No abstract

Estimates of the atmospheric 210Pb flux can be made from old (∼ 100 years) soil profiles because of the strong retention of this nuclide in the organic rich surface layers. Correction for radon loss can be made by modeling the observed 210Pb and 226Ra profiles. This is shown to have only a small effect for most of the soils studied. Comparison of soil‐based 210Pb fluxes with other estimates indicates good agreement except in the forested montane region of eastern New Mexico; the high 210Pb content of soils there remains to be explained.

No abstract

During Leg 113, a drifting sediment-trap array was deployed to investigate the flux of natural particulate materials from Weddell Sea summer surface waters. This array was launched, tracked, and recovered from the ice-escort vessel Maersk Master, rather than from the JOIDES Resolution drillship, to carry out these upper-ocean studies without interfering with drilling operations. The arrangement proved highly successful, allowing particle traps to be deployed on 16 occasions for 23-59 hr each during the course of the Maersk Master's ice-tending duties. This paper describes the field program and archives data on the geochemical and biochemical constituents of the material that was trapped. Mass fluxes out of the upper 100 m averaged 12 mg/m 2 /hr, with the highest fluxes trapped near Site 695 (90 mg/m 2 /hr). The trapped material was mostly flocculate in appearance, with microplankton assemblages dominated by diatoms of the genera Nitzschia and Thalassiosira and by the foraminifer Neogloboquadrinapachyderma. The material averaged 28% biogenic silica by weight; the organic portion was rich in amino acids, with average organic carbon/organic nitrogen ratio (by moles) of 7 ± 2. Organic carbon isotopic fractionation (5 13 C) ranged from-27 to-31; that of organic nitrogen (6 15 N) ranged from-2 to +7.

No abstract

No abstract

No abstract

No abstract