Calcareous nannofossil biostratigraphy and paleoecology of the Cenomanian – Turonian transition in the Tarfaya Basin, southern Morocco     

Abdel Aziz Tantawy   《Cretaceous Research》2008,29(5-6):995

An abundant and diverse nannoflora occurs across the Cenomanian/Turonian (C/T) boundary at Tazra in the Tarfaya Basin of southern Morocco. The nannoflora of this sequence permits recognition of three biozones (CC10-CC12), three subzones (CC10a, CC10b and CC10c), and thirteen important nannolith bioevents previously reported from this interval elsewhere. The floral record shows erratic species abundance fluctuations that clearly vary with lithology and reflect at least in part preservational bias and diagenetic processes. In general, four dissolution resistant taxa are dominant: Watznaueria barnesae, Eiffellithus turriseiffelii, Eprolithus floralis, and Zeugrhabdotus spp. The late Cenomanian Zone CC10 marks a rapid excursion in ∂¹³C and is characterized by the successive extinction of four taxa, which are widely recognized as reliable biomarkers: Corollithion kennedyi, Axopodorhabdus albianus, Lithraphidites acutus, and Helenea chiastia. This interval is also marked by high species richness and high abundance of the tropical species Watznaueria barnesae, suggesting warm tropical waters. The subsequent ∂¹³C plateau and organic carbon-rich black shale deposition of the oceanic anoxic event (OAE2) is characterized by low species richness, but high nannofossil abundance, and peak abundance of the cool water and high productivity indicator Zeugrhabdotus spp., followed by the first peak abundance of cool water Eprolithus floralis. This interval correlates with the planktic foraminiferal diversity minimum and the Heterohelix shift, which marks the expansion of the oxygen minimum zone (OMZ). The C/T boundary is identified based on the FO of Quadrum gartneri, which is <1 m below the FO of the planktic foraminifer C/T marker Helvetoglobotruncana helvetica. In the early and middle Turonian, the two dominant species, tropical W. barnesae and cool water E. floralis, alternate in abundance and suggest fluctuating climatic conditions.  相似文献   

Integrated stratigraphy and <Superscript>40</Superscript>Ar/<Superscript>39</Superscript>Ar chronology of the Early to Middle Miocene Upper Freshwater Molasse in eastern Bavaria (Germany)     

H. Abdul Aziz  M. Böhme  A. Rocholl  A. Zwing  J. Prieto  J. R. Wijbrans  K. Heissig  V. Bachtadse 《International Journal of Earth Sciences》2008,97(1):115-134

A detailed integrated stratigraphic study was carried out on middle Miocene fluvial successions of the Upper Freshwater Molasse (OSM) from the North Alpine Foreland Basin, in eastern Bavaria, Germany. The biostratigraphic investigations yielded six new localities thereby refining the OSM biostratigraphy for units C to E (sensu; Heissig, Actes du Congres BiochroM’97. Mem Trav EPHE, Inst Montpellier 21, 1997) and further improving biostratigraphic correlations between the different sections throughout eastern Bavaria. Radioisotopic ages of 14.55 ± 0.19 and 14.88 ± 0.11 Ma have been obtained for glass shards from the main bentonite horizon and the Ries impactite: two important stratigraphic marker beds used for confirming our magnetostratigraphic calibration to the Astronomical Tuned Neogene Time Scale (ATNTS04; Lourens et al. in Geologic Time Scale 2004, Cambridge University Press, 2004). Paleomagnetic analysis was performed using alternating field (AF) and thermal (TH) demagnetization methods. The AF method revealed both normal and reverse polarities but proofs to yield unreliable ChRM directions for the Puttenhausen section. Using the biostratigraphic information and radioisotopic ages, the magnetostratigraphic records of the different sections are tentatively correlated to the Astronomical Tuned Neogene Time Scale (ATNTS04; Lourens et al. in Geologic Time Scale 2004, Cambridge University Press, 2004). This correlation implies that the main bentonite horizon coincides to chron C5ADn, which is corroborated by its radioisotopic age of 14.55 Ma, whereas the new fossil locality Furth 460, belonging to OSM unit E, probably correlates to chron C5Bn.1r. The latter correlation agrees well with the Swiss Molasse locality Frohberg. Correlations of the older sections are not straightforward. The Brock horizon, which comprises limestone ejecta from the Ries impact, possibly correlates to C5ADr (14.581–14.784 Ma), implying that, although within error, the radioisotopic age of 14.88 ± 0.11 Ma is somewhat too old. The fossil localities in Puttenhausen, belonging to the older part of OSM unit C, probably coincide with chron C5Cn.2n or older, which is older than the correlations established for the Swiss Molasse. Electronic supplementary material The online version of this article (doi: ) contains supplementary material, which is available to authorized users.  相似文献   

