Levels and determinants of urinary and blood metals in the geothermal area of Mt. Amiata in Tuscany (Italy).

Natural sources and anthropogenic activities are responsible for the widespread presence of heavy metals in the environment in the volcanic and geothermal area of Mt. Amiata (Tuscany, Italy). This study evaluates the extent of the population exposure to metals and describes the major individual and environmental determinants. A human biomonitoring survey was carried out to determine the concentrations of arsenic (As), mercury (Hg), thallium (Tl), antimony (Sb), cadmium (Cd), nickel (Ni), chromium (Cr), cobalt (Co), vanadium (V), and manganese (Mn). The associations between socio-demographics, lifestyle, diet, environmental exposure, and metal concentrations were evaluated using multiple log-linear regression models, adjusted for urinary creatinine. A total of 2034 urine and blood samples were collected. Adjusted geometric averages were higher in women (except for blood Hg) and younger subjects (except for Tl and Cd). Smoking was associated with Cd, As, and V. Some dietary habits (rice, fish, and wine consumption) were associated with As, Hg, Co, and Ni. Amalgam dental fillings and contact lenses were associated with Hg levels, piercing with As, Co, and Ni. Among environmental determinants, urinary As levels were higher in subjects using the aqueduct water for drinking/cooking. The consumption of locally grown fruits and vegetables was associated with Hg, Tl, and Co. Exposure to geothermal plant emissions was associated only with Tl.

Pollution levels and risk assessment of thallium in Chinese surface water and sediments.

Thallium (Tl) is one of the most toxic metals and can cause chronic and acute damage to humans. Due to occurrences of incidents involving Tl pollution in China, its potential environmental impacts are receiving increased attention. However, there is still limited information on Tl concentrations in the environment and their risks to human health and wildlife. This paper provides an overview of the contamination of surface water and sediments by Tl across China and assesses the potential risks using several methods. The acute and chronic aquatic life criteria for Tl were determined to be 13.25 and 1.65 µg/L, respectively. The acute and chronic risk quotients (RQs) of Tl in surface water near mining areas were 0.01-41.51 and 0.20-666.67, respectively, indicating medium to high ecological risks to aquatic organisms. Tl in sediments of Pearl and Gaofeng rivers pose a high risk based on the higher geo-accumulation index (Igeo) and potential ecological risk index (EI) values. Exposure parameters for the Chinese population were used to derive health criteria and assess non-carcinogenic risk posed by Tl in centralized drinking water sources. Tl criteria for protection of human health were calculated to be 0.18 µg/L for water+organisms and 0.30 µg/L for organisms only. The non-carcinogenic risk posed by Tl was acceptable. The human health criteria of Tl for children were the lowest among all age groups. The risks posed by Tl to health of children are greater than those for adults. Therefore, emphasis should be placed on protecting children from exposure to Tl. For the Chinese population, the drinking water guidance value to ensure protection of human health was determined to be 0.44 µg/L. The availability of multiple Tl guidance values for designated water uses will improve the environmental regulation and surveillance of Tl pollution in China and other countries.

Bioaccumulation of 35 metal(loid)s in organs of a freshwater mussel (Hyriopsis cumingii) and environmental implications in Poyang Lake, China.

Benthic bioaccumulation of hazardous materials has been a great challenge to the health of lake ecosystems. As representative benthic macroinvertebrates, freshwater mussels and their accumulation characteristics have been regarded as effective indicators for assessing potential risks induced by sedimentary metal(loid)s in lakes. Here we profile organ-specific accumulation of 35 metal(loid)s in a freshwater mussel (Hyriopsis cumingii) and their correlations to metal speciation in sediments of Poyang Lake, the largest lake of China. Significant organ-specific characteristics of metal accumulation were found in gills, though higher thallium (Tl) and selenium (Se) were found in the hepatopancreas, and greater arsenic (As) mostly accumulated in gonads. Pearson correlation analysis revealed that the bioaccumulation of silver (Ag), cobalt (Co), and rare earth elements (ΣREE) in gills and As in gonads were closely associated with those in bioavailable fraction of sediments. Based on the biochemical analysis in the major organs, gills exhibited the highest enzymatic activity compared with hepatopancreas and gonads. Sedimentary metals, particularly for available Ag, Co, and ΣREE, play key roles in causing lipid peroxidation in gills and significantly promote the activities of superoxide dismutase (SOD)/glutathione reductase (GR), while many metals (e.g., cadmium, manganese, Se) inhibit the glutathione (GSH) content in gonads and hepatopancreas. Our study indicates a high physiological sensitivity of mussels to these target metals, which highlights the significance of organ-specific accumulation of metal(loid)s in understanding the potential ecological risks of sedimentary metal(loid)s in lake ecosystems.

