2019 Vol. 38, No. 5
Caffeine is a stimulant of central nervous system derived from tea and coffee drinks. Investigating on its consumption is important for monitoring the population health and the size of the caffeine consumer market. In this study, a sewerage epidemiology method was used to investigate caffeine consumption in seven major cities in Liaoning Province. The mean concentration of caffeine in influent wastewater samples was determined to be 2.77±1.55 μg·L-1 using gas chromatography-mass spectrometry. The per capita consumption of caffeine in Liaoning Province was estimated to be 39.5 mg·d-1 based on the combined data of the influent flow rate of the wastewater treatment plant, the human metabolic data of caffeine, and the served population of the wastewater treatment plant. Monte Carlo method was used to estimate the consumption, and the results showed that the per capita caffeine consumption of urban residents in Liaoning Province was 41.2 mg·d-1(95% CI:22.9-74.4 mg·d-1). In 2017, the urban population of Liaoning Province was calculated to be 29.5 million. The total caffeine consumption of urban residents in Liaoning Province was 1210 kg·d-1(95% CI:680-2190 kg·d-1). Sensitivity analysis shows that caffeine's human metabolic factor is the parameter that contributes most to the uncertainty in the process of back-calculation. This study provides a rapid and timely method for the investigation of caffeine consumption.
A Schiff base from the condensation of 5-nitrosalicylaldehyde with N-phenyl-o-phenylenediamine and its Cu(Ⅱ)-complex were synthesized by solution method. The structure and chemical composition of the Schiff base and its Cu(Ⅱ)-complex were characterized with various techniques including elemental analysis (EA), UV-Vis absorption spectroscopy (UV), Fourier-transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). Catalytic degradation of triclosan (TCS) by hydrogen peroxide in the presence of the Cu(Ⅱ)-complex was evaluated under various conditions. The results revealed that the Cu(Ⅱ)-complex showed good catalytic performance on the degradation of TCS. The TCS removal efficiency increased with the increase of Cu(Ⅱ)-complex concentration, H2O2 concentration, and reaction temperature. At optimal reaction conditions of 0.05 mmol·L-1 Cu(Ⅱ)-complex0, 1.0 mmol·L-1 H2O2, 0.02 mmol·L-1 TCS, pH 7.6, and at temperature 50℃, TCS was removed by 80.5% within 30 min. The dominant reactive oxygen species (ROS) involved in the reaction was identified as ·OH radical using 2-propanol, sodium azide, and nitro blue tetrazolium as scavengers for ·OH, 1O2 and O2-, respectively. The results suggested that the Cu(Ⅱ)-complex is a promising catalyst for catalyzing oxidative degradation of TCS by H2O2 in aqueous solution under neutral condition.
Iron-carbon microelectrolysis was employed to degrade two synthetic compounds sulfamethoxazole and carbamazepine. The effects of iron carbon mass ratio, reaction time, pH, iron dosing quantity and other factors on the degradation rate of sulfamethoxazole and carbamazepine were investigated. The results showed that sulfamethoxazole was completely removed within 60 minutes when pH=1,Fe:C=1:1,Fe=80 g·L-1. The highest degradation efficiency of carbamazepine (90%) occurred at 60 minutes with pH=1, Fe:C=1:4,Fe=80 g·L-1. Sulfamethoxazole and carbamazepine undergone redox reactions and the nitrogen was reduced to ammonia nitrogen. The degradation of sulfamethoxazole and carbamazepine was in accordance with pseudo first order reaction kinetics.
SnO2-Sb/MWCNTs composites were prepared through sol-gel method, and were hot-pressed onto stainless steel mesh to form a 2-D electrode. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and electrochemical measurements were used to investigate the morphology, phase composition and electrochemical performance. It was demonstrated that SnSbOx was successfully doped onto MWCNTs. Oxygen evolution potential, electrocatalytic activity and stability were substantially improved. Enhanced hydroxyl radical production capability was tested by fluorescence spectrometry method. Service life test was conducted with five cycles of electrochemical degradation of ceftazidime. The results demonstrated that SnO2-Sb/MWCNTs electrode could reach a 90% removal rate after 60 min under a current density of 2 mA·cm-2.
