The Hα-cyclonic spectra of a flare loop system on 1981 April 27

The data such as the H-spectrum-spectroheliographic (SSHG) observations, the H-chromospheric observations, etc., of a flare loop prominence which occurred on the western solar limb on 1981 April 27 have been obtained at Yunnan Observatory. The distribution of the internal motions and the macroscopical motion of the flare loop prominence with time and space in the course of its eruption and ascension is derived from the comprehensive analysis of the data. The possible physical pictures and the instability of the motions of the loop are inferred and discussed.     

Time scale of an early to mid-Paleozoic orogenic cycle of the long-lived Central Asian Orogenic Belt, Inner Mongolia of China: Implications for continental growth

We present a detailed, new time scale for an orogenic cycle (oceanic accretion–subduction–collision) that provides significant insights into Paleozoic continental growth processes in the southeastern segment of the long-lived Central Asian Orogenic Belt (CAOB). The most prominent tectonic feature in Inner Mongolia is the association of paired orogens. A southern orogen forms a typical arc-trench complex, in which a supra-subduction zone ophiolite records successive phases during its life cycle: birth (ca. 497–477 Ma), when the ocean floor of the ophiolite was formed; (2) youth (ca. 473–470 Ma), characterized by mantle wedge magmatism; (3) shortly after maturity (ca. 461–450 Ma), high-Mg adakite and adakite were produced by slab melting and subsequent interaction of the melt with the mantle wedge; (4) death, caused by subduction of a ridge crest (ca. 451–434 Ma) and by ridge collision with the ophiolite (ca. 428–423 Ma). The evolution of the magmatic arc exhibits three major coherent phases: arc volcanism (ca. 488–444 Ma); adakite plutonism (ca. 448–438 Ma) and collision (ca. 419–415 Ma) of the arc with a passive continental margin. The northern orogen, a product of ridge-trench interaction, evolved progressively from coeval generation of near-trench plutons (ca. 498–461 Ma) and juvenile arc crust (ca. 484–469 Ma), to ridge subduction (ca. 440–434 Ma), microcontinent accretion (ca. 430–420 Ma), and finally to forearc formation. The paired orogens followed a consistent progression from ocean floor subduction/arc formation (ca. 500–438 Ma), ridge subduction (ca. 451–434 Ma) to microcontinent accretion/collision (ca. 430–415 Ma); ridge subduction records the turning point that transformed oceanic lithosphere into continental crust. The recognition of this orogenic cycle followed by Permian–early Triassic terminal collision of the CAOB provides compelling evidence for episodic continental growth.     

Timing of the Nihewan formation and faunas

Magnetostratigraphic dating of the fluvio-lacustrine sequence in the Nihewan Basin, North China, has permitted the precise timing of the basin infilling and associated Nihewan mammalian faunas. The combined evidence of new paleomagnetic findings from the Hongya and Huabaogou sections of the eastern Nihewan Basin and previously published magnetochronological data suggests that the Nihewan Formation records the tectono-sedimentary processes of the Plio-Pleistocene Nihewan Basin and that the Nihewan faunas can be placed between the Matuyama-Brunhes geomagnetic reversal and the onset of the Olduvai subchron (0.78-1.95 Ma). The onset and termination of the basin deposition occurred just prior to the Gauss-Matuyama geomagnetic reversal and during the period from the last interglaciation to the late last glaciation, respectively, suggesting that the Nihewan Formation is of Late Pliocene to late Pleistocene age. The Nihewan faunas, comprising a series of mammalian faunas (such as Maliang, Donggutuo, Xiaochangliang, Banshan, Majuangou, Huabaogou, Xiashagou, Danangou and Dongyaozitou), are suggested to span a time range of about 0.8-2.0 Ma. The combination of our new and previously published magnetostratigraphy has significantly refined the chronology of the terrestrial Nihewan Formation and faunas.     

