Ozone (O₃) is a potent oxidant associated with adverse health effects. Low-cost O₃ sensors, such as metal oxide (MO) sensors, can complement regulatory O₃ measurements and enhance the spatiotemporal resolution of measurements. However, the quality of MO sensor data remains a challenge. The University of Utah has a network of low-cost air quality sensors (called AirU) that primarily measures PM₂.₅ concentrations around the Salt Lake City valley (Utah, U.S.). The AirU package also contains a low-cost MO sensor ($8) that measures oxidizing/reducing species. These MO sensors exhibited excellent laboratory response to O₃ although they exhibited some intra-sensor variability. Field performance was evaluated by placing eight AirUs at two Division of Air Quality (DAQ) monitoring stations with O₃ federal equivalence methods for one year to develop long-term multiple linear regression (MLR) and artificial neural network (ANN) calibration models to predict O₃ concentrations. Six sensors served as train/test sets. The remaining two sensors served as a holdout set to evaluate the applicability of the new calibration models in predicting O₃ concentrations for other sensors of the same type. A rigorous variable selection method was also performed by least absolute shrinkage and selection operator (LASSO), MLR and ANN models. The variable selection indicated that the AirU’s MO oxidizing species and temperature measurements and DAQ’s solar radiation measurements were the most important variables. The MLR calibration model exhibited moderate performance (R² = 0.491), and the ANN exhibited good performance (R² = 0.767) for the holdout set. We also evaluated the performance of the MLR and ANN models in predicting O₃ for five months after the calibration period and the results showed moderate correlations (R²s of 0.427 and 0.567, respectively). These low-cost MO sensors combined with a long-term ANN calibration model can complement reference measurements to understand geospatial and temporal differences in O₃ levels.

Poly/perfluoroalkyl substances (PFASs) have some water solubility so that they are more liable to enter surface water. A comprehensive analysis method was established to analyze 17 classes of 58 PFASs in surface water by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) after automated solid phase extraction (SPE). The method showed acceptable recoveries and precision with recoveries of 60%–130% and RSD less than 30% with a few exceptions, and method detection limits (MDLs) of 0.004 ng/L-2.0 ng/L. It was investigated the surface water around Zhangjiang High-Technology Park in Shanghai. The concentration of ∑PFASs ranged from 115 ng/L to 600 ng/L. The main pollutant was perfluoro-3-methylheptanoic acid (P3MHpA), which is isopropyl isomer of perfluorooctanoic acid (PFOA), accounting 41.6% of ∑PFASs. It was detected in all samples and its level was far higher than that of PFOA with the maximum of 432 ng/L determined surrounding integrated circuits company. Short-chain perfluorocarboxylic acids (PFCAs) and PFOA were also major constituents accounting for 39.9% of ∑PFASs. Perfluorosulfonic acid (PFSAs (C₄, ₆, ₈)) were detected in all samples, while most concentrations were below 10 ng/L. In addition, 1H,1H,2H,2H-perfluorooctane sulfonate (6:2) (6:2 FTS), 2,3,3,3-tetrafluoro-2-(1,1,2,2,3,3,3-heptafluoropropoxy)-propanoic acid (HFPO-DA) and 9-chlorohexadecafluoro-3-oxanonane-sulfonate (9Cl-PF3ONS) were also detected in all samples at low level. Long chain PFCAs and PFSAs and other classes of PFASs were also detected with low levels and/or low frequencies. The level of PFASs shows an increasing trend in surface water in Shanghai. The whole risk is low for residents from water exposure, while it should cautious to the emission of P3MHpA from integrated circuits and its potential risk.

