Fig. 2 Distributions of different land-use types in the study
area. (a) Principal coordinates analysis (PCoA) biplot and (b) area
proportions of major land-use types in three study regions.
The
environmental factors in the different rivers over two seasons (autumn
and spring) are visualized in Fig. S3. In both seasons, Turb, Cond, TN,
TP, NH4+-N, and
NO3--N in water samples from Weihe
River were
significantly
higher compared with those of the Hanjiang River and Qinling
tributaries. Pearson’s correlation coefficients were used to analyze the
impacts of different land-use types on the environmental factors. The
proportions of agricultural land, grassland, urbanized land, and open
water areas
exhibited
significant positive correlations with Turb, Cond, TN, TP,
NH4+-N, and
NO3--N. However, with an increase in
the proportion of forest land area, all environmental factors exhibited
decreasing trends, excluding DO (Fig. S3).