Hatam Fatemeh, Blokker Mirjam, Doré Evelyne, Prévost Michèle
Industrial Chair on Drinking Water, Department of Civil, Geological and Mining Engineering, Polytechnique Montréal, CP 6079, Succ. Centre-ville, Montréal, QC H3C 3A7, Canada.
KWR Watercycle Research Institute, Groningenhaven 7, 3433 PE Nieuwegein, the Netherlands.
Sci Total Environ. 2023 Jun 25;879:162975. doi: 10.1016/j.scitotenv.2023.162975. Epub 2023 Mar 23.
Water conservation measures are increasing in response to regulatory requirements addressing the need for lower environmental footprint and in response to water shortages. In households with lead service lines (LSLs), lowering consumption can adversely impact lead release as it will increase stagnation. Using a lead dissolution model and data from extensive pilot studies on excavated LSLs, the impact of adaptation to different water conservation strategies on dissolved lead contamination at the kitchen tap is assessed under three water qualities and three LSL lengths (3, 14 and 30 m) using hydraulic and water quality modelling. Consumers' behavioural variability is also assessed based on integration of EPANET and results of the stochastic water demand model SIMDEUM. Demand reduction increased the dissolved lead concentrations (Pb) at the end of the LSL with mean values ranging from 28.4 to 63.3 μg/L (without corrosion control) and from 4.6 to 9.9 μg/L with corrosion control (addition of orthophosphate and pH adjustment). Adding orthophosphate (1 mg P/L) to the water reduces the mean Pb values at the kitchen tap from 7.1 μg/L to 1.2 μg/L for a high water demand scenario and from 31.2 to 4.9 μg/L for a low water demand scenario. Finally, the Integrated Exposure Uptake Biokinetic (IEUBK) model is used to predict the potential blood lead levels (BLLs) for children aged 0-84 months. Results showed that the orthophosphate addition of only 1 mg P/L can significantly decrease the proportion of children with a BLL >5 μg/dL, from 82 % to 17 %, under the most extreme water conservation scenario studied, using the 90th percentile of Pb concentrations during usage at kitchen tap. Wide variations of Pb concentrations at the kitchen tap were calculated at times of use over a week (up to 155 μg/L in lower demand scenarios, without corrosion control) showing evident limitations of single random daytime sampling.
为响应降低环境足迹的监管要求以及应对水资源短缺问题，节水措施日益增多。在有含铅服务管道（LSLs）的家庭中，降低用水量可能会对铅释放产生不利影响，因为这会增加水的停滞时间。利用铅溶解模型以及对挖掘出的LSLs进行的大量试点研究数据，通过水力和水质建模，在三种水质和三种LSL长度（3米、14米和30米）条件下，评估了采用不同节水策略对厨房水龙头处溶解铅污染的影响。还基于EPANET和随机用水需求模型SIMDEUM的结果整合，评估了消费者行为的变异性。减少用水量会增加LSL末端的溶解铅浓度（Pb），平均值在无腐蚀控制时为28.4至63.3微克/升，有腐蚀控制（添加正磷酸盐和调节pH值）时为4.6至9.9微克/升。在高用水需求情景下，向水中添加正磷酸盐（1毫克磷/升）可将厨房水龙头处的平均铅值从7.1微克/升降至1.2微克/升，在低用水需求情景下可从31.2微克/升降至4.9微克/升。最后，使用综合暴露吸收生物动力学（IEUBK）模型预测0至84个月儿童的潜在血铅水平（BLLs）。结果表明，在所研究的最极端节水情景下，仅添加1毫克磷/升的正磷酸盐可使血铅水平>5微克/分升的儿童比例从82%显著降至17%，采用厨房水龙头使用期间铅浓度的第90百分位数。计算得出一周内用水时厨房水龙头处铅浓度变化很大（在低需求情景下无腐蚀控制时高达155微克/升），这表明单次随机白天采样存在明显局限性。
