Nd abundance and isotopic composition distributions of surface seawaters of the Northwest Pacific Ocean and its adjacent seas
-
- Amakawa Hiroshi
- Department of Chemistry, Tokyo Metropolitan University
-
- Alibo Dia Sotto
- Chemistry Department, University of San Carlos
-
- Nozaki Yoshiyuki
- The Ocean Research Institute, University of Tokyo
書誌事項
- タイトル別名
-
- Nd concentration and isotopic composition distributions in surface waters of Northwest Pacific Ocean and its adjacent seas
この論文をさがす
抄録
Nd isotopic composition and concentration distributions were determined in surface waters of the Northwest Pacific Ocean and its adjacent seas, i.e., the Okhotsk and Japan Seas. The Okhotsk and Japan Seas samples showed higher Nd concentrations (19∼31 pmol/kg) than the Northwest Pacific Ocean samples, suggesting a large amount of Nd input from the land areas surrounding the Okhotsk and Japan Seas. Although the Nd isotopic composition data were limited for those regions, each oceanic area showed a distinctive value. The lone sample from the Okhotsk Sea had radiogenic Nd (εNd = −3.6) that was comparable to samples from the Pacific Ocean, indicating a large amount of radiogenic Nd supply from the Kuril Islands. On the other hand, the Japan Sea samples had the most highly unradiogenic Nd (εNd = −8.9∼−7.2). The southernmost sample had the most negative value, due to the influence of the Tsushima Warm Current (TWC) having a low εNd value. The latitudinal distributions of Nd isotopic composition and concentration in the surface waters of the Northwest Pacific Ocean showed marked variations. Nd concentration was low at low latitudes (3∼8 pmol/kg) and was increased with increasing latitude (16∼20 pmol/kg). On the other hand, Nd isotopic composition showed a mid-latitude minimum (εNd = ∼−6) and high εNd values at low and high latitudes (εNd = −2∼−1). The distribution of the εNd values seemed to be controlled by three currents: Kuroshio Extension, Oyashio Current and North Equatorial Current (NEC). The Kuroshio Extension, which showed a low εNd value, seemed to play an important role in transporting continentally derived Nd to the central Pacific. The Oyashio Current and NEC are supplied with large amounts of radiogenic Nd from the Kuril and Aleutian Islands, and the Hawaiian Islands, respectively. Based on the Nd isotopic composition and concentration distributions, we calculated the radiogenic Nd flux to the Pacific Ocean surface waters and estimated the Nd residence time. Our calculation suggested that the radiogenic Nd flux required to account for the Nd isotopic composition is higher than 70% of the unradiogenic Nd flux including Nd remobilization from coastal and shelf sediments and atmospheric input. It was also revealed that a large Nd remobilization flux is necessary to attain a global Nd residence time of ∼400 y as estimated in previous studies.
収録刊行物
-
- GEOCHEMICAL JOURNAL
-
GEOCHEMICAL JOURNAL 38 (6), 493-504, 2004
一般社団法人日本地球化学会
- Tweet
詳細情報 詳細情報について
-
- CRID
- 1390001204551667840
-
- NII論文ID
- 130003743470
- 10014092918
-
- NII書誌ID
- AA00654975
-
- COI
- 1:CAS:528:DC%2BD2MXmtlygtw%3D%3D
-
- ISSN
- 18805973
- 00167002
-
- NDL書誌ID
- 7202593
-
- 本文言語コード
- en
-
- データソース種別
-
- JaLC
- NDL
- Crossref
- CiNii Articles
-
- 抄録ライセンスフラグ
- 使用不可