典型山地城市雨水径流污染负荷时空分布

Spatial and Temporal Distribution of Rainwater Runoff Pollution Load in a Typical Mountain City

为了了解山地城市雨水径流污染特征,选取坡度大、绿地比率高的典型山地区域,研究在各降雨等级条件下、不同下垫面的初期雨水污染物时空分布特性及不同污染物指标间相关性。结果显示:径流污染在降雨初期有最大值,其后各污染指标随时间变化迅速下降,且雨强越大趋势越明显;不同下垫面初期雨水径流水质优劣顺序为砖石>硬化铺装>绿地,不同雨强初期雨水径流水质优劣顺序为中雨>大雨>暴雨;研究区域内地表径流中总氮(TN)主要以溶解态输出,总磷(TP)则以颗粒态输出;绿地的产流中颗粒态氮磷要显著高于其他下垫面,暴雨下雨水径流中颗粒态氮磷也显著高于其他雨强;在不同雨强及下垫面条件下,悬浮颗粒物(SS)与高锰酸盐指数(CODMn)、TP、TN、溶解性总磷(TDP)、溶解性总氮(TDN)均高度正相关。说明山地型绿地存在一定水土流失情况,污染负荷较集中于初期雨水中,而且随雨强增大更加明显,SS对各污染物浓度的变化具有显著影响。因此,控制初期雨水中SS含量是降低山地城市雨水径流污染物含量的有效途径。

In order to know the characteristics of rainwater runoff pollution in mountain city,a typical mountain area with large slope and high green space ratio was selected to study the spatial and temporal distribution characteristics of pollutants in initial rainwater under different rainfall levels and different underlying surfaces,and to study the correlation between different pollutant indexes.The results showed that runoff pollution had the maximum value at the beginning of rainfall,then the pollution indexes decreased rapidly with time,and this phenomenon was strengthened by the heavier rain.The pollution order of rainwater runoff on different underlying surfaces from slight to serious was brick>hardened pavement>green space,and the pollution order of runoff water quality in the early stage of different rainfall intensities was moderate rain>heavy rain>rainstorm.The total nitrogen(TN)in surface runoff in the study area was mainly dissolved,while the total phosphorus(TP)was mainly particulate.The particulate nitrogen and phosphorus in runoff of green place was significantly higher than that of other underlying surfaces,and the particulate nitrogen and phosphorus in rainwater runoff under rainstorm was also significantly higher than that of other rainfall intensities.Under different rainfall intensities and underlying surface conditions,suspended particulate(SS)matter was highly positively correlated with permanganate index(COD Mn),TP,TN,total dissolved phosphorus(TDP)and total dissolved nitrogen(TDN).It shows that there is a certain degree of soil erosion in mountainous green space,and the pollution load is more concentrated in the initial rainwater,and it is more obvious with the increase of rainfall intensity.SS has a significant impact on the concentration of pollutants.Therefore,controlling the SS content in the initial rainwater is an effective way to reduce the pollutant content of rainwater runoff in mountainous cities.