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Phosphorus inactivation in a eutrophic lake by the direct addition of ferric aluminium sulphate: impact on iron and phosphorus
Author(s) -
FOY R. H.
Publication year - 1985
Publication title -
freshwater biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.297
H-Index - 156
eISSN - 1365-2427
pISSN - 0046-5070
DOI - 10.1111/j.1365-2427.1985.tb00232.x
Subject(s) - hypolimnion , epilimnion , eutrophication , phosphorus , overwintering , ferric , environmental chemistry , zoology , precipitation , chemistry , ecology , nutrient , biology , inorganic chemistry , physics , organic chemistry , meteorology
SUMMARY.1 Following addition of ferric aluminium sulphate (FAS) in February 1980 to a eutrophic lake, White Lough, Northern Ireland, the cycles of phosphorus (P) and iron (Fe) over 34 months were compared to those in the 18 months preceding the application. 2 During the summer of 1980, P release to the hypolimnion was reduced by 92% compared to 1979 but by 1982 had returned to pre‐treatment levels. Phosphorus budget calculations for the post‐ treatment period indicated that P was accumulating in the sediment at a rate sufficient to permit the recovery of P release. 3 In the three summers following FAS addition, Fe released into the hypolimnion increased by 56–71% compared to 1979 but this increase represented less than 10% of Fe added in the FAS. 4 Prior to FAS treatment, hypolimnetic Fe and P were mixed throughout the lake at overturn, resulting in high winter concentrations, but after treatment, overturn was accompanied by large reductions in the lake Fe and P content due to precipitation. As a result, overwintering P concentrations in 1980/81 and 1981/82 were in the range 31–53μg P1 ‐1 compared to 111–194μg P1 ‐1 in 1978/79 and 1979/80. 5 The reduction of hypolimnetic P release in 1980 and 1981 and lower overwintering P had little impact on summer epilimnetic P concentrations which for 1979–82 were 51, 36, 47 and 48μg P1 ‐1 respectively. Phosphorus concentrations in the epilimnion were raised between April and June in each year by a release of P into the epilimnion. August and September was the only period when reductions in hypolimnetic P were reflected in lower P concentrations in the epilimnion.