Fluoroquinolones (FQs) present in water environments pose threats to aquatic organisms. The concentration of FQs adsorbed onto sediments is generally higher than that in water. Here, we studied the toxicities of two FQ antibiotics, norfloxacin (NOR) and ofloxacin (OFL), on the snail Bellamya aeruginosa, an adaptable benthic animal. For this, we performed acute toxicity experiments on young snails and sub-chronic exposure experiments on adult snails by exposure to the FQs for 1–28 days. The 96 h median effective concentrations showed that NOR toxicity was higher than OFL toxicity, although both NOR and OFL were low-toxicity substances (EC₅₀ > 100 mg L⁻¹). Four concentrations were used in the sub-chronic exposure experiments. Results of the measurement of bioconcentration factors (BCF) showed that OFL accumulation was higher than NOR accumulation in snail tissues. During the depuration period (28–49 days), at low concentrations (2 and 20 μg L⁻¹), both FQs required at least 7 days to reach the maximum residue limit (50 μg kg⁻¹). Conversely, at high concentrations (200 and 2000 μg L⁻¹), 14 days (NOR) and 21 days (OFL) were required. Our results could facilitate management of the environmental risks of antibiotics and conservation of aquatic animals.

Numerous mitigation techniques have been incorporated to capture or remove SO₂ with flue gas desulfurization (FGD) being the most common method. Regenerative FGD method is advantageous over other methods due to high desulfurization efficiency, sorbent regenerability, and reduction in waste handling. The capital costs of regenerative methods are higher than those of commonly used once-through methods simply due to the inclusion of sorbent regeneration while operational and management costs depend on the operating hours and fuel composition. Regenerable sorbents like ionic liquids, deep eutectic solvents, ammonium halide solutions, alkyl-aniline solutions, amino acid solutions, activated carbons, mesoporous silica, zeolite, and metal-organic frameworks have been reported to successfully achieve high SO₂ removal. The presence of other gases in flue gas, e.g., O₂, CO₂, NOx, and water vapor, and the reaction temperature critically affect the sorption capacity and sorbent regenerability. To obtain optimal SO₂ removal performance, other parameters such as pH, inlet SO₂ concentration, and additives need to be adequately governed. Due to its high removal capacity, easy preparation, non-toxicity, and low regeneration temperature, the use of deep eutectic solvents is highly feasible for upscale utilization. Metal-organic frameworks demonstrated highest reported SO₂ removal capacity; however, it is not yet applicable at industrial level due to its high price, weak stability, and robust formulation.

Facilitated by a receding sea ice extent, new and shorter routes have led to increased maritime traffic in Arctic areas with an inherent risk for oil spills along Arctic rocky shorelines. To estimate natural oil removal under Arctic conditions, a crude oil and a heavy fuel oil were applied to slate tiles, mimicking rocky shore substratum, and placed at four levels within and just above the tidal zone on two rocky shorelines in West Greenland. Tiles were regularly sampled (within 95 days) to determine natural oil removal and chemical composition of the remaining oil. We found that natural oil removal on the rocky shorelines depends on (1) level position on the shoreline, i.e., within and above the tidal zone where ample exposure to water and wave-wash increases oil removal rate and efficiency, and (2) physical and chemical oil properties with the crude oil being removed more readily than the heavy fuel oil. These findings can help improve the risk assessment of oil spills in Arctic areas and facilitate the development of effective oil spill response strategies in Arctic seas.