The neonicotinoid imidacloprid (IMI) is one of the most extensively applied neuro-active insecticides worldwide and continues to enter surface waters in many countries despite a recent ban for outdoor use in the EU. Yet little is known about ecotoxicological effects on non-target benthic freshwater species exposed to environmentally relevant concentrations of IMI and its marketed products. The aim of the present study was to narrow this gap by assessing effects of pure IMI and its commercial formulation Confidor® on the aquatic oligochaete Lumbriculus variegatus, a key species in freshwater sediments. To this end, we determined dose-response relationships in 24 h toxicity tests, bioconcentration during 24 h and 5 d of exposure to 0.1, 1 and 10 μg IMI L⁻¹, and physiological stress responses by measuring glutathione S-transferase, glutathione reductase and catalase activity in the same conditions. Maximum neonicotinoid concentrations reported from the field were lethal to L. variegatus within 24 h (LC₅₀ of 65 and 88 μg IMI L⁻¹ in pure form and as active ingredient of Confidor®, respectively). At sub-lethal exposure concentrations, tissue content of IMI significantly increased with exposure time. The observed bioconcentration factors (BCFs) were far above the water octanol coefficient (KOW), indicating a potentially large underestimation of IMI bioaccumulation when based on KOW. Activities of biotransformation and antioxidant enzymes indicated attempts of L. variegatus to counter xenobiotic-triggered oxidative stress to very low IMI and Confidor® concentrations. Together, our data add significantly to growing evidence that the continued proliferation of neonicotinoids require increased efforts in environmental risk assessment, especially in view of species-specific differences in sensitivities to the insecticide and possibly to additives of commercial formulations.

Previous studies have associated the risk of autism spectrum disorder (ASD) with increased exposures to metals and metalloids such as arsenic. In this study, we used an animal-to-human translational strategy to identify key molecular changes that potentially mediated the effects of arsenic exposures on ASD development. In a previously established rat model, we have induced autistic behaviors in rat pups with gestational arsenic exposures (10 and 45 μg/L As₂O₃ in drinking water). Neuronal apoptosis and the associated epigenetic dysregulations in frontal cortex were assayed to screen potential mediating pathways, which were subsequently validated with qPCR, western blotting, and immunohistochemistry analyses. Furthermore, the identified pathway, along with serum levels of 26 elements including arsenic, were characterized in a case-control study with 21 ASD children and 21 age-matched healthy controls. In animals, we found that arsenic exposures caused difficulties of social interaction and increased stereotypic behaviors in a dose-dependent manner, accompanied by increased neuronal apoptosis and upregulation of Hipk2-p53 pathway in the frontal cortex. In humans, we found that serum levels of Hipk2 and p53 were 24.7 (95%CI: 8.5 to 43.4) % and 23.7 (95%CI: 10.5 to 38.5) % higher in ASD children than in healthy controls. ASD children had significantly higher serum levels of 15 elements, among which arsenic, silicon, strontium, and vanadium were positively associated with both Hipk2 and p53. Results from both the rat arsenic exposure and human case-control studies suggest a likely role of Hipk2-p53 pathway in ASD development induced by exposures to environmental pollutants such as arsenic.

The microplastic particles with 29 pyrolyzate compounds of marine water samples from the seashore locations in Cape Town, South Africa were analysed using Pyrolysis- GC-TOF-MS. The mass spectra data documented the presence of various chemical groups that include alkanes, alkenes, dienes, fatty acids and esters, biphenyl and benzene (along with derivatives). Out of 16 identified polymers in the study area, polythene (PE) was the dominant in six out of seven locations with 87.5% followed by polyethylene terephthalate (PET) and polyvinylchloride (PVC) in five (71.4%) and four (57.1%) out of seven locations respectively. The other constituent polymers of microplastics identified through pyrolyzates were polystyrene (PS), polyamide 12 (PA-12) polyacrylic acid (PAA) and ethyl vinyl acetate (EVA) copolymer. The microplastic samples contained six additives predominantly in the family of fatty acid esters and nine plasticizers from alcohols, carboxylic esters and acids. The base peaks of m/z 41, 43, 55, 57, 69, 73, 91, 102, 105, 127 and 154 were characterized respectively with the fragmented species of C₃H₅⁺, C₃H₇⁺, C₄H₇⁺, C₄H₉⁺, C₅H₉⁺, C₃H₅O₂⁺, C₇H₇⁺, C₃H₁₀O₂⁺(McLafferty ion), C₈H₉⁺, C₈H₁₅O⁺ and C₁₂H₁₀⁺. Accordingly to Globally Harmonized System (GHS) of hazard classification, about 27.4% of pyrolyzates are Irritants, 31.4% of pyrolyzates found to be Irritants along with other hazards such as Flammable, Compressed Gas, Environmental Hazard, Corrosive, Health Hazard, Acute Toxicity and Allergy. About 41.2% of the pyrolyzates are not classified under the Irritant category. Characterizations of the plastic microparticles from the seven seashore locations such as FTIR, SEM with EDX and TGA were also done and discussed to understand the functional groups, surface morphology with elemental composition and stability respectively of the polymeric microparticles.

