1. Mul i a ia e s a is ical analysis o wa e and sedimen quali y index 1
de elopmen : A s udy o an u ban i e suscep ibili y.2
2. E alua ion o an u ban i e suscep ibili y applying mul i a ia e s a is ical3
analysis o wa e and sedimen quali y index de elopmen . 4
5
Keywo ds: Quali y Index; P incipal Componen Analysis; U ban ca chmen ; Seasonali y 6
Abs ac : Applying a mul ime ic index o i e quali y e alua ion becomes sui able o 7
iden i ying hose si es suscep ible o ecological de e io a ion due o mul iple human 8
p essu es. In his s udy, a P incipal Componen Analysis was pe o med o de elop wa e 9
and su ace sedimen quali y indexes, allowing us (i) o weigh ing he in luence o each 10
indi idual en i onmen al a iable depending on he maximum g adien s obse ed o 11
his o ical da a moni o ed in he s udy i e , (ii) o conside he possible syne gism o 12
an agonism de i ed om he combined e ec o se e al pollu an s, and (iii) o exp ess 13
he quali y as a de ia ion wi h espec o a e e ence condi ions selec ed based on 14
biological da a p e iously ob ained. 15
Wa e and sedimen quali y indexes assis ed us in he apid de ec ion o he dele e ious 16
e ec o indus ial, was ewa e ea men plan s and, mainly, un ea ed u ban was ewa e 17
e luen s discha ges in o he Deba Ri e ca chmen . On he o he hand, high i e lows 18
helped o dilu e con amina ion enhancing wa e quali y om Janua y o Ma ch. Ri e 19
quali y also appea ed o be coupled o sedimen dynamics, since me als we e 20
p e e en ially adso bed on o sedimen s du ing he d y season, whe eas he e was po en ial 21
o me al mobiliza ion o wa e du ing sedimen esuspension in he we season. 22
The e o e, an annual de e mina ion o su ace sedimen s quali y becomes sui able o 23
moni o ing wa e quali y du ing he d y season, iden i ying hose si es which could 24
dese e special a en ion, and planning u u e s a egies o i e quali y imp o emen . 25
This is he accep ed manusc ip o he a icle ha appea ed in inal o m in Science o The To al En i onmen 711 : (2020) // A icle
ID 135026, which has been published in inal o m a h ps://doi.o g/10.1016/j.sci o en .2019.135026. © 2019 Else ie unde CC BY-
NC-ND license (h p://c ea i ecommons.o g/licenses/by-nc-nd/4.0/)
Howe e , wo limi a ions we e ound: (1) su ace sedimen was no app op ia e o wa e 26
physicochemical quali y moni o ing due o o ganic ma e and nu ien con inuous 27
ans o ma ion; and (2) a mul ime ic index did no p o ide a concise and de ini i e 28
quali y in o ma ion, hus a new ool o combining wi h quali y index was p oposed o 29
speci ically e alua e he wa e and su ace sedimen quali y a each loca ion. 30
1. In oduc ion 31
Wa e quali y index has become an app ecia e ool in e alua ing i e quali y since i 32
ans o ms mul iple en i onmen al indica o s measu emen s in o a single dimensionless 33
numbe . Consequen ly, quali y index assis s wa e au ho i ies, policy make s and also he 34
gene al public in apidly de ec ing spa ial and empo al ends, iden i ying pollu an s 35
sou ces, assessing egula o y policies and en i onmen al p og ams, and making 36
ecommenda ions o u u e imp o emen s (Yisa and Jimoh, 2010; Fino i e al., 2015; 37
Gi au e al., 2016). 38
Al hough many wa e quali y indexes ha e been de eloped and wo ldwide applied, 39
he e is s ill no commonly accep ed me hodology o index de elopmen . In gene al, he e 40
a e ou s eps unde aken: (1) indica o selec ion; (2) sub-index ob aining o 41
ans o ma ion o measu ed alues o a common scale; (3) assignmen o weigh s; and (4) 42
agg ega ion o weigh ed sub-index o compu e he inal index alue (Su adian e al., 43
2016). Typically, he in ol emen o expe judgemen (Delphi me hod) has been applied 44
o he i s h ee s eps in he o mula ion o he mos used indexes on a na ional o global 45
le el (e.g. Na ional Sani a ion Founda ion Wa e Quali y Index (B own e al., 1970), 46
Sco ish Resea ch De elopmen Depa men Index (SRDD, 1976), House’s Wa e 47
Quali y Index (House, 1986) o O egon Wa e Quali y Index (Cude, 2001)), hus 48
in oducing subjec i i y in he index elabo a ion p ocess. Howe e , applica ion o 49
mul i a ia e s a is ical echniques, such as P incipal Componen Analysis (PCA), could 50
help gain objec i i y and ce ain y. This me hod o e s he possibili y o in oducing 51
his o ical da a moni o ed a di e en loca ions along he s udy a ea, and he maximum 52
g adien s obse ed a e used o weigh ing he in luence o each indica o on wa e quali y 53
(URA, 2008; P impas e al., 2010; Selle e al., 2013). 54
Fo i e quali y e alua ion, sedimen s a e also app ecia ed as quali y indica o s 55
because o hei capaci y o con inuously accumula e pollu an s (De esa-Rey e al., 2010; 56
Ba oli e al., 2012). Thei anspo along he i e is also coupled o sedimen dynamics, 57
whe e suspended pa icles deposi ion a ou s pollu an s being accumula ed on he 58
i e bed and sedimen esuspension usually occu ing du ing lood e en s p omo es hei 59
mobiliza ion (Rügne e al., 2014; He e o e al., 2018). 60
To da e, nume ous indexes ha e been used o es ima ing he quali y o i e 61
sedimen s, such as he Geoaccumula ion Index (Igeo) (Now ouzi and Pou khabbaz, 62
2014), En ichmen Fac o (EF) (Kaushik e al., 2009), Po en ial Ecological Risk Index 63
(RI) (Kabi e al., 2011) o Pollu ion Load Index (PLI) (Banu e al., 2013). Howe e , hey 64
a e no based on ma ching chemical and biological da a (Bi ch, 2018). On he o he hand, 65
he so-called Sedimen Quali y Guidelines (SQGs), such as E ec s Range (ERM/ERL) 66
(Toka li, 2017), E ec s Le el (TEL/PEL) (Zheng e al., 2008) o Ecological Risk Fac o 67
(ERF) (Kabi e al., 2011), ha e been de eloped om empi ical and mechanis ic 68
app oaches, and used o indi idual chemicals o a mix u e o subs ances o sc een 69
con aminan s posing a isk o ben hic communi ies (Bi ch, 2018). Howe e , hey a e 70
pu ely addi i es and hey do no conside possible syne gism o an agonism de i ed om 71
he combined e ec o se e al pollu an s. 72
The o e all aim o his s udy is he e o e o de elop a mul ime ic index o bo h wa e 73
and su ace sedimen s, linking chemical wi h biological da a o a mo e eliable 74
e alua ion o he combining e ec o a ious en i onmen al indica o s on he quali y o 75
he Deba Ri e ca chmen . The speci ic objec i es we e (i) o use a mul i a ia e s a is ical 76
analysis enabling he conside a ion o possible syne gic/an agonis e ec , and he 77
quan i ica ion o he deg ee o closeness be ween he sampling si e and a e e ence 78
condi ions cha ac e is ics o he s udy a ea, (ii) o iden i y sou ces o an h opogenic 79
con amina ion in luencing he i e quali y, and (iii) o e alua e he in luence o 80
seasonali y on physical mechanisms go e ning he exchange o pollu an s be ween wa e 81
and su ace sedimen s. We hypo hesized ha combined analysis o wa e and su ace 82
sedimen quali y will p o ide us mo e comp ehensi e and de ailed in o ma ion abou he 83
suscep ibili y o a ca chmen subjec ed o mul iple human p essu es. 84
2. Ma e ials and me hods 85
2.1 S udy a ea and sampling desc ip ion 86
His o ically, he Deba Ri e ca chmen (538 km2, Fig. 1) has been no able o i s 87
g ea es ecological de e io a ion caused by a dense popula ion and an in ense indus ial 88
de elopmen , which con ibu e o me als, nu ien s and/o o ganic- ich compounds 89
