Sex-Specific Effects of Environmental Exposure to the Antimicrobial Agents Benzalkonium Chloride and Triclosan on the Gut Microbiota and Health of Zebrafish (Danio rerio).

The use of disinfectants containing benzalkonium chloride (BAC) has become increasingly widespread in response to triclosan (TCS) restrictions and the COVID-19 pandemic, leading to the increasing presence of BAC in aquatic ecosystems. However, the potential environmental health impacts of BAC on fish remain poorly explored. In this study, we show that BAC and TCS can induce the gut dysbiosis in zebrafish (Danio rerio), with substantial effects on health. Breeding pairs of adult zebrafish were exposed to environmentally relevant concentrations of BAC and TCS (0.4-40 µg/L) for 42 days. Both BAC and TCS exposure perturbed the gut microbiota, triggering the classical NF-κB signaling pathway and resulting in downstream pathological toxicity associated with inflammatory responses, histological damage, inhibited ingestion, and decreased survival. These effects were dose-dependent and sex-specific, as female zebrafish were more susceptible than male zebrafish. Furthermore, we found that BAC induced toxicity to a greater extent than the restricted TCS at environmentally relevant concentrations, which is particularly concerning. Our results suggest that environmental exposure to antimicrobial chemicals can have ecological consequences by perturbing the gut microbiota, a previously underappreciated target of such chemicals. Rigorous ecological analysis should be conducted before widely introducing replacement antimicrobial compounds into disinfecting products.

Concentration levels and ecological risk assessment of typical organophosphate esters in representative surface waters of a megacity.

Organophosphate esters (OPEs) have been widely used as flame retardants and plasticizers in consumer and industrial products. They have been found to have numerous exposure hazards. Recently, several OPEs have been detected in surface waters around the world, which may pose potential ecological risks to freshwater organisms. In this study, the concentration, spatial variation, and ecological risk of 15 OPEs in the Beiyun and Yongding rivers were unprecedentedly investigated by the ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) and risk quotient (RQ) method. The result showed that triethyl phosphate (TEP), tri (2-chloroisopropyl) phosphate (TCPP) were the most abundant OPEs with average concentrations of 55.53 ng/L and 42.29 ng/L, respectively. The concentrations of OPEs in the Beiyun River are higher than in the Yongding River, and their levels were higher in densely populated and industrial areas. The risk assessment showed that there was insignificant from OPEs to freshwater organisms in these rivers (RQs <0.1). The risk was higher downstream than upstream, which was related to human-intensive industrial activities downstream in the Yongding River. The ecological risk of OPEs in surface waters worldwide was estimated by joint probability curves (JPCs), and the result showed that there was a moderate risk for tri (2-chloroethyl) phosphate (TCEP), a low risk for trimethyl phosphate (TMP), and insignificant for other OPEs. In addition, the QSAR-ICE-SSD model was used to calculate the hazardous concentration for 5% (HC5). This result validated the feasibility and accuracy of this model in predicting acute data of OPEs and reducing biological experiments on the toxicity of OPEs. These results revealed the ecological risk of OPEs and provided the scientific basis for environmental managers.

Temperature-Dependent Molecular Evolution of Biochar-Derived Dissolved Black Carbon and Its Interaction Mechanism with Polyvinyl Chloride Microplastics.

Biochar-derived dissolved black carbon (DBC) molecules are dependent on the BC formation temperature and affect the fate of emerging contaminants in waters, such as polyvinyl chloride microplastic (MPPVC). However, the temperature-dependent evolution and MPPVC-interaction of DBC molecules remain unclear. Herein, we propose a novel DBC-MPPVC interaction mechanism by systematically interpreting heterogeneous correlations, sequential responses, and synergistic relationships of thousands of molecules and their linking functional groups. Two-dimensional correlation spectroscopy was proposed to combine Fourier transform-ion cyclotron resonance mass spectrometry and spectroscopic datasets. Increased temperature caused diverse DBC molecules and fluorophores, accompanied by molecular transformation from saturation/reduction to unsaturation/oxidation with high carbon oxidation states, especially for molecules with acidic functional groups. The temperature response of DBC molecules detected via negative-/positive-ion electrospray ionization sequentially occurred in unsaturated hydrocarbons → lignin-like → condensed aromatic → lipid-/aliphatic-/peptide-like → tannin-like → carbohydrate-like molecules. DBC molecular changes induced by temperature and MPPVC interaction were closely coordinated, with lignin-like molecules contributing the most to the interaction. Functional groups in DBC molecules with m/z < 500 showed a sequential MPPVC-interaction response of phenol/aromatic ether C-O, alkene C═C/amide C═O → polysaccharides C-O → alcohol/ether/carbohydrate C-O groups. These findings help to elucidate the critical role of DBCs in MP environmental behaviors.

