27 D2. Environmental Geology & Geochemistry (Posters)

Monday, 18 March 2019
8:00 AM - 12:00 PM
Casco Bay Hall

GEOCHEMICAL ANALYSIS OF BRIAR CREEK LAKE IN COLUMBIA COUNTY, PENNSYLVANIA

Paper number: 27-8
Program: Technical Sessions
Time: 8:00 AM – 12:00 PM

Authors

Abstract

Briar Creek Lake is a 53-acre lake built in the early 1970s to aid in flood control in SE Columbia County. Although BU geochemists have studied the Briar Creek watershed in the past, waters of the lake itself had not been analyzed. Water samples were collected at the inlet, outlet, and in three transects across the eastern, middle, and western portions of the lake, a total of 11 sites. In addition, in situ measurements (pH, conductivity, dissolved oxygen, and temperature) were collected at each location except the inlet (unfortunately). Sediment samples and discharge measurements were obtained at both the inlet and outlet. Turbidity was measured on all samples prior to their storage on ice. In the lab, triplicate unfiltered samples were acidified to pH < 2 and refrigerated for future total metal analysis. Water was then filtered (GFF 0.7µm effective pore size) and 1) acidified to pH < 2 and refrigerated for dissolved metal analysis; 2) frozen for future simple anion and cation measurement; 3) used in triplicate for alkalinity and acidity titrations. In situ measurements showed that pH stayed consistently between 7.1 – 7.2 across the study area. Dissolved oxygen was high throughout the whole lake (all greater than 93% saturation), highest, not surprisingly, at outlet (site 1) where water was more turbulent. Conductivity generally decreased from inlet to outlet. Turbidity was highest near the inlet (site 10), most likely due to sediment kicked up from the ever harder rain increasing the inflow, which was notable by the cloudiness of the water. The lake was most alkaline in the middle (site 6) and most acidic at the inlet (site 11). The ICP results for heavy metals showed that only aluminum was detectable in dissolved form with aluminum and iron detectable in total metal samples. SEM analysis of sediment samples and filters revealed multiple diatoms (Navicula?), indicating good water quality.

Geological Society of America Abstracts with Programs. Vol. 51, No. 1

doi: 10.1130/abs/2019NE-328628

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