High Concentrations Of Cd Research Articles

Heavy Metals in Surface Waters in A State of The Brazilian Amazon: An Integrative Review

Objective: The aim was to carry out a systematic literature review on studies and research into heavy metals (traces) in rivers in the Amazon region of Pará. Theoretical Framework: To have a chronological understanding of the situation of possible contamination by trace metals, affecting the quality of water in the Amazon, impacting ecosystems and public health. Industrial, agricultural and urban development has had a negative impact on rivers in Pará, contributing to the degradation of water resources. Method: This is a review, with a descriptive, qualitative and quantitative approach, using literature searches (descriptors) of research carried out in the state of Pará, published between 2005 and 2023. Articles with solid evidence were considered, in accordance with the parameters recommended by resolutions 274/2000 and 357/2005 and ordinance 888/2021 of the National Environment Council - CONAMA, expressing the results through descriptive statistics. Results and Discussion: It was possible to demonstrate the main environmental impacts of pollutant and contaminant sources in rivers in the Amazon region of Pará, such as high concentrations of Pb, Cu, As, Cd, Cr and Hg, especially Pb and Hg, which were present in 60% of the studies carried out in different aquatic environments over the last 20 years in the state of Pará. Research Implications: It helps to visualize the little research carried out in the Pará Amazon, as well as providing a better understanding of land use in the region, correlating it with the contamination of surface water by heavy metals. Originality/Value: It is of socio-environmental and scientific importance, as it provides a better understanding of the level of contamination and frequency of heavy metals in the surface waters of the state of Pará.

The analytical assessment of metal contamination in industrial soils of Saudi Arabia using the inductively coupled plasma technology

Abstract In response to significant demand for evaluating the presence of heavy elements in diverse industrial areas of Saudi Arabia, the study sought to analyze the concentration ratios of 16 elements across 11 different artificial soil types in the industrial zones situated in Riyadh, Sudair, and Al-Ahsa. To achieve this objective, the research utilized the wet digestion technique and employed an ICPE-9000 spectrophotometer for quantifying element concentrations. The study had a dual focus: initially, it sought to gauge the pollution attributed to heavy metals arising from enrichment processes, and second, it evaluated the geographical accumulation of pollutants in the soil. The results revealed varying concentration levels of heavy metals across the industrial areas under study. Specifically, the soil in the Yanbu region exhibited the highest concentration values for iron, manganese, zinc, chromium, nickel, copper, cobalt, cadmium, and beryllium. In contrast, the soil in the industrial area of Riyadh had the highest concentration values for lead, mercury (Hg), molybdenum (Mo), selenium (Se), and arsenic (As). Furthermore, the highest concentration of Cd was recorded in the soil of the Jubail region. Conversely, the soil in the Al-Ahsa region displayed the lowest concentration levels for these heavy metals. The conductivity of the synthetic soil ranged from 0.47 to 6.07 μS·cm−1, accompanied by a pH range of 6.6–8.6. The results emphasized the fluctuations in element concentrations, indicating significant implications for both environmental and human health. Notably, around 20% of the gathered samples showed concentrations of heavy elements like Mo, As, Hg, and Se that surpassed the allowable limits.

Physiological and transcriptomic analyses reveal the cadmium tolerance mechanism of Miscanthus lutarioriparia.

Miscanthus lutarioriparia is a promising energy crop that is used for abandoned mine soil phytoremediation because of its high biomass yield and strong tolerance to heavy metals. However, the biological mechanism of heavy metal resistance is limited, especially for applications in the soil restoration of mining areas. Here, through the investigation of soil cadmium(Cd) in different mining areas and soil potted under Cd stress, the adsorption capacity of Miscanthus lutarioriparia was analyzed. The physiological and transcriptional effects of Cd stress on M. lutarioriparia leaves and roots under hydroponic conditions were analyzed. The results showed that M. lutarioriparia could reduce the Cd content in mining soil by 29.82%. Moreover, different Cd varieties have different Cd adsorption capacities in soils with higher Cd concentration. The highest cadmium concentrations in the aboveground and belowground parts of the plants were 185.65 mg/kg and 186.8 mg/kg, respectively. The total chlorophyll content, superoxide dismutase and catalase activities all showed a trend of increasing first and then decreasing. In total, 24,372 differentially expressed genes were obtained, including 7735 unique to leaves, 7725 unique to roots, and 8912 unique to leaves and roots, which showed differences in gene expression between leaves and roots. These genes were predominantly involved in plant hormone signal transduction, glutathione metabolism, flavonoid biosynthesis, ABC transporters, photosynthesis and the metal ion transport pathway. In addition, the number of upregulated genes was greater than the number of downregulated genes at different stress intervals, which indicated that M. lutarioriparia adapted to Cd stress mainly through positive regulation. These results lay a solid foundation for breeding excellent Cd resistant M. lutarioriparia and other plants. The results also have an important theoretical significance for further understanding the detoxification mechanism of Cd stress and the remediation of heavy metal pollution in mining soil.

