Spatial distribution and controlling factors of sediment nitrogen forms in the mangrove wetland at Dongzhai Port, Hainan Province

Abstract

The occurence of nitrogen in sediments directly affects the process, pathway and contribution of nitrogen in the nature, therefore exploring the environmental geochemical behavior of different nitrogen speciation in sediments is of great significance for studying nitrogen geochemical cycle. In this study, the surface sediment and sediment core were collected in the mangrove wetland at Dongzhai Port, Hainan Province.The different forms of transferable nitrogen were analyzed via hierarchical extraction.The spatial distribution characteristics and influencing factors were investigated. The results showed that the contents of total nitrogen (TN) and total transferable nitrogen (TTN) in the sediments ranged from 1 149.2 to 1 690.6 mg/kg and from 464.6 to 647.5 mg/kg, respectively, both of which presented a decreasing trend from the upstream to the estuary. The strong oxidant extracted nitrogen (SOEF-N) is the major nitrogen species in TTN, and positively correlated with TTN contents. According to C/N ratio, the organic matter in the study area is mainly from the discharge of a large number of pollutants.The significant positive correlation between TN, water content and TOC in the mangrove columnar sediments in Dongzhai Port, indicates that nitrogen and organic matter have similar sources.

Keywords

• mangrove
• nitrogen form
• sediment
• spatial characteristics
• dongzhai port in hainan