Helical Nanographenes Bearing Pentagon-Heptagon Pairs by Stepwise Dehydrocyclization.

The incorporation of pentagon-heptagon pairs into helical nanographenes lacks a facile synthetic route, and the impact of these pairs on chiroptical properties remains unclear. In this study, a method for the stepwise construction of pentagon-heptagon pairs in helical nanographenes by the dehydrogenation of [6]helicene units was developed. Three helical nanographenes containing pentagon-heptagon pairs were synthesized and characterized using this approach. A wide variation in the molecular geometries and photophysical properties of these helical nanographenes was observed, with changes in the helical length of these structures and the introduction of the pentagon-heptagon pairs. The embedded pentagon-heptagon pairs reduced the oxidation potential of the synthesized helical nanographenes. The high isomerization energy barriers enabled the chiral resolution of the helicene enantiomers. Chiroptical investigations revealed remarkably enhanced circularly polarized luminescence and luminescence dissymmetry factors with an increasing number of the pentagon-heptagon pairs.

Effects of dissolved organic matter from sediment and soil samples on the growth and physiology of four bloom-forming algal species.

Algal blooms negatively impact the water quality of reservoirs; however, the role of dissolved organic matter (DOM) in bloom formation in reservoirs has not been investigated. Therefore, we assessed the compositions of sediment- and soil-derived DOM and their effects on the growth, physiology, and photosynthetic activity of Microcystis aeruginosa, Anabaena sp., Chlamydomonas sp., and Peridiniopsis sp. (bloom-forming species). Sediment DOM promoted the growth of all algal species, whereas soil DOM significantly promoted the growth of Chlamydomonas sp. and Peridiniopsis sp.; this effect was due to enhanced stress tolerance and photosynthetic efficiency exhibited by these algae under DOM treatment. However, soil DOM slightly inhibited the growth of Anabaena sp. by increasing reactive oxygen species levels and inactivating some photosystem II reaction centers. The tyrosine-like substance, humic acid-like substances, and unsaturated aliphatic compounds were the main DOM components that affected algal growth. The findings of this study will provide a theoretical foundation for the development of bloom-prevention strategies for river-type reservoirs.

Effects of dissolved organic matter derived from two herbs on the growth, physiology, and physico-chemical characteristics of four bloom-forming algae species.

While algal blooms occur frequently in lakes and reservoirs worldwide, the effects of dissolved organic matter (DOM) from lakeside and riparian zones on bloom formation are not well understood. In this study, we characterized the molecular composition of DOM from Cynodon dactylon (L.) Pers. (CD-DOM) and Xanthium sibiricum Patrin ex Widder (XS-DOM) and assessed their effects on the growth, physiology, volatile organic compounds (VOCs), and stable carbon isotope in four bloom-forming algae species (Microcystis aeruginosa, Anabaena sp., Chlamydomonas sp., and Peridiniopsis sp.). Stable carbon isotope analysis showed that the four species were affected by DOM. Both DOM types increased the cell biomass, polysaccharide and protein contents, chlorophyll fluorescence parameter values, and VOCs release of Anabaena sp., Chlamydomonas sp. and Microcystis aeruginosa, suggesting that DOM stimulated algal growth by increasing nutrient sources, photosynthetic efficiency, and stress tolerance. And in general, these three strains exhibited better growth at higher DOM concentrations. However, DOM treatment inhibited the growth of Peridiniopsis sp., as indicated by the increases in reactive oxygen species, damage in photosystem II reaction centers, and blockage in electron transport. Fluorescence analysis showed that tryptophan-like compounds were the main DOM components that affected algal growth. Molecular-level analysis suggested that unsaturated aliphatic compounds may be the most important DOM components. The findings indicate that CD-DOM and XS-DOM promote the blue-green algal blooms formation and thus should be considered in the management of natural water quality.

Spatiotemporal dynamics of phytoplankton biomass and community succession for driving factors in a meso-eutrophic lake.

