Gas seep induced interstitial water circulation: observations and environmental implications

1995 ◽  
Vol 15 (8) ◽  
pp. 931-948 ◽  
Author(s):  
S.C.M. O'Hara ◽  
P.R. Dando ◽  
U. Schuster ◽  
A. Bennis ◽  
J.D. Boyle ◽  
...  
Keyword(s):  
Interstitial Water ◽  
Water Circulation ◽  
Environmental Implications

scholarly journals The effects of methane seepage at an intertidal/shallow subtidal site on the shore of the Kattegat, Vendsyssel, Denmark

1994 ◽  
Vol 41 ◽  
pp. 65-79
Author(s):  
P. R. Dando ◽  
S. C. M. O'Hara ◽  
S. J. Niven ◽  
U. Schuster ◽  
L. J. Taylor ◽  
...  
Keyword(s):  
Hydrogen Sulphide ◽  
Gas Flow ◽  
Interstitial Water ◽  
Nematode Species ◽  
Water Circulation ◽  
Oxidation Rates ◽  
Methane Seepage ◽  
Sulphide Concentration ◽  
Gas Seepage ◽  
Shallow Subtidal

The effects of methane gas seepage were studied at an intertidal/shallow subtidal site on the Kattegat coast of Denmark. A 30 m wide zone, containing approximately 65 gas seeps, extended over 70 m seawards from the shore. This was characterised by the presence of slabs, pavement and small pillars of carbonate-cemented sandstone which formed a partially buried reef. The escaping gas contained 91-100% methane with some carbon dioxide, 0.6--0.9%, and hydrogen sulphide. The hydrogen sulphide concentration varied over time and between individual seeps. Gas flow rates of individual seeps ranged up to 211 h-1 and the estimated total flow was 110 I h-1• Seeps were often stopped by sand movement, but the overall gas flow from the site appeared to be constant. The escaping gas generated an interstitial water circulation and drew overlying seawater into the sediment. Water pumped out by the seeps was enriched in phosphate and ammonia. Sulphate reduction rates in the seep area were 1.1-17.1 m moles sulphate reduced and aerobic methane oxidation rates were 0.2 - 5.5 m moles methane consumed m-2 day-1• The composition of the flora and fauna surrounding the seeps was affected by the presence of hard substrate (the cemented sandstone). Epifauna was more abundant in the seep zone than else­where, whereas the macrobenthic infauna was reduced in the seep zone, possibly due to the cementation. The sediment was almost devoid of meiobenthic organisms, except nematodes. Nematode species numbers, abundance and biomass were lower at the seeps than 5-20 cm away. The nematode fauna penetrated deeper into the sediment close to the seeps than at the seeps themselves. This is explained by the interstitial water circulation at and close to the seeps. 14C measurements showed that little methane carbon was entering the food web surrounding the seeps.

ANALYSIS OF WATER CIRCULATION IN BOILERS UNDER STEADY-STATE CONDITIONS

2011 ◽  
Vol 3 (4) ◽  
pp. 261-275
Author(s):  
Syed-Ahmad M. Said ◽  
Mohamed A. Habib ◽  
Hassan M. Badr ◽  
R. Ben-Mansour ◽  
S. Al-Anizi
Keyword(s):  
Steady State ◽  
Water Circulation

Structural Transformation of Punjab Agriculture and its Environmental Implications

2020 ◽  
pp. 533-546
Keyword(s):  
Structural Transformation ◽  
Diversity Index ◽  
Green Revolution ◽  
Agricultural Practices ◽  
Secondary Data ◽  
Cropping Pattern ◽  
Environmental Implications ◽  
Question Mark ◽  
Sustainability Issue ◽  
Economic Survey

As per Economic Survey of Punjab, (2019-20), Punjab alone contributed more than 1/4 and 1/3 of the central pool of rice and th rd wheat respectively in 2018-19 and accordingly named as bread-basket of India. However, such a huge contribution was due to the structural transformation of agriculture in Punjab under the Green Revolution. Such transformation leads to intensive use of natural resources with mono-culture of wheat-paddy till today, which put a big question mark on the sustainability issue of agriculture in Punjab. The present study was exclusively based on secondary data, covering the period of 1965-66 to 2018-2019, almost 55 years. Hirschman Herfindhal index and Simpson Diversity index were used to determine the extent of concentration and diversification in the cropping pattern of Punjab agriculture. The results highlight the facts that level of diversification was declining and the level of concentration was increasing. Moreover, Compound Growth Rate (CGR) of yield was either stagnating or declining over the years. Not only this, based on the index of agriculture production, the trend values were negative since the 21 century. Accordingly, st intensive agricultural practices should be stopped, and diversification should get priority in such a way that food security is not jeopardized.

ELEMENTS DISTRIBUTION OF THE DENGJIA LOESS SECTION, CENTRAL HENAN AND ITS ENVIRONMENTAL IMPLICATIONS

2011 ◽  
Vol 31 (2) ◽  
pp. 129-134
Author(s):  
Ruixia YANG ◽  
Zhifei LI ◽  
Li ZHANG ◽  
Peng LU ◽  
Hongli GAO
Keyword(s):  
Environmental Implications
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