The rapid detection of biological toxicity of Marine pollution is of great significance to the emergency monitoring of sudden Marine water pollution accidents, the rapid investigation and evaluation of Marine environment ecological risks, and the protection of Marine environment. However, existing biological toxicity detection methods have a long toxic response time, and it is difficult to realize the rapid response of Marine pollutants. In view of this, this study has taken the active marine microalgae, Platymonas subcordiformis, as the test organism to study its mobility response to typical heavy metal pollutants Mercury（Hg）and Chromium（Cr）in seawater, in order to provide a basis for establishing a rapid detection method for marine biological toxicity. The results ha showed that within 2h, the motion parameters of the Platymonas subcordiformis, including movement mode, movement ability, and swimming velocity, exhibited significant response characteristics to 0.075~2.5mg/L Hg and 0.1~3mg/L Cr, and there was a good dose-response relationship between the motion parameters and the concentrations of the two independent heavy metals；The 2h-EC₅₀ values of Hg and Cr obtained based on different motion parameters were 0.63~2.38mg/L and 0.60~2.49mg/L, respectively；Overall, among different motion parameters, the curve velocity（VSL）has the most sensitive response to the toxicity of heavy metals Hg and Cr. The 2h-EC₅₀ values of Hg and Cr obtained using VSL as the response index are 0.63 and 0.60mg/L respectively. The above results are comparable to traditional toxicity tests（including microalgae 72-hour growth inhibition test, 24~48 hours photosynthesis inhibition test, and 96-hour fish death test）, and the toxicity response time is significantly reduced, indicating that microalgae motility as a new biological testing indicator can quickly and effectively evaluate the toxicity of marine heavy metal pollutants.

Based on the analysis of the material composition and mercury（Hg）content in the surface sediments of the Yellow River subaqueous delta, the distribution characteristics and influencing factors of Hg in the region were examined. The results showed that the Hg content in the surface sediments ranged from 15.09 to 53.11µg/kg, with an average content of 36.32µg/kg, which was relatively low compared to other domestic and international marine areas. The Hg content in the sediments exhibited a'low-high-low-high' pattern from the shore to the sea, with peak concentrations observed at the shear front and in the fine-grained sediment areas offshore. Elevated Hg levels were also found in the sediments near Laizhou Bay in the southern region. Hg was primarily derived from natural sources but was also influenced by emissions from human activities. Hydrodynamic conditions played a crucial role in controlling the distribution of Hg, with a tendency for Hg to accumulate in fine-grained sediments. The 'filter' effect of the estuary, especially the shear front, significantly influenced the spatial distribution of Hg and its transport to the open sea. The distribution of Hg was also related to its carriers, such as organic carbon, carbonate minerals, and iron-manganese oxides. These carriers directly bound with Hg, affecting its distribution, and also influenced the properties of the sediments, thus indirectly influencing the distribution of Hg.

This research conducted an experiment on DNAPL contamination in a saturated porous medium within a three-dimensional sandbox and performed synchronized dynamic monitoring using electrical resistivity tomography（ERT）. The resistivity images obtained from ERT were used to determine the spatial distribution of DNAPL contaminants, which were then compared with the numerical simulation model established in the sandbox experiment. The absolute value of the relative error in the diameter of the DNAPL distribution area obtained from the numerical simulation and the DNAPL distribution area determined by the ERT monitoring ranged from 2.00% to 27.50% across different spatial locations. The absolute value of the relative error in the diameter of the DNAPL distribution area obtained from the numerical simulation and the DNAPL distribution area determined by the ERT monitoring ranged from 2.7% to 40.58% at different time points. The results demonstrate the feasibility of using the numerical simulation software Petrasim to predict the distribution range of DNAPL contamination in saturated sandy soil.

