Navigating the difference of riverine microplastic movement footprint into the sea: Particle properties influence.

As a critical source of marine microplastics (MPs), estuarine MPs community varied in movement due to particle diversity, while tide and runoff further complicated their transport. In this study, a particle mass gradient that represents MPs in the surface layer of the Yangtze River estuary was established. This was done by calculating the masses of 16 particle types using the particle size probability density function (PDF), with typical shapes and polymers as classifiers. Further, Aschenbrenner shape factor and polymer density were embedded into drag coefficients to categorically trace MP movement footprints. Results revealed that the MPs in North Branch moved northward and the MPs in South Branch moved southeastward in a spiral oscillation until they left the model boundary under Changjiang Diluted Water front and the northward coastal currents. Low-density fibrous MPs are more likely to move into the open ocean and oscillate more than films, with a single PE fiber trajectory that reached a maximum oscillatory width of 16.7 km. Over 95 % of the PVC fiber particles settled in nearshore waters west of 122.5°E. Elucidating the aggregation and retention of different MPs types can provide more accurate environmental baseline reference for more precise MP exposure levels and risk dose of ingestion for marine organisms.

Microplastics in Chinese coastal waters: A mini-review of occurrence characteristics, sources and driving mechanisms.

The oceans are facing global and irreversible pollution from microplastics, and China is not immune. In this mini-review, information on microplastics in four coastal waters of China and the natural and social environment of key basins were compiled. The results showed that microplastics were ubiquitous in the coastal waters, and the abundance and spatial distribution of microplastics varied significantly under different sampling methods. For trawl samples, microplastic abundance ranged from 0.045 to 1170.8 items m-3, among which the coastal waters of the East China Sea were the most polluted. For filtered samples, microplastic abundance ranged from 46 to 63,600 items m-3, and the coastal waters of the Yellow Sea were the most polluted. Meanwhile, human activities in basin were the key factors affecting microplastic pollution in coastal waters. The main terrestrial source in the coastal waters of the South China Sea was express packaging loss, whereas the main source in the other coastal waters was tyres and road markings wear from vehicle trip. The decoupling results of analytic hierarchy process showed that there was spatial heterogeneity in the impact of socio-economic and natural environmental factors in the basin on the distribution of microplastics in coastal waters. Among the five major basins, the impact weights of the latter were 20.00%, 83.34%, 66.66%, 50.00% and 25.00%, respectively. This study provides the first perspective of land-sea linkage to summarize the characteristics, sources and influencing factors of microplastics in Chinese coastal waters, providing ideas for reducing marine microplastic pollution from the source.

[Pollution Characteristics and Ecological Risk Assessment of Microplastics in the Yangtze River Basin].

The Yangtze River, the largest river in China, has not been comprehensively studied for its basin's microplastic pollution status. Therefore, a comprehensive investigation and assessment system of microplastics was developed at the river basin scale to characterize the spatial distribution and composition of microplastics in the Yangtze River Basin in order to analyze their influencing factors and assess their ecological risks. The results showed that the microplastic abundance in the study area ranged from 21 to 44 080 n·m-3, with an average abundance of 4 483 n·m-3. The spatial distribution of microplastic abundance was higher in the tributaries than in the main streams (except the Ganjiang Basin), with the Chengdu of the Minjiang Basin being the tributary area with the highest abundance of microplastics detected. The size of microplastics in the river basin was concentrated in the 0-1 mm range; the shapes were mainly fiber and fragment; and the colors were mainly colored and transparent. Further, introducing the diversity index of microplastics, it was found that both the Simpson index and the Shannon-Wiener index could quantify the diversity of microplastic characteristic composition in the river basin, but there were certain differences in the changing trends between the two. Regression analysis showed that anthropogenic activities were significantly and positively correlated with microplastic abundance (P<0.05), and among the eight anthropogenic activity factors, civilian vehicle ownership and tourism income were the most strongly correlated with microplastic abundance, indicating that transportation and tourism were the main factors influencing microplastic distribution. From the perspective of the potential ecological risk index of microplastics, microplastics in the Yangtze River Basin posed a certain ecological risk, with 68.97% of the area falling within risk zones III and IV, with the ecological risk of microplastics in Taihu Lake warranting more widespread attention.

Water quality's responses to water energy variability of the Yangtze River.

River energy serves as an indicator of pollutant-carrying capacity (PCC), influencing regional water quality dynamics. In this study, MIKE21 hydrodynamics-water quality models were developed for two scenarios, and grid-by-grid numerical integration of energy was conducted for the Yangtze River's mainstream. Comparison of predicted and measured values at monitoring points revealed a close fit, with average relative errors ranging from 5.17 to 8.37%. The concept of PCC was introduced to assess water flow's ability to transport pollutants during its course, elucidating the relationship between river energy and water quality. A relationship model between Unit Area Energy (UAE) and PCC was fitted (R2 = 0.8184). Temporally, reservoir construction enhanced the smoothness of UAE distribution by 74.47%, attributable to peak shaving and flow regulation. While this flood-drought season energy transfer reduced PCC differences, it concurrently amplified pollutant retention by 40.95%. Spatially, energy distribution fine-tuned PCC values, showcasing binary variation with energy changes and a critical threshold. Peak PCC values for TP, NH3-N, and COD were 2.46, 2.26, and 54.09 t/(km·a), respectively. These insights support local utility regulators and decision-makers in navigating low-carrying capacity, sensitive areas, enhancing targeted water protection measures for increased effectiveness and specificity.

