scholarly journals Microbial Processing and Production of Aquatic Fluorescent Organic Matter in a Model Freshwater System

Water ◽  
2018 ◽  
Vol 11 (1) ◽  
pp. 10
Author(s):  
Bethany Fox ◽  
Robin Thorn ◽  
Alexandre Anesio ◽  
Timothy Cox ◽  
John Attridge ◽  
...  
Keyword(s):  
Organic Matter ◽  
Aquatic Ecosystems ◽  
Sampling Period ◽  
Cell Multiplication ◽  
Cellular Processes ◽  
Bacterial Enumeration ◽  
Freshwater System ◽  
Parallel Factor ◽  
Incubation Temperatures

Organic matter (OM) has an essential biogeochemical influence along the hydrological continuum and within aquatic ecosystems. Organic matter derived via microbial processes was investigated within a range of model freshwater samples over a 10-day period. For this, excitation-emission matrix (EEM) fluorescence spectroscopy in combination with parallel factor (PARAFAC) analysis was employed. This research shows the origin and processing of both protein-like and humic-like fluorescence within environmental and synthetic samples over the sampling period. The microbial origin of Peak T fluorescence is demonstrated within both synthetic samples and in environmental samples. Using a range of incubation temperatures provides evidence for the microbial metabolic origin of Peak T fluorescence. From temporally resolved experiments, evidence is provided that Peak T fluorescence is an indication of metabolic activity at the microbial community level and not a proxy for bacterial enumeration. This data also reveals that humic-like fluorescence can be microbially derived in situ and is not solely of terrestrial origin, likely to result from the upregulation of cellular processes prior to cell multiplication. This work provides evidence that freshwater microbes can engineer fluorescent OM, demonstrating that microbial communities not only process, but also transform, fluorescent organic matter.

scholarly journals A Single Species, Micromonas pusilla (Prasinophyceae), Dominates the Eukaryotic Picoplankton in the Western English Channel

2004 ◽  
Vol 70 (7) ◽  
pp. 4064-4072 ◽  
Author(s):  
Fabrice Not ◽  
Mikel Latasa ◽  
Dominique Marie ◽  
Thierry Cariou ◽  
Daniel Vaulot ◽  
...  
Keyword(s):  
Aquatic Ecosystems ◽  
Fluorescent In Situ Hybridization ◽  
Algal Species ◽  
Sampling Period ◽  
Single Species ◽  
English Channel ◽  
Green Algal ◽  
Micromonas Pusilla ◽  
Green Algal Species

ABSTRACT The class Prasinophyceae (Chlorophyta) contains several photosynthetic picoeukaryotic species described from cultured isolates. The ecology of these organisms and their contributions to the picoeukaryotic community in aquatic ecosystems have received little consideration. We have designed and tested eight new 18S ribosomal DNA oligonucleotide probes specific for different Prasinophyceae clades, genera, and species. Using fluorescent in situ hybridization associated with tyramide signal amplification, these probes, along with more general probes, have been applied to samples from a marine coastal site off Roscoff (France) collected every 2 weeks between July 2000 and September 2001. The abundance of eukaryotic picoplankton remained high (>103 cells ml−1) during the sampling period, with maxima in summer (up to 2 × 104 cells ml−1), and a single green algal species, Micromonas pusilla (Prasinophyceae), dominated the community all year round. Members of the order Prasinococcales and the species Bathycoccus prasinos (Mamiellales) displayed sporadic occurrences, while the abundances of all other Prasinophyceae groups targeted remained negligible.

Increases in humic and bioavailable dissolved organic matter in a forested New England headwater stream with increasing discharge

2016 ◽  
Vol 67 (9) ◽  
pp. 1279 ◽  
Author(s):  
Henry F. Wilson ◽  
Peter A. Raymond ◽  
James E. Saiers ◽  
William V. Sobczak ◽  
Na Xu
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
New England ◽  
Aquatic Ecosystems ◽  
Redox State ◽  
Headwater Stream ◽  
Four Component Model ◽  
Parallel Factor ◽  
Aquatic Sciences ◽  
Hillslope Processes

