Fig. 1: Map of sampling sites.

a Global and b Central European distribution of 117 sampling sites (numbered blue circles) at which the occurrence and the determinants of intracellular nitrate were studied. The map was created using the software package ODV 5.6.1 (Schlitzer, Reiner, Ocean Data View, odv.awi.de, 2021). Sampling details are given in Supplementary Table 1 (Supplementary Data 1) and in an interactive map created using Google My Maps (https://bit.ly/2XF9kkQ).