将：上述监测结果验证了2号餐厅在日间及夜晚部分时段的流量优势性且其餐厨行为下产生的污水中34S与排水片区末端污水中34S的高度相关性这解释了排水片区末端污水中34S的变化规律：其在全监测周期中整体均高于自来水本底中34S水平仅于夜间部分时段发生相较本底的指标削减。324不确定度评定基于排水片区末端的污水水质指标不确定度评定公式本文实验条件下其污水34S的不确定度结果如所示表5。统计结果显

The monitoring results above have verified the flow advantage of Restaurant 2 during certain time periods in both daytime and nighttime, and the high correlation between the δ34S in the wastewater generated from its kitchen behavior and the δ34S in the wastewater at the end of the drainage area. This explains the variation pattern of δ34S in the wastewater at the end of the drainage area, which was consistently higher than the δ34S level in tap water throughout the monitoring period, with only a reduction in certain nighttime periods compared to the baseline. The uncertainty assessment in Section 3.2.4, based on the uncertainty assessment formula for wastewater quality indicators at the end of the drainage area, shows the uncertainty results for δ34S in the wastewater under the experimental conditions in this paper, as shown in Table 5. The statistical results indicate that the uncertainty range of δ34S in the wastewater at the end of the drainage area corresponds to three consecutive monitoring cycles, ranging from 0.36‰ to 0.59‰, showing a medium level of uncertainty stability overall.

In conclusion, this paper conducted experimental research on the variation pattern of δ34S in the wastewater at the end of the drainage area under different water use behaviors in the study area. The following conclusions were drawn: (1) δ34S is less affected by different water use behaviors, and it shows good stability under various water use behaviors. Except for the 64.69% increase caused by kitchen behavior, the relative change range of δ34S compared to tap water under behaviors such as washing, showering, toilet flushing, and dishwashing was -14.37% to 5.62% on average. (2) The fluctuation amplitude of δ34S in the wastewater at the end of the drainage area relative to the tap water baseline is small, with an average relative change of 25.99%. The overall variation trend of δ34S with time is small and stable, and the daily fluctuation pattern has certain reproducibility. (3) δ34S shows good stability under different water use behaviors in the drainage households and in the wastewater at the end of the drainage area. Therefore, δ34S is suitable as a water quality characteristic factor for pipe network diagnosis