High Amounts Of Heavy Metals Research Articles

Heavy Metals in Tree Parts (Roots, Bark, Leaves) and Fruits Grown in Mechanic Workshops in Nigeria

The day-to-day activities carried out at the mechanic workshop like panel beating, welding, and automobile battery servicing may result in high amounts of heavy metals in the soil near mechanic workshops. Spent engine oils also emit a huge number of toxic metals, when disposed of on the floor at workshops, they settle on soil and are absorbed into nearby trees and plants. Therefore, making the tree parts and fruits at mechanic workshops prone to attack by heavy metals. This work is focused on testing if the presence of heavy metals would have adverse effects on the tree parts (roots, shoots, upper leaves, lower leaves) and fruits of mechanic workshops. A mechanic village in Abeokuta, Ogun State was chosen as the case study. The tree parts were oven-dried, ground, digested, and taken for analysis using AAS. Zinc (Zn), Lead (Pb), and Mercury (Hg) were found in higher amounts than the recommended allowable limits by WHO/FAO. Results show that the upper bark had the highest heavy metal concentration. In general, the tested heavy metals were recognized in the order: Zinc (Zn) > Lead (Pb) > Mercury (Hg) > Nickel (Ni) > Manganese (Mn) > Iron (Fe) > Copper (Cu). It is recommended that mechanic villages should be sited far from residential areas. Remediation of polluted soil should be encouraged. Phytoremediation was suggested to be the best method for reducing the concentration of heavy metal in the soils and tree parts at mechanic workshops. Continuous education and training should be provided for automobile repairers/ mechanics, emphasizing the environmental implications of their poor occupational waste management and the dangers of eating fruits and taking herbs from trees planted in workshops.

Rubus plicatus Weihe & Nees: resilience to pollution caused by stone quarries

This study aimed to analyze the effect of pollution caused by stone quarries on the morpho-anatomy, biochemistry, and physiology of a medicinal wild bramble Rubus plicatus Weihe & Nees. Samples were collected from two natural protected areas: Iron Gates Natural Park and Jiu Gorge National Park, both located in the southwestern part of Romania, and two unpolluted areas from these parks as background sites. We carried out the following analyses on the collected leaves of this taxon: morphology, micromorphology, anatomy, assimilating pigments, heavy metals (Pb, Ni, Cr, Fe), dry mass, bioactive compounds (total phenols and flavonoids), and antioxidant capacity. The results showed more stomata, higher amounts of assimilating pigments, higher amounts of heavy metals (especially lead), less dry mass, less phenols, and more flavonoids in Rubus plicatus leaves from polluted areas compared to areas without sources of pollution. The increased number of stomata and the amounts of assimilator pigments revealed the mechanisms developed by this species in order to survive in polluted conditions.

Impact of industrial effluent on selected grass species

Industrial wastewater contains a variety of substances such as organic carbon, salts and heavy metals, which along with arsenic (As), cadmium (Cd), lead (Pb) and nickel (Ni) are known to be highly toxic even in very low concentrations. This study was carried out to test the impact of industrial effluent from the Industrial Estate Islamabad, the capital city of Pakistan, on four local grass species of the Pothohar region, i.e., Panicum maximum (Mombasa grass), Cenchrus ciliaris (Dhaman grass), Cynodon dactylon (Khabbal grass) and Chloris gayana (Rhodes grass). These grasses were grown in tap water (T0), industrial effluent (T1), and in industrial effluent-tap water ratio (50:50; T2). The concentrations of As, Cd, Pb, and Ni accumulated by these grasses were appraised with inductively coupled plasma optical emission spectrometry (ICP-OES). All four grasses differed significantly in terms of their accumulation of different types of metal elements in the shoot and root organs. The analysis of industrial effluent, and root and shoot biomass samples of all four grasses did not have high amounts of heavy metals with reference to the levels of the metals documented by WHO. It is generally recommended that the effluents from the Industrial Estate Islamabad can be used with some caution for growing forage grasses including the four species tested in this study.