Poyang Lake is characterized by significant water level fluctuations, leading to complex transformation processes among precipitation, soil water, and groundwater. Due to the limitations of intricate wetland conditions and traditional monitoring methods, it is challenging to conduct quantitative studies on soil water movement and its interaction with groundwater. In this study, three vegetation communities at different elevations in Poyang Lake were investigated to analyze the isotopic composition of precipitation, lake water, groundwater, and soil water（0~80cm）. The characteristics of wetland soil water movement were examined across various hydrological periods. The results showed that the slope of the soil evaporation line（SEL）in the Artemisia capillaris community（5.91）was significantly lower than that of the local meteoric water line（LMWL, 7.60）. The lc-excess values of soil water in 0~60cm layer were negative, indicating strong evaporation, with a maximum impact depth of 60 cm. The slopes of the SEL in the Phragmites australis and Carex cinerascens communities（6.70 and 6.75, respectively）were slightly lower than the LMWL, and the lc-excess values of soil water were close to 0, indicating minimal evaporation. Regarding soil water movement, the δ¹⁸O values of soil water in the A. capillaris community increased with depth during spring（May）and summer（June to August）, indicating piston-flow dominated transport. During autumn（September and October）, soil water δ¹⁸O values became enriched and decreased with depth, indicating the dominant influence of evaporation. Furthermore, the soil water δ¹⁸O values in the A. capillaria community were significantly enriched compared to groundwater isotopes. No depleted isotope signals or evidence of groundwater supply were detected in the soil water, even when the groundwater table was at its shallowest（1.92m）. These results suggest that vertical hydrological connectivity between root-zone soil water and groundwater was blocked. In contrast, soil water movement in the P. australis and C. cinerascens communities was significantly influenced by groundwater level fluctuations. During the groundwater level rise period（April and May）, shallow soil water（0~40cm）in these two communities primarily originated from atmospheric precipitation, while deep soil water（40~80cm）was replenished by capillary rise of groundwater. Groundwater contributed more than 50% to the replenishment of root-zone soil water. During the shallow groundwater table period（June and August）, frequent exchanges occurred between soil water and groundwater in the P. australis community. In the groundwater table decline period（September and October）, the P. australis and C. cinerascens communities exhibited non-uniform soil water flow processes, characterized by noticeable preferential flow.

Using the Gansu section of the Yellow River Basin as the research object, Fragstats 3.3 software and Pearson correlation analysis method were used to calculate the landscape pattern index of the river buffer zone, analyze the correlation between water quality and landscape pattern indicators, and investigate the factors influencing the water quality of the Yellow River’s main stream and tributaries in Gansu Province. The data included the land use data with the resolution of 30m in 2020, water quality monitoring data, and socio-economic data from 2018 to 2021. The results indicated that:（1）From 2018 to 2021, the water quality of the main stream and tributaries of the Yellow River in Gansu Province were improving, except the Taohe River, where the concentration of water quality indicators was in the increasing trend；however, TN at more than 80% of monitoring sites remained above Class V water quality standards, with significant nitrogen pollution persisting in the Weihe River, Jinghe River, and Zhuanglang River. High concentrations of TN and NH₄⁺-N were mainly distributed in the central and eastern parts of the basin, TP levels were elevated across most areas, and COD was dispersed, with hotspots concentrated in parts of Lanzhou City and central Linxia Hui Autonomous Prefecture.（2）A significant correlation was observed between landscape patterns and water quality indicators. Higher aggregation and connectivity of landscape patches were associated with better water quality, whereas higher levels of fragmentation and dispersion increased the risk of water pollution.（3）Water quality indicators exhibited strong spatial heterogeneity. The driving factor analysis revealed that NH₄⁺-N, TP, permanganate index, and COD were primarily influenced by rural activities, while TN and DO were mainly affected by urban living and industrial production.

Based on core sampling, sequential extraction procedure in the laboratory, correlation analysis between sediments and groundwater, and mineral saturation index（SI）of groundwater, this paper explored the distribution, form and influencing factors of RIS in Quaternary sediments in the middle and lower reaches of Chaobai alluvial-proluvial fan, in Beijing. Results showed that the content of RIS in the study area followed a descending order of: Pyrite-S（CRS）>essential sulfur（ES）>acid volatile sulfide（AVS）, among which CRS accounting for 80.1%, ES and AVS accounting for 13.4% and 5.56% respectively. 67% of samples had CRS/AVS value higher than 3. The RIS content in sediments in the upper reaches was lower than that in the lower reaches, and RIS contents in the four aquifers from shallow to deep were 84.3, 37.4, 39.1 and 10.5mg/kg respectively, showing an overall decreasing trend. The results of RDA and correlation analysis indicated that the TOC content, CRS/AVS value and water content in sediments were crucial factors affecting the content and form of RIS in the study area. Specifically, the content of RIS was also affected by the groundwater pH value, iron/sulfur ratio and hydrogeological conditions, and the form of RIS was affected by the COD_Mn and ORP of groundwater. The SI value of FeS in groundwater fluctuated around 0, and the SI value of FeS₂>0. In summary, RIS in the sediments of the study area is basically unaffected by human disturbance, and the activity and bioavailability of sulfide are low. The sediments may affect the concentrations of sulfate, sulfide, iron and arsenic in groundwater mainly through AVS precipitation/dissolution and ES disproportionation reaction.

