Packed column experiments and numerical simulations were conducted to investigate the co-transport behavior of nanoscale iron supported on biochar (nFe/BC) pyrolyzed at 500℃ and 800℃, respectively, with arsenic (As) in contaminated soil. The results showed that the mobility of nFe/BC (nFe/BC500 and nFe/BC800) in As-contaminated soil was obviously lower than that of pristine biochars (BC500 and BC800), decreasing by about 57.8% and 45.5% in As-contaminated soil, respectively. This is likely because zeta potentials of nFe/BC became less negative due to the adherence of positively charged Fe onto the BC. Therefore, electrostatic repulsion between nFe/BC and soil grain was weakened, resulting in a lower mobility of nFe/BC. Also the mobility of nFe/BC was reduced with an increase in pyrolysis temperature. This is likely because that the surface charge of nFe/BC produced at high temperature was less negative, due to the lower density of O-containing functional groups. Therefore, the total repulsive interaction energies between nFe/BC and soil grain were reduced. A two-site kinetic retention model was successfully employed to simulate the transport of nFe/BC in soils, further illustrating the co-transport characteristics of nFe/BC. Additionally, pristine BCs facilitated the transport of As due to the competition between BCs and As for the available sorption sites on the soil surface. However, nFe/BC first inhibited the transport of As, and then promoted it. The main reason could be because the iron substance or Fe₃O₄ on the surface of nFe/BC reacted with As, and then fixed it in soil. Once the reaction between nFe/BC and As was completed, nFe/BC lost its original inhibitory effect, and instead acted as a carrier to promote As transport in soil. This could cause potential risks of As to the groundwater environment.

This paper aims to review the global research progress and emerging hotspots related to plastic pollution in marine and inland water from 2008 to 2023, based on data from the Web of Science and CNKI databases. A total of 13872 articles were selected and analyzed, with the majority of studies conducted in analytical methods and monitoring techniques. The findings emphasize that discharge and non-degradable nature of plastic waste are the main drivers of pollution in these aquatic environments. Increasing global attention has been directed toward this issue, as reflected in the growing number of publications since 2020. At present, mainstream analytical methods for studying plastic pollution include microscopic observation, Fourier-transform infrared spectroscopy (FTIR) and Raman spectroscopy. However, field sampling efforts remain limited, with challenges such as varying mesh sizes used in trawl nets affecting data consistency. To address these limitations, future research should utilize unmanned aerial vehicles (UAVs) and advanced remote sensing technologies for monitoring plastic pollution. It should also explore the potential integration of satellite, aerial, and ground-based remote sensing into a multi-scale, comprehensive monitoring system, providing scientific insights and practical recommendations for advancing plastic pollution research and management.

The distribution characteristics of benzene, toluene, ethylbenzene and xylene (BTEX) concentrations in seawater and the atmosphere in the East China Sea in October 2020 were investigated, the sea-air exchange fluxes were evaluated, and the ecological risks and environmental effects were analyzed. The results showed the average concentrations of benzene, toluene, ethylbenzene, m/p-xylene and o-xylene were (136.8±76.8), (321.3±279.0), (530.3±530.0), (336.2±453.6) and (493.7±814.7) pmol/L in the surface seawater, respectively, and were (122.3±84.2), (217.1±162.4), (423.8±399.0), (236.8±215.1) and (344.3±288.5) pmol/L in the bottom seawater. The high values were found in the nearshore and the eastern part of the investigated sea area, of which the high values in the nearshore indicated they were influenced by land-based inputs, and the high values in the eastern part might be related to the petroleum extraction activities. The average atmospheric concentrations of benzene, toluene, ethylbenzene, m-/p-xylene and o-xylene were (110.5±45.3),(410.1±384.4), (139.5±108.8), (128.3±123.9) and (108.9±97.6) ×10^-12, and the backward trajectories showed they were affected by the input from land-based sources. The mean sea-air fluxes of benzene, toluene, ethylbenzene, m-/p-xylene and o-xylene were (25.6±13.1),(73.1±78.2), (179.9±194.5), (146.3±185.4), and (216.3±358.7) g/(km²⋅d), indicating that the investigated sea area is an important source of atmospheric. In terms of ecological risk, the concentrations of BTEX in seawater were far below the acute toxicity median effect concentration (EC50) and the half-lethal concentration (LC50) for marine organisms, indicating that BTEX posed relatively low direct harm to segmental marine life. In the atmosphere, the calculated carcinogenicity risk value (R), the non-carcinogenicity risk hazard quotient (HQ), and the non-carcinogenicity risk index (HI) were much lower than the reference values, indicating that the direct threat of atmospheric BTEX to human health was low. The analysis of O₃ and SOA generation potentials revealed that toluene and xylene were the key active components of BTEX and had the most significant impact on environmental effects.