Effects of climate change and nutrient load caused by human activities on lake phytoplankton blooms have attracted much attention globally. However, their roles and synergistic effects on phytoplankton biomass and community historical succession are not well understood, especially for meso-eutrophic plateau lakes. In this study, a multi-year (1997-2022) monthly dataset including hydro-chemical and meteorological indicators of the meso-eutrophic plateau lake Erhai in China, was used to explore the contributions of climate change and nutrients on phytoplankton biomass variation and community succession. Phytoplankton biomass increased from 1997 to 2006, slowly decreased from 2006 to 2015, then increased again from 2015 to 2022, according to a generalised additive model (GAM). Alongside warming, nitrogen, phosphorus and organic matter are key drivers of long-term interannual variation in phytoplankton biomass and historical succession of the phytoplankton community. The extensive blooms in recent years were strongly associated with both organic matter accumulation and global warming. Phytoplankton biomass in northern and southern districts was greater than in central areas, with Cyanophyta and Pyrrophyta dominating in the north and Chlorophyta prevalent in the south. Since 2015, phytoplankton diversity has increased significantly, and biomass has declined in the southern district but increased markedly in the northern district. Spatial heterogeneity was caused by the spatial distribution of nutrients and the buoyancy regulation capacity of cyanobacteria. The results demonstrate that bloom mitigation responds strongly to nitrogen and phosphorus control in meso-eutrophic lakes, therefore preventing and controlling blooms through nitrogen and phosphorus reduction is still an effective measure. Given the accumulation of organic matter in recent years, synergistic control of organic matter and total nitrogen and phosphorus could effectively reduce the risk of cyanobacterial and dinoflagellate blooms.

A comprehensive assessment of upgrading technologies of wastewater treatment plants in Taihu Lake Basin.

To meet the increasingly stringent discharge standards of wastewater treatment plants (WWTPs) in the Taihu Lake Basin, the Chinese government successively established the National Special Water Project Program to develop new technologies to retrofit and upgrade existing wastewater treatment processes during the 11th, 12th, and 13th Five-Year Plans. However, there is a lack of systematic sorting of the existing research outcomes, and thus hinders the application and promotion of the upgrade technologies. Based on the outcomes of the National Special Water Project and a field survey, this research analyzed the current status of wastewater treatment in the Taihu Lake Basin and systematically integrated the retrofitting measures of WWTPs in terms of achieving the Grade IA of the national standard and local stricter discharge standards (DB 32/1072-2018 and DB 33/2169-2018). In particular, the boundary conditions, design parameters, specific recommendations of the technologies, and some typical engineering cases were provided accordingly. Finally, this study discussed the future development directions of WWTPs during the upgrade process from the perspective of carbon neutrality and digitalization. The present work will hopefully assist in retrofitting and constructing WWTPs to achieve the stricter effluent discharge criteria and help optimize the design and construction of WWTPs in the best way.

Management of water quality targets based on river-lake water quality response relationships for lake basins - A case study of Dianchi Lake.

In a lake basin, there is a mismatch between river and lake water quality targets and a method for setting specific water quality targets for these rivers is urgently needed. Using Dianchi Lake as an example, we proposed a lake basin water quality management system based on the river-lake water quality response relationship, coupled with a Soil and Water Assessment Tool (SWAT) basin hydrological model and Environmental Fluid Dynamics Code (EFDC) lake water quality hydrodynamic model. River water quality control requirements based on the river-lake water quality response were proposed, under the premise that the Dianchi Lake water quality reaches the required standard. Then, water quality control targets for rivers were determined, and corrected for influencing factors, such as current river water quality and composition of flow. Our systematic approach efficiently identified key lake basin pollution sources, and accurately located key points for water quality improvement and pollution control. Combined with a correction for clean water source and current water quality of each river, the proposed water quality targets were practical and operable. Meanwhile, the EFDC model was used to verify the entire process to ensure that river water quality targets could be set to achieve lake water quality targets. To ensure that Dianchi Lake water quality can reach Class IV standard, the Chemical oxygen demand (COD) concentration would need to be maintained under 30 mg/L,Waihai total nitrogen (TN) below 7 mg/L, total phosphorus (TP) below 0.2 mg/L, and ammonia nitrogen (NH3-N) below 2 mg/L.

Distribution characteristics and health risk assessment of volatile organic compounds in the groundwater of Lanzhou City, China.

