Sample records for regional paddy field

  1. [Nitrogen balance and environmental impact of paddy field under different N management methods in Taihu Lake region].

    PubMed

    Xue, Li-Hong; Yu, Ying-Liang; Yang, Lin-Zhang

    2011-04-01

    Effects of nitrogen (N) management methods of paddy field on N export to environment and paddy N balance in Taihu lake region, China were studied. Field experiment including site-specific nitrogen management (SSNM), organic & chemical N fertilizer treatment (OCN), control released urea treatment (CRN), reduced chemical N treatment (RN) and farmer's N treatment (FN) were conducted at the Taihu lake region in 2008. N loss including runoff, leaching, ammonia volatilization and N2O were calculated, and the N balance was evaluated. Results showed the grain yield of SSNM, OCN, CRN and RN treatments was identical with FN treatment, while the total N rate reduced about 20%-40%, and N use efficiency (NUE) increased 14.5%-44%. N export of SSNM and CRN treatments decreased 52.8% and 45.4% in comparison with FN treatment. Under the same N input, N export of OCN treatment was lower than pure chemical N treatment (RN). N surplus was observed in FN treatment, while N deficit existed in SSNM treatments. CRN and SSNM treatments could increase NUE, reduce N export without sacrifice of yield and benefit, and could be as an economic and environment-friendly measure to intensify in Taihu lake region. PMID:21717759

  2. Paddy field, groundwater and land subsidence

    SciTech Connect

    Wen, L.J. [Council of Agriculture, Taipei (Taiwan, Province of China)

    1995-12-31

    Through many years of research and technical interchange both at home and abroad, it is commonly recognized that paddy fields possess the functions of micro-climate adjustment, flood detection and prevention, soil and water conservation, river-flow stabilization, soil salinization prevention, water purification, groundwater recharge, rural area beautification and environmental protection which are all beneficial to the public. In recent years, the global environmental problems have become a series concern throughout the world. These include the broken ozone layer, green house effects, acid rain, land desertion, tropical rain forest disappearing etc. Among them, rain forest disappearing draws great attention. Both rain forests and paddy fields are in tropical areas. They have similar functions and are disappearing because of economic pressure. This paper describes the special functions of paddy fields on water purification, ground water recharge and prevention of land subsidence, and reiterates groundwater utilization and land subsidence prevention measures. In view of the importance of groundwater resources, paddy fields, which can not be replaced by any other artificial groundwater recharge facilities, should not be reduced in acreage, nor can they be left idle. Paddy fields shall be properly maintained and managed in order to strengthen their special functions in the years to come even under heavy pressure from foreign countries.

  3. Spatial landuse planning using land evaluation and dynamic system to define sustainable area of paddy field: Case study in Karawang Regency, West Java, Indonesia

    NASA Astrophysics Data System (ADS)

    Widiatmaka, Widiatmaka; Ambarwulan, Wiwin; Firmansyah, Irman; Munibah, Khursatul; Santoso, Paulus B. K.

    2015-04-01

    Indonesia is the country with the 4th largest population in the worlds; the population reached more than 237 million people. With rice as the staple food for more than 95 percent of the population, there is an important role of paddy field in Indonesian food security. Actually, paddy field in Java has produced 52,6% of the total rice production in Indonesia, showing the very high dependence of Indonesia on food production from paddy fields in Java island. Karawang Regency is one of the regions in West Java Province that contribute to the national food supply, due to its high soil fertility and its high extent of paddy field. Dynamics of land use change in this region are high because of its proximity to urban area; this dynamics has led to paddy field conversion to industry and residential landuse, which in turn change the regional rice production capacity. Decreasing paddy field landuse in this region could be serve as an example case of the general phenomena which occurred in Javanese rice production region. The objective of this study were: (i) to identify the suitable area for paddy field, (ii) to modelize the decreasing of paddy field in socio-economic context of the region, and (iii) to plan the spatial priority area of paddy field protection according to model prediction. A land evaluation for paddy was completed after a soil survey, while IKONOS imagery was analyzed to delineate paddy fields. Dynamic system model of paddy field land use is built, and then based on the model built, the land area of paddy field untill 2040 in some scenarios was developped. The research results showed that the land suitability class for paddy fields in Karawang Regency ranged from very suitable (S1) to marginally suitable (S3), with various land characteristics as limiting factors. The model predicts that if the situation of paddy field land use change continues in its business as usual path, paddy field area that would exist in the region in 2040 will stay half of the recent area. Based on the model, the scenario were developed for the protection of priority area. With such scenario, paddy field remains close to the value predicted oficially. Spatial information then can play a role by presenting the scenario spatially. Combining spatial information with land suitability, priority areas of paddy field protection can be delineated. Policies that followed also then be compiled, including the location of protection. Key-words: Land evaluation, food security, spatial information

