δ 13C, and δ 15N were found for the Norwegian subpopulation. [ABSTRACT FROM AUTHOR]

The presence of mercury (Hg) in the environment is a major concern because mercury is toxic for living organisms. Estimating the Hg toxicity of environmental samples is difficult because contaminants occur in pools of various bioavailabilities, and thus, measuring the total concentration of a contaminant rarely reflects the real toxicity and risk. There is therefore a need to design advanced methods to measure the bioavailable fraction of the contaminants. Here, we used the diffusive gradient in thin films (DGT) method to determine the bioavailability of Hg in agricultural soils containing 0.02 and 0.64 mg kg−1 of Hg. Specifically, we used homemade manufactured open and restricted diffusive layers to distinguish between inorganic and organic bioavailable Hg species in soil. The findings demonstrate for the first time the successful use of restricted gel for the determination of inorganic Hg species in soil. Moreover, a model program has been used to calculate the effective concentration for predicting Hg concentration uptake by plants. For this purpose, lettuces were planted in soils to assess Hg soil-to-plant transfer. Concentrations of Hg obtained by DGT measurements in soils matched the Hg concentration found in lettuce roots, thus confirming the effectiveness of this technique in predicting Hg uptake by plants. [ABSTRACT FROM AUTHOR]

Human activities in cities affect properties of urban soils. In particular, urban soils often contain high contents of harmful metals even in deeper horizons added to them from diverse sources over centuries of the city development. This is reflected in complex distribution of metals in bulk soils with depth and the complex metal fractionation, but the exact sources of the metals are difficult to identify. This is also the situation in soils from Wroclaw, one of the largest cities in Poland. Potentially harmful elements Pb, Cd and Hg were examined in six profiles located along the major communication route and compared to two non-urban soils profiles located close to the same route. In all of the urban profiles, Pb and Cd exceeded the element contents observed in non-urban profiles and showed an erratic distribution compared to the more predictable one in non-urban soils. The differences between urban and non-urban profiles were explained as the result of contamination coming from more pollution sources in the case of urban soils, the conclusion supported by Pb isotope analyses. In fact, Pb isotopes showed that the contamination sources in urban soils included leaded petrol, coal combustion, smelting and possibly old pre-industrial ore processing, whereas leaded petrol and pre-industrial lead were the only possible anthropogenic sources in non-urban soils. The comparison of Wrocöaw soils with those from cities of comparable size Kraków and Poznań show similar ranges of metal contents with implication that urban pollution oversteps diverse geogenic chemical background. On the other hand, the comparison with other European cities show large variability in metal contents and suggest that urban soils contamination is time integrated and reflects long-term industrial evolution of each country. [ABSTRACT FROM AUTHOR]

Concentrations of mercury (Hg) were examined in the blood of mute swans from rural breeding sites and urban wintering areas in southern parts of Poland, Europe. The birds were classified into three age groups: cygnets, juveniles and adults. To investigate the potential impact of Hg on birds, hematocrit (Ht), reduced glutathione (GSH) levels and morphometric measurements were taken. Using morphometric parameters, we stated that all mute swans sampled were in good condition. The mercury concentrations found were rather low and differed between birds from industrialized wintering areas and rural breeding areas (means 7 ng/mL and 2 ng/mL, respectively). We found no difference in Hg concentrations between the sexes, but concentrations varied significantly between age groups (cygnets 2 ng/mL, juveniles 7 ng/mL and adults 6 ng/mL). A similar trend was observed for hematocrit levels. GSH levels did not differ between any of the groups studied. We found no significant relationship between blood parameters (Ht, GSH) in relation to Hg concentrations. We conclude that the Hg concentrations in blood may be influenced by industrialization, season and age, but generally low concentration such as those found by us do not affect Ht and GSH levels. Image 1 • Blood Hg concentrations found were generally low. • Blood parameters (Ht, GSH and Hg levels) did not differ in respect of sex. • Only levels of Ht and Hg differed according to age group (the lowest in cygnets). • No correlations were found between the blood parameters studied. Variability of low mercury levels in blood of mute swans is linked to age and season factors, but it is unrelated to blood parameters and sex. [ABSTRACT FROM AUTHOR]

The overall aim of the present study was to assess human exposure to environmental contaminants from consumption of harbour seal (Phoca vitulina) meat in the southwestern Baltic Sea. For this purpose, muscle tissue from harbour seals (n = 27) was sampled from Danish locations in the period 2005–2015 and analysed for concentrations of total mercury (Hg), organochlorine contaminants such as polychlorinated biphenyls (PCBs) and organochlorine pesticides as well as perfluoroalkyl substances (PFAS) with particular focus on perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA). Hg, ∑PCB, PFOS and PFOA concentrations in the muscle tissue ranged between 0.27 and 4.76 μg g−1 wet weight (ww; mean: 1.38 μg g−1 ww, n = 27), 12.2–137 ng g−1 ww (mean: 47.5 ng g−1 ww, n = 10), 6.95–33.6 ng g−1 ww (mean: 15.8 ng g−1 ww, n = 10) and 0.16–0.55 ng g−1 ww (mean: 0.28 ng g−1 ww, n = 10), respectively. We compared the concentrations with literature-derived human tolerable weekly intake (TWI) values for mercury (1.3 μg kg−1 week−1), ∑PCB (2.1 μg kg−1 week−1), PFOS (0.013 μg kg−1 week−1) and PFOA (0.006 μg kg−1 week−1). The comparisons showed that the weekly consumption of harbour seal meat by children (weighing 30 kg), women (weighing 60 kg) and men (weighing 80 kg) should not exceed 28, 57 and 76 g (for Hg), 1.3, 2.7 and 3.5 kg (for ∑PCB), 25, 50 and 67 g (for PFOS) and 640, 1290 and 1720 g (for PFOA). In conclusion, Hg and PFOS are the contaminants of most importance in seal meat from this area with respect to existing tolerable intake rates and risks of adverse human health effects. • Human exposure to Hg, PCBs and PFOS in harbour seal meat was assessed. • Weekly consumption of harbour seal meat should not exceed 28–76 g for Hg. • The results show that it was 1.3–3.5 kg for ∑PCB. • For PFOS it was 25–67 g and for PFOA 640–1720 g. • This shows that Hg and PFOS are the contaminants with highest risks of human health effects. [ABSTRACT FROM AUTHOR]

