کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5784961 | 1639835 | 2017 | 15 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Seasonal radiocarbon reservoir ages for the 17th century James River, Virginia estuary
ترجمه فارسی عنوان
فصل سیلاب رادیو کربن فصلی برای قرن 17 میلادی رودخانه جیمز رودخانه ویرجینیا
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
ژئوشیمی و پترولوژی
چکیده انگلیسی
This study utilizes a combined stable isotope and 14C dating approach to determine the radiocarbon reservoir age correction, ÎR, for the James River, Virginia estuary from 17th century Crassostrea virginica shells of known collection dates. ÎR, which can vary spatially and temporally, is a locality-specific adjustment applied to the global ocean reservoir, R, to further account for the offset between the atmospheric and marine 14C calibration curves. To assess the temporal variability in ÎR, continuous δ18O sampling along the oyster shell hinge provides a seasonal record throughout the oyster's life. This is then used to identify sampling locations for 14C measurements based on calcite precipitated during the Summer (>19 °C) and Fall through Spring (F-Sp, <15 °C) months. The resulting seasonal ÎR values range from â151 ± 46 to +109 ± 55 14C years (260 years) due to changes in the contribution and age of dissolved inorganic carbon (DIC) from marine and freshwater sources in the James River estuary. The F-Sp samples display a larger ÎR range than the Summer samples, as do the shells precipitated during drought conditions (1606-1612) when compared to shells from the remainder of the 17th century. The largest intrashell ÎR variability, 195 14C years, is similarly found in a drought shell and is attributed to variability caused by the extreme regional 1606-1612 drought. Early land use changes related to European development and farming practices also altered the age of DIC in the James River estuary. We estimate that the soil inorganic carbon (SIC) contributing to freshwater DIC ranged from 0 to â¼1800 years old and reflected both the drought and land use changes that occurred during the 17th century. Using only the Summer samples, which represent the majority of shell calcite, we obtain a mean ÎR = â32 ± 11 14C years (1Ï) for 17th century James River estuary ÎR at the very onset of European colonization. Employing a seasonally resolved sampling method will provide the greatest constraint on 14C measurements in an estuarine environment where multiple carbon sources can fluctuate on seasonal timescales and as a result of large scale environmental change.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Quaternary Geochronology - Volume 41, August 2017, Pages 119-133
Journal: Quaternary Geochronology - Volume 41, August 2017, Pages 119-133
نویسندگان
Brittany L. Grimm, Howard J. Spero, Juliana M. Harding, Thomas P. Guilderson,