discha ges in o he main i e and s eams (Ma ínez-San os e al., 2015). Un il he ecen 90
cons uc ion o a sewe age sys em and he commissioning o h ee was ewa e ea men 91
plan s (WWTPs) – he Ap ai z (2007), Mekolalde (2008) and Epele (2012) −, a mode a e, 92
poo o e en bad ecological po en ial was epo ed in he main i e , as well as in a ious 93
s eams like he Oña i and Ego (URA, 2013). Howe e , imp o emen s in he compliance 94
wi h he en i onmen al objec i es ha e been egis e ed o e he las yea s (2013-2017), 95
especially in he mid-high pa o he main i e and he Oña i s eam. E en he Ego 96
s eam, which con inues o g a ely b each all biological indica o s, p esen ed a sligh 97
posi i e change o he in e eb a e communi y and he ish auna in he las campaigns 98
(URA, 2018), p obably due o he cons uc ion and connec ion o he sewe om E mua-99
Eiba o he Ap ai z WWTP in June 2014. To da e, un ea ed u ban was ewa e s (UWW) 100
om Mallabia a e s ill discha ged in he Ego s eam (Fig. 1). 101
Acco ding o me eo ological and hyd ological da a measu ed and eco ded e e y 10 102
min since Oc obe 1995 in he Al zola gauging s a ion by Gipuzkoa P o incial Council 103
(www.gipuzkoa.eus/es/deba), mean annual p ecipi a ion (P) and discha ge (Q) o he las 104
en yea s (2008-2018) we e 1245 mm and 12.3 m3 s-1, espec i ely. The we es pe iod 105
ex ended om Janua y o Ma ch and he d ies mon hs we e usually om July o Oc obe . 106
The e o e, wo di e en se s o hyd ological condi ions we e es ablished du ing he 107
esea ch yea ( om Jan. ’15 o Jan. ’16): a high low o we season co esponding o 108
sampling campaigns wi h Q alues o o e 12 m3 s-1 (Jan.’15, Feb. ’15, Ma . ‘15 and Jan. 109
‘16); and a low low o d y season comp ising mon hs wi h Q alues o below 12 m3 s-1 110
(Fig. 1). 111
Wi h a iew o s udying he in luence o di e en an h opogenic con amina ion 112
sou ces on he i e wa e and su ace sedimen quali y, ele en loca ions along he Deba 113
Ri e ca chmen we e chosen: in he main i e (D1-D7), and in he Mazmela (M1), Oña i 114
(O1) and Ego (E1-E2) ibu a ies (Fig. 1). Mon hly o bimon hly wa e samples we e 115
collec ed in polye hylene bo les and wa e elec ical conduc i i y (EC) was measu ed in 116
si u wi h a C ison EC-Me e Basic 30+. By con as , su ace sedimen sampling was 117
exclusi ely ca ied ou on he campaign o Oc obe 2015, a low low mon h (1.435 m3 s-
118
1; Fig. 1), in an a emp o diminish he in luence o hyd ological pa e n o e he chemical 119
and, p edominan ly, biological cha ac e is ics. As pe USEPA (2001), su ace sedimen 120
subsamples (0-5 cm dep h) om mul iple poin s wi hin each sampling loca ion we e 121
collec ed using a s e ilized spoon, sie ed h ough a 2 mm mesh, composi ed in he ield 122
and sealed in s e ile polyp opylene con aine s. All wa e and sedimen samples we e 123
e ige a ed in he da k and anspo ed o he Chemical and En i onmen al Enginee ing 124
labo a o y (Uni e si y o he Basque Coun y) on he same day. 125
2.2 En i onmen al a iables analysis 126
Once in he labo a o y, wa e samples we e il e ed h ough 0.45 µm Milipo e 127
ni ocellulose il e . One eplica e o each sample was acidi ied o pH < 2 wi h HNO3 128
(69%) o ca ions (Ca2+, Mg2+, Na+ and K+) and me als (Cu, Zn, C , Ni and Pb) analysis 129
using ICP-OES (Pe kin Elme Op ima 2000) and an Ul asonic Nebulize (CETAC, 130
U5000AT+; only o me als). Dissol ed o ganic ca bon (DOC) and anions (NO3-, SO42- 131
and Cl-) we e measu ed in he non-acidi ied eplica e using a To al O ganic Analyze 132
(TOC-L Shimadzu) and an ion ch oma og aphy (DIONEX ICS 3000), espec i ely. 133
Addi ionally, concen a ion o NH4+ was de e mined by he modi ied Be helo eac ion. 134
The asco bic acid me hod (4500-P E) and he N-(1-naph hly) e hylenediamine 135
dihyd ochlo ide me hod (4500-NO2- B) we e used o PO43- and NO2- de e mina ion, 136
espec i ely (APHA-AWWA-WPCF, 2018). 137
Su ace sedimen s samples (< 2mm) we e ai -d ied and g ound wi h a pes le and 138
mo a o homogeniza ion. Thei mois u e con en was de e mined in acco dance wi h 139
APHA-AWWA-WPCF (2018). One eplica e o each sample was di ec ly s o ed esh a 140
-20 ºC o pe o ming a DNA ex ac ion and a eal- ime quan i a i e PCR analysis. 141
Analysis o chemical a iables. To al ca bon (TC) and ni ogen (TN) we e analysed 142
using a T uSpec CHNS Elemen al De e mina o (Leco Co po a ion). To al o ganic 143
ca bon (TOC) was de e mined as desc ibed in Me hod 2540 E (APHA-AWWA-WPCF, 144
2018). To al ino ganic ca bon (TIC) was calcula ed by he di e ence be ween TC and 145
TOC. Ino ganic ni ogen (NH4+ and NO3ˉ) was measu ed a e 2M KCl ex ac ion 146
(Mul aney, 1996) using a Jasco V630 spec opho ome e . To al o ganic ni ogen (TON) 147
was calcula ed by he di e ence be ween TN and ino ganic ni ogen. 148
Based on he me hodology desc ibed in a p e ious s udy (Unda-Cal o e al, 2017) o 149
es ima e he po en ial o me als o cause non-ca cinogenic ha m ul e ec s in exposed 150
people (child en) o con amina ed su ace sedimen s, haza d quo ien (HQ) was 151
calcula ed as shown in he ollowing equa ion: 152
HQ= /
(1) 153
Chemical daily in ake (CDI) ep esen s he possible en y o me als (mg kg-1 day-1) 154
in o he human body, B is he pe cen age o bioaccessible me al pseudo-con en in su ace 155
sedimen s when human gas ic o in es inal en i onmen al condi ions we e ep oduced, 156
and R D is he es ima ed amoun o he daily o al exposu e le el o he popula ion ha 157
is likely no o ha e an app eciable isk o dele e ious e ec s du ing i s li e ime. I he 158
sum o HQ co esponding o he gas ic and in es inal bioaccessibili ies (∑HQ) o a leas 159
one o he me als (Cu, Zn, C , Ni and Pb) conside ed a each si e exceeds 1, he su ace 160
sedimen may be a conce n o po en ial ha m ul e ec s. 161
Analysis o biological a iables. A e DNA ex ac ion om su ace sedimen samples 162
(0.25 g o d y weigh sedimen ) using Powe SoilTM DNA Isola ion Ki , eal- ime qPCR 163
(qPCR) was ca ied ou o deni i ying genes (ni K, ni S and nosZ) measu emen s as 164
desc ibed in Ma ínez-San os e al. (2018). The a io nosZ:ni was calcula ed, whe e ni 165
co esponds o he sum o ni K and ni S. 166
Addi ionally, he ac i i y o Ni a e Reduc ase (NR) – he enzyme esponsible o 167
educing NO3- o NO2- in deni i ica ion– o each su ace sedimen sample was analysed 168
ollowing he p ocedu e es ablished in a p e ious s udy (Unda-Cal o e al., 2019a). Since 169
NR ac i i y was conside ed he main limi ing s ep o deni i ica ion, and in o de o 170
es ima e he capaci y o he mic obial communi ies ha bou ed in he su ace sedimen s 171
o cumula i e ni a e comple e elimina ion, he au ho s p oposed he calcula ion o he 172
Response Time as shown in he ollowing equa ion: 173
Response Time (min)=
( )
(
) (2) 174
All analy ical p ocedu es o bo h wa e and su ace sedimen samples we e pe o med 175
in iplica e. 176
2.3 S a is ical analysis o i e quali y assessmen 177
All s a is ical p ocessing o he da a desc ibed below we e pe o med using SPSS 22.0 178
so wa e. 179
2.3.1 Va iables and e e ence condi ions selec ion c i e ia 180
In gene al, simila en i onmen al a iables we e in ol ed in he quali y index 181
de eloped in di e en epo s (Şene e al., 2017; Wang e al., 2017; Bi ch, 2018). 182
Howe e , since his esea ch aims a e alua ing he in luence o an h opogenic 183
con amina ion on wa e and su ace sedimen quali y, EC, DOC, nu ien s (PO43-, NO3-, 184
