Data for: Human activity coupled with climate change strengthens the role of lakes as an active pipe of dissolved organic matter

This dataset contains data from an investigation to resolve the relative
importance of multiple environmental drivers on the quantity and quality
of chromophoric DOM in lakes at the continental scales. The study is
described in the paper: “Du Y., Chen F., Zhang Y., He H., Wen S., Huang
X., Song C., Li. K., Wang J., Kellings D., and Lu Y. 2023. Human activity
coupled with climate change strengthens the role of lakes as an active
pipe of dissolved organic matter, Earth’s Future, in press”.  The
primary objectives of the study were to (i) quantity the magnitude of
environmental drivers modulating lacustrine DOM quantity and quality at a
continental scale, including climate, land cover, societal development,
and water retention time, and (ii) unravel individual and interactive
effects of the environmental drivers. Firstly, we constructed a structural
equation model framework that incorporated both direct and indirect
pathways. Secondly, we collected a continental-scale dataset of lake DOM
quantity and quality, along with the corresponding environmental driver
variables from a group of carefully selected lakes (n=182). Lastly, we
established structure equation models to analyze DOM quantity and quality
variations as a function of the four environmental drivers. The main
results include: (1) land cover and societal development both exhibit
positive direct effects on lake CDOM quantity, highlighting the
significant role of well-vegetated soils and anthropogenic activities as
sources of lake DOM on a continental scale. (2) Climate has two strong but
opposite effects –a warming and wet climate facilitates soil OM production
and export but also enhances CDOM in-lake transformation. (3) Three
proxies are proposed as indicators of the magnitude of biogeochemical
drivers influencing lake DOM across ecoclimatic zones, including
fluorescent DOM/DOC indicating economic activity, percentages of a
degraded fluorescent DOM component indicating solar irradiation, and
percent tyrosine-like DOM reflecting DOM processing time within the
watershed and lake.