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BACKGROUND: Crude oil had a great influence on the determination of mercury and arsenic in oil-bearing cores by Atomic Fluorescence Spectrometry. At present, the main methods of removing organic matter such as crude oil are high-temperature firing and high-temperature oxidation with strong acid. In these methods, high reaction temperature will cause loss of mercury and arsenic, resulting in lower results. OBJECTIVES: To develop a separation method with low operating temperature. METHODS: Mercury and arsenic in oil-bearing cores were determined by Atomic Fluorescence Spectrometry with Soxhlet extraction at a low temperature for this method of 75°C and the remaining part was decomposed by 50% aqua regia. RESULTS:The detection limits were 0.003mg/kg and 0.10mg/kg for mercury and arsenic, respectively. The relative standard deviations were 7.3% and 5.1%, respectively. The relative standard deviation of mercury decreased from 33.0% to 7.3%, and the relative standard deviation of arsenic decreased from 25.0% to 5.1%. The recoveries of standard addition were greater than 92.5%. CONCLUSIONS: Compared with traditional methods, this method avoided the problems of insufficient contact between samples and aqua regia due to the hydrophobicity of crude oil, incomplete decomposition of samples and mercury loss due to excessive reaction temperature. The proposed method provides a reference for the determination of other elements in oil-bearing cores. [ABSTRACT FROM AUTHOR]

Atmospheric particulate-bound mercury (PBM) plays an important role in the geochemical cycling of mercury (Hg). This study reviewed research progress of the PBM, including the possible emission and deposition pathways, measurement methods and the global distribution. The primary PBM sources are anthropogenic sources, but natural sources could be also a considerable contributor, for instance, chemical transport and dust in the arid and desert area. Different filter methods, such as quartz fibre filters, have been applied to the PBM measurement, and PBM can also be real-time monitored automatically. Generally, the average PBM concentrations were higher in the Northern Hemisphere than in the Southern Hemisphere. However, the PBM level of Antarctica is quite high. PBM concentrations were higher in the urban areas than in the remote areas, and there was a high PBM level in the developing countries. Moreover, high PBM concentrations were observed in the range 20°–60° of northern latitude. [ABSTRACT FROM AUTHOR]

Total mercury (THg) and monomethylmercury (MMHg) concentrations as well as mercury (Hg) isotope ratios were determined in sediment cores sampled from six locations from the Canadian Arctic Archipelago (CAA). At most sites, THg concentrations showed a decreasing trend with depth, ranging from 5 to 61 ng/g, implicating possible increased Hg deposition and/or riverine inputs in top sediment layers. MMHg values showed large oscillations within the top 10 cm of the cores. This variability decreased at the bottom of the cores with MMHg concentrations ranging from less than12 to up to 1073 pg/g. Average concentrations of THg and MMHg in the top 10 cm were linearly correlated, whereas no correlation was observed with organic matter (loss on ignition). Mercury isotope ratios showed negative values for both δ202Hg (−1.59 to −0.55‰) and Δ199Hg (−0.62 to −0.01‰). δ202Hg values became more negative with depth, while the opposite was observed for Δ199Hg. The former is consistent with predicted historical atmospheric Hg trends as a result of increased coal burning worldwide. Hg isotope ratio measurements in CAA sediments offer additional opportunities to trace Hg processes and sources in the Arctic. Unlabelled Image • Hg, MMHg, and Hg isotope ratios were determined in sediments from Canadian Arctic. • Hg concentrations showed a decreasing trend with depth, ranging from 5 to 61 ng/g. • MMHg values showed large oscillations within the top 10 cm of the cores. • MMHg concentrations appeared to be impacted by a range of processes. • Hg isotope ratios indicate inputs from global coal use. [ABSTRACT FROM AUTHOR]

Abstract We investigated the temporal trend of mercury (Hg) in arctic foxes from Svalbard, Norway sampled in the period 1997–2014 (n = 109, from 11 trapping seasons). We used linear models to investigate the effect of trapping season, feeding habits (δ 13C), food availability from marine and terrestrial ecosystems (reindeer carcasses and sea ice cover), sex, age and body condition on liver total Hg (THg) levels. Liver THg levels increased in arctic foxes with 7.2% (95% CI: 2.3, 9.6) per year when the concentrations were adjusted for variation of δ 13C, sea ice cover, and reindeer carcasses, whereas the raw annual trend was 3.5% (CI: −0.11, 7.2). However, the THg levels in arctic foxes from Svalbard are still lower than other marine mammals. We also demonstrate that arctic fox terrestrial food consumption is important for lowering the overall THg levels in this species. Graphical abstract Unlabelled Image Highlights • We analyzed liver concentrations of THg in 109 arctic foxes from Svalbard. • THg levels in arctic foxes increased with 7.2% per year from 1997 to 2014. • The increase in THg per year is lower than in other Arctic regions. • Terrestrial food consumption reduced THg levels in arctic foxes. [ABSTRACT FROM AUTHOR]

