Chromium Cr Research Articles

Heavy metal contamination and antibiotic residues in poultry feed and meat in Bangladesh

Presence of harmful contaminants and residues in poultry feed and meat have serious public health consequence. This study was carried out to identify and quantify antibiotic residues, heavy metals and toxins in poultry feed and meat in the two selected poultry production belts of Bangladesh. A total of 94 broiler feed samples and 60 broiler meat samples were collected and tested by Thin Layer Chromatography (TLC), High Performance Liquid Chromatography (HPLC) and Enzyme-linked Immunosorbent Assay (ELISA) for identification and quantification of the parameters. Antibiotic residues were detected in 18.89% of the feed samples, whereas, there were no toxin (Aflatoxin) positive samples. Among the antibiotic positive samples, Oxytetracycline (OTC) was found predominant and detected in 12.22% cases. The mean concentrations of Cadmium (Cd), Lead (Pb), Chromium (Cr) were found as 0.04 mg/kg, 1.28 mg/kg and 2.55 mg/kg respectively in feed samples. In the case of meat samples, the mean concentration of OTC, Ciprofloxacin (CIP), and Tetracycline (TCL) residues were found 8.67 ppb, 7.18 ppb and 0.81 ppb accordingly. The highest mean concentration of Oxytetracycline (OTC) (10.15 ppb) was found in samples collected from local poultry sellers, whereas, the highest mean concentration of Tetracycline (TCL) (1.35 ppb) and Ciprofloxacin (CIP) (10.62 ppb) were observed in the samples obtained from local farm. The highest percentage of TCL and CIP (64% and 48% respectively) were found in samples collected from local farm. Chlortetracycline (CTC) was found predominant (70%) in samples collected from Contract farms. On the other hand, out of 60 meat samples, Cd and Cr were detected in only one meat sample with concentration of 56.41 mg/kg and 14.44 mg/kg respectively. Lead was not detected in any of the meat samples. Asian Australas. J. Food Saf. Secur. 2021, 5 (2), 71-78

Enhancement of the Mechanical and Tribological Properties of Aluminum-Based Alloys Fabricated by SPS and Alloyed with Mo and Cr

Multicomponent aluminum-based alloys doped with chromium (Cr) and molybdenum (Mo), fabricated by spark plasma sintering (SPS), derived from a powder mixture prepared by mechanical alloying, were studied in this work. The morphology of the pristine and worn surfaces was analyzed using a scanning electron microscope equipped with an energy-dispersive X-ray spectroscopy system. The obtained alloys exhibited higher hardness (73 and 72) for the Al–Mo and Al–Cr alloys, respectively, compared to reference bronze. Besides improved hardness, SPS-sintered alloys also showed a lower value of the weight and linear wear and the highest score-resistance compared to bronze. The enhanced tribological behavior is related to the formation of secondary structures on the friction surfaces of rubbing pairs, which in turn reduce wear. For the first time, the present research has demonstrated the effectiveness of the addition of Mo and Cr for the fabrication of sintered multicomponent Al-based alloys with a tailored microstructure that induces the formation of secondary structures on the tribosurfaces due to the self-organization processes during friction.

Investigation on Optimal Ta/Cr Ratio of a Single Crystal Ni-Base Superalloy in View of the Isothermal Oxidation Behavior

The relative content of strengthening element tantalum (Ta) and oxidation-resistant element chromium (Cr) is an essential value for superalloys to obtain an excellent combination of oxidation resistance and mechanical properties. In the present paper, the isothermal oxidation behavior of several single crystal Ni-base superalloys with different Ta/Cr (wt. %, similarly hereinafter) ratios at 1000 °C in static air has been systematically investigated to explore the optimal Ta/Cr for excellent oxidation resistance. A detailed microstructure study using X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) and an electro-probe microanalyzer (EPMA) was performed to reveal the oxidation products and mechanisms. For all alloys, a three-layer structured scale consisting of an outer (Cr, Al, Ti, Ni, Ta)-O layer, an inner Al2O3 layer and an inner nitride layer was formed. As Ta/Cr increased, the amounts of Ta-containing products, cracks, holes and inner nitride increased. Meanwhile, the completeness of the Al2O3 layer got worse. It was shown that if Ta/Cr ≤ 0.5, Ta increased the growth rate of Cr2O3 via the doping effect induced by Ta cations. If Ta/Cr > 0.5, Ta reduced the completeness of Cr2O3 through competitive growth of Ta2O5 and Cr2O3. A good oxidation performance can be expected with the value Ta/Cr ≤ 0.5.

