Yangtze- and Taiwan-derived sediments on the inner shelf of East China Sea

X-ray diffraction (XRD) mineralogical and grain-size analyses indicate that inner continental shelf sediments in the East China Sea (ECS) represent a unique mixing of clays derived from the Yangtze River and silts/sands from small western Taiwanese rivers. Taiwanese (e g., Choshui) clays (< 2 mu m) display no smectite but the best illite crystallinity and are only distributed along southeastern Taiwan Strait. Both Yangtze and Taiwanese river clays are illite-dominated, but the poor illite crystallinity and the presence of smectite and kaolinite indicate that Taiwan Strait clays are mainly Yangtze-dominated. In contrast, medium silts (20-35 mu m) and very fine sands (63-90 mu m) in the Taiwan Strait are characterized by low feldspar/quartz, low K-feldspar/plagioclase and high kaolinite/quartz, indicating their provenance from Taiwanese rivers. Taiwanese silts and sands are introduced primarily by the way of typhoon-derived floods and transported northward by the Taiwan Warm Current during summer-fall months. Yangtze clays, in contrast, are widely dispersed southward about 1000 km to the western Taiwan Strait, transported by the China Coastal Current during winter-spring months Since most Taiwan Strait samples were collected in May 2006, clay results in this paper might only represent the winter-spring pattern of the dispersal of Yangtze sediments. (C) 2009 Elsevier Ltd. All rights reserved.

Recent 2000-year geological records of mud in the inner shelf of the East China Sea and their climatic implications

AXIS(14)C dating and grain-size analysis for Core DD2, located at the north of the Yangtze River-derived mud off the Zhejiang-Fujian coasts in the inner shelf of the East China Sea, provide us a high-resolution grain-size distribution curve varying with depth and time. Data in the upper mud layer of Core DD2 indicate that there are at least 9 abrupt grain-size increasing in recent 2000 years, with each corresponding very well with the low-temperature events in Chinese history, which might result from the periodical strengthening of the East Asian Winter Monsoon (EAWM), including the first-revealed maximum temperature lowering event at around 990 a BP. At the same time, the finer grain size section in Core DD2 agrees well with the Sui-Tang Warming Period (600-1000 a AD) defined previously by Zhu Kezhen, during which the climate had a warm, cold and warm fluctuation, with a dominated cooling period of 750-850 a AD. The Little Ice Age (LIA) can also be identified in the core. It starts around 1450 a AD and was followed by a subsequent cooling events at 1510, 1670 and 1840 a AD. Timing of these cold events revealed here still needs to be further verified owing to some current uncertainty of dating we used in this study.

Records of the East Asian winter monsoon from the mud area on the inner shelf of the East China Sea since the mid-Holocene

AMS(14)C dating and analysis of grain size, major elements and clay minerals were applied to Core MZ01 from the mud area on the inner shelf of the East China Sea. Based on the environmentally sensitive grain size, clay mineral and major element assemblages, the history of the East Asia winter monsoon since the mid-Holocene could be reconstructed. These three proxies, mean grain size (>9.71 mu m), chemical index of alteration (CIA) and ratio of smectite to kaolinite in particular, show similar fluctuation patterns. Furthermore, 10 extreme values corresponding to the contemporary cooling events could be recognized since the mid-Holocene; these extreme values are likely to have been caused by the strengthening of the East Asia winter monsoon. The cooling events correlated well with the results of the delta O-18 curves of the Dunde ice core and GISP2, which therefore revealed a regional response to global climate change. Four stages of the East Asia winter monsoon were identified, i.e. 8300-6300 a BP, strong and unstable; 6300-3800 a BP, strong but stable; 3800-1400 a BP, weak and unstable; after 1400 a BP, weak but stable.

Numerical modeling of water wave interaction with a soft mud bed

A vertical 2-D numerical model is presented for simulating the interaction between water waves and a soft mud bed. Taking into account nonlinear rheology, a semi-empirical rheological model is applied to this water-mud model, reflecting the combined visco-elasto-plastic properties of soft mud under such oscillatory external forces as water waves. In order to increase the resolution of the flow in the neighborhood of both sides of the inter-surface, a logarithmic grid in the vertical direction is employed for numerical treatment. Model verifications are given through comparisons between the calculated and the measured mud mass transport velocities as well as wave height changes.

