Environmental Science: Processes & Impacts最新文献

Isocyanates are well-known irritants and sensitizers, and measuring their occupational airborne exposure is challenging due to their high chemical reactivity and semi-volatile nature. This study builds on a previous publication by our team that focused on comparing evaluation methods for isocyanates. The current research aims at developing, validating, and applying a laboratory generation system designed to replicate real-world conditions for spraying clear coats in autobody shops using hexamethylene diisocyanate (HDI)-based products. The system involved a spray gun connected to two chambers in series, enabling sample collection and analysis. The system successfully generated HDI and isocyanurate concentrations ranging from 0.008 to 0.040 mg m^-3 and 0.351 to 3.45 mg m^-3, respectively, with spatial homogeneity (RSD) of 5.8% and 16.5%. The particle-size distribution (MMAD) of 4 μm was measured using a cascade impactor and an electrical low-pressure impactor. The samples generated were used to correlate the amount of isocyanates collected with scanning electron microscope images of droplets on a filter. Three methods were compared to the reference method-an impinger with a backup glass fibre filter (GFF) and 1,2-methoxyphenylpiperazine (MP) based on ISO 16702/MDHS 25-in six generation experiments: (1) Swinnex cassette 13 mm GFF MP (MP-Swin); (2) closed-face cassette 37 mm GFF (end filter and inner walls) MP (MP-37); and (3) denuder and GFF dibutylamine (DBA) (ISO 17334-1 Asset). The analysis revealed clear trends regarding which sampler sections collected HDI (mainly in the vapor phase) or isocyanurate (exclusively in the particulate phase). The study found no significant bias between the tested methods (MP-Swin, MP-37, and Asset) and the reference method (impinger) for both HDI monomer and isocyanurate. The three tested methods showed limits of agreement beyond the acceptable range of ±30% (95% confidence interval), largely due to data variability, though MP-Swin and MP-37 exhibited lower variability than Asset. The results will be further evaluated in a real-world environment where similar clear coats are used.

Per- and polyfluoroalkyl substances (PFAS) are reported in residential and commercial paints, but there are no data for paints used in the transportation sector. From 2023 to 2024, 16 traffic paints and 10 bridge paints were collected from Pacific Northwest regional transportation facilities or purchased and analyzed for total fluorine by ¹⁹F-nuclear magnetic resonance (NMR) spectroscopy, volatile PFAS by gas chromatography-mass spectrometry (GC-MS), and ionic target and suspect PFAS by liquid chromatography-quadrupole time-of-flight mass spectrometry. The only target PFAS identified was 6:2 fluorotelomer phosphate diester (diPAP) which ranged in concentrations from 0.065 to 13 μg g^-1. While 6:2 diPAP is not regulated in paints, it can undergo environmental transformation to act as a source of perfluoroalkyl carboxylic acids. A combination of ¹⁹F-NMR and GC-MS was used to quantify and identify the fluorinated aromatic PFAS, parachlorobenzotrifluoride (PCBTF), at concentrations from 440 to 16 000 μg g^-1 in bridge paints, thus PCBTF may contribute to work exposure and levels in urban air. Additionally, evolved gas analysis with mass spectrometry and pyrolysis-GC-MS established that the insoluble fraction of paints is not comprised of fluoropolymers. Based on the amount of paint required per kilometer, we estimate up to 0.20-2.30 g 6:2 diPAP per kilometer depending on marking type. Therefore, traffic paint may be a potential source of the PFAS detected in urban runoff.

This study investigated microplastic polyester fibres representative of those shed during laundering as sorbents for metal ions. During sewage distribution and treatment, microplastics are exposed to elevated concentrations of metal ions, typically for several days. Cryogenic milling was used to generate polyethylene terephthalate (PET) fibres. Characterisation using optical microscopy and Raman spectroscopy revealed that milling did not cause significant chemical alteration to the fibres. Milled fibres were subsequently assessed in screening tests for their capacity to retain 12 metal ions-Sb(III), As(III), Cd(II), Cr(VI), Cu(II), Co(II), Pb(II), Hg(II), Mo(VI), Ni(II), V(V) and Zn(II)-at pH 8. All metal ions were sorbed onto PET fibres. The highest distribution coefficient (K_d) was observed for Pb²⁺ (939 mL g^-1), followed by Cd²⁺ (898 mL g^-1), Cu²⁺ (507 mL g^-1), Hg²⁺ (403 mL g^-1), and Zn²⁺ (235 mL g^-1). The extent of sorption is largely explicable by electrostatic interactions between the PET surface (1.95 point of zero net charge) and the predicted metal ion species. The sorption behaviour of Cd²⁺ and Hg²⁺ was examined in more detail since both showed high sorption capacity and are highly toxic. Kinetic experiments revealed that the sorption of both elements was relatively fast, with a steady state reached within six hours. Experimental data from isotherm tests fitted well to the Langmuir sorption model and demonstrated that PET fibres had a much greater sorption capacity for Hg²⁺ (17.3-23.1 μg g^-1) than for Cd²⁺ (4.3-5.3 μg g^-1). Overall, the results indicate that retention of metal ions onto PET fibres originating from laundry is expected during full-scale sewage treatment, which facilitates the subsequent transfer of metals into the terrestrial environment, given that sewage sludge is commonly applied to agricultural land.