  4. Depth distribution of radiocesium in Fukushima paddy fields three years after the accident

    NASA Astrophysics Data System (ADS)

    Lepage, Hugo; Laceby, J. Patrick; Evrard, Olivier; Onda, Yuichi; Lefèvre, Irène; Ayrault, Sophie

    2015-04-01

    Rice paddy fields located in the vicinity of the Fukushima Dai-Ichi Nuclear Power Plant (FDNPP) were contaminated by radioactive fallout from the March 2011 accident. Although many studies have investigated the fate of radiocesium in soil in the months following the accident, the potential migration of radiocesium in rice paddy fields requires further examination after major typhoons occurred in this region in 2011 and 2013. Further investigations are also required because paddy fields are typically comprised of Andosols, a soil type in which radiocesium has been known to potentially migrate deeper in the depth profile. To investigate the depth migration of radiocesium we collected soil cores in 10 paddy fields located less than 20 km from the FDNPP in November 2013. The maximum depth penetration of 137Cs was attributed to field maintenance (e.g. grass cutting) (97% of 137Cs in the upper 5-cm) and farming operations (tillage/cultivation - 83% of 137Cs in the upper 5-cm). The low migration observed in undisturbed paddy fields could be attributed to the presence of phyllosilicates that were detected by X-ray diffraction in Andosols. As radiocesium is mainly located in the uppermost soil layers, we recommend the rapid removal of these upper layers (e.g. the top 5 cm) to reduce radiocesium export during erosive events such as the major typhoons known to impact the region. Further research is required to thoroughly understand the impacts of erosion on the transfer and migration of radiocesium throughout the Fukushima Prefecture.

  5. The Study of Runoff Loads from Lotus Paddy Fields

    NASA Astrophysics Data System (ADS)

    Kuroda, Hisao; Kato, Tasuku; Nakasone, Hideo

    To solve the problem of diffuse pollution brought about of eutrophication in lakes, an investigation was conducted in lotus paddy fields, at which little research had been conducted. The study area consisted of low-land lotus paddy fields around the Lake Kasumigaura watershed in Ibaraki Prefecture. The area is well known as the largest production center of lotus roots in Japan. The results of the study show that the mass balance loads of total nitrogen(T-N), total phosphorus(T-P), chemical oxygen demand(COD), and suspended solids from the lotus paddy fields were -3.22 , 1.87, 75.36 and 552 kg·km-2·d-1, respectively. Comparing these values to the unit reported in "The Fifth Plan for Water Quality Conservation in the Lakes and Ponds related to Lake Kasumigaura", it was found that T-N was purified, T-P was 2.1 times higher and COD was 4.8 times higher. It was found that the major cause of the effluent loads was the outflow of suspended matters during puddling and lotus planting. The dissolved matter was influenced by the increase of discharge. The suspended matter discharge from the lotus paddy fields temporarily accumulated at the end of the drainage canals and flowed out when there was a rainfall.