Abstract Biotic mercury (Hg) methylation appears to depend on factors such as microbial activity and the concentration and bioavailability of Hg2+ to the Hg-methylating organisms. Recently, the presence of cyanobacteria has been linked with high methylmercury (MeHg) concentrations. The aim of this work was to test MeHg production in microcosms, in relation to the amount of periphytic cyanobacteria, dissolved organic matter (DOM) and phosphorus concentrations, as well as periphytic primary production rates. Water and periphyton samples were collected for cultivation and isolation of cyanobacteria from the Guaporé River floodplain, Brazil. We cultivated the periphyton in microcosms with different concentrations of cyanobacteria, total phosphorus and DOM. The highest net MeHg production (6.8 to 24.6% of added Hg d−1) occurred in the microcosm with added cyanobacteria, followed by microcosms with added phosphorus (6.1 to 11.4%) and added DOM (6.4 to 9.1%). Positive correlations were found between MeHg production, addition of cyanobacteria, phosphorus and DOM and periphytic primary productivity. Our results bring the first direct experimental evidence of the relevance of cyanobacteria and primary production as regulators of MeHg production in periphyton. These findings have numerous implications for the management of natural and engineered wetlands. Graphical abstract Unlabelled Image Highlights • highest MeHg production in periphyton microcosms with added cyanobacteria • the highest net MeHg production in microcosms followed the order DOM > P > cyanobacteria • positive correlation between MeHg production and primary productivity • cyanobacteria regulate MeHg production in wetlands [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the toxic effects of mercury (Hg) and silver nanoparticles (AgNP) on histopathologic damage, mercury accumulation, and behavior pattern of common carp (Cyprinus carpio). In this regard, the fish were divided into six groups of Hg (one concentration), AgNPs (two concentrations), and Hg + AgNPs mixture (two concentrations) and one control group. Histopathological anomalies of various tissues of common carp was investigated using hematoxylin-eosin method. In this study, some histopathological changes in the intestine of carp such as degeneration, hemorrhage, increase in the number of goblet cells, and necrosis in the chemicals tested during different periods are observed. Moreover, results showed that the mercury uptake in tissues of common carp was increased in the presence of silver nanoparticles, so that the highest uptake of mercury in tissues was in gill tissues. In conclusion, the results indicated that the silver nanoparticles enhanced the toxicity and uptake of mercury in tissues of carp. [ABSTRACT FROM AUTHOR]

Heavy metals are naturally embedded in aquatic environment, but their levels are increasing due to industrial, agricultural and mining activities. Mercury (Hg) and lead (Pb) are two of the most common toxicants that can be found in aquatic environment. Behavioural and neurological changes are associated with overexposure to Hg poisoning, while Pb might cause high blood pressure and damage to the reproductive organs. Fish is a common table food consumed by humans for protein nourishment; therefore, it is important to study heavy metal contamination in it. The aim of the present work was therefore to determine the content of Hg and Pb in milkfish (Chanos chanos Forsk) from Pampang fishponds, Makassar, Indonesia. Dithizone was used as the reagent for the qualitative analysis of Hg, while KCN was used for Pb. Quantitative analysis performed by Atomic Absorption Spectrophotometry at 253.5 nm for Hg and 283.3 nm for Pb confirmed the presence of Hg and Pb. The results showed that the average content of Hg in milkfish was 1.01 μg/g while Pb was undetected. Therefore, it could be concluded that milkfish from the Pampang fishponds were contaminated with Hg thus poses high risk for human health. [ABSTRACT FROM AUTHOR]

Total (all forms of inorganic and organic) concentrations of mercury (Hg) and selenium (Se) were measured in dorsal muscle and eggs of wild fishes from two shallow lakes in China: Tai Lake (Ch: Taihu; TL) and Baiyangdian Lake (BYDL). Hazard quotients (HQs) were calculated by dividing concentrations of Se or Hg in muscle or eggs of fishes by threshold concentrations for effects expressed as tissue residue toxicity reference values (TR-TRVs). Concentrations of Hg in whole bodies of fishes were estimated by concentrations in muscle. Based on concentrations of Hg in whole body, HQs for fishes in TL and BYDL were less than 1.0, which suggests little to moderate potential for effects on these fishes and unaccepted adverse effects of Hg are unexpected for adult fishes. HQs of Se in muscle of common carp from TL were closed to 1.0, and 27% of HQs based on concentrations of Hg in eggs of fishes from BYDL exceeded 1.0. Potential hazard due to Hg on common carp in TL and reproductive effects of Se on fishes from BYDL exhibited need for concern. Ratios of molar concentrations of Se to Hg were greater than 1.0. Thus, there might be some protective effects of Se on effects of Hg on fishes in TL and BYDL. [ABSTRACT FROM AUTHOR]

• NO and Hg conversion using a spiral SDBD reactor were investigated. • The Hg conversion was largely dependent on the existence of O 2. • C 2 H 4 inhibited the Hg capture but boosted the conversion of NO. • SO 2 , H 2 O and CO 2 decreased Hg and NO conversion significantly. A spiral Surface Dielectric Barrier Discharge reactor was employed to remove both NO and Hg from the flue gas. The effects of O 2 and peak voltage were extensively studied. Only NO, NO 2 and N 2 O were observed using FTIR at the outlet of the reactor in the atmosphere of NO/O 2 /N 2. A desired NO conversion efficiency of 99.2% at 7 kV was obtained in the absence of O 2 with low energy cost. The presence of O 2 can suppress the reduction reaction while accelerating the oxidization of NO, consequently restraining the NO reduction to N 2 and promoting the NO 2 generation. O 2 is necessary for the oxidation of Hg. At peak voltage of 7.0 kV, the Hg conversion reached above 94% at O 2 concentration higher than 4%. It decreased to lower than 55% at 3.5 kV. Different concentrations of CO 2 , C 2 H 4 , SO 2 , HCl and H 2 O were also introduced to study their effect on NO and Hg conversions. When the CO 2 concentration was increased from 0% to 5 and 10%, the NO conversion decreased from 81.0% to 74.1% and 73.6% respectively. At peak voltage of 7 kV and 500 ppm and 1000 ppm of C 2 H 4 were introduced, the NO conversion increased from 78.7% to 85.4% and 93.8% accordingly, while Hg removal efficiency declined. With HCl concentration increasing to 30 and 60 ppm, the Hg oxidation rate increased significantly to above 90% at peak voltage of 9 kV. A strong inhibition effect of SO 2 and H 2 O on NO and Hg conversion were observed. [ABSTRACT FROM AUTHOR]

