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Abstract A novel and effective photocatalyst namely titanium dioxide doped with zinc elements stacked on reed straw biochar which was pretreated by acid (Zn-TiO 2 /pBC) with visible light response was successfully prepared by a simple modified sol-gel method firstly. The prepared samples were characterized by scanning microscopy (SEM), energy dispersive X-ray spectrum (EDS), X-ray diffraction (XRD), nitrogen adsorption-desorption (BET) and UV–Vis diffuse reflectance spectra (DRS). The photocatalytic activity of Zn-TiO 2 /pBC was further investigated through the photodegradation of sulfamethoxazole (SMX). Compared with TiO 2 and TiO 2 /pBC, Zn-TiO 2 /pBC had better photocatalytic activity under visible light due to zinc elements effectively inhibiting the agglomeration of TiO 2 and hindering the combination of photogenerated electrons and holes. The removal rate of SMX could reach 81.21%, which was 1.37 times higher than that of TiO 2 /pBC(300). Three common anions (SO 4 2−, Cl−, NO 3 −) existing in the Yellow River exhibited detrimental effects on the SMX photodegradation to a certain degree. It might mainly occurred hydroxylation, cleavage of S N bond and opening of isoxazole ring reactions during the photodegradation process of SMX. Meanwhile, there might be four main degradation pathways proposed throw the LC/MS/MS analysis. Finally, good reusability and stability illustrated Zn-TiO 2 /pBC owned good practicality and feasibility for removal of organic pollutants in environment remediation area. Graphical abstract Unlabelled Image Highlights • Zn-TiO 2 /pBC as a novel and effective photocatalyst was successfully synthesized firstly. • Zn-TiO 2 /pBC could absorb visible light due to the presence of zinc and biochar. • Effect of common anions in the Yellow River on the SMX photodegradation was evaluated. • Five regeneration results showed excellent reusability and stability of Zn-TiO 2 /pBC. • Photocatalytic mechanism and degradation pathways of SMX were analyzed. [ABSTRACT FROM AUTHOR]

Arsenic (As) speciation and bioaccumulation in fish muscle tissues have been intensively investigated in marine ecosystem. However, little is known about these in freshwater fish. In this study, freshwater fish including 120 specimens and 8 species were collected from the Xiang River, a typical mine-impacted river in China. Six As species including arsenite (AsIII), arsenate (AsV), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), arsenocholine (AsC) and arsenobetaine (AsB) were simultaneously separated and determined using HPLC-ICP-MS. The mean (± SD) concentration of total As (tAs) in the dried fish muscle was 0.748 ± 0.651 mg·kg − 1 . AsB was found as the predominant As species in most of the studied fish samples, in accordance with the reports in marine fish. However, the diversity of inorganic/organic As proportion observed in the studied freshwater fish species was larger than that in marine fish species due to greater spatial variability of As contamination, mobilization and origination in the studied catchments. The percentage of AsB (AsB%) in fish muscle was irrelevant to tAs concentration, while the percentage of iAs (iAs%) decreased with tAs concentration in a hyperbolic pattern. This can be attributed to restricted assimilation and accumulation of toxic iAs with increasing tAs concentration in fish. Chronic non-carcinogenic and carcinogenic health risks were evaluated through Monte-Carlo simulation. The result indicated that consuming freshwater fish in the Xiang River could cause considerable carcinogenic risk to local inhabitants. [ABSTRACT FROM AUTHOR]

Water shortage has become a serious problem for the sustainable development of irrigated agriculture in arid regions. In these areas, the scale and planting structure of agriculture suitable for local water resources is particularly important. Irrigation water demand is a crucial indicator of water requirement in irrigation districts. In this study, Mann-Kendall method was used to analyze the temporal changes of climatic factors of the past 50 years and ArcGis to determine spatial changes in human activities. The path analysis was used to quantitative characterize direct and indirect effects of these factors on irrigation water demand and suggest how human activity can be altered to reduce irrigation water demand. The results show that temperature has risen significantly since the completion of the second-stage irrigation district, wind speed has dropped since the completion of the first-stage irrigation district, and cultivated land area has greatly expanded. The direct impact and comprehensive effect of planting area on irrigation water demand is the largest. Controlling for the total water intake, the maximum agricultural planting scale is 40,133 ha. Through adjustment of the planting structure, the scale of irrigated agriculture could increase by as much as 25.8%. Therefore, agricultural planting structures and planting scales suitable for local water resources should be put into action for future sustainable development of agriculture. Unlabelled Image • Calculated the timing change of net irrigation water demand • Climate factors and human activities have changed significantly. • Planting area is the most important direct factor affecting crop water demand. • Adjusting crop planting structure expands agro-scale by 25.8% at given water supply. [ABSTRACT FROM AUTHOR]