印度共和国主要矿产资源及其地质特征

印度共和国是南亚地区矿产资源比较丰富的国家,铁矿探明储量175.7亿吨;铝土矿探明储量26.54亿吨;锰矿探明储量1.35亿吨;铬铁矿储量5900万吨;重晶石储量3000万吨。目前,全印度已开发了89种矿产资源,其中有52种非金属矿产,11种金属矿产,22种稀有金属矿产,4种能源矿产。全国生产矿     

Impact of land use covers upon karst processes in a typical Fengcong depression system of Nongla, Guangxi, China

The direction and intensity of karst processes can be deeply affected by soil physical and chemical variations which were resulted from land use. Taking Nongla Fengcong depression area, Mashan County, Guangxi as an example, authors discussed the impact of land use on karst processes based on the data of field limestone tablet. The results showed that the corrosional rates at varied soil depth are quite different. Corrosional rate in woodland and orchard is mostly bigger than 20 mg/a, which is much higher than that in tilled land and shrub. Generally, corrosional rate decreased from orchard, woodland, tilled land, fallow land and shrub successively, in which soil organic matter (OM) and soil pH are two major controlling factors: corrosion process is controlled remarkably by soil OM in woodland and orchard. The higher the organic matter content is and the less the pH value is, the higher the corrosional rate is. Owing to lower organic matter content, the corrosional rate is mainly affected by soil CO₂ in tilled land and shrub.     

Modeling on adsorption–desorption of trace metals to suspended particle matter in the Changjiang Estuary

The uptake and release of trace metals (Cu, Ni, Zn, Cd, and Co) in estuaries are studied using river and sea end-member waters and suspended particulate matter (SPM) collected from the Changjiang Estuary, China. The kinetics of adsorption and desorption were studied in terms of environmental factors (pH, SPM loading, and salinity) and metal concentrations. The uptake of the metals studied onto SPM occurred mostly within 10 h and reached an asymptotic value within 40 h in the Changjiang Estuary. As low pH river water flows into the high pH seawater and the water become more alkaline as it approaches to the seaside of estuary, metals adsorb more on SPM in higher pH water, thus, particulate phase transport of metal become increasingly important in the seaward side of the estuary. The percentage of adsorption recovery and the distribution coefficients for trace metals remained to be relatively invariable and a significant reduction only occurred in very high concentrations of metals (>0.1 mg L⁻¹). The general effect of salinity on metal behavior was to decrease the degree of adsorption of Cu, Zn, Cd, Co, and Ni onto SPM but to increase their adsorption equilibrium pH. The adsorption–desorption kinetics of trace metals were further investigated using Kurbatov adsorption model. The model appears to be most useful for the metals showing the conservative behavior during mixing of river and seawater in the estuary. Our work demonstrates that dissolved concentration of trace metals in estuary can be modeled based on the metal concentration in SPM, pH and salinity using a Kurbatov adsorption model assuming the natural SPM as a simple surfaced molecule.     

Natural radioactivity in sediment of Wei River,China

The concentrations of natural radionuclides in sediment of Wei River of China were measured using γ-ray spectrometry with the aim of estimating the radiation hazard as establishing a database for radioactivity levels of river sediment of China. The activity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K in sediment samples ranged from 10.4 to 39.9 Bq kg⁻¹, 15.3 to 54.8 Bq kg⁻¹ and 514.8 to 1,175.5 Bq kg⁻¹, respectively. The concentrations of these radionuclides were compared with the typical world values and the average activities of Chinese soil and Shaanxi soil. Radium equivalent activity (Ra_eq), external hazard index (H _ex) and representative level index (I _γr) were calculated for the samples to assess the radiation hazards arising due to the use of these sediment samples in the construction of dwellings. All the sediment samples have Ra_eq lower than the limit of 370 Bq kg⁻¹, H _ex less than unity and I _γr close to 1 Bq kg⁻¹. The overall mean outdoor terrestrial gamma dose rate is 64.8 nGy h⁻¹ and the corresponding outdoor annual effective dose is 0.079 mSv. None of the studied location is considered a radiological risk and sediment can be safely used in construction.     

