Long term monitoring of atmospheric wet and dry depositions and associated nutrients fluxes was conducted on the coast of Japan facing the East China Sea continuously for 1 year and 2 months, with the origin of air mass investigated based on isotope analyses (Sr, Nd, and NO₃). During the same period, intensive observations of ocean conditions and the chemical composition of sinking particles collected using sediment traps were conducted to investigate the effects of atmospheric deposition-derived nutrients on phytoplankton blooms. Dry-deposition-derived nutrient inputs to the surface ocean were larger during autumn to spring than in summer due to the effect of continental air mass occasionally carrying Asian dust (yellow sand). However, these nutrients fluxes were limited (1.1–1.5 mg-N m⁻² day⁻¹ on average) and didn't appear to cause phytoplankton blooms through the year. Although average dissolved inorganic nitrogen (DIN) concentrations in rainwater were lower in oceanic air masses compared to continental air masses, wet-deposition-derived nutrient inputs to the surface ocean on rainy days during the summer (26.0 mg-N m⁻² day⁻¹ on average) were large due to higher precipitation from oceanic air masses. Wet-deposition-derived nutrients significantly increased nutrient concentrations in the surface ocean and seemed to cause phytoplankton blooms in the warm rainy season when nutrients in the surface were depleted due to increased stratification. The increase in phytoplankton biomass was reflected in increased particle sinking into the bottom layer, as well as changing chemical characteristics. The supply of flesh phytoplankton-derived labile organic matter into the bottom layer could be expected to promote rapid bacterial decomposition and contribute to the formation of hypoxic water masses in early summer when the ocean was strongly stratified. Atmospheric deposition-derived nutrients in East Asia will have important impacts on not only the oligotrophic outer ocean but also surrounding coastal areas in the warm rainy season.

With the fast growth of the production and application of engineered nanomaterials (ENMs), nanoparticles (NPs) that escape into the environment have drawn increasing attention due to their ecotoxicological impacts. Motile microalgae are a type of primary producer in most ecosystems; however, the impacts of NPs on the motility of microalgae have not been studied yet. So the toxic impacts of three common metal oxide NPs (nTiO₂, nZnO, and nFe₂O₃) on swimming speed and locomotion mode of a marine microalgae, Platymonas subcordiformis, were investigated in this study. Our results demonstrated that both the velocity and linearity (LIN) of swimming were significantly decreased after the exposure of P. subcordiformis to the tested NPs. In addition, the obtained data indicate that NPs may suppress the motility of P. subcordiformis by constraining the energy available for swimming, as indicated by the significantly lower amounts of intracellular ATP and photosynthetic pigments and the lower activities of enzymes catalyzing glycolysis. Incubation of P. subcordiformis with the tested NPs generally resulted in the overproduction of reactive oxygen species (ROS), aggravation of lipid peroxidation, and induction of antioxidant enzyme activities, suggesting that imposing oxidative stress, which may impair the structural basis for swimming (i.e. the membrane of flagella), could be another reason for the observed motility suppression. Moreover, NP exposure led to significant reductions in the cell viability of P. subcordiformis, which may be due to the disruption of the energy supply (i.e., photosynthesis) and ROS-induced cellular damage. Our results indicate that waterborne NPs may pose a great threat to motile microalgae and subsequently to the health and stability of the marine ecosystem.

Artificial light at night (ALAN) is a pervasive form of pollution largely affecting wildlife, from individual behaviour to community structure and dynamics. As nocturnal mammals, bats are often adversely affected by ALAN, yet some “light-opportunistic” species exploit it by hunting insects swarming near lights. Here we used two potentially competing pipistrelle species as models, Kuhl’s (Pipistrellus kuhlii) and common (Pipistrellus pipistrellus) pipistrelles, both known to forage in artificially illuminated areas. We set our study in a mountainous area of central Italy, where only recently did the two species become syntopic. We applied spatial modelling and radiotracking to contrast potential vs. actual environmental preferences by the two pipistrelles. Species distribution models and niche analysis showed a large interspecific niche overlap, including a preference for illuminated areas, presenting a potential competition scenario. Pipistrellus pipistrellus association with ALAN, however, was weakened by adding P. kuhlii as a biotic variable to the model. Radiotracking showed that the two species segregated habitats at a small spatial scale and that P. kuhlii used artificially illuminated sites much more frequently than P. pipistrellus, despite both species potentially being streetlamp foragers. We demonstrate that ALAN influences niche segregation between two potentially competing species, confirming its pervasive effects on species and community dynamics, and provide an example of how light pollution and species’ habitat preferences may weave a tapestry of complex ecological interactions.

