Beyond high frequency monitoring: an optimised automatic sampling

2021 ◽  
Author(s):  
Jérémy Mougin
Keyword(s):  
Organic Matter ◽  
Water Body ◽  
High Frequency ◽  
Passive Samplers ◽  
Size Exclusion ◽  
Strong Impact ◽  
Small Stream ◽  
Automatic Sampling ◽  
Frequency Monitoring ◽  
On Line

<p>Beyond high frequency monitoring : an optimised automatic sampling</p><p>Mougin Jérémy, Superville Pierre-Jean, Cornard Jean-Paul, Billon Gabriel</p><p> </p><p>In order to improve the representativity of samples when monitoring a water body, efforts have been made these last years to develop new methodologies to replace grab samples. Passive samplers have allowed to have measurement averaged over several days and represented a first step. High frequency monitoring (usually one measure per hour), either in situ or on-line, led to the observations of daily cycles or transitory phenomena that were not suspected beforehand.</p><p>However, such method is usually difficult to implement for some trace analytes (e.g. trace metals or pesticides) or for some specific analysis (e.g. size exclusion chromatography on natural organic matter). Automatic sampling and analysis in the lab can be a solution, but it becomes very labor intensive as soon as the sampling frequency is high. Luck is also needed as a long sampling period can sometimes lead to very few variations if the water system is stable. In order to optimise the automatic sampling, a new methodology has been developped in this project.</p><p>A multiparameter probe measuring general parameters (temperature, pH, turbidity, ORP, conductivity, dissolved oxygen and two fluorometers for organic matter) was coupled with an automatic filtering sampler. The data from the probe are processed on-line and an algorithm decides if the geochemical situation in the water body seems new enough to trigger the sampling, based on previously sampled waters. The aim of this device is to collect the right number of samples with the best representativeness of phenomena taking place in the environment.</p><p>This method will be tested over a year in 2021 in order to monitor the dissolved organic matter in a small stream with both rural and urban contamination. These high-frequency measurements and samplings could make it possible to better define the sources and dynamics of the organic matter that has a strong impact on the quality of watercourses.</p>

scholarly journals Size-Based Characterization of Freshwater Dissolved Organic Matter finds Similarities within a Water Body Type across Different Canadian Ecozones

2020 ◽  
Author(s):  
Pieter J. K. Aukes ◽  
Sherry L. Schiff ◽  
Jason J. Venkiteswaran ◽  
Richard J. Elgood ◽  
John Spoelstra
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Size Exclusion Chromatography ◽  
Water Body ◽  
Size Exclusion ◽  
List Type ◽  
Body Type ◽  
Wide Range ◽  
Exclusion Chromatography ◽  
Dom Composition

ABSTRACTDissolved Organic Matter (DOM) represents a mixture of organic molecules that vary due to different source materials and degree of processing. Characterizing how DOM composition evolves along the aquatic continuum can be difficult. Using a size-exclusion chromatography technique (LC-OCD), we assessed the variability in DOM composition from both surface and groundwaters across a number of Canadian ecozones (mean annual temperature spanning −10 to +6 C). A wide range in DOM concentration was found from 0.2 to 120 mg C/L. Proportions of different size-based groupings across ecozones were variable, yet similarities between specific water-body types, regardless of location, suggest commonality in the processes dictating DOM composition. A PCA identified 70% of the variation in LC-OCD derived DOM compositions could be explained by the water-body type. We find that DOM composition within a specific water-body type is similar regardless of the differences in climate or surrounding vegetation where the sample originated from.HighlightsSize-exclusion chromatography (using LC-OCD) is a fast and effective tool to quantify differences in DOM composition across different environmentsProportions of biopolymers and low molecular weight fractions can distinguish between surface and groundwater DOMSimilar water-body types have comparable DOM size compositions across ecozones that range in annual air temperatures from –10 to 6ºC

Application of a fractionation technique for better understanding of the removal of natural organic matter by alum coagulation