Volatile organic compounds (VOCs) typically exist in the aqueous environment due to global anthropogenic activities. The distribution and contaminated profile (or characteristics) of VOCs in the groundwater of Lanzhou, China, were investigated in this study. Groundwater samples were collected from 30 sampling points in December 2015, and a total of 17 VOCs were analyzed by purge and trap gas chromatography-mass spectrometry. Thirteen types of VOCs were detected at 29 sampling points in the study area. Of these, dichloromethane and toluene, which were found at 22 sampling points, had the highest detection frequency (73.3%), followed by benzene (66.7%), 1,2-dichloroethane (50%), and xylenes (50%). The highest average concentration among the detected VOCs was found for chloroform (5151.5 µg/L). The spatial distribution of VOC contamination in four major urban areas of Lanzhou and the variation in VOC concentration caused by land use transitions were also analyzed. The results showed that Xigu district was the most polluted area in Lanzhou, mainly due to land use for industrial proposes. On the contrary, the samples for Anning district showed lower VOC concentrations because of better groundwater quality, which is associated with the absence of manufacturing industries in this region. The health risk assessment model developed by the United States Environmental Protection Agency was employed in this study to evaluate safety for drinking water use. This study found that despite considering the volatilization of VOCs from water due to heating, six sampling points (G05 in Qilihe district; G07 and G09 in Xigu district; G16, G17, and G15 in Chengguan district) showed non-carcinogenic risks, ranging from 1.63 to 14.2, while three points (G16 in Chengguan district, and G10 and G07 in Xigu district) exhibited high carcinogenic risks for human health, ranging from 2.94 × 10-4 to 6.85 × 10-4. Trichloroethylene, tetrachloroethylene, and 1,2-dichloroethylene were identified as the dominant VOCs, presenting high non-carcinogenic risk. 1,2-dichloroethane and vinyl chloride were the primary factors for high carcinogenic risk. The high-risk areas were concentrated in Xigu and Chengguan districts, suggesting the need to alert the relevant local government departments.

High contamination, bioaccumulation and risk assessment of perfluoroalkyl substances in multiple environmental media at the Baiyangdian Lake.

The contamination of perfluoroalkyl substances (PFASs) in the Baiyangdian Lake has exacerbated readily since 2008. This study analyzed the perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkane sulfonic acids (PFSAs) in the surface water, sediment, and fish of the Baiyangdian Lake. In the surface water, the total concentration of PFASs ranged in 1193-3462 ng L-1 (mean 1734 ng L-1) in the rainy season and 469-1724 ng L-1 (mean 876 ng L-1) in the dry season. The total concentration of PFASs in the sediment ranged in 1.97-13.3 ng g-1 (mean 6.53 ng g-1). It was found that PFCAs and PFSAs with longer chains were more easily adsorbed in the sediment. Among the collected fish samples, the enrichment of PFASs in the tissues fell in the order of liver > cheek > muscle. For the muscle, stomach, and liver tissues of the fish samples, significant correlations existed between the δ15N values and the concentration of perfluorooctane sulfonic acid (PFOS). The contents of PFOS and perfluorooctanoic acid (PFOA) in the fish were not at a level high enough to significantly risk human health.

Use of multiple water surface flow constructed wetlands for non-point source water pollution control.

Multiple free water surface flow constructed wetlands (multi-FWS CWs) are a variety of conventional water treatment plants for the interception of pollutants. This review encapsulated the characteristics and applications in the field of ecological non-point source water pollution control technology. The roles of in-series design and operation parameters (hydraulic residence time, hydraulic load rate, water depth and aspect ratio, composition of influent, and plant species) for performance intensification were also analyzed, which were crucial to achieve sustainable and effective contaminants removal, especially the retention of nutrient. The mechanism study of design and operation parameters for the removal of nitrogen and phosphorus was also highlighted. Conducive perspectives for further research on optimizing its design/operation parameters and advanced technologies of ecological restoration were illustrated to possibly interpret the functions of multi-FWS CWs.

Distribution characteristics of poly- and perfluoroalkyl substances in the Yangtze River Delta.

In this work, a method was developed and optimized for the analysis of polyfluoroalkyl and/or perfluoroalkyl substances (PFASs) content in surface water and sediment samples with high instrumental response and good separation. Surface water and sediment samples were collected from the Yangtze River Delta (YRD) to analyze the distribution characteristics of perfluoroalkyl carboxylic acids (PFCAs), perfluoroalkane sulfonic acids (PFSAs), perfluoroalkyl phosphonic acids (PFPAs), perfluoroalkyl phosphinic acids (PFPiAs), and polyfluoroalkyl phosphoric acid diesters (diPAPs). The results showed that the total concentrations of PFCAs and PFSAs in YRD varied from 31 to 902ng/L. PFCAs (≥11 carbons) and PFSAs (≥10 carbons atoms) were not detected in any surface water samples. The mean concentrations of all PFCAs and PFSAs in surface water from the sampling areas decreased in the following order: Yangtze river (191ng/L)≈Taihu lake (189ng/L)>Huangpu river (122ng/L)≈Qiantang river (120ng/L)>Jiaxing urban river (100ng/L). Strong significant (p<0.05) correlations between the concentrations of many of the compounds were found in the sampling areas, suggesting a common source for these compounds. Only perfluorooctanoic acid (PFOA) was observed in all sediment samples, at concentrations varying from 0.02 to 1.35ng/g. Finally, detection rates of two diPAPs were only 8% and 10%, respectively and the concentration of diPAPs was two to three times lower compared to PFCAs and PFSAs.

