Model simulations to determine optimal fishing effort and season duration for a tropical shrimp fishery     

Chen  Weizhong  Al-Foudari  Hussain 《中国海洋湖沼学报》2018,36(5):1860-1869

Journal of Oceanology and Limnology - Kuwait’s shrimp fishery presents typical tropical shrimp fishery characteristics with highly variable recruitment, fast growth and strong seasonal...  相似文献   

Occurrence of Nummulitic coralline limestone from offshore Palar Basin,Bay of Bengal,India     

S. Ramesh  K. Nvv Murthy  S. M. Hussain  S. Ramasamy  G. A. Ramadass 《Marine Georesources & Geotechnology》2020,38(1):57-63

Abstract

Palar basin is located between Pennar and Cauvery sedimentary basins of East coast of India in Bay of Bengal, northeast Indian Ocean. Sea floor drill (Wire-line Autonomous Coring System – WACS) with operational capability of up to 3000?m water depth was developed to collect long cores from deep sea floor for geotechnical and ocean resource assessment studies. During the drilling operation it encountered Nummulitic coralline limestone of Lower Eocene age at 18 meters below the seafloor (mbsf) at 850?m water depth indicating carbonated platform presence for the first time at the study region. Bathymetry contour from Naval Hydrography Chart and General Bathymetric Chart of the Oceans (GEBCO) has revealed the presence of shallow mounds from 50 to 200?m depth closure contour near the sampling site at 850?m water depth which might be a submerged carbonated structure. Since, Nummulites are shallow water dwelling fauna (<20?m depth) but its occurrence at 18 mbsf in 850?m water depth is recorded because of the advancement in technology tool for long core sampling by means of sea floor drill.  相似文献   

Present environment and historic changes from the record of lake sediments, Dhaka City, Bangladesh   总被引：1，自引：0，他引：1  

Faruque Ahmed  M. Hawa Bibi  M. Hussain Monsur  Hiroaki Ishiga 《Environmental Geology》2005,48(1):25-36

Changes in the urban environment of Dhaka City have been evaluated from the geochemical compositions of bottom sediments from two lakes, Gulshan-1 and –2. Abundances of Pb, Zn, Fe₂O₃ and total sulfur in a Gulshan-1 core gradually increase toward the sediment–water interface. Three stages of condition change can be recognized in Gulshan-1, based on trace metal concentration patterns. The basal Stage I corresponds to background Dhaka sedimentation, whereas gradual increase in Stage II represents the beginning of pollution. Marked increases in Pb and Zn in Stage III reflect rapid urban development and increased emissions to the atmosphere. The condition of the Dhaka environment is compared to that of Japan based on Zn–Fe₂O₃ and Pb–Fe₂O₃ relations. Zn–Fe₂O₃ ratios in Stage I Dhaka sediments are similar to normal Japanese sediments, whereas Stage II data lie on the same trend as Japan urban sediments. Dhaka Stage III samples have greater Zn:Fe₂O₃ ratios than Japanese urban sediments, suggesting Zn pollution from poorly-controlled industrial sources. In contrast, the Dhaka Pb–Fe₂O₃ trend lies between normal and urban Japanese sediments. Although vehicle emissions in Dhaka are now significant, the data suggest that Pb pollution from this source remains in its early stages.  相似文献   

Spatial pattern of variation in populations of Acacia nilotica in semi-arid environment     

S. Mahmood  A. Ahmed  A. Hussain  M. Athar 《International Journal of Environmental Science and Technology》2005,2(3):193-199

Variability among populations was analyzed in five provenances of Acacia nilotica from spatially variable habitats. Populations of A. nilotica developed in response to their habitat conditions. The level of variability was significantly high among the populations. Phenotypic variability was extremely high for leaf and stipular spine characteristics. The nature of morphological variability for vegetative traits appeared environmentally controlled. The differentiation of leaf and stipular spine expression seems to have an adaptive significance for the species in terms of water economy. Although, seed and pod characteristics are genetically controlled showing a lower proportion of variability but these traits supported r and k-selection that may allow the species to survive under a wide array of contrasting habitats. The study suggested that populations of A. nilotica are differentiated in relation to the heterogeneity of environment. These populations became adapted to their habitat through the variability of morphological expressions. The morphologically differentiated populations of the species had allowed them to maintain themselves in a wide array of environmental situations enabling A. nilotica to occupy ample ecological ranges.  相似文献   

