Maturity Stages (maturity + stage)

Distribution by Scientific Domains


Selected Abstracts


Effect of Maturity Stages and Drying Methods on the Retention of Selected Nutrients and Phytochemicals in Bitter Melon (Momordica charantia) Leaf

JOURNAL OF FOOD SCIENCE, Issue 6 2009
Min Zhang
ABSTRACT:, The purpose of this study was to investigate the nutrient and phytochemical composition of bitter melon leaves under varying maturity levels and drying techniques. Fresh, oven-dried, and freeze-dried leaves were evaluated over 3 maturity stages. In fresh leaves at various stages, crude fat, crude protein, and soluble dietary fiber contents ranged from 4.2% to 13.6%, 6.4% to 23.1%, and 0.04% to 3.50% on dry-weight basis, respectively. The contents of K, Ca, Mg, Fe, and Zn ranged from 1850.8 to 2811.8, 837.4 to 4978.2, 317.3 to 512.4, 8.4 to 16.7, and 4.1 to 5.9 mg/100 g dry-weight basis, respectively. Vitamin C, ,-carotene, and lutein contents ranged from 397.4 to 1275.1, 154.2 to 422.8, and 737.6 to 1304.6 ,g/g dry-weight basis. The major flavonoids and phenolic acids were rutin, gentistic acid, and,o -coumaric acid, which ranged from 7.57 to 12.75, 2.53 to 10.11, and 4.24 to 9.75 mg/g dry-weight basis, respectively. In oven-dried samples, 40.2% to 52.3% of vitamin C, 35.4% to 55.4% of ,-carotene, 25.6% to 71.6% of lutein, 26.4% to 84.0% of rutin, trace to 11.4% of gentistic acid, and 7.4% to 46.6% of,o -coumaric acid were retained, while the retainment ratios of these components in freeze-dried samples were 84.7% to 99.0%, 76.4% to 99.3%, 90.4% to 96.1%, 39.8% to 99.3%, 24.1% to 68.4%, and 75.8% to 87.0%, respectively. The data showed that freeze-drying better preserves the nutrient and phytochemical quality of bitter melon leaves in comparison to oven-drying. Bitter melon leaf is a rich source of selected nutrients and phytochemicals. [source]


Rheological properties of Josapine pineapple juice at different stages of maturity

INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 4 2009
Rosnah Shamsudin
Summary The rheological behaviour of Josapine pineapple juice with at various maturity stages was studied at a wide range of temperature (5,65 °C) and concentration (4,14 °Brix) using a rotational rheometer as the measuring system. The results show that josapine pineapples juice demonstrated a Newtonian behavior and is influenced by maturity stage, temperature and concentration. The Arrhenius typed equation successfully describe the effect of temperature on the viscosity, on the other hand, the effect of concentration can be described better using exponential equation. Finally, an equation describing the combined effect of temperature and concentration on viscosity at different stages of maturity was successfully developed. [source]


Blood cell profile of six Mediterranean mariculture fish species

JOURNAL OF APPLIED ICHTHYOLOGY, Issue 1 2007
M. Pavlidis
Summary The haematological profile and a description of the cell types from the peripheral blood of six Mediterranean fish species are presented. The highest haematocrit value was recorded in the saupe, Sarpa salpa (P < 0.001), the only herbivorous species, and which also lacked monocyte cells. Eosinophils were absent from the blood of the European sea bass Dicentrarchus labrax. White sea bream, Diplodus sargus and gilthead sea bream, Sparus aurata had statistically significantly high numbers of neutrophils and low numbers of lymphocytes (P < 0.001). The numbers of different leucocyte cell types were not influenced by sex or maturity stage in any species, although some variation in the maximum diameter of the cells was observed. [source]


