Heavy Metal Load Research Articles

Human risk associated with potential exposure to heavy metals in a gadoid fish species from selected markets in Benin City, Nigeria

The study ascertained the levels of Cadmium (Cd), Copper (Cu), Lead (Pb) and Zinc (Zn) in the Atlantic cod (Gadus morhua) of mean weight 679 ± 16.05 g, from selected markets in Benin city, Nigeria, by Atomic Absorption Spectrometric technique, in order to ascertain their suitability for human consumption. The mean concentrations of heavy metals in G. morhua ranged from 0.03 mg/kg Cd at New Benin market to 52.85 mg/kg for Zn at Ramat market while there was no significant difference (p>0.05) in the mean concentrations of heavy metals in fish between markets. The estimated daily intake (EDI) values for heavy metals ranged from 0.0032 mg/person/day for Cd to 1.70 mg/person/day for Zn while the estimated annual intake (EAI) values for heavy metals ranged from 1.17 mg/person/year for Cd to 620.5 mg/person/year for Zn. The estimated quantity consumed (EQC) values ranged from 0.000064 mg/meal for Cd to 0.034mg/meal for Zn while the theoretical maximum daily intake (TMDI) was 2414 mg/person/day. The margin of exposure (MOE) values for heavy metals ranged from 0.63 for Cd to 4.19 for Cu while the total toxicity of mixtures (TTM) value was 4.82. The toxic/hazard quotient (TQ) values ranged from 0.24 for Cu to 1.60 for Cd while the total heavy metal load in fish by market, ranged from 41.26 mg/kg at New Benin market to 59.27 mg/kg at Ramat market. The mean concentrations of Cd, Pb and Zn in G. morhua exceeded the thresholds established for heavy metals in fish by CODEX Alimentarius, Commission Regulation and Food and Agriculture Organization of the United Nations (FAO), thus making them the metals of critical ecological concern. The implication is that G. morhuamust be consumed with caution in order to avert health problems associated with excess concentrations of Cd, Pb and Zn.Keywords: heavy metals, Gadus morhua, toxic/hazard quotient, markets, Nigeria

Assessment of DNA integrity through MN bioassay of erythrocytes and histopathological changes in Wallago attu and Cirrhinus mirigala in response to freshwater pollution.

The aim of this study was to determine the level of contamination and genotoxic impact through micronucleus assay and histopathology in Wallago attu and Cirrhinus mrigala procured from the polluted site of the River Chenab at industrial and sewage waste disposal. The water sample was found viciously contaminated with heavy metals i.e. Ni, Cr, Mn, Co, Pb, Hg, Zn, Sn, Cu while all other physio-chemical variables crossed the suggested limits of WHO. The heavy metals load induced histopathological alterations were correlated to environmental degradation and the productivity of this biological system. W. attu and C. mrigala harvested from contaminated sites of the river indicated higher intensity of DNA damage through micronucleus induction and nuclear abnormalities with 5.46 ± 0.17, 1.23 ± 0.08 and 4.2 ± 0.11, 0.4 ± 0.04‰ respectively. Muscle sections of W. attu and C. mrigala harvested from the polluted section of river demonstrated the necrosis, degeneration of muscle fibers, intra-fibular edema and release of the blood into the tissues due to the bursting of blocked of the blood vessels. Dermal layers showed degeneration of the collagen bundles those were found loose or collapsed in some regions. Photomicrography also revealed vacuolar degeneration in muscle tissues and atrophy of muscle bundles. Intra fibular edema and splitting of muscle fibers were also seen along with bioaccumulation of toxicants. W. attu showed maximum incidence of alterations with highest histopathological alteration index related to environmental degradation. Control fish samples showed normal muscle tissues with normal equally spaced muscle bundles and myotomes.

