Freshwater rivers play the key role in providing drinking water sources and building the bridge of oceans and lands. Hence, environmental pollutants can be transferred into drinking water through a water treatment process and transported land-based microplastics into the ocean. Microplastics are considered a new pollutant that is becoming a threat to freshwater ecosystems. The present study investigated the temporal and spatial variation of microplastics abundance and their characteristics of occurrence in surface water, sediment and soil samples of Baotou section of Yellow River in China in March 2021 and September 2021. According to the LDIR analysis, the average abundances of microplastics in wet season (surface water 2510.83 ± 2971.27n/L, sediment 6166.67 ± 2914.56n/kg) were higher than that in dry season（surface water 432.5 ± 240.54n/L, sediment 3766.67 ± 1625.63n/kg), particularly being significant difference in the dry and wet seasons of surface water. The predominant polymer types in surface water (PBS and PET during the dry season, PP during the wet season) demonstrated that the temporal variation of microplastics abundance in surface water could be attributed to the combined effect of the regional precipitation, fishing activities and improper disposal of plastic waste. And the results of spatial abundances of microplastics showed that the microplastics abundance of soil and sediment was higher than that in river water and microplastics abundance in the river of the south side was the higher than other water sampling sites, revealing the differences of microplastics burden at the different sampling sites. Moreover, it is worth noting that a large amount of PAM was detected in sediments and soil, but not in water, and the biodegradable plastics PBS and PLA were also detected in the Yellow River. It was a very useful information for evaluating environmental impacts and ecological effects of degradable plastics compared to the traditional plastics after the implementation of a new environmental policy in the future. Thus, this study provided insights into the temporal-spatial characteristics of microplastics in an urban river and raised environmental management awareness of the long-term threat to drinking water safety by microplastics.

Long-term and short-term exposure to carbon nanoparticles (CNPs) can affect fetal development and subsequent adverse outcomes including preterm delivery, intrauterine growth restriction, low birth weight, increased health risk linked to cardiovascular, respiratory and nervous systems in adulthood. The adverse developmental outcomes of CNPs were well known, but the underlying mechanisms remain unresolved. In this study, zebrafish embryos were treated with CNPs of 50,100,200 μg/mL and the toxic effects were observed. Using the RNA-seq analysis approach, we examined the effects of CNPs (200 μg/mL) on gene expression in zebrafish embryos exposed from 4 to 96 h-post-fertilization (hpf). We observed that CNPs-treated embryos exhibited increased malformations and decreased hatching. A total of 236 differentially expressed genes were detected by transcriptome analyses, which were associated with phototransduction, amino acid metabolism, steroid and steroid hormone biosynthesis. Transcriptome results were verified by real-time fluorescence quantitative PCR (RT-qPCR). Our results indicated that CNPs exposure was most likely to lead to differential gene changes in steroid and hormone biosynthesis pathways, thus inducing developmental toxicity such as delayed incubation of zebrafish embryos, increased malformation rate and multiple malformation phenotypes.

Polyethylene terephthalate (PET) is a type of polymer plastic that is often used to make plastic bags, bottles, and clothes. However, the waste of such plastic products is decomposed into microplastics (MPs), which are plastic fragments smaller than 5 mm, by various external forces such as wind, UV radiation, mechanical wear, and biodegradation. PET MPs have been widely detected in the environment and human tissue samples; however, the toxicity and mechanism of PET MPs in mammals are still unclear. In this study, we investigated the male reproductive toxicity of PET MPs and their underlying mechanism. A total of 80 male mice were orally exposed to 0.01, 0.1, and 1 mg/d of PET MPs (with a diameter of 1 μm) for 42 days. The results showed that 1 μm PET MPs induced different degrees of pathological damage to testicular tissues, decreased sperm quality, and increased the apoptosis of spermatogenic cells via oxidative stress and p38 signaling pathway activation. To further illustrate and verify the mechanistic pathway, oxidative stress was antagonized using N-acetylcysteine (NAC), and the activation of the p38 signaling pathway was blocked using SB203580. The results revealed that the male reproductive injury effects after exposure to PET MPs were significantly ameliorated. Specifically, the testicular tissue lesions were relieved, the sperm quality improved, and the apoptosis of spermatogenic cells decreased. These results demonstrated that PET MP exposure induced male reproductive toxicity through oxidative stress and the p38 signaling pathway. This study provides new insights into the reproductive toxicity of MPs in males, as well as valuable references for public health protection strategies.

Antibiotic resistance genes (ARGs) have been widely recognized as emerging environmental contaminants due to their potential threats to public health and ecosystems. Owing to the extensive use of antibiotics in clinical, agricultural, and aquaculture settings, large quantities of ARGs are continuously introduced into the natural environment. As a result, aquatic environments—particularly surface waters—act as important reservoirs and transmission pathways for ARGs. However, despite the Yellow River being a major surface river in northern China, the occurrence and sources of ARGs in this river remain poorly understood. In this study, shotgun metagenomic sequencing was applied to investigate the composition of ARGs, mobile genetic elements (MGEs), and virulence factors (VFs) in three water sources in the Baotou section of the Yellow River. A total of 35 types of ARGs, 3 types of MGEs, and 14 categories of VFs were identified across all samples. Among them, multidrug resistance genes, peptide resistance genes and glycopeptide resistance genes exhibited relatively high abundances, indicating their widespread distribution in the study area. In terms of MGEs, recombinases and transposases were dominant, suggesting their important roles in gene mobilization. Meanwhile, VFs were mainly associated with metabolic functions, immune modulation, and adherence, reflecting the potential pathogenic risks in the aquatic environment. Co-occurrence networks revealed extensive associations between ARGs and MGEs, as well as ARGs and VFs. Many positive correlations were observed, suggesting possible ecological associations between ARGs and MGEs and potential co-selection between ARGs and VFs. Overall, this study provides valuable insights into the distribution patterns and co-occurrence patterns of ARGs, MGEs, and VFs in the Yellow River and offers a scientific basis for the management and control of antibiotic resistance pollution in large river systems.