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Abstract The adsorption of perfluorinated acids (PFAs) onto soils with different physicochemical properties was investigated in this study. The adsorption kinetics for all PFAs onto the soil with the highest contents of total organic carbon (TOC) and iron oxide were well described by a biexponential adsorption model, indicating that two types of binding sites characterized by a fast and a slow sorption rates were involved in the adsorption, and the time required for achieving adsorption equilibrium was <48 h for all PFAs. The adsorption isotherms were well represented by both of Freundlich equation (R 2 = 0.9547–0.9977) and/or Virial equation (R 2 = 0.8720–0.9995). The interfacial capacitances derived from the Virial isotherm were substantially low (in the range of 33.7 to 851 μF/m2) for all soils, but were not analyte-independent for all PFAs onto the same soil. The linear regression between distribution coefficient (K d) and individual soil property as well as principle component analysis were conducted for determining the dominant soil physicochemical properties affecting the adsorption of PFAs onto soil in the present study. The results indicated that the content of protein rather than of total organic carbon (TOC) was the dominant property, and then followed by anion exchange capacity (AEC) and the content of iron oxides. For the other properties, the influences of fulvic acid (FA) and aluminum oxides were PFA-dependent, while there were no effects of saccharide, humic acid (HA), specific surface area (SSA) and cation exchange capacities (CEC) on the adsorption. Graphical abstract Unlabelled Image Highlights • The sorption kinetics can be well described by a biexponential adsorption model. • The sorption isotherms are well represented by Freundlich and/or Virial equations. • The content of protein rather than TOC affects the adsorption of PFAs onto soils. • AEC and iron oxides are also dominant soil properties affecting the adsorption. [ABSTRACT FROM AUTHOR]

Abstract An integrated stochastic-fuzzy pollution assessment method (ISFPAM) for soil heavy metal was established based on geo-accumulation index (I geo), stochastic-fuzzy theory and double weight system under synthetical consideration of metal ecotoxicity and bioaccessibility. The pollution characteristics of the topsoil heavy metals (Cu, Zn, Cd, Pb and Cr) in Xiangjiang New District were evaluated by the widely-used Single factor index (SF), Nemerow index (NI), I geo , Potential ecological index (PERI), Risk assessment code (RAC) and the ISFPAM. The results of SF , NI , I geo , RI and RAC of the studied metals revealed the following orders: Cd > Zn > Cr > Cu > Pb, Cd > Zn > Pb > Cr > Cu, Cd > Cr > Cu > Zn > Pb, Cd > Cu > Pb > Cr > Zn, and Cd > Pb > Cr > Zn > Cu, respectively. The different pollution assessment methods outputted the differentiated conclusions to some extent except the judgment for Cd. Results based on ISFPAM indicated that metal pollution degrees decreased in the order of Cd (5.91, Grade 6) > Cu (2.81, Grade 3) > Pb (2.66, Grade 3) > Cr (1.58, Grade 2) > Zn (0.69, Grade 1). By detailed comparison analysis, the double weight system and stochastic-fuzzy theory made ISFPAM better resolving ability to find out priority heavy metals and areas with relatively higher enrichment, ecotoxicity and bioaccessibility under efficient parameter uncertainty control. Cd, Cu and Pb were regarded as the priority control metals, especially Cd. Simultaneously, the reliabilities of heavy metal pollution corresponding to adjacent pollution grades were quite close in some sites, which recommend recheck for avoid misleading the decision-makers. Graphical abstract Unlabelled Image Highlights • Soil metal enrichment, ecotoxicity and bioaccessibility need integrated evaluation. • Integrated stochastic-fuzzy pollution assessment method (ISFPAM) was established. • ISFPAM integrated I geo , stochastic-fuzzy theory and double weight system. • Cd, Cu and Pb was identified to be priority pollutants in topsoil from XND. • ISFPAM show better resolving ability compared with SF , NI , I geo , RI and RAC. [ABSTRACT FROM AUTHOR]

In this study, comparative analyses of highway runoff samples obtained from seventeen storm events have been conducted between the traditional water quality assessment method and biotoxicity tests, using zebrafish ( Danio rerio ) embryos and luminous bacteria ( Vibrio qinghaiensis. Q67 ) to provide useful information for ecotoxicity assessment of urban highway runoff. The study results showed that the Nemerow pollution index based on US EPA recommended Criteria Maximum Concentrations (CMC) (as traditional water quality assessment method) had no significant correlation with luminous bacteria acute toxicity test results, while significant correlation has been observed with two indicators of 72 hpf (hours post fertilization) hour hatching rate and 96 hpf abnormality rate from the toxicity test with zebrafish embryos. It is therefore concluded that the level of mixture toxicity of highway runoff could not be adequately measured by the Nemerow assessment method. Moreover, the key pollutants identified from the water quality assessment and from the biotoxicity evaluation were not consistent. For biotoxic effect evaluation of highway runoff, three indexes were found to be sensitive, i.e. 24 hpf lethality and 96 hpf abnormality of zebrafish embryos, as well as the inhibition rate for luminous bacteria Q67 . It is therefore recommended that these indexes could be incorporated into the traditional Nemerow method to provide a more reasonable evaluation of the highway runoff quality and ecotoxicity. [ABSTRACT FROM AUTHOR]