Life Cycle Assessment of Alternative Road Base Materials: the Case of Phosphogypsum

Phosphogypsum (PG) is the most abundant by-product generated by the phosphate fertilizer industry. Formed during the production of phosphoric acid from natural phosphate rock, PG is mostly disposed in stacks or released into coastal regions’ waters. Due to the expected increase in the world PG production – currently estimated to be around 250 Mt per year – and the environmental impacts of actual waste management scenarios, there is a call for a paradigm shift, by considering PG not as a waste but as a resource. About 15% of the total PG production is nowadays used as fertilizer, retarder, road base material or building material. The load of radionucleids and heavy metals contained in PG however questions the sustainability of such valorization routes. This paper aims to compare the environmental impacts of different PG valorization scenarios through life cycle assessment. Based on Moroccan conditions for phosphoric acid production, it discusses the key parameters influencing the assessment as well as assumptions regarding the allocation of emissions and resource use over PG and phosphoric acid.

Evaluation of the potential risks of heavy metal contamination in rice paddy soils around an abandoned Hg mine area in Southwest China

To assess the potential ecological and health risks of trace elements (Hg, Cd, As, Mn, Sb, Pb, Cu, Ni, Cr, and Zn), a total of 138 soil samples from rice paddies were collected during the rice harvest season in the Wanshan mining area, Guizhou Province, Southwest China. Factors of the pollution load index (PLI), geo-accumulation index (I-Geo), enrichment factor (EF), and risk index (RI) were determined. High concentrations of Hg, Sb, As, Zn, Cd, Cu, and Mn were observed in the soils. The PLI, I-Geo, and EF results all showed high levels of contamination by Hg and Sb and moderate levels of contamination by As, Pb, Zn, Cu, Cd, and Mn. There was no significant contamination from Ni and Cr. The RI was very high, with Hg as the dominant pollutant, as expected, indicating that the historical large-scale Hg mining, as well as artisanal mining, has had a significant impact on the Wanshan area. Moreover, coal combustion, manganese factories, and the use of agrochemicals by the local population could also have an impact on the soil through the introduction of heavy metal loads. To address the current state of contamination, pollutant remediation and the regulation control of the anthropogenic activities in Wanshan are urgently needed.

Effect of particulate organic matter fractions on the distribution of heavy metals with aided phytostabilization at a zinc smelting waste slag site

Particulate organic matter (POM) significantly affects the distribution of heavy metals in contaminated soil. However, the effect of POM on the fate of heavy metals during in situ-aided phytostabilization of waste slag is unclear. The objective of this study was to investigate the distributions of heavy metals such as Cu, Pb, Zn, and Cd in the POM fractions at a zinc smelting waste slag site under in situ-aided phytostabilization after five years. The results showed that the litters and residues of four plants―Arundo donax, Broussonetia papyrifera, Cryptomeria fortunei, and Robinia pseudoacacia―decomposed to form different POM size fractions. The percentage of the 0.05–0.25 mm POM size fraction was the highest, followed by the >1 mm and 0.5–1 mm POM size fractions, and that of the 0.25–0.5 mm POM size fraction was the lowest. The masses of POM derived from the four plants were in the following order: C. fortunei > B. papyrifera > A. donax > R. pseudoacacia. The contents, enrichment coefficients, and mass loads of heavy metals such as Cu, Pb, Zn, and Cd in the POM increased with decreasing POM size, and those in the 0.05–0.25 mm POM size fraction were the highest. The mass load of heavy metals in the POM occurred in the following order: Cu > Cd > Zn > Pb. The surfaces of the POM with coarser and smaller size fractions were smoother and rougher, respectively, and the smaller POM size fractions had larger specific surface areas. The main functional groups in the different POM size fractions were –COOH, –OH, CO, CC, C–H, Si–O, and –CH3. The POM fractions played a significant role in determining the distribution of heavy metals in the revegetated waste slag. These findings have important implications for aided phytostabilization, which significantly influences the fate and speciation of heavy metals at the phytoremediation site.

