An improved oxygen method for measuring primary production in lakes

Tschumi, Pascal; Zbären, D.; Zbären, J.

doi:10.1080/03680770.1977.11896483

Cited by 1 publication

(3 citation statements)

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“…somewhat higher than for the initial samples. This is to be expected because uneven distribution of detritus and respiring organisms introduces additional variation in the final oxygen content, something that Tschumi et al (1977) also have noted.…”

Section: Manual Vs Automatic Titrationmentioning

confidence: 71%

“…This result is contrary to statements by Cornett and Rigler (1986). All bottles (even with Winkler reagents added) were stored under water (Tschumi et al 1977, Anonymous 1987) at a temperature close to the original temperature of the water which was siphoned into the bottles. If bottles are stored in air at a lower temperature, gas bubbles may form under the stopper, and erroneous values will result.…”

Section: Manual Vs Automatic Titrationmentioning

confidence: 99%

“…The smallest significant difference between two sets of n samples, assuming normal distribution and using a onetailed Student's t-test, will be: (Tschumi et al 1977), where SD is the standard deviation of the oxygen analysis for n replicate bottles, t the Student's distribution, and k a factor for small n values. If n = 3 for both initial and incubated bottles, k= 1.128 and t= 2.1318 (p = 0.05).…”

Section: Manual Vs Automatic Titrationmentioning

confidence: 99%

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Automatic potentiometric determination of dissolved oxygen

Granéli

1991

Mar. Biol.

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Abstract. Commercially available automatic titration systems were tested in 1988 for potentiometric titration of liberated iodine by the Winkler method of oxygen determination. The potentiometric equivalence point was also compared to the manual starch end point. Finally the automatic method was used in order to estimate belowhalocline respiration in the Kattegat, Sweden. Standard deviations of 0.007 ml Oz 1-1 or 0.1 to 0.3% coefficients of variation (% standard deviation of the mean) were achieved when titrating 25 ml from replicate 60-ml oxygen bottles using the automatic method, or 50 ml manually. The precision for replicate titrations of 50-ml aliquots of 0.001 N K I O 3 was <0.05% (0.002 ml 0.01 N Na2SzOa) for the automatic method. Titration time for 25-ml aliquots was 2 to 4 min, somewhat longer than for manual titrations (1 to 1.5 rain). However, during titration the operator is free to perform other tasks. It is not possible to use automatic sample changers, due to rapid iodine volatilization. The equipment can be handled by relatively unskilled analysts and is suitable for use on board research vessels or in field stations [weight for a Mettler TM titrator (Mettler Instrumente AG, Greifensee, Switzerland) < 10 kg, volume <0.1 m3]. Below-halocline oxygen consumption in the SE Kattegat ranged from 0 to 6 ml Oz m -3 h-1 (mean values for September and October 1988=1.69 and 0.66ml O2m -3 h -1, respectively, with 95% confidence limits of ca. +0.6 ml 02 m -3 h-~).

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Section: Manual Vs Automatic Titrationmentioning

confidence: 71%

Section: Manual Vs Automatic Titrationmentioning

confidence: 99%

Section: Manual Vs Automatic Titrationmentioning

confidence: 99%

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