Heterogeneous Dynamic Behavior and Synergetic Evolution Mechanism of Internal Components and Released Gases during the Pyrolysis of Aquatic Biomass.

Evolution of gaseous contaminants from biomass pyrolysis has drawn increasing attention. However, the thermal degradation, dynamics, and synergetic evolution mechanisms during real-time biomass pyrolysis remain unclear. Herein, a novel method using thermogravimetry-Fourier transform infrared spectrometry-gas chromatography/mass spectrometry (TG-FTIR-GC/MS) combined with thermal kinetics and two-dimensional correlation spectroscopy was proposed to explore the chemical properties and temperature response mechanisms of gaseous species released during Phragmites communis (PC) and Typha angustifolia (TA) pyrolysis. The thermal degradation mechanisms of PC/TA pyrolysis were mainly associated with the sigmoidal rate and random nucleation mechanisms. The formation intensities of alcohols/ethers, phenols/esters, acids, aldehydes, and ketones were higher during low-temperature TA pyrolysis and high-temperature PC pyrolysis. The average carbon oxidation state (OS¯C) of gaseous species mainly ranged from -1.5 to -0.5, and the OS¯C slope of most gaseous species was greater than -2.0, which was related to the reduction of aldehyde/ketone groups. Two-dimensional (2D)-TG-FTIR-COS analysis revealed that the sequential temperature response of gaseous species followed: acids → phenols, esters → aldehydes → hydrocarbons → alcohols, ethers → aromatics during PC/TA pyrolysis. The establishment of relationships between the sequential response of gases and degraded components provides an important basis for online monitoring/recovery of gaseous contaminants during biomass pyrolysis.

Dynamic Evolution and Covariant Response Mechanism of Volatile Organic Compounds and Residual Functional Groups during the Online Pyrolysis of Coal and Biomass Fuels.

Volatile organic compound (VOC) emissions from pyrolysis of widely used biomass are expected to increase significantly under the carbon neutrality target. However, the dynamic emissions and evolution mechanism of biomass-VOCs remain unclear, hindered by complex reactions and offline measurements. Here, we propose a novel covariant evolution mechanism to interpret the emission heterogeneities, sequential temperature responses, and evolved correlations of both VOCs and residual functional groups (RFGs) during corn straw (CS), wood pellet (WP), and semibituminous coal (SBC) pyrolysis. An innovative combination of online thermogravimetric-Fourier transform infrared-gas chromatography/mass spectrometry and two dimensional-correlation spectroscopy was applied. The relative percentages of CS/WP-VOCs were higher than those of SBC-VOCs, and most VOCs tended to have relatively small carbon skeletons as the average carbon oxidation state increased. With the temperature increased from low to high during CS/WP pyrolysis, the primary sequential response of VOCs (acids → phenols/esters → alcohols/ethers/aldehydes/ketones → hydrocarbons/aromatics) corresponded to the RFG response (hydroxyl groups → -CH3/-CH2-/-CH groups → aliphatic ethers and conjugated ketones). Compared with the relative regularity for CS/WP responses, the gas-solid products from SBC pyrolysis exhibited complex temperature-dependent responses and high oxidation-induced variability. These insights provide favorable strategies for the online monitoring system to facilitate priority removal of coal and biomass fuels-VOCs.

General Challenges and Recommendations for the Water Quality Criteria of Endocrine Disrupting Chemicals (EDCs).