Metals contamination and trace element level in breast milk samples of mothers in Kenitra, Morocco

ABSTRACT The current study aimed to examine the quality of breast milk in Kenitra city (Morocco), regarding its levels of essential elements Iron (Fe), Copper (Cu), and Zinc (Zn) and heavy metals chromium (Cr), lead (Pb), and cadmium (Cd), besides carried out the inter-element correlation and investigated their association with some sociodemographic parameters of lactating women. For this, a total of 95 (n = 95) samples of breast milk were collected, at the second postpartum month from mothers in five governmental health care centres in Kenitra. After total mineralisation, human milk sample analysis was conducted by using flame atomic absorption spectrophotometry (AAS) for the essential elements detection, and heavy metal quantification was performed by using the atomic absorption spectrophotometer with a graphite furnace. Mean levels of Fe, Cu and Zn were 0.43, 0.26 and 6.11 mg/L, while the main concentrations of Cr, Pb and Cd were 8.84, 3.20 and 0.60 µg/L, respectively. Statistical analysis had proved a highly significant correlation between surveyed elements, especially between Cu and Zn, Pb and Cd, besides the strong relationship between the essential elements mentioned before and the heavy metals. Moreover, breast milk elements are most affected by sociodemographic parameters, principally the body mass index (BMI) of mothers, dietary habits and newborn gender. Moreover, 6.46% and 27.37% of samples are exceeded the recommended limits for Cd and Pb, respectively, which verify the low contamination of surveyed breast milk samples. Whereas, the mean values of Cr and Zn were above the limits recommended by the word human organisation, but so far there are no reports of adverse effects on newborns at those reported doses. These data justify the requirement to set surveillance policies by health organisations with the purpose of limit maternal and foetal exposure to heavy metals and strengthen health education.

Chromium induced neurotoxicity by altering metabolism in zebrafish larvae

BackgroundRecently, both trivalent chromium Cr (III) and hexavalent chromium Cr (VI) have been reported to produce neurotoxicity. However, the underlying mechanisms of the neurotoxicity caused by different chemical valence of chromium remain unclear. ObjectiveThe purpose of this study was to investigate the mechanism of neurotoxicity induced by exposure to chromium with different valence states based on metabolic disturbance in zebrafish larvae. MethodsZebrafish embryos were exposed to 1 mg/L Cr (III) and 1 mg/L Cr (VI) for 120 hpf respectively. The related indexes of neural development were observed by stereoscope and behavior analysis system. 8OH-dG were detected using enzyme-linked immunosorbent assay. The generation of reactive oxygen species was detected using an oxidant-sensing probe 2',7'-dichlorodihydrofluorescein diacetate. AChE activity was determined by a colorimetric assay based on hydrolysis of acetylcholine. The expression levels of neurodevelopmental genes and methyltransferase genes in juvenile zebrafish was analyzed by real-time PCR. The methylation status of neurogenin1 and neurod1 genes was detected by bisulfite sequencing PCR. The binding of H3K27me3 was detected by chromatin immunoprecipitation-qPCR. Metabolic profiles and one carbon metabolic analysis were performed by UPLC-MS. ResultsThere were no significant differences in survival rate, hatching rate and spontaneous movement of zebrafish in both Cr-exposed groups compared to the control. The malformation rate in Cr (VI) -exposed group was obviously increased compared to the control and Cr (III) -exposed group. At 48hpf and 72hpf of exposure, the embryonic heart rate in Cr (III)-exposed group was significantly higher than that of Cr (VI)-exposed group and the control. At 120hpf, zebrafish in both Cr-exposed groups exhibited decreasing changes in swimming distance and disturbance of sensitivity to light and dark. 8OH-dG in Cr (VI)-exposed group were significantly higher than that in the control. The generation of ROS in both Cr -exposed groups was significantly higher than that in the control. The activity of AchE was significantly decreased in both Cr-exposed groups compared to the control. Most of early neurogenesis related genes, such as α-tubulin, elavl3, gap43, sox19b, neurogenin1 and neurod1 in Cr-exposed groups were significantly up-regulated compared to those in the control. The expression of dnmt1 and dnmt3 genes was significantly down-regulated in both Cr-exposed groups. BSP-PCR results showed that genic sequences in the neurogenin1 and neurod1 genes have lower levels of DNA methylation in both Cr-exposed groups, especial in Cr (VI)-exposed group. ChIP analysis showed that there was a decrease in H3K27me3 binding within the corresponding region of neurogenin1 in both Cr-exposed groups and that of neurod1 in Cr (III)-exposed group. Untargeted metabolomic analysis showed that significant changes in metabolites induced by Cr exposure were associated with differences in primary bile acid biosynthesis, phospholipid biosynthesis (phosphatidylcholine biosynthesis and phosphatidylethanolamine biosynthesis), linoleic acid metabolism, arachidonic acid metabolism, amino acid metabolism, purine metabolism, betaine metabolism, spermidine and spermine biosynthesis, and folate metabolism, the last four of which are related to one carbon metabolism. Targeted analysis of one carbon metabolites (5-MT, Gly, Met, SAH and Hcy) related with folate cycle and methionine metabolism were significantly decreased upon Cr exposure. The elevated SAM to SAH ratio in both Cr- exposed group indicated the decreasing capacity for methylation reaction. ConclusionCr (III) and Cr (VI) can induce neurotoxicity by interfering with one carbon metabolism and affecting DNA methylation and histone methylation to regulate the expression of neuro-related genes. Cr exposure also influenced primary bile acid biosynthesis and phospholipid biosynthesis, which are associated with neuroprotective effects and need to be further validated.

