High Metal Concentrations Research Articles

Leaching characteristics of metals from recycled concrete aggregates (RCA) and reclaimed asphalt pavements (RAP)

Recycled concrete aggregates (RCA) and reclaimed asphalt pavements (RAP) are two construction waste products that are commonly used in the road construction industry. Besides many advantages, pollutants leaching from RCA and RAP are highlighted as the most concerning environmental issue. This study investigated metals leaching characteristics from RCA and RAP due to the variations in key influential factors of pH, dissolved organic carbon (DOC), compaction and liquid to solid ratio (L/S). The leaching tests for RCA and RAP were carried out separately and additionally, the standard leaching test was conducted as the benchmark for leaching investigations. Study outcomes revealed that the combined influences of factors are variable for RCA and RAP, while influences are also variable for individual metals. L/S ratios considerably affect the release of metals from RCA under saturated conditions, facilitating high metal concentrations in the leachate. On the other hand, acidic solutions are more favourable for leaching of metals from RAP. The influence of DOC in solution was minimal on the metal leachability. Interestingly, the increased degree of compaction with a higher density of materials presented the highest negative influence on metal leachability, suggesting that the metal leachability can significantly reduce, in particular when the RCA and RAP are used for the sub-base layers of road structure with a higher degree of compaction. However, the use of these recycled materials under field conditions should be further studied as there is an increasing concern of metal leaching from RCA and RAP with respect to recreational and drinking water thresholds.

Potentially Harmful Elements (As, Sb, Cd, Pb) in Soil Polluted by Historical Smelting Operation in the Upper Silesian Area (Southern Poland)

This study aimed at determining the concentration and possibility of migration of potentially harmful elements (PHEs) in soils and mining and metallurgical waste in the Silesian-Cracow region. Our research was carried out in selected locations of Ruda Śląska, Świętochłowice, Bytom, and in the Olkusz region (Bukowno) in southern Poland. The concentrations of metals (e.g., Ag, Ba, Ca, Cd, Cu, Fe, Mg, Mn, Pb, Sr, Zn), metalloids (As, Sb), and sulphur were determined in 33 soil samples (with a depth range of 0.0–0.3 m) and 12 slag samples. These studies show an increased concentration of metals, metalloids, and sulphur, exceeding the level of regional geochemical background. The research results indicate that the degree of the chemical transformation of soils in the analysed regions of Ruda Śląska, Bytom, and Bukowno is advanced. This highlights the high concentrations of most metals, i.e., arsenic, antimony, and sulphur, in the surface layer of soils (topsoil) due to historic Zn-Pb ore mining and Zn and Fe metallurgy. The presence of both primary and secondary metal sulphides, sulphates, carbonates, oxides/hydroxides, silicates, and aluminosilicates was found in the mineral composition of soils and slags.

Lead and copper removal from sterile dumps by phytoremediation with Robinia pseudoacacia

In Romania, huge quantities of gangue material from the mining activity practiced in the past were improperly stored and led to the pollution of the environment. Thus, this work is framed to manage the sterile dump of the “Radeș” mine (Alba, Romania) through a 12-week phytoremediation process. The efficient use of Robinia pseudoacacia was studied through the implementation, at the laboratory level, of a phytoremediation experiment based on various variants prepared by mixtures of gangue material, uncontaminated soil, and dehydrated sludge. The prepared variants, all planted with R. pseudoacacia, were watered with tap water, potassium monobasic phosphate, and enzyme solution. The bioconcentration and translocation factors for lead showed values ˂ 1, which indicates a potential presence of an exclusion system for Pb or a reduced Pb bioavailability since the R. pseudoacacia accumulates high concentrations of metals absorbed on and inside the roots. For copper, both factors had values > 1 indicating the suitability of R. pseudoacacia to readily translocate copper into the epigean organs. In the investigated experimental conditions, the highest efficiency in the removal of copper (93.0%) and lead (66.4%) by plants was obtained when gangue material was not mixed with other materials and wetted with enzymatic solution.

