Study on Influence of Airborne Microbes Concentration of Urban Greenspaces : Case Study of Campus of Jiangsu University, China

이관림 강원대학교 대학원 2013 국내석사

Microbes including bacteria, fungal spores, actinomyces and viruses are widely distributed in the air. The airborne microbes are important biological components in urban ecological system. They have a direct relationship with ecological balance and many life phenomena in nature, and play very important roles in natural matter cycle. Their pollution can lead to changes of air quality easily, and they can also influence human health by spreading all kinds of diseases. Therefore, airborne microbe condition is central representation of comprehensive factors of urban environment and is one of the important indexes to evaluate urban air environment quality. Improving urban environment quality is one of the effective channels to control airborne microbial types and quantities. Urban greenspace has important ecological functions of purifying air and improving urban environment and plays an important role in improving urban environment quality. Urban greenspace plants can absorb and filter dust in air through branches and reduce carriers which bacteria survive and reproduce in order to control their quantities; they can inhibit or eliminate bacteria, fungi and pathogenic microorganisms directly in environment. Therefore, the systematical and comprehensive study and analysis on antibacterial effect of urban greenspaces in different seasons and with different structures and the establishment of health protection artificial floras have important significances in maintaining urban greenspace system structures and functions, controlling urban pollution and improving urban environment quality. In this paper, the sampling sites and control sites were chosen in the campus of Jiangsu University, China and the concentration of airborne bacteria and fungi were measured during the daytime from 9:00am to 5:00 pm in 3 days of Spring (May, 2012), Summer (August, 2012), Autumn (November, 2012) and Winter (February, 2013). The results indicated that greenspace air has low bacterial concentration and significant difference by being compared with base area, more greenspace airborne microbial pollution degrees are “clean space” or “less clean space”, which suggests that greenspace has antibacterial and bactericidal effects for airborne microbial pollution, but the concentration of fungi in greenspace air is higher than bare area. Furthermore, the concentration of airborne microbes has apparent characteristics of spatio-temporal variation. The airborne microbial concentration in greenspace has obvious season and month daily changes. The results showed that there is a negative correlation between airborne microbial concentration and greenspace coverage rate, that is to say, the more greenspace coverage rate is, the smaller quantity of air bacteria is, which reflects that greenspace has ecological effect of reducing quantity of bacteria in air. Moreover, the results also showed that there is a positive correlation between vegetation canopy density in greenspace and fungal concentration in air, the larger vegetation canopy density is, the higher fungal concentration is. Different greenspace systems have different space structures, as well as bactericidal and microorganism reducing capabilities. Overall, in the comparisons with greenspace airborne microbial concentrations of different space structures, multi-layered structure (tree-shrub-grass combination) is larger than simple vegetation allocation structure (tree-shrub combination; shrub-grass combination) which is larger than single allocation structure (grass), indicating that the vertical vegetation structure of greenspaces is an important factor affecting airborne microbial inhibition rate.

Transversality conditions on the pair of ordered functionals : 두 순서있는 범함수의 Transversality conditions

이관림 서울대학교 대학원 1972 국내박사

Effects of open-field experimental multiple climate change drivers (warming and precipitation manipulation) on soil microbial community, soil extracellular enzyme, and soil respiration

