Nanjing Environmental Monitoring Center

Nanjing, China

Nanjing Environmental Monitoring Center

Nanjing, China
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Wang M.,Nanjing Environmental Monitoring Center | Yang L.,Nanjing Environmental Monitoring Center | Hu E.,Nanjing Environmental Monitoring Center
Chinese Journal of Chromatography (Se Pu) | Year: 2017

A method by using microwave extraction and high performance liquid chromatography was developed to determine polycyclic aromatic hydrocarbons (PAHs) in airborne particles. The glass / quartz fiber filter, on which particles adsorbed, was extracted with a mixed solvent n-hexane / acetone (1 :1, v / v) using microwave, and the subsequent purification of the extract was carried out by a florisil cartridge. The prepared sample was determined by high performance liquid chromatography coupled with photodiode array (PDA) and fluorescence dual- detector. The target compounds showed good linearity between the mass concentration of 20. 0 μg / L and 500 μg / L, with the correlation coefficients not less than 0. 996 0. The spiked recoveries of target compounds in blank filter ranged from 56. 3% -101%. The current method has been applied to investigate the distribution of PAHs in airborne particles in Nanjing City.

Chen K.,Nanjing University of Information Science and Technology | Yin Y.,Nanjing University of Information Science and Technology | Wei Y.-X.,Nanjing Environmental Monitoring Center | Yang W.-F.,Nanjing University of Information Science and Technology
Zhongguo Huanjing Kexue/China Environmental Science | Year: 2010

Chemical characteristics and possible sources of fine particular matter (PM2.5) was investigated for 1 year in Nanjing. PM2.5 was collected from June 2007 to May 2008, which carbonaceous species, organic carbon (OC) and elemental carbon (EC), in the samples were analyzed. Seasonal variations of OC and EC concentrations were investigated; the pollution degree and characteristics of carbonaceous aerosols during haze and no haze period were analyzed and compared. Results showed that yearly PM2.5 and carbonaceous concentrations varied in wide ranges with 12.1~287.1 μg/m3 for PM2.5, 2.6~47.0 μg/m3 for OC and 1.0~33.6 μg/m3 for EC. On seasonal average, the highest PM2.5 (109.6 μg/m3) and OC (20.8 μg/m3) levels occurred during summer. The seasonal average concentrations of PM2.5 and organic carbon levels ranked by the order of summer > autumn > winter > spring, while the seasonal average concentrations of EC were in the order of autumn, spring, winter and summer. The OC/EC ratio and concentrations of carbonaceous species such as, OC, EC and total carbon (TC) in haze days were 1.7 2.0, 1.8, and 1.9 times higher than those in non-haze days. Backward air trajectories indicated that haze formation in Nanjing was attributable to air masses with abundant water vapors and pollutants.

Wang T.,Nanjing University | Jiang F.,Nanjing University | Deng J.,Nanjing University | Deng J.,Chinese Institute of Urban Environment | And 6 more authors.
Atmospheric Environment | Year: 2012

Air pollution and haze weather have become more and more important environmental and meteorological issues in Yangtze River Delta (YRD) region of China. In order to foster urban and regional air quality management and realize operational prediction and early warning of air pollution and haze weather episode, an urban air quality forecasting system based on the new generation of weather research forecast and chemistry model WRF-Chem and a regional haze weather forecasting system based on Regional Atmospheric Environment Modeling System (RegAEMS) were applied in Shanghai, Nanjing and YRD area. More than one year runs and typical case studies show that WRF-Chem performed well in urban air quality forecast on surface concentrations of air pollutants such as SO 2, NO 2 and PM 10. The accuracy rate of prediction on urban Air Pollution Index (API) is 50-83% and 80% for Shanghai and Nanjing, respectively. RegAEMS presents relatively good ability in forecast on regional haze weather. A new classification standard on haze level was proposed, which take the key parameters such as relative humidity, PM 2.5 and visibility into account. It is estimated that RegAEMS predicts haze level with accuracy rate of 58 and 77% for Nanjing and Shanghai in YRD region. Many factors, including meteorology, emission inventory and chemical processes can be attributable to the forecast bias. However, from this study, it is highly suggested that improvements of emission inventory from construction dust, fugitive dust, soil dust, transportation and biomass burning are very crucial to get better performance on air quality and haze weather prediction. © 2012 Elsevier Ltd.

