Study On The Control Of Simulated Road Runoff And Water Quality By Biologic Detention System Constructed By Different Plants

The biological retention system can achieve the retention and purification of rainwater with the interaction of plants,osmotic matrix and microorganism,and in situ measures to reduce the flood peak flow and delay the location of flood peak,which are constructed by gravel layer,packing layer,planting soil layer,plant layer and aquifer.The paper simulates the pollutants of road runoff and road runoff,and carries out the control variable experiment under the same conditions of the biological detention facilities,and compares the study of the control of the simulated road runoff by the biological retention system constructed by the single plant and the combination plant of different plants.First,a comparative study of the single planting of Polygonum capitatum and Ophiopogon bodinieri var.pygmaeus and the combination of a combination with Achnatherum pekinense and Iris pseudacorus,and the drought tolerance and waterlogging tolerance of uncovered,Pine bark and vermiculite were compared.Secondly,we compare the control ability of biologic retention system constructed by planting types above to simulate runoff and water quality.Through the study,the plants which are resistant to waterlogging,drought tolerance and retention are screened,as well as the plants with higher control effect on the simulated runoff and water quality.The main results are as follows:(1)There was a significant difference between 5 indices in single plant planting and combined planting(P < 0.05).The best performance of drought tolerance was the combination of Polygonum capitatum and Achnatherum pekinense,of Ophiopogon bodinieri var.pygmaeus and Iris pseudacorus,of Achnatherum pekinense and Ophiopogon bodinieri var.pygmaeus.Pine bark,vermiculite,the differences of the 5 evaluation indexes between plant significantly(P < 0.05).Overall,performance of waterlogging tolerant of plants in vermiculite is better than pine bark,is better than that without covering.In addition,vermiculite,Polygonum capitatum,Ophiopogon bodinieri var.pygmaeus were planted with Achnatherum pekinense combination capacity of waterlogging tolerance optimal performance.(2)There was a significant difference between the 5 evaluation indexes of plants in single planting and combined planting before and after mulching.(P < 0.05).On the whole,the drought tolerance of plant combination was better than that of single planting,and the drought tolerance after adding vermiculite was better than that after adding pine tree,which was better than that of nocover.(3)The difference of the retention time between the single planting layer of different plants was significant(P < 0.05).With the increase of simulated runoff,the difference detained time decreased between the single planting and the combined planting of different plants,and the combination planting was better than the single planting,and the vermiculite was better than the pine bark after the vermiculite,which was better than that of the no cover.The difference of residence time between the whole system layer before and after covering is very significant(P <0.01).When the simulated road flow is 30 L,the retention time of the bark is 14 minutes to 22 minutes longer than that of the pine bark after the vermiculite is added,and the time of the tree bark is 25 to 50 minutes longer than that without the cover.(4)There was a significant difference in the retention of single plant layer when plants were planted and planted together,and when there was no mulch,there was a significant difference in the amount of single plant layer(P < 0.05).After adding vermiculite,the difference between the remaining amount of the simulated road flow rate of 30 L and 90 L was significant(P < 0.05),but the difference between the simulated road flow rate of 90 L and 170 L was not significant(P > 0.05).In general,vermiculite increased the overall level of single plant layer retention,and pine bark increased the largest single plant layer retention.The difference between the remaining amount of the whole system layer before and after the added cover was significant(P < 0.05).When the simulated runoff was 30 L,90L and 170 L,the difference between the remaining amount was not significant(P > 0.05),and the average retention rate was 21.51 L.(5)when the simulated runoff was 90 L,the difference between the runoff peak flow and the peak position of runoff and flood peak was significant(P < 0.05)before and after the adding of the mulch.The biological retention system constructed by the combination of Ophiopogon bodinieri var.pygmaeus and Iris pseudacorus could reduce the runoff peak flow rate of 17.01%,when no cover was covered,and the single planting and combined planting of the Ophiopogon bodinieri var.pygmaeuswere compared with the single planting and combination planting of Polygonum capitum,and the position of the delayed runoff peak was 9 minutes to 13 minutes.When the simulated runoff was 170 L,the difference between the runoff peak flow and the runoff peak position was significant(P < 0.05),and there was no significant difference between the bark and the vermiculite(P > 0.05).On the whole,vermiculite is slightly better than that of pine bark were better than no coverings.After adding vermiculite,single planting and combination planting of Ophiopogonbodinieri var.pygmaeus can reduce the flow peak flow of 0% to 7.84%,and can delay the runoff peak position of 4 minutes to 6 minutes.(6)The biological retention system of single plant and combination planting of different plants,the purification ability of single plant layer and whole system layer to total nitrogen,total phosphorus and chemical oxygen demand,and the performance of single plant and combination planting with Ophiopogon bodinieri var.pygmaeus is better than single planting and combination planting of Iris pseudacorus,and the performance of simulated runoff is 90 L.The difference of the total nitrogen purification percentage between the single plant layer and the whole system layer was very significant(P < 0.01).After adding vermiculite,the difference was better than that of the pine bark,which was better than that of no cover.The purification percentage of the total nitrogen can be increased by 13% after the bark and vermiculite in the single plant layer.The total nitrogen purification rate of the whole system layer can reach 86% when the total nitrogen is not covered,and the total nitrogen can be increased by 6% after adding the cover.The single plant layer of dwarf Ophiopogon japonicus and C.sinensis planted on the total nitrogen purification capacity showed the best performance when simulated runoff was 90 L,reaching 55%.The difference between the percentage of chemical oxygen demand of the single plant layer and the overall system layer before and after adding mulch is significant(P < 0.05).A single plant layer can purify total phosphorus 39% without covering.The whole system layer 23%,the percentage of up to 70% after purification the pine bark.