 Hello, everyone. I'm Shanyin, I'm from Shanghai Jordan University. Today I wanna share with you some work we have done in the last few years. The title, yeah, yeah, just like this. And why I chose this title? I think, you know, the answer must be true. The green infrastructure actually could and not to rate urban air pollution. So that's why we are gathered here today. But what's the more important is how we could prove this and make it better. Now this is a first air pollution. I won't talk about PM 2.5 and polycylic aromatic hydrocarbons, pH as a typical air pollutants in the city. They are mainly man-made pollutants, very stable and they make it long distance with harmful effects to urban residents. Urban air pollutants could deposit from air to plants, soil and water by dry and white depositions. And sometime back to the air by resuspension and release. The vegetation or plants could play an important role in the biogeochemical cycling. The dry deposition on leaves and absorptions are the key roles to remove air pollution. So what's the main influence of factors between air pollutants and the vegetation? A study can quote four aspects. Let's see that including tree species pollutants, mitralogical factors and plant community. If we look at, we could say tree species actually means functional trees of trees and leaves, which we could call this internal factors. And the pollutants and the mitralogical factors are external conditions. These two interact with each other at the surface of leaves and branches. And also with a well-designed plant community, that's how we could have a cleaner city and a human wellbeing. So as I said, the questions are concerned. We're concerned about the urban forest and air pollutants should be seen from different scales and have different questions. In the internal and external factors, in the first scale, we focus on the leaf and tree species. The question is, which tree species has better capacity to remove air pollutants? And the second scale, we focus about the plant community. What are the effects of landscaping design on pollutants removal? And the third scale, we should look at the whole urban area, how to play land use types to help improve urban air quality. So let's start with the first scale. What happened in trees and leaves? There are also two questions we would like to answer. So how do leaves absorb aeroparticles? And which tree species should be selected? In our study, we choose 14 type of tree species in Shanghai with four conifers and 10 broadleafed. Leaves and branches are both simple. We use a winterno method and a smoke chamber method to determine the PM2.5 dry deposition velocity on leaves and branches and 3D x-ray microscope is used to observe where are the particulate matters on the surface and in the leaves? So let's answer the first questions. How do leaves absorb particles? As the figure shows, the coagulation effect happened on the leaves, which means small particles combined and accumulate into large sized particles. And that helps leaves to absorb or fix more particles in the air. And from the right finger, the functional trees of leaves, we found that the single leaf area specifically for weight and the surface free energy were the main influence of factors of particle deposit on leaves. For the question two, which tree species should be selected? This is the PM2.5 dry deposition velocity of 14 tree species in Shanghai. We could see the conifer trees usually had a higher capacity than broadleafed trees, but it does not mean these trees are suitable everywhere and every time. I mean, the leaf areas of conifers less than broadleafed trees. So this results just provide an alternative for tree species selection. Just as Wendy said before, right species in right places. And the second scale is from what we could see and use. They are different landscape design, but what is a good design which could beneficial to air pollution removal? That's what we want to answer in this part. We are looking at the gray space along an urban avenue. We sampled and test the PM concentration in the gray space and outside it. The results show that the concentration in and over the gray space were actually lower compared to the roadside. The right finger shows that the larger the conductivity is, the more noticeable particle purification will be. But you know the trees would grow, they need space to grow. So if you plant a tree in a very high density, they will die in future. So we think the best conductivity should not too low or too high. The best range should be 70% to 85% for the particles removal. And based on what we found in last slide, we tried to make some landscape design of urban gray space along the road. In 300 square meters gray space, there should be 10 to 12 trees, 20 large shops, and 50 small shops. The reach of trees, large shop, and small shops should be one to two to five. The structure of vegetation could achieve the conductivity 70% and the shell belt velocity 30%. So the third scale is the scale of the whole urban area, like what I showed before. If we know how the air pollution distributed, then what we could do on urban forestry planning and design. So we take Shanghai's aero PAH pollution as an example. We sampled for 84 sites all over Shanghai, determining the PAH concentrations and also recorded the land use type of every simple insight in different buffers, water, road, farmland, residential, grassland, business, and woodland. The reach of each land use type was calculated and associated with the pollutant concentrations. We would like to answer two questions here. One, which land use types are the main source of PAH and which ones are main sinks? The second, could more green space and waters factually improve the urban air quality? This is the PAH distribution. The distribution showed that the PAH concentrations is higher in urban area than sub-urban and rural area. For the distance and the population granted, the PAH concentration decreased with the distance getting further from the city center. But the PAH concentration positively correlated with the population density and the right finger shows. The results implied that the humans activities were the main source of PAH in urban areas. And it's very funny that the housing price in Shanghai is very expensive, especially in urban area. It seems that people who live in the city center must be very rich, but they have to suffer with serious air pollution. And the relationship between land use type and the PAH concentration would also prove what I said. We could see from the left finger, the right circles are positively related, which means these land use types are the source of PAHs, while the blue circles are negatively related. So they are the sink of PAH, or they could absorb PAH. So we could say the road, industry, residential and business areas are the source. Humans activities resulted to higher air pollution. However, the woodland, water and farmland are the sinks of PAH, but the influential range are also different. The PAH emissions from the road, residential and business are mainly high molecular weight compounds, such as cooking, traffic emissions had a very long migration distance, but wood and waters would absorb the pH very nearby. They seem to be a very effective ways to improve air quality. So I would like to conclude myself here. The green infrastructures, including urban forest, farmland, waters can effectively elevate urban air pollution. We have to balance the land use type using more green infrastructures to make the city cleaner. So for the future research, I think the critical zone research is very popular here in the right time. And I think the urban forestry links all the urban critical zone elements and we should look very careful about it in future. So that's my talk today. Thank you so much.