PubMed | Fudan University, University of Shanghai for Science and Technology and Nanjing Environmental Monitoring Center
Type: Journal Article | Journal: Environmental science and pollution research international | Year: 2016

The gas-phase ammonia (NH3) and fine particle PM2.5 ammonium (pNH4(+)) (collectively, NHx) were monitored between July 2013 and August 2014 in a busy traffic area of Nanjing, China. Results showed that PM2.5 concentration was 66.7 g m(-3), and NH3 concentration was 6.66 g m(-3). In the PM2.5, the concentration of pNH4(+) was 3.04 g m(-3), SO4(2-) (pSO4(2-)) was 10.16 g m(-3), and NO3(-) (pNO3(-)) was 1.60 g m(-3). The significant correlation curves from the tests of PM2.5 revealed that molar ratio of pNH4(+) and pSO4(2-) was approximately 2, which could be (NH4)2SO4. Particulate NH4(+) primarily associated with pSO4(2-), which accounted for 4.54% of total PM2.5 mass. The PM2.5 observed acidic and the NH3 in the atmosphere neutralized acidic species, mainly in a sulfate form. The traffic intensity in the region was partially related to the formation of PM2.5 and NH3, suggesting that traffic pollution may be an important source of PM2.5. The reaction between NHx and acidic species was assumed to the secondary PM2.5. The neutralization and photochemical property of NHx were discussed.

Huang D.,Nanjing University | Xu B.,Nanjing University | Tang J.,Nanjing University | Luo J.,Nanjing University | And 4 more authors.
Analytical Methods | Year: 2010

A simple and sensitive indirect determination method for sulfide in water samples by anodic stripping voltammetry (ASV) using mercury-film electrode (MFE) has been developed, which is based on the determination of residual cadmium ion after reaction of Cd2+ with S2-. The linear range is adjustable depending on Cd2+ concentration, for example, the determination of S2- can be achieved in the range of 1.5-7.0 × 10-6 mol L-1 by selecting 3.0 × 10-6 mol L-1 Cd2+. The detection limit is 1.3 × 10 -8 mol L-1 under optimum conditions, and the relative standard deviation (RSD, n = 10) for 2.0 × 10-6 mol L -1 S2- is 0.7%. Compared with other methods, this method has the following prominent advantages: with low detection limit, easy to operate and less interference. The proposed method has been successfully applied to the determination of S2- in synthetic wastewater, lake water, beverage, spring water and real wastewater samples. © 2010 The Royal Society of Chemistry.

Dou Y.,Nanjing University | Dou Y.,Nanjing Environmental Monitoring Center | Wang B.,Nanjing University | Chen L.,Nanjing University | Yin D.,Tongji University
Environmental Science and Pollution Research | Year: 2013

Bicarbonate plays a crucial role in limiting the growth of submersed aquatic macrophytes in eutrophic lakes, and high ammonia is often toxic to macrophytes. In order to evaluate the combined effect of HCO3 - and total ammonia (i.e., the total of NH3 and NH4 +) on submersed macrophytes Vallisneria natans, the growth and physiological response of V. natans in the presence of HCO3 - and ammonia were studied. The results showed that with the increase of ammonia, morphological parameters of V. natans declined. In contrast, increased HCO3 - concentration stimulated the growth of V. natans, especially when the NH4 +-N/NO3 --N ratio was 1:7. High ammonia concentration induced excess free amino acids (FAA) accumulation and soluble carbohydrates (SC) depletion in plant tissues. However, the elevated HCO3 - promoted the synthesis of SC and rendered the decrease of FAA/SC ratio. The results also suggested that HCO3 - could partially alleviate the stress of ammonia, as evidenced by the decrease of FAA/SC ratio and the growth enhancement of V. natans when the ammonia concentration was 0.58 mg L-1. Given the fact that HCO3 - is probably the dominant available carbon source in most eutrophic lakes, the ability of V. natans to use HCO3 - for SC synthesis may explain the alleviating effect of HCO3 - on V. natans under ammonia stress. © 2013 Springer-Verlag Berlin Heidelberg.

Huang D.-Q.,Nanjing University | Huang D.-Q.,Fuyang Teachers College | Xu B.-L.,Nanjing University | Tang J.,Nanjing University | And 3 more authors.
International Journal of Electrochemical Science | Year: 2012