塔克拉玛干沙漠不同区域土壤热通量变化比较     

张文斌  买买提艾力﹒买买提依明  何清  杨兴华  霍文  杨帆  塔伊尔.艾则孜 《沙漠与绿洲气象(新疆气象)》2016,10(2):57-62

选取塔克拉玛干沙漠腹地塔中地区和北缘过渡带肖塘地区2013年土壤热通量观测资料,初步比较分析了塔克拉玛干沙漠两种下垫面的土壤热通量变化特征。结果表明：(1)在日变化尺度上,两个站点都有明显的日变化特征,1月份塔中站土壤热通量日平均变化幅度小于肖塘站,日较差分别为58.9 W.m2和72.4 W.m2,4月份两站土壤热通量变化幅度较为接近,日较差分别为88.1W.m2、100.1 W.m2。7、10月份塔中站土壤热通量变化幅度明显高于肖塘站,日较差分别为99.0 W.m2、53.7W.m2,100.3 W.m2、73.3W.m2。(2)不同天气条件下两个站点土壤热通量变化都有很大差异。晴天,塔中站和肖塘站土壤热通量变化都呈现出单峰型,变化幅度较一致,日较差分别为119.7 W.m2、119.1 W.m2。沙尘天和雨天受云层或降水的影响土壤热通量变化波动较大,沙尘天塔中站变化幅度小于肖塘站,日较差分别为83.6 W.m2、133.1 W.m2;雨天塔中站和肖塘站变化幅度都很剧烈,日较差分别为70.6 W.m2、66.6 W.m2。(3)年变化尺度上,塔中站土壤热通量在7月份达到最大值(7.7 W.m2),在11月出现最小值(-5.3 W.m2),肖塘站7月份出现最大值(4.2 W.m2),11月份出现最小值(-10.2 W.m2)。塔中站和肖塘站土壤热通量年总量差异很大,塔中站为16.8 W.m2,能量由大气向土壤传递,土壤为热汇,而肖塘站则为-34.9 W.m2,能量由土壤向大气传播,土壤表现为热源。  相似文献   

Hydrogeological conditions and aquifers potentiality for sustainable development of the desert areas in Wadi Qena,Eastern Desert,Egypt     

Ahmed Aziz Abdel Moneim 《Arabian Journal of Geosciences》2014,7(11):4573-4591

To increase the potentiality of development and land reclamation activities, the Egyptian government funds the construction of a new desert road in Upper Egypt. This road connects Upper Egypt with the Red Sea Governorate. Surrounding the road is 207,000 acres of land surface which is almost flat and suitable for reclamation. To ensure the sustainability of the proposed development surrounding the road, analyses of the morphometric parameters, infiltration test and the grain size distribution, geoelectrical and hydrogeological investigations were conducted in the area. The results indicated a possibility of flash flood hazards and poor drainage condition for land reclamation activities is expected. The hydrogeological and geoelectrical investigations revealed that the unconfined Quaternary and confined Nubian Sandstone aquifers are the main aquifers in the area. The depths to water in the two aquifers range from 18 to 36 and 80 to 300 m with an average thickness of 40 and 275 m, respectively. The aquifers are made of sands and silt with clay intercalations. The total dissolved solids of water ranges between 1,700 and 5,400 mg/L, whereas the sodium absorption ratio ranges between 7 and 30 meq/L, indicating the suitability of water for irrigating medium- to high-salt-tolerant crops with proper drainage facilities. Thus, water in this area is not suitable for domestic use. Based on hydrogeological equations, the available water for extraction from the aquifers in the area is about 17.195?×?10⁹ m³, and this volume is not feasible to reclaim the whole proposed area for reclamation. Meanwhile, it may be possible to water small farms (not more than 60,000 acres for 50 years). Surface water source should be considered for the sustainability development of the area.  相似文献   