Heavy metals partition between leachate and solids in the course of municipal sewage treatment

Measurements of heavy metals contents (Cu, Zn, Pb, Cd) were carried out in liquid and solid fractions of sewage and sewage sludge after stabilization as well as dewatering. Investigation was carried out in municipal WWTP ,,Wschod" in Gdansk. The flow of sewage was equal to 88 000 m3 /d. The treatment consists of two stages: the first stage - mechanical (4screens, 2 sandtraps, 4 primary sedimentation tanks) and the second stage - advanced biological MUCT system (6 reactors - each incorporating the following chambers: dephosphatation, pre-denitrification, denitrification and nitrification followed by 2 secondary sedimentation tanks) modified by introduction of an additional chamber which secures dioxidation of sewage recirculated between nitrification and denitrification chambers. Sewage sludge (primary and secondary) is stabilized by fermentation. The last step of sludge utilization is mechanical dewatering. Samples of sewage were collected at the following points of the WWTP: at the beginning - raw sewage, mechanically treated sewage and biologically treated sewage. Samples of reject waters after thickening and after mechanical dewatering of sludge were collected too. The following types of sewage sludge were investigated: primary, secondary, thickened (on the Klein press), digested and mechanically dewatered (Noxon centrifuges). In the sampling points samples were collected twice per month during the 6 months period in the years 2000-2001. Inflowing sewage carried the following loads of heavy metals: Zn - 27.2 kg/d, Cu - 5.4 kg/d, Pb - 1.3 kg/d and Cd - 0.4 kg/d. Basing on balances of heavy metals loads it was proved that 87.0% Zn and 83.0% Cu were kept in sludge. Among analysed sewage sludge samples, the highest contents of heavy metals was found in sludge after mechanical dewatering and in the mixture of primary and secondary sludge (Zn - 780.4 mg/kg d.m., Cu - 144.6 mg/kg d.m., Pb - 5.4 mg/kg d.m. and Cd - 2.4 mg/kg d.m. The contents of heavy metals in examined sludge were compared with Polish admissible loads of metals applied with sludge to soil fertilization. Basing on the findings, admissible loads of sewage sludge to agricultural land were not exceeded.

PATTERNS OF HEAVY METALS ACCUMULATION IN FISH IN LAKES OF THE FENNOSCANDIAN GREEN BELT (IN THE MURMANSK REGION)

The patterns of heavy metals (HM) accumulation in fish from lakes of the Murmansk Region within the Green Belt of Fennoscandia (GBF) exposed to long-term air-borne pol-lution associated with the operation of a non-ferrous metal processing enterprise have been studied. The detrimental effects of air-borne water pollution from the Kola GMK mine and smelter do not depend on the dominant wind directions. The reduction in emis-sions from the Nickel site of the Kola GMK in the past decades has not led to a significant decrease in the level of anthropogenic load. On the contrary, a long-term upward trend is observed in the content of Cu in the organs of whitefish, char, pike and perch in all the lakes studied. The accumulation of Cu and Ni in fish target organs tended to decrease along the distance gradient from the source of pollution. The revealed pattern is con-sistent with the intensity of pathologies development in whitefish organs. The common whitefish (Coregonuslavaretus(L., 1758)) is the most reliable test object that reflects the degree of pressure from long-term exposure to HM. The size of the catchment area is supposed to predetermine the intensity and rate of HM accumulation in fish organisms. The cumulative effect of persistent anthropogenic HM load on waterbodies in the study area, climate change processes, and man-induced eutrophication of waters can show in a decline in the biological diversity of the fish fauna in GBF, reduction in the number of valuable fish species. The identified patterns can be used in assessing the state both of existing and planned protected areas inside GBF.

