Technical Note: Total Dissolved Gas Pressure (TDGP) Sensing in the Laboratory

D'Aoust, Brian G.

doi:10.14227/dt140207p38

Cited by 8 publications

(4 citation statements)

References 11 publications

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“…The gases sources may include the atmosphere, the chemical or biological activities in the water bodies. Therefore, the total dissolved gas pressure (TDGP or PT) is equivalent to the sum of the partial pressures of the all gases dissolved in the water [25].. A pressure increase indicates an increase in the amount of gases dissolved in water [26]. However, in this study, no significant variation in the water pressure for all seasons of the year was observed.…”

Section: Physico-chemical Analysismentioning

confidence: 58%

Spectroscopic Determination of Water Salinity in Brackish Surface Water in Nandoni Dam, at Vhembe District, Limpopo Province, South Africa

Nthunya¹,

Maifadi²,

Mamba³

et al. 2018

Preprint

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The problem of limited water supply in the Vhembe District (Limpopo Province, South Africa) is exacerbated by a preponderance of dissolved salts, which cause disagreeable taste and odour in the water as reported by the communities using this water for drinking. The water treatment plant that supplies the treated water to the communities in the District sources this raw water from the Nandoni Dam at the Livhuvu river catchment. However, there are no scientific studies that have been reported in the literature which focused on determining the levels of water salinity from various water sources in the municipalities of the District. Water samples from various sites across the Nandoni Dam, a primary source of domestic water supply in the region, were collected during all the seasons basis over a period of twelve months in order to ascertain the concentrations of dissolved salts in the dam. Onsite analyses of the water samples were conducted using the YSI ProDSS multimeter, while the laboratory water analyses were conducted using the spectroquant and atomic absorption spectrometers. Although salinity tests seem to indicate that the water sampled across most of the Nandoni Dam is brackish during all seasons of the year with the highest being 750 mg/L, water samples from the dam mid-outlet and the treatment plant are slightly below the WHO brackish water bracket of 500 mg/L with unfavourable taste for drinking. Results from this study indicate that the water sourced from the Nandoni Dam is not suitable for human consumption and therefore requires integrated water resource management, as well as robust and cost-effective water desalination treatment.

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Section: Physico-chemical Analysismentioning

confidence: 58%

Spectroscopic Determination of Water Salinity in Brackish Surface Water in Nandoni Dam, at Vhembe District, Limpopo Province, South Africa

Nthunya¹,

Maifadi²,

Mamba³

et al. 2018

Preprint

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“…P TDG sensors were laboratory‐calibrated prior to deployment by recording the output signal in an enclosed vessel filled with air and containing all sensors at a variety of known gas pressures that were set using a gas regulator fitted on a compressed air cylinder. The equilibration time for dissolved gases to diffuse across the silicon membrane and reach equilibrium depends on the surface area to volume ratio, gas permeability, and thickness of the silicon tubing (Manning et al 2003 ; D'Aoust 2007 ). Based on unpublished data, the equilibration time for the P TDG sensors used is approximately 20 min with an accuracy of ±5.0%.…”

