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Abstract: Hexabromocyclododecanes (HBCDs) and tris (2,3-dibromopropyl) isocyanurate (TBC) are both brominated flame retardants, and have been used throughout the world with subsequent concern for potential environment pollution. Here we describe the development of a method for the simultaneous determination of TBC and HBCD diastereoisomers in environmental matrices by high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). The method recovery ranged from 81% to 93% and limits of detections (LODs) on column were 4.3pg, 0.5pg, 0.4pg, 0.3pg for TBC, α-HBCD, β-HBCD, and γ-HBCD, respectively, which showed high sensitivity compared to previous published methods. Compared to electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI) was found to be a more sensitive, effective ionization mode for determination of HBCDs. This novel method was further validated by analyzing TBC and HBCDs in biotic and abiotic samples. The concentration ranges of TBC, α, β, γ-HBCD in sediment samples were 136.1–5884.6ng/g, 9.0–1079.6ng/g, 1.0–1161.7ng/g, and 65.4–3964.2ng/g, respectively. The concentration range for TBC, α-HBCD, β-HBCD, and γ-HBCD in common carp samples were 51.1–1899ng/g, 21.6–1338ng/g,

Mass spectrometry data may be affected by random noise and baseline drift due to experimental instruments and conditions, posing significant challenges for detecting spectral peaks, particularly when identifying weak and separating overlapping peaks. To increase the sensitivity and enhance the resolution, we propose a mass spectral peak detection algorithm that integrates resolution enhancement and image segmentation. Initially, the extended Mexican hat wavelet is proposed by integrating the peak sharpening method with its wavelet. This approach accurately transforms mass spectra into wavelet space using the continuous wavelet transform. Subsequently, the triangular single-peak thresholding method, a more suitable threshold segmentation approach for spectral analysis, is introduced to identify ridges in the two-dimensional wavelet space. Compared to traditional Otsu and its improved variants, long-tailed single-peaked histograms are more effectively processed by this method with lower computational complexity, enabling faster identification of segmentation thresholds and image segmentation. Ultimately, peak positions are determined by utilizing ridge and valley lines in wavelet space along with the original spectrum. To evaluate the performance of the peak recognition algorithm, two metrics are introduced: the receiver operating characteristic (ROC) curve and the balanced F score (F1 score). When compared to multi-scale peak detection (MSPD), continuous wavelet transform and image segmentation (CWT-IS), the developed approach is more suitable for weak and highly overlapping peaks. The robustness and practicality of the method are verified through peak detection using matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectra. [ABSTRACT FROM AUTHOR]

Rationale: Ion mobility spectrometry (IMS), as a promising analytical tool, has been widely employed in the structural characterization of biomolecules. Nevertheless, the inherent limitation in the structural resolution of IMS frequently results in peak overlap during the analysis of isomers exhibiting comparable structures. Methods: The radial basis function (RBF) neural network optimization algorithm based on dynamic inertial weight particle swarm optimization (DIWPSO) was proposed for separating overlapping peaks in IMS. The RBF network structure and parameters were optimized using the DIWPSO algorithm. By extensively training using a large dataset, an adaptive model was developed to effectively separate overlapping peaks in IMS data. This approach successfully overcomes issues related to local optima, ensuring efficient and precise separation of overlapping peaks. Results: The method's performance was evaluated using experimental validation and analysis of overlapping peaks in the IMS spectra of two sets of isomers: 3′/6′‐sialyllactose; fructose‐6‐phosphate, glucose‐1‐phosphate, and glucose‐6‐phosphate. A comparative analysis was conducted using other algorithms, including the sparrow search algorithm, DIWPSO algorithm, and multi‐objective dynamic teaching‐learning‐based optimization algorithm. The comparison results show that the DIWPSO‐RBF algorithm achieved remarkably low maximum relative errors of only 0.42%, 0.092%, and 0.41% for ion height, mobility, and half peak width, respectively. These error rates are significantly lower than those obtained using the other three algorithms. Conclusions: The experimental results convincingly demonstrate that this method can adaptively, rapidly, and accurately separate overlapping peaks of multiple components, improving the structural resolution of IMS. [ABSTRACT FROM AUTHOR]