Environmental Impact of Heavy Metals from Poultry Waste Discharged into the Olosuru Stream, Ikire, Southwestern Nigeria

Water supplies can be contaminated by anthropogenic activities. The poultry industry uses a variety of heavy metals as additives in chicken feed, but excretion, runoff and dumping of heavy metals can threaten water bodies and have adverse effects on human health. The aim of the present study was to determine the environmental impact of heavy metals from poultry waste discharged into the Olosuru stream, located in Ikire, southwest Nigeria. In order to study changes in heavy metal loads, samples were collected six times during the wet season (September, October 2014 and April 2015) and dry season (November 2014, January and February 2015). The inhabitants of Olosuru village use water for domestic and agriculture purposes from the Olosuru stream which is located only a few meters from a poultry farm discharge point. Three stations were sampled, upstream to downstream, with 500 meter distance between each point. Selected heavy metals concentrations in the Olosuru stream were all above the World Health Organization (WHO) standard for drinking water. The highest mean concentrations of heavy metals were recorded at the downstream station, while arsenic, iron and lead showed significant spatial and seasonal differences. Seasonally, the highest iron concentrations were recorded in the dry season (0.104±0.401 mg/L), while the mean concentrations of other heavy metals recorded during the sampling period were higher during the wet season. Concentrations of heavy metals in the present study were above acceptable limits. Poultry waste discharged into the Olosuru stream, can have negative impacts on the stream and health implications for local residents. The authors declare no competing financial interests.

Incorporating a non-reactive heavy metal simulation module into SWAT model and its application in the Athabasca oil sands region.

Heavy metal contaminations in an aquatic environment is a serious issue since the exposure to toxic metals can cause a variety of public health problems. A watershed-scale model is a useful tool for predicting and assessing heavy metal fate and transport in both terrestrial and aquatic environments. In this study, we developed a simulation module for non-reactive heavy metals and incorporated it into the widely used Soil Water Assessment Tool (SWAT) model. The simulated processes in the developed model include heavy metaldeposition, partitioning in soil and water, and transport by different pathways in both terrestrial and aquatic environments. Three-phase partitioning processes were considered in the module by simulating heavy metals portioning to dissolved organic carbon in the soil and stream. This developed module was used for watershed-scale simulation of heavy metal processes in the Muskeg River watershed (MRW) of the Athabasca oil sands region in western Canadafor the first time. The daily streamflow and sediment load from 2015 to 2017 were first calibrated and validated. Subsequently, the daily Leadand Copperloads at the outlet station were used for heavy metal calibration and validation. The performances for the daily heavy metal loads simulation during the wholesimulation period can be considered as "satisfactory" based on the recommended model performance criteria with the Nash-Sutcliffe efficiency as 0.41 and 0.71 for Pb and Cu loads, respectively. The simulation results indicate that the spring and summer are hot moments for heavy metal transport and the snowmelt in spring and rainfall runoff events in summer are the main driving forces for the metal transport in the MRW. We believe the developed model can be a useful tool for simulating the fate and transport of non-reativeheavy metals at watershed scale and further used to assess management scenarios for mitigating heavy metal pollution in the Athabasca oil sands region.

CHEMICAL AND MICROBIAL SAFETY OF STREET VENDED EGG ROLL IN ABEOKUTA METROPOLIS

A total of 12 samples of egg rolls retailed in three locations in Abeokuta and a laboratory prepared sample serving as control were analyzed for their microbial load and presence of heavy metals (Lead, Cadmium, Chromium). The samples were analyzed for bacteria using standard procedures. Analysis of the food samples showed that total viable bacterial count ranged from 1.2 x 105 to 4.2 x 105 cfu/g, total staphylococcus count ranged between 1.2 x 104 and 6.4 x 104 cfu/g, coliform count ranged from 1.0 x 104 to 3.0 x 104cfu/g, total campylobacter count ranged between 1.0x104 and1.3x104 cfu/g and there were no growths for the total listeria count. Five bacteria genera were isolated including Staphylococcus aureus, Escherichia coli, Klebsiella aerogenes, Salmonella typhi, Campylobacter coli. Cadmium and Chromium contamination ranged from 3.50±0.71 - 12.50±0.71 and 0.75±0.35 - 3.50±0.00 respectively. Statistical analysis of the heavy metals shows a significant difference (p<0.05) between the control and samples. The level of microbial contamination could be associated with inadequate handling and processing by processors and vendors, contamination caused by either poor hygiene or poor quality of water used. Moreover, contamination of cadmium and chromium in all the samples could be incident upon the water used in producing it, however lead was absent in all the samples. It is therefore recommended that health education should be done for food handlers and consumers about food safety.
 
