Journal of Environmental Science and Health Part A-toxic\/hazardous Substances & Environmental Engineering最新文献

Heavy metal (HM) contamination in urban road dust (RD) represents a significant environmental and public health concern, particularly in densely populated and industrialized regions. This study investigated the spatial distribution and associated health risks of cadmium (Cd), chromium (Cr), nickel (Ni), lead (Pb), and zinc (Zn) in RD across various land-use types in Arak, Iran. During a nine-month sampling campaign, 160 RD samples were collected from twenty strategic locations representing industrial, residential, commercial, and high-traffic zones. Land-use regression (LUR) modeling was employed to map HM concentrations and identify pollution hotspots. The mean concentrations of Cd, Cr, Ni, Pb, and Zn were 0.48, 64.6, 44.4, 133.9, and 277.6 mg/kg, respectively, substantially exceeding global soil background values. Spatial analysis identified the southern, central, and southeastern sectors as critical pollution hotspots, primarily influenced by vehicular emissions and industrial activities. Health risk assessment revealed ingestion as the dominant exposure pathway, with lead posing the most significant non-carcinogenic risk to children (HI = 0.522). The cumulative hazard index for all metals reached 0.9036 in children, approaching the safety threshold of 1. Furthermore, the total carcinogenic risk for children (2.27 × 10^-4) slightly exceeded acceptable levels, with nickel being the predominant contributor. This study provides critical evidence supporting the urgent need for targeted public health interventions, stringent emission controls, and science-based urban planning strategies to mitigate heavy metal exposure risks in vulnerable urban populations.

The current study employed the isolation of a novel metal-resistant bacterium, Enterobacter quasihormaechei (GenBank Accession No. OR659321) from raw printed circuit boards (PCBs) waste for its bioleaching potential. The bacterium shows promising recovery efficiencies of multiple important metals (Ag 87.5%, Al 60.53%, Mg 58.71%, Cr 56.52%, Ca 55.80%, Cu 55.03%, Mo 50%, Zn 46.36%, Ba 44.22%, Fe 34.54%, Ni 34.15% and Mn 28.22%) from PCBs waste at 37 °C, 150 rpm and 5-days of incubation period. Further confirmation of bioleaching was carried out by FTIR, FE-SEM, EDS and XRD, respectively. The oxidation-reduction potential (ORP) was also investigated, and it was found to be reduced during the bioleaching of electronic waste. Overall, the current study demonstrates that the bacterium, E. quasihormaechei, can recover multiple valuable metals from PCBs without chemical pretreatment or nutrient additives through eco-friendly and cost-effective bioleaching methods.

The paper presents the results of Cr, Co, Cu, Fe, Ni, Mn, Pb, Zn, and four radionuclides (²²⁶Ra,²³²Th, ¹³⁷Cs, and ⁴⁰K) determination in transplanted lichens after two, four, and six months of exposure. Lichens were sampled from the area of Mountain Igman in Bosnia and Herzegovina (BiH) and transplanted to two locations (Pofalići and Bjelave) in Sarajevo, the capital city of BiH. The total metals content was determined by flame atomic absorption spectrometry (FAAS). Gamma spectrometry (GS) was used for radionuclide activity determination. Content of Cr, Co, Cu, Fe, Mn, Ni, Pb an Zn in lichen after two, four, and six months of exposure ranged as follows: 137Cs ranged from 19.95 to 56.66 Bq/kg, while for ⁴⁰K ranged from 49.65 to 330.61 Bq/kg. The specific activity of ²²⁶Ra and ²³²Th was below the GS limit of detection.

Clopyralid is among the most widely used herbicides worldwide. Discharging clopyralid-contaminated water into the environment can adversely affect human health and ecosystems. Research on the biological treatment of clopyralid-laden wastewater is crucial for enhancing process performance and preventing environmental contamination. This study investigates the biodegradation of clopyralid by an activated sludge (AS) culture to clarify its microbial degradation and inhibition kinetics. Furthermore, the inhibitory effect of clopyralid on isolated AS microorganisms (bacteria and fungi) was examined using paper disk and broth culture methods. The results demonstrate the potential of AS to biodegrade clopyralid. Clopyralid degradation rates increased with increasing herbicide concentration from 50 to 225 mg/L, then declined. At 300 mg/L, clopyralid biodegradation was completely inhibited. Luong's kinetics model for inhibitory substrates accurately described this biodegradation pattern. All cultured bacteria and fungi were inhibited at higher clopyralid doses. However, while most bacteria were inhibited at 1200 mg/L of clopyralid, fungi were inhibited at a 10-fold higher concentration. At this concentration range, clopyralid exhibited a bacteriostatic/fungistatic effect rather than a bactericidal/fungicidal one. That is, it did not cause lethal disruption of essential cellular functions. The findings of this study could inform strategies to enhance clopyralid biodegradation at high concentrations in AS reactors.