Water quality criteria (WQC) play an important role in the environmental management of pollutants in different countries or institutions. It has been found that endocrine disrupting chemicals (EDCs) can potentially alter functions of the endocrine system and consequently cause adverse effects in aquatic organisms. Therefore, the complicated modes of action and mechanisms of EDCs should be carefully considered in WQC studies. For example, the research regarding the WQC derivation of EDCs should prioritize sensitive aquatic species in consideration of the WQC derivation. Second, the chronic toxicity of EDCs should be of utmost concern. In addition, the appropriate effects and endpoints of EDCs should be carefully selected for the WQC derivation. Moreover, it was pointed out that some new methods should be taken into consideration in the WQC studies of EDCs in the near future.

Novel Insights into the Molecular-Level Mechanism Linking the Chemical Diversity and Copper Binding Heterogeneity of Biochar-Derived Dissolved Black Carbon and Dissolved Organic Matter.

Biochar-derived dissolved black carbon (DBC) varies in chemical composition and significantly affects the environmental fate of metal ions. However, the intrinsic molecular composition of DBC fractions and their molecular interaction mechanisms with metal ions remain unclear. We propose a novel, molecular-level covariant binding mechanism to comparatively interpret the heterogeneities, active sites, and sequential responses of copper binding with molecular compounds in DBC and natural dissolved organic matter (DOM). Relatively large proportions of lipid/aliphatic/peptide-like compounds with low mass distributions and lignin-like compounds with oxidized/unsaturated groups existed in acidic- and alkaline-extracted DBC, respectively. A larger percentage of tannin-like/condensed aromatic compounds and higher average conditional stability constants (logK̅Cu) of visible fluorescent components were found for DOM than for DBC. Overall, 200-320 Da and 320-480 Da molecular components contributed significantly to the logK̅Cu values of UVA and visible fluorescent components, respectively, in DBC/DOM. Nitrogenous groups likely exhibited stronger binding affinities than phenolic/carboxylic groups. The sequential copper-binding responses of molecular compounds in DBC/DOM generally followed the order lipid/aliphatic/peptide-like compounds → tannin-like compounds → condensed aromatic compounds. These insights will improve the prediction of the potential effects of DBC on various contaminants and the risks of biochar application to ecosystems.

The sublethal effects of ethiprole on the development, defense mechanisms, and immune pathways of honeybees (Apis mellifera L.).

Ethiprole has been widely used in agriculture, but there have been few studies on the adverse effects of ethiprole on nontarget organisms. This study focused on the mechanism of the sublethal effects of ethiprole on the development, antioxidation mechanisms, detoxification mechanisms and immune-related gene expression of honeybees (Apis mellifera L.). Honeybee larvae were found to be more sensitive than pupae to ethiprole. It was found that ethiprole inhibited the pupation and eclosion of bee larvae in a dose-dependent manner, with ethiprole doses of 1 × 10-3 mg/L decreasing pupation and eclosion rates to 50.00 ± 8.84% and 20.83 ± 10.62%, respectively. The activities of antioxidative enzymes (superoxide dismutase and catalase) and detoxification factors (glutathione and glutathione S-transferase) were also significantly increased in ethiprole-exposed honeybees, indicating that a sublethal dose of ethiprole also induced oxidative stress in honeybees. In the 1 × 10-3 mg/L ethiprole-exposure group, the expression of pathogen recognition-related gene PGRP-4300 was upregulated 11.10 ± 0.45-fold, and that of detoxification-related gene CYP4G11 was upregulated 8.84 ± 0.11-fold, indicating that ethiprole induced an immune reaction in honeybees. To the best our knowledge, this study represents the first demonstration that sublethal concentrations of ethiprole inhibit honeybee development and activate honeybee defense and immune systems.

New insights on the enhanced non-hydroxyl radical contribution under copper promoted TiO2/GO for the photodegradation of tetracycline hydrochloride.