Polycyclic aromatic hydrocarbons are a class of highly toxic and unremitting organic pollutants that are widely distributed in the natural environment. In this work, a metal-organic framework (MOF) designated as HKUST-1 [Cu₃(BTC)₂] was synthesized, characterized, and applied as a solid-phase extraction sorbent for the determination of a trace polycyclic aromatic hydrocarbon, anthracene (Ant) as model compound, in various real samples by spectrofluorimetry. The synthesized MOF exhibited large surface areas and high extraction ability, making it excellent candidate as sorbent for enrichment of trace anthracene. The effects of influential parameters on the performance of the dispersive micro-solid-phase extraction (Dμ-SPE) process, such as the initial anthracene concentration, pH, sorbent dosage, and shaking time, were investigated and optimized by the experiment design method. Under the optimized experimental conditions, good linearity in the range of 3–85 ng mL⁻¹ with correlation coefficient 0.997 and good sensitivity with low detection limit 0.5 ng mL⁻¹ for Ant was achieved. The method has been validated in the analysis of real tap water, soft drink, and vegetable juice samples with recoveries in the range of 86.33–103.00% and relative standard deviations in the range of 1.94–3.77%. The as-prepared HKUST-1 was used for at least four times without any obvious decline of extraction capability. The results of this study show the great potential of MOFs as sorbents in Dμ-SPE procedures for the separation and determination of trace Ant in complicated matrices.

Blechnum orientale L. is a traditional, medicinal fern found in China. To assess the characteristics of heavy metals and As accumulation, the fronds, roots, and the rooting soils of this fern were sampled from urban, suburban, and rural woodlands across Guangdong Province in southern China. The concentrations of As, Cd, Cr, Cu, Hg, Mn, Ni, Pb, and Zn in both the fern and its rooting soils were separately detected by ICP-MS. Contamination levels of woodland rooting soils were also assessed using both a single pollution index and the Nemerow pollution index. Both the metal concentrations and the pollution index showed that soils from urban, suburban, and even rural woodlands were adversely contaminated by As, Cd, Hg, and Pb. Based on transfer factor, B. orientale had good translocation of As, Hg, and Mn, but poor translocation of Cd, Cr, Ni, Cu, Ni, Pb, and Zn from the roots to the fronds. This result suggests that this fern could be an excluder to latter metals. Despite the significantly higher levels of metals in the roots as compared with the fronds, the low bioaccumulation factor suggests that this fern has a weak capacity for metal accumulation.

Calcium peroxide (CP) has been widely applied in environmental remediation, but few studies have reported its application in controlling Microcystis blooms. To recognize its feasibility for mitigating Microcystis blooms, the properties of CP in terms of hydrogen peroxide (HP) release and phosphate removal were investigated at different CP doses, temperatures, and initial pH values. HP release kinetics followed the Higuchi model. Batch experiments conducted in this study suggested that the HP yield and release rate were positively correlated with the CP dose. Increasing temperature decreased the HP yield but accelerated the HP release rate. The phosphate removal kinetics were well simulated by the pseudo-second-order model. The batch experiments suggested that an increased CP dose enhanced the phosphate removal capacity, but it did not affect the phosphate removal rate. Moreover, increased temperature accelerated both phosphate removal capacity and rate. However, the initial pH of low-buffer-capacity solutions did not notably affect HP release and phosphate removal. According to laboratory experiments, HP released from CP could impair photosynthetic activity, resulting in Microcystis mortality. Furthermore, the reduced phosphate concentration in the solutions suggested that CP could facilitate the control of eutrophication, which directly reduced bloom formation. Hence, our results confirmed CP as a promising algicide for Microcystis bloom control, and it is worthwhile to develop novel methods for bloom mitigation based on CP. Graphic abstract

Carbon intensity refers to the carbon emission of per unit output generated by a country or a region. It shows the economic system’s close connection with carbon emission and its direct or indirect influence on environment. The carbon intensity curves of many countries visually show significant features of convergence. In order to strictly testify this phenomenon, this thesis chronologically defines convergence of carbon intensity and testifies it with endogenous growth model as theoretical basis. To realize the empirical test on convergence of carbon intensity, the author selects 24 countries as test samples and divides them into 3 groups, on which σ convergence test and cointegration test are conducted. Test result shows that convergence of carbon intensity exists in countries with high or medium high income, while countries with medium or low income shows insignificant convergence tendency in carbon intensity. Besides, σ convergence test demonstrates the time and degree ranking of convergence of carbon intensity of the 3 groups, which provides a concrete referential standard for countries to analyze and control changes in carbon intensity.

