Abstract:
To study sources and distribution of organic matter in Muangmai mangrove, Lamu estuary,
Chonburi province. Field sampling were performed in June and November 2014, August and
December 2016 in mangrove (12 stations) where receives treated wastewater, adjacent mudflat (11
station) and wastewater treatment plant (1 station). Values of stable isotope of carbon in mangrove
leaves, mangrove sediment, mangrove POM, mangrove crab (Sesarma haematocheir ) and treated
wastewater were -30.60±1.16‰, -24.21±0.79‰, -27.05‰, -25.66±2.32‰ and -27.91‰, respectively,
and 
15N values were 7.20±1.83‰, 4.40±2.24 ‰, 4.08‰, 8.68±1.34‰ and 10.8‰, respectively.
The values of stable isotope in treated wastewater, mangrove sediment and mangrove crab
were no significantly different (p>0.05), whereas the isotopic compositions between treated
wastewater, mudflat sediment and bivalves were significantly different (p<0.05). Results from this
study indicates that organic matter from Chonburi central wastewater treatment plant spread to
mangrove but did not accumulate in an adjacent mudflat area.