ABSTRACT

THIS STUDY EXAMINED THE MICROBIAL CONTAMINATION CHARACTERISTICS OF THREE DIFFERENT ROOF MATERIALS (GREEN ROOF, METAL ROOF, AND CONCRETE ROOF) DURING RAINFALL EVENTS. THROUGH RUNOFF SAMPLES COLLECTED FROM MULTIPLE RAINFALL EVENTS IN THE EXPERIMENTAL RAINWATER COLLECTION SYSTEM MODEL, THE POLLUTION CHARACTERISTICS OF TOTAL COLONY-FORMING UNITS, ESCHERICHIA COLI, AND TOTAL COLIFORMS WERE ANALYZED IN COMBINATION WITH WATER QUALITY PARAMETERS SUCH AS PH, TURBIDITY, CHEMICAL OXYGEN DEMAND (COD), AND ELECTRICAL CONDUCTIVITY. THE STUDY USING THE WILCOXON SIGNED RANKS TEST AND FOUND THAT THE MICROBIAL CONTAMINATION LOAD OF INITIAL RAINWATER WAS SIGNIFICANTLY HIGHER THAN THAT OF SUBSEQUENT RUNOFF. THE MANN-WHITNEY U TEST WAS USED TO COMPARE THE DIFFERENCES IN MICROBIAL CONTAMINATION CAUSED BY DIFFERENT ROOF MATERIALS. THE RESULTS SHOW THAT THE METAL ROOF PERFORMED THE BEST IN TERMS OF MICROBIAL CONTROL, WHILE THE GREEN ROOF HAD THE POOREST MICROBIAL CONTROL EFFICIENCY. THE SPEARMAN CORRELATION ANALYSIS REVEALED THAT TURBIDITY AND CONDUCTIVITY WERE SIGNIFICANTLY POSITIVELY CORRELATED WITH MICROBIAL CONTAMINATION, CONFIRMING THAT POLLUTANTS AND NUTRIENT IONS ARE CORE FACTORS DRIVING MICROBIAL PROLIFERATION. MOREOVER, THE METAL ROOF EXHIBITED OUTSTANDING DISINFECTION EFFICACY UNDER DIRECT SUNLIGHT (MICROBIAL SURVIVAL RATE 0.00003% - 0.0004%), ITS HIGH REFLECTIVITY AND THERMAL CONDUCTIVITY WORKING IN SYNERGY WITH UV RADIATION TO DESTROY MICROBIAL DNA, WHILE UNDER SHADED CONDITIONS, THE STERILIZATION EFFICIENCY DECREASED BY APPROXIMATELY 100 TIMES. THE STUDY SUGGESTS THAT METAL ROOFS SHOULD BE PRIORITIZED FOR USE IN WATER QUALITY-SENSITIVE SCENARIOS. GREEN ROOFS NEED TO BE EQUIPPED WITH INITIAL RAINWATER RETENTION AND SUBSTRATE ANTIBACTERIAL IMPROVEMENT, AND CONCRETE ROOFS CAN ENHANCE THEIR ANTIBACTERIAL ABILITY THROUGH HYDROPHOBIC SURFACE TREATMENT. THE STUDY PROVIDES A SCIENTIFIC BASIS FOR IMPROVING THE DESIGN OF RAINWATER COLLECTION SYSTEMS IN MACAU, ENRICHING THE RESEARCH CASES OF ROOF RUNOFF POLLUTION IN TROPICAL COASTAL CITIES, AND IS OF GREAT SIGNIFICANCE FOR IMPROVING THE URBAN RAINWATER MANAGEMENT SYSTEM AND PROTECTING WATER ENVIRONMENTAL QUALITY. 本研究考察了三种不同屋顶材料（绿色屋顶、金属屋顶和混凝土屋顶）在降雨期间的微生物污染特征。通过在实验雨水收集系统模型中多次降雨事件所采集的径流样本，结合 PH 值、浊度、化学需氧量（COD）和电导率等水质参数，对总菌落形成单位、大肠杆菌和总大肠菌群的污染特征进行了分析。研究采用威尔科克森符号秩检验，发现初期雨水的微生物污染负荷显著高于后续径流。采用曼 - 惠特尼 U 检验比较了不同屋顶材料造成的微生物污染差异。结果表明，金属屋顶在微生物控制方面表现最佳，而绿色屋顶的微生物控制效率最差。斯皮尔曼相关性分析表明，浊度和电导率与微生物污染显著正相关，这证实了污染物和营养离子是驱动微生物增殖的核心因素。此外，金属屋顶在阳光直射下表现出卓越的消毒效果（微生物存活率 0.00003% - 0.0004%），其高反射率和热导率与紫外线辐射协同作用，破坏微生物 DNA，而在遮阴条件下，其杀菌效率降低约 100 倍。该研究建议，在水质敏感的场景中应优先使用金属屋顶。绿色屋顶需要配备初期雨水截留装置和基质抗菌改进措施，而混凝土屋顶可通过疏水表面处理来增强其抗菌能力。该研究为澳门雨水收集系统的设计改进提供了科学依据，丰富了热带沿海城市屋顶径流污染的研究案例，对于完善城市雨水管理系统和保护水环境质量具有重要意义。