Application of MODFLOW and geographic information system to groundwater flow simulation in North China Plain, China

MODFLOW is a groundwater modeling program. It can be compiled and remedied according to the practical applications. Because of its structure and fixed data format, MODFLOW can be integrated with Geographic Information Systems (GIS) technology for water resource management. The North China Plain (NCP), which is the politic, economic and cultural center of China, is facing with water resources shortage and water pollution. Groundwater is the main water resource for industrial, agricultural and domestic usage. It is necessary to evaluate the groundwater resources of the NCP as an entire aquifer system. With the development of computer and internet information technology it is also necessary to integrate the groundwater model with the GIS technology. Because the geological and hydrogeological data in the NCP was mainly in MAPGIS format, the powerful function of GIS of disposing of and analyzing spatial data and computer languages such as Visual C and Visual Basic were used to define the relationship between the original data and model data. After analyzing the geological and hydrogeological conditions of the NCP, the groundwater flow numerical simulation modeling was constructed with MODFLOW. On the basis of GIS, a dynamic evaluation system for groundwater resources under the internet circumstance was completed. During the process of constructing the groundwater model, a water budget was analyzed, which showed a negative budget in the NCP. The simulation period was from 1 January 2002 to 31 December 2003. During this period, the total recharge of the groundwater system was 49,374 × 10⁶ m³ and the total discharge was 56,530 × 10⁶ m³ the budget deficit was −7,156 × 10⁶ m³. In this integrated system, the original data including graphs and attribution data could be stored in the database. When the process of evaluating and predicting groundwater flow was started, these data were transformed into files that the core program of MODFLOW could read. The calculated water level and drawdown could be displayed and reviewed online.     

Wind wave-forced fine sediment erosion during the slack water periods in Hangzhou Bay,China

The shallow water wave simulation model-SWAN incorporated with a simple fine sediment erosion model is applied to Hangzhou Bay, China, to model the horizontal distribution of the maximum bottom orbital velocity and corresponding fine sediment erosion rates induced by: (1) southeasterly steady winds (5, 20 and 30 m/s), (2) southwesterly steady winds (5 and 20 m/s); (3) northwesterly steady winds (5 and 20 m/s); (4) east-southeasterly steady winds (5 and 20 m/s); (5) easterly steady winds (5 and 20 m/s) under closed and unclosed boundaries; and (6) unsteady winds during the slack water periods. Results suggest: (1) the steady wind wave-induced maximum bottom orbital velocities and corresponding fine sediment erosion rates generally increased with the increasing steady winds; (2) closed and unclosed boundary conditions had more significant influences on modeled fine sediment erosion rates under 5 m/s easterly steady winds than 20 m/s; and (3) steady and unsteady wind wave-induced maximum bottom currents could be significant in eroding fine sediment bed in Hangzhou Bay. The results show implications for geomorphology, sedimentology, coastal erosion, and environmental pollution mitigation in Hangzhou Bay.     

Environmental contamination of Zn,Cd, Ni,Cu, and Pb from industrial areas in Hamadan Province,western Iran

Eleven surface soil samples from calcareous soils of industrial areas in Hamadan Province, western Iran were analyzed for total concentrations of Zn, Cd, Ni, Cu and Pb and were sequentially extracted into six fractions to determine the bioavailability of various heavy metal forms. Total Zn, Cd, Ni, Cu and Pb concentrations of the contaminated soils were 658 (57–5,803), 125.8 (1.18–1,361), 45.6 (30.7–64.4), 29.7 (11.7–83.5) and 2,419 (66–24,850) mg kg⁻¹, respectively. The soils were polluted with Zn, Pb, and Cu to some extent and heavily polluted with Cd. Nickel values were not above regulatory limits. Copper existed in soil mainly in residual (RES) and organic (OM) fractions (about 42 and 33%, respectively), whereas Zn occurred essentially as RES fraction (about 69%). The considerable presence of Cd (30.8%) and Pb (39%) in the CARB fraction suggests these elements have high potential biavailability and leachability in soils from contaminated soils. The mobile and bioavailable (EXCH and CARB) fractions of Zn, Cd, Ni, Cu, and Pb in contaminated soils averaged (7.3, 40.4, 16, 12.9 and 40.8%), respectively, which suggests that the mobility and bioavailability of the five metals probably decline in the following order: Cd = Pb > Ni > Cu > Zn.