| 1. |
- Peinerud, Elsa K.
(författare)
-
Interpretation of Si concentrations in lake sediments : three case studies
- 2000
-
Ingår i: Environmental Geology. - : Springer. - 0943-0105 .- 1432-0495. ; 40:1-2, s. 64-72
-
Tidskriftsartikel (refereegranskat)abstract
- The biogenic Si concentration in a sediment can be determined as the non-detrital Si concentration by normalization of the total Si concentration with Al. This procedure is based upon the assumptions that (1) that Al exists predominantly in detrital, i.e. minerogenic, particles and (2) that biogenic Si (mainly diatom frustules) is the dominating non-detrital Si phase. This paper focuses on the reasons for the variations of the non-detrital Si concentration in these lake sediments. Data from three lakes are presented, representing three principally different cases regarding the Si concentration. The processes controlling the concentrations of detrital and non-detrital Si are discussed.
|
|
| 2. |
- Peinerud, Elsa K., et al.
(författare)
-
Non-detrital Si concentrations as an estimate of diatom concentrations in lake sediments and suspended material
- 2001
-
Ingår i: Chemical Geology. - 0009-2541 .- 1872-6836. ; 177:3-4, s. 229-239
-
Tidskriftsartikel (refereegranskat)abstract
- This paper evaluates a method, based on normalization with Al, to estimate the concentration of diatoms in suspended and deposited sediments. Provided that Al exists primarily in the detrital phase, one can calculate the fraction of non-detrital Si (i.e. biogenic Si). Suspended matter and sediment in two lakes in northern Sweden have been analyzed. Results from the normalization method are compared with microscope count data. The results from the two methods differ somewhat. Partly dissolved diatom frustules may explain part of this discrepancy. These remnants can hardly be recognized as diatoms. Therefore, they are not counted during the microscopic analysis, although they contribute to the concentration of biogenic Si. Another factor is the differences in Si content among different types of diatoms. We show that the calculated concentrations of non-detrital Si are good estimates of the diatom concentrations. By using normalization as a tool, reasonable estimates of the stocks of biogenic Si can be obtained rapidly. Using these estimates as a guide, sites where considerable changes in diatom productivity and/or dissolution rates have occurred can be identified.
|
|
| 3. |
|
|
