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Water Cycle 4 (2023) 207–215
Available online 27 October 2023
2666-4453/© 2023 The Authors. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co. Ltd. This is an open access article under the CC
BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Using UV–Vis differential absorbance spectra of tropical peat water DOM
fraction to determine trihalomethanes formation potential and its
estimated cytotoxicity
Muammar Qada
a
,
*
, Diana Rahayuning Wulan
a
, Raden Tina Rosmalina
a
, Retno Wulandari
b
,
Wisnu Prayogo
c
, Rosetyati Retno Utami
d
, Yusuf Eka Maulana
e
, Suprihanto Notodarmojo
f
,
Yuniati Zevi
f
a
Research Center for Environmental and Clean Technology, National Research and Innovation Agency, Jalan Sangkuriang, Bandung, 40135, Indonesia
b
Chemical Engineering Department, Faculty of Engineering, Universitas Bhayangkara Jakarta Raya, Jl. Harsono RM No. 67, Jakarta, Indonesia
c
Department of Building Engineering Education, Universitas Negeri Medan, Medan, 20221, Indonesia
d
Research Center for Limnology and Water Resources, National Research and Innovation Agency, Jalan Raya Jakarta-Bogor KM. 46, Cibinong, Bogor, 16911, Indonesia
e
Organic Chemistry Division, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesha No. 10, Bandung, 40132, Indonesia
f
Water and Wastewater Engineering Research Group, Faculty of Civil and Environmental Engineering, Institut Teknologi Bandung, Jalan. Ganesha 10, Bandung, 40132,
Indonesia
ARTICLE INFO
Keywords:
Differential absorbance spectra
Tropical peat water
Dissolved organic matter
Trihalomethanes
Cytotoxicity
ABSTRACT
Absorbance differential spectra could be utilized to identify dissolved organic matter (DOM) characteristics such
as the disinfection by products (DBPs) formation. This research purposed to establish the relationship between
absorbance differential spectra and trihalomethanes-4 (THM4) formation potential, as well as the estimated
cytotoxicity of tropical peat water DOM percentage. The ion exchange resin was used to separate the DOM
components from peat water. In addition, the UV–Vis spectrum was examined between 200 and 700 nm. The
hydrophobic-acid (HPOA) fraction contains the highest concentration of dissolved organic carbon (DOC), THM4
production potential, and calculated cytotoxicity. On the other hand, the hydrophilic-neutral (HPIN) fraction has
the lowest potential THM4 production. The UV–Vis absorbance spectra of all DOM fractions showed a compa-
rable peak at 277 nm. The differential spectra of 277 nm (ΔA
277
) indicated a signicant association with DOC
concentration (99.6 %), trichloromethane (TCM) creation (86.6 %), total-THM4 (TTHM4) (81.3 %) formation,
THM4 estimated cytotoxicity (89.7 %), and a moderate correlation with bromodichloromethane (BDCM) for-
mation (55.6 %). Meanwhile, ΔA
277
had a poor correlation with brominated THM4 formation potential
(chlorodibromomethane (CDBM): 2.59, tribromomethane (TBM): 2.78 %). The absorbance differential spectra
might be employed as a surrogate measure for the peat water DOM fraction and its precursor properties to form
THM4 during the chlorination process, as well as its estimated cytotoxicity.
1. Introduction
Wetland has covered about 5 % of earth and become a major land-
scape in several regions such as in Southeast Asia countries [1]. Wetland
that is covered by organic matter is considered as peatland [2]. The
decomposition that occurs on the organic matter is derived from the
vegetation, which produces the organic soils that cover the surface
[1–3]. Since the peatland has thin organic soil, it has become important
terrestrial carbon store and vital element for global carbon
soil-atmosphere exchange [4]. The existence of the peatland spreads
around the world from Asia, Africa, Europe, and America [5]. Most of
the peatlands are lied in the South East Asia region as tropical peatland
(56.2 %) [1]. Indonesia has a big portion of tropical peatland especially
in Sumatra and Kalimantan Islands [2].
The peatland is not only having big carbon storage, but also has a
massive water catchment area [6–8]. The runoff from this area can affect
the water quality with high organic matter content, dissolved from peat
soils [8]. The decomposition process of peat soils does not only enrich
the peat water with humic and fulvic acid that has strong hydropho-
bicity, but also other hydrophobicity fractions such as transphilic and
* Corresponding author.
E-mail address: muam003@brin.go.id (M. Qada).
Contents lists available at ScienceDirect
Water Cycle
journal homepage: www.keaipublishing.com/en/journals/water-cycle/
https://doi.org/10.1016/j.watcyc.2023.10.003
Received 20 July 2023; Received in revised form 2 October 2023; Accepted 25 October 2023
Water Cycle 4 (2023) 207–215
208
hydrophilic dissolved organic matter [9–11]. Since the tropical peat
water has been used as an important water source in the tropical peat-
land [2,12], the presence of the DOM fractions may be another challenge
in treating tropical peat water.
The characteristic of natural organic matter (NOM) dissolved in
tropical peat water has important rules on the formation of THM4
especially trihalomethanes [9,13,14]. The presence of humic and fulvic
acid, a hydrophobic-acid (HPOA) DOM has been observed as a major
precursor of THM4 formation [15]. This large molecular weight dis-
solved organic matter has a strong hydrophobic acid character with a
massive aromatic carbon chain [16,17]. The HPOA DOM fraction is not
the only fraction that can contribute to the formation of THM4 in peat
water [9]. In fact, the presence of other fractions such as transphilic
(TPH), hydrophilic-charged (HPIC), and hydrophilic-neutral (HPIN) has
a big contribution to THM4 formation in certain characteristics and
conditions [9]. The precursor characteristic is not only determined by
high aromaticity content, but also by other factors such as, molecular
weight, compound content, halogen content, and water matrix [15].
Most of the DBPs are formed from the chlorination processes, i.e.:
cytotoxic, carcinogenic, mutagenic, neurotoxic, genotoxic, and terato-
genic. Since higher concentration of THM4 is formed during the chlorine
disinfection process, the presence of THM4 should be aware. Previous
research had reported the cytotoxicity of a single compound of DBPs
including THM4 [18]. The presence of THM4 in water could trigger
several health effects including bladder and cancer [19].
UV–Vis differential absorbance spectra has been widely used to
determine the DOM properties in water [20–23], including
metal-binding properties [21,24], molecular weight [25], treatment
efciency [26], and DBPs formation [27]. The conventional UV
254
absorbance method has been used as effective surrogate parameter for
predicting the presence of NOM and DBPs. On the other hand, the use of
UV–Vis spectral parameters such as spectral slopes, spectral ratio, and
differential spectra gains more attention of researcher to determine
more specic characteristic of DOM in water. Hopefully, the use of
UV–Vis differential absorbance could be determined the THM4 forma-
tion potential and estimated cytotoxicity of peat water DOM fraction.
