Microcystis is a well-known toxic cyanobacterium in eutrophic environments, and an increasing number of Microcystis blooms have emerged in salty reservoirs and coastal rivers. This study observed that many Microcystis were identified in a coastal river in June 2020. The relative abundance of Microcystis decreased from 81.2 to 10.2% in the sampling sites from a salinity of 0 (Sal. 0) to a salinity of 12 (Sal. 12). Hepatotoxic microcystins (MCs) were identified in the coastal river and its estuary. Of the samples, those with a salinity of 5 (Sal. 5) had the highest concentration of MCs at 7.81 ± 0.67 μg L⁻¹. In a saline water simulation experiment, the results showed that salt inhibited Microcystis (M.) aeruginosa growth, enhanced the activity levels of superoxide dismutase (SOD) and catalase (CAT) and stimulated microcystin production. Transcription analysis showed that the expression levels of the psaB and rbcL genes controlling photosymbiotic processes were downregulated, and capD and csaBgene-related polysaccharide productions were upregulated by salt incubation. Notably, metabolism analysis showed that the total polysaccharides, proteins and small molecular matter, such as sucrose, methionine and N-acetyl-D-glucosamine, in the Microcystis cells increased substantially to resist the extracellular hyperosmotic pressure caused by the high salinity levels in culture. These findings indicate that increased salt in a natural aquatic body shifts the phytoplankton community by influencing the physiological metabolism of cyanobacteria and poses a high risk of microcystin exposure during cyanobacterial blooms in coastal rivers.

Understanding the impact of the heterogeneity of the ecological environment on biodiversity is a key issue in ecology. Topographical heterogeneity was potentially important in grassland systems to create or change habitats for grasshopper settlement and foraging. Yet, there was little knowledge of how grasshopper communities respond to plant communities along the altitude gradient. We investigated the role of plant communities on grasshopper diversity with geostatistical methods to test the effects of heterogeneity in the natural grassland on the upper reaches of the Heihe River, Qilian Mountains. To aim the goal of the study, nonreturn experiments were used to collect the grasshoppers’ diversity and populations, and the plant’s community was sampled at the same location. The results showed that the semivariograms of grasshopper abundance and plant communities were both nonlinear models, while the grasshopper abundance typically produces heterogeneity with a larger range and nuggets than plant communities (except the plant coverage range in the model, range <1.5 m). The two communities presented the spatial distribution pattern of aggregated distribution, and the spatial trend is more intense in the northeast-southwest direction than in the northwest-southeast. The grasshopper species developed a good selection on microenvironment to habitat and the distribution consistent with plants, forming the horizontal distribution with a flaky and plaque distribution pattern. The relationship between grasshoppers and plants was highly dependent on the altitude, and grasshopper abundance has a positive correlation with plant richness (F = 0.68) and plant coverage (F = 0.32) and has a negative correlation with plant height (F = 0.13). In summary, the spatial distribution and correlation characteristics of plant communities and grasshoppers formed a plaque heterogeneity structure under the altitude gradients.

There are increasing debates on the relationship between economic complexity and environmental degradation. This study deepens our understanding of this nexus in 11 emerging economies given the moderating role of energy consumption while controlling for economic development, trade openness and population growth. The findings from the quantile regression technique reveal that emerging economies are characteristic of low energy consumption, leading to insignificant contributions of economic complexity to environmental degradation across the spectrum as they also have very low-trade openness. Further results show the invalidity of the EKC between energy use (such as fossil fuels) and environmental degradation in emerging economies. Moreover, the Environmental Kuznets Curve (EKC) between economic development and environmental degradation is valid especially for those countries in the low and median quantiles (Egypt, Indonesia, and Vietnam). Also, the EKC hypothesis between population and environmental degradation is valid only for countries in the high and highest quantiles (Korea Republic, Turkey, Mexico and Iran). Finally, the results revealed that trade openness strictly reduces environmental degradation across the spectrum. Policy implications, limitations of the study and direction for future research are discussed.

The sorption processes of persistent organic pollutants on microplastics particles are poorly understood. Therefore, the present study investigated the sorption processes of perfluorooctanesulfonate (PFOS) on polyethylene (PE) microplastic particles (MPs) which are representing a prominent environmental pollutant and one of the most abundant microplastic polymers in the aquatic environment, respectively. The focus was set on the investigation of the impact of the particle size on PFOS sorption using four different PE MPs size ranges. The sorption kinetics for 6 months was studied with one selected size range of PE MPs. Besides, the desorption of PFOS from PE MPs under simulated digestive conditions was carried out by using artificial gut fluid mimicking the intestinal juice of fish. The investigation of the size effects of particles over 6 months demonstrated a linear increase of PFOS concentration sorbed onto PE with a decrease of the particle size. Thus, our findings implicate efficient sorption of PFOS onto PE MPs of different sizes. The results showed that PFOS desorbed from the PE MPs into the artificial gut fluid with a rate of 70 to 80%. Besides, a longer exposure of PE MPs to PFOS leads to a higher concentration adsorbed by PE MPs, which may favor the ingestion of higher concentration of PFOS, and thus represents a higher risk to transfer relevant concentrations of PFOS during digestion.

The degradation of water environment (WE) has constrained the sustainable development of cities, while the rapid urbanization also exacerbates water environment change. However, the complicated relationship between urbanization and WE is far from clearly understood. In this study, a comprehensive index system for urbanization and WE was applied along with the System Index Evaluation Model (SIEM) and a Coupling Coordination Degree Model (CCDM) to analyze the coupling between urbanization and WE in Nanjing, East China, from 1990 to 2018. The comprehensive index of urbanization increased from 0.0392 in 1990 to 0.9890 in 2018, showing a clear increasing trend. Demographic and spatial urbanization made the largest contribution to urbanization development from 1990 to 2010, while economic urbanization became the largest contributor to urbanization development between 2011 and 2018. Under the combined effects of pressure, state, and response subsystems, the comprehensive WE index showed an upward trend with some fluctuations from 1990 to 2018. The degree of coupling coordination between urbanization and WE displayed an overall upward tendency, growing from 0.18 in 1990 to 0.95 in 2018. The coupling coordination state transitioned from a serious imbalance during the low coupling period (1990–1992) into the superior coordination of the highly coupled period (2011–2018). With the continuous urbanization in the future, in addition to ensuring the optimal management of surface water, protection of groundwater should be reinforced. The results advance our understanding of the dynamic relationship between urbanization and WE and provide important implications for urban planning and water resource protection.

Citalopram (CTP) and mirtazapine (MTP) are two typical psychoactive drugs used for the depression treatment. As emerging pollutants, CTP and MTP have raised concern because of their harmful effect on aquatic organisms. Therefore, the ecotoxicological risk of these two pollutants to aquatic organisms should be given more attention. In this study, the effects of CTP and MTP on the feeding rate, heartbeat, nutritional enzymes, and their related gene expression of D. magna were investigated under single and binary mixture pollutant exposure. Subsequently, the recovery of exposed D. magna was studied to assess the toxic persistence of those pollutants. After 24-h exposure, the ingestion rate decreased by 34.2% and 21.5%, in the group of 1.45 mg/L CTP (C-H) and binary mixture with high concentration (Mix-H), respectively. After 24-h recovery, the feeding rate of D. magna was stimulated by a compensatory response. Over the exposure period, the heartbeat rate of D. magna increased significantly in the groups of CTP, MTP, and their binary mixture with low concentration (Mix-L), and then, their heartbeat rate was recovered during the recovery period. The activity of α-amylase (AMS) and trypsin were significantly changed in most of the exposed daphnia, both during the exposure and recovery period. CTP/MTP exposure stimulated the expression of the AMS gene. MTP and Mix-H exposure inhibited the expression of the trypsin gene and the other groups stimulated its expression. After 24-h recovery, the stimulating or inhibitory effects were alleviated. There were different responses between gene expression and enzyme activity. In conclusion, our results highlighted the toxic effects at high concentrations of single and mixed pollution of CTP and MTP on the feeding rate, heartbeat, AMS and trypsin enzyme activity, and expression of related genes of D. magna to assess the environment risk of them.

Climate change and health are inextricably linked, especially the role of ambient temperature. This study aimed to analyze the non-communicable disease (NCD) burden attributable to low temperature globally, regionally, and temporally using data from the Global Burden of Disease (GBD) study 2019. Globally, in 2019, low temperature was responsible for 5.42% DALY and 7.18% death of NCDs, representing the age-standardized disability-adjusted life years (DALY) and death rates (per 100,000 population) of 359.6 (95% uncertainty intervals (UI): 306.09, 416.88) and 21.36 (95% UI:18.26, 24.74). Ischemic heart disease was the first leading cause of DALY and death resulting from low temperature, followed by stroke. However, age-standardized DALY and death rates attributable to low temperature have exhibited wide variability across regions, with the highest in Central Asia and Eastern Europe and the lowest in Caribbean and Western sub-Saharan Africa. During the study period (1990–2019), there has been a significant decrease in the burden of NCDs attributable to low temperature, but progress has been uneven across countries, whereas nations exhibiting high sociodemographic index (SDI) declined more significantly compared with low SDI nations. Notably, three nations, including Uzbekistan, Tajikistan, and Lesotho, had the maximum NCDs burden attributed to low temperature and displayed an upward trend. In conclusion, ambient low temperature contributes to substantial NCD burden with notable geographical variations.