Investigation of heavy metals uptake in root-shoot of native plant species adjoining wastewater channels.

Metal pollution in water, soil, and vegetation is an emerging environmental issue. Therefore, this study investigated the abundance of heavy metals (HMs) within roots and shoots of native plant species i.e., Bromus pectinatus, Cynodon dactylon, Poa annua, Euphorbia heliscopa, Anagallis arvensis, and Stellaria media grown in the adjoining area of municipal wastewater channels of a Pakistani city of Abbottabad. HMs concentrations (mg L-1) in municipal wastewater were: chromium (Cr) (0.55) > nickel (Ni) (0.09) > lead (Pb) (0.07) > cadmium (Cd) (0.03). Accumulation of HMs in both roots and shoots of plant species varied as B. pectinatus > C. dactylon > P. annua > E. heliscopa > A. arvensis > S. media. Irrespective of the plant species, roots exhibited higher concentrations of HMs than shoots. Higher amount of Cr (131.70 mg kg-1) was detected in the roots of B. pectinatus and the lowest amount (81 mg kg-1) in A. arvensis, Highest Cd concentration was found in the shoot of B. pectinatus and the lowest in the E. heliscopa. The highest concentration of Ni was found in the roots of S. media (37.40 mg kg-1) and the shoot of C. dactylon (15.70 mg kg-1) whereas the lowest Ni concentration was achieved in the roots of A. arvensis (12.10 mg kg-1) and the shoot of E. heliscopa (5.90 mg kg-1). The concentration of HMs in individual plant species was less than 1000 mg kg-1. Considering the higher values (> 1) of biological concentration factor (BCF), biological accumulation co-efficient (BAC), and translocation factor (TF), B. pectinatus and S. media species showed greater potential for HMs accumulation than other species. Therefore, these plants might be helpful for the remediation of HM-contaminated soil.

Genome-wide identification and evolutionary analysis of the NRAMP gene family in the AC genomes of Brassica species

BackgroundBrassica napus, a hybrid resulting from the crossing of Brassica rapa and Brassica oleracea, is one of the most important oil crops. Despite its significance, B. napus productivity faces substantial challenges due to heavy metal stress, especially in response to cadmium (Cd), which poses a significant threat among heavy metals. Natural resistance-associated macrophage proteins (NRAMPs) play pivotal roles in Cd uptake and transport within plants. However, our understanding of the role of BnNRAMPs in B. napus is limited. Thus, this study aimed to conduct genome-wide identification and bioinformatics analysis of three Brassica species: B. napus, B. rapa, and B. oleracea.ResultsA total of 37 NRAMPs were identified across the three Brassica species and classified into two distinct subfamilies based on evolutionary relationships. Conservative motif analysis revealed that motif 6 and motif 8 might significantly contribute to the differentiation between subfamily I and subfamily II within Brassica species. Evolutionary analyses and chromosome mapping revealed a reduction in the NRAMP gene family during B. napus evolutionary history, resulting in the loss of an orthologous gene derived from BoNRAMP3.2. Cis-acting element analysis suggested potential regulation of the NRAMP gene family by specific plant hormones, such as abscisic acid (ABA) and methyl jasmonate (MeJA). However, gene expression pattern analyses under hormonal or stress treatments indicated limited responsiveness of the NRAMP gene family to these treatments, warranting further experimental validation. Under Cd stress in B. napus, expression pattern analysis of the NRAMP gene family revealed a decrease in the expression levels of most BnNRAMP genes with increasing Cd concentrations. Notably, BnNRAMP5.1/5.2 exhibited a unique response pattern, being stimulated at low Cd concentrations and inhibited at high Cd concentrations, suggesting potential response mechanisms distinct from those of other NRAMP genes.ConclusionsIn summary, this study indicates complex molecular dynamics within the NRAMP gene family under Cd stress, suggesting potential applications in enhancing plant resilience, particularly against Cd. The findings also offer valuable insights for further understanding the functionality and regulatory mechanisms of the NRAMP gene family.