This research was conducted to make a preliminary observation on
the calculated cytotoxicity from formed THM4 on the DOM hydropho-
bicity fraction of peat water. The result of this research could be used as
a guide for choosing suitable treatment method for tropical peat water,
that could reduce the toxic effect of formed THM4 from the nal
disinfection process.
2. Materials and methods
2.1. Samples and chemicals
Samples were collected from the Indragiri Hilir Regency’s peatland
in Riau Province, Indonesia. Sigma Aldrich (USA) provided all frac-
tionation resins (Superlite DAX-8, Amberlite XAD-4, and Amberlite IR-
958). THM4 standard compounds (Trihalomethanes Calibration Mix-
Sigma Aldrich) including chloroform/TCM, bromodichloromethane/
BDCM, chlorodibromomethane/CDBM, and bromoform/TBM in meth-
anol. Merck (Germany) that supplied the fractionation chemicals (hy-
drochloric acid, sodium hydroxide, sodium chloride, sodium sulte, and
methanol), the THM4 extraction reagents (methyl tert-butyl ether and
sodium sulfate), sodium sulte and the phosphate buffer. Pudak Scien-
tic (local) provided the chlorine solution (sodium hypochlorite 25 %).
Every solution was diluted in Milli-Q grade water.
2.2. DOM fractionation and chlorination
The fractionation of peat waters dissolved organic matter (DOM) was
carried out in accordance with our prior research [9,10]. To remove
suspended particles from peat water, a 0.45 m membrane was used.
Samples were adjusted to pH 2 before put into a Superlite DAX-8 resin,
which absorbed the HPOA fraction. The unabsorbed fraction was put
into an Amberlite XAD-4 resin, which absorbed the TPH component. The
absorbed HPOA and TPH fractions were eluted with sodium hydroxide.
The unabsorbed fraction that passed the XAD-4 was put into an anion
exchange Amberlite IRA-958 resin that absorbed HPIC fraction. Then, it
was eluted with a sodium hydroxide/sodium chloride combination. The
XAD-4 efuent that was not retained by any of the resins was the HPIN
fraction. Sodium hypochlorite solution with 1 % chlorine content was
added to 100 mL of all peat waters DOM fractions and stored for 24 h at
pH 7. Each operation was repeated three times to ensure data accuracy.
2.3. Analytical methods
THM4 was analyzed based on EPA 551.1 [28] procedures by using
Gas Chromatography (GC) Agilent 7890A that was coupled with Agilent
5975C Mass Selective Detector (MSD) and Agilent 7693 Series Auto-
matic Liquid Sampler. Then, we used Agilent MSD ChemStation soft-
ware to analyze the data. The DOC was analyzed with a TOC analyzer
(Shimadzu TOC VCSH) utilizing APHA 5310 technique B [29]. Whereas,
the UV–Vis Spectrophotometer (Shimadzu UV-1700) was used to
determine the UV–Vis absorbance of peat water DOM fractions. Esti-
mated cytotoxicity was calculated based on THM4 formation data by
dividing the molar concentration of each reported THM4 (M
THM4
) with
the supplied cytotoxicity (LC
50
) values (M
LC50.
) exposed to Chinese
hamster ovarium (CHO) cell [18] (Eq. (1)).
Estimated cytotoxicity =MTHM4
MLC50
(1)
3. Results and discussions
3.1. Peat water characteristics
Table 1 shows the raw peat water and its DOM fractions character-
istics. The DOC content in tropical peat water is very high due to the
high concentration of humic acid, as depicted by its high color content
and acidic pH. The UV
254
absorbance of peat water is also high due to
high DOC concentration. The SUVA value of raw peat water is higher
than 4 indicates that the peat water has high hydrophobic DOM [30].
The acidic pH of natural peat water indicates that the DOM is discovered
in the form of humic acid [9].
The HPOA fraction has the highest percentage of DOC concentration
(63.29 %) followed by TPH (16.57 %), HPIN (11.21 %), and HPIC (6.97
%) fractions. The DOM content in the peat water is also indicated by the
UV
254
absorbance that is dominated by the HPOA fraction. The SUVA
values of HPOA and TPH fractions are higher than 4, indicate strong
hydrophobicity domination. On the other hand, since the HPIC and
HPIN are hydrophilic fractions, the SUVA values are lower than 2. Even
the TPH exhibits a slightly higher E
2
/E
3
ratio (absorbance ratio of A
250
/
Table 1
Peat water DOM fractions characteristics.
Raw DOM Fractions
HPOA TPH HPIN HPIC
pH 5.20 N.A. N.A. N.A. N.A.
Color
(PtCo)
3050 N.A. N.A. N.A. N.A.
DOC (mg/
L)
52.06 ±
3.73
32.95 ±
3.51
8.63 ±
1.52
5.84 ±
0.80
3.63 ±
0.65
UV
254
(cm
−1
)
3.95 ±
0.00
2.40 ±
0.01
0.46 ±
0.005
0.07 ±
0.0005
0.06 ±
0.0005
SUVA (L/
mg⋅m)
7.58 ±
0.59
7.28 ±
0.82
5.28 ±
0.95
1.14 ±
0.94
1.55 ±
0.35
E
2
/E
3
5.02 ±
0.01
5.25 ±
0.00
5.21 ±
0.00
2.95 ±
0.00
3.09 ±
0.00
E
4
/E
6
8.06 ±
0.01
1.18 ±
0.00
1.22 ±
0.00
1.30 ±
0.00
0.61 ±
0.00
M. Qada et al.
Water Cycle 4 (2023) 207–215
209
A
365
) compared to the HPOA percentage, indicating a smaller molecular
weight and a higher degree of aromaticity [31,32]. The E
2
/E
3
ratio
shows that DOM is independent of chromophoric DOM (C-DOM),
decreasing with increasing molecular weight [33]. The HPOA fraction
also has higher E
4
/E
6
value (absorbance ratio of A
465
/A
665
) compared to
other fractions. Beyond aromaticity, the E
4
/E
6
ratio correlates with
molecule size, overall acidity, and carbonyl content [34].
