Wetland is a transitional area where terrestrial ecosystems and aquatic ecosystems interact and influence each other, and it is an important ecosystem on the Earth’s surface. Due to the special characteristics of wetland ecology, the decomposition of wetland plant litter is slightly different from litter in forests, grasslands, and meadows and other traditional areas. The role of litter mineralization in the wetland ecological C cycle and the functional role of plant litter have been neglected. This study analyzes the decomposition mechanism and decomposition model of wetland litter material and focuses on the effects of the decomposition process of wetland litter material on the structure of the soil fauna community, decomposition of soil organic matter, sediment properties, and the dynamic changes in the C cycle of the biological system by combining domestic and international studies from recent years. Finally, we propose that the direction of future research on wetland litter decomposition should be to reveal the mechanism of wetland biodiversity and ecology, as well as the ecological correlation between aboveground and belowground biodiversity, with a view to providing a decision-making basis for wetland phytoremediation and wetland wastewater treatment.

In this study, concentrations of Cr, Mn, Pb, Cu, Zn, As, Cd, Sb, and Fe were determined in soils of a Pb-Zn mine watershed in northern Guangxi, China, for ecological risk assessment and source analysis. The atomic fluorescence spectrometry and ICP-OES were used to determine concentrations of heavy metals (HMs), and the total amount of Mn, Cu, Zn, As, Cd, and Pb exceeded the limit. Among them, the weak acid extractable fraction (F1) state masses of Pb, Mn, and Zn accounted for a higher ecological risk. The study area was divided into three distinct areas: highest concentrations of HMs were distributed in front of the Sidi River mountain (1^# and 2^#) and at the subterranean river entrance (5^# and 6^#), followed by the area along the river and the irrigated area of the river (3^# and 4^#), and the central highlands and southwestern parts had low concentrations (7^# and 8^#). The ecological risk assessment results indicate Cd is of extremely high ecological risk, Pb and Mn are of medium minor ecological risk, Zn is of minor ecological risk, and the rest have almost no impact on the eco-environment. The source apportionment results showed that Cu, Zn, Cd, Sb, and Pb were mainly controlled by anthropogenic activities, such as mining; Cr, Fe, and As were mainly influenced by natural processes, such as soil-forming parent rocks; and Mn is jointly controlled by mining and soil-forming parent rocks. This study can provide scientific guidance and technical support for soil risk control or remediation in mining areas.

Low C/N wastewater results from a wide range of factors that significantly harm the environment. They include insufficient carbon sources, low denitrification efficiency, and ${\mathrm{NH}}_4^{+}$-N concentrations in low C/N wastewater that are too high to be treated. In this research, the membrane biofilm reactor and hydrogen-based membrane biofilm reactor (MBR-MBfR) were optimized and regulated under different operating parameters: the simulated domestic sewage with low C/N was domesticated and the domestic sewage was then denitrified. The results of the MBR-MBfR experiments indicated that a C/N ratio of two was suitable for ${\mathrm{NH}}_4^{+}$-N, ${\mathrm{NO}}_2^{-}$-N, ${\mathrm{NO}}_3^{-}$-N, and chemical oxygen demand (COD) removal in partial nitrification-denitrification (PN-D) and hydrogen autotrophic denitrification for further treatment. The steady state for domestic wastewater was reached when the MBR-MBfR in the experimental conditions of HRT = 15 h, SRT = 20 d, 0.04 Mpa for H₂ pressure in MBfR, 0.4–0.8 mg/L DO in MBR, MLSS = 2500 mg/L(MBR) and 2800 mg/L(MBfR), and effluent concentrations of ${\mathrm{NH}}_4^{+}$-N, ${\mathrm{NO}}_3^{-}$-N, and ${\mathrm{NO}}_2^{-}$-N were 4.3 ± 0.5, 1.95 ± 0.04, and 2.05 ± 0.15 mg/L, respectively. High-throughput sequencing results revealed the following: (1) The genus Nitrosomonas as the ammonia oxidizing bacteria (AOB) and Denitratisoma as potential denitrifiers were simultaneously enriched in the MBR; (2) at the genus level, Meiothermus,Lentimicrobium, Thauera,Hydrogenophaga, and Desulfotomaculum played a dominant role in leading to ${\mathrm{NO}}_3^{-}$-N and ${\mathrm{NO}}_2^{-}$-N removal in the MBfR.

The concentrations of 17 antibiotics in the surface water and groundwater of a typical river in the Huixian Wetland were measured, and the ecological and health risks of these antibiotics to surface water and groundwater were assessed. The three types of antibiotics measured included quinolones, tetracyclines, and sulphonamides. The results showed that the mean values of the three antibiotics in surface water were sulfonamides > quinolones > tetracyclines and in groundwater were sulfonamides > tetracyclines > quinolones, and the antibiotic residues were associated with aquaculture and livestock breeding in the wetland, which indicated that antibiotics had a very high rate of use in the Huixian Wetland. The results of the ecological risk evaluation showed that the potential risk of five antibiotics, namely ofloxacin, sulfadiazine, sulfamethoxazole, enrofloxacin, and doxycycline, was high. The results of the health risk evaluation indicated that most of the residual antibiotics were of a medium and low risk to humans.

Mg/Fe layered bimetallic oxide mulberry rod biochar composites (MFBCs) were prepared from mulberry rods and characterized using electron microscopy scanning (SEM), X-ray diffraction (XRD), Fourier infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). We investigated the adsorption properties of MFBCs for phosphorus, which was recovered via crystallization using calcium chloride as a precipitant. According to the findings, the MFBC is a layered bimetallic oxide with a specific surface area of 70.93 m²·g⁻¹. Its point of zero charge values, or pHzpc, was 7.66. The removal of phosphorus usingMFBCs gradually decreased with increasing pH, and the optimum pH for phosphorus removal was 4.0. The maximum phosphorus adsorption by MFBCs at 298 K was 29.682 mg·g⁻¹ for MFBCs. The adsorption process of phosphorus onto MFBCs is a heat absorption process, and the adsorption isothermal data of phosphorus onto MFBCs fit with the Langmuir adsorption isothermal model. Phosphorus recovery is achieved when calcium chloride is added to the phosphate-enriched desorption solution at a Ca/P molar ratio of 2.2. The phosphorus product obtained from this process is very pure hydroxyphospapatite. The recovery rate of phosphorus in the desorption solution is 99.64%.

Exposure to an environment containing microplastics can cause adverse effects on creatures through respiratory and digestive systems. In this paper, 50–500 μm polystyrene microplastics (exposure concentrations were 200 μg/L, 800 μg/L, and 3200 μg/L concentrations) were selected to study the distribution of polystyrene microplastics (PS-MPs) and the effects on the growth, development, tissue damage and gene expression of crucian carp juveniles. The results showed that PS-MPs were enriched in the intestinal tract (GIT) and gill tissue of crucian carp, and the average number of PS-MPs was between 0 to 2.33 items per individual. It was found that the average number of MPs in the intestine was more than in the gills, and it was independent of the PS-MP concentration. However, the specific gravity of PS-MPs in excreta was concentration-dependent. In addition, it was found that the exposure of the medium concentration group promoted the weight of the crucian carp larvae, inhibited the growth rate, and reduced the weight in the low and high concentration groups. The histopathological results indicated that the intestinal, gill, brain, and liver tissues all showed different degrees of damage, and the higher the concentration of PS-MPs, the more severe damage to the tissue cells. This experiment evaluated 15 genes in three treatments, which found that PS-MPs had different effects on gene expression in the liver, intestine, and gill tissues, and the tested genes were involved in different response pathways associated with virulence.