[Concentrations, Sources, and Dry Deposition Fluxes of Different Forms of Phosphorus in Qingdao Aerosols in Summer].

Total suspended particulate (TSP) samples were collected in Qingdao from June to July 2016. Different forms of phosphorus in these samples-including total phosphorus (TP), dissolved phosphorus (DP), dissolved inorganic phosphorus (DIP), and dissolved organic phosphorus (DOP) were analyzed to investigate their distribution characteristics and sources, as well as their dry deposition fluxes. Results showed that the mass concentration of TP in aerosols was (49.3±30.6) ng·m-3, and the concentration of DP was (15.5±10.4) ng·m-3, accounting for 30.9%±11.0% of TP. DIP dominated in dissolved state P, contributing about 60%. The sources of different forms of P were analyzed, showing that the P in Qingdao aerosols in summer was derived from both crustal and anthropogenic sources, with the latter including biomass burning and agricultural fertilization. TP was mainly derived from soil sources, which contributed 38%, while the contribution of agricultural activities and industrial sources was about 20%. DIP in DP was mainly derived from agricultural activities and combustion sources, with contributions of 51% and 24%, respectively. DOP was mainly derived from soil sources and agricultural activities, contributing 41% and 27% respectively. The dry deposition flux of TP in Qingdao was (51.7±31.7) µg·(m2·d)-1, of which 23.2%±8.2% was the water-soluble fraction. DOP in the total dry deposition flux of DP was non-negligible, accounting for 40%. The atmospheric deposition of soluble P would support phytoplankton carbon production of (0.5±0.3) mg·(m2·d)-1, contributing about 1% to new productivity in the Yellow Sea.

[Concentration, Solubility, and Dry Deposition Flux of Trace Elements in Fine and Coarse Particles in Qingdao During Summer].

PM2.5 and total suspended particulate (TSP) samples were synchronously collected in Qingdao from June to July 2016. The total and water-soluble concentrations of 12 trace elements in these samples were analyzed to investigate their distribution characteristics in fine and coarse particles as well as their dry deposition fluxes. The results showed that the total mass concentrations of Al, Fe, Sr, Mn, and Ba, which are expected to mainly originate from crustal sources, were generally distributed in the coarse particles, and the part mass in the coarse mode accounted for 55%-60% of their total concentrations. Cr, Ni, V, Zn, Pb, As, and Cd, which mainly originate from anthropogenic contributors, generally existed in fine particles where the part mass accounted for 65%-85% of their total concentrations. The soluble mass concentrations of trace elements, whether from crustal or anthropogenic sources, were mainly distributed in the fine particles. The proportions of Al, Fe, Mn, and Ba in soluble mass concentration existing in the fine particles were 50%-80% and 70%-90% for Cr, Ni, V, Zn, Pb, As, and Cd. The solubility of trace elements was higher in fine particles than in coarse particles. The soluble concentrations of trace elements exhibited a positive correlation with acid compounds, and the solubility exhibited a negative correlation with pH in the fine particles, implying that acidification processes play a key role in determining the solubility of trace elements in fine particles. The soluble fractions in the total dry deposition flux of Al and Fe were only 1%-2%; that of Sr, Ba, Cr, and Pb were about 30%-40%; and that of Mn, Ni, V, Zn, As, and Cd were about 50%-60%. The atmospheric deposition of soluble Fe supported phytoplankton carbon production of (194±150) mg·(m2·d)-1, contributing about 10% of the primary productivity in the Yellow Sea.

[Distribution of Oxalate in Atmospheric Aerosols and the Related Influencing Factors in Qingdao, During Winter and Spring].