NO2-, NH4+) and dissol ed me als (Cu, Zn, Pb, Ni and C ) we e selec ed as indica o s o 185
wa e quali y; ins ead, TOC, TIC, NO3-, NH4+, TON and haza dous quo ien (∑HQ) o 186
a ious me als (Cu, Zn, Pb, Ni and C ) we e used o he de elopmen o sedimen quali y 187
index. All hese a iables a e known o al e biological quali y o i e s, ha e a educed 188
analy ical cos and help o iden i ying he impac o human ac i i ies. 189
Fi s ly, all da a we e log- ans o med in o de o educe he skewness. A e applying 190
he Le ene’s es o con i m which a iables had equali y o a iance o no , one-way 191
ANOVA ( aking ρ < 0.05 as signi ican , in acco dance wi h Tukey’s mul iple ange es ) 192
and he U-Mann Whi ney non-pa ame ic es we e pe o med, espec i ely. Examina ion 193
o signi ican di e ences among sampling si es helped us o ecognize he an h opogenic 194
o igin o a iables. In addi ion, a Spea man co ela ion analysis (non-pa ame ic es ) was 195
pe o med o iden i y common sou ces. 196
The es ablishmen o e e ence condi ions is an essen ial second s ep since he quali y 197
o any sampling loca ion mus be exp essed as a de ia ion wi h espec o hose 198
condi ions. Acco ding o WFD CIS guidance documen No. 10 (REFCOND, 2003), 199
e e ence condi ions shall be ep esen ed by alues o he ele an biological quali y 200
elemen s (i.e., composi ion and abundance o aqua ic lo a, composi ion and abundance 201
o ben hic in e eb a e auna o composi ion, abundance and age s uc u e o ish auna) 202
in classi ica ion o ecological s a us. Al e na i ely, mic oo ganisms a e also pa icula ly 203
sui able o he moni o ing o i e quali y due o hei key ole in biogeochemical cycling 204
and hei sensi i i y and quick esponse o any ecosys em pe u ba ion (Chae e al., 2009; 205
Guo e al., 2012). 206
The nosZ:ni a io ep esen s he ela i e abundance o he ni ous oxide educ ase 207
(nosZ) gene – esponsible o he con e sion om N2O o N2 – wi h espec o he ni i e 208
educ ase genes (ni = ni S + ni K) - esponsible o he educ ion o NO2- o NO. Whe eas 209
ni S and ni K a e conside ed o be uni e sal o all deni i ie s (Azziz e al., 2017), nosZ 210
gene lack was obse ed (Jones e al., 2008; Ligi e al., 2014). Consequen ly, a low 211
nosZ:ni a io will sugges ha N2O g eenhouse gas emissions could be expec ed as a 212
esul o an incomple e deni i ica ion. In addi ion, since he p esence o deni i ying 213
bac e ia does no necessa ily imply ha i is ope a ing (Ve aa e al., 2017), he Response 214
Time was also used o ensu e he mic obial communi y capaci y o comple ely elimina e 215
he ni a e excess. The e o e, we used a combina ion o hese pa ame e s in ol ed in 216
mic obial deni i ica ion in su ace sedimen s, – he p ocess by which NO3- and NO2- a e 217
educed o NO and N2O, and inally a e con e ed o N2 and e u ned o he a mosphe e 218
–, as i e biological quali y indica o o e e ence condi ions es ablishmen . 219
Zn-Pb-Cu (∑HQ) in su ace sedimen s. As obse ed, me al a ailabili y and, hence, me al 365
bioaccessibili y in sedimen s modula es hei oxici y. In ac , while C -Ni we e 366
p edominan ly e ained in he mine al la ice o su ace sedimen s, Pb was he mos 367
a ailable me al (Unda-Cal o e al., 2019b). 368
Acco ding o wa e QI spa ial dis ibu ion (Fig. 4A), he highes median alue was 369
de ec ed a headwa e s (D1, E1), and a he Mazmela (M1) and Oña i (O1) ibu a ies, 370
while he lowes median alue was a E2, bo h o physicochemical a iables (I) and 371
speci ic pollu an s (II). Despi e he high impac o indus ial ac i i ies, i is especially 372
no iceable he imp o emen o he Oña i ibu a y wa e quali y o a le el simila o hose 373
non-impac ed si es (D1, M1 and E1), also egis e ed by he Basque Wa e Boa d (URA, 374
2018). Howe e , he wa e quali y was be e when physicochemical a iables we e 375
conside ed (all samples a O1 had a QI alue abo e 0.5) han wi h speci ic pollu an s 376
(almos 25% o samples a O1 had QI alue below 0.5). 377
Rega ding con amina ion sou ce ype (Fig. 1), e luen s om WWTPs and, 378
p imo dially, un ea ed UWW seem o ha e mo e nega i e e ec s on wa e 379
physicochemical quali y han exclusi ely indus ial was ewa e s. In ac , median wa e 380
QI based on physicochemical a iables was highe a D2-D4-D6 han a D3-D5-D7 and, 381
especially, a E2 (Fig. 4A). In con as o D2-D4-D6, mo e han 75% o samples had a QI 382
alue below 0.5 a D3-D5-D7 and a E2. Mo eo e , samples pe cen age wi h QI alue 383
below 0.5 inc eased om less han 25% a D2 o mo e han 25% a D4 and o mo e han 384
50% a D6, due o he indi ec impac o he Mekolalde WWTP and he Ego ibu a y, 385
espec i ely. Con e sely, ad e se e ec s o speci ic pollu an s on wa e quali y could no 386
be dis inguished based on con amina ion sou ce ype. Compa ed o a 20 % o de ia ion 387
among physicochemical QI median alues, D2-D3-D4-D5 showed a highe homogenei y 388
(almos 3% o de ia ion among median alues) conce ning speci ic pollu an s and, 389
he e o e, he nega i e e ec s o indus ial ac i i ies o WWTPs becomes indisce nible. 390
Su ace sedimen QI shows he same spa ial end as wa e (Fig. 4A), whe e he 391
highes median alues we e exhibi ed a headwa e s (D1 and E1) while he lowes 392
median alues was ound a E2, bo h o physicochemical a iables (I) and speci ic 393
pollu an s (II). Mo eo e , he in luence o an h opogenic ac i i ies on su ace sedimen 394
quali y was mo e p onounced. Rega ding e luen s om WWTPs, simila wa e quali y 395
was de ec ed downs eam o he Epele and Mekolalde WWTPs (D3 and D5, 396
espec i ely), and lowe downs eam o Ap ai z WWTP (D7) due o he Ego ibu a y 397
con luence. Howe e , he inc ease o TIC, NO3- and NH4+ con en in su ace sedimen s 398
downs eam o Epele WWTP (Table S2) was so conside able ha he physicochemical 399
quali y was lowe a D3 (QI < 0.5) and, e en a D4, han a D7 (Fig. 4A). In addi ion, 400
speci ic pollu an s load om indus ial ac i i ies ex emely de e io a ed su ace 401
sedimen quali y a D2 and D4 (75% and 100% o QI educ ion compa ed o D1 and 402
D3, espec i ely). 403
3.3 E ec s o seasonali y and sedimen dynamics on wa e quali y 404
The in luence o he hyd ological condi ions on he quali y o he Deba Ri e was also 405
e alua ed. O e all, he wa e quali y was be e om Janua y o Ma ch han om May o 406
No embe , as exhibi ed by he 25 h pe cen ile o QI alues calcula ed o he we and he 407
d y seasons, espec i ely (Fig. 4A). Howe e , his is no ue a hose sampling si es (D1, 408
M1, D2, O1 and E1) whe e highe median alues o he mos in luencing en i onmen al 409
a iables (PO43--NO3--NO2--NH4+) we e obse ed o he we season (Table S1). Despi e 410
win e ain alls inc eased i e discha ge measu ed in he Al zola gauging s a ion (R2 = 411
0.65; Fig. 1) and, consequen ly, migh a ou con amina ion dilu ion, p e ious indings 412
sugges ed ha he shallow dep h o he wa e column oge he wi h he ab up slope a 413
jus ups eam om hese si es (Fig. 1) could p omo e highe sedimen esuspension 414
(Unda-Cal o e al., 2019b). Resuspension oge he wi h changes in he pH o he 415
oxida ion condi ions o he i e en i onmen caused by loods could p omo ed he 416
elease o elemen s (e.g. o ganic ma e , N, P o me als) apped in su ace sedimen s o 417
he o e lying wa e (Zhu e al., 2017; Camino Ma ín-To e e al., 2017; Pe anich e al., 418