The pH of Drinking Water and Its Human Health Implications: A Case of Surrounding Communities in the Dormaa Central Municipality of Ghana

Of all the things to consider about safe water, the pH of drinking water probably has been overlooked. Most spoken about, however, is alkaline water which has a host of supposed health benefits? For instance, it is known to help the body to clear toxins thereby improving metabolism. Meanwhile, research has shown that most diseases, illnesses, and bad bacteria thrive in an over-acidic environment. Additionally, the acidic water indirectly may impact on budget as this would contribute to the metallic or sour taste of drinking water, and stained laundry and provide blue-green staining of sinks and other household fixtures. Acidic water having low pH often are known to contain high amounts of heavy metals. Also, research has found that solutions with low pH are more likely to have heavy metals from the environment. Other researchers have identified that acidic water can be high in Pb, As, Cu, Ni, Cb, Cr, and Zn. All these elements fall under heavy metals and exposure to them can be dangerous, and could lead to heavy metal poisoning and toxicity. This is concerning as water is said to be life and the population within Dormaa Central Municipality is most likely to have symptoms such as diarrhoea, nausea and vomiting, abnormal pains, weakness, shortness of breath, suppression of the immune system, organ damage, and enamel wearout leading to dental cavities. Water samples and their corresponding spatial locations were collected from (how many?) communities within the Dormaa Central Municipality. The potential for hydrogen (pH) readings of the respective water samples was measured using a pH meter. The results obtained range from 0.2 mmHg to 6.5 mmHg.

Synthesis of geopolymers using municipal solid waste incineration fly ash and construction and demolition waste: Mechanical and thermal activation

The safe disposal and utilization of MSWI FA, enriching with high amounts of heavy metals, chlorides and organic pollutants, has turned into a critical problem that restricts MSWI development. In this study, the resource utilization feasibility of MSWI FA with CDW and GGFBs by geopolymers was analyzed, and the performance of geopolymers with the different MSWI FA dose and activation method was investigated. With the increase of MSWI FA addition, the compressive strength of geopolymer showed a trend of first increasing and then decreasing. Mechanical and thermal activation had a significant effect on the properties of geopolymers through improving the reactivity of raw materials and promoting hydration reaction. Various characterization methods indicated hydration products such as CSH, CASH and NASH gel were generated in geopolymers. In terms of S/S of pollutants, geopolymers exhibited excellent capability. Compared with MSWI FA, the concentration of heavy metals, especially Pb, in the leachate from geopolymers was significantly reduced due to the transformation of heavy metals into more stable forms. Moreover, mechanical and thermal activation could promote the S/S of heavy metals, except Pb and Zn. After geopolymerization, the total TEQ of PCDD/Fs decreased from 42.8 to 4.7 ng TEQ/kg with the IE of 45.09%. This article provides a new method for the collaborative resource utilization of MSWI FA, CDW and GGFBs.

Prospects of green roof technology as a sustainable solution to urban pollution index

This study was conducted to explore the impact of rooftop plantations on local air quality under agro-ecological conditions of Lahore and Faisalabad. An optoelectronic sensing device was used to capture particulate matter concentration, while heavy metal detection was carried out from dust samples collected randomly from different sites with no or varying levels of vegetation cover in comparison to bare roofs. It was revealed that the average particulate suspension rate was 13–24% lower on roof gardens as compared to bare roofs while a higher amounts of heavy metals were detected from bare roof dust samples. Lead was maximum in midtown and baseline areas in both cities, while it was most ubiquitous heavy metal in all locations than zinc, copper and nickel combined.The pollution load index revealed that Lahore has a higher level of pollution load as compared to Faisalabad. Moreover, pollution load index for Lahore is generalized as maximum in midtown (1.64) followed by baseline (1.48), typical roof (0.98), roof garden (0.78) while standard garden has least (0.75). In Faisalabad high pollution load index was recorded in midtown (1.48), baseline line (1.36) and typical roof (1.08) while standard garden and roof garden were scaled under low pollution level with pollution load index of 0.69 and 0.60. Results confirmed that plantation in form of big trees only or plantations with small trees, shrubs, and ground covers were effective in capturing dust and heavy metal compared to areas with no vegetation at all. Conversely, plantation on rooftop was as effective as plantation on ground compared to bare roofs for mitigating pollution load in urban areas. The present study suggested that utilizing roofs in residential and commercial areas of Faisalabad and Lahore could be an efficient strategy to counter air pollution in near future.

