This paper used the multi-region input-output model to calculate the embodied carbon and its industrial structure of China's inter-city industrial trade based on the perspective of value-added trade, depict the structural characteristics of the embodied carbon transfer network, and the mechanism of the embodied carbon transfer network is revealed through the exponential random graph model (ERGM). The study found that: The inter-city industrial trade embodied carbon transfer network is dense but without scale, with small world structure and miscompatibility. Resource-intensive and capital-intensive industries contribute more than 90% of the embodied carbon transfer. Cities with high embodied carbon net outflow are mainly resource-based and industrial cities in the Yellow River Basin and the Bohai Rim region, while cities with high embodied carbon net inflow are mainly the national and regional central cities east of Hu Huanyong Line. Large-scale embodied carbon transfer mainly occurs among the cities within the provinces, and the inter-city embodied carbon transfer network has a certain provincial boundary effect. The embodied carbon transfer of provincial cities presents the "core-edge" structure around the provincial central cities. The embodied carbon transfer of inter-provincial cities shows the radial structure from the resource-based cities and industrial cities in the Yellow River basin and the Bohai Rim region to Beijing, Shanghai, Hangzhou, Ningbo, Suzhou, Chongqing, Guangzhou, Guangzhou and Shenzhen and other central cities. In the mechanism of inter-city embodied carbon transfer network, mutualism and preference dependence effect are important endogenous mechanisms. Cities with developed economy, dense population, high per capita consumption level and advanced industry are more inclined to flow into the embodied carbon. Cities with higher comparative advantages and low energy efficiency in resource-based industries are more inclined to outflow embodied carbon. Policy proximity and geographic proximity have a positive impact on the inter-city embodied carbon transfer network, and technical proximity has a negative impact.

This study focuses on five typical lakes in cold-arid areas, analyzing the phosphorus pool capacity and phosphorus migration dynamics of sediments using methods such as phosphorus fractionation, diffusive gradients in thin films (DGT), and the DGT Induced Fluxes in Sediments model (DIFS). Partial least squares path modeling (PLS-PM) was further employed to identify the key driving factors for the endogenous phosphorus pool capacity and migration dynamics in these lakes. The results showed that the average values of total phosphorus (TP_w), total nitrogen (TN_w), and nitrogen-to-phosphorus ratio (TN_w/TP_w) in the water of the five lakes were (0.81 ± 1.31)mg/L, (3.40 ± 1.87)mg/L, and (26.13 ± 22.75), respectively, indicating that these were phosphorus-limited lakes. The average total phosphorus (TP_s) content in surface sediments was (763.48 ± 563.70)mg/kg, with calcium-bound phosphorus (Ca-P) accounting for 51.09% of the TP_s. The comprehensive pollution index (FF) values for sediments indicate a severe pollution level. The biologically available phosphorus (BAP) dissolved active phosphorus (C_DGT-P), and distribution coefficient (K_d) average (193.54 ± 55.94)mg/kg, (0.19 ± 0.14)mg/L, and (11.34 ± 9.29)cm³/g, respectively. All three indicators of phosphorus pool capacity were lower than those in lakes of the eastern plains, reflecting a relatively low phosphorus reservoir capacity in cold and arid lakes. The DIFS model shows that the reaction time (T_c) of the five lakes ranges from 0.004 to 74, 170s, lower than that of lakes in the eastern plains, indicating slower phosphorus migration dynamics and a relatively lower supply rate to the water body. PLS-PM analysis reveals that the primary factor influencing phosphorus reservoir capacity in these lakes was sediment properties (0.64,P<0.05). The main factor influencing phosphorus migration dynamics (0.95, P<0.05) was the environmental conditions of the water bodies, with limited influence from lake trophic state and phytoplankton.