Unexpected enrichment of thallium and its geochemical behaviors in soils impacted by historically industrial activities using lead­zinc carbonate minerals.

Thallium is a trace metal with severe toxicity. Contamination of thallium (Tl) generated by steel and non-ferrous metals industry is gaining growing concern worldwide. However, little is known on Tl contamination owing to industrial activities using carbonate minerals. This study revealed abundant geochemical mobile/bioavailable Tl (> 65.7%, in average; mostly in oxidizable fraction) in soils from a carbonate-hosted PbZn ore utilizing area in China for the first time. Unexpected Tl enrichment was observed in soil accompanying with 3655, 7820, 100.1, 27.3 and 29.9 mg/kg (in average) of Pb, Zn, As, Cd and Sb, respectively. Characterization using X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis further confirmed that historical industrial activities impose anthropogenic catastrophic effects on the local agricultural soil system. The ecological and health risk assessment of heavy metal(loid)s in soils proclaimed serious potential non-carcinogenic risks of Pb and V to adults, and Pb, Tl and As to children. Sequential extraction analysis showed that Tl, as well as Pb, Zn, Mn, Co, and Cd, mainly existed in the mobile fractions (exchangeable/acid-extractable, reducible and oxidizable), indicating an ecological risk of biological accumulation of multiple metal(loid)s in this area. These findings provide a theoretical basis for taking appropriate remediation measures in order to ensure safety of soils in such industrial areas likewise.

Escalating health risk of thallium and arsenic from farmland contamination fueled by cement-making activities: A hidden but significant source.

Soil-to-vegetable migration of toxic metal(loid)s is a pivotal pathway of human exposure to chemical intoxication. Thallium (Tl) and arsenic (As) are highly toxic metal(loid)s but their co-occurrence in soils and vegetables remain poorly understood. Herein, the present study focuses on potential health risk arising from co-occurrence of TlAs in various common vegetables cultivated in different farmlands around an industrial area featured by cement production activities. The results reveal obvious co-contamination of Tl (2.28 ± 1.39 mg/kg) and As (102.0 ± 66.7 mg/kg) in soils. Fine particles bearing sulfide and other minerals associated with Tl and As are detected in fly ash from cement plant, which can be migrated by wind over a long distance with hidden but inevitable pollution. Bioaccumulation Factor (BCF) and Enrichment Factor (EF) show that taro and corn preferentially accumulate Tl especially in underground parts. Hazard Quotient (HQ) indicates that consumption of these vegetables may result in chronic poisoning and/or even carcinogenic risk. The study highlights that the pathway and high risk of co-contamination of TlAs in the nearby farmlands posed by cement-making activities should be highly concerned.

Contamination, oral bioaccessibility and human health risk assessment of thallium and other metal(loid)s in farmland soils around a historic TlHg mining area.

In this study, tweenty-nine soil samples were collected from a historic TlHg mining area, located in southwest Guizhou, China. Total concentrations of metal(loid)s in soils and in vitro extracts were analysed by ICP-MS, and the bioaccessibility of metal(loid)s was conducted by two often used in vitro extraction methods, Simplified bioaccessibility Extraction Test (SBET) and Physiologically Based Extraction Test (PBET). The health risk assessment based on total concentrations of metal(loid)s, bioaccessibility of SBET and PBET through soil ingestion were investigated. Results indicated that the collected cultivated soils contained elevated concentrations of Tl (44.8 ± 67.7 mg kg-1), Hg (110 ± 193 mg kg-1), As (84.4 ± 89.2 mg kg-1) and Sb (14.8 ± 24.8 mg kg-1), exceeding the regional background values of Guizhou province, China and the Chinese farmland risk screening values. However, the bioaccessibility of Tl, Hg, As and Sb were relatively low, usually less than 30% for most samples and varied greatly among metal(loid)s and sampling sites. The average bioaccessibility values of Tl, Hg, As and Sb by SBET were lower than those by PBET. The non-carsinogenic risk (HQ and HI) and Carcinogenic Risk (CR) values were significantly reduced when incorporating the bioaccessibiltiy of metal(loid)s into health risk assessment. It is worth noting that the health risk to children exceeded adults. Moreover, Tl and As contributed the most to the risk, indicating that more attention should be paid on Tl and As during the daily environmental regulation and management of contaminated soils in Lanmuchang.

