Control Of Organic Pollutants Research Articles

The Application of the Principle of Common but Differentiated Responsibilities in Environmental Governance on the High Seas

Abstract As an important principle of international environmental law, the principle of common but differentiated responsibilities (the CBDR principle) is being applied to various international environment protection regimes including environmental governance on the high seas as an important guiding principle in the law of the sea. This may be beneficial for engaging the international community to protect the high seas in solidarity. However, the application of the CBDR principle encounters difficulties, which include obstacles regarding cross-sector application, different understandings of the CBDR principle and difficulties in implementation of international instruments. This article argues that the differentiation should not depend exclusively on the traditional dichotomy of developing and developed countries but must be determined on a fluid and case-by-case basis. This suggests that the details of the differentiated responsibilities should also be context-specific rather than uniform for all States. Moreover, the implementation of the CBDR principle to address environmental problems on the high seas should be based on substantive fairness. Finally, this article makes several observations. First, the demands of developing countries in the field of maritime emission reduction should be considered. Second, obligation of capacity building and the transfer of marine technology prescribed in the BBNJ Agreement should be encouraged and implemented. Third, strengthening international cooperation in plastic pollution control on the high seas is expected. Fourth, the international community should provide developing countries with the financial support and technical assistance in persistent organic pollutants control. All of these may contribute to the protection of the high seas environment and the future realization of the sustainable development of the oceans.

Spatial–temporal distribution characteristics and traceability analysis of organic matter in Shahe Reservoir (Beijing, China)

Shahe Reservoir is a key node in the upstream of the North Canal, and the water quality has gradually improved after the implementation of low water operation in 2018. The organic matter(OM) in the sediment decreased from 16.66 to 14.22%.In this study, the FI index and parallel factor method were used to investigate the traceability of OM and dissolved organic matter (DOM) in the Shahe Reservoir before and during low water level operation(LWLO), and the results showed that the terrestrial source fraction of OM in sediments was mainly related to organic-rich terrestrial plant residues carried by tributaries and overflows/outfalls during the rainy season, and the FI index indicated that the organic matter (OM) in the Shahe Reservoir before and during LWLO in each DOM in the area is derived from authigenic sources of autotrophic microorganisms, algae, etc. The parallel factor method shows that more than most of the pollutants in the DOM are input from endogenous sources and a small proportion of pollutants are input from exogenous sources. Nutrients in both sediment and interstitial water increased during the LWLO, with TN and TP levels increasing by 262.38 and 204.45 mg·kg−1 in sediment, NH4+–N, PO43−−P, TN and TP in interstitial water increasing by 0.98, 1.36, 2.07 and 4.33 mg·L−1, respectively. Pearson correlation analysis and principal component analysis showed that OM was significantly correlated with nutrients: OM and TN (p < 0.01) and OM and TP (p < 0.05) in the pre-LWLO; OM and TN and TP (p < 0.01) in the LWLO.The results suggested that organic matter pollution control should be mainly carried out from the perspective of endogenous input, focusing on controlling the release of nutrients in sediments.

Application of Biochar for Organic Pollution Control and Energy Storage

Against the backdrop of a growing global climate problem, Against the background of a growing global climate problem, the research on biochar resource utilization is of great importance and urgency. This paper investigates the physical and chemical properties of biochar and its preparation method, and analyzes its principle, application and development prospect in organic pollution control and energy storage. Biochar, due to its large specific surface area and high specific electric capacity, has higher capacitance and charging/discharging stability and lower production cost as graphite electrodes for graphite batteries compared to traditional materials. Biochar is ideally utilized in the field of energy storage. The research and application of biochar is not only helpful for the utilization and transformation of traditional fossil fuel to renewable and clean energy, but also an ideal development area for the rational improvement of soil pollution and the rational disposal of bio-organic wastes.

Removal ibuprofen from aqueous solution by a noval Al-modified biochar.