How microplastic loads relate to natural conditions and anthropogenic activities in the Yangtze river basin.

As the third largest river in the world, microplastic pollution in the Yangtze River basin is currently attracting worldwide attention. However, fragmented research information is insufficient to reveal the occurrence and driving mechanisms of microplastics throughout the Yangtze River basin. Building on a systematic review of 20 existing publications, this study constructed a dataset including microplastic data from 366 samples in the Yangtze River basin through a data filtering process, and data on natural conditions and anthropogenic activities from 101 basin municipalities. Further, multivariate statistical analysis was utilized to enhance the understanding of the abundance, composition and drivers of microplastics within the basin. Differences in microplastic abundance among the sampling sites were up to 5 orders of magnitude, with the highest abundance value found in the upstream city of Chengdu. The comprehensive diversity index used to describe the composition characteristics of microplastics ranged from 0.31 to 0.68, slightly higher than the national average. Based on a statistical analysis framework, natural conditions and anthropogenic activities were shown to jointly drive the distribution of microplastics, and the dominant driver shifted between the two with spatial variation. In the upstream, anthropogenic activities dominated by GDP (r = 0.85, P < 0.01) were the main positive factor. In the middle and downstream, natural conditions and anthropogenic activities had comparable driving forces as the stability of natural resistance increased, and both were positively correlated with microplastics. Combining the constructed normalized stepwise linear regression model with GIS spatial analysis, the basin-wide application demonstrated that microplastic pollution in the upstream and delta deserved more attention. After coupling the distance factors, microplastic pollution was concentrated in the middle and downstream of the Yangtze River basin, covering important drinking water sources. This study provided important data support for subsequent targeted microplastic reduction and treatment.

How the Yangtze River transports microplastic to the east China sea.

Land transportation in the Yangtze River basin is an important source of microplastics in the East China Sea, so it is significant to clarify the source, fate and river-sea transition of microplastics. Taking the Yangtze River as the study area, the interpolation method was used to analyze the monthly changes of the microplastic load in the estuary, the input-output model was used to estimate the flux of microplastics into the sea, and the inflow process of microplastics was studied through correlation analysis. The results showed that: (1) The load of microplastics in the Yangtze River estuary varied with season, reaching the maximum in October, with a monthly load of 3.91 Gg; (2) The total amount of microplastics entering the sea in the Yangtze River basin was higher than the medium level, which was 7.02 Gg. Among them, tributary input was the most important source, accounting for 62.9%. Non-point and point sources were further subdivided into 11 categories, with the largest proportion of microplastics generated during vehicle trip. Spatially speaking, the microplastics transported in the midstream accounted for the largest proportion, accounting for 55.56%; (3) microplastics had a strong correlation with COD and TP, indicating that the inflow process of microplastics was similar to that of traditional pollutants, which were river retention, wastewater treatment plant removal, water consumption removal and inflow to the East China Sea. Although the proportion of the last one was only 8.05%, the ecological risk was still not negligible due to the huge amount.

Long non-coding RNA Mirt2 interacts with long non-coding RNA IFNG-AS1 to regulate ulcerative colitis.

Long non-coding RNAs (lncRNAs) Mirt2 and interferon-γ antisense RNA I (IFNG-AS1) play opposing roles in lipopolysaccharide (LPS)-induced inflammation, a key initiator of ulcerative colitis (UC). The present study aimed to analyze the potential interaction between Mirt2 and IFNG-AS1 in UC. Levels of IFNG-AS1 and Mirt2 in plasma samples from UC patients were measured using reverse transcription-quantitative PCR. Receiver operating characteristic curves were used to evaluate the diagnostic values of IFNG-AS1 and Mirt2 fr UC. The role of Mirt2 and IFNG-AS1 in colonic epithelial cell apoptosis was analyzed by cell apoptosis assay. In patients with UC, Mirt2 and IFNG-AS1 exhibited an inverse correlation, in which Mirt2 was downregulated while IFNG-AS1 was upregulated. Altered expression of IFNG-AS1 and Mirt2 separated patients with UC from healthy controls. In colonic epithelial cells, lipopolysaccharide treatment led to the downregulation of Mirt2 and the upregulation of IFNG-AS1. Furthermore, overexpression of Mirt2 in colonic epithelial cells resulted in downregulation of IFNG-AS1, and vice versa. Overexpression of Mirt2 led to a decreased rate of colonic epithelial cell apoptosis, while overexpression of IFNG-AS1 led to an increased rate of apoptosis. Moreover, IFNG-AS1 overexpression attenuated the effects of Mirt2 overexpression. Therefore, Mirt2 may interact with IFNG-AS1 during UC to participate in colonic epithelial cell apoptosis.