High temporal resolution of airborne Ambrosia pollen measurements above the source reveals emission characteristics

Abstract

The aim of this study was to setup a field experiment that will collect suitable data for parameterizing the release of Ambrosia pollen. The study took place on the Pannonian plain during three flowering seasons: 2014, 2015 and 2016. The sampling of airborne pollen was performed using volumetric spore traps at 0.5 m and 5 m above the canopy level of a strong homogenous Ambrosia artemisiifolia L. field (10 m × 10 m) in three temporal resolutions: 1 h, 7.5 minutes and 1.07 minutes. This high temporal resolution revealed characteristics that were hitherto unknown. Pollen production per day was estimated to range from 6.38 billion to 770 billion pollen grains for the whole experimental field. Measurements of meteorological parameters included: temperature, relative humidity, solar radiation, precipitation, wind speed and wind direction. Weak correlations between pollen concentration and meteorological parameters were obtained, indicating nonlinear relationships among them. The distribution of pollen concentration with respect to meteorological parameters showed that high pollen concentrations coincide with temperature in the interval 20-24°C, and that relative humidity of around 95% can delay or even switch off the emission, while the turbulent kinetic energy of a wind less than 0.1 m² s¯² is sufficient for lifting the pollen into the air. The test of the new model for Ambrosia pollen emission processes showed a strong correlation between measured and modeled data when the estimated emission capacity for the field was in the range of 45-75 billion pollen grains per day. ATMENV-D-18-00419R1 High temporal resolution of airborne Ambrosia pollen measurements above the source reveals emission characteristics Reviewer #1: I appreciate the work of the authors to elaborate this new version, which I find much improved and highly interesting. I have very few comments now that I summarize here: Reply: The authors thank to the reviewer for helping us to improve the quality of the paper. Reviewer #1: l. 49-50, I do not know the policy of Atmospheric environment with regard to Keywords but I would suggest not use in them words already appearing in the title. So, I propose to consider as Keyword Ragweed (instead of Ambrosia) and pollen production (added or instead pollen emission). Reply: There is no strict rule regarding the words used in the title and as Keywords in Atmospheric Environment. In the new version we have added "ragweed" instead of Ambrosia, however we kept "pollen emission" since the emission process is in the focus of the paper. High temporal resolution of airborne Ambrosia pollen measurements above the source reveals emission characteristics

Land-Use and Height of Pollen Sampling Affect Pollen Exposure in Munich, Germany

“…The effect of local sources, as shown in our study, is enhanced by the location of the DEBIED trap at ground level [25]. This is because pollen traps at roof level sample in more homogeneous conditions and thus deliver more representative measurements of pollen from the surrounding area [29,30].…”

“…These differences could be explained by a combination of the height effect and the configuration of sources, as the DEBIED pollen trap is located at ground level in a garden in close contact with grasses. In an experiment where Ambrosia pollen were collected over an artificially created source, Šikoparija et al [25] found several orders of magnitude more pollen at ground level. This suggests that the effect of height on pollen concentrations is enhanced when the main pollen sources are located in direct contact to the sampling station [41].…”

“…These differences are associated with the spatial distribution of pollen sources with respect to the prevailing meteorological conditions [3,[22][23][24]. Pollen sampling in close proximity to the emission sources provides unrepresentative measurements, only applicable to very local pollen conditions [25]. Other characteristics such as urbanization levels near the station or the proximity to gardens or parks will influence measured pollen concentrations [26].…”

Relationship between airborne pollen assemblages and major meteorological parameters in Zhanjiang, South China

“…And average relative humidity is also positively correlated with arboreal pollen types, such as Castanopsis, Pinus, Myrica, and Euphorbiaceae. Previous research has shown that the pollen emission process varies between species; for example, some grasses may require high relative humidity, which causes the swelling and splitting of the anthers [51]. In spring, the RDA results show that the average temperature (p = 0.01) had relatively significant correlation with pollen concentration of major pollen types, and other meteorological factors failed to pass the test.…”

Bioaerosol field measurements: Challenges and perspectives in outdoor studies

“…Unlike inorganic dust concentrations, which are lower both during and shortly after rainfall (Issanova and Abuduwaili 2017), concentrations, e.g., of bioaerosols including fungal spores and bacteria, can frequently increase during and after rainfall due to both passive and active processes (Joung, Ge, and Buie 2017;Morris et al 2017;Rathnayake et al 2017;Conen et al 2017;Wolf et al 2017;Wang et al 2016;Petters and Wright 2015;Hader, Wright, and Petters 2014;Wright et al 2014;Huffman et al 2013;Schumacher et al 2013). Concentrations of various classes of bioaerosols, including fungal spores, bacteria, and pollen, are also known to change depending on the time of the day, influenced by a combination of biological emission processes, relative humidity, increase of turbulent kinetic energy, and also atmospheric dilution effects caused by daily changes in boundary layer height ( Sikoparija et al 2018b;Healy et al 2014;Huffman et al 2012;Fang et al 2007). Finally, the speed of atmospheric dilution and microbial activity, such as growth or gene expression, occurs on a much shorter time scales than the sampling and could thus go unnoticed.…”