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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 (AlPO 4 ·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 μg 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 μm) phosphorus with increasing aluminum and an accompanying increase in particulate lead and phosphorus (>0.45 μm).

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ABSTRACT. Changes in clutch and egg size in many avian species have been linked to seasonal variation, female physiological state, and laying date during breeding season. These reproductive variables have also been linked to population status and habitat variables. Recent declines in Herring Gull (Larus argentatus) populations in the Atlantic region may be associated with environmental changes, fishery activities, or natural species interactions and fluctuations. We studied variability and trends in Herring Gull egg, clutch, and population size at a cluster of three islands of the Grand Manan Archipelago in the Bay of Fundy, Canada. A generalized linear model investigating variability in Herring Gull egg volume over a 28-year period (1988 to 2015) showed increasing egg volume since a low in 2000, significant positive correlations with regional fisheries landings, and weak interactions with sea surface temperature and the winter North Atlantic Oscillation (NAO) index. Herring Gull egg size decreased by 11.6% from 1988 to 2000, but both egg size and clutch size have increased significantly since 2001. A 2015/2016 population estimate of the three islands showed a 36% decline in Herring Gull numbers since 2001. Changes in annual and seasonal availability of various fishery related food sources, specifically decreasing Atlantic herring (Clupea harengus) and groundfish landings and increasing American lobster (Homarus americanus) landings, may be linked to these increases in reproductive variables. However, it appears that other factors may be influencing the declining gull population because despite increased availability of alternative food sources and increased clutch size and egg volume, there has been no documented increase in abundance. Interspecific interactions, anthropogenic activities, and climatic variability may also have a role in these population dynamics. Variabilité de la taille des oeufs et baisse des populations chez le Goéland argenté en relation avec la pêche commerciale et les conditions climatiquesRÉSUMÉ. Les changements dans la taille des oeufs et de la ponte chez plusieurs espèces d'oiseaux ont été associés aux variations saisonnières, à l'état physiologique des femelles et à la date de ponte pendant la saison de nidification. Des diminutions récentes des populations de Goélands argentés (Larus argentatus) dans la région de l'Atlantique seraient peut-être liées à des changements environnementaux, aux activités de pêche ou aux interactions et fluctuations naturelles des espèces. Nous avons étudié la variabilité et la tendance de la taille des oeufs, de la ponte et des populations dans un groupe de trois îles dans l'archipel de Grand Manan dans la baie de Fundy, Canada. Un modèle linéaire généralisé conçu pour examiner la variabilité du volume des oeufs de ce goéland sur une période de 28 ans (1988 à 2015) a révélé un volume croissant depuis un minimum atteint en 2000, une corrélation positive significative avec les débarquements de pêche commerciale régionale et de faibles interactions avec la ...

Lead is a neurotoxin and an environmental contaminant. Many jurisdictions require that it be monitored in drinking water, especially where lead plumbing remains in use. But seasonal variation in lead concentrations can bias monitoring programs if it is not understood and accounted for. Here, we describe an unexpected pattern in lead release to drinking water, identified through point-of-use sampling. The median lead concentration representing paired first-draw water samples—collected in multiple years—was 46% lower in October compared to February. Seasonal variation in orthophosphate, pH, and alkalinity accounted for at least some of this pattern and predicted lead solubility in October was 76% of that in February. But seasonally varying aluminum may also have been a factor; as a supplement to the field study, we evaluated the effects of aluminum residual, temperature, and orthophosphate concentration on lead release from lead coupons. Increasing the orthophosphate concentration from 0–1 mg/L decreased lead release by 34%, and increasing water temperature from 4–21˚C increased lead release by 120%. Increasing the aluminum concentration from 20–500 µg/L increased lead release by 41% and modified the effect of orthophosphate, rendering it less effective in controlling lead release. We attributed this to a decrease in the concentration of soluble (<0.45 µm) phosphorus with increasing aluminum and an accompanying increase in particulate lead and phosphorus (>0.45 µm). These data suggest that residual aluminum from coagulation may interfere with orthophosphate corrosion control, especially when the treatment process does not allow the pH of minimum aluminum hydroxide solubility to be targeted.