Chromium (Cr), classified by the International Agency for Research on Cancer (IARC) as a carcinogen, poses significant risks to human health. This study evaluated the uptake of Cr in Arachis hypogaea, Vigna unguiculata, and Zea mays cultivated in Cr-contaminated soils and assessed the associated toxicological risks to human consumers. A greenhouse experiment was conducted using soils contaminated with Cr at 10 and 30 mg kg^-1. Chromium concentrations in soils and plant tissues were quantified using ICP-OES, and bioconcentration and translocation factors (TFs) were determined to assess Cr uptake and movement within the plants. The lifetime incremental cancer risk (ILCR) was determined to evaluate potential long-term health risks. Results showed that all three species accumulated significant amounts of Cr in roots and aerial tissues, with bioconcentration factors (BFs) greater than one in most treatments. However, TFs remained below or equal to one for most cases, indicating limited upward movement of Cr. Importantly, ILCR values were within permissible limits, suggesting no significant carcinogenic risk for consuming these crops. These findings indicate that A. hypogaea, V. unguiculata, and Z. mays are resistant to Cr contamination and can be safely cultivated and consumed in soils containing up to 30 mg kg^-1 of Cr. This study provides valuable insights for ecotoxicological risks and for the safe management of Cr-contaminated agricultural soils in Mozambican industrial areas.

Oil pollution poses a serious threat to aquatic ecosystems and water quality, necessitating the development of efficient, selective, and reusable absorbent materials. In this study, cork was chemically modified using deep eutectic solvents (DES) synthesized from nonanoic acid combined with either choline chloride or betaine at a 1:4 molar ratio. To further enhance hydrophobicity, the DES-treated corks were subsequently coated with stearic acid. The successful chemical modification and structural changes were confirmed through comprehensive characterization using Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR), ultra-high resolution scanning electron microscope (UHR-SEM), and thermogravimetric analysis (TGA). The materials were then tested for their oil absorption capacity, reusability, and antibacterial properties. The comprehensive characterization confirmed successful chemical modification and structural changes in the cork material. The DES-treated corks exhibited improved antibacterial activity against Escherichia coli ATCC 25922, showing significant reductions of 23.2% (choline chloride-based) and 47.1% (betaine-based) compared to untreated cork. Absorption tests with engine oil and dichloromethane demonstrated that the betaine-nonanoic acid-treated cork achieved superior performance, with high absorption capacities of 13.92 g g^-1 and 28.15 g g^-1, respectively, and an oil-water separation efficiency of 80.14%. Furthermore, the material maintained high efficiency over 10 reuse cycles with minimal loss in capacity. These findings highlight the potential of DES-treated cork, particularly when coated with stearic acid, as a sustainable and high-performing sorbent for oil spill remediation.

With the rapid development of agriculture and industrialization, nitrate (NO₃^-) contamination has become an increasingly severe global environmental issue. In this study, a nitrogen-doped porous carbon material (Cf-U1Z1-450) was synthesized using coffee grounds as the carbon precursor, with quaternary nitrogen (N-Q) species successfully incorporated via urea-assisted doping. Structural characterization confirmed the effective introduction of N-Q groups, which significantly enhanced the material's adsorption performance. Batch adsorption experiments revealed that Cf-U1Z1-450 exhibited a maximum nitrate adsorption capacity of 0.62 mmol/g under acidic conditions (pH 3). Even under neutral to alkaline conditions (pH 7-11), it still showed considerable uptake, suggesting that N-Q groups remained active at higher pH. Furthermore, fixed-bed column adsorption experiments demonstrated regeneration ability and adsorption stability, with the saturated adsorption capacity remaining nearly unchanged after five adsorption-desorption cycles. These results indicate the crucial role of N-Q functional groups in improving nitrate removal and biomass-derived carbon materials modified with N-Q hold potential for application in nitrate-contaminated water treatment.