Determination of thallium in urine, blood, and hair in illicit opioid users in Iran.

CONTEXT: Heavy metals, including thallium and lead, are introduced to illicit drug users' body as a result of using drugs such as cocaine and heroin. OBJECTIVE: This study aimed to determine urine, blood, and hair thallium (Tl) concentrations in illicit opioid users along with the relevant clinical signs and symptoms consistent with thallotoxicosis and to compare them with the corresponding variables in the control non-opioid user group. MATERIALS AND METHODS: This case-control study was conducted on 50 illicit opioid users who had abused opioids continuously for more than a year, referred to Amirie Drug Abuse Treatment Clinic in Kashan, Iran. The control group included 50 non-opioid users. Thallium concentrations in urine, blood, and hair were assessed in both groups (n = 100) using electrothermal (graphite furnace) atomic absorption spectrometry (ET AAS, GF AAS). RESULTS: In the studied group, the median (interquartile range) concentrations of thallium in urine, blood, and hair were 54.8 ± 79.9 µg/L, 14.5 ± 11.1 µg/L, and 5.4 ± 3.7 µg/g, respectively; these values were 4.8 ± 5.2 µg/L, 2.5 ± 2.4 µg/L, and 1.4 ± 1.1 µg/g, respectively, in the control group. There were significant differences in urine, blood, and hair thallium concentrations between the study group and the control group (p < 0.001). There were significant correlations between duration of illicit opioid use and urine thallium concentrations (r = 0.394, p = 0.005) and hair thallium concentrations (r = 0.293, p = 0.039), but not with blood thallium concentrations (r = 0.246, p = 0.085). Urine and blood thallium concentrations of illicit opioid users with clinical signs and symptoms consistent with thallotoxicosis of weakness (p = 0.01), depression (p = 0.03), and headache (p = 0.03) were higher than users without these problems. DISCUSSION AND CONCLUSION: The results of the study showed that thallium concentrations in urine, blood, and hair in illicit opioid users were significantly higher than the comparable concentrations in the control group. This can be due to the use of illicit opioids adulterated with thallium. Also, this study showed long-term illicit opioid use may lead to thallium exposure. In addition, cigarette smoking was associated with increased thallium exposure.

Removal of thallium from environmental samples using a raw and chemically modified biosorbent derived from domestic wastes.

Because of its high toxicity, thallium (Tl) causes environmental pollution even at very low concentrations. Despite its extremely high environmental risk, limited information about Tl removal from water is present on the literature. This work focused on the use of an eco-friendly and low-cost Ilex paraguariensis (yerba mate) biowaste to remove Tl from environmental water samples. Raw (YM) and L-cysteine chemically modified yerba mate (YM@LC) were used. The effect of pH and biosorbent concentration on the biosorption capacity was studied using an experimental design. The optimal experimental conditions were as follows: YM concentration 0.25 g L-1, pH 6.0, and YM@LC concentration 0.25 g L-1, pH 4.0. Kinetic studies yielded data that were in accordance with pseudo-second-order model. Equilibrium studies were also developed and indicated that the most appropriate model was that of Sips, with a maximum capacity of biosorption at 328 K of 333.4 mg g-1 for YM and 384.4 mg g-1 for YM@LC. The thermodynamic evaluation exhibited an endothermic, spontaneous, and favorable biosorption for both biosorbents. YM and YM@LC showed significant potential for Tl removal from environmental water samples.

Details of a thallium poisoning case revealed by single hair analysis using laser ablation inductively coupled plasma mass spectrometry.

