Hourly PM₂.₅ speciation data have been widely used as an input of positive matrix factorization (PMF) model to apportion PM₂.₅ components to specific source-related factors. However, the influence of constant source profile presumption during the observation period is less investigated. In the current work, hourly concentrations of PM₂.₅ water-soluble inorganic ions, bulk organic and elemental carbon, and elements were obtained at an urban site in Nanjing, China from 2017 to 2020. PMF analysis based on observation data during specific pollution (firework combustion, sandstorm, and winter haze) and emission-reduction (COVID-19 pandemic) periods was compared with that using the whole 4-year data set (PMFwₕₒₗₑ). Due to the lack of data variability, event-based PMF solutions did not separate secondary sulfate and nitrate. But they showed better performance in simulating average concentrations and temporal variations of input species, particularly for primary source markers, than the PMFwₕₒₗₑ solution. After removing event data, PMF modeling was conducted for individual months (PMFₘₒₙₜₕ) and the 4-year period (PMF₄₋yₑₐᵣ), respectively. PMFₘₒₙₜₕ solutions reflected varied source profiles and contributions and reproduced monthly variations of input species better than the PMF₄₋yₑₐᵣ solution, but failed to capture seasonal patterns of secondary salts. Additionally, four winter pollution days were selected for hour-by-hour PMF simulations, and three sample sizes (500, 1000, and 2000) were tested using a moving window method. The results showed that using short-term observation data performed better in reflecting immediate changes in primary sources, which will benefit future air quality control when primary PM emissions begin to increase.

This study modified a passive sampling technique similar to the US EPA Method 325 A/B method but extended to include more toxic volatile organic compounds (VOCs) under varied climate conditions to enhance field applicability. A mixing chamber was built to determine uptake rates (Us) for the target compounds. It was found that the Us of 27 air toxics previously reported in the literature agreed reasonably well with our findings within 18%, thus proving the chamber's integrity. To broaden the compound coverage, both Carbopack X and Carboxen 569 were studied for a suite of toxic VOCs to meet stringent quality control (QC) criteria of correlation coefficients (R-square), method detection limits (MDL), back diffusion (BD), storage stability, as well as a wide range of climate conditions in temperature and humidity. After excluding the species that failed to pass any of the QC criteria, Carbopack X was found to fit 50 air toxics, whereas Carboxen 569 held 37. After excluding the overlapped species, 61 toxic VOCs can be determined with robust Us for a broad range of climate conditions when the two sorbents are used in pairs. A one-week field measurement was conducted to compare with the online thermal desorption gas chromatography-mass spectrometry (TD-GC-MS) with hourly data resolution. The field passive sampling showed comparable results to the means of the online hourly measurements, despite the high variability of selected target compounds, such as toluene from 0.3 ppbv as the 5th percentile to the maximum of about 80 ppbv. Passive sampling clearly demonstrated the ability to smooth out concentration variability and thus the time-averaging strength of toxic VOCs, revealing its ideal role as an exposure monitor over time. The passive sampling method can be more desired than active sampling or online methods when the aim is simply the knowledge of prolonged time-averaged concentrations.

We investigated the concentrations and profiles of 15 siloxanes (four cyclic siloxanes, D₄–D₇; 11 linear siloxanes, L₄–L₁₄), four synthetic musks (two polycyclic musks, HHCB and AHTN; two nitro musks, MX and MK), and HHCB-lactone, in 158 personal care products marketed in China. Siloxanes were detected in 88% of the samples analyzed, at concentrations as high as 52.6 mg g⁻¹; Linear siloxanes were the predominant compounds. Among synthetic musks, more than 80% of the samples contained at least one of these compounds, and their total concentrations were as high as 1.02 mg g⁻¹. HHCB was the predominant musk in all of the samples analyzed, on average, accounting for 52% of the total musk concentrations. Based on the median concentrations of siloxanes and musks and the average daily usage amounts of consumer products, dermal exposure rates in adults were calculated to be 3.69 and 3.38 mg d⁻¹ for siloxanes and musks, respectively.