In this study, a pot experiment was conducted to simulate soil contaminated with varying levels of cadmium（Cd）, arsenic（As）, and lead（Pb）to investigate the changes in biomass, the absorption and accumulation of mineral nutrients, as well as the accumulation characteristics of heavy metals under different contamination conditions. Furthermore, soil threshold for Cd, As, and Pb in acidic soil were derived to ensure the safe production of cherry radish. The results indicated that cherry radish exhibited significant toxic effects when heavy metals content added in soil reached the risk control threshold. The contents of iron（Fe）, copper（Cu）, and zinc（Zn）in root of cherry radish increased initially and then decreased as the level of heavy metals contamination increased, while manganese（Mn）content continuously increased. The root of cherry radish had the highest enrichment and translocation ability for Cd, with average bioconcentration factors（BCF）being 18.6 and 115 times higher than those for As and Pb, respectively. The average translocation factors（TF）for Cd were 4.02 and 2.41 times higher than those for Pb and As, respectively. Based on the National Food Safety Standard（GB2762—2022）, and considering the safety of both the roots and shoots of cherry radishes, the derived soil threshold values for safe cherry radish production in acidic soil were 0.30mg/kg for Cd, 171.1mg/kg for As, and 27.5mg/kg for Pb.

The effects of three different influent strategies on the protein content of extracellular polymeric substances（EPS）were investigated to assess their impact on sludge retention capacity of the CANON process. R1was operated under conventional influent strategy as the control group, while R2 and R3 were subjected to different variable influent strategies. After 90 days of operation, the SVI values in R1, R2, and R3 were 62.93, 53.10, and 57.59mL/g respectively indicating that the variable influent strategies could improve sludge settleability. The PN/PS ratios were significantly higher in R2（8.21）and R3（7.61）compared to R1（5.56）. Three-dimensional fluorescence analysis revealed that the proportion of aromatic proteins in TB-EPS was highest in R2（32.47%）, much higher than in R1（11.58%）and R3（10.5%）. This indicated that the variable influent strategy promoted the formation of aromatic proteins in TB-EPS, enhancing the hydrophobicity of the sludge and improving settleability. The specific anaerobic ammonium oxidation activity（SAA）increased to 4.03, 4.68 and 4.36mg N/（g VSS· h）in R1, R2, and R3, respectively. Notably, the SAA in R2 and R3 exceeded that of the seed sludge, indicating the successful formation of mature CANON granular sludge. Although microbial activity in R2 and R3 was initially inhibited by loading fluctuations during early operation, the microbial communities gradually adapted to environmental fluctuations and regained stable metabolic activity, successfully operating the CANON process on day 54 and day 51, respectively. Total nitrogen removal efficiencies reached approximately 72.54%, 70.14%, and 73.75% in R1, R2 and R3 by day 90, demonstrating effective nitrogen removal performance.

This study investigated the functional characteristics of plant growth-promoting rhizobacteria（PGPR）isolated from the rhizosphere soil of Celosia argentea Linn., a Cd-hyperaccumulator. A strain with high tolerance to Cd^2-, Pb^2-, and Zn^2- was isolated. This strain was identified using physiological and biochemical characteristics analysis and sequence analysis of the 16S rDNA and nrdA functional genes. The effects of various culture conditions on the strain's growth and heavy metal removal capabilities, as well as its potential for promoting plant growth were examined. This strain was identified as Achromobacter sp., designated WL-37. The minimum inhibitory concentrations（MIC）of Cd^2-, Pb^2-, and Zn^2- for strain WL-37 were determined to be 600, 1800, and 1000mg/L, respectively. Under optimized conditions（e.g., pH values and inoculation amounts）, the strain achieved maximum removal rates of 69% for Cd²⁺, 95% for Pb²⁺, and 62% for Zn²⁺. Moreover, WL-37 exhibited multiple plant-promoting traits, including nitrogen fixation, ACC deaminase production, and siderophore production. In summary, the high-efficiency strain identified in this study represents a valuable resource for the remediation of multi-metal contaminated soils and supports the development of plant-microbe combined remediation technologies.

The study analyzed the effects of different mulching durations（4 to 19 years）on the characteristics of microplastics in the soil of peanut fields. The results showed that as the mulching duration increased, the abundance of microplastics in the soil tended to rise. Compared with a mulching duration of 4 years, the abundance of microplastics in the soil with a mulching duration of 19 years varied between 660 and 3150 pieces/kg. The abundance of microplastics with a small particle size（<2mm）increased with both the mulching duration and soil depth. Long-term continuous mulching promoted the penetration of microplastics into deeper soil layers, which was specifically reflected in the fact that microplastics with a small particle size accounted for 49.9% in the 20~30cm soil layer. In sampling points with different mulching durations and soil depths, the color of microplastics was predominantly transparent, followed by black, green, and purple, while other colors such as red had relatively lower proportions. The shapes of microplastics included fibrous, foamy, film-like, fragmental, and granular, with fibrous shapes being the most dominant. Moreover, the polymer types of microplastics were diverse, mainly consisting of PE（polyethylene, 34.2%）, PP（polypropylene, 17%）, and PS（polystyrene, 16.3%）. In summary, the increase in mulching duration significantly affected the proportion of transparent microplastics in the soil, but had no significant impact on the types of microplastics and polymers.