China's gold mining enterprises produce a large amount of cyanide slag containing copper ions and cyanide every year, which causes serious environmental pollution if deposited directly. Aiming at hazardous waste cyanide slag, a new process of "cyanide slag washing, copper ions precipitation in washing solution and gaseous membrane recovery of CN^-" was developed by combining theoretical analysis with experimental research, which realized the comprehensive utilization of copper ions and cyanide in the slag. Firstly, the washing test of cyanide waste slag was carried out. The results showed that when the pH of washing water was 3.0 and the water amount was 0.8 m³/t, the total cyanide concentration in the leaching toxicity of cyanide residue was less than the limit value of 5 mg·L^-1 stipulated by the national standard. Secondly, the thermodynamics and chemical analysis results show that Cu²⁺/Cu(CN)_n^(n-1)- in the washing solution can be removed by CuCN and CuS precipitation, and cyanide is converted into HCN and absorbed by NaOH solution to form NaCN. Further experimental studies showed that the precipitation rate of Cu²⁺/Cu(CN)_n^(n-1)- reached 98.99% under the condition of pH 3.5 and NaHS dosage of 200 mg·L^-1. The total cyanide removal rate was 99.02% when the flow rate of washing solution was 0.4 m³/h and the two-stage membrane was used. The feasibility and stability of the new method were verified by the cycle test, which can not only solve the problem of toxic and harmful substances leakage in the tailings dam but also maximize the utilization of mineral resources.

This study corroborated the viability of heterogeneous Fenton and heterogeneous photo-Fenton process for the degradation of atrazine from aqueous solution. Nano-scale iron manganese binary oxide supported zeolite (NIMZ) was synthesized and was used as a catalyst to degrade atrazine. The influence of numerous factors like pH, H₂O₂ dosage, and catalyst dosage on atrazine degradation was investigated. Under the operating parameters of pH 3, 0.02 M H₂O₂, and 200 mg/L catalyst, the heterogeneous Fenton system reached its highest atrazine degradation efficiency of 58.15%. Nonetheless, the atrazine elimination achieved through the heterogeneous Fenton method was relatively modest. Thus, to enhance the atrazine degradation efficiency, heterogeneous photo-Fenton method was employed to treat atrazine concentration of 50 µg/L. The experimentally determined optimal pH, H₂O₂ dosage and catalyst dosage in the heterogeneous photo-Fenton process were 3, 0.02 M and 250 mg/L, respectively. A degradation efficiency of 76.26% was recorded with the heterogeneous photo-Fenton process, exceeding the conventional heterogeneous Fenton process (58.15%) by 18.11%. Quenching studies revealed that effectiveness of heterogeneous photo-Fenton process was majorly owing to large number of hydroxyl radicals generated because of catalytic decomposition of H₂O₂ by NIMZ and photo decomposition of H₂O₂ by irradiation of UV light.

The aim of this study was to evaluate the survival, metabolism and swimming behavior of Rhinella arenarum tadpoles exposed to burned sediments from dry lagoons located in the "Los Sapos" Island (Santa Fe Province, Argentina), with different fire events over one year: no fire events (NF), two fire events (TF) and multiple fire events (MF). The physicochemical parameters of the sediments were analyzed. A sediment test was performed using 25, 50 and 100% dilutions of each sediment sample at a microcosm scale for 48 h. Tadpole survival and swimming behavior, as well as acetylcholinesterase (AChE) and glutathione S-Transferase (GST) activities (markers of neurotoxicity and oxidative stress), were analyzed. The burned sediments showed high conductivity (<1000 μS/cm2) and proton activity with presence of carbonates. The treatments with sediments from TF and MF led to mass tadpole mortality (100%). Diluted 25 and 50%, these treatments also resulted in a significant decrease (30%) in the activities of AChE and GST as well as in the swimming speed (60%) and total distance moved (40%) respect to the NF treatment (ANOVA and Tukey's test, p < 0.05). These results highlight the high ecological risks faced by tadpole reproductive sites that have been affected by fires.