Huser, Brian
- University of Minnesota
Abstract
Phosphorus (P) binding by aluminum (Al), iron (Fe), and calcium (Ca) in lake sediments was studied in both nutrient-rich circumneutral lakes and nutrient-poor acidic lakes. Restoration efforts on nutrient-rich lakes often involve the addition of Al salts to increase the P sorption capacity of the sediment. In contrast, increased Al inputs to acidified lakes generally have the effect of decreasing available P in the water column to undesirably low levels. Efforts to restore acidified lakes (e.g. liming) can result in increased Al and Fe binding of P in the sediment.
Nutrient-rich (eutrophic) lakes in the Minneapolis, MN area that have received aluminum sulfate treatments to control internal P loading were studied. Methods used to determine alum dose were compared and the results of alum treatments applied to the Minneapolis Chain of Lakes were examined. P concentrations improved (decreased) initially in all lakes, and three lakes were still experiencing continued benefits at the end of this study. Analysis of the sediment, however, showed that internal P load reductions met the restoration goals in all lakes, which suggests that the importance of external P loading on water quality was underestimated in the lake with short-term treatment benefits.
Binding of P by Al in acidified lakes resulted in the inactivation of a substantial amount of P over nearly five decades in lakes across southern Sweden. In addition, total sulfur (ST) in the lake sediment also increased during the industrial acidification period (IAP; determined by 210lead dating) in two lakes (Lakes Gårdsjön and Gyltigesjön). Based on this evidence and that from other studies, ST levels in sediment cores from 12 lakes were related to elevated levels of Al and Al bound P (Al-P) during the IAP and to increasing sulfate in the deposition over Sweden during the period ~1930-1970. Of the 12 lakes, four showed increased sediment Al and Al-P during the IAP, three showed increases before the IAP, three showed increases during both periods and two lakes showed increases that could not be related to the IAP. It is hypothesized that forest harvesting, which was at its peak in Sweden in the mid to late 1800s, caused the pre-IAP increases in sediment Al and Al-P, and that liming or acidic inflows caused the non-IAP related increases in Al and Al-P.
Published in
Publisher: University of Minnesota
SLU Authors
UKÄ Subject classification
Oceanography, Hydrology, Water Resources
Environmental Sciences
Publication identifier
- ISBN: 978-0-496-93329-7
Permanent link to this page (URI)
https://res.slu.se/id/publ/140066