A total of 119 total suspended particle (TSP) samples were collected in Qingdao from December 2012 to April 2013. Concentrations of oxalate in TSP were measured to investigate the distributional characteristics of oxalate and the related influencing factors, in winter and spring. The concentrations of oxalate in Qingdao aerosols were 31-370 ng·m-3 with an average of 104 ng·m-3 in winter, and 11-1926 ng·m-3 with an average of 400 ng·m-3 in spring, with a significant difference between the concentrations in the two seasons. Different weather conditions affected the distribution of oxalate in aerosols. The oxalate concentration in TSP was the highest in the hazy days, followed by that in the dusty days, while this concentration in foggy days was close to that in the clear days, and the lowest concentration of oxalate appeared in the rainy days. Oxalate in Qingdao aerosols exhibited a significant positive correlation with temperature and solar radiation, suggesting that the secondary production of oxalic acid via photochemical oxidation has an important contribution to the oxalate concentrations in aerosols. The mechanisms of secondary formation of oxalate in aerosols in winter and spring are possibly different, with the aqueous phase oxidation process predominating in winter and the gas-phase oxidation-driven process predominating in spring. The results of PMF source analysis also showed that the secondary formation is the main source of oxalate in Qingdao aerosol, and its contribution to oxalate production is nearly 45% in winter and 70% in spring. The concentration of oxalate in spring aerosol was significantly higher than that in winter aerosol, the main reason of which was that temperature and solar radiation in spring were significantly higher than those in winter, promoting the secondary formation of particulate oxalate.

[Concentrations and Solubility of Trace Elements in Atmospheric Precipitation in Qingdao].

Thirty-five atmospheric precipitation samples were collected at an urban site in Qingdao from June 2016 to May 2017. The total and soluble concentrations of eight trace elements in the samples were determined, and the variable characteristics of the concentrations and solubility of trace elements, as well as the factors affecting the solubility of trace elements in atmospheric precipitation, have been discussed. Based on the overall data, the total concentrations of the trace elements were found to be in the order Al > Fe > Zn > Mn > Ba > Pb > Sr > V, but the soluble concentrations of the trace elements were in the order Zn > Al > Mn > Fe > Ba > Sr > Pb > V. Solubility was about 5% for the crustal elements Al and Fe, and the solubility of the elements affected by anthropogenic sources was relatively higher, 10%-40% for Pb and Ba, 20%-60% for Mn and Sr, and nearly 55% for Zn and V. The total and soluble concentrations of the trace elements were higher in winter and spring than in summer and autumn, but element solubility in spring was the highest. During continuous rainfall, the total concentrations of trace elements in precipitation decreased appreciably, but the variation trend of the solubility of trace elements was not consistent during the different rainfall processes. The variation in pH was the main factor controlling the solubility of trace elements in precipitation.

[Concentrations of Acidic Gases, Ammonia and Related Water-Soluble Ions in PM2.5 and Gas-Particle Partitioning in Qingdao].

Fifty-eight samples were collected in Qingdao from November to December 2012 using a PM2.5 sampler. Concentrations of acidic gases, ammonia and their partner ions in PM2.5 were determined, and the correlation between concentrations and the gas-particle partitioning were analyzed. The averaged concentrations of HNO3, HNO2, HCl, SO2 and NH, in atmosphere samples of Qingdao were 1. 36, 1. 64, 1. 46, 27. 58 and 2. 95 µg.m-3, respectively, for the concentrations of NO3-, NO2, Cl-, SO(4)2- and NH: in PM2, were 6. 49, 0. 12, 1. 95, 9. 36 and 6. 04 µg.m-3, respectively. When the measurements made in haze days, compared to those made in clear days, the concentration of these ions in PM2.5 increased more than those of acidic gases and ammonia; In foggy days, the concentrations of gases were lower than those in clear days except HNO2, while the reverse was true for the concentrations of all particulate species in PM2.5. During whole study period, the NH3 level was high and the NH4+ in PM2.s in Qingdao was mainly present as (NH4)2SO4. The analysis results suggested that formation of N03 were mainly determined by HNO3. To further explore the control factors of these species in PM2.5, the thermodynamic equilibrium model of ISORROPIA I was employed. Our sensitivity tests showed that the formation of NH4+ was less sensitive to the change of total NH3 (TNH3), but sensitive to the changes of total H2 SO4(TSO4) and total HNO3 (TNO3). The formation of NO3- and SO(4)2- was sensitive to the changes of TNO3 and TSO4, respectively. Taken together, our findings implied that the reduction of TNO3 and TSO4 rather than TNH3 appears to be more effective in lowering mass concentrations of PM2.5 in Qingdao.