Bi 2 WO 6 possesses good stability but poor photocatalytic activity under visible light. Herein, the coupling of Bi 2 WO 6 , Fe 3 O 4 and biochar (Bi 2 WO 6 /Fe 3 O 4 /BC) was investigated to enhance the photocatalytic performance of Bi 2 WO 6 through facile hydrothermal method, which almost completely degraded ofloxacin (OFL) and ciprofloxacin (CIP) within 30 min under energy-saving visible LED irradiation. The superior photocatalytic activity of Bi 2 WO 6 /Fe 3 O 4 /BC was ascribed to the stronger visible light adsorption capacity and the lower recombination of electron-hole pairs. O 2 − played a major role during the photocatalytic reaction. The characterization results suggested that the introduction of biochar avoided the agglomeration of Bi 2 WO 6 microspheres and Fe 3 O 4 nanoparticles, at the same time, the biochar participated in OFL and CIP photodegradation by consuming different oxygen-containing functional groups. In order to further evaluate the application potential of Bi 2 WO 6 /Fe 3 O 4 /BC, the effects of environment factors and the application in different actual water were carefully investigated. Various transformation products and the possible degradation pathways of OFL and CIP were analyzed based on high resolution mass spectrometry (HRMS) results, moreover, the toxicity evaluation results of Escherichia coli indicated these intermediates products were less toxic compared OFL and CIP. Overall, Bi 2 WO 6 /Fe 3 O 4 /BC can provide a potential way for the application of photocatalytic technology in ambient wastewater purification. Unlabelled Image • Bi 2 WO 6 /Fe 3 O 4 /BC exhibited excellent removal rates of ofloxacin and ciprofloxacin. • Fe 3 O 4 and biochar promoted the light absorption property and charge separation. • O 2 − was the main active species in ofloxacin and ciprofloxacin degradation. • Hydroxylation and ring cleavage of these two drugs were main degradation pathway. • Bi 2 WO 6 /Fe 3 O 4 /BC had broad prospects in antibiotic-contaminated sewage treatment. [ABSTRACT FROM AUTHOR]

Coastal marshes have a significant capacity to sequester carbon; however, sea-level rise (SLR) is expected to result in prolonged flooding and saltwater intrusion in coastal regions. To explore the effects of SLR projections on net CO 2 uptake in coastal marshes, we conducted a "double-check" investigation, including the eddy covariance (EC) measurements of the CO 2 fluxes in subtropical coastal marshes along inundation and salinity gradients, in combination with a mesocosm experiment for analyzing CO 2 flux components under waterlogging and increased salinity conditions. During the same measurement periods, the net ecosystem CO 2 exchange (NEE EC based on the EC dataset) in an oligohaline marsh was higher than that in a low-elevation mesohaline marsh, whereas the NEE EC was lower than that in a high-elevation freshwater marsh. The declines in NEE EC between the marshes could be attributed to a greater decrease in gross primary production relative to ecosystem respiration. Waterlogging slightly increased the NEE ms (NEE based on the mesocosms) because of inhibited soil respiration and slight changes in plant photosynthesis and shoot respiration. However, the NEE ms measured during the drainage period decreased significantly due to the stimulated soil respiration. The NEE ms decreased with increasing salinity (except under mild salinity), and waterlogging exacerbated the adverse impacts of salinity. The amplificatory effect of decreases in both leaf photosynthesis and growth under hydrological stresses contributed more to reduce the NEE ms than to respiratory effluxes. Both waterlogging and increased salinity reduced the root biomass, soil microbial biomass, and activities of assayed soil enzymes (except for cellulase under waterlogging conditions), leading to limited soil respiration. The declines in plant growth, photosynthesis, and soil respiration could also be attributed to the decrease in soil nutrients under waterlogging and increased salinity conditions. We propose that the coupling of SLR-driven hydrological effects lowers the capacity of CO 2 uptake in subtropical coastal marshes. Unlabelled Image • NEE of the coastal marshes decreased under SLR projection at various scales. • Decline in NEE was attributed to the unequal responses of GPP and ER to stresses. • Limited leaf growth and photosynthesis significantly reduced carbon uptake. • SLR projection reduced plant biomass, soil microbial biomass and enzyme activities. • Decreased soil nutrients also affected the carbon budget in marsh plants and soil. [ABSTRACT FROM AUTHOR]

