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Delineating the Chemical Composition of the Salinity Source for Saline Ground Waters: An Example from East‐Central Concordia Parish, Louisiana
Author(s) -
Stoessell Ronald K.
Publication year - 1997
Publication title -
groundwater
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.84
H-Index - 94
eISSN - 1745-6584
pISSN - 0017-467X
DOI - 10.1111/j.1745-6584.1997.tb00100.x
Subject(s) - salinity , composition (language) , chemical composition , environmental science , geography , oceanography , hydrology (agriculture) , archaeology , geology , chemistry , art , literature , geotechnical engineering , organic chemistry
In the absence of significant water‐rock interaction, the chemical composition of a saline brine polluting a ground‐water aquifer can be delineated from conservative‐mixing relations. An example is the Mississippi River Alluvium Aquifer, within Angelina Plantation in east‐central Concordia Parish, Louisiana, which has high ground‐water salinities, of unknown origin. Chloride concentrations are linearly correlated with concentrations of major cations and with bromide and iodide. These relationships are consistent with mixing of fresh water with a saline source of either a single brine or multiple brines of similar composition and with a lack of significant water‐rock interactions in the ground water during and after mixing. The saline source has the following predicted mass ratios for a brine containing 80,000 ppm CI: Na/CI, 0.58; Br/CI, 0.0013; I/CI, 0.00028; Sr/CI, 0.0026; K/CI, 0.0035; CaCI, 0.035; and Mg/CI, 0.0080. The predicted 87 Sr/ 86 Sr ratio is 0.70805. The mass ratios fall within the range of Tertiary oil‐field brines in the Louisiana Gulf Coast. The major reservoir for hydrocarbon production in the area is the Wilcox Formation; however, the “predicted” source brine is unlikely to be a “pure” Wilcox brine from Concordia Parish. Ratios of 87 Sr/ 86 Sr are usually lower and bromide, iodide, and calcium concentrations are always lower in the Wilcox brines than predicted in the saline source.