Abstract Mercury (Hg) is one of the primary health concerns in natural and urbanised environments due to past and present natural and anthropogenic emissions. Its environmental cycle is driven by redox reactions, microbial metabolism and organic matter (OM) interactions, which may all lead to formation of bioaccumulative organic Hg species; methylmercury (MeHg), with damaging consequences for human and ecosystem health. Hence, Hg lability and bioavailability has been the focus of many investigations and assessed with a variety of chemical proxies in order to improve understanding of the conditions that lead to enhanced bioavailability of Hg and its species. We investigated Hg labile species with Diffusive Gradient in Thin-film technique (DGT) in the water column and sediment of Zenne River (Brussels, Belgium) and Gulf of Trieste (North Adriatic). They represent two contemporary important Hg-impacted areas; the former by anthropogenic urban pollution, and the latter by historic pollution from Hg mining. Hg speciation of labile inorganic and methylmercury in these two environments was not yet investigated using DGT technique. The results show labile Hg species changing with season in the water column of Zenne River, while the sediments are the source of bioavailable MeHg to the water column that is transported further creating a halo effect in the region. Values of labile Hg species for water column and sediments in Gulf of Trieste differ from previous research, highlighting the need for more investigation into Hg bioavailability. MeHg/THg ratios were compared to other sampling methods for labile Hg species. Graphical abstract Unlabelled Image Highlights • Labile Hg species were measured using a Diffusive Gradient in Thin-film technique. • DGTs were used in the Zenne River Brussels and Gulf of Trieste (North Adriatic). • Winter-time THg in Zenne is highly labile and mobilized far from its source. • MeHg/THg% in Gulf showed higher labile Hg bioavailability than previously thought. • Labile MeHg in the sediment of the Gulf represents up to 75% of total labile Hg. [ABSTRACT FROM AUTHOR]

A spiral Surface Dielectric Barrier Discharge reactor was employed to remove both NO and Hg from the flue gas. The effects of O2 and peak voltage were extensively studied. Only NO, NO2 and N2O were observed using FTIR at the outlet of the reactor in the atmosphere of NO/O2/N2. A desired NO conversion efficiency of 99.2% at 7 kV was obtained in the absence of O2 with low energy cost. The presence of O2 can suppress the reduction reaction while accelerating the oxidization of NO, consequently restraining the NO reduction to N2 and promoting the NO2 generation. O2 is necessary for the oxidation of Hg. At peak voltage of 7.0 kV, the Hg conversion reached above 94% at O2 concentration higher than 4%. It decreased to lower than 55% at 3.5 kV. Different concentrations of CO2, C2H2, SO2, HCl and H2O were also introduced to study their effect on NO and Hg conversions. When the CO2 concentration was increased from 0% to 5 and 10%, the NO conversion decreased from 81.0% to 74.1% and 73.6% respectively. At peak voltage of 7kV and 500ppm and 1000 ppm of C2H2 were introduced, the NO conversion increased from 78.7% to 85.4% and 93.8% accordingly, while Hg removal efficiency declined. With HCI concentration increasing to 30 and 60 ppm, the Hg oxidation rate increased significantly to above 90% at peak voltage of 9kV. A strong inhibition effect of SO2 and H2O on NO and Hg conversion were observed. [ABSTRACT FROM AUTHOR]

Background: Diabetes mellitus (DM) is linked to an increased risk of lung cancer; however, the exact molecular basis is unclear. Methods: We used a microarray method and found a group of microRNAs differently expressed in lung cancer cells at high or low glucose treatment. Results: Among these, miR‐194 changed significantly, which indicated further analysis. miR‐194 was significantly downregulated in non‐small cell lung cancer (NSCLC) cells cultured in high glucose (HG) medium and clinical NSCLC tissues with DM. The introduction of miR‐194 significantly suppressed the proliferation, migration, and invasion of lung cancer cells induced by HG, suggesting that miR‐194 may be a suppressor during HG‐induced NSCLC progression. Further analysis indicated that NFAT5 was a direct target gene of miR‐194, evidenced by the direct binding of miR‐194 with the 3'untranslated region of NFAT5. MiR‐194 could decrease the expression of NFAT5 at both messenger RNA and protein levels, while overexpression of NFAT5 reversed the decreased proliferation, migration, and invasion ability mediated by miR‐194 in lung cancer cells. Conclusion: Our findings provide new insight into the mechanism of NSCLC progression. Therapeutically, miR‐194 may serve as a potential target for the treatment of lung cancer patients with DM. [ABSTRACT FROM AUTHOR]

Research on mercury (Hg) in aquatic ecosystems in China has focused mainly on fish, with little research on the base of the food chain and Hg bioaccumulation mechanisms. This paper summarizes research progress pertaining to the characteristics, current status, and trends of Hg accumulation in the aquatic food chain in China, analyzes the effects of human activities on the transmission and accumulation of Hg in aquatic food chains, and assesses their risks to human and ecosystem health. A comparison of fish samples in China between 2000 and 2018 indicates that their total Hg content remains at relatively safe levels. However, because current information is generally insufficient to confirm how anthropogenic activities affect transformation and bioaccumulation in the aqueous environment, Hg isotope studies should be a focus of research on aquatic food webs. Additionally, more attention should be paid to Hg transport and bioaccumulation in the basic food chain by focusing on multi-contaminant joint exposure studies and establishing Hg bio-transport models. [ABSTRACT FROM AUTHOR]