Compost-derived dissolved organic matter (DOM_C) is a heterogeneous assemblage of different redox-active organic molecules. We hypothesize that DOM_C can interact with Cr(VI) and reduce it to Cr(III), thereby influencing the dynamics of Cr(VI) in soil and aquatic environments. Here, DOM_C, along with soil humic substances isolated from red soil and black soil, were fractionated into humic acid fractions (i.e., HA_C, HA_B, and HA_R) and fulvic acid fractions (i.e., FA_C, FA_B, and FA_R), respectively. The reduction and interaction between Cr(VI) and the six organic matter fractions were investigated. The results showed that the total Cr(VI) reduction capacity (TRC) of the six organic matter fractions was 26.77-49.34 μM Cr(VI) per mg OM. The TRC of HA fractions was 35.54-49.34 μM Cr(VI) per mg OM, which exceeded that of FA fractions (26.77-31.29 μM Cr(VI) per mg OM). DOM_C had a HA/FA ratio of 0.64, which was higher than that of black soil humic substance (0.59) and red soil humic substance (0.20). The sum of the TRC of DOM_C was 35.57 μM Cr(VI) per mg OM, which was larger than that of black soil humic substance (32.87 μM Cr(VI) per mg OM) and red soil humic substance (33.01 μM Cr(VI) per mg OM). The TRC was positively correlated with TOC, TN, phenol C, alkyl C, and aromatic C contents and negatively correlated with E₂/E₃, O-alkyl C, and carboxyl C contents. The reduction of Cr(VI) at pH 6 was negligible, whereas 32-67% Cr(VI) was reduced at pH 2. The Cr(VI) reduction capacities (RC2, RC2, and RC6) at pH 2-6 were positively correlated (R² > 0.71) with phenol C. Spectral analysis showed that there was no obvious complexation between Cr(VI) and the six organic matter fractions at pH 6, and thus the reduction of Cr(VI) was negligible, but solution pH could affect the accessibility of organic molecules to Cr(VI) and thus influence Cr(VI) reduction.

Quantifying source contributions to indoor PM_2.5 levels by indoor PM_2.5 sources has been limited by the costs associated with chemical speciation analyses of indoor PM_2.5 samples. Here, we propose a new methodology to estimate this contribution. We applied FUzzy SpatioTemporal Apportionment (FUSTA) to a database of indoor and outdoor PM_2.5 concentrations in school classrooms plus surface meteorological data to determine the main spatiotemporal patterns (STPs) of PM_2.5. We found four dominant STPs in outdoor PM_2.5, and we denoted them as regional, overnight mix, traffic, and secondary PM_2.5. For indoor PM_2.5, we found the same four outdoor STPs plus another STP with a distinctive temporal evolution characteristic of indoor-generated PM_2.5. Concentration peaks were evident for this indoor STP due to children's activities and classroom housekeeping, and there were minimum contributions on sundays when schools were closed. The average indoor-generated estimated contribution to PM_2.5 was 5.7 μg m^-3, which contributed to 17% of the total PM_2.5, and if we consider only school hours, the respective figures are 8.1 μg m^-3 and 22%. A cluster-wise indoor-outdoor PM_2.5 regression was applied to estimate STP-specific infiltration factors (F_inf) per school. The median and interquartile range (IQR) values for F_inf are 0.83 [0.7-0.89], 0.76 [0.68-0.84], 0.72 [0.64-0.81], and 0.7 [0.62-0.9], for overnight mix, secondary, traffic, and regional sources, respectively. This cost-effective methodology can identify the indoor-generated contributions to indoor PM_2.5, including their temporal variability.

Correction for 'How do ecosystem service functions affect ecological health? Evidence from the Yangtze River Economic Belt in China' by Wei Wang et al., Environ. Sci.: Processes Impacts, 2024, https://doi.org/10.1039/D4EM00296B.

The interaction between dissolved organic matter (DOM) and iron minerals has a significant effect on its stabilization and preservation in the environment. In this study, iron minerals with different crystal forms (crystalline goethite and amorphous ferrihydrite) were selected to investigate the photochemical transformation process for DOM immobilized on iron minerals under simulated sunlight irradiation at the molecular scale with the help of Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS). The results showed that a total of 7148 molecules were detected in alkaline-extractable sedimentary DOM, of which 38.8% and 36.2% were adsorbed by ferrihydrite and goethite, respectively, while there was no selectivity difference between the two iron minerals in terms of DOM adsorption. After simulated sunlight irradiation, the DOM adsorbed by goethite was significantly degraded (58.3%), in which the H/C ratio of the mineral-immobilized DOM increased and the O/C ratio decreased, and the photodegradation primarily involved DOM molecules with high Kendrick mass defect (KMD) values. The results confirmed that the iron mineral types play an important role in the transportation and transformation of DOM, which adds to the understanding of the fate of DOM in natural environments.