This paper investigated the effects of potassium permanganate/sodium bisulfite (PM/BS) on the degradation of pesticide metribuzin (MET) under different pH conditions, and the changes and toxicity evaluation of disinfection by-products (DBPs) during oxidation and subsequent chlorination. At the same time, potassium permanganate (PM) was used as a control group. Results showed that PM/BS pre-oxidation increased the degradation efficiency of MET compared with PM pre-oxidation. In the two pre-oxidation processes, the degradation efficiency of MET was the largest under acidic conditions and decreased with the increase of pH, while the formation potential and toxicity of DBPs increased with the increase of pH. It is worth noting that the degradation efficiency under alkaline conditions was low, and a large amount of dichloroacetonitrile was formed, which leads to a large increase in the formation potential and toxicity of DBPs. The reasons for this phenomenon were discussed in detail. Finally, it was concluded that the degradation of pollutants in the PM/BS system needs to be controlled under acidic conditions, which can increase the degradation efficiency and reduce the toxicity of DBPs.
Hydrated electron (eaq-)-based reduction processes are promising for degrading organic pollutants in water engineering systems. The second order rate constant (keaq-) of eaq- with organic compounds is an important parameter for evaluating the removal efficiency of organic pollutants in advanced reduction proless. However, experimental determination of keaq-seems fairly unrealistic because of the large number of organic chemicals. Thus, it is necessary to develop an effective method to predict keaq-. In this study, the experimental keaq-values of 94 aromatic compounds were collected. The quantitative structure-activity relationship (QSAR) models for predicting keaq-were constructed by stepwise multiple linear regression (MLR) and support vector machines (SVM) methods, respectively. Both two models had satisfactory goodness-of-fit (Radj,tr2 > 0.800), robustness (QLOO2=0.782) and good predictability (Qext2> 0.790). Mechanistic analysis reveald that the energy of the lowest unoccupied molecular orbital (ELUMO) and the spectral mean absolute deviation from augmented edge adjacency mat weighted by dipole moment (SpMAD_AEA(dm)) were the most important descriptors. Additionally, keaq- was found to be related to the bond order and polarizability of the compounds. The meta-analysis showed that aromatic compounds with electron-withdrawing functional groups tended to have higher reactivity with eaq- than those containing electron-donating groups.
Traditional health risk assessment methods do not really reflect the heavy metals risk, because the interactions among heavy metals and their effects on target organs are not taken into account. To solve this problem, the traditional evaluation method was modified by the target organ toxicity dose (TTD) approach of ATSDR and the weight of evidence (WOE) approach of EPA. This study evaluated the non-carcinogenic health risks of heavy metals in solidified fly ash from a municipal solid waste incinerator in South China through the TTD and WOE methods, and the results were compared with that of the traditional method. The results showed that the Hazard Index (HI) values of the traditional health risk method was 0.2084, whereas the value of TTD modified HI and WOE modified HI was 0.5165 and 0.6717. The value of health risks by the TTD and WOE method were higher than that of the traditional method. It could reflect the factual health risk better for male workers in MSWI.
Extracellular polymeric substances (EPS) self-produced by green algae influence its bio-purification of inorganic arsenic. Chlorella pyrenoidosa was chosen as the representative EPS-producing green algae to investigate bioaccumulative characteristics of inorganic arsenic and EPS effects, based on a 24 h short-term simulation exposure experiment to As(Ⅲ) and As(V). Results showed that the intracellular arsenic accumulation rate increased with the exposure concentration of As(Ⅲ) and As(V), and they matched well the Michaelis-Menten enzymatic reaction kinetic equation in the range of 0-40 mg·L-1. Increasing inorganic arsenic promoted the production of algae EPS, especially soluble EPS, and a significantly linear relationship was observed between EPS secretion rate and intracellular arsenic accumulation rate (R2 > 0.900). Compared to EPS-removed live cells, the maximum extracellular accumulation capacity of the intact algae cells for As(Ⅲ) and As(V) increased by 30.6% and 14.2%, while the maximum intracellular accumulation capacity reduced by 49.0% and 31.0%, respectively. The micro-interfacial interactions of algal EPS with inorganic arsenic impacts arsenic bioremediation.