Preparation and characteristic analysis of nanofacula array

The development of nanofacula array is an effective methods to improve the performance of Near-field Scanning Optical Microscopy (NSOM) and achieve high-throughput array scanning. The nanofacula array is realized by preparing metal nanopore array through the "two etching-one development" method of double-layer resists and the negative lift-off process after metal film coating. The shading property of metal film plays important rules in nanofacula array fabrication. We investigate the shading coefficient of three kinds of metal films (gold–palladium alloy (Au/Pd), platinum (Pt), chromium (Cr)) under different coating times, and 3.5 min Au/Pd film is determined as the candidate of the nanofacula array fabrication for its lower thickness (about 23 nm) and higher shading coefficient (≥ 90%). The nanofacula array is obtained by irradiating with white light (central wavelength of 500 nm) through the metal nanopore array (250/450 nm pore diameter, 2 μm pore spacing and 7 μm group spacing). Moreover, the finite difference and time domain (FDTD) simulation proves that the combination of nanopore array and microlens array achieves high-energy focused nanofacula array, which shows a 3.2 times enhancement of electric field. It provides a new idea for NSOM to realize fast super-resolution focusing facula array.

Assessment of potential human health risks in aquatic products based on the heavy metal hazard decision tree

BackgroundNaturally existing and human-produced heavy metals are released into the environment and cannot be completely decomposed by microorganisms, but they continue to accumulate in water and sediments, causing organisms to be exposed to heavy metals.ResultsThis study designs and proposes heavy metal hazard decision trees for aquatic products, which are divided into seven categories including pelagic fishes, inshore fishes, other fishes, crustaceans, shellfish, cephalopods, and algae. Based on these classifications, representative fresh and processed seafood products are at the root of the heavy metal hazard decision trees. This study uses 2,107 cases of eating 556 cooked fresh or processed seafood product samples. The constructions of the proposed decision trees consist of 12 heavy metals, which include inorganic arsenic (iAs), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), lead (Pb), strontium (Sr), thallium (Tl), and zinc (Zn). The heavy metal concentrations in cooked fresh and processed seafood product samples are subjected to a food safety risk assessment.ConclusionsThe results indicate the relationships among the seven categories of aquatic products, the relationships among 12 heavy metals in aquatic products, and the relationships among potential human health risks. Finally, the proposed heavy metal hazard decision trees for aquatic products can be used as a reference model for researchers and engineers.

