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Sources and Sinks of Ions in a Soft Water, Acidic Lake in Florida
Author(s) -
Baker Lawrence A.,
Brezonik Patrick L.,
Edgerton Eric S.
Publication year - 1986
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/wr022i005p00715
Subject(s) - precipitation , sulfate , nitrate , hydrology (agriculture) , groundwater , environmental science , soil water , sink (geography) , environmental chemistry , flux (metallurgy) , surface water , deposition (geology) , chemistry , sediment , environmental engineering , geology , soil science , geomorphology , physics , geotechnical engineering , cartography , organic chemistry , meteorology , geography
Fluxes and storage of water and major ions were measured for McCloud Lake, a small, acidic soft water lake in north central Florida that receives 90% of its water input from direct precipitation. Wet precipitation had a volume‐weighted p H of 4.5 and accounted for a H + flux of 420 eq/ha yr; deposition of SO 2 , NO 2 , and HNO 3 contributed an additional 150–300 eq H + /ha yr. Although precipitation passing through the sandy soils and littoral sediment was neutralized by mineral weathering, sulfate reduction or adsorption, and nitrate immobilization, ground water was only 10% of the total water input to the lake and neutralized only about 30% of precipitation H + input. Compared to atmospheric deposition, lake water shows little enrichment of cations but is depleted in SO 4 2− , NO 3 − and NH 4 + , while >80% of precipitation H + is neutralized. The major H + neutralization processes within the lake are sulfate reduction (26–34 meq SO 4 2− /m 2 yr) and NO 3 − immobilization (17–20 meq NO 3 − /m 2 yr), while NH 4 + immobilization is a small internal source of H + . Sinks and sources of cations could not reliably be calculated because of uncertainties in groundwater inputs. Internal H + ‐consuming processes are important in lakes with no surface inlets or outlets and which receive most of their water from direct precipitation. For these lakes, the rate and extent of acidification is largely determined by a balance between H + inputs and H + consumption by internal processes.