Sediment phosphorus (P) release and retention are important in controlling whole-system P dynamics and budget in eutrophic lakes. Here we combine short- (seasonal) and long-term (years to decades) studies to quantify the internal P loading and P release potential in the sediments of Lake Chaohu and explore their controlling mechanisms. In the west region of the lake, short-term P diffusive fluxes ranged from 0.2 mg/m²·d⁻¹ to 6.69 mg/m²·d⁻¹ (averaged 2.76 mg/m²·d⁻¹) and long-term net P release ranged from 2.25 mg/m²·d⁻¹ to 8.94 mg/m²·d⁻¹ (averaged 5.34 mg/m²·d⁻¹); in the east region, short-term P diffusive fluxes varied from 0.73 mg/m²·d⁻¹ to 1.76 mg/m²·d⁻¹ (averaged 1.05 mg/m²·d⁻¹) and long-term P release ranged from 0.13 mg/m²·d⁻¹ to 4.15 mg/m²·d⁻¹ (averaged 1.3 mg/m²·d⁻¹). Both short- and long-term P releases were in the same order of magnitudes as the external P inputs (3.56 mg/m²·d⁻¹). Comparison of the long-term and short-term sediment P release indicates that while the high summer P release in the east might only represent a snapshot value, the sediments in the west contribute to large P release for years or even decades, impeding water quality recovery under lake management. Mobilization of surface sediment legacy P accounted for 81% of short-term P release. The long-term release was dominated by remobilization of iron bond P (BD-P) (average 52.1%) at all sites, while Aluminium-bound P (NaOH-rP) exhibited partly reactive and potentially mobile, releasing P to the water column in most sites in the west. Our study demonstrates the importance of sediments as P sources in lake Chaohu. The combination of short- and long-term P release studies can help understand the roles of sediments in regulating the water quality and eutrophication.

We quantify for the first time marine aerosol properties and their differences in the offshore and remote ocean in the mid-latitude South Asian waters, low-latitude South Asian waters, and equatorial waters of the Western Pacific Ocean, based on shipboard cruise observations conducted by the Western Pacific Ocean Scientific Observation Network in winter 2018, and further investigate the effects of long-range transport of continental aerosols on the marine environment. During the overall observation period, the average number concentration of particle matter which aerodynamic diameters<2.5 μm (PM₂.₅N) was 35.1 ± 87.4 cm⁻³ and the mass concentration (PM₂.₅M) was 12.3 ± 9.1 μg/m³. The PM₂.₅N and PM₂.₅M during the continental air mass transport period were 7.2 and 1.3 times higher than those during the non-transport period (109.2 ± 169.3 cm⁻³, 15.9 ± 14.9 μg/m³), respectively. Excluding transport period, the average PM₂.₅N and PM₂.₅M are reduced by 120% and 7%. Coarse mode particle number concentration (PM₂.₅–₁₀N) and mass concentration (PM₂.₅–₁₀M) are not significantly influenced by continental air masses (only a reduction of 7% and 2%). The variation of marine aerosol concentrations in different latitudes zones is greatly influenced by continental aerosol transport. The offshore PM₂.₅M/PM₁₀M was 30%, 21%, and 22% in the mid-latitude sea of South Asia, a low-latitude sea of South Asia, and the equatorial sea, respectively. In comparison, in the remote ocean, the distribution ratio of PM₂.₅M/PM₁₀M tended to be steady (22%–23%), and the background characteristics of marine aerosols were clearly represented. The aerosol concentration decreases with the increase of wind speed during the transport period, and the wind speed reflects the scavenging effect on aerosol. In the non-transport period, the wind speed at the sea surface promotes the generation of marine aerosols, and the impact in wind speed is strongest in the PM₂.₅–PM₅ particle size range.

