The Yellow River is the second largest river in China. Carbon transport by the Yellow River has significant influence on riverine carbon cycles in Asia. During the wet season, the riverine carbon was mainly found in dissolved form, i.e., dissolved organic carbon (DOC), along the entire course of the river. The distinct spatial variations of DOC concentration were observed at different reaches of the mainstream (p < 0.01), while the highest mean DOC concentration was generally observed at midstream (4.13 ± 0.91 mg/L). Carbon stable isotope analysis δ¹³C and C: N ratio of DOC, evidenced the sources of DOC in headwater and upstream were primarily the terrestrial plants (94% and 61%), but it was changed to soil organic matter (SOM) in mid- and downstream (36% and 37%), and the contribution of sewage to DOC were also increased to 17% and 18%. In the whole mainstream of the Yellow River, water temperature (WT) had a significant impact on DOC concentration, and it could explain 67% of the DOC variance. However, in a large catchment, the driving mechanisms on the DOC variations in headwaters will not necessarily be those controlling DOC trends in downstream. The study firstly quantified, in headwater and upstream, the natural factors explained as much as 65% and 73% of the DOC variations, respectively. In mid- and downstream areas, DOC was significantly influenced by the amount of wastewater discharged by the industry and the use of chemical fertilizers (p < 0.05). These findings may facilitate a better assessment of global riverine carbon cycling and may help to reveal the importance of the balance between development and environmental sustainability with the changing DOC transport features in the Yellow River due to human disturbances.

As a common natural phenomenon, corpse decomposition may lead to serious environmental pollution such as nitrogen pollution. However, less is known about antibiotic resistance genes (ARGs), an emerging contaminant, during corpse degradation. Here, ARGs and microbiome in three soil types (black, red and yellow soil) have been investigated between experimental and control groups based on next-generation sequencing and high-throughput quantitative PCR techniques. We found that the absolute abundance of total ARGs and mobile genetic elements (MGEs) in the experimental groups were respectively enriched 536.96 and 240.60 times in different soil types, and the number of ARGs in experimental groups was 7–25 more than that in control groups. For experimental groups, the distribution of ARGs was distinct in different soil types, but sulfonamide resistance genes were always enriched. Corpse decomposition was a primary determinant for ARGs profiles. Microbiome, NH₄⁺ concentrates and pH also significantly affected ARGs profiles. Nevertheless, soil types had few effects on ARGs. For soil microbiome, some genera were elevated in experimental groups such as the Ignatzschineria and Myroides. The alpha diversity is decreased in experimental groups and microbial community structures are different between treatments. Additionally, the Escherichia and Neisseria were potential pathogens elevated in experimental groups. Network analysis indicated that most of ARGs like sulfonamide and multidrug resistance genes presented strong positively correlations with NH₄⁺ concentrates and pH, and some genera like Ignatzschineria and Dysgonomonas were positively correlated with several ARGs such as aminoglycoside and sulfonamide resistance genes. Our study reveals a law of ARGs’ enrichment markedly during corpse decomposing in different soil types, and these ARGs contaminant maintaining in environment may pose a potential threat to environmental safety and human health.

Elevated CO₂ concentrations can change the multi-level nutritional relationship of the ecosystem through the cascading effect of the food chain. To date, few studies have investigated the effects of elevated CO₂ concentration on the Araneae species through the tritrophic system. Hylyphantes graminicola (Araneae: Linyphiidae) is distributed widely in Asia and is a dominant predator in cotton fields. This study investigated chemical components in the food chain of cotton (Gossypium hirsutum)—cotton aphid (Aphis gossypii)—predator (H. graminicola) and compared the development, reproduction, and predation of H. graminicola under ambient (400 ppm) and elevated concentration of CO₂ (800 ppm). The results showed that the elevated CO₂ concentration increased the chemicals of cotton and cotton aphid, but it did not affect the nutrients, development, reproduction, and predation of the spider. However, the survival rate of the spider was significantly decreased in elevated CO₂. The results will further our understanding of the role of natural enemies in an environment with elevated CO₂ concentration.

Central Asia is one of many regions worldwide that face severe water shortages; nevertheless, water pollution in this region exacerbates the existing water stress and increases the risk of regional water conflicts. In this study, we perform an extensive literature review, and the data show that water pollution in Central Asia is closely linked to human activities. Within the Asian Gold Belt, water pollution is influenced mainly by mining, and the predominant pollutants are heavy metals and radionuclides. However, in the irrigated areas along the middle and lower reaches of inland rivers (e.g., the Amu Darya and Syr Darya), water pollution is strongly associated with agriculture. Hence, irrigated areas are characterized by high concentrations of ammonia, nitrogen, and phosphorus. In addition, the salinities of rivers and groundwater in the middle and lower reaches of inland rivers generally increase along the flow path due to high rates of evaporation. Soil salinization and frequent salt dust storms in the Aral Sea basin further increase the pollution of surface water bodies. Ultimately, the pollution of surface water and groundwater poses risks to human health and deteriorates the ecological environment. To prevent further water pollution, joint monitoring of the surface water and groundwater quantity and quality throughout Central Asia must be implemented immediately.

