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Understanding the phenology of urban trees can help mitigate the heat island effect by strategically planting and managing trees to provide shade, reduce energy consumption, and improve urban microclimates. In this study, we carried out the first evaluation of high spatial resolution satellite images from Landsat-8, Sentinel-2, and PlanetScope images to quantify urban street tree phenology in downtown Beijing. The major research goals are to evaluate the consistency in pixel-level spring–summer growth period phenology and to investigate the capacity of high-resolution satellite observations to distinguish phenological transition dates of urban street trees. At the city scale, Landsat-8, Sentinel-2, and PlanetScope show similar temporal NDVI trends in general. The pixel-level analysis reveals that green-up date consistency is higher in areas with medium (NDVI > 0.5) to high (NDVI > 0.7) vegetation cover when the impacts of urban surfaces on vegetation reflectance are excluded. Similarly, maturity date consistency significantly increases in densely vegetated pixels with NDVI greater than 0.7. At the street scale, this study emphasizes the efficacy of NDVI time series derived from PlanetScope in quantifying the phenology of common street tree genera, including Poplars (Populus), Ginkgos (Ginkgo), Chinese Scholars (Styphnolobium), and Willows (Salix), in downtown Beijing to improve urban vegetation planning. Based on PlanetScope observations, we found that the four street tree genera have unique phenological patterns. Interestingly, we found that the trees along many major streets, where Chinese Scholars are the major tree genus, have later green-up dates than other areas in downtown Beijing. In conclusion, the three satellite observation datasets prove to be effective in monitoring street tree phenology during the spring–summer growth period in Beijing. PlanetScope is effective in monitoring tree phenology at the street scale; however, Landsat-8 may be affected by the mixture of land covers due to its relatively coarse spatial resolution. [ABSTRACT FROM AUTHOR]

Abstract On August 14th, 2018, a Beijing resident living in Xicheng District found a female H. longicornis tick attached to the skin at the front of his upper shin. On examination, the patient was afebrile and appeared well. The species of the tick was identified through morphological characteristics and phylogenetic analysis based on cytochrome C oxidase subunit I. This H. longicornis tick was screened for tick-borne pathogens such as viruses, bacteria and parasites. RNA pathogens were screened by PCR and sequencing, while DNA pathogens were screened by metagenomic analyses. It was found that the tick was positive for the DNA sequences of zoonotic and animal pathogens such as A. phagocytophilum, Ehrlichia minasensis and C. burnetii. Considering the good health condition of the patient, we hypothesized that the pathogens originated from the tick specimen itself rather than host blood meal. For the first time, our study reveals the possible risk of transmission of tick-borne pathogens to human beings through tick bit in downtown Beijing. Further research is needed to screen for tick-borne pathogens among unfed ticks collected from central Beijing.

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The particulate matter (PM) pollution of Beijing fluctuated significantly before and after precipitation events during the rainy period. The rainwater samples were continually collected at five-minute intervals on the roof of a building in downtown Beijing. The PM 2.5 was also monitored at same temporal scale. The pH and concentrations of ammonia-N, nitrate-N, phosphorus, sulfur, and heavy metals (Cd, Mn, Fe, Zn, and Cu) in the rainwater samples were measured, and the values were used to assess the effect of washing on PM 2.5 and determine the characteristics of the rainwater pollutants. The PM 2.5 was negatively correlated to the quantity of accumulated rainfall (R 2 value ranged from 0.668 to 0.974), which identified the function of the washing process on PM 2.5 pollution. The washing process of rainfall strongly affects PM 2.5 , which decreased to 10–30 μg m − 3 with 5 mm of rainfall. The analysis of the temporal patterns of ten pollutants in rainwater demonstrated that most of the pollution load was contributed by the first 5 to 10 min of the washing process. The event mean concentration (EMC) of nine inorganic pollutants was used to evaluate the pollution load and identify sources of particle pollution. Sulfur was the primary inorganic element detected in PM, and the average EMC of twelve rainfall events was 8.92 mg L − 1 . The EMC of ammonia-N, nitrate-N, and phosphorus after significant PM 2.5 pollution was 11.57 mg L − 1 , 1.72 mg L − 1 , and 0.019 mg L − 1 , respectively. The total pollution load of the rainwater collecting area during the rainy reason was also calculated, and the largest heavy metal load of 3.11 mg was attributed to Zn. The pollution loads of heavy metals and the stable relationship between the pollutants indicate the potential urban environmental management policies in Beijing. [ABSTRACT FROM AUTHOR]