Formate and acetate as recorded in a mid－latitude glacier in west China

Formic (HCOOH) and acetic (CH3COOH) acids are the chief carboxylic compounds in the troposphere[1]. Although weak acids, they contribute significantly to the free acidity, ionic balance of precipitation and the chemical reactions in the atmosphere, especially in the remote areas[2—4]. General sources for formate and acetate have been identified in the past 3 decades although a satisfactory source attribution is lacking to explain atmospheric observations[5]. Possible sources include veget…     

Evidence of the 1991 Pinatubo volcanic eruption in South Polar snow

Traces of tephra and increased sulfate (SO ₄ ²⁻ ) concentrations were identified in the 1992–1994 snow layers in 2 firn cores from South Pole. The deposition of the Pinatubo SO ₄ ²⁻ aerosol was delayed due to the long transport to the high south latitudes and its initial existence at high altitudes in the Antarctic atmosphere. Electron microscopic analyses show that the element composition of the tephra is identical to that of volcanic ash found near the Pinatubo volcano in Philippines. Detailed stratigraphic snow sampling resolved the Pinatubo signal from that of Cerro Hudson eruption during August 1991 in Chile. The South Pole sulfate flux from Pinatubo is calculated to be (10.9±1.1) kg·km⁻², while the Hudson sulfate flux is (3.2±1.1) kg·km⁻². This information will be useful to estimating the magnitudes of the past volcanic eruptions recorded in Antarctic ice core.     

Spectrofluorimetric determination of magnesium (II) with 7-(8-Hydroxy-3, 6-disulfonaphthylazo)-8-hydroxyquinoline-5-sulfonic acid

A new fluorescent reagent, 7-(8-hydroxy-3, 6-disulfonaphthylazo)-8-hydroxyquinoline-5-sulfonic acid (HDNHQ) for the determination of magnesium has been developed. It reacted with magnesium to form a 1∶1 fluorescent complex withλ _ex/λ _em immediately at room temperature in ammonia-ammonium chloride buffer (pH 10.7). A linear relationship was obtained in the magnesium concentration range of 0–160 ng·mL⁻¹ with the detection limit of 0.04 ng·mL⁻¹. The proposed method was simple, rapid and sensitive. It has been successfully applied to the determination of trace magnesium in blood serum with recoveries of 103.75% and 98.16%, respectively. Foundation item: Supported by the Zi-Qiang Foundation of Wuhan University Biography: Zhang Xian (1975-), female, Ph. D candidant, research direction: organic reagent synthesis and analysis.     

The 4700 aB.P. volcanic signal detected in Vostok BH8 ice core, Antarctica

The detailed electrical conductivity measuremerit （ECM）, trace chemical compositions and microparticles concentration analysis are performed for BH8 ice core from the depth of 126.0m to 130.0m at Vostok Station. At depth 128.7m, a volcanic signal 4726 a B.P. is detected. The volcanic sulphate flux is 95.8 kg·km^-2, sulphate peak concentration 1352.8 ng·g^-1, duration time about 10.1 years, comparable with some well-known volcanic events. The results indicate that it seems to be a relatively large scale, long lasting volcanic signal with farther volcanic origin.     

Estimation of soil respiration in a paddy ecosystem in the subtropical resion of China

Water vapor, energy exchange, and CO2 flux were measured continuously from 2003 to 2005 using the eddy covariance technique in a paddy ecosystem in the subtropical region of China. The CO2 fluxes at nighttime during fallow periods （from middle October to late April） were used to analyze the dynamics of soil respiration and its relationship with soil temperature, and to simulate the annual dynamics of soil respiration in paddy ecosystems. The variation of soil respiration showed a clear seasonal pattern. The soil respiration rates at night during the fallow periods were 52--398 mg· m^-2· h^-1, and exponentially correlated （P〈0.001） with soil temperatures at different depths of soil （5, 10, and 20 cm）, particularly the temperature measured at a depth of 5 cm. Based on the simulated exponential equations developed, annual average soil respiration rates and total soil respiration of paddy soil in the subtropical region of China were estimated to be 178.5--259.9 mg· m^-2· h^-1 and 1.56--2.28 kg· m^-2· a^-1, respectively. The simulation equations can be applied to evaluating soil respiration in paddy ecosystems during the rice-growing season.     