Arsenic (As) is a highly toxic metalloid adversely affecting the environment, human health, and crop productivity. The present study assessed the synergistic effects of salinity and As on photosynthetic attributes, stomatal regulations, and metabolomics responses of the xero-halophyte Salvadora persica to decipher the As-salinity cross-tolerance mechanisms and to identify the potential metabolites/metabolic pathways involved in cross-tolerance of As with salinity. Salinity and As stress-induced significant stomatal closure in S. persica suggests an adaptive response to decrease water loss through transpiration. NaCl supplementation improved the net photosynthetic rate (by +39%), stomatal conductance (by +190%), water use efficiency (by +55%), photochemical quenching (by +37%), and electron transfer rate (54%) under As stress as compared to solitary As treatment. Our results imply that both stomatal and non-stomatal factors account for a reduction in photosynthesis under high salinity and As stress conditions. A total of 64 metabolites were identified in S. persica under salinity and/or As stress, and up-regulation of various metabolites support early As-salinity stress tolerance in S. persica by improving antioxidative defense and ROS detoxification. The primary metabolites such as polyphenols (caffeic acid, catechin, gallic acid, coumaric acid, rosmarinic acid, and cinnamic acid), amino acids (glutamic acid, cysteine, glycine, lysine, phenylalanine, and tyrosine), citrate cycle intermediates (malic acid, oxalic acid, and α-ketoglutaric acid), and most of the phytohormones accumulated at higher levels under combined treatment of As + NaCl compared to solitary treatment of As. Moreover, exogenous salinity increased glutamate, glycine, and cysteine, which may induce higher synthesis of GSH-PCs in S. persica. The metabolic pathways that were significantly affected in response to salinity and/or As include inositol phosphate metabolism, citrate cycle, glyoxylate and dicarboxylate metabolism, amino acid metabolism, and glutathione metabolism. Our findings indicate that inflections of various metabolites and metabolic pathways facilitate S. persica to withstand and grow optimally even under high salinity and As conditions. Moreover, the addition of salt enhanced the arsenic tolerance proficiency of this halophyte.

Geochemical cycling of iron (Fe) mediated by sediment microbes drives the remobilization of phosphorus (P). Understanding the underlying mechanism is essential for the evaluation of P retention by wetlands. The diffusive gradients in thin film (DGT) and 16S rDNA sequencing techniques were combined to explore seasonal variations in the remobilization mechanism of sediment P in a free water surface wetland in southwest China. A significantly positive correlation between labile P and Fe concentrations was found from the sediment profiles, indicating coupled remobilization of Fe and P in the sediment. Fe-reducing bacterial genera, particularly Sphingomonas and Geothermobacter, were responsible for the reductive dissolution of Fe oxides and subsequent P release in sediment. The efflux of sediment P was higher in the rainy season (95 ± 87 ng cm⁻² d⁻¹) than in the dry season (39 ± 29 ng cm⁻² d⁻¹). Based on the significantly positive relationship between the efflux and total concentration of sediment P, we propose a promising regression equation for quantifying the release risk of sediment P. The Luoshijiang Wetland exhibited a higher release potential as indicated by a greater regression slope (0.558) compared to the other water bodies (0.055), which was mainly attributed to the lower labile Fe:P molar ratio in the sediment. Based on estimations of the diffusive flux of P at the sediment-water interface, sediment contributed more than 172 and 413 g of P per day to the water column in the dry and rainy seasons, respectively, accounting for 14.0% and 1.9% of the P mass in the surface water of the wetland.

Perfluorooctane sulfonate (PFOS) is among the most commonly per- and poly-fluoroalkyl substances (PFAS) found in environmental samples. Nevertheless, the effect of this legacy persistent organic contaminant has never been investigated on corals to date. Corals are the keystone organisms of coral reef ecosystems and sensitive to rising ocean temperatures, but it is not understood how the combination of elevated temperature and PFOS exposure will affect them. Therefore, the aims of the present study were (1) to evaluate the time-dependent bioconcentration and depuration of PFOS in the scleractinian coral Stylophora pistillata using a range of PFOS exposure concentrations, and (2) to assess the individual and combined effects of PFOS exposure and elevated seawater temperature on key physiological parameters of the corals. Our results show that the coral S. pistillata rapidly bioconcentrates PFOS from the seawater and eliminates it 14 days after ceasing the exposure. We also observed an antagonistic effect between elevated temperature and PFOS exposure. Indeed, a significantly reduced PFOS bioconcentration was observed at high temperature, likely due to a loss of symbionts and a higher removal of mucus compared to ambient temperature. Finally, concentrations of PFOS consistent with ranges observed in surface waters were non-lethal to corals, in the absence of other stressors. However, PFOS increased lipid peroxidation in coral tissue, which is an indicator of oxidative stress and enhanced the thermal stress-induced impairment of coral physiology. This study provides valuable insights into the combined effects of PFOS exposure and ocean warming for coral's physiology. PFOS is usually the most prevalent but not the only PFAS defected in reef waters, and thus it will be also important to monitor PFAS mixture concentrations in the oceans and to study their combined effects on aquatic wildlife.