Biodiversity and Sediment Contamination in Wet Stormwater Ponds Depending on Design and Catchment Characteristics

Stormwater ponds are a common way to handle stormwater and are used to retain pollutants through sedimentation. The ponds resemble small natural lakes and will be colonized by flora and fauna. How design with respect to age, ratio between wet volume and reduced catchment area and land use influences the retention and how biodiversity is affected was examined. Age and ratio were determined in 135 and 59 ponds, respectively, and 12 of these ponds were selected for studies of dry weight (DW), organic matter (OM), total phosphorus (TP) and aluminum (Al), zinc (Zn), copper (Cu), chromium (Cr), cadmium (Cd) and lead (Pb) in the sediment. Invertebrate biodiversity was determined by Shannon–Wiener index (H’) and Pielou Evenness (J). DW, OM, TP and metals in the sediment close to the outlet of the ponds were influenced by pond age and the volume/area ratio whereas the sediment in the inlet area was more affected by the catchment type. Biodiversity increased with increasing ratio, while age had no effect on the sediment biodiversity but some effect on the water phase biodiversity. Biodiversity decreased with higher OM and TP and tend to decrease with increasing metal content. Higher volume/area ratio results in less sediment accumulation which improves the biodiversity. More pollutants are accumulating with age, which negatively affects the biodiversity. In conclusion, pond ratio, catchment type and, to some extent, age effect the load of contaminants in the sediment and the pond biodiversity. Proper design and management are recommended as a mitigating measure.

Heavy Metal Content Analysis and Toxicity Assessment of Oil-Based Drilling Mud using Zebrafish Embryos

Aim: Used oil-based drilling muds (OBDMs) are toxic to marine organisms due to the fluid’s complex chemical nature. The illegal dumping of used OBDMs is still rampant in many parts of the world despite of the stringent laws and regulations pertaining to its disposal. To date, study of the assessment of heavy metal content in used OBDMs from the Malaysian oil and gas industry has been limited. Furthermore, the study of the toxic effect of OBDMs using a zebrafish embryo model has never been reported before. Therefore, in this research, the used oil-based drilling muds (OBDMs) were analyzed for their heavy metal content and toxicity against Zebrafish embryos. Methods: Used OBDMs were collected from an Anchor Handling Tug Supply (AHTS) vessel mud tank from Kemaman, Terengganu. The heavy metal content in the mud was analyzed using ICP-AES. Zebrafish embryos were exposed to OBDMs of varying concentrations (i.e., 0.25 mg/ml, 0.125 mg/ml, 0.06 mg/ml, 0.03 mg/ml, 0.015 mg/ml, 0.0076 mg/ml, 0.0034 mg/ml and 0.0019 mg/ml). The toxicity and teratogenicity of the mud on zebrafish embryos were assessed every 24 hours, for 96 hours, using endpoints like embryo mortality, heart rate and hatching rate. Results: The heavy metal content of used OBDMs had the highest concentration of barium (Ba) 2360 ppm, followed by lead (Pb) 120 ppm, zinc (Zn) 104 ppm, arsenic (As) 9 ppm, and chromium (Cr) 16 ppm, with cadmium (Cd) concentration of less than 1 ppm being the lowest. The Ba (2360 mg/L) concentration in the OBDM sample exceeded the concentration of Ba in normal marine sediment reported to be around 2000 mg/L. The 96 h LC50 of the OBDM in zebrafish embryos was reported to be 0.005 mg/mL (5 ppm). Zebrafish embryos that were exposed to high concentrations of OBDMs exhibited a lower hatching rate and reduced heart rate than the control group. Conclusion: The findings of this study are indicative of the highly toxic nature of used OBDMs and its dosage-dependent teratogenicity effects on zebrafish embryo. Knowledge of the potential environmental impacts of OBDMs released into the marine environment can be the basis for prudent decision-making that will help minimize environmental damage.

Urban mosquitoes and filamentous green algae: their biomonitoring role in heavy metal pollution in open drainage channels in Nairobi industrial area, Kenya

