Implications of CN Ratios from Two USGS Sediment Trap Samples Recovered from the Kaoping Canyon

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Implications of C/N Ratios from Two USGS Sediment
Trap Samples Recovered from the Kaoping Canyon
Saulwood Lin, Institute of Oceanography Natioanal
Taiwan University James Liu Institute of Marine
Geology and Chemistry National Sun-Yat-Sen
University
?International Sediment Trap Workshop? National
Sun Yat-sen University, Kaohsiung, Taiwan. March
23-27, 2009
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(Hedges et al., 1995)
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(Huh et al., 2007)
Dadson et al. (2003)
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Modes of SS transport

• Normal river plume
• Density flow

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Wet season
Annual rainfall
Dry season
From Taiwan Central Weather Bureau
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High frequency of typhoon invasion (4 per year)
Total 436 typhoons invaded Taiwan during 1897 to
2007
From Central Weather Bureau
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(Boutton et al., 1991)
( Kendall et al., 2001)
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Sediment Mooring
T6KP Winter (Dry) Season (January 10-March 20,
2008) T7KP Summer (Wet) Season (July 7-September
11, 2008)
(From J. Liu)
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USGS Sediment Trap
(From J. Liu)
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Samples from T7KP
(From J. Liu)
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Typhoon Invasion (July 7-Sept. 11, 2008)
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(From J. Liu)
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Objective

• To study particulate (TOC, TON, C/N ratio,
  ?13COrg) passing through the KP Canyon during wet
  and dry season,
• To delineate source(s) of particle transport
  through the KP canyon,
• To examine the effect of typhoon on types of
  organic carbon passing the canyon,
• To compare short event driven and seasonal
  variations on organic carbon deposition and
  transport.

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Analytical Method

• Grind sample
• Remove Carbonate
• (2N HCl for 8 hrs)
• Freeze dry
• (5 days)
• Elemental Analyzer
• (TOC, TON)
• C/N molar ratio

CHN Analyzer Thermo Flash 2000
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Problems may encounter using Elemental Analyzer
1. Sample Weight
2. Homogenized Sample
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T6KP Sediment Trap Dry Season
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T7KP Sediment Trap wet season
Sep 11, 2008
Aug 3, 2008
typhoon floods
Jul 13, 2008
Jul 8, 2008
(from CA Huh)
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T7KP Sediment Trap wet season
Typhoon Flood ?
Typhoon Flood
? Sand ? Clay Silt
(Grain size data from J Liu)
Plant Debris
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Summary . Particulate organic carbon, nitrogen
contents and grain sizes showed semi-cyclic
oscillation during dry season, while extreme
values were observed for wet season, . Distinct
C/N ratios are found for sediments collected
during dry and wet season . C/N ratios are
mostly marine in sediments collected during dry
season, probably a result of periodical
tide/current winnowing into the KP canyon . C/N
ratios fluctuate rapidly during wet season, but,
mostly terrigenous, a result of typhoon
event . Particular organic matter were carried
into the canyon during both season but
probably through different transport mechanism,
tide vs flood (hyperpycnal ?).
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Thanks for your attention Comments and
suggestions