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Table 6

Potential resuspension eventsa at OC26 identified from two traps deployed at 30 mab and 120 mab. DOI: https://doi.org/10.1525/elementa.285.t6

EventEvent timingTrap period and characteristicsSupporting evidenceComments

 
Large-scale resuspension: Hurricane Isaac 28 Aug–2 Sept 2012 21 Aug–8 Sept 2012 (cup 4); LSiupper << LSilower; POC:DWupper = 3.3; POC:DWlower = 3.0; δ34Supper = 15.5‰; δ34Slower = 15.4‰ High current speeds, especially at M2, 3, 4 and ADCP; high particle concentrations at 108 mab, as seen in ADCP; peak sinking velocities of very small particles on 2 Sept (flux camera); δ34Supper = δ34Slower Hurricane Isaac caused high deep currents at the site on 28 Aug, making landfall on 29 Aug; water pushed back from shore gives a second signal at the site, 31 Aug to 2 Sept. Both events caused large-scale resuspension reaching to above 120 mab, impacting both traps, with more material entering the lower trap, suggesting most resuspended material came from below. 
Small-scale resuspension 12–14 Sept 2012 8–29 Sept 2012 (cup 1, 2nd deployment); no δ34S data High current speeds, specifically at M3, M4; changes in BNL at PC3–PC5 Rapid changes were observed in the BNL: thickening of the BNL, changes in particle size distribution, initial increase in particle concentration followed by decrease associated with the increase in deep current speeds. 
Far-field, small-scale resuspension/BNL Nov–Dec 2012 21 Nov–8 Dec 2012 (cup 5); LSiupper >>LSilower; POC:DWupper = 2.2; POC:DWlower = 4.4 Current speeds at M3 low, <10 cm s–1; no δ34S data This type of signal may best be explained by resuspension on higher lying slopes, with the formation of a deep nepheloid layer carrying resuspended material into the upper but not lower trap. 
Far-field, small-scale resuspension Mar 2013 5–22 Mar 2013 (cup 11);LSiupper << LSilower; POC:DWupper = 3.7; POC:DWlower = 5.8 Current speeds at M3 elevated, >20 cm s–1; δ34Supper = 15.8‰;δ34Slower = 17.2‰ Same as above 
Far-field, small-scale resuspension/BNL May 2013 13–31 May 2013 (cup 15); LSiupper >>LSilower; POC:DWupper = 2.8; POC:DWlower = 4.6 Current speeds at M3 low, <10 cm s–1; no δ34S data Same as above 
Local small-scale resuspension June–July 2013 17 Jun–4 Jul 2013 (cup 17); LSiupper << LSilower; POC:DWupper = 4.5; POC:DWlower = 3.1 Current speeds at M3 elevated, >10 cm s–1; no δ34S data Resuspended material only entered lower trap, suggesting the nepheloid layer to be between 30 and 120 mab. 
EventEvent timingTrap period and characteristicsSupporting evidenceComments

 
Large-scale resuspension: Hurricane Isaac 28 Aug–2 Sept 2012 21 Aug–8 Sept 2012 (cup 4); LSiupper << LSilower; POC:DWupper = 3.3; POC:DWlower = 3.0; δ34Supper = 15.5‰; δ34Slower = 15.4‰ High current speeds, especially at M2, 3, 4 and ADCP; high particle concentrations at 108 mab, as seen in ADCP; peak sinking velocities of very small particles on 2 Sept (flux camera); δ34Supper = δ34Slower Hurricane Isaac caused high deep currents at the site on 28 Aug, making landfall on 29 Aug; water pushed back from shore gives a second signal at the site, 31 Aug to 2 Sept. Both events caused large-scale resuspension reaching to above 120 mab, impacting both traps, with more material entering the lower trap, suggesting most resuspended material came from below. 
Small-scale resuspension 12–14 Sept 2012 8–29 Sept 2012 (cup 1, 2nd deployment); no δ34S data High current speeds, specifically at M3, M4; changes in BNL at PC3–PC5 Rapid changes were observed in the BNL: thickening of the BNL, changes in particle size distribution, initial increase in particle concentration followed by decrease associated with the increase in deep current speeds. 
Far-field, small-scale resuspension/BNL Nov–Dec 2012 21 Nov–8 Dec 2012 (cup 5); LSiupper >>LSilower; POC:DWupper = 2.2; POC:DWlower = 4.4 Current speeds at M3 low, <10 cm s–1; no δ34S data This type of signal may best be explained by resuspension on higher lying slopes, with the formation of a deep nepheloid layer carrying resuspended material into the upper but not lower trap. 
Far-field, small-scale resuspension Mar 2013 5–22 Mar 2013 (cup 11);LSiupper << LSilower; POC:DWupper = 3.7; POC:DWlower = 5.8 Current speeds at M3 elevated, >20 cm s–1; δ34Supper = 15.8‰;δ34Slower = 17.2‰ Same as above 
Far-field, small-scale resuspension/BNL May 2013 13–31 May 2013 (cup 15); LSiupper >>LSilower; POC:DWupper = 2.8; POC:DWlower = 4.6 Current speeds at M3 low, <10 cm s–1; no δ34S data Same as above 
Local small-scale resuspension June–July 2013 17 Jun–4 Jul 2013 (cup 17); LSiupper << LSilower; POC:DWupper = 4.5; POC:DWlower = 3.1 Current speeds at M3 elevated, >10 cm s–1; no δ34S data Resuspended material only entered lower trap, suggesting the nepheloid layer to be between 30 and 120 mab. 

a A significant difference in LSi flux between the two traps (smallest deviation > 95 mg m–2 d–1) and a POC:DW ratio ≤3.3 in at least one trap (Figure 8) was interpreted as an indicator of resuspension.

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