With the increase of organic emissions in production and human life, the pollution control of organic is now an urgent problem in the environmental field. In this study, hydrothermal carbonization rice husk-loaded Al-modified biochar (Al-BC) was synthesized, and the results of scanning electron microscopy could be used to determine that Al oxide composite was loaded on the surface of the material. The specific surface area was 57.049 m2g-1, pore volume was 0.254 cm3g-1, and average pore diameter was 8.922nm for BC and 109.617 m2g-1, 0.215 cm3g-1, and 3.969nm for Al-BC, respectively. The control effects of these two adsorption materials on organic pollutant ibuprofen (IBU) under different pH conditions were also investigated. The research results show that the adsorption capacity of Al-BC (30.24-1.48mgg-1) is better than BC (19.98-0.92mgg-1) at pH from 2 to 11. Solution pH plays a crucial role in IBU adsorption from organic solution. The Langmuir fitting results show that at pH = 7, the saturated adsorption capacity of IBU on BC could reach up to 18.68mgg-1; the adsorption capacity on Al-BC was 60.49mgg-1. The thermodynamic parameters indicate that the adsorption is spontaneous, endothermic, and increased disorder. The adsorption material prepared in this study could provide a reference for organic pollution control in water.

Microextraction of electric fields and analytes by Janus hydrophobic/hydrophilic microfiber filter: Application in Raman detection of persistent organic pollutants in complex liquid environments

As one of the most pressing environmental issues, the prevention and control of persistent organic pollutants (POPs) continue to garner the attention of various fields. However, there is a lack of effective detection methods for trace amounts of POPs in sewage with a complex composition. To address this, a new Janus microextraction surface-enhanced Raman spectroscopy (SERS) strategy was explored in this study. By designing a Janus glass microfiber filter (GF) membrane structure with a superhydrophobic screening surface and a ZIF-8/Ag/GF detection surface, we demonstrated that POPs molecules in mixed sewage can be sensitively detected and specifically adsorbed and enriched. Thus, a concentration of p-aminothiophenol solution as low as 10−12 M was successfully detected with an enhancement factor as high as 5.16 × 109. Additionally, the collected Raman signal remained unimpeded by impurities such as dye molecules or sediment particles in sewage. Most importantly, the Janus GF substrate enabled the separation and detection of other POPs molecules such as PCB-77, perylene, and pyrene, indicating the immense potential of the Janus SERS strategy in the field of POPs detection.

Land use regulates the spectroscopic properties and sources of dissolved organic matter in the inflowing rivers of a large plateau lake in southwestern China: implication for organic pollution control.

Dissolved organic matter (DOM) transported by inflowing rivers can considerably contribute to the organic loadings of lakes. The current study characterized the DOM properties and source apportionment in the inflowing rivers of Dianchi Lake, the sixth largest freshwater lake in China suffering from organic pollution, during the rainy season by using spectroscopic and carbon stable isotope techniques, and the regulation role of land use was assessed. The results showed that land use (urbanized, agricultural, or mixed) largely affected DOM properties. Greater concentrations and fluorescence intensities of DOM with low aromaticity and dominant autochthonous sources were observed in the urban rivers than in the agricultural rivers. The proportion of humic-like substances increased, while that of tryptophan-like matter decreased from upstream to downstream of two main urban rivers. DOM in the agricultural rivers was characterized by more amounts of aromatic humic-like substances with dominant allochthonous sources compared to that in the urban rivers. Stable isotope analysis showed that the decomposition of macrophytes and input of terrestrial sources from C3 plant-dominated soil and sewage were the major DOM origins in the rivers. The positive linear relationship between the chemical oxygen demand (COD) concentration and fluorescence intensities of terrigenous DOM components implied the necessity of controlling exogenous inputs to alleviate organic pollution in the Dianchi Lake.

Evaluating the pre-treatment protocol required to produce an effective carbonized waste adsorbent for organic pollution control