The biology of the bigeye grenadier at South Georgia

JOURNAL OF FISH BIOLOGY, Issue 6 2004
S. A. Morley
The biology of the bigeye grenadier Macrourus holotrachys caught as by-catch in the Patagonian toothfish Dissostichus eleginoides longline fishery conducted around South Georgia was investigated to improve data available for fisheries management. Age estimates suggest that M. holotrachys is a moderately slow growing species (K = 0·10), reaching ages of >30 years and attaining total lengths (LT) >80 cm (L, = 33). The size at which 50% of females had started to mature (Lint50) for M. holotrachys was 21 cm pre-anal length (LPA) and occurred at c. 9 years old. Estimates of natural mortality and Pauly's growth performance index were found to be low (M = 0·09 and , = 2·82 respectively). Gonad maturity stage was described from macroscopic and histological investigation. Mature ovaries had oocytes at all developmental stages with between 22 and 55% likely to be spawned each year. Absolute fecundity ranged from 22 000 to 260 000 eggs and was positively correlated with both pre-anal length and mass. A highly skewed sex ratio of 32 : 1, females : males, was found for specimens caught by longlines but not for a small sample of shallower trawl-caught specimens. It is suggested that females are far more susceptible to longline capture than males. Macrourus holotrachys is a bentho-pelagic predator and scavenger that feeds on a wide range of fishes and invertebrates. The fish are long lived, slow-growing species typical of deep-water grenadiers; fisheries management strategies should reflect their probable susceptibility to overfishing. [source]


PHYSICOCHEMICAL AND FLAVOR CHANGES OF FRAGRANT BANANA (MUSA ACUMINATA AAA GROUP "GROSS MICHEL") DURING RIPENING

JOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 3 2010
SOMRUEDEE THAIPHANIT
ABSTRACT The objective of this research was to characterize the physicochemical and flavor changes that occur in ripe Hom Thong (Musa acuminata AAA Group "Gross Michel") flesh at stage 6,8. It was found that the higher fresh maturity stage of Hom Thong at P < 0.05 has the following results: the antioxidant activities, moisture content and reducing sugar are significantly increased. The titratable acidity, total soluble solid and prebiotic activities' score for Lactobacillus acidophilus LA5 and Bifidobacterium lactis BB-12 are significantly decreased. The total dietary fiber remains unchanged. Using headspace solid-phase microextraction and gas chromatography,mass spectrometry to characterize volatile compound found that the flavor 20 volatile compounds (11 esters, 5 alcohols, 3 carbonyls and 1 ketone) are varied on Hom Thong maturity stage. The compounds with the most aroma impact for ripe Hom Thong flesh at stage 6,8 were 3-methylbutyl butanoate, 3-methyl-1-butyl acetate, 3-methylbutyl 3-methylbutanoate and 2-methylpropyl ethanoate. PRACTICAL APPLICATIONS Ripe banana Musa acuminata, AAA Group "Gross Michel," locally known in Thailand as Hom Thong, is a popular food item consumed as fruit, snacks or food ingredients for confections, spreads and other banana products. Using a suitable ripening stage of the banana flesh is the most critical step among many steps of unit operations for achieving high-quality banana products. This study not only characterizes the physicochemical and flavor changes that occur in ripe Hom Thong flesh at stage 6,8, but also studies antioxidant activities and prebiotic activities. Manufacturers can utilize the data presented in this article to select the suitable ripening stage in order to avoid product failure and to produce the best quality products for functional food, pharmafood, medifood or vitafood that are rich in natural banana flavor. [source]


Influence of agricultural practices on the quality of sweet pepper fruits as affected by the maturity stage

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 11 2007
Antonio José Pérez-López
Abstract Background: Peppers are popular vegetables because of their colour, taste and nutritional value. The levels of vitamin C, carotenoids and phenolic compounds in peppers and other vegetables depend on several factors, including cultivar, agricultural practice and maturity stage. Results: In this study the effects of maturation and type of agricultural practice (organic or conventional) on the ascorbic acid, total carotenoid and total phenolic contents and colour parameters of sweet peppers (Capsicum annuum cv. Almuden) grown in a controlled greenhouse were determined. Levels of vitamin C, phenolic compounds and carotenoids increased during ripening, with red sweet peppers having higher contents of these bioactive compounds. Moreover, peppers grown under organic culture had higher vitamin C, phenolic and carotenoid levels than those grown under conventional culture. With respect to colour parameters, organic red peppers had higher values of L*, a*, b*, C* and Hab than conventional red peppers, giving them a higher intensity of red colour. Conclusion: Thus organic farming had a positive effect on the nutritional content of peppers, increasing the vitamin C activity and the level of phenolic compounds, both implicated in the antioxidant activity of vegetables, and the content of carotenoids, implicated in the colour variance observed in pepper fruits. Copyright © 2007 Society of Chemical Industry [source]


