Detecting groundwater contamination of a river in Georgia, USA using baseflow sampling

Detecting groundwater contamination of a river in Georgia, USA using baseflow sampling | Détection de la pollution par la nappe d’une rivière en Géorgie, USA mettant en œuvre l’échantillonnage de l’écoulement de base Detección de la contaminación de aguas subterráneas de un río en Georgia, EEUU utilizando el muestreo de caudal base 利用基流取样探测美国乔治亚州某河流的地下水污染 Detecção da contaminação de água subterrânea num rio na Geórgia, EUA, utilizando amostragens do caudal de base

2009

Algal blooms and fish kills were reported on a river in coastal Georgia (USA) downstream of a poultry-processing plant, prompting officials to conclude the problems resulted from overland flow associated with over-application of wastewater at the plant’s land application system (LAS). An investigation was undertaken to test the hypothesis that contaminated groundwater was also playing a significant role. Weekly samples were collected over a 12-month period along an 18 km reach of the river and key tributaries. Results showed elevated nitrogen concentrations in tributaries draining the plant and a tenfold increase in nitrate in the river between the tributary inputs. Because ammonia concentrations were low in this reach, it was concluded that nitrate was entering via groundwater discharge. Data from detailed river sampling and direct groundwater samples from springs and boreholes were used to isolate the entry point of the contaminant plume. Analysis showed two separate plumes, one associated with the plant’s unlined wastewater lagoon and another with its LAS spray fields. The continuous discharge of contaminated groundwater during summer low-flow conditions was found to have a more profound impact on river-water quality than periodic inputs by overland flow and tributary runoff.

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