With the goal of fostering the circular economy, the present work was devised to minimize and manage agricultural waste by transforming it into biochar; a versatile dye removal adsorbent. Waterways across the globe are frequently fouled and contaminated with organic materials, especially via unregulated industrial effluents, producing toxic water supplies. Rhodamine B (RhB) and Methylene blue (MB) dyes were used as model organic pollutants in water. The contaminants were then readily extracted from environmental samples using sustainable wheat straw derived biochars. These materials were utilized in an effort to link the circular economy directly to environmental protection, reducing organic contamination by using a low carbon solution. Herein, two methods were adopted to refine a low temperature carbonized material, dependent on initial pre-treatment; leaching followed by milling (method-I) and milling followed by leaching (method-II). Scanning Electron Microscopy (SEM), nitrogen physisorption, proximate and ultimate analysis and Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR) were used to examine the properties of the synthesized materials. It was found that by altering the process of initial waste pre-treatment, an increase in available surface area (6.284 m2g−1–20.754 m2g−1) and pore structure can be found post feedstock pyrolysis. Additionally, FTIR of the biochar post extraction supported the adsorption process of both dyes, demonstrating a change in dye-adsorbent bonding, depending on the initial waste pre-treatment for the biochar. In batch mode, several operating parameters including pH, concentration, duration, and dose were optimized. Kinetics and adsorption isotherm studies for biochar synthesized by method-II pre-treatment (BC-II) revealed that the system follows Pseudo-first-order kinetics and Freundlich adsorption isotherm model with the relative R2 of 0.9989 and 0.9880 for RhB, comparing with 0.9933 and 0.9932 for MB. The optimal produced biochar, BC-II effectively removed 91.06% of RhB from solution at pH 4 and 92.43% for MB at pH 8. This study brings forth a solution to enhance waste management by creating a circular scenario and alleviate environmental contamination by utilizing wheat straw as a biochar adsorbent, produced under controlled and low temperature conditions.

Sorption of organic contaminants by biochars with multiple porous structures: Experiments and molecular dynamics simulations mediated by three-dimensional models

Interactions between organic pollutants and carbon-based particles are critical for understanding and predicting the fate of organic contaminants in the environment. However, traditional modeling concepts did not consider three-dimensional (3-D) structures of carbon-based materials. This prevents a deep understanding of the sequestration of organic pollutants. Therefore, this study revealed interactions between organics and biochars by combining experimental measurements and molecular dynamics simulations. Biochars displayed the best and worst sorption performances for naphthalene (NAP) and benzoic acid (BA), respectively, among the five adsorbates. The kinetic model fitting suggested that biochar pores played a vital role during sorption and led to the fast and slow sorption of organics on the biochar surface and in pores, respectively. Active sites on the biochar surface predominantly sorbed organics. Organics were only sorbed in pores when the surface’s active sites were fully occupied. These results can guide the development of efficient organic pollution control strategies to protect human health and improve ecological security.

Fate of Naturally Dissolved Organic Matter and Synthetic Organic Compounds Subjected to Drinking Water Treatment Using Membrane, Activated Carbon, and UV/H2O2 Technologies.

Organic pollutants are toxic and are present in drinking water. The conventional processes of most water plants can basically meet the discharge standard. However, based on the improvement of the objective of organic pollutants control and the constant change of water characteristics, the results may not be ideal. This study evaluates the effectiveness of different treatments such as microfiltration, nanofiltration, reverse osmosis, activated carbon, and ultraviolet irradiation/H2O2 in terms of the removal of organic pollutants. Among the DOM results, nanofiltration, reverse osmosis, and activated carbon showed optimal performance due to the characteristics of processes and the compound properties. However, the risks of low-molecular-weight organic residue and byproduct formation are still present. Thirty-nine species of synthetic organic compounds (SOC) were qualitatively and semiquantitatively analyzed. Different technologies showed varying removal capabilities for SOC based on their properties and many substances coexisted leading to abnormal removal performances. These residual organics showed the characteristics of lower molecular weight, more hydrophilicity, further unknown impacts, and with risk of DBPs. Based on the above insights, possible methods can be rationally chosen for on-demand decontamination of organics in unconfined aquatic environment and long-time impact on water characteristics and human health also should be considered.

Dynamics of the water environment in a water quantity-quality-soil model of China's Yellow River basin: imbalance and driving factors.

Dynamic assessment of the water environment reflects variations in water resources in a basin under the combined influence of nature and humans and is a prerequisite for rational water management. This study provides an integrated assessment of the water environment in a water quantity-quality-soil model. Using the long-term monthly data from hydrological monitoring stations, the water environment of the Yellow River basin is assessed from the year 2006 to 2019. The kernel density estimation and the Dagum Gini coefficient are used to analyze the spatial and temporal imbalances of the water environment. Geographic detectors are used to extract external driving factors of the unbalanced evolution. The study results reveal that (1) the water environment in the basin shows a fluctuating downward trend, which mainly depends on the organic pollution control indicators, with a contribution of 22.85%. Scores of the water environment in the midstream are lower than those in the upstream and downstream due to the heavy pollutant discharges. (2) The spatial imbalance shows a fluctuating downward trend. Inter-regional variation is the primary source of regional variation in the water environment, with an average contribution of 56.02%. (3) The temporal imbalance of the water environment is on the rise, with a degree of multipolarity. The significant left trailing feature of the kernel density curve suggests that there are areas within the basin where the water environment is extremely poor. (4) For the overall basin and upstream, economic development and technological innovation are the main external driving factors influencing the spatial and temporal imbalances of the water environment. For the midstream and downstream, population density and environmental regulations are the main drivers. The interaction of any two factors has a greater impact than the single one.

