Environmental emissions of perfluoroalkyl acids (PFAAs) often contaminate aquatic ecosystems and accumulate in the species therein. This can represent an exposure pathway for human populations where seafood is consumed. Concentrations of PFAAs in water breathing animals may be a function of many different factors, however, little is known about how these different factors impact contaminant accumulation in estuarine and marine species. This study explores the relationships between PFAA accumulation and two key variables, animal size and sediment concentrations, for a number of important seafood species. Sixty Dusky Flathead (Platycephalus fuscus), 58 Mulloway (Argyrosomus japonicus) and 53 Giant Mud Crab (Scylla serrata) were tested for perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA) and perfluorohexane sulfonate (PFHxS) in edible tissues, and the concentrations compared with animal size and sediment concentrations at the location of capture. PFAAs showed a high degree of variation among species, and PFOA and PFHxS were only common in Giant Mud Crab. Log-transformed PFOS concentrations in all three species showed negative correlations with animal size (weight). There was limited evidence for relationships between PFOS muscle tissue concentration and sediment PFOS concentration. The patterns observed are potentially explained by changes in trophic position, relative growth rate, consumption rate and metabolic rate, throughout the species life history. The results contrast with observations for other persistent organic pollutants, whereby larger individuals tend to carry greater contaminant loads. Future work is required to establish whether these patterns are evident for PFAAs in other species and contaminant sources.

Cadmium (Cd) contamination is a big challenge for managing food supply and safety around the world. Reduction of the bioaccumulation of cadmium (Cd) in wheat is an important way to minimize Cd hazards to human health. This study compared and highlighted the effects of soil and foliar applications of Zn on Cd accumulation and toxicity in cultivars with high Cd accumulation (high-Cd wheat) and low Cd accumulation (low-Cd wheat). Both foliar and soil Zn applications provided effective strategies for reducing wheat grain Cd concentrations in the high-Cd wheat by 26–49% and 25–52%, respectively, and these also significantly reduced the concentrations in wheat stems and leaves. Foliar and soil Zn applications significantly reduced Cd in leaves and stems of the low-Cd wheat but had no effects on grain Cd. Both soil and foliar Zn applications significantly alleviated Cd toxicity by regulation of Cd transport genes, as reflected by the increased grain yield and antioxidant enzyme activity in the wheat tissues. Gene expression in response to zinc application differed in the two wheat cultivars. Down-regulation of the influx transporter (TaNramp5) and upregulation of the efflux transporters (TaTM20 and TaHMA3) in the high-Cd wheat may have contributed to the Zn-dependent Cd alleviation and enhanced its tolerance to Cd toxicity. Additionally, foliar Zn applications down-regulated the leaf TaHMA2 expression that reduced root Cd translocation to shoots, while soil Zn applications down-regulated the root TaLCT1 expression, which contributed to the reduction of root Cd concentrations. Soil (99 kg ZnSO₄·7H₂O ha⁻¹) and foliar (0.36 kg ZnSO₄·7H₂O ha⁻¹) Zn applications can effectively decrease the Cd in grains and guarantee food safety and yield, simultaneously. The presented results provide a new insight into the mechanisms of, and strategies for, using Zn for the Cd reduction in wheat.