2002 ◽  
Vol 2 (5-6) ◽  
pp. 427-433 ◽  
Author(s):  
J. van Leeuwen ◽  
C. Chow ◽  
R. Fabris ◽  
N. Withers ◽  
D. Page ◽  
...  
Keyword(s):  
Organic Matter ◽  
Natural Organic Matter ◽  
High Performance ◽  
Relative Proportion ◽  
Water Source ◽  
Size Exclusion ◽  
Gas Chromatography Mass Spectrometry ◽  
Pyrolysis Gas ◽  
Alum Treatment ◽  
Hydrophobic Acids

To gain an improved understanding of the types of organic compounds that are recalcitrant to water treatment, natural organic matter (NOM) isolates from two drinking water sources (Mt. Zero and Moorabool reservoirs, Victoria, Australia) were separated into fractions of distinct chemical behaviour using resins. Four fractions were obtained from each water source and were organics absorbed to: (1) XAD-8 (very hydrophobic acids, VHA); (2) DAX-4 (slightly hydrophobic acids, SHA); (3) bound to an anion exchange resin (charged organics, CHAR); and (4) not absorbed or bound to resins (neutrals, NEUT). These fractions were then tested to determine the capacity of alum to remove them from water and to correlate this with the character of each isolate. The fractions were characterised by the application of high performance size exclusion chromatography (HPSEC), bacterial regrowth potential (BRP), trihalomethane formation potential (THMFP), pyrolysis gas-chromatography mass spectrometry (Py-GC-MS) and thermochemolysis. The highest removals of dissolved organic carbon (DOC) by alum treatment were in waters spiked with the CHAR fractions while the NEUT fractions were the most recalcitrant. The number average molecular weights (Mn) of DOC of the CHAR fractions before treatment were the highest, whilst those of the NEUT fractions were the lowest. After alum treatment, the Mn of the NEUT fractions were only slightly reduced. Results from Py-GC-MS and thermochemolysis indicate that the NEUT fractions had the highest relative proportion of saccharide derived organic material. Nonetheless, the BRP of waters spiked with the NEUT fractions differed markedly, indicating that organics recalcitrant to alum treatment can vary substantially in their chemical composition and capacity to support microbial growth.

scholarly journals Providing online STEM workshops in times of isolation

2021 ◽  
Vol 1 (6) ◽  
Author(s):  
Robert Weinhandl ◽  
Susanne Thrainer ◽  
Zsolt Lavicza ◽  
Tony Houghton ◽  
Markus Hohenwarter
Keyword(s):  
Grounded Theory ◽  
Success Factors ◽  
Qualitative Interview ◽  
Strong Impact ◽  
Learning And Teaching ◽  
Learning Barriers ◽  
On Line ◽  
Trained Teachers ◽  
And Mathematics ◽  
Interview Studies

AbstractThe global spread of COVID-19 has resulted in learning and teaching being confronted with immense challenges and changes since spring 2020. Measures to contain the COVID-19 pandemic had and continue to have a particularly strong impact on non-formal and informal learning, which are important features of out-of-class on-line STEM workshops combining science, technology, engineering and mathematics. We developed and carried out online STEM workshops for approximately 250 students during times of isolation in the spring and summer of 2020. To identify potential success factors and stumbling blocks for designing and implementing online STEM workshops, we conducted a qualitative interview-based study with a selection of eight experts in the summer and autumn 2020, i.e. after the STEM workshops. The experts were Austrian and German teachers who planned and implemented STEM workshops for students age 10 to 18. Our collected data was examined using techniques of grounded theory approaches. Using techniques of qualitative interview studies and grounded theory approaches, we found that removing learning barriers and creating new types of learning spaces, online socio-constructivist learning, and teachers' TPACK for STEM Workshops are important factors when considering and designing STEM workshops for online learning environments. These same factors will also be central when planning and implementing online STEM workshops in post-COVID-19 times. To facilitate student participation and to increase social interaction are critical elements for practitioners working on online STEM workshops—both during and after COVID-19. Highly trained teachers with in-depth technical, pedagogical, and content skills are essential to facilitate participation and interactions among students, teachers, and learning contents.

On-line measurement of total c and 14C of 14C-Labelled organic matter

1994 ◽  
Vol 26 (3) ◽  
pp. 407-411 ◽  
Author(s):  
P. Benoit ◽  
Choné Th. ◽  
E. Barriuso
Keyword(s):  
Organic Matter ◽  
Line Measurement ◽  
On Line
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