Modified eco-risk assessment method (MEAM) integrated with the hierarchical bioavailability determined by the fraction detection of Cd, Pb, Zn, Cu, Cr in road dust samples and the local population distribution derived from the local land use map, was proposed to make the hierarchical eco-risk management strategy in Xiandao District (XDD), China. The geo-accumulation index ( I geo ), the original potential eco-risk index ( E r i ) and the modified eco-risk assessment index (MEAI) were used to identify the priority pollutant. Compared with the Hunan soil background values, evaluated metal concentrations were found to different extent. The results of mean I geo , E r i and bioavailability of studied metals revealed the following orders: Cd > Pb ≈ Zn > Cu ≈ Cr, Cd > Pb > Cu > Cr > Zn and Cd > Zn > Cu ≈ Pb > Cr, respectively. Therefore, Cd was regarded as the priority pollutant. To identify the priority areas taking into account cost consideration, the hierarchical risk map based on the results of the modified eco-risk assessment index with overlay of the population density map was needed and made. The west and partly south areas of XDD were under higher eco-risk generally. Moreover, the whole XDD area was divided into 4 area categories with different management priorities based on the possibility of occurrence of eco-risk, and the hierarchical risk management strategy associated with protecting local population was suggested to facilitate allocation of funds for risk management. [ABSTRACT FROM AUTHOR]

Abstract: Soils, vegetables and rainwaters from three vegetable production bases in the Guiyang area, southwest China, were analyzed for Pb concentrations and isotope compositions to trace its sources in the vegetables and soils. Lead isotopic compositions were not distinguishable between yellow soils and calcareous soils, but distinguishable among sampling sites. The highest 207Pb/206Pb and 208Pb/206Pb ratios were found for rainwaters (0.8547–0.8593 and 2.098–2.109, respectively), and the lowest for soils (0.7173–0.8246 and 1.766–2.048, respectively). The 207Pb/206Pb and 208Pb/206Pb ratios increased in vegetables in the order of roots

Abstract: Perfluorinated acids (PFAs) have been recognized as emerging environmental pollutants because of their widespread occurrences, persistence, and bioaccumulative and toxicological effects. PFAs have been detected in aquatic environment and biota in China, but the occurrences of these chemicals have not been reported in solid matrices in China. In the present study, short- and long-chain PFAs (C2–C14) have been quantitatively determined in solid matrices including sediments, soils and sludge collected in Shanghai, China. The results indicate that sludge contains more PFAs than sediments and soils, and the total PFAs concentrations in sediments, soil and sludge are 62.5–276ngg−1, 141–237ngg−1 and 413–755ngg−1, respectively. In most cases, trifluoroacetic acid was the major PFA and accounted for 22–90% of the total PFAs. Although the levels of perfluorooctanoate (PFOA) and perfluorooctanesulfonate (PFOS) were not only lower than trifluoroacetic acid, but also lower than some short-chain PFCAs (

Urban industrial areas were being built globally, which decreased key geographical separation between agriculture and industrial areas, especially in developing countries. Now, limited studies concerned coordinated the vegetables and soil management for toxic elements (TEs) in this mixed land system. To fill this gap, an integrated environmental multi-media risk management method was explored based on laboratory analysis, health risk assessment, uncertainty control, and source apportionment. The Chinese Beihu area of Wuhan City was selected as a typical case and the measurements of Zn, Cr, Cu, Pb, As, and Cd in soil revealed that TEs pollution was slight and concentrations met the Chinese standards. Meanwhile, some vegetables exceeded corresponding standard limits. To further quantify negative health effects posed by the studied TEs both in soils and vegetables, an established fuzzy health risk assessment for farmers was employed and the results indicated that the soil exposure of As and the vegetable consumption needed the priority control. The carcinogenic risk (CR) of As in soil was [4.60E-6, 1.45E-5] and the cumulative CR (sum of CR As , CR Pb and CR Cd) in leafy vegetables was [1.08E-4, 1.38E-4], which was higher than that of the other vegetables. Preventing soil oral exposure and reducing self-grown vegetable consumption (30%–50%) were proven as effective risk interventions via uncertainty control methods. Spatially, the risk grades under maximum membership principle decreased from south to north in the Beihu area, and the south area was identified as the priority control area. Source apportionment identified four source patterns (Zn-Cr-Cu, Pb, As, and Cd) for soil, and the probable bioaccumulation mechanisms for leafy vegetables by multivariate statistical analyses. Finally, the integrated management strategies were formulated from perspectives of the risk sources, exposure pathways and the scenario. Unlabelled Image • Integrated health risk in a typical farmland near industrial complex was explored. • Priority control element and pathway were gotten via fuzzy health risk model. • Soil As exposure and vegetable consumption were important contributors of CR. • Bajifu Avenue-Green Road was priority control area by multi-spatial analysis. • Cd, Pb and As were correlated in migration patterns of soil-vegetable media. [ABSTRACT FROM AUTHOR]