Using 137Cs tracing technique to estimate wind erosion rates in the typical steppe region,northern Mongolian Plateau

Wind erosion is one of the major factors of land degradation in the typical steppe region, northern Mongolian Plateau. Using ^137Cs tracing technique, we estimated the wind erosion rates of different pastures and abandoned farmland at Bayannur and Karakorum in Mongolia. The pastures and cutting grassland at Bayannur were slightly eroded by wind, with the rates of 64.58-169.07 t·km^-2.a^-1. The abandoned farmland in Karakorum, however, was strongly eroded by wind, with annual surface soil loss of 4.05 mm. a^-1, and wind erosion rates up to 6723.06 t· km^-2. a^-1. The total loss of surface soil due to wind erosion has been 17.4 cm since the cultivation of the steppe land in the 1960s. The wind ero- sion rate at the abandoned farmland was much higher than that at the typical steppe sites, showing that the cultivation led to serious wind erosion in the typical steppe region, northern Mongolian Plateau. By contrast, traditional livestock grazing resulted in less disturbance to the surface soil, and did not induce to devastating wind erosion, which plays an important role in maintaining the stability of the steppe ecosystem in the northern Mongolian Plateau.     

Discovery of the superlarge gallium ore deposit in Jungar, Inner Mongolia, North China

Gallium, Ge, V, and U are the associated valuable elements in coal. From the 1950s to the 1970s, some researchers in the departments of coal industry and mineral resources of China investigated these elements in coal during geological explorations. The enrichment mechanism and the environmental influence of trace elements in coal have been deeply studied in recent twenty years. With respect to the ore-forming theories and practical utilizations of metals in coal, germanium was furthest studi…     

Determination of ciprofloxacin hydrochloride in pharmaceutical preparation and biological fluid by Rayleigh light scattering technique

A highly sensitive and simple Rayleigh light scattering (RLS) method for determination of ciprofloxacin hydrochloride has been developed. Ciprofloxacin hydrochloride (CPFH) reacted with tetraphenylboron sodium(TPB) to form an ion-association complex in pH 5.31 aqueous solution, which resulted in a significant enhancement of the RLS intensity, which was linear with the concentration of CPFH in the range of 12.7–419 ng·mL⁻¹. The limit of detection for CPFH was 6.99 ng·mL⁻¹. The method is simple, highly sensitive and selective within a wide linear range. Appliying this method to determination of ciprofloxacin hydrochloride in pharmaceutical preparations and biological fluids obtained satisfactory results. Foundation item: Supported by the National Natural Science Foundation of China(20675059) and Research Foundation of Leshan Teachers’ College, China (Z0625)     

Identification of the deposited layers in landslides reservoir and investigation of the sediment yields during the later sixteenth century on the Hill Loess Plateau,China

There are many sediment trapping reservoirs in the Hill Loess Plateau. The Huangtuwa small catchment is selected as a research field where samples were collected in a sediment deposit profile with a vertical length of 12.73 m. By the variation of fine particle content and pollen concentration, 54 flood couples were identified. Taking the freeze-thawing disturbed texture as the sign of the latest flood couple in a year, it is ascertained that those 54 floods should happen in 31 years. Using pyramid volume calculation formula, the sediment yields of flood ranged between 716-30376 t· km^-2, The average sediment yield was 7106 t· km^-2, The annual sediment yields varied between 968-55579 t· （km^2· a）^-1, and the average value is 12629 t· （km^2· a）^-1. Compared with the modern annual sediment discharge of the Huaining River, the erosion rate in the Huangtuwa region 450 years ago was similar to the modern erosion rate. In the period from the 27th year to the 31st year, the average annual sediment yield increased sharply to 31309 t· （km^2· a）^-1. It implied that re-reclamation of the abandoned land in the catchment since the landslide disaster, where vegetation had rehabilitated already, caused very severe soil erosion in the catchment.     

