Middle Jurassic palynomorphs of the Dalichai Formation, central Alborz Ranges, northeastern Iran: Paleoecological inferences     

DEHBOZORGI Afsaneh  SAJJADI Freshteh  HASHEMI Hossein 《中国科学:地球科学(英文版)》2013,56(12):2107-2115

Palynological data are used to draw paleoecological inferences for the Dalichai Formation,northeast of Semnan,northeastern Iran.All samples examined yield well-preserved,diverse palynofloras consisting predominantly of miospores;dinoflagellate cysts,foraminiferal test linings,and fungal spores occur as minor constituents.Fifty-four species of spores(37 genera),18species of pollen(9 genera),and 16 species of dinoflagellate cysts(13 genera)are recognized.Co-occurrence of such miospore species with known vertical ranges as Klukisporites variegatus,Sellaspora asperata,Murospora florida,and Concavissimisporites verrucosus suggests a Middle Jurassic(Bajocian-Callovian)age for the host strata,thus corroborating the available paleozoological evidence.Such spore species as Klukisporites,Cyathidites,and Dictyophyllidites known to have been produced by Pterophyta dominate the palynofloras.Thus the contemporaneous coastal vegetation was characterized by predominance of Pterophyta whereas representatives of Ginkgophyta,Pteridospermophyta,Lycophyta,Coniferophyta,and Bryophyta were rarely represented.This reconstruction implies that a moist,warm climate prevailed in northeastern Iran during the Middle Jurassic(Bajocian-Callovian).This is confirmed by occurrence of fungal spores accompanied by such warm water dinoflagellate cysts as Mendicodinium groenlandicum,Pareodinia ceratophora,and Gonyaulacysta jurassica.Abundance of Amorphous Organic Matter(AOM)signifies a shallow,low-energy,dysoxic-anoxic depositional site for the host strata.Furthermore,the ratio of AOM to marine palynomorphs as well as abundance of blade-shaped to eqiudimensional opaque palynomacerals could indicate low sedimentation rate in a shallow,low-oxygenated marine environment.Additionally,occurrence of chorate dinoflagellate cysts(e.g.,Adnatosphaeridium caulleryi)and acritarchs bearing relatively long processes(e.g.,Micrhystridium)possibly suggests deepening upward in the study section.  相似文献   

Modification of MCM‐41 with Anionic Surfactant: A Convenient Design for Efficient Removal of Cationic Dyes from Wastewater     

Mohammad Ali Zanjanchi  Hassan Sajjadi  Majid Arvand  Ali Mohammad‐Khah  Bahram Ghalami‐Choobar 《洁净——土壤、空气、水》2011,39(11):1007-1013

The potential of MCM‐41 for the removal of cationic dyes from water solution was evaluated using sodium dodecyl sulfate (SDS) for the surface modification of this mesoporous material. Admicelle structures formed on the surface of the calcined MCM‐41 are capable of removing organic pollutants and cationic species from water environment. The structural, textural, and surface chemical characteristics of the prepared SDS‐modified MCM‐41 (SDS‐MCM‐41) were studied. The adsorption capacity of SDS‐MCM‐41 was evaluated for methylene blue (MB) as a target cationic dye. Equilibrium adsorption isotherm data were manipulated employing nonlinear regression analysis. The Langmuir, Freundlich, and Sips isotherm models were examined. The adsorption data were well fitted to both Langmuir and Sips isotherm models. The maximum adsorption capacity of SDS‐MCM‐41 for MB, based on Langmuir and Sips models, were 290.8 and 297.3 mg g^?1, respectively. Ethanol was found to be an effective solvent for partial regeneration of the adsorbent.  相似文献   

Assessment of climate change impacts on climate variables using probabilistic ensemble modeling and trend analysis     

Safavi  Hamid R.  Sajjadi  Sayed Mahdi  Raghibi  Vahid 《Theoretical and Applied Climatology》2017,130(1-2):635-653

Water resources in snow-dependent regions have undergone significant changes due to climate change. Snow measurements in these regions have revealed alarming declines in snowfall over the past few years. The Zayandeh-Rud River in central Iran chiefly depends on winter falls as snow for supplying water from wet regions in high Zagrous Mountains to the downstream, (semi-)arid, low-lying lands. In this study, the historical records (baseline: 1971–2000) of climate variables (temperature and precipitation) in the wet region were chosen to construct a probabilistic ensemble model using 15 GCMs in order to forecast future trends and changes while the Long Ashton Research Station Weather Generator (LARS-WG) was utilized to project climate variables under two A2 and B1 scenarios to a future period (2015–2044). Since future snow water equivalent (SWE) forecasts by GCMs were not available for the study area, an artificial neural network (ANN) was implemented to build a relationship between climate variables and snow water equivalent for the baseline period to estimate future snowfall amounts. As a last step, homogeneity and trend tests were performed to evaluate the robustness of the data series and changes were examined to detect past and future variations. Results indicate different characteristics of the climate variables at upstream stations. A shift is observed in the type of precipitation from snow to rain as well as in its quantities across the subregions. The key role in these shifts and the subsequent side effects such as water losses is played by temperature.

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Metal concentrations in selected tissues and main prey species of the annulated sea snake (Hydrophis cyanocinctus) in the Hara Protected Area, northeastern coast of the Persian Gulf, Iran     

Rezaie-Atagholipour M  Riyahi-Bakhtiari A  Sajjadi M  Yap CK  Ghaffari S  Ebrahimi-Sirizi Z  Ghezellou P 《Marine pollution bulletin》2012,64(2):416-421

This study is the first detailed ecotoxicological study of the annulated sea snake, Hydrophis cyanocinctus. Concentrations of lead, cadmium, nickel and vanadium were evaluated in muscle, liver, kidney, skin and blood of the annulated sea snake (H. cyanocinctus) and in the whole bodies of its main prey species (Periophthalmus waltoni and Boleophthalmus dussumieri) in the Hara Protected Area, the Persian Gulf. The mean concentrations of lead and vanadium were highest in the kidney, which identified the kidney as a target organ for metals in sea snakes as it is in other reptilian groups. Mean concentrations of cadmium and nickel were highest in the liver and skin, respectively. Mean cadmium concentrations were significantly higher in the liver compared to prey species, which indicated that prey items may be a source of cadmium for the annulated sea snake in the study area. Data presented here may be considered as a baseline for further ecotoxicological studies in sea snakes.  相似文献