2018), con ibu ing o i s quali y decline. In ac , a p e ious s udy (Ga cía-Ga cía e al., 419
2019) ocused on e alua ing he a iabili y o pa icula e me al pollu ion du ing lood 420
e en s in he Deba Ri e ca chmen es ablished hyd odynamic p ocesses as main ac o 421
con olling he beha iou o pa icula e me als. 422
Sedimen plays an impo an ole in con amina ion ans e be ween aqua ic 423
en i onmen compa men s, ac ing as a sink o sou ce o many pollu an s. Fo a mo e 424
accu a e e alua ion o he kindness o su ace sedimen analysis o a apid wa e quali y 425
moni o ing, linea eg essions we e applied be ween wa e and sedimen QIes du ing wo 426
hyd ological se s (Fig. 4B). As opposed o physicochemical a iables (I), a lux o 427
speci ic pollu an s (II) in he sedimen -wa e in e ace could be well iden i ied, especially 428
o he d y season. Me als a e nonbiodeg adable and, consequen ly, long pe sis en ; 429
he e o e, physical and biochemical p ocesses only could con ol hei mobili y (Violan e 430
e al., 2010), simpli ying he comp ehension o me al exchange a he wa e -sedimen 431
in e ace. Con e sely, o ganic ma e and nu ien s a e subjec ed o a con inuous 432
ans o ma ion in i e en i onmen ; hus, se e al p ocesses should be also conside ed o 433
a ealis ic modelling o o ganic ma e and nu ien luxes be ween wa e and sedimen 434
(Thou eno e al., 2007). This ac illus a es how an annual de e mina ion o 435
bioaccessible me al in su ace sedimen s can be applied as an app op ia e s a egy o 436
moni o ing me al-dependen wa e quali y, and o iden i ying hose si es which could 437
dese e special a en ion, especially du ing he d y pe iod in which he i e quali y migh 438
be se e ely comp omised. 439
I should be no ed ha su ace sedimen s unde es ima e wa e quali y based on speci ic 440
pollu an s (II), excep a D1, D3 and E1 (Fig. 4B). The high capaci y o su ace sedimen s 441
o adso b me als om he o e lying wa e has been ex ensi ely discussed (Li e al., 2014; 442
Lundy e al., 2017; Chu e al., 2019), and o ganic ma e con en has been epo ed as a 443
key ac o con olling me al adso p ion (Yang e al., 2010). Indeed, Zn, Cu and C 444
adso p ion on o su ace sedimen s, which we e no ably bound o he oxidizable ac ion 445
( om 17.7% o 30.3% o he pseudo- o al con en ; Unda-Cal o e al., 2019b), seems o 446
be a ou ed by a posi i e o ganic ma e g adien be ween wa e and sedimen s (Fig. S2). 447
The good linea ela ionship obse ed be ween physicochemical a iables-dependen and 448
speci ic pollu an s-dependen QIes o wa e samples du ing he d y season (Fig. 5A) 449
sugges s a common sou ce o bo h en i onmen al a iables ca ego ies along he 450
ca chmen , posing he physicochemical ones a highe h ea o he wa e quali y 451
downs eam o D2 and in he Ego ibu a y. Con e sely, his beha iou al pa e n changed 452
du ing he we season o ano he closely ela ed o su ace sedimen s, whe e speci ic 453
pollu an s g ea ly condi ioned hei quali y (Fig. 5B). The al e a ion on me al pe o mance 454
wi h i e hyd ological condi ions e idences ha su ace sedimen s ac as sink o 455
dissol ed me als du ing sedimen a ion in he d y season, whe eas he e is po en ial o 456
mobiliza ion o a ailable me als in su ace sedimen s o he o e lying wa e du ing 457
sedimen esuspension in he we season. 458
Fo iden i ying he key en i onmen al a iable esponsible o he decline o wa e and 459
su ace sedimen quali y along he i e du ing he d y season, he con ibu ion pe cen age 460
o each a iable was calcula ed (Fig. 6). Sampling si es wi h wa e QI (25 h pe cen ile o 461
alues) abo e 0.5 o he d y season (D1, M1, D2, O1 and E1; Fig. 4A) p esen ed posi i e 462
con ibu ions o almos all physicochemical a iables, excep o EC (specially a D2) and 463
DOC (mainly a E1). While g oundwa e ci cula ion om e apo i ic ocks was iden i ied 464
as esponsible o high EC alues om D1-M1 o D2, soil e osion and he subsequen 465
o ganic ma e solubiliza ion could o igina e high DOC con en s in wa e a E1. On he 466
o he hand, sampling si es wi h wa e QI (25 h pe cen ile o alues) below 0.5 o he d y 467
season (D3, D4, D5, E2, D6 and D7; Fig. 4A) p esen ed nega i e con ibu ions o all 468
physicochemical a iables, being DOC and ino ganic ni ogen (NO3-, NO2- o NH4+) he 469
key ac o s declining wa e quali y. Each con amina ion sou ce ype (Fig. 1) seems o 470
di e en ly al e ni ogen cycle along he i e . While NO3- con en in wa e a si es 471
immedia ely downs eam o WWTPs (D3, D5 and D7) a e o g ea e conce n, NH4+ and, 472
p imo dially, NO2- om un ea ed UWW de e io a ed wa e quali y a E2. Those si es 473
wi h di ec impac o indus ial ac i i ies bu indi ec in luence o WWTPs e luen s (D4) 474
o UWW (D6) p esen ed a combina ion o high NO3-+NO2- nega i e con ibu ion o wa e 475
quali y (bo h be ween 20-30%; Fig. 6). 476
Rega ding speci ic pollu an s, all sampling si es excep D1 p esen ed nega i e 477
con ibu ion o some me al. Despi e hei non-pollu ed na u e, headwa e s om he 478
Mazmela (M1) and he Ego (E1) ibu a ies p esen ed nega i e CP o Pb o wa e quali y, 479
possibly as a esul o he solubiliza ion o mobile Pb in su ace sedimen s. Among he 480
si es wi h wa e QI (25 h pe cen ile o alues) below 0.5 o he d y season (D4, D5, E2, 481
D6 and D7; Fig. 4A), hose which showed high nega i e CP o C +Cu+Zn (a leas 50%; 482
Fig. 6) had he wo s wa e quali y. 483
Only su ace sedimen s om D3 and E2 showed physicochemical QI alues below 0.5 484
(Fig. 4A), being NO3- he main physicochemical a iable con ibu ing o he decline o 485
sedimen quali y. The high Time Response and he low nosZ:ni a io measu ed a hese 486
si es (Table S2) indica e a low po en ial o deni i ying he excess o ni a es. On he 487
o he hand, su ace sedimen s om D2, D4, D5, E2 and D7 p esen ed a low quali y (QI 488
< 0.5; Fig. 4A), mainly due o he high nega i e CP o Cu, Zn and, p incipally, Pb (>50% 489
o nega i e con ibu ion a D4 and D5). 490
In conjunc ion wi h he QI, calcula ing he CP o en i onmen al a iables o i e 491
quali y also becomes an essen ial ool o basin manage s o speci ically e alua e he 492
quali y decline a each sampling si e. In ac , despi e he low in luence (wj; Table 2) o 493
DOC and dissol ed Pb on wa e quali y wi h espec o o he en i onmen al a iables 494
in ol ed in QI calcula ion, hey we e he main cause o he bad quali y egis e ed a D6 495
and D7 (Fig. 6). 496
4. Conclusions 497
Recogni ion o he suscep ibili y o a ca chmen subjec ed o mul iple human p essu es 498
is essen ial o an e ec i e decision-making o manage s, whose mission aims o 499
achie ing a sus ainable de elopmen o an u ban ecosys em oge he wi h he compliance 500
o he en i onmen al objec i es es ablished by he Eu opean Wa e F amewo k Di ec i e 501
(WFD, 2000/60/CE). In his con ex , a mul ime ic index was a use ul ool o e alua ing 502
he combined e ec o a ious en i onmen al indica o s on i e quali y. Pe o ming a 503
PCA o he quali y index de elopmen allowed us (i) o assign a weigh o ela i e 504
in luence on he o e all quali y o each en i onmen al indica o acco ding o he s a is ical 505
dis ibu ion (mean and s anda d de ia ion) o all moni o ed da a, and (ii) o exp ess he 506
quali y as a de ia ion wi h espec o a e e ence condi ions, as equi ed by he WFD 507
(2000/60/CE). 508
The discha ge o indus ial, WWTP and, mainly, un ea ed UWW e luen s in o he 509