In urban areas, green infrastructure (GI) has been widely developed utilizing different types of engineered soil to enhance ecosystem functions to interact with soil dissolved organic matter (DOM). However, there remains a lack of urban studies that have examined the link between GI features and soil DOM. This study, which was conducted in a typical heavily industrialized and urbanized area (Ningbo City, East China), aimed to characterize the chemical variation and composition of DOM in the engineered soil of four GI types (enhanced tree tips, ETP; street-side infiltration swales, SSIS; vegetated swales, VS; urban forests, UF). The results showed that soil organic carbon varies among the four GI types with significantly lower content in SSIS and ETP compared to VS and UF. Smaller variation was observed in the water-soluble organic carbon (WSOC) content, with UF having significantly higher content than ETP. Three humic-like substances and one protein-like substance were derived using the parallel factor analysis (PARAFAC) model. These fluorescent compositions and their spectral parameters displayed specific distributions among GI features with VS having the highest proportion of humic-like substances (C1) and the lowest proportion of protein-like substances (C4). The distribution of spectral indices indicated terrigenous sources of DOM in these GI engineered soils. Significant positive correlations were found between protein-like substances and the population density and nightlight index, while negative correlations were found between humic-like substances (C1) and these two indices. These results demonstrate significant human disturbance of the chemical composition and characteristics of GI features. Our findings suggest that the overall design and management of GI features have a fundamental influence on soil DOM that is vital for carbon cycling in urban ecosystems. Unlabelled Image • Soil DOM in different green infrastructure features was characterized by EEM-PARAFAC. • SOC and WSOC content varied with green infrastructure types. • Green infrastructure shape fluorescent components and spectral characteristics of DOM • Human activities affect DOM quantity and fluorescence characteristics in GI soils. [ABSTRACT FROM AUTHOR]

Surface ozone (O 3 ) is a harmful air pollutant that has attracted growing concern in China. In this study, the mixing ratios of O 3 and nitrogen oxides (NO x ) at three different sites (urban, suburban and rural) of Ningbo were continuously measured to investigate the spatiotemporal characteristics of O 3 and its relationships with environmental variables. The diurnal O 3 variations were characterized by afternoon maxima (38.7–53.1 ppb on annual average) and early morning minima (11.7–26.2 ppb) at all the three sites. Two seasonal peaks of O 3 were observed in spring (April or May) and autumn (October) with minima being observed in winter (December). NO x levels showed generally opposite variations to that of O 3 with diurnal and seasonal maxima occurring in morning/evening rush-hours and in winter, respectively. As to the inter-annual variations of air pollutants, generally decreasing and increasing trends were observed in NO and O 3 levels, respectively, from 2012 to 2015 at both urban and suburban sites. O 3 levels were positively correlated with temperature but negatively correlated with relative humidity and NO x levels. Significant differences in O 3 levels were observed for different wind speeds and wind directions ( p < 0.001). O 3 levels varied non-linearly with wind speed ranges with an increasing trend within 4 m/s. Higher mixing ratio of O 3 was observed for wind blowing from the sea, which indicates that the coastal air mass might carry more O 3 . A decreasing trend in O 3 levels was observed from weekdays to weekends at all the three sites. As to the spatial variation, higher levels of O 3 were observed at the suburban and rural sites where less O 3 was depleted by NO titration. In contrast, the urban site exhibited lower O 3 but higher NO x levels due to the influence of traffic emissions. Larger amplitudes of diurnal and monthly O 3 variations were observed at the suburban site than those at the urban and rural sites. In general, the O 3 levels at the non-urban sites were more affected by the background transport, while both the local and regional contributions played roles in urban O 3 variations. The annual average O 3 mixing ratios (22.7–37.7 ppb) in Ningbo were generally similar to those of other regions around the world. However, the recommended air quality standards for O 3 were often exceeded during warm seasons, which could be a potential threat to both local population and plant growth. [ABSTRACT FROM AUTHOR]

Abstract: Hexabromocyclododecane (HBCD) is a high production volume brominated flame retardant (BFR) which has been of increasing environmental and public health concern due to its potential environmental persistency, bioaccumulation and toxicity. Tris-(2,3-dibromopropyl) isocyanurate (TBC) is another BFR which has recently been found in environmental matrices near a manufacturing plant, but its production volume and environmental distribution is currently not well known. This study was conducted to investigate the presence and distribution of these two BFRs in farm soils at a region in southeast Beijing. Total HBCD levels ranged from 0.17 to 34.5ngg−1 on a dry weight basis (dw) with a median level of 2.97ngg−1 dw. The composition profile of HBCD diastereoisomers was, on average, 28%, 13% and 59% for α-, β- and γ-HBCD, respectively. Detection frequency of TBC was only 25% in 2010 but was detected in all soil samples in 2011, and the median level was 0.19ngg−1 dw with the range between below detection limit to 1.62ngg−1 dw. There were no significant differences of HBCD and TBC levels among different irrigation sources in the region. The soil HBCD and TBC levels in samples collected in 2011 were significantly higher than in 2010. The increasing short-term temporal levels in farm soil might be due to the rapid urbanization in this region or could also reflect the increasing usage of HBCD and TBC after the phase out of other BFRs. [Copyright &y& Elsevier]