This study presents a comprehensive analysis of organic carbon (OC), elemental carbon (EC), and particularly the light absorption characteristics of EC and water-soluble brown carbon (WS–BrC) in total suspended particles in the Kathmandu Valley from April 2013 to January 2018. The mean OC, EC, and water-soluble organic carbon (WSOC) concentrations were 34.8 ± 27.1, 9.9 ± 5.8, and 17.4 ± 12.5 μg m⁻³, respectively. A clear seasonal variation was observed for all carbonaceous components with higher concentrations occurring during colder months and lower concentrations in the monsoon season. The relatively low OC/EC ratio (3.6 ± 2.0) indicates fossil fuel combustion as the primary source of carbonaceous components. The optical attenuation (ATN) at 632 nm was significantly connected with EC loading (ECS) below 15 μg cm⁻² but ceased as ECS increased, reflecting the increased influence of the shadowing effect. The derived average mass absorption cross-section of EC (MACEC) (7.0 ± 4.2 m² g⁻¹) is comparable to that of freshly emitted EC particles, further attesting that EC was mainly produced from local sources with minimal atmospheric aging processes. Relatively intensive coating with organic aerosols and/or salts (e.g., sulfate, nitrate) was probably the reason for the slightly higher MACEC during the monsoon season, whereas increased biomass burning was a major factor leading to lower MACEC in other seasons. The average MACWS₋BᵣC at 365 nm was 1.4 ± 0.3 m² g⁻¹ with minimal seasonal variations. In contrast to MACEC, biomass burning was the main reason for a higher MACWS₋BᵣC in the non-monsoon season. The relative light absorption contribution of WS-BrC to EC was 9.9% over the 300–700 nm wavelength range, with a slightly higher ratio (13.6%) in the pre-monsoon season. Therefore, both EC and WS-BrC should be considered in the study of optical properties and radiative forcing of carbonaceous aerosols in this region.

MicroRNAs (miRNAs) are a class of small, non-coding RNAs with a post-transcriptional regulatory function on gene expression and cell processes, including proliferation, apoptosis and differentiation. In recent decades, miRNAs have attracted increasing interest to explore the role of epigenetics in response to air pollution. Air pollution, which always contains kinds of particulate matters, are able to reach respiratory tract and blood circulation and then causing epigenetics changes. In addition, extensive studies have illustrated that miRNAs serve as a bridge between particulate matter exposure and health-related effects, like inflammatory cytokines, blood pressure, vascular condition and lung function. The purpose of this review is to summarize the present knowledge about the expression of miRNAs in response to particulate matter exposure. Epidemiological and experimental studies were reviewed in two parts according to the size and source of particles. In this review, we also discussed various functions of the altered miRNAs and predicted potential biological mechanism participated in particulate matter-induced health effects. More rigorous studies are worth conducting to understand contribution of particulate matter on miRNAs alteration and the etiology between environmental exposure and disease development.

The toxicity of organic aerosols has been largely ascribed to the generation of reactive oxygen species, which could subsequently induce oxidative stress in biological systems. The reaction of DTT with redox-active species in PM has been generally assumed to be pseudo-first order, with the oxidative potential of PM being represented by the DTT consumption per minute of reaction time per μg of PM. Although catalytic reactive species such as transition metals and quinones are long believed to be the main contributors of DTT responses, the role of non-catalytic DTT reactive species such as organic hydroperoxides (ROOH) and electron-deficient alkenes (e.g., conjugated carbonyls) in DTT consumption has been recently highlighted. Thus, understanding the reaction kinetics and mechanisms of DTT consumption by various PM components is required to interpret the oxidative potential measured by DTT assays more accurately. In this study, we measured the DTT consumptions over time and characterized the reaction products using model compounds and secondary organic aerosols (SOA) with varying initial concentrations. We observed that the DTT consumption rates linearly increased with both initial DTT and sample concentrations. The overall reaction order of DTT with non-catalytic reactive species and SOA in this study is second order. The reactions of DTT with different functional groups have significantly different rate constants. The reaction rate constant of isoprene SOA with DTT is mainly determined by the concentration of ROOH. For toluene SOA, both ROOH and electron-deficient alkenes may dominate its DTT reaction rates. These results provide some insights into the interpretation of DTT-based aerosol oxidative potential and highlight the need to study the toxicity mechanism of ROOH and electron-deficient alkenes in PM for future work.

