ABSTRACT
In this study, 30 PM2.5 samples were collected from the atmosphere in Changchun City in the autumn of 2017. The concentration and composition characteristics of 17 polycyclic aromatic hydrocarbons (PAHs) in the samples were analyzed by gas chromatography mass spectrometry (GC-MS). The diagnostic ratio and principal component analysis method were used to determine the source of PAHs pollution. The health risk assessment was carried out by both calculating the equivalent carcinogenic concentration of benzo(a)pyrene and the lifetime risk of cancer. Results show that the average PM2.5 concentration in autumn in Changchun is (50.84±12.23) µg·m-3, and the content of organic carbon (OC) and elemental carbon (EC) are (17.07±5.64) µg·m-3 and (1.33±0.75) µg·m-3, respectively, accounting for 37% of the total PM2.5. The total concentration of PAHs is (15.69±5.93) ng·m-3, which was dominated by medium- to high-ring-number PAHs, accounting for 84.26% of total PAHs. The atmospheric PAHs in Changchun mainly originate from motor vehicle exhaust emissions (44.48%) > coal combustion (29.16%) > biomass burning (26.36%), local transportation (gasoline vehicles) emissions being the main source of pollution. The average carcinogenic concentration of benzo(a)pyrene is in the range of 1.55 ng·m-3 and 5.38 ng·m-3, and the average carcinogenic equivalent concentration is (6.44±1.53) ng·m-3, which is generally considered a slight pollution level. The ingestion of PAHs by breathing is the most harmful to the health of adult women, followed by adult males and children, however since the lifetime carcinogenic risk value of the entire population did not exceed 1×10-6, their health risks are considered to be at acceptable levels.
Subject(s)
Air Pollutants/adverse effects , Polycyclic Aromatic Hydrocarbons/adverse effects , Risk Assessment , Adult , Child , China , Cities , Environmental Monitoring , Female , Humans , Male , Particulate Matter/adverse effectsABSTRACT
To investigate the effect of biomass burning in Changchun in autumn on the absorbance of water-soluble organic carbon (WSOC) on PM2.5, PM2.5 samples were collected from October to November 2017. The light absorption characteristics of WSOC, carbonaceous components, and carbohydrate content in PM2.5 were analyzed. The study showed that the average concentrations of WSOC, organic carbon (OC), and elemental carbon (EC) in PM2.5 in Changchun were (10.12±3.47), (17.07±5.64), and (1.34±0.75) µg·m-3, respectively; the average contribution rate of secondary organic carbon (SOC) to OC was 38.93%. The total sugar concentration in Changchun is (1049.39±958.85) ng·m-3, of which the content of anhydroglucose (L-glucan, galactan, and mannan), as a biomass burning tracer in total sugar, was 91.69%. The results of sugar correlation analysis showed that biomass combustion was the main source of contribution to carbohydrates in the autumn of Changchun. The light absorption wavelength index of WSOC in autumn was 5.75±1.06, and the unit mass absorption efficiency was (1.23±0.28) m2·g-1, indicating that biomass combustion has an important influence on WSOC absorbance. The biomass combustion characteristic source parameter was used to quantify the contribution of biomass burning to WSOC concentration, which was found to be 58.82%, while the contribution to total WSOC light absorption was 40.92%.
ABSTRACT
Organic aerosols have attracted increasing attention recently due to their significant contribution to fine particles (PM2.5) and their complex components and sources. In this study, a total of 40 PM2.5 samples were collected simultaneously with high-volume samplers in Changchun from 16th Oct to 29th Nov 2016. Organic carbon (OC), elemental carbon (EC), non-polar organic compounds including n-alkanes, polycyclic aromatic hydrocarbons (PAHs), and hopanes, and levoglucosan in atmospheric fine particles were analyzed. The main sources of organic aerosols were identified by molecular markers, diagnostic ratios, and a principal component analysis-multiple liner regression (PCA-MLR) model. The results showed that the average mass concentration of PM2.5 was (79.0±55.7) µg·m-3, and the averaged OC and EC mass concentrations were (20.7±15.6) µg·m-3 and (2.2±1.1) µg·m-3, which accounted for 26.2% and 2.8% of PM2.5, respectively. The total average concentration of the tested non-polar organic compounds was (186.3±104.5) ng·m-3 and, in descending order, this was composed of n-alkane (101.3±67.0) ng·m-3, polycyclic aromatic hydrocarbons (81.4±46.0) ng·m-3, hopanes (3.8±1.9) ng·m-3. The PCA-MLR model results showed that the relative contributions of the main sources of organic aerosols were coal combustion (47.0%), biomass burning (42.6%), and traffic emission (10.4%).
