Survey of ecological environmental conditions and influential factors for public parks in Shanghai

Urban public parks provide a recreational environment for residents, hence more and more citizens would spend time in parks, especially elderly and kids. Therefore, it is important to evaluate the quality of ecological environment inside parks. Therefore, this study conducted the first measurements in ten public parks of Shanghai to investigate heavy metals in air, soil and leaf, growth parameters of leaf, and ambient PM_2.5 and black carbon (BC) concentrations. Results showed Al and Mg appeared the highest in air. Cr, Cu, Mn and Zn were dominating in soil. Ca and Mg were much greater in leaves. It was concluded geographical locations were major reasons to explain the level of heavy metals, which mainly came from vehicle emissions. A small portion was attributing to chemical industries nearby. PM_2.5 concentrations ranged from 0.01 mg/m³ to 0.10 mg/m³, which met up level I and level II of air quality standard in China. BC concentrations ranged from 1000 ng/m³ to 6000 ng/m³. Via comparing the correlation between photosynthesis and PM_2.5, as well as chlorophyll content and PM_2.5, it was concluded that chlorophyll can be regarded as an indicator for assessing air quality, but not photosynthesis. Unexpectedly, a positive correlation was observed between the stomatal conductance and PM_2.5 as well as BC, which might be attributed to plants resisting the ambient stress. The results of this study can be used for assessments of air quality and health exposure inside parks, and also could provide urban policy maker with scientific evidences for urban park planning.