TY - JOUR
T1 - Factors characterizing phosphate oxygen isotope ratios in river water
T2 - an inter-watershed comparison approach
AU - Ide, Jun’ichiro
AU - Ishida, Takuya
AU - Cid-Andres, Abigail P.
AU - Osaka, Ken’ichi
AU - Iwata, Tomoya
AU - Hayashi, Takuya
AU - Akashi, Masanori
AU - Tayasu, Ichiro
AU - Paytan, Adina
AU - Okuda, Noboru
N1 - Funding Information:
This work was supported in part by RIHN Project (Grant No. #D06-14200119), the River Foundation (Grant Nos. #28-5211-047 & 261211010), and the Grant-in-Aid for Scientific Research (Grant Nos. #JP24370010; #JP15K16115; #JP18K11623) from the Japan Society for the Promotion of Science. We also thank Ms. Ijin Kang for helping our field survey. Sampling of riverbed rocks was conducted with the permission of Kinki Regional Development Bureau Office, Ministry of Land, Infrastructure, Transport and Tourism of Japan. Public sewage division of Koka and Yasu in Shiga Prefecture provided monitoring data on small-scale WWTPs and logistic support for the sampling of their effluents. Central Glass Co., Ltd. and the public sewage division of Shiga Prefecture provided the stock solution of manufactured chemical fertilizers and annual report of the public sewage program in Shiga Prefecture, respectively.
Funding Information:
This work was supported in part by RIHN Project (Grant No. #D06-14200119), the River Foundation (Grant Nos. #28-5211-047 & 261211010), and the Grant-in-Aid for Scientific Research (Grant Nos. #JP24370010; #JP15K16115; #JP18K11623) from the Japan Society for the Promotion of Science. We also thank Ms. Ijin Kang for helping our field survey. Sampling of riverbed rocks was conducted with the permission of Kinki Regional Development Bureau Office, Ministry of Land, Infrastructure, Transport and Tourism of Japan. Public sewage division of Koka and Yasu in Shiga Prefecture provided monitoring data on small-scale WWTPs and logistic support for the sampling of their effluents. Central Glass Co., Ltd. and the public sewage division of Shiga Prefecture provided the stock solution of manufactured chemical fertilizers and annual report of the public sewage program in Shiga Prefecture, respectively.
Publisher Copyright:
© 2020, The Japanese Society of Limnology.
PY - 2020/8/1
Y1 - 2020/8/1
N2 - We compared the oxygen isotope ratio of dissolved phosphate (δ18OPO4) in two rivers with different land-cover and geological features (Ado River and Yasu River) within Lake Biwa basin, central Japan, to explore what factor primarily characterizes the δ18OPO4. Mean values of δ18OPO4 in river water were 19.0 ± 2.4‰ (n = 7) in Ado River and 13.1 ± 2.3‰ (n = 15) in Yasu River, which were significantly different. Comparisons of δ18OPO4 between river water and potential sources of phosphate revealed that in the Ado River, the δ18OPO4 was similar to that in rocks from the accretionary complex and decreased with increasing sedimentary rock coverage. In the Yasu River, the δ18OPO4 was low in the upper forested areas, but increased with paddy field coverage. These results demonstrate that river δ18OPO4 strongly reflects inputs from geological substances, but is also impacted by land-use activities and varies with anthropogenic land coverage in the watershed. Thus, river δ18OPO4 relates to land or bedrock coverage differentially in each river. Regression analysis showed that residuals of the δ18OPO4 tended to converge to zero with increasing drainage area, suggesting that river δ18OPO4 more explicitly reflects land-cover and geological features on a larger watershed scale.
AB - We compared the oxygen isotope ratio of dissolved phosphate (δ18OPO4) in two rivers with different land-cover and geological features (Ado River and Yasu River) within Lake Biwa basin, central Japan, to explore what factor primarily characterizes the δ18OPO4. Mean values of δ18OPO4 in river water were 19.0 ± 2.4‰ (n = 7) in Ado River and 13.1 ± 2.3‰ (n = 15) in Yasu River, which were significantly different. Comparisons of δ18OPO4 between river water and potential sources of phosphate revealed that in the Ado River, the δ18OPO4 was similar to that in rocks from the accretionary complex and decreased with increasing sedimentary rock coverage. In the Yasu River, the δ18OPO4 was low in the upper forested areas, but increased with paddy field coverage. These results demonstrate that river δ18OPO4 strongly reflects inputs from geological substances, but is also impacted by land-use activities and varies with anthropogenic land coverage in the watershed. Thus, river δ18OPO4 relates to land or bedrock coverage differentially in each river. Regression analysis showed that residuals of the δ18OPO4 tended to converge to zero with increasing drainage area, suggesting that river δ18OPO4 more explicitly reflects land-cover and geological features on a larger watershed scale.
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U2 - 10.1007/s10201-020-00610-6
DO - 10.1007/s10201-020-00610-6
M3 - Article
AN - SCOPUS:85082952035
SN - 1439-8621
VL - 21
SP - 365
EP - 377
JO - Limnology
JF - Limnology
IS - 3
ER -