Molecular-Scale Study of Aspartate Adsorption on Goethite and Competition with Phosphate.

Knowledge of the interfacial interactions between aspartate and minerals, especially its competition with phosphate, is critical to understanding the fate and transport of amino acids in the environment. Adsorption reactions play important roles in the mobility, bioavailability, and degradation of aspartate and phosphate. Attenuated total reflectance Fourier-transform infrared (ATR-FTIR) measurements and density functional theory (DFT) calculations were used to investigate the interfacial structures and their relative contributions in single-adsorbate and competition systems. Our results suggest three dominant mechanisms for aspartate: bidentate inner-sphere coordination involving both α- and γ-COO(-), outer-sphere complexation via electrostatic attraction and H-bonding between aspartate NH2 and goethite surface hydroxyls. The interfacial aspartate is mainly governed by pH and is less sensitive to changes of ionic strength and aspartate concentration. The phosphate competition significantly reduces the adsorption capacity of aspartate on goethite. Whereas phosphate adsorption is less affected by the presence of aspartate, including the relative contributions of diprotonated monodentate, monoprotonated bidentate, and nonprotonated bidentate structures. The adsorption process facilitates the removal of bioavailable aspartate and phosphate from the soil solution as well as from the sediment pore water and the overlying water.

Characterization of Mixing Processes in the Confluence Zone between the Three Gorges Reservoir Mainstream and the Daning River Using Stable Isotope Analysis.

Understanding the interaction processes between the mainstream and its tributaries and detailing the rates of contribution of water and nutrients from two different waterbodies in the confluence zone are essential for water management in the Three Gorges Reservoir (TGR). The stable isotope ratios of hydrogen (δD) and oxygen (δ(18)O) were applied to explore the interactions between the TGR mainstream and a typical tributary, the Daning River. The results of the model calculations showed that approximately 78.9% of the water and 88% of the nitrate in the confluence zone were from the TGR mainstream. The dynamic vertical distributions of the mixing ratios, major ion contributions, and flow velocities indicated that the water mass from the Yangtze River mainstream flowed backward from the confluence zone up to the tributary along the surface and upper-middle layers, whereas water from the tributary flowed into the mainstream through the lower-middle and bottom layers. This study demonstrates the value of hydrogen and oxygen isotope tracers in accurately describing water mass mixing processes and estimating the rates of contribution of different nutrient sources in the confluence zone, which will provide valuable information for controlling algal blooms in the future.

Three Gorges Reservoir: density pump amplification of pollutant transport into tributaries.

The impoundment of the Three Gorges Reservoir (TGR) on the Yangtze River in China burdened its tributary backwaters with severe environmental problems.1 Confluence zones of reservoir tributaries with the Yangtze River main channel are main drivers of pollutant dynamics in the TGR2 and are thus keys to develop mitigation measures. Here, we show a novel experimental approach of spatiotemporal water quality analysis to trace water mass movements and identify pollutant transport pathways in reservoir water bodies. Our results show the movements of density currents in a major tributary backwater of the TGR. A huge interflow density current from the Yangtze River main channel transported its heavy metal carriage to the upstream reaches of the tributary backwater. Water from the upstream backwater moved counterwise and carried less but pollutant-enriched suspended sediments. This scenario illustrates the importance of confluence zone hydrodynamics for fates and pathways of pollutants through the widely unknown hydrodynamics of new reservoirs.

Integrated biomarkers in wild crucian carp for early warning of water quality in Hun River, North China.

Metabolizing enzymes play important roles in the detoxification of various pollutants in aquatic organisms, thereby they can also be used to provide early-warning signals of environmental risks. Real-time quantitative reverse-transcription polymerase chain reaction assays were developed to quantify cytochrome P450 1A (CYP1A), superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT), and glutathione-S-transferase (GST) in crucian carp (Carassius auratus). The methods were then used to detect the respective mRNA expression levels in liver tissue in wild crucian carp from the Hun River, North China. CYP1A mRNA expression was significantly up-regulated in fish from stations S5, S6, and S8 (p < 0.05). SOD mRNA expression was significantly down-regulated in downstream areas relative to fish from upstream sites (p < 0.05); GPx and CAT mRNA expression levels were also down-regulated at S9 (p < 0.05). In contrast, GST mRNA expression showed no obvious change between fish collected from up- or downstream areas of the river. Finally, an integrated biomarker response was used to evaluate the integrated impact of pollutants in the Hun River and allow better comprehension of the real toxicological risk of these investigated sites.