Estimate of carbonate production by scleractinian corals at Luhuitou fringing reef, Sanya, China

Carbonate production by scleractinian corals not only maintains coral reef growth, but also represents an important source of atmospheric carbon dioxide. In this paper the carbonate production by scler-actinian corals at Luhuitou fringing reef, Sanya, Hainan Island, China, is investigated with an ecological census-based method. Averaged carbonate production is 1.16 ± 0.55 kg·m-2·a-1 and 3.52 ± 1.32 kg·m-2·a-1 on the reef flat and reef slope, respectively, depending on the composition and distribution of cor...     

Electrochemical properties of LiNi<Subscript>0.5</Subscript>Mn<Subscript>1.3</Subscript>Ti<Subscript>0.2</Subscript>O<Subscript>4</Subscript>/Li<Subscript>4</Subscript>Ti<Subscript>5</Subscript>O<Subscript>12</Subscript> cells

Spinel compounds LiNi_0.5Mn_1.3Ti_0.2O₄ (LNMTO) and Li₄Ti₅O₁₂ (LTO) were synthesized by different methods. The particle sizes of LNMTO and LTO are 0.5–2 and 0.5–0.8 μm, respectively. The LNMTO/LTO cell exhibits better electrochemical properties at both a low current rate of 0.2C and a high current rate of 1C. When the specific capacity was determined based on the mass of the LNMTO cathode, the LNMTO/LTO cell delivered 137 mA·h·g⁻¹ at 0.2C and 118.2 mA·h·g⁻¹ at 1C, and the corresponding capacity retentions after 30 cycles are 88.5% and 92.4%, respectively.     

Trace determination of zirconium using anodic adsorptive voltammetry at a carbon paste electrode modified with multi-walled carbon nanotubes

A carbon paste electrode modified with multi-walled carbon nanotubes （MWCNT） was prepared and the determination of ultra trace amount of zirconium based on the anodic adsorptive voltammetry of the zirconium-calcium-alizarin red S mix-polynuclear complex is described in this paper for the first time. The results showed that the sensitivity and the selectivity of the method are excellent. The second derivative linear scan voltammograms of the complex were recorded by polarographic analyzer from 200 to 1200 mV （vs. SCE） and it was found that the complex can be adsorbed on the surface of the electrode, yielding a peak at about 840 mV, corresponding to the oxidation of ARS in the complex. The peak current increases linearly with Zr （IV） concentration in the range of 6.0×10^-12--6.0×10^-11 mol. L^-1 （accumulation time 120 s）, 6.0×10^-11--2.0×10^-9 mol. L-1 （accumulation time 90 s） and 2.0×10^-9--1.0×10^-7 mol. L^-1 （accumulation time 60 s） and the detection limit （S/N = 3） is 2.0×10^-12 mol. L^-1 （accumulation time 180 s）. The procedure has been successfully applied to the determination of zirconium in the ore samples.     

Pollen flux and vertical dispersion in coniferous and deciduous broadleaved mixed forest in the Changbai Mountains

The pollen flux in coniferous and deciduous broadleaved mixed forest in the Changbai Mountains is presented in one year's experiments. The results indicate that arboreal pollen percentages are more than 65% and pollen flux is higher than 5000 grain·cm-2·a-1,while less than 2% and lower than 1000 grain·cm-2·a-1 for shrubby pollen,and less than 20% and lower than 3000 grain·cm-1·a-1 for herbaceous pollen for most samples at different heights. The pollen assemblages are similar to those in the samples under 8 m height where Pinus and Ouercus are dominant and followed by the few non-local pollen types,and Fraxinus percentages are high with a few non-local pollen types at 16 m to 32 m height as well as non-local pollen clearly increased at 40 m height. Comparisons between pollen assemblages and vegetation composition suggest that similarities are higher for pollen trap samples than for surface moss samples.     