Fire is an important disturbance agent in Chinese boreal forests but the long-term effects of wildfires on soil nitrogen (N) net mineralisation rates (R min) in natural versus human-assisted restorations are not well understood. In this study, we analysed upper (0–10 cm) and lower layer (10–20 cm) soil samples from natural restoration and afforestation plots in a Dahurian larch (Larix gmelinii) forest in north-eastern China 29 years after a mega fire disturbance. Our results showed that the soil inorganic N (NH 4 +-N and NO 3 −-N) pool of the upper and lower layers of the regenerated plots remained significantly lower than in unburned control plots. This suggests that the effects of a high burn severity fire on soil N availability were still significant almost 30 years after the event. Restoration type (natural restoration versus afforestation) also had significant effects on upper layer soil N availability; compared with afforestation, natural restoration was more beneficial for the accumulation of soil inorganic N and the recovery of R min after fire disturbance. Specifically, the concentration of inorganic N and the mean R min in upper layer soils in the natural restoration plots were approximately 41% greater and 3.6 times greater, respectively, than in the afforestation plots. The differences in soil N availability between the two restoration types were attributed to differences in soil water content (SWC), soil microbial biomass nitrogen (MBN), and the recovery of vegetation after the fire disturbance. Our study demonstrates that natural restoration has proved more successful than afforestation in countering soil N losses in boreal forests in China resulting from a high burn severity fire disturbance. Unlabelled Image • High burn severity fire on soil N availability were still significant almost 30 years after the event. • Compared with afforestation, natural restoration was more beneficial for the recovery of R min after fire disturbance. • Natural restoration was better than afforestation in countering post-fire soil N losses in boreal forests in China. [ABSTRACT FROM AUTHOR]

Abstract Permafrost soils store a large amount of nitrogen (N) which could be activated under the continuous climate warming. However, compared with carbon (C) stock, little is known about the size and spatial distribution of permafrost N stock. By combining measurements from 519 pedons with two machine learning models (supporting vector machine (SVM) and random forest (RF)), we estimated the size and spatial distribution of N stock across the Tibetan alpine permafrost region. We then compared these spatially-explicit N estimates with simulated N stocks from the Community Land Model (CLM). We found that N density (N amount per area) in the top three meters was 1.58 kg N m−2 (interquartile range: 1.40–1.76) across the study area, constituting a total of 1802 Tg N (interquartile range: 1605–2008), decreasing from the southeast to the northwest of the plateau. N stored below 1 m accounted for 48% of the total N stock in the top three meters. CLM4.5 significantly underestimated the N stock on the Tibetan Plateau, primarily in areas with arid/semi-arid climate. The process of biological N fixation played a key role in the underestimation of N stock prediction. Overall, our study highlights that it is imperative to improve the simulation of N processes and permafrost N stocks in land models to better predict ecological consequences induced by rapid and widespread permafrost degradation. Graphical abstract Unlabelled Image Highlights • 1802 Tg nitrogen was stored in the 0–3 m depth across the Tibetan alpine permafrost region. • CLM underestimated the nitrogen stock across the Tibetan alpine permafrost region. • Biological nitrogen fixation process played a key role in the model underestimation. [ABSTRACT FROM AUTHOR]

In order to enhance the adsorption capacity of cadmium (Cd) ion from aqueous solution, the rice straw-derived biochar (BC800) was modified by a mixture of HNO 3 and H 2 O 2 (MHH) with equal volume. Several elemental, chemical and structural characterization methods were used to determine the characteristics of biochars. Batch adsorption experiments were carried out concerning the influences of contact time, initial pH value, and initial concentration. The results indicated that the modified biochar (BCM) was more effective in removing Cd 2+ from water than BC800. For 550 mg L −1 Cd 2+ concentration solution, the adsorption capacity of 93.2 mg g −1 was observed for BCM, which was much higher than that of BC800 (69.3 mg g −1 ). The BCM had a significant increase of acidic functional groups with a rate of 101.6% and the component carboxyl, lacton and phenol groups increased by 124.1%, 29.3% and 111.3% respectively, while the specific surface area increased about 22.0%, compared with BC800. The pseudo-second-order model provided high correlation coefficients for BCM, speculating chemisorption of the Cd 2+ onto biochars. Therefore, the rice straw-based biochar treated by MHH is considered to be an efficient adsorbent for Cd 2+ removal from aqueous solution, especially for high concentrations of cadmium solution. [ABSTRACT FROM AUTHOR]