Telfairia Occidentalis Leaf Concentrations of Hg, Pb and Cd Planted in Old Sewage Sludge Dumpsites in Owerri Imo State

Leaves of Telfairia OCCIDENTALIS planted in abandoned Sewage Dumpsite were analyzed for mercury Hg, Lead Pb and Cadmium Cd levels. Samples were collected from three dump areas at a depth of 0-30cm, and fallow lands of about 50 meters away from the dumps were also sampled for reference. The samples were subjected to analysis and Heavy metals were determined using Atomic Absorption Spectrophotometer (AAS). The findings indicated that sewage increased the soil concentrations of Heavy Metals (0.19 Hg, 17.0 Pb, and 3.0 Cd Mg/Kg1) when compared with control (0.04 Hg, 1.4 Pb, and 0.29 Cd Mg/Kg1). These were not high when compared with established permissible limits according to FEPA WHO. These concentrations were not high to cause health challenges. Many scientist reported that not all sewage sludge contains high amount of heavy metals especially when allowed to decompose for a longer period of 4 years even without prior treatment, but repeated application can increase levels. Sewage Sludge also increased N, P, K, Ca, Mg, K and ECEC and this may triggered the reason of continuous planting by farmers in dumpsites due to the fact that sewage sludge can increase the nutrient content of soil and improves its physical and chemical properties. Organic matter content which is also of great importance in soil reaction was increased by the sewage sludge deposit. The deposit of sewage sludge added organic matter, improved the soil physical and chemical properties, at the same time increased the heavy metals levels. But the heavy metals levels were not above permissible limits for heavy metal concentrations in soils. It is therefore recommended to land spray the sludge and allowed to decompose for about 2 years before planting on it. The result was discussed in-line with heavy metals in questions and permissible limits for each.

Evaluation of metal pollution related to human health risk in freshwater snail Viviparus contectus (Millet, 1813) as a potential bioindicator species in Lake Habitat (Turkey).

Freshwater mollusks are employed as bioindicators for the assessment of water quality in biomonitoring studies since the water quality of natural resources is crucial for humans. The freshwater snail species known as Viviparus contectus (Viviparidae: Gastropoda) is one that people eat. Here, the levels of heavy metals (Cd, Cr, Pb, As, Zn, and Cu) in water and V. contectus samples were determined. An Inductively Coupled Plasma Atomic Emission Spectrometer (ICP-AES, Spectro Arcos, vertical plasma) was used for the analysing the heavy metal concentrations in water and freshwater snail samples. The results of the current investigation demonstrated that freshwater snails accumulated metals in their water and soft tissues in the following orders: Pb > Cr = Zn = Cu = Cd = As and Zn > Cu > Pb > Cd > As = Cr. Autumn was the time of year when higher amounts of heavy metals (As, Cr, Cu, Zn, and Hg) were found. Pb content in the freshwater snail samples was strongly impacted by seasonal fluctuations (P 0.05). For adults, the EDI (estimated daily intake) values were lower than the TDI (tolerable daily intake) values, and the HI (hazard index) values were below 1. Freshwater snail samples had Zn and Pb levels that were over the FAO/WHO, Turkish Food Codex, JECFA, and EC limit values. Except for Pb, the water study shows mean metal concentrations below the USEPA, Turkish Pollution Control Regulation, and World Health Organisation maximum allowed levels. Aquatic ecosystems were negatively impacted by anthropogenic activities overall, and this study can provide a helpful data set for investigations on metallic contamination in water bodies and biomonitoring in freshwater ecosystems.

ASSESSMENT OF HEAVY METAL LOAD IN FRUITS AND VEGETABLES CONSUMED IN AND AROUND ANAMBRA STATE POLYTECHNIC, MGBAKWU

Fruits and vegetables are of plant source and are consumed a lot by human and animals. Fruits and vegetables could be contaminated with heavy or toxic metals through contaminated soil and water with these heavy metals. Contaminated fruits and vegetables consumed by man and animals will gradually build up of this toxins and if not detoxified faster in the body will build up to a concentration higher than the permissible level (Zurbrugg et al., 2003). Human activities such as industrial production, mining, agriculture and transportation release a high amount of heavy metals to the biosphere. The primary sources of metal pollution are the burning of fossil fuels, smelting of metal like ores, municipal wastes, fertilizers, pesticides and sewage (Xiaoli, 2007; Radwan and Salama, 2006; Wilson and Pyatt, 2007). The purpose of this quantitative study was to examine the level of heavy metal load of fruits and vegetables consumed in and around Anambra State Polytechnic, Mgbakwu, Southeast Nigeria. Local officials may utilize this study's results to develop a standard that can improve the quality of commercially sold fruits and vegetables in and around the locality.

