The Khuzestan Plain in southwestern Iran is a major dust source. This study presents the first province wide assessment of potentially toxic elements in 69 surface sediment samples. Mean concentrations (mg/kg) decreased in the order: Ti (2012), Mn (478), Ba (209), Ni (115), V (75), Cr (65), Zn (49), Co (25), Cu (20), Pb (20), As (6.7), Mo (3.1), Sn (1.7), Cd (0.6). Pronounced spatial variability (CV > 50%) for Ba, Mo, and As suggests localized anthropogenic sources, while As, Cd, Ni, and Mo exceed Upper Continental Crust values; Ni surpasses both TEL and PEL by factors of 7.2 and 2.7, respectively. A strongly correlated lithogenic cluster (Ti, Mn, Ni, V, Cr, Co, Sn) reflects bedrock weathering, whereas As, Ba, Mo, Pb, and Zn are decoupled from this assemblage, indicating anthropogenic inputs. Cadmium exhibits significant enrichment (EF = 11.6), pointing to dominant industrial sources, followed by As (EF = 8.8); Mo, Ni, Co, and Pb show moderate enrichment (EF = 4.6, 4.4, 2.8, and 2.5, respectively). Although mean contamination is low (mCd = 1.59), the potential ecological risk is moderate (RI = 241.8), with Cd contributing >70% of the total risk, while Ni drives the direct toxicological risk (TRI = 5.4).
Mercury (Hg) from artisanal and small-scale gold mining (ASGM) remains a source of long-term soil contamination in the Brazilian Amazon, yet its long-term persistence and controlling factors in deactivated sites are still poorly understood. This study evaluates total mercury (THg) concentrations in surface soils from three ASGM sites in the Tapajos region (active, deactivated in 2024, and deactivated for approximately 30 years), with a focus on the role of soil properties in Hg retention. Results show that the site deactivated for similar to 30 years still exhibits elevated THg concentrations (27 to 8,862 ng g(-1); median = 324 ng g(-1)) and ecological risk levels above regulatory thresholds, highlighting the long-term environmental legacy of ASGM. In contrast, recently deactivated and active sites presented average THg concentrations near the background value of 178 ng g(-1) (134 +/- 44 ng g(-1) and 77 +/- 93 ng g(-1), respectively), with localized increases near operational structures. In the long-term deactivated site, THg concentrations were strongly associated with the proportion of fine particles (R-2 = 0.73) and positively correlated with water-holding capacity (WHC, rho = 0.54, p < .01), indicating higher THg concentrations in finer-textured soils. These findings suggest that Hg persistence in this site is primarily associated with geoenvironmental controls rather than natural attenuation processes. Soil heterogeneity likely promotes the formation of microenvironments that are favorable to Hg retention and may limit its remobilization, even under high rainfall conditions. Overall, this study advances the understanding of Hg behavior in tropical post-ASGM landscapes by demonstrating that contamination persistence can be closely linked to substrate properties and small-scale variability. Our findings have direct implications for environmental monitoring and risk assessment, highlighting the need for site-specific approaches to address the long-term impacts of ASGM in the Brazilian Amazon.
Excessive concentrations of trace metals in soils in quantities above the allowed limits are dangerous to biota, ecosystems, and human health, especially when they enter the food chain through contaminated crops. Peri-urban subsistence food gardens in Lae city, Papua New Guinea, play an important role in household food security by providing a significant amount of dietary energy. However, rapid urbanization, industrial expansion, and other anthropogenic activities contaminate food garden soils with trace metals. This study investigated the concentrations, contamination status, and ecological risks of Cd, Cr, Ni, and Pb in peri-urban food garden soils in Lae City. Soil samples were taken at three depths (0-10, 10-20, and 20-30 cm), and metal concentrations were measured using inductively coupled plasma-optical emission spectroscopy, and contamination and environmental risk indicators were evaluated. Cadmium, Ni, and Pb concentrations surpassed WHO/FAO standards in 93.3%, 100%, and 10% of samples, respectively. The contamination factor, geo-accumulation index, and ecological risk indices consistently identified Cd as a significant ecological threat. While Cd and Pb were predominantly linked to anthropogenic activities, Ni and Cr appeared to originate mainly from geogenic sources. These results highlight the need for targeted monitoring and management strategies to safeguard soil quality and public health.