Recent studies have shown that the pyrolysis of biomass combined with clay can result in both lower cost and increase in plant yields. One of the major sources of nutrients for pasture growth, as well as fuel and building materials in Tibet is yak dung. This paper reports on the initial field testing in a pasture setting in Tibet using yak dung, biochar, and attapulgite clay/yak dung biochars produced at ratios of 10/90 and 50/50 clay to dung. We found that the treatment with attapulgite clay/yak dung (50/50) biochar resulted in the highest pasture yields and grass nutrition quality. We also measured the properties and yields of mixtures of clay/yak dung biochar used in the field trials produced at 400 °C and 500 °C to help determine a possible optimum final pyrolysis temperature and dung/clay ratio. It was observed that increasing clay content increased carbon stability, overall biochar yield, pore size, carboxyl and ketone/aldehyde functional groups, hematite and ferrous/ferric sulphate/thiosulphate concentration, surface area and magnetic moment. Decreasing clay content resulted in higher pH, CEC, N content and an enhanced ability to accept and donate electrons. The resulting properties were a complex function of both processing temperature and the percentage of clay for the biochars processed at both 400 °C and 500 °C. It is possible that the increase in yield and nutrient uptake in the field trial is related to the higher concentration of C/O functional groups, higher surface area and pore volume and higher content of Fe/O/S nanoparticles of multiple oxidation state in the 50/50 clay/dung. These properties have been found to significantly increase the abundance of beneficial microorganisms and hence improve the nutrient cycling and availability in soil. Further field trials are required to determine the optimum pyrolysis production conditions and application rate on the abundance of beneficial microorganisms, yields and nutrient quality. [ABSTRACT FROM AUTHOR]

Light scattering of aerosols depends on ambient relative humidity (RH) since hygroscopic particles absorb significant water at high RH, and this results in low visibility. This paper used custom-made parallel nephelometers (PNEPs) to measure aerosol light scattering enhancement factor ƒ(RH), and utilized data including visibility, PM 2.5 , black carbon, water-soluble ions mass concentrations and surface meteorological parameters, in conjunction with background weather conditions, to analyze a haze event in Guangzhou during 8th–15th Dec. 2013. Unfavorable weather conditions, such as high RH and low wind speed, were observed during the haze event. The hourly average mass concentration of PM 2.5 was 127 μg/m 3 , with concentration of 192.4 μg/m 3 on 9th and 196 μg/m 3 on 13th. The ƒ(RH) did not exhibit significant changes during this haze process, with value of ƒ(80%) = 1.58 ± 0.07. Although the mass fraction of water-soluble ions to PM 2.5 decreased after 12th Dec., the aerosol hygroscopicity might not have changed significantly since the mass fraction of nitrate became more dominant, which has stronger ability to take up water. The best-fitted parameterized function for ƒ(RH) is ƒ(RH) = 0.731 + 0.1375 ∗ (1 – RH / 100) − 1 + 0.00719 ∗ (1 – RH / 100) − 2 . Combining the fixed parameterization of ƒ(RH) above, the visibility was calculated with the measured light scattering and absorption coefficient of particles and gas under dry condition, as well as ambient RH. The predicted visibility range agrees well with the measurements without precipitation. Using ISORROPIA II model, the calculated aerosol liquid water content (ALWC) at ambient RH varied consistently with the PM 2.5 under lower RH, while it was more influenced by high RH. This work also show that high RH accompanied with precipitation will enhance aerosol hygroscopic growth effect, leading to further visibility degradation, even if PM 2.5 mass decreased due to precipitation. [ABSTRACT FROM AUTHOR]

Currently, Guangzhou region was facing the problem of severe air pollution. Large amount of aerosols in the polluted air dramatically attenuated solar radiation. This study investigated the vertical optical properties of aerosols and inverted the height of boundary layer in the Guangzhou region using the lidar. Simultaneously, evaluated the impact of different types of clouds on aerosol radiation effects using the SBDART. The results showed that the height of the boundary layer and the surface visibility changed consistently, the average height of the boundary layer on the hazy days was only 61% of that on clear days. At the height of 2 km or lower, the aerosol extinction coefficient profile distribution decreased linearly along with height on clear days, but the haze days saw an exponential decrease. When there was haze, the changing of heating rate of atmosphere caused by the aerosol decreased from 3.72 K/d to 0.9 K/d below the height of 2 km, and the attenuation of net radiation flux at the ground surface was 97.7 W/m 2 , and the attenuation amplitude was 11.4%; when there were high clouds, the attenuation was 125.2 W/m 2 and the attenuation amplitude was 14.6%; where there were medium cloud, the attenuation was 286.4 W/m 2 and the attenuation amplitude was 33.4%. Aerosol affected mainly shortwave radiation, and affected long wave radiation very slightly. [ABSTRACT FROM AUTHOR]

