Variations in total organic carbon and acid-volatile sulfide distribution in surface sediments from Luan River Estuary, China

The distribution of total organic carbon (TOC), acid-volatile sulfide (AVS) and sediment grain sizes was studied in surface sediments collected from the coastal water near Luan River Estuary during spring and summer 2015. The aim was to examine the relationships between TOC, AVS and sediment grain sizes. The paired samples t test result revealed that seasonal variation had significant effects on the spatial distribution of TOC and AVS in the surface sediments (p < 0.05). The scatter plots indicated that AVS concentration had significant positive correlations with TOC content in both spring and summer (spring: r = 0.475, p < 0.05; summer: r = 0.689, p < 0.01). The TOC content had a good correlation with sediment grain size, and for both seasons, TOC contents were relatively higher in fine-grained sediments. The relationship between AVS concentration and sediment grain size was not significant in the spring, but was significant in the summer. Cluster analysis further revealed that the spatial distribution of TOC and AVS in surface sediments was significantly affected by sediment grain size, and these distributions varied slightly between the seasons. According to AVS concentrations in surface sediments, the coastal water near Luan River Estuary during spring and summer 2015 was considered as “the healthy area.”