[Optical signatures of chromophoric dissolved organic matter in water body of Tien Lake].

The water samples of the Tien Lake were collected for the three-dimensional fluorescence spectrum detected. And parallel factor analysis (PARAFAC) and principal component analysis (PCA) were used for the spectra analyzing to know the main factor and relative contribution of the chromophoric dissolved organic matter (CDOM). PARAFAC decomposed CDOM into four components, the humic-like: C1 (240, 415), C3 (265, 525), C4 (255, 505) and the protein-like: C2(230/280, 330). The fluorescence intensity of CDOM components was high in north and estuary of the lake, but low in the other region. All the four components show significant positive correlations (p < 0.01), this result means they may have the same sources. Principal component analysis shows that these four components of the Tien Lake are all from terrestrial organic matter, meanwhile its DTN, DTP, DON may also come with the terrestrial substance. These components of Tien Lake can well be connected with dissolved nutrient salts by nonlinear multiple regression, which means we can use the three-dimensional fluorescence spectrum results of CDOM to indicate the eutrophication degree of Tien Lake.

[Distribution Characteristics and Risk Assessment of Organophosphates in Water and Sediment in Dongting Lake].

Organophosphates （OPEs） are widely used as flame retardants and additives and thus are commonly detected in the environment. In order to explore their environmental behavior, the concentrations of 13 OPEs in the surface water and sediment of Dongting Lake were analyzed using UPLC-MS/MS. The results showed that 11 OPEs were detected, with detection frequencies of 5.26%-100% and 58.3%-100%, and the concentrations of OPEs were 2.06-2 028 ng·L-1 and 19.6-2 232 ng·g-1 in water and sediment, respectively. Overall, contamination concentrations were ranked in descending order as follows： inflowing rivers, lake area, and outlet, whereas the spatial distribution of concentrations in sediment was inversely proportional to hydrodynamics. The concentration of OPEs in Dongting Lake was at a high level compared with that of domestic and foreign lakes. Among the detected 11 OPEs, tri-iso-butyl phosphate （TnBP） and （TiBP） were dominant in water, accounting for 52.3% and 22.4% of ∑OPEs, respectively. TPhP was the dominant OPEs in sediment, accounting for 31.2% of ∑OPEs. The correlation and principal component analysis indicated that OPEs pollution in Dongting Lake was mainly affected by industrial production emissions, fishery aquaculture, and atmospheric deposition. The assessment results of the risk entropy showed that most of the detected OPEs in water had relatively low ecological risks, whereas the ecological risk of 2-ethylhexyl diphenyl phosphate （EHDPP） at some sampling points requires further attention.

The storm runoff management strategy based on agricultural ditch nutrient loss characteristics in Erhai Lake, China.

Initial flush management is an effective measure to control non-point source pollution (NPSP) in storm runoff. However, determining the parameter of the initial flush in different areas may pose challenges in storm runoff management strategies. To address this issue, Erhai Lake in China, Yunnan-Guizhou Plateau, was selected as an example for the study. Erhai Lake is a typical mesotrophic lake with the profound influence of NPSP. The NPSP control strategy in this area will provide a valuable reference for other lakes. In 2021, 289 storm events and 190 ditchwater samples were detected around Erhai Lake. The average flow in the ditches ranged from 0.004 to 0.147 m3/s, the instant total nitrogen (TN) concentration ranged from 0.28 to 91.43 mg/L, and the instant total phosphorus (TP) concentration ranged from 0.26 to 7.35 mg/L in the storm events. It was found that the concentration of pollutants was lower than expected in the initial flush period. Instead, the event mean concentrations of TN and TP were 9.3 and 2.1 times higher than in the wet seasons, showing high nutrient concentration levels throughout the entire rainfall period. To manage storm runoff effectively, a flow-processes-division method was proposed to analyze the inflow condition and pollutant removal rate in different runoff periods. The peak flow interception strategy was recommended as the optimal stormwater management plan, as it showed the highest inflow conditions and 50% pollutant removal rate. Considering the need to reduce the constant flush of stormwater runoff, it is essential to establish a healthy water cycle system to alleviate NPSP and raise the Erhai water level. The storm runoff management method can serve as a practical tool for lake areas that do not exhibit initial flush characteristics.