Effectiveness of light-emitting diodes for arsenic and mercury accumulation by Ceratophyllum demersum L.: An innovative advancement in phytoremediation technology

Light Emitting Diodes (LEDs) have emerged as a tool with great potential in the field of phytoremediation, offering a novel approach to enhance the efficiency of plant-based remediation techniques. In this work investigated the influence of LEDs on the phytoremediation of arsenic (As) and mercury (Hg) by Ceratophyllum demersum L., propagated using tissue culture methods. In addition, the biochemical properties of the plants exposed to metal toxicity were examined. Phytoremediation experiments employed concentrations of As (0.01–1.0 mg/L) and Hg (0.002–0.2 mg/L), with application periods set at 1, 7, 14, and 21 days. In addition to white, red and blue LEDs, white fluorescent light was used for control purposes in the investigations. A positive correlation was observed between higher metal concentrations, extended exposure times, and increased metal accumulation in the plants. Red LED light yielded the highest level of heavy metal accumulation, while white fluorescent light resulted in the lowest accumulation level. Examination of the biochemical parameters of the plants, including photosynthetic pigment levels, protein quantities, and lipid peroxidation, revealed a pronouncedly enhanced performance in specimens subjected to red and blue LED illumination, surpassing outcomes observed in other light treatments. The findings of this study introduce innovative avenues for the effective utilization of red and blue LED lights in the realm of phytoremediation research. Thus, the interaction between LEDs, tissue culture, and the phytoremediation process could lead to synergistic effects that contribute to more effective and sustainable remediation strategies.

A Type of Metal-Tannin Nanoparticles: Featuring Oxidative Antibacterial Effects Applied in Wound Healing

The number of people who die annually due to wound infections globally is not insignificant, hence there is an urgent need to find an inexpensive and efficient antibacterial and anti-inflammatory therapy. Metal-tannin complexes combine the advantages of coordination polymers and high metal content, and their simple processing, good biocompatibility, as well as the antibacterial and anti-inflammatory properties brought about by polyphenolic substances, have attracted widespread attention. Here, we utilize the sol-gel chemistry principles of formaldehyde-assisted metal-tannin crosslinking to synthesize Metal-TA nanoparticles for wound treatment. These nanoparticles release high concentrations of metal ions in weakly alkaline environments, and under stimulation from high levels of reactive oxygen species (ROS) in the wound, undergo a Fenton-like reaction to produce •OH, thereby exerting antibacterial effects on the wound.

The drivers of benthic macroinvertebrates communities along a subtropical river system: Sediments chemistry or water quality?

AbstractImpacts of metal pollution, either on water or in sediments within aquatic systems have been a serious challenge globally. Little is known about the ecological impacts of metal pollution on benthic macroinvertebrates species in sub–tropical river systems. The aim of this study was to examine benthic macroinvertebrates community composition in relation to sediment metal concentrations and other physicochemical variables in the Mutshundudi River system. Benthic macroinvertebrates sampling and community composition analysis, sediment collection, processing, metal analysis and assessment of water variables in the river system were done across two seasons at 12 sampling sites. The river was categorized into three segments: upstream, midstream and downstream. The results from geo‐accumulation (Igeo) values showed that sediments were loaded with Na, Zn, and B in all river segments. In comparison with South African water quality guidelines for aquatic ecosystems, water quality ranged from good at upstream sites because of low anthropogenic activities to very poor in downstream sites because of high anthropogenic activities. Sediments from the Mutshundudi River showed significant differences on high concentrations of metals (i.e., Mg, K, Na, and Cu) and seasonal variations. Both water quality and sediment chemistry were considered the driving factors of benthic macroinvertebrates, since species densities and composition reduced with a decline in water and sediment quality during both cool–dry and hot–wet seasons. Continuous build‐up of the metal contaminants, such as Mg, K, Na, and Cu in river sediments may pose adverse impacts on macroinvertebrate community structure.

