Systematic microbial production of optically active dissolved organic matter in subarctic lake water

2019 ◽  
Vol 65 (5) ◽  
pp. 951-961
Author(s):  
Martin Berggren ◽  
Cristian Gudasz ◽  
Francois Guillemette ◽  
Geert Hensgens ◽  
Linlin Ye ◽  
...  
2020 ◽  
Author(s):  
Liang Wei

<p>The biogeochemical interfaces are hotspots for organic matter (OM) transformation. However, direct and continuouxiacis tracing of OM transformations and N and P degradation processes are lacking due to the heterogeneous and opaque nature of soil microenvironment. To investigate these processes, a new soil microarray technology (SoilChips) was developed and used. Homogeneous 2-mm-diameter SoilChips were constructed by depositing a dispersed paddy soils with high and low soil organic carbon (SOC) content. A horizon suspension on a patterned glass. Dissolved organic matter from the original soil was added on the SoilChips to mimic biogeochemical processes on interfaces. The chemical composition of biogeochemical interfaces were evaluated via X-ray photoelectron spectroscopy (XPS) and the two-dimensional distribution of enzyme activities in SoilChips were evaluated by zymography. Over 30 days, soil with high SOC content increases microbial nutrition (N and P) requirements than soil with low SOC evidenced by higher hotspots of β-1,4-N-acetaminophen glucosidase, and acid phosphomonoesterases and higher 16S rRNA gene copies. The degree of humification in dissolved organic matter (DOM) was higher and the bioavailability of DOM was poorer in soil with high SOC than soil with low SOC. The poorest bioavailability of DOM was detected at the end of incubation in soil with high SOC. Molecular modeling of OM composition showed that low SOC mainly facilitated the microbial production of glucans but high SOC mainly facilitated the microbial production of proteins. We demonstrated that SOC content or DOM availability for microorganisms modifies the specific OM molecular processing and N and P degradation processes, thereby providing a direct insight into biogeochemical transformation of OM at micro-scale.</p>


2007 ◽  
Vol 184 (1-4) ◽  
pp. 157-176 ◽  
Author(s):  
Khan M. G. Mostofa ◽  
Takahito Yoshioka ◽  
Eiichi Konohira ◽  
Eiichiro Tanoue

2013 ◽  
Vol 71 ◽  
pp. 57-61 ◽  
Author(s):  
Yan-Rong He ◽  
Xiang Xiao ◽  
Wen-Wei Li ◽  
Pei-Jie Cai ◽  
Shi-Jie Yuan ◽  
...  

2015 ◽  
Vol 6 (1) ◽  
Author(s):  
Helena Osterholz ◽  
Jutta Niggemann ◽  
Helge-Ansgar Giebel ◽  
Meinhard Simon ◽  
Thorsten Dittmar

2012 ◽  
Vol 433 ◽  
pp. 238-246 ◽  
Author(s):  
Dolly N. Kothawala ◽  
Eddie von Wachenfeldt ◽  
Birgit Koehler ◽  
Lars J. Tranvik

2017 ◽  
Vol 5 ◽  
Author(s):  
Alina Mostovaya ◽  
Jeffrey A. Hawkes ◽  
Thorsten Dittmar ◽  
Lars J. Tranvik

2007 ◽  
Vol 38 (3) ◽  
pp. 265-285 ◽  
Author(s):  
Birgot Paavel ◽  
Helgi Arst ◽  
Antti Herlevi

The study focuses on the analysis of inherent optical properties of lake waters characterized by consisting of several optically active substances (OAS) (phytoplankton, suspended particles and dissolved organic matter). The results obtained can be useful for deriving the algorithms of optical remote sensing models which need the spectral data on inherent optical properties of the aquatic environment. The spectral absorption and attenuation coefficients were measured in situ using the instrument ac-9 for eight wavelengths in the range of 400–700 nm. The investigation sites were five Finnish and six Estonian lakes. The concentrations of chlorophyll a and total suspended particulate matter, as well as the absorption coefficient of coloured dissolved organic matter (at 380 nm) were determined in a laboratory from water samples taken concurrently with ac-9 measurements. There are three main objectives: (1) to calculate the values of absorption and specific absorption coefficients of tripton on the basis of ac-9 and laboratory data; (2) to estimate the contribution of pure water, chlorophyll a, dissolved organic matter and tripton to the total absorption and attenuation coefficients (results for ac-9 wavelengths and also for the PAR region, 400–700 nm); and (3) to determine the slope (and its variability) of the scattering coefficient spectrum for each measurement series and to estimate the reasons of this variability. At the wavelength of 532 nm the values of the specific absorption coefficient of tripton varied between 0.013 and 0.098 L mg−1 m−1, while the slope of its spectrum ranged from 0.0060 to 0.0109 nm−1. The contributions of different components of the aquatic medium to the total absorption/attenuation coefficients varied noticeably from lake to lake. The slope of the scattering coefficient spectrum was in the range of 0.32–2.5, the multiple regression between the slope and three main optically active substances jointly gave the determination coefficient R2(adjusted)=0.655.


2019 ◽  
Vol 8 (1) ◽  
Author(s):  
Alexandra MacFarland ◽  
Hayley Schiebel

Chromophoric dissolved organic matter (CDOM) is a combination of plant and animal decomposition byproducts and the optically active component of dissolved organic matter (DOM) in water. CDOM measurements have been a focus in the literature related to aqueous environments since the 1980s. Current CDOM analysis is conducted using spectrophotometers that are large, bulky, and expensive (most upwards of $50,000 USD). In this study, the accuracy of a more compact, less expensive (~ $5,500 USD) field spectrometer (StellarNet) was tested for accuracy against a traditional spectrophotometer (Photon Technologies International (PTI)). Thirty-six samples were collected from the Neponset River Salt Marsh in Boston, Massachusetts and analyzed on both instruments with the same set of standards for comparison. The correlation between measurements taken by the two instruments was strongly linear (R2 = 0.9278) and the two sets of data (StellarNet and PTI) were not statistically different (p-value > 0.05), indicating that the less expensive, smaller StellarNet spectrometer is reliable in addition to field appropriate. The StellarNet spectrometer requires additional analysis (compared to the PTI) to convert the output of the instrument (photons) to a concentration (QSU). Highly concentrated sample concentrations (3-fold dilutions required) were not as well-correlated between instruments (R2 = 0.5027). However, this dilution error can be attributed to the length of time (1 year) between sample analysis (i.e., freezing/thawing effects) and/or sampling errors between analysts on the different instruments.


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