『Abstract
Mn biogeochemistry was studied from 1994 to 2003 in a small forested
catchment in the central Czech Republic using the watershed mass
balance approach together with measurements of internal stores
and fluxes. Mn inputs in bulk deposition were relatively constant
during a period of sharply decreasing acidic deposition, suggesting
that the Mn source was terrestrial, and not from fossil fuel combustion.
Mn inputs in bulk deposition and Mn supplied by weathering each
averaged 13 mg m-2 year-1 (26 mg m-2
year-1 total input), whereas Mn export in streamwater
and groundwater averaged 43 mg m-2 year-1.
Thus an additional Mn source is needed to account for 17 mg m-2
year-1. Internal fluxes and pools of Mn were significantly
greater than annual inputs and outputs. Throughfall Mn flux was
70 mg m-2 year-1, litterfall Mn flux was
103 mg m-2 year-1, and Mn net uptake by
vegetation was 62 mg m-2 year-1. Large pools
of labile or potentially labile Mn were present in biomass and
surficial soil horizons. Small leakages from these large pools
likely supply the additional Mn needed to close the watershed
mass balance. This leakage may reflect an adjustment of the ecosystem
to recent changes in atmospheric acidity.
Keywords: Manganese; Biogeochemistry; Czech Republic; Catchment;
Biotite weathering; Forest ecosystem; Mass balance』
1. Introduction
2. Site description
3. Material and methods
4. Results and discussion
4.1. Manganese in ecosystem compartments
4.1.1. Bedrock
4.1.2.Soil
4.1.3. Stream sediment
4.1.4. Biomass
4.2. Summary of manganese concentrations and pools
4.3. Mn input and output fluxes
4.3.1. Atmospheric inputs
4.3.2. Output through surface and subsurface flow
4.4. Internal fluxes
4.4.1. Mineral weathering
4.4.2. Canopy leaching
4.4.3. Soil leaching
4.4.4. Annual increments in wood and bark
4.4.5. Litterfall
4.5. Mn mass balance
5. Summary and conclusions
Acknowledgement
References