Understanding the processes controlling the transfer of organic matter from terrestrial to aquatic ecosystems is of fundamental importance for the aquatic sciences. Over the course of a full year, fluorescence, absorbance and bioavailability of dissolved organic matter (DOM) were characterised in Bigelow Brook, a forested headwater stream in Massachusetts, USA. Parallel factor analysis (PARAFAC) identified a four-component model to describe observed DOM fluorescence (C1–C4). Component C2 exhibited the characteristics of a more humic-like fluorophore, with a potentially more reduced redox state and increased with discharge, whereas more fulvic-like (C1) and protein-like (C3, C4) fluorophores decreased. Under both dark and light-exposed conditions, percentage bioavailable dissolved organic carbon (%BDOC) increased with discharge (R2 = 0.37 and R2 = 0.56). C2 and specific absorptivity (SUVA) were reduced following BDOC incubations, whereas C1, C3 and C4 increased. These changes to DOM characteristics with increasing discharge were observed under both baseflow and stormflow conditions, indicating that with rising watertable, loading from a large riparian or hyporheic pool of organic matter is likely occurring. Other headwater streams, where loading is controlled by hillslope processes, are likely to exhibit a similar pattern of increasing export of more humic and bioavailable DOM during hydrologic events.

scholarly journals Effects of land use and nutrients on the characteristics of dissolved organic matter in the Nanchong Section of Jialing River, China in December 2019

2021 ◽  
Author(s):  
Liuqing Zhang ◽  
Xiaohua Zhu ◽  
Xing Huang ◽  
Chaorong Liu ◽  
Yan Yang
Keyword(s):  
Land Use ◽  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Absorption Coefficient ◽  
Aquatic Ecosystems ◽  
Direct Evidence ◽  
Chromophoric Dissolved Organic Matter ◽  
Jialing River ◽  
Parallel Factor ◽  
Effects Of Land Use

Abstract Chromophoric dissolved organic matter (CDOM) in aquatic ecosystems can reflect the impacts of human activities on the carbon-cycling process. However, direct evidence of the combined effect of land use and anthropogenic nutrients on CDOM characteristics in river ecosystems is limited. Herein, we collected water samples from 18 sites in the Nanchong section of Jialing River in December 2019 to elucidate how the land use and nutrients affect the source and composition of CDOM through parallel factor (PARAFAC) analysis of excitation–emission matrices (EEMs). First, the absorption coefficient a254 (r2=0.29, p<0.01) and three fluorescence components (humic-like C1 and C2 and protein-like C3) (r2=0.31–0.37, p<0.01) significantly increased with increased urban area, and the four parameters were higher in the urban than in the suburb (p<0.05). The correlation between small CDOM molecule and cropland land was positive (p<0.01). Second, the increase in nutrient levels increased the a254 (r2=0.84 and 0.33, p<0.01) and three fluorescence components (r2=0.30–0.84, p<0.01 or p<0.05). Third, allochthonous CDOM were prevalent in the Nanchong Section of Jialing River, and the proportions of C1 and C2 were 42 and 41%, respectively. Our findings indicated that the variability of source and composition of CDOM significantly depended on urbanization and increased nutrients in the Nanchong Section of Jialing River.

scholarly journals Dissolved organic matter and its optical characteristics in the Laptev and East Siberian seas: spatial distribution and interannual variability (2003–2011)

Ocean Science ◽  
2018 ◽  
Vol 14 (1) ◽  
pp. 87-103 ◽  
Author(s):  
Svetlana P. Pugach ◽  
Irina I. Pipko ◽  
Natalia E. Shakhova ◽  
Evgeny A. Shirshin ◽  
Irina V. Perminova ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Aquatic Ecosystems ◽  
Spectral Characteristics ◽  
Optical Characteristics ◽  
Arctic Shelf ◽  
Dominant Factor ◽  
Salinity Range ◽  
The World