Variability in the correlation between Asian dust storms and chlorophyll a concentration from the North to Equatorial Pacific.

A long-term record of Asian dust storms showed seven high-occurrence-frequency centers in China. The intrusion of Asian dust into the downwind seas, including the China seas, the Sea of Japan, the subarctic North Pacific, the North Pacific subtropical gyre, and the western and eastern Equatorial Pacific, has been shown to add nutrients to ocean ecosystems and enhance their biological activities. To explore the relationship between the transported dust from various sources to the six seas and oceanic biological activities with different nutrient conditions, the correlation between monthly chlorophyll a concentration in each sea and monthly dust storm occurrence frequencies reaching the sea during 1997-2007 was examined in this study. No correlations were observed between dust and chlorophyll a concentration in the <50 m China seas because atmospheric deposition is commonly believed to exert less impact on coastal seas. Significant correlations existed between dust sources and many sea areas, suggesting a link between dust and chlorophyll a concentration in those seas. However, the correlation coefficients were highly variable. In general, the correlation coefficients (0.54-0.63) for the Sea of Japan were highest, except for that between the subarctic Pacific and the Taklimakan Desert, where it was as high as 0.7. For the >50 m China seas and the North Pacific subtropical gyre, the correlation coefficients were in the range 0.32-0.57. The correlation coefficients for the western and eastern Equatorial Pacific were relatively low (<0.36). These correlation coefficients were further interpreted in terms of the geographical distributions of dust sources, the transport pathways, the dust deposition, the nutrient conditions of oceans, and the probability of dust storms reaching the seas.

[Seasonal distribution of water-soluble inorganic ions in the atmospheric aerosol in Qingdao].

To collect comprehensive information on the characteristics and sources of water-soluble ions in the atmospheric aerosol in Qingdao, samples of total suspended particles (TSP) were collected from January to December 2008, and the concentrations of the major water-soluble inorganic ions were analyzed using ion chromatography. The results showed that SO4(2-), NO3-, NH4+ and Cl- were the dominant water-soluble ions in TSP, the sum of the four accounting for 86.9% of water-soluble ions in mass concentration. TSP and water-soluble inorganic ions showed obvious seasonal variations and there were a variety of sources. The mass concentrations of Na+, NH4+, Ca2+, F- and Mg2+ were highest in winter and lowest in summer. The concentrations of K+ and PO4(3-) were highest in autumn and lowest in summer. NO3-, Cl- and SO4(2-) concentrations had the highest values in spring, winter, and spring, respectively. Different weather conditions had great influence on the concentrations of TSP and water-soluble ions. The mass concentrations of TSP were highest in dust weather followed by haze, smog, fog and sunny days. The average mass concentrations of Na+ , Mg2+, Ca2+, F- , Cl- and PO4(3-) were highest in smog days while the other ions in haze days.

[Contribution of water soluble organic nitrogen to total nitrogen in atmospheric aerosols in Qingdao].

Organic nitrogen (ON) is a quantitatively important component of reactive nitrogen in atmospheric aerosols. Deposition of ON in seawater from atmosphere could enhance primary productivity, as well as with the changes in the phytoplankton community composition. 64 total suspended particles (TSP) samples collected at Qingdao from January to December in 2008 were applied to analyze the concentrations of water soluble organic nitrogen in aerosols. Concentrations of ON in Qingdao aerosols ranged from 30 to 2073 nmol x m(-3) (100-12 157 micromol x g(-1)), with the highest values occurring in December, followed in March and April and the lowest values in June to September. ON mean concentration in TSP in 2008 was 430 nmol x m(-3) (2 323 micromol x g(-1)). The contribution of ON to total nitrogen (TN) was (37.5 +/- 21.6)%, with the maximum presenting in December and the minimum in September. The distribution of organic nitrogen in aerosols was significantly affected by the weather conditions. During haze and fog episodes, the concentrations of ON in the aerosols were 789 nmol x m(-3) and 412 nmol x m(-3), respectively, 4 times and twice higher than that during clear episodes. However, the particle mass concentrations in haze and fog days were comparable with that in clear days. During dust episodes, the concentration of particles was 5 times higher than that during clear episodes while ON concentration slightly enhanced 0.4 times. The ON concentration in aerosols after raining was 57 nmol x m(-3), decreased 80% than that before raining due to the efficient wet scavenging.