Validation of macroscopic maturity stages according to microscopic histological examination for European anchovy

MARINE ECOLOGY, Issue 2009
Rosalia Ferreri
Abstract The identification and classification of macroscopic maturity stages plays a key role in the assessment of small pelagic fishery resources. The main scientific international commissions strongly recommend standardizing methodologies across countries and scientists. Unfortunately, there is still a great deal of uncertainty concerning macroscopic identification, which remains to be validated. The current paper analyses reproductive data of European anchovy (Engraulis encrasicolus L. 1758), collected during three summer surveys (2001, 2005 and 2006) in the Strait of Sicily, to evaluate the uncertainty in the macroscopic maturity stage identification and the reliability of the macroscopic adopted scale. On board the survey vessels, the maturity stage of each fish was determined macroscopically by means of an adopted maturity scale subdivided in six stages. Later, at the laboratory, the gonads were prepared for histological examination. The histological slides were analysed, finally assigning the six maturity stages for macroscopic examinations. A correspondence table was obtained with the proportion and number of matches between the two methods. The results highlight critical aspects in the ascription of macroscopic maturity stages, particularly for the present research aim. Different recommendations were evaluated depending on the scope of the study conducted on maturity (e.g. daily egg production, fecundity and maturity ogive computation). The most interesting results concern the misclassification of stage IV and stages III and V (the most abundant), which confirms their macroscopic similarity. Although the results are based on a small number of samples, the advantages and disadvantages of macroscopic and histological methods are discussed with the aim to increase the accuracy of correct identification and to standardize macroscopic maturity ascription criteria. [source]


How can the feeding habits of the sand tiger shark influence the success of conservation programs?

ANIMAL CONSERVATION, Issue 4 2009
L. O. Lucifora
Abstract The feeding habits of the sand tiger shark Carcharias taurus, one of the most threatened sharks of the world, are poorly known. Sand tiger sharks are critically endangered in the South-west Atlantic. Since 2007, the law requires that all individuals caught in recreational fisheries off Argentina must be released. Using data from a north Patagonian recreational fishery (n=164 stomachs with contents), we analyzed the diet of sand tiger sharks in relation with size, sex, maturity stage and season; assessed prey consumption patterns and hooking location; and estimated diet overlap with fishery landings. Sand tiger sharks consumed mainly teleosts (55.4% of the total prey number, N) and elasmobranchs (41.84%N), and ate more benthic elasmobranchs (batoids and angel sharks) as they become larger. Sharks swallowed prey mostly in one piece (93.7%) and were hooked mainly in internal organs (87.4%, n=175), causing occlusion and perforation of the esophagus and stomach, and lacerations to the pericardium, heart and liver. Sand tiger sharks fed on the most heavily landed species, overlapping almost completely (>90%) with fishery landings. Conservation plans should take into account that releasing hooked sharks could be insufficient to minimize fishing mortality and that competition for food with fisheries is likely to occur. [source]


Applicability of Carbazole Migration Indices in Continental Rift Basins: A Case Study of Western Lujiapu Depression in Kailu Basin, NE China

ACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 3 2010
Shuqing ZHOU
Abstract: Kailu Basin in which the Western Lujiapu Depression is located is a typical continental rift basin. Biomarker parameters of the oils indicate that depositional facies and environments vary between the Bao 1 and Bao 14 fault blocks with a higher saline environment in the Bao 1 fault block, but such difference has no significant impact on carbazole abundance and distribution. Maturity and migration distance are the main controls on carbazole abundance and distribution in the Western Lujiapu Depression. The commonly used migration indices, such as ratios of nitrogen shield isomers to nitrogen exposed isomers (1-/4-methylcarbazole ratio, 1,8-/2,4-dimethylcarbazole (DMC) ratio and half-shield/exposed-DMC ratio), absolute concentrations of alkylated carbazoles and BC ratio (= benzo [a]carbazole/ (benzo[a]carbazole + benzo[c]carbazole)) increase at the low mature range and decrease at a higher mature range with increasing maturity. At relatively low maturity stage (Rc<0.77%), maturation has reversal effects with migration on the ratios of nitrogen shield isomers to nitrogen exposed isomers, which may cover migration influence and makes these parameters fail to indicate migration effects. Valid migration indicators at this maturity stage are concentrations of alkylated carbazoles and BC ratios, which can provide ideal tools for migration direction assessment even within short migration distance. Maturity effects should be taken into account when carbazole compounds are applied to indicate migration direction, and at different maturity stages, these commonly used parameters have different validity in tracing migration direction. Coupled with our previous study in the Eastern Lujiapu Depression, a conceptual model of the variation of nitrogen migration indices can be established for terrestrial rifted basins, that is, strong fractionation lateral migration model through sandy beds, weak fractionation vertical migration model along faults, and maturity impacts on migration assessment. [source]


The impact of financial performance on environmental policy: does firm life cycle matter?