Abstract. The East Siberian Arctic Shelf (ESAS) is the broadest and shallowest continental shelf in the world. It is characterized by both the highest rate of coastal erosion in the world and a large riverine input of terrigenous dissolved organic matter (DOM). DOM plays a significant role in marine aquatic ecosystems. The chromophoric fraction of DOM (CDOM) directly affects the quantity and spectral quality of available light, thereby impacting both primary production and ultraviolet (UV) exposure in aquatic ecosystems. A multiyear study of CDOM absorption, fluorescence, and spectral characteristics was carried out over the vast ESAS in the summer–fall seasons. The paper describes observations accomplished at 286 stations and 1766 in situ high-resolution optical measurements distributed along the nearshore zone. Spatial and interannual CDOM dynamics over the ESAS were investigated, and driving factors were identified. It was shown that the atmospheric circulation regime is the dominant factor controlling CDOM distribution on the ESAS. This paper explores the possibility of using CDOM and its spectral parameters to identify the different biogeochemical regimes in the surveyed area. The analysis of CDOM spectral characteristics showed that the major part of the Laptev and East Siberian seas shelf is influenced by terrigenous DOM carried in riverine discharge. Western and eastern provinces of the ESAS with distinctly different DOM optical properties were also identified; a transition between the two provinces at around 165–170° E, also consistent with hydrological and hydrochemical data, is shown. In the western ESAS, a region of substantial river impact, the content of aromatic carbon within DOM remains almost constant. In the eastern ESAS, a gradual decrease in aromaticity percentage was observed, indicating contribution of Pacific-origin waters, where allochthonous DOM with predominantly aliphatic character and much smaller absorption capacity predominates. In addition, we found a stable tendency towards reduced concentrations of CDOM and dissolved lignin and an increase in spectral slope and slope ratio values eastward from the Lena River delta; the Lena is the main supplier of DOM to the eastern Arctic shelf. The strong positive correlation (r  =  0.97) between dissolved organic carbon (DOC) and CDOM values in the surface shelf waters influenced by terrigenous discharge indicates that it is feasible to estimate DOC content from CDOM fluorescence assessed in situ using a WETStar fluorometer. This approach is reliable over the salinity range of 3 to 24.5. The fact that there is little difference between predicted and observed parameters indicates that the approach is justified. The direct estimation of DOM optical characteristics in the surface ESAS waters provided by this multiyear study will also be useful for validating and calibrating remote sensing data.

scholarly journals Lipid biomarkers in Holocene and glacial sediments from ancient Lake Ohrid (Macedonia, Albania)

2010 ◽  
Vol 7 (11) ◽  
pp. 3473-3489 ◽  
Author(s):  
J. Holtvoeth ◽  
H. Vogel ◽  
B. Wagner ◽  
G. A. Wolff
Keyword(s):  
Organic Matter ◽  
Lipid Biomarkers ◽  
Lake Ohrid ◽  
Labile Organic Matter ◽  
Glacial Sediments ◽  
Plant Matter ◽  
Lipid Biomarker ◽  
First Results ◽  
Near Shore

Abstract. Organic matter preserved in Lake Ohrid sediments originates from aquatic and terrestrial sources. Its variable composition reflects climate-controlled changes in the lake basin's hydrology and related organic matter export, i.e. changes in primary productivity, terrestrial plant matter input and soil erosion. Here, we present first results from lipid biomarker investigations of Lake Ohrid sediments from two near-shore settings: site Lz1120 near the southern shore, with low-lying lands nearby and probably influenced by river discharge, and site Co1202 which is close to the steep eastern slopes. Variable proportions of terrestrial n-alkanoic acids and n-alkanols as well as compositional changes of ω-hydroxy acids document differences in soil organic matter supply between the sites and during different climate stages (glacial, Holocene, 8.2 ka cooling event). Changes in the vegetation cover are suggested by changes in the dominant chain length of terrestrial n-alkanols. Effective microbial degradation of labile organic matter and in situ contribution of organic matter derived from the microbes themselves are both evident in the sediments. We found evidence for anoxic conditions within the photic zone by detecting epicholestanol and tetrahymanol from sulphur-oxidising phototrophic bacteria and bacterivorous ciliates and for the influence of a settled human community from the occurrence of coprostanol, a biomarker for human and animal faeces (pigs, sheep, goats), in an early Holocene sample. This study illustrates the potential of lipid biomarkers for future environmental reconstructions using one of Europe's oldest continental climate archives, Lake Ohrid.

scholarly journals Heavy-metal pollution alters dissolved organic matter released by bloom-forming Microcystis aeruginosa

RSC Advances ◽  
2017 ◽  
Vol 7 (30) ◽  
pp. 18421-18427 ◽  
Author(s):  
Haiming Wu ◽  
Li Lin ◽  
Guangzhu Shen ◽  
Ming Li
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Microcystis Aeruginosa ◽  
Metal Pollution ◽  
Heavy Metal Pollution ◽  
Aquatic Ecosystems ◽  
Eutrophic Lakes

The risk of heavy metals to aquatic ecosystems was paid much attention in recent years, however, the knowledge on effects of heavy metals on dissolved organic matter (DOM) released byMicrocystiswas quite poor, especially in eutrophic lakes.

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