[Distribution of atmospheric particulate inorganic nitrogen in different weather conditions in the heating period in Qingdao].

The atmospheric aerosol samples were collected before and in the heating period during October 2007-April 2008 in Qingdao coastal region, and inorganic nitrogen components were analyzed using IC (Ion Chromatography). The results showed that the concentration of aerosol particles and particulate inorganic nitrogen components (NH4+, NO3-) were increased from 137.41 microg/m3, 2.48 microg/m3, 6.95 microg/m3 before to 250.34 microg/m3, 4.43 microg/m3, 10.28 microg/m3 in the heating period respectively. The concentrations of TSP (total suspended particles) and inorganic nitrogen in Qingdao were influenced by different weather conditions. The average concentration of TSP was 181.34 microg/m3 in sunny days during heating period, increased by 32.0% than before. But the nitrate and ammonium showed a value of 5.56 and 1.86 microg/m3 in sunny days, lower than that before heating, which mainly came from secondary aerosols. The average concentrations of TSP, nitrate and ammonium increased were 1-2 times higher in foggy days in heating period due to lower temperature, high humidity and accumulation of pollutants. The concentrations of TSP, nitrate and ammonium decreased in strong winds and temperature drop weather. The size distribution of aerosol particles and inorganic nitrogen, were influenced clearly by heating soot and ash. The size distribution of nitrate showed double peaks with a higher peak in accumulation mode (0.43-0.65 microm) and a lower one in coarse mode (3.3-4.7 microm) before heating, and the peak in the 'accumulation mode' shifted to 0.65-1.1 microm during heating period. NH4(+) -N, a major inorganic nitrogen component in the particulate matter, showed single peak in the "accumulation mode".

[Distributions of dissolved and particulate amino compounds in atmospheric aerosols at Qingdao].

Amino compounds is one class of organic nitrogen compounds that has been measured extensively in aerosols and rainwater. These compounds in atmospheric deposition might have a potential role in marine ecosystem since it can be directly utilizable sources of nitrogen for microorganisms and plants. 66 total suspended particles samples were collected at Qingdao from January to December in 2008. Concentrations of dissolved amino compounds (DAC) and particulate amino compounds (PAC) were analyzed using precolumn fluorescence derivatization with o-phthaldialdehyde and N-isobutyryl-L-cysteine, combined with reverse-phase high performance liquid chromatography. Concentrations of DAC in Qingdao aerosols ranged from 2.4 to 40.9 nmol x m(-3), with highest values occurring in spring, followed in summer and lowest values in autumn and winter. PAC concentration were from 0.7 to 76.1 nmol x m(-3), presenting the seasonal trend of spring > winter > autumn > summer. Compositions of amino compounds in aerosols varied seasonally. By classifying air mass back trajectories during each sampling period, the aerosol samples in Qingdao were mainly influenced by northerly continental source, southerly continental source and marine source. Concentrations of DAC and PAC were found highest in the samples influenced by southerly continental source, followed by northerly continental source and lowest in the samples by marine source. Compositions of amino compounds were also influenced by the sources. Contributions of protein-type to total amino compounds were highest in the aerosols from marine source and lowest in the aerosols from southerly continental source.

[Distributions of inorganic nitrogen species in atmospheric aerosols over the East China Sea].