Ambient noise measurements in Rawalpindi–Islamabad,twin cities of Pakistan: a step towards site response analysis to mitigate impact of natural hazard     

S. M. Talha Qadri  S. H. Sajjad  R. A. Sheikh  Khaista Rehman  Zahid Rafi  Bushra Nawaz  Waseem Haider 《Natural Hazards》2015,78(2):1111-1123

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Anomalous optical variations in the grossular garnet from the Eden Mills,Belvidere Mountain (Vermont,USA)     

Manzoor Ahmad Badar  Safdar Hussain  Shanawer Niaz  Saif ur Rehman 《Arabian Journal of Geosciences》2016,9(9):545

The optical anomalies, and surface and lamellar textures of a birefringent grossular garnet crystal from the Eden Mills, Belvidere Mountain, Vermont, USA, have been investigated by optical polarizing microscope, electron-probe micro-analyzer, back-scattered electron imaging, infrared spectroscopy, and single-crystal X-ray diffractometer from the standpoint of crystal growth. This grossular shows one-to-one correlation between natural surface features and its internal textures under crossed polarizers. Electron-probe micro-analyzer (EPMA) gave average chemical composition in (110) thin section, of bright lamella {Ca_2.97Mn_0.06}_∑3.03 [Al_1.59Fe_0.37Ti_0.01]_∑1.97(Si_3.00)_∑3.00 (Gros_79.5And_18.9Sps_1.6) and of dark host {Ca_2.99Mn _0.06}_∑3.05 [Al_1.73Fe_0.26 Ti_0.01]_∑2.00(Si_2.97OH_0.03)_∑3.00 (Gros_85.4And₁₃Sps_1.6). The correspondence of surface features and the internal textures with spiral or pyramidal growth mechanism suggest that the internal textures of the Eden Mills grossular are formed during growth process. The optical vibrational orientations and the growth steps inclination along [001] and \( \left[\overset{-}{1}10\right] \) directions predict monoclinic symmetry. With X-ray diffractometer (XRD) method, pseudocubic parameters are a = 11.839(2) Å, b = 11.855(1) Å, and c = 11.868(2) Å with interaxial angles α = 90.00(1)°, β = 89.99(1)°, and γ = 90.02(2)° that show orthorhombic symmetry of this crystal. Lamellar texture of Al³⁺-rich host with Fe³⁺-rich lamella infers cation ordering at octahedral site of the garnet structure. IR data favors the non-cubic orientation of [(OH) ₄] at tetrahedral position in this grossular structure.  相似文献   

Relationship between finite strain and tectonic setting in the Ar-Ruwaydah area,eastern Arabian Shield,Saudi Arabia     

Osama M. K. Kassem  Abdullah L.A. Almutairi  Abdel Aziz M. Al Bassam  Hussain J. Al Faifi 《Arabian Journal of Geosciences》2016,9(19):728

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Sequence stratigraphic analysis of Eocene Rock Strata,Offshore Indus,southwest Pakistan     

Natasha Khan  Khaista Rehman  Sajjad Ahmad  Jamil Khokher  M. Iqbal Hajana  M. Hanif 《Marine Geophysical Researches》2016,37(3):207-228