Economic valuation of suspended sediment and phosphorus filtration services by four different wetland types: A preliminary assessment for southern Ontario,Canada     

Tariq Aziz  Philippe Van Cappellen 《水文研究》2021,35(12):e14442

Wetlands are known for their water filtration (or purification) function. Although different wetland types differ in their filtration capacity, they are usually aggregated together in economic valuation studies. Here, we explicitly separate the valuation of the suspended sediment and phosphorus (P) filtration services of the four major wetland types—bogs, fens, marshes and swamps—found in southern Ontario, Canada. The areal extents of the four wetland types are derived from the Canadian Wetland Inventory (CWI) progress map, while the sediment accretion rate is used as the key variable regulating the suspended sediment and P filtration functions. Based on available literature data, we assess the relationship of the sediment accretion rate to wetland size. Because only weak positive correlations are found, we assign a mean (average) sediment accretion rate to each wetland type. The sediment accretion rates are combined with mean soil P concentrations to estimate Pretention rates by the wetlands. The replacement cost method is then applied to valuate the sediment and P filtration services. The unit values for both sediment and P retention decrease in the order: marshes > bogs ≈ swamps > fens. The total value of sediment plus phosphorus removal by all wetlands in southern Ontario amounts to $4.2 ± 2.9 billion per year, of which about 80% is accounted for by swamps. We further assess the costs of different options to offset the additional P loading generated in a hypothetical scenario whereby all wetlands are converted to agriculture. The results demonstrate that replacing the P filtration function of existing wetlands with conventional land management and water treatment solutions is not cost-effective, hence reinforcing the importance of protecting existing wetlands.  相似文献   

Temporal variations of mesozooplankton abundance and biomass in the mangrove creek area along the Karachi coast, Pakistan     

Farah Naz  Naureen Aziz Qureshi  Noor Us Saher 《海洋学报(英文版)》2014,33(12):222-230

The temporal variations of mesozooplankton abundance and biomass （1-Volumetric method by settling volume and displacement volume and 2- Gravimetric method through wet weight, dry weight and ash-free dry weight） with relation to environmental parameters were studied in the mangrove creek area of Karachi coast, Pakistan. The data of mesozooplankton samples along with environmental parameters （temperature, salinity, pH, etc.） were collected during January 1998 to December 1998 from two creek stations. The abun-dance of mesozooplankton also exhibited seasonal trends at both stations. At Sta. S2, the highest and low-est abundance values were observed during post-monsoon and southwest monsoon respectively whereas, at Sta. S1, a clear trend of high abundance in pre-monsoon to low abundance in southwest monsoon was observed. Mesozooplankton abundance was also positively correlated with settling volume, displacement volume, wet weight and dry weight. The highest biomass value was observed in the northeast monsoon and pre-monsoon periods. The results of the canonical analysis of the output from the discriminate function was tested. Out of fifteen variables, only one was significantly different in single character ratios dry weight/ash free-dry weight （F3,23=4.78,P＆lt;0.005）. The mesozooplankton community was collectively composed of 28 taxa. Among these groups, copepoda （66.3%）, gastropod larvae （9.94%）, evadne （4.60%）, zoea （3.60%）, cypris nauplii （2.56%）, lemellibranch larvae （1.87%）, chaetognaths （1.81%）, ostracods （1.73%）, lucifer （1.15%） and barnacles nauplii （1.35%） contributed the most to the similarities within Sta. S1, while copepoda （74.68%）, cypris nauplii （5.29%）, gastropods （4.87%）, barnacles nauplii （4.81%）, evadne （1.72%）, zoea （1.53%） and ca-ridean larvae （1.18%） at Sta. S2. The remaining mesozooplanktonic group were accounted for less than 5% and 6% at Sta. S1 and Sta. S2 respectively, of the total organisms. Similarity perce  相似文献   

