Trihalomethane and Haloacetic Acid Formation Potential of Tropical Peat Water: Effect of Tidal and Seasonal Variations

Abstract

The existence of humic substances in peat water impacts the presence of the dissolved organic matter (DOM) which is the precursor of trihalomethanes (THMs) and haloacetic acids (HAAs). However, information on DOM characteristics, THMs and HAAs Formation Potential (THMFP and HAAFP) in tropical peat water are still limited. This study aimed to determine the correlations between DOM, THMFP, and HAAFP during dry and rainy seasons in tropical peat water in Indonesia. Samples of peat water are taken from the water canal and tidally affected river on Sumatera's peatland during the rainy season and dry season to determine the effects of the seasons and tides. DOM measured by dissolved organic carbon (DOC), specific ultraviolet absorbance and the ratio of E465/E665 while THMFP determined from a total of THMFP4 measurements and HAAFP determined from measurement of total HAAFP5. Compared to dry season, values of all organic parameters on rainy season were higher but fewer in river. Canal water has a higher DOC while river water has a higher chloride and bromide content. Increasing of DOC in the rainy season correlates with increasing of THMFP4 and HAAFP5. THMFP4 is dominated by chloroform on canal while brominated THMs predominate in river water which correlates with the presence of bromide. Chlorinated HAAs dominate HAAFP5 in canal water while brominated HAAs increases in the river. Seasons and tides affect the appearance of bromide contaminants in water that affects the form of THMFP and HAAFP.

Characterization of Fluorescent Dissolved Organic Matter in an Affected Pollution Raw Water Source using an Excitation-Emission Matrix and PARAFAC

“…Therefore, the raw water characteristics combined with chlorination method in the final disinfection stage can potentially produce drinking water that contains harmful THMs. Nonetheless, studies investigating the quantity and characteristics of DOM compound in tropical raw water sources including Indonesian rivers are very limited (Qadafi et al, 2020). The presence of DOM in the raw water is commonly represented as the concentrations of chemical oxygen demand (COD) and biochemical oxygen demand (BOD) including in Indonesia.…”

The Presence of Trihalomethanes and Haloacetic Acids in Tropical Peat Water

“…All samples were taken and analyzed in triplicate for accuracy. All reagents and solutions used in this research were based on our previous studies [3,10].…”

“…The SUVA254 values ranged from 5.53 ± 0.09 to 5.85 ± 0.06 L/mg.m, indicating that the natural organic compounds in the peat water were mostly humic substances with high aromaticity and were strongly hydrophobic. The presence of humic substances with a large molecular structure derived from peat soils comes from the decomposition of dead plants and animals in the peatland [3,10,21,23,24].…”

“…The presence of brominated THM4 was higher in the dry season. This probably occurs due to fewer dilution in the water body [10,12,13].…”

“…The five HAAs (HAA5), i.e., monochloroacetic acid (MCAA), dichloroacetic acid (DCAA), trichloroacetic acid (TCAA) monobromo-acetic acid (MBAA), and dibromoacetic acid (DBAA), are classified as probable and possible human carcinogens (Group-C) [8]. The United States Environmental Protection Agency (USEPA) has set a maximum pollution level of 80 μg/L for total THM4 and 60 μg/L for total HAA5 [9,10].…”