Deba Ri e ca chmen inc eased o ganic ma e , nu ien and me al con en in wa e and 510
su ace sedimen s, hence con ibu ing o a lowe QI, especially in he Ego ibu a y, and 511
mid- and downs eam o he main i e . On he o he hand, high lows helped o dilu e 512
con amina ion and, he e o e, highe wa e QI was obse ed om Janua y o Ma ch. 513
Hyd ological condi ions also seemed o induce di e en beha iou al pa e n o sedimen s, 514
ac ing as me al sink in he d y season, whe eas he e is po en ial o me al mobiliza ion 515
o wa e du ing sedimen esuspension in he we season. The e o e, an annual 516
de e mina ion o su ace sedimen s QI becomes sui able o moni o ing wa e quali y 517
du ing he d y season, iden i ying hose si es which could dese e special a en ion, and 518
planning u u e s a egies o i e quali y imp o emen . Two limi a ions we e ound: (1) 519
su ace sedimen was no app op ia e o wa e physicochemical quali y moni o ing due 520
o o ganic ma e and nu ien con inuous ans o ma ion; and (2) a mul ime ic index did 521
no p o ide a concise and de ini i e quali y in o ma ion, hus he calcula ion o bo h he 522
QI and he CP o en i onmen al a iables was p oposed o speci ically e alua e he wa e 523
and su ace sedimen quali y a each loca ion. 524
Acknowledgemen s 525
The au ho s wish o hank he Minis y o Economy and Compe i i eness (CTM2014-526
55270-R), he Basque Go e nmen (Consolida ed G oup o Hyd ogeology and 527
En i onmen , IT1029-16) and he Uni e si y o he Basque Coun y (UPV-EHU, 528
UFI11/26) o suppo ing his esea ch. 529
Re e ences 530
Alloway, B.J., Jackson, A.P., 1991. The beha iou o hea y me als in sewage sludge-amended soil. Sci. To al En i on. 100, 151–176. 531 APHA-AWWA-WPCF (Ame ican Public Heal h Associa ion, Ame ican Wa e Wo ks Associa ion & Wa e Pollu ion Con ol 532 Fede a ion), 2018. S anda d Me hods o he Examina ion o Wa e and Was ewa e . Am. Public Assoc., Washing on, DC. 533 A ailable online a : h ps://www.s anda dme hods.o g/abou / 534 Azziz, G., Monza, J., E chebehe e, C., I isa i, P., 2017. ni S- and ni K- ype deni i ie communi ies a e di e en ially a ec ed by soil 535 ype, ice cul i a and wa e managemen . Eu . J. Soil Biol. 78, 20-28. h ps://doi.o g/10.1016/j.ejsobi.2016.11.003. 536 Banu, Z., Chowdhu y, M.S.A., Delwa , M.H., Nakagami, K., 2013. Con amina ion and ecological isk assessmen o hea y me al in 537 he sedimen o Tu ag Ri e , Bangladesh: an index analysis app oach. J. Wa e Resou . P o . 5, 239–248. 538 h ps://doi.o g/10.4236/jwa p.2013.52024 539 Ba oli, G., Papa, S., Sagnella, E., Fio e o, A., 2012. Hea y me al con en in sedimen s along he Calo e i e : ela ionships wi h 540 physical–chemical cha ac e is ics. J. En i on. Manag. 91, S9–S14. h p://dx.doi.o g/10.1016/j.jen man.2011.02.013. 541 Bi ch, G.F., 2018. A e iew o chemical-based sedimen quali y assessmen me hodologies o he ma ine en i onmen . Ma . Pollu . 542 Bull. 133, 218-232. h ps://doi.o g/10.1016/j.ma polbul.2018.05.039 543 B own, R.M., McClelland, N. I., Deininge , R.A., Toze , R.G., 1970. A Wa e Quali y Index: Do We Da e? Wa e and Sewage Wo ks, 544 117(10), 339-343. 545 Camino Ma ín-To e, M., Ci ian, E., Ruiz, E., Galán, B., Vigu i, J.R., 2017. Es ua ine sedimen esuspension and acidi ica ion: 546 Release beha iou o con aminan s unde di e en oxida ion le els and acid sou ces. J. En i on. Manage. 199, 211-221. 547 h p://dx.doi.o g/10.1016/j.en man.2017.05.044 548
Chae , G.M., My old, D.D., Bo omley, P.J., 2009. A soil quali y index based on he equilib ium be ween soil o ganic ma e and 549 biochemical p ope ies o undis u bed coni e ous o es soils o he Paci ic No hwes . Soil. Biol. Biochem. 41, 822-830. 550 h ps://doi.o g/10.1016/j.soilbio.2009.02.005. 551 Chu, Z., Gu, W., Li, Y., 2019. Adso p ion Mechanism o Hea y Me als in Hea y Me al/Pes icide Coexis ing Sedimen Sys ems 552 h ough Fac o ial Design Assis ed by 2D-QSAR Models. Pol. J. En i on. S ud. 27(6), 2451-2461. 553 h ps://doi.o g/10.15244/pjoes/80962 554 Cude, C. G., 2001. O egon Wa e Quali y Index: A Tool o E alua ing Wa e Quali y Managemen E ec i eness. J. Am. Wa e 555 Resou . Assoc. 37(1), 125-137. h ps://doi.o g/10.1111/j.1752-1688.2001. b05480.x. 556 De esa-Rey, R., Díaz-Fie os, F., Ba al, M.T., 20120. T ace me als in i e bed sedimen s: an assessmen o hei pa i ioning and 557 bioa ailabli y by using mul i a ia e explo a o y analysis. J. En i on. Manag. 91, 2471-2477. 558 h p://dx.doi.o g/10.1016/j.jen man.2010.06.024 559 Fino i, A.R., Finkle , R., Susin, N., Schneide , V.E., 2015. Use o wa e quali y index as a ool o u ban wa e esou ces managemen . 560 In . J. Sus. De . Plann. 10(6), 781-794. h ps://doi.o g/10.2495/SDP-V10-N6-781-794 561 Ga cía-Ga cía, J., Ruiz-Rome a, E., Ma ínez-San os, M-, An igüedad. I., 2019. Tempo al a iabili y o me allic p ope ies du ing 562 lood e en s in he Deba Ri e u ban ca chmen (Basque Coun y, No he n Spain) a e he in oduc ion o sewage ea men 563 sys ems. En i on. Ea h Sci. 78, 1-23, h ps://doi.o g/10.1007/s12665-018-8014-1 564 Gi au, M., Chen, J., Ma, Z., 2016. Wa e Quali y Indices as Tools o Decision Making and Managemen . Wa e Resou . Manag. 565 30(8), 2591-2610. h ps://doi.o g/10.1007/s11269-016-1311-0 566 Guo, H., Yao, J., Cai, M., Qian, Y., Guo, Y., Richnow, H.H., e al., 2012. E ec s o pe oleum con amina ion on soil mic obial 567 numbe s, me abolic ac i i y and u ease ac i i y. Chemosphe e 87, 1273-1280. h ps://doi.o g/10.1016/j. 568 He e o, A., Vila, J., Elja a , E., Gineb eda, A., Saba e , S., Ba alla, R.J., Ba celó, D., 2018. T anspo o sedimen bo ne con aminan s 569 in a Medi e anean i e du ing a high low e en . Sci. To al En i on. 633, 1392-1402. 570 h ps://doi.o g/10.1016/j.sci o en .2018.03.205 571 Hoope , R.P., 2003. Diagnos ic ools o mixing models o s eam wa e chemis y. Wa e Resou . Res. 39, 1055. 572 h ps://doi.o g/10.1029/2002WR001528, 3. 573 House, M.A., 1989. A wa e quali y index o i e managemen . Wa e En i on. J. 3(4), 336-344. h ps://doi.o g/10.1111/j.1747-574 6593.1989. b01538.x 575 Jones, C.M., S es, B., Rosenquis , M., Hallin, S., 2008. Phylogene ic analysis o ni i e, ni ic oxide, and ni ous oxide espi a o y 576 enzymes e eal a complex e olu iona y his o y o deni i ica ion. Mol. Biol. E ol. 25, 1955-1966. 577 h ps://doi.o g/10.1093/molbe /msn146 578 Kabi , M.I., Lee, H., Kim, G., Jun, T., 2011. Co ela ion assessmen and moni o ing o he po en ial pollu an s in he su ace sedimen s 579 o Pyeongchang Ri e , Ko ea. In . J. Sedimen Res. 26 (2), 152–162. h ps://doi.o g/10.1016/S1001-6279(11)60083-8 580 Kausik, A., Kansal, A., San osh, Meena, Kuma i, S., Kaushik, C.P., 2009. Hea y me al con amina ion o i e Yamuna, Ha yana, 581 India: Assessmen by Me al En ichmen Fac o o he Sedimen s. J. Haza d. Ma e , 164(1), 265-270. 582 h ps://doi.o g/10.1016/j.jhazma .2008.08.031 583 Li, S., Zhang, C., Li, Y., 2014. Adso p ion o mul i-hea y me als Zn and Cu on o su icial sedimen s: modelling and adso p ion 584 capaci y analysis. En i on. Sci. Pollu . Res. In . 21(1), 399-406. h ps://doi.o g/10.1007/s11356-013-1916-2. 585 Ligi, T., T uua, M., T uua, J., Nõl aka, H., Kaasikb, A., Mi sch, W.J., Mande , U., 2014. E ec s o soil chemical cha ac e is ics and 586 wa e egime on deni i ica ion genes (ni S, ni K, and nosZ) abundances in a c ea ed i e ine we land complex. Ecol. Eng. 72, 587 47-55. h ps://doi.o g/10.1016/j.ecoleng.2013.07.015 588 Lundy, L., Al es, L., Re i , M., Wildeboe , D., 2017. Me al Wa e -Sedimen In e ac ions and Impac s on an U ban Ecosys em. In . 