Foamed plastic debris in aquatic systems has become one of the emerging global contaminants. In this study, the behavior of polystyrene foam (PSF) and microplastics (MPs) adhered on the PSFs were investigated on the Tuul River shore in Ulaanbaatar, the capital city of Mongolia. The micro-sized (<5 mm) PSF, which was the dominant PSF over 600 pieces in 100 m², have accumulated along the shoreline of Tuul River. Carbonyl index (CI) was calculated to evaluate the surface oxidation of macro-sized (20–100 mm), meso-sized (5–20 mm), and micro-sized PSFs and confirm the relative aging depending on photodegradation. CI ranged from 0.00 to 1.09 in the sampled PSFs, whereby the degraded PSFs with high CI were distributed on the shore of downstream of sewer drainage. Micro-sized PSFs showed a wide range of CI and a relatively high average value of CI as compared to those of meso- and macro-sized PSFs. Most of PSFs aggregated with MPs and the adhered MPs have been ubiquitously detected from the surface of PSFs. Adhered micro-sized plastics explored from the surface of PSFs with various sizes, except for mega-sized (>100 mm) PSF, ranged from 5 to 141 items per piece of PSF fragment. The aggregates of PSFs and MPs were common status of PSFs during their transportation. The present findings, which indicated a high concentration of adhered MPs, raise an environmental concern about the widespread aquatic plastic pollution.

The severe and pervasive effects of multispecies foodborne microbial biofilms highlight the importance of rapid detection and diagnosis of contamination risk in the field using epifluorescence-based techniques (EBT) combined with automatic image-counting software. This study screened the hygiene quality of the environment, the carcass and the slaughtering equipment in the El-Kharga abattoir, New Valley Province, Egypt, to assess possible contamination during slaughter process. In addition, biofilm was assessed, and bacteria was enumerated by epifluorescence microscopy. Using both conventional and EBT, the highest bacterial counts were observed for the slaughtering equipment (6.6 and 5.2 cfu/cm2, respectively), followed by different parts of the carcass (4.1 and 4.4 cfu/cm2, respectively) and environmental samples (3.9 and 4.1 cfu/cm2, respectively). A high prevalence of E. coli O157:H7 was observed on the slaughtering equipment (25%), which also led to carcass (1%) contamination. Moreover, Enterobacteriaceae members were detected during examination, such as Klebsiella pneumoniae, Enterobacter aerogenes, and Raoultella ornithinolytica. Despite the relatively good hygiene quality of the abattoir environment, there is also a high risk associated with biofilm formation by pathogenic microorganisms on the slaughtering equipment. Moreover, EBT showed different structures of the biofilm, including those formed at different maturation stages, such as voids, microbubbles, channels and mushroom shapes. (EBT) microscopy combined with image-counting software could be a candidate substitute to estimate efficiently, precisely and rapidly the microbial aggregation and exposure risk in field than the conventional counting techniques.

Natural sources, such as soil and wind-erosion dust (SWD), biomass open burning (BOB), sea salt spray (SSAS) and biogenic source (BIO), are major contributors to atmospheric emissions of trace elements (TEs) globally. In this study, we used a comprehensive approach to account for area-, production- and biofuel consumption-based emission factor calculation methods, and thus developed an integrated high-resolution emission inventory for 15 types of TEs (As, B, Cd, Co, Cr, Cu, Hg, Mn, Mo, Ni, Pb, Sb, Se, V and Zn) originated from natural sources in China for the year 2015. The results show that national emissions of TEs in 2015 range from 7.45 tons (Hg) to 1, 400 tons (Zn) except for the extremely high emissions of Mn (10, 677 tons). SWD and BIO are identified as the top two source contributors, accounting for approximately 67.7% and 26.1% of the total emissions, respectively. Absolute emissions of TEs from natural sources are high in the Xinjiang, Inner Mongolia and Tibet autonomous regions with large areas of bare soil and desert. However, emission intensity of TEs per unit area in the Southern provinces of China is higher than those in Northern China and Southwestern China, with the Yunnan and Sichuan provinces displaying the highest emission intensity. Our results suggest that controlling SWD can play a significant role in reducing fugitive particulate matter and the associated emissions of TEs from natural sources in China; and desertification control is particularly critical in the Northwest provinces where the majority of deserts are located.

The transport of trace metals in river–lake systems can potentially increase or decrease primary productivity in some basins and subsequently affect the carbon cycle of watersheds. In this study, we investigated a variety of trace metal concentrations and transport flux in the Poyang Lake basin during four seasons. Results show that the Gan River transports 78% of selenium (Se) and 42% of lead (Pb) into Poyang Lake each year, resulting in heavy metal pollution dominated by Pb and Se in 30%–75% of its water. Although toxic heavy metals, such as Pb, chromium (Cr), and copper (Cu), inhibit phytoplankton growth and decrease its gross primary productivity (GPP), excessive Se could effectually promote productivity. However, the negative effect of Pb on GPP is more significant than the positive effect of Se on GPP; hence, their interaction effectuates a decrease in total primary productivity. Additionally, under high nutrients level, the synergistic effect of heavy metals and nutrients will reduce GPP. Agricultural fertilizer is likely the source of both Pb, Cu, Se and N. Gan River contributes 35%–80% of the heavy metal inputs to Poyang Lake. It is therefore necessary to improve the ecological environment of phytoplankton and promote productivity in the Poyang Lake basin by reducing the application of agricultural chemical fertilizers to control pollution. Our results indicate that the role of certain, less studied trace elements (e.g., Pb, Cr, Cu, and Se) in regulating primary productivity of watershed ecosystems is more important than previously thought. This study also discusses potential impacting mechanisms associated with these metals on phytoplankton, whose biological functions need to be verified in future experiments.