Heavy metals pose significant morbidity and mortality threats to humans in connection with both acute and chronic exposure. The often-delayed manifestations of some toxic effects and the wide-spectrum of symptoms caused by heavy metal poisoning may perplex the clinical diagnosis and, when involved in crimes, complicate the forensic investigation. To investigate the original intoxication process of a thallium poisoning case, which occurred in China more than two decades ago, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) was used to analyze several hairs of the victim from before, during and after the poisoning period. Ablation line scans of the entire length of a ∼7cm hair revealed ∼4months of repeated exposure to thallium with increased doses and frequency toward the end, while scan of a ∼0.7cm hair revealed ∼2weeks of constant ingestions of large doses of thallium accompanied by elevated amount of lead. The endogenous origin of thallium was confirmed by the preservation of the same longitudinal distribution profile in the inner part of hair, but the source of lead could not be unambiguously determined due to the intrinsic limitation of hair analysis to distinguish ingested lead from exogenous contaminants. The overall thallium distribution profiles in the analyzed hairs suggested both chronic and acute thallium exposures that correlated well with the sequential presentation of a plethora of symptoms experienced by the victim. Aligning the time-resolved thallium peaks with symptoms also provided clues on possible routes of exposure at different poisoning stages. This work demonstrated the capability of using single hair LA-ICP-MS analysis to reconstitute a prolonged and complicated heavy metal poisoning case, and highlighted the necessity of assessing multiple elements in the medico-legal investigation of suspicious heavy metal poisonings.

Spectrophotometric investigation of Glutathione modulation by Thallium chloride in aqueous medium.

Thallium has been shown to significantly influence various tissues of living organisms; Exposure to Thallium can disturb mitochondrial function, degenerate neurons, and interfere with the function of critical metabolic enzymes and co-enzymes. Glutathione (GSH) an essential biomarker is considered a key factor in harnessing the thallium toxicity. In the present study the interaction of Thallium (Thallium Chloride) and glutathione was investigated spectro-photo-metrically in aqueous media. The renowned Elman's experimental protocol was followed at a wavelength of 412nm for Glutathione quantification in each sample. The pH of each sample was maintained at 7.6 using Phosphate buffer during the entire course of the experiment. A concentration as well as time dependent depletion of glutathione after exposure to various concentration of Thallium metal was observed, revealing chemical interaction between the metal and glutathione. The exact mechanism of interaction of Thallium and glutathione is still to be investigated. However, this piece of research suggests that a decrease in the concentration of Glutathione may be due to Thallium-GSH abduct or oxidize glutathione (GSSG) formation. This study was performed in-vitro as a model of in vivo.

Temporal Fluctuations in Indoor Background Gamma Radiation Using NaI(Tl).

An enhanced understanding of background gamma radiation is necessary for accurate radionuclide activity quantification. Background spectra are routinely subtracted from spectra of samples prepared in known geometries, with data collection time chosen to optimize statistics for counting uncertainties. The work presents measured background spectra collected inside and outside shields of varying geometry and composition, showing the effects of these on background. Gamma background measurements with and without blank samples are included along with spectra from different sizes and shapes of NaI(Tl) detectors. If the environment is being monitored for quick and confident detection of recently appearing radiation sources, a thorough knowledge of the background radiation and its temporal variation is essential. To study the requirements of such background measurements, sequential background gamma radiation collections were obtained on an hourly basis for a total of 316 h from an unshielded 5.5 × 11 × 40 cm NaI(Tl) detector located inside a laboratory setting where small sources are routinely stored and used. Finally, a strategy for optimizing data collection times and analyzing background gamma radiation spectra for long-term radionuclide monitoring is presented.

The efficient removal of thallium from sintering flue gas desulfurization wastewater in ferrous metallurgy using emulsion liquid membrane.

