Use of pharmaceuticals and pesticides to constrain nutrient sources in coastal groundwater of northwestern Long Island, New York, USA

Abstract

In developed, non-agricultural, unsewered areas, septic systems and fertilizer application to lawns and gardens represent two major sources of nitrogen to coastal groundwater, in addition to atmospheric input. This study was designed to distinguish between these two possible nitrogen sources by analyzing groundwater samples for pharmaceutical residuals, because fertilizers do not contain any of these pharmaceuticals, but domestic wastewater commonly does. In addition, several herbicides and insecticides used in lawn treatment were analyzed as indicators of nitrogen delivery to groundwater from fertilizers. Groundwater samples were taken through piezometres at shoreline sites in unsewered areas surrounding Northport Harbor and in sewered areas adjacent to Manhasset Bay (hereafter referred to as "Northport" and "Manhasset", respectively), both in northwestern Long Island, USA. Excessive nitrogen loading has led to reduced dissolved oxygen concentrations in Long Island Sound, and the groundwater contribution to the nitrogen budget is poorly constrained. The frequent detection of the anticonvulsant compound carbamazepine in groundwater samples of the Northport Harbor area (unsewered), together with the fact that few pesticides associated with lawn applications were detected, suggests that wastewater input and atmospheric input are the likely sources of nitrogen in the Northport groundwater. High concentrations of nitrogen were also detected in the Manhasset (sewered) groundwater. The low detection frequency and concentration of carbamazepine, however, suggest that the sewer system effectively intercepts nitrogen from wastewater there. The likely sources of nitrogen in the Manhasset groundwater are atmospheric deposition and lawn fertilizers, as this area is densely populated.

Phosphorus in groundwater discharge – A potential source for lake eutrophication

“…The excessive application of fertilizers in private gardens may also cause groundwater contaminations (Vanek, 1993;Zhao et al, 2011).…”

Molecular signature of organic nitrogen in septic-impacted groundwater

“…In populated coastal areas, septic systems may be particularly important sources of both inorganic and organic nitrogen. 3,[6][7][8] At present, however, it is difficult to link the bulk DON found in impacted aquatic systems to specic sources or processes due to a lack of information about the molecular-level composition of DON.…”

Groundwater dynamics in subterranean estuaries of coastal unconfined aquifers: Controls on submarine groundwater discharge and chemical inputs to the ocean

“…With many urban areas, industrial sites, refineries and transport hubs (airports, harbors) located along coastlines, elevated concentrations of organic contaminants (e.g., hydrocarbons (petroleum products), chlorinated solvents, polyaromatic hydrocarbons and pesticides) in CUAs are common in developed areas [Zhao et al, 2011;Sbarbati et al, 2015]. Where terrestrial groundwater discharges to the ocean and organic contamination of the CUA is near the shoreline (i.e., < 1 41 km), there is potential for the contaminants to migrate to the coastal ocean via FSGD [Westbrook et al, 2005;Mastrocicco et al, 2012;Colombani et al, 2014].…”