Assessment of Water Quality and Ecological Functions of Urban Wetlands at the AIT Campus, Thailand

Abstract

Wetlands play a vital role in urban ecosystems by offering critical services such as water purification, nutrient cycling, biodiversity support, and carbon sequestration. This study aimed to characterize the physico-chemical and microbiological water quality of selected wetlands at the Asian Institute of Technology (AIT) campus in Thailand, from November 2016–March 2017. Seven wetlands were sampled using the Standard Method. Dissolved Oxygen (DO), pH, Turbidity, Electrical Conductivity (EC), Ammonia-Nitrogen (NH₃-N), Total Kjeldahl Nitrogen (TKN), Total Phosphorus (TP), Chemical Oxygen Demand (COD), Chlorophyll a, and Escherichia coli (E. coli) were analysed. Additional analyses included sediment and macrophyte carbon sequestration, algal diversity, and zooplankton (rotifer) density. The results revealed slightly alkaline pH (7.5-8.3) and moderate to high DO levels (3.4–8.5 mg/L). SV1 and Chiang Rak ponds exhibited elevated turbidity (12.9–16.7 NTU), nutrient enrichment (e.g., NH₃-N at 3.4 mg/L, TKN at 4.48 mg/L), and critical E. coli contamination (up to 7,420 MPN/100 mL). High chlorophyll a levels were recorded in SV2 (195 µg/L) and Chiang Rak (928 µg/L). Rotifer density varied across sites, with the highest in Fountain Pond (280 ± 43 individuals/L), corresponding with improved microbial quality. Carbon sequestration was substantial in macrophyte biomass (e.g., SV2: 9.4 ± 0.5 g C m² month¹) and sediments (e.g., WD Pond: 6.6 ± 0.7 g C m² month¹). The findings suggest that while the AIT wetlands offer considerable ecological services, certain sites risk pollution and require improved management to enhance their sustainability and ecosystem functions.