Sediment alkalinity production in calcite-treated acidic lakes

Miscellaneous · Sun Jan 01 00:00:00 EST 1989

OSTI ID:5606669

Rhea, J R

Lake neutralization by the addition of calcite is one form of mitigation currently used to restore lakes acidified by acid deposition. This study focuses on the role that sediments play in reacidification of calcite treated acidic lakes. The study evaluated the effectiveness of sediment treatment in providing acid neutralization capacity (ANC) to the water column of calcite treated lakes during reacidification, determined sediment Ca{sup +2}-H{sup +} exchange coefficients, and evaluated the rate and extent of calcite dissolution and deactivation within lake sediments. The results obtained from these studies were integrated into a mathematical model (SAM) that simulates alkalinity flux from sediments of calcite treated lakes. Sediment and sediment pore water chemistry profiles collected from Little Simon Pond (LSP) and Woods Lake (WL) before whole lake additions of slurried calcite indicated that denitrification, sulfate reduction, and cation exchange contributed to pre-treatment sediment alkalinity fluxes of {minus}0.14 and {minus}0.13 eq/m{sup 2}-yr, respectively. These pre-treatment measurements produced summer sediment ANC fluxes that neutralized an estimated 15% (WL) and 48% (LSP) of annual watershed acidity loads. Post-treatment ANC production resulting from calcite dissolution increased sediment ANC flux to greater than 2 eq/m{sup 2}-yr (LSP) and approximately 1 eq/m{sup 2}-yr (WL). Elevated ANC flux continued through 9 (LSP) and 11 months (WL) subsequent to treatment indicating sediment treatment can retard lake reacidification. Sediment calcium-hydrogen exchange coefficients (K{sub H}{sup Ca}) illustrated a strong dependence on bulk solution pH and ionic strength. At 0.01 M ionic strength, K{sub H}{sup Ca} varied log-linearly with pH from a low of 10{sup {minus}5.32} (moles/L){sup 0.5} at pH 7.0 to a high of 10{sup {minus}4.65} (moles/L){sup 0.5} at pH 5.0.

• Research Organization: BKI Associates, Inc., McLean, VA (United States)
• OSTI ID: 5606669
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
01 COAL, LIGNITE, AND PEAT
ACID NEUTRALIZING CAPACITY
MATHEMATICAL MODELS
ACID RAIN
ENVIRONMENTAL EFFECTS
LAKES
ACIDIFICATION
CALCITE
DISSOLUTION
ION EXCHANGE
PH VALUE
SEDIMENTS
SULFATES
WATER CHEMISTRY
WATER POLLUTION
ALKALINE EARTH METAL COMPOUNDS
ATMOSPHERIC PRECIPITATIONS
CALCIUM CARBONATES
CALCIUM COMPOUNDS
CARBON COMPOUNDS
CARBONATE MINERALS
CARBONATES
CHEMISTRY
MINERALS
OXYGEN COMPOUNDS
POLLUTION
RAIN
SULFUR COMPOUNDS
SURFACE WATERS
540320* - Environment
Aquatic- Chemicals Monitoring & Transport- (1990-)
010900 - Coal
Lignite
& Peat- Environmental Aspects