Concentrations and Patterns of Atmospheric Particulate Nitrogen and Phosphorus During Different Weather Conditions in Qingdao Coastal Region

Abstract

Total suspended particulate (TSP) samples were continuously collected in the Qingdao coastal region from March 2018 to October 2019. The concentrations of dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP), dissolved total nitrogen (DTN), dissolved total phosphorus (DTP), total nitrogen (TN), and total phosphorus (TP) in the samples were (7.13±6.59) μg·m-3, (17.42±9.88) ng·m-3, (8.34±7.03) μg·m-3, (25.59±13.67) ng·m-3, (10.68±10.59) μg·m-3, and (76.34±51.79) ng·m-3, respectively. The results showed that the concentrations of different nitrogen and phosphorus species in aerosols varied significantly during the sampling period due to the influence of emission intensity, air mass source, and meteorological conditions. The concentrations of DIN, DTN, and TN were the highest in autumn followed by spring, winter, and summer, showing similar seasonal variations. However, TP showed the highest concentration in spring and the lowest in summer. The concentrations of DIN, DTN, and TN on haze days were 4.3, 3.8, and 4.5 times higher than on non-haze reference days, respectively, and DIP, DTP, and TP concentrations were 1.9, 1.9, and 1.2 times higher, respectively. During the heating period, the DIN/DTN ratio on haze days was (92.65±4.09)%, which was 8.87% higher than on non-haze days. During the non-heating period, the DIN/DTN ratio was (80.52±8.42)%, which was 4.83% higher than the reference days. However, the average DTN/TN ratio on haze days was significantly lower than on non-haze days; the average DTN/TN ratio on haze days was (73.41±12.18)% and (80.36±4.72)% during the heating and non-heating period, respectively, and were 13.35% and 5.92% lower, respectively, on non-haze days. The proportion of DIP to DTP on hazy days increased by only 1.47% relative to non-haze days, while the DIP/DTP ratio varied between hazy days. Due to the influence air mass sources, relative humidity, and atmospheric acidification process, the DTP/TP ratio on haze days increased by 10.58% relative to non-haze days. The concentrations of DIN, DTN, and TN in aerosols affected by dust events were 2.5, 2.6, and 2.6 times higher than on non-dust days, while DIP, DTP, and TP were 4.0, 2.8, and 7.2 times higher, respectively.