李冠霖 Graduate School, Korea University 2017 국내박사

생물지구화학적 물질 순환의 주요 조절 인자인 대기 온도와 강수량은 기후변화에 따라 크게 변화할 것으로 예상된다. 그리고 기후변화에 따른 대기 온도 및 강수량의 변화는 토양 내 양분의 무기화, 손실 및 흡수 과정과 CO2 배출 등에 영향을 미칠 것이다. 그런데 육상 생태계의 구조와 기능은 토양 내 미생물에 의하여 조절되므로, 기후변화에 대한 미생물의 반응과 이에 따른 피드백 작용을 이해하는 것은 매우 중요하다. 그러나 기후변화가 토양 미생물에 미치는 영향은 여전히 불분명한 부분으로 남아 있다. 본 연구의 목적은 기후변화(대기 온도 및 강수량의 변화)가 토양 미생물 군집, 효소 활성도, 토양 호흡에 미치는 영향과, 이러한 미생물 변화가 기후변화에 어떠한 피드백 작용을 할 것인지를 밝히는 것이다. 이를 위하여 2013년 4월, 고려대학교 캠퍼스에 2년생 소나무 묘목을 식재한 실외 실험적 온난화(+3 °C) 및 강수량 조절(-30%, +30%) 실험지를 조성하고 연구를 진행하였다. 첫 번째로 기후변화가 토양 미생물 군집의 구조와 조성에 미치는 영향을 분석하였다. 이를 위하여 2014년 10월부터 2015년 12월까지 2개월 주기로 매월 세 번째 주에 토양(0–15 cm 깊이)을 채취하고, High-throughput analysis와 BIOLOG EcoPlate를 활용하여 토양의 미생물 군집의 구조와 조성을 조사하였다. 조사 결과, 강수량을 변화시키지 않은 조건에서, 온난화 처리는 비온난화 처리에 비하여 미생물 바이오매스 탄소와 질소를 각각 3.7%와 19.9% 증가시켰다. 그러나 강수량을 감소시킨 조건에서는, 온난화에 의한 미생물 바이오매스의 변화는 나타나지 않았다. 한편 온난화 및 강수량 조절을 적용한 처리들은 온난화와 강수량 조절을 모두 적용하지 않은 처리에 비하여 세균과 곰팡이의 군집 풍부도(community richness)를 각각 -14.3%–-2.1%와 -26.0%–17.4%만큼 변화시켰다. 이들 처리는 세균의 군집 다양성(community diversity)을 -3.5%–-0.9%만큼 변화시켰으나, 곰팡이의 군집 다양성을 -52.3%–0.5%만큼 변화시켰다(P < 0.01). 그런데 온난화가 미생물 군집 조성에 미치는 영향은 강수량 조절 처리에 따라, 그리고 세균과 곰팡이 간에 상이하였다. 특히 온난화 및 강수량 조절 처리는 실험지에서 우점하는 세균 그룹인 Proteobacteria의 풍부도(abundance)를 유의하게 변화시켰다(P < 0.05). 이러한 토양 미생물 군집의 변화는 온난화 및 강수량 조절 처리에 따른 토양 조건(토양 온도, 수분, 양분 유효도 등) 변화에 의한 것으로 추정된다. 두 번째로 기후변화가 탄소, 질소 및 인 순환에 관여하는 토양 효소(β-glucosidase, N-acetyl-glucosaminidase, Leucyl aminopeptidase, phosphatase)의 활성도에 미치는 영향을 분석하였다. 이를 위하여 2015년 4월부터 12월까지 2개월 주기로 매월 세 번째 주에 토양(0–15 cm 깊이)을 채취하였다. 측정 결과, 토양 효소의 활성도와 이들 간 비율(ecoenzymatic ratios)은 온난화 및 강수량 조절 처리보다는 월 변이의 영향을 크게 받는 것으로 나타났다. 즉, 정도의 차이는 있으나 모든 토양 효소의 활성도는 12월에 가장 높았다. 한편 온난화 처리는 효소의 활성도를 증가 또는 감소시켰으며, 처리의 영향은 일관되지 않고 조사구별로 상이하였다. 이는 기후변화가 토양 조건과 미생물 군집을 변화시킴으로써 효소의 활성도에 영향을 미치며, 이러한 기후변화의 영향이 토양 수분 등의 조건에 따라 차이를 보일 수 있다는 것을 의미한다. 마지막으로 기후변화가 토양 호흡에 미치는 영향을 분석하였다. 이를 위하여 2015년 6월 19일, 8월 19일, 10월 20일 오전에 비분산형 적외선 CO2 센서와 폴리아크릴 재질 챔버로 토양 호흡을 측정하였다. 강수량을 증가시킨 조건에서, 온난화 처리는 비온난화 처리에 비하여 토양 호흡을 54.6%–59.7%만큼 증가시켰다(P < 0.05). 그러나 이와 대조적으로 강수량을 감소시킨 조건에서, 온난화 처리는 비온난화 처리에 비하여 토양 호흡을 19.4%만큼 감소시켰다. 그리고 온난화에 따른 토양 호흡의 변화는 토양 수분 조건별로 상이하였다. 따라서 온난화는 토양 호흡을 유의하게 증가시키나, 수분이 부족한 조건에서는 온도 증가에 의한 토양 건조 현상이 온난화에 따른 토양 호흡 변화를 제한할 수 있을 것으로 판단된다. 이와 같은 결과들을 종합하면, 대기 온도의 증가와 강수량의 변화는 토양 환경을 변화시킴으로써 토양 미생물 군집, 효소 활성도, 토양 호흡 등에 영향을 미치는 것으로 나타났다. 그런데 이러한 기후변화가 토양 미생물 군집, 효소 활성도, 토양 호흡에 미치는 영향은 일관되지 않고 측정 월 등에 따른 변이를 보였다. 특히 수분이 부족할 경우, 토양 수분 조건이 기후변화에 대한 토양 미생물 군집, 효소 활성도, 토양 호흡의 반응을 제한하였다. 본 연구의 결과는 기후변화가 토양 미생물에 미치는 영향이 주위 환경에 따른 차이(context-dependency)를 보이며, 이를 기후변화에 따른 변화를 모의하는데 고려해야 함을 의미한다. 소나무가 한국의 침엽수림과 혼효림에서 가장 우점하는 수종임을 고려하면, 소나무를 식재한 조건에서 토양 미생물 반응을 모의한 본 연구의 결과는 미래 기후변화 하에서 소나무림의 변화를 예측하는 데에 기여할 수 있을 것으로 기대된다. Atmospheric temperature and natural precipitation regimes are major environmental factors regulating important biogeochemical cycles in terrestrial ecosystems and are expected to be altered by climate change. Therefore, soil nutrient mineralization, transformation, loss, and uptake by plants, as well as gas (e.g., CO2 and N2) efflux from soil are likely to change as well. Despite the likelihood that the terrestrial ecosystem process and functions mediated and catalyzed by soil microbes will react to climate change, their response and feedback has yet to be clearly understood. The present study aims to determine the effects of climate change drivers (i.e., atmospheric warming and precipitation manipulation) and their interaction on soil microbial community, soil extracellular enzyme, and soil respiration (RS), and to understand their feedbacks to this process. This will be accomplished by conducting a multiple climate change drivers experiment involving atmospheric warming by 3 °C and reduced or elevated precipitation manipulations by 30%. The site was established at Korea University in April, 2013 and used to study the effects of open-field experimental atmospheric warming and precipitation manipulation on two-year-old Pinus densiflora seedlings. In the first study, soil microbial community structure and composition were analyzed to investigate how multifactor climate change drivers affected soil microbial communities. Surface soil (0 - 15 cm) was collected during the third week of October and December in 2014, and April, June, August, October, and December in 2015. High-throughput analysis and BIOLOG EcoPlate assays were