589 J. En i on. Res. Public Heal h 14(7):722. h ps:/doi.o g/10.3390/ije ph14070722 590 Ma ínez-San os, M., Lanzén, A., Unda-Cal o, J., Ma ín, I., Ga bisu, C., Ruiz-Rome a, E., 2018. T ea ed and un ea ed was ewa e 591 e luen s al e i e sedimen bac e ial communi ies in ol ed in ni ogen and sulphu cycling. Sci. To al En i on. 633, 1051-592 1061. h ps://doi.o g/10.1016/j.sci o en .2018.03.229 593 Ma ínez-San os, M., P obs , A., Ga cía-Ga cía, J., Ruiz-Rome a, E., 2015. In luence o an h opogenic inpu s and a high-magni ude 594 lood e en on me al con amina ion pa e n in su ace bo om sedimen s om he Deba Ri e u ban ca chmen . Sci. To al 595 En i on. 514, 10-25. h ps://doi.o g/10.1016/j.sci o en .2015.01.078. 596 Mul aney, R.L., 1996. Ni ogen-Ino ganic Fo ms. In: Spa ks, D.L., Page, A.L., Helmke, P.A., e al. (Eds.), Me hods o Soil Analysis: 597 Pa 3. Chemical Me hods, Soil Science Socie y o Ame ica Book Se ies no Vol. 5. Soil Science Socie y o Ame ica, Inc., 598 Madison, WI, pp. 1123-1184. 599 Now ouzi, M., Pou khabbaz, 2014. Applica ion o geoaccumula ion index and en ichmen ac o o assessing me al con amina ion 600 in he sedimen s o Ha a Biosphe e Rese e, I an. Chem. Spec. Bioa ailab. 26(2), 99-105. 601 h ps://doi.o g/10.3184/095422914X13951584546986 602 Pe anich, E., Co elli, S., Acqua i a, A., Vi o , C.D., Faganeli, J., Con in, M., 2018. Ben hic nu ien cycling a he sedimen -wa e 603 in e ace in a lagoon ish a ming sys em (no he n Ad ia ic Sea, I aly). Sci. To al En i on. 644, 137-149. 604 h p://dx.doi.o g/10.1016/j.sci o en .2018.06.310 605 P impas, I., Tsi sis, G., Ka ydis, M., Kokko is, G.D., 2010. P incipal componen analysis: De elopmen o a mul i a ia e index o 606 assessing eu ophica ion acco ding o he Eu opean wa e amewo k di ec i e. Ecol. Indic. 10(2), 178-183. 607 h ps://doi.o g/10.1016/j.ecolind.2009.04.007 608 REFCOND, Wo king G oup 2.3 om Common Implemen a ion S a egy o he Wa e F amewo k Di ec i e (2000/60/EC). Guidance 609 Documen No 10. Ri e s and Lakes – Typology, Re e ence Condi ions and Classi ica ion Sys ems. A ailable online a : 610 h p://ec.eu opa.eu/en i onmen /wa e /wa e - amewo k/ 611 Richa dson, D.J., 2000. Bac e ial espi a ion: a lexible p ocess o a changing en i onmen . Mic obiology 146:551–571. h ps://doi. 612 o g/10.1099/00221287-146-3-551. 613 Rügne , H., Schwien ek, M., Egne , M., G a hwohl, P., 2014. Moni o ing o e en -based mobiliza ion o hyd ophobic pollu an s in 614 i e s: Calib a ion o u bidi y as a p oxy o pa icle acili a ed anspo in ield and labo a o y. Sci. To al En i on. 490, 191-615 198. h ps://doi.o g/10.1016/j.sci o en .2014.04.110 616 Selle, B., Schwien ek, M., Lischeid, G., 2013. Unde s anding p ocesses go e ning wa e quali y in ca chmen s using p incipal 617 componen sco es. J. Hyd ol. 486, 31-38. h ps://doi.o g/10.1016/j.jhyd ol.2013.01.030 618 Şene , Ş., Şene , E., Da az, A., 2017. E alua ion o wa e quali y using wa e quali y index (WQI) me hod and GIS in Aksu Ri e 619 (SW-Tu key). Sci. To al En i on. 584-585, 131-144. h p://doi.o g/10.1016/j.sci o en .2017.01.102 620 SRDD, 1976. De elopmen o a wa e quali y index. Sco ish esea ch de elopmen depa men , applied esea ch & de elopmen 621 epo numbe ARD3 (p. 61). Edinbu g, UK: Enginee ing Di ision. 622 Su adian, A.D., Mu il, N., Yilmaz, A.G., Pe e a, B.J.C., 2016. De elopmen o i e wa e quali y indices-a e iew. En i on. Moni . 623 Assess. 188:58. h ps://doi.o g/10.1007/s10661-015-5050-0. 624
Thou eno , M., Billen, G., Ga nie , J., 2007. Modelling nu ien exchange a he sedimen -wa e in e ace o i e sys ems. J. Hyd ol. 625 341(1-2), 55-78. h ps://doi.o g/10.1016/j.jhyd ol.2007.05.001 626 Toka li, 2017. Bioecological and s a is ical isk assessmen o oxic me als in sedimen s o a wo ldwide impo an we land: Gala Lake 627 Na ional Pa k (Tu key). A ch. En i on. P o . 43(1), 34-47. h ps://doi.o g/10.1515/aep-2017-0007 628 Unda-Cal o, J., Ma ínez-San os, M., Ruiz-Rome a, E., 2017. Chemical and physiological me al bioaccessibili y assessmen in su ace 629 bo om sedimen s om he Deba Ri e u ban ca chmen : Ha moniza ion o PBET, TCLP and BCR sequen ial ex ac ion 630 me hods. Eco ox. En i on. Sa e. 138, 260-270. h p://dx.doi.o g/10.1016/j.ecoen .2016.12.029 631 Unda-Cal o, J., Ma ínez-San os, M., Ruiz-Rome a, E., Lechuga-C espo, J.L., 2019a. Implica ions o deni i ica ion in he ecological 632 s a us o an u ban i e using enzyma ic ac i i ies in sedimen s as an indica o . J. En i on. Sci. 75, 255-268. 633 h ps://doi.o g/10.1016/j.jes.2018.03.037 634 Unda-Cal o, J., Ruiz-Rome a, E., Fdez-O iz de Vallejuelo, S., Ma ínez-San os, M., G edilla, A., 2019b. E alua ing he ole o 635 pa icle size on u ban en i onmen al geochemis y o me als in su ace sedimen s. Sci. To al En i on. 646, 121-133. 636 h ps://doi.o g/10.1016/j.sci o en .2018.07.172 637 URA (Agencia Vasca del Agua – U Agen zia), 2008. Es ablecimien o de obje i os de calidad ela i os a indicado es isicoquímicos 638 gene als en los íos de la CAPV según la di ec i e 2000/60/CE. A ailable online a : h p://www.u agen zia.euskadi.eus 639 URA (Agencia Vasca del Agua – U Agen zia), 2013. Red de Seguimien o del Es ado Biológico de los Ríos de la Comunidad 640 Au ónoma del País Vasco. In o me de esul ados. Campaña 2013. A ailable online a : h p://www.u agen zia.euskadi.eus 641 URA (Agencia Vasca del Agua – U Agen zia), 2018. Red de seguimien o del Es ado Biológico de los Ríos de la Comunidad 642 Au ónoma del País Vasco. In o me de esul ados. Campaña 2017. A ailable a : h p://www.u agen zia.euskadi.eus 643 USEPA, 2001: Me hods o collec ion, s o age and manipula ion o sedimen s o chemical and oxicological analyses: echnical 644 manual. EPA-823-B-01-002. Washing on, DC. A ailable online a : h p://nepis.epa.go 645 Ve aa , A.J., Dimi o , M.R., Sch ie -Ujil, A.P., Smid , H., de Klein, M., 2017. Abundance, ac i i y and communi y s uc u e o 646 deni i ie s in d ainage di ches in ela ion o sedimen cha ac e is ics, ege a ion and land-use. Ecosys ems 20(5), 928-943. 647 h ps://doi.o g/10.1007/s10021-016-0083-y. 648 Violan e, A., Cozzolino, V., Pe elomo , L., Capo ale, A.G., Pigna, M., 2010. Mobili y and bioa ailabili y o hea y me als and 649 me alloids in soil en i onmen s. J. Soil. Sci. Plan Nu . 10(3), 268-292. h p://dx.doi.o g/10.4067/S0718-95162010000100005 650 Wang, J., Liu, G., Liu, H., Lam, P.K.S., 2017. Mul i a ia e s a is ical e alua ion o dissol ed ace elemen s and a wa e quali y 651 assessmen in he middle eaches o Huaihe Ri e , Anhui, China. Sci. To al En i on. 583, 421-431. 652 h p://doi.o g/10.1016/j.sci o en .2017.01.088 653 WFD, 2000/60/EC. Di ec i e 2000/60/EC o he Eu opean Pa liamen and o he Council o 23 Oc obe 2000 Es ablishing a 654 F amewo k o Communi y Ac ion in he Field o Wa e Policy. Eu opean Pa liamen , Council o he Eu opean Union. A ailable 655 a : h p://da a.eu opa.eu/eli/di /2000/60/oj 656 Yang, X., Xiong, B., Yang, M., 2010. Rela ionships among Hea y Me als and O ganic Ma e in Sedimen Co es om Lake Nanhu, 657 an U ban Lake in Wuhan, China. J. F eshw. Ecol. 25(2), 243-249. h ps://doi.o g/10.1080/02705060.2010.9665074 658 Yisa, J. and Jimoh, T., 2010. Analy ical S udies on Wa e Quali y Index o Ri e Landzu. Am. J. Appl. Sci. 7(4), 453-458. 659 h ps:/doi.o g/ 10.3844/ajassp.2010.453.458 660 Zheng, Na., Wang, Q., Liang, Z., Zheng, D., 2011. Cha ac e iza ion o hea y me al concen a ions in he sedimen s o h ee eshwa e 661 i e s in Huludao Ci y, No heas China. En i on. Poll. 154(1), 135-142. h ps://doi.o g/10.1016/j.en pol.2008.01.001 662 Zhu, L., Li, X., Zhang, C., Duan, Z., 2017. Pollu an s’ Release, Redis ibu ion and Remedia ion o Black Smelly Ri e Sedimen 663 Based on Re-Suspension and Deep Ae a ion o Sedimen . In . J. En i on. Res. Public Heal h 14(4), 374. 664 h ps://doi.o g/10.3390/ije ph14040374 665 Zum ,W.G., 1997. Cell biology and molecula basis o deni i ica ion. Mic obiol. Mol. Biol. Re . 61, 533–616. 666