 

Contribution of submicronic (PM1) and coarse (PM>1) particulate matter deposition to the heavy metal load of lichens transplanted along a busy road

The aim of this study was to estimate the contribution of submicronic (PM1) and coarse (PM > 1) particulate matter deposition to the heavy metal load of lichens exposed along a busy road, based on the assumption that the accumulation of heavy metals occurs mostly as particles. We tested the hypothesis that lichens exposed inside a nylon cover with mesh size of 1 μm accumulate less heavy metals than lichens exposed without any cover. To this purpose, thalli of the lichen Evernia prunastri were transplanted for three months along a busy road of the urban area of Siena (Central Italy), with half of the samples exposed inside a nylon cover with a mesh size of 1 μm. The content of Al, As, Cd, Cr, Cu, Fe, Ni, Pb, Sb, and Zn was measured by ICP-MS before and after the exposure. The results showed that samples exposed inside the nylon cover accumulated a lower amount of most chemical elements and that Sb, along with Cd and Cu were the main traffic-related elements in the study area. Differences in element uptake were not caused by differences in sample vitality caused by the experimental procedure. Using a conversion factor it was possible to estimate element deposition rates for PM1 and PM > 1.

Use of national-scale data to examine human-mediated additions of heavy metals to wetland soils of the US

Soil concentrations of 12 heavy metals that have been linked to various anthropogenic activities were measured in samples collected from the uppermost horizon in approximately 1000 wetlands across the conterminous US as part of the 2011 National Wetland Condition Assessment (NWCA). The heavy metals were silver (Ag), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), antimony (Sb), tin (Sn), vanadium (V), tungsten (W), and zinc (Zn). Using thresholds to distinguish natural background concentrations from human-mediated additions, we evaluated wetland soil heavy metal concentrations in the conterminous US and four regions using a Heavy Metal Index (HMI) that reflects human-mediated heavy metal loads based on the number of elements above expected background concentration. We also examined the individual elements to detect concentrations of heavy metals above expected background that frequently occur in wetland soils. Our data show that wetland soils of the conterminous US typically have low heavy metal loads, and that most of the measured elements occur nationally in concentrations below thresholds that relate to anthropogenic activities. However, we found that soil lead is more common in wetland soils than other measured elements, occurring nationally in 11.3% of the wetland area in concentrations above expected natural background (> 35 ppm). Our data show positive relationships between soil lead concentration and four individual landscape metrics: road density, percent impervious surface, housing unit density, and population density in a 1-km radius buffer area surrounding a site. These relationships, while evident on a national level, are strongest in the eastern US, where the highest road densities and greatest population densities occur. Because lead can be strongly bound to wetland soils in particular, maintenance of the good condition of our nation’s wetlands is likely to minimize risk of lead mobilization.

Analysis of Heavy Metal Loading Optimization Through Criticality Calculation on RDE