used to detected the soil microbial community structure and composition. The results showed that warming slightly increased microbial biomass carbon (C) and nitrogen (N) by an average of 3.7% and 19.9%, respectively, in precipitation control plots. However, the enhancement of microbial biomass as a function of warming was not observed in the reduced precipitation plots. Compared with the ambient treatment (unwarmed and precipitation control treatment), all other treatments slightly altered bacterial and fungal community richness, ranging from -14.3% to -2.1% and -26.0% to 17.4%, respectively. However, all other treatments altered bacterial community diversity, ranging from -3.5% to - 0.9%, and significantly altered fungal community diversity ranging from -52.3% to 0.5% (P < 0.01). Warming distinguished bacterial and fungal community composition under different precipitation manipulation plots. In particular, the experimental treatments induced significant differences in Proteobacteria abundance (P < 0.05), which was the dominant group in the bacterial community. The alterations in the soil microbial community may result from a direct and/or indirect treatment effect on soil conditions (e.g., soil temperature, moisture, and quantity and quality of available nutrients). In the second study, four soil potential extracellular enzyme activities which likely impact C, N, and phosphorus (P) dynamics were measured to investigate the effects of climate change drivers and their interaction on soil extracellular enzyme. Surface soil (0 - 15 cm) was collected during the third week of April, June, August, October, and December in 2015. The results showed that four soil potential extracellular enzyme activities and three ecoenzymatic ratios were more affected by the month than by the direct and/or interaction effects of climate change drivers. The highest values of all potential extracellular enzyme activities were observed in December at various levels. Both positive and negative warming effects on soil extracellular enzymes were observed, and the responses of enzymes to treatments were dissimilarity among plots. The results indicated that climate change drivers altered soil potential extracellular enzyme activities through alterations in soil conditions, and soil microbial biomass and community structure. In particular, soil moisture could regulate the responses of soil extracellular enzymes to the climate change effect. In the third study, RS was examined to investigate the effects of climate change drivers and their interaction on the RS of P. densiflora seedlings. RS were measured on the mornings of June 19th, August 19th, and October 20th, 2015 using a portable diffusion-type, non-dispersive infrared (NDIR) CO2 sensor and a polyacrylics chamber. The results showed that warming induced significant changes in RS (P < 0.05), enhancing RS by an average of 54.6% and 59.7% in the control and elevated precipitation plots, respectively; however, warming reduced RS by 19.4% in plots subjected to lower rates of precipitation, indicating a link between warming and moisture. On the basis of these findings, warming is posited to significantly influence RS, but the warming effect on RS may be weakened by warming-induced soil drying in water-limited environments. These results indicate that climate change drivers would alter soil microbial communities, soil extracellular enzymes, and RS directly and indirectly through changes in soil conditions. The responses of soil microbial communities, soil extracellular enzyme activities, and RS to climate change drivers showed strong but dissimilarity monthly variations. In particular, soil moisture regulated the responses of soil microbial communities, soil extracellular enzyme activities, and RS to climate change in water-limited environments. These results indicate that the responses of soil ecosystem to climate change are context-dependent and indicate the importance of taking into account the context-dependency of climate change effects on soil microbial communities and functions. Given that P. densiflora is one of the representative temperate coniferous trees in the naturally occurring coniferous and mixed forests of South Korea, the results of this research are useful for predicting microbial responses in P. densiflora forest ecosystems across South Korea in the face of future climate change.