  6. Evaluating health of paddy rice field ecosystem with remote sensing and GIS in Lower Yangtze River Plain, China

    NASA Astrophysics Data System (ADS)

    Li, Jingjing; Qin, Zhihao; Li, Wenjuan; Lin, Lu

    2008-10-01

    A paddy rice ecosystem is a farming system composed of paddy, animals, microbes and other environmental factors in specific time and space, with particular temporal and spatial dynamics. Since paddy rice is a main grain crop to feed above half of population in China, the performance of paddy rice ecosystem is highly concerned to yield level of paddy and food supply safety in China. Therefore, monitoring the performance of paddy rice ecosystem is very important to obtain the required information for evaluation of ecosystem health. In the study we intend to develop an approach to monitor the ecosystem performance spatially and dynamically in a regional scale using MODIS remote sensing data and GIS spatial mapping. On the basis of key factors governing the paddy rice ecosystem, we accordingly develop the following three indicators for the evaluation: Crop growing index (CGI), environmental Index (EI), and pests-diseases index (PDI). Then, we integrated the three indicators into a model with different weight coefficients to calculate Comprehensive ecosystem health index (CEHI) to evaluate the performance and functioning of paddy rice ecosystem in a regional scale. CGI indicates the health status of paddy rice calculated from the normalizing enhanced vegetation Index (EVI) retrieved from MODIS data. EI is estimated from temperature Index (TI) and precipitation Index (PI) indicating heat and water stress on the rice field. PDI reflects the damage brought by pests and diseases, which can be estimated using the information obtained from governmental websites. Applying the approach to Lower Yangtze River Plain, we monitor and evaluate the performance of paddy rice ecosystem in various stages of rice growing period in 2006. The results indicated that the performance of the ecosystem was generally very encouraging. During booting stage and heading and blooming stage, the health level was the highest in Anhui province, which is the main paddy rice producer in the region. During stage of yellow ripeness, Jiangsu province had the lowest level of performance. Yield level of paddy rice in 2006 confirms that the applicability of the proposed approach for a rapid evaluation and monitoring of agricultural ecosystem performance in Lower Yangtze River Plain. As a result, the new approach could supply scientific basis for relevant departments taking policies and measures to make sure stable development of paddy yield.

  7. Phosphine in paddy fields and the effects of environmental factors.

    PubMed

    Niu, Xiaojun; Wei, Aishu; Li, Yadong; Mi, Lina; Yang, Zhiquan; Song, Xiaofei

    2013-11-01

    Ambient levels of phosphine (PH3) in the air, phosphine emission fluxes from paddy fields and rice plants, and the distribution of matrix-bound phosphine (MBP) in paddy soils were investigated throughout the growing stages of rice. The relationships between MBP and environmental factors were analyzed to identify the principal factors determining the distribution of MBP. The phosphine ambient levels ranged from 2.368±0.6060 ng m(-3) to 24.83±6.529 ng m(-3) and averaged 14.25±4.547 ng m(-3). The highest phosphine emission flux was 22.54±3.897 ng (m(2)h)(-1), the lowest flux was 7.64±4.83 ng (m(2)h)(-1), and the average flux was 14.17±4.977 ng (m(2)h)(-1). Rice plants transport a significant portion of the phosphine emitted from the paddy fields. The highest contribution rate of rice plants to the phosphine emission fluxes reached 73.73% and the average contribution was 43.00%. The average MBP content of 111.6 ng kg(-1)fluctuated significantly in different stages of rice growth and initially increased then decreased with increasing depth. The peak MBP content in each growth stage occurred approximately 10 cm under the surface of paddy soils. Pearson correlation analyses and stepwise multiple regression analysis showed that soil temperature (Ts), acid phosphatase (ACP) and total phosphorus (TP) were the principal environmental factors, with correlative rankings of Ts>ACP>TP. PMID:23876504

  8. Abundance of rare earth elements in rice paddy soils from three regions of Sri Lanka

    Microsoft Academic Search

    Rohana Chandrajith; Chandrasekara Bandara Dissanayake; Heinz Jürgen Tobschall

    2004-01-01

    Very few studies deal with the rare earth element (REE) content within paddy soil systems. This paper presents, for the first time, the distribution of REEs in paddy soils from three different regions in Sri Lanka. Seventy samples from the Kalutara and Kandy regions located in the Wet Zone and Anuradhapura region in the Dry Zone were selected for this

  9. Urbanization dramatically altered the water balances of a paddy field dominated basin in Southern China

    NASA Astrophysics Data System (ADS)

    Hao, L.; Sun, G.; Liu, Y.; Wan, J.; Qin, M.; Qian, H.; Liu, C.; John, R.; Fan, P.; Chen, J.

