کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
10223805 1701057 2018 19 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Deposition patterns on the Chukchi shelf using radionuclide inventories in relation to surface sediment characteristics
ترجمه فارسی عنوان
الگوهای رسوب در قفسه چوکچی با استفاده از موجودی های رادیونوکلئید در ارتباط با خصوصیات رسوبات سطح
کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات زمین شناسی
چکیده انگلیسی
Forty sediment cores collected on the Chukchi shelf and adjacent portions of the East Siberian Sea have been assayed for the sedimentation tracer 137Cs and 34 were also assayed for 210Pb. While both sedimentation and bioturbation influence how these tracers are distributed vertically in sediment cores, only about half of the cores had distinct, single mid-depth or subsurface maximum activity peaks associated with 137Cs originating from bomb fallout. For the same reasons, only 14 of the 34 cores assayed showed a consistent decline in excess sedimentary 210Pb with depth in the core. Furthermore, sedimentation rate estimates from 210Pb assays were only consistent with estimated 137Cs sedimentation rates in 4 of the 14 cores from north of Bering Strait. A high degree of bioturbation on the shelf is primarily responsible for these patterns, but the influence of sedimentation on vertical profiles is also important, particularly in areas of low accumulation where shallow burial of maximum burdens of 137Cs in high current areas such as Herald Canyon can be observed. Shallow burial of radiocesium is also observed in comparatively low sedimentation areas such as Hanna Shoal, on the northeast Chukchi Shelf. By contrast, elsewhere on the northeast Chukchi Shelf and in productive benthic “hotspots,” the stronger influence of bioturbation leads to radiocesium that is more evenly distributed vertically within sediments, i.e., no distinct mid- or subsurface depth maximum activity associated with bomb fallout. These sediment profiles of radiocesium reflect several other sediment characteristics that are affected by current flow. These sediment characteristics in turn impact biological activity, including grain size, carbon to nitrogen ratios of the organic fraction of surface sediments and total organic carbon content. The distribution patterns of the radionuclides, particularly the depth where 137Cs reaches maximum activity, reflects sedimentation under both quiescent and strong currents. The activity of 137Cs at that depth of maximum activity provide insights on how much the vertical distribution of the radionuclide has been impacted by bioturbation, as well as the characteristics of the sediments that play a role in influencing deposition and total inventories of radiocesium on continental shelves.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Deep Sea Research Part II: Topical Studies in Oceanography - Volume 152, June 2018, Pages 48-66
نویسندگان
, ,