TY - JOUR
T1 - Identification of Phosphorus Sources in a Watershed Using a Phosphate Oxygen Isoscape Approach
AU - Ishida, Takuya
AU - Uehara, Yoshitoshi
AU - Iwata, Tomoya
AU - Cid-Andres, Abigail P.
AU - Asano, Satoshi
AU - Ikeya, Tohru
AU - Osaka, Ken'Ichi
AU - Ide, Jun'Ichiro
AU - Privaldos, Osbert Leo A.
AU - Jesus, Irisse Bianca B.De
AU - Peralta, Elfritzson M.
AU - Triño, Ellis Mika C.
AU - Ko, Chia Ying
AU - Paytan, Adina
AU - Tayasu, Ichiro
AU - Okuda, Noboru
N1 - Funding Information:
This research was supported by the RIHN Project (Grant No. D06-14200119) and the River Foundation (Grant Nos. 28-5211-047 and 261211010). The sampling of the riverbed rocks was conducted with permission of the Kinki Regional Development Bureau Office, Ministry of Land, Infrastructure, Transport & Tourism. The public sewage division of Koka City and Yasu City provided monitoring data on the small-scale WWTPs and logistic support to sample their effluents. The Central Glass Co., Ltd provided the stock solution of the manufactured chemical fertilizers. We thank T. Ohta, T. Haraguchi, and R. Shibata for their technical advice on data analysis.
Publisher Copyright:
© 2019 American Chemical Society.
PY - 2019/5/7
Y1 - 2019/5/7
N2 - Identifying nonpoint phosphorus (P) sources in a watershed is essential for addressing cultural eutrophication and for proposing best-management solutions. The oxygen isotope ratio of phosphate (δ18OPO4) can shed light on P sources and P cycling in ecosystems. This is the first assessment of the δ18OPO4 distribution in a whole catchment, namely, the Yasu River Watershed in Japan. The observed δ18OPO4 values in the river water varied spatially from 10.3‰ to 17.6‰. To identify P sources in the watershed, we used an isoscape approach involving a multiple-linear-regression model based on land use and lithological types. We constructed two isoscape models, one using data only from the whole watershed and the other using data from the small tributaries. The model results explain 69% and 96% of the spatial variation in the river water δ18OPO4. The lower R2 value for the whole watershed model is attributed to the relatively large travel time for P in the main stream of the lower catchment that can result in cumulative biological P recycling. Isoscape maps and a correlation analysis reveal the relative importance of P loading from paddy fields and bedrock. This work demonstrates the utility of δ18OPO4 isoscape models for assessing nonpoint P sources in watershed ecosystems.
AB - Identifying nonpoint phosphorus (P) sources in a watershed is essential for addressing cultural eutrophication and for proposing best-management solutions. The oxygen isotope ratio of phosphate (δ18OPO4) can shed light on P sources and P cycling in ecosystems. This is the first assessment of the δ18OPO4 distribution in a whole catchment, namely, the Yasu River Watershed in Japan. The observed δ18OPO4 values in the river water varied spatially from 10.3‰ to 17.6‰. To identify P sources in the watershed, we used an isoscape approach involving a multiple-linear-regression model based on land use and lithological types. We constructed two isoscape models, one using data only from the whole watershed and the other using data from the small tributaries. The model results explain 69% and 96% of the spatial variation in the river water δ18OPO4. The lower R2 value for the whole watershed model is attributed to the relatively large travel time for P in the main stream of the lower catchment that can result in cumulative biological P recycling. Isoscape maps and a correlation analysis reveal the relative importance of P loading from paddy fields and bedrock. This work demonstrates the utility of δ18OPO4 isoscape models for assessing nonpoint P sources in watershed ecosystems.
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U2 - 10.1021/acs.est.8b05837
DO - 10.1021/acs.est.8b05837
M3 - Article
C2 - 30938522
AN - SCOPUS:85064746297
SN - 0013-936X
VL - 53
SP - 4707
EP - 4716
JO - Environmental Science & Technology
JF - Environmental Science & Technology
IS - 9
ER -
