Resurrecting vintage paper seismic records

Marine seismic data has been collected for several decades in both academia and industry. Early single channel acquisitions were often, if at all, recorded on magnetic media that are generally no longer supported for replay. Although seismic data over 10 years old has limited quality compared to modern acquisition, thousands of survey km of hard copy records remains world wide in areas with no recent coverage. In addition, many processed multi-channel datasets are now not available as digital files for a variety of reasons. Rising interest in continental margin geology in response to climate change priorities and the UNCLOS submission requirements of maritime states has created a demand to re-use these older records where the cost of new or re-acquisition is not pragmatic. Through creating digital SEG-Y files from images of these records they can be reprocessed and re-interpreted. This paper investigates the practicalities of paper seismic record re-use and measures the performance of a typical conversion option as an indicator of the validity of the concept. Examples of applications of the process illustrate what can be achieved and the limitations that exist so that users can make an informed choice of whether to resurrect their information.     

The role of oxyradicals in intracellular proteolysis and toxicity in mussels

Studies were performed on the common mussel, M. edulis L., to determine whether copper (Cu) exposure can affect the extent to which digestive cell proteins are oxidised and whether such oxidative damage is mediated by free radicals. Three age groups of mussels were exposed for 6 ^-days to environmentally realistic concentrations of Cu and then digestive gland homogenates were examined for evidence of protein carbonyl formation. Significant increases in carbonyls relative to untreated control mussels were seen for the youngest (2–4 year-old) and oldest (≥ 10 year-old) mussels only after exposure for 6 days, followed by recovery from exposure for a further 6 days. Untreated mussels also showed an age-related difference in protein oxidation, with a significantly lower concentration in the youngest animals (2–4 year olds). Copper did not affect the levels of modified tryptophan or tyrosine residues or the extent of total lipid peroxidation in digestive gland homogenate. Significant depletion of total vitamin E (a-tocopherol) was seen only in young and medium-aged mussels following exposure for 6 days. The levels of protein carbonyl groups were increased in digestive cell cytosol and lighter lysosomes but not in heavier lysosomes or digestive gland microsomes following 5 days exposure to Cu. Dihydrohodamine-123 was converted to fluorescent rhodamine-123 following sequestration into digestive cell lysosomes. The results suggest a link between the lysosomal sequestration of copper, a concomitant increase in the production of oxyradicals and the potential for intracellular oxidative damage, as well as an increased capacity for oxidative damage in older animals.     

THE USE OF AIRBORNE AUXILIARY DATA IN THE RIGOROUS LEAST SQUARES ADJUSTMENT OF A BLOCK OF AERIAL TRIANGULATION

The problem of incorporating airborne auxiliary data into an aerial triangulation block adjustment is considered. The conclusion is reached that this problem can be most readily solved by the use of a fully rigorous adjustment method. The first order adjustment equations for all types of airborne auxiliary control are developed and the method of incorporating these equations into the block solution is demonstrated. The general computing problems of the aerial triangulation block adjustment are briefly discussed and a method outlined for the incorporation of tie strips, at any angle across the block, into the adjustment without unduly increasing the storage requirements for the solution. The problem of correctly weighting the different types of available data is discussed. The paper concludes with a demonstration of the improved accuracy possible if precise aerial triangulation data are combined with apparently crude absolute airborne data.     

Variation in sunscreen compounds (mycosporine‐like amino acids) for marine species along a gradient of ultraviolet radiation transmission within doubtful sound,New Zealand

We examined the response of four species of New Zealand marine algae (Ecklonia radiata, Apophlaea lyallii, Rhodymenia spp., Ulva lactuca) and a sea urchin (Evechinus chloroticus) to spatial variation in ultraviolet radiation (UV‐R) by examining the concentration of UV‐R absorbing compounds known as mycosporine‐like amino acids (MAAs). The purpose was to understand how, and the degree to which, local marine species could potentially respond to any future increases in incident UV‐R in the New Zealand marine environment. The research was undertaken in Doubtful Sound, where we observed a gradient of water column UV‐R transmission along the 40 km length of the fiord. We examined spatial differences in MAAs along the UV‐B gradient in the macrophytes and temporal changes in MAAs in sea urchin gonads. Among the algae, thallus MAA concentrations (nmol mg^–1 protein) ranged from 12.5 to 87.8 in E. radiata, from 433.1 to 1446.4 in A. lyallii, 12.7 to 103.4 in Rhodymenia spp., but were not detected in U. lactuca. For E. chloroticus, gonadal MAA concentrations ranged from 83.9 to 224.3 nmol mg^–1 protein spatially, and over the year from 1.85 to 14.12 nmol mg^–1 dry weight (DW) depending on site and gametogenic cycle. Laboratory manipulations indicated that concentrations of MAAs in E. chloroticus gonads and eggs are influenced by diet. MAA concentration could be correlated with UV‐B intensities in two of the algal species. E. chloroticus MAA concentrations could also be correlated with UV‐B transmission, which we concluded was a reflection of the greater ingestion and accumulation of MAA‐rich macrophytes at those sites where higher ambient UV‐R induced greater MAA concentrations to occur in the algae. Given this, we suggest that one response of marine species to increases in UV‐B would be an increase in the synthesis and/or accumulation of MAAs for photoautotrophs and a dietary accumulation of those MAAs in E. chloroticus, an important herbivore in this system.