Light-absorbing organic aerosols, also known as brown carbon (BrC), enhance the warming effect of the Earth’s atmosphere. The seasonal and spatial variability of BrC absorption properties is poorly constrained and accounted for in the climate models resulting in a substantial underestimation of their radiative forcing estimates. This study reports seasonal and spatial variability of absorption properties and simple forcing efficiency of light-absorbing water-soluble organic carbon (WSOC, SFEWSOC) by utilizing current and previous field-based measurements reported mostly from Asia along with a few observations from Europe, the USA, and the Amazon rainforest. The absorption coefficient of WSOC at 365 nm (bₐbₛ₋₃₆₅) and the concentrations of carbonaceous species at Kanpur were about an order of magnitude higher during winter than in the monsoon season owing to differences in the boundary layer height, active sources and their strengths, and amount of seasonal wet precipitation. The WSOC aerosols during winter exhibited ∼1.6 times higher light absorption capacity than in the monsoon season at Kanpur site. The assessment of spatial variability of the imaginary component of the refractive index spectrum (kλ) across South Asia has revealed that it varies from ∼1 to 2 orders of magnitude and light absorption capacity of WSOC ranges from 3 to 21 W/g. The light absorption capacity of WSOC aerosols exhibited less spatial variability across East Asia (5–13 W/g) when compared to that in the South Asia. The photochemical aging of WSOC aerosols, indicated by the enhancement in WSOC/OC ratio, was linked to degradation in their light absorption capacity, whereas the absorption Ångström exponent (AAE) remained unaffected. This study recommends the adoption of refined climate models where sampling regime specific absorption properties are calculated separately, such that these inputs can better constrain the model estimates of the global effects of BrC.

As an emerging pollutant, uranium poses serious concerns to ecological and human health. The kidney has been established as a major deposition site and the most sensitive target organ for uranium poisoning, and the underlying toxicological mechanisms have been associated with oxidative stress and mitochondrial respiration. However, the identities of key molecular targets in uranium-induced toxicity remain elusive. In this study, we comprehensively evaluated the in vitro effects of uranium on ten critical enzymes in the mitochondrial respiration pathway and discovered that respiratory chain complex IV (cytochrome c oxidase) and complex V (ATP synthase) were strongly inhibited. The inhibitory effects were validated with mitochondria from human renal proximal tubule cells—the most affected renal site in uranium poisoning. The IC₅₀ values (around 1 mg/L) are physiologically relevant, as they are comparable to known kidney accumulation levels in uranium poisoning. In addition, these inhibitory effects could explain the well-documented uranium-induced reactive oxygen species generation and mitochondrial alterations. In conclusion, cytochrome c oxidase and ATP synthase are possibly key molecular targets underlying the toxic effects of uranium.

Phenanthrene (Phe) is a tricyclic polycyclic aromatic hydrocarbon with high bioavailability under natural exposure. However, there are few studies on the reproductive toxicity of Phe in mammals. In this study, male Kunming mice were gavaged once every two days with Phe (5, 50, and 500 ng/kg) for 28 weeks. The accumulation levels of Phe in the testis were dose-dependently increased. Histopathological staining showed that Phe exposure reduced the number of spermatogonia, sperm and Sertoli cells. The percentage of testicular apoptotic cells was significantly increased, which was further verified by the upregulated BAX protein. The expression of the GDNF/PI3K/AKT signaling pathway was downregulated, which might suppress the self-renewal and differentiation of spermatogonial stem cells. Meanwhile, Phe exposure inhibited the expression of Sertoli cell markers (Fshr, WT1, Sox9) and the Leydig cell marker Cyp11a1, indicating damage to the function of Sertoli cells and Leydig cells. Serum estrogen and testicular estrogen receptor alpha were significantly upregulated, while androgen receptor expression was downregulated. These alterations might be responsible for impaired spermatogenesis. This study provides new insights for evaluating the reproductive toxicity and potential mechanisms of Phe in mammals.