Export and remineralization of POM in the Southern Ocean and the South China Sea estimated from 210Po/210Pb disequilibria

Disequilibria between ^210Po and ^210Pb in the upper water and their potential applications as a proxy of particle export and remineralization were examined in the Southern Ocean （station IV3） and the South China Sea （NS44）. ^210po was deficit in surface waters but excessive relative to ^210Pb in subsurface waters. Good positive correlation between ^210Po and particulate organic carbon （POC） indicated deficits and excess of ^210Po resulted from particulate organic matter （POM） export and remJneralization respectively, which was also supported by the decreased δ^13C and increased δ^15N downwards as a result of particle remineralization. On the basis of ^210Po/^210Pb box-model, POC export flux out of the surface waters were 1.2 mmol C. m^-2. d^-1 and 2.3 mmol C. m^-2. d^-1 for station NS44 and IV3, respectively. In the subsurface waters, remineralization fluxes of ^210Po were 0.062 Bq. m^-2.d^-1 and 0.566 Bq.m^-2.d^-1 for station NS44 and IV3 along with the recycle efficiency of 52±26% and 119±52%, respectively. Remineralized fluxes of POM derived from ^210Po and exported POC were 0.6 mmol C.m^-2.d^-1 and 2.7 mmol C. m^-2. d^-1 for NS44 and IV3. This study suggested that ^210Po was a powerful tracer of particle export and remineralization.     

Preliminary evidence indicating Dome A （Antarctica） satisfying preconditions for drilling the oldest ice core

Lowest temperature and snow accumulation rate are preconditions for retrieving the oldest ice core from the polar ice sheets. The 10-m depth firn temperature at Dome A, the summit of the Antarctic Ice Sheet, recorded by an automatic weather station （AWS） was -58.3℃ in 2005 and -58.2℃ in 2006, respectively. The 10-m firn temperature is an approximation of the annual mean air temperature （AMAT）, and this is the lowest AMAT that has been recorded on the surface of the Earth. The stable isotopic ratios （δ^18O and δD） of surface snow at Dome A are also lower than at other ice sheet domes along the East Antarctic Ice Divide such as Dome C, Dome F, Dome B and Vostok. These facts indicate that Dome A is the ＂pole of cold＂ on the Earth. The total amount of snow accumulation rate in 2005 and 2006 was only 0.16 cm, equaling 0.016 m water equivalent per year, the lowest precipitation ever recorded from Antarctica. Preliminary evidences indicate that Dome A is a candidate site for recovering the oldest ice core.     

Synthesis, Characterization and Properties of LiFePO4/C Cathode Material

Lithium iron phosphate coated with carbon (LiFePO₄/C) was synthesized by improved solid-state reaction using comparatively lower temperature and fewer sintering time. The carbon came from citric acid, which acted as a new carbon source. It was characterized by thermogravimetry and differential thermal analysis (TG/DTA), X ray diffractometer (XRD), Element Analysis (EA) and Scanning electron microscope (SEM). We also studied the electrochemical properties of the material. The first discharge capacity of the LiFePO₄/C is 121 mAh·g⁻¹ at 10 mA·g⁻¹, at room temperature. When the current density increased to 100 mA·g⁻¹, the first discharge capacity decreased to 110 mAh·g⁻¹ and retained 95% of the initial capacity after 100 cycles. The LiFePO₄/C obtained shows a good electrochemical capacity and cycle ability at a large current density. Foundation item: Supported by the National Natural Science Foundation of China (20071026) Biography: ZHOU Xin-wen (1980-), male, Master, research direction: inorganic material chemistry.     