This study focuses on five typical lakes in cold-arid areas, analyzing the phosphorus pool capacity and phosphorus migration dynamics of sediments using methods such as phosphorus fractionation, diffusive gradients in thin films (DGT), and the DGT Induced Fluxes in Sediments model (DIFS). Partial least squares path modeling (PLS-PM) was further employed to identify the key driving factors for the endogenous phosphorus pool capacity and migration dynamics in these lakes. The results showed that the average values of total phosphorus (TP_w), total nitrogen (TN_w), and nitrogen-to-phosphorus ratio (TN_w/TP_w) in the water of the five lakes were (0.81 ± 1.31)mg/L, (3.40 ± 1.87)mg/L, and (26.13 ± 22.75), respectively, indicating that these were phosphorus-limited lakes. The average total phosphorus (TP_s) content in surface sediments was (763.48 ± 563.70)mg/kg, with calcium-bound phosphorus (Ca-P) accounting for 51.09% of the TP_s. The comprehensive pollution index (FF) values for sediments indicate a severe pollution level. The biologically available phosphorus (BAP) dissolved active phosphorus (C_DGT-P), and distribution coefficient (K_d) average (193.54 ± 55.94)mg/kg, (0.19 ± 0.14)mg/L, and (11.34 ± 9.29)cm³/g, respectively. All three indicators of phosphorus pool capacity were lower than those in lakes of the eastern plains, reflecting a relatively low phosphorus reservoir capacity in cold and arid lakes. The DIFS model shows that the reaction time (T_c) of the five lakes ranges from 0.004 to 74, 170s, lower than that of lakes in the eastern plains, indicating slower phosphorus migration dynamics and a relatively lower supply rate to the water body. PLS-PM analysis reveals that the primary factor influencing phosphorus reservoir capacity in these lakes was sediment properties (0.64,P<0.05). The main factor influencing phosphorus migration dynamics (0.95, P<0.05) was the environmental conditions of the water bodies, with limited influence from lake trophic state and phytoplankton.

Taking the Pengxi River, a typical tributary bay of the Three Gorges Reservoir, as an example, continuous monitoring of the water flow, water quality, and algal bloom in the bay during the drawdown period in 2023 was carried out. The hydrodynamics, thermal stratification, and water quality evolution patterns of the tributary bay were analyzed, and the occurrence, disappearance, and influencing factors of algal blooms were revealed. The results show that during the observation period, the chlorophyll a of phytoplankton in the Pengxi River bay was positively correlated with water temperature (r=0.43, P<0.05) and euphotic layer depth (r=0.38, P<0.05), and negatively correlated with upstream inflow (r=-0.53), flow velocity (r=-0.54), and mixed layer depth Z_mix (r =-0.37). However, nutrients were not the limiting factors for the occurrence and disappearance of algal blooms. When the water temperature was suitable and the thermal stratification was stable, algal blooms began to occur. A gradual water level drawdown (<0.2m/day) fails to notably enhance flow velocity or break thermal stratification in the bay, resulting in minimal suppression of algal blooms in tributary bays. During the drawdown period, rainfall and upstream inflow could significantly affect the hydrodynamic processes and nutrient levels in the bay, which were the key factors determining the occurrence and disappearance of algal blooms in Gaoyang Lake. Increasing the discharge flow from Hanfeng Lake (>80m³/s)could effectively control algal blooms in the Pengxi River bay.

This study involved the collection and analysis of bacteria and fungi samples in water and sediment from ten typical sub-lakes of Poyang Lake. A hydrological connectivity index system for sub-lakes was established to quantitatively assess the effect of hydrological connectivity on microbial community structure. The results indicate significant differences in the α-diversity of water bacteria, sediment bacteria, and fungal communities during different stages of the dry season, sediment bacteria and fungi showed higher α-diversity during the mid-dry season. The difference in β diversity of water bacterial community was more obvious in different periods, and the β diversity of sediment bacterial and fungal communities showed spatial differences. With the increase of hydrological connectivity, the similarity of sediment bacterial and fungal communities was lower. The water area ratio (WSP) and water depth (WD) were the main hydrological connectivity variables affecting the water bacterial community structure. Lake basin elevation (LE) and WD were the main hydrological connectivity variables affecting sediment bacteria and fungi community structure. Hydrological connectivity explained less variation in water bacterial community structure (7.6%) compared to sediment bacteria (33.3%) and fungal (29.7%) community structures. The co-interpretation rate of hydrological connectivity and physicochemical factors on bacterial community structure in water was only 2.4%, and the co-interpretation rates of bacterial and fungal community structure in sediments were 9.7% and 6.2%, respectively. Sediment bacterial and fungal communities were predominantly shaped by stochastic and deterministic processes, respectively, while both processes jointly influenced water bacterial communities. Under moderate hydrological connectivity, water bacterial communities showed stronger stochastic processes, whereas as connectivity increased, stochastic processes in sediment bacteria and fungi weakened.