To understand accumulation, depuration, and transfer of dioxin-like compounds from feed to fish, the levels of 3,3',4,4'5-pentachlorobiphenyl (PCB126) in liver, muscle, kidney and blood of oreochromis nilotica, exposured to the diet with contaminant were determined. Kinetic parameters were calculated by using a pharmacokinetic model to study application of the model in predicting concentrations for contaminants. Results showed that the predicted values of contents for PCB126 in muscle and the half life of PCB126 in tissues were in good agreement with the measured values. Fugacity was applied to indicate transfer of PCB126 in tissues. Results suggested that liver was an important organ for accumulation and transfer of PCB126 which stimulated the growth of liver to elevate capacity of bioaccumulation. The transfer of PCB126 in muscle was unaffected by exposure time, and the peak PCB126 concentration was delayed generating from the import of PCB126 from other tissues to muscle during depuration.
Phthalic acid esters (PAEs), classified as an important group of industrial additives, can be used as plasticizers and softeners in the plastics industry, also applied as flavoring agents and film-forming agents in the chemical industry. With the properties as one of persistent organic pollutants of environmental hormones, PAEs induce negative effects on biological reproductive development, metabolism. Consequently this effect can endanger the ecosystem along food chain. This paper summarizes the international research progress in the aspects of PAEs' different exposure trend and intends to provide some reference for more further studies of the effects of PAEs on ecological environment.
A rapid and quantitative method based on headspace-solid phase micro-extraction (HS-SPME) with gas chromatography-mass spectrometry(GC-MS) was used to analyze the volatile organic odorous substances(VOCs)produced in sewage wastewater. The studied VOCs, which mainly include OVOCs, VSCs and BTEX, are major odorous pollutants. According to the properties of different odorous substances, the conditions of the HS-SPME, such as extraction fiber coating, extraction temperature, extraction time, salting out effect and resolution time, were optimized experimentally.The results show that DVB/CAR/PDMS (50/30 μm) has the highest extraction selectivity for the VOCs.The optimal condition was obtained as follows:20% (W/V) NaCl was added to the water sample, and the VOCs were extracted under incubation conditions at 65℃ for 30 min,and then analyzed for 180 s.The VOCs were found to be linear in the validated range with correction coefficients(R2) better than 0.98.The detection limits of the method were all less than 4-55 ng·L-1, while the relative standard deviations(RSD) were in a range of 9.8%-15.5%, the average recovery rate was 79.1%-108.6%. This method was used to detect different sewage wastewaters. The experimental results show that the method can simultaneously identify multiple trace odor substances in different sewage wastewaters.
A high performance liquid chromatography-electrospray ionization-mass spectrometry (HPLC-ESI-MS) method was developed for the determination of the seleno amino acids in earthworms. Selenomethione (SeMet) and methylselenocysteine (MeSeCyS) were extracted from earthworms by oscillating and ultrasound assisted enzymatic hydrolysis. These two seleno amino acids were isolated and determined by HPLC-ESI-MS using external standard method. Then the positive ion and multiple reaction monitoring (MRM) was applied and operated. The results indicated that both SeMet and MeSeCys had a good calibration curve in a range of 4-600 ng·mL-1, with R2 > 0.9999. The method detection limits of SeMet and MeSeCys were 0.49 μg·g-1 and 0.67 μg·g-1, respectively. The recoveries of standard addition were 81.1%-112.4%, with RSD values less than 3.1%. This detection method was preferred over others as it had eliminated the need for more cumbersome procedures, such as pre-column derivatization and increased the opposite direction gas.
A rapid method for the screening and determination of 26 pesticides was developed based on solid phase extraction and ultrahigh performance liquid chromatography (UHPLC)-quadrupole time-of-flight mass spectrometry (Q-TOF/MS). Initially, a database containing the accurate mass, retention time and the MS/MS spectra of the 26 pesticides was established. Based on the above database, the qualitative identifications of the 26 pesticides in surface water were accomplished without comparison with the standard substances. The target compounds in real water samples were first enriched by solid phase extraction cartridges and then eluted out of the cartridges using acetonitrile/isopropanol solution (1:1). The resultant samples were then loaded onto a reversed phase C18 column and subjected to separation under gradient elution using 0.1% formic acid in methanol and 0.1% formic acid in water (with 10 mmol·L-1 ammonium acetate) as binary mobile phases, further detected using UHPLC-Q-TOF/MS, and quantificated by external standard method. It was demonstrated that in the studied concentration range, all 26 pesticides exhibited very good linearity with the linear correlation coefficients all higher than 0.994. The recoveries ranged from 67.74% to 112.3% with the relative standard deviations (RSD) between 0.45% and 12.2%.