Many studies have suggested that organic matter (OM) substantially reduces the bioavailability and risks of mercury (Hg) in soils and sediments; however, recent reports have supported that OM greatly accelerates Hg methylation and increases the risks of Hg exposure. This study aims to summarize the interactions between Hg and OM in soils and sediments and improve our understanding of the effects of OM on Hg methylation. The results show that OM characteristics, promotion of the activity of Hg-methylating microbial communities, and the microbial availability of Hg accounted for the acceleration of Hg methylation which increases the risk of Hg exposure. These three key aspects were driven by multiple factors, including the types and content of OM, Hg speciation, desorption and dissolution kinetics and environmental conditions. [ABSTRACT FROM AUTHOR]

Although reservoir creation increases fish mercury (Hg) concentrations, little information exists on its effects on Hg concentrations in aquatic mammals. River otters (Lontra canadensis) and American mink (Neovison vison) are two aquatic mammals that have been used as model species for assessing Hg bioaccumulation in aquatic systems. We assessed Hg and selenium (Se) concentrations in these two species within and outside of the Williston Reservoir (Peace-Williston (PW) watershed) in northern British Columbia (BC) and used these data to investigate potential explanatory factors (i.e., watershed, gender, trophic level (δ15N), and regional geology) influencing Hg concentrations. Hg concentrations in otter and mink inhabiting the Mackenzie watershed (outside the PW) were significantly lower than other watersheds in Northern BC. The general trend was the same for both species; the Peace-Williston having the highest and Mackenzie having the lowest Hg concentrations. For mink, the Peace-Williston watershed, higher trophic levels, and higher proportions of igneous/metamorphic bedrock were all significant influences on higher Hg concentrations (logistic regression). Higher trophic levels or proportions of of igneous/metamorphic bedrock, however, were not directly associated with the PW watershed suggesting there may be an impoundment effect. Baseline data on natural Hg inputs before planned anthropogenic changes occur is a critical first step to aiding interpretations of Hg-related effects on wildlife populations and their related ecosystems. [ABSTRACT FROM AUTHOR]

Abstract Total mercury (Hg) and methylmercury (MeHg) circulation in a connected river-floodplain system composed of two black water (a small forest river, igarapé , and Cuniã Lake) and a white water body (Madeira River), located in the Madeira River Basin were evaluated during the rising-water, early and late falling-water periods. We assessed organic matter (C and N composition, (C:N) a ; and δ13C isotopic signature), and physical and chemical influences (pH, dissolved O 2 , electric conductivity) in relationship to Hg and MeHg concentrations. Hg and MeHg concentrations in a sediment profile and three aquatic macrophytes (E. crassipes , E. azuera and Oryza sp.) were measured. Igarapé and Cuniã Lake showed higher Hg and MeHg concentrations (115–709; 10–25 ng g−1) in the suspended particulate matter compared (SPM) compared to the Madeira River (Hg: 5–16; MeHg: 0.2–0.3 ng g−1), partially independent of seasonality (p = 0.06). Total Hg had higher affinity for the SPM (1.75 times) than for dissolved organic matter. Organic matter characteristics correlated with MeHg concentrations (δ13C and (C:N) a ; r2 = 0.79; p < 0.0001), as well as physical and chemical parameters of the water column (dissolved O 2 and pH; r2 = 0.80; p < 0.0001), demonstrating that physical and chemical changes between the river-floodplain system affect MeHg circulation and production. The inverse correlation of MeHg and SO 4 2− concentrations (r2 = 0.73; p < 0.0001) suggests the action of sulfate-reducing bacteria. Total Hg and MeHg concentrations as well as %MeHg were detected in the sediment profile (Hg: 24–51; MeHg: 0.6–3.2 ng g−1; %MeHg: 1.8–6.2) and aquatic macrophytes (Hg: 1–30; MeHg: 0.3–7.5 ng g−1; %MeHg: 1.6–33.7). We conclude that the highest Hg and MeHg concentrations in Cuniã Lake, compared to the Madeira River, are due to the physical and chemical differences between these environments. Graphical abstract Unlabelled Image Highlights • Alluvial floodplains in the Amazon region have a complex Hg biogeochemical cycle. • Here floodplains had higher Hg and MeHg concentrations relative to Madeira River. • 13C-isotope and (C:N) ratios were useful for predicting MeHg concentrations. • Total Hg showed higher affinity for the SPM than for the dissolved matter. • Aquatic macrophyte and sediment MeHg demonstrated transfer from sediment to biota. [ABSTRACT FROM AUTHOR]

Abstract Due to its biomagnification mercury (Hg) is an element of concern especially in the remote pristine ecosystems such as Antarctica. Despite the sensitivity of the region, there is still a limited knowledge about the influence of natural processes, i.e. volcanism, climate, atmospheric mercury depletion events or freeze-thawing cycles, on the Hg cycle in Antarctica. We analysed total Hg and solid phase Hg species (Hg-thermo–desorption-AAS) in 1600 years old sediments from Limnopolar Lake (Byers Peninsula, South Shetland Islands). Some sections of the core show unusual high Hg concentrations (1141–11286 ng g−1) and accumulation rates (310–4902 µg m−2 yr−1). Hg-thermo-desorption analyses indicate that Hg is bound in the sediment by organic matter of different degree of degradation. We propose a combination of different natural processes to explain the high enrichment of Hg in the sediments. The nearby (30 km) Deception Island volcano appears to be the main source of Hg, while climatic conditions have controlled freezing-thawing of the ice-cover and the enrichment of Hg in the snowpack on the frozen lake (and its catchment). The release of Hg from the snowpack during thawing events appears to cause the extreme Hg enrichment in the sediments. The global atmospheric pollution is a minority signal in our record. The ∼2.2 fold increase in Hg concentrations since AD ∼ 1860 points industrial activities as the unique pollution cause. Our findings indicate that thawing of Antarctic ice might release large quantities of Hg to freshwater and marine systems and related food chains. [ABSTRACT FROM AUTHOR]