Per-and poly-fluorinated alkyl substances (PFAS) are a group of chemicals used in a wide variety of commercial products and industrial applications. These chemicals are persistent, can accumulate in humans' and animals' tissues and in the environment, representing an increasing concern due to their moderate to highly toxicity. Their global distribution, persistence and toxicity led to an urgent need to investigate bioaccumulation also in marine species. In 2013 PFAS contamination was detected in a vast area in Veneto region, mainly in Adige and Brenta rivers. In order to investigate any relevant presence of these substances in marine vertebrates constantly living in the area, PFAS were measured in hepatic tissue samples of 20 bottlenose dolphins (Tursiops truncatus) stranded along the northern Adriatic Sea coastline between 2008 and 2020. Using high performance liquid chromatography-mass spectrometry, 17 target PFAS (PFBA, PFPeA, PFHxA, PFHpA, PFOA, PFNA, PFDA, PFUnA, PFDoA, PFTrDA, PFTeDA, PFBS, PFHxS, PFOS, PFDS, PFHpS, PFPeS), were quantified in the samples. PFAS profiles were generally composed of the same five dominant PFAS (PFOS > PFUnA > PFDA ≈ PFDoA ≈ PFTrDA). The greatest PFOS concentration found was 629,73 ng/g wet weight, and PFOS accounted until 71% in the PFAS profiles. No significant differences between sexes were found, while calves showing higher mean values than adults, possibly indicating an increasing ability in the elimination of PFAS with age. Finally, a temporal analysis was carried out considering three different periods of time, but no temporal differences in concentrations were found. The results suggest that long-chain PFAS are widespread in bottlenose dolphins along the North Adriatic Sea. Furthermore, they represent a baseline to investigate the impact of PFAS on marine mammals’ conservation and health. Filling an important gap in the knowledge of PFAS accumulation in bottlenose dolphins, this study highlights the relevant role of Environmental and Tissue Banks for retrospective analyses on emergent contaminants.

Sulfate (SO₄•⁻) and hydroxyl-based (HO•) radical are considered potential agents for As(III) removal from aquatic environments. We have reported the synergistic role of SO₄•⁻ and HO• radicals for As(III) removal via facile synthesis of biochar-supported SO₄•⁻ species. MoS₂−modified biochar (MoS₂/BC), iron oxide-biochar (FeOₓ@BC), and MoS₂−modified iron oxide-biochar (MoS₂/FeOₓ@BC) were prepared and systematically characterized to understand the underlying mechanism for arsenic removal. The MoS₂/FeOx@BC displayed much higher As(III) adsorption (27 mg/g) compared to MoS₂/BC (7 mg/g) and FeOx@BC (12 mg/g). Effects of kinetics, As(III) concentration, temperature, and pH were also investigated. The adsorption of As(III) by MoS₂/FeOx@BC followed the Freundlich adsorption isotherm and pseudo-second-order, indicating multilayer adsorption and chemisorption, respectively. The FTIR and XPS analysis confirmed the presence of Fe–O bonds and SO₄ groups in the MoS₂/FeOₓ@BC. Electron paramagnetic resonance (EPR) and radical quenching experiments have shown the generation of SO₄•⁻ radicals as predominant species in the presence of MoS₂ and FeOₓ in MoS₂/FeOx@BC via radical transfer from HO• to SO₄²⁻. The HO• and SO₄•⁻ radicals synergistically contributed to enhanced As(III) removal. It is envisaged that As(III) initially adsorbed through electrostatic interactions and partially undergoes oxidation, which is finally adsorbed to MoS₂/FeOx@BC after being oxidized to As(V). The MoS₂/FeOₓ@BC system could be considered a novel material for effective removal of As(III) from aqueous environments owing to its cost-effective synthesis and easy scalability for actual applications.