This pioneering study investigated the activity concentrations of naturally occurring radionuclides in 25 quarry pit soils collected from Jhalokati, Barishal, and Dhamrai, Bangladesh. HPGe gamma-ray spectrometry revealed that the measured activity concentrations ofspace(226)Ra (15-22spaceBq/kg),space(232)Th (14-34spaceBq/kg), and majority ofspace(40)K (260-480spaceBq/kg) in quarry pit soils were below the worldwide average values of 30, 35, and 400spaceBq/kg, respectively. Importantly,space(137)Cs was undetectable in all samples, indicating no influence from past nuclear fallout events. The relatively low levels of radionuclides are attributed to the regional geological setting, characterized by alluvial sediments with inherently low radioelement content, as well as processes of weathering, leaching, and quarrying that further reduce radionuclide retention. Radiological hazard parameters were similarly low: the radium equivalent activity ranged from 64 to 97spaceBq/kg (mean 80spaceBq/kg), well below the recommended limit of 370spaceBq/kg; the outdoor and indoor absorbed dose rates (31-48 and 38-57 nGy/h, respectively) were lower than the global average values of 59 and 64 nGy/h; the annual effective doses (0.22-0.34 mSv/y, mean 0.28 mSv/y) remained far below the public dose limit of 1 mSv/y; both the external (0.18-0.27) and internal (0.23-0.33) hazard indices werespace<1, indicating safe radiological conditions. This study identifiesspace(232)Th as the primary contributor to environmental radiological risk, with strong correlations to hazard parameters, whilespace(226)Ra andspace(40)K exhibit weaker correlations and distinct geochemical behaviors, highlighting the regional variability ofspace(40)K concentrations and the uniformity ofspace(226)Ra andspace(232)Th across study sites. Overall, the results demonstrate that quarry pit soils in the studied regions pose negligible radiological risk, providing the first radiological baseline for quarry materials in Bangladesh.
With the rapid advancement of urbanization and industrialization, the emission of various pollutants is continuously increasing, posing unprecedented challenges to soil environmental quality. In this context, electrokinetic remediation technology has demonstrated promising prospects in addressing these issues. Compared with traditional treatment methods, electrokinetic remediation offers the advantages of high efficiency, controllability, and environmental friendliness. This study developed a new adsorption material and coupled it with electrokinetic remediation technology to construct a combined remediation system for the treatment of cadmium(Cd)-contaminated soil. During the experimental process, variations in parameters such as electric current and pH were monitored, and the distribution characteristics and removal efficiency of Cd in the treated soil were systematically studied. hydrothermal carbon, steel slag, and the the composite material HPC/SS were used as fillers, and the integrated electrokinetic-adsorption remediation technology was applied to improve Cd removal performance. The experimental setup consisted of a regular hexagonal multi-anode system, with an electric field intensity of 1.5 V/cm. A 0.1 mol/L citric acid solution was used as the electrolyte, and the remediation process was conducted for 5 days. The results showed that introducing the HPC/SS adsorption agent in the cathode area increased the current and achieved the highest removal rate of 67.09% for soil samples containing 100 mg/kg of Cd(II) in the heavy metal-polluted soil.HPC/SS is a type of mesoporous material, which has a larger specific surface area than single materials and possesses good magnetic properties, allowing it to be recovered using an external magnetic field, making it a reusable adsorbent.