To investigate the relative importance of the bottom-up versus top-down on phytoplankton biomass in the estuary and its adjacent waters of the Yellow River during the water and sediment regulation scheme (WSRS), the study utilized R2V software to extract historical data (2011~2020) on chlorophyll a (Chl a) concentration, environmental factors, and zooplankton abundance in the estuary and its adjacent waters of the Yellow River from the literature. The spatial distribution and interannual variation of Chl a concentration was analyzed, and regression tree models Chl a with environmental and biological factors at different stages of WSRS were developed to explore the controlling factors. The results showed that Chl a concentrations in the estuary and its adjacent waters of the Yellow River generally decreased from the estuary towards offshore areas from 2011 to 2020. As WSRS progressed, the high-value areas gradually shifted to the nearshore northwest of the estuary. Regions with significant interannual variations in Chl a concentrations largely overlapped with high-value areas at each stage. The regression tree model indicated that, with the progression of water and sediment regulation, there was a notable shift in the dominant effects on Chl a concentration. Before WSRS, the top-down effect of zooplankton grazing was the primary driver of Chl a spatial variability. During the water and sediment regulation period, Chl a concentration was mainly controlled by bottom-up effects. In the early WSRS, temperature was the primary driving factor, while in the later stage of WSRS, dissolved inorganic phosphorus (DIP) became the main driving factor. The changes in salinity fronts caused by freshwater flow during WSRS may be an important factor inducing changes in the dominant effects on Chl a concentration.

Sulfate radical (SO₄^•−)-based advanced oxidation processes (SR-AOPs) are characterized by in situ generation of SO₄^•− with strong oxidation capacity, which can effectively degrade a variety of organic pollutants. However, SO₄^•− can transform nitrite (NO₂⁻) and bromide (Br⁻) into toxic nitrated byproducts and halogenated byproducts, respectively. In this study, the mechanisms underlying the formation of nitrated and brominated byproducts on the reaction system in which NO₂⁻ and Br⁻ coexist were systematically investigated. Results showed that three nitrated byproducts, including 2-nitrophenol, 4-nitrophenol, and 2,4-dinitrophenol were produced during the heat-activated persulfate nitrification process. It was observed that nitrophenols accounted for approximately 34.5% of the phenol transformed under reaction conditions of [phenol]= 50µmol/L, [NO₂⁻]=100µmol/L,[PDS]=2mmol/L and temperature of 60℃ C. Once NO₂⁻ was co-present, the formation rate of nitrophenol was significantly accelerated. The conversion rate increased to 46.0% under the same conditions. Br⁻ can be oxidized by SO₄^•− to form reactive bromine species, which rapidly react with NO₂⁻ to form a strong oxidizing agent, nitryl halide. Then nitryl halide reacts with the phenol and plays a key role in promoting the formation of nitrophenol. Note that, Br⁻ is eventually released and acts as a catalyst equivalent. Meanwhile, the presence of NO₂⁻ results in an inhibition of the rate of formation of brominated byproducts, such as dibromoacetic acid. Therefore, the transformation mechanisms of NO₂⁻ and Br⁻ influence each other in SR-AOPs. When they coexist, promote the formation of nitrophenol byproducts but inhibit brominated byproducts.

This study takes the Wujing Road Tunnel in Tianjin as an example to explore the emission characteristics of benzothiazoles (BTs) in particulate, gaseous pollutants, and road dust. The results show that the concentrations of particulate matter, gaseous pollutants, and BTs in road dust exhibit regular patterns, especially the concentration changes of 2-hydroxybenzothiazole (2-OH-BT) and benzothiazole (BT). Since BTs in the enclosed tunnel environment mainly originate from tire wear particles of motor vehicles, 2-OH-BT and BT can serve as important tracers for identifying non-exhaust emissions from motor vehicles. During the tunnel experiment, the daily traffic volume ranged from 11,972 to 16, 157 vehicles per day, the total carbon (TC) concentration was between 10.85and 15.75μg/m³, and the BTs concentration was between 3.33 and 8.41ng/m³. The gas-particle ratio values of 2-mercaptobenzothiazole (MBT), 2-OH-BT, and BT in the tunnel were generally higher than those in the receptor environment, and 2-OH-BT and BT were the dominant gaseous BTs components. This indicates that most MBT, 2-OH-BT, and BT generated from tire wear sources of motor vehicles are released in the gaseous phase, so the gaseous BTs should not be overlooked. For the calculation of motor vehicle emission factors, the average emission factors of organic carbon (OC), elemental carbon (EC), and PM_2.5 in the Wujing Road Tunnel were 2.80, 1.60, and 13.77mg/(km⋅vehicle), respectively. In the health risk assessment model, the daily exposure to BTs through ingestion was the highest. The daily intake for children and adults was 12.03 and 1.29ng/(kg⋅d), respectively. The total daily exposure for children was more than nine times that of adults, indicating that children may face a greater health threat from traffic pollution than adults.

