The Behavior of Low Molecular Weight Organic Carbon-14 Containing Compounds in Contaminated Groundwater During Denitrification and Iron-Reduction

Removal of natural organic matter (NOM) in biofilters can be affected by many factors including NOM characteristics, use of pre-ozonation, water temperature, and biofilter backwashing. Laboratory experiments were performed and a biofilter simulation model was developed for the purpose of evaluating the effects of each of these factors on NOM removal in biofilters. Four sources of NOM were used in this study to represent a broad spectrum of NOM types that may be encountered in water treatment. In batch experiments with raw NOM, the removal of organic carbon by biodegradation was inversely proportional to the UV absorbance (254 nm)-to-TOC ratio and directly proportional to the percentage of low molecular weight material (as determined by ultrafiltration). The extent and rate of total organic carbon (TOC) removal typically increased as ozone dose increased, but the effects were highly dependent on NOM characteristics. NOM with a higher percentage of high molecular weight material experienced the greatest enhancement in biodegradability by ozonation. The performance of laboratory-scale continuous-flow biofilters was not significantly affected by periodic backwashing, because backwashing was unable to remove large amounts of biomass from the filter media. Model simulations confirmed our experimental results and the model was used to further evaluate the effects of temperature and backwashing on biofilter performance.

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Lack of Correlation between Turnover of Low-Molecular-Weight Dissolved Organic Carbon and Differences in Microbial Community Composition or Growth across a Soil pH Gradient

Applied and Environmental Microbiology ◽

10.1128/aem.02870-10 ◽

2011 ◽

Vol 77 (8) ◽

pp. 2791-2795 ◽

Cited By ~ 31

Author(s):

Johannes Rousk ◽

Philip C. Brookes ◽

Helen C. Glanville ◽

David L. Jones

Keyword(s):

Molecular Weight ◽

Microbial Community ◽

Organic Carbon ◽

Dissolved Organic Carbon ◽

Community Composition ◽

Soil Ph ◽

Predictive Power ◽

Microbial Community Composition ◽

Low Molecular Weight ◽

Soil C

ABSTRACTWe studied how soil pH (pHs 4 to 8) influenced the mineralization of low-molecular-weight (LMW)-dissolved organic carbon (DOC) compounds, and how this compared with differences in microbial community structure. The mineralization of LMW-DOC compounds was not systematically connected to differences in soil pH, consistent with soil respiration. In contrast, the microbial community compositions differed dramatically. This suggests that microbial community composition data will be of limited use in improving the predictive power of soil C models.

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Interactions between aged biochar, fresh low molecular weight carbon and soil organic carbon after 3.5 years soil-biochar incubations

Geoderma ◽

10.1016/j.geoderma.2018.07.016 ◽

2019 ◽

Vol 333 ◽

pp. 99-107 ◽

Cited By ~ 11

Author(s):

Xinyu Jiang ◽

Xiangping Tan ◽

Jiong Cheng ◽

Michelle L. Haddix ◽

M. Francesca Cotrufo

Keyword(s):

Molecular Weight ◽

Organic Carbon ◽

Soil Organic Carbon ◽

Low Molecular Weight

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Identification and analysis of low-molecular-weight dissolved organic carbon in subglacial basal ice ecosystems by ion chromatography

Biogeosciences ◽

10.5194/bg-13-3833-2016 ◽

2016 ◽

Vol 13 (12) ◽

pp. 3833-3846 ◽

Cited By ~ 8

Author(s):

Emily C. O'Donnell ◽

Jemma L. Wadham ◽

Grzegorz P. Lis ◽

Martyn Tranter ◽

Amy E. Pickard ◽

...

Keyword(s):

Molecular Weight ◽

Organic Carbon ◽

Dissolved Organic Carbon ◽

Microbial Activity ◽

Free Amino ◽

Low Molecular Weight ◽

Subglacial Environment ◽

Basal Ice ◽

Order Of Magnitude

Abstract. Determining the concentration and composition of dissolved organic carbon (DOC) in glacial ecosystems is important for assessments of in situ microbial activity and contributions to wider biogeochemical cycles. Nonetheless, there is limited knowledge of the abundance and character of DOC in basal ice and the subglacial environment and a lack of quantitative data on low-molecular-weight (LMW) DOC components, which are believed to be highly bioavailable to microorganisms. We investigated the abundance and composition of DOC in basal ice via a molecular-level DOC analysis. Spectrofluorometry and a novel ion chromatographic method, which has been little utilized in glacial science for LMW-DOC determinations, were employed to identify and quantify the major LMW fractions (free amino acids, carbohydrates, and carboxylic acids) in basal ice from four glaciers, each with a different type of overridden material (i.e. the pre-entrainment sedimentary type such as lacustrine material or palaeosols). Basal ice from Joyce Glacier (Antarctica) was unique in that 98 % of the LMW-DOC was derived from the extremely diverse free amino acid (FAA) pool, comprising 14 FAAs. LMW-DOC concentrations in basal ice were dependent on the bioavailability of the overridden organic carbon (OC), which in turn was influenced by the type of overridden material. Mean LMW-DOC concentrations in basal ice from Russell Glacier (Greenland), Finsterwalderbreen (Svalbard), and Engabreen (Norway) were low (0–417 nM C), attributed to the relatively refractory nature of the OC in the overridden palaeosols and bedrock. In contrast, mean LMW-DOC concentrations were an order of magnitude higher (4430 nM C) in basal ice from Joyce Glacier, a reflection of the high bioavailability of the overridden lacustrine material (> 17 % of the sediment OC comprised extractable carbohydrates, a proxy for bioavailable OC). We find that the overridden material may act as a direct (via abiotic leaching) and indirect (via microbial cycling) source of DOC to the subglacial environment and provides a range of LMW-DOC compounds that may stimulate microbial activity in wet subglacial sediments.

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