The rapid development of global COVID-19 pandemic poses an unprecedented challenge to the safety and quality of laboratory diagnostic testing. Little is known about the laboratory surface areas and operation behaviors that may cause potential contamination in SARS-CoV-2 nucleic acid testing. This study aims to provide reference basis for the improvement of laboratory disinfection programs and personal operating protocols. In this study, we compared the qRT-PCR and ddPCR in detecting of residual virus that existed on the object surfaces from sample transportation and reception related facilities, testing related instruments, personal protective equipment and other facilities in nucleic acid testing laboratory. All samples were negative by qRT-PCR, in contrast, 13 of 61 samples were positive for SARS-CoV-2 by ddPCR. The areas with highest density of SARS-CoV-2 nucleic acid were the outer gloves of operator A (37.4 copies/cm2), followed by door handle of 4 °C refrigerator (26.25 copies/cm2), goggles of operator A (22.16 copies/cm2), outer cover of high speed centrifuge (19.95 copies/cm2), inner wall of high speed centrifuge (14.70 copies/cm2) and others. We found that all the positive objects were directly or indirectly contacted by the operator's gloved hands, suggesting that hands contact was the main transmission pathway that led to laboratory environmental contamination. In summary, ddPCR has an advantage over qRT-PCR in tracing laboratory contamination. We evaluated the risk areas and operation behaviors that may easily cause contamination, and provided recommendation for improving the laboratory disinfection programs and personal operating specifications. Hands contact was the main transmission pathway that led to laboratory environmental contamination, during testing on SARS-CoV-2 in BSL-2. Unlabelled Image • Hands contact was the main transmission pathway that led to BSL-2 contamination. • ddPCR has an advantage over qRT-PCR in tracing laboratory contamination. • Risk areas and operation behaviors that may cause contamination were evaluated. • Recommendations were provided to improve the laboratory safety and test quality. [ABSTRACT FROM AUTHOR]

In this work, nanoscale zero-valent iron (NZVI) was synthesized via liquid phase reduction method with surfactant polyethylene glycol (PEG-4000) modified and supported onto zeolite to prepare PZ-NZVI composite. SEM-EDS, XPS, BET.etc. characterizations indicated that the sphere NZVI particles were loaded on the zeolite successfully and the aggregation was restrained. The adsorption performance of PZ-NZVI for norfloxacin (NOR) or ofloxacin (OFL), two typical fluoroquinolones (FQs), from water was conducted. The equilibrium studies were demonstrated using Langmuir, Freundlich, Temkin and Elovich isotherms and better agreement was attained with the Temkin model. Compared with NZVI and zeolite, PZ-NZVI had higher FQs removal efficiency, and the Langmuir maximum adsorption capacity was 54.67 mg g−1 (NOR) and 48.88 mg g−1 (OFL). The kinetic parameters displayed that two FQs adsorption onto PZ-NZVI followed pseudo-second-order kinetic model. The thermodynamic analysis suggested the adsorption process was spontaneous and exothermic. In addition, the adsorption tests were executed at different influence factors and the adsorbent PZ-NZVI was suitable for a wide pH range (4–10) with the FQs (10 mg L−1) removal efficiency above 90% in 1 h. Furthermore, it was found that PZ-NZVI can be effortlessly separated from mixed solutions using external magnetic field. Finally, the process of FQs adsorbed onto PZ-NZVI was attributed to the surface complexion (forming bidentate complexes), hydrophobic interaction, pore filling and electrostatic interaction. Unlabelled Image • PZ-NZVI composite was prepared and well applied for two FQs removal in water. • Coating PEG-4000 and supported on zeolite enhanced the dispersity of NZVI. • Temkin isotherm and pseudo-second-order kinetic models best fitted experimental data. • Electrostatic, hydrophobic interactions and complexation were the main mechanisms. [ABSTRACT FROM AUTHOR]

Three adsorbents, namely, original biochar (CLB), montmorillonite (MMT)-biochar composite (MBC), and magnetic MMT-biochar composite (MMBC) were successfully fabricated by one step pyrolysis of original cauliflower (Brassica oleracea L.) leaves, mixture of cauliflower leaves and MMT, and FeCl 3 -laden mixture of cauliflower leaves and MMT under limited oxygen atmosphere, respectively. The characterizations of samples indicated that substantial MMT mineral particles and Fe 3 O 4 nanoparticle were dispersed on the surface of MMBC. Due to the introduction of Fe 3 O 4 , MMBC performed excellent magnetization property. The adsorption experiments of oxytetracycline (OTC) indicated that the maximum adsorption ability of MMBC was 58.85 mg·g−1, which was 2.63 times as large as CLB, also, larger than that of MBC. Meanwhile, pH, ionic strength, and humic acid (HA) performed slight effects for adsorption of OTC on MMBC. In addition, MMBC still removed 92% OTC after five regeneration cycles. Finally, primary mechanisms of OTC adsorption onto MMBC were attributed to hydrogen bonding and π-π reaction, and ion exchange reaction was considered to exist. Meanwhile, functional groups including Si-O-Al, Si-O-Si, Si-O, and Fe 3 O 4 nanoparticles would provide extra binding sites for OTC adsorption. Therefore, MMBC had an obvious potential to apply into water purification as a reliable, low-cost, and environmentally friendly adsorbent. Unlabelled Image • Magnetic montmorillonite biochar material is first prepared by one step pyrolysis. • The composite performs excellent adsorption capacity for oxytetracycline. • Adsorption is mainly controlled by hydrogen bond, π-π and ion exchange reactions. • Fe 3 O 4 nanoparticles on composite provide extra adsorption sites. • The spent composite is successfully regenerated and collected by magnet. [ABSTRACT FROM AUTHOR]