TiO2/graphene oxide (GO) as photocatalyst in the photo-degradation of multitudinous pollutants has been extensively studied. But its low photocatalytic efficiency is attributed to the high band gap energy which lead to low light utilization. Cu-TiO2/GO was synthesized via the impregnation methods to enhance the catalytic performance. The Cu-TiO2/GO reaction rate constant for photo-degradation of pollutants (tetracycline hydrochloride, TC) was about 1.4 times that of TiO2/GO. In 90 min, the removal ratio of Cu-TiO2/GO for TC was 98%, and the maximum degradation ratio occurred at pH 5. After five cycles, the removal ratio of Cu-TiO2/GO still exceeded 98%. UV-visible adsorption spectra of Cu-TiO2/GO showed that its band gap was narrower than TiO2/GO. Electron paramagnetic resonance (EPR) spectra test illustrated the generation rate of •O2- and •OH was higher in Cu-TiO2/GO system than TiO2/GO and TiO2 system. The contribution sequence of oxidative species was •O2- > holes (h+) > •OH in both TiO2/GO and Cu-TiO2/GO system. Interestingly, the contribution of •OH in Cu-TiO2/GO was less than that in TiO2/GO during the photo-degradation process. This phenomenon was attributed to the better adsorption performance of Cu-TiO2/GO which could reduce the accessibility of TC to •OH in liquid. The enhanced non­hydroxyl radical contribution could be attributed to that the more other active species or sites on (nearby) the surface of Cu-TiO2/GO generated after doping Cu. These results provide a new perspective for the tradition metal-doped conventional catalysts to enhance the removal of organic pollutants in the environment.

A preliminary study on pollution characteristics of surfactant substances in fine particles in the Beibu Gulf Region of China.

The pollution characteristics of surfactant substances in fine particles (PM2.5) in spring were studied in the Beibu Gulf Region of China, 68 samples of PM2.5 were collected at Weizhou Island in Beihai City from March 12 to April 17, 2015. The Anionic Surfactant Substances (ASS) and Cationic Surfactant Substances (CSS) in the samples were analyzed using Byethyl Violet Spectrophotometry and Disulfide Blue Spectrophotometry, respectively. Combined with the data from backward trajectory simulation, the effects of air pollutants from remote transport on the pollution characteristics of surfactant substances in PM2.5 in the Beibu Gulf Region were analyzed and discussed. The results showed that the daily mean concentrations of ASS and CSS in spring in the Beibu Gulf Region were 165.20 pmol/m3 and 8.05pmol/m3, and the variation ranges were 23.21-452.55 pmol/m3 and 0.65-31.31 pmol/m3, accounting for 1.82‰ ± 1.65‰ and 0.12‰ ± 0.11‰ of the mass concentration of PM2.5, respectively. These concentrations were lower than those in comparable regions around the world. There was no clear correlation between the concentrations of ASS and CSS in PM2.5 and the mass concentrations of PM2.5. Tourism and air transport had a positive contribution on the concentrations of ASS. The concentration of surfactant substances in PM2.5 was significantly impacted by wind speed and wind direction. Atmospheric temperature, air pressure and precipitation had little effect on the concentrations of surfactant substances. Surfactant substances in PM2.5 significantly impacted visibility. Results also showed that the main sources of surfactant substances were from the southern China and Southeast Asia.

Efficient antimony removal by self-assembled core-shell nanocomposite of Co3O4@rGO and the analysis of its adsorption mechanism.

Co3O4@rGO were facilely prepared by template free self-assemble in this study. The morphology of Co3O4@rGO was actiniaria-like core-shell structural nanocomposites. The formation mechanism of Co3O4@rGO core-shell nanocomposite was discussed according to its significant time-dependent morphology evolution course. To evaluate the application potential of Co3O4@rGO, its adsorption performance toward highly toxic antimony ions were studied. The Co3O4@rGO nanocomposite exhibit high anti-interference ability and high adsorption ability. The maximum adsorption capacities towards Sb(III) and Sb(V) are 151.04 and 165.51 mg/g, respectively. River water samples containing antimony violating the limit were used to evaluate the practical application of Co3O4@rGO, and high performance was achieved. The EU and China limits for antimony in drinking water can be met by using mesoporous Co3O4@rGO treating the actual river water samples with original antimony concentration lower than 50 µg/L. Adsorption isotherm, adsorption kinetics, pH and co-existing ions effects were also studied in details. The results indicate that mesoporous Co3O4@rGO is an excellent adsorbent for antimony removal. Mesoporous Co3O4@rGO nanocomposite is a potential candidate for antimony removal from waste water.

Plasmonic silver/silver oxide nanoparticles anchored bismuth vanadate as a novel visible-light ternary photocatalyst for degrading pharmaceutical micropollutants.