Pyridine-linked covalent triazine frameworks with bidirectional electron donor-acceptor for efficient organic pollution removal.

Simultaneous regulation of adsorption and photocatalytic performance of covalent triazine frameworks (CTFs) to achieve efficient control of organic pollution in water is a promising strategy, but remains a formidable challenge. Herein, pyridine linkers were innovatively introduced into pristine CTF (p-CTF) and the bidirectional electron donor-acceptor (EDA) system of contaminant-to-pyridine and pyridine-to-triazine was constructed inside. Experimental results combined with theoretical calculations revealed that pyridine units with π-deficient properties performed as electron acceptors and electron donors in the adsorption and photocatalytic processes, respectively. This special structure provided a directional pathway for electron transfer, which endowed CTFs with excellent adsorption and photocatalytic properties. Compared to p-CTF, pyridine-linked CTF (M-CTF) showed a 16-fold increase in adsorption capacity for naphthalene (973.4 μmol·g-1). Benefiting from the optimized light absorption and electron transfer form (n → π*transition), M-CTF exhibited high regeneration efficiency after adsorption of both bisphenol A (94% after 4 cycles) and naphthalene (95% after 4 cycles). Besides, the removal performance of organic micropollutants from natural water showed a great advantage thanks to the bidirectional EDA system. Overall, the present study provides new insights into the optimization of electronic structures for carbon-based environmental functional materials applied to organic pollution control in water.

Influence of Microbial Treatment on the Preparation of Porous Biochar with Stepped-Up Performance and Its Application in Organic Pollutants Control.

In this study, Irisensata Thunb grass (ITG) was used as a biomass carbon resource to prepare biochars for the first time. After microbial treatment, the obtained microbial-treated ITG (MITG) was activated by using a mixed base as an activator for preparation of biochar (MITGB). The specific surface area and total pore volume of MITGB were 3036.4 m2/g and 1.5252 cm3/g, which were higher than those of biochar prepared without microbial treatment (ITGB, 2930.0 m2/g and 1.5062 cm3/g). Besides, the physicochemical properties of MITGB and ITGB were also quite different including micro morphology, surface chemistry, functional groups, etc. In the experiment of removing organic pollutants with synthetic dye RhB and antibiotic TH as the models, MITGB showed excellent treatment ability. The maximum adsorption capacities of MITGB for RhB and TH were 1354.2 and 1462.6 mg/g, which were higher than most of the biochars. In addition, after five cycles of recycling, the adsorption capacities of the organic pollutant models can still be maintained at more than 80%, which showed high stability. This work verified the feasibility of microbial treatment to further improve the performance of biochar and provided a new idea and direction for exploring other biochars.

One-Step Carbonization Synthesis of Magnetic Biochar with 3D Network Structure and Its Application in Organic Pollutant Control.

In this study, a magnetic biochar with a unique 3D network structure was synthesized by using a simple and controllable method. In brief, the microbial filamentous fungus Trichoderma reesei was used as a template, and Fe3+ was added to the culture process, which resulted in uniform recombination through the bio-assembly property of fungal hyphae. Finally, magnetic biochar (BMFH/Fe3O4) was synthesized by controlling different heating conditions in a high temperature process. The adsorption and Fenton-like catalytic performance of BMFH/Fe3O4 were investigated by using the synthetic dye malachite green (MG) and the antibiotic tetracycline hydrochloride (TH) as organic pollutant models. The results showed that the adsorption capacity of BMFH/Fe3O4 for MG and TH was 158.2 and 171.26 mg/g, respectively, which was higher than that of most biochar adsorbents, and the Fenton-like catalytic degradation effect of organic pollutants was also better than that of most catalysts. This study provides a magnetic biochar with excellent performance, but more importantly, the method used can be effective in further improving the performance of biochar for better control of organic pollutants.