ABSTRACT
Ammonium salts, including ammonium nitrate, ammonium sulfate and ammonium hydrogen sulfate, are the main components of secondary inorganic aerosols and play an important role in the formation of haze events. The sources and transformation processes of atmospheric ammonium have received more and more attention. In this study, we modified the previous stable isotope analysis technique by improving the injection volume and adding a pH adjustment step, which gave a rapid and accurate measurement of ammonium nitrogen isotope ratio in atmospheric aerosol samples. Firstly, we added alkaline hypobromite to the extracted solution of the atmospheric aerosol filter samples (0.25 µg·mL-1 ammonium nitrogen in 4 mL) to oxidize ammonium (NH4+) to nitrite (NO2-). Then, after adjusting the pH, nitrite (NO2-) was reduced to nitrous oxide (N2O) by hydroxylamine hydrochloride under pH <0.3. Finally, nitrous oxide (N2O) was analyzed by Precon-GasBench-IRMS system to measure ammonium nitrogen isotope ratio. Our approach required low amount of NH4+ and avoided the use of highly toxic and explosive reagents. Meanwhile, the precision of our method could reach as high as 0.2 (n=10). This method could increase the NH4+ reduction efficiency to 100% at a condition of pH <0.3 and satisfy the demands of precision and accuracy for determination of ammonium nitrogen isotope in atmospheric aerosol samples. This method would help us better understand the sources, evolutions, chemical and deposition processes of atmospheric ammonium.
Subject(s)
Air Pollutants/analysis , Ammonium Compounds/analysis , Environmental Monitoring , Hydroxylamine/chemistry , Nitrogen Isotopes/analysis , Nitrogen , Oxidation-Reduction , SaltsABSTRACT
Objective To explore the effect of iodine excess on bone metabolism in experimental autoimmune thyroiditis (EAT) rats. Methods We selected 36 female Lewis rats with body weight of (131 ± 15)g,and divided them into 3 groups randomly: control group, EAT group and EAT + high iodine group, assuring 12 rats in every group. These rats were fed fodder with different concentration of iodine(0.9,0.9, 18.0 mg/kg), and rats in EAT group and EAT + high iodine group were immunized with pig thyroglobulin(pTG) and complete Freund's adjuvant(CFA) to create EAT model. After two weeks, the pathological changes of the thyroid tissues were observed,and the serum thyroid autoantibody[thyroglobulin antibody(TGAb) and thyroid microsomal antibody(TMAb)], the thyroid hormone levels[triiodo thyronine(T3) and thyrine(T4)] and some relevant data of bone metabolism[bone gla protein (BGP), tartrate-resistant acid phosphatase (TRAP), C-terminal propeptide of type Ⅰ procollagen (PICP),C-terminal telopeptide of type Ⅰ collagen (ICTP), insulin-like growth factor- 1 ( IGF- 1 ), osteoprotegerin (OPG) and receptor activator of NF-κB ligand (RANKL)] were measured. Results Inflammatory cell infiltration and local follicular structural damage were observed in the thyroid tissues of EAT rats in EAT group and EAT + high iodine group, and the pathological changes of EAT + high iodine group were mainly thyroid follicular expansion and integration. The level of serum TGAb, TMAb, T3 and T4 of EAT rats in EAT group and EAT + high iodine group[ (63.01 ± 12.36)%, (60.62 ± 11.24)%, (3.78 ± 1.43), (125.12 ± 16.00)pmol/L and (75.00 ± 15.44)%,(72.15 ± 15.00)%, (3.69 ± 0.91 ), (149.40 ± 20.67)pmol/L] were higher than those of the control group[ (4.47 ±1.04)%, (5.73 ± 1.01 )%, (0.75 ± 0.12), (76.91 ± 9.30)pmol/L, all P ＜ 0.05], and the level of serum TGAb,TMAb and T4 of EAT rats in EAT + high iodine group were higher than those of the EAT group(all P ＜ 0.05).The level of serum BGP, PICP and IGF- 1 in EAT group[ ( 1.70 ± 0.31 ), ( 11.31 ± 1.52) μg/L, (0.31 ± 0.06 ) mg/L]were lower than those of the control group[ (8.60 ± 0.33), (14.28 ± 3.10)μg/L, (1.16 ± 0.02)mg/L, all P ＜0.05], and the level of serum TRAP, ICTP, OPG and RANKL[ ( 19.88 ± 3.60)ng/L, (2.43 ± 0.82), (22.36 ± 2.80),( 1.35 ± 0.23 )μg/L] were higher than those of the control group[ ( 14.57 ± 3.56)ng/L, (0.50 ± 0.20), (1.61 ± 0.34),(0.10 ± 0.02)μg/L, all P ＜ 0.05]; compared with EAT group, the level of PCIP and OPG in EAT + high iodine group [ (8.03 ± 1.84), ( 16.80 ± 3.79)μg/L] were obviously decreased(all P ＜ 0.05). Conclusions The reinforcement of differentiation and maturation of osteoblast in the EAT rats results in the increasing of bone resorption. The activity of osteoblast and osteoclast of the EAT rats are inhibited by excessive iodine, showing a low conversion-type osteoporosis.