BUSINESS STRATEGY AND THE ENVIRONMENT, Issue 6 2009
Khaled Elsayed
Abstract Existing literature has provided inconclusive evidence regarding the impact of financial performance on firm policy relating to environmental issues. In this paper, we propose that the influence of corporate financial performance on corporate environmental policy is unlikely to be monotonic but, rather, will vary with firm life cycle. We test this hypothesis by the application of static and dynamic techniques on panel data from UK companies. The results provide support for our hypotheses that financial performance has the strongest impact on environmental policy in the maturity stage of the firm life cycle and the weakest impact in the rapid growth stage. Copyright © 2007 John Wiley & Sons, Ltd and ERP Environment. [source]


Effects of land-cover changes on the hydrological response of interior Columbia River basin forested catchments

HYDROLOGICAL PROCESSES, Issue 13 2002
James R. VanShaar
Abstract The topographically explicit distributed hydrology,soil,vegetation model (DHSVM) is used to simulate hydrological effects of changes in land cover for four catchments, ranging from 27 to 1033 km2, within the Columbia River basin. Surface fluxes (stream flow and evapotranspiration) and state variables (soil moisture and snow water equivalent) corresponding to historical (1900) and current (1990) vegetation are compared. In addition a sensitivity analysis, where the catchments are covered entirely by conifers at different maturity stages, was conducted. In general, lower leaf-area index (LAI) resulted in higher snow water equivalent, more stream flow and less evapotranspiration. Comparisons with the macroscale variable infiltration capacity (VIC) model, which parameterizes, rather than explicitly represents, topographic effects, show that runoff predicted by DHSVM is more sensitive to land-cover changes than is runoff predicted by VIC. This is explained by model differences in soil parameters and evapotranspiration calculations, and by the more explicit representation of saturation excess in DHSVM and its higher sensitivity to LAI changes in the calculation of evapotranspiration. Copyright © 2002 John Wiley & Sons, Ltd. [source]


Rheological properties of Josapine pineapple juice at different stages of maturity

INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 4 2009
Rosnah Shamsudin
Summary The rheological behaviour of Josapine pineapple juice with at various maturity stages was studied at a wide range of temperature (5,65 °C) and concentration (4,14 °Brix) using a rotational rheometer as the measuring system. The results show that josapine pineapples juice demonstrated a Newtonian behavior and is influenced by maturity stage, temperature and concentration. The Arrhenius typed equation successfully describe the effect of temperature on the viscosity, on the other hand, the effect of concentration can be described better using exponential equation. Finally, an equation describing the combined effect of temperature and concentration on viscosity at different stages of maturity was successfully developed. [source]


Population biology of the red gurnard (Aspitrigla cuculus L.; Triglidae) in the inshore waters of Eastern Anglesey and Northwest Wales

JOURNAL OF APPLIED ICHTHYOLOGY, Issue 4 2010
A. L. Marriott
Summary ICES has identified red gurnard Aspitrigla cuculus (L.) as a potential commercial species and recommended that monitoring programmes should be conducted to derive information on biological parameters for stock assessment purposes. In this paper, data on the population biology of red gurnard in the coastal waters of Northwest Wales and Eastern Anglesey are presented. Total length (TL) of fish sampled ranged from 15.4 to 35.0 cm (males) and 10.5 to 43.1 cm (females), with the majority of females between 20 and 30 cm TL (70.0%) and males between 20 and 30 cm TL (71.0%). TL/weight (W) relations were similar between immature and mature individuals for both sexes and between both sexes (all maturity stages combined), producing a combined data equation W = 0.005 TL3.19. Age of fish ranged from 1 to 7 years and 1 to 6 years, respectively, for females and males, with the majority of females age 3 (37%) and the majority of males age 2 (49%). The age structures of female and male red gurnards were significantly different, with the older age classes consisting predominantly of female fish. Both males and females exhibited similar asymptotic growth patterns; the combined von Bertalanffy growth function was . Instantaneous rates of total mortality were calculated as 1.13 year,1 for males and 0.98 year,1 for females. The size (L50) and age at first maturity (A50) were estimated to be 26.3 cm TL and 3.6 years for males, 28.1 cm TL and 3.5 years for females and 25.6 cm TL and 3.7 years for both sexes combined. [source]