Exploration of the Effects of Cadmium Stress on Photosynthesis in Oenanthe javanica (Blume) DC.

Cadmium ion (Cd2+) stress is a major abiotic stressor affecting plant photosynthesis. However, the impact of sustained high-concentration Cd stress on the photosynthetic electron transport chain of aquatic plants is currently unclear. Here, prompt fluorescence (PF), delayed fluorescence (DF), and P700 signals were simultaneously measured to investigate the effect of Cd stress on photosynthesis in water dropwort [Oenanthe javanica (Blume) DC.]. We aimed to elucidate how Cd stress continuously affects the electron transport chain in this species. The PF analysis showed that with prolonged Cd stress, the FJ, FI and FP steadily decreased, accompanied by a positive shift in the K-band and L-band. Moreover, JIP-test parameters, including TRO/ABS, ABS/CSO, TRO/CSO and PIABS, were significantly reduced. The P700 signals showed that exposure to Cd stress hindered both the fast decrease and slow increase phases of the MR transient, ultimately resulting in a gradual reduction in both VPSI and VPSII-PSI. The DF analysis showed a gradual decrease in the I1 and I2 values as the duration of stress from Cd increased. The above results suggested that Cd stress affected the photosynthetic electron transport in water dropwort by influencing the amount of active PSII and PSI, primarily affecting PSII RCs in the early to mid-stages and PSI reductive activity in the later stage.

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.

Effects of Cadmium Stress on Seed Germination and Physiology and Biochemistry during Early Seedling Growth of Masson Pine (Pinus massoniana Lamb.)

Abstract This study evaluated the effects of cadmium (Cd) on seed germination and the physiological and biochemical characteristics of Pinus massoniana, which was used as the experimental material; culture dishes and germination boxes were used as testing devices. Seed germination and seedling growth in the presence of various Cd concentrations (0.4, 0.8, 1.2, 2, and 0 mg/L) were explored. The germination indexes of Pinus massoniana seeds used were germination percentage (GP), germination energy (GE), germination index (GI), vigor index (VI). and embryo length. The indexes of early growth of seedlings used were soluble sugar and soluble protein content, antioxidant enzyme activity, Cd content, and Cd enrichment. We found that Pinus massoniana presented reduced GP, GE, GI, VI, and embryo length with increasing Cd concentrations, and the VI and embryo length significantly decreased (P < .05). The physiological and biochemical indexes of Pinus massoniana seedlings were promoted at low Cd concentrations and inhibited at high Cd concentrations; each index peaked under 0.4 mg/L Cd. The Cd content in seedlings and the degree of enrichment decreased and then increased with increasing Cd concentration. Grey correlation analysis results showed that the effects of Cd stress were the strongest on embryo length in seeds (correlation degree: 0.769). Study Implications The effect of heavy metal pollution on seed germination and growth is closely related to phytoremediation of heavy metal soil. Pinus massoniana is the most widely distributed pine species in China. It is an economically important industrial timber with important ecological value. This study found that under the stress of different cadmium concentrations, heavy metal Cd stress inhibited the germination of Pinus massoniana seeds, and moderate Cd concentration promoted the physiological and biochemical of Pinus massoniana seedlings. Pinus massoniana seedlings have the ability to enrich heavy metal Cd.

Monitoring of the Fluctuation of the Pollutant Load of Leachate Rejected in Environment. Study in the Northeast of Algeria