Organic ultraviolet (UV) filters are used in personal care products, but they are also added to industrial products and are constantly released to the environment. This study analyses the occurrence of 8 widely used organic UV filters in seawater from three beaches on the Gran Canaria Island (Spain) and in three wastewater treatment plants (WWTPs) by taking samples from influents and effluents. It also discusses the target compounds’ post-treatment removal efficiencies. Sampling was carried out for 6 months and analytes were extracted by solid phase extraction with Sep-pak C18 cartridges. They were determined by ultra-high performance liquid chromatography coupled to mass spectrometry in tandem. The potential environmental hazard associated with the found concentrations was also assessed for marine organisms. Different target compounds were detected on the analysed beaches and in the wastewater. Benzophenone-3 (BP3) was the most recurrent compound in the seawater samples (frequency detection of 83%) and also in wastewater influents and effluents (measured in all the samples). However, the highest concentrations for seawater (172 μg L⁻¹) and influent wastewater (208 μg L⁻¹) corresponded to octocrylene, while methylene bis-benzotriazolyltetramethylbutylphenol was the compound most concentrated in secondary treatment effluent (34.0 μg L⁻¹) and BP3 in tertiary treatment effluent (8.07 μg L⁻¹). All the analysed samples showed that at least one target UV filter was present. Regarding the removal efficiencies of these compounds in the studied WWTPs, consistent differences between the target compounds were observed in influent concentration terms, where the average removal rates were higher than 50% for most of the compounds. Conventional treatment is unable to completely remove many studied compounds, while tertiary treatment acts as an additional elimination for some of them. An environmental hazard quotient above 1 was found for octocrylene, benzophenone-3 and 4-methylbenzylidene camphor, which indicates a potential high hazard for living species if these compounds are present.

Most amyotrophic lateral sclerosis (ALS) cases are sporadic (∼90%) and environmental exposures are implicated in their etiology. Large industrial facilities are permitted the airborne release of certain chemicals with hazardous properties and report the amounts to the US Environmental Protection Agency (EPA) as part of its Toxics Release Inventory (TRI) monitoring program. The objective of this project was to identify industrial chemicals released into the air that may be associated with ALS etiology. We geospatially estimated residential exposure to contaminants using a de-identified medical claims database, the SYMPHONY Integrated Dataverse®, with ∼26,000 nationally distributed ALS patients, and non-ALS controls matched for age and gender. We mapped TRI data on industrial releases of 523 airborne contaminants to estimate local residential exposure and used a dynamic categorization algorithm to solve the problem of zero-inflation in the dataset. In an independent validation study, we used residential histories to estimate exposure in each year prior to diagnosis. Air releases with positive associations in both the SYMPHONY analysis and the spatio-temporal validation study included styrene (false discovery rate (FDR) 5.4e-5), chromium (FDR 2.4e-4), nickel (FDR 1.6e-3), and dichloromethane (FDR 4.8e-4). Using a large de-identified healthcare claims dataset, we identified geospatial environmental contaminants associated with ALS. The analytic pipeline used may be applied to other diseases and identify novel targets for exposure mitigation. Our results support the future evaluation of these environmental chemicals as potential etiologic contributors to sporadic ALS risk.