3.2. UV–Vis differential absorbance spectra
Fig. 1 shows the UV–Vis differential absorbance, and differential
spectra at 277 nm, of peat waters’ DOM fractions. All UV–Vis differential
spectra of DOM fraction show similar differential absorbance trend that
increase from wavelength of 200 nm–277 nm peak then rapidly
decreased reaching the visible light wavelength (Fig. 1a). This differ-
ential absorbance trend shows that wavelength of 277 nm (UV
277
) as the
highest absorbance peak among all DOM peat waters’ fractions. The
HPOA fraction has the highest UV
277
differential absorbance due to its
content of humic acid. Then, it is followed by HPIC, with nearly similar
absorbance values, TPH, and HPIN fractions.
The differential spectra of UV
277
(ΔA
277
) can be calculated based on
the absorbance trend (Fig. 1b). Conversely with ΔA
277
absorbance, the
HPOA fraction has the lowest ΔA
277
that is followed by TPH, HPIC, and
HPIN fractions. Meanwhile, the DOC concentration shows opposite
pattern (Table 1). HPOA fraction as the highest concentration is fol-
lowed with TPH, HPIC and HPIN fractions. This may be happened due to
the HPOA fraction that is contained of humic and fulvic acid as major
DOM that can be found in natural water. The ΔA
277
is close to ΔA
272
which had been proposed by previous study [35] that associated with
the continuous reaction of activated aromatics and highly correlated
with THM4 formation.
The UV absorbance of natural water between 250 and 280 nm is
commonly used to predict the concentration of aromatic structures,
identied as chlorine-reactive site of NOM [35]. The majority of re-
searches have demonstrated a linear relationship between DBP con-
centrations and absorbance at a single wavelength of 272 nm, with very
high determination coefcients (R
2
) of typically greater than 0.90. This
suggests that a signicant quantity of precursors, characterized by
absorbance at this wavelength, will undergo a reaction to generate an
intermediate product, that eventually releasing the observed DBP [35].
The selection of this wavelength is based on the empirical observation of
the highest differential absorbance at this specic wavelength [36].
These ndings demonstrate some shared properties of water differ-
ential spectra. The differential spectra have been used to determine
several DOM properties such as DBPs formation [22,27,36,37], metal
binding [24,38], ion binding into extracellular polymeric substances
[39], chlorite formation and chlorine consumption [23], molecular
weight [25,39,40], evolution of charges of peat fulvic and humic acid
[41] and NOM removal on coagulation process [42] as shown in Table 2.
To the best of our knowledge, all previous studies on UV–Vis differential
absorbance spectra were not conducted on correlation between differ-
ential absorbance spectra of DOM fractions with THM4 formation in
association with its estimated cytotoxicity, especially for high humic
content water such as peat water.
Differential absorption refers to a change in UV–Vis absorption at
specic wavelength or within specic wavelength range under different
conditions [43]. The formation of THM group was successfully identi-
ed from river water at ΔA
272
[35,36]. The formation of DBPs from
various river water samples were identied at ΔA
272
with correlations of
90–95 %, ion binding from Suwanee River humic acid (SRHA) samples
at various differential wavelength with correlations >80 % [44], and
chlorite formation from SRHA and Suwanee River fulvic acid (SRFA)
samples at ΔA
316-400
with correlations >90 % [23], and DOM at ΔlnA
400
with a correlation of 99 % [42]. There was a direct correlation between
the concentration of substances in water and the magnitude of ΔUV-Vis
[45,46]. Higher concentrations generally result in larger absorption
changes, especially in the UV range. The composition of substances,
including specic functional groups (e.g., aromatic rings, phenolic
groups, carboxylic acids), can also affect the differences in ΔUV-Vis
absorption [23,47]. Different components can contribute to specic
UV–Vis features, allowing the identication of chemical characteristics.
3.3. THM4 formation potential of peat water DOM fractions
Fig. 2 shows THM4 formation and its estimated cytotoxicity of peat
water DOM fraction after 24 h chlorination in pH 7. In the formation of
Fig. 1. Differential UV–Vis absorbance (a), and ΔA
277
value (b) of tropical peat water DOM fractions.
M. Qada et al.
Water Cycle 4 (2023) 207–215
210
chlorinated THM4, TCM dominated almost every fraction of peat water
DOM, except HPIC, as can be seen in Fig. 2a. Our result is in line with
previous researches [48–50], which stated that TCM is the most formed
THM in the chlorination process. The highest TCM formation is in the
HPOA, followed by the TPH fraction. The low TCM formation only takes
place in the HPIC fraction, which is dominated by brominated THM4.
The hydrophobic (HPOA and TPH) has a higher TCM formation poten-
tial than the hydrophilic fraction due to higher aromatic compounds that
precursor to TCM [51].
The BDCM has the second-highest formation potential. It is higher in
TPH, followed by HPOA fraction. Since hydrophilic fraction has higher
precursor properties than brominated DBPs [52], the HPIC fraction also
has high DBCM formation. Brominated THM4 dominates the formation
of THM4 in HPIC fraction, although it is not as high as chlorinated
THM4. CDBM has the highest formation in HPIC, followed by TBM as the
smallest formed THM4 in each fraction. According previous studies [48,
53], TBM’s presence was inuenced by bromide ions in water. The
formation of brominated DBPs could rule the THM4 formation since the
water contained high hydrophilic fractions [52].
HPOA fraction is highly contributed to the formation of total THM4
(t-THM4FP) with 51.9 % of formation followed by TPH fraction at 31 %
(Fig. 2b). Consequently, the patterns of TCM and TTHM4 formation are
nearly similar. TCM is the major THM4 that formed during the chlori-
nation of water containing high levels of humic substances [50,54,55].
The HPIC fraction has the smallest TTHM4 formation at 5.7 %. The
humic and fulvic acids in HPOA fraction are the major precursor to
THM4 formation [15]. Similarly, TPH fraction contains β-dicarbonyl
acids, were important in the THM4 formation [15]. TPH fraction is
dened as a DOM fraction that has intermediate polarity between hy-
drophobic and hydrophilic DOM and has low aromatic and phenolic
carbon compared to HPOA fraction [56]. Also, TPH fraction is dened as
low hydrophobic fraction [57], so still has high estimated cytotoxicity.
Previous studies reported that the hydrophilic fractions had tryptophan
as a signicant precursor to THM4 [58,59].
3.4. Estimated cytotoxicity
The calculated cytotoxicity of THM4 shows similar pattern with
THM4 formation. Although brominated THM4 has the highest cyto-
toxicity value compared to chlorinated THM4 [18], the high formation
of TCM still dominates the THM4 estimated cytotoxicity (Fig. 2c). The
formation of BDCM is the second source of THM4 estimated toxicity in
all peat water fractions. Since the HPOA fraction has the highest DOC
concentration in peat water, it dominates the estimated THM4 cyto-
toxicity followed by TPH, HPIC and HPIN fractions (Fig. 2d).
The toxicity of DBPs is determined by the organic matter’s precursor
characteristics and its concentration in water. DBPs are cytotoxic, gen-
otoxic, carcinogenic, neurotoxic, mutagenic, and teratogenic in the
majority of cases [60]. THM4 is one of the two DBPs regulated by the
USEPA. The formation of other regulated DBP, haloacetic acids-5
(HAA5) in peat water DOM fraction had been studied previously [9,
10]. However, the data on other DBPs that may more toxic than regu-
lated DBPs are still lacked. In addition, several DBPs are developmen-
tally toxic and have growth inhibition [61,62]. The estimated
cytotoxicity in this study was based solely on THM4 formations during
the chlorination of in peat waters DOM fractions. It should be noted that
the cytotoxicity calculated does not represent the complete amount of
toxicity of generated DBPs after chlorine disinfection. Furthermore, the
observed DBPs are not the only source of toxicity. More studies should
be done to investigate the generation of other DBPs and their toxicity in
the chlorination process of tropical peat water DOM fractions.
3.5. THMs formation mechanism
Fig. 3 shows the mechanism of DBPs formation of each DOM example
in the presence of bromide. Chlorine initiates the attack on organic
Table 2
Available research in correlation between DOM properties and UV–Vis differ-
ential absorbance.
Object Water source Δ
Wavelength
Correlation References
Individual DBPs Tolt River ΔA
272
95 % [22]
THM Lake Sartori ΔA
272
98 % [37]
THMs and HAAs Alibeykoy raw
and fractioned
water
ΔA
254
Low
correlation
[40]
Binding of copper
(II) by
Suwannee
River fulvic
acid (SRFA)
SRFA ΔA
208
,
ΔA
242
,
ΔA
276
,
ΔA
314
,
ΔA
378
, and
ΔA
551
99 % [44]
Ions binding onto
extracellular
polymeric
substances in
different mixed
microbial
cultures
AerAOB,
AnAOB,
activated
sludge
ΔA
300
98,
97, and 95
%
[39]
THM4 and HAN4 Membrane
bioreactor
treated water of
municipal
wastewater
(Ji’nan, China)
ΔLnA
350
99 % [27]
Metal ion binding Caffeic acid,
ferulic acid,
sinapic acid,
terephthalic
acid,
isophthalic
acid, esculetin
and myricetin
ΔA
240
,
ΔA
276
,
ΔA
316
, ΔA
385
correlated [38]
Metal-DOM
interaction
SRHA ΔS
350-400
ΔA
235
91–98 % [24]
Chlorite
formation and
ClO2
consumption
SRHA and
SRFA
ΔA
316
ΔA
400
91–99 %
92–99 %
[23]
DBP
concentrations
Du Nord River ΔA
272
62–99 % [36]
Carboxylic-like
groups and
total NOM-
bound Al (III)
ions
SRHA ΔS
260-270
and
ΔS
350-400
98 % [21]
DBP SRNOM ΔA
272
90 % [35]
Weight-averaged
molecular
weight
SRHA
SRFA
ΔA
200
99 %
97 %
[25]
evolution of
charges of peat
fulvic and
humic acid
Carboxylic and
phenolic range
ΔA
280
ΔA
350
98–99 % [41]
Dissolved organic
matter removal
by coagulation
Source water
for the Beijing
Mega-city
ΔlnA
400
99 % [42]
metal-NOM
complexes
Metal-esculetin
solution
ΔA
240
,
ΔA
276
,
ΔA
310
, and
ΔA
390
80 % [26]
DOC
concertation,
THM4
formation and
its estimated
cytotoxicity of
tropical peat
water DOM
fractions
Tropical peat
water
ΔA
277
81–99 % This study
SRFA: Suwannee River fulvic acid, AerAOB: aerobic ammonium-oxidizing bac-
teria, AnAOB: anaerobic ammonium-oxidizing bacteria, SRHA: Suwannee River
humic acid, SRNOM: Suwannee River NOM.
M. Qada et al.
Water Cycle 4 (2023) 207–215
211
matter through electrophilic substitution, leading to the formation of
chlorinated DBPS, such as THM4 [63]. The presence of bromide in water
can react with chlorine to form hypobromous acid. HPOA and TPH
fractions contain of high phenolic/aromatic carbon with high molecular
weight. A phenolic compound can form haloform such as THM during
chlorination process (Fig. 3a). Bromide in water can react with chlorine
to generate hypobromous acid and bromate, both of which exhibit
higher reactivity compared to chlorine [14]. HPOA fraction in peat
water is contained of humic and fulvic acid [9,64]. Humic acids are
macromolecular and complex, with core components that are
substituted aromatic and aliphatic hydrocarbons with high molecular
weight (2000–5000 Da) [15]. On the other hand, fulvic acid is identied
by lower molecular weight and aromaticity compared to humic acids
(500–2000 Da) [15].
TPH is a DOM fraction with intermediate polarity between hydro-
phobic and hydrophilic DOM and low aromatic and phenolic carbon
when compared to HPOA [56]. The carboxyl group (COOH) is an
example of an HPIC DOM fraction, as it can function as an acid by losing
a proton to produce a negatively charged carboxylate ion. Carbonyl
(C
–
–
O), an uncharged yet polar functional group (containing partial
positive and partial negative charges), serves as an example of an HPIN
fraction. Carboxyl groups are frequently found in amino acids, fatty
Fig. 2. THM4 formation and of tropical peat water DOM fractions its estimated cytotoxicity: (a) THM4, (b) TTHM4, (c) estimated cytotoxicity of THM4, and (d)
estimated cytotoxicity of TTHM4.
Fig. 3. The interaction between chlorine and DBP precursor: (a) phenolic, (b) carboxyl, and (c) carbonyl compounds.
M. Qada et al.
Water Cycle 4 (2023) 207–215
212
acids, and other macromolecules, while carbonyls can be found in a
wide range of biological components, including proteins, peptides, and
carbohydrates [15].
3.6. Correlation between DOC, THM4, and calculated cytotoxicity and
differential spectra
Fig. 4 shows the correlation between ΔA
277
and DOC concentration,
THM4 formation potential and its estimated cytotoxicity of peat waters
DOM fractions. ΔA
277
was highly correlated to DOC concentration of
each peat water DOM fraction (99.6 %) (Fig. 4a). Moreover, ΔA
277
also
shows high correlation with highly chlorinated-THM4 (TCM) (86.6 %)
(Fig. 4b) and moderate correlation to BDCM formation (55.6 %)
(Fig. 4c). However, the formation of high brominated-THM4 shows
remarkably weak correlation with ΔA
277
with 0.25 % and 0.27 % for
CDBM (Fig. 4d) and TBM (Fig. 4e). Since the formation of THM domi-
nates the THM4 formation of peat waters DOM fractions, the TTHM4
formation has moderate correlation with ΔA
277
(69.6 %) (Fig. 4f). A
Fig. 4. Relationship between ΔA
277
and: (a) DOC, (b) TCM, (c) BDCM, (d) CDBM, (e) TBM, (f) TTHM4, and (g) Calculated cytotoxicity of THM4 of tropical peat
water DOM fractions.
M. Qada et al.
Water Cycle 4 (2023) 207–215
213
study of Krasner et al. (2022) also reported that correlation of ΔA
277
-
TCM was higher than ΔA
277
BDCM. The BDCM, CBDM, and TBM for-
mation was inuenced by the presence of bromide in water [65].
Meanwhile, another previous study found that the high bromide con-
centration affected the ΔA-THM4 relationship [35].
Since the ΔA
277
values of HPIN and HPIC fractions were nearly
similar, a perplexing deviation in data was observed for ΔA
277
≈4
especially in relation to highly correlated parameters such as TCM
(Fig. 4b) and cytotoxicity (Fig. 4g) with ΔA
277
value. Although ΔA
277
is
moderately correlated to TTHM4, the calculated cytotoxicity of TTHM4
shows strong correlation to ΔA
277
with higher percentage (89.7 %)
(Fig. 4g). The primary DBP precursors in natural water are chromo-
phoric DOM with unsaturated moieties that typically have ultra-
violet–visible (UV–Vis) absorbance [27]. In addition, the presence of
chromophoric DOM tend to form TCM as dominant THM4 during
chlorination process [50]. Although the cytotoxicity of TCM is lower
than brominated THM4, the high formation of TCM dominates the
THM4 cytotoxicity that impacts the ΔA-estimated cytotoxicity
relationship.
Although the relationship between UV–Vis differential spectra and
several peat water DOM fraction characteristics such as DOC concen-
tration, THM4 formation, and THM4 estimated cytotoxicity has been
investigated in this study, more precise DOM fraction and raw peat
water specications should be considered for future research. There are
several parameters to consider, including the presence of distinct DOM
fractions such as hydrophobic base, hydrophilic acid, hydrophilic
neutral, and DOM fractions based on molecular weight. In addition,
specic experimental condition such as effect of pH, chlorine concen-
tration, chlorine contact time and presence of bromide in water are need
to be examined. Also, the formation of other regulated DBPs, HAA5,
nitrogenous DBPS such as haloacetonitriles, halonitromethanes, and
haloacetamide, and phenolic DBPs should be investigated with regard to
their association with UV–Vis differential spectra in order to discover
new applications for UV–Vis differential spectra.
3.7. Potential application UV–Vis differential spectra
In tropical regions, the peat water DOM characteristics especially the
presence of hydrophobic fractions such as humic acid depicted in its
color [66] are inuenced by several factors such as season and tides
[54]. The conventional water treatment using alum coagu-
lation−sedimentation process could not completely remove the pres-
ence of DOM in peat water [9]. The coagulation process is effective in
removing the hydrophobic DOM fraction but has limited impact on the
removal of hydrophilic fractions [67]. The remaining HPIC and HPIN
fractions dissolved in treated water could serve as sources of DBPs
precursor [10,15,68]. This study used the peat water DOM fraction
differential spectra to determine THM4 formation during chlorination
process. By knowing the differential spectra of raw peat water and
remaining DOM fraction in treated peat water, the THM4 formation
during nal chlorination process and its cytotoxicity could be predicted.
4. Conclusion
The UV–Vis differential absorbance spectra of peat water DOM
fractions are related to DOC concentration, THM4 formation, and THM4
estimated cytotoxicity. Ion exchange resin was used to separate the DOM
fraction into HPOA, TPH, HPIC, and HPIN fractions. The UV–Vis dif-
ferential spectra of peat water DOM fractions show a signicant peak at
277 nm (ΔA
277
). The ΔA
277
shows a strong relationship with DOC
concentration, TCM formation, total THM4 formation, and THM4 esti-
mated cytotoxicity, with percentages of 99.6 %, 86.6 %, 81.3 %, and
89.7 %, respectively. Furthermore, the BDCM formation exhibits a
moderate correlation with ΔA
277
(55.6 %). However, the production of
highly-brominated THM4 has no relation with ΔA
277
. Based on our
ndings, the ΔA
277
might be employed as a surrogate parameter for
DOM fractions DOC concentration in relation to THM4 and its cyto-
toxicity during peat water treatment process.
Declaration of competing interest
The authors declare that they have no known competing nancial
interests or personal relationships that could have appeared to inuence
the work reported in this paper.
Acknowledgment
This study was supported by the Indonesia Endowment Fund for
Education (Lembaga Pengelola Dana Pendidikan/LPDP), Ministry of
Finance Republic of Indonesia, under Grant No. 201705210110920.
References
[1] S.E. Page, J.O. Rieley, R. Wu, Lowland tropical peatlands of Southeast Asia, in:
Peatlands Evol. Rec. Environ. Clim. Chang., 2006, pp. 145–172, https://doi.org/
10.1016/S0928-2025(06)09007-9.
[2] M. Qada, D.R. Wulan, S. Notodarmojo, Y. Zevi, Characteristics and treatment
methods for peat water as clean water sources: a mini review, Water Cycle 4 (2023)
60–69, https://doi.org/10.1016/J.WATCYC.2023.02.005.
[3] M.E. Raghunandan, A.S. Sriraam, An overview of the basic engineering properties
of Malaysian peats, Geoderma Reg 11 (2017) 1–7, https://doi.org/10.1016/j.
geodrs.2017.08.003.
[4] L. Bendell-Young, Peatland interstitial water chemistry in relation to that of surface
pools along a peatland mineral gradient, Water, Air. Soil Pollut. 143 (2003)
363–375, https://doi.org/10.1023/A:1022865109409.
[5] M.S. Omar, E. Ifandi, R.S. Sukri, S. Kalaitzidis, K. Christanis, D.T.C. Lai, S. Bashir,
B. Tsikouras, Peatlands in Southeast Asia: a comprehensive geological review,
Earth Sci. Rev. 232 (2022), 104149, https://doi.org/10.1016/J.
EARSCIREV.2022.104149.
[6] E.P. Querner, W. Mioduszewski, A. Povilaitis, A. ´
Slesicka, Modelling peatland
hydrology:three cases from northern Europe, Pol. J. Environ. Stud. 19 (2010)
149–159.
[7] R.A. Bourbonniere, Review of water chemistry research in natural and disturbed
peatlands, Can. Water Resour. J. 34 (2009) 393–414, https://doi.org/10.4296/
cwrj3404393.
[8] J.P. Ritson, M. Bell, R.E. Brazier, E. Grand-Clement, N.J.D. Graham, C. Freeman,
D. Smith, M.R. Templeton, J.M. Clark, Managing Peatland Vegetation for Drinking
Water Treatment OPEN, Nat. Publ. Gr., 2016, https://doi.org/10.1038/srep36751.
[9] M. Qada, S. Notodarmojo, Y. Zevi, Performance of microbubble ozonation on
treated tropical peat water: effects on THM4 and HAA5 precursor formation based
on DOM hydrophobicity fractions, Chemosphere 279 (2021), 130642, https://doi.
org/10.1016/j.chemosphere.2021.130642.
[10] M. Qada, S. Notodarmojo, Y. Zevi, Haloacetic acids formation potential of tropical
peat water DOM fractions and its correlation with spectral parameters, water, air,
Soil Pollut 232 (2021) 319, https://doi.org/10.1007/S11270-021-05271-4.
[11] C. Abdi Mahmud, B. Mu’min, Removal natural organic matter (NOM) in peat water
from wetland area by coagulation-ultraltration hybrid process with pretreatment
two-stage coagulation, J. Wetl. Environ. Manag. 1 (2013) 42–49, https://doi.org/
10.20527/jwem.v1i1.88.
[12] N.A. Rahman, C.J. Jol, V. Ismail, Emerging application of electrocoagulation for
tropical peat water treatment: a review, Chem. Eng. Process. - Process Intensif. 165
(2021), 108449, https://doi.org/10.1016/j.cep.2021.108449.
[13] M. Qada, S. Notodarmojo, Y. Zevi, Effects of microbubble pre-ozonation time and
pH on trihalomethanes and haloacetic acids formation in pilot-scale tropical peat
water treatments for drinking water purposes, Sci. Total Environ. 747 (2020),
141540, https://doi.org/10.1016/j.scitotenv.2020.141540.
[14] M. Qada, R.T. Rosmalina, M.M. Pitoi, D.R. Wulan, Chlorination disinfection by-
products in Southeast Asia: a review on potential precursor, formation, toxicity
assessment, and removal technologies, Chemosphere 316 (2023), 137817, https://
doi.org/10.1016/J.CHEMOSPHERE.2023.137817.
[15] T. Bond, E.H. Goslan, S.A. Parsons, B. Jefferson, A critical review of trihalomethane
and haloacetic acid formation from natural organic matter surrogates, Environ.
Technol. Rev. 1 (2012) 93–113, https://doi.org/10.1080/09593330.2012.705895.
[16] A. Phetrak, J. Lohwacharin, H. Sakai, M. Murakami, K. Oguma, S. Takizawa,
Simultaneous removal of dissolved organic matter and bromide from drinking
water source by anion exchange resins for controlling disinfection by-products,
J. Environ. Sci. 26 (2014) 1294–1300, https://doi.org/10.1016/S1001-0742(13)
60602-6.
[17] H. Zhang, J. Qu, H. Liu, X. Zhao, Characterization of isolated fractions of dissolved
organic matter from sewage treatment plant and the related disinfection by-
products formation potential, J. Hazard Mater. 164 (2009) 1433–1438, https://
doi.org/10.1016/j.jhazmat.2008.09.057.
[18] E.D. Wagner, M.J. Plewa, CHO cell cytotoxicity and genotoxicity analyses of
disinfection by-products: an updated review, J. Environ. Sci. 58 (2017) 64–76,
https://doi.org/10.1016/J.JES.2017.04.021.
[19] N. Costet, C.M. Villanueva, J.J.K. Jaakkola, M. Kogevinas, K.P. Cantor, W.D. King,
C.F. Lynch, M.J. Nieuwenhuijsen, S. Cordier, Water disinfection by-products and
M. Qada et al.
Water Cycle 4 (2023) 207–215
214
bladder cancer: is there a European specicity? A pooled and meta-analysis of
European case–control studies, Occup. Environ. Med. 68 (2011) 379–385, https://
doi.org/10.1136/OEM.2010.062703.
[20] Y. Huang, S. Cheng, Y.P. Wu, J. Wu, Y. Li, Z.L. Huo, J.C. Wu, X.C. Xie, G.V. Korshin,
A.M. Li, W.T. Li, Developing surrogate indicators for predicting suppression of
halophenols formation potential and abatement of estrogenic activity during
ozonation of water and wastewater, Water Res. 161 (2019) 152–160, https://doi.
org/10.1016/j.watres.2019.05.092.
[21] M. Yan, T. Luo, N. Li, G.V. Korshin, Monitoring the kinetics of reactions between
natural organic matter and Al(III) ions using differential absorbance spectra,
Chemosphere 235 (2019) 220–226, https://doi.org/10.1016/J.
CHEMOSPHERE.2019.06.072.
[22] G.V. Korshin, W.W. Wu, M.M. Benjamin, O. Hemingway, Correlations between
differential absorbance and the formation of individual DBPs, Water Res. 36 (2002)
3273–3282, https://doi.org/10.1016/S0043-1354(02)00042-8.
[23] S. Huang, W. Gan, M. Yan, X. Zhang, Y. Zhong, X. Yang, Differential UV–vis
absorbance can characterize the reaction of organic matter with ClO2, Water Res.
139 (2018) 442–449, https://doi.org/10.1016/J.WATRES.2018.04.006.
[24] H. Xu, M. Yan, W. Li, H. Jiang, L. Guo, Dissolved organic matter binding with Pb(II)
as characterized by differential spectra and 2D UV–FTIR heterospectral correlation
analysis, Water Res. 144 (2018) 435–443, https://doi.org/10.1016/J.
WATRES.2018.07.062.
[25] H. Wu, Z. Chen, F. Sheng, J. Ling, X. Jin, C. Wang, C. Gu, Characterization for the
transformation of dissolved organic matters during ultraviolet disinfection by
differential absorbance spectroscopy, Chemosphere 243 (2020), 125374, https://
doi.org/10.1016/J.CHEMOSPHERE.2019.125374.
[26] C. Zhang, X. Han, G. V Korshin, A.M. Kuznetsov, M. Yan, Interpretation of the
differential UV-visible absorbance spectra of metal-NOM complexes based on the
quantum chemical simulations for the model compound esculetin, Chemosphere
276 (2021), 130043, https://doi.org/10.1016/j.chemosphere.2021.130043.
[27] D. Ma, C. Xia, B. Gao, Q. Yue, Y. Wang, C-, N-DBP formation and quantication by
differential spectra in MBR treated municipal wastewater exposed to chlorine and
chloramine, Chem. Eng. J. 291 (2016) 55–63, https://doi.org/10.1016/J.
CEJ.2016.01.091.
[28] USEPA, Method 551.1: determination of chlorination disinfection byproducts,
chlorinated solvents , and halogenated pesticides/herbicides in drinking water by
liquid-liquid extraction and gas chromatography with electron-capture detection,
Natl. Expo. Res. Lab. Off. Res. Dev. U.S. Environ. Prot. Agency. (1995) 1–61.
[29] R. Baird, L. Bridgewater, Standard Methods for the Examination of Water and
Wastewater, 23rd Edition, American Public Health Association, Washington, D.C,
2017.
[30] J.K. Edzwald, J.E. Tobiason, Enhanced coagulation: US requirements and a broader
view, Water Sci. Technol. 40 (1999) 63–70, https://doi.org/10.1016/S0273-1223
(99)00641-1.
[31] J. Peuravuori, K. Pihlaja, Molecular size distribution and spectroscopic properties
of aquatic humic substances, Anal. Chim. Acta 337 (1997) 133–149, https://doi.
org/10.1016/S0003-2670(96)00412-6.
[32] A. Vergnoux, R. Di Rocco, M. Domeizel, M. Guiliano, P. Doumenq, F. Th´
eraulaz,
Effects of forest res on water extractable organic matter and humic substances
from Mediterranean soils: UV–vis and uorescence spectroscopy approaches,
Geoderma 160 (2011) 434–443, https://doi.org/10.1016/j.
geoderma.2010.10.014.
[33] J.R. Helms, A. Stubbins, J.D. Ritchie, E.C. Minor, D.J. Kieber, K. Mopper,
Absorption spectral slopes and slope ratios as indicators of molecular weight,
source, and photobleaching of chromophoric dissolved organic matter, Limnol.
Oceanogr. 53 (2008) 955–969.
[34] Y. Chen, N. Senesi, M. Schnitzer, Information provided on Humic Substances by
E4/E6 Ratios, Soil Sci. Soc. Am. J., 1976, pp. 352–358, https://doi.org/10.2136/
sssaj1977.03615995004100020037x.
[35] N. Beauchamp, C. Dorea, C. Bouchard, M. Rodriguez, Multi-wavelength models
expand the validity of DBP-differential absorbance relationships in drinking water,
Water Res. 158 (2019) 61–71, https://doi.org/10.1016/J.WATRES.2019.04.025.
[36] N. Beauchamp, O. Laamme, S. Simard, C. Dorea, G. Pelletier, C. Bouchard,
M. Rodriguez, Relationships between DBP concentrations and differential UV
absorbance in full-scale conditions, Water Res. 131 (2018) 110–121, https://doi.
org/10.1016/J.WATRES.2017.12.031.
[37] P. Roccaro, F.G.A. Vagliasindi, Differential vs. absolute UV absorbance approaches
in studying NOM reactivity in DBPs formation: comparison and applicability,
Water Res. 43 (2009) 744–750, https://doi.org/10.1016/J.WATRES.2008.11.007.
[38] M. Yan, X. Han, C. Zhang, Investigating the features in differential absorbance
spectra of NOM associated with metal ion binding: a comparison of experimental
data and TD-DFT calculations for model compounds, Water Res. 124 (2017)
496–503, https://doi.org/10.1016/J.WATRES.2017.08.004.
[39] C. Yin, F. Meng, Y. Meng, G.H. Chen, Differential ultraviolet–visible absorbance
spectra for characterizing metal ions binding onto extracellular polymeric
substances in different mixed microbial cultures, Chemosphere 159 (2016)
267–274, https://doi.org/10.1016/J.CHEMOSPHERE.2016.05.089.
[40] N. Ates, M. Kitis, U. Yetis, Formation of chlorination by-products in waters with
low SUVA—correlations with SUVA and differential UV spectroscopy, Water Res.
41 (2007) 4139–4148, https://doi.org/10.1016/J.WATRES.2007.05.042.
[41] S. Liu, M.F. Benedetti, W. Han, G.V. Korshin, Comparison of the properties of
standard soil and aquatic fulvic and humic acids based on the data of differential
absorbance and uorescence spectroscopy, Chemosphere 261 (2020), 128189,
https://doi.org/10.1016/J.CHEMOSPHERE.2020.128189.
[42] Y. Zhou, Y. Xie, M. Wang, F. Zou, C. Zhang, Z. Guan, M. Yan, In-situ
characterization of dissolved organic matter removal by coagulation using
differential UV–Visible absorbance spectroscopy, Chemosphere 242 (2020),
125062, https://doi.org/10.1016/J.CHEMOSPHERE.2019.125062.
[43] C. Zhang, X. Han, G.V. Korshin, A.M. Kuznetsov, M. Yan, Interpretation of the
differential UV–visible absorbance spectra of metal-NOM complexes based on the
quantum chemical simulations for the model compound esculetin, Chemosphere
276 (2021), 130043, https://doi.org/10.1016/J.CHEMOSPHERE.2021.130043.
[44] M. Yan, D. Dryer, G.V. Korshin, M.F. Benedetti, In situ study of binding of copper
by fulvic acid: comparison of differential absorbance data and model predictions,
Water Res. 47 (2013) 588–596, https://doi.org/10.1016/J.WATRES.2012.10.020.
[45] H.T. Carter, E. Tipping, J.F. Koprivnjak, M.P. Miller, B. Cookson, J. Hamilton-
Taylor, Freshwater DOM quantity and quality from a two-component model of UV
absorbance, Water Res. 46 (2012) 4532–4542, https://doi.org/10.1016/J.
WATRES.2012.05.021.
[46] M.T. Aung, K.K. Shimabuku, N. Soares-Quinete, J.P. Kearns, Leveraging DOM UV
absorbance and uorescence to accurately predict and monitor short-chain PFAS
removal by xed-bed carbon adsorbers, Water Res. 213 (2022), 118146, https://
doi.org/10.1016/J.WATRES.2022.118146.
[47] Y. Huang, S. Cheng, Y.P. Wu, J. Wu, Y. Li, Z.L. Huo, J.C. Wu, X.C. Xie, G.V. Korshin,
A.M. Li, W.T. Li, Developing surrogate indicators for predicting suppression of
halophenols formation potential and abatement of estrogenic activity during
ozonation of water and wastewater, Water Res. 161 (2019) 152–160, https://doi.
org/10.1016/J.WATRES.2019.05.092.
[48] A.T. Chow, Disinfection byproduct reactivity of aquatic humic substances derived
from soils, Water Res. 40 (2006) 1426–1430, https://doi.org/10.1016/j.
watres.2006.01.008.
[49] B. Panyapinyopol, T.F. Marhaba, V. Kanokkantapong, P. Pavasant,
Characterization of precursors to trihalomethanes formation in Bangkok source
water, J. Hazard Mater. 120 (2005) 229–236, https://doi.org/10.1016/J.
JHAZMAT.2005.01.009.
[50] M.R. Sururi, S. Notodarmojo, D. Roosmini, Aquatic organic matter characteristics
and THMFP occurrence in a tropical river, Int. J. GEOMATE 17 (2019) 203–211,
https://doi.org/10.21660/2019.62.85393.
[51] X. Zhong, C. Cui, S. Yu, The determination and fate of disinfection by-products
from ozonation-chlorination of fulvic acid, Environ. Sci. Pollut. Res. 24 (2017)
6472–6480, https://doi.org/10.1007/s11356-016-8350-1.
[52] G. Hua, D.A. Reckhow, Effect of pre-ozonation on the formation and speciation of
DBPs, Water Res. 47 (2013) 4322–4330, https://doi.org/10.1016/j.
watres.2013.04.057.
[53] J. Awad, J. van Leeuwen, C. Chow, M. Drikas, R.J. Smernik, D.J. Chittleborough,
E. Bestland, Characterization of dissolved organic matter for prediction of
trihalomethane formation potential in surface and sub-surface waters, J. Hazard
Mater. 308 (2016) 430–439, https://doi.org/10.1016/j.jhazmat.2016.01.030.
[54] M. Qada, S. Notodarmojo, Y. Zevi, Y.E. Maulana, Trihalomethane and haloacetic
acid formation potential of tropical peat water: effect of tidal and seasonal
variations, Int. J. GEOMATE 18 (2020) 111–117, https://doi.org/10.21660/
2020.66.9487.
[55] N. Sharma, S. Mohapatra, L.P. Padhye, S. Mukherji, Role of precursors in the
formation of trihalomethanes during chlorination of drinking water and
wastewater efuents from a metropolitan region in western India, J. Water Process
Eng. 40 (2021), 101928, https://doi.org/10.1016/J.JWPE.2021.101928.
[56] J.P. Crou´
e, M.F. Benedetti, D. Violleau, J.A. Leenheer, Characterization and copper
binding of humic and nonhumic organic matter isolated from the South platte river
: evidence for the presence of nitrogenous binding site, Environ. Sci. Pollut. Res. 37
(2003) 328–336, https://doi.org/10.1021/es020676p.
[57] Y. Shi, J. Huang, G. Zeng, Y. Gu, Y. Hu, Evaluation of soluble microbial products
(SMP) on membrane fouling in membrane bioreactors (MBRs) at the fractional and
overall level : a review, Rev. Environ. Sci. Bio/Technology. 17 (2018) 71–85,
https://doi.org/10.1007/s11157-017-9455-9.
[58] M.R. Sururi, S. Notodarmojo, D. Roosmini, An investigation of a conventional
water treatment plant in reducing dissolved organic matter and trihalomethane
formation potential from a tropical river water source, J. Eng. Technol. Sci. 52
(2020) 271–288, https://doi.org/10.5614/j.eng.technol.sci.2020.52.2.10.
[59] M. Ma, M. Wang, X. Cao, Y. Li, J. Gu, Yield of trihalomethane, haloacetic acid and
chloral upon chlorinating algae after coagulation-ltration: is pre-oxidation
necessarily negative for disinfection by-product control? J. Hazard Mater. 364
(2019) 762–769, https://doi.org/10.1016/j.jhazmat.2018.09.056.
[60] S.D. Richardson, M.J. Plewa, E.D. Wagner, R. Schoeny, D.M. DeMarini,
Occurrence, genotoxicity, and carcinogenicity of regulated and emerging
disinfection by-products in drinking water: a review and roadmap for research,
Mutat. Res. Mutat. Res. 636 (2007) 178–242, https://doi.org/10.1016/J.
MRREV.2007.09.001.
[61] Y. Pan, X. Zhang, Four groups of new aromatic halogenated disinfection
byproducts: effect of bromide concentration on their formation and speciation in
chlorinated drinking water, Environ. Sci. Technol. 47 (2013) 1265–1273, https://
doi.org/10.1021/es303729n.
[62] J. Liu, X. Zhang, Comparative toxicity of new halophenolic DBPs in chlorinated
saline wastewater efuents against a marine alga: halophenolic DBPs are generally
more toxic than haloaliphatic ones, Water Res. 65 (2014) 64–72, https://doi.org/
10.1016/J.WATRES.2014.07.024.
[63] X. Zhong, C. Cui, S. Yu, Formation of aldehydes and carboxylic acids in humic acid
ozonation, Water. Air. Soil Pollut. 228 (2017) 1–11, https://doi.org/10.1007/
s11270-017-3418-1.
[64] S. Notodarmojo, Mahmud, A. Larasati, Adsorption of natural organic matter (NOM)
in peat water by local Indonesia tropical clay soils, Int. J. GEOMATE 13 (2017)
111–119, https://doi.org/10.21660/2017.38.30379.
M. Qada et al.
Water Cycle 4 (2023) 207–215
215
[65] S.W. Krasner, A. Jia, C.F.T. Lee, R. Shirkhani, J.M. Allen, S.D. Richardson, M.
J. Plewa, Relationships between regulated DBPs and emerging DBPs of health
concern in U.S. drinking water, J. Environ. Sci. 117 (2022) 161–172, https://doi.
org/10.1016/J.JES.2022.04.016.
[66] Y. Zevi, M. Qada, S. Notodarmojo, The presence of trihalomethanes and
haloacetic acids in tropical peat water, J. Eng. Technol. Sci. 54 (2022), 220314,
https://doi.org/10.5614/J.ENG.TECHNOL.SCI.2022.54.3.14.
[67] S. Notodarmojo, M. Qada, Y. Zevi, Absorbance spectral slopes for monitoring
tropical peat water dissolved organic matter fractions during microbubble pre-
ozonation, CLEAN – Soil, Air, Water 51 (2023), 2300122, https://doi.org/
10.1002/CLEN.202300122.
[68] L. ¨
Onnby, E. Salhi, G. McKay, F.L. Rosario-Ortiz, U. von Gunten, Ozone and
chlorine reactions with dissolved organic matter - assessment of oxidant-reactive
moieties by optical measurements and the electron donating capacities, Water Res.
144 (2018) 64–75, https://doi.org/10.1016/j.watres.2018.06.059.
M. Qada et al.