別紙4I q果程博̲ト(英文))Date 01' submission (nlonth day, yeal')
DcpaTlmcnt of ArchileclLⅡ'e andKurikoYokotaSludel]tlD N山nbel

D189503
SupervisoTS

Civil Engineel'ing
Ppljcan[、s namo

J111y 9,2021

PertiwiAI)darani

Takanobu lnoue

Shigeru Kato

Abstract (Doctor)
Title ofT11esisSpatio・ten)poralvariation assessn〕ent ot zinc concentrations and loads
and 北S S01Ⅱ'ce identification ln Ylveys

Approx.80O W01'dsZinc (zn) is cnlcial for Hfe and plays a vital part in organisl〕〕S' bi010gical activities (11LⅡ11ans, anilnals, andPlanls). zn,11〕e fourth‑most fl、equcnt metal in usage、 is widely used in the indusu'ial sect01' 10 create
Products. zn is the d)ird‑1nost produced non寸でΠ'ous lnetalin japal〕 and the third‑most released chemicali11、vater bodies' zn has becolne one of the lnost critical considerations concenlinσ WorldⅥdde 、入喰ter quality、

including in Japan, W北h 小e l'ole of pl'eS引'ving aquaLic lirc. slncC 2003,小e Japanese Minislry of lhe
Environment has establiS11ed 1Ⅱ) environmel〕tal quality standard (EQS) for zn in sulface water (0.030 mg/L)
to conserve aquatic lifc. However, multiple Japanese rivers sti11 Could not comply with 廿le EQs in 2019
Thcrer01'e,1his sludy aimed to asscss thc spatial and lemporal val'iation and {he source idenlincation ofzn innear‑neutralriV釧'S

This study was conducted in two riva'S, affected mail〕1y by urban areas (manufactuling induS廿ies) andaσricU11山e localed in the vicinily of Aizumame Rjver and u〕e un〕eda River, Aichi, Japan. This sludy
Consisled of three slu'vey lypes, i.e., monlhly basenow survey (on sunny days), hourly baseao、N SUI ey (onSunny days during 、N'eekday and 圦妃ekend), and hourly stonl〕aow S11Wey (during a lain event). The lnonthly
baseaow survey and tlw l)ourly baseflow S山Vey wcrc unde11akcn in 血C Aizun〕ame River and the umeda
Rivel'. Becausc a fU11hel' inveS1喰ation of 小e possible zn source and lhe underlying factors of 11W zn
Val'iability was needed, n〕m'e detailed water paranleter nleaS1辻elnent was conducted in t11e umeda RiverXvaler parametcrs [zn, Fe (ir0川, paTⅡCulate organic carbon (POC)、 tempera山re, PH, electroconductivily、
C飢ions、 and anions] and riverbcd sedimen(S (zn, Fe, and poc in nne sand, medium sand, and coal'se sand)Were lneaS1Ⅱed accordil]gly. The n〕etal content was n】eaS1辻ed using atonlic absorption spectromen'y.
Hie松rchical clusler analysis dlcA), aow analysis、 pearson ca'relalion, principal compone川 factmloading
analysis (PCFA),10ad and disC11al'ge cU1刃e (L・Q modcl)、 and end member mixing analysis (EMMA) xvel'eP凱'fon〕1ed to assess t11e association among the parameters and to ldent廿y the potential zn s01ⅡCes,
In the <izLmlame River、 atthe two downstream sampHng stations (A4 = 0.059 mg/上; A5 = 0.055 mg/L),theEQs was breached in 2017. zn levels considerably varied rrom undetccted to o. Bり mg/L. Throughouttheye雛, zn concentrations along tl)e ulneda River nuctuated in spatial and temporal, tan部no n'om o.002 to0,090 lng/L. At tl〕e n〕ost do、vnsh'ealn part of dw un〕eda River, the annual nleal〕 concentration value of
0,031 mg/L exceeded 11W EQS. Antl)1'opogenic ac{ivilies have Hkely inauenced the riverine zn levels inUmeda River.

へ40st of ule zn concentrations ln tl〕e river water and wastcwata' were presel〕ted in a dissolved phase in t11e
Umeda RiYel・. seasonal variation also affecled {he zn nuctualion in watel',1n which the hig11es{ 1evel wasfound during tl〕e winter and spring. By contrast, in sununer and aUτいmn、 tl〕e zn conccntrations in d]eriverbed sediment were relatively higher than in other seasons.
The HCA ofobscrvatk"]revealed thatthe nliddle‑10wcrreach ofthe Ai2Ulnan〕e RiV田' and un]eda RiV飢'1]asbccn p011Uted by zn. Based on dw now analysis, the induslnal area alt11e downslTcam section conu'ibutcd
44ツ。(in summer) t088ツ。(in winter) of total zn loading in dlc Aizumalne River. HoweV飢'. in t11C UITlcda
RiV磁・, tl〕e industrial zn input (61%) was clearly obscrved only in spring. A f1ⅡthⅢ'(1ata analysis of 工入喰terPal・ameters in 小e umeda Rivel' was thus conducted to whC小er the vanabilily 、Nas afrccled by lhe watcr
Pal・ameters. Accordinσ to the HCA of Yariable in the un)eda River、 d〕e cations luld anions preS巳ⅡCe 田'e
σCneraⅡy less signiflcant in len11 0f n〕etal transpon and behavior colnP磁'ed lo para111eters such as pH、
01・ganic maⅡer, and 小C parliculale Fe. The dissolvcd zn 、Nas gl'ouped toge小Cr W1111 PH, POC, and HC03、.
171U・tl〕ennore、 reS111ts of C111Ster variable analysis wel'e veri6ed by pcFA、 which S110、入's t11at t11e dissolved zn(t0菖ether witl〕 PH, Na+, CI、, HC03、, POC、 ca2'、 and Mg2+) contributed to a varifact01 (industrial pointS0山・ces) which explains aboU1 15% of t11C lolal val'iance. MeanW11ile, pal'ticulale zn participated in 小e
Varifactor (agricultural so{1rccs)、 1'eprcsenting 17% of total variancc. Moreovcr、 particulate zn and Fe werc
also involved in the verifactor (inorganiC 介action of ss), constituting 8゜心 oft11C total variance.
The source identincation was also confirn〕ed by thc hour1ド Survcy. TI〕C I)ourl>' SLlrvey conducl・ed in

the baseaow during weekday and weekend revealed that the zn levels were remarkably higher
duYinσ Weekday, indicating that the lndustYlal po]nt soul'ces contnbuted to t11e Nverlne zn levels
both in the Aizumame River (57%) and the umeda River (67%). The Fe was potentiaⅡy originatedfrom natural occurrences、 During the stormaow. the Fe concentrations were lnalnly governed by

the suspended solids. The zn concenれ,ations relnained high f0110wing the dischaΥ又e Huctuation inthe storlnaow and had four subsequent peaks indicating theSourccs

X入7ereUbjquit(川SNevertheless, at the end of the storn〕aow, the zn source might have been relatlvcly reduced, as
Shown by lower concentYations. AlthoU牙h the zn was likely 6'om non、polnt souYces accoYdlng to the
L・Q model, severa] data poinもS did not fit the prediction il)terval of thc rcgression line' using thebaseaow and storlnaow loads colnparison and the ENINIA, approximately 74% ofthe zn loadings

Were ye]eased from point sources and tl〕e Yest was oylginated from non"polnt sources. Not on]yindustrial discharges buL also anLhropogenic non、point sources should be adequatcly managed 11〕
Order to lnaintain the zn levelbelow the toxlc threshold levelto the aquatic organlsms.