To investigate the pollution status, sources, and ecological risks of polycyclic aromatic hydrocarbons ( PAHs ) in surface waters of low-latitude plateau lakes in China, monthly sampling and analysis of surface water 16 PAHs mass concentrations, composition characteristics, and spatiotemporal distribution were conducted in Qilu Lake in the central region of Yunnan Province from January to December 2024. The study quantitatively analyzed the pollution sources and relative contributions of PAHs detected and assessed their ecological risks in Qilu Lake. The findings revealed that 13 PAHs were detected in varying degrees in the surface water of Qilu Lake during both the rainy and dry seasons, with a predominance of three-ring structures. During the rainy season, the total mass concentrations of 16PAHs ranged from undetected ( below the method detection limit, same below ) to 198.42 ngL-1( average 49.11 ngL-1), while during the dry season, it ranged from undetected to 213.38 ngL-1( average 63.79 ngL-1). The highest individual mass concentrations were found for Phe ( 49.94 ngL-1) and Ace ( 43.63 ngL-1). The average mass concentration of PAHs at all sampling points was higher in the dry season ( 63.79 ngL-1) compared to the rainy season ( 49.11 ngL-1). Spatial distribution showed that during the rainy season, PAHs mass concentrations were highest at Lake Management Station S2 ( 55.39 ngL-1), followed by Majiawan S3 ( 41.19 ngL-1), and then Lake Center S1 ( 34.60 ngL-1). In contrast, during the dry season, the order was Majiawan S3 ( 61.00 ngL-1) > Lake Management Station S2 ( 57.26 ngL-1) > Lake Center S1 ( 51.85 ngL-1). Positive Matrix Factorization ( PMF ) results indicate that during the rainy season, the surface water of Qilu Lake mainly sources PAHs from industrial sources ( contributing 31.9% ) and the volatilization leakage and combustion emissions of crude oil products ( contributing 29.5% ). In contrast, during the dry season, the primary sources are a mixture of coal and biomass combustion ( contributing 55.0% ) and biomass combustion alone ( contributing 25.2% ). Additionally, based on ecological risk assessment using the Risk Quotient ( RQ ), Ace, Flu, and Ant are identified as the main ecological risk factors for Qilu Lake. During the dry season, all sampling points and a specific points during the rainy season exhibit occasional moderate ecological risks. Overall, PAHs in the water body are at low to moderate ecological risk levels and require attention. In the context of heightened national focus on new pollutant management, traditional persistent organic pollutants such as PAHs still warrant continuous monitoring.
Polyacrylic acid/sodium alginate-based titanium dioxide (PAA/SA@TiO2) composite hydrogel has the good nitrogen removal properties in the nitrogen-containing wastewaters. Under the optimal adsorption conditions, which include pH 7, temperature 35 degrees C, adsorbent dosage 6 g/L, adsorption equilibrium time 70 min, the adsorption efficiency is 85.56%, 79.46%, and 67.63% when the initial ammonia nitrogen concentrations of 100, 200, and 300 mg/L, respectively, indicating that the hydrogel has good adsorption performance for ammonia nitrogen. The adsorption process conforms to the monolayer adsorption of the Langmuir model, and the adsorption kinetic process belongs to the pseudo-second-order kinetic model of chemical adsorption. The structure of PAA/SA@TiO2 composite hydrogel is stable. The thermogravimetric analysis revealed that its main chain of the composite hydrogel began to break and degrade only at 446 degrees C with thermally decomposed hydroxyl and carboxyl groups. At 800 degrees C, the thermal loss rate was 48%. After 5 cycles of adsorption regeneration, the adsorption efficiency only drops by about 10%. The research results showed that PAA/ SA@TiO2 composite hydrogel had great application prospects in the field of nitrogen-containing wastewater treatment, which provided the theoretical basis and operating parameters for the hydrogel applying in the nitrogen-containing wastewaters treatment.