Novel brominated flame retardants (NBFRs) are now ubiquitous in the environment with the extensive production and application. In the present study, pentabromotoluene (PBT), hexabromobenzene (HBB) and decabromodiphenyl ethane (DBDPE) were spiked into the sediments where mudsnails (Bellamya aeruginosa) were cultivated. In the 35-day enrichment process, the highest concentration of the three NBFRs measured in mudsnail is 2.0 mg/kg, 22 mg/kg and 5.2 mg/kg dry weight (dw), respectively. The average enrichment of NBFRs in viscera was about 3 times of pleopod with the same mass. Meanwhile, the parent mudsnails can transfer NBFRs to their offspring. The removal half-life of the three NBFRs was in the range of 2.6 and 5.7 days according to the first-order kinetic equation. Several degradation products of the NBFRs were detected in mudsnail samples, which were exposed to single substance. 2,4,6-tribromotoluene was identified as degradation product of PBT; 1,2,4,5-tetrabromobenzene and 1,2,4-tribromobenzene were identified as debromination products of HBB. Possible degradation pathways were further proposed. Additionally, mudsnails after exposed to 50 mg/kg of NBFRs were observed under a scanning electron microscope, indicating that shrinkage, tissue hyperplasia and perforation occurred on the visceral surface. Such damage might be related to the accumulation of more pollutants in mudsnails viscera. As one of the few studies to explore the biological process of NBFRs, our observation could provide a scientific basis for evaluating the environmental risks of NBFRs to benthic organisms.

Mining causes extensive damage to aquatic ecosystems via acidification, heavy metal pollution, sediment loading, and Ca decline. Yet little is known about the effects of mining on freshwater systems in the Southern Hemisphere. A case in point is the region of western Tasmania, Australia, an area extensively mined in the 19th century, resulting in severe environmental contamination. In order to assess the impacts of mining on aquatic ecosystems in this region, we present a multiproxy investigation of the lacustrine sediments from Owen Tarn, Tasmania. This study includes a combination of radiometric dating (¹⁴C and ²¹⁰Pb), sediment geochemistry (XRF and ICP-MS), pollen, charcoal and diatoms. Generalised additive mixed models were used to test if changes in the aquatic ecosystem can be explained by other covariates. Results from this record found four key impact phases: (1) Pre-mining, (2) Early mining, (3) Intense mining, and (4) Post-mining. Before mining, low heavy metal concentrations, slow sedimentation, low fire activity, and high biomass indicate pre-impact conditions. The aquatic environment at this time was oligotrophic and dystrophic with sufficient light availability, typical of western Tasmanian lakes during the Holocene. Prosperous mining resulted in increased burning, a decrease in landscape biomass and an increase in sedimentation resulting in decreased light availability of the aquatic environment. Extensive mining at Mount Lyell in the 1930s resulted in peak heavy metal pollutants (Pb, Cu and Co) and a further increase in inorganic inputs resulted in a disturbed low light lake environment (dominated by Hantzschia amphioxys and Pinnularia divergentissima). Following the closure of the Mount Lyell Co. in 1994 CE, Ca declined to below pre-mining levels resulting in a new diatom assemblage and deformed diatom valves. Therefore, the Owen Tarn record demonstrates severe sediment pollution and continued impacts of mining long after mining has stopped at Mt. Lyell Mining Co.

Maternal blood glucose level is associated with fetal growth, therefore, its role in the associations between air pollution and birth weight deserves investigation. We examined the mediation effect of maternal blood glucose on the associations between maternal air pollution exposure and birth weight. A total of 10,904 pregnant women in Foshan, China during 2015–2019 were recruited. Oral glucose tolerance test (OGTT) was administered to each participant after late trimester 2. Air pollution data at the monitoring stations in residential districts was used to estimate exposures of each participant during trimester 1 and trimester 2. Mixed-effects linear models were used to estimate the associations between air pollution and birth weight. After controlling for ten covariates, the direct effect of PM₂.₅ and SO₂ (each 10 μg/m³ increment) on birth weight was −15.7 g (95% CI: −29.4, −4.8 g) and −83.6 g (95% CI: −134.8, −33.0 g) during trimester 1. The indirect effect of PM₂.₅ and SO₂ (each 10 μg/m³ increment) on birth weight by increasing maternal fasting glucose level was 6.6 g (95% CI: 4.6, 9.1 g) and 22.0 g (95% CI: 4.1, 44.0 g) during trimester 1. Our findings suggest that air pollution might affect the birth weight through direct and indirect pathway, and the indirect effect might be mediated by maternal blood glucose.