This study aims to identify a bacterium for heavy metal bioremediation. Pill bugs (Crustacea; Isopoda; Oniscidea), known for their ability to accumulate and detoxify heavy metals in humid environments, were chosen as the bacterial source. A bacterium was isolated from pill bugs and identified by 16S rDNA sequencing. Its heavy metal removal capacity from liquid culture medium was then evaluated using ICP-MS. Lastly, the therapeutic and protective effect of the isolate against heavy metal-induced genotoxicity was evaluated at the chromosomal level in the model organism Allium cepa, focusing on the heavy metal most effectively removed by the bacterium. As a result of the study, a bacterium identified as Pseudomonas sp. SS5. The bacterium's bioremediation capacity was assessed over 24h and 48h, with the following removal percentages observed: iron (6.07% and 24.38%), copper (17.82% and 63.29%), cadmium (0.41% and 4.11%), aluminum (12.29% and 30.73%), nickel (0.76% and 0.58%), and manganese (0% at 24h but 41.05% at 48h). The bacterium exhibited the highest removal efficiency for copper. In pre-, co-, and post-treatment groups of A. cepa, the bacterium showed protective effects against copper-induced mutagenicity at all tested concentrations. The SS5 strain significantly reduced copper-induced chromosomal aberrations and DNA damage compared to the control. [GRPAHICS]
Cadmium (Cd) and arsenic (As) accumulate in soils due to their persistence, posing a global remediation challenge. This study investigated the effectiveness of ferromanganese-modified biochar (Fe-Mn-BC) for stabilizing Cd and As and explored the underlying mechanisms. Soil incubation experiments were conducted using TCLP, CaCl2-extractable Cd, NaH2PO4-extractable As, and BCR sequential extraction. After 60 days of Fe-Mn-BC application, extractable Cd and As decreased from 0.65 to 0.29 mg kg(-1) and from 11.42 to 6.99 mg kg(-1), respectively, indicating enhanced stabilization. The amendment promoted transformation of mobile fractions (weak-acid Cd and reducible As) into more stable residual forms, thereby limiting metal mobility. Soil pH remained stable (7.67-7.96), supporting the stabilization process. Overall, Fe-Mn-BC reduced the bioavailability and ecotoxicity of Cd and As. Among treatments, Fe-0.(1)-Mn-0.(1) BC showed the highest effectiveness, followed by Fe-0.(1)-Mn-0.(0)(5) BC, Fe-0.(0)(5)-Mn-0.(1) BC, and BC.
This study investigated the distribution, sources, and ecological risk of PAHs along the New Damietta and Elrekabia drainage canals in northern Egypt. The isomer ratios indicated that the most abundant sources along the study area were from pyrogenic sources possibly due to anthropogenic activities along the drainage canals as fossil fuel combustion and traffic activities. The risk quotient (RQ) of wastewater to both New Damietta and Elrekabia drainage canals indicated that all detected PAHs exceeded the guideline thresholds, resulting in extremely high ecological risk levels, with Elrekabia drain exhibiting consistently higher risk values than New Damietta drain. Statistically, the difference in source type contribute to variability in PAHs as the industrial activities tend to release heavy PAHs, while agricultural and domestic sources release light and or mixed contaminants. The dendrogram analyses reflect overlapping or similar mixed pollution inputs among the two drains. In both areas, the most contributors to carcinogenic effects in wastewater were benzo[a]pyrene in addition to benzo[b]fluoranthene in sediment extract. The last PAHs individual was also the most mutagenic contributor. The obtained RQ values were several orders of magnitude higher than unity, indicating extremely high ecological risk rather than conventional high-risk classification.
This study assessed heavy metal contamination, spatial distribution patterns, and ecological risks in sediments of the Luvuvhu River Catchment (LRC), situated within the Vhembe Biosphere Reserve, South Africa. Sediment samples collected from 22 sites between November 2020 and October 2021 were analysed for trace metal concentrations and evaluated using pollution indices and multivariate statistical techniques. Although metal concentrations were generally higher during the wet season, seasonal differences were not statistically significant, indicating persistent contamination sources. Spatial variability was pronounced, with elevated metal levels in upstream and midstream sections, reflecting significant anthropogenic influences. A marked change in sediment quality at the Luvuvhu-Limpopo confluence suggests additional transboundary inputs from the Limpopo River system. Pollution indices, including Enrichment Factor, Contamination Factor, Geo-accumulation Index, and Pollution Load Index, indicated overall low to moderate contamination, although manganese showed notable enrichment (EF = 11.59). Multivariate analyses identified three dominant source groups linked to agriculture, urban runoff, and wastewater discharges. While basin-wide contamination remains moderate, localized hotspots and upstream pollutant loading present potential ecological risks. These findings highlight the need for integrated catchment-scale monitoring and targeted management strategies to protect aquatic ecosystems and support sustainable transboundary water resource governance.
