Variation of Water Quality in Ningxia Section of the Yellow River in Recent 5 Years

Figure 4

Correlation heatmap among the water quality parameters of the Ningxia section of the Yellow River during 2016–2020. (a) 2016; (b) 2017; (c) 2018; (d) 2019; (e) 2020. AN means ammonia-nitrogen.

(a)

(b)

(c)

(d)

(e)