Effects of hypolimnetic oxygenation on water quality in Amisk Lake, Alberta, a deep, eutrophic lake with high internal phosphorus loading rates
| Autor: | E E Prepas, J M Burke |
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| Rok vydání: | 1997 |
| Předmět: | |
| Zdroj: | Canadian Journal of Fisheries and Aquatic Sciences. 54:2111-2120 |
| ISSN: | 1205-7533 0706-652X |
| DOI: | 10.1139/f97-125 |
| Popis: | Year-round injection of pure oxygen into the hypolimnion of one of two basins in Amisk Lake during 1988-1993 changed dissolved oxygen (DO) and nutrient concentrations in both lake basins without eliminating thermal stratification. Changes were greatest in the treated basin and during 1990-1993, when an upgraded injection system operated; injection rates of <-1increased mean summer hypolimnetic DO concentrations from 1.0 (1980-1987) to 4.6 mg ·L-1(1990-1993). Summer hypolimnetic DO depletion rates nearly doubled relative to the pretreatment period. Mean summer hypolimnetic total phosphorus (TP) concentrations decreased from 123 to 56 µg · L-1, despite low iron to phosphorus ratios near the sediments. Similarly, mean hypolimnetic ammonium concentrations declined from 120 to 42 µg ·L-1. Epilimnetic TP and chlorophyll a concentrations decreased to 87 and 45%, respectively, of pretreatment summer means. Oxygen consumption rates in the treated basin were lower in winter than in summer; injection rates of <-1increased mean winter deepwater DO concentrations from 2.5 to 7.2 mg ·L-1. In winter, mean deepwater TP concentrations decreased from 96 to 51 µg ·L-1. Oxygenation enhanced deepwater circulation in the treated basin in summer and winter. No changes were seen in two other reference basins during the study period. The hypolimnetic oxygen injection technology developed at Amisk Lake can be a cost-effective management tool for lakes with high hypolimnetic oxygen depletion rates related to high internal nutrient loading rates. |
| Databáze: | OpenAIRE |
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