Bioremoval and Resistance of Some Heavy Metals by Bacterial Isolates from the Sediments of the Diyala River

Background:Heavy metals are pollutants that do not decompose, but enter the food chain, and thus form toxic compounds that have a harmful effect on biological functions. There are an unlimited number of organisms in various environments, including bacteria, that are able to degrade and reduce the high levels of many pollutants, most of which have not been as important to researchers as they are interested in pathological microorganisms. Objective: This research sheds light on a number of bacterial isolates that were isolated and identified, one of which showed its high ability to grow in culture environments with high concentrations of heavy metals. Materials and Methods: Twelve sediment samples were collected from the Diyala River within the boundaries of the study area, which included four main sites. Fifteen bacterial isolates capable of resisting heavy metals were recognized at a concentration of (50 mg / L), and then five isolates were selected as the best isolates to grow and resistance of cobalt between (400-750 mg/L), chromium between (1600-2600 mg/L), nickel between (1200-1600 mg/L) and lead between (1200 - 2200 mg/liter). One of these isolates, (iso 4) showed a high ability to remove heavy metals (chromium, cobalt, nickel, and lead) after the test, with concentrations of (25, 50, and 100 mg/L), and the removal rate for 5 days of chromium was (36, 55, 68, 73 and 77%) respectively, and the removal rate of cobalt was (22, 34, 44, 54 and 59%) and the removal rate of nickel was (23, 40, 56, 68 and 80%) and the removal rate for lead is (58, 68, 74, 80 and 86%). The same isolate also showed high efficiency in removing lead due to the ability to resist high concentrations with a 100% percentage of lead removal at a concentration of 25 mg/L from the first day until the fifth day. The biochemical diagnosis of the selected bacterial isolates was adopted and the diagnosis was made using the VITEK-2 system for isolate No. 4, as the results showed that it belongs to the genus Klebsiella pneumonia. Conclusions: These environmental isolates can be applied in many bioremediations techniques to remove many toxic compounds cheaply and safely.

Heavy metals in soil, finger millet and weeds due to nutrient management practices under a 43-year-old long term fertilizer experiment

Chemical fertilizers contain traces of heavy metals and long-term use of fertilizers in agriculture could lead to the accumulation of heavy metals in the soil. Specific amounts of fertilizers and manure have been consistently applied for the past 43 years. Soil and plant samples were collected and quantified for heavy metals. The results revealed that the application of FYM and inorganic fertilizers led to a higher concentration of heavy metals in surface soil and decreased with soil depth. The application of 100% RDF resulted in higher concentrations of metals in samples of finger millet and all the heavy metals were below toxic limits. The PLI of heavy metals was found to have a value <10, indicating that soils are less polluted. Cd and Pb had BCF values of <1 for grain and straw, which indicates a lower concentration of metals in soil than those taken up by plants, while >1 for As and Cr indicates a higher uptake in grain and straw than in soil.

Association of Acidotolerant Cyanobacteria to Microbial Mats below pH 1 in Acidic Mineral Precipitates in Río Tinto River in Spain.

This report describes acidic microbial mats containing cyanobacteria that are strongly associated to precipitated minerals in the source area of Río Tinto. Río Tinto (Huelva, Southwestern Spain) is an extreme acidic environment where iron and sulfur cycles play a fundamental role in sustaining the extremely low pH and the high concentration of heavy metals, while maintaining a high level of microbial diversity. These multi-layered mineral deposits are stable all year round and are characterized by a succession of thick greenish-blue and brownish layers mainly composed of natrojarosite. The temperature and absorbance above and below the mineral precipitates were followed and stable conditions were detected inside the mineral precipitates. Different methodologies, scanning and transmission electron microscopy, immunological detection, fluorescence in situ hybridization, and metagenomic analysis were used to describe the biodiversity existing in these microbial mats, demonstrating, for the first time, the existence of acid-tolerant cyanobacteria in a hyperacidic environment of below pH 1. Up to 0.46% of the classified sequences belong to cyanobacterial microorganisms, and 1.47% of the aligned DNA reads belong to the Cyanobacteria clade.