Nitrous oxide emission factors (N₂O-EF, percentage of N₂O–N emissions arising from applied fertilizer N) for cropland emission inventories can vary with agricultural management, soil properties and climate conditions. Establishing a regionally-specific EF usually requires the measurement of a whole year of N₂O emissions, whereas most studies measure N₂O emissions only during the crop growing season, neglecting emissions during non-growing periods. However, the difference in N₂O-EF (ΔEF) estimated using measurements over a whole year (EFwy) and those based on measurement only during the crop-growing season (EFgₛ) has received little attention. Here, we selected 21 studies including both the whole-year and growing-season N₂O emissions under control and fertilizer treatments, to obtain 123 ΔEFs from various agroecosystems globally. Using these data, we conducted a meta-analysis of the ΔEFs by bootstrapping resampling to assess the magnitude of differences in response to management-related and environmental factors. The results revealed that, as expected, the EFwy was significantly greater than the EFgₛ for most crop types. Vegetables showed the largest ΔEF (0.19%) among all crops (0.07%), followed by paddy rice (0.11%). A higher ΔEF was also identified in areas with rainfall ≥600 mm yr⁻¹, soil with organic carbon ≥1.3% and acidic soils. Moreover, fertilizer type, residue management, irrigation regime and duration of the non-growing season were other crucial factors controlling the magnitude of the ΔEFs. We also found that neglecting emissions from the non-growing season may underestimate the N₂O-EF by 30% for paddy fields, almost three times that for non-vegetable upland crops. This study highlights the importance of the inclusion of the non-growing season in the measurements of N₂O fluxes, the compilation of national inventories and the design of mitigation strategies.

Cooking and heating with solid fuels results in high levels of household air pollutants, including particulate matter (PM); however, limited data exist for size fractions smaller than PM₂.₅ (diameter less than 2.5 μm). We collected 24-h time-resolved measurements of PM₂.₅ (n = 27) and particle number concentrations (PNC, average diameter 10–700 nm) (n = 44; 24 with paired PM₂.₅ and PNC) in homes with wood-burning traditional and Justa (i.e., with an engineered combustion chamber and chimney) cookstoves in rural Honduras.The median 24-h PM₂.₅ concentration (n = 27) was 79 μg/m³ (interquartile range [IQR]: 44–174 μg/m³); traditional (n = 15): 130 μg/m³ (IQR: 48–250 μg/m³); Justa (n = 12): 66 μg/m³ (IQR: 44–97 μg/m³). The median 24-h PNC (n = 44) was 8.5 × 10⁴ particles (pt)/cm³ (IQR: 3.8 × 10⁴–1.8 × 10⁵ pt/cm³); traditional (n = 27): 1.3 × 10⁵ pt/cm³ (IQR: 3.3 × 10⁴–2.0 × 10⁵ pt/cm³); Justa (n = 17): 6.3 × 10⁴ pt/cm³ (IQR: 4.0 × 10⁴–1.2 × 10⁵ pt/cm³). The 24-h average PM₂.₅ and particle number concentrations were correlated for the full sample of cookstoves (n = 24, Spearman ρ: 0.83); correlations between PM₂.₅ and PNC were higher in traditional stove kitchens (n = 12, ρ: 0.93) than in Justa stove kitchens (n = 12, ρ: 0.67). The 24-h average concentrations of PM₂.₅ and PNC were also correlated with the maximum average concentrations during shorter-term averaging windows of one-, five-, 15-, and 60-min, respectively (Spearman ρ: PM₂.₅ [0.65, 0.85, 0.82, 0.71], PNC [0.74, 0.86, 0.88, 0.86]).Given the moderate correlations observed between 24-h PM₂.₅ and PNC and between 24-h and the shorter-term averaging windows within size fractions, investigators may need to consider cost-effectiveness and information gained by measuring both size fractions for the study objective. Further evaluations of other stove and fuel combinations are needed.

Oil spills can result in changes in chemical contaminant concentrations along coastlines. When concentrations are measured along the Gulf of Mexico over time, this information can be used to evaluate oil spill shoreline exposure dates. The objective of this research was to identify more accurate oil exposure dates based on oil spill chemical concentrations changes (CCC) within sediments in coastal zones after oil spills. The results could be used to help improve oil transport models and to improve estimates of oil landings within the nearshore. The CCC method was based on separating the target coastal zone into segments and then documenting the timing of large increases in concentration for specific oil spill chemicals (OSCs) within each segment. The dataset from the Deepwater Horizon (DWH) oil spill was used to illustrate the application of the method. Some differences in exposure dates were observed between the CCC method and between oil spill trajectories. Differences may have been caused by mixing at the freshwater and sea water interface, nearshore circulation features, and the possible influence of submerged oil that is unaccounted for by oil spill trajectories. Overall, this research highlights the benefit of using an integrated approach to confirm the timing of shoreline exposure.