BackgroundIndustrial wastewater is a human health hazard upon exposure. Aquatic organisms in contaminated wastewater may accumulate the toxic elements with time. Human population living in informal settlements in Nairobi industrial area risk exposure to such toxic elements. Biomonitoring using aquatic organisms in open drainage channels can be key in metal exposure assessment. Levels of Mercury (Hg), Lead (Pb), Chromium (Cr), Cadmium (Cd), Thallium (Tl), and Nickel (Ni) were established in samples of wastewater, filamentous green algae (Spirogyra) and mosquitoes obtained from open drainage channels in Nairobi industrial area, Kenya.ResultsPb, Cr, & Ni levels ranged from 3.08 to 15.31 µg/l while Tl, Hg, & Cd ranged from 0.05 to 0.12 µg/l in wastewater. The Pb, Cr, Ni, & Cd levels were above WHO, Kenya & US EPA limits for wastewater but Hg was not. Pb, Cr, Tl, & Ni levels in assorted field mosquitoes were 1.3–2.4 times higher than in assorted laboratory-reared mosquitoes. Hg & Cd concentrations in laboratory-reared mosquitoes (0.26 mg/kg & 1.8 mg/kg respectively) were higher than in field mosquitoes (0.048 mg/kg & 0.12 mg/kg respectively). The levels of Pb, Cr, & Ni were distinctively higher in field mosquito samples than in wastewater samples from the same site. Pb, Cr, Ni, Cd & Hg levels in green filamentous Spirogyra algae were 110.62, 29.75, 14.45, 0.44, & 0.057 mg/kg respectively. Correlation for Pb & Hg (r (2) = 0.957; P < 0.05); Cd & Cr (r (2) = 0.985; P < 0.05) in algae samples was noted. The metal concentrations in the samples analyzed were highest in filamentous green algae and least in wastewater.ConclusionWastewater, mosquitoes, and filamentous green algae from open drainage channels and immediate vicinity, in Nairobi industrial area (Kenya) contained Hg, Pb, Cr, Cd, Tl, and Ni. Mosquitoes in urban areas and filamentous green algae in open drainage channels can play a role of metal biomonitoring in wastewater. The potential of urban mosquitoes transferring heavy metals to human population from the contaminated wastewater should be investigated.

Dusts Control operations in Ririwai Mines, Kano State, Nigeria

Respirable dust is everywhere (in the surface and underground mine) operations and its environs. Ririwai Tin mine is laden with dust of metallic particles of Arsenic (As), Chromium (Cr), Lead (Pb) and Zinc (Zn). These particles are also found in the soil. Continuous inhalation of dust could lead to irreversible diseases. This paper addresses the control of dust, using previous review of prevailing metallic concentrates. This research answers questions like which are the dust control strategies to be adopted by Ririwai tin mine to obtain best practice? What challenges will Ririwai tin mine face when applying dust control methods in their operation? What is the impact of dust laden with metallic particles on soil, water, vegetation and man in Ririwai tin mine?

Dusts Control operations in Ririwai Mines, Kano State, Nigeria

Respirable dust is everywhere (in the surface and underground mine) operations and its environs. Ririwai Tin mine is laden with dust of metallic particles of Arsenic (As), Chromium (Cr), Lead (Pb) and Zinc (Zn). These particles are also found in the soil. Continuous inhalation of dust could lead to irreversible diseases. This paper addresses the control of dust, using previous review of prevailing metallic concentrates. This research answers questions like which are the dust control strategies to be adopted by Ririwai tin mine to obtain best practice? What challenges will Ririwai tin mine face when applying dust control methods in their operation? What is the impact of dust laden with metallic particles on soil, water, vegetation and man in Ririwai tin mine?

PHYSICOCHEMICAL COMPOSITION AND HEAVY METAL DETERMINATION OF SELECTED INDUSTRIAL EFFLUENTS OF IBADAN CITY, NIGERIA

The rise of heavy metal presence in environmental waters has made it necessary to continuously examine industrial effluents to maintain the quality of the environment. The focus of this study is centered on determining the heavy metal concentrations and some physicochemical parameters in twelve industrial effluents samples collected from various locations across Ibadan city. A composite sampling method was utilized to obtain representative effluent samples of the 12 Industries (categorized into food, beverage, tobacco, plastic, Pharmaceutical, chemical, and allied industries) and borehole samples from around the city were used as control. The effluent samples were digested by nitric acid (HNO3) and analyzed for cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), and lead (Pb) using the atomic absorption spectrophotometric method (AAS). Some physicochemical parameters such as pH (Jenway 3510 pH meter), total dissolved solids (Hanna TDS meter), total suspended solids, and phosphate were determined. The heavy metal mean values were compared with Federal Environment Protection Agency (FEPA) and the United States Environmental Protection Agency (USEPA) standard values shown in table 1. The mean concentrations of heavy metal in the industrial effluent samples were Cu (0.32 mg/L), Pb (0.037 mg/L), Ni (0.50 mg/L), Co (0.037 mg/L), Cd (0.016 mg/L), Fe (54.0 mg/L) and Cr (0.44 mg/L). It was found that Chemical and allied industries have the highest concentration for metals such as Fe (128 mg/L), Ni (1.1 mg/L), and Cu (0.27 mg/L) while Cr (0.0067 mg/L) and Co (0.08 mg/L) were obtained in the Food/Beverage and pharmaceutical industries respectively. Conclusively, the industries around the Ibadan city stand as potential contributors to pollution, hence a periodical and continuous assessment effort are recommended.

