Determination of dust in the urban atmosphere of Antalya using a developed sampling method

This study aims to develop a nature-based sampler as an alternative to conventional particulate matter (PM) sampling and evaluate its performance in an urban atmosphere alongside conventional systems. In this context, moss has been used as a biomaterial instead of a filter in the conventional method. In the conventional method, using the energy of the particle carried by the wind- instead of the region holding particles larger than the aerodynamic diameter of 10 micrometers (PM10), which is a pre-impactor at a certain volume drawn- inspired by PM emission control devices, pre-impactors have been designed for different wind speeds. A small fan was used to balance the energy loss due to friction and create a partial negative pressure inside the device. Although the aim was to use moss cultivated in a laboratory environment, this process failed due to contamination. As a contingency plan, naturally, growing mosses were provided, and these mosses were placed inside the sampler after pre-treatment. The developed devices were used in two separate campaign periods in the city center of Antalya over eight months (with eight sampling periods, each lasting one month). During the first campaign period (21/09/2021-21/12/2021), one PM2.5 and one PM2.5-10 sample were collected daily using conventional samplers. In the second campaign period (19/01/2022-19/06/2022), one PM2.5 and one PM2.5-10 sample were collected every three days continuously for 72 hours using conventional samplers. The elemental analyses of the samples collected during the first campaign period were conducted at the Middle East Technical University (METU) Central Laboratory, while the analyses of the samples collected during the second campaign period were conducted at the IzTech Integrated Research Centers. All analyses were performed using ICP-MS and ICP-OES devices. Due to budget constraints, only a portion of the samples collected during the second campaign period, specifically between 21/03/2022 and 19/06/2022, were analyzed. When the results of the first campaign period were examined, it was found that the results differed from the conventional systems due to the inability to separate the mosses collected from nature from the soil they were exposed to. During the last two sampling processes in the second campaign period, a pre-washing procedure for the mosses was developed. However, it was observed that the changes in the washing process did not positively impact the results. Generally, similarities were found between the results of the conventional and developed sampling systems in terms of concentration changes of certain elements such as Na and As. The soil enrichment factor and source identification analyses determined that mosses contained more soil-derived elements and were less affected by anthropogenic influences. The inability of the developed sampler to create a homogeneous sampling environment and its failure to correct the deviation caused by higher sampling rates, which are a result of increased wind speeds, emerges as another reason for the observed differences between the results obtained with the conventional sampler. After the source identification study, it was determined that the presence of the soil factor in the composition of the mosses used in the developed sampling system caused a deviation. Therefore, it is valuable that other factors (anthropogenic, combustion, and oil burning) showed a similar distribution of sources over time, albeit with lower contributions. Longer studies are aimed to be conducted with the developed sampler to eliminate uncertainties. It is also considered that investigations can be carried out to determine anthropogenic semi-volatile pollutants, such as PAHs and PCBs, which have low background concentrations in mosses.