Arsenic is a toxic metalloid element. Severe pollution of arsenic has been found in soil and groundwater of many industrial sites. This paper investigated the enhancing effect and mechanism of 20 mT Weak Magnetic Field (WMF) on arsenic removal by Zero-valent iron (ZVI). Results showed that the enhancing effect of WMF on arsenic removal was significant under all pH conditions (5-9). Especially when initial pH was 7, the rate of reaction increased by 443% (from 0.21 s-1 to 1.14 s-1) and removal efficiency increased by 189% (from 30.9% to 89.1%) in the presence of WMF. Moreover, the enhancing effect of WMF was more significant by ZVI of smaller particle size (5-9 μm). In addition, we found that in the presence of WMF, more oxygen participated in the reaction, which promoted the corrosion of ZVI and generated more iron oxides and hydroxides. These substances accelerated the adsorption and precipitation of arsenic. The results of SEM and XPS supported this mechanism. Therefore, as an effective method to promote arsenic removal by ZVI, WMF is energy-free, chemical-free, environmental-friendly and has a prospective future.
Non-ferrous metal smelting slag has the characteristics of complex composition and environmental hazard. It is the staple industrial solid wastes, and its comprehensive utilization is a difficult task in solid waste treatment and disposal. In this paper, the characteristics of typical copper smelting slag, red mud, magnesium smelting slag, lead zinc smelting slag and lithium slag in non-ferrous metal smelting slag are reviewed, and the feasibility of desulfurization and denitrification of non-ferrous metal smelting slag is analyzed. The process flow method of magnesium smelting slag wet desulfurization and red mud desulfurization and denitrification is summaried, and the application of other smelting slag dry and wet desulfurization and denitration is also listed. Finally, the prospect of comprehensive utilization of non-ferrous metal smelting slag is prospected.
With respect to the blockage of equipment and pipelines caused by the coking reaction of organic compounds during the preheating stage of the supercritical water oxidation system for textile pollutants, the hydrothermal reaction of Reactive Orange 7, one of the typical textile pollutants, was investigated in the sub/supercritical water. The influence of reaction parameters on the conversion of tar was examined. And it is suggested that the tar yield reached maximum at the reaction temperature of 350℃. Besides, the partial oxidation and the addition of NaOH could facilitate the gasification reaction pathway and inhibit the generation of tar effectively. Finally, the increment of the material concentration would promote the conversion of dye compound into tar during the hydrothermal process, which was disadvantageous to the system operation. The research results could provide the theoretical foundation for the optimization of the supercritical water oxidation system to treat the textile pollutants.
Composite nanofiber membranes of thermoplastic urethane/polyacrylonitrile (TPU/PAN) were prepared by an improved electrospinning technique, and the influence of different composite modes and layers on the microstructure of the composite nanaofiber membrane was investigated. Meanwhile, the influence of surface density of nanofiber membrane on the filtration efficiency and filtration pressure drop was also explored in the air filtration test. In order to obtain nanofiber membranes with the high efficiency and low resistance for air filtration, the effect of composite modes and layers of TPU (crude fiber) and PAN (fine fiber) on air filtration were demonstrated. The results show that the optimal combination mode between TPU and PAN is Mixed/PAN, and the optimal number of layers is Mixed/PAN/Mixed/PAN. The best air filtration was achieved when the surface density was 1.31 g·m-2, and the filtration efficiency reached 97.34%, the filtration pressure drop was only 98.13 Pa, and the quality factor was 0.038 pa-1. This indicates that the higher efficiency and the lower resistance can be achieved by combination of composite modes and layers. At the same time, the pore diameter of the nanofiber membrane under the optimum conditions was tested by bubble pressure method, and the average value was 2.26 μm.
Cd-contaminated soil has seriously threatened the health of human and safety of ecological environment. Stabilization is an important method in remediating Cd-contaminated soil due to its high efficiency, rapidity and low cost. In this study, modified nano-silica (GSN) was used as a stabilization agent to remediate Cd-contaminated agricultural soil under both laboratory and field conditions. The influence of GSN addition on DTPA-extractable Cd content, distribution of Cd fraction and Cd content in wheat grain were analyzed. Under laboratory conditions, GSN addition reduced the content of DTPA-extractable Cd in the soil and the highest stabilization efficiency reached to 91.77%. The exchangeable and carbonate bounded fractions Cd content in soil decreased by 69.26% and 48.29% respectively when the dosage of GSN is 1%, while the content of residual Cd in soil increased by 143.14%. In addition, the addition of different dosages of GSN had insignificant effect on the soil enzyme activities. In the field experiment, the addition of GSN had insignificant effect on wheat yields, and the content of Cd in wheat grain decreased from 0.342 mg·kg-1 to 0.178 mg·kg-1. These results indicate that GSN has great potential in stabilizing Cd contaminated agricultural soils.
Rice (Oryza sativa) seedlings were co-cultured with multi-walled carbon nanotubes (MWCNTs) and cadmium (Cd) of different concentrations to explore the effects of combined contamination on their growth. The results showed that the growth of rice seedlings was negatively related with the concentration of MWCNTs in the single treatment of MWCNTs. Low concentration of MWCNTs (1.5 mg·L-1) inhibited the growth of rice seedlings, whereas higher concentrations (≥ 6.0 mg·L-1) significantly (P<0.05) inhibited its growth. The addition of 5mg·L-1 Cd2+ enhanced the growth inhibition of MWCNTs on rice seedlings. When the concentrations of MWCNTs increased from1.5 to 12 mg·L-1, the root vigors of rice seedlings decreased by 6.4%, 10.4%, 24.4% and 13.9% in comparison with the composite treatment groups, respectively. The chlorophyll contents were significantly reduced, and the peroxidase activity of rice leaves in the composite treatment groups were 11.0%, 46.1%, 5.6%, and 11.6%, respectively, which were slightly higher than those in the single treatment group. The leaf stomatal conductance of rice seedlings decreased. The intercellular CO2 concentration increased, whereas the photosynthetic rate and leaf stomatal conductance of rice seedlings decreased. It was indicated that MWCNTs and Cd2+ had obvious synergistic effects on the growth of rice seedlings.
In this study, the effect of physical disturbance on phosphate sorption and immobilization onto zirconium-modified zeolite (ZrMZ)-amended sediment was investigated. Results showed that, although the ZrMZ amendment resulted in the increase in the phosphate sorption capacity for the sediment, physical disturbance reduced the phosphate sorption capacity and rate for the ZrMZ-amended sediment. Based on the Langmuir isotherm model, the maximum phosphate monolayer sorption capacity for the ZrMZ-amended sediment after incubation under physical disturbance condition was 743 mg·kg-1, which was 18% lower than that under static condition (902 mg·kg-1). Furthermore, physical disturbance changed the P speciation and bioavailablity in the ZrMZ-amended sediment. After physical disturbance, the contents of Na2S2O4/NaHCO3 extractable P (BD-P) and NaOH extractable P (NaOH-rP) in the ZrMZ-amended sediment decreased, but that of residual P (Res-P) increased. Moreover, the contents of bioavailable P (BAP) including NaHCO3 extractable phosphorus (Olsen-P) and algal available phosphorus (AAP) in the ZrMZ-amended sediment also decreased after physical disturbance. Results of this work indicate that the physical disturbance decreased the phosphate adsorption ability for the ZrMZ-amended sediment but increased the stability of P in the ZrMZ-amended sediment.
To investigate the enrichment of fluoride in geothermal water in Xinyi-Lianjiang region, a total number of 23 sets of water samples were collected including geothermal water, river water and groundwater. Piper diagrams, Gibbs chart and isotopes analysis were applied to explore the chemical characteristics and distribution of high fluoride geothermal water. And the enrichment of fluoride in geothermal water was revealed with Saturation index, ion ratio analysis and correlation analysis methods. The results indicated that more than 65% of the samples had a fluoride content above 1 mg·L-1, and more than 83% of the samples was the hot water samples have a fluoride content above 1 mg·L-1, and the geothermal water containing high fluoride was dominated by the hydrochemical type of HCO3-Na. High fluoride groundwater showed high concentrations of Na+, low concentration of Ca2+ and weakly alkaline. The hydrogen and oxygen isotope data indicated that geothermal water was mainly derived from precipitation, and the longer circulation paths existed in high fluoride water. The major fluoride of the geothermal water came from water rock action and dissolution of fluoride-containing minerals. And dissolved sedimentation of calcium-containing minerals, adsorption-desorption and cation exchange were the main influencing factors of fluoride enrichment in geothermal water.