    2015-02-01

    Rice paddy fields provide important ecosystem services (e.g., food production, water retention, carbon sequestration) to a large population globally. However, these benefits are declining as a result of rapid environmental and socioeconomic transformations characterized by population growth, urbanization, and climate change in many Asian countries. This case study examined the responses of streamflow and watershed water balances to the decline of rice paddy fields due to urbanization in the Qinhuai River Basin in southern China where massive industrialization has occurred in the region during the past three decades. We found that streamflow increased by 58% and evapotranspiration (ET) decreased by 23% during 1986-2013 as a result of an increase in urban areas of three folds and reduction of rice paddy field by 27%. Both highflows and lowflows increased significantly by about 28% from 2002 to 2013. The increases in streamflow were consistent with the decreases in ET and leaf area index monitored by independent remote sensing MODIS data. The reduction in ET and increase in streamflow was attributed to the large cropland conversion that overwhelmed the effects of regional climate warming and climate variability. Converting traditional rice paddy fields to urban use dramatically altered land surface conditions from a water-dominated to a human-dominated landscape, and thus was considered as one of the extreme types of contemporary hydrologic disturbances. The ongoing large-scale urbanization in the rice paddy-dominated regions in the humid southern China, and East Asia, will likely elevate stormflow volume, aggravate flood risks, and intensify urban heat island effects. Understanding the linkage between land use change and changes in hydrological processes is essential for better management of urbanizing watersheds.

  10. Simulating Water Transport and Loss in a Direct-Seeded Paddy Field Using Hydrus-1D

    Microsoft Academic Search

    Li Yong; Zhang Yu; Huang Chun-hui

    2010-01-01

    The characteristic of water transport and loss in a direct-seeded paddy field, Danyang Region at upstream of Taihu Lake Basin, was studied under local traditional field water management using Hydrus-1D model. Results show that the drying\\/wetting boundary condition on soil surface was well simulated by using divided stress period method in the Hydrus-1D model, and the estimated hydrodynamic parameters can

  11. Investigation of Spatial Distribution of Radiocesium in a Paddy Field as a Potential Sink

    PubMed Central

    Tanaka, Kazuya; Iwatani, Hokuto; Takahashi, Yoshio; Sakaguchi, Aya; Yoshimura, Kazuya; Onda, Yuichi

    2013-01-01

    Surface soils, under various land uses, were contaminated by radionuclides that were released by the Fukushima Daiichi Nuclear Power Plant accident. Because paddy fields are one of the main land uses in Japan, we investigated the spatial distribution of radiocesium and the influence of irrigation water in a paddy field during cultivation. Soil core samples collected at a paddy field in Fukushima showed that plowing had disturbed the original depth distribution of radiocesium. The horizontal distribution of radiocesium did not show any evidence for significant influence of radiocesium from irrigation water, and its accumulation within the paddy field, since the original amount of radiocesium was much larger than was added into the paddy field by irrigation water. However, it is possible that rainfall significantly increases the loading of radiocesium. PMID:24260481

  12. Field investigation to assess nutrient emission from paddy field to surface water in river catchment

    NASA Astrophysics Data System (ADS)

