Research On The Response Mechanism Of Tire Wear Particle Input And The Operating Efficiency Of Bioretention System

Tire wear particles generated by vehicle tires rubbing against the road are heavily gathered around the road.After the initial rainfall,the tire wear particles flowed into the bioretention system along with the storm run-off,resulting in unknown effects on the operation efficiency of the system.In this study,the effects of different concentrations of tire wear particles on the operational efficiency of the system were investigated based on the approach from macroscopic to microscopic,and from vegetation layer to microbial function of the system for the purpose of providing the theoretical basis and reference on the effects of tire wear particles on the bioretention system.(1)Study on the macroscopic operating efficiency of the system showed that the input of tire wear particles weakened the infiltration rate of the system by clogging the soil pores(OR: 1.1555 mm/min>C0.1: 1.0187 mm/min>C1: 0.8777 mm/min>C10:0.7390 mm/min>C100: 0.5792 mm/min),and the retention rate of the system was negatively correlated with the input concentration of tire wear particles(-0.359**).The removal efficiency of ammonia nitrogen in the system was negatively correlated with the input concentration of tire wear particles,while the removal efficiency of total phosphorus,phosphate,total organic nitrogen and the content of various organic matter in the system increased with the input concentration of tire wear particles.(2)Study on the microecology of the system showed that tire wear particles inhibited the nitrification potential and promoted the denitrification potential and the microbial diversity of the system.In terms of nitrogen metabolism pathway,the experimental group increased the 1.7.1.4 enzymes that converted nitrite nitrogen into ammonia nitrogen,and NIT-6 enzymes that converted nitrate nitrogen into ammonia nitrogen,and decreased 6.3.4.16 enzymes that converted ammonia nitrogen into carbamoyl-p,compared with the control group.For the oxidative phosphorylation pathway,the experimental group increased eight enzymes,namely Ndufs4,Ndh H,Ndh D,gamma,B,C,E and a,compared with the control group.In the phosphate and phosphite metabolic pathway,the experimental group increased only one enzyme coded 2.7.8.1,compared with the control group.The intergroup occupancy of systemic nitrogen metabolism decreased with the increase of tire wear particle input concentrations.Low concentrations of tire wear particles promoted carbon metabolism,while high concentrations inhibited it.Among the intergroup correlations of systemic KEGG functions,oxidative phosphorylation and nitrogen metabolism were significantly correlated with the input of tire wear particles(p<0.001).(3)Study on the system plants showed that the root lengths of the plants shortened by 62.92 cm,102.40 cm,102.38 cm,and 189.77 cm with the increasing input concentrations of tire wear particles.While the control group had a positive growth of 15.77 cm.According to the photosynthetic rates,the C0.1 system did not significantly inhibit plant growth state,the C1 system showed the earliest inhibitory effect,and the C10 and C100 systems were the latest to show the stress effect on plant growth state.Tire wear particles promoted plant respiration rate(0.223),intercellular CO2 concentration(0.014)and plant vapor pressure difference(0.09),and suppressed the net photosynthetic rate(-0.192),leaf temperature(-0.183),leaf stomatal conductance(-0.176)and transpiration rate of plants(-0.136).There is a significant correlation between tire wear particles and the operating efficiency of the bioretention system.Only by analyzing and managing the input of tire wear particles according to local conditions,can the operation efficiency of the system be effectively improved.