Swine manure treatment plants are important reservoirs of plasmid-harboring antibiotic resistance genes (ARGs) and physicochemical contaminants, but the changes in the abundances of plasmids and ARGs, and their interactions with the physicochemical properties of manure, are still unclear. Thus, in the present study, plasmidome and metagenome analyses were conducted for samples collected at different stages in the swine manure treatment process. The results indicated that anaerobic digestion and aerobic digestion were the most efficient stages for reducing the abundances of ARGs in swine manure. However, the plasmids associated with ARGs were not effectively removed in these stages. Through the whole treatment process, the IncL/M, IncQ1, IncHI2A, IncA/C, and IncN plasmid groups had strong correlations (r > 0.8, P < 0.01) with most ARG types, thereby indicating that these plasmids play important roles in the persistence of ARGs in this environment. Furthermore, the pH, total nitrogen, total phosphorus, and four heavy metals (Cu, Zn, As, and Fe) significantly affected the abundances of seven ARG subtypes (tetB(P), ant(6)-Ia, tet44, aph(3′′)-Ib, mefB, tet(L), and tet(39)). In particular, florfenicol had the most positive correlations with ARGs. Our results indicated that nutrients, heavy metals, and antibiotics all contributed to the presence and persistence of plasmid-harboring ARGs. This study provides insights into the fate of plasmids and ARGs, and related factors during the swine manure treatment process, thereby facilitating the development of a new treatment technique for removing ARGs and reducing the public health risk associated with livestock production.

Discharge of 2,4-dinitrotoluene (2,4-DNT) into the environment leads to a serious soil and water sources pollution problem, due to toxicity and possible carcinogenicity of this toxic substance. In this work, the photocatalytic degradation of 2,4-DNT was investigated using CoFe₂O₄/SiO₂/TiO₂ nanoparticles. The catalyst features were characterized by using XRD, TEM, EDX, UV-vis DRS, FTIR, and VSM techniques. The influence of different experimental factors on degradation efficiency including pH value, catalyst dosages, and initiate concentration of 2,4-DNT were investigated. Mineralization of the model pollutant was determined using TOC analysis under optimum conditions. A possible mechanism, process kinetic and reusability of magnetic photocatalyst were also performed. In optimum experimental conditions (pH=3, photocatalyst dosage=0.75 g/L, 2,4-DNT=0.025 g/L), degradation efficiency achieved 88.5% within 180-min reaction time with TOC removal of 55.6%. Dominate oxidizing radicals during the degradation of 2,4-DNT by CoFe₂O₄/SiO₂/TiO₂ were hydroxyl radicals. The photocatalytic degradation of 2,4-DNT followed first-order rate kinetics. After three successive use cycles, the degradation efficiency was reduced by 64%. Our results revealed that the synthesized CoFe₂O₄/SiO₂/TiO₂ photocatalyst was a good choice for degradation of 2,4-DNT, due to proper potential reusability and catalytic activity.

As one of the large ecological infrastructures, the urban water system connectivity (UWSC) project is an important part of urban ecosystem construction. It is helpful for the scientific planning and construction of the project to systematically evaluate the effects. However, due to the complex and various effects of UWSC project, there is no complete effect system and quantitative method. Against this backdrop, the composition and mechanism of positive and negative effects of ecological economics of UWSC project were deeply analyzed to improve the composition system of eco-economic effects in this study. At the same time, the emergy theory was used to put forward the quantification method of eco-economic effect system. Taking the UWSC project in Xuchang as an example, its ecological, social, and economic effects were evaluated. The result showed that the average eco-economic effect of the project is 49.97 million dollars/year. Economic effect and ecological effect are significant, accounting for 82.49% and 15.89% of total effect, respectively. This study can provide reference for comprehensive and unified assessment of eco-economic effects of UWSC project.