Mycotoxin is toxic secondary metabolite formed by certain filamentous fungi. This toxic compound can enter the food chain through contamination of food (e.g., by colonization of toxigenic fungi on food). In light of the growing concerns on the health hazards posed by mycotoxins, it is desirable to develop reliable analytical tools for their detection in food products in both sensitive and efficient manner. For this purpose, the potential utility of molecularly imprinted polymers (MIPs) has been explored due to their meritful properties (e.g., large number of tailor-made binding sites, sensitive template molecules, high recognition specificity, and structure predictability). This review addresses the recent advances in the application of MIPs toward the sensing of various mycotoxins (e.g., aflatoxins and patulin) along with their fabrication strategies. Then, performance evaluation is made for various types of MIP- and non-MIP-based sensing platforms built for the listed target mycotoxins in terms of quality assurance such as limit of detection (LOD). Further, the present challenges in the MIP-based sensing application of mycotoxins are discussed along with the future outlook in this research field.

Airborne microplastics (MPs) have recently drawn the attention of the scientific community due to their possible human inhalation risk. Indoor environments are of relevance as people spend about 90% of their time indoors. This study evaluated MPs concentrations in three indoor environments: houses, public transport and working places, which are representative of urban life. Sampling involved the collection of airborne particulate matter on nylon 20 μm pore size filters. Samples were first visually inspected, and particles were characterized (colour, length or area). Polymer identification was performed through μFTIR analysis. Working conditions were controlled to guarantee quality assurance and avoid background contamination. Limits of detection, recovery tests and repeatability were performed with home-made polyethylene (PE), polypropylene (PP), and polystyrene (PS) standards. The highest average MP concentrations were found in buses (17.3 ± 2.4 MPs/m³) followed by 5.8 ± 1.9 MPs/m³ in subways, 4.8 ± 1.6 MPs/m³ in houses, and 4.2 ± 1.6 MPs/m³ in the workplaces. Polyamide, PA (51%), polyester PES (48%) and PP (1%) were the polymers identified and most common in personal care products and synthetic textiles. Most of these polymers were below 100 μm in size for both fibres (64 ± 8%) and fragments (78 ± 11%). The frequency of MP particles in our study decreased with increasing size, which points to their potential as an inhalation hazard.

Particulate matter data obtained from the national air quality monitoring network in China has become an essential and critical data source for many current and forthcoming studies as well as the formulation and implementation of air pollution regulatory policies on particulate matter (PM2.5 and PM10). However, the quality control of this data is dubitable and can affect many future studies and policies. This study identifies and elucidates two significant quality control issues with the data. They are PM2.5 levels exceeding concurrent co-located PM10 levels and the registration of same concentrations for consecutive hours at some stations. Future studies utilizing particulate matter data need to acknowledge and address these issues to ensure accurate and reliable results.

Flow and dispersion of traffic pollutants in a generic urban neighborhood with avenue-trees were investigated with Computational Fluid Dynamics (CFD). In Part I of this two-part contribution, quality assessment and assurance for CFD simulations in urban and vegetation configurations were addressed, before in Part II flow and dispersion in a generic urban neighborhood with multiple layouts of avenue-trees were studied. In a first step, a grid sensitivity study was performed that inferred that a cell count of 20 per building height and 12 per canyon width is sufficient for reasonable grid insensitive solutions. Next, the performance of the realizable k-ε turbulence model in simulating urban flows and of the applied vegetation model in simulating flow and turbulence in trees was validated. Finally, based on simulations of street canyons with and without avenue-trees, an appropriate turbulent Schmidt number for modeling dispersion in the urban neighborhood was determined as Sct = 0.5.