In view of the typically unsatisfactory antibiotics removal performances that were observed in the traditional 'three ponds and two dams' combination process, a new composite packing filter dam was developed. Through the synergetic combination of composite packing balls with a specially designed filter dam structure, highly efficient and broad-spectrum removal of antibiotics was achieved. Results showed that the removal rates of antibiotics (in terms of total mass concentrations) in perch, eel, raw fish and shrimp culture pond water were maintained at more than 80% by the composite packing filter dam. Quinolones, sulphonamides, tetracyclines and chloramphenicol were removed to different extents, among which the best removal effects were observed for quinolones and sulphonamides. The composite filler consisting of iron filings, ceramsites and polybutylene succinate (PBS) was found to significantly improve the removal of quinolones and sulfonamides. Ceramsites were demonstrated to play an adsorption role through which quinolone and sulfonamide antibiotics were removed via pore filling and π-π electron donor-acceptor interactions, which was identified as the main antibiotic removal pathway. Iron filings were shown to remove tetracycline and chloramphenicol through adsorption and reduction processes, and were suggested to have accelerated the direct electron transfer process that promoted antibiotic degradation. PBS was involved in the removal of antibiotics through co-metabolic denitrification. Both iron filings and PBS were proven to enhance the metabolic activity of functional microorganisms, thereby accelerating antibiotic removal. The synergistic effect between these components was confirmed to help achieve efficient and broad-spectrum antibiotic removal.

The distribution characteristics of benzene, toluene, ethylbenzene and xylene (BTEX) concentrations in seawater and the atmosphere in the East China Sea in October 2020 were investigated, the sea-air exchange fluxes were evaluated, and the ecological risks and environmental effects were analyzed. The results showed the average concentrations of benzene, toluene, ethylbenzene, m/p-xylene and o-xylene were (136.8±76.8), (321.3±279.0), (530.3±530.0), (336.2±453.6) and (493.7±814.7) pmol/L in the surface seawater, respectively, and were (122.3±84.2), (217.1±162.4), (423.8±399.0), (236.8±215.1) and (344.3±288.5) pmol/L in the bottom seawater. The high values were found in the nearshore and the eastern part of the investigated sea area, of which the high values in the nearshore indicated they were influenced by land-based inputs, and the high values in the eastern part might be related to the petroleum extraction activities. The average atmospheric concentrations of benzene, toluene, ethylbenzene, m-/p-xylene and o-xylene were (110.5±45.3),(410.1±384.4), (139.5±108.8), (128.3±123.9) and (108.9±97.6) ×10^-12, and the backward trajectories showed they were affected by the input from land-based sources. The mean sea-air fluxes of benzene, toluene, ethylbenzene, m-/p-xylene and o-xylene were (25.6±13.1),(73.1±78.2), (179.9±194.5), (146.3±185.4), and (216.3±358.7) g/(km²⋅d), indicating that the investigated sea area is an important source of atmospheric. In terms of ecological risk, the concentrations of BTEX in seawater were far below the acute toxicity median effect concentration (EC50) and the half-lethal concentration (LC50) for marine organisms, indicating that BTEX posed relatively low direct harm to segmental marine life. In the atmosphere, the calculated carcinogenicity risk value (R), the non-carcinogenicity risk hazard quotient (HQ), and the non-carcinogenicity risk index (HI) were much lower than the reference values, indicating that the direct threat of atmospheric BTEX to human health was low. The analysis of O₃ and SOA generation potentials revealed that toluene and xylene were the key active components of BTEX and had the most significant impact on environmental effects.

