Abstract

Lead colloids—particles between 0.001 and 1 µm—present unique challenges for maintaining drinking water quality. Most of the published literature on lead in drinking water adopts a threshold for soluble lead of <0.45 µm, yet strong evidence of lead colloids occurring below this threshold has been reported across North America and Europe. This highlights the potential to misclassify colloidal lead as soluble. Remedial actions taken to reduce soluble lead concentrations can differ from those used to target colloidal lead, and in some cases may exacerbate the problem. Concentrations of colloidal lead are difficult to measure and to predict from water quality data. Nevertheless, advances in analytical techniques have allowed for more precise identification and characterization of lead colloids and their interactions with other compounds in drinking water. Analytical cost or expertise may be a barrier to utilizing some of these techniques. A critical analysis, weighing practicality and data quality, of the strengths and weaknesses of these methods is presented. This review identifies and discusses four key factors that promote colloidal lead formation and mobility in drinking water: natural organic matter, adsorption of lead to colloidal iron particles, precipitation with orthophosphate, and complexation or dispersion by sequestrants. This review also summarizes previous observations of lead colloids originating from the corrosion of drinking water distribution system and premises plumbing components and evaluates the use of colloidal analysis as a diagnostic tool. Despite the challenges and need for further research, colloidal analysis is a useful tool to inform better lead mitigation strategies.

摘要

铅胶体——粒径介于 0.001 和 1 µm 之间的颗粒——对维持饮用水质量提出了独特的挑战。大多数已发表的关于饮用水中铅的文献都采用 <0.45 µm 的可溶性铅阈值，但北美和欧洲报告了铅胶体低于该阈值的有力证据。这突出了将胶体铅错误分类为可溶性铅的可能性。为降低可溶性铅浓度而采取的补救措施可能与针对胶体铅的措施不同，在某些情况下可能会加剧问题。胶体铅的浓度很难从水质数据中测量和预测。尽管如此，分析技术的进步使得铅胶体及其与饮用水中其他化合物的相互作用更加精确的鉴定和表征成为可能。分析成本或专业知识可能是使用其中一些技术的障碍。对这些方法的优缺点进行了批判性分析，权衡了实用性和数据质量。本综述确定并讨论了促进饮用水中胶体铅形成和流动性的四个关键因素：天然有机物、铅对胶体铁颗粒的吸附、正磷酸盐沉淀以及螯合剂的络合或分散。本综述还总结了先前对源自饮用水分配系统和房屋管道部件腐蚀的铅胶体的观察，并评估了胶体分析作为诊断工具的用途。尽管存在挑战和需要进一步研究，但胶体分析是一种有用的工具，可以为更好的铅缓解策略提供信息。