This study was conducted to analyze the genetic variability of Escherichia coli from domesticated animal wastes for microbial source tracking (MST) application in fecal contaminated shellfish growing waters of Xiangshan Bay, East China Sea. (GTG)₅ primer was used to generate 1363 fingerprints from E. coli isolated from feces of known 9 domesticated animal sources around this shellfish culture area. Jackknife analysis of the complete (GTG)₅-PCR DNA fingerprint library indicated that isolates were assigned to the correct source groups with an 84.28% average rate of correct classification. Based on one-year source tracking data, the dominant sources of E. coli were swine, chickens, ducks and cows in this water area. Moreover, annual and spatial changes of E. coli concentrations and host sources may affect the level and distribution of zoonotic pathogen species in waters. Our findings will further contribute to preventing fecal pollution in aquatic environments and quality control of shellfish.

Although a growing number of studies have reported microplastics (MPs) in biosolids and soils, there are significant differences in the concentrations found across different regions worldwide. This has raised questions about the quality of studies due to a lack of standardized sampling and analysis methods for detecting MPs in such complex samples. In this study, we applied a systematic quantitative literature review (SQLR) methodology to analyze studies reporting MPs in sludge/biosolids and agricultural soils. We also assessed the quality of individual studies on MPs in sludge/biosolids and soils based on the inclusion of quality assurance/quality control (QA/QC) procedures. There is limited understanding about MPs in soils with a history of biosolid application with only 9% of publications reporting MPs in biosolid-amended soil. There was almost eight orders of magnitude difference (3.4 × 10⁻⁵ to 9.4 × 10³ particles/g) between the highest concentrations of MPs in sludge/biosolid samples compared to the lowest virgin soil samples. The literature shows a consistency in the polymer types (polyester, PP and PE) and morphotypes (fibres and fragments) of MPs most frequently detected in biosolids and soils, suggesting a potential role of biosolids in soils MP pollution. Despite the large variations in the sizes of MPs, there was a negative correlation between the lowest size detected and concentrations reported. This indicates that current concentrations of MPs are influenced by the detection size. Our assessment shows that the majority of studies to-date lack critical QA/QC measures, particularly field blank, positive control and method validation. This highlights an urgent need for quality improvement of future research in this field to produce reliable data, ultimately crucial to assess the risk of MPs and derive suitable environmental guidelines. It is recommended that MPs studies methodically include QA/QC protocols at every step of the process to ensure the integrity of the data that is published.

The use of synthetic pesticides is not allowed in organic production, but traces of synthetic pesticides are regularly detected in organic food. To safeguard the integrity of organic production, organic certifiers are obliged to investigate the causes for pesticide residues on organic food, entailing high costs to the organic sector. Such residues can have various origins, including both fraud and unintentional contamination from the environment. Because the knowledge about contamination from environmental sources is scattered, this review provides an overview of pathways for unintentional and technically unavoidable contamination of organic food with synthetic pesticides in Europe. It shows that synthetic pesticides are widely present in all environmental compartments. They originate from applications in the region, in distant areas or from historical use. Transition into the food chain has been demonstrated by various studies. However, large uncertainties remain regarding the true pesticide contamination of the environment, their dynamics and the contamination risks for the food chain. Organic operators can take certain measures to reduce the risks of pesticide contamination of their products, but a certain extent of pesticide contamination is technically unavoidable. The present paper indicates that (i) a potential risk for pesticide residues exists on all organic crops and thus organic operators cannot meet a ‘zero-tolerance’ approach regarding pesticide residues at the moment. (ii) Applying a residue concentration threshold to distinguish between cases of fraud and unavoidable contamination for all pesticides is not adequate given the variability of contamination. More reliable answers can be obtained with a case-by-case investigation, where evidence for all possible origins of pesticide residues is collected and the likelihood of unavoidable contamination and fraud are estimated. Ultimately, for organic certification bodies and control authorities it will remain a challenge to determine whether a pesticide residue is due to neglect of production rules or technically unavoidable.