Dynamics and sources of dissolved organic carbon during phytoplankton bloom in hypereutrophic Lake Taihu (China)

详细信息    查看全文

• 作者：Linlin Ye^a ; ^b ; Xiaodong Wu^c ; Bo Liu^a ; Dezhi Yan^a ; Fanxiang Kong^b ; ^{fxkong@niglas.ac.cn" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Dissolved organic carbon ; Particulate organic carbon ; Stable carbon isotope ; Bioavailability ; Source ; Lake Taihu
• 刊名：Limnologica - Ecology and Management of Inland Waters
• 出版年：2015
• 出版时间：September 2015
• 年：2015
• 卷：54
• 期：Complete
• 页码：5-13
• 全文大小：1628 K

文摘

To establish the influence of phytoplankton blooms on the dynamics and sources of dissolved organic carbon (DOC) in Lake Taihu, the concentrations and stable carbon isotope values (δ¹³C) of DOC and particulate organic carbon (POC) were analyzed, along with environmental factors, including water temperature, chlorophyll a (Chl a) concentration, phytoplankton community and total bacterial abundance, from March to August 2013 at five sites in Lake Taihu. Significant differences were observed in the DOC concentrations and δ¹³C_DOC values at the sampling sites. On average, the proportion of DOC in the total organic carbon (TOC) pool ranged from 30% ± 10% to 81% ± 7%. POC was positively associated with both Chl a concentration and cyanobacteria biomass, suggesting that cyanobacteria blooms contribute to the POC pool in Lake Taihu. Depleted ¹³C in DOC relative to POC was observed in August, indicating that DOC was partially derived from POC in August. However, Chl a explained only 40% of the variation in DOC in the entirety of Lake Taihu, and at two sites far from the estuary, the contribution of allochthonous carbon was less than 50% in August. These results suggested a greater influence of allochthonous sources on the DOC pool. Moreover, the biodegradability of DOC was further determined by the total dissolved carbohydrates to DOC ratio (TCHO/DOC), specific UV absorbance (SUVA₂₅₄), and the concentrations of bioavailable DOC (BDOC). On average, 17% of the variation in DOC was attributable to the BDOC pool, and the BDOC concentration correlated positively with Chl a, cyanobacteria biomass, and total bacterial abundance, suggesting that cyanobacteria–derived DOC is biodegradable and is preferentially utilized by bacteria.