Corrosion of steel structures in sea-bed sediment

Seabed sediment (SBS) is a special soil that is covered by seawater. With the developments in marine oil exploitation and engineering, more and more steel structures have been buried in SBS. SBS corrosion has now become a serious problem in marine environment and an important issue in corrosion science. In this paper, approach in the field of SBS corrosion is reviewed. Electrochemical and microbial corrosion factors, corrosion mechanism, measurement of metal corrosion rate, corrosion evaluation and prediction of corrosion are also discussed here.

CO2H2O and energy exchange of an Inner Mongolia steppe ecosystem during a dry and wet year

We used an eddy covariance technique to measure evapotranspiration and carbon flux over two very different growing seasons for a typical steppe on the Inner Mongolia Plateau, China. The rainfall during the 2004 growing season (344.7 mm) was close to the annual average (350.43 mm). In contrast, precipitation during the 2005 growing season was significantly lower than average (only 126 mm). The wet 2004 growing season had a higher peak evapotranspiration (4 mm day(-1)) than did the dry 2005 growing season (3.3 mm day(-1)). In 2004, latent heat flux was mainly a consumption resource for net radiation, accounting for similar to 46% of net radiation. However, sensible heat flux dominated the energy budget over the whole growing season in 2005, accounting for 60% of net radiation. The evaporative rate (LE/R-n) dropped by a factor of four from the non-soil stress to soil water limiting conditions. Maximum half-hourly CO2 uptake was -0.68 mg m(-2) s(-1) and maximum ecosystem exchange was 4.3 g CO2 m(-2) day(-1) in 2004. The 2005 drought growing stage had a maximum CO2 exchange value of only -0.22 mg m(-2) s(-1) and a continuous positive integrated-daily CO2 flux over the entire growing season, i.e. the ecosystem became a net carbon source. Soil respiration was temperature dependent when the soil was under non-limiting soil moisture conditions, but this response declined with soil water stress. Water availability and a high vapor pressure deficit severely limited carbon fixing of this ecosystem; thus, during the growing season, the capacity to fix CO2 was closely related to both timing and frequency of rainfall events. (c) 2007 Published by Elsevier Masson SAS.

Seasonal and interannual variation in water vapor and energy exchange over a typical steppe in Inner Mongolia, China

In this study, we conducted eddy covariance (EC) measurements of water vapor exchange over a typical steppe in a semi-arid area of the Inner Mongolia Plateau, China. Measurement sites were located within a 25-year-old enclosure with a relatively low leaf area index (similar to 1. 5 m(2) m(-2)) and dominated by Leymus chinensis. Energy balance closure was (H + LE) = 17.09 + 0.69 x (Rn - G) (W/m(2); r(2) = 0.95, n = 6596). Precipitation during the two growing seasons of the study period was similar to the long-term average. The peak evapotranspiration in 2004 was 4 mm d(-1), and 3.5 mm d(-1) in 2003. The maximum latent heat flux was higher than the sensible heat flux, and the sensible heat flux dominated the energy budget at midday during the entire growing season in 2003; latent heat flux was the main consumption component for net radiation during the 2004 growing season. During periods of frozen soil in 2003 and 2004, the sensible heat flux was the primary consumption component for net radiation. The soil heat flux component was similar in 2003 and 2004. The decoupling coefficient (between 0.5 and 0.1) indicates that evapotranspiration was strongly controlled by saturation water vapor pressure deficit (VPD) in this grassland. The results of this research suggest that energy exchange and evapotranspiration were controlled by the phenology of the vegetation and soil water content. In addition, the amount and frequency of rainfall significantly affect energy exchange and evapotranspiration upon the Inner Mongolia plateau. (c) 2007 Published by Elsevier B.V.

Short-term effect of targeted placements of sheep excrement on grassland in inner mongolia on soil and plant parameters

Grazing animal excrement plays an important role in nutrient cycling and redistribution in grazing ecosystems, due to grazing in large areas and return in small areas. To elucidate the changes to the soil and pasture caused by sheep urine, fresh dung, and compost patches, a short- term field experiment using artificially placed pats was set up in the autumn of 2003 in the Inner Mongolian steppe. Urine application significantly increased soil pH during the first 32 days in soil layers at depths of both 0 - 5 cm and 5 - 15 cm. Rapid hydrolysis of urea gave large amounts of urine- nitrogen ( N) as ammonium ( NH4+) in soil extracts and was followed by apparent nitrification from day 2. Higher inorganic N content in the urine- treated soil was found throughout the experiment compared with the control. No significant effects of sheep excrement on soil microbial carbon ( C) and soil microbial N was found, but microbial activities significantly increased compared with the control after application of sheep excrement. Forty- six percent of dung- N and 27% of compost- N were transferred into vegetation after the experiment. The results from this study suggest that large amounts of nutrients have been lost from the returned excrement patches in the degraded grassland of Inner Mongolia, especially from sheep urine- N.

