The role of urban parks in improving public health has been analyzed in the context of urban design in developed countries, but has seldom been considered in developing countries such as China. Previous studies have found positive correlations between parks and residents' physical activity and mental health status. In this study, we conducted a questionnaire survey to investigate respondents' physical activity status and its relationship with urban parks. The impact of different activities engaged in during park use on positive mental health was examined. The average physical activity level of the sample was 92.7 min of moderate to vigorous physical activity per day. Park users were more active in all forms of physical activity, except transport walking, than non-users. The presence of a park within 500 m from home and park use were significantly associated with total physical activity. Physical activity in parks significantly restored visitors' moods and energy levels, and interaction with nature brought mental health benefits in terms of relaxation and self-perceived confidence. Overall, this study found a positive correlation of urban parks with public physical activity and positive mental health benefits. However, further research is needed to improve the understanding of this relationship in the context of China.

The rapid expansion of urbanization has caused land cover change, especially the increasing area of impervious surfaces. Such alterations have significant effects on the soil ecosystem by impeding the exchange of gasses, water, and materials between soil and the atmosphere. It is unclear whether impervious surfaces have any effects on soil bacterial diversity and community composition. In the present study, we conducted an investigation of bacterial communities across five typical land cover types, including impervious surfaces (concrete), permeable pavement (bricks with round holes), shrub coverage (Buxus megistophylla Levl.), lawns (Festuca elata Keng ex E. Alexeev), and roadside trees (Sophora japonica Linn.) in Beijing, to explore the response of bacteria to impervious surfaces. The soil bacterial communities were addressed by high-throughput sequencing of the bacterial 16S rRNA gene. We found that Proteobacteria, Actinobacteria, Acidobacteria, Bacteroidetes, Chloroflexi, and Firmicutes were the predominant phyla in urban soils. Soil from impervious surfaces presented a lower bacterial diversity, and differed greatly from other types of land cover. Soil bacterial diversity was predominantly affected by Zn, dissolved organic carbon (DOC), and soil moisture content (SMC). The composition of the bacterial community was similar under shrub coverage, roadside trees, and lawns, but different from beneath impervious surfaces and permeable pavement. Variance partitioning analysis showed that edaphic properties contributed to 12% of the bacterial community variation, heavy metal pollution explained 3.6% of the variation, and interaction between the two explained 33% of the variance. Together, our data indicate that impervious surfaces induced changes in bacterial community composition and decrease of bacterial diversity. Interactions between edaphic properties and heavy metals were here found to change the composition of the bacterial community and diversity across areas with different types of land cover, and soil properties play a more important role than heavy metals.