Rainwater extracting characteristics and its potential impact on DBPs generation: A case study.

Area of Science:

• Environmental Chemistry
• Water Quality Management
• Climate Change Impacts

Background:

• Global warming intensifies extreme precipitation, increasing pollutant loads in water sources.
• Surface runoff and wet deposition introduce dissolved organic matter (DOM) into water bodies, threatening water supply security.
• Assessing DOM characteristics and disinfection by-products formation potential (DBPsFP) is vital for water treatment.

Purpose of the Study:

• To investigate the source characteristics and leaching mechanisms of DOM in rainwater.
• To evaluate the DBPsFP of different rainwater DOM fractions.
• To understand the influence of extraction parameters on DOM and related substances in soil.

Main Methods:

• Rainwater and soil samples were collected for extraction experiments.
• Parallel Factor (PARAFAC) analysis identified three DOM components in rainwater: humic-like (C1), protein-like (C2), and marine/terrestrial humic-like (C3).
• Hydrophobic Neutral (HON), Hydrophobic Bases (HOB), Hydrophobic Acidic (HOA), and Hydrophilic (HIS) fractions were analyzed for molecular weight and DBPsFP. Partial Least Squares Path Modeling (PLS-PM) was used for soil extracts.

Main Results:

• Rainwater DOM comprised microbial humic-like (63.1%), protein (28.9%), and humic-like (8.1%) components.
• Molecular weight order was HON < HOB < HOA < HIS.
• HOA and HON fractions were key precursors for trihalomethanes (THMs); HON and HIS fractions for haloacetic acids (HAAs) and trichloroacetonitrile (TCAN), respectively.
• Subsoil extracts showed higher dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) than topsoil.
• Extraction temperature dominated DOM abundance in topsoil, while extraction time influenced fluorescence and physicochemical indices in subsoil.

Conclusions:

• Rainwater DOM composition and molecular weight distribution influence its potential to form disinfection by-products.
• Extraction conditions significantly affect DOM characteristics in soil, impacting water source quality.
• Findings aid in managing global warming impacts on water sources vulnerable to contaminated rainfall.