Chemosphere最新文献

Wastewater treatment plants (WWTPs) are a point source for the release of per- and polyfluorinated alkyl substances (PFAS) into the environment. In our study we investigated wastewater effluent and mixed liquor samples for PFAS in order to obtain information on the current PFAS contamination in municipal WWTPs in Bavaria, Germany. In addition to PFAS target analysis, the total oxidizable precursor (TOP) assay was used as a PFAS sum parameter to obtain information on the precursor concentration in the samples. The sewersheds of the investigated wastewater treatment plants were characterized according to the industrial sectors that discharge into the public sewer system using the Statistical Classification of Economic Activities in the European Community (NACE) code. Known PFAS were detected in all effluent samples, except one, and in concentrations up to 4.700 ng L^-1. The concentrations in effluent samples varied widely between the different sampling dates at the individual WWTPs and also between the different WWTPs. The PFAS concentration in the effluent of 65 % of the WWTPs investigated increased significantly by a factor of 2.9 on average after the TOP assay. In the mixed liquor samples, the PFAS concentration ranged between 56 and 440 μg kg^-1 dw. The concentration varied less than in the effluent samples. After the TOP assay the PFAS concentration in the mixed liquor samples increased on average by a factor of 4. The NACE codes alone cannot be used to determine whether low or high PFAS concentrations are to be expected in a municipal WWTP. However, they can provide an indication of PFAS dischargers and help to prioritize further investigations. Without the TOP assay, the PFAS concentration in the effluent and the mixed liquor samples is clearly underestimated. Our investigations identified hotspots with very high PFAS concentrations in the WWTP effluents. Measures must be taken at the sources to prevent the further release of PFAS into the environment via municipal WWTPs.

Tire particles (TPs) are one of the biggest contributors to microplastic pollution, with reported soil concentrations exceeding 1 % close to busy roads. Little research has been done on the impact of TPs on soil organisms. In this study, two size classes of tire particles, 0-75 μm and 75-180 μm, were compared to determine if size does influence their toxicity to the springtail Sinella curviseta. Adult springtails were exposed for three weeks to TPs spiked in LUFA 2.2 natural soil at concentrations between 0.0016 % and 4 % (w/w). TP addition caused an increase of soil pH at the two highest concentrations, and a dose-related increase of soil Zn concentrations, which were higher for the larger TPs. Available (0.01 M CaCl₂ extractable) Zn concentrations also increased, but were far below toxic levels in all cases. Springtail survival was not affected, but reproduction was decreased by 59 % and 39 % at the highest concentration (4 %) compared to the control for the 0-75 μm and 75-180 μm classes, respectively. EC₅₀s were 3.50 % TPs in soil for the 0-75 μm class and 6.36 % TPs for the 75-180 μm class, and differed significantly between the two size classes (χ²_df = 1 > 3.84, p < 0.05). These results suggest that smaller sized tire particles (0-75 μm) are more toxic to S. curviseta than larger ones (75-180 μm). It may also be concluded that long-term exposure to tire particles may threaten springtail populations at the highest concentrations currently found near roadsides.

The high concentration of heavy metals and persistent organic pollutants in tannery wastewater poses a serious threat to human health and environmental safety. These pollutants are difficult to remove through conventional treatment methods. This study investigates an alternative treatment approach that uses a sequential process that combines a biological stage with electrochemical treatment for improved efficiency. In the initial stage, a microalga isolated from local tannery effluent, identified as Chlorella sorokiniana, was used to remove heavy metals, achieving up to 78.43 % removal of chromium, and the almost complete removal of other toxic metals (99.3 % for As, and 98.9 % for V). Although biological treatment initially led to an increase in chemical oxygen demand (COD), extended incubation times resulted in COD reductions of up to 37 %. Various mixed metal oxide (MMO) anodes were prepared for the electrochemical stage using microwave irradiation for calcination. Tannery wastewater pre-treated with microalgae was further treated electrochemically using Ti/(RuO₂)₀.₉(TiO₂)_0.1 and Ti/(RuO₂)_0.9(Sb₂O₅)_0.1 anodes at different current densities. The Ti/(RuO₂)₀.₉(TiO₂)_0.1 anode, calcined at 400 °C and operated at 60 mA/cm², achieved the highest COD removal of 94.25 %, with further reduction in chromium. Under optimized conditions, the energy consumption was 21.4 kWh/m³, marking the lowest reported for electrochemical treatment of tannery wastewater, highlighting the efficiency of these anodes relative to previous studies. Integrating biological and electrochemical methods, this sequential treatment approach significantly improves the removal of organic compounds, chromium, and other pollutants, demonstrating the synergistic effect of the combined process and presenting a more sustainable and effective solution for tannery wastewater treatment.

