Method for determination of density or relative density of liquefied petroleum gases and other light hydrocarbons by pressure hydrometer method

Estimates of the relative density of fishes form the basis of many marine ecological studies as well as the assessment of effects of fishing or pollution. Plasticity in the behavioural response of large reef fishes to SCUBA divers means that commonly used underwater visual census (UVC) techniques do not always provide reliable estimates of relative density. The paper describes the system configuration, deployment methods, testing and use of a remotely deployed baited underwater video (BUV) system for the survey of carnivorous reef fishes (snapper, Pagrus auratus and blue cod,Parapercis colias) in marine reserves of northern New Zealand. Concurrent UVC and BUV surveys inside and outside a marine reserve showed that, whereas UVC detected few snapper in either area (resulting in little confidence in statistically significant results), BUV demonstrated significant differences in relative density. Conversely, blue cod were found to occur at significantly higher densities within the reserve by UVC, but not by BUV. The provision of accurate estimates of fish size (<20 mm error) from video footage also illustrated differences in size structure between protected and fished populations. The data suggest that a combination of survey techniques is likely to be necessary where multispecies assemblages are being assessed.

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Ethylene production in apple infected by Gleosporium album Ostrw. at cold storage

Horticultural Science ◽

10.17221/3732-hortsci ◽

2011 ◽

Vol 33 (No. 1) ◽

pp. 1-6

Author(s):

J. Goliáš ◽

A. Němcová ◽

P. Mýlová

Keyword(s):

Cold Storage ◽

Ethylene Production ◽

Canonical Correlation ◽

Storage Temperature ◽

Apple Fruit ◽

Gas Analysis ◽

Light Hydrocarbons ◽

High Affinity ◽

Headspace Gas

In ten cultivars of apple fruit, ethylene production expressed in μl/kg/h was determined. The cultivar Resista exhibited a higher ethylene production and can be differentiated from other cultivars. The production ranged from 4.2 ± 0.58 μl/kg/h in the case of Meteor cv. up to 131.6 ± 5.5 μl/kg/h in Resista cv. Infected fruit of Topaz cv. had a lower ethylene production at cold storage temperature (3°C) than some healthy fruit. All examined cultivars can be divided into three clusters. Discriminant analysis and canonical correlation analysis of the examined apple fruit led to the determination of healthy and infected fruit. Values of ethylene production were analyzed on intact fruit by using headspace gas analysis by CGC with thermal desorption technique. Carbosieve G was chosen as the adsorbent material for the traps due to its relatively high affinity for light hydrocarbons such as ethylene. For a full trap of ethylene in the enrichment column the sufficient amount of percolating gas is about 0.3 l.  

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