The RDE (Indonesian Experimental Power Reactor) designed to produce 10 MW thermal with cylindrical core. The HGTR (High Temperature Gas-cooled Reactor) reactor technology with passive inherent safety is adopted. This RDE reactor core is designed to produce high temperature output range about 700°C, making it particularly suitable for cogeneration purposes such as electricity, desalination water production and industrial high temperature heat application. The improvement of performance and neutronic safety design parameter which strongly affects to the neutron moderation ratio such as the HM (Heavy Metal) loading optimization is important to ensure that. Therefore HM loading through the criticality calculation of the RDE reactor core using VSOP’94 code and MCNP6 coupled with ENDF/BII library is performed. Calculations using VSOP’94 code utilize DATA-2, ZUT-DGL, BIRGIT and VSOP-CITATION modules, whereas the calculations with MCNP6 start from the TRISO kernel modeling, fuel pebble and 3-D full core modeling. The optimization of HM loading calculation on core criticality is done through simulating of the heavy metal loading (HM) variation level from 1-15 gHM/pebble using several enrichment of 235U from 8%, 10%, 12% 14% and 17% using VSOP’94 and MCNP6 code through RDE core criticality with good results. The smallest difference of effective multiplication factor on RDE core criticality (below 1%) between two calculations with VSOP’94 and MCNP6 occurs at the HM loading level of 5 gHM/pebble at all 235U enrichment levels. At 17% enrichment, a similar trends to other enrichment, gives the maximum core criticality on HM loading of 8 gHM/pebble with effective multiplication factor of 1.17860 and 1.22458, respectively for VSOP’94 and MCNP6 with a difference of -3.75476%. As for HM loading 5 gHM/pebble calculations using VSOP’94 and MCNP6 each gives effective multiplication factor value of 1.16096 and 1.16666, respectively, with a difference of about -0.48857%.

Inherent safety analysis of the UO2 fueled pebble lattice at the RDE using SRAC2006 module of PIJ

Reaktor Daya Eksperimental (RDE) is type of High Temperature Gas Cooled Reactor (HTGR) with nominal power 10 MWth that uses pebble bed type of sperical fuel. In the development of the RDE core design, as the earliest stage is to study characteristic of the fuel pebble latice cell, mainly related to the inherent safety. In this study, the inherent safety analysis to the transient effect of fuel temperature and water ingress in the pebble fuel lattice on RDE design core has been done by using Standard Reactor Analysis Code (SRAC2006) Probability I J (PIJ) module. In addition, the nuclide content in the spent pebble fuel lattice was also analyzed. PIJ is code based on the collision probability method applicable to analyze the change of k-inf value when transient occurs at certain fuel burn up point. The analysis was performed to the 17.00% and 8.50% enrichment of UO2 fuel pebble at varying levels of uranium heavy metal loading, i.e 3, 5, 7, and 9 gram. The k-inf value of the fuel pebble lattice has been calculated using branching burn up mode module PIJ through double heterogenity model. Calculation results showed that the higher loading level of heavy metal of uranium then the k-inf value will be smaller. The transient with increasing of the temperature at each particular burn up point or the occurrence of water ingress will also decreas in the k-inf value of fuel pebble lattice. From the analysis result, it can be concluded that pebble lattice fueled with 17% enrichment of UO2 on RDE has inherent safety properties i.e. the decreasing of k-inf value if transient temperature occurs. And when there is water ingress, the inherent safety characteristeic is shown by pebble lattice with maximum loading of 9 g uranium heavy metal.. The percentage of the nuclide content in spent fuel of pebble latice on RDE is similar to the PWR lattice, so it is not possible for a large number of plutonium production. At the transient by increasing of temperature, there are no significant increasing of gaseous fission product production (Xe-135, I-135, Sm-149, Pm-149).

