The toxicity of nanoplastics to aquatic organisms has been widely studied in terms of biochemical indicators. However, there is little discussion about the underlying toxic mechanism of nanoplastics on microalgae. Therefore, the chronic effect of polystyrene (PS) nanoplastics (80 nm) on Chlorella pyrenoidosa was investigated, in terms of responses at the biochemical and molecular/omic level. It was surprising that both inhibitory and promoting effects of nanoplastcis on C. pyrenoidosa were found during chronic exposure. Before 13 days, the maximum growth inhibition rate was 7.55% during 10 mg/L PS nanoplastics treatment at 9 d. However, the inhibitory effect gradually weakened with the prolongation of exposure time. Interestingly, algal growth was promoted for 1–5 mg/L nanoplastics during 15–21 d exposure. Transcriptomic analysis explained that the inhibitory effect of nanoplastics could be attributed to suppressed gene expression of aminoacyl-tRNA synthetase that resulted in the reduced synthesis of related enzymes. The promotion phenomenon may be due to that C. pyrenoidosa defended against nanoplastics stress by promoting cell proliferation, regulating intracellular osmotic pressure, and accelerating the degradation of damaged proteins and organs. This study is conducive to provide theoretical basis for evaluating the actual hazard of nanoplastics to aquatic organisms.

Insufficient evidence exists regarding the visible physiological toxic endpoints of MPs exposures on zebrafish larvae due to their small sizes. Herein, the impacts of micro-polystyrene particles (μ-PS) and 100 nm polystyrene particles (n-PS) on the toxicity of cadmium (Cd) through altering neutrophil expressions were identified and quantified in the transgenic zebrafish (Danio rerio) larvae Tg(lyz:DsRed2), and the effects were size-dependent. When exposed together with μ-PS, the amount of neutrophils in Cd treated zebrafish larvae decreased by 25.56% through reducing Cd content in the larvae. By contrast, although n-PS exposure caused lower Cd content in the larvae, the expression of neutrophils under their combined exposure remained high. The mechanism of immune toxicity was analyzed based on the results of metabonomics. n-PS induced high oxidative stress in the larvae, which promoted taurine metabolism and unsaturated fatty biosynthesis in n-PS + Cd treatment. This observation was accordance with the significant inhibition of the activities of superoxide dismutase and catalase enzymes detected in their combined treatment. Moreover, n-PS promoted the metabolic pathways of catabolic processes, amino acid metabolism, purine metabolism, and steroid hormone biosynthesis in Cd treated zebrafish larvae. Nanoplasctis widely coexist with other pollutants in the environment at relatively low concentrations. We conclude that more bio-markers of immune impact should be explored to identify their toxicological mechanisms and mitigate the effects on the environment.

Copper (Cu) is a vital micronutrient required for numerous fundamental biological processes, but excessive Cu poses potential detrimental effects on public and ecosystem health. However, the molecular details linking endoplasmic reticulum (ER) stress and apoptosis in duck renal tubular epithelial cells have not been fully elucidated. In this study, duck renal tubular epithelial cells exposed to Cu sulfate (CuSO₄) (0, 100 and 200 μM) and a PERK inhibitor (GSK2606414, GSK, 1 μM) for 12 h were used to investigate the crosstalk between ER stress and apoptosis under Cu exposure. Cell and ER morphological and functional characteristics, intracellular calcium (Ca²⁺) levels, apoptotic rates, ER stress and apoptosis-related mRNA and protein levels were examined. The results showed that excessive Cu could cause ER expansion and swelling, increase the expression levels of ER stress-associated genes (PERK, eIF2α, ATF4 and CHOP) and proteins (p-PERK and CHOP), induce intracellular Ca²⁺ overload, upregulate the expression levels of apoptosis-associated genes (Bax, Bak1, Caspase9 and Caspase3) and the cleaved-Caspase3 protein, downregulate Bcl-xl and Bcl2 mRNA levels and trigger apoptosis. PERK inhibitor treatment could ameliorate the above changed factors caused by Cu. In conclusion, these findings indicate that excessive Cu could trigger ER stress via activation of the PERK/ATF4/CHOP signaling pathway and that ER stress might aggravate Cu-induced apoptosis in duck renal tubular epithelial cells.