Various precursor emissions and chemical mechanisms for secondary organic aerosol (SOA) formation were incorporated into a regional air quality model system (RAQMS) and applied to investigate the distribution, composition, and source contribution of SOA over east China in summer 2018. Model comparison against a variety of observations at a national scale demonstrated that the model was able to reasonably reproduce meteorological variables, O₃ and PM₂.₅ concentrations, and the model simulated SOA concentration generally agreed with observations, with the overall NMB of 7.0% and R of 0.4 in 10 cities over east China. The simulated period-mean SOA concentrations of 4–15 μg m⁻³ were mainly distributed over the North China Plain (NCP), the middle and lower reaches of the Yangtze River and Chongqing district. SOA dominated organic aerosol (OA) over China in summertime (90%). The percentage contributions to SOA from ASOA (SOA produced from anthropogenic volatile organic compounds (AVOC)), BSOA (SOA produced from biogenic volatile organic compounds (BVOC)), DSOA (SOA produced from aqueous uptake of glyoxal and methylglyoxal) and S/I-SOA (SOA produced from semi-volatile and intermediate volatile organic compounds) were estimated to be 48.3%, 28.6%, 14.3%, and 8.8% respectively, over east China in summertime. In terms of domain and period average, ASOA contributed most to SOA (59%) in north China, while BSOA contributed most to SOA (37.3%) in northeast China. The percentage contribution of DSOA to SOA reached 21.5% in southwest China. S/I-SOA accounted for approximately 10% of SOA in most areas of east China. This study reveals that while AVOC dominates SOA formation on average over east China, the SOA source contributions differ considerably in different regions of China. BVOC makes the same contribution to SOA formation as AVOC in northeast China and southwest China, where forest coverage and BVOC emission are higher and anthropogenic emissions are relatively low, highlighting the significant role of BVOC in summer SOA formation in China.

Considerable efforts on exposure assessment of microplastics (MPs) as an agent in transport of toxic contaminants have been performed in organisms. However, chemical diffusion of inherent hydrophobic organic contaminants from MPs under simulated gut conditions is poorly examined. The present study examined the transfer kinetics of polybrominated diphenyl ethers (PBDEs) from polystyrene (PS), acrylonitrile butadiene styrene (ABS), and polypropylene (PP) MPs under gut surfactants (sodium taurocholate) at two relevant body temperatures of marine organisms, and evaluated the importance of MP ingestion in bioaccumulation of PBDEs in lugworm by a biodynamic model. Diffusion coefficients of PBDEs range from 5.82 × 10⁻²³ to 7.96 × 10⁻²⁰ m² s⁻¹ in PS, 5.49 × 10⁻²³ to 3.45 × 10⁻²⁰ m² s⁻¹ in ABS, and 5.58 × 10⁻²¹ to 5.79 × 10⁻¹⁷ m² s⁻¹ in PP, with apparent activation energies in the range of 33–148 kJ mol⁻¹. The biota–plastic accumulation factors of PBDEs leached from these plastics range from 1.44 × 10⁻⁸ to 7.15 × 10⁻⁵. Although ingestion of MPs with the common size (>0.5 mm) showed the negligible contribution to bioaccumulation of PBDEs in lugworm, their contribution in PBDEs transfer can be increased with gradual breakdown of MPs.

Plant-based products such as essential oils and other extracts have been used for centuries due to their beneficial properties. Currently, their use is widely disseminated through a variety of industries and new applications are continuously emerging. For these reasons, they are produced industrially in large quantities and consequently they have the potential to reach the environment. However, the potential effects that these products have on the ecosystems’ health are mostly unknown. In recent years, the scientific community started to focus on the possible toxic effects of essential oils and plant extracts towards non-target organisms. As a result, an increasing body of knowledge has emerged. This review describes the current state of the art on the toxic effects that essential oils and plant extracts have towards organisms from different trophic levels, including producers, primary consumers, and secondary consumers. The majority of the studies (76.5%) focuses on the aquatic environment, particularly in aquatic invertebrates (45.1%) with only 23.5% of the studies focusing on the potential toxicity of plant-derived products on terrestrial ecosystems.While some essential oils and extracts have been described to have no toxic effects to the selected organisms or the toxic effects were only observable at high concentrations, others were reported to be toxic at concentrations below the limit set by international regulations, some of them at very low concentrations. In fact, L(E)C₅₀ values as low as 0.0336 mg.L⁻¹, 0.0005 mg.L⁻¹ and 0.0053 mg.L⁻¹ were described for microalgae, crustaceans and fish, respectively. Generally, essential oils exhibit higher toxicity than extracts. However, when the extracts are obtained from plants that are known to produce toxic metabolites, the extracts can be more toxic than essential oils.Overall, and despite being generally considered “eco-friendly” products and safer than they synthetic counterparts, some essential oils and plant extracts are toxic towards non-target organisms. Given the increasing interest from industry on these plant-based products further research using international standardized protocols is mandatory.