Prediction of Total Petroleum Hydrocarbons and Heavy Metals in Acid Tars Using Machine Learning

Hazardous petroleum wastes are an inevitable source of environmental pollution. Leachates from these wastes could contaminate soil and potable water sources and affect human health. The management of acid tars, as a byproduct of refining and petrochemical processes, represented one of the major hazardous waste problems in Romania. Acid tars are hazardous and toxic waste and have the potential to cause pollution and environmental damage. The need for the identification, study, characterization, and subsequently either the treatment, valorization, or elimination of acid tars is determined by the fact that they also have high concentrations of hydrocarbons and heavy metals, toxic for the storage site and its neighboring residential area. When soil contamination with acid tars occurs, sustainable remediation techniques are needed to restore soil quality to a healthy production state. Therefore, it is necessary to ensure a rapid but robust characterization of the degree of contamination with hydrocarbons and heavy metals in acid tars so that appropriate techniques can then be used for treatment/remediation. The first stage in treating these acid tars is to determine its properties. This article presents a software program that uses machine learning to estimate selected properties of acid tars (pH, Total Petroleum Hydrocarbons—TPH, and heavy metals). The program uses the Automatic Machine Learning technique to determine the Machine Learning algorithm that has the lowest estimation error for the given dataset, with respect to the Mean Average Error and Root Mean Squared Error. The chosen algorithm is used further for properties estimation, using the R2 correlation coefficient as a performance criterion. The dataset used for training has 82 experimental points with continuous, unique values containing the coordinates and depth of acid tar samples and their properties. Based on an exhaustive search performed by the authors, a similar study that considers machine learning applications was not found in the literature. Further research is required because the method presented therein can be improved because it is dataset dependent, as is the case with every ML problem.

Ex-situ phytoextraction using Pteris vittata as a sustainable way to protect soil resource

Chemical industrial sites are potential land resources for urban construction, but the high concentration of heavy metals in soil restricts their timely redevelopment. Remediation treatment must be performed before the reutilization of these sites. Aiming to investigate the potential of Pteris vittata to remove arsenic (As) from an As-contaminated chemical industrial site, a 16-month ex-situ field experiment was conducted to monitor the dynamics of growth and As uptake of P. vittata. The shoot (pinnae and petiole) biomass increased linearly with the extension of time, and reached 1342 g m−2 at the time of ∼16 months after transplantation. The shoot As concentration in pinnae showed a “large increase followed by small decrease” tendency and reached its highest value of 2550 mg kg−1 at the time of ∼10 months after transplantation. Compared with the control that removed 5.1 kg As ha −1, the addition of potassium dihydrogen phosphate at the dose of 600 mg (P2O5) kg−1 or ammonium dihydrogen phosphate at the dose of 300 mg (P2O5) kg−1 increased the As removal by P. vittata to ∼13.0 kg ha−1. The total cost of ex-situ phytoremediation was 41.6 US$ t−1, being ∼67% lower than that of common site remediation technologies such as soil washing. Ex-situ phytoremediation is suggested to enable a timely re-development of land resource and a sustainable protection of soil resource.

Isolation and Characterization of Heavy Metal-Tolerant Bacterial Isolates from Industrial Effluents in Uttar Pradesh, India

Industrial activities over the past century have significantly increased human exposure to pollutants such as heavy metals. Industrial emissions of heavy metals, which are carcinogenic, mutagenic and toxic, contaminate natural water supplies and the agricultural environment. Due to the high concentration of heavy metals in industrial effluents, the bacteria present there naturally develop resistance to heavy metals. The aim of this study is to isolate and characterize bacteria resistant to heavy metal, lead (Pb), copper (Cu), chromium (Cr), cadmium (Cd), and nickel (Ni) from sites contaminated by industrial effluents in Uttar Pradesh, India. A total of 58 bacterial isolates were isolated from 9 samples according to their various morphological parameters and 32 isolates were found positive for all heavy metals, which revealed that samples contained metal-resistant bacterial diversity. Two isolates were identified up to species level based on their physiological, biochemical and molecular characterization as Comamonas testosteroni (S4C1) and Bacillus cereus (S5C3). Both isolates are highly resistant to lead (Pb), copper (Cu), chromium (Cr), cadmium (Cd), and nickel (Ni) and they show different MICs against the above heavy metals at different levels. A growth experiment showed that the presence of heavy metals concentration had no discernible impact on the growth rate among the isolates. Gel analysis showed interesting patterns of protein expression were observed in the presence of various heavy metals. MALDI-TOF analysis found that specific proteins (S layer protein, F0F1ATP synthase subunit b, Flagellin, 50S ribosomal protein L4, Molecular chaperone) were overexpressed in the presence of heavy metals. As a result, identifying the heavy metal resistance bacteria and their proteins study could be useful as a preliminary investigation for the development of prospective bioremediation agents of potentially hazardous waste treatment technology.