Reproductive biology of the silver pomfret, Pampus argenteus (Euphrasen), in Kuwait waters

JOURNAL OF APPLIED ICHTHYOLOGY, Issue 6 2000
S. Dadzie
Summary The reproductive activities of the silver pomfret, Pampus argenteus (Euphrasen), in Kuwait waters were investigated from March 1996 to February 1998. Observations on the seasonal distribution of maturity stages and variations in seasonal fluctuations in the gonadosomatic index (GSI) confirmed recent findings that the spawning period begins in May. The species has a prolonged spawning period in the females extending from May to August, whereas the males mature in April and ripe specimens were encountered in monthly samples until September. The recruitment pattern confirmed the one breeding season. There are two spawning peaks, the first in May and the second in August. Variations in GSI relative to fish length indicated that females and males are most fecund at about 24.5,26.4 cm and 20.5,22.4 cm length classes, respectively. The males mature earlier than females, at a minimum size of 12.5,14.4 cm, while the females mature at 20.5,22.4 cm. The oocyte diameter-frequency distribution suggests a serial rhythm of spawning. Fecundity ranged from 28 965 to 455 661 and correlated positively with: (a) standard length (P < 0.006); (b) ovary weight (P < 0.001); and (c) body weight (P < 0.001), and negatively with egg size (P < 0.003). [source]


Reproductive cycle of female Brazilian codling, Urophycis brasiliensis (Kaup 1858), caught off the Uruguayan coast

JOURNAL OF APPLIED ICHTHYOLOGY, Issue 2 2000
By A. Acuña
Between August 1993 and September 1995, aspects of reproduction of female Urophycis brasiliensis (Phycidae), a euryhaline species found in the Western Atlantic between 23° and 40° S, were studied. A total of 2500 specimens (23,60 cm; 113,2400 g) were obtained from artisanal fishermen at two locations on the Uruguayan coast: Piriápolis, influenced by the discharge of the Río de la Plata, and La Paloma, a marine site. The ovaries of 900 fish, analysed according to standard histological techniques, revealed eight maturity stages, including one virgin ovary obtained from the catch of a research vessel. The gonadosomatic index ranged from 0.13 to 8.7. Its maximum was determined in the autumn in La Paloma, whereas a shift towards the winter was observed in Piriápolis. In both capture areas, resting stage 2 was present in the samples throughout the year, reaching 67% of the total. At no time were hydrated ovaries observed. The histological cycle is described and compared with macroscopic features of the female gonad. Maturity stages determined in the field had to be confirmed by histological analysis in order to avoid erroneous classification. Although the two ports are only 150 km apart, data indicate different and extended reproductive periods, between June and December for Piriápolis, and March to May for La Paloma. Data indicate synchronous group spawning, possibly as a reproductive strategy in a highly variable environment. The results are compared with scarce information available on U. brasiliensis in its distribution area and data on other species of the same genus. [source]


The link between migration, the reproductive cycle and condition of Sardinella aurita off Mauritania, north-west Africa

JOURNAL OF FISH BIOLOGY, Issue 5 2007
R. Ter Hofstede
The annual migration pattern of round sardinella Sardinella aurita up and down the north-western African coast between 12° N (Senegal) and 22° N (western Sahara) was shown to be associated with spawning activity and a distinct seasonality in fish condition, based on monthly sampling from commercial catches (2000,2003). Some S. aurita were found to spawn throughout the entire year, but a peak in spawning existed during the summer (June to September). The spawning cycle is apparent from seasonality in maturity stages, but is also demonstrated by the increase in gonad mass and fat content of the fish in springtime, the period preceding spawning. During the months after spawning, although feeding is maintained, the physical condition of the fish collapses, and fat content rapidly declines. [source]


