Fractionation and characterization of dissolved organic matter in a shallow eutrophic lake, its inflowing rivers, and other organic matter sources

Wang

et al. 2007

Environ Monit Assess

Dissolved organic matter (DOM) and its potential to form disinfection by-products (DBPs) during drinking water treatment raise challenges to water quality control. Understanding both chemical and physical characteristics of DOM in source waters is key to better water treatment. In this study, the DOM from four typical source waters in China was fractionated by XAD resin adsorption (RA) and ultrafiltration (UF) techniques. The trihalomethane formation potential (THMFP) of all fractions in the DOM were investigated to reveal the major THM precursors. The fraction distributions of DOM could be related to their geographical origins in a certain extent. The dominant chemical fraction as THM precursors in the DOM from south waters (East-Lake reservoir in Shenzhen and Peal rivers in Guangzhou) was hydrophobic acid (HoA). The size fraction with molecular weight (MW) <1 kDa in both south waters had the highest THMFP. The results of cluster analysis showed that the parameters of fractions including DOC percentage (DOC%), UV 254 %, SUVA 254 (specific UV 254 absorbance) and THMFP were better for representing the differences of DOM from the studied waters than specific THMFP (STHMFP). The weak correlation between SUVA 254 and STHMFP for either size or XAD fractions suggests that whether SUVA 254 can be used as an indicator for the reactivity of THM formation is highly dependent on the nature of organic matter.

Section: Chemical Fractions Of Domsupporting

confidence: 93%

Section: Fractionation Of Dom By Resin Adsorptionmentioning

confidence: 99%

Size and resin fractionations of dissolved organic matter and trihalomethane precursors from four typical source waters in China

Wang

et al. 2007

Environ Monit Assess

“…The humic substances are derived from decaying plant debris and are major components of organic matter in soil and freshwater environments. Imai et al (37) reported that about 32% of DOC consisted of humic substances in Lake Kasumigaura. In the open ocean, the fraction of humic substances in DOC appears to be much lower (ϳ10%) (38).…”

Section: Discussionmentioning

confidence: 99%

Bacterial Contribution to Dissolved Organic Matter in Eutrophic Lake Kasumigaura, Japan

Kawasaki

Komatsu

Kohzu

et al. 2013

Appl Environ Microbiol

Self Cite

dIncubation experiments using filtered waters from Lake Kasumigaura were conducted to examine bacterial contribution to a dissolved organic carbon (DOC) pool. Bacterial abundance, bacterial production, concentrations of DOC, total dissolved amino acids (TDAA), and total dissolved neutral sugars (TDNS) were monitored during the experiments. Bacterial production during the first few days was very high (20 to 35 g C liter ؊1 day ؊1 ), accounting for 40 to 70% of primary production. The total bacterial production accounted for 34 to 55% of the DOC loss during the experiment, indicating high bacterial activities in Lake Kasumigaura. The DOC degradation was only 12 to 15%, whereas the degradation of TDAA and TDNS ranged from 30 to 50%, suggesting the preferential usage of TDAA and TDNS. The contribution of bacterially derived carbon to a DOC pool in Lake Kasumigaura was estimated using D-amino acids as bacterial biomarkers and accounted for 30 to 50% of the lake DOC. These values were much higher than those estimated for the open ocean (20 to 30%). The ratio of bacterially derived carbon to bulk carbon increased slightly with time, suggesting that the bacterially derived carbon is more resistant to microbial degradation than bulk carbon. This is the first study to estimate the bacterial contribution to a DOC pool in freshwater environments. These results indicate that bacteria play even more important roles in carbon cycles in freshwater environments than in open oceans and also suggests that recent increases in recalcitrant DOC in various lakes could be attributed to bacterially derived carbon. The potential differences in bacterial contributions to dissolved organic matter (DOM) between freshwater and marine environments are discussed.

“…Unsaturated bonds, found in a variety of aromatic humic substances (e.g. phenols, benzene rings, carboxylic acids), have maximum absorbance near 254 nm (Imai et al 2001), whereas substances of autochthonous origin are predominantly composed of aliphatic, alicyclic structures, indicative of a lipid hydrocarbon source (Leenheer 1994). DIC was determined on the same occasions as PP.…”

Section: Methodsmentioning

confidence: 99%

Microbial food webs in the dark: independence of lake plankton from recent algal production

Daniel¹,

Gutseit²,

Anesio³

et al. 2005

Aquat. Microb. Ecol.

We investigated the development of a heterotrophic plankton food web with or without phytoplankton primary production in a long-term (>1 yr) laboratory experiment. Water from 3 Swedish lakes (humic, oligotrophic clearwater, eutrophic) was exposed to low light or kept in total darkness in triplicate 100 l cylinders. Dissolved organic carbon (DOC) dynamics, bacterial growth and biomass of protozoans, rotifers and microcrustaceans were followed over 18 mo. In the dark treatments, no primary production was detected and DOC concentrations decreased by between 19 and 27% (1.3 to 3.2 mg C l -1). There was bacterial and protozoan growth in the dark during the whole experimental period. However, numbers and production of bacteria, as well as protozoan biomass, were significantly lower in darkness. Dissolved (DOM) and particulate organic matter (POM) initially present in the water (i.e. 18 mo old at the end of the experiment) helped to support substantial metazoan biomasses in dark treatments in the humic and eutrophic waters, but not in the oligotrophic clearwater lake. DOM in the humic water, thus largely of allochthonous origin, gave the highest and most prolonged support to zooplankton living in darkness. Our study indicates that a microbial food web, based on allochthonous organic matter and developing independently from phytoplankton, can act as a link to metazoan zooplankton, especially in oligotrophic humic lakes. These results confirm studies using stable C isotopes, showing a substantial incorporation of terrestrial carbon into zooplankton.KEY WORDS: Dissolved organic matter · DOM · Bacteria · Microbial food web · Zooplankton · Lake · Terrestrial carbon Resale or republication not permitted without written consent of the publisher