Physio-chemical properties and dynamic of the surface sediment in riparian mangroves along the Tien river, Tien Giang province

Abstract

This study was conducted to investigate the physio-chemical properties and vertical dynamic of the surface sediment (0–5 cm) in riparian mangroves along the Tien river, Tien Giang province. The distribution of riparian mangroves located from the polyhaline zone (transect S1 and S2) to the mesohaline zone (transect S3 and S4) and the oligohaline zone (transect S5). Three plots (10x10 m) per transect were set based on the elevation of the mangrove floor (cm + mean sea level) and dominant plants. A total of 28 sediment samples were collected in December 2016 and April 2017. Seasonal variation of pH, redox potential (Eh), electrical conductivity of saturated extract (ECse), bulk density, sediment organic matter (SOM) and total sulfur (TS) were measured in accordance with the standard protocols. Seasonal trends of vertical erosion and accumulation were tested by the tracer stick method. The ECse values and TS concentrations were higher in the dry season and in transects closed to the estuary (S1, S2 and S3) but these trends weren’t found for pH, Eh, and SOM. In most of the riparian mangroves along the Tiền river, low elevation (0–50 cm) was one of important factors affecting the Eh and ECse. In the rainy season, major changes in vertical erosion and acumulation have occurred in the transects near the mouth of the river.