In order to model the environmental impact of leachate produced at the engineered landfill center (ELC) of Bouguerguer, Guelma located in the north east of Algeria. A physico-chemical characterization during 2020, was carried out in order to estimate this impact. For this purpose fourteen parameters have been studied which are, In vivo: pH, conductivity, Salinity. In vitro: Organic element contents (BOD5, COD); Heavy metal contents (Fe, Zn, Pb, Cd and Cr); The contents of nutrient elements (Nitrate, Nitrite, Ammonium and Suspended matter). The results obtained show that the leachates studied, have the following characteristics: A basic pH of 8,85 , Suspended matter a fairly large load with 5397,92 mg/L. The organic load interpreted by a COD that reaches an average 1603, 75 mg O2/L and a BOD5 that reaches an average of 778,54 mg O2/L, which strongly justifies the presence of organic pollution. The mineral pollution is also present, translated by a high electrical conductivity which reaches an average value of 33,38 mS/cm, Nitrates and nitrites average 15,68 and 17,93 mg/l respectively. The leachates are also characterized by a high content of Fr, Zn, Pb, Cd and Cr with an average of (42,70 ; 10,44 ; 8,27 ; 4,37 and 5,97 mg/l) respectively. Noting that the results obtained constitute the first characterization of leachates in this landfill and thus provide a database for future research.

Migration Behaviour of the Combined Pollutants of Cadmium and 2,2′,4,4′,5,5′-Hexabrominated Diphenyl Ether (BDE-153) in Amaranthus mangostanus L. and Their Toxicity to A. mangostanus

The effects of different concentrations of cadmium and 2,2′,4,4′,5,5′-hexabrominated diphenyl ether (BDE-153) on the growth and related physiological and biochemical indexes of Amaranthus mangostanus L. (amaranth) were studied. The results showed that the presence of BDE-153 promoted the absorption of Cd by the amaranth and inhibited the migration of Cd from the roots to the shoots. At the same time, 0.1 mg/L of Cd had a synergistic effect on the migration of BDE-153, but 5 mg/L Cd inhibited the accumulation of BDE-153 in the aboveground part of the amaranth. In addition, the kinetics of the uptake of pollutants by the amaranth showed that both Cd and BDE-153 could be transported by amaranth, but Cd and BDE-153 were mainly enriched in the roots, and the presence of Cd may cause a lag in the uptake of BDE-153 in the shoots. Compared with the control group, the biomass of the amaranth affected by BDE-153 and a high concentration of Cd (5 mg/L) decreased by 30.2–49.5%, the chlorophyll content decreased by 43.0–60.3%, the Evans blue increased, and the MDA content was higher. The activities of superoxide dismutase (SOD) and catalase (CAT) also decreased with an increase in the BDE-153 concentration. This indicates that the interaction between BDE-153 and a high concentration of Cd (5 mg/L) is more toxic to amaranth than single Cd pollution. This paper provides the necessary data support for phytoremediation of heavy metal and organic compound pollution.

Cadmium Exposure Impairs Development, Detoxification Mechanisms and Gene Expression of Glyphodes pyloalis Walker (Lepidoptera: Pyralidae)

Cadmium (Cd) is the most serious heavy metal pollutant in the agricultural soil of China and can transfer and accumulate through the food chain and affect the growth, development and physiological processes of phytophagous insect. Glyphodes pyloalis Walker (G. pyloalis) is one of the most important pests of mulberry, and there are few studies on the adverse effects of heavy metals on insects, especially mulberry pests. To understand the toxicology of Cd exposure on G. pyloalis, we investigated the effects of three different concentrations of Cd (0, 3.89 and 51.69 mg/kg, labeled as control check (CK), low dose (LD) and high dose (HD)) on the development and detoxification mechanism of G. pyloalis and explored the molecular mechanism of Cd on G. pyloalis larvae using RNA-seq technology. Transcriptome analysis showed that compared with the CK, a total of 63 differentially expressed genes (DEGs) were identified in LD exposure, including 24 upregulated and 39 downregulated candidates. In CK versus HD groups, 395 upregulated DEGs and 436 downregulated DEGs were identified and the expression patterns of 12 genes related to detoxification and metabolism were verified using qPCR. These DEGs were relevant to multiple specific peroxisome and drug metabolism-cytochrome P450 pathways. Gene annotation and quantitative real-time PCR revealed that a high concentration of Cd significantly stimulated the expression of metabolic detoxification enzyme genes. The results revealed that Cd exposure changed the pupal weight, adult emergence rate and the activities of AKP, ACP and GST in G. pyloalis and induced notable adverse effects at the molecular level on detoxification and metabolism such as concentration and time differences. In addition, we silenced CYP12A2 by RNA interference. Bioassays showed that after silencing CYP12A2, the survival rate of G. pyloalis under Cd exposure was lower than that of the control group.