The total count number concentration of particles from 10 to 1000 nm, particle size distribution, and PM 2.5 (aerodynamic diameter ≤ 2.5 μm) mass concentration were measured on a parking apron next to the runway at Tianjin International Airport in China. The data were collected 250, 270, 300, 350, and 400 m from the runway. Wind direction and wind speed played important roles in determining the characteristics of the atmospheric particles. An inverted U-shaped relationship was observed between the measured particle number concentration and wind speed, with an average peak concentration of 2.2 × 10 5 particles/cm 3 at wind speeds of approximately 4–5 m/s. The atmospheric particle number concentration was affected mainly by aircraft takeoffs and landings, and the PM 2.5 mass concentration was affected mainly by the relative humidity (RH) of the atmosphere. Ultrafine particles (UFPs, diameter < 100 nm), with the highest number concentration at a particle size of approximately 16 nm, dominated the measured particle size distributions. The calculated particle emission index values for aircraft takeoff and landing were nearly the same, with mean values of 7.5 × 10 15 particles/(kg fuel) and 7.6 × 10 15 particles/(kg fuel), respectively. The particle emission rate for one aircraft during takeoff is two orders of magnitude higher than for all gasoline-powered passenger vehicles in Tianjin combined. The particle number concentrations remained much higher than the background concentrations even beyond 400 m from the runway. [ABSTRACT FROM AUTHOR]

Abstract This paper analyzes observation data in the Pearl River Delta (PRD) region from 2012 to 2013, and explores the impact of typhoon periphery on high ozone and high aerosol pollution episodes (double high episodes). Observation analysis show that severe tropical storms to severe typhoons are mainly located in the range of 10°N-30°N, 116°E-135°E when double high episodes occur. Meanwhile, obvious high temperature, low humidity, low wind speed, high actinic flux, high aerosol optical depth (AOD), and high single scattering albedo (SSA) can be observed in double high episodes. The diurnal cycle of the PM 2.5 is significant in double high episodes, and the average peak concentration in the afternoon can exceed 90 μg/m3. The diurnal cycle of PM 2.5 in non–double high episodes is not significant, and the average value is about 34–39 μg/m3. The ozone peak concentration in double high episodes is 81–103 ppbv, which is about 27–40 ppbv higher than that of non–double high episodes. High correlation can be found between the aerosol and ozone diurnal cycles in double high episodes, and r2 reaches 0.76. In double high episodes, black carbon, nitrate, and sea salt decrease while sulfate, ammonium, secondary organic carbon, and total PM 2.5 significantly increase in the afternoon. The growth of PM 2.5 in double high episodes is mainly contributed by scattered fine particles from photochemical processes and transmission. The mechanisms that control the double high episodes in the PRD are described below. Ozone and aerosol begin to accumulate under unfavorable meteorological conditions. Via local photochemical processes and external transport, the scattered aerosol increases and leads to an increase in multiple scattering and actinic radiation, which is in turn more favorable for photochemical reaction and further increases the ozone concentration. Meanwhile, high oxidizability promotes the formation of scattered aerosol, creating positive feedback. In addition, the scattered aerosol increases backscattering, which increases the photolysis rate and ozone concentration in the middle and upper boundary layer. Meanwhile, downdraft and turbulence transports high-concentration ozone to the ground. Graphical abstract Unlabelled Image Highlights • The impact of typhoon periphery on high ozone and high aerosol pollution episodes (double high episodes) are analyzed. • The double high episodes were characterized by high temperature, low humidity, low wind speed, high UVA, and high SSA. • In double high episodes, BC, NO 3 -, and Na+ decrease as SO 4 2-, NH 4 +, SOC, and PM 2.5 significantly increase in the afternoon. • The growth of PM 2.5 in double high episodes is mainly contributed by scattering fine particles. • Under the control of typhoon periphery, the actinic flux is the key factor causing double high episodes. [ABSTRACT FROM AUTHOR]

