| Bioaerosols are a significant subgroup of atmospheric aerosols and it has great impact on environment, human health, global climate and atmospheric process. It is very important to study the distribution of bioaerosols in the Qingdao coastal region to know the composition and environmental effect of bioaerosols over the sea. Bioaerosol samples were collected by six-stage Andersen sampler from Sept.2007 to Aug.2008 and from Jun.2009 to Feb.2010 in the Qingdao coastal region. The concentrations of culturable microbe (including terrigenous/marine bacteria and fungi) and total microbe (including'culturable microbe'and'non-culturable microbe') in different particle sizes were analyzed. The composition, seasonal and size distribution of bioaerosols in the Qingdao coastal region were discussed. And the impact of dust on microbial distribution of bioaerosols were also discussed.The results showed that the monthly average proportion of non-culturable microbe to total microbe was 99.24% on average from Jun.2009 to Feb.2010 in the Qingdao coatal region, while culturable microbe accounted for only 0.76%. Culturable fungi contributed more to total culturable microbe than culturable bacteria while marine microbe contributed more to total culturable microbe than terrigenous microbe. And.marine bacteria/fungi contributed more to total culturable microbe than terrigenous ones. Terrigenous/marine fungi, total culturable fungi and total marine microbe of samples collected under dust weather contributed more to total culturable microbe than non-dust samples.The average concentrations of total microbe and culturable microbe (including terrigenous/marine bacteria, terrigenous/marine fungi, total terrigenous microbe, total marine microbe, total bacteria, total fungi and total culturable microbe) had obvious variations in months and seasons. From Jun.2009 to Feb.2010 at Yushan and Laoshan sampling site of in Qingdao, the monthly average concentrations of total microbe were in the ranges of 8.11X104-1.88X105 CFU/m3 and 8.52X104-1.76X105 CFU/m3 respectively, and the seasonal average concentrations of total microbe were highest in the fall, higher in the summer, lowest in the winter. From Sept.2007 to Feb.2008, the highest and lowest concentrations of terrigenous/marine bacteria were observed in Apr. and May 2008 respectively at Yushan site, while the highest and lowest concentrations of terrigenous/ marine fungi appeared in Sept.2007 and Feb.2008 respectively. All kinds of culturable microbes showed higher concentrations in spring and fall, lower ones in summer and winter. From Jun.2009 to Feb.2010, the highest concentrations of terrigenous/marine bacteria appeared in Dec.2009, with the lowest concentration of terrigenous fungi and the highest concentration of marine fungi being in Oct.2009 at two sites. The seasonal average concentrations of terrigenous/marine bacteria were highest in the winter, higher in the fall and lowest in the summer. The seasonal average concentrations of marine fungi were highest in the fall, higher in the summer and lowest in the winter at Yushan and Laoshan sites. The terrigenous fungi concentration showed highest value in the winter, higher in the summer and lowest in the fall at Yushan site, while terrigenous fungi concentration showed highest value in the summer, higher in the fall and lowest in the winter at Laoshan site..From Jun.2009 to Feb.2010 in the Qingdao coastal region, the total microbial particle size presented a log-normal distribution, with the highest proportion of particles with size in 3.3-4.7μm to total particles and the lowest one of that in 0.65-1.1μm, which showed that the total microbe mainly existed in coarse particles larger than 2.1μm with the average proportion higher than 70%. During the sampling period, particle size of terrigenous/marine bacteria showed a skew distribution, with the highest proportion of particles larger than 7.0μm to total ones and the lowest one of that in 0.65-1.1μm for terrigenous/marine bacteria. And the particle size of terrigenous/marine fungi presented a log-normal distribution with the highest ratio of particles in 2.1-3.3μm to total particles and the lowest one of that in 0.65-1.1μm for terrigenous/ marine fungi. The culturable microbe mainly existed in coarse particles larger than 2.1μm and the coarse mode contributed more than 80% for total particles.The average concentrations of terrigenous/marine bacteria and terrigenous/marine fungi of samples under dust weather were 4.4,3.8,5.8 and 7.1 times that non-dust samples in the spring 2008. The particle size of terrigenous/marine bacteria of samples collected under dust weather showed the similar distribution to that of non-dust samples, But the proportion of particles with diameter of>7.0μm and 0.65-1.1μm were higher for dust samples than that for non-dust sample. Terrigenous fungi under dust weather had higher proportion of particles larger than 3.3μm and in 0.65-1.1μm to the total ones than non-dust weather, and marine fungi under dust weather had higher proportion of particles ranged in 3.3-7.0μm to total ones compared with non-dust samples. |
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