FIGURE CAPTIONS 667
Fig. 1 Loca ion o sampling si es, main u ban a eas, Al zola gauging s a ion, un ea ed 668
u ban was ewa e (UWW) discha ge, and was ewa e ea men plan s (WWTPs) in he 669
Deba Ri e ca chmen . Table summa izes he sampling ype and he mos impo an 670
in o ma ion o he sampling si es: loca ion in he ca chmen and he impac o di e en 671
con amina ion sou ces in each si e (acco ding o he esul s ob ained in he spa ial 672
dis ibu ion o quali y index (QI) in he Fig. 4). The heigh p o ile o he ca chmen , and 673
he wa e discha ge (Q) and p ecipi a ion (P) e olu ion du ing he esea ch pe iod a e also 674
included. 675
Fig. 2 Flow diag am summa izing all he s eps o he classi ica ion o he con ibu ion 676
o an en i onmen al a iable o wa e o su ace sedimen quali y. 677
Fig. 3 Rela ionship be ween wo biological a iables ela ed o deni i ying communi y 678
abundance (nosZ:ni ) and ac i i y (Response Time) o he e e ence condi ions 679
es ablishmen . 680
Fig. 4 Spa ial dis ibu ion o wa e and su ace sedimen QI along he ca chmen (A), and 681
linea ela ionship be ween hem (B) when physicochemical a iables (I) o speci ic 682
pollu an s (II) we e aken in o accoun . Fo wa e , each box in (A) shows he 25 h, 50 h 683
and 75 h pe cen iles o alues calcula ed o he esea ch pe iod Jan’15 - Jan16’. The 25 h 684
pe cen ile o alues calcula ed o he d y (ci cles) and we ( iangles) seasons a e also 685
plo ed in (A) and used o linea ela ionships in (B). 686
Fig. 5 Linea ela ionships be ween QI ela ed o physicochemical a iables and speci ic 687
pollu an s in wa e samples du ing he d y and we seasons (A), and in su ace sedimen s 688
(B). Fo wa e , he 25 h pe cen ile alues om Fig. 4B we e used. Sampling si es wi hin 689
he g ey a ea a e cha ac e ized by wo se physicochemical a iables-dependen QI han 690
speci ic pollu an s-dependen QI. 691
II
I
D1 D2 D3 D4 D5 E1 E2 D7
D1
D2
D3 D4
D5
D7
E1
E2
D1
D2
D3
D4
D5
D7
E1
E2
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
Wa e QI
Sedimen QI
D y Season: R
2
= 0.56
We Season: R2= 0.45
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
D1 M1 D2 O1 D3 D4 D5 E1 E2 D6 D7
QI
Wa e Sedimen
AB
D1
D2 D3
D4
D5 D7
E1
E2
D1
D2 D3
D4 D5
D7
E1
E2
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
Wa e QI
Sedimen QI
D y Season ( ): R2= 0.73
We Season ( ): R2= 0.52
D1 D2 D3 D4 D5 E1 E2 D7
Wa e Sedimen
B
D y Season ( ): R2= 0.56
We Season ( ): R2= 0.45
A
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
D1 M1 D2 O1 D3 D4 D5 E1 E2 D6 D7
QI
D1
D2
D3 D4
D5
D6
D7
E1
E2
M1 O1
D1
D2
D3
D4
D5
D6
D7
E1
E2
M1
O1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
Speci ic Pollu an s QI
Physicochemical a iables QI
A)
D1
D2
D3
D4
D5
E1
E2
D7
R² = 0.32
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
Speci ic Pollu an s QI
Physicochemical a iables QI
B)
R2= 0.78
R2= 0.57
D y Season ( ):
We Season ( ):
1
2
3
4
5
6
1
2
3
4
5
6
Posi i e
Nega i e
0 ≤ 10%
10 ≤ 20%
0 ≤ 10%
10 ≤ 20%
20 ≤ 30%
20 ≤ 30%
30 ≤ 40%
30 ≤ 40%
40 ≤ 50%
40 ≤ 50%
> 50%
> 50%
C
Ni
Pb
Zn
Cu
C
Ni
Pb
Zn
Cu
2 1 2 2
5 1 1 6
2 1 4
1 2 1 3 2
6 6 4 2
4 6 6 5
1 1 1 1 1
1 1 1
1 1 1 1 1 1 1 1
D1 D2 D3 D4
D5 E1 E2 D7
Posi i e Con ibu ion
Nega i e Con ibu ion
1111 1 111
11
1
1
1
1
1
2
22 2
2
4
4
66
1
1
11
1 1 1
2
2
4
3
5
5
66
6
3 2 1
1 5 1 1 5
5 1 5 1
3 3 2 3
3 6 1 6 3
4 5 2
4 1 1 3 4
1 3 3
4 1 1 1 1 1 1 1
Posi i e Con ibu ion
Nega i e Con ibu ion
D1 D2 D3 D4 D5 E1 E2 D7
1
1 1 1
2
2
3
333
3
45
5 5
1
1
11 1 11 1 1
1 1
1
1
2
3
3
3
3
4 4
66
55
4TON
TON
TOC
TOC
TIC
TIC
NO3-
NO3-
NH4+
NH4+
SEDIMENT
1 1 1
1 2 3 1 1 1 1 1
3 2 5 6
3 3 1 2 3 2 4
3 2 1 2 1
2 2 2 2 2 2
2 2 2 1 2
4 3 4 2 2 3
2 2 1 2 1
1 1 2 3 2 2
2 2 1 2 1
1 1 1 3 2 1
Posi i e Con ibu ion
Nega i e Con ibu ion
1
3
3
2
2
2
2
2
2
2 2
2
2
2
2
2
2
2
2
1
1
1 1
1
1
1
1
1
1
1
44 3
3
3
2
2 2
2
2
1
1
1
1
D1 M1 D2 D3 O1 D4 D5 E1 E2 D6 D7
EC
EC
DOC
DOC
NO3-
PO43-
NO2-
NO2-
NH4+
NH4+
NO3-
PO43-
WATER
1
6 3 3 2 4
1 1 2 2 2 2
1 3 1 1 1 3
1 1 3 2 2
1 2 2 2 3
3 4 3 3 2 2
2 2 2 2 1
1 2 1 2 3 2
1 2 3 3 3 2 1
2 5 3 3
D1 M1 D2 D3 O1 D4 D5 E1 E2 D6 D7
Nega i e Con ibu ion Posi i e Con ibu ion
1
11
2
2
22
22
2
2
33
3
33
3
4
5
1
1
11
1
2
22
22
2
3
3
3
6
C
Ni
Pb
Zn
Cu
C
Ni
Pb
Zn
Cu
I
II
1 1
2
2
1
2
2
5
3
3
12
4
4
3
4
1
3
4
3
3
2
1
1
1
1
3
4
2
2
3
3
3
2
64
4
1
3
3
55
I
II
Table 1. Pa ame e s o he calcula ion o quali y index (QI): mean (M
j), s anda d de ia ion (σj),
e e ence condi ions (Ve y Bad Quali y (VBQ) and Ve y Good Quali y (VGQ)) and loading
ac o s (lpc) om he PCA o he en i onmen al a iables measu ed in wa e and su ace sedimen
samples om he Deba Ri e ca chmen . Co ela ion ac o s, eigen alues and explained a iance
o each P incipal Componen (PC) we e also included.
M
j ± σj Re e ence
Condi ions Loading ac o s (lpc.j)
Co ela ion ac o s
VBQ VGQ PC1 PC2 PC1 PC2
WATER
Physicochemical Va iables
EC 2.62 ± 0.219 2.66 2.43 0.068 -0.924 0.127 -0.965
DOC 0.584 ± 0.160 0.819 0.213 0.360 0.136 0.673 0.142
PO43- 1.378 ± 0.622 2.53 0.918 0.489 0.133 0.913 0.139
NO3- 2.77 ± 0.408 3.27 2.17 0.422 -0.246 0.789 -0.256
NO2- 0.904 ± 0.554 2.35 0.279 0.483 -0.087 0.902 -0.091
NH4+ 1.66 ± 0.555 3.03 0.805 0.463 0.205 0.865 0.214
Eigen alues
3.49 1.09
Explained a iance
58% 18%
Speci ic Pollu an s
Cu 0.319 ± 0.263 0.462 -0.602 0.420 -0.277 0.641 -0.285
Zn 0.837 ± 0.595 2.37 -0.602 0.582 -0.011 0.889 -0.012
Pb -0.437 ± 0.232 -0.129 -0.602 -0.186 -0.878 -0.284 -0.903
Ni 0.197 ± 0.469 0.35 -0.602 0.487 0.221 0.744 0.228
C -0.373 ± 0.414 0.79 -0.602 0.462 -0.321 0.706 -0.329
Eigen alues
2.34 1.06
Explained a iance
47% 21%
SEDIMENT
Physicochemical Va iables
TOC 1.28 ± 0.111 1.22 1.28 0.192 -0.657 0.303 -0.951
TIC 1.18 ± 0.313 1.61 0.702 0.480 0.340 0.757 0.493
NO3- 0.933 ± 0.250 1.41 0.789 0.535 0.254 0.844 0.369
NH4+ 0.897 ± 0.369 1.56 0.512 0.617 -0.023 0.973 -0.033
TON 0.239 ± 0.233 0.143 0.214 0.256 -0.623 0.403 -0.903
Eigen alues
2.49 2.10
Explained a iance
50% 42%
Speci ic Pollu an s
∑HQCu
0.260 ± 0.250 0.0010 0.0040 -0.467 -0.379 -0.591 -0.554
∑HQZn
0.422 ± 0.463 1.04 -0.498 -0.660 0.069 -0.834 0.101
∑HQPb
0.761 ± 0.137 0.869 0.668 -0.580 0.315 -0.733 0.460
∑HQNi 1.05 ± 0.206 1.10 1.25 0.100 0.580 0.126 0.847
∑HQC
1.381 ± 0.354 1.95 1.71 -0.010 0.645 -0.013 0.942
Eigen alues
1.60 2.13
Explained a iance
32% 43%
Table 2 Cons an e m (K) and weigh s (wj) a ibu ed o selec ed en i onemn al a iables (j) o
wa e and su ace sedimen QI equa ions cons uc ion (Eq. 7). S anda dized weigh s we e also
calcula ed: wj’=wjx(σj/σQI).
