『Abstract
Solid-phase phosphorus (P) speciation and benthic phosphate fluxes
have been determined in Arabian Sea sediments. Benthic phosphate
fluxes are highest in the continental slope sediments, underlying
bottom waters with low oxygen concentrations. Organic matter degradation
and phosphate desorption from iron oxides do not produce sufficient
phosphate to explain these high phosphate fluxes. The potentially
high deposition of P associated with fish debris (Pfish)
in the Arabian Sea, and a good correlation between benthic phosphate
fluxes and Pfish accumulation rates suggest
that benthic phosphate fluxes in these sediments are to a large
extent governed by dissolution of biogenic apatite. Factors controlling
dissolution and preservation of fish debris, therefore, may play
an important role in the burial and regeneration of P in continental
margin sediments. A sharp decrease of the reactive P accumulation
rate with increasing water depth, in combination with rather constant
primary productivity rates throughout the northern Arabian Sea,
indicates that P burial in continental margin sediments located
within the OMZ is more efficient than in deep basin sediments.
The effectiveness of P burial is to a large extent regulated by
P regeneration occurring in the water column and redeposition
processes. Sedimentary phosphorus burial efficiencies, thus, should
be interpreted with caution in terms of the environmental conditions.
Keywords: Arabian Sea; Phosphorus; Phosphorus cycling; Diagenesis;
Oxygen minimum zone』
1. Introduction
2. Materials and methods
2.1. Sample locations
2.2. Pore water analysis
2.3. Solid-phase analysis
3. Results
3.1. Porewaters
3.2. Solid phase
4. Discussion
4.1. Benthic phosphate release
4.1.1. Organic matter degradation
4.1.2. Phosphate desorption from iron oxides
4.1.3. Fish debris dissolution
4.2. Phosphorus burial in the Arabian Sea
5. Conclusions
Acknowledgements
References