Chemistry-driven Enchytraeidae assemblages acting as soil and ecosystem engineers in edaphic communities

Smaller body-sized invertebrate groups are known to be highly sensitive to environmental pollution. Like soil nematodes, enchytraeids have very permeable cuticles and come into direct contact with heavy metals; therefore they can be adversely affected by soil pollution. However, in contrast to nematodes, fewer data on enchytraeids are at our disposal to assess their functional responses to heavy metals. Such an assessment would be of greatest value, as in any edaphic community, enchytraeids are the only functional group bridging the detrital energy flux across the bacterial-driven and the fungal-driven pathways. For this purpose we investigated and evaluated the effect of heavy metals on the occurrence and biomass of enchytraeids in different soils in The Netherlands. Samplings of topsoils were carried out in 297 sites with Pleistocene sandy soils, river clay and sea clay under different environmental stress and all recovered enchytraeid species have been included in three existing phylogenetical clades (hereafter: A, B, and C). Our results show that the biomass of the enchytraeid species belonging to the Clade C is highly correlated with Cr, Cu and Zn in sandy soils (all 2-tails significance values share p < 0.005, n = 186) but is correlated with Cu and Hg in loamy soils (p < 0.05, n = 111), whilst the biomass of the enchytraeid species belonging to the Clade B is highly correlated with either Cd + Cu + Pb in sandy soils (p < 0.025, n = 186) or Hg + Pb in loamy soils (p < 0.05, n = 111). The entire enchytraeid community actively contributes to promote the rapid turnover of soil organic matter. Given that clay-rich soils retain a much higher amount of heavy metals in contrast to sandy soils, most enchytraeids share different values as bioindicators according to the soil type, even comparing river clay with sea clay. Hence, elemental availabilities have disproportionately strong effects on enchytraeids and on the entire edaphic community according to the soil types.

Heavy metals in daily meals and food ingredients in the Yangtze River Delta and their probabilistic health risk assessment

Heavy metal exposure via food consumption is inadequately investigated and deserves considerable attention. We collected hundreds of food ingredients and daily meals and assessed their probabilistic health risk using a Monte Carlo simulation based on an ingestion rate investigation. The detected concentrations of four heavy metals (Cr, Cd, Pb, and Hg) in all daily meal samples were within the limits stipulated in the National Food Safety Standard (GB 2762-2017), while that for As level was excessive in 0.3 % of daily meal samples. The same results were also observed in most food ingredient samples, and a standard-exceeding ratio of 23 % of As was observed in aquatic food or products, especially seafood, which was with the highest concentration reaching 1.24 mg/kg. Combining the detected heavy metal amounts with the ingestion rate investigation, the hazard quotients (HQs) of As, Cr, Cd, Pb, and Hg in daily meals and food ingredients were all calculated as lower than 1 (no obvious harm), while the incremental lifetime cancer risk (ILCR) of As and Cr (>1 × 10−4), indicating that the residual As posed potential health effects to human health. It was noteworthy that the proportion of aquatic foods only accounted for 6.3 % of daily meals, but they occupied 41.1 % of the heavy metal exposure, which could be attributed to the high amounts of heavy metals in aquatic foods. This study not only provided basic data of heavy metal exposure and potential health risks through daily oral dietary intake, but also illuminated the contribution of different kinds of food ingredients. Specifically, the study highlighted the contamination of aquatic foods with As, especially seafood such as shellfish and bivalves.

Mycorrhiza: A Potential Application for Increased Crop Productivity in a Degraded Soil