Cigarette smoke (CS) affects immune functions, leading to severe outcomes in smokers. Robust evidence addresses the immunotoxic effects of combustible tobacco products. As heat-not-burn tobacco products (HNBT) vaporize lower levels of combustible products, we here compared the effects of cigarette smoke (CS) and HNBT vapor on Jurkat T cells. Cells were exposed to air, conventional cigarettes or heatsticks of HNBT for 30 min and were stimulated or not with phorbol myristate acetate (PMA). Cell viability, proliferation, reactive oxygen species (ROS) production, 8-OHdG, MAP-kinases and nuclear factor κB (NFκB) activation and metallothionein expression (MTs) were assessed by flow cytometry; nitric oxide (NO) and cytokine levels were measured by Griess reaction and ELISA, respectively. Levels of metals in the exposure chambers were quantified by inductively coupled plasma mass spectrometry. MT expressions were quantified by immunohistochemistry in the lungs and liver of C57Bl/6 mice exposed to CS, HNBT or air (1 h, twice a day for five days: via inhalation). While both CS and HBNT exposures increased cell death, CS led to a higher number of necrotic cells, increased the production of ROS, NO, inflammatory cytokines and MTs when compared to HNBT-exposed cells, and led to a higher expression of MTs in mice. CS released higher amounts of metals. CS and HNBT exposures decreased PMA-induced interleukin-2 (IL-2) secretion and impaired Jurkat proliferation, effects also seen in cells exposed to nicotine. Although HNBT vapor does not activate T cells as CS does, exposure to both HNBT and CS suppressed proliferation and IL-2 release, a pivotal cytokine involved with T cell proliferation and tolerance, and this effect may be related to nicotine content in both products.

Intentional or incidental thermal changes inevitably occur during the lifecycle of plastics. High temperatures accelerate the aging of plastics and promote their fragmentation to microplastics (MPs). However, there is little information available on the release of MPs after fires. In this study, an atomic force microscope combined with nanoscale infrared analysis was used to demonstrate the physicochemical properties of polypropylene (PP) plastics under simulated fire scenarios. Results showed that the chemical composition and relative stiffness of heat-treated plastic surfaces changed, significantly enhancing the generation of MPs under external forces; over (2.1 ± 0.2) × 10⁵ items/kg abundance of MPs released from PP which were burned at 250 °C in air and trampled by a person. The leaching of antimony (Sb) from MPs in different solutions first increased and then decreased with increasing temperature, reaching a maximum at 250 °C. Higher concentrations of humic acid (10 vs 1 mg/L) caused a greater release of Sb. Furthermore, the tap water leachates of PP burned at 250 °C had the greatest effect on the growth and photosynthetic activity of Microcystis aeruginosa. Our results suggest fires as a potential source of MPs and calls for increased focus on burning plastics in future research.

Rivers are viewed as major pathways of microplastic transport from terrestrial areas to marine ecosystems. However, there is paucity of knowledge on the dispersal pattern and transport of microplastics in river sediments. In this study, a three dimensional hydrodynamic and particle transport modelling framework was created to investigate the dispersal and transport processes of microplastic particles commonly present in the environment, namely, polyethylene (PE), polypropylene (PP), polyamide (PA), and polyethylene terephthalate (PET) in river sediments. The study outcomes confirmed that sedimental microplastics with lower density would have higher mobility. PE and PP are likely to be transported for a relatively longer distance, while PA and PET would likely accumulate close to source points. High water flow would transport more microplastics from source points, and high flow velocity in bottom water layer are suggested to facilitate the transport of sedimental microplastics. Considering the limited dispersal and transport, the study outcomes indicated that river sediments would act as a sink for microplastic pollutants instead of being a transport pathway. The patchiness associated with the hotspots of different plastic types is expected to provide valuable information for microplastic source tracking.

Assessment of microplastic impacts in biota is challenging due to the complex behavior of the test particles and their interactions with other particulates, including microorganisms, in the environment. To disentangle responses to microplastic exposure from those to other suspended solids, both microplastic and natural particles must be present in the test system. We evaluated how microplastic, non-plastic particles, and biofilms interacted in their effects on survivorship using acute toxicity assay with Daphnia magna. The animals were exposed to microplastic and kaolin at different concentrations of suspended solids (SS; 10, 100, and 1000 mg/L) with a varying microplastic contribution (%MP; 0–80%) and biofilm (presence/absence) associated with the solids. Also, we examined how these exposure parameters (SS, %MP, and Biofilm) affected aggregate formation that was analyzed using particle size distribution data. Under the exposure conditions, Daphnia mortality was primarily driven by SS concentration but ameliorated by both microplastic and biofilm. The ameliorating effects were related to increased particle aggregation in the presence of biofilm and high %MP. In addition, a weak yet significant positive effect of the biofilm on the survivorship was observed, presumably, due to microbial food supply to the daphniids in the exposure system; the bacteria were utilized at the absence of other food. Therefore, the effects of both natural and anthropogenic particulates depend on the particle behavior and aggregation in the water governed by microbial communities and physicochemical properties of the particles, which must be taken into account in the hazard assessment of plastic litter.