In this paper, the analytical applications of bismuth film electrodes (BiEFs) are summarized in recent years. Using BiEFs as working electrode, an indirect determination method for sulfide in water samples by anodic stripping voltammetry (ASV) is established, based on the determination of residual Cd 2+ after reacting with S 2-. Under the optimal experimental conditions (0.1 mol L -1 pH 4.5 NaAc-HAc, C Cd2+ = 3.6 × 10 -6 mol L -1, deposition potential E d = -1.2 V, and reaction time t R = 120 s), the determination of S 2- can be achieved in the range of (0.7-5.0) × 10 -6 mol L -1 with a detection limit (DL) of 2.1 × 10 -7 mol L -1 and a relative standard deviation (RSD, n=10) of 3.6% for 1.7 × 10-6 mol L- 1 S 2-. Compared with the previously proposed methods, this method can eliminate the interferences such as Br -, SCN -, PO 4 3-, CO 3 2-, NO 2 -, Al(III) and Fe(II) efficiently. In addition, the proposed method possesses the distinct advantages of cheap instrument and simple manipulation. It has been successfully applied to the determination of S 2- in different spiked water matrices (mineral water, lake water, synthetic wastewater and real wastewater) with recoveries ranging from 95 to 106%. © 2012 by ESG.

Han S.-Y.,Nanjing University | Qiao J.-Q.,Nanjing University | Zhang Y.-Y.,Nanjing University | Yang L.-L.,Nanjing Environmental Monitoring Center | And 3 more authors.
Chemosphere | Year: 2011

n-Octanol/water partition coefficients (P) for DDTs and dicofol were determined by reversed-phase high performance liquid chromatography (RP-HPLC) on a C18 column using methanol-water mixture as mobile phase. A dual-point retention time correction (DP-RTC) was proposed to rectify chromatographic retention time (tR) shift resulted from stationary phase aging. Based on this correction, the relationship between logP and logkw, the logarithm of the retention factor extrapolated to pure water, was investigated for a set of 12 benzene homologues and DDT-related compounds with reliable experimental P as model compounds. A linear regression logP=(1.10±0.04) logkw - (0.60±0.17) was established with correlation coefficient R2 of 0.988, cross-validated correlation coefficient Rcv2 of 0.983 and standard deviation (SD) of 0.156. This model was further validated using four verification compounds, naphthalene, biphenyl, 2,2-bis(4-chlorophenyl)-1,1-dichloroethane (p,p'-DDD) and 2,2-bis(4-chlorophenyl)-1,1-dichloroethene (p,p'-DDE) with similar structure to DDT. The RP-HPLC-determined P values showed good consistency with shake-flask (SFM) or slow-stirring (SSM) results, especially for highly hydrophobic compounds with logP in the range of 4-7. Then, the P values for five DDT-related compounds, 2-(2-chlorophenyl)-2-(4-chlorophenyl)-1,1,1-trichloroethane (o,p'-DDT), 2-(2-chlorophenyl)-2-(4-chlorophenyl)-1,1-dichloroethane (o,p'-DDD), 2-(2-chlorophenyl)-2-(4-chlorophenyl)-1,1-dichloroethene (o,p'-DDE), and 2,2,2-trichloro-1,1-bis(4-chlorophenyl)ethanol (dicofol) and its main degradation product 4,4'-dichlorobenzophenone (p,p'-DBP) were evaluated by the improved RP-HPLC method for the first time. The excellent precision with SD less than 0.03 proved that the novel DP-RTC protocol can significantly increases the determination accuracy and reliability of P by RP-HPLC. © 2011 Elsevier Ltd.

PubMed | Imperial College London, Nanjing University and Nanjing Environmental Monitoring Center
Type: | Journal: The Science of the total environment | Year: 2016

In this study, samples of size-fractionated particulate matter were collected continuously using a 9-size interval cascade impactor at an urban site in Nanjing, before, during and after the Asian Youth Games (AYG), from July to September of 2013, and the Youth Olympic Games (YOG), from July to September of 2014. First, elemental concentrations, water-soluble ions including Cl

PubMed | Nanjing Environmental Monitoring Center
Type: Journal Article | Journal: Se pu = Chinese journal of chromatography | Year: 2014

An effective method was developed to determine phenolic compounds in soil by ultrasonic extraction-gas chromatography (GC). The soil sample was extracted with methylene dichloride-hexane (2:1, v/v) for 3 min with the extraction temperature lower than 50 degrees C for 3 times. The extract was purified by alkaline aqueous solution (pH > 12), and the phenolic compounds were dissolved in aqueous solution. After the organic solution was discarded, the aqueous solution was adjusted to pH <3 and subsequently extracted with methylene dichloride-ethyl acetate (4:1, v/v) twice. The analytes were determined by GC-FID and quantified by external standard method. The limits of quantification for all tested phenolic compounds were 0.01-0.06 mg/kg in about 10 g soil samples. The recoveries were between 62.9% and 111.4% with the relative standard deviations (RSDs) in the range of 4.3%-24.0% (n = 6). The results showed that this method is sensitive, accurate, and suitable for the determination of the 21 phenolic compounds in soil.

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