Urban Heat Island (UHI) is posing a significant challenge due to growing urbanisations across the world. Green infrastructure (GI) is popularly used for mitigating the impact of UHI, but knowledge on their optimal use is yet evolving. The UHI effect for large cities have received substantial attention previously. However, the corresponding effect is mostly unknown for towns, where appreciable parts of the population live, in Europe and elsewhere. Therefore, we analysed the possible impact of three vegetation types on UHI under numerous scenarios: baseline/current GI cover (BGI); hypothetical scenario without GI cover (HGI-No); three alternative hypothetical scenarios considering maximum green roofs (HGR-Max), grasslands (HG-Max) and trees (HT-Max) using a dispersion model ADMS-Temperature and Humidity model (ADMS-TH), taking a UK town (Guildford) as a case study area. Differences in an ambient temperature between three different landforms (central urban area, an urban park, and suburban residential area) were also explored. Under all scenarios, the night-time (0200 h; local time) showed a higher temperature increase, up to 1.315 °C due to the lowest atmospheric temperature. The highest average temperature perturbation (change in ambient temperature) was 0.563 °C under HGI-No scenario, followed by HG-Max (0.400 °C), BGI (0.343 °C), HGR-Max (0.326 °C) and HT-Max (0.277 °C). Furthermore, the central urban area experienced a 0.371 °C and 0.401 °C higher ambient temperature compared with its nearby suburban residential area and urban park, respectively. The results allow to conclude that temperature perturbations in urban environments are highly dependent on the type of GI, anthropogenic heat sources (buildings and vehicles) and the percentage of land covered by GI. Among all other forms of GI, trees were the best-suited GI which can play a viable role in reducing the UHI. Green roofs can act as an additional mitigation measure for the reduction of UHI at city scale if large areas are covered.

Inhalation represents the most prevalent route of exposure with Thorium-232 compounds (Th-nitrate/Th-dioxide)/Th-containing dust in real occupational scenario. The present study investigated the mechanism of Th response in normal human alveolar epithelial cells (WI26), exposed to Th-nitrate or colloidal Th-dioxide (1–100 μg/ml, 24–72 h). Assessment in terms of changes in cell morphology, cell proliferation (cell count), plasma membrane integrity (lactate dehydrogenase leakage) and mitochondrial metabolic activity (MTT reduction) showed that Th-dioxide was quantitatively more deleterious than Th-nitrate to WI26 cells. TEM and immunofluorescence analysis suggested that Th-dioxide followed a clathrin/caveolin-mediated endocytosis, however, membrane perforation/non-endocytosis seemed to be the mode of Th internalization in cells exposed to Th-nitrate. Th-estimation by ICP-MS showed significantly higher uptake of Th in cells treated with Th-dioxide than with Th-nitrate at a given concentration. Both Th-dioxide and nitrate were found to increase the level of reactive oxygen species, which seemed to be responsible for lipid peroxidation, alteration in mitochondrial membrane potential and DNA-damage. Amongst HSPs, the protein levels of HSP70 and HSP90 were affected differentially by Th-nitrate/dioxide. Specific inhibitors of ATM (KU55933) or HSP90 (17AAG) were found to increase the Th- cytotoxicity suggesting prosurvival role of these signaling molecules in rescuing the cells from Th-toxicity.

Groundwater flow through aquifer soils or packed bed systems can fluctuate for various reasons, which could affect the concentration of natural colloids and per- and polyfluoroalkyl substances (PFAS) in the pore water. In such cases, PFAS concentration could either decrease due to matrix diffusion of PFAS or increase by the detachment of colloids carrying PFAS. Yet, the effect of flow fluctuation on PFAS transport or release in porous media has not been examined. To examine the relative importance of either process, we interrupted the flow during an injection of groundwater spiked with perfluorobutanoic acid (PFBA), perfluorooctanoic acid (PFOA), and bromide as conservative tracer through clay-rich soil, so that diffusive transport would be prominent during flow interruption. After flow interruption, the PFAS concentration did not decrease indicating an insignificant contribution of matrix diffusion. The concentration increased, potentially due to enhanced release of colloid-associated PFAS. Analysis of samples before and after flow interruption by particle size analysis and SEM confirmed an increase in soil colloid concentration after the flow interruption. XRD analysis of soil and the colloids proved that PFAS were associated with specific sites of the colloids. Due to a higher affinity of PFOA to soil colloids, the total PFOA concentration in the effluent samples increased more than PFBA after the flow interruption process. The results indicate that colloids may have a disproportionally higher role in the transport of PFAS in conditions that release colloids from porous media. Thus, fluctuations in groundwater flow can increase this colloid facilitated mobility of PFAS.

The mechanisms of soot’s photochemistry are still unclear, especially, how the microstructure and composition of soot influence its photoactivity. In the current study, we started with the exploration of the microstructure of soot particles and gained new insights. The elemental-carbon fraction of soot (E-soot), considered the core component of soot and can reflect the intrinsic characteristics of soot, was extracted by organic solvents and characterized in terms of structure and chemical reactivity. The intrinsic structure of E-soot was found to be more analogous to reduced graphene oxide than to graphene, in terms of containing similar levels of defective sites such as oxygen-containing functional groups and environmentally persistent free radicals, as well as exhibiting similar optoelectronic performance. The generation of reactive oxygen species via an electron transfer pathway under visible light suggests that reduced graphene oxide-like E-soot can serve as a potential carbo-photocatalyst, which facilitates elucidating the mechanism of E-soot’s role during soot’s photochemical aging. Our study reveals the intrinsic structure of soot and its role in photo-triggered reactive oxygen species production, which is vital for atmospheric and health effects.