Oyster shell-modified lignite composite in globular shape as a low-cost adsorbent for the removal of Pb2+ and Cd2+ from AMD: Evaluation of adsorption properties and exploration of potential mechanisms

A low-cost composite adsorption material has been synthesized from fishery wastes and natural minerals to address challenges such as ecological balance destruction caused by high concentrations of Pb and Cd in acid mine drainage (AMD), unreasonable use of low-caloric lignite, and environmental pollution caused by idle accumulation of oyster shells. This new adsorbent can effectively treat AMD by improving acidity and adsorbing Pb2+ and Cd2+. In this study, oyster shell-modified lignite composite in globular shape (OSL-G) was synthesized by using pyrolyzed oyster shell and lignite, with the addition of bentonite adhesive. The adsorption properties of OSL-G on AMD were evaluated, and the potential mechanism of OSL-G repairing AMD was explored. The results showed that when the mass ratio of oyster shell to lignite was 1:1, oyster shell-modified lignite composite (OSL) was synthesized at 900 °C for 20 min. When the adhesive content was 15.50 %, the roasting temperature was 640 °C, and the roasting time was 2.35 h, OSL-G was synthesized and the adsorption effect was the best. The OSL-G could effectively treat AMD with pH 4 ∼ 5 and initial Pb2+ and Cd2+ concentrations of 10 mg/L within 600 min at a dosage of 4 g/L. The OSL-G adsorption process followed the quasi-second-order kinetic model and the Freundlich model. The maximum adsorption saturation capacities of Pb2+ and Cd2+ were 107.2821 mg/g and 8.3777 mg/g at 298.15 K, respectively. The adsorption process was a multistep controlled spontaneous endothermic process. The potential mechanism was mainly the adsorption-condensation coexistence results of electrostatic adsorption, neutralization precipitation, ion exchange, and surface complexation. The removal rates of Pb2+ and Cd2+ of the recovered OSL-G (ROSL-G) were still high, reaching 57.26 % and 50.38 % after 5 times of adsorption–desorption, respectively. The applicability of ROSL-G after adsorption–desorption for other heavy metal components in AMD proved its good application potential. This study suggested that OSL-G can be used as a promising environmentally friendly adsorbent for AMD. This study provided a broad picture of the management and reuse possibilities of fishery wastes and natural mineral resources, and addressed established, current, and potential strategic needs, particularly in terms of sustainability challenges and ecological civilization construction.

AtERF13 and AtERF6 double knockout fine-tunes growth and the transcriptome to promote cadmium tolerance in Arabidopsis

The toxic heavy metal cadmium (Cd) restricts plant growth. However, how plants fine-tune their growth to modulate Cd resistance has not been determined. Ethylene response factors (ERFs) are key regulators of Cd stress, and Arabidopsis thaliana ERF13 and ERF6 (AtERF13 and AtERF6) negatively regulate growth. We previously demonstrated that AtERF13 is a transcriptional activator that binds a Cd-responsive element. Herein, we report that Arabidopsis plants improve Cd tolerance by repressing AtERF13 and AtERF6. We found that AtERF13 and AtERF6 were strongly downregulated by Cd stress and that AtERF6 weakly bound Cd-responsive elements. Moreover, AtERF13 physically interacted with AtERF6. Importantly, AtERF13 and AtERF6 double knockout mutants, but not single mutants or overexpression lines, grew better, tolerated more Cd and had higher Cd contents than did the wild type. Comparative transcriptome analysis revealed that the double mutants regulate the defense response to cope with Cd toxicity. Accordingly, we propose that, upon Cd stress, Arabidopsis plants repress AtERF13 and AtERF6 to relieve their growth inhibition effects and adjust the transcriptome to adapt to Cd stress, leading to increased Cd tolerance. Our findings thereby provide deep mechanical insights into how dual-function transcription factors fine-tune growth and the transcriptome to promote Cd tolerance in plants.

