As climate change is becoming a growing concern and the importance of water management is
increasing, the retention of carbon and nutrients in wetland soils including inland and coastal area has become
important. In this study, retention characteristics of organic matter and nutrients of coastal sediment and soils in
different types of wetlands such as constructed wetland, natural (inland marsh, estuary, tidal flat) wetlands were
investigated. A correlation analysis was also performed to understand the relationship among organic matter
properties, nutrient concentrations and soil texture of wetland soils. The degree of retention of organic matter and
nitrogen in wetland soils varied with the wetland type. Inland wetlands retain more nitrogen than estuary or coastal
wetlands, and natural wetlands retain more organic matter and nitrogen than constructed ones. Coastal sediments in a
bay area where seawater circulation is restricted have more nutrients than those in estuary or tidal flats where
seawater circulates well. The results showed that the sediment chemical oxygen demand has a high correlation with
the total organic carbon and the total nitrogen in the studied area.