The lead section is well written but is too lengthy, and I would suggest adding more hyperlinks. Using a larger font size or underlining the subheadings would better contrast them with the paragraphs. The sections are organized well, one suggestion is to have a section for lead in the biosphere with subsections: oceans and freshwater. Each section’s length is equal to its importance, everything is on-topic, and the article is un-biased. The figure is drawn well, with larger fluxes depicted by larger arrows. The figure is cohesive and makes good use of space, and the caption is very descriptive. I would link the references to the figure and make the figure bigger and center it. Overall, this is well written and thorough. I suggest adding more hyperlinks throughout the article and linking the references, but that should be an easy fix. Great job.