Soil salinity is a global threat to the environmental sustainability, in particular to the developing countries due to their limited resources for soil reclamation. In a greenhouse pot experiment, Pennisetum giganteum, was investigated for its tolerance to salt stress and simultaneous phytoremediation capability. 4 weeks post-germination, NaCl (10, 50, 150, 250, 350, 450 and 550 mM) and tap water (control) was applied after every 2 consecutive days for two weeks in a completely randomized design and their effects were established in the growth and physico-chemical aspects of these plants. Our results indicated that P. giganteum withstood high salt stress (with 550 mM NaCl tolerance threshold level). Interestingly, the plants grown under saline conditions had higher biomass yield when compared to the control. Furthermore, the antioxidant activity and proline content of plants under saline conditions were significantly (p < 0.05) higher than those of control plants, indicating their adaptability to high salt stress. Biochemical analysis such as chlorophyll contents, total soluble sugar, total phenol and protein contents revealed considerable differences between plants grown under higher NaCl stress compared to the control conditions. Additionally, significantly different ionic flux along with high K⁺/Na⁺ ratio was observed in plants grown under a range of saline conditions. The results obtained are therefore of value to indicate P. giganteum an eco-friendly alternate source for the phytoremediation of saline soils and may be used as base for future research on this plant. Effective strategies need to be adopted with this plant to reclaim saline-degraded as well as marginal soils.

The emission of polychlorinated dibenzo-p-dioxins and -furans (PCDD/F) from full-scale municipal solid waste incinerators (MSWI) is harmful to human and environmental health. This study analyzes the effect of different units of an air pollution control devices (APCDs), i.e. the semi-dry scrubber, fabric filter (FF), selective catalytic reduction (SCR), and wet scrubber (WS), on the removal characteristics and gas- and solid-phase distributions of PCDD/F in MSWI flue gas. APCDs reduce PCDD/F concentrations from 24.9 ng Nm⁻³ to 0.979 ng Nm⁻³ (2.16 ng I-TEQ Nm⁻³ to 0.0607 ng I-TEQ Nm⁻³), with a total removal efficiency (RE) of 96.1% (97.2% I-TEQ). Specifically, APCDs remove more than 95% of both gas- and solid-phase PCDD/F. The FF coupled with active carbon injection (FF + ACI) substantially reduces both gas- and solid-phase PCDD/F concentrations with an RE of 97.2% (98.7% I-TEQ). Additionally, FF + ACI exhibits a better RE of PCDF (98.9%) than PCDD (94.6%) and leads to PCDD congeners dominating the gas-phase. Both desorption and destruction of PCDD/F occur in the SCR, which favors removal of gas-phase PCDD/F but increases solid-phase PCDD/F. Therefore, SCR only decreases PCDD/F with a low RE of 27.6% (16.9% I-TEQ). However, SCR reduces NOₓ with a high RE of 82.3%, which could inhibit the RE of PCDD/F because of their different reaction mechanisms. WS increases PCDD/F in both the gas and solid-phase by 1.95 times (2.57 times for I-TEQ) due to the memory effect, which typically increases the total mass concentration of PCDD/F and the proportions of lower-chlorinated gas-phase PCDD/F. Migration of gas- and solid-phase PCDD/F are also analyzed according to temperature. The results of this study can contribute to the optimized design of industrial APCDs for controlling PCDD/F emissions from MSWI.