Tianbao reservoir in southern China (surrounded by Eucalyptus plantation) serves as a source of drinking water for the inhabitants. However, the reservoir water experiences black water (BW) of which the cause remains unclear. In this study, field observation and simulated laboratory experiment were conducted to understand the cause of the BW. The diffusive gradient in thin-film (DGT) device monitored the spatial changes in concentration of iron (Fe²⁺), manganese (Mn²⁺), sulfide (S²⁻), and dissolved organic carbon (DOC) at the SWI. The planar optode (PO) showed that hypoxia contributed immensely to the high positive fluxes Fe²⁺, Mn²⁺, and S²⁻ measured, which co-precipitated to form black materials (FeS and MnS) at the SWI. The co-precipitation between Fe–S and Mn–S was supported by their significant positive correlation (Fe–S: r > 0.05, p < 0.05, Mn–S: r > 0.2, p < 0.05). Significant reduction (p < 0.05) in tannins concentration from November (strong thermal stratification) to December (weak thermal stratification) indicated that Fe²⁺ and tannins reacted during the mixing of reservoir water in December due to weak stratification. The simulated experiment confirmed that fresh Eucalyptus leaves produces a significant (p < 0.05) amount of tannins during hypoxia and reacts with Fe²⁺ to produce black water. A high positive correlation (r > 0.8) between Fe²⁺ and DOC demonstrated that Fe²⁺ and DOC combined and contributed to the reservoir water blackening. The study provides a better understanding on the impact of Eucalyptus plantation on water quality and provide guidance for scientific planting of Eucalyptus plantation in reservoir basins in southern China to ensure safe drinking water.

Industrial parks play an extremely important role in the rapid development of China’s economy. However, as the backbone of China’s economic development, industrial parks also consume huge energy resources and cause serious pollution to the environment, making China face greater pressure on environmental issues. This article takes the Yongcheng Economic and Technological Development Area, a typical energy-intensive industrial park in Henan Province, as the research object to analyze its energy saving and emission reduction potential. Three scenarios (baseline scenario, energy cascade utilization scenario, and energy efficiency technology enhancement scenario) are set to quantify the energy-saving potential and air pollutant emission reduction of the park under different scenarios. The results show that in the energy cascade utilization scenario, by realizing the recycling of waste heat resources from heat source enterprises, it can bring energy saving of 6385 TJ, and reduce 0.35 kt SO₂, 0.79 kt NOₓ, 0.067 kt PM₁₀, and 0.035 kt PM₂.₅. And CO₂ emission reductions have reached 604 kt. In the energy efficiency technology enhancement scenario, by eliminating relatively backward technologies and adding advanced energy-saving technologies, 7306 TJ energy saving could be achieved. SO₂, NOₓ, PM₁₀, PM₂.₅, and CO₂ emission reductions are 0.37, 0.82, 0.038, 0.071, and 719 kt, respectively. The results of the CALPUFF model indicate that the pollutant concentrations of SO₂, NOₓ, PM₁₀, and PM₂.₅ in the spring and autumn are relatively high, while those in the summer and winter seasons are relatively low. In four seasons, the highest 1-h average concentration and dispersion range of four pollutants have been reduced both in the energy cascade utilization scenario and in the efficiency technology enhancement scenario.

The coronavirus (COVID-19) pandemic is infecting the human population, killing people, and destroying livelihoods. This research sought to explore the associations of daily average temperature (AT) and air quality (PM₂.₅) with the daily new cases of COVID-19 in the top four regions of Spain (Castilla y Leon, Castilla-La Mancha, Catalonia, and Madrid). To this end, the authors employ Pearson correlation, Spearman correlation, and robust panel regressions to quantify the overall co-movement between temperature, air quality, and daily cases of COVID-19 from 29 February to 17 July 2020. Overall empirical results show that temperature may not be a determinant to induce COVID-19 spread in Spain, while the rising temperature may reduce the virus transmission. However, the correlation and regression findings illustrate that air quality may speed up the transmission rate of COVID-19. Our findings are contrary to the earlier studies, which show a significant impact of temperature in raising the COVID-19 spread. The conclusions of this work can serve as an input to mitigate the rapid spread of COVID-19 in Spain and reform policies accordingly.