Micro- and macroscopic characteristics to stage gonadal maturation of female Baltic cod

JOURNAL OF FISH BIOLOGY, Issue 2 2003
J. Tomkiewicz
A set of histological characteristics to judge ovarian development was established and used to elaborate morphological criteria of 10 maturity stages of Baltic cod Gadus morhua sampled throughout the annual cycle to represent different macroscopic maturity stages. The applied characteristics confirmed most stages of the macroscopic scale, but the separation of late immature and resting mature females remained imprecise. Atretic vitellogenic oocytes or encapsulated residual eggs identified the resting condition morphologically, but not all ovaries with visible signs of previous spawning showed such features. One ovarian stage that was previously classified as ,ripening' was changed to ,spawning', owing to the prevalence of hydrated eggs and empty follicles. Ovaries with malfunctions were defined by a separate stage. Macroscopic criteria were revised by comparing the gross anatomy of ovaries with their histology. Female length and gonado-somatic index supported stage definitions, but substantial variation in Fulton's condition factor and the hepato-somatic index rendered these of little use for this purpose. The time of sampling influenced staging accuracy. A female spawner probability function based on the proportion of ripening and ripe specimens in early spring seems to be the most appropriate method to estimate spawner biomass and reproductive potential. [source]


Effect of Maturity Stages and Drying Methods on the Retention of Selected Nutrients and Phytochemicals in Bitter Melon (Momordica charantia) Leaf

JOURNAL OF FOOD SCIENCE, Issue 6 2009
Min Zhang
ABSTRACT:, The purpose of this study was to investigate the nutrient and phytochemical composition of bitter melon leaves under varying maturity levels and drying techniques. Fresh, oven-dried, and freeze-dried leaves were evaluated over 3 maturity stages. In fresh leaves at various stages, crude fat, crude protein, and soluble dietary fiber contents ranged from 4.2% to 13.6%, 6.4% to 23.1%, and 0.04% to 3.50% on dry-weight basis, respectively. The contents of K, Ca, Mg, Fe, and Zn ranged from 1850.8 to 2811.8, 837.4 to 4978.2, 317.3 to 512.4, 8.4 to 16.7, and 4.1 to 5.9 mg/100 g dry-weight basis, respectively. Vitamin C, ,-carotene, and lutein contents ranged from 397.4 to 1275.1, 154.2 to 422.8, and 737.6 to 1304.6 ,g/g dry-weight basis. The major flavonoids and phenolic acids were rutin, gentistic acid, and,o -coumaric acid, which ranged from 7.57 to 12.75, 2.53 to 10.11, and 4.24 to 9.75 mg/g dry-weight basis, respectively. In oven-dried samples, 40.2% to 52.3% of vitamin C, 35.4% to 55.4% of ,-carotene, 25.6% to 71.6% of lutein, 26.4% to 84.0% of rutin, trace to 11.4% of gentistic acid, and 7.4% to 46.6% of,o -coumaric acid were retained, while the retainment ratios of these components in freeze-dried samples were 84.7% to 99.0%, 76.4% to 99.3%, 90.4% to 96.1%, 39.8% to 99.3%, 24.1% to 68.4%, and 75.8% to 87.0%, respectively. The data showed that freeze-drying better preserves the nutrient and phytochemical quality of bitter melon leaves in comparison to oven-drying. Bitter melon leaf is a rich source of selected nutrients and phytochemicals. [source]


RELATIONSHIP BETWEEN ORGANIC MATTER, SULPHUR AND PHOSPHATE CONTENTS IN UPPER CRETACEOUS MARINE CARBONATES (KARABOGAZ FORMATION, SE TURKEY): IMPLICATIONS FOR EARLY OIL GENERATION

