Nutrient Cycling in a Strongly Acidified Mesotrophic Lake

In contrast to the well-known nutrient transformations in circumneutral lakes, acidified water bodies may exhibit significant changes in nutrient cycling due to changes in their chemistry and biology. In-lake cycles of carbon (C), nitrogen (N), and phosphorus (P) were evaluated in the strongly acidi...

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Published in:Limnology and oceanography 2004-07, Vol.49 (4), p.1202-1213
Main Authors: Kopáček, Jiří, Brzáková, Martina, Hejzlar, Josef, Nedoma, Jiří, Porcal, Petr, Vrba, Jaroslav
Format: Article
Language:English
Subjects:
Aluminum
Animal and plant ecology
Animal, plant and microbial ecology
Biological and medical sciences
Earth sciences
Earth, ocean, space
Exact sciences and technology
Fresh water ecosystems
Freshwater
Fundamental and applied biological sciences. Psychology
Geochemistry
Glacial lakes
Hydrology
Hydrology. Hydrogeology
Lakes
Limnology
Mineralogy
Nutrient cycle
Particulate matter
Phosphorus
Production estimates
Sediments
Seston
Silicates
Synecology
Water geochemistry
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Summary:In contrast to the well-known nutrient transformations in circumneutral lakes, acidified water bodies may exhibit significant changes in nutrient cycling due to changes in their chemistry and biology. In-lake cycles of carbon (C), nitrogen (N), and phosphorus (P) were evaluated in the strongly acidified Plešné Lake (Central Europe). The lake tributaries had high concentrations of dissolved organic C (DOC), inorganic N, and total phosphorus (TP), resulting in annual averages of 644, 52, and 0.72 μmol L-1, respectively. Because of the absence of fish and largely reduced zooplankton, Plešné Lake has a "simplified" food web. The mass balance of nutrients was based on the major external inputs (tributaries and atmospheric deposition), internal sources and transformations (primary and bacterial production, biological decomposition of sedimenting seston and sediments), sedimentation, and outputs. External inputs of total organic C (TOC), total N (TN), and TP into Plešné Lake were 7,244, 864, and 8.6 mmol m-2 yr-1, respectively. Net primary production of particulate C $(\text{C}_{\text{part}})$ and extracellularly released DOC were 3,205 and 613 mmol m-2 yr-1, respectively. Bacterial $\text{C}_{\text{part}}$ and total inorganic C production were both 1,518 mmol m-2 yr-1. Of the total internal and external inputs of TOC, TN, and TP, the in-lake processes removed 4,551 (50% respiration, 40% sedimentation, and 10% photooxidation), 211 (74% sedimentation and 26% denitrification), and 4.6 (100% sedimentation) mmol m-2 yr-1 respectively. Compared to circumneutral lakes, nutrient cycling differed as follows: (1) Liberated orthophosphate from sedimenting seston was converted from a liquid to a particulate phase by colloidal aluminum (Al) in the hypolimnion and deposited. Similar abiotic P immobilization with Al removed 1.6 mmol m-2 yr-1 from the whole-water column, thus reducing by ∼20% the pool of potentially bioavailable P and contributing to a severe P limitation of biomass. (2) The cessation of nitrification due to long-term water acidification led to an atypical situation in which the lake became a net source of NH4+ (30 mmol m-2 yr-1) because dissimilative liberation of NH4+ exceeded its assimilation.
ISSN:0024-3590
1939-5590
DOI:10.4319/lo.2004.49.4.1202