O3-assisted low-temperature preparation of marginal S and graphitic N co-doped graphene oxide as high-performance electrocatalyst for bisphenol A degradation

In this research, a novel insight was provided for oriented low-temperature S and N doping into graphene oxide (GO).Given the gradual concern in the high-temperature dependence of traditional annealing method for the oriented design of heteroatom doping, utilizing O3 etching-assisted heteroatom doping can simultaneously resolve the problems of energy consumption and doping species design. In this research, with O3 etching, 100 at.% marginal S (C-SOX-C) and 92 at.% graphitic N co-doped O3-S/NGO were successfully synthesized at annealing temperature of 200 °C. Characterization results showed that S and N doping via O3 etching maintained the sheet-like structure of GO without much stacking (layer thickness of 4–5 nm). In addition, active defects were formed by O3 etching and S/N atom doping to provide active center for catalytic reaction. The electrocatalytic degradation behavior proved that 100 % bisphenol A degradation efficiency could be achieved by O3-S/NGO within 30 min and that the main active species generated during the reaction were O2•−, 1O2 and active chlorine. The possible pathways of bisphenol A degradation were also determined to complete the discussion. This project was based on the environmental demand of organic pollution control and suggested an optimal preparation strategy for high-performance catalyst preparation and utilization.

Metal-Catalyzed Formation of Organic Pollutants Intermediated by Organic Free Radicals.

Metal compounds play important roles in the formation of organic pollutants during thermal-related processes. However, the metal-catalyzed predominant organic pollutants have not previously been characterized nor have any detailed catalytic mechanisms been clarified. Here, we preciously distinguished the multiple organic free radical intermediates on metal catalyst surfaces during the organic pollutant formation through laboratory and theoretical studies. Differences between the organic free radical intermediate species, concentrations, and formation mechanisms under the catalysis of different metal compounds were investigated. The results were verified mutually with the differed characteristics of organic pollutant products. CuO predominantly catalyzed the formation of highly chlorinated phenoxy radical intermediates and dioxins. High proportions of semiquinone radicals and oxygen-containing derivatives were found on ZnO surfaces. Differently, methyl-substituted phenoxy radicals and long-chain products formed on Al2O3 surfaces. The results will be instructive for the target emission control of priority organic pollutants during thermal-related processes rich in different metal compounds.

Two-step pyrolysis to anchor ultrahigh-density single-atom FeN5 sites on carbon nitride for efficient Fenton-like catalysis near 0 °C

Low temperatures approaching 0 °C will slash the efficiency of Fenton-like catalysis for organic pollution control. Herein, a two-step pyrolysis strategy is developed to fabricate the carbon nitride nanosheet-supported single-atom Fe catalyst with ultrahigh Fe loading amount of 16.64 wt%. The secondary pyrolysis generates surface vacancies to convert Fe coordination structure from FeN3 to FeN5, which exhibits ultralow activation energy of 6.54 kJ mol−1 in peroxymonosulfate activation for sulfamethoxazole degradation via a new ‘surface contact oxidation’ path. The catalyst-dose-normalized kinetic rate constant on FeN5 site reaches 21.38 L min−1 g−1 at 2 °C, even exceeding that on FeN3 site and reported values by 0.61–70.27 time(s) at 25–30 °C. Density-functional-theory calculations reveal that additional N ligands (L) make less charges transfer from Fe toward -SO4 in critical [FeL-SO4] intermediates, enabling their thermodynamically favorable electron seizure from pollutants, and cause easier -SO4H desorption for rapid site regeneration, contributing to excellent low-temperature resistance.

Insights into toxicity of polychlorinated naphthalenes to multiple human endocrine receptors: Mechanism and health risk analysis.

