Groundwater sources and flow patterns derived from stable isotopes and elemental chemistry in the southeast Louisiana freshwater aquifers
- Louisiana State Univ., Baton Rouge (USA)
Freshwater aquifers of southeast Louisiana constitute the core of the giant Southern Hills aquifer system that is confined to the north and east by outcropping Miocene beds and the groundwater divide, respectively, and to the south and west by the respective flushing limits. The aquifer system above 900 m consists of interbedded sands and confining clays that are Miocene and younger in age and are dipping south at about 2.8 m/km. The freshwaters contained in the stratified sand aquifers have a gravity-driven fluid flow and a dominant cation-anion combination of NaHCO{sub 3}. These aquifers provide the main source of drinking water for the Baton Rouge metropolitan area and its industrial corridor. Intensive pumping of groundwater from the deep aquifers since the early 1900s has resulted in a pronounced cone of depression centered north of Baton Rouge, and a significant decrease in hydraulic heads, which affected substantially the velocities and directions of groundwater flow. In order to evaluate the groundwater origins and flow patterns in the stratified aquifers, and predict possible migration path of contaminants from hazardous waste disposal sites into the aquifers, the authors analyzed oxygen and hydrogen isotopes and the sodium and chloride contents of 73 water wells above {minus}900 m depth. Precipitation and Mississippi River water samples were also analyzed for isotopes and elemental chemistry for the duration of the study in order to establish the hydrological background of possible recharge sources to the aquifers. The mean {delta}{sup 18}O value for precipitation in the study area is {minus}3.8 0/00 (SMOW) whereas the Mississippi River at St. Francisville has an annual weighted mean {delta}{sup 18}O value of {minus}6.9 0/00. {delta}{sup 18}O values of freshwater wells range from {minus}3.5 to {minus}4.7 0/00 and their {delta}{sup 18}O/{delta}D relationship obeys Craig's meteoric water line equation.
- OSTI ID:
- 5950206
- Report Number(s):
- CONF-9010204-; CODEN: AABUD
- Journal Information:
- AAPG Bulletin (American Association of Petroleum Geologists); (USA), Vol. 74:9; Conference: Gulf Coast Association of Geological Societies and Gulf Coast Section of SEPM (Society of Economics, Paleontologists, and Mineralogist) meeting, Lafayette, LA (USA), 17-19 Oct 1990; ISSN 0149-1423
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
AQUIFERS
GEOCHEMISTRY
HYDROLOGY
LOUISIANA
FLUID FLOW
GROUND WATER
ISOTOPE RATIO
MISSISSIPPI RIVER
OXYGEN 18
TERTIARY PERIOD
WATER CHEMISTRY
CENOZOIC ERA
CHEMISTRY
EVEN-EVEN NUCLEI
FEDERAL REGION VI
GEOLOGIC AGES
HYDROGEN COMPOUNDS
ISOTOPES
LIGHT NUCLEI
NORTH AMERICA
NUCLEI
OXYGEN COMPOUNDS
OXYGEN ISOTOPES
RIVERS
STABLE ISOTOPES
STREAMS
SURFACE WATERS
USA
WATER
580000* - Geosciences