HR: 0800h
AN: OS51C-1325    [Abstracts]
TI: The effect of sediment trap poisons on particulate phosphorus integrity
AU: Truesdale, K
EM: ktruesdale@hotmail.com
AF: University of South Carolina, Department of Geological Sciences, Columbia, SC 29208 United States
AU: * Benitez-Nelson, C R
EM: cbnelson@geol.sc.edu
AF: University of South Carolina, Department of Geological Sciences, Columbia, SC 29208 United States
AU: Styles, R
EM: rmstyles@geol
AF: University of South Carolina, Department of Geological Sciences, Columbia, SC 29208 United States
AU: Tappa, E
EM: tappa@geol.sc.edu
AF: University of South Carolina, Department of Geological Sciences, Columbia, SC 29208 United States
AB: The biogeochemical cycling of phosphorus (P) in marine systems has been complicated by a lack of information regarding the flux of particulate P from surface waters to the seafloor. This is because one of the most common ways to collect sinking particles is through the use of sediment traps where poisons are often added to reduce post depositional biological processing. Although few in number, several studies have suggested that these poisons may also affect sample integrity, particularly with respect to P. In this study, we examined the effects of three preservatives (mercuric chloride, formalin, and sodium azide) on P concentrations in marine sediments collected from a range of coastal and open ocean environments: the Black Sea (BS), Cariaco Basin (CB), Gulf of Mexico (GoM), and Winyah Bay (WB). Duplicate samples with controls were exposed to each preservative, and the loss of P to the supernatant was monitored over a period of six months. P losses to the supernatant happened rapidly, with most of the P loss occurring within the first 2 - 5 days of exposure. Formalin was consistently the least effective in preserving P sample integrity, with ~ 5 % of the initial P found in the supernatant for sediments of the BS, ~12 % from the GoM, ~ 20 % in CB, and as much as 40 % in WB. Mercuric chloride was the second least effective preservative, with P losses of 20 % in WB and $<$ 5 % in the other sediments. In contrast, sodium azide, appeared to be the most effective trap solution, with P losses never exceeding more than 5 % of the total P measured in the sediment. In most of our experiments with formalin and sodium azide, the dominant form of P found in the supernatant occurred as soluble reactive P. However, mercuric chloride consistently had dissolved organic P concentrations greater than 50 % of the total P measured in the supernatant, confirming earlier studies that mercuric chloride releases ATP during preservation. Our results suggest that P losses in sediment traps may vary widely, depending on the region and initial composition of the material. In addition, sodium azide appears to be the best trap solution for preserving P integrity and should be used whenever possible.
DE: 4825 Geochemistry
DE: 4845 Nutrients and nutrient cycling
DE: 4800 OCEANOGRAPHY: BIOLOGICAL AND CHEMICAL
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting