Spatiotemporal Variation Characteristics of Water Pollution and the Cause of Pollution Formation in a Heavily Polluted River in the Upper Hai River

Table 6

Results of the seasonal Mann–Kendall test and the seasonal Mann–Kendall test of flow-adjusted concentrations.

Monitoring site	Water quality parameters	SMK test			SMK test of flow-adjusted concentrations
		r	a (%)	Trend	R^2	a (%)	Trend
G5	CODCr	−4.300	0.14	Significant downward	0.150	9.27	Downward
	BOD5	1.100	0.09	Significant upward	0.087	3.44	Upward
	NH3–N	−1.587	0.00	Significant downward	0.127	0.03	Significant downward
	TP	−0.110	0.00	Significant downward	0.277	0.00	Significant downward
	F^−	−0.067	0.39	Significant downward	0.184	17.52	No trend (trendless)

r: decline rate; a: significance level; R²: correlation coefficient of the flow regulation formula.