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Biochar is frequently applied for the reduction of mercury (Hg) migration in soil; however, most of the studies only focused on the adsorption capacity evaluation of fresh biochar. We investigated the Hg adsorption capacities of biochar prepared from wheat straw, corn straw, and sunflower seed shells. Biochar aging was simulated via natural aging, high-temperature aging, and freeze-thaw aging. The adsorption capacities of all the aged biochar were increased, and wheat straw biochar and seed shells biochar treated with high-temperature aging (wBC-Ha500 and sBC-Ha600) and corn straw biochar treated with freeze-thaw aging (cBC-Fta500) showed an observable improvement on the equilibrium adsorption amounts. The kinetics of the fresh biochar samples fitted the pseudo-first-order kinetic model and the pseudo-second-order kinetic model, while the kinetics of the aged biochar samples fitted the pseudo-second-order kinetic model. Biochar adsorption capacity increased with higher initial concentrations and increasing temperatures. Elemental analysis, Fourier-transform infrared spectroscopy (FT-IR) spectra, cation-exchange capacity (CEC), surface area (SA), zeta potential, and X-ray photoelectron spectroscopy (XPS) showed that the aging mechanism consisted of hydroxylation and carboxylation caused by the functional groups on the biochar surface. According to the different climatic zones in China, wheat straw biochar and seed shell biochar are suitable for the tropical zone and the subtropical zone, while corn straw biochar is more suitable for the cold and the mid-temperate zones. [ABSTRACT FROM AUTHOR]

Abstract The non-essential metal mercury (Hg) can have deleterious effects on health of organisms, and tends to bioaccumulate with age in long-lived organisms and to biomagnify along food webs. Because elasmobranchs are fished for human consumption and their Hg levels are frequently above the maximum Hg concentration recommended for fish consumption, understanding the drivers of Hg concentration is of considerable interest. Total Hg concentrations were analysed in muscle tissues of 14 shark and 2 batoid species (n = 339 individuals) sampled across multiple habitats (coastal, open ocean and bathyal) in the southwestern Indian Ocean. Stable isotope ratios of carbon (δ13C) and nitrogen (δ15N) were analysed to assess whether relative trophic position and foraging habitats affected Hg concentrations. Hg concentrations increased with δ15N and body length, highlighting the mechanisms of bioaccumulation and biomagnification in relation with the trophic position and size of the individuals. Habitats where elasmobranchs were collected also affected their Hg concentrations. Bathyal sharks had high Hg concentrations that were almost similar to those of oceanic species, despite their lower relative trophic position. Higher bioavailability of Hg due to its enhanced methylation in deeper waters was considered as the most likely explanation for this result. These results highlight that multiple factors contribute to mercury accumulation in elasmobranchs. Graphical abstract fx1 Highlights • Hg concentrations in 16 elasmobranch species from the Indian Ocean were measured. • Trophic position, habitat and length explained Hg concentrations in elasmobranchs. • Variations of CH 3 Hg levels in the water column may explain the influence of the habitat on Hg concentrations. • Ageing and food uptake may explain the higher Hg levels in larger elasmobranchs. [ABSTRACT FROM AUTHOR]

Abstract In order to accurately determine the spatial distribution of soil Hg pollution in one agricultural land, 104 topsoil samples were studied by means of three subclass agricultural lands, including vegetable field, paddy field and orchard field in the southeast of China. The method of multiple linear regression modeling combined with the spatial analysis is adopted to recognize the driving factors of soil Hg contamination in each subclass agricultural land. Consequently, corresponding spatial distribution maps of estimated soil Hg concentrations in vegetable field and paddy field are plotted. Results demonstrate greater mean soil Hg concentrations in vegetable field and paddy field over orchard field, but both of them are lower than the maximum permissible concentration in the Chinese Environmental Quality Standard for agricultural soils. In vegetable field, soil Hg concentrations are closely interrelated with chimneys which have the least distances to their around soil samples. In paddy field, both the soil sampling slopes and distances from soil samples to the nearest roads are the dominant driving factors of soil Hg concentration variance. The spatial distribution of soil Hg concentrations reveals several localized hotspots in the north for the vegetable field, while in the paddy field, spreads evenly across the space. These results suggest that while the exhaust emission from industrial chimneys might drive the contamination difference of soil Hg in vegetable field in the study area, surface runoff and traffic contamination from the roads might be other factors causing those spatial variances of soil Hg contamination in paddy field. Quantification of soil Hg concentrations in agricultural lands at subclass level may provide a more accurate basis for taking appropriate prevention and controlling action to protect agricultural soil quality and human health. Highlights • Subclass level factors driving soil Hg variation in agricultural land are identified. • Potential diffusion and transportation process of soil Hg contamination is explained. • Fine distributions of soil Hg concentration in vegetable and paddy fields are mapped. [ABSTRACT FROM AUTHOR]

