Nitrogen Distribution and Its Influencing Factors in the Sediment

Sediment, as a seawater nutrient buffer, can continuously receive and release biogenic elements to balance the water chemically or physically. The nitrogen in sediments includes two kinds one is released into water to take part in the cycling, and the other is buried in sediments. In addition, the burial part can also release when environment changed sharply. So the burial part is a potential source of nitrogen for water. 

The areas with TN 0.1% match well with the mud patches. The coastal belt with elevated TN content extends southward from the Changjiang River 

Estuary. It is noteworthy that this belt veers offshore and extends toward the SOT as it approaches the northern end of the Taiwan Strait. 

The spatial distribution of IN, ON, and TN was similar in the Changjiang River Estuary sediments. But the change in IN was smaller than those of ON and TN. Fig. 4.29 (Li et al., 2006b) shows the distribution of IN, ON, and TN in sections A and B (Fig. 4.2). Their distribution can be divided into three regions (stations 1 4, 4 11 and 11 20) in section A according to their regular variation, while in section B the change in IN, ON, and TN was more stable. 

The mean grain size of seabed sediments, ranging from A j) to 7.5 / (Fig. 4.30, Gao et al., 2007), increases from land to sea in the ECS, and the isolines project towards the northeast and east outside of the Changjiang River Estuary and Hangzhou Bay, respectively. To the east of 123° E, mean grain size isohnes appear in circular ringed distribution, and the highest value occurs at 123.5° E and 30.5° N. 

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