Increasing rates of commercialization and industrialization have led to the comprehensive evaluation of toxic effects of microplastics on crop plants. However, research on the impact of functionalized polystyrene nanoplastics on the toxicity of heavy metals remains limited. This study investigated the effects of polystyrene, carboxy-modified polystyrene, and amino-modified polystyrene on lead (Pb) toxicity in dandelion seedlings. The results showed that carboxy -modified polystyrene with a negative charge absorbed more Pb²⁺ than polystyrene and amino-modified polystyrene, and their maximum adsorption amounts were 5.328, 0.247, and 0.153 μg g⁻¹, respectively. The hydroponic experiment demonstrated that single amino-modified polystyrene was more toxic to dandelion seedlings than polystyrene and carboxy-modified polystyrene. The presence of Pb²⁺ was found to increase antioxidant enzymes (superoxide dismutase and catalase) and non-antioxidant enzymes (glutathione and ascorbic acid) activities in response to excessive reactive oxygen species in dandelion leaves and roots treated with polystyrene and carboxy-modified polystyrene, while it did not change much when amino-modified polystyrene was added. Interestingly, compared with single Pb²⁺, the addition of amino-modified polystyrene with positive charges induced an obvious decrease in the above parameters; however, they declined slightly in the treatments with polystyrene and carboxy-modified polystyrene despite a stronger adsorption capacity for Pb²⁺. Similarly, the bioactive compounds, including flavonoids, polyphenols, and polysaccharides in dandelion, showed a scavenging effect on O₂⁻ and H₂O₂, thereby inhibiting the accumulation and reducing medicinal properties. This study found that the effects of microplastics on the uptake, distribution, and toxicity of heavy metals depended on the nanoparticle surface charge.

Marine sediments act as a sink for various heavy metals, which may have profound impact on sedimentary microbiota. However, our knowledge about the collaborative response of bacterial community to chronic heavy metal contamination remains little. In this study, concentrations of seven heavy metals (As, Cd, Cr, Cu, Hg, Pb, and Zn) in sediments collected from the East China Sea were analyzed and Illumina Miseq 16 S rRNA sequencing was applied to characterize the structure of bacterial community. Microbiota inhabiting sediments in the East China Sea polluted with heavy metals showed different community composition from relatively pristine sites. The response of bacterial community to heavy metal stress was further interrogated with weighted correlation network analysis (WGCNA). WGCNA revealed ten bacterial modules exhibiting distinct co-occurrence patterns and among them, five modules were related to heavy metal pollution. Three of them were positively correlated with an increase in at least one heavy metal concentration, hubs (more influential bacterial taxa) of which were previously reported to be involved in the geochemical cycling of heavy metals or possess tolerance to heavy metals, while another two modules showed opposite patterns. Our research suggested that ecological functional transition might have occurred in East China Sea sediments by shifts of community composition with sensitive modules majorly involved in the meaningful global biogeochemical cycling of carbon, sulfur, and nitrogen replaced by more tolerant groups of bacteria due to long-term exposure to low-concentration heavy metals. Hubs may serve as indicators of perturbations of benthic bacterial community caused by heavy metal pollution and support monitoring remediation of polluted sites in marine environments.

The adsorption of radioactive iodine, which is capable of presenting high mobility in aquatic ecosystems and generating undesirable health effects in humans (e.g., thyroid gland dysfunction), was comprehensively examined using pristine spent coffee ground biochar (SCGB) and bismuth-impregnated spent coffee ground biochar (Bi@SCGB) to provide valuable insights into the variations in the adsorption capacity and mechanisms after pretreatment with Bi(NO₃)₃. The greater adsorption of radioactive iodine toward Bi@SCGB (adsorption capacity (Qₑ) = 253.71 μg/g) compared to that for SCGB (Qₑ = 23.32 μg/g) and its reduced adsorption capability at higher pH values provide evidence that the adsorption of radioactive iodine with SCGB and Bi@SCGB is strongly influenced by the presence of bismuth materials and the electrostatic repulsion between their negatively charged surfaces and negatively charged radioactive iodine (IO₃⁻). The calculated R² values for the adsorption kinetics and isotherms support that chemisorption plays a crucial role in the adsorption of radioactive iodine by SCGB and Bi@SCGB in aqueous phases. The adsorption of radioactive iodine onto SCGB was linearly correlated with the contact time (h¹/²), and the diffusion of intra-particle predominantly determined the adsorption rate of radioactive iodine onto Bi@SCGB (Cₛₜₐgₑ II (129.20) > Cₛₜₐgₑ I (42.33)). Thermodynamic studies revealed that the adsorption of radioactive iodine toward SCGB (ΔG° = −8.47 to −7.83 kJ/mol; ΔH° = −13.93 kJ/mol) occurred exothermically and that for Bi@SCGB (ΔG° = −15.90 to −13.89 kJ/mol; ΔH° = 5.88 kJ/mol) proceeded endothermically and spontaneously. The X-ray photoelectron spectroscopy (XPS) analysis of SCGB and Bi@SCGB before and after the adsorption of radioactive iodine suggest the conclusion that the change in the primary adsorption mechanism from electrostatic attraction to surface precipitation upon the impregnation of bismuth materials on the surfaces of spent coffee ground biochars is beneficial for the adsorption of radioactive iodine in aqueous phases.