Abstract Methylmercury (MeHg) transfer from water into the base of the food web (bioconcentration) and subsequent biomagnification in the aquatic food web leads to most of the MeHg in fish. But how important is bioconcentration compared to biomagnification in predicting MeHg in fish? To answer this question we reviewed articles in which MeHg concentrations in water, plankton (seston and/or zooplankton), as well as fish (planktivorous and small omnivorous fish) were reported. This yielded 32 journal articles with data from 59 aquatic ecosystems at 22 sites around the world. Although there are many case studies of particular aquatic habitats and specific geographic areas that have examined MeHg bioconcentration and biomagnification, we performed a meta-analysis of such studies. Aqueous MeHg was not a significant predictor of MeHg in fish, but MeHg in seston i.e., the base of the aquatic food web, predicted 63% of the variability in fish MeHg. The MeHg bioconcentration factors (i.e., transfer of MeHg from water to seston; BCF w-s) varied from 3 to 7 orders of magnitude across sites and correlated significantly with MeHg in fish. The MeHg biomagnification factors from zooplankton to fish varied much less (logBMF z-f , 0.75 ± 0.31), and did not significantly correlate with fish MeHg, suggesting that zooplanktivory is not as important as bioconcentration in the biomagnification of fish MeHg across the range of ecosystems represented in our meta-analysis. Partial least square (PLS) and linear regression analyses identified several environmental factors associated with increased BCF, including low dissolved organic carbon, low pH, and oligotrophy. Our study reveals the widespread importance of MeHg bioconcentration into the base of the aquatic food web for MeHg at higher trophic levels in aquatic food webs, as well as the major influences on the variability in this bioconcentration. Graphical abstract Unlabelled Image Highlights • Extensive MeHg bioaccumulation literature review and meta-analysis • MeHg bioconcentration factors at food web base predict preyfish MeHg. • DOC and trophic status influence MeHg bioconcentration factors. • MeHg concentration in water column does not predict MeHg in biota. • Conceptualization of a MeHg BCF elevator leading to a BMF staircase [ABSTRACT FROM AUTHOR]

Fish are a group of organisms that are highly sensitive to mercury (Hg) contamination of the aquatic environment. At the same time, because this element can be accumulated in tissues, it can pose a serious threat to human health. The main objective of the study was to determine the content of Hg in the muscles (HgM) and gills (HgG) of various species of fish from shallow lakes with varied physicochemical conditions. Sampling was done in 5 lakes from April to November 2012 and 2013. The concentration of Hg in fish tissues was affected by 4 variables, including ammonium nitrogen, chlorophyll-a, oxygen saturation, and temperature, and the first 2 axes explained 78.9% of total variance in Hg concentration. The concentration of Hg in muscles was widely varied depending on the fish species, and its highest concentration was observed in predatory fish such as asp and perch, while the lowest concentration of this element was found in Prussian carp, bream, and rudd. Although content of Hg increased with fish body length, in non-predatory fish this correlation was less clear. The gills of the fish contained lower concentrations of Hg than the muscles. Hg content in muscles was within acceptable weekly limits, but predatory fish consumed in large quantities by the local population may pose a potential risk for human health. [ABSTRACT FROM AUTHOR]

Surface sediments (n =85) from a 160-km river-estuarine transect of the Clyde, UK, were analysed for total mercury (Hg), saturated hydrocarbons and unresolved complex mixtures (UCMs) of hydrocarbons. Results show that sediment-Hg concentration ranges from 0.01 to 1.38mgkg–1 (mean 0.20mgkg–1) and a spatial trend in Hg-content low–high–low–high, from freshwater source, to Glasgow, to estuary, is evident. In summary, sediment-Hg content is low in the upper Clyde (mean of 0.05Hg mgkg–1), whereas sediments from the Clyde in urbanised Glasgow have higher Hg concentrations (0.04 to 1.26mgkg–1; mean 0.45mgkg–1), and the inner estuary sediments contain less Hg (mean 0.06mgkg–1). The highest mean sediment Hg (0.65mgkg–1) found in the outer estuary is attributed to historical anthropogenic activities. A significant positive Spearman correlation between Hg and total organic carbon is observed throughout the river estuary (0.86; P <0.001). Comparison with Marine Scotland guidelines suggests that no sites exceed the 1.5mgkg–1 criterion (Action Level 2); 22 fall between 0.25 and 1.5mgkg–1 dry wt. (Action Level 1) and 63 are of no immediate concern (<0.25mgkg–1 dry wt.). Saturated (n -alkane) hydrocarbons in the upper Clyde are of natural terrestrial origin. By contrast, the urbanised Glasgow reaches and outer estuary are characterised by pronounced and potentially toxic UCM concentrations in sediments (380–914mg/kg and 103–247mgkg–1, respectively), suggesting anthropogenic inputs such as biodegraded crude oil, sewage discharge and/or urban run-off. [ABSTRACT FROM AUTHOR]

Purpose: Select South Dakota, USA water bodies, including both natural lakes and man-made impoundments, were sampled and analyzed to assess mercury (Hg) dynamics and historical patterns of total Hg deposition.Materials and methods: Sediment cores were collected from seven South Dakota lakes. Mercury concentrations and flux profiles were determined using lead (210Pb) dating and sedimentation rates.Results and discussion: Most upper lake sediments contained variable heavy metal concentrations, but became more consistent with depth and age. Five of the seven lakes exhibited Hg accumulation fluxes that peaked between 1920 and 1960, while the remaining two lakes exhibited recent (1995-2009) Hg flux spikes. Historical sediment accumulation rates and Hg flux profiles demonstrate similar peak and stabilized values. Mercury in the sampled South Dakota lakes appears to emanate from watershed transport due to erosion from agricultural land use common to the Northern Great Plains.Conclusions: For sampled South Dakota lakes, watershed inputs are more significant sources of Hg than atmospheric deposition. [ABSTRACT FROM AUTHOR]