Perfluoroalkyl carboxylic acids (PFCAs) are persistent in the environment, and can enter the human body. This study aimed to investigate the in vivo kinetics of branched PFCAs with seven to fourteen carbon atoms (C₇ to C₁₄) using samples collected different individuals: bile (n = 5), urine (n = 10), and cerebrospinal fluid (CSF) (n = 7), with their corresponding serum. This study revealed that the clearance values of PFCAs were greatly affected by whether they were linear or branched. Furthermore, it demonstrated that C₇ and C₈ branched PFCAs had higher total (renal plus fecal) clearance values than their linear counterparts and that they were more easily excreted from the body via urine (higher renal clearances). However, when the chain length was C₉ or longer, the clearance value was almost the same as that of linear PFCAs because fecal clearance through the bile is the main route of clearance from C₉ onwards, and there is no significant difference in fecal clearance between branched and linear ones. The ratio of branched to linear PFCAs in the CSF was similar as that in the serum for all PFCAs (C₇ to C₁₄) measured, and there appeared to be no difference in blood-brain barrier permeability. This information will be useful for evaluating potential health risks related to branched PFCAs.

Gravity-driven membrane (GDM) systems are increasingly recognized as sustainable and energy-efficient solutions for decentralized water treatment. However, membrane fouling, particularly by organic matter, remains a significant operational challenge, necessitating regular chemical cleaning to maintain performance. The present study was undertaken to investigate the cleaning efficiency of sodium dichloroisocyanurate (NaDCC) tablets, a novel solid-state alternative to conventional liquid cleaning agents such as sodium hypochlorite (NaOCl), sodium lauryl sulfate (SLS), acetic acid, and citric acid. NaDCC tablets, originally developed for drinking water disinfection, offer advantages in terms of transport, storage, and safety compared with conventional liquid formulations. A comparative evaluation of cleaning agents was conducted on hollow fiber membranes used in GDM systems, with the concentration and contact times optimized for each chemical. NaOCl demonstrated the highest permeability recovery, reaching 48.29% at 500 mg L^-1 after 12 h, followed closely by NaDCC, with a recovery of 46.55% under similar conditions. Conversely, SLS, acetic acid, and citric acid presented significantly lower recovery rates, with maximum flux restorations of 14.57%, 14.90%, and 16.73%, respectively. These results highlight the comparable performance of NaDCC and NaOCl in addressing organic fouling while offering practical advantages such as greater stability and reduced chemical handling risks. This study highlights the efficacy of NaDCC as a viable detergent for GDM systems, and also provides a comprehensive comparative analysis of the water permeability performances of commercial detergents such as NaOCl, which cause various ecotoxicities, and suggests the feasibility of NaDCC as a chemical detergent in practical membrane processes. Our findings contribute to the development of more sustainable and cost-effective membrane-cleaning protocols that enhance long-term operational efficiency and minimize environmental impacts.

The influence of transboundary air pollutants originating from the Asian continent on South Korea has been a major concern. Although organochlorine pesticides (OCPs) have been banned for several decades, they continue to be detected in the Korean environment. However, studies on the long-range atmospheric transport (LRAT) of OCPs in South Korea, particularly in background areas, remain limited. This study investigated the atmospheric levels, sources, and behavior of OCPs at Deokjeok Island, a background site near the west coast of the Korean Peninsula. Total concentrations of 24 OCPs ranged from 53.6 to 325 pg/m³, which are lower than those reported by the national POPs monitoring network of South Korea and similar to levels found in other background regions in Northeast Asia. HCB (62.7 pg/m³, 45%) and PeCB (46.6 pg/m³, 33%) were the most dominant OCPs in the gaseous phase, whereas DDTs were predominant (1.65 pg/m³, 44%) in the particulate phase. Gaseous OCPs were strongly influenced by past use and re-emissions, while ongoing emissions and LRAT were the major sources of particulate OCPs. The consistent detection of mirex provides strong evidence of LRAT. In addition, correlation analysis and the Clausius-Clapeyron equation indicated that DDTs were significantly influenced by LRAT. Concentration-weighted trajectory maps identified East, North, and Northeast China as the major source regions for gaseous OCPs, driven by re-emissions, while the primary source areas for particulate OCPs were Beijing, Hebei, Tianjin, and Shandong. Air/soil fugacity fractions showed equilibrium or net deposition for most OCPs (except PeCB), indicating the dynamic environmental behavior of OCPs influenced by past use and LRAT. This study provides evidence of LRAT of OCPs to South Korea, demonstrating the significant impact of transboundary pollution. These results highlight the importance of ongoing monitoring of both historically and currently used pesticides at receptor sites in Northeast Asia.

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/policies/article-withdrawal). < This article has been retracted at the request of the Editors-in-Chief. A journal-wide investigation by Elsevier's Research Integrity & Publishing Ethics team identified violations of the journal's policies on authorship and conflict of interest related to the submission and review of this paper. An authorship change was made during the revision of this paper; the author Kathirvel Brindhadevi was added to the revised paper without validation or authorisation and credited with preparing the original draft. Review of this submission was handled by Guest Editor Thamaraiselvi Kaliannan despite an extensive record of collaboration, including co-publication, with one of the paper co-authors (Arivalagan Pugazhendhi). Acceptance of the article was partly based upon the positive advice of reviewers who were closely linked to one of the authors (Pugazhendhi). This compromised the editorial process and breached the journal's policies. The authors disagree with this retraction and dispute the grounds for it.>.

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/policies/article-withdrawal). .

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/policies/article-withdrawal). .