NEW-TYPE OF TIME-SERIES SEDIMENT TRAP FOR THE RELIABLE COLLECTION OF INORGANIC AND ORGANIC TRACE CHEMICAL-SUBSTANCES

The new sediment trap has a 0.5 m(2) aperture, a funnel slope of 34 de grees and is capable of collecting 21 samples at programmed intervals (1 min-1 year) during deployment in the deep ocean. The trap has been designed to allow reliable data on trace inorganic and organic compone nts (such as trace elements, n-alkanes, PCBs, PAHs, amino/fatty acids) in addition to the standard biogeochemical variables in the collected particles. Due to the exclusive use of synthetic (such as fiberglass, PVC, PTFE, or POM-Delrin(R)) and highly resistant metallic materials contamination problems have been eliminated for these species. Blank v alues determined in several tests in the open ocean were as low as 1% or even less of the amounts present in trap material, even at low part iculate loadings. Another major aim was the elimination of loss of dis solved components from the sample cups into seawater. Microbial and ch emical processes modify the collected particles, thereby mobilizing or iginally particulate species into solution. It is thus essential to av oid greater losses of dissolved species through diffusion into the sur rounding seawater after collection. This was achieved by means of an e specially designed sealing mechanism. Tests with tracer substances dur ing field studies proved that losses of dissolved components from supe rnatants during one year of deployment are as low as 10%. Additionally , the relationship between flow characteristics around the traps and t heir excursions from the vertical position in a bottom-tethered array was studied during a one-year deployment in the North Atlantic. (C) 19 96 American Institute of Physics.