Based on the data of CO, NO2, SO2, O3, PM10 and PM2.5, the temporal and spatial variation of atmospheric pollutant concentration was studied in the urban area of Hohhot using cluster analysis and correlation analysis. The results showed that the pollution of PM10, PM2.5 and O3 were much more serious in 2017, and the days of exceeding allowable limit were 49 d, 52 d and 41 d, respectively. Carbon monoxide and sulphur dioxide pollution were generally light. The concentrations of CO, NO2, SO2 and PM2.5 showed lower in winter and higher in summer. O3 corcentration showed lower in summer and higher in winter. PM10 showed higher in spring and winter, and lower in summer and autumn. Both O3 and NO2 showed the single-peak daily change characteristics, and the trend was opposite. CO, SO2 and PM2.5 all showed similar bipolar daily changes. Correlation analysis showed that O3 concentration was positively correlated with temperature. PM2.5 was significantly positive correlation with humidity. CO, NO2 and SO2 all showed significantly negative correlation with wind speed. PM10 had different correlations with various meteorological factors in different seasons.
Through the study of the hydrogeochemical characteristics of the hot springs in the deep fault of the western Guangdong (namely Xinyi-Lianjiang deep fault zone), it was revealed that the water chemical components were mainly the dissolution control of silicate minerals, and the Na-K-Mg diagram showed that the hot spring water-rocks interactions were in an unbalanced state. Meanwhile, the thermal storage temperature was estimated to be between 63.2-122.5℃, and the circulation depth was in the range of 1453-3430 m. Our results could provide a basis for further exploration of the relationship between geothermal water and deep faults, as well as shallow geological structures, hydrogeological conditions, and geothermal resource development.
Drinking water quality is of great concern to the public as it directly affects human health.Taking a representative drinking water source (Reservoir A and Reservoir B) in the southeast coastal area of China as the study area, and using the water quality data during 2007-2016, this paper assessed human health risks using the US EPA health-based risk assessment model. Results showed that, the total health risks for adult of Reservoir A and Reservoir B were 3.21×10-5 a-1 and 3.26×10-5 a-1(Risk level Ⅱ, at low-moderate level),while for children were 1.05×10-4 a-1 and 1.07×10-4 a-1(Risk level Ⅳ, at moderate-high level), respectively. The total human health risk includes carcinogenic risk and non-carcinogenic risk, while the former was about 3-4 orders of magnitude higher than the later. The major carcinogenic contaminants in this drinking water source were As, Cd and Cr6+, in which Cr6+ and As were the key carcinogenic contaminants that accounted for 98% of the carcinogenic risk. During 2007-2016, the health risks to both adult and children in Reservoir B showed significant increasing trends.
Cyclic volatile methylsiloxanes (cVMS) have high volatility and high lipophilicity and they are identified as potential global pollutants that are widely distributed in the environment. In this paper, the concentrations of three cyclic volatile methylsiloxanes(D4, D5, D6) were investigated using liquid-liquid microextraction method in the influents and effluents of eight wastewater treatment plants (WWTPs) in Dalian, China. For a period of one year, the seasonal variation of cVMS concentrations in the influents and effluents was investigated. The annual average concentrations of total siloxanes in the influents and effluents were 830.2 ng·L-1 and 234.8 ng·L-1 in WWTPs, respectively. The average concentrations of D4, D5, and D6 in the influents were 471.9 ng·L-1, 1.565×103 ng·L-1 and 453.6 ng·L-1, respectively. The average concentrations of D4, D5, and D6 in the effluents were 249.3 ng·L-1, 244.1 ng·L-1, and 210.9 ng·L-1, respectively. In general, the range of cVMS removal efficiency was 47.2%-84.4%. Concentrations of D4、D5、D6 in the influents were higher than those found in the effluents. The percentage ratio of D5 is 62.2%. The concentration of cVMS in the influents and effluents of WWTPs showed obvious seasonal variations, with higher concentration in the winter and lower in the spring and autumn. The average concentration of cVMS in the influents in the winter was 1.57 times that of spring, and 2.26 times that of autumn. And the average concentration in the effluents in the winter was 1.95 times that of spring and 4.24 times that of autumn. Compared to biological aerated filter (BAF) and cyclic activated sludge technology (CAST) processes, constant water level sequencing batch reactor (CWSBR) had higher removal rate for cVMS.