Organophosphate esters (OPEs) are widely used as flame retardants, plasticizers and defoamers and their exposure are likely associated with a number of adverse effects in humans. In this study, tris(chloroethyl) phosphate and thirteen OPE metabolites including six hydroxylated OPEs (HO-OPEs) were analyzed in 46 urine samples, collected from 8 provinces located across different regions in China. 1-Hydroxy-2-propyl bis(1-chloro-2-propyl) phosphate (BCIPHIPP) and 2-hydroxyethyl bis(2-butoxyethyl) phosphate (BBOEHEP) were major metabolites of their parent compounds with detection frequencies of 54.3%–89.1%, which were all higher than their corresponding OPE diesters (2.2%–6.5%). The urine-based estimated daily intake (EDI) of OPEs ranged from 0.06 ng/kg·bw for tris(2-butoxyethyl) phosphate (TBOEP) to 273 ng/kg·bw for 2-ethylhexyl phenyl phosphate. Analyzed with concentrations in paired dust samples, dust exposure to OPEs and their diesters may explain 0.28%–23.8% of the urine-based EDI of OPEs and the contribution of dust TBOEP was the highest. Although direct exposure to OPE diesters in dust showed a minor contribution, their intake via food and drinking water may account for a larger portion of urinary OPE metabolites. Overall, the hazard quotients of four OPEs indicated no immediate exposure risk for the investigated Chinese residents but the cumulative and long-term chronic effects involving exposure to other OPEs and OPE diesters are worth further concerns.

Isoprene, formaldehyde and acetaldehyde are important reactive organic compounds which strongly impact atmospheric oxidation processes and formation of tropospheric ozone. Monsoon meteorology and the topography of Himalayan foothills cause surface emissions to get rapidly transported both horizontally and vertically, thereby influencing atmospheric processes in distant regions. Further in monsoon, Indo-Gangetic Plain is a major rice growing region of the world and daytime hourly ozone can frequently exceed phytotoxic dose of 40 ppb O₃. However, the sources and ambient variability of these compounds which are potent ozone precursors are unknown. Here, we investigate the sources and photochemical processes driving their emission/formation during monsoon season from a sub-urban site at the foothills of the Himalayas. The measurements were performed in July, August and September using a high sensitivity mass spectrometer. Average ambient mixing ratios (±1σ variability) of isoprene, formaldehyde, acetaldehyde, and the sum of methyl vinyl ketone and methacrolein (MVK+MACR), were 1.4 ± 0.3 ppb, 5.7 ± 0.9 ppb, 4.5 ± 2.0 ppb, 0.75 ± 0.3 ppb, respectively, and much higher than summertime values in May. For isoprene these values were comparable to mixing ratios observed over tropical forests. Surprisingly, despite occurrence of anthropogenic emissions, biogenic emissions were found to be the major source of isoprene with peak daytime isoprene driven by temperature (r ≥ 0.8) and solar radiation. Photo-oxidation of precursor hydrocarbons were the main sources of acetaldehyde, formaldehyde and MVK+MACR. Ambient mixing ratios of all the compounds correlated poorly with acetonitrile (r ≤ 0.2), a chemical tracer for biomass burning suggesting negligible influence of biomass burning during monsoon season. Our results suggest that during monsoon season when radiation and rain are no longer limiting factors and convective activity causes surface emissions to be transported to upper atmosphere, biogenic emissions can significantly impact the remote upper atmosphere, climate and ozone affecting rice yields.

The present study proposes a maize sprouts hydroponic growth model to evaluate the As, Cd, Cr and Pb translocation from multinutrient fertilizer and to do speciation of As and Cr in this fertilizer and As in parts of plant in order to predict their phytoavailability. X-ray absorption near edge structure (XANES) was employed to speciate As and Cr directly on fertilizer solid sample. Arsenate (Asⱽ) and a solid solution of FeCrO₃ were the major species identified in the samples. The sprouts were hydroponically cultivated in water, fertilizer slurry and fertilizer extract media. Concentrations of As, Cd and Pb measured on leaves of maize sprouts ranged from 0.061 to 0.31 mg kg⁻¹, whereas Cr was not translocated to the aerial parts of sprouts. High performance liquid chromatographic with inductively coupled plasma mass spectrometry (HPLC-ICP-MS) analysis was used to determine As speciation in maize sprouts, as well as in the fertilizer extracts and slurries. Arsenate was the only species identified in the initial fertilizer extract and this information is in agreement with the XANES results. However, the reduction of arsenate to arsenite was observed in extracts and slurries collected after sprout growth, probably due to the action of exudates secreted by plant roots. Arsenite was the predominant species identified in sprouts, the high phosphate concentration in the medium may have contributed to reduce arsenate phytoavailability.