Abstract Microcystis aeruginosa (M. aeruginosa) commonly blooms in summer while Cyclotella meneghiniana (C. meneghiniana) outbreaks in fall in water reservoirs of Southeast China. Pre-oxidation has been demonstrated to enhance the algae removal from chemical coagulation processes. However, excessive dosage of pre-oxidant can increase the disinfection by-products formation potential (DBPsFP). Additionally, the DBPs formation mechanisms from algae during the pre-oxidation-coagulation-chlorination processes have not well elucidated. In this study, the objectives were to investigate the trichloromethane (TCM) formation, the changes of water quality indexes, and the morphology changes of algal cells from M. aeruginosa or C. meneghiniana contaminated water during potassium permanganate (KMnO 4) or chlorine (Cl 2) pre-oxidation-coagulation-chlorination disinfection. The results showed that the TCM yield for two algal species decreased with the dosage increase of KMnO 4 pre-oxidation, but increased with the dosage increase of pre-chlorination. Therefore, the 2.0 mg/L KMnO 4 or 0.5 mg/L Cl 2 was proposed as the optimal dosage for preventing both M. aeruginosa blooms in summer and for C. meneghiniana outbreaks in fall. M. aeruginosa exhibited a slightly higher TCM yield than C. meneghiniana in these treatment processes. Based on the release of potassium (K) ion and SEM analysis, KMnO 4 had less damage on cell integrity than Cl 2 at the dosage ≤2.0 mg/L. In addition, C. meneghiniana was easier to be disrupted by both pre-oxidants than M. aeruginosa , combining with subsequent coagulation led to different value of dissolved organic carbon (DOC), UV–visible absorbance (UV 254) and turbidity. Graphical abstract Unlabelled Image Highlights • M. aeruginosa exhibited a higher TCM formation than C. meneghiniana. • The variation of the water quality indexes was related to TCM formation. • Optimized pre-oxidation is beneficial to the removal of TCM precursors. [ABSTRACT FROM AUTHOR]

Abstract Dongting Lake is the second largest freshwater lake in China and is one of the globally important wintering sites for migratory waterbirds in the East Asian–Australasian Flyway. Crucial sites and environmental variables for wintering migratory waterbirds are of great concern in the Dongting Lake wetlands. In this research, based on annual (2003/2004–2016/2017) waterbird and habitat census data, we recognized the crucial sites for waterbirds during wintering seasons by comparing the difference of waterbird populations at the community, foraging guild and species levels in different natural wetlands within East Dongting Lake, and then identified the crucial environmental variables affecting waterbird distributions by analyzing the relationship between waterbird populations and the environmental variables, including vegetation area, mudflat area, water area with the depth of 0–20 cm, water area with the depth of 20–50 cm, water area with the depth of 50–100 cm, water area with the depth >100 cm, growth status of vegetation (Min, Mean and Max NDVI), and the human disturbance. Results indicated that five natural wetlands, i.e., Daxiaoxi, Chunfeng, Baihu lakes, Dingzi dyke and Tanjiaweizi, were recognized as the crucial wintering sites for migratory waterbirds in the East Dongting Lake. Among the ten selected environmental variables, water areas with the depth of 0–20 cm, 20–50 cm and >100 cm, human disturbance, Min and Mean NDVIs were identified as the crucial environmental variables overall. Waterbirds at different levels exhibited significant linear relationship with certain environmental variables, with the exception of Bean goose and Lesser White-fronted goose at the species level, which showed Gaussian distribution with changes in mean NDVI. The crucial environmental variables appeared to be foraging guild- and species-specific. These findings provide significant information for managers to understand the differences of wetlands and waterbird populations within East Dongting Lake, and to make more targeted conservation efforts. Graphical abstract Unlabelled Image Highlights • Waterbird populations were analyzed at community, foraging guild and species levels. • Five crucial wintering sites were verified in East Dongting Lake. • Six crucial environmental variables were identified in East Dongting Lake. • Crucial sites and environmental variables were foraging guild-specific. • Crucial sites and environmental variables were species-specific. [ABSTRACT FROM AUTHOR]

Abstract Exposure to arsenic in the environment is hazardous to biota. Three types of sediments from a shallow, high arsenic aquifer were collected from Jianghan Plain, Central China to investigate interactions between indigenous bacterial activity and arsenic adsorption/desorption. For the same level of bacterial activity, the As(III) or As(V) adsorption rate in sediments decreased from clay loam to loamy sand to silty sand. However, the arsenic desorption rate from these sediments followed the reverse sequence. For the same arsenic speciation and content, bacterial activity decreased from clay loam to loamy sand to silty sand. Overall, arsenic adsorption/desorption rates were related to both bacterial activity and sediment texture. The bacteria present could reduce As(V) to As(III), thereby favoring its release from sediment into solution and increasing the ratio of As(III) to total arsenic. These results indicate indigenous bacteria strongly affect the adsorption/desorption and oxidation-reduction of arsenic, and are actively involved in the dynamic equilibrium of arsenic between sediment and groundwater in this shallow aquifer. Graphical abstract Unlabelled Image Highlights • Jianghan Plain is a recently discovered high arsenic area in China. • Bacteria affect arsenic adsorption/desorption and oxidation/reduction. • Bacteria establish an arsenic dynamic equilibrium between sediment and groundwater. • Arsenic adsorption/desorption is related to bacterial activity and sediment texture. • Bacterial activity can denote the extent of arsenic adsorption/desorption. [ABSTRACT FROM AUTHOR]