Exposure to hull cleaning wastewater induces mortality through oxidative stress and cholinergic disturbance in the marine polychaete Perinereis aibuhitensis

While wastewater and paint particles discharged from the in-water cleaning process of ship hulls are consistently released into benthic ecosystems, their hazardous effects on non-target animals remain largely unclear. In this study, we provide evidence on acute harmful effects of hull cleaning wastewater in marine polychaete Perinereis aibuhitensis by analyzing physiological and biochemical parameters such as survival, burrowing activity, and oxidative status. Raw wastewater samples were collected during ship hull cleaning processes in the field. Two wastewater samples for the exposure experiment were prepared in the laboratory: 1) mechanically filtered in the in-water cleaning system (MF) and 2) additionally filtered with a 0.45 μm filter in the laboratory (LF). These wastewater samples contained high concentrations of metals (zinc and copper) and metal–based booster biocides (copper pyrithione and zinc pyrithione) compared to those analyzed in seawater. Polycheates were exposed to different concentrations of the two wastewater samples for 96 h. Higher mortality was observed in response to MF compared to LF–exposed polychaetes. Both wastewater samples dose-dependently decreased burrowing activity and AChE activity. Drastic oxidative stress was observed in response to the two wastewater samples. MDA levels were significantly increased by MF and LF samples. Significant GSH depletion was observed with MF exposure, while increased and decreased GSH contents were observed in LF-exposed polychaetes. Enzymatic activities of antioxidant components, catalase, superoxide dismutase, and glutathione S-transferase were significantly modulated by both wastewater samples. These results indicate that even filtered hull cleaning wastewater can have deleterious effects on the health status of polychaetes.

Mobility and environmental impact of cadmium (Cd) during weathering of carbonaceous black shales in western Hunan, China

Carbonaceous black shale generally contains high concentration of Cd, with weathering leading to Cd release to environment. In this study, the mobility of Cd during weathering was quantified using geochemical assessment on black shale from western Hunan, China. Results suggested that Cd was heterogeneously distributed in shale profiles with concentrations ranging from 0.16 to 109.9 (mg/kg). Cd distribution was heterogeneous resulting from the parent shale inheritance and the mobility of Cd during weathering. Black shales weathered to a moderate degree with Cd mobility characterized by both enrichment in and release from weathered shales. Cd enrichment in weathered shales resulted from the re-enrichment of Cd in secondary minerals formed during the initial stage of carbonate (and phosphorite) dissolution, and the secondary stage of sulfide oxidation. The release of Cd was caused by decomposition of the secondary Cd-bearing minerals. Cadmium was extensively released during pedogenesis, and Cd release mass flux was estimated to range from 1.26 to 9.50 (g/m2) with a mean of 6.60 g/m2. Thus, black shale weathering may lead to the releasing of large amount of Cd resulting in Cd contamination to local environments.

Selective recovery of palladium from wastewater by modified PVC waste pipe

Green, efficient, and cost effective methods of recycling palladium (Pd) from wastewater have attracted increasing attention. In the present study, polyvinyl chloride (PVC) was utilized as a backbone for N-(3-aminopropyl)-imidazole to graft onto and yield an adsorbent suited for selective Pd recovery from wastewater by chlorine coordination. Batch experiments showed that the self-synthesized adsorbent had a Pd(II) adsorption rate of >99% at pH 1.0–3.0 and >93% in 4 min. The selectivity of the adsorbent in a complex mixed system containing high concentrations of typical base metals (CCu(II):CZn(II):CPd(II) = 66:33:1) was investigated, and the adsorbent demonstrated much higher selectivity for Pd (97.59%) than for Cu (0.52%) and Zn (2.96%). The adsorbent can also be reused as the adsorption rate remained above 99% after five cycles. Furthermore, waste PVC pipes also could be used as the synthetic raw material. The adsorbent demonstrated a high adsorption rate even when synthesized from discarded PVC pipes and the adsorption rate reached over 93% in 2 h and reached 95.15% at equilibrium in 4 h. Scanning electron microscopy and energy-dispersive spectrometry, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy were used to analyze the adsorption mechanism, which was attributed to electrostatic interaction and intermolecular interaction. The self-synthesized adsorbent is potentially applicable to the green recovery of Pd from wastewater owing to its high adsorption rate and selectivity.

