Impacts of the steel industry on sediment pollution by heavy metals in urban water system

Prenatal placental metal accumulation and its association with child attention deficit/hyperactivity disorder and autism spectrum disorder symptom at 3 years of age: The role of psychosocial-environmental support in infancy

The placenta is recognized as a barrier to the passage of harmful substances and is an ideal biomonitoring sample for assessing cumulative prenatal exposure to metals. However, scientific knowledge is insufficient regarding the effects of cumulative prenatal exposure to metal mixtures on behavioral development in early life. This study included 2154 mother-infant pairs from the Ma'anshan Birth Cohort study. Concentrations of eleven metals in the placenta were quantified, and attention-deficit/hyperactivity disorder (ADHD) and autism spectrum disorder (ASD) symptom were assessed in 3-year-old children. Thrive factor (T-factor) scores, derived from factors such as breastfeeding, sleep, parenting style, secondhand smoke exposure, family income, and parental absence, were calculated during infancy. It was found that elevated concentrations of cadmium (Cd) (OR: 1.36, 95% CI: 1.06, 1.75), manganese (Mn) (OR: 1.34, 95% CI: 1.02, 1.77), and copper (Cu) (OR: 1.53, 95% CI: 1.05, 2.23) in the placenta were associated with increased ADHD risk in children. Additionally, arsenic (As) showed a moderate association with ADHD risk (OR: 1.34, 95% CI: 0.99, 1.83). Results from the Bayesian Kernel Machine Regression (BKMR) model indicated significant positive associations between the mixture of placental metals and ADHD symptom risk when all eleven metal concentrations were elevated. The quantile-based g-computation (Qgcomp) approach also suggested a nearly significant association between the total mixture of eleven metals/elements and ADHD symptom risk (OR: 1.27, 95% CI: 0.97, 1.65). Among the metals, Cd was the largest contributor to the positive association, followed closely by Cu, cobalt (Co), Mn, mercury (Hg), As, and chromium (Cr). Conversely, zinc (Zn) was the largest contributor to the negative association, followed by selenium (Se) and lead (Pb). Further analysis revealed that a simultaneous increase in metal concentrations (Cd, Cu, Co, Mn, Hg, As, and Cr) by one quartile was significantly associated with ADHD symptom risk (OR: 1.31, 95% CI: 1.03, 1.69). Moreover, higher T-factor scores, composed of breastfeeding, sleep, parenting style, secondhand smoke exposure, household income, and parental absence, were significantly associated with decreased ADHD and ASD symptom risk at age 3. We observed a gradual attenuation or even disappearance of the associations of placental Cu and Mn with ADHD symptom as T-factor scores increased. Our findings suggest that Cd, Cu, and Mn are key metals associated with ADHD risk in early life, and that psychosocial environmental factors in infancy are potential modifiers of these associations.

Spatial distribution, contamination levels, and risk assessment of heavy metals along the Eastern India coastline

The proposed comprehensive study was accomplished to analyze the ecological phenomenon, heavy metals occurrence, and its significance. The spatial distribution of heavy metals in the sediments such as Cadmium (Cd), Cobalt (Co), Cupper (Cu), Lead (Pb), Mercury (Hg), Nickel (Ni), Zinc (Zn), Iron (Fe), and Chromium (Cr) of the Eastern coastline of India (ECI) was evaluated across 61 sites along the 1400 km stretch of the Bay of Bengal and the Arabian Sea coastline. The heavy metal concentration was higher for Hg (0.08 μg/g) and Cd (3.44 μg/g), likely due to mining and extraction activities. Strong positive correlations (R2>0.5,p<0.01) observed between Cd∼Fe R2=0.70, Cd∼-Cr R2=0.68, Co∼Zn R2=0.79, Cu∼Ni R2=0.73 suggesting co-miming sources while negative correlations Ni∼Cr R2=-0.50, Ni∼Pb R2=-0.56, Cu∼Pb R2=-0.58 indicate the separation of these metals in sediments due to geochemical conditions and tailing disposal. The heavy metals, Co, Cu, Pb, Ni, Fe, and Cr were under the concentrations proposed by sediment quality guidelines (SQGs). It indicated there is fewer immediate effects of heavy metals, however, even at low levels metals like Hg, Cd, and Pb can cause chronic exposure effects, bioaccumulation and subclinical health impacts over time. The stations of Utkal (UC 14-UC 18) and Coromandel (CC 8-CC 11) coastline act as shipping ports and are involved in mining activities and recorded geological weathering of rocks in these areas, compared to other sampling locations along Utkal, Andhra and Coromandel coastline.