This study investigated the regulatory mechanisms of zero-valent iron-graphite composite materials (0~4.0g/L) on sludge fermentation via chain elongation(CE) systems through a gradient dosing approach. The enhancement of iron-carbon materials on the CE process were systematically analyzed by monitoring the variations of short-chain carboxylic acids (SCCAs) and medium-chain carboxylic acids (MCCAs) concentrations, decomposition and metabolism of organics, electron transfer efficiency, and evolution of microbial community structure. The results demonstrated that the MCCAs production reached 10.65g/L at an iron-carbon dosage of 0.5g/L, representing a 2.04-fold increasement compared to the control group. The selectivity of caproic acid reached 53.60%, enhanced by 24.96% compared to the control. Mechanistic studies revealed that iron-carbon materials influenced the three stages of anaerobic fermentation (solubilization, hydrolysis, and acidification), promoting the decomposition and metabolism of organics and the conversion of polysaccharides to SCCAs. Simultaneously, a significant enhancement in electron transfer activity was observed in the groups with iron-carbon addition. Microbial community analysis further indicated that iron-carbon materials increased the relative abundance of the phylum Firmicutes and the genus Clostridium sensu stricto 12, which facilitated hydrolysis and CE processes in anaerobic fermentation. This study suggested that the application of iron-carbon materials could enhance MCCAs production in sludge anaerobic fermentation systems.

To elucidate the potential ecological risks of carbon dots, a novel nanomaterial, this study investigated the physiological responses and underlying mechanisms of the freshwater microalgae Euglena gracilis following exposure to pristine carbon dots（CDs）and Cu-N-doped carbon dots（Cu-CDs）. The results demonstrated that both types of carbon dots initially promoted but subsequently inhibited the growth of E. gracilis over time. Compared to CDs, Cu-CDs exerted a more pronounced impact on key physiological processes, including photosynthesis and antioxidant defense. Exposure to 1mg/L and 10mg/L Cu-CDs resulted in the accumulation of photosynthetic pigments and a decline in photosystem II activity, whereas a significant change in photosynthetic pigment content was observed only at 10mg/L in the CDs-exposed group. The maximum inhibition rates of superoxide dismutase activity induced by CDs and Cu-CDs were 62.52% and 78.35%, respectively. Metabolomics analysis further confirmed that Cu-CDs triggered a stronger metabolic disturbances, with the most notable alterations observed in lipid metabolism pathways, indicating compromised membrane stability of E. gracilis. Disruptions in amino acid and photosynthetic metabolism pathways were primarily attributed to oxidative stress. Additionally, both CDs and Cu-CDs affected energy metabolism by altering in alanine, aspartate, and glutamate metabolism, as well as glycolysis/gluconeogenesis pathways. Overall, the impairment of photosynthetic and antioxidant system may represent the primary toxic mechanisms of carbon dots in E. gracilis.

The Dongjiang River Basin was chosen as the study area to compare the nitrogen concentrations and isotopes in the river with different land uses, so as to provide a better understanding and evidence for impacts of urbanization on active nitrogen turnover. In this study, the distinct characteristics of nitrogen concentrations and isotopes were found in urbanized rivers compared to rivers with other land uses. Firstly, the nitrogen concentrations in urbanized rivers were gradually increased due to urbanization and nitrate has become a main nitrogen speciation. Secondly, based on the isotope Rayleigh fractionation model, it was found that the nitrification potential in urbanized river channels was enhanced and about 25.8% of nitrate nitrogen came from nitrification in situ. In addition, a positive correlation between ln（NO₃^--N）and δ¹⁵N-NO₃^- was recorded in urbanized rivers. Moreover, Δδ¹⁵N/Δδ¹⁸O in the dry and wet seasons were –2 and -6, respectively, indicating that the denitrification potential was weakened to provide evidence for nitrate accumulation in urbanized river channels. Likewise, a weak correlation between δ¹⁵N-PN and δ¹⁵N-NH₄⁺ was also recorded in urbanized rivers, and the ¹⁵N enrichment factor of nitrate assimilation also differed from the theoretical value, indicating a weak assimilation of ammonia and nitrate nitrogen. Finally, more input pathways and less sink processes of nitrogen in urbanized rivers have become a key mechanism for elevated riverine nitrogen concentrations in the lower reaches of Dongjiang river.