Quantification of methane bubbles in shallow freshwaters using horizontal hydroacoustical observations

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985858%3A_____%2F15%3A00443155" target="_blank" >RIV/67985858:_____/15:00443155 - isvavai.cz</a>

Nalezeny alternativní kódy

RIV/60077344:_____/15:00443155

Výsledek na webu

<a href="http://dx.doi.org/10.1002/lom3.10051" target="_blank" >http://dx.doi.org/10.1002/lom3.10051</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1002/lom3.10051" target="_blank" >10.1002/lom3.10051</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Quantification of methane bubbles in shallow freshwaters using horizontal hydroacoustical observations

Popis výsledku v původním jazyce

Methane represents an important greenhouse gas, and its ebullition is a significant method of releasing the gas from bottom sediments of shallow waters to the atmosphere. Detecting methane bubbles is complicated because of high spatiotemporal variability; however, hydroacoustical surveys represent an effective method for quantifying ebullitive emissions. Vertical and horizontal hydroacoustical observations performed in shallow waters are presented in this work, with an emphasis on horizontal observations. Bubbles of various sizes, ranging from 2.5 to 907.2 μl, were artificially prepared using a bubble generator and released from a depth of 6 m in a freshwater lake. The acoustic target strength (TS) of these bubbles was observed using both the vertical and horizontal beams of 120-kHz frequency sonar. The recorded TS of the bubbles in vertical mode varied from -61 dB to -43 dB. These values were significantly stronger than those of the bubbles observed in horizontal mode, which ranged from 62 dB to -48 dB. The TS obtained in both the vertical and horizontal modes increased with increasing bubble size. Additionally, the TS of the smallest sizes in vertical mode increased as the bubbles rose to the surface. For other sizes of bubbles and in horizontal mode, the bubble TS either decreased or did not change significantly when the bubbles traveled upwards. Based on these results, we suggest elimination of the depth correction for volume in studying methane bubbles in shallow waters. Furthermore, we developed equations that can determine bubble volume from bubble TS in both the vertical and horizontal planes.

Název v anglickém jazyce

Quantification of methane bubbles in shallow freshwaters using horizontal hydroacoustical observations

Popis výsledku anglicky

Methane represents an important greenhouse gas, and its ebullition is a significant method of releasing the gas from bottom sediments of shallow waters to the atmosphere. Detecting methane bubbles is complicated because of high spatiotemporal variability; however, hydroacoustical surveys represent an effective method for quantifying ebullitive emissions. Vertical and horizontal hydroacoustical observations performed in shallow waters are presented in this work, with an emphasis on horizontal observations. Bubbles of various sizes, ranging from 2.5 to 907.2 μl, were artificially prepared using a bubble generator and released from a depth of 6 m in a freshwater lake. The acoustic target strength (TS) of these bubbles was observed using both the vertical and horizontal beams of 120-kHz frequency sonar. The recorded TS of the bubbles in vertical mode varied from -61 dB to -43 dB. These values were significantly stronger than those of the bubbles observed in horizontal mode, which ranged from 62 dB to -48 dB. The TS obtained in both the vertical and horizontal modes increased with increasing bubble size. Additionally, the TS of the smallest sizes in vertical mode increased as the bubbles rose to the surface. For other sizes of bubbles and in horizontal mode, the bubble TS either decreased or did not change significantly when the bubbles traveled upwards. Based on these results, we suggest elimination of the depth correction for volume in studying methane bubbles in shallow waters. Furthermore, we developed equations that can determine bubble volume from bubble TS in both the vertical and horizontal planes.

Druh

J_x - Nezařazeno - Článek v odborném periodiku (Jimp, Jsc a Jost)

CEP obor

DA - Hydrologie a limnologie

OECD FORD obor

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Projekt

<a href="/cs/project/GAP504%2F12%2F1186" target="_blank" >GAP504/12/1186: Hydroakustické rozlišení ryb od bublin a kvantifikace emisí metanových bublin z přehrad mírného pásma</a><br>

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2015

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

LIMNOLOGY AND OCEANOGRAPHY-METHODS

ISSN

1541-5856

e-ISSN

—

Svazek periodika

13

Číslo periodika v rámci svazku

11

Stát vydavatele periodika

US - Spojené státy americké

Počet stran výsledku

8

Strana od-do

609-616

Kód UT WoS článku

000367227000002

EID výsledku v databázi Scopus

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