Prenatal metals and offspring cognitive development: Insights from a large-scale placental bioassay study

The developing foetus is particularly sensitive to neurotoxic metals. The placenta is considered an ideal tissue for biomonitoring prenatal cumulative metal exposure. Based on the Ma'anshan Birth Cohort study (MABC) in China, this study investigated associations of non-essential metals and essential metals in placenta, including arsenic (As), cadmium (Cd), mercury (Hg), lead (Pb), cobalt (Co), selenium (Se) and zinc (Zn), with cognitive development in children among 1586 mother-child pairs. Also, we explored potential interactions between the metals and modifying role of the sex. Children's cognitive development was tested at preschool age using the Wechsler Preschool and Primary Scale of Intelligence, Fourth Edition (WPPSI-IV). Analyses used multiple linear regression, Bayesian kernel machine regression (BKMR), the quantile g-computation (Qgcomp), interaction and marginal effects models, and restricted cubic spline in R and STATA. In this study, the geometric means [GMs (SD)] for placental metal concentrations were 8.10 (7.54) ng/g for As, 32.32 (29.20) ng/g for Cd, 11.89 (13.33) ng/g for Hg, 32.21 (28.24) ng/g for Pb, 15.05 (8.91) ng/g for Co, 508.82 (192.35) ng/g for Se, 18481.60 (14030.61) ng/g for Zn. In individual models, placental As levels were negatively associated with the Fluent Reasoning Index (FRI) in the overall sample. Cd levels were negatively associated with the full-scale intelligence quotient (FSIQ), the Verbal Comprehension Index (VCI) and the Visual Spatial Index (VSI). The four metal mixture (As, Cd, Hg and Pb) was negatively associated with FSIQ, VCI, VSI and FRI. Placental Cd and As were the largest contributors to the negative mixture association on the FSIQ. The negative associations of placental As, Cd and Hg with FSIQ in children were gradually attenuated with increasing Zn and Se. After stratifying by sex, the individual and mixture associations between elevated placental non-essential metal exposures and reduced cognitive scores were significant only in boys. Zn and Se were the major contributors to the positive mixture associations on the FSIQ. In summary, prenatal exposure to As, Cd and Hg has sex-specific adverse associations on children's cognitive development. A more accurate assessment of the necessity of prenatal supplementation of micronutrients including Zn and Se is needed.

Metal pollution reconstruction in São Paulo City (Southeast Brazil) over the twentieth century by paleolimnological approach

In this study, we evaluated the pollution history by metals over the twentieth century in an urban reservoir (Garças Reservoir, Metropolitan Region of São Paulo, Southeast Brazil) by the paleolimnological approach. The concentrations of eight metals (Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) were determined in a 210Pb-dated sediment core (~ 100 years of information). Metal's enrichment and pollution degree were assessed using the Consensus-Based Sediment Quality Guidelines (CBSQG), enrichment factor (EF), Geoaccumulation Index (Igeo), and Potential Ecological Risk Index (RI). Local background values were used to calculate metal enrichment indexes. Principal component analysis (PCA) was performed to analyze metal variability across samples. Overall heavily to extremely contamination was determined mainly after ~ 1975, particularly to Pb, Ni, and Fe, whereas moderately to heavily Cu, Zn, Mn, and Co pollution levels were detected by Igeo. Very high EF values (> 2 ≤ 24) were found, suggesting mainly anthropogenic sources for these elements. However, Pb concentrations declined considerably towards the top of the core, reflecting the prohibition of leaded gasoline since 1986. The long-term metal enrichment in the Garças Reservoir was related mainly to vehicular traffic emissions and industrial activities. Further anthropogenic stressors such as untreated sewage inputs and surface runoff contributed significantly to metal pollution, particularly from the late 1950s, reflecting the most populous region socio-economic development in Brazil.

Spatial distribution of heavy metal assessment in beach sediment due to bauxite mining in Kuantan, Pahang, Peninsular Malaysia

The effect of open-pit bauxite mining on beach sediment contamination in the urban coastal environment of Kuantan City, Malaysia, was investigated. The contents of 11 heavy metals (Pb, Cd, Al, Mn, Cu, Zn, Fe, As, Ni, Cr, and Ag) in 30 samples from Kuantan beach sediment zones (supratidal, intertidal, and subtidal) were determined using inductively coupled plasma optical emission spectrometry followed by contamination indexes, Pearson's correlation analysis, and principal component analysis (PCA). The results indicated that Cd, As, Ni, and Ag values in beach sediment zones were significantly higher compared to background values. Contamination indexes suggest that Cd, As, Ni, and Ag were highly contaminated, and moderate to extremely enriched near the Kuantan Port. However, these heavy metal concentrations are lower compared to previous studies in the region. Sediment quality guidelines highlighted the occasional presence of Cd and Ag. Based on Pearson's correlation analysis, PCA, and cluster analysis, sources of these heavy metals in beach sediments were likely from agricultural runoff, uncontrolled industrial and residential discharge, and unprotected mine waste near the Kuantan Port. Furthermore, effective management of mining practices and ongoing monitoring are essential to reduce contamination risks.