Mycorrhiza is obtained from two Greek expressions, namely: mykes (fungus) and rhiza (root). In otherwise, mycorrhiza means fungus-root as coined by Frank in 1885. So, mycorrhiza association is defined as the mutual relationship between fungus and plant root in which the fungus derive carbon from its host plant while the host plants obtain minerals from the fungus. Mycorrhizas are found in different biomes ranging from high latitudes and altitudes, deserts, lowland tropical forest to aquatic ecosystems. It is a known fact that several plants cannot thrive in their natural habitats without this mutualism, as 95-99 % of all plant species have been estimated to belong to genera that generally form mycorrhizas. It is only three families of plant that do not enter into mutual relationship with fungus. These families are as follows: Cyperaceae, Chenopodiaceae, and Brassicaceae. There are now seven types of mycorrhizas among which are arbuscular (AM) endomycorrhiza, ericoid endomycorrhizas, arbutoid endomycorrhizas, monotropoid endomycorrhizas, orchidaeous endomycorrhizas, ectomycorhizas and ectendomycorrhizas. The benefits of mycorrhiza association cannot be overemphasized as studies have shown that it improves nutrient supply of carbon, phosphorus and nitrogen to both plant and fungus that might not normally be made available to plant roots in large amount. It also enhances the performance of plant growing in soils with high amounts of heavy metals and water absorption of desert plants.

Characterization and comparison of gasification and incineration fly ashes generated from municipal solid waste in Singapore

Slagging-gasification has received increasing attention as a municipal solid waste treatment technology. Compared with incineration, slagging-gasification can produce valuable syngas and generates by-products that can be easier reusable in different applications in some cases. Among these by-products, the gasification fly ash (GFA) is the only hazardous solid residue to be landfilled. To explore its potential recycling methods and maximize its recycling efficiency, the detailed physicochemical properties of GFA are crucial. This study conducted a comprehensive characterization of six GFA samples and the results were compared with one incineration fly ash (IFA) sample and available data of IFA collected in Singapore in literature. X-ray fluorescence (XRF), and microwave acid digestion (MAD) followed by inductively coupled plasma optical emission spectroscopy (ICP-OES) and inductively coupled plasma mass spectroscopy (ICP-MS) were carried out to determine the physicochemical composition of ashes. X-ray diffraction (XRD) and thermogravimetric analysis (TGA) were applied to identify their mineralogical composition. The hazard of the material was assessed through one-stage batch leaching tests. The results showed that the GFAs and IFA were both mainly composed of calcium compounds and chloride salts. However, GFA contained higher amounts of heavy metals especially lead (Pb) and zinc (Zn) than IFA. Zn contents in tested GFA samples were in a range of 1.4–3.0%, indicating the potential to recover Zn. The Ca(OH)2 content in GFA samples was up to 24.1%, which could be recovered as a low-grade lime. Based on the characteristics of GFA, a reusing method combining civil engineering utilization and resource recovery was suggested.

Heavy Metal-Resistant Plant Growth-Promoting Citrobacter werkmanii Strain WWN1 and Enterobacter cloacae Strain JWM6 Enhance Wheat (Triticum aestivum L.) Growth by Modulating Physiological Attributes and Some Key Antioxidants Under Multi-Metal Stress.

Due to wastewater irrigation, heavy metal (HM) exposure of agricultural soils is a major limiting factor for crop productivity. Plant growth–promoting bacteria (PGPB) may lower the risk of HM toxicity and increase crop yield. In this context, we evaluated two HM-resistant PGPB strains, i.e., Citrobacter werkmanii strain WWN1 and Enterobacter cloacae strain JWM6 isolated from wastewater-irrigated agricultural soils, for their efficacy to mitigate HM (Cd, Ni, and Pb) stress in a pot experiment. Increasing concentrations (0, 50, 100, and 200 ppm) of each HM were used to challenge wheat plants. Heavy metal stress negatively affected wheat growth, biomass, and physiology. The plants under elevated HM concentration accumulated significantly higher amounts of heavy metals (HMs) in shoots and roots, resulting in increased oxidative stress, which was evident from increased malondialdehyde (MDA) content in roots and shoots. Moreover, alterations in antioxidants like superoxide dismutase (SOD), peroxidase (POD), ascorbate peroxidase (APX), and catalase (CAT) were observed in plants under HM stress. The severity of damage was more pronounced with rising HM concentration. However, inoculating wheat with Citrobacter werkmanii strain WWN1 and Enterobacter cloacae strain JWM6 (107 CFU ml–1) improved plant shoot length (11–42%), root length (19–125%), fresh weight (41–143%), dry weight (65–179%), and chlorophyll a (14%-24%) and chlorophyll b content (2–24%) under HM stress. Citrobacter werkmanii strain WWN1 and Enterobacter cloacae strain JWM6 either alone or in co-inoculation enhanced the antioxidant enzyme activity, which may lower oxidative stress in plants. However, seeds treated with the bacterial consortium showed an overall better outcome in altering oxidative stress and decreasing HM accumulation in wheat shoot and root tissues. Fourier transform infrared spectroscopy indicated the changes induced by HMs in functional groups on the biomass surface that display effective removal of HMs from aqueous medium using PGPB. Thus, the studied bacterial strains may have adequate fertilization and remediation potential for wheat cultivated in wastewater-irrigated soils. However, molecular investigation of mechanisms adopted by these bacteria to alleviate HM stress in wheat is required to be conducted.