WATER SEDIMENT
Physicochemical a iables
wj w'j wj w'j
K 1.733 [-] K 1.535 [-]
EC -0.061 -0.054 TOC 0.219 0.075
DOC -0.296 -0.191 TIC -0.389 -0.374
PO43- -0.104 -0.261 NO3- -0.497 -0.382
NO3- -0.141 -0.233 NH4+ -0.309 -0.350
NO2- -0.117 -0.262 TON 0.041 0.028
NH4+ -0.109 -0.244
Speci ic Pollu an s
wj w'j wj w'j
K 0.537 [-] K 2.031 [-]
Cu -0.249 -0.350 ∑HQCu -0.468 -0.297
Zn -0.114 -0.363 ∑HQZn -0.446 -0.524
Pb -0.140 -0.174 ∑HQPb -1.449 -0.505
Ni -0.091 -0.228 ∑HQNi -0.044 -0.023
C -0.176 -0.390 ∑HQC -0.133 -0.119
A: Euclidean dis ance be ween he o hogonal p ojec ion o he sampling si e on he “Ve y Good-Bad Quali y”axis and he
VGQ poin .
B: Euclidean dis ance be ween he VBQ and VGQ poin s. “Ve y Good-Bad Quali y”axis.
C: Euclidean dis ance be ween he sampling si e and he VGQ poin .
D: Euclidean dis ance be ween he sampling si e and he VBQ poin .
D1
D1
D1
D2
D2
D2
D2
D2
D2 D2
D2
D2
D3
D3
D3
D3
D3
D3
D3
D3
D3
D4
D4
D4
D4
D4
D4
D4
D4
D4
D5
D5
D5
D6
D6
D6
D6
D6
D6D6
D6
D6
D7
D7
D7
E2
E2
E2
E2
E2
E2
E2
E2
E2
E1
E1
E1
E1
E1
E1
E1
E1
E1
M1
M1
M1
M1 M1
M1
M1
M1
M1
O1
O1
O1
O1 O1
O1
O1
O1
O1
VGQ
VBQ
-3.0
-2.0
-1.0
0.0
1.0
2.0
3.0
-4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0
PC2 (18%)
PC1 (58%)
D y
We
EC
DOC
PO43-
NO3-
NO2-
NH4+
PC2 (18%)
PC1 (58%)
1
1
D1 D2
D3 D4
D5
E1
E2
[Cuw/Cuss]= 1.51[DOC/TOC] - 0.08
R² = 0.61
0.00
0.20
0.40
0.60
0.80
0.00 0.10 0.20 0.30 0.40 0.50
Cuw/Cuss
DOC/TOC
D1
D2
D3
D4
D5
E1
E2 D7
[Znw/Znss] = 0.69 [DOC/TOC] - 0.01
R² = 0.61
0.00
0.10
0.20
0.30
0.40
0.50
0.00 0.10 0.20 0.30 0.40 0.50
Znw/Znss
DOC/TOC
D1 D2
D3
D4
E1
E2
D7
[C w/C ss] = 0.34 [DOC/TOC] + 0.009
R² = 0.54
0.00
0.10
0.20
0.30
0.40
0.50
0.00 0.10 0.20 0.30 0.40 0.50
C w/C ss
DOC/TOC
D1
D2
D3
D4
D5
E2
D7
R² = 0.70
0
5
10
15
20
25
30
35
40
45
0 1 2 3 4
TIC (mg g-1)
Alkalini y (mg CaCO3g-1)
UWW
WWTP
Table S1. Median alues o en i onmen al a iables measu ed in wa e samples o all sampling si es du ing he d y (Q < 12 m3 s-1) and we (Q > 12 m3 s-1)
seasons, and wa e quali y e e ence condi ions (VGQ o VBQ). Fo he d y season, maximum alues a e shown in bold and di e en uppe case le e s wi hin
he same pa ame e indica e ha medians a e signi ican ly di e en a ρ = 0.05 among sampling si es. Once all da a we e log- ans o med in o de o educe he
skewness and he Le ene’s es con i med which pa ame e s had equali y o a iance (*) o no (**), one-way ANOVA ( aking ρ < 0.05 as signi ican , in
acco dance wi h Tukey’s mul iple ange es ) and he U-Mann Whi ney non-pa ame ic es we e pe o med, espec i ely, o analyse he di e ences.
EC**
DOC** PO
4
3
-
* NO
3
-
* NO
2
-
* NH
4
+
* Cu** Zn* Pb** Ni** C **
Season
Si e µS·cm
-
1
mg·L
-
1
µg P·L
-
1
µg N·L
-
1
µg N·L
-
1
µg N·L
-
1
µg·L
-
1
µg·L
-
1
µg·L
-
1
µg·L
-
1
µg·L
-
1
D y
D1
746
abcd
2.85
ab
1.27
a
233
ab
1.57
a
10.4
ab
0.250
ab
4.11
abc
0.250
a
0.475
abcd
0.250
abc
(N = 5)
M1
956
bc
3.47
ab
4.90
a
243
b
2.38
a
11.0
b
0.920
b
1.67
bc
0.650
a
0.760
ac
0.250
b
D2
1030
c
4.26
ab
10.3
ab
328
abc
6.22
ab
36.4
abc
1.11
bc
4.90
abc
0.730
a
1.64
ab
0.250
b
D3
652
bc
4.73
ab
103
c
1918
e
12.2
bc
47.5
acd
1.48
ac
5.89
bd
0.580
a
3.25
bd
0.250
b
O1
267
d
2.20
b
5.48
a
301
abd
2.86
a
11.6
b
1.26
abc
5.70
abc
0.660
a
0.690
c
0.250
b
D4
393
ab
4.07
ab
38.9
bcd
1585
ae
12.3
bc
62.0
ce
1.41
ac
9.78
bd
0.250
a
2.30
abd
0.250
bc
D5
511
abcd
4.22
ab
110
bcd
2116
cde
26.6
bcd
93.6
ce
1.65
abc
12.1
bde
0.250
a
7.28
abcd
2.45
abc
E1
422
a
2.13
ab
10.5
ad
229
b
3.59
ab
20.0
ab
0.550
b
0.650
c
0.780
a
0.250
c
0.250
b
E2
420
a
5.92
a
182
c
1606
de
99.5
d
664
1.81
ac
78.8
e
0.610
a
1.55
ab
3.06
a
D6
370
a
4.19
ab
56.6
bcd
1238
ae
21.4
cd
140
de
1.86
a
18.4
ade
0.250
a
6.33
d
0.900
c
D
7
441
abcd
5.55
ab
119
bcd
2177
cde
27.3
bcd
96.9
cd
1.71
abc
22.5
abe
0.250
a
6.95
abcd
0.955
abc
We
D1
190
3.07
2.64
226
1.82
12.8
0.250
1.80
0.250
0.820
0.250
(N = 4)
M1
407
3.92
9.72
468
3.48
27.3
1.59
3.60
0.250
2.53
0.250
D2
396
4.93
24.9
453
4.75
38.6
2.18
7.51
0.250
2.17
0.250
D3
359
4.89
53.4
456
9.37
78.7
2.12
4.86
0.250
2.61
0.250
O1
184
3.65
13.4
292
2.77
27.6
2.13
6.59
0.250
1.06
0.250
D4
276
3.35
25.8
533
6.30
46.2
1.61
6.18
0.250
1.70
0.250
D5
279
4.71
34.3
1027
8.95
31.2
1.63
24.3
0.250
3.60
0.250
E1
301
4.72
19.3
265
2.65
20.2
1.53
3.57
0.250
0.585
0.250
E2
312
3.97
45.1
634
13.8
140
2.65
8.60
0.250
1.35
1.29
D6
271
3.96
39.1
545
8.20
46.4
2.02
9.68
0.250
2.34
0.520
D
7
365
4.50
97.7
1043
27.5
120
1.63
24.3
0.250
3.60
0.250
VGQ
268
1.63
8.27
149
1.90
6.38
0.250
0.250
0.250
0.250
0.250
VBQ
454
6.58
342
1853
223
1079
2.9
232
0.743
2.24
6.22
Table S2. En i onmen al a iables de e mined in he su ace sedimen s a each sampling si e in Oc obe 2015. (*) Sedimen quali y e e ence condi ions: E1
(VGQ) and E2 (VBQ).
TOC TIC NO3- NH4+ TON
∑HQ (x103)
Response
Time
nosZ:ni
(x107)
Cu Zn Pb Ni C
Si e
mg·g-1
mg·g-1
µg N·g-1
µg N·g-1
mg·g-1
[-] [-] [-] [-] [-]
min [-]
D1 27.5 5.75 6.02 8.96 3.19
0.985 1.18 4.12 8.76 12.9
23.0 5.62
D2 18.4 14.4 5.97 4.26 1.89
4.19 2.37 6.37 6.58 10.9
24.2 3.10
D3 26.4 29.0 14.6 20.1 3.97
2.26 4.72 3.58 9.67 11.0
47.0 2.05
D4 15.9 17.3 8.39 7.31 1.28
2.16 4.91 8.09 27.9 46.5
30.0 2.54
D5 18.5 20.1 4.41 6.42 1.49
1.65 3.36 8.25 8.14 14.3
16.5 2.01
E1* 18.9 5.04 6.15 3.25 1.64
1.01 0.317 4.65 17.9 51.8
19.9 6.61
E2* 16.5 40.4 25.8 36.1 1.39
1.00 10.9 7.40 12.6 89.5
74.7 2.29
D7 12.8 14.8 9.38 3.57 0.787
3.60 3.16 5.65 9.08 23.4
33.3 2.85