JOURNAL OF PETROLEUM GEOLOGY, Issue 4 2010
S. Inan
In this paper, we discuss the relationship between the organic matter, sulphur and phosphate contents of Upper Cretaceous marine carbonates (Karabogaz Formation) in the Adiyaman Petroleum Province of SE Turkey. The results of organic geochemical analyses of core samples obtained from the Karabogaz Formation suggest that phosphate deposition occurred in settings where the water column was oxic to sub-oxic. However, the preservation of organic matter was favoured in anoxic environments. Moreover, the presence of sulphur (especially sulphur incorporated into kerogen) in organic matter-rich layers led to early oil generation. The results of stepwise py-gc analyses are consistent with a model in which, with increasing maturity, S-S and C-S bonds are the first to be eliminated from the macromolecular kerogen structure. Study of the maturity evolution of S-rich kerogen by laboratory pyrolysis implies that marginally mature and/or mature kerogen in the Karabogaz Formation, which may be classified as classic "Type II" kerogen, was most probably Type II/S at lower maturity stages. This enabled oil generation to occur at relatively shallow burial depths and relatively early stages of maturation. It is reasonable to conclude that Type II/S kerogen, overlooked in previous studies, was abundant in TOC-rich intervals in the Karabogaz Formation. Early generation (and expulsion) from Type II/S kerogen may have sourced the sulphur-rich oils in the Adiyaman area oilfields. [source]


Validation of macroscopic maturity stages according to microscopic histological examination for European anchovy

MARINE ECOLOGY, Issue 2009
Rosalia Ferreri
Abstract The identification and classification of macroscopic maturity stages plays a key role in the assessment of small pelagic fishery resources. The main scientific international commissions strongly recommend standardizing methodologies across countries and scientists. Unfortunately, there is still a great deal of uncertainty concerning macroscopic identification, which remains to be validated. The current paper analyses reproductive data of European anchovy (Engraulis encrasicolus L. 1758), collected during three summer surveys (2001, 2005 and 2006) in the Strait of Sicily, to evaluate the uncertainty in the macroscopic maturity stage identification and the reliability of the macroscopic adopted scale. On board the survey vessels, the maturity stage of each fish was determined macroscopically by means of an adopted maturity scale subdivided in six stages. Later, at the laboratory, the gonads were prepared for histological examination. The histological slides were analysed, finally assigning the six maturity stages for macroscopic examinations. A correspondence table was obtained with the proportion and number of matches between the two methods. The results highlight critical aspects in the ascription of macroscopic maturity stages, particularly for the present research aim. Different recommendations were evaluated depending on the scope of the study conducted on maturity (e.g. daily egg production, fecundity and maturity ogive computation). The most interesting results concern the misclassification of stage IV and stages III and V (the most abundant), which confirms their macroscopic similarity. Although the results are based on a small number of samples, the advantages and disadvantages of macroscopic and histological methods are discussed with the aim to increase the accuracy of correct identification and to standardize macroscopic maturity ascription criteria. [source]


Applicability of Carbazole Migration Indices in Continental Rift Basins: A Case Study of Western Lujiapu Depression in Kailu Basin, NE China

ACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 3 2010
Shuqing ZHOU
Abstract: Kailu Basin in which the Western Lujiapu Depression is located is a typical continental rift basin. Biomarker parameters of the oils indicate that depositional facies and environments vary between the Bao 1 and Bao 14 fault blocks with a higher saline environment in the Bao 1 fault block, but such difference has no significant impact on carbazole abundance and distribution. Maturity and migration distance are the main controls on carbazole abundance and distribution in the Western Lujiapu Depression. The commonly used migration indices, such as ratios of nitrogen shield isomers to nitrogen exposed isomers (1-/4-methylcarbazole ratio, 1,8-/2,4-dimethylcarbazole (DMC) ratio and half-shield/exposed-DMC ratio), absolute concentrations of alkylated carbazoles and BC ratio (= benzo [a]carbazole/ (benzo[a]carbazole + benzo[c]carbazole)) increase at the low mature range and decrease at a higher mature range with increasing maturity. At relatively low maturity stage (Rc<0.77%), maturation has reversal effects with migration on the ratios of nitrogen shield isomers to nitrogen exposed isomers, which may cover migration influence and makes these parameters fail to indicate migration effects. Valid migration indicators at this maturity stage are concentrations of alkylated carbazoles and BC ratios, which can provide ideal tools for migration direction assessment even within short migration distance. Maturity effects should be taken into account when carbazole compounds are applied to indicate migration direction, and at different maturity stages, these commonly used parameters have different validity in tracing migration direction. Coupled with our previous study in the Eastern Lujiapu Depression, a conceptual model of the variation of nitrogen migration indices can be established for terrestrial rifted basins, that is, strong fractionation lateral migration model through sandy beds, weak fractionation vertical migration model along faults, and maturity impacts on migration assessment. [source]