The effects of relative humidity on the direct conversion efficiency, mineralization rate and components of waste gas from benzene photooxidation degradation were studied. Quantum chemical DFT method was used to analyze the reaction path of benzene photooxidation degradation under the competition of hydroxyl radical and oxygen atoms at different relative humidity. The results showed that the direct conversion efficiency of benzene increased first and then decreased with increasing relative humidity. The maximum direct conversion efficiency was 82% appearing at relative humidity of 50%. The mineralization rate decreased significantly at higher relative humidity, and the smallest value is 2%. The components of waste gas varied much at different relative humidity. At relative humidity of 40%, the oxidative degradation path of benzene was determined by oxidation of 1,2-cyclohexanediol to 1,2-cyclohexanedione, and the maximum reaction energy barrier is 15.3 kcal center dot mol-1, which is beneficial to improving the mineralization effect and generating some organic compounds with higher molecular weight such as P10 acetophenone and P11 benzaldehyde; As the relative humidity increased from 50% to 80%, the maximum reaction energy barrier decreased from 48.1 kcal center dot mol-1to 22.9 kcal center dot mol-1. At this time, oxidative degradation path of benzene was determined by oxidation of 1, 4-cyclohexanediol to 1,4-cyclohexanedione and oxidation of 1,2cyclohexanediol to 1,2-cyclohexanedione. The introduction of hydroxyl radicals greatly decreased the oxidation difficulty of 1,4-cyclohexanediol and 1,2-cyclohexanediol, resulting in sharply decreasing mineralization rate and direct conversion efficiency. To determine the optimal relative humidity, it is necessary to comprehensively analyze the direct conversion efficiency, mineralization rate, and components of waste gas.
The objective of this study was to establish a method for the detection of six selenium species in Se-enriched puerarin powder, including Se(VI),Se(IV),SeCys(2),MeSeCys,SeMet and SeEt. Also this study was to analyze the antioxidant damage of the main selenium species. The sample was extracted with 0.1 mol center dot L-1 NaOH solution at 90 degrees C for 30 min, then protease XIV, lipase and amylase were added. And enzymolysis was performed at 37 degrees C for 18 h in water bath. Six selenium species were rapidly detected by high performance liquid chromatography-inductively coupled plasma-mass spectrometry (HPLC-ICP-MS). The effect of main selenium species on the oxidative damage of AML12 cells induced by Lipopolysaccharide (LPS) was measured. The results showed that the detection limits for the six selenium species were 0.017 -0.053 mg center dot kg(-1), and the correlation coefficients of the standard curves were all above 0.9998. The spiked recoveries of the samples determined by this pretreatment method were all between 71.2%-117.3%, and the relative standard deviations were all within 10%. Compared to the model group, the activity of AML12 cells induced by LPS increased significantly (P<0.01) after being applied to SeMet at a concentration of 1 mu mol center dot L-1, the content of Malondialdehyde (MDA) decreased by 30.1% (P<0.01), the activity of Superoxide Dismutase (SOD) increased by 43.9% (P<0.01), and the activity of Glutathione Peroxidase (GSHx) increased by 44.7% (P<0.01). The results suggest that SeMet has a protective effect on LPS induced oxidative damage in AML12 cells. So it can enhance the ability of plants on antioxidant damage.
Thiophene-ring modified carbon nitride hollow sphere photocatalysts (CNS) were synthesized by one-step low-temperature solvothermal method using thiophene group-containing molecules as monomers. The structure, morphology and optoelectronic properties of the catalysts were characterized by XRD, SEM, XPS, UV-Vis DRS, PL and others. The results show that appropriate amount of thiophene-rings embedded in the carbon nitride framework does not affect the hollow spherical morphology of the products, the long-range polymerization degrees of them are reduced, but it increases the surface defects of the spheres, expands the visible light absorption range, narrows the band gap, enhances the generation density of photogenerated charges and effectively inhibits the recombination of photogenerated electron-holes, therefore enhances the photocatalytic performances significantly. The photocatalytic reduction of Cr6+ in aqueous solution, water splitting for hydrogen production, and methyl orange degradation tests show that CNS-2 modified by thiophene-ring performs much enhanced photocatalytic activity, and its reaction rate was 2.5, 3.8 and 1.6 times that of unmodified carbon nitride (CN), respectively. Pphotogenerated e− and indirectly generated \begin{document}$\cdot {\rm{O}}_2^- $\end{document} are the main active species for reduction and oxidation reactions, respectively.