Sea ice plays a fundamental role in Arctic marine environments, by driving primary productivity and sustaining ice-associated ecosystems. Simultaneously, sea ice influences the contamination of Arctic marine organisms, by modifying contaminant cycles or their bioavailability. Changes in sea ice conditions could therefore profoundly impact the functioning of Arctic marine food webs and their contamination. Top predators such as seabirds, which are subject to bioaccumulation and biomagnification of contaminants, are particularly exposed. In this context, the present study aims to investigate the influence of sea ice and of the use of ice-derived resources on the contamination of seabirds by mercury (Hg). To this end, eggs of thick-billed murres (Brünnich's guillemots, Uria lomvia ; n = 60) were collected on Prince Leopold Island (Canadian High Arctic) during four years of varying ice conditions (2010–2013). Trophic tracers (i.e., Highly Branched Isoprenoids, HBIs – an indicator of the use of ice-derived resources; carbon and nitrogen stable isotopes – indicators of foraging habitats and trophic status), as well as total Hg concentrations were quantified. Results showed that feeding on ice-derived resources (as indicated by HBI concentrations) was positively correlated to sea ice cover, and both positively influenced Hg concentrations in murre eggs. However, when testing for the best predictor with model selection, sea ice concentration only drove Hg contamination in murres. This work provides new insights into the role of sea ice and ice-derived resources in the contamination by Hg of Arctic wildlife. Further research is now needed to better understand the relationship between sea ice and Hg contamination in Arctic biota and its underlying mechanisms, but also to identify Hg sources in rapidly changing environmental conditions in the Arctic. [Display omitted] • Trophic biomarkers and total Hg concentrations were measured in thick-billed murres. • Egg Hg concentrations were higher during icier years. • Hg concentrations were higher when murres relied heavily on ice-derived resources. • Ice concentrations were the best predictor for egg Hg contamination. [ABSTRACT FROM AUTHOR]

Swordfish (Xiphias gladius) are important marine predators facing potential mercury (Hg) contamination. This study analyzed Hg levels in swordfish muscle tissue from two Mediterranean Sea stocks. Italian specimens showed significantly higher Hg concentrations (1.4 ± 0.8 mg kg−1 ww) than Spanish ones (0.8 ± 0.5 mg kg−1 ww), with many samples exceeding EU's safety limit (1 mg kg−1 ww). Selenium (Se) content and Se:Hg ratios were examined, along with the maximum safe fish meals per month for vulnerable consumers. These results highlight the urgent need for monitoring and mitigation strategies to reduce health risks, especially for susceptible populations. [Display omitted] • Swordfish from Sicily had higher Hg content than that from Balearic Island. • Hg content above 1.0 mg kg−1 ww limit in 48 % of samples analyzed. • Fish size correlated positively with Hg content. • The Selenium Health Benefit Value (HBV Se) index indicated a 20 % consumer risk. • Suggested safe monthly swordfish meals: 0.6 for children, 1.4 for pregnant women [ABSTRACT FROM AUTHOR]

Marine sediments play a significant role as reservoirs for mercury (Hg), a bioaccumulative toxic pollutant that poses risks to human and ecosystem health. Iron (Fe) has been recognized as an influential factor in the complexation and bioavailability of Hg in sediments. However, limited studies have investigated the interactions between the chemical fractions of these elements in natural settings. This study aims to examine the fractions of Hg and Fe in sediments of the Baltic Sea, a region historically impacted by Hg pollution. The Hg fractions were determined using the thermodesorption technique, while sequential extraction was employed to identify the Fe fractions. The findings confirm the crucial role of Fe in the formation, as well as the horizontal and vertical distribution of labile and stable Hg in marine sediments. Factors such as the contribution of organic matter, the presence of reactive Fe, and Fe associated with sheet silicates emerged as significant drivers that positively influenced the content of the most labile Hg fractions, potentially affecting the mobility and bioavailability of Hg in the marine environment. • Fe fractions and sediment features explained 76% of Hg level and fraction variability. • Content of labile Hg fractions (Hg ADS1 , Hg ABS) and reactive Fe (Fe R) was proportional. • Share of labile Hg increased with the content of clay minerals and organic matter. • Organic matter inhibited precipitation of HgS and Fe sorption on sediment particles. • Hg and Fe indicated peaked sediment pollution in the second half of the 20th century. [ABSTRACT FROM AUTHOR]

In this study the transfer characteristics of mercury (Hg) from a wide range of Chinese soils to corn grain (cultivar Zhengdan 958) were investigated. Prediction models were developed for determining the Hg bioconcentration factor (BCF) of Zhengdan 958 from soil, including the soil properties, such as pH, organic matter (OM) concentration, cation exchange capacity (CEC), total nitrogen concentration (TN), total phosphorus concentration (TP), total potassium concentration (TK), and total Hg concentration (THg), using multiple stepwise regression analysis. These prediction models were applied to other non-model corn cultivars using a cross-species extrapolation approach. The results indicated that the soil pH was the most important factor associated with the transfer of Hg from soil to corn grain. Hg bioaccumulation in corn grain increased with the decreasing pH. No significant differences were found between two prediction models derived from different rates of Hg applied to the soil as HgCl2. The prediction models established in this study can be applied to other non-model corn cultivars and are useful for predicting Hg bioconcentration in corn grain and assessing the ecological risk of Hg in different soils.

An analytical method to determine tin concentrations in natural samples, by coupling atomic fluorescence spectrometry, hydride generation and flow injection system was developed. The sample digestion procedure and the conditions of hydride generation were fully optimized. The best conditions for the generation of SnH4 were obtained with NaBH4 4% (m v-1) and HCl 0.6 mol L-1. The optimized flow rates were 1.2 mL min-1 for sample, 1.2 mL min-1 for HCl and 1.6 mL min-1 for NaBH4 solution. The sample volume was 500 µL. The best acid volume for digestion of solid samples was stablished to be 3 mL HNO3 + 1 mL HCl. The accuracy of the method was established by the analysis of certified reference materials and by comparative determinations, using inductively coupled optical emission spectrometry. The approach developed was shown to offer a robust method with excellent accuracy and precision for the determination of Sn in environmental samples. Finally, the method was applied to analyse the soil, sediment and water samples, collected in area under anthropogenic activities: processing area of cassiterite in Corumbataí/SP. The obtained data indicated that there was alteration in the natural quality of the environment as a result of the activities developed in that site