This study explored the combined disruption mechanism of polychlorinated naphthalenes (PCNs) on the three key receptors (estrogen receptor, thyroid receptor, and adrenoceptor) of the human endocrine system. The intensity of PCN endocrine disruption on these receptors was first determined using a molecular docking method. A comprehensive index of PCN endocrine disruption to human was quantified by analytic hierarchy process and fuzzy analysis. The mode of action between PCNs and the receptors was further identified to screen the molecular characteristics influencing PCN endocrine disruption through molecular docking and fractional factorial design. Quantitative structure-activity relationship (QSAR) models were established to investigate the toxic mechanism due to PCN endocrine disruption. The results showed that the lowest occupied orbital energy (ELUMO) was the most important factor contributing to the toxicity of PCNs on the endocrine receptors, followed by the orbital energy difference (ΔE) and positive Millikan charge (q+). Furthermore, the strategies were formulated through adjusting the nutritious diet to reduce health risk for the workers in PCN contaminated sites and the effectiveness and feasibility were assessed by molecular dynamic simulation. The simulation results indicated that the human health risk caused by PCN endocrine disruption could be effectively decreased by nutritional supplementation. The binding ability between PCNs and endocrine receptors significantly declined (up to -16.45%) with the supplementation of vitamins (A, B2, B12, C, and E) and carotene. This study provided the new insights to reveal the toxic mechanism of PCNs on human endocrine systems and the recommendations on nutritional supplements for health risk reduction. The methodology and findings could serve as valuable references for screening of potential endocrine disruptors and developing appropriate strategies for PCN or other persistent organic pollution control and health risk management.

Degradation mechanism of tetracycline using sulfidated nanoscale zerovalent iron driven peroxymonosulfate and metabolomic insights into environmental risk of intermediates products

• S-nZVI driven PMS exhibited an excellent performance to eliminate tetracycline. • Both SO 4 •− and •OH as dominant species were committed to degrading tetracycline. • Ten degradation intermediates were screened and determined by HRMS analysis. • Further intermediates products induced upmetabolism of carbohydrate, citrate cycle. • SO 4 •− based incomplete mineralization decreased the toxicity of tetracycline. Sulfide-modified nanoscale zerovalent iron (S-nZVI) has aroused increasing interest due to its excellent ability towards environmental decontamination. Heterogeneous catalytic degradation of tetracycline hydrochloride (TC-H) mediated by iron-based materials has been explored by previous researches. Yet, unknown role and degradation mechanism of tetracycline hydrochloride (TC-H) through S-nZVI driven peroxymonosulfate (PMS) need to be further investigated. In current research, the impacts of S-nZVI dosage, PMS dosage, initial pH, anions and humic acids were independently explored during TC-H degradation process. S-nZVI exhibited the high efficiency for activating PMS. TC-H degradation followed a pseudo-first order kinetics reaction with k obs at 0.1403 min −1 . HA, Cl − , HPO 4 2− , NO 3 − exhibited varied reduction of the reaction rates on TC-H removal. Besides, SO 4 •− and •OH were dedicated to degrading TC-H, and SO 4 •− was proved to be predominant one. The alteration of sulfide species from XPS analysis played a pivotal role in raising the electron transfer rate to improve TC-H degradation. Ten intermediates products were determined through HRMS and primary transformation mechanism involved in N-demethylation reaction, demethylation reaction, elimination reaction and hydrogenation reaction were proposed. Based on metabolomics analysis, up-regulated expression of carbohydrate metabolism, citrate cycle, CoA biosynthesis, fatty acid degradation and amino acid synthesis in Escherichia coli were significantly induced by the further products, whereas glutathione metabolism was significantly down-regulated, endorsing that potential toxicity induced by intermediates were weakened. To sum up, S-nZVI/PMS as a promising nano-water environmental remediation method could be feasible for emerging environment organic pollutants control.

Component structure and characteristic analysis of cyanobacterial organic matters.

The characteristic analysis of cyanobacterial organic matters is an important premise of cyanobacterial organic pollution control. This paper investigated the component structure characteristics of algal organic matters (AOM) secreted and released by cyanobacteria in laboratory culture and actual Taihu Lake environment by spectroscopic quantitative and qualitative methods. Results showed that the secretion amount of AOM was mainly 4-6 μg COD/106 cells during the growth period of Microcystis aeruginosa, and the content ratio of extracellular organic matters (EOM) to intracellular organic matters (IOM) gradually increased from 0.83 in adaptation and logarithmic period to 3.33 in stable and decay period. The secretion of IOM showed a decrease trend, which indicated the decrease of its synthesis or the gradual infiltration and loss caused by cell membrane damage. From the component characteristics, the EOM had lower SUVA value and higher proportion of small molecular substances with molecular weight <3 kDa, indicating its more difficult to separate from water than IOM. Compared with the laboratory culture environment, the actual Taihu Lake resulted in more obvious characteristic heterogeneity of cyanobacteria EOM and IOM.