The Effect of Land-Use Changes on the Amount of Heavy Metal Pollution in Urban Runoff in Tehran

Background &amp; Aims of the Study: Urban development trends and land-use changes harm the quality of urban runoff. Heavy metals are one of the most important pollutants in urban runoff. This study aimed to investigate the amount of heavy metal pollutants (Zn, Pb, Cu, As, Hg, and Cd) in different land uses in a densely populated urban area of Tehran. Materials and Methods: Six stations were selected for urban runoff sampling in five land uses. Land uses were residential, commercial, industrial, traffic, and outdoor. A station (sixth station) with mixed land use was selected, which included the runoff of all uses. The event mean concentration (EMC) model was used to estimate this study’s heavy metal pollution load. Results: The amount of all heavy metals except Arsenic in fields with industrial use was higher than other land uses (Cu=0.292 mg/l), (Pb=0.6166 mg/l), (Zn=1.36 mg/l), (Cd=0.0114 mg/l), and (Hg=0.1332 mg/l). While the amount of Arsenic metal in the station with outdoor land use (AS=0.111 mg/l) was the highest. Conclusion: The results of this study indicate that the risk of metals on long dry days without precipitation is very high. Uncertainties related to the accumulation of pollution and various human activities can be attributed to the high amount of heavy metals in the mixed land use compared to land use alone

Elemental Analysis of Bottled and Sachet Water Commercially Available in Abuja Metropolis Nigeria

Background: Rapid industrialization and indiscriminate use of chemical fertilizers and pesticides in agriculture are causing heavy and varied pollution in aquatic environment leading to deterioration of water quality and depletion of aquatic biota. Drinking water that contain high amount of heavy metals is a serious threat to the health of humans. People are exposed primarily to heavy metals through water consumption; however, few heavy metals can bioaccumulate in the body and may induce cancer and other risks. The objectives of this study are to assess the quality of packaged water marketed in Abuja metropolis and to compare the level of conformance to quality standards based on different processing technologies employed by packaged water manufacturers in the treatment of raw water. Methods: Different samples of both sachet and bottled water along with their raw water were randomly collected from different water production companies, coded and analyzed using the flame system of the atomic absorption spectrophotometer (AAS) for elemental contents and also compare results based on production processes from the different companies. Results: The results obtained showed that 13.3% of the raw water sample were contaminated with lead, 46.7% of the samples contain nickel above WHO limit, while 40% of the sample had concentration of cadmium above the WHO limit. Conclusion: The study showed that the reverse osmosis and activated carbon filtration technique are highly efficient in removing unwanted particles/ contaminants. The study further revealed that some of the finish product had substantial amount of metals which are above WHO and NAFDAC limit for drinking water.

Li-ion Batteries Waste Processing and Utilization Progress: A Review

Li ion batteries (LIBs) are widely used as energy storage for electronic devices and electric vehicles. Due to its limited lifetime, its disposal can cause a serious environmental problem. Heavy metals are highly toxic and require serious handling. Moreover, the some of the heave metals are considered valuable to be directly discarded. In this review, LIBs waste processing techniques were discussed. The cathode material which contain high amount of heavy metals can be processed using metallurgical approach, such as: pyro-metallurgy, hydro-metallurgy and bio-metallurgy which have their own advances and disadvantages. The recovery of heavy metals can be performed by bottom-up process such as chemical precipitation, hydrothermal, and sol-gel process. In the end, the recovered valuable metals can be used as precursor to Li-ion batteries materials, thus reducing the exploitation of metals through mining process and reducing hazardous waste.