Cadmium accumulation in soil resulting from application of biogas digestate and wood ash – Mass balance modelling

This study investigates the impact of substituting conventional NPK fertilizer with wood ash and biogas digestates at an agricultural field site in southwest Sweden. A three-year field experiment, comprising a crop rotation cycle of spring wheat, winter wheat, and oats, was conducted. The obtained results were employed to establish a dynamic mass balance model for the A horizon of the soil at the site. The Cd leaching term in the model was estimated using the Stockholm Humic model (SHM), which was recalibrated to accommodate low Cd concentrations by incorporating Cd complexation to thiol sites. The findings indicate that treatments receiving NPK fertilizer and biogas digestates experienced a net Cd loss, whereas treatments with wood ash demonstrated net Cd accumulation, attributed to its higher Cd content. Harvest yields were highest in the NPK treatment, and lower in two of the wood ash treatments, likely due to lower nitrogen additions in the latter. Cd offtake mirrored this trend, with the highest values in the NPK treatments and the lowest in the wood ash treatments, potentially also influenced by a pH difference of 0.2 units during the last year of the experiment. Geochemical modelling showed that Cd leaching is highly dependent on pH and that geochemically active soil Cd in the A horizon may have doubled between 1950 and 2002, due to elevated atmospheric deposition and fertilizer Cd during this period. Despite significant reductions in anthropogenic Cd fluxes since 2002, soil Cd has only decreased by 4%, showing the slow response of the soil pool to flux changes. Attaining a new steady-state after alterations in input fluxes will require hundreds of years. These results carry significance for determining sustainable application rates for recycled nutrient sources and underscore the crucial role of pH-dependent Cd sorption for Cd leaching.

Effects of land use/cover change on heavy metal distribution of soils in wetlands and ecological risk assessment

This study aimed to determine the impact of land use/cover changes on the heavy metal content in the Sultan Marshland and surrounding area and assess the pollution status. 54 topsoil samples (0–20 cm) were collected from the Rangeland, Farmland, Scrubland, Southern Marshland, Northern Marshland, and Dry Lake areas. The heavy metal contents of the soil samples (Cr, Pb, Fe, Zn, Cu, Co, Mn, Cd, Mo, As, and Ni) were determined using ICP-MS and ICP-OES devices. The impact of land use/cover change on soil heavy metal content was evaluated using variance analysis, while differences between groups were identified using the Duncan test. Principal Component Analysis (PCA) was conducted to identify potential sources of heavy metals. The contamination status of the soils was evaluated based on land use/cover using the Contamination Factor (Cf), Pollution Load Index (PLI), Ecological Risk Factor (Er), and Potential Ecological Risk Index (PERI).Changes in land use/cover around the Sultan Marshlands affected heavy metal distribution of the soils except for Cd. Among all land use/cover types, Fe concentration was the highest in the soils, while Cd concentration was the lowest. Soils in Southern Marshland exhibited higher average concentrations of Cr, Fe, Zn, Co, Cu, and Ni compared to other land uses/covers. Farmlands and rangelands had higher concentrations of Cd, As and Pb. Land use/cover was ranked based on the total heavy metal load in the following order in terms of average values: Southern Marshland > Scrubland > Farmland > Rangeland > Northern Marshland > Dry Lake. According to Cf, the soils in the Dry Lake were exposed to considerable levels of As contamination. Based on PLI, half of the soil sampling points in the Southern Marshland soils showed a degradation in environmental quality. Er indicated that all land uses moderately polluted with Cd. According to the average PERI, all soils under different land use/cover types were categorized as having a low ecological risk. It was believed that heavy metals originated from both natural and human activities. To ensure the sustainability of the ecosystem and to mitigate the risk of heavy metal pollution entering the food chain, it is recommended to manage farming and mining activities and land use habits.

Pollution Status of Groundwater Resource by Some Heavy Metals Using Index Approach in Some Part of Nasarawa Area, Kano State, Nigeria

Groundwater is the world's most significant natural resource providing water for different purposes, including drinking, domestic, industrial and irrigational. However, polluted groundwater may endanger human survival. This research evaluated the status of groundwater resource pollution caused by some heavy metals in some parts of the Nasarawa local government area of Kano State. 15 groundwater samples were collected from functional boreholes in the area. Heavy metals concentrations evaluated include Zn, Mn, Cr, Mg, Cd, Fe, Cu, and Pb and were compared with the World Health Organization and Nigerian Standard for Drinking Water Quality to establish their suitability for human consumption. Descriptive statistics was employed to summarize the analyzed data. Metal index was used to determine the pollution status of the groundwater. The result revealed that Zn, Fe, Cu, and Mn with the mean value of (0.090, 0.160, 0.191 and 0.11) were found within the stipulated limit set by WHO (3.0, 0.3, 2.0 and 0.5) and NSDWQ (3.0, 0.5-50, 1.0 and 0.2), while Pb, Cd, Cr, and Mg (0.105, 0.127, 0.206 and 0.82) exceeded the permissible limits recommended by WHO (0.01, 0.003, 0.05 and 0.5). A high concentration of Pb, Cd, Cr, and Mg may be attributed to anthropogenic influences possibly deriving from improper municipal and Bampai industrial waste disposal. The values of the metal index (MI) revealed that the water is seriously affected by Pb, Cd and Cr, which can pose serious health damage to consumers. It is recommended that constant and continuous monitoring of Pb, Cd and Cr in groundwater be made in the study area due to its proximity to Bampai and Sharadda industrial sites.

