Fig. 4
![Fig. 4](http://media.springernature.com/full/springer-static/image/art%3A10.1186%2Fs12302-021-00558-z/MediaObjects/12302_2021_558_Fig4_HTML.png)
Synchronous and asynchronous maps of hetero 2D-COS of PARAFAC components of DOM from wastewater in the WWTP. Red presents positive correlations and blue presents negative correlations. a synchronous map of C1 and C2; b asynchronous map of C1 and C2; c synchronous map of C1 and C4; d asynchronous map of C1 and C4; e synchronous map of C3 and C4; f asynchronous map of C3 and C4