To investigate chemical characteristics, abatement mechanisms and regional transport of atmospheric pollutants during the COVID-19 outbreak control period in the Yangtze River Delta (YRD) region, China, the measurements of air pollutants including fine particulate matter (PM₂.₅) and volatile organic compounds (VOCs) on non-control period (NCP, 24 December 2019–23 January 2020) and control period (CP, 24 January–23 February 2020) were analyzed at the urban Pudong Supersite (PD) and the regional Dianshan Lake Supersite (DSL). Due to the stricter outbreak control, the levels of PM₂.₅ and VOCs, and the occurrence frequencies of haze-fog episodes decreased substantially from NCP to CP, with average reduction rates of 31.6%, 38.9% and 35.1% at PD, and 34.5%, 50.7% and 37.9% at DSL, respectively. The major source for PM₂.₅ was secondary sulfate & nitrate in both periods, and the emission control of primary sources such as coal burning and vehicle exhaust decreased the levels of precursors gas sulfur dioxide and nitrogen oxide, which highly contributed to the abatement of PM₂.₅ from NCP to CP. The higher levels of ozone at both PD and DSL on CP might be due to the weak nitrogen monoxide titration, low relative humidity and high visibility compared with NCP. Vehicle exhaust and fugitive emission from petrochemical industry were the major contributors of ambient VOCs and their decreasing activities mainly accounted for VOCs abatement. Moreover, the high frequency of haze-fog events was closely impacted by medium-scale regional transport within Anhui and Jiangsu provinces. Therefore, the decreasing regional transported air pollutants coincided with the emission control of local sources to cause the abatement of haze-fog events in YRD region on CP. This study could improve the understanding of the change of atmospheric pollutants during the outbreak control period, and provide scientific base for haze-fog pollution control in YRD region, China.

Given that studies on actual sewage treatment plants are often affected by environmental conditions, it is challenging to clearly understand the associated bioaerosol generation and diffusion characteristics during the aeration process. Therefore, to enhance understanding in this regard, in this study, bioaerosol generator was used to simulate bioaerosol generation and diffusion under two aeration modes, i.e., bubble bottom aeration and brush surface aeration. The total concentration range of culturable bacteria in the bioaerosol produced by bubble bottom aeration and that produced by brush surface aeration were 300–3000 CFU/m³. Under bubble bottom aeration, the generated bioaerosol was symmetrically distributed around the source point, whereas under brush surface aeration, it was primarily distributed in the forward direction of the rotating brush surface. These bioaerosols from bubble bottom aeration predominantly consisted of particles with sizes below 3.3 μm, particularly those with sizes in the range 1.1–2.1 μm. On the contrary, the bioaerosols produced via brush surface aeration predominantly consisted of particles with sizes above 3.3 μm. The distribution characteristics of population structure in the two aeration modes were consistent with the distribution characteristics of concentration in the corresponding models. Additionally, the results showed that when the aeration process is unaffected by environmental conditions (particle matters, wind direct, wind speed, etc.), the bioaerosol components originate primarily from the parent sewage or sludge, and do not diffuse far from the source point. Therefore, source reduction (capping or sealing) can be recommended as the primary control strategy for bioaerosols in sewage treatment plants. The adoption of such measures will significantly limit the diffusion of bioaerosols, thereby reducing the potential risks associated with human exposure.