The degradation of pharmaceutical micropollutants is an intensifying environmental problem and synthesis of efficient photocatalysts for this purpose is one of the foremost challenges worldwide. Therefore, this study was conducted to develop novel plasmonic Ag/Ag2O/BiVO4 nanocomposite photocatalysts by simple precipitation and thermal decomposition methods, which could exhibit higher photocatalytic activity for mineralized pharmaceutical micropollutants. Among the different treatments, the best performance was observed for the Ag/Ag2O/BiVO4 nanocomposites (5 wt.%; 10 min's visible light irradiation) which exhibited 6.57 times higher photodegradation rate than the pure BiVO4. Further, the effects of different influencing factors on the photodegradation system of tetracycline hydrochloride (TC-HCl) were investigated and the feasibility for its practical application was explored through the specific light sources, water source and cycle experiments. The mechanistic study demonstrated that the photogenerated holes (h+), superoxide radicals (•O2-) and hydroxyl radicals (•OH) participated in TC-HCl removal process, which is different from the pure BiVO4 reaction system. Hence, the present work can provide a new approach for the formation of novel plasmonic photocatalysts with high photoactivity and can act as effective practical application for environmental remediation.

Simulated photo-degradation of dissolved organic matter in lakes revealed by three-dimensional excitation-emission matrix with regional integration and parallel factor analysis.

Simulated photo-degradation of fluorescent dissolved organic matter (FDOM) in Lake Baihua (BH) and Lake Hongfeng (HF) was investigated with three-dimensional excitation-emission matrix (3DEEM) fluorescence combined with the fluorescence regional integration (FRI), parallel factor (PARAFAC) analysis, and multi-order kinetic models. In the FRI analysis, fulvic-like and humic-like materials were the main constituents for both BH-FDOM and HF-FDOM. Four individual components were identified by use of PARAFAC analysis as humic-like components (C1), fulvic-like components (C2), protein-like components (C3) and unidentified components (C4). The maximum 3DEEM fluorescence intensity of PARAFAC components C1-C3 decreased by about 60%, 70% and 90%, respectively after photo-degradation. The multi-order kinetic model was acceptable to represent the photo-degradation of FDOM with correlation coefficient (Radj2) (0.963-0.998). The photo-degradation rate constants (kn) showed differences of three orders of magnitude, from 1.09 × 10-6 to 4.02 × 10-4 min-1, and half-life of multi-order model ( T1/2n) ranged from 5.26 to 64.01 min. The decreased values of fluorescence index (FI) and biogenic index (BI), the fact that of percent fluorescence response parameter of Region I (PI,n) showed the greatest change ratio, followed by percent fluorescence response parameter of Region II (PII,n), while the largest decrease ratio was found for C3 components, and the lowest T1/2n was observed for C3, indicated preferential degradation of protein-like materials/components derived from biological sources during photo-degradation. This research on the degradation of FDOM by 3DEEM/FRI-PARAFAC would be beneficial to understanding the photo-degradation of FDOM in natural environments and accurately predicting the environmental behaviors of contaminants in the presence of FDOM.

A review of atmospheric benzene homologues in China: Characterization, health risk assessment, source identification and countermeasures.

Benzene homologues are important chemical precursors to the formation of ground-level ozone and secondary organic aerosol (SOA) in the atmosphere, in addition, some toxic species are harmful to human health. Strict countermeasures have been taken to fight air pollution since 2013, and total amount control of volatile organic compounds is being promoted in China at present. Therefore, it is important to understand the pollution situation and the control status of ambient benzene homologues in China. This paper reviews research progress from published papers on pollution characteristics, atmospheric photochemical reactivity, health risk assessment and source identification of ambient benzene homologues in recent years in China, and also summarizes policies and countermeasures for the control of ambient benzene homologues and the relevant achievements. The total ambient levels of benzene, toluene, ethylbenzene and xylenes (BTEX) shows a declining tendency from 2001 to 2016 in China. The mass concentrations of BTEX are generally higher in southern regions than in northern regions, and they present vertical decreasing variation characteristics with increasing altitude within the height range of about 5500 m. Toluene has the highest ozone formation potential and SOA formation potential both in urban areas and background areas, while benzene poses an obvious carcinogenic risk to the exposed adult populations in urban areas. Source identification of ambient benzene homologues suggested that local governments should adopt differentiated control strategies for ambient benzene homologues. Several recommendations are put forward for future research and policy-making on the control of ambient benzene homologues in China.