Alleviating Cd Stress in Sunflower (Helianthus annuus) through the Sodium Silicate Application

Sunflower has substantial potential for the remediation of heavy metals in soil, but its efficiency in Cd-contaminated soil is limited, with high concentrations of Cd causing stress in plants. Exogenous Si enhances plant tolerance to heavy metals, but the mechanism for enhancing the tolerance of oil sunflower under Cd stress is not known. In potting experiments, sunflowers were grown in soil with a Cd concentration of 11.8 mg/kg soil (the maximum value in the Zhundong coal mining area of Xinjiang) and five Si treatment levels (0, 50, 250, 500, and 1500 mg/kg soil). Exogenous Si improved sunflower development, gas exchange characteristics, and antioxidant enzyme activities in sunflower compared with the Cd-only control; exogenous Si application increased Cd concentrations in sunflower roots, stems, and leaves, and Cd was mainly concentrated in sunflower roots. Sunflower biomass increased by 13.83–114.18%, and gas exchange parameters increased by 16.95–36.03%, 30.06–66.82%, and 9.77–14.71%, respectively, as compared to the control. With the increase in sodium silicate concentrations, sunflower antioxidant enzyme activities increased by 8.81–150.28%, 91.35–351.55%, and 35.11–54.69%, respectively, and MDA content decreased by 3.34–25.14% as compared to Si0. Moreover, exogenous Si increased Cd uptake and minimized Cd stress in sunflowers at the seedling and blooming stages, and it potentially facilitated the phytoremediation of Cd-contaminated soils through enriched plants such as sunflower, as well as contributing to the achievement of sustainable development of the soil environment.

Effects of agro-climatic zones, soil orders, and irrigation types on the exchangeable cadmium in paddy soils

Even though the concentrations of the total cadmium (Cd) in paddy soils from different countries have been reported, the exchangeable-Cd (Ex-Cd) concentrations in these soils are unknown despite its importance in agriculture. This study was conducted with a total of 5460 soil samples collected in Sri Lanka, representing six agro-climatic zones, six soil orders, and three irrigation types. The Ex-Cd concentrations in soil samples were extracted using 0.01 ​M CaCl2 and analyzed using an inductively coupled plasma-mass spectrophotometry. The Ex-Cd concentrations were <0.31–163 ​μg ​kg−1, with mean and median concentrations being 14.1 and 8.98 ​μg ​kg−1, respectively, which was affected by both agro-climatic and soil conditions. Samples from the Wet zone, particularly the Wet zone Low country, had higher Ex-Cd (24.1 ​μg ​kg−1) than those from the Dry zone Low country (11.6 ​μg ​kg−1). Among the soil orders, Histosols (21.3 ​μg ​kg−1) and Inceptisols (19.5 ​μg ​kg−1) had the highest Cd concentration while Vertisols had the lowest (6.3 ​ ​kg−1). The irrigation types only affected Ex-Cd concentrations in Dry zone Low country, but not in other agro-climatic zones. Overall, it is important to consider agro-climatic zones, soil orders, and irrigation types when implementing agronomic strategies to mitigate the risk associated with Cd accumulation in paddy fields.