The removal of thallium ions in flue gas desulfurization wastewater from ferrous metallurgic industry was studied by emulsion liquid membrane (ELM) method using 2-ethylhexyl phosphoric acid-2-ethylhexyl ester (P507) as carrier, aviation kerosene (AK) as organic solvent, polyisobutylene succinimide (T154) as surfactant, polyisobutylene (PIB) as additive, and sulfuric acid as internal reagent. Some important influence parameters such as concentrations of carrier, surfactant and stripping agent, agitation speed, extraction time, volume ratios of feed solution to emulsion phase and internal phase to membrane phase, and their effects on the removal efficiency of Tl in the ELM process were investigated and optimized. Under the optimum operating conditions of 2% of carrier, 5% of surfactant, 0.5 M of stripping agent, 350 rpm of agitation speed, 12.5:1 of volume ratio of feed solution to emulsion phase, and 3:1 volume ratio of membrane to internal phase, the maximum extraction efficiency of thallium reached 99.76% within 15-min reaction time. The ICP-MS analysis indicated that the thallium concentration in treated wastewater was below 5 µg/L and could meet the emission standard demand for industrial wastewater enacted by the local government of Hunan province of China. Meanwhile, the extraction of impurity ions calcium and magnesium in the ELM system was investigated. The result showed that an acidic environment would be in favor of the removal of Tl from calcium and magnesium contained in wastewater. Graphical abstract ᅟ.

Thallium contamination in arable soils and vegetables around a steel plant-A newly-found significant source of Tl pollution in South China.

Thallium (Tl) is a highly toxic rare element. Severe Tl poisoning can cause neurological brain damage or even death. The present study was designed to investigate contents of Tl and other associated heavy metals in arable soils and twelve common vegetables cultivated around a steel plant in South China, a newly-found initiator of Tl pollution. Potential health risks of these metals to exposed population via consumption of vegetables were examined by calculating hazard quotients (HQ). The soils showed a significant contamination with Tl at a mean concentration of 1.34 mg/kg. The Tl levels in most vegetables (such as leaf lettuce, chard and pak choy) surpassed the maximum permissible level (0.5 mg/kg) according to the environmental quality standards for food in Germany. Vegetables like leaf lettuce, chard, pak choy, romaine lettuce and Indian beans all exhibited bioconcentration factors (BCF) and transfer factors (TF) for Tl higher than 1, indicating a hyperaccumulation of Tl in these plants. Although the elevated Tl levels in the vegetables at present will not immediately pose significant non-carcinogenic health risks to residents, it highlights the necessity of a permanent monitoring of Tl contamination in the steel-making areas.

Pre-mining trace element and radiation exposure to biota from a breccia pipe uranium mine in the Grand Canyon (Arizona, USA) watershed.

The risks to wildlife and humans from uranium (U) mining in the Grand Canyon watershed are largely unknown. In addition to U, other co-occurring ore constituents contribute to risks to biological receptors depending on their toxicological profiles. This study characterizes the pre-mining concentrations of total arsenic (As), cadmium (Cd), copper (Cu), lead (Pb), mercury (Hg), nickel (Ni), selenium (Se), thallium (Tl), U, and zinc (Zn); radiation levels; and histopathology in biota (vegetation, invertebrates, amphibians, birds, and mammals) at the Canyon Mine. Gross alpha levels were below the reporting limit (4 pCi/g) in all samples, and gross beta levels were indicative of background in vegetation (<10-17 pCi/g) and rodents (<10-43.5 pCi/g). Concentrations of U, Tl, Pb, Ni, Cu, and As in vegetation downwind from the mine were likely the result of aeolian transport. Chemical concentrations in rodents and terrestrial invertebrates indicate that surface disturbance during mine construction has not resulted in statistically significant spatial differences in fauna concentrations adjacent to the mine. Chemical concentrations in egg contents and nestlings of non-aquatic birds were less than method quantification limits or did not exceed toxicity thresholds. Bioaccumulation of As, Pb, Se, Tl, and U was evident in Western spadefoot (Spea multiplicata) tadpoles from the mine containment pond; concentrations of As (28.9-31.4 µg/g) and Se (5.81-7.20 µg/g) exceeded toxicity values and were significantly greater than in tadpoles from a nearby water source. Continued evaluation of As and Se in biota inhabiting and forging in the mine containment pond is warranted as mining progresses.

Metals transfer from tobacco to cigarette smoke: Evidences in smokers' lung tissue.