Both the effects of aerosol hygroscopicity and mixing state on aerosol optical properties were analyzed using ground-based measurements and a Mie model in this study. The sized-resolved particle hygroscopic growth factor at RH = 90% ( Gf (90%)) and the enhancement factor for the scattering coefficients ( f (RH) sp ) were measured by a self-constructed Hygroscopic Tandem Differential Mobility Analyzer (H-TDMA) and two nephelometers in parallel (PNEPs) respectively from 22nd February to 18th March 2014 in the Pearl River Delta, China. In addition, the particle number size distribution (PNSD) and BC mass concentration (M BC ) were measured simultaneously. During the observation period, the f (RH) sp increased sharply along with increasing RH (40%–85%) and the value of f (80%) sp was 1.77 ± 0.18. The mean Gf (90%) for all particles are 1.44 (80 nm), 1.48 (110 nm), 1.52 (150 nm) and 1.55 (200 nm), and the mean Gf (90%) for more-hygroscopic particles are 1.58 (80 nm), 1.63 (110 nm), 1.66 (150 nm) and 1.67 (200 nm) respectively. Based on Gf , PNSD and M BC , the enhancement factor of the aerosol optical properties (extinction ( f (RH) ep ), scattering ( f (RH) sp ), backscattering ( f (RH) hbsp ), absorption ( f (RH) absp ), and hemispheric backscatter fraction ( f (RH) hbsp )) were calculated under three aerosol mixing state assumptions. The results show that the calculated f (80%) sp values agreed well with the ones measured by PNEPs, illustrating that the Gf size distribution fittings are reasonable. The f (RH) ep , f (RH) sp and f (RH) hbsp increased along with increasing RH for three mixtures, while f (RH) HBF decreased. The f (RH) absp increased for the homogenously internal mixture, but remained stable for the external mixture. For the core-shell mixture, the f (RH) absp increased from RH = 0 to 75% and then decreased, due to a decrease of light entering the BC core. The enhancement factor of aerosol direct radiative forcing ( f (RH) Fr ) increased sharply as the RH elevated for the external mixing state. However, f (RH) Fr increased or decreased along with the elevated RH for the homogenously internal mixture and the core-shell mixture depending on initial value of the aerosol direct radiative forcing ( ∆F r ) in a dry condition. [ABSTRACT FROM AUTHOR]

Ocean acidification (OA) and pathogenic diseases pose a considerable threat to key species of marine ecosystem. However, few studies have investigated the combined impact of reduced seawater pH and pathogen challenge on the immune responses of marine invertebrates. In this study, Pacific oysters, Crassostrea gigas , were exposed to OA (~2000 ppm) for 28 days and then challenged with Vibrio splendidus for another 72 h. Hemocyte parameters showed that V. splendidus infection exacerbated the impaired oyster immune responses under OA exposure. An iTRAQ-based quantitative proteomic analysis revealed that C. gigas responded differently to OA stress and V. splendidus challenge, alone or in combination. Generally, OA appears to act via a generalized stress response by causing oxidative stress, which could lead to cellular injury and cause disruption to the cytoskeleton, protein turnover, immune responses and energy metabolism. V. splendidus challenge in oysters could suppress the immune system directly and lead to a disturbed cytoskeleton structure, increased protein turnover and energy metabolism suppression, without causing oxidative stress. The combined OA- and V. splendidus -treated oysters ultimately presented a similar, but stronger proteomic response pattern compared with OA treatment alone. Overall, the impaired oyster immune functions caused by OA exposure may have increased the risk of V. splendidus infection. These results have important implications for the impact of OA on disease outbreaks in marine invertebrates, which would have significant economic and ecological repercussions. [ABSTRACT FROM AUTHOR]

Concentrations and distribution characteristics of organophosphate esters (OPEs) in surface sediment samples were analyzed and discussed for the first time in the open Bohai Sea (BS) and Yellow Sea (YS). Three halogenated OPEs [tris-(2-chloroethyl) phosphate (TCEP), tris-(1-chloro-2-propyl) phosphate (TCPP), and tris-(1,3-dichloro-2-propyl) phosphate (TDCPP)] and five non-halogenated OPEs [tri-isobutyl phosphate (T i BP), tri- n -butyl phosphate (T n BP), tripentyl phosphate (TP e P), triphenyl phosphate (TP h P) and tris-(2-ethylhexyl) phosphate (TEHP)] were detected in this region. The concentrations of eight OPEs in total (Σ 8 OPEs) ranged from 83 to 4552 pg g − 1 dry weight (dw). The halogenated OPEs showed higher abundances than the non-halogenated ones did, with TCEP, TCPP, and TEHP the main compounds. Generally, concentrations of OPEs in the BS were higher than those in the YS. Riverine input (mainly the Changjiang Diluted Water (CDW)) and deposition effect in the mud areas might have influenced the spatial distributions of OPEs. Correlation between OPE concentrations and total organic carbon (TOC) indicated TOC was an effective indicator for the distribution of OPEs. Inventory analysis of OPEs implied that sea sediment might not be the major reservoir of these compounds. [ABSTRACT FROM AUTHOR]