Status of accumulated heavy metals in soils from organic and conventional farms in Akinyele Local Government, Ibadan, Oyo State, Nigeria

The risk associated with the presence of heavy metals in soil is their potential toxicity and ability to enter the ecosystem through the food chain. Total heavy metal content of a soil is inadequate for predicting the toxicity of heavy metals in soil. Therefore, the current study was designed to determine the various forms in which the selected heavy metals: Chromium (Cr), Lead (Pb), Nickel (Ni), and Cadmium (Cd) exist in the soil to ascertain the available forms for plant uptake. Soils samples were randomly collected from selected organic and conventional farms in Akinyele local government, Ibadan, Oyo State, Nigeria, at different depths (0-15, 15-30 and 30-45 cm) using random sampling method. Routine analysis was carried out to determine the textural classes and chemical properties of soil samples. The total heavy metals of the soil samples were determined and their fractions were analysed using sequential extraction method. Cadmium was not detected in most of the soil samples. Residual fraction was predominant in all the analysed heavy metals. In addition, Cr was more associated with the oxidizable fraction having a range of 0.1 mg/kg from Ajibode organic farm (AO) at 30-45 cm depth. Pb and Ni were both more associated with reducible fraction with Pb having a range of 2.7 mg/kg in Ajibode conventional farm (AI) at 0-15 cm depth and 0.1 mg/kg in (AI) at 30-45 cm depth. Reducible values of Ni ranges from 4.3 mg/kg in AI at 0-15 cm to 1.4 mg/kg in AO at 30-45 cm. The apparent mobility and bioavailability for these heavy metals in the studied soils were in the order: Pb&gt;Cr&gt;Ni. The result showed that uptake of heavy metals by the plants would be low as the concentration of the exchangeable form of the heavy metals in the analysed soil sample has the least concentration when compared with the other forms.

Levels of heavy metals in pelagic and benthic fish species in river Nun at Amassoma, Bayelsa State, Nigeri

The heavy metals content in three fish species from River nun Amassoma axis was investigated. This was done in order to gauge the concentration of heavy metals in fish tissues and to estimate the safety of consuming these fish species on human health. Three species (pelagic and benthic fishes) were collected from local fishermen at the landing jetty and analyzed for heavy metals in the soft tissues using standard procedures. The heavy metals investigated are Cadmium (Cd), Nickel (Ni), Lead (Pb) and Chromium (Cr). Result indicates that Cd&gt;Ni&gt;Pb&gt;Cr in the fish samples analyzed while Chrysichthys auratus showed the greatest abundant characteristics of Cr, Pb, Ni, Cd. There was no significant difference (P&gt;0.05) in concentrations of Cr and Ni for all fish species. However, the results showed that there is a significant difference (P&lt;0.05) in Pb concentration between Chrysichthys auratus, Chrysichthys aluuensis and Petrocephalus bane bane. Cd concentration in the fish species reveal that there is a significant difference (P&lt;0.05) between Chrysichthys auratus and Petrocephalus bane bane but no significant difference (P&gt;0.05) between Chrysichthys auratus and Chrysichthys aluuensis and between Chrysichthys aluuensis and Petrocephalus bane bane Heavy metal in the fish species showed that Chrysichthys auratus&gt;Chrysichthys aluuensis&gt;Petrocephalus bane bane. All metal characteristics were lower than the suggested WHO permissible limit. Benthic fish species have a greater heavy metal concentration than the pelagic fishes. Based on the observation from this study, the continuous and sustained consumption of Chrysichthys auratus and indeed benthic fish species possess a higher risk to health, while Cd poisoning in fish is most culpable of pollution in River Nun at Amassoma. axis.

Heavy Metal Concentrations in Malaysian Adults' Hair and Associated Variables in Bukit Mertajam, Penang, Malaysia.

