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DIURNAL AND EPISODIC DRIVERS OF STABLE CARBON ISOTOPES AND DISSOLVED GASSES IN THE HYPEREUTROPHIC LAKE TAIHU, CHINA (E)

The increasing frequency and magnitude of harmful algal blooms (HABs) is a global problem, exacerbated by rising temperatures, cultural eutrophication, urbanization and agricultural development. Lake Taihu, China, a hypereutrophic, subtropical lake, is a poster child for this issue, and frequently experiences HABs dominated by potentially toxigenic cyanobacteria. This study investigates the impact of these HABs on the lake carbon (C) cycle at large, and the role of inorganic C supply on phytoplankton ecology. Water samples were collected on a dawn-noon-dusk schedule over the course of a month in northwestern Taihu. Stable C isotopes were quantified for both DIC and POC, along with dissolved gas concentrations, diagnostic phytopigments, and other biogeochemical indicators. Environmental conditions were highly variable over the course of the study, including weeks of monsoon rains, episodic storms, and periods of relative calm. Hot, calm, and potentially CO2 limited conditions were associated with cyanobacterial dominance, while chlorophytes appeared to proliferate during and after storms. The lake was always a source of CH4 to the atmosphere, but fluctuated between a sink and a source for both CO2 and N2O. Diurnal cycles of production and respiration, along with air-water exchange appeared to cause ∂13C-DIC to vary between -4 and -9‰, demonstrating the importance of biological as well as physical factors on inorganic C dynamics. This work highlights the importance of processes at both diel and event-scales.

Authors

Van Dam, B. R., University of North Carolina, USA, bvandam@live.unc.edu

Tobias, C., University of Connecticut, USA, craig.tobias@uconn.edu

Paerl, H. W., University of North Carolina, USA, hpaerl@email.unc.edu

Zhu, G., Nanjing Institute of Geography and Limnology, China, gwzhu@niglas.ac.cn

Details

Poster presentation

Session #:021
Date: 03/03/2017
Time: 11:00 - 12:00
Location: Poster/Exhibit Hall

Presentation is given by student: Yes

PosterID: 215