Toxics

With the rapid growth of livestock farming, the use of antibiotics and heavy metals as feed additives has raised environmental and health concerns. This study systematically analyzed the contamination levels of antibiotics and heavy metals in manure samples collected from five farms of varying scales in Liuyang City, Hunan Province. Utilizing 16S rDNA high-throughput sequencing technology, the study also examined the structural and functional characteristics of manure microbial communities. Ecological risk and human health risk assessments were also conducted. Results revealed that antibiotic residues in pig manure were generally higher than those in chicken manure, with significant differences in antibiotic usage across farms of varying scales. Cu and Zn levels exceeded standards in some samples, particularly from small-scale farms. Microbial community structures showed marked differences, with pig manure exhibiting higher microbial diversity. Functional prediction indicated active metabolism, strong environmental adaptability, and robust pollutant degradation capacity. Risk assessments revealed moderate to high ecological and human health risks from certain antibiotics and heavy metals, with significant non-carcinogenic and carcinogenic risks particularly for children. The study emphasizes that rational control of antibiotic and heavy metal use, coupled with enhanced manure management and resource utilization, is crucial for safeguarding ecological security and public health.

Microplastics (MPs) are widespread worldwide and have become a significant environmental problem due to their durability and the large quantities that enter ecosystems. As the global spread of microplastic pollution continues, the Armenian gull (Larus armenicus) in the Lake Van Basin has emerged as an important bioindicator. This study highlights the widespread impact of human-generated waste on natural habitats by detecting the presence of microplastics in gull feces using a non-invasive, polymer-supported method. Methods: The study was conducted between 10 May 2024 and 26 April 2025. A total of 480 fecal samples were analyzed from four stations with different characteristics and exposed to various anthropogenic effects. Instead of individual-level statistical inference, we performed temporal comparisons descriptively at the composite level. Results: We categorized suspected MPs by type, shape, size, and color, using FTIR to confirm the polymer identity of a representative subset (>300 µm; ~20%) and SEM–EDX to examine particle surfaces. A total of 8197 MP particles were observed in the feces collected from the stations. The most frequently observed MP type, size, shape and color were fiber (32.6%), 100–300 µm (30.8%), spherical (29.2%) and brown (18.4%), respectively. The chemical structures of all examined MPs were polyethylene (PE) (42.6%), polystyrene (PS) (28.38%) and polyethylene terephthalate (PET) (8.5%). SEM-EDX confirmed that the microplastics are polymers by showing their degraded surface and carbon/oxygen ratio. Conclusions: Identifying polymer species in ingested plastics is valuable for future studies, as the results can be used to assess the relationship between microplastics.

Ammonia nitrogen stands as a pivotal water quality indicator within the frameworks of aquatic ecological quality assessment and aquatic ecological governance systems. This study focuses on the adsorption method, selecting four inorganic adsorbents—clinoptilolite, volcanic rock, bentonite, and fly ash—as research subjects, and introduces rare earth modifiers for rare earth-loading modification. Various modifications were applied to the adsorbents to enhance their ammonia nitrogen adsorption efficacy. Combined with material characterization, the microscopic features and adsorption behaviors of the adsorbents were elucidated, aiming to provide a theoretical foundation for addressing practical engineering challenges and to screen out the optimal inorganic adsorbent and the most effective modification protocol. Based on the experimental findings, cerium chloride modification can significantly enhance the ammonia nitrogen adsorption performance of clinoptilolite. Under the optimal preparation conditions (cerium chloride concentration: 1.0%, solid–liquid ratio: 1:40, pH = 9), the ammonia nitrogen removal efficiency reaches 85.45%. This modification process leads to the formation of new substances: a large amount of cerium oxide and cerium hydroxide are loaded onto the surface of clinoptilolite, which contributes to the increases in specific surface area (21.92 m²/g), average pore diameter (12.27 nm), and total pore volume (0.07 cm³/g). Furthermore, during the modification, cerium hydroxide undergoes hydroxylation, rendering the clinoptilolite surface negatively charged—this facilitates the adsorption of ammonia nitrogen via electrostatic interaction. Notably, the characteristic structural peaks of clinoptilolite remain unchanged before and after modification, indicating that the modification primarily acts on the material surface. This not only improves the ammonia nitrogen adsorption efficiency but also preserves the structural stability of clinoptilolite.