This study evaluates the air quality in Nanchong City in 2015–2018 based on automatic monitoring data and meteorological data in the main urban area. Results show that overall air quality in the main urban area of Nanchong was standard and improved from 2015 to 2018. SO2, NO2, and CO had slight influences on air quality in the study area, whereas excessive annual average PM2.5 and increasing O3 concentration challenged the air quality. The monthly average mass concentrations of particulate matters (PM2.5 and PM10), NO2, and CO generally presented a “U-shaped” distribution pattern while O3 showed the opposite. The diurnal variation of PM, NO2, and CO has two peaks related to the morning and evening rush hours. Vehicle exhaust is the main source of local pollution. Over-standard PM2.5 can significantly inhibit O3 production while O3 can easily promote the secondary generation of PM2.5 due to its strong oxidization. PM2.5 emission should be controlled strictly in winter, while in summer, the sources of O3 should be controlled vigorously. Air pollution is comprehensive and complicated and is influenced by various factors, mainly meteorological and human factors. Measures such as artificial rainfall should be included at the appropriate time to cope with adverse meteorological conditions when heavy pollution occurs in winter.

The sources and variation trend of ambient air pollutants, the duration of pollution process and the conditions for decontamination were analyzed in this essay based on the ambient air pollutants data, PM_2.5 source analysis data and meteorological factors in Nanchong City during 2014 to 2019. The results indicated that the concentrated discharge of fireworks on New Year’s Eve was the main reason for the sharp deterioration of the ambient air quality. PM_2.5 and PM₁₀ concentrations increased significantly after fireworks were set off, and the peak value appeared at about 02:00 on the Lunar New Year’s Day, but the value of PM_2.5/PM₁₀ did not change significantly. The concentration of SO₂ in gaseous pollutants was slightly affected by fireworks, while NO₂, CO and O₃ were not affected basically. Having been affected by fireworks, the concentrations and percentages of K⁺, Cl^- and Mg²⁺ of the water-solubility ions in PM_2.5 significantly increased at the 0.01 level. Meanwhile, the concentrations and percentages of the metal elements, including Cu, Pb, Mg, Al, K and Ba, significantly increased at the 0.05 level. Restricted to the topography and meteorological factors, the duration of the pollution was prolonged.

The evolution and expression of floral traits are responses to selection pressure from biotic and abiotic factors. Although floral traits significantly vary among environments, the flower remains unchanged. We aimed to understand the adaptation of Epimedium chlorandrum of floral traits to a frequently nocturnally rainy and wet environment and the roles of floral traits in pollination and reproduction. We observed flowering phenology, measured floral characteristics including the number of pollen grains and ovules per flower, measured pollen viability and stigma receptivity, tested the volume and sugar concentration of nectar, and conducted flower-visit observations in this species. Different pollination treatments were performed to characterize the breeding system. The inner sepals and highly curved longer spurs of E. chlorandrum jointly formed an umbrella that shielded the anthers and stigma from rain wash and prevented nectar dilution. E. chlorandrum was visited by six species, while Bombus trifasciatus was the only effective pollinator and fed on the nectar. One flower secreted approximately 17.06 μL of nectar with a 29.19 g/100 ml sugar concentration, and the pollination efficiency of B. trifasciatus was positively associated with the nectar sugar concentration. The self- and open-pollination treatments resulted in fewer fertile seeds than the cross-pollination treatment. In contrast, the autonomous self-pollination treatment failed to yield fertile seeds. In summary, pollen limitation caused by harsh weather and pollinator shortage occurred during the pollination process of E. chlorandrum, which was partially alleviated by self-compatibility.