Labile dissolved organic carbon

Sondergaard, M., and M. Middleboe. 1995. A cross-system analysis of labile dissolved organic carbon. Marine Ecology — Progress Series 118 283-294. 

Sobczak, W. V. 1996. Epilithic bacterial responses to variations in algal biomass and labile dissolved organic carbon during biofilm colonization. Journal of the North American Benthological Society 15 143-154. 

The formula for BCD in Eq. (2) was derived under the assumption that the bacterial growth rate was mineral nutrient limited. If the supply rate of labile organic carbon from allochthonous and autochthonous sources is insufficient to meet this demand, the pool of labile dissolved organic carbon (DOC) will eventually be depleted and the bacteria will become carbon... 

Zweifel, U. L. 1999. Factors controlling accumulation of labile dissolved organic carbon in the Gulf of Riga. Eastuarine, Coastal and Shelf Science 48 357—370. 

Heterotrophic bacteria are now seen as potentially important links between dissolved resources and higher trophic levels (Vadstein et ah, 1993). This altered view of the role of bacteria has especially important consequences for conceptualizing the significance of bacteria in phosphorus dynamics at the base of the food web, because heterotrophic bacteria differ from phytoplankton in being relatively phosphorus-rich organisms (Vadstein, 2000). Heterotrophic bacterial metabolism of phosphorus is dependent not only on phosphorus availability but also on the availability of labile dissolved organic carbon in the immediate environment. 

Table 9.2. Two physiological states of natural bacterioplankton assemblages. Cellular phosphorus content and phosphate uptake in environments with low or high concentrations of labile dissolved organic carbon. Values are means (standard error in parentheses). Reproduced from Gao (2002) with permission. ND, not determined.

Park, J. C., M. Aizaki, T. Fukushima, and A. Otsuki. 1997. Production of labile and refractory dissolved organic carbon by zooplankton excretion An experimental study using large outdoor continuous flow-through ponds. Canadian Journal of Fisheries and Aquatic Sciences 54 434—443. 

Bano, N., M. A. Moran, and R. E. Hodson. 1998. Photochemical formation of labile organic matter from two components of dissolved organic carbon in a freshwater wetland. Aquatic Microbial Ecology 16 95-102. 

Sondergaard, M., B. Hansen, and S. Markager. 1995. Dynamics of dissolved organic carbon lability in a eutrophic lake. Limnology and Oceanography 40 46-54. 

FIGURE 1 Detrital structure and primary fluxes of dissolved organic carbon in lake ecosystems with the food-web structure of predominantly pelagic components (box) that reflects the importance of the microbiota, the microbial loop, and physical processes by which most other organic matter inputs are metabolized heterotrophically or degraded by physical processes. DOM denotes dissolved organic matter, with labile (LDOM) and recalcitrant (RDOM) components POM denotes particulate organic matter. 

FIGURE 2 Common sources of organic carbon and rates of mineralization of labile (LDOC) and recalcitrant (RDOC) dissolved organic carbon in lakes and streams. 

After filtration, samples for reactive Hg (Hg-R) and total dissolved Hg (Hg-T) were acidified with 0.5% HC1.47 BrCl is also often used to preserve samples intended for Hg-T determination. The acidification of samples to be used for Hg-R determination was not recommended by Parker and Bloom,85 especially those with high levels of dissolved organic carbon (DOC). DOC may coagulate after acidification of the solution, with concomitant adsorption and precipitation of Hg-R. Labile Hg (Hg-R) appears to be relatively stable (days to weeks) in filtered, unpreserved samples. 

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