In this study, two proficient Cadmium (Cd) resistant and plant growth-promoting actinobacterial strains were isolated from metal-polluted soils and identified as Streptomyces sp. strain RA04 and Nocardiopsis sp. strain RA07. Multiple abiotic stress tolerances were found in these two actinobacterial strains, including Cd stress (CdS), drought stress (DS) and high-temperature stress (HTS). Both actinobacterial strains exhibited multifarious plant growth-promoting (PGP) traits such as phosphate solubilization, and production of indole-3-acetic acid, siderophores and 1-aminocyclopropane-1-carboxylate deaminase under CdS, DS and HTS conditions. The inoculation of strains RA04 and RA07 significantly increased Sorghum bicolor growth and photosynthetic pigments under CdS, DS, HTS, CdS + DS and CdS + HTS conditions as compared to their respective uninoculated plants. The actinobacterial inoculants reduced malondialdehyde concentration and enhanced antioxidant enzymes in plants cultivated under various abiotic stress conditions, indicating that actinobacterial inoculants reduced oxidative damage. Furthermore, strains RA04 and RA07 enhanced the accumulation of Cd in plant tissues and the translocation of Cd from root to shoot under CdS, CdS + DS and CdS + HTS treatments as compared to their respective uninoculated plants. These findings suggest that RA04 and RA07 strains could be effective bio-inoculants to accelerate phytoremediation of Cd polluted soil even in DS and HTS conditions.

Biochar modification by metals and metal oxides is considered a practical approach for enhancing the adsorption capacity of anionic compounds such as phosphate (P). This study obtained paper mill sludge (PMS) biochar (PMSB) via a one-step process by pyrolyzing PMS waste containing ferric salt to remove anionic P from water. The ferric salt in the sludge was transformed into ferric oxide and zero-valent-iron (Fe⁰) in N₂ atmosphere at pyrolysis temperatures ranging from 300 to 800 °C. The maximum adsorption (Qₘ) of the PMSBs for P ranged from 9.75 to 25.19 mg P/g. Adsorption is a spontaneous and endothermic process, which implies chemisorption. PMSB obtained at 800 °C (PMSB800) exhibited the best performance for P removal. Fe⁰ in PMSB800 plays a vital role in P removal via adsorption and coprecipitation, such as forming the ≡Fe–O–P ternary complex. Furthermore, the possible chemical precipitation of P by CaO decomposed from calcite (CaCO₃; an additive of paper production that remains in PMS) may also contribute to the removal of P by PMSB800. Moreover, PMSBs can be easily separated magnetically from water after application and adsorption. This study achieved a waste-to-wealth strategy by turning waste PMS into a metal/metal oxide-embedded biochar with excellent P removal capability and simple magnetic separation properties via a one-step pyrolysis process.

Bauxite residue, an industrial alkaline solid waste, has a low organic carbon content which hinders plant growth. Dissolved organic matter (DOM) drives many biogeochemical processes including carbon storage and soil formation in soils. Input of exogenous organic materials may provide organic carbon and accelerate soil formation processes in bauxite residue. However, the potential effects of ameliorants on the quantity and quality of DOM in bauxite residue are still poorly understood. Here, the integration of ultraviolet–visible (UV–Vis) spectra, fluorescence spectra, and parallel factor (PARAFAC) analysis were used to investigate the vertical characteristics of DOM in bauxite residue treated by PV (the combined addition of 2% phosphogypsum and 4% vermicompost, w/w) and BS (6% w/w including 4% bagasse and 2% bran) with 2-year column experiments. The content of DOM in untreated residues ranged from 0.064 to 0.096 g/kg, whilst higher contents of DOM were observed in PV (0.13 g/kg) and BS (0.26 g/kg) treatment. Meanwhile, with the increase of residue depth, the aromaticity and hydrophobic components of DOM in residue decreased, which indicated that the degree of humification of the treated residues in the upper layer was higher than that in the lower layer. Compared with BR, BS and PV treatment accumulated the related content of fulvic acid-like substance from 36.14% to 71.33% and 74.86%, respectively. The incorporation of vermicompost and biosolids increased the content of humic-like substances, whilst decreasing the content of protein-like substances in the surface layer, which may be due to the enrichment of the microbial community. During soil formation processes, the application of organic amendments reduced both salinity and alkalinity, enhanced microbial community diversity, and changed the quantity and quality of DOM in bauxite residue. These findings improve our understanding of the dynamics of DOM and response of DOM to soil formation processes in bauxite residue.