Effects of forage composition and growing season on methane emission from sheep in the Inner Mongolia steppe of China

Understanding the effects of dietary composition on methane (CH4) production of sheep can help us to understand grassland degradation resulting in an increase of CH4 emission from ruminant livestock and its resulting significance affecting CH4 source/sink in the grazing ecosystem. The objective of this study was to investigate the effect of forage composition in the diet of sheep in July and August on CH4 production by sheep in the Inner Mongolia steppe. The four diet treatments were: (1) Leymus chinensis and Cleistogenes squarrosa (LC), (2) Leymus chinensis, Cleistogenes squarrosa and concentrate supplementation (LCC), (3) Artemisia frigida and Cleistogenes squarrosa (AC), and (4) Artemisia frigida, Cleistogenes squarrosa and concentrate supplementation (ACC). CH4 production was significantly lower in July than in August (31.4 and 36.2 g per sheep-unit per day, respectively). The daily average CH4 production per unit of digestive dry matter (DM), organic matter (OM) and neutral detergent fiber (NDF) increased by 10.9, 11.2 and 42.1% for the AC diet compared with the LC diet, respectively. Although concentrate supplementation in both the AC and LC diets increased total CH4 production per sheep per day, it improved sheep productivity and decreased CH4 production by 14.8, 12.5 and 14.8% per unit of DM, OM and NDF digested by the sheep, respectively. Our results suggested that in degraded grassland CH4 emission from sheep was increased and concentrate supplementation increased diet use efficiency. Sheep-grazing ecosystem seems to be a source of CH4 when the stocking rate is over 0.5 sheep-units ha(-1) during the growing season in the Inner Mongolia steppe.

Short-term effects of sheep excrement on carbon dioxide, nitrous oxide and methane fluxes in typical grassland of Inner Mongolia

Excrement patches of grazing animals play an important role in greenhouse gas (GHG) fluxes due to the high nitrogen (N) and available carbon (C) deposited in small areas, but little information is available for the effect of excrement in the Inner Mongolian grassland (43 26 degrees N, 116 degrees 40'E). To elucidate the effect of grazing sheep urine, fresh dung and compost on fluxes of methane (CH4), carbon dioxide (CO2), and nitrous oxide (N2O), a short-term field study (65 days) was carried out in the typical grassland of Inner Mongolia with the optimised closed chamber/GC technique. Compared with the control, cumulative net CH4 consumption decreased 36, 31, and 18% from urine, fresh dung, and compost plots, respectively; net CO2-C output increased by 6.5, 1.5, and 1.2% from urine, fresh dung, and compost treated soil, respectively; about three times as much N2O-N was emitted from urine and the fresh dung treatments during 65 days. Nitrous oxide emission was positively correlated with CO, emission (R = 0.691, P < 0.01) and water-filled pore space (R = 0.698, P < 0.01). The percentages of N2O-N loss of applied-N were 0.44 and 1.05% for urine and fresh dung, respectively. Our results suggest that in autumn in the degraded grassland of Inner Mongolia, the effect of sheep excrement may be ignored when evaluating the total GHG emissions.

Suitability of extractants for predicting available sulfur in natural grassland in the Inner Mongolia steppe of China

It was the objective of this study to compare the suitability of different extractants for predicting the availability of sulfur (S) in natural grassland in a sulfur response trial on three different soil types in the Inner Mongolia steppe of China. For soil analysis, seven different extractants have been employed. The inorganic SO4-S concentration was determined by ion chromatography. Additionally, in the Ca(H-2-PO4)(2) extract the total soluble S was determined employing turbidimetry. Weak salt solutions (0.15% CaCl2, Ca(H2PO4)(2), and KH2PO4) extracted similar amounts Of SO4-S. Extraction with 0.025 M KCl provided the lowest SO4-S values. Deionized water dissolved significantly more SO4-S in the control plots than most weak salt extractants. The concentration of soluble organic S decreased in the control plots after 100 days of plant growth, indicating that the organic S pool contributed significantly to the S nutrition of the forage crops. Significant relationships among the SO4-S in the soil determined in different extracts and crop yield, sulfur content in the forage, and total sulfur uptake were only found for the Ca(H2PO4)(2) extract. In general, the correlation coefficients proved to be unsatisfactory for field experimentation.

