In recent years, there has been growing concern about antibiotic contamination in water bodies, particularly the widespread presence of fluoroquinolones (FQs), which pose a serious threat to ecosystems due to their extensive use and the phenomenon of “pseudo-persistence”. This article provides a comprehensive review of the literature on FQs in water bodies, summarizing and analyzing contamination levels of FQs in global surface water over the past three years, as well as the bioaccumulation and metabolism patterns of FQs in aquatic organisms, their ecological toxicity, and the influencing factors. The results show that FQs contamination is widespread in surface water across the surveyed 32 countries, with ciprofloxacin and norfloxacin being the most heavy contaminants. Furthermore, contamination levels are generally higher in developing and developed countries. It has been observed that compound types, species, and environmental factors influence the bioaccumulation, metabolism, and toxicity of FQs in aquatic organisms. FQs tend to accumulate more in organisms with higher lipid content, and toxicity experiments have shown that FQs exhibit the highest toxicity to bacteria and the weakest toxicity to mollusk. This article summarizes and analyzes the current research status and shortcomings of FQs, providing guidance and theoretical support for future research directions.

Ferric chloride (FeCl₃) modified reed straw-based biochar was synthesized to remove nitrate from aqueous solutions and achieve waste recycling. The adsorption of nitrate onto Fe-RBC-600 adsorbents could be described by the pseudo-second-order kinetic model and fitted to Langmuir adsorption, and the maximum adsorption capacity predicted using the Langmuir model was 272.024 mg g⁻¹. The adsorbent characterization indicated that a high temperature of 600 °C and an oxygen-poor environment could develop a hydrophobic surface and O-containing functional groups on the biochar, which provided more binding sites for Fe³⁺/Fe²⁺ attachment and increased the surface functionality of Fe-RBC-600 with iron oxide formation. The increasing surface functionality successfully enhanced the nitrate adsorption property. The mechanism of nitrate adsorption was mainly attributed to the physical adsorption onto the positive surface and sequential chemical reduction by Fe²⁺, and the electrostatic adsorption by protonated amine groups.

This study aimed to investigate the levels of 12 sulfonamide antibiotics in freshwater fish species obtained from three cities in northeastern China (Harbin, Changchun, and Shenyang). The analysis was conducted using HPLC–MS/MS to accurately quantify the antibiotic concentrations in the fish samples. The results showed that the average levels of sulfonamide antibiotics in fish samples from Harbin, Changchun, and Shenyang were 1.83 ng/g ww, 0.98 ng/g ww, and 1.60 ng/g ww, respectively. Sulfamethoxazole displayed the highest levels and detection rates in all three cities, whereas sulphapyridine exhibited the lowest concentrations in all the fish samples. The levels of sulfonamide antibiotic residues in the different fish species varied widely among the cities, and the highest level of antibiotic residues was found in the muscle of carnivorous fish. The results from a health risk evaluation on the consumption of these fish indicated that the risk from long-term antibiotic exposure to local residents from the intake of the sampled fish was small and not sufficient to pose a significant health risk to consumers.

In this paper, the characteristics of water pollution in Yitong River were analyzed by the comprehensive pollution index method. Combined with the pore water concentration gradient method and Fick’s first law, the release characteristics of nutrients at the sediment–water interface of Yitong River (Jilin Province, China) were studied. The results showed that the distribution trend of nitrogen and phosphorus content in the overlying and interstitial water of the Yitong River was the same, and the highest values appeared at the S3 and S5 points in the urban section. The water quality was mainly affected by nitrogen pollutants in domestic sewage. The evaluation results of the water quality comprehensive pollution index showed that the pollution degree of interstitial water in urban areas was much higher than that of the overlying water, and the endogenous nitrogen and phosphorus pollutants had the risk of diffusion to the overlying water. The exchange flux analysis of ammonia nitrogen (NH₄⁺-N), total dissolved nitrogen (TDN), and total dissolved phosphorus (TDP) in water showed that the diffusion flux of NH₄⁺-N ranged from 0.03 to 6.52 mg·(m²·d)⁻¹, and the sediment was the “source” of ammonia nitrogen pollutants. The range of TDN diffusion flux was −1.57 to 11.6 mg·(m²·d) ⁻¹, and the difference between points was large. The sediment was both the “source” and “sink” of nitrogen pollutants. The range of TDP diffusion flux was −0.05 to 0.22 mg·(m²·d) ⁻¹. Except for point S8, the TDP diffused from sediment into the water body. Among all the sampling points, the diffusion fluxes of NH₄⁺-N, TDN, and TDP at the S3 point were the largest, the release rate of endogenous pollutants was the most rapid, and the pollution to the water quality was the most serious. The results are of great significance to the exchange flux of nutrients at the sediment–water interface of rivers and the prevention and control of water eutrophication. It also provides a reference for the study of nutrient exchange flux at the sediment–water interface of rivers and other surface water bodies worldwide.

In recent years, the Yitong River in Changchun City has been polluted by human activities to a certain extent, and therefore, it is necessary to monitor its water quality. Phytoplankton are sensitive to environmental changes and are an ideal biological indicator for environmental monitoring. This study studied the phytoplankton distribution in eight sampling sites of the Changchun section of the Yitong River from April to September 2019. The aim was to investigate the relationships between phytoplankton community structure’s temporal and spatial distribution characteristics and water quality in the Changchun section of the Yitong River. Environmental factors such as the total nitrogen (TN), total phosphorus (TP), water temperature (WT), ammonia nitrogen (NH3-N), chemical oxygen demand (CODCr), permanganate index (CODMn), and chl-a were measured and assessed. The results identified 161 species of phytoplankton belonging to eight phyla among eight sampling sites of the Changchun section of the Yitong River, including 67 species of Chlorophyta, 11 species of Cyanobacteria, and 51 species of Bacillariophyta. The percentage of Cyanobacteria phytoplankton abundance in the urban area was higher than that in the reservoir and the wet regions. From the temporal perspective, the total phytoplankton density and biomass peaked in summer, with the highest values recorded in June, followed by July. The study showed that TN, TP, and chl-a were the main environmental factors affecting the phytoplankton community structure in the Changchun section of the Yitong River.