    Kogure, Kanami; Aichi, Masaatsu; Zessner, Matthias

    2015-04-01

    In order to maintain good river environment, it is remarkably important to understand and to control nutrient behavior such as Nitrogen and Phosphorus. Our former research dealing with nutrient emission analysis in the Tone River basin area in Japan, in addition to urban and industrial waste water, nutrient emission from agricultural activity is dominant pollution source into the river system. Japanese style agriculture produces large amount of rice and paddy field occupies large areas in Japanese river basin areas. While paddy field can deteriorate river water quality by outflow of fertilizer, it is also suggested that paddy field has water purification function. As we carried out investigation in the Tone River Basin area, data were obtained which dissolved nitrogen concentration is lower in discharging water from paddy field than inflowing water into the field. Regarding to nutrient emission impact from paddy field, sufficient data are required to discuss quantitatively seasonal change of material behavior including flooding season and dry season, difference of climate condition, soil type, and rice species, to evaluate year round comprehensive impact from paddy field to the river system. In this research, field survey in paddy field and data collection relating rice production were carried out as a preliminary investigation to assess how Japanese style paddy field contributes year round on surface water quality. Study sites are three paddy fields located in upper reach of the Tone River basin area. The fields are flooded from June to September. In 2014, field investigations were carried out three times in flooding period and twice in dry period. To understand characteristics of each paddy field and seasonal tendency accompanying weather of agricultural event, short term investigations were conducted and we prepare for further long term investigation. Each study site has irrigation water inflow and outflow. Two sites have tile drainage system under the field and TD water can be sampled for infiltrating water measurement. We installed monitoring wells to measure ground water level and water quality. Inflow, outflow, flooding water, infiltrating water, and ground water were measured and sampled. Regarding to parameters, temperature, pH, EC, DO and COD, main ions were measured to understand characteristic of water quality and transformation processes. Inorganic forms of nitrogen and phosphorus were also measured, as behavior and balance of nitrogen and phosphorus are focused on. We observed following points by taking data of water quality; seasonal trend, changes occurred according to agricultural events like irrigation and fertilization. Nitrogen in ground water tends to high in June due to fertilizer. It is thought because farmers fertilize the filed before transplanting at the beginning of flooding season. Regarding to dissolved inorganic nitrogen, higher concentrations were observed in inflow water than in flooding water and outflow water. Though it needs discussion in loads as well as flow measurement, this suggests that nutrients are absorbed in paddy field and less nutrients are emitted after irrigation water passing through paddy field. Based on this research we are planning continuous investigation to assess environmental impact from paddy field.

  13. Assessment of the camellia seed meal impact on loaches in paddy fields

    Microsoft Academic Search

    Rong-Song Chen; Kuo-Liang Wang; Chia-Ying Wu

    In Taiwan, Camellia seed meal is often sprayed on rice paddies during rice transplantation season to stop the growth of Pomacea canaliculata. However, the application of camellia seed meal endangers muciferous mollusks and fishes in paddy fields. Though researchers\\u000a have examined the effects of the saponin in the camellia seed meal on Pomacea canaliculata, previous studies ignore the effects of

  14. [Effects of rice-duck farming on paddy field water environment].

    PubMed

    Quan, Guo-Ming; Zhang, Jia-En; Chen, Rui; Xu, Rong-Bao

    2008-09-01

    Field experiment was conducted to investigate the effects of rice-duck farming on the water environment in paddy field. The results showed that under rice-duck farming, the temperature and pH value of the surface water in paddy field decreased, and the electrical conductivity, oxidation-reduction potential, turbidity, and the contents of nitrogen (N), phosphorus (P) and potassium (K) increased. The total N, P, and K increased by 1.85-5.06 times, 2.01-8.70 times, and 42.79%-109.18%, respectively, as compared to those in conventional rice farming. All of these illustrated that rice-duck farming improved the paddy field water environment and nutrient supply, optimized the ecological environment of paddy field, and promoted the growth and development of rice. PMID:19102319

  15. Depth distribution of cesium-137 in paddy fields across the Fukushima pollution plume in 2013.

    PubMed

    Lepage, Hugo; Evrard, Olivier; Onda, Yuichi; Lefèvre, Irène; Laceby, J Patrick; Ayrault, Sophie

    2015-09-01

    Large quantities of radiocesium were deposited across a 3000 km(2) area northwest of the Fukushima Dai-ichi nuclear power plant after the March 2011 accident. Although many studies have investigated the fate of (137)Cs in soil in the months following the accident, the depth distribution of this radioactive contaminant in rice paddy fields requires further examination after the typhoons that occurred in this region. Such investigations will help minimize potential human exposure in rice paddy fields. Radionuclide activity concentