The primary sources of dissolved inorganic carbon (DIC) in water are
carbonate materials and CO produced during the
biological processing of organic matter. The application of carbon
isotope techniques to terrestrial and aquatic ecosystems can accurately
elucidate carbon fluxes and other carbon cycle processes in these
systems. Lake ecosystems on the Qinghai-Tibetan Plateau are fragile and
sensitive to changes in climate and environment. This study explored the
relationship between the carbon isotopic composition
(δC) of the DIC
(δC) in the Genggahai Lake, the
lake environment, and the climate of the watershed based on the observed
physicochemical parameters of water in areas with different types of
submerged macrophyte communities, combined with changes in the
temperature and precipitation during the same period. Overall, the
δC of the Genggahai Basin
exhibited a large range of values, with an average
δC for inflowing spring water
(δC) of –11.1 ‰, which was the
most negative, followed by an average
δC value of –10.8 ‰ for that
from the Shazhuyu River (δC)
and an averageδC value of –6.91
‰ for lake water (δC).
Variations in the photosynthetic activity intensity of different aquatic
plants yield significantly changing
δC values in areas with varied
aquatic plant communities. Hydrochemical observations revealed that
δC and aquatic plant
photosynthesis primarily affected the differences in the
δC values of the Genggahai
Lake, thereby identifying them as the key components of the lake carbon
cycle.