PESTICIDES AND TOXIC METALS RESIDUES IN MUSCLE AND LIVER TISSUES OF SHEEP, CATTLE AND DROMEDARY CAMEL IN SAUDI ARABIA

Data regarding determination of pesticide residues and toxic elements in edible tissues of different animals particularly in the camels in Eastern region of Saudi Arabia are scarce. Therefore, current study aimed to evaluate levels of forty-five pesticides and heavy metals (lead (Pb); cadmium (Cd); Arsenic (As)) in muscle and liver tissue samples that collected from forty-two animals; sheep (n=21), cattle (n=11) and dromedary camels (n=10) admitted to Al-Ahsa abattoir, Eastern province, Saudi Arabia. Seven of forty-five pesticides residues were detected in tissues by gas chromatographic mass spectrometry (GC/MS). The detected pesticides were organophosphorus (diazinon, profenofos and coumaphos), pyrethroid (cypermethrin, permethrin and lambda-cyhalothrin) and acaricide (amitraz). Diazinon has been detected in both muscle and liver tissues of all examined carcasses. However, other detected residues distributed according to species. All toxic metals have been detected in both muscle and liver tissues of all tested animals. The heavy metal loads were species independent. The concentrations of Pb and As in liver tissues were comparable to that of muscle tissues of all tested animals. However, the concentrations of Cd in liver were significantly higher than that in muscles of all tested animals. All values of detected pesticide residues and heavy metals were below the maximum residue limits (MRLs). In conclusion, pesticide residues and toxic metals were detected in meat and liver tissues of sheep, cattle and dromedary camels that admitted to Al-Ahsa abattoir, Saudi Arabia. The detected pesticides residues and toxic metals were well below MRLs; thereby no risks are associated with its human consumption.Key words: chromatography; residues; toxic elements; meat; pesticides; animals

Hospital centered surveillance of births in Gaza, Palestine, 2011–2017 and heavy metal contamination of the mothers reveals long-term impact of wars

Prevalence of preterm, low birth weight and birth defects increased significantly since 2011 in Gaza, Palestine. No change in known co-factors of reproductive health justified this rise. Two military attacks in 2012 and 2014 introduced novel risk factors for outcomes at birth: contamination by teratogenic and carcinogenic heavy metals weapon-remnants, ongoing impoverishment, and impaired rehabilitation of waste management. It was previously shown that mothers exposed to military attacks had higher metal load than those unexposed and mother's heavy metals trans-pass placenta. We investigated association in time of heavy metal contamination and reproductive health using hospital-based surveillance (2011–2016–2017) of births, accompanied by assessment in 2016 of metal load in mother and newborn hair. Mother's housing proximal to unmanaged waste predicted preterm birth and birth defects, and these women had highest load of heavy metals. Poor diet predicted low birth weight. Circumstances prevent investigation of heavy metals molecular impact(s) during fetal development.

The Fatty Acid Composition of Major Membrane Lipids of the Mussel Crenomytilus grayanus (Dunker, 1853) (Bivalvia: Mytilidae) under Chronic Anthropogenic Pollution: Evaluation of Stability

Accumulation of heavy metals and their effect on the composition of fatty acids and molecular species of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) has been studied in the molluskan organs and tissues of the Gray mussel from clean and polluted water areas of Peter the Great Bay of the Sea of Japan. The total load of heavy metals accumulated in the mussel was evaluated with the coefficient of total concentration (ΣCC), which turned out to be extremely high for all the organs studied in mollusks from a polluted site. Cu and Pb accounted for the main share in the total load. It was found that accumulation of heavy metals in the kidneys, gills, and muscles had no effect on the composition of fatty acids, molecular species, and forms of basic membrane lipids of PC and PE. It has been shown that high resistance of membrane lipids of the Gray mussel to chronic anthropogenic pollution with heavy metals allows the mussel to function under conditions of contamination.

Toxic Environment of war: Maternal prenatal heavy metal load predicts infant emotional development