Distribution characteristics of phytoplankton functional groups and their relationship with environmental factors in Taihu Basin

太湖流域地处长江下游，水系发达，是典型的平原水网地区，为明确空间和环境因子对太湖流域浮游植物功能类群分布的影响，本研究于2019年8—9月期间比较太湖流域包括河流、湖泊和水库的85个采样点的浮游植物、空间和环境特征. 首次利用“人工智能图像识别技术”，并结合传统人工镜检，共鉴定浮游植物250个分类单位，隶属于9门13纲28目57科110属，以绿藻门(45.6%)、硅藻门(19.2%)和蓝藻门(16.4%)为主. 共划分功能类群31个，包括M、D、J、S1、C、Y、F、P、MP、H1、SN、W1、G、K和TB共15个优势功能类群. 结果表明：1)太湖流域不同水体功能类群组成差异显著，差异主要来自M、J、S1、Y、P、H1类群；2)浮游植物功能类群分布具有一定的空间异质性，以太湖为中心向外形成3个聚类组，物种组成类型依次为蓝藻型、蓝藻-绿藻-硅藻型、绿藻-硅藻-蓝藻型，主要贡献类群依次为M、S1类群，M、S1、P、J类群，P、S1、J、D、C类群；3)在太湖流域，相对于环境因子而言，空间因子对浮游植物功能类群组成的影响更大. RDA分析表明，COD_Mn、NO₃^--N、TN、SD、pH值和DO与太湖流域浮游植物优势功能类群呈显著相关. 过去十年，以控源截污为主导的环境管理政策已在太湖流域取得显著成效，但是对于以M、S1类群水华为特征的夏季太湖流域而言，蓝藻水华防控仍是必须面对的难题，有机污染物和氮的控制仍是关注重点，不同水体类型和浮游植物功能类群因地制宜的管控模式仍是关键.;The study area locates in the Taihu Basin, and it spans across three provinces (Jiangsu, Zhejiang, Anhui) and the Shanghai Administrative Region. We sampled at 85 sites during Aug. and Sep. 2019, including lakes, rivers, streams and reservoirs, to investigate the effects of spatial and environmental factors on the distribution characteristics of phytoplankton functional groups (PFG) in Taihu Basin. A total of 250 phytoplankton taxa, belonging to 9 phyla, 13 classes, 28 orders, 57 families and 110 genera, were identified by the artificial intelligence image recognition technology for the first time, combined with traditional microscopy. The phytoplankton species composition was dominated by Chlorophyta (45.6%), followed by Bacillariophyta (19.2%) and Cyanophyta (16.4%). According to the PFG classification method, 31 functional groups were identified, respectively, with dominant function groups including M, S1, C, D, Y, G, MP, P, J, SN, F, TB, K, H1 and W1. The results showed that: 1) There were significant differences in the PFG composition among different water bodies in Taihu Basin, mainly from M, J, S1, Y, P and H1 groups; 2) The PFG distribution in Taihu Basin showed certain spatial heterogeneous, and three cluster groups were found. Moreover, the corresponding species composition types are Cyanophyta, Cyanophyta-Chlorophyta-Bacillariophyta and Chlorophyta-Bacillariophyta-Cyanophyta. The dominant groups are M and S1 groups, M, S1, P, j groups, P, S1, J, D and C groups, respectively; 3) Spatial factor plays a major role in the formation of phytoplankton community than environmental factor in Taihu Basin. Redundant analysis showed that COD_Mn, NO₃^--N, TN, SD, pH and DO were the main environmental factors affecting the PFG distribution. Over the past decade, the environmental management policy led by source pollution control has achieved remarkable results in the Taihu Basin; however, more effective prevention and control methods are expected to propose for controlling cyanobacterial blooms in the future, and the control of organic pollutants and nitrogen should be paid more attention for aquatic ecological management in Taihu Basin during summer. More importantly, appropriate aquatic ecological management mode should be adopted to deal with different water types and different PFGs.