不同植被绿色屋顶径流水质年际变化特征

绿色屋顶是海绵城市建设的重要措施之一，近年来逐渐得到广泛关注.为探究植被和使用时长对绿色屋顶径流水质的影响，于北京市区搭建了3种不同植被类型佛甲草（Sedum lineare）、大花马齿苋（Portulaca grandiflora）和无植被（对照）]的绿色屋顶.根据2017～2019年植物生长情况、雨季雨水和绿色屋顶径流水质的长期监测，定量分析不同植被绿色屋顶径流水质的年际变化特征.结果表明，相较雨水，3种绿色屋顶在监测期内均是NH⁺₄-N的汇，浓度平均削减率在50.1%～79.2%之间，但均是PO^3-₄-P、 DCr、 DCu和DNi的源；佛甲草和大花马齿苋绿色屋顶在2017年是NO^-₃-N的汇，浓度平均削减率分别为71.4%和99.5%,在2018和2019年是NO^-₃-N的源，而对照绿色屋顶在监测期均为NO^-₃-N的源；绿色屋顶的植被类型和使用时长显著影响其径...

Inter-annual Changes in Runoff Quality from Green Roofs with Different Vegetation

As an important measure of the sponge city, green roofs have received extensive attention in recent years. To investigate the inter-annual changes in runoff quality of green roofs with different vegetation types, three green roofs with different vegetation cover (Sedum lineare, Portulaca grandiflora, and a non-vegetated control) were set up in Beijing. The influences of vegetation and monitoring period on runoff quality from the green roofs were evaluated using the plant growth characteristics and the quality of rainwater and runoff from the green roofs during the rainy season of 2017-2019. The results showed that all three green roofs were the sinks of NH₄⁺-N, and the average mass concentration reduction rates were between 50.1% and 79.2%. However, all three green roofs were sources of PO₄^3--P, DCr, DCu, and DNi. The green roofs covered with S. lineare and P. grandiflora were sinks of NO₃^--N in 2017, and the average mass concentration reduction rates were 71.4% and 99.5%, respectively, but they became sources of NO₃^--N in both 2018 and 2019. However, the non-vegetated control was the source of NO₃^--N in all three rainy seasons. Both vegetation type and length of monitoring period had significant effects on the mass concentrations of NO₃^--N, PO₄^3--P, DNi, and DCu in runoff from the green roofs (P<0.05) but had no significant effects on the mass concentrations of NH₄⁺-N and DCr in runoff from the green roofs (P>0.05). In 2017-2019, the mass concentrations of NO₃^--N in runoff from the non-vegetated control and the green roofs covered by S. lineare and the mass concentration of PO₄^3--P in runoff from the green roof covered by P. grandiflora increased yearly. The mass concentrations of DNi and DCu in runoff from all three green roofs increased in 2018 but dropped in 2019. Among the green roofs with different vegetation types, the green roof covered by P. grandiflora showed better NO₃^--N retention capacity than that of the other green roofs but may have increased the concentrations of PO₄^3--P, DNi, and DCu in the runoff.