Aerosol liquid water content (ALWC) has an important effect on atmospheric visibility as well as heterogeneous chemical reactions. In this paper, we used the data size-resolved particle hygroscopic growth factor, and particle number size distribution (PNSD) obtained from H-TDMA and SMPS to compute ALWC at the Guangzhou Panyu site from the winter of 2014 and the spring of 2015. The corresponding results were relatively consistent with the trend for ALWC ISO calculated from the ISORROPIA II thermodynamic equilibrium model based on the measurement of aerosol water-soluble ionic compositions obtained from MARGA, with a linear fit yielding an R 2 value of 0.76. The fact that ALWC HTDMA was somewhat higher than ALWC ISO at low RH values was at least partially attributable to the fact that effects resulting from organic matter hygroscopicity were not taken into account when computing ALWC ISO . In sensitivity testing, ambient relative humidity, PNSD and particle hygroscopicity were all found to affect ALWC, in that order. Particles of different modes made different contributions to ALWC with the contributions of nuclear, Aitken, accumulation and coarse modes assessed at < 1%, 3%, 85% and 12%, respectively, indicating that the contribution of accumulation mode particles to ALWC dominated among all the aerosol particle modes. During clean processes, decreases in relative humidity and PM 2.5 both resulted in a decrease in ALWC. During the pollution processes, calm winds caused local particle accumulation, with ALWC increasing as RH increased. Intraday trends in ALWC and relative humidity were consistent, with minimum mean values observed in the afternoon due to low ambient relative humidity inhibiting an increase in ALWC. However, diurnal variation of aerosol hygroscopicity and ALWC tended to be somewhat anti-correlated, indicating that diurnal changes in aerosol hygroscopicity are not a primary factor resulting in ambient AWLC changes. [ABSTRACT FROM AUTHOR]

Combustion of pelletized municipal sewage sludge (MSS) can generate pestilent byproducts: fly ash and slag. Comparisons of heavy metal sequential extraction results among MSS, fly ash and slag showed that after combustion, the bioavailable heavy metal fractions (acid soluble/exchangeable, reducible and oxidizable fractions) were mostly transformed into the very stable heavy metal fractions (residual fractions). On the other hand, the results of toxicity characteristic leaching procedure (TCLP), diethylenetriamine pentaacetic acid and HCl extraction (phyto-accessibility assessment) demonstrated that the mobility and toxicity of heavy metals were greatly reduced. The direct and long-term bioavailability and eco-toxicity of heavy metals in fly ash and slag were relieved, which implied that combustion of pelletized MSS could be a promising and completely safe disposal technology for MSS treatment. [ABSTRACT FROM AUTHOR]

Disinfection is an indispensable process to inactivate pathogens, while unexpected disinfection by-products (DBPs) would also be formed between the reaction of residual disinfectants and microorganisms in the water distribution system (WDS). However, there are few studies referring to the formation of DBPs and DBPs-associated toxicity under various disinfection methods based on microorganisms in the real WDS. In addition, the main contributors of bacterial communities or components that generate DBPs are unclear. In this study, the formation of trihalomethanes (THMs), halo-acetic acids (HAAs), nitrosamines (NAs) from culturable microorganisms in pipeline network by ozonation(O 3), chlorination (Cl 2), chloramination (NH 2 Cl) and joint disinfection methods were compared, meanwhile, their calculated toxicities under different oxidation scenarios were also discussed. Moreover, 16S ribosomal ribonucleic acid (rRNA) gene sequencing was used to identify the main microbial communities. The results demonstrated that THMs and HAAs increased with increasing disinfectant dosages, while the quantity of NAs (mainly nitroso dimethylamine (NDMA)) was not significantly related to disinfectant dosages for each disinfection strategy. Chloroform (TCM) and dichloroacetic acid (DCAA) were the dominant THMs and HAAs species, respectively. NDMA existed in the samples before disinfections, which may due to the metabolic activity of microorganisms. Pre-O 3 increased THMs formation during subsequent Cl 2 and NH 2 Cl treatment. However, pre-O 3 effectively reduced HAAs produced by subsequent chlorination. O 3 /Cl 2 disinfection had the highest DBPs formation potential (DBPFP) (883.6 nM), while its calculated toxicity was similar to that in Cl 2 disinfection treatment. Pseudomonas was the most abundant bacterial genus in biofilm of WDS pipeline. This study can aid in an optimal disinfection strategy for water treatment plants to reduce the toxicity of DBPs caused by biomass in pipelines and ensure water quality safety. Unlabelled Image • Pre-O 3 increased THMs formation during subsequent Cl 2 and NH 2 Cl treatment. • Pre-O 3 effectively reduced HAAs produced by subsequent chorination. • Due to the metabolic activity of biomass, NDMA existed before disinfections. • The calculated toxicity was the highest in O 3 but the lowest in Cl 2. • Pseudomonas was the most abundant bacterial genus in biofilm on WDS pipeline. [ABSTRACT FROM AUTHOR]