An experiment was conducted to study the effects of storage layer and plant selection on the evapotranspiration of green roofs quantitatively. By setting 4 pilot green roofs designed with different structures and different vegetation, the variation of evapotranspiration (ET), soil moisture content and the corresponding weather conditions were monitored and recorded. The results show that, for both of the green roofs vegetated with Sedum lineare and Callisia repens, the water evaporated from the storage layer plays the role in the recharge of the moisture content of the upper soil layer. In addition, it shows a positive correlation between the initial soil moisture content and daily evapotranspiration in varying degrees during drought periods. The setting of storage layer would increase the evapotranspiration of a green roof. However, the correlation level of the green roof vegetated with Sedum lineare is lower than that with Callisia repens, due to its complexity and particularity of the crassulacean acid metabolism (CAM) mode, and the hourly evapotranspiration fluctuates greatly. Different from Callisia repens, the stomas would close when the solar radiation is very strong to reduce the amount of transpiration and retain water. It would provide a theoretical basis for the assessment of ecological benefits on evapotranspiration of green roofs.

In view of the problem that the non-point source pollutants had different accumulation characteristics on urban complex different underlying surfaces, the research took Changzhou central city as an example, collected 64 samples of surface pollutants on residential, industrial, traffic, commercial and cultural lands, tested the contents of SS, ammonia nitrogen and total and dissolved COD, TP, TN of surface pollutants, analyzed the accumulation characteristics of surface pollutants on different urban lands and the seasonal differences among residential and traffic lands. The results showed that the cumulative intensities of pollutants on roads were generally higher than other lands, especially SS and the total COD, with 59004.5 and 11179.7 mg/m² respectively. The cumulative intensities of dissolved pollutants on commercial lands were highest. The cumulative intensities of pollutants on cultural, residential and industrial lands were low. The cumulative intensities in October 2014 (autumn) and March 2015 (spring) had significant seasonal differences on roads. Compared with autumn, the average cumulative intensities of SS in spring were reduced by 7.7%, while total TN and dissolved COD, TN, TP and ammonia nitrogen were increased by 3.3%, 49%, 85%, 61% and 200%. The cumulative intensities had no seasonal differences on residential lands. The average ratios of grainy to total COD, TP and TN were 86.5%, 85.1% and 71.1%, which indicated that the main pollutants were adsorbed on the particulate matters, and more urban cleaning helped reduce urban non-point source pollution. The average contents of COD and TN per unit mass of particulate matters on commercial lands were higher than that on the other lands with 532.6 mg/g and 17.5 mg/g, while that on roads were lower than that on the other lands with 212.2 mg/g (COD), 0.86 mg/g (TP) and 2.9 mg/g (TN).