TY - JOUR
T1 - Sources of hydroxyl radical in headwater streams from nitrogen-saturated forest
AU - Chiwa, Masaaki
AU - Higashi, Naoko
AU - Otsuki, Kyoichi
AU - Kodama, Hiroki
AU - Miyajima, Tohru
AU - Takeda, Kazuhiko
AU - Sakugawa, Hiroshi
N1 - Funding Information:
We thank Professor N. Nakatani of Rakuno Gakuen University and Dr. H. Kondo of Hiroshima University for technical support. The cost of publication was supported in part by a Research Grant for Young Investigators of the Faculty of Agriculture, Kyushu University. This research was partially supported by “Rehabilitation of Ariake Bay and demonstration of rehabilitation technologies” in a research and development program for resolving critical issues commissioned by the Ministry of Education, Culture, Sports, Science and Technology, Japan.
Publisher Copyright:
© 2014 Elsevier Ltd.
PY - 2015/1/1
Y1 - 2015/1/1
N2 - Hydroxyl radical (HO) photoformation rate (RHO) was determined in headwater stream samples from nitrogen (N)-saturated forests, (1) to quantify the sources of HO in headwater streams and (2) to evaluate the nitrate NO3--induced enhancement of HO formation in stream water caused by N saturation in forested watersheds. Stream water fulvic acid extracted from the forested watersheds was used to quantify the contribution of dissolved organic matter (DOM) to RHO. The results showed that almost all (97%; 81-109%) RHO sources in our headwater stream samples were quantitatively elucidated; the photolysis of NO3- (55%; 34-75%), nitrite [N(III)] (2%; 0.5-5.2%), and DOM-derived HO formation, from which photo-Fenton reactions (18%; 12-26%) and the direct photolysis of fluorescent dissolved organic matter (FDOM) (22%; 10-40%), was successfully separated. FDOM, which accounted for 53% (24-96%) of DOM in total organic carbon bases, was responsible for HO formation in our headwater streams. High NO3- leaching caused by N saturation in forested watersheds increased RHO in the headwaters, indicating that N-saturated forest could significantly change photoinduced and biogeochemical processes via enhanced HO formation in downstream water.
AB - Hydroxyl radical (HO) photoformation rate (RHO) was determined in headwater stream samples from nitrogen (N)-saturated forests, (1) to quantify the sources of HO in headwater streams and (2) to evaluate the nitrate NO3--induced enhancement of HO formation in stream water caused by N saturation in forested watersheds. Stream water fulvic acid extracted from the forested watersheds was used to quantify the contribution of dissolved organic matter (DOM) to RHO. The results showed that almost all (97%; 81-109%) RHO sources in our headwater stream samples were quantitatively elucidated; the photolysis of NO3- (55%; 34-75%), nitrite [N(III)] (2%; 0.5-5.2%), and DOM-derived HO formation, from which photo-Fenton reactions (18%; 12-26%) and the direct photolysis of fluorescent dissolved organic matter (FDOM) (22%; 10-40%), was successfully separated. FDOM, which accounted for 53% (24-96%) of DOM in total organic carbon bases, was responsible for HO formation in our headwater streams. High NO3- leaching caused by N saturation in forested watersheds increased RHO in the headwaters, indicating that N-saturated forest could significantly change photoinduced and biogeochemical processes via enhanced HO formation in downstream water.
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U2 - 10.1016/j.chemosphere.2014.02.046
DO - 10.1016/j.chemosphere.2014.02.046
M3 - Article
C2 - 24630456
AN - SCOPUS:84919752862
SN - 0045-6535
VL - 119
SP - 1386
EP - 1390
JO - Chemosphere
JF - Chemosphere
ER -