Effect of long-term grazing on soil organic carbon content in semiarid steppes in Inner Mongolia

To clarify the response of soil organic carbon (SOC) content to season-long grazing in the semiarid typical steppes of Inner Mongolia, we examined the aboveground biomass and SOC in both grazing (G-site) and no grazing (NG-site) sites in two typical steppes dominated by Leymus chinensis and Stipa grandis, as well as one seriously degraded L. chinensis grassland dominated by Artemisia frigida. The NG-sites had been fenced for 20 years in L. chinensis and S. grandis grasslands and for 10 years in A. frigida grassland. Above-ground biomass at G-sites was 21-35% of that at NG-sites in L. chinensis and S. grandis grasslands. The SOC, however, showed no significant difference between G-site and NG-site in both grasslands. In the NG-sites, aboveground biomass was significantly lower in A. frigida grassland than in the other two grasslands. The SOC in A. frigida grassland was about 70% of that in L. chinensis grassland. In A. frigida grassland, aboveground biomass in the G-site was 68-82% of that in the NG-site, whereas SOC was significantly lower in the G-site than in the NG-site. Grazing elevated the surface soil pH in L. chinensis and A. frigida communities. A spatial heterogeneity in SOC and pH in the topsoil was not detected the G-site within the minimal sampling distance of 10 m. The results suggested that compensatory growth may account for the relative stability of SOC in G-sites in typical steppes. The SOC was sensitive to heavy grazing and difficult to recover after a significant decline caused by overgrazing in semiarid steppes.

海拉尔盆地贝尔凹陷基岩潜山特征及储层预测

The lithology of the buried hill of Triassic Budate group in Beier depression is epimetamorphic clastic rock and volcanic clastic rock stratum. Recently the favorable hydrocarbon show was discovered in buried hill of base rock, and large-duty industrial oil stream was obtained in some wells in Beier depression. Based on the information of seismos and wells, the tectonic framework, tectonic deformation times and faulted system of the Beier depression are comprehensively studied, then configuration, evolutional history, genetic type and distributed regularity of buried hill are defined. According to observing description and analysis of core sample, well logging and interpretive result of FMI, the lithological component, diagenetic type and diagenetic sequence of buried hill reservoir are confirmed, then reservoir space system of buried hill is distinguished, and vegetal feature, genetic mechanism and distributed regularity of buried hill fissure are researched, at the same time the quantitative relationship is build up between core fissures and fissures interpreted by FMI. After that fundamental supervisory action of fault is defined to the vegetal degree of fissure, and the fissure beneficial places are forecasted using fractal theory and approach. At last the beneficial areas of Budate group reservoir are forecasted by reservoir appraisal parameters optimization such as multivariate gradually regression analysis et. al. and reservoir comprehensive appraisal method such as weighing analyze and clustering procedure et. al. which can provide foundation for the next exploratory disposition. Such production and knowledge are obtained in this text as those: 1. Four structural layers and two faulting systems are developed, and four structural layers are carved up by three bed succession boundary surfaces which creates three tectonic distortional times homology. Three types of buried hill are divided, they are ancient physiognomy buried hill, epigenetic buried hill, and contemporaneous buried hill. 2. Reservoir space of Budate buried hill is mainly secondary pore space and fissure, which distributes near the unconformity and/or inside buried hill in sections. The buried hill reservoir experienced multi-type and multi-stage diagenetic reconstruction, which led to the original porosity disappeared, and multi secondary porosity was created by dissolution, superficial clastation and cataclasis et. al. in diagenetic stage, which including middle crystal pore, inter crystal pore, moldic pore, inter particle emposieu, corrosion pore space and fissure et. al. which improved distinctly reservoir capability of buried hill. 3. The inner reservoir of buried hill in Beier depression is not stratigraphic bedded construction, but is fissure developing place formed by inner fault and broken lithogenetic belt. The fissures in inner reservoir of buried hill are developed unequally with many fissure types, which mainly are high angle fissure and dictyonal fissures and its developing degree and distribution is chiefly controlled by faulting. 4. The results of reservoir comprehensive evaluate and reservoir predicting indicates that advantageous areas of reservoir of buried hill chiefly distributes in Sudeerte, Beixi and Huoduomoer, which comprehensive evaluate mainly Ⅱand Ⅲ type reservoir. The clues and results of this text have directive significance for understanding the hydrocarbon reservoir condition of buried hill in Beier depression, for studying hydrocarbon accumulated mechanism and distributed regularity, and for guiding oil and gas exploration. The results of this text also can enrich and improve nonmarine hydrocarbon accumulated theory.