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Resuspension‐Mediated Temporal Variation in Phosphorus Concentrations and Internal Loading
Author(s) -
Niemistö Juha P.,
Holmroos Heidi,
Nurminen Leena,
Horppila Jukka
Publication year - 2009
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2008.0075
Subject(s) - eutrophication , sediment , phytoplankton , chlorophyll a , sedimentation , phosphorus , suspended solids , environmental science , environmental chemistry , algal bloom , nutrient , hydrology (agriculture) , chemistry , geology , environmental engineering , wastewater , geomorphology , biochemistry , geotechnical engineering , organic chemistry
Sediment resuspension is an important factor for nutrient cycling in shallow lakes. Temporal variation in sediment resuspension and its influence on P concentrations and internal loading were studied in the shallow and eutrophic Kirkkojärvi basin. Gross sedimentation and sediment resuspension were estimated with sediment traps during three exposure periods in spring, midsummer, and autumn. The effects of resuspension on the concentrations of suspended solids, total phosphorus (TP), soluble reactive P, and chlorophyll a were followed. The level of sediment resuspension was greatest in midsummer (July–August 63.9 g dw m −2 d −1 ), due to strong phytoplankton blooms modifying the surface film of the sediment more prone to resuspension. The dependence of high total P concentrations (226–385 μg L −1 ) on sediment resuspension and suspended solids was significant at the time. The concentrations of soluble reactive P were also high in midsummer (52–91 μg L −1 ), but had a negative dependence on suspended solids. This dependence was due to algal assimilation as was proved by a negative effect of chlorophyll a on soluble reactive P. Consequently, we suggest that the increase in the total P concentrations caused by sediment resuspension in midsummer was possibly intensified by strong algal blooms occurring at the time because strong assimilation resulting in high pH (pH 7.3 in May, 9.3–10.2 in July–August, 7.6 in October) may have increased the desorption of P from the suspended inorganic particles and intensified the P transfer into the phytoplankton biomass in midsummer.