In order to analyse the response of bacterial community structure to the abundance of nitrogen (N) and phosphorus (P) metabolic functions in different water depths of lakes, this paper presents a characterization of the spatial distribution and correlation of bacterial community structure and the abundance of N and P related metabolic functions in the surface, middle and bottom waterbodies by high-throughput sequencing technology, with Lake Dali as the object of the study. The results showed that the composition of the dominant bacterial communities in the surface, middle and bottom water layers varied significantly with the changes in the physical and chemical properties of the water. Based on the ecological network, the dominant and important genera under the first five dominant phyla were analysed under the screening criteria of degree and abundance values, and the dominant genera in the different depths of Lake Dali were significantly changed, such as three genera in the surface and middle water, and two genera in the bottom water. Comparatively, CL500-29_marine_group and Thermus in the surface water, Synechococcus and norank_o__NB1-n in the middle water, and Synechococcus、norank_o__NB1-n、norank_f__CK06-06-Mud-MAS4B-21 in the bottom water, remained consistent with the two screening criteria. Further PICRUSt2 prediction of the functional composition of the bacterial community yielded 6 primary functions and 12 secondary metabolic functions. In particular, although Pseudomonas,Paracoccus and Synechococcus showed significant positive correlation with the abundance of N and P metabolic functions, the correlation with the N and P content of different forms was different, such as Pseudomonas showed positive correlation with the change of N and P content, Paracoccus showed negative correlation with the N and P content, and Synechococcus showed negative correlation with N and positive correlation with P elements. Overall, the differences in N and P contents caused by changes in water depth had significant effects on N and P metabolism and the dominant genera.

To investigate the effects of water flow disturbances on the growth and aggregation characteristics of Microcystis blooms, this study conducted controlled indoor experiments in a flume, with disturbance frequencies set at 30, 40, 50, and 60min^-1. The growth dynamics and size variation of Microcystis colonies were systematically analyzed under varying disturbance conditions. The results showed that low-intensity water flow disturbances (frequency<40min^-1 or velocity<0.026m/s) significantly promote the secretion of extracellular polymeric substances (EPS) in Microcystis, with a strong correlation observed between Chlorophyll-a and EPS concentrations (r²>0.85). Conversely, high-intensity disturbances (frequency>50min^-1 or velocity>0.034m/s) inhibited EPS secretion, leading to a weakened correlation between Chlorophyll-a and EPS concentrations (r²<0.8). Within the experimental ranges of flow velocity (0~0.08m/s) and turbulent kinetic energy (0~0.004m²/s²), the size of Microcystis colonies exhibited minimal variation (ranging from 0.4~0.6mm). Furthermore, low-intensity disturbances facilitated the formation of surface blooms with shorter durations, whereas higher-intensity disturbances suppressed bloom aggregation while extending algal survival periods.

A typical urban lake (Xinghu Lake) in the Guangdong Hong Kong Macao Greater Bay Area was selected as the study area, and the density flotation method was used to extract microplastics from surface sediments. The spatiotemporal occurrence characteristics of microplastic were presented, and the potential ecological risks of microplastic were revealed, and the spatial autocorrelation of microplastic abundance was analyzed. The results showed that the average abundances of microplastic in surface sediments of Xinghu Lake were (637±392) and (1765±883) particles/kg during the wet and dry seasons, respectively. Here, the colors of microplastic were mainly blue and black, lines were the dominant microplastic shapes, and the size of microplastic was concentrated in the range of 100 to 2000µm. Rayon, polypropylene, and polyethylene terephthalate were the main polymer types of microplastic in surface sediments of Xinghu Lake during the wet and dry seasons. The abundances of microplastic in surface sediments of Xinghu Lake showed a strong spatial autocorrelation during different seasons, and the sampling interval for microplastic should be less than 435m here. Meanwhile, the average comprehensive potential ecological risk indexes of microplastic in surface sediments of Xinghu Lake were 53.0 9and 344.08 during the wet and dry seasons, which were the slight and very strong risk levels, respectively. Furthermore, the potential ecological risks of rayon microplastics were relatively high.

To investigate the relative importance of the bottom-up versus top-down on phytoplankton biomass in the estuary and its adjacent waters of the Yellow River during the water and sediment regulation scheme (WSRS), the study utilized R2V software to extract historical data (2011~2020) on chlorophyll a (Chl a) concentration, environmental factors, and zooplankton abundance in the estuary and its adjacent waters of the Yellow River from the literature. The spatial distribution and interannual variation of Chl a concentration was analyzed, and regression tree models Chl a with environmental and biological factors at different stages of WSRS were developed to explore the controlling factors. The results showed that Chl a concentrations in the estuary and its adjacent waters of the Yellow River generally decreased from the estuary towards offshore areas from 2011 to 2020. As WSRS progressed, the high-value areas gradually shifted to the nearshore northwest of the estuary. Regions with significant interannual variations in Chl a concentrations largely overlapped with high-value areas at each stage. The regression tree model indicated that, with the progression of water and sediment regulation, there was a notable shift in the dominant effects on Chl a concentration. Before WSRS, the top-down effect of zooplankton grazing was the primary driver of Chl a spatial variability. During the water and sediment regulation period, Chl a concentration was mainly controlled by bottom-up effects. In the early WSRS, temperature was the primary driving factor, while in the later stage of WSRS, dissolved inorganic phosphorus (DIP) became the main driving factor. The changes in salinity fronts caused by freshwater flow during WSRS may be an important factor inducing changes in the dominant effects on Chl a concentration.