Tobacco use kills millions of people every year around the world. The current level of 11 metals in tobacco was determined and their transfer rate to cigarette smoke was calculated as the difference between the total metal content in cigarettes and the amount present in its ashes. The metals content was also determined in the lung tissue of smokers and non-smokers in order to evaluate the marks that smoking leaves in this tissue. Metals content in tobacco ranged from less than 1µg/g (Co, Cd, Pb, As and Tl) to several hundreds of µg/g (Al, Mn and Ba). The highest transfer rate from tobacco to cigarette smoke was found for Tl (85-92%) and Cd (81-90%), followed by Pb (46-60%) and As (33-44%). Significantly higher levels of As, Cd and Pb were found in the lung tissue of smokers compared to non-smokers, showing that smoking results in an increase of these metals in the lungs and that they contribute to the carcinogenic potential of cigarette smoke. This study presents important data on current metals content in tobacco and its transference to cigarette smoke and provides evidence of their accumulation in smokers' lung tissue.

LC/DAD/MS" and ICP-AES Assay and Correlations between Phenolic Compounds and Toxic Metals in Endemic Thymus alsarensis from the Thallium Enriched Allchar Locality.

Samples of Thymus alsarensis Ronniger, an endemic species for the Allchar locality, were evaluated for their polyphenolic composition and heavy metals. Allchar district is an abandoned antimony-arsenic-thallium deposit in the north-west of Kozuf Mountain, R. Macedonia, with a unique mineral composition affecting the mineral composition of the flora. A systematic method for phenolic compounds characterization was developed using mass spectrometry coupled to HPLC/DAD. Analyses were focused on the polyphenolic compounds to establish a possible correlation to the region specific heavy metals As and TI in the different organs of T. alsarensis. Twenty-seven polyphenols: phenolic acid derivatives and flavonoid glycosides of luteolin, apigenin, quercetin, and kaempferol were detected; contents were higher in the leaves and flowers compared with stems and roots. Quinic acid (1), prolithospermic acid (6), salvianolic acid B (7), salvianolic acid A (8), monomethyl lithospermate (9), luteolin dihexoside (12), luteolin pentosyl-hexoside (14), luteolin acetyl pentosyl-hexoside (16), luteolin acetyl hexoside (17), luteolin dipentoside (21), luteolin pentoside (24), luteolin acetyl dipentoside (25), kaempferol pentosyl-hexoside (19) and kaempferol acetyl pentosyl-hexoside (22) were detected in T. alsarensis for the first time. To assay the content of As and TI, root, stem, leaf and flower samples were analyzed by inductively coupled plasma atomic emission spectrometry (ICP-AES). Significant accumulation of As and TI was observed with As content from 0.25 to 140 mg/kg and TI from 0.10 to 496 mg/kg. The content of As was much higher in the roots, while the content of TI was significantly higher in the roots, flowers and leaves in all T. alsarensis specimens. Comparison of the results obtained for total polyphenols and for As and TI content does not suggest any correlation (positive or negative) between the total phenolic content and the content of TI and As. On the other hand, it is evident that the soil rich with specific heavy metals (TI and As) affects the type of polyphenolic compounds produced in different organs, compared with other Thymus species growing on soil that is not contaminated.

Human fatality due to thallium poisoning: autopsy, microscopy, and mass spectrometry assays.

Thallium has been responsible for many intoxications since its discovery; however, toxicological profiles for thallium in human fatalities have not been updated recently. Autopsy, microscopic investigations, and toxicological analyses were performed on a married couple who died from thallium sulfate intended homicidal poisoning. The distribution of thallium was established by inductively coupled plasma mass spectrometry with hair samples showing the highest thallium concentration. Electron microscopy revealed a dystrophic condition of hair with disorganized cuticle and atrophy of the hair bulb. Thallium interacts with cells at different levels, with prominent ultrastructural injuries in the mitochondria and endoplasmic reticulum, and high concentration of electron dense granules observed in the cytoplasm and mitochondria of several organs. Alopecia, toxic encephalopathy, and peripheral neuropathy were diagnosed in the victims and suggested to be crucial implications for thallium poisoning. The analytical procedures used in this case are of considerable forensic importance in the diagnosis of thallium poisoning.

A calixarene-based ion-selective electrode for thallium(I) detection.