This study uses mobile monitoring to gain a better understanding of particulate matter (PM) sources in two areas of Central and Outer London, UK. We find that, unlike emissions of nitrogen oxides (NO + NO₂ = NO_x), which are elevated in Central London due to the high number of diesel vehicles and congestion, fine particulate matter (PM_2.5) emissions are well-controlled. This finding provides evidence for the effectiveness of vehicle particulate filters, supporting the view that their widespread adoption has mitigated PM_2.5 emissions, even in the highly dieselized area of Central London. However, mobile monitoring also reveals infrequent elevated PM_2.5 concentrations caused by malfunctioning vehicles. These events were confirmed through simultaneous measurements of PM_2.5 and sulfur dioxide (SO₂), the latter being a strong tracer of engine lubricant combustion. A single event from a gasoline car, representing just 0.15% of the driving distance in Outer London, was responsible for 7.4% of the ΔPM_2.5 concentration above background levels, highlighting the ongoing importance of addressing high-emission vehicles. In a novel application of mobile monitoring, we demonstrate the ability to identify and quantify non-vehicular sources of PM. Among the sources unambiguously identified are construction activities, which result in elevated concentrations of coarse particulate matter (PM_coarse = PM₁₀ - PM_2.5). The mobile measurements clearly highlight the spatial extent of the influence of such sources, which would otherwise be difficult to determine. Furthermore, these sources are shown to be weather-dependent, with PM_coarse concentrations reduced by 62.1% during wet conditions compared to dry ones.

Per and polyfluoroalkyl substances (PFAS) are ubiquitous in the indoor environment, resulting in indoor exposure. However, a dearth of concurrent indoor multi-compartment PFAS measurements, including air, has limited our understanding of the contributions of each exposure pathway to residential PFAS exposure. As part of the Indoor PFAS Assessment (IPA) Campaign, we measured 35 neutral and ionic PFAS in air, settled dust, drinking water, clothing, and on surfaces in 11 North Carolina homes. Ionic and neutral PFAS measurements reported previously and ionic PFAS measurements reported herein for drinking water (1.4-34.1 ng L^-1), dust (202-1036 ng g^-1), and surfaces (4.1 × 10^-4-1.7 × 10^-2 ng cm^-2) were used to conduct a residential indoor PFAS exposure assessment. We considered inhalation of air, ingestion of drinking water and dust, mouthing of clothing (children only), and transdermal uptake from contact with dust, air, and surfaces. Average intake rates were estimated to be 3.6 ng kg^-1 per day (adults) and 12.4 ng kg^-1 per day (2 year-old), with neutral PFAS contributing over 80% total PFAS intake. Excluding dietary ingestion, which was not measured, inhalation contributed over 65% of PFAS intake and was dominated by neutral PFAS because fluorotelomer alcohol (FTOH) concentrations in air were several orders of magnitude greater than ionic PFAS concentrations. Perfluorooctanoic acid (PFOA) intake was 6.1 × 10^-2 ng kg^-1 per day (adults) and 1.5 × 10^-1 ng kg^-1 per day (2 year-old), and biotransformation of 8 : 2 FTOH to PFOA increased this PFOA body burden by 14% (adults) and 17% (2 year-old), suggesting inhalation may also be a meaningful contributor to ionic PFAS exposure through biotransformation.

Dissolved organic matter (DOM) released from biochar may impact antibiotic mobility and environmental fate in subsurface environments. Here, DOM samples derived from biochars (BDOM) generated by pyrolyzing corn straw at 300, 450, and 600 °C were employed to elucidate the mobility characteristics of these organic substances and their influences on the transport of sulfamerazine (SMZ, a typical sulfonamide antibiotic) in soil porous media. The results demonstrated that BDOM produced at a lower pyrolysis temperature exhibited greater mobility owing to the weaker hydrophobic and H-bonding interactions between BDOM and soil particles. Additionally and importantly, BDOM facilitated the promotion of SMZ mobility owing to the increased electrostatic repulsion between SMZ^- forms and soil grains, the steric hindrance effect induced by the deposition of organic matter, and the competitive retention between SMZ molecules and BDOM. Meanwhile, the promotion effects of BDOM enhanced with improving pyrolysis temperature owing to the promoted deposition of organic matter on soil surfaces and the strengthened electrostatic repulsion. Moreover, the facilitated effects of BDOM on SMZ mobility declined as the solution pH values were raised from 5.0 to 9.0 or the flow rate increased from 0.18 to 0.51 cm min^-1. This trend was due to decreased deposition competition and the steric effect caused by decreased retention of BDOM on soil particles. Furthermore, the cation-bridging effect emerged as an important mechanism contributing to the promotion effects of BDOM when the solution contained divalent cations (Cu²⁺ or Ca²⁺). Moreover, a two-site non-equilibrium model was used to interpret the controlling mechanisms for the effects of BDOM on the transport of SMZ. Findings from this work highlight that biochar-derived dissolved organic matter can remarkably affect the environmental behaviors of antibiotics in aquatic environments.