Toxicological profile and potential health concerns through metals and trace elements exposure in brick kiln workers from Lahore, Pakistan.

This study examined levels of lead (Pb), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), and arsenic (As) in blood, hair, and nails of 18 brick kiln workers from three brick kiln units located around a metropolitan city, Lahore, Pakistan. All the trace elements except Hg and As were detected in the studied matrices of Brick kiln workers. In general, brick kiln workers reflect the highest concentration of Pb, followed by Cd, Cr, and Cu. Of the pollutants analyzed, Pb has the highest mean (min-max) concentrations at 0.35 (0.09-0.65) in blood(μg/mL), 0.34 (0.14-0.71) in hairs(μg/g), and 0.44 (0.32-0.59) in nails(μg/g) of brick kiln workers. Following Pb, the trend was Cd 0.17 (0.10-0.24), Cu 0.11(0.03-0.27), and Cr 0.07 (0.04-0.08) in blood(μg/mL), followed by Cr 0.11(0.05-0.20), Cd 0.09 (0.03-0.13), and Cu 0.08 (0.04-0.16) in hairs(μg/g) and Cu 0.16 (0.05-0.36), Cd 0.13 (0.11-0.17), and Cr 0.10 (0.05-0.14) in nails(μg/g) respectively. Relatively higher concentrations of metals and other trace elements in blood depicts recent dietary exposure. The difference of trace elements except Pb was non-significant (P > 0.05) among studied matrices of workers as well as between Zigzag and traditional exhaust-based brick kilns. The concentrations of Pb, Cd and Cr in blood of brick kilns workers are higher than the values reported to cause health problems in human populations. It is concluded that chronic exposure to metals and other trace elements may pose some serious health risks to brick kiln workers which needs to be addressed immediately to avoid future worst-case scenarios.

Evaluation of Metal Partitioning across Humboldt Penguin (Spheniscus humboldti) Egg Components.

Humboldt Penguin (Spheniscus humboldti) population declines are attributable to several multifaceted anthropogenic impacts. At present, the exposure of Humboldt Penguins to high concentrations of heavy metals in the marine environment is a preeminent concern, due to mining along the Peruvian coast near key rookery sites. Metal and selenium concentrations were determined in eggs collected from September 2020 to April 2021 from a managed-care penguin population at the Brookfield Zoo to establish reference values for health indices conducted on wild populations. Concentrations of 16 elements, with emphasis on those found in mine efflux-arsenic, cadmium, copper, lead, mercury, selenium, and zinc-were assessed via inductively coupled plasma mass spectrometry in yolk, albumen, and eggshell. Data analyses indicate a clear delineation between egg constituents, with lipid-rich yolk displaying notably higher concentrations (μg/g) of arsenic (0.20 ± 0.064), chromium (0.086 ± 0.03), cobalt (0.01 ± 0.003), iron (238.65 ± 54.72), lead (0.32 ± 0.97), manganese (2.71 ± 0.66), molybdenum (0.57 ± 0.14), tin (3.29 ± 0.99), and zinc (64.03 ± 13.01) than other components (albumen and eggshell). These data confirm that heavy metals are partitioned differently across Humboldt Penguin egg components, which provides insight into the potential connection between embryonic nutrient source contamination and subsequent chick viability.