Three new calixarene Tl(+) ionophores have been utilized in Tl(+) ion-selective electrodes (ISEs) yielding Nernstian response in the concentration range of 10(-2)-10(-6)M TlNO3 with a non-optimized filling solution in a conventional liquid contact ISE configuration. The complex formation constants (logßIL) for two of the calixarene derivatives with thallium(I) (i.e. 6.44 and 5.85) were measured using the sandwich membrane technique, with the other ionophore immeasurable due to eventual precipitation of the ionophore during these long-term experiments. Furthermore, the unbiased selectivity coefficients for these ionophores displayed excellent selectivity against Zn(2+), Ca(2+), Ba(2+), Cu(2+), Cd(2+) and Al(3+) with moderate selectivity against Pb(2+), Li(+), Na(+), H(+), K(+), NH4(+) and Cs(+), noting that silver was the only significant interferent with these calixarene-based ionophores. When optimizing the filling solution in a liquid contact ISE, it was possible to achieve a lower limit of detection of approximately 8nM according to the IUPAC definition. Last, the new ionophores were also evaluated in four solid-contact (SC) designs leading to Nernstian response, with the best response noted with a SC electrode utilizing a gold substrate, a poly(3-octylthiophene) (POT) ion-to-electron transducer and a poly(methyl methacrylate)-poly(decyl methacrylate) (PMMA-PDMA) co-polymer membrane. This electrode exhibited a slope of 58.4mVdecade(-1) and a lower detection limit of 30.2nM. Due to the presence of an undesirable water layer and/or leaching of redox mediator from the graphite redox buffered SC, a coated wire electrode on gold and graphite redox buffered SC yielded grossly inferior detection limits against the polypyrrole/PVC SC and POT/PMMA-PDMA SC ISEs that did not display signs of a water layer or leaching of SC ingredients into the membrane.

Phytoremediation of water polluted by thallium, cadmium, zinc, and lead with the use of macrophyte Callitriche cophocarpa.

The objective of the present work was to study the phytoremediation capacity of Callitriche cophocarpa concerning water contaminated with thallium (Tl), cadmium (Cd), zinc (Zn), and lead (Pb) derived from the natural environment. We found that after a 10-day incubation period, shoots of C. cophocarpa effectively biofiltrated the water so that it met (for Cd, Zn, and Pb) appropriate quality standards. The order of accumulation of the investigated elements by shoots (mg kg(-1) dry weight) were as follows: Zn (1120) < Tl (251) < Cd (71) < Pb (35). The order of bioconcentration factors were as follows: Cd (1177) < Tl (1043) < Zn (718) < Pb (597). According to Microtox bioassay, C. cophocarpa significantly eradicated polluted water toxicity. During the experiment, the physiological status of plants was monitored by taking measurements of photosystem II activity (maximum efficiency of PSII, photochemical fluorescence quenching, nonphotochemical fluorescence quenching, and quantum efficiency of PSII), photosynthetic pigment contents, and shoot morphology. Plants exposed to metallic pollution did not exhibit significant changes in their physiological status compared with the control. This work is potentially applicable to the future use of C. cophocarpa in the phytoremediation of polluted, natural watercourses.

Concentrations of metals in soils in the neighborhood of a hazardous waste incinerator: assessment of the temporal trends.

The concentrations of arsenic (As), beryllium (Be), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), mercury (Hg), manganese (Mn), nickel (Ni), lead (Pb), antimony (Sb), tin (Sn), thallium (Tl), and vanadium (V) were determined in 30 soil samples collected in April 2011 near a hazardous waste incinerator (HWI; Constantí, Catalonia, Spain), which is under regular operations since 1999. The results were compared with those of recent surveys performed in the same zone, as well as with data from a background study (1996-1998). We also assessed the human health risks derived from metal exposure in the area under potential influence of the emissions of the HWI. Manganese was the most abundant element in soils, with a mean value of 316.4 µg/g, followed by Pb and Cu (mean values, 42.5 and 38.2 µg/g, respectively). In contrast, Sb, Cd, and Tl presented the lowest values (0.12, 0.27, and 0.29 µg/g, respectively), while Hg was below its limit of detection. In the period 1998-2011, only As, Cr, Sn, Tl, and V levels presented significant increases in soils. The estimated carcinogenic and noncarcinogenic risks derived from exposure to these metals from soils should not mean any special concern for the population living in the surroundings of the HWI.