Novel Insights into the Kinetics, Evolved Gases, and Mechanisms for Biomass (Sugar Cane Residue) Pyrolysis.

Biomass, a renewable energy source, via available thermo-chemical processes has both engineering and environmental advantages. However, the understanding of the kinetics, evolved gases, and mechanisms for biomass pyrolysis is limited. We first propose a novel temperature response mechanism for the pyrolysis of sugar cane residue using thermogravimetric analysis-Fourier transform infrared spectrometry-mass spectrometry (TG-FTIR-MS) combined with Gaussian model and two-dimensional correlation spectroscopy (2D COS). The existence and contribution of distinct peaks in TG-FTIR spectra were innovatively distinguished and quantified, and the temperature-dependent dynamics of gas amounts were determined using Gaussian deconvolution. The 2D-TG-FTIR/MS-COS results revealed for the first time that the primary sequential temperature responses of gases occurred in the order: H2O/CH4 > phenols/alkanes/aromatics/alcohols > carboxylic acids/ketones > CO2/ethers > aldehyde groups/acetaldehyde. Subtle sequential changes even occurred within the same gases during pyrolysis. The quantity dynamics and sequential responses of gases were fitted to the combined effects of the order-based, diffusion, and chemical reaction mechanisms for the component degradation. The combination of TG-FTIR-MS, Gaussian model, and 2D COS is a promising approach for the online monitoring and real-time management of biomass pyrolysis, providing favorable strategies for pyrolysis optimization, byproduct recovery, energy generation, and gas emission control in engineering and environmental applications.

Adsorption behaviors of phenanthrene and bisphenol A in purple paddy soils amended with straw-derived DOM in the West Sichuan Plain of China.

The objectives of this study were to investigate the adsorption and transfer behaviors of phenanthrene (PHE) and bisphenol A (BPA) in purple paddy soils amended with dissolved organic matter (DOM) derived from rice and canola straw in the West Sichuan Plain of China. In the pristine soil, PHE was preferentially adsorbed on both pristine clayey (L) and sandy (T) paddy soils than BPA, indicating that the retention/adsorption by soils is closely dependent on the chemical properties of organic pollutants (OPs). The noticeably higher adsorption of PHE and BPA on smaller size fraction of the soils (L2 and T2) were observed, possibly due to their higher surface areas and higher content in organic matters with higher aromaticity and hydrophobicity in this soil fraction. The DOMs derived from rice (RDOM) and canola (CDOM) straws possessed remarkable differences in E2/E3 and SUV254 measurements, which reflected that their chemical composition might be different. When CDOM was introduced in the studied soil T1, adsorption of BPA was doubled, but the augment in adsorption was much less impressive with RDOM, showing the nature of derived DOM played an important role. The study also demonstrated that in the fine fraction of clayey soil (L2), the retention of a same OP (PHE) was remarkably dropped when CDOM or RDOM was introduced, whereas in a sandy soil of the same size fraction (T2), the phenomenon was the opposite, suggesting a potential risk that, in certain types of soil, the introduction of straw derived DOMs may enhance the mobility of some OPs. The humification time of straw seems not to affect the adsorptions of OPs in most studied systems. Adsorption kinetics of PHE and BPA in the adsorption systems with derived DOMs were well fitted to the two-step first-order model with radj2 values of 0.994-0.998. Results of this study will provide further comprehensive fundamental data for risk assessment and control of organic pollutants (OPs) in farmland ecosystems.

Technical study on national mandatory guideline for deriving water quality criteria for the protection of freshwater aquatic organisms in China.

Water quality criteria are the basis for formulating environmental water quality standards, and are also an important part of environmental water protection and environmental management programs. The current study focused on a systematic discussion of the current research progress of water quality criteria theories and methodology for aquatic organisms both in China and internationally. This study also successfully pointed out key scientific issues which should be considered in the determination of water quality criteria guidelines from the following perspectives for a national strategy: the selection of pollutants; data collection and screening; species selection; water quality criteria derivation methods, and so on. For the first time, this study systematically introduced technology for the determination of water quality criteria guidelines for protecting aquatic organisms which was suitable for China's regional characteristics and national conditions. Furthermore, this study pointed out the key research directions which should be considered in the future construction of China's environmental criteria and management systems, in order to provide technical support for environmental protection and management projects.