Potensi Tanaman Sangitan (Sambucus javanica) sebagai Fitoremediator Tanah Tercemar Logam Berat Zn dari Air Limbah Industri Pelapisan Logam

Phytoremediation is an alternative biological treatment that can be used to reduce soil or water pollutants. Phytoremediation has the advantage of environmentally friendly waste products and a lower budget compared to physical and chemical processes. In addition, phytoremediation has the weakness of long contaminant absorption times, and quite a few plants that are used as phytoremediation agents die because they are unable to survive the high concentrations of heavy metals contained in polluted media. This study aims to determine the ability of the S. javanica (S. javanica) plant as a phytoremediator for soil contaminated with the heavy metal Zn from industrial wastewater. Phytoremediation lasted for 10 days by contacting artificial Zn wastewater with a concentration of 5 mg/L and as much as 50 ml/day on the test plants. The planting medium used was 100% soil (A1) and 50% homogenized soil with 50% manure (A2). Tests were carried out on each part of the plant and growing medium with contact times of 0, 5, and 10 days of phytoremediation. The plant used as a phytoremediator is Sangitan (S. javanica). The optimum contact time in this study occurred on the 10th day of phytoremediation, and the addition of a 50% dose of organic matter in manure had an effect on the concentration of the heavy metal Zn. The accumulation of heavy metal Zn in plant leaves was greater than in roots, with an average BCF of 0.694 for leaves and 0.308 for roots. While the TF value > 1 represents that the Sangitan plant (S. javanica) has the potential to be a phytoremediator and has a high ability to translocate the heavy metal Zn.

Metals Accumulation of Tropical Shrub Melastoma malabathricum L. (Melastomataceae) Populations and Their Relation To Soil Edaphic Factor

Melastoma malabathricum L. (Melastomataceae) is a widely distributed tropical shrub that grows in Southeast Asia. Recent research found that M. malabathricum has a bioremediatory potential that can accumulate high concentrations of toxic metals such as Al, Pb, As, and Cr. Thus, this study aimed to investigate the metal hyperaccumulation in M. malabathricum from various populations and their relation to soil edaphic factors. We collected mature leaves and soils of M. malabathricum from 15 different populations in Negeri Sembilan, Selangor, and Pahang in Peninsular Malaysia. These 15 populations consist of lowland forests, dump sites, riparian, oil palm and rubber plantations, paddy fields, and mining sites. We found that M. malabathricum accumulated high concentrations of Al (3.45±1.58 to 8.697±1.61 mg g-1) followed by Fe (1.02±0.02 to 1.07±0.04 mg g-1), Pb (0.013±0.001 to 0.016±0.001 mg g-1), As (0.008±0.005 to 0.23±0.004 mg g-1), and Cr (0.005±0.0003 to 0.02±0.01 mg g-1). The highest concentration of soil Al was 85.95±5.00 mg g-1, Fe with 69.960±7.47mg g-1, Pb with 0.192±0.03 mg g-1, As with 0.156±0.06 mg g-1 and Cr with 0.133±0.03 mg g-1. We found no significant association between high foliar metal concentrations of the metals (Al, Pb, As & Cr) with the soil chemical properties but some soil metal elements were intercorrelated with foliar metal concentrations. Understanding the potential of M. malabathricum in accumulating high levels of metal elements, provides useful information for phytoremediation works. Further research is required to investigate the mechanism uptake and tolerance of heavy metals in M. malabathricum.

Arsenic contamination of groundwater: Review on arsenic contamination of Assam

Groundwater contamination is a global problem. Although groundwater is considered as safe, high concentrations of heavy metals in groundwater like arsenic (As) can pose potential human health concerns and hazards. Arsenic is a natural chemical element of the earth’s crust and is commonly distributed all over the environment. High concentrations of arsenic (As) in drinking water have been found in several parts of the world. World Health Organization’s provisional guideline value for arsenic in drinking water - 0.01 mg/l (10 μg/l). In Assam, many districts have been reported to be most affected by arsenic contamination of groundwater which is above the permissible level. People in Assam have directly or indirectly consumed the groundwater. This paper emphasizes the overview of the present scenario of intensity of arsenic contamination in groundwater in different districts of Assam. The paper also critically reviews the sources of arsenic contamination and arsenic led human effects.