Petrographic and geochemical characterization of seep carbonate from Alaminos Canyon,Gulf of Mexico

Seep carbonates were collected from the Alaminos Canyon lease area, Gulf of Mexico. The carbonates are present as slabs and blocks. Bivalve shell and foraminifer are the dominant bioclasts in carbonate. Pores are common and usually filled with acicular aragonite crystals. XRD investigation shows that aragonite is the dominate mineral （98%）. Peloids, clotted microfabirc and botryoidal aragonite are developed in carbonate and suggest a genesis linked with bacterial degradation of the hydrocarbons. The δ^13C value of bioclasts in carbonate is from -4.9‰ to -0.6‰, indicating that the carbon source is mainly from sea water as well as the small portion incorporation of the seep hydrocarbon. The microcrystalline and sparite aragonite shows the δ^13C value from -31.3‰ to -23.4‰, suggesting that their carbon is derived mainly from microbial degradation of crude oil. ^14C analyses give the radiocarbon age of about 10 ka. Rare earth elements （REE） analyses of the 5% HNO3-treated solution of the carbonates show that the total REE content of the carbonates is low, that is from 0.752 to 12.725 μg·g^-1. The shale-normalized REE patterns show significantly negative Ce anomalies. This suggests that cold seep carbonate is most likely formed in a relatively aerobic environment.     

An acetylcholinesterase inhibitor, 3-benzidino-5-methyl-6-phenylpyridazine, blocking outward potassium currents in acutely isolated rat hippocampal pyramidal neurons

3-benzidino-5-methyl-6-phenylpyridazine (BMP) inhibited electric eel acetylcholinesterase (AChE), with IC50 being 0.58 μmol·L-1. As an AChE inhibitor, the effects of BMP on delayed rectifier potassium current (IK(DR)) and transient outward potassium current (IK(A)) in acutely isolated rat hippocampal pyramidal neurons were studied using the whole cell patch-clamp technique. BMP (0.1―50 μmol·L-1) inhibited IK(DR) and IK(A) in a concentration-dependent and voltage-independent manner. The IC50 value for the bl...     

REE composition in scheelite and scheelite Sm-Nd dating for the Xuebaoding W-Sn-Be deposit in Sichuan

The scheelite with large size and euhedral shape from Xuebaoding, Sichuan Province is an ideal min- eral to study REE patterns and Sm-Nd dating of non-gold deposits. The scheelite has diameters of 1― 10 cm and colors of pale beige to deep orange. Most of these scheelites occur in association with beryl, cassiterite and muscovite. The rare earth elements indicate that scheelite samples from Xuebaoding W-Sn-Be deposits contain high concentrations of rare earth elements with total ΣREE Y contents in the range of 369―1725 μg·g?1 and nearly all of these scheelite samples are enriched in LREE and depleted in HREE and have negative Eu anomalies. The REE patterns of the scheelites are similar to those of A-type granite with obvious tetrad effect, similar to that of type II scheelites. Based on reported fluid inclusion studies, the mineralizing-fluid of the Xuebaoding W-Sn-Be deposit indicates low Na activity. The REE patterns of the scheelite are probably controlled by partition coefficient in hydrothermal fluid. In the 147Sm/144Nd-143Nd/144Nd diagram, the scheelites show a linear array corresponding to an isochron age of 182.0±9.2 Ma (MSWD = 0.52). The Sm-Nd age represents the formation age of the scheelite and can indicate that the W, Sn and Be mineralization at Xuebaoding took place in the Early Yanshanian. The Sm-Nd dating result is important for the study of the multi-metal resources in western Sichuan Province.     

The climate influence of anthropogenic land-use changes on near-surface wind energy potential in China

There is considerable interest in the potential impact of climate change on wind energy in China. The climate change of near-surface wind energy potential in China under the background of global warming and its association with anthropogenic land-use changes are investigated by calculating the difference in surface wind speeds between the NCEP/NCAR reanalysis data and the observations since the reanalysis dataset contains the influence of large-scale climate changes due to greenhouse gases, it is less sensitive to regional surface processes associated with land types. The surface wind data in this study consist of long-term observations from 604 Chinese Roution Meteorological Stations and the NCEP/NCAR reanalysis data from 1960-1999. The results suggest that the observed mean wind speeds significantly weakened and the near-surface wind power trended downward due to urbanization and other land-use changes in the last 40 years. The mean wind energy weakened by -3.84 W·m^-2 per decade due to the influence of anthropogenic land-use change, which is close to the observed climate change （-4.51 W·m^-2/10 a）.