ENVIRONMENTAL ASSESSMENT OF POLLUTION IN AN INDUSTRIAL ENVIRONMENT USING HEAVY METAL POLLUTION INDICES AND STABLE ISOTOPES, CASE STUDY OF THE INDUSTRIAL ZONE OF SKIKDA, NORTH-EAST ALGERIA

An environmental assessment study was conducted in the industrial area of Skikda in the Northeast of Algeria which involved physicochemical parameters, heavy metal concentrations, and stable isotopes of surface water, groundwater, and soil. The results revealed high concentrations of Cd, Ni, Fe, Cu, As, Cr, Pb, Co, and Mn in groundwater. The southern part exhibited the lowest heavy metal concentrations, while the industrial zone in the North contained the highest levels. Therefore, the industrial area showed significant pollution in groundwater by Cr, Pb, and As with respectively 0.5, 0.69, and 0.44 mg/l, surpassing the respective WHO(World Health Organization) standards of 0.05, 0.01, and 0.01 mg/l. Spatial analysis showed that the industrial area presents higher concentrations of As, Cr, Cd, Pb, Cu, Zn, Ni, and Fe which demonstrated similar trends in spatial distribution, their concentrations increasing within the industrial zone. However, the western part had no significant pollution sources except for a public landfill and SONATRACH industrial complex, high concentrations of Co and Mn in the south and the west parts were observed. Mean concentration in soils indicated that Cd is ranged between35.32 to 95.12 ppm, for Fe between 145.1 and 702 ppm, As varies between 1.03 and 81.85 ppm, and Zn between 50 and 520.32 ppm and considered as dominant metals. However, Mn, Co and Cr were lower respectively with 1.97, 12.11 and 7.25 ppm. Cd and As were most influenced by the polluting companies, while Cr was mainly influenced by natural factors, such as pH and soil type. Based on the contamination degree index, the soil pollution levels of Cd, Pb, and As were classified as extremely contaminated. The statistical analysis indicated substantial anthropogenic contributions to groundwater contamination concentrated in the industrial area. The groundwater exhibits a range of δ18O and δ2H values, varying from 2.45 to -5.33‰ and 19.82 to -1.67‰ vs. the V-SMOW (Vienna-Standard Mean Ocean Water) standard, respectively. The mean isotopic composition is -2.50‰ for δ18O, -19.32‰ for δ2H, with a mean deuterium excess of 6.45. These values align with the Meteoric Water Line observed in the western Mediterranean region. It indicates a hydrological connection between recharge and groundwater which suggests a significant interaction between groundwater and surface water. Due to their proximity to the river and the shallow aquifer, the downstream area is more vulnerable to surface pollution. Furthermore, the young groundwater in the downstream can be attributed to the rapid recharge and replenishment of the aquifer caused by rainfall and quick infiltration and sustained by the shallow aquifer depth and sandy soil. Consequently, the rainwater and industrial wastes lead to faster pollutant infiltration. Anthropogenic sources, including industrial effluents from smelting, refining, manufacturing, steel and textile industries, electroplating, nickel-cadmium battery production, welding, PVC product and paint pigment manufacturing, were identified as major contributors to heavy metal pollution.

Concentration and Health Risk of Heavy Metals in Herbs from Electronic Waste Disposal Site in Lagos State, Nigeria

Considering that about 80 % of the world population uses herbs for the treatment of illnesses and the contamination that is prevalent at electronic waste (e-waste) disposal sites, this study evaluated the concentrations of heavy metals and health risks in the use and consumption of Rhynchospora corymbosa, Pentodon pentandrus and Cyclosorus dentatus, herbs commonly found in electronic waste disposal site in Lagos State, Nigeria using appropriate standard methods. The mean concentrations of the heavy metals in the plant were: 100.78±0.91, 0.16±0.02, 25.68±0.44, 258.94±1.62, and 8.51±0.04 mg/kg for Pb, Cd, Ni, Cu and Cr, respectively. Pentodon pentandrus had the highest Pb, Cu and Ni concentrations, Cyclosorus dentatus had the highest Cd concentration while Rhynchospora corymbosa recorded the highest concentration of Cr. The bio-accumulation factor of Cu in Pentodon pentandrus and in Rhynchospora corymbosa and of Cr in Rhynchospora corymbosa were higher than 1. The estimated daily intake of Pb and Ni in Pentodon pentandrus, Cyclosorus dentatus and Rhynchospora corymbosa exceeded the Provisional Maximum Tolerable Intake, indicating an intolerable risk to the consumers’ health. The hazard index of each of the plants indicates that the cumulative health effects of the heavy metals would cause potential health hazards to the consumers. This useful information gives an accurate indication of the levels of contamination of the plants and the potential health risk effects of the consumption of these herbs from the dumpsite.