Influence of Hardness and Dissolved Organic Carbon on the Acute Toxicity of Copper to Zebrafish (Danio rerio) at Different Life Stages.

Copper (Cu) bioavailability varies under water conditions. In the present study, the whole life of zebrafish was divided into three different life stages (larvae, juvenile and adult) based on the growth curve, then the influences of water hardness and dissolved organic carbon (DOC) concentration on the acute toxicity of zebrafish were respectively investigated. The results indicated that the life stages had significant effects on Cu toxicity. The larvae stage was less sensitive to Cu than both the juvenile and adult stages. With the increase of water hardness, the toxicity of Cu on zebrafish was decreased, a linear relationship was observed between water hardness and Cu toxicity, and the same was true for DOC concentration. The results showed that taking the 24 days juvenile zebrafish to study the water quality criteria of Cu was stable, sensitive and economical.

Three decades of changes in water environment of a large freshwater Lake and its relationship with socio-economic indicators.

Tai Lake (Ch: Taihu) has attracted international attention forcyanobacteria blooms. However, the drivers of cultural eutrophication, especially long-term socio-economic indicators have been little researched. The results of research demonstrate how socio-economic development affected quality of water and how it has been improved by anthropogenic activities. This study described variability in indicators of water quality in Tai Lakeand investigated thedrivers. Significant relationships existed between concentrations of annual mean total nitrogen (TN), total phosphorous (TP), chemical oxygen demand (COD) and biological oxygen demand (BOD), and population, per capital gross domestic production (GDP) and sewage discharge (p < 0.05). However, mechanisms causing change varied among TN, TP, COD and BOD. Before 2000, the main contributors to increases in concentrations of TN were human population, GDP and volumes of domestic sewage discharges. After 2000, discharges of industrial sewage become the primary contributor. After 1998, the regressions of annual mean TN, TP and COD on per capital GDP, population and domestic sewage discharge were reversed compared to the former period. Since 1999, an apparent inverted U-shaped relationship between environmental pollution and economic development has developed, which indicated that actions taken by governments have markedly improved quality of water in Tai Lake. The statistical relationship between BOD and per capital GDP didn't conform to the Kuznet curve. The U-shaped Kuznet curve may offer hope for the future that with significant environmental investments a high GDP can be reached and maintained without degradation of the environment, especially through appropriate management of industrial sewage discharge.

Are current Chinese national ambient air quality standards on 24-hour averages for particulate matter sufficient to protect public health?

With rapid economic development and urbanization in recent decades, China has experienced the worsening of ambient air quality. For better air quality management to protect human health, Chinese government revised national ambient air quality standards (NAAQS) for particulate matter (PM) in 2012 (GB3095-2012). To assess the effectiveness of current NAAQS for PM on public health in Chinese population, we conducted a meta-analysis on published studies examining the mortality risk of short-term exposure to PM with aerodynamic diameters less than 10 and 2.5µm (PM10 and PM2.5) in China. The reported 24-hour concentrations of PM10 and PM2.5 in studies ranged from 43.5 to 150.1µg/m3 and 37.5 to 176.7µg/m3. In the pooled excess, mortality risk estimates of short-term exposure to PM. In specific, per 10µg/m3 increase in PM10, we observed increases of 0.40% (95%CI: 0.33%, 0.47%), 0.57% (95%CI: 0.44%, 0.70%) and 0.49% (95%CI: 0.40%, 0.58%) in total, respiratory and cardiovascular mortality, per 10µg/m3 increase in PM2.5, we observed increases of 0.51% (95%CI: 0.38%, 0.63%), 0.62% (95%CI: 0.52%, 0.73%) and 0.75% (95%CI: 0.54%, 0.95%) in total, respiratory and cardiovascular mortality. Finally, we derived 125µg/m3 for PM10 and 62.5µg/m3 for PM2.5 as 24-hour recommendation values based on the pooled estimates. Our results indicated that current Chinese NAAQS for PM could be sufficient in mitigating the excess mortality risk from short-term exposure to ambient PM. However, future research on long-term exposure cohort studies in Chinese population is also essential in revising annual averages for PM in Chinese NAAQS.