Nickel (Ni) and manganese (Mn) are well known for the production of steel and alloys and are commonly found co-occurring in Ni ores. They are metals of environmental concern and contamination in the marine environment is problematic single exposures and in combination. Several studies have documented the effects of single metal exposure on the model anemone E. pallida, but research on the effects of metal mixtures is far less common. This novel study assesses the accumulation and stress effects of Ni and Mn over a 12-d exposure period. E. pallida were exposed in two separate experiments; Ni alone and Ni in combination with Mn, to assess accumulation, along with any effect on the density of symbionts and anemone tentacle length. Anemones were transferred to ambient seawater to assess depuration and recovery over 6 d. Anemone tissue accumulated Ni at a magnitude of five times higher in a mixture of 0.5 mg Ni/L with 2.5 mg Mn/L compared to the same concentration in a single Ni exposure experiment. In both experiments, Ni and Mn preferentially accumulated in the Symbiodinium spp. compared to the anemone tissue, but Ni depuration was more rapid in the mixture than Ni alone exposure. This study reveals a significant reduction in anemone Symbiodinium spp. density after exposure to Ni and Mn mixtures, but not with Ni exposure alone. A significant dose-dependent reduction in tentacle length was observed in anemones after 12 d of the Ni exposure both with and without Mn. The estimated sublethal concentration that causes tentacle retraction in 50% of test anemones (EC50) by Ni was 0.51 (0.25–0.73) mg/L, while in combination with Mn the EC50 was 0.30 mg Ni/L (confidence limits not calculatable). The present data reveals the importance of testing metal effects in combination before establishing safe limits for marine invertebrates.

Finding an appropriate satellite image as simultaneous as possible with the sampling time campaigns is challenging. Fusion can be considered as a method of integrating images and obtaining more pixels with higher spatial, spectral and temporal resolutions. This paper investigated the impact of Landsat 8-OLI and Sentinel-2A data fusion on prediction of several toxic elements at a mine waste dump. The 30 m spatial resolution Landsat 8-OLI bands were fused with the 10 m Sentinel-2A bands using various fusion techniques namely hue-saturation-value (HSV), Brovey, principal component analysis (PCA), Gram-Schmidt (GS), wavelet, and area-to-point regression kriging (ATPRK). ATPRK was the best method preserving both spectral and spatial features of Landsat 8-OLI and Sentinel-2A after fusion. Furthermore, the partial least squares regression (PLSR) model developed on genetic algorithm (GA)-selected laboratory visible-near infrared-shortwave infrared (VNIR–SWIR) spectra yielded more accurate prediction results compared to the PLSR model calibrated on the entire spectra. It was hence, applied to both individual sensors and their ATPRK-fused image. In case of the individual sensors, except for As, Sentinel-2A provided more robust prediction models than Landsat 8-OLI. However, the best performances were obtained using the fused images, highlighting the potential of data fusion to enhance the toxic elements’ prediction models.

Amoxicillin (AMO) and amikacin (AMK) are broad-spectrum antibiotics that are most preferably given post-delivery (normal and cesarian) in the maternity hospitals located in Sagar city (Madhya Pradesh), India. Both the antibiotics make their way through sewage/drainage systems into the environment in the form of metabolized and unmetabolized compounds. Growing concern about the contamination of wastewater by antibiotics requires fast, sensitive and eco-friendly techniques. Therefore a simple, rapid and environmental friendly chromatographic method has been developed for simultaneous determination of AMO and AMK in maternity hospital wastewater samples. A micellar liquid chromatographic (MLC) method was developed with a C₁₈ column (250 mm × 4.6 mm), sodium dodecyl sulphate (SDS; 0.15 M), 1-butanol (7%) as a modifier, pH 5 and photo diode detector (PDA) at 270 nm and 256 nm for AMO and AMK respectively. The method was fast with analysis time below 9 min. In the present MLC method, linearities (r > 0.998), limits of quantification in the range of 0.02–0.04 μg/mL, repeatabilities, and intermediate precision below 4.9% were adequate for the quantification of AMO and AMK. The proposed method can be utilized to detect and quantify both the antibiotics in various samples by hospitals, pharmaceutical companies, pollution control board, municipal corporations, etc.

This study assessed the human health risk of exposure to legacy PAHs in the Nwaenebo River sediments that received effluents for over two decades from the Nigeria National Petroleum Corporation (NNPC) petroleum product Depot in Emene, Enugu, Nigeria. The study went further to estimate economic costs of the sediment PAHs pollution based on the human health risk of exposure. The human health risks were determined by estimating carcinogenic and mutagenic risks via Benzo[a]pyrene total potential equivalent (BaP TPE) and mutagenic equivalent quotient (MEQ). The economic costs of the sediment pollution comprised costs due to mortality and those due to morbidity and were estimated using the value of statistical lives (VSLs) and cost of illness (CoI), respectively. The study, with an appropriate selection of sampling points established that the NNPC petroleum Depot was responsible for the Nwaenebo River sediment PAHs pollution with ƩPAHs concentration 14.3–163 mg/kg. The carcinogenic and mutagenic risks varied from 1.3*10^-5 to 4.7*10^-5 and 1.4*10^-5 to 6.0*10^-5 respectively. Based on risk threshold of 10^-6, these risks were high. The long term economic costs of pollution of the sediments by the PAHs were estimated at 60.5 million USD and 0.46 million USD for mortality and morbidity costs, respectively.