The presence of heavy metals in human hair is being tracked to predict health risk, forensics, and environmental monitoring. Heavy metals are typically non-biodegradable and have a lengthy half-life, allowing them to linger in humans and the environment for many years. Heavy metal exposure in hair has been attributed to multiple sources from the environment and food intake. In this study, copper (Cu), nickel (Ni), zinc (Zn), chromium (Cr), manganese (Mn), lead (Pb), and cadmium (Cd) levels were measured in the scalp hair of 50 individuals in Bukit Mertajam, Penang, Malaysia. In conjunction with sampling, subjects' age, gender, lifestyle, diet, and working environment were also obtained through the questionnaire. The Atomic Absorption Spectrometry (AAS) method was used to extract all the metals in the hair samples. The mean concentrations of heavy metals were found to be in the following order (unit of mg/kg): Cr > Zn > Pb > Ni > Cd > Cu. Manganese was detected below the limit of quantitation among the elements (< LOQ). All elements except Mn were higher and comparable to the previous studies' international limit values. Cadmium prevalence was substantially associated with age, smoking habit, dyed hair, and working environment in Pearson's correlation analysis (p ≤ 0.05). Zinc was also found to be related to the working environment. Some elements were observed to be statistically related between heavy metals, Cd/Zn, Cd/Ni, Cr/Ni, and Pb/Ni, whereas smoking habit/dyed hair and dyed hair/working environment were the associated factors for metal distribution that were statistically correlated (p ≤ 0.05). To recapitulate, this study found that the distribution of heavy metals in hair was influenced by associated factors and between heavy metals. It has been indicated that heavy metal exposure to humans is influenced by factors such as geographical location, lifestyle, and working environment.

Accumulation of heavy metals and antioxidant defense system in the gametophyte of Didymodon rigidulus Hedw. in areas with high traffic loads

Background. Various modes of transport are among the main sources of environmental pollution with heavy metals and other pollutants. Bryophytes are known to accumulate heavy metals; however, metabolic changes in mosses under conditions of metal accumulation have not been extensively studied. The aim of this article was to analyze the accumulation of heavy metals, the process of lipid peroxidation (LPO) and the activity of enzymes of the antioxidant system in Didymodon rigidulus Hedw. moss collected in urban areas with an intense load created by road and railway transport. Materials and Methods. Gametophyte shoots were collected at three sampling sites in the city of Lviv (Ukraine). Site 1 was selected in a park zone, which was considered a control one; sites 2 and 3 were selected in areas with heavy road and rail traffic, respectively. Concentrations of chromium (Cr), nickel (Ni), lead (Pb), and zinc (Zn) in the moss material were determined by atomic absorption spectrophotometry. The levels of LPO products, namely lipid hydroperoxides and thiobarbituric acid reactive substances (TBARS), as well as superoxide dismutase (SOD) and catalase activities, were determined by standard methods. The results were processed using the methods of variation statistics. Results. Moss D. rigidulus growing in the park area (site 1) accumulated metals in the following order of decreasing concentration: Zn&gt; Cr&gt; Ni&gt; Pb. Gametophyte shoots of D. rigidulus collected at site 2 accumulated higher levels of Pb, Zn and Ni (by 2.27, 1.78 and 1.45 times, respectively), and at site 3, higher levels of Pb and Zn (by 1.8 and 1.67 times, respectively) compared to gametophytes collected in the park zone. In the moss samples from these sites, no significant differences in the Cr content were found as compared to the control. Concentration of lipid hydroperoxides in the moss sampled at sites 2 and 3 was 4.26 and 3.75 times higher, respectively, compared to the control, and TBARS production was more intense in plant material from site 2 than from the control site. SOD and catalase activities were considerably increased in D. rigidulus moss from site 2 compared with those from the control area; however, the activity of both enzymes in the moss samples from site 3 did not significantly exceed the control levels. Conclusions. Both road and rail traffic loads contribute to the accumulation of heavy metals, especially Zn and Pb, in D. rigidulus moss growing in the surrounding areas. Under such conditions, LPO process is stimulated, which is more pronounced in moss growing in area with heavy road traffic. The increased activity of antioxidant enzymes (SOD and catalase) in moss growing in this area can play an important role in protecting bryophyte cells against metal-induced oxidative stress under conditions of intense metal accumulation.