Microplastics are emerging contaminants and widely distributed in the environment. They are considered as a vector of numerous organic pollutants including antibiotics in aquatic environments and thereby influence their distribution and transport behaviors. However, the effects of microplastics on the environmental behavior of antibiotics in soils remain largely unclear. In this paper, the influence of polyamide (PA) microplastics on sorption and transport of the selected antibiotic [oxytetracycline (OTC)] in a sandy loamy soil was studied by performing batch and column experiments. Results show that PA microplastics increase the pH of reaction systems, which contributes to OTC sorption onto the tested soils. However, altering pH is not the key influencing mechanism because the overall sorption capacity decreases slightly after adding PA microplastics, which can be attributed to the dilution effect. Reduction of OTC sorption by adding microplastics promotes the migration of OTC in the tested soil, which could be demonstrated by the results of column experiments that the breakthrough of OTC occurs earlier with an increasing content of PA microplastics. According to the fitting parameters of HYDRUS−1D model, PA microplastics can affect the transport of OTC by altering the soil pore structure and dispersion coefficient. These results provide new insight into the interaction between microplastics and organic pollutants in soil environments.

Urban turfgrass ecosystems are expected to increase at unprecedented rates in upcoming decades, due to the increasing population density and urban sprawl worldwide. However, so far urban turfgrasses are among the least understood of all terrestrial ecosystems concerning their impact on biogeochemical N cycling and associated nitrous oxide (N₂O) and nitric oxide (NO) fluxes. In this study, we aimed to characterize and quantify annual N₂O and NO fluxes from urban turfgrasses dominated by either C4, warm-season species or C3, cool-season and shade-enduring species, based on year-round field measurements in Beijing, China. Our results showed that soil N₂O and NO fluxes varied substantially within the studied year, characterizing by higher emissions during the growing season and lower fluxes during the non-growing season. The regression model fitted by soil temperature and soil water content explained approximately 50%–70% and 31%–38% of the variance in N₂O and NO fluxes, respectively. Annual cumulative emissions for all urban turfgrasses ranged from 0.75 to 1.27 kg N ha⁻¹ yr⁻¹ for N₂O and from 0.30 to 0.46 kg N ha⁻¹ yr⁻¹ for NO, both are generally higher than those of Chinese natural grasslands. Non-growing season fluxes contributed 17%–37% and 23%–30% to the annual budgets of N₂O and NO, respectively. Our results also showed that compared to the cool-season turfgrass, annual N₂O and NO emissions were greatly reduced by the warm-season turfgrass, with the high root system limiting the availability of inorganic N substrates to soil microbial processes of nitrification and denitrification. This study indicates the importance of enhanced N retention of urban turfgrasses through the management of effective species for alleviating the potential environmental impacts of these rapidly expanding ecosystems.

First flush or the first pore volume of effluent eluted from biofilters at the start of rainfall contributes to most pollution downstream because it typically contains a high concentration of bacterial pathogens. Thus, it is critical to evaluate designs that could minimize the release of bacteria during a period of high risk. In this study, we test the hypothesis of whether an addition of iron-based media to biofilter could limit the leaching of Escherichia coli (E. coli), a pathogen indicator, during the first flush. We applied E. coli-contaminated stormwater intermittently in columns packed with a mixture of sand and compost (70:30 by volume, respectively) and iron filings at three concentrations: 0% (control), 3%, and 10% by weight. Columns packed with a mixture of sand and iron (3% or 10%) without compost were used to examine the maximum capacity of iron to remove E. coli. In columns with iron, particularly 10% by weight, the leaching of E. coli during the first flush was 32% lower than the leaching from compost columns, indicating that the addition of iron amendments could decrease first-flush leaching of E. coli. We attribute this result to the ability of iron to increase adsorption and decrease growth during antecedent drying periods. Although the addition of iron filings increased E. coli removal, the presence of compost decreased the adsorption capacity: exposure of 1 g of iron filings to 1 mg of DOC reduces E. coli removal by 8%. The result was attributed to the alteration of the surface charge of iron and blocking of adsorption sites shared by E. coli and DOC. Collectively, these results indicate that the addition of sufficient amounts of iron media could decrease pathogen leaching in the first flush effluent and increase the overall biofilter performance and protect downstream water quality.