Competitive adsorption of heavy metals onto modified biochars: Comparison of biochar properties and modification methods

Various biochars (BCs) have been developed to remove heavy metals contained in road runoff; however, there is insufficient information regarding the competitive adsorption efficiency of modified BC with regard to heavy metals due to a lack of comparative evaluation based on BC properties and modification methods. In this study, three different types of BC (RBC: rice husk, WBC: wood chip, MBC: mixture) were modified following five different methods: acidic, alkaline, oxidic, and manganese oxide (MnOx) and iron oxide (FeOx) impregnation. The changes in the physicochemical and morphological properties of the modified BC were investigated, and the adsorption characteristics of three heavy metals (Cd, Pb, and Zn) under single and mixed conditions were compared and evaluated. The improvements in the BC properties varied for different BC types and modification methods; in particular, alkaline and manganese modification caused substantial the changes in the surface area and functional groups (such as aromatic ring, –OH, and Mn–O groups). The BC prepared by manganese oxide impregnation absorbed a high amount of heavy metals (>9.15 mg/g) even under mixed conditions through cation exchange and surface complexation. The distribution coefficient (Kd) of heavy metals was high in the order of Pb > Cd > Zn; thus, the adsorption of Pb replaced that of Zn in competitive adsorption due to the difference in their affinity to BC. Therefore, the results suggest that BC prepared by manganese oxide impregnation is suitable for removing heavy metals from road runoff, as it maintained high heavy metals adsorption regardless of the BC material, even under competitive conditions.

Copper and Lead Ions Removal by Electrocoagulation: Process Performance and Implications for Energy Consumption

Electroplating wastewater contains high amount of heavy metals that can cause serious problems to humans and the environment. Therefore, it is necessary to remove heavy metals from electroplating wastewater. The aim of this research was to examine the electrocoagulation (EC) process for removing the copper (Cu) and lead (Pb) ions from wastewater using aluminum electrodes. It also analyzes the removal efficiency and energy requirement rate of the EC method for heavy metals removal from wastewater. Regarding this matter, the operational parameters of the EC process were varied, including time (20−40 min), current density (40−80 A/m2), pH (3−11), and initial concentration of heavy metals. The concentration of heavy metals ions was analyzed using the atomic absorption spectroscopy (AAS) method. The results showed that the concentration of lead and copper ions decreased with the increase in EC time. The current density was observed as a notable parameter. High current density has an effect on increasing energy consumption. On the other hand, the performance of the electrocoagulation process decreased at low pH. The higher initial concentration of heavy metals resulted in higher removal efficiency than the lower concentration. The removal efficiency of copper and lead ions was 89.88% and 98.76%, respectively, at 40 min with electrocoagulation treatment of 80 A/m2 current density and pH 9. At this condition, the specific amounts of dissolved electrodes were 0.2201 kg/m3, and the energy consumption was 21.6 kWh/m3. The kinetic study showed that the removal of the ions follows the first-order model.

Maternal Geophagy of Calabash Chalk: Effects on Neurobehavior and Brain-Histomorphology of Mice

The aim of this study was to evaluate the behavior and the brain-histomorphology of mice due to the consumption of calabash chalk. Asian and African pregnant or breast-feeding women frequently consume calabash chalk/clay for morning sickness or as a nutritional supplement. However, scientists found high amounts of heavy metals, especially lead acetate in it. This study was conducted by twenty-four female Swiss-albino mice. They were divided into four groups: control group (gr 1:1ml distilled water) and three treated groups (gr 2, 3 & 4) with the doses of 200 mg/kg, 400 mg/kg and 600 mg/kg of calabash chalk suspension, respectively, by oral gavage. Four tests were performed to evaluate the behavioral changes along with measurement of body weight and histomorphology of cerebral cortex. The data were analyzed by SPSS-software. The study showed a significant decrease in body weight in all of the treated groups (p<0.01). Apart from the elevated plus maze test, decreased behavioral pattern was observed in a dose-dependent manner (in gr 3 & 4: p <0.001). The effect of calabash chalk on histomorphology of the cerebral cortex showed a higher cellular population, hypertrophy and vacuolations in the treated groups, in a dose-dependent manner. All the three neurobehavioral parameters showed anxiogenic effects of calabash chalk with the only exception of elevated plus maze test where it showed anxiolytic activity. Both anxiogenic and anxiolytic effects observed were highly suggestive of alteration in estrogenic activity. An elevated level of estrogen could be the key mediator of anxiolytic effects whereas anxiogenic activity might result from trace metals like arsenic and lead present in the calabash chalk.