Atlantic Ocean sea-surface temperatures and regional streamflow variability in the Adour-Garonne basin,France     

Abdoul Aziz Oubeidillah  Glenn Tootle  Sally-Rose Anderson 《水文科学杂志》2013,58(3):496-506

Abstract

The identification of Atlantic Ocean (AO) climatic drivers may prove valuable in long lead-time forecasting of streamflow in the Adour-Garonne basin in southwestern France. Previous studies have identified the Atlantic Multidecadal Oscillation (AMO) and the North Atlantic Oscillation (NAO) as drivers of European hydrology. The current research applied the singular value decomposition (SVD) statistical method to AO sea-surface temperatures (SSTs) to identify the primary AO climatic drivers of the Adour-Garonne basin streamflow. Annual and seasonal streamflow volumes were selected as the hydrological response, while average AO SSTs were calculated for three different 6-month averages (January–June, April–September and July–December) for the year preceding streamflow. The results identified a region along the Equator as the probable driver of the basin streamflow. Additional analysis evaluated the influence of the AMO and NAO on Adour-Garonne basin streamflow.

Editor Z.W. Kundzewicz; Associate editor H. Aksoy

Citation Oubeidillah, A.A., Tootle, G. and Anderson, S.-R., 2012. Atlantic Ocean sea-surface temperatures and regional streamflow variability in the Adour-Garonne basin, France. Hydrological Sciences Journal, 57 (3), 496–506.  相似文献   

Chromium(VI) and cadmium removal from aqueous solutions using the BAZLSC/cockle shell constructed wetland system: optimization with RSM     

A. Mojiri  R. M. Tajuddin  Z. Ahmad  L. Ziyang  H. A. Aziz  N. M. Amin 《International Journal of Environmental Science and Technology》2018,15(9):1949-1956

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Environmental impact assessment of a new nuclear power plant (NPP) based on atmospheric dispersion modeling     

Abubakar Sadiq Aliyu  Ahmad Termizi Ramli  Muneer Aziz Saleh 《Stochastic Environmental Research and Risk Assessment (SERRA)》2014,28(7):1897-1911

The US Environmental Protection Agency’s short-range atmospheric dispersion model (AERMOD 12345) is a good candidate for radiological dose calculations to the general public and the environment. It advanced capability should provide better confidence in the accuracy of offsite dose and risk assessment. The code has been used to compute the scaling factors for air concentration and ground level deposition of fission products based on routine and hypothetical accident releases from the NPP site in Geregu, Nigeria (7°33′N, 6°41′E). All computations were within the 16 km emergency planing zone of a generic reactor design considered by the study. The scaling factors have been used to assess the potential environmental risk of the NPP using an integrated approach to the assessment and management of environmental risks from ionizing radiation (D-ERICA). Obtained results should provide baseline information for decision making in terms of operation license provision for the pioneer NPP.  相似文献   

Detection of multiple potentially pathogenic bacteria in Matang mangrove estuaries,Malaysia     

Aziz Ghaderpour  Khairul Nazrin Mohd Nasori  Li Lee Chew  Ving Ching Chong  Kwai Lin Thong  Lay Ching Chai 《Marine pollution bulletin》2014

The deltaic estuarine system of the Matang Mangrove Forest Reserve of Malaysia is a site where several human settlements and brackish water aquaculture have been established. Here, we evaluated the level of fecal indicator bacteria (FIB) and the presence of potentially pathogenic bacteria in the surface water and sediments. Higher levels of FIB were detected at downstream sampling sites from the fishing village, indicating it as a possible source of anthropogenic pollution to the estuary. Enterococci levels in the estuarine sediments were higher than in the surface water, while total coliforms and E. coli in the estuarine sediments were not detected in all samples. Also, various types of potentially pathogenic bacteria, including Klebsiella pneumoniae, Serratia marcescens and Enterobacter cloacae were isolated. The results indicate that the Matang estuarine system is contaminated with various types of potential human bacterial pathogens which might pose a health risk to the public.  相似文献