Distribution of dissolved organic carbon in lakes of different trophic types

Abstract

The distributions of dissolved organic carbon (DOC) in the warm season were elucidated in ten lakes of different trophic types in Japan, Russia, and China. DOC showed similar vertical distributions in all the lakes in summer when thermal stratification occurred. DOC in the epilimnion was higher than the value of 0.8 mg C l Ϫ1 found in the hypolimnion. In three Japanese lakes, hypolimnion DOC was negatively correlated with apparent oxygen utilization (AOU), reflecting the net oxidation of DOC using the dissolved oxygen in lake water. The DOC : O 2 ratios (0.115-0.179), calculated by the slopes of the regression lines of DOC versus AOU in hypolimnion water, were as low as those of deep-sea water, which indicates low bioavailability of lake water DOC for heterotrophic bacteria. DOC and conductivity did not correlate well except in two Japanese lakes: one showed a positive correlation and the other a negative correlation, indicating DOC loading from the inflowing rivers. Eutrophic lakes tended to have higher DOC values than meso-and oligotrophic lakes, and DOC values in the surface water negatively correlated with Secchi depths.

Distribution of dissolved organic carbon and dissolved fulvic acid in mesotrophic Lake Biwa, Japan

“…However, in lakes having low DOC concentrations (below 5.0 mg C l -1 ), the C : N ratios are low (approximately 12.2-15.1) and are similar to those of autochthonous algae and macrophytes (approximately 12). In oligo-and mesotrophic lakes such as Lake Biwa in this paper, in which DOC remains at low concentrations below several mg C l -1 (Sugiyama et al 2004), determining the nature of DOC is very difficult. Thus, developments of separate techniques relating to the chemical, physical, and biological characteristics of DOC are very important.…”

Dynamics of dissolved organic carbon in eutrophic Lake Taihu and its tributaries and their implications for bacterial abundance during autumn and winter

“…Monteiro et al (2014) predicted DOC concentrations in an Amazonian black-water catchment using EC measures. Moreover, a significant positive correlation between DOC and EC was observed in both mesotrophic Lake Ikeda (Sugiyama et al 2004) and Yasu River (Mostofa et al 2007) in Japan. Large amounts of untreated wastewater from factories and residential areas are discharged into Chendonggang and Yincungang rivers (Yang et al 2012), a significant difference (n D 5, p D 0.04, two-tailed t-test) in EC was observed between lake center and Chendonggang River.…”

“…Large amounts of untreated wastewater from factories and residential areas are discharged into Chendonggang and Yincungang rivers (Yang et al 2012), a significant difference (n D 5, p D 0.04, two-tailed t-test) in EC was observed between lake center and Chendonggang River. Moreover, a positive relationship was apparent in Lake Taihu (n D 25, r D 0.5, p D 0.01), indicating that a fraction of DOC is input from the inflow rivers (Yoshioka et al 2002;Sugiyama et al 2004).…”

“…Therefore, it would be reasonable to assume that the dynamics of DOC are influenced by riverine input. Where water bodies of different chemical composition meet, EC can be used as an index of solute mixing (Sugiyama et al 2004). Monteiro et al (2014) predicted DOC concentrations in an Amazonian black-water catchment using EC measures.…”

Long-term trends of chemical and modelled photochemical parameters in four Alpine lakes

“…Several authors have reported an inverse correlation between DOC values and Secchi disk depths (Sugiyama et al, 2004;Aguilera et al, 2013), based on the reasonable assumption that high-DOC waters show elevated absorption of sunlight (Morris et al, 1995). In fact, the combination of absorbing material and suspended particles in high concentration would decrease the penetration of sunlight in the water column (Wetzel, 2001;Salmaso et al, 2007).…”