To compare the health risks of multiple metal(loid)s in groundwater, and discuss the feasibility of drinking water standards, 66 groundwater samples were collected from the Hetao Plain in October 2017. Eighteen metal(loid) species (boron (B), manganese (Mn), iron (Fe), strontium (Sr), barium (Ba), lithium (Li), scandium (Sc), titanium (Ti), vanadium (V), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), selenium (Se), rubidium (Rb), molybdenum (Mo), uranium (U)) were analyzed, and the related non-carcinogenic risks were assessed. The results showed that 83.3% of the groundwater samples had As and Fe contents above the maximum allowed contaminant levels (MCLs) in drinking water standards, followed by Mn (70.2%), B (65.2%), Se (60.6%), U (18.2%), Ni (18.2%) and Mo (1.50%). Compared with the dermal exposure pathway, oral ingestion made a risk contribution of more than 99% for all target metal(loid)s. Site-specific hazard quotient (HQ) values ranged from 2.30E+00 to 1.75E+02, indicating that multiple metal(loid)s in the drinking groundwater cause a serious non-carcinogenic risk to the local people. The risk contributions (mean value) were ranked as As (55.2%) > U (25.5%) > Li (10.8%) > other total metal(loid)s (8.60%), and the contributions of U and Li could reach 91.7% (site 20) and 69.8% (site 56), respectively. The calculation of specific health risks further indicated that the MCLs of metal(loid)s do not match the corresponding health risk well. Some metal(loid)s such as Li that showed high exposure risks in this study, still have no MCL values until now. Therefore, current drinking water standards need to be updated.

Cattle-derived biochar (CB), which is derived from industrial pyrolysis of cattle carcasses in harmless treatment plants, is a naturally occurring mineral form of carbonate-bearing hydroxyapatite (CHAP) with a small amount of elemental carbon. CB has 4.02% of carbonate content, which falls under the B-type substitution of CHAP. In this work, the Cd(II) sorption capacity of CB was determined to be 0.82 mmol/g, with 97.6% of the Cd(II) uptake contributing to CHAP and only 2.36% of the Cd(II) uptake contributing to the elemental carbon component. The calculation and linear combination fitting (LCF) of Cd L₃-edge X-ray absorption near-edge structure (XANES) analysis indicated that the contributions of Cd(II) species to CB presented the following order: ion exchange (57.6%–61.0%) > precipitation (24.4%–29.9%) > surface complexation (12.5%–13.4%). The depth dependent X-ray photoelectron spectroscopy (XPS) showed the presence of ion exchange, which is accompanied by intraparticle diffusion. LCF of XANES and Rietveld analysis of X-ray diffraction (XRD) demonstrated that Cd(II) was precipitated in the form of Cd₅H₂(PO₄)₄·4H₂O on the CB surface. Furthermore, the precipitate was directly observed and identified by scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS). Consequently, we revealed the intricate binding mechanism of Cd(II) to CHAP-rich CB and confirmed the importance of surface precipitation.

2,2′,4,4′-Tetrabromodiphenyl ether (BDE-47) is associated with various adverse human health effects; however, the knowledge of its toxicity is still very limited. Mitochondrial injury has been observed in liver cells exposed to BDE-47 in vitro. Mitophagy impairment causes the accumulation of dysfunctional mitochondria, contributing to the pathological mechanisms of liver injury. The aim of this study was to investigate whether BDE-47 impairs mitophagy to trigger mitochondrial dysfunction-related liver injury and the underlying mechanisms. This study revealed that BDE-47 elicited mitochondrial dysfunction and related oxidative liver injury by impairing mitophagy. Moreover, our results showed that NAD⁺ insufficiency is responsible for BDE-47-mediated mitophagy defect and mitochondrial dysfunction in mouse livers, which was associated with suppression of Sirt3/FoxO3a/PINK1 signaling. Furthermore, our results indicated a potential role of miR-34a-5p in the hepatotoxicity of BDE-47. Mechanistically, BDE-47 dramatically upregulated miR-34a-5p expression in mouse livers. The data from AAV-sponge-mediated miR-34a-5p inhibition suggested that miR-34a-5p diminished NAD⁺ level by directly targeting NAMPT expression in BDE-47-treated mouse livers, which was confirmed by luciferase reporter assay. Consequently, miR-34a-5p markedly abated Sirt3/FoxO3a/PINK1 signaling-mediated mitophagy to promote mitochondrial dysfunction in BDE-47-treated mouse livers. The present study provided in vivo evidence to reveal a potential mechanism for BDE-47-induced mitochondrial dysfunction and related liver injury and indicated that miR-34a-5p-mediated mitophagy impairment might be a therapeutic target for BDE-47 toxicity.