Seasonal Lead Release into Drinking Water and the Effect of Aluminum

Monitoring lead in drinking water is important for public health, but seasonality in lead concentrations can bias monitoring programs if it is not understood and accounted for. Here, we describe an apparent seasonal pattern in lead release into orthophosphate-treated drinking water, identified through point-of-use sampling at sites in Halifax, Canada, with various sources of lead. Using a generalized additive model, we extracted the seasonally varying components of time series representing a suite of water quality parameters and we identified aluminum as a correlate of lead. To investigate aluminum's role in lead release, we modeled the effect of variscite (AlPO4 center dot 2H(2)O) precipitation on lead solubility, and we evaluated the effects of aluminum, temperature, and orthophosphate concentration on lead release from new lead coupons. At environmentally relevant aluminum and orthophosphate concentrations, variscite precipitation increased predicted lead solubility by decreasing available orthophosphate. Increasing the aluminum concentration from 20 to 500 mu g L-1 increased lead release from coupons by 41% and modified the effect of orthophosphate, rendering it less effective. We attributed this to a decrease in the concentration of soluble (<0.45 mu m) phosphorus with increasing aluminum and an accompanying increase in particulate lead and phosphorus (>0.45 mu m).

Automated summary

Monitoring lead concentration in drinking water is crucial for public health. Research suggests that there is a seasonal pattern in lead release, and aluminum is identified as a correlate of lead. The precipitation of variscite increases lead solubility, while higher aluminum concentrations enhance lead release and weaken the effect of orthophosphate.