Optimization of a Coastal Environmental Monitoring Network Based on the Kriging Method: A Case Study of Quanzhou Bay, China

Table 2

Seawater quality standards and categories in China.

Quality grade		I	II	III	IV
Seawater quality index	COD (mg/L)	0–2	2-3	3-4	4-5
	DIN (mg/L)	0–0.20	0.20–0.30	0.30–0.40	0.40–0.50
	PO4-P (mg/L)	0–0.15	0.015–0.030	0.015–0.030	0.030–0.045

Seawater quality standard from state oceanic administration [39].