BackgroundPeople in war zones are exposed to heavy metal contamination deriving from new-generation weapons, in addition to exposure to psychologically traumatizing war events. Pregnant women and their children-to-be are particularly vulnerable to both biological and psychological war effects. ObjectiveThe aim of the current study was to analyse the impact of maternal prenatal heavy metal contamination on infant emotional development and to examine the potential moderating role of maternal symptoms of post-traumatic stress disorder (PTSD) in the association between heavy metal load and infant emotional development. MethodsThe participants were 502 Palestinian mothers, pregnant in their first trimester during the 2014 War on Gaza. The mothers were recruited at their delivery (T1) and followed at the infants’ age of 6–7 months (T2; N = 392). The load of five weapon-related heavy metals (chromium, mercury, vanadium, strontium, and uranium) was analysed by Inductively Coupled Plasma Mass Spectrometry (ICP/MS) from mothers’ hair samples at childbirth (T1). Assessment of maternal PTSD symptoms was based on the Harvard Trauma Questionnaire (HTQ) and infant emotional development on the Infant Behavior Questionnaire (IBQ), both reported by mothers (T2). ResultsTwo of the analysed metals, chromium and uranium, adversely predicted children’s early emotional development, indicated by decreased positive affectivity, increased negative emotionality, and problems in early orientation and regulation. Mother’s PTSD did not moderate the impact of heavy metal contamination on children’s emotional development. ConclusionsAdverse impact of war is not limited to those who experience it directly, but is passed on to future generations through multiple mechanisms. International organizations are obliged to protect parents and infants from the modern weaponry in wars.

Neutronic analysis of thorium MOX fuel blocks with different driver fuels in advanced block-type HTRs

The use of thorium-based fuels is an attractive option to achieve high burnup level and relatively longer reactor operation period. This also includes some other potential advantages, such as, low proliferation risk and high conversion ratio, etc. It is interesting to utilize thorium-based fuels in advanced high temperature reactors (AHTRs), because they are a better choice for their high burnup limit and inherently-safe HTRs with a low-pressure operation condition. The neutronic performance of thorium MOX fuel blocks, including infinite multiplication factor, conversion ratio, discharge burnup and the neutron spectra in AHTRs, has been investigated by the DRAGON V4 code for four different driver fuels, U-233, reactor-grade plutonium (RGrPu), weapon-grade plutonium (WGrPu) and weapon-grade uranium (WGrU). Based on a typical fuel block of AHTRs, the influence of varying heavy metal loading and effective enrichment on the neutronic performance of the four fuel blocks is firstly investigated. The heavy metal loading of 5 kg and effective enrichment of 12% are selected for the neutronic comparisons. The further comparisons of the four thorium fuels with different driver fuels show that the Th/RGrPu and Th/WGrPu fuel blocks have intermediate neutron spectra, while Th/U233 and Th/WGrU fuel blocks have thermal neutron spectra. The Th/U233 fuel achieves the highest infinite multiplication factor at beginning of life because of its high thermal η value. Th/RGrPu fuel achieves the highest conversion ratio and the highest discharge burnup.

The content and pollution evaluation of heavy metals in surface seawater in Dalian Bay

Surface seawater samples at 23 sites in the offshore area of Dalian Bay were collected in November 2014 and May 2015, to investigate the concentration and pollution characteristics of the six heavy metals (Cu, Pb, Zn, Cd, Hg and As) in that area. The heavy metals pollution condition was evaluated using single factor pollution index evaluation method and comprehensive pollution evaluation method, the variation coefficient method was used to analyze the dispersion degree of pollutants on the spatial scale between the stations, and the correlation analysis and PCA method was used to study the main resources of heavy metals pollutants. The results showed that the average value of Cu, Pb, Zn, Cd, Hg and As met the I water quality requirements of the seawater water quality standard. The single factor pollution index values of the six heavy metals in the two seasons were in the following order: Cu>Pb> Zn>Hg>Cd>As. The evaluation result of the comprehensive pollution index method showed the average value was less than 1, so the study area was clean. The result of the variation coefficient showed that the heavy metal content in the water body between the stations was small in the investigation area, and the pollution degree of the heavy metal pollution factors in the sea area was basically the same. The results of correlation analysis and principal component analysis indicated the correlation coefficient of Cu, Pb, Zn, Cd, Hg and As was small and the positive load of heavy metals was low. Therefoere, there were no similar pollution level or common source of pollution between six metals, that is, the probability of common sources was lower among the elements.