In this study, seismic data from two wells (Pak G2-1 and Indus Marine-1C) and age diagnostic larger benthic foraminifera (LBF) within drill cuttings has been used for the first time to identify depositional sequences within the carbonates in the Offshore Indus Basin, Pakistan. The Offshore Indus is tectonically categorized as a passive continental margin where carbonates occur as shelf carbonates in the near offshore and on volcanic seamounts in deeper waters. Seismic data analysis has indicated the presence of minor faults and carbonate buildups above the igneous basement in the south. Patterns of the seismic reflections enabled definition of three seismic facies units identified as: Unit 1 basement, represented by chaotic, moderate amplitude reflection configuration; while parallel bedding and the drape of overlying strata is typical character of Unit 2, carbonate mound facies. The younger Miocene channels represent Unit 3. The diagnosis of Alveolina vredenburgi/cucumiformis biozone confirmed the Ilerdian (55–52 Ma) stage constituting a second order cycle of deposition for the Eocene carbonates (identified as Unit 2). The carbonate succession has been mainly attributed to an early highstand system tract (HST). The environmental conditions remained favorable leading to the development of keep-up carbonates similar to pinnacle buildups as a result of aggradation during late transgressive system tract and an early HST. The carbonate sequence in the south (Pak G2-1) is thicker and fossiliferous representing inner to middle shelf depths based on fauna compared to the Indus Marine-1C in the north, which is devoid of fossils. Three biozones (SBZ 5, SBZ 6 and SBZ 8) were identified based on the occurrence of LBF. The base of the SBZ 5 zone marks the larger foraminifera turnover and the Paleocene–Eocene (P–E) boundary. The LBF encountered in this study coincides with earlier findings for the P–E boundary. Our findings indicate that the entire Ilerdian stage ranges from 55.5 to 52 Ma that was the episode of warmer water conditions on the carbonate shelves leading to the diversification of K-strategist larger foraminifera. The larger foraminiferal assemblage encountered in this study confirms the findings. The possible indication of stratigraphic-combination traps, revealed as reflection terminations, make carbonate mounds in the south a potential exploration target.  相似文献   

Long-range precipitation forecasts using paleoclimate reconstructions in the western United States     

Christopher Allen CARRIER  Ajay KALRA  Sajjad AHMAD 《山地科学学报》2016,13(4):614-632

Long-range precipitation forecasts are useful when managing water supplies.Oceanicatmospheric oscillations have been shown to influence precipitation.Due to a longer cycle of some of the oscillations,a short instrumental record is a limitation in using them for long-range precipitation forecasts.The influence of oscillations over precipitation is observable within paleoclimate reconstructions;however,there have been no attempts to utilize these reconstructions in precipitation forecasting.A data-driven model,KStar,is used for obtaining long-range precipitation forecasts by extending the period of record through the use of reconstructions of oscillations.KStar is a nearest neighbor algorithm with an entropy-based distance function.Oceanic-atmospheric oscillation reconstructions include the El Nino-Southern Oscillation(ENSO),the Pacific Decadal Oscillation(PDO),the North Atlantic Oscillation(NAO),and the Atlantic Multi-decadal Oscillation(AMO).Precipitation is forecasted for 20 climate divisions in the western United States.A 10-year moving average is applied to aid in the identification of oscillation phases.A lead time approach is used to simulate a one-year forecast,with a 10-fold cross-validation technique to test the models.Reconstructions are used from 1658-1899,while the observed record is used from 1900-2007.The model is evaluated using mean absolute error(MAE),root mean squared error(RMSE),RMSE-observations standard deviation ratio(RSR),Pearson’s correlation coefficient(R),NashSutcliffe coefficient of efficiency(NSE),and linear error in probability space(LEPS) skill score(SK).The role of individual and coupled oscillations is evaluated by dropping oscillations in the model.The results indicate ’good’ precipitation estimates using the KStar model.This modeling technique is expected to be useful for long-term water resources planning and management.  相似文献   

Contamination of soil and carrots irrigated with different sources of water in Punjab,Pakistan     

Kafeel Ahmad  Zafar Iqbal Khan  Sumaira Yasmin  Asma Ashfaq  Ijaz Rasool Noorka  Nudrat Aisha Akram  Hazoor Ahmad Shad  Abrar Hussain  Fahim Arshad  Muhammad Sher  Hafiz Muhammad Tahir  Humayun Bashir  Asma Zafar 《Environmental Earth Sciences》2016,75(5):426

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