Section: Methodsmentioning

confidence: 99%

In‐Well Degassing of Monitoring Wells Completed in Gas‐Charged Aquifers

Morais

Ryan

2022

Groundwater

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Total dissolved gas pressure (PTDG) measurements are useful to measure accurate in situ dissolved gas concentrations in groundwater, but challenged by in‐well degassing. Although in‐well degassing has been widely observed, its cause(s) are not clear. We investigated the mechanism(s) by which gas‐charged groundwater in a recently pumped well becomes degassed. Vertical PTDG and dissolved gas concentration profiles were monitored in the standing water column (SWC) of a groundwater well screened in a gas‐charged aquifer for 7 days before and 15 days after pumping. Prior to pumping, PTDG values remained relatively constant and below calculated bubbling pressure (PBUB) at all depths. In contrast, significant increases in PTDG were observed at all depths after pumping was initiated, as fresh groundwater with elevated in situ PTDG values was pumped through the well screen. After pumping ceased, PTDG values decreased to below PBUB at all depths over the 15‐day post‐pumping period, indicating well degassing was active over this time frame. Vertical profiles of estimated dissolved gas concentrations before and after pumping provided insight into the mechanism(s) by which in‐well degassing occurred in the SWC. During both monitoring periods, downward mixing of dominant atmospheric and/or tracer gases, and upwards mixing of dominant groundwater gases were observed in the SWC. The key mechanisms responsible for in‐well degassing were (i) bubble exsolution when PTDG exceeded PBUB as gas‐charged well water moves upwards in the SWC during recovery (i.e., hydraulic gradient driven convection), (ii) microadvection caused by the upward migration of bubbles under buoyancy, and (iii) long‐term, thermally driven vertical convection.

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“…The release of gases from the water body by bubbles is called ebullition. Bubbles can be formed and sustained, when gas pressure reaches absolute pressure (Figure 5; [8,63,64]). Such bubbles migrate toward the water surface due to their buoyancy.…”

Section: Ebullitionmentioning

confidence: 99%

Gas Pressure Dynamics in Small and Mid-Size Lakes

Boehrer

Jordan

Leng

et al. 2021

Water

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Dissolved gases produce a gas pressure. This gas pressure is the appropriate physical quantity for judging the possibility of bubble formation and hence it is central for understanding exchange of climate-relevant gases between (limnic) water and the atmosphere. The contribution of ebullition has widely been neglected in numerical simulations. We present measurements from six lacustrine waterbodies in Central Germany: including a natural lake, a drinking water reservoir, a mine pit lake, a sand excavation lake, a flooded quarry, and a small flooded lignite opencast, which has been heavily polluted. Seasonal changes of oxygen and temperature are complemented by numerical simulations of nitrogen and calculations of vapor pressure to quantify the contributions and their dynamics in lacustrine waters. In addition, accumulation of gases in monimolimnetic waters is demonstrated. We sum the partial pressures of the gases to yield a quantitative value for total gas pressure to reason which processes can force ebullition at which locations. In conclusion, only a small number of gases contribute decisively to gas pressure and hence can be crucial for bubble formation.

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Technical Note: Total Dissolved Gas Pressure (TDGP) Sensing in the Laboratory

Cited by 8 publications

References 11 publications

Spectroscopic Determination of Water Salinity in Brackish Surface Water in Nandoni Dam, at Vhembe District, Limpopo Province, South Africa <strong> </strong><strong> </strong>

Spectroscopic Determination of Water Salinity in Brackish Surface Water in Nandoni Dam, at Vhembe District, Limpopo Province, South Africa <strong> </strong><strong> </strong>

In‐Well Degassing of Monitoring Wells Completed in Gas‐Charged Aquifers

Gas Pressure Dynamics in Small and Mid-Size Lakes

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Technical Note: Total Dissolved Gas Pressure (TDGP) Sensing in the Laboratory

Cited by 8 publications

References 11 publications

Spectroscopic Determination of Water Salinity in Brackish Surface Water in Nandoni Dam, at Vhembe District, Limpopo Province, South Africa <strong>&nbsp;</strong><strong> </strong>

Spectroscopic Determination of Water Salinity in Brackish Surface Water in Nandoni Dam, at Vhembe District, Limpopo Province, South Africa <strong>&nbsp;</strong><strong> </strong>

In‐Well Degassing of Monitoring Wells Completed in Gas‐Charged Aquifers

Gas Pressure Dynamics in Small and Mid-Size Lakes

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Product

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Spectroscopic Determination of Water Salinity in Brackish Surface Water in Nandoni Dam, at Vhembe District, Limpopo Province, South Africa <strong> </strong><strong> </strong>

Spectroscopic Determination of Water Salinity in Brackish Surface Water in Nandoni Dam, at Vhembe District, Limpopo Province, South Africa <strong> </strong><strong> </strong>