Dependence of evolution of Cyanobacteria superiority on temperature and nutrient use efficiency in a meso-eutrophic plateau lake.

Algal blooms in lakes have been a challenging environmental issue globally under the dual influence of human activity and climate change. Considerable progress has been made in the study of phytoplankton dynamics in lakes; The long-term in situ evolution of dominant bloom-forming cyanobacteria in meso-eutrophic plateau lakes, however, lacks systematic research. Here, the monthly parameters from 12 sampling sites during the period of 1997-2022 were utilized to investigate the underlying mechanisms driving the superiority of bloom-forming cyanobacteria in Erhai, a representative meso-eutrophic plateau lake. The findings indicate that global warming will intensify the risk of cynaobacteria blooms, prolong Microcystis blooms in autumn to winter or even into the following year, and increase the superiority of filamentous Planktothrix and Cylindrospermum in summer and autumn. High RUETN (1.52 Biomass/TN, 0.95-3.04 times higher than other species) under N limitation (TN < 0.5 mg/L, TN/TP < 22.6) in the meso-eutrophic Lake Erhai facilitates the superiority of Dolichospermum. High RUETP (43.8 Biomass/TP, 2.1-10.2 times higher than others) in TP of 0.03-0.05 mg/L promotes the superiority of Planktothrix and Cylindrospermum. We provided a novel insight into the formation of Planktothrix and Cylindrospermum superiority in meso-eutrophic plateau lake with low TP (0.005-0.07 mg/L), which is mainly influenced by warming, high RUETP and their vertical migration characteristics. Therefore, we posit that although the obvious improvement of lake water quality is not directly proportional to the control efficacy of cyanobacterial blooms, the evolutionary shift in cyanobacteria population structure from Microcystis, which thrives under high nitrogen and phosphorus conditions, to filamentous cyanobacteria adapted to low nitrogen and phosphorus levels may serve as a significant indicator of water quality amelioration. Therefore, we suggest that the risk of filamentous cyanobacteria blooms in the meso-eutrophic plateau lake should be given attention, particularly in light of improving water quality and global warming, to ensure drinking water safety.

Imposex effects on the veined rapa whelk (Rapana venosa) in Bohai Bay, China.

Environmentally relevant concentrations of organotin compounds (OTs) may trigger sex changes in marine invertebrates and pose a threat to the marine ecosystem. In this study, we investigated organotin levels and the biological responses of wild veined rapa whelk (Rapana venosa) from Lüjuhe district (LJH), Dashentang district (DST), and Nanpaihe district (NPH) in Bohai Bay, China. We found that 11.11 and 22.95 % of the veined rapa whelks from DST and NPH exhibited imposex characteristics with a relative penis size index (RPSI) of 12.50 and 12.31, respectively. The RNA/DNA ratio was significantly lower in females from DST than those from LJH (p < 0.05), and a slight increase in DNA damage was observed in females and imposex individuals compared to males. Moreover, less genetic distance occurred between LJH and NPH (0.016) than between LJH and DST (0.028), although they belonged to the same regional population. OTs analysis showed that triphenyltin chloride concentrations (41.45 ng/g dried weight) were significantly higher than tributyltin concentrations (9.51 ng/g dried weight) in tissues (p < 0.05), but no significant differences were observed in sediments (p > 0.05). In conclusion, the occurrence of imposex individuals and biological responses of the wild veined rapa whelk from Bohai Bay suggest that the marine ecosystem might be at risk.

Role of gas vesicles and intra-colony spaces during the process of algal bloom formation.

Aggregation morphology, vertical distribution, and algal density were analyzed during the algal cell floating process in three environments. The role of gas vesicles and intra-colony spaces was distinguished by algal blooms treated with ultrasonic waves and high pressure. Results demonstrated that the two buoyancy providers jointly provide buoyancy for floating algal cells. The results were also confirmed by force analysis. In the simulation experiment, the buoyancy acting on algal cells was greater than its gravity at sample ports 2 and 3 of a columnar-cultivated cell vessel, and intra-colony spaces were not detected. In Taihu Lake, gas vesicle buoyancy was notably less than total algal cell gravity. Buoyancy provided by intra-colony spaces exceeded total algal cell gravity at the water surface, but not at other water depths. In the Daning River, total buoyancies provided by the two buoyancy providers were less than total algal cell gravity at different water depths.