Temporal and spatial distributions of N and P concentrations in the Hulun Lake ice (upper ice, middle ice, lower ice) and water bodies were analyzed by using the monitoring data during the ice-cold periods of 2015-2017, and the relationship between the eutrophication status index, N, P and Chl.a in the lake was also investigated. The results show that the concentrations of TN and TP in the ice bodies of Hulun Lake were continuously increased in the past three years, and the water quality of the upper ice had exceeded the class V water quality standard limit. Due to the impacts of human activities, external inputs and the internal exchange of pollutants in the lake, the TN and TP concentrations in upper ice were the highest, followed by the lower ice and middle layer. The spatial distribution of TN and TP in the water body was characterized by low concentrations in the lake center and high concentrations in the surrounding area. The concentrations of DTP and DIP decreased first then increased in the vertical direction of ice layer. The concentration range of DTP was from 0.213 mg·L-1 to 0.509 mg·L-1, while the concentration range of DIP was from 0.109 mg·L-1 to 0.432 mg·L-1. The spatial distribution of DTP and DIP was similar to TP. The comprehensive eutrophication status index of water bodies at various sampling sites in Hulun Lake was calculated by using Chl.a, TN, and TP as parameter, and the result show that the correlation between chlorophyll a and TP was good, with a correlation coefficient of 0.627. Further, the concentration of N/P was between 4.38 and 62.3 with an average of 24.49, which means the Hulun Lake belongs to a certain extent of phosphorus-restricted lakes.
According to the "Specification of Land Quality Geochemical Evaluation(DZ/T 0295-2016)", 17 elements in the soil samples were determined, soil environmental quality and soil nutrient abundance status were identified, and comprehensive evaluation of soil quality was obtained. The results showed that the quality of the agricultural land in Ruoqiang County was in good condition, with medium geochemical grade accounting for 85.9%. The comprehensive level of soil nutrients was mainly lacking, among which organic matter, N, Fe and Zn were lacking, and Mo was rich. The soil environment quality was generally good, and the area of mild to severe pollution was less than 8%. Soil pollution was mainly affected by As, Cr and Cd. Meanwhile, this evaluation found that the selenium-rich land resources accounted for 5.3% of the study area, providing a basis for the local development of Se-rich agricultural products.
In this study, a method for the determination of nine N-nitrosamines in water was established by auto-solid phase extraction (ASPE)-gas chromatography-tandem mass spectrometry (GC-MS/MS). After the water samples were enriched by NDMA-SPE at a speed of 10 mL·min-1, the impurities and the water film on the surface of SPE bed were removed by leaching with 20% methanol water solution. The analytes were eluted and collected from the SPE bed with dichloromethane. After concentration, the quantitative analysis was conducted through GC-MS/MS. The analytes were separated on a Rtx-Wax chromatographic column,and ionized by electron impact (EI) source. The data were collected by multiple reaction monitoring (MRM) mode,followed by quantitative analysis using internal standard method. The correlation coefficients of linear calibration curves were over 0.999 in the corresponding linear ranges(1.00—100 μg·L-1). The method detection limit was 0.1—0.5 ng·L-1. The recovery rates of the nine N-nitrosamine compounds were 71%—94%, 74%—95% and 75%—103% at the low, medium and high spike levels, respectively. The corresponding relative deviations were 6.7%—15.8%, 5.1%—12.3% and 4.5%—9.6%, respectively.
A method for Simultaneous determination of puerarin and paeoniflorin in XuanyuntingCapsules by online solidphase extraction coupled with HPLC. The calibration curve of puerarin wasliner within the range of 44.00-132.00 μg·mL-1 (r=0.9997).The average recovery was 97.07% (n=6) and RSD was 1.24%.The calibration curve of paeoniflorin was liner within the range of 284.00-852.00 μg·mL-1 (r=0.9991). The average recovery was 103.64% (n=6) and RSD was 0.501%.
A method for the determination of 10 kinds of strobilurin fungicides residues in fruits by gas chromatography-mass spectrometry with Shimadzu GC/MS-TQ8050 NX triple quadrupole was established. Fruit samples were extracted simply by acetonitrile, purified by dispersed solid phase extraction reagent and analyzed by GC/MS/MS, which greatly reduced the sample pretreatment process. The linearity of 10 kinds of Strobilurin fungicides residues was good in the range of 0.5-200 μg·L-1, and the correlation coefficients were above 0.998. The standard solution of 5.0 μg·L-1 was injected continuously for 6 needles, and the peak area RSD% was less than 8%. The recoveries of actual samples were 93.5%-104.3%. The method is rapid, simple and sensitive, and fully meets the requirements of food safety analysis for the detection of Strobilurin fungicides residues.