Mangla Lake, a vital freshwater reservoir in Azad Jammu and Kashmir, Pakistan, sustains nearly half a million people. This study presents a novel, integrated assessment of heavy metal (HM) contamination in its sediments, combining high-resolution geospatial sampling with multivariate chemometric analysis to elucidate pollution sources, spatial patterns, and ecological risks. Sediment samples (n = 123 from 41 sites) were analyzed via ICP-MS for 10 HMs (Cr, Mn, Fe, Ni, Cu, As, Cd, Sb, Hg, Pb). Advanced statistical techniques - including cluster analysis, factor analysis, principal component analysis, and generalized network dimensionality reduction (GNDA) were employed alongside pollution indices (Igeo, EF, Hakanson's RI) to identify and apportion contamination sources. Results indicate that Fe, Mn, Cr, Ni, Pb, and As are the predominant contaminants, forming distinct spatial clusters linked to anthropogenic inputs (agricultural runoff, urban/industrial discharges) and natural weathering. GNDA outperformed traditional methods, explaining 86% variance and effectively discriminating between geogenic and anthropogenic sources. While ecological risk indices suggest low-to-moderate basin-wide risk, localized hotspots near inflows exhibit elevated concentrations, necessitating targeted management. The study advances regional sediment pollution assessments by coupling statistical source apportionment with sedimentological and hydrodynamic context, highlighting the roles of fine sediment transport, seasonal hydrology, and land use in contamination dynamics. Comparative analysis with regional and global reservoirs reveals Mangla's unique contamination profile, driven by Himalayan lithology and moderate urbanization. Findings underscore the value of integrated, process-informed monitoring and provide a scalable framework for reservoir sediment management in data-scarce regions. The results are significant for national governmental agencies (including healthcare) and planning authorities in the region and highlight the value of multidisciplinary analysis.
Hydrogen peroxide (HP) decomposition (Fenton process) is indiscriminately used to remediate any soil polluted with organic pollutants. To assess the impact of HP on gasoline site remediation, two soils with contrasting textures and Fe contents were selected: Inceptisol (In) - high clay and total Fe; Spodosol (Sp) - low clay and total Fe (soluble Fe2+ was supplemented). Columns of undeformed soil samples were fortified with gasoline and submitted to HP remediation. Remediated soil and leachate samples were analyzed. Total gasoline reduction was lower in sandy (62%) than in clayey (85%) soil. Despite this relatively high reduction of gasoline, secondary environmental problems were significant. There was significant acidification of Sp. Hydrogen peroxide reactions reduced organic matter content (OM) on both soils: sandy Sp - 66% and clayey In - 22%. The quality of OM was also negatively impacted (humin degradation), especially in sandy Sp. Hydrogen peroxide promoted strong phytotoxicity on sandy Sp. The leachate of Sp was also negatively impacted by HP: increasing Mn and Al concentrations and severe Daphnia magna toxicity. The viability of remediation with HP of sandy soil and sediment must be carefully analyzed case by case. On the other hand, clayey and high total Fe soils and sediments that do not need the supplementation of acid Fe2+ solution can be recommended.
Heavy metal (HM) contamination in coastal sediments presents significant environmental and human health concerns This study provides a site-specific integrated assessment of physicochemical properties, sediment texture, HM concentrations (Cu, Zn, Mn, Fe, Pb, Cd), contamination status, ecological risks, and human health implications in surface sediments from Sugandha Beach, Cox's Bazar. Pollution status was evaluated using enrichment factor, geo-accumulation index, contamination factor, and pollution load index, while ecological and human health risks were assessed using deterministic and Monte Carlo simulation approaches. The sediments were predominantly alkaline (pH 8.15-8.41) and sandy (88.69-93.72%), with low organic matter content. Elevated Pb concentrations were observed at all sites, with localized enrichment of Cu and Zn, whereas Cd remained below detection limits. Contamination indices indicated moderate pollution at S-5 to S-6 and S-12, primarily driven by Pb and Cu. Ecological risk ranged from low to moderate, with Pb as the major contributor. Health risk assessments indicated acceptable non-carcinogenic and carcinogenic risks, although children exhibited higher exposure sensitivity. Multivariate analyses revealed that HM distribution was associated with mixed anthropogenic and natural inputs. These findings provide baseline data for a highly dynamic sandy beach system and support targeted monitoring and management strategies for coastal environmental protection.