Microplastics are continuously released into the terrestrial environment from sources where they are used and produced. These microplastics accumulate in soils, sediments, and freshwater bodies, and some are conveyed via wind and water to the oceans. The concentration gradient between terrestrial inland and coastal regions, the factors that influence the concentration, and the fundamental transport processes that could dynamically affect the distribution of microplastics are unclear. We analyzed microplastic concentration reported in 196 studies from 49 countries or territories from all continents and found that microplastic concentrations in soils or sediments and surface water could vary by up to eight orders of magnitude. Mean microplastic concentrations in inland locations such as glacier (191 n L⁻¹) and urban stormwater (55 n L⁻¹) were up to two orders of magnitude greater than the concentrations in rivers (0.63 n L⁻¹) that convey microplastics from inland locations to water bodies in terrestrial boundary such as estuaries (0.15 n L⁻¹). However, only 20% of studies reported microplastics below 20 μm, indicating the concentration in these systems can change with the improvement of microplastic detection technology. Analysis of data from laboratory studies reveals that biodegradation can also reduce the concentration and size of deposited microplastics in the terrestrial environment. Fiber percentage was higher in the sediments in the coastal areas than the sediments in inland water bodies, indicating fibers are preferentially transported to the terrestrial boundary. Finally, we provide theoretical frameworks to predict microplastics transport and identify potential hotspots where microplastics may accumulate.

Ambient fine particulate matter (PM₂.₅) can change the expression profile of microRNAs (miRs), which may play important roles in mediating inflammatory responses. The present study attempts to investigate the roles of miR-146a-5p in regulating cytokine expression in a human monocytic leukemia cell line (THP-1). Four types of PM₂.₅ extracts obtained from Beijing, China, were subjected to cytotoxic tests in THP-1 cells. These four PM₂.₅ extracts included two water extracts collected from non-heating and heating season (WN and WH), and two organic extracts from non-heating and heating season (DN and DH). Firstly, the four PM₂.₅ extracts caused cytotoxicity, oxidative stress responses, cytokine gene expressions and interleukin 8 (IL-8) release in THP-1 cells, with WH showing the highest cytotoxicity, WN showing the highest oxidative stress and inflammatory responses. Additionally, we observed expression of miR-146a-5p was significantly increased, with the maximal response of six folds in WN group. Cellular autophagy was initiated by PM₂.₅ indicated by related protein and gene expressions. Both RNA interference and autophagy inhibitor were applied to interrupt autophagy process in THP-1 cells. Autophagy dysfunction could alleviate IL-8 expression, suggesting autophagy process regulated cytokine expression and inflammatory response caused by PM₂.₅. A chemical inhibitor was applied to inhibit the function of miR-146a-5p, and then the expressions of IL-8 and autophagic genes were significantly aggravated. Meanwhile, two target genes of miR-146a-5p, interleukin-1 associated-kinase-1 (IRAK1) and tumor-necrosis factor receptor-associated factor-6 (TRAF6) were increased dramatically, which also played important roles in regulation of autophagy. These data suggested miR-146a-5p negatively modulated cytokine expression caused by PM₂.₅ via autophagy process through the target genes of IRAK1 and TRAF6. Our findings raised the concerns of the changes of miR expression profile and following responses caused by PM₂.₅.

Effects of commercial sand mining on aquatic diversity are of increasing global concern, especially in parts of some developing countries. However, understanding of this activity on the diversity of macroinvertebrates remains focused on the α component of species diversity, rather than community functioning. Thus, there remains much uncertainty regarding how each component of taxonomic (TD) and functional (FD) diversity respond to the activity both in freshwater and marine environments. Here, we assessed the effect of sand dredging on α, β and γ components of TD and FD during different dredging periods based on the response of macroinvertebrate communities over 4 years in the second largest freshwater lake in China. After three years of active dredging, substantial reductions in each component (α, β and γ) of TD and FD were observed within the dredged area. Moreover, after one year of natural recovery, a distinct restoration was observed with an obvious return in multiple facets of TD and FD indices. No such changes were observed within the adjacent and reference areas. Decreases in the multiple components of TD and FD within the dredged area were most likely associated with the direct extraction of substrate and associated benthic fauna and indirect variations of the water and sediment environment (e.g., increases in water depth and decreases in %Clay). Furthermore, dispersal processes and mass effects mainly contributed to the maintenance of TD and FD during the dredged and recovery stages. In addition, the fast recovery of TD and FD was also related to the simple taxonomic structure and highly connected nature of the study area. Our results suggest that a more precise experimental design (BACI) should be pursued to avoid potentially confounding effects (e.g., natural disturbance) because the sensitivity of diversity indices depends upon different experimental designs. Moreover, measurement of the impacts of sand dredging on macroinvertebrate diversity can be undertaken within a rigorous framework for better understanding the patterns and processes of each component of TD and FD under the sand dredging disturbance.