Quantification of heavy metal contamination and source in urban water sediments using a statistically determined geochemical baseline

Geochemical baselines (GBs) play a crucial role in discerning natural variability from anthropogenic impacts on elemental composition within the environment. However, their applicability in quantifying the contribution of pollution sources to heavy metal contamination in sediments remains understudied. This research aimed to assess the degree of contamination and local pollution source attribution by leveraging geochemical baselines derived from statistical techniques, specifically the relative cumulative frequency (RCF) and 2σ-iterative (2σ-I) methods. In the urban water systems of Ma'anshan City, the major iron ore centre in eastern China, we observed concentration ranges of Cr, Cu, Ni, Pb and Zn in 36 sediment samples ranging from 66.89 to 352.08 mg/kg, 22.01 to 133.37 mg/kg, 22.66 to 50.80 mg/kg, 14.66to 264.37 mg/kg and 73.30 to 2707.46 mg/kg, respectively. RCF and 2σ-I techniques yielded similar GBs with no significant differences (p > 0.05). The geo-accumulation index and contamination factor analysis showed a sediment heavy metal accumulation rank of Zn > Pb > Cr > Cu > Ni. The contribution percentage of pollution sources varied with land functional type of watershed. For industry-influenced sediments, the contribution of local sources to Cr, Cu, Pb and Zn was significant, with shares of 43%-88%. Overall, this study highlights the valuable insights provided by GBs for effective management of urban aquatic environments.

Review on the impact of heavy metals from industrial wastewater effluent and removal technologies

The incidence of water pollution in developing countries is high due to the lack of regulatory policies and laws that protect water bodies from anthropogenic activities and industrial wastewater. Industrial wastewater contains significant amounts of heavy metals that are detrimental to human health, aquatic organisms, and the ecosystem. The focus of this review was to evaluate the sources and treatment methods of wastewater, with an emphasis on technologies, advantages, disadvantages, and innovation. It was observed that conventional methods of wastewater treatment (such as flotation, coagulation/flocculation, and adsorption) had shown promising results but posed certain limitations, such as the generation of high volumes of sludge, relatively low removal rates, inefficiency in treating low metal concentrations, and sensitivity to varying pH. Recent technologies like nanotechnology, photocatalysis, and electrochemical coagulation have significant advantages over conventional methods for removing heavy metals, including higher removal rates, improved energy efficiency, and greater selectivity for specific contaminants. However, the high costs associated with these advanced methods remain a major drawback. Therefore, we recommend that future developments in wastewater treatment technology focus on reducing both costs and waste generation.

Evaluating the human health risks of heavy metal contamination in copper and steel factory effluents in Nnewi, Anambra State, Nigeria

Heavy metal (HM) contamination above permissible limits poses a risk to human health. The study evaluated the health risk (cancer and non-cancer) of exposure to copper (Cu) and steel factory wastes on water samples near the factory based on the hazard quotient (HQ) derived from the HM concentrations. Triplicate water samples were collected by purposive sampling and their concentrations of selected HMs [Pb, Zn, Cu, Mn, Mg, Fe, Cd] were analyzed by Atomic Absorption Spectrometry. The health risks were determined from the concentrations of HMs in water samples ingested orally. The range concentrations were [Fe, 0.074-0.178], [Pb, 0.011-0.013], [Cd, 0.005-0.02], and [Mn, 0.023-0.045] which were above the reference values set by World Health Organization. The contribution of the individual metal to the chronic daily intake (CDI) in the three samples are Mg>Fe>Mn>Zn>Cd>Pb>Cu. In the three different samples, the CDI for Mg was highest in the factory borehole [0.15523]. Comparing the CDI values from the three different collection points, Cu, Pb, Zn and Fe were highest from the factory effluent. Mg contributed the highest HQ [5.46307] in all the water samples, followed by Pb [3.87618] and then Cd[2.64009], which reflect their significantly high hazard indices observed. The incremental life cancer risk [ILCR] via ingestion showed that the cancer risk resulting from Cd in the different sources demands attention. The factory effluent recorded the highest mean levels of the metals analyzed, which were higher than the permissible limits. Magnesium contributed the highest non-cancer risk, while Cd had the highest cancer risk.

Phosphate-solubilizing bacteria improve the antioxidant enzyme activity of Potamogeton crispus L. and enhance the remediation effect on Cd-contaminated sediment

Phosphorus-solubilizing bacteria (PSB) assisted phytoremediation of cadmium (Cd) pollution is an effective method, but the mechanism of PSB-enhanced in-situ remediation of Cd contaminated sediment by submerged plants is still rare. In this study, PSB (Leclercia adecarboxylata L1-5) was inoculated in the rhizosphere of Potamogeton crispus L. (P. crispus) to explore the effect of PSB on phytoremediation. The results showed that the inoculation of PSB effectively improved the Cd extraction by P. crispus under different Cd pollution and the Cd content in the aboveground and underground parts of P. crispus all increased. The μ-XRF images showed that most of the Cd was enriched in the roots of P. crispus. PSB especially showed positive effects on root development and chlorophyll synthesis. The root length of P. crispus increased by 51.7 %, 80.5 % and 74.2 % under different Cd pollution, and the Ca/Cb increased by 38.9 %, 15.2 % and 8.6 %, respectively. Furthermore, PSB enhanced the tolerance of P. crispus to Cd. The contents of soluble protein, MDA and H2O2 in 5 mg·kg-1 and 7 mg·kg-1 Cd content groups were decreased and the activities of antioxidant enzymes were increased after adding PSB. The results showed that the application of PSB was beneficial to the in-situ remediation of submerged plants.