33 total suspended particle samples and 7 size-segregated particle samples were collected over the East China Sea from Nov. to Dec., 2006, Feb. to Mar., 2007 and May. to Jun., 2008. Concentrations of ammonium, nitrate and nitrite in aerosols were measured to investigate their seasonal variation and size distribution. The concentrations of ammonium in aerosols ranged from 2.6 to 646.9 nmol x m(-3) ,with the higher values observed in winter and spring, and the lower values in summer. Nitrate concentrations were from 5.5 to 281.5 nmol x m(-3), presenting the seasonal trend of winter > spring approximately summer. The concentrations of nitrite were very low, less than 0.5 nmol x m(-3). The relative contributions of nitrogen species to total nitrogen varied seasonally in some extent. The contribution of nitrate was comparable with that of ammonium in winter, while the contribution of ammonium was the predominant in spring and summer. The size distribution of nitrate presented clear monthly changes. Most of nitrate existed in the fine particles less than 2.1 microm in Nov. to Dec., and it predominated in the coarse particles with the size of 1.1-4.7 microm and 2.1-7.0 microm, respectively, in Feb. to Mar. and May. to Jun. The size distributions of ammonium in different months were similar, with one peak presenting in the < 1.1 microm fine particles. The air mass back trajectories analysis indicated that the distributions of inorganic nitrogen in aerosols were significantly influenced by the sources and transport pathways of air mass. Both high nitrogen concentration per unit atmospheric volume (nmol x m(-3)) and per unit mass particle (micromol x g(-1)) occurred when the air mass passed over severe pollution region. Both low concentration in atmosphere and particle occurred when the air mass came from clean marine atmosphere. Lower concentration in atmosphere and higher concentration in particle occurred when the air mass originated from the continent and transported long distances over the sea.

[Urea in aerosol and rainwater over the East China Sea in winter and spring].

Organic nitrogen is a quantitatively important component of fixed nitrogen in atmospheric aerosol and rainwater. Urea as a possible candidate of organic nitrogen component might have a significant influence to the marine ecosystem since its bioavailability and broad range of natural and anthropogenic sources. 23 total suspended particulate samples, 4 size-segregated particles samples and 10 rainwater samples collected over the East China Sea from Nov. to Dec., 2006 and Feb. to Mar., 2007 were applied to analyze the concentrations of urea, nitrate and ammonium in aerosols and rainwater, respectively. In winter and spring, the concentrations of urea nitrogen were from 0.2 nmol m(-3) to 17.7 nmolx m(-3) and 6.5 nmol x m(-3) to 14.6 nmol x m(-3) in bulk aerosols, respectively and the corresponding concentrations were from 7.8 miromol x L(-1) to 18.1 micromol x L(-1) and 12.1 micromol x L(-1) to 35.3 micromol x L(-1) in rainwater. In both aerosols and rainwater over the East China Sea, the concentrations of urea nitrogen were higher in spring than those in winter. Urea nitrogen in aerosols contributed about 5% to the three measured nitrogen species and it was about 20% in rainwater. The size distribution of urea was markedly different from those of nitrate and ammonium,which had no pronounced difference among cascade stages. A slightly enhance urea contribution presented in the range of 0.43-0.65 microm in spring, which was 19.8%. In contrast, an enhancement presented in the range of 3.3-4.7 microm in winter, which was 19.8%. Factor analysis indicated that the sources of urea in aerosols were dominated by wind-blown soils in winter and sublime of urea in soils in spring, respectively.

[Nitrifying bacteria and nitrification in sediment at the adjacent sea area of Yangtze River Estuary in summer].

The influence factors and environmental effects of nitrification process were discussed based on the measurements of nitrifier quantities and nitrification rates at eight sites off Yangtze River Estuary in June 2006. Using FISH (Fluorescence in situ hybridization) method, the nitrifying bacteria were counted as 1.87 x 10(5) -3.53 x 10(5) cells/g wet weight and exhibited salt tolerance to some extent. The nitrification rates, measured by acetylene inhibition technique, ranged from 101.3 to 514.3 micromol/(m2 x h) and had a decreased gradient from nearshore to offshore sediment with two high value regions located at the mouth of Yangtze River and Hangzhou Bay respectively. The nitrifier quantity was a main factor to effect nitrification rates at high-salinity sea area, with an influence ratio of 87.7%. Fluxes of transformed nitrogen and consumed oxygen by nitrification process were 4.68 x 10(5) kg and 6.07 x 10(4) mol per day respectively, suggesting that nitrification would be an important factor for the distribution of DIN species and DO at bottom water in early summer.