Heavy metals in shell fishes of Ojo River, Lagos State, Nigeria

&#x0D; &#x0D; &#x0D; The research examined the accumulations of six heavy metals including chromium (Cr), lead (Pb), iron (Fe), zinc (Zn), cadmium (Cd), and copper (Cu) in water as well as in three male and female species of crab (Cardisoma armatum, Callinectes danae, Callinectes ornatus) sampled from Ojo River in Lagos State of Nigeria. Physico-chemical parameters of the water samples from the River and heavy metal concentrations in the crab species obtained also from the River were examined using standard methods. The results showed that total dissolved solute (TDS), electrical conductivity (EC), salinity, dissolved oxygen, biological oxygen demand and chemical oxygen demand varied significantly along the River course, with TDS and EC being relatively high. Heavy metals detected in the crabs were Fe, Cu and Zn, with Cu being the highest in the species examined. The species C. ornatus presented the highest content of Cu followed by C. armatum and C. danae. The content of heavy metals (mg kg–1) among the crab species showed that Cu (23.47±0.10) &gt; Zn (19.06±0.01) &gt; Fe (16.85±0.01) in all the species except in C. armatum where Fe (1.26±0.44) was &gt; Zn (1.19±0.02). Furthermore, Pb, Cd and Cr were not found in the crabs and this could be associated with the fact that the area consists mainly of residential houses, farms and a few industries. Notably, the content of the heavy metals was larger in the female than the male crabs. This study reported different levels of heavy metal accumulation in male and female species of crabs. Also, the shell fishes from Ojo River might be considered safe for consumption, but the need for continuous monitoring to prevent bioaccumulation is recommended.&#x0D; &#x0D; &#x0D;

Effectiveness of common macrophytes for phytoremediation of hexavalent Cr prevalent in chromite mining areas

Hexavalent chromium Cr(VI) is carcinogenic. To reduce Cr(VI) toxicity, a study was undertaken to assess the effectiveness of common macrophytes in the range of Cr concentration prevalent in chromite mining areas at Sukinda, Odisha, India. The metal varied from 0.09 to 2.14 mg/L during 2016 − 2019 and indicated that ≅70% waterbodies are contaminated with Cr(VI). Phytoremediation experimentation using five common macrophytes resulted in Pistia stratiotes, Salvinia minima and Ipomoea aquatica as suitable species by remediating 57 to 100% Cr(VI) from 0.2 to 1.0 mg/L within 54 days. S. minima had then found to remove 1 to 1.8 and 1.6 to 2.8 times more Cr (total) than P. stratiotes and I. aquatica respectively from a level of 0.5 to 2.5 mg/L Cr(VI) within 49 days. Irrespective of plant-duration, P. stratiotes excelled over S. minima by 59 to 68% and I. aquatica by 55 to 89% in BCF value. S. minima thus proved best by removing maximum Cr per unit time while the combination of S. minima and P. stratiotes would have promise in respect of generating low volume of remediated biomass in phytoremediation of Cr(VI). Novelty statement Macrophytes differ in their response to remove metal, screening against a given metal concentration suggests the suitable species and testing signifies their effectiveness of remediating metal from contaminated sources.

Study on removal of Microcystis aeruginosa and Cr (VI) using attapulgite-Fe3O4 magnetic composite material (MCM)

In order to remove Microcystis aeruginosa (M. aeruginosa) and hexavalent chromium Cr (VI) from wastewater, attapulgite was modified with hydrochloric acid and mixed with ferroferric oxide (Fe3O4) to prepare magnetic composite material (MCM), which could be utilized to flocculate M. aeruginosa and adsorb Cr (VI) effectively, and could be taken out from water easily under external magnetic field. The experimental results showed that the MCM could precipitate the M. aeruginosa with the removal rate over 96% within 10 min, and in the meantime, it could efficiently adsorb Cr (VI) with the removal rate of Cr (VI) reaching 95% within 5 min. The adsorption of Cr (VI) by MCM conforms to the pseudo-second-order kinetic model, and the isotherm model for the adsorption of Cr (VI) conforms to the Langmuir equation. The adsorption amount of Cr (VI) decreased with the increase of temperature, indicating that the adsorption process of Cr (VI) was exothermic. This work therefore proposes a new approach for treatment of wastewater containing M. aeruginosa and Cr (VI), and also elucidates the adsorption properties of the applied material.