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Background: While a dam is constructed to adjust and store water resources, it has negative impacts on biodiversity of the corresponding ecosystems. In particular, the dam regulation induces water-level fluctuations (WLFs), resulting in remarkable effects on the riparian vegetation succession of the drawdown zone ecosystem. These riparian plant responses play important roles in the biodiversity conservation. However, in-depth investigative adequate studies are still lacking. The objective of this study was to assess the community assembly under the anti-seasonal WLFs of China's Three Gorges Reservoir (TGR). To analyze the WLFs' impacts on plant community, the drawdown zone of the TGR was divided into four sub-zones (zone I, II, III, and IV) according to the inundation periods. The community biomass, height, total coverage, and species diversity in each sub-zone were surveyed. To detect the response of individual plant to the WLFs, dominant plants of Echinochloa crusgalli, Setaria viridis, Bidens pilosa, and Xanthium sibiricum were selected as targeted species to compare the plant's morphological and physiological traits between non-flooded area and the moderately inundated area. Results: The peaks of community biomass (1859.62 ± 663.77 g), total coverage (103.93 ± 11.81%), and diversity indexes were found in zone II that experienced 90 days of inundation. Community height and total coverage were both significantly negatively correlated to the inundated gradients. Generalized linear models and quadratic regression analyses revealed that community biomass, height, and total coverage were strongly related to the inundated gradients, implying that the inundation is the major factor contributing to the variation of the riparian vegetation patterns. The values of morphological traits (plant height and biomass) in the zone II were higher than those in the non-flooded zone, and were significantly positively correlated with physiological traits. Conclusions: Community structure, diversity, and functional traits analysis indicated that the drawdown zone referencing to the 90-day inundation was suitable for the plant community establishment. Results on plant functional traits suggest the adaption of riparian plants to the TGR hydrological regime. However, further investigative studies with more plant species are necessary to elucidate their adaptation mechanisms. [ABSTRACT FROM AUTHOR]

The application of plastic mulch films brings convenience to agricultural production, but also causes plastic waste that can be degraded into microplastics (MPs). However, little is known about the fate of plastic waste in agricultural ecosystem under freeze-thaw alternation in middle and high latitudes, as well as in highlands around the world. Whether the release of plasticizers, i.e. phthalate esters (PAEs), under such conditions would pose a potential risk to exposed organisms due to bioaccumulation is also unknown. To fill these data gaps, the agricultural fields in Liaoning of China with typical freeze-thaw alternation was selected as the study area. The transformation of plastic film was demonstrated by simulation freeze-thaw alternating from −30 to 20 ℃. Soil samples were collected to investigate the patterns of MP composition, abundance, and distribution. Concurrently, the concentrations of two PAEs including bis(2-ethylhexyl) phthalate (DEHP) and diethyl phthalate (DEP) in soils were analyzed to provide information on the correlation between MPs abundance and PAEs concentrations as well as potential risks. The results showed that freeze-thaw alternating can accelerate the formation of MPs and release of PAEs from plastic waste. The abundance of MPs was positively correlated with the concentration of PAEs. Soil PAEs ranged from 3268 ± 213–6351 ± 110 μg/kg, indicating that over 40 % of the PAEs were transferred from plastic films to soils. Such residual amounts could pose risk for exposed organisms. Hence, the current study suggested that special concerns should be given to the release plasticizers in plastic waste of agricultural soils. [Display omitted] • -30/20 ℃ freeze-thaw alternations accelerate plasticizers release from mulch. • MPs abundance was positively correlated with concentration of phthalate derivatives (DEP and DEHP) in soil. • DEHP as a major plasticizer contributes to the ecological risk. [ABSTRACT FROM AUTHOR]

In order to assess the risk of pesticides to aquatic ecosystems, five single-dose pesticides including chlorpyrifos, pymetrozine, dinotefuran, azoxystrobin, and acetochlor that are frequently used in developing countries, were selected. Based on the principle of conservative risk assessment, application amounts for different dosage forms were recommended, the Top-Rice model and risk quotient method were used to evaluate the aquatic ecological risk of the aforementioned single-dose pesticide products. The results showed that predicted peak environmental concentration ranges after application on rice were 110.52-564.25 μg/L for chlorpyrifos, 20.79-114.6 μg/L for pymetrozine, 21.81-114.02 μg/L for dinotefuran, 16.52-56.94 μg/L for azoxystrobin, and 167.22-2184.01 μg/L for acetochlor in different seasons of Changsha, Hangzhou, Nanning in China, and Lahore and Faisalabad in Pakistan. Under the current conditions of registered administration, the acute and chronic risks posed by chlorpyrifos to fish and invertebrates were deemed alarming, and those by pymetrozine and dinotefuran were considered acceptable. The acute risk of exposure of azoxystrobin to vertebrates such as fish, and invertebrates such as daphnia and shrimp is alarming, whereas the chronic risk to vertebrates, invertebrates, and algae was acceptable. The acute exposure risk posed by acetochlor was deemed worrying, and in the case of chronic exposure, only 36 % of the simulation group exhibited a risk quotient below 1, indicating no risk. These findings imply that the ecological risks of using registered chlorpyrifos and acetochlor products on rice cannot be ignored. It should be noted that the analysis method and model employed in this study were intentionally conservative to ensure a comprehensive assessment of the potential risks associated with the use of registered pesticide products. However, the model failed to consider influential factors like photolysis of pesticides on the soil surface, thereby introducing a certain degree of conservativeness in the evaluation results., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Cyanobacterial blooms are of global concern due to the multiple harmful risks they pose towards aquatic ecosystem and human health. However, information on the fate of organic pollutants mediated by cyanobacterial blooms in eutrophic water remains elusive. In the present study, endocrine disruptive potentials of phytoplankton samples were evaluated throughout a year-long surveillance in a large and eutrophic freshwater lake. Severe cyanobacterial blooms persisted during our sampling campaigns. Estrogenic agonistic, anti-estrogenic, anti-androgenic, and anti-glucocorticogenic effects were observed in the phytoplankton samples using in vitro reporter gene bioassays. 27 endocrine disrupting chemicals (EDCs) of different modes of action were detected in the samples via UPLC-MS/MS system. Results from mass balance analysis indicated that the measured estrogenic activities were greater than the predicted estrogenic potencies from chemical analysis, demonstrating that chemical analysis of targeted EDCs is unable to fully explain the compounds responsible for the observed estrogenicities. Results from Spearman's correlation analysis concluded that the concentrations of ten EDCs in phytoplankton samples were negatively correlated with cyanobacterial biomass, suggesting the potential occurrence of biomass bio-dilution effects of EDCs due to the huge biomass of cyanobacteria during bloom seasons. The present study provided complementary information about the potential endocrine disruptive risks of cyanobacterial blooms, which is important for understanding and regulating EDCs in eutrophic lakes., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Dams have profound impacts on river ecosystems, amongst them inundation of land, altered dynamics of the water body or uprising reservoir backwaters influencing tributary or upstream river sections. Along the outstandingly ecologically important Yangtze River in China, the Three Gorges Reservoir (TGR) is the largest project, covering an area of 1080 km 2 . From the beginning, the dam-project came in for criticism on increasing environmental risks due to sub-merging former industrial and urban areas. We simulated dynamics of biotic and abiotic components of the TGR ecosystem (trophic guilds of aquatic organisms, hydrodynamics, nutrients), as well as the behaviour of the herbicidal substance propanil and its metabolites 3,4-Dichloroaniline (DCA) and 3,3',4,4'-tetrachloroazoxybenzene (TCAB). A modelling environment, provided by the AQUATOX software, was adapted to the specific situation at a tributary reach to the Yangtze river 'Daning River'. As the simulated food web contained several interconnected trophic levels, a significant biomagnification of metabolites was demonstrated by our simulation studies. In particular, newly emerging stagnant downstream sections of tributaries exhibited high probabilities due to accumulating pesticides from upstream sources. The common problem of algal blooms in the TGR-region was addressed by dose-response simulation experiments with essential nutrients. Impacts on structure and abundance of populations of aquatic organisms were shown. However, even high nutrient loads resulted in only slight changes of densities of organisms of all trophic levels. Nevertheless, the probabilities for large-scale algal blooms affecting drinking water quality were considered low because of high flow velocities and discharge rates towards the Yangtze River. We see high potential of simulation-based assessments that provide information for risk managers dealing with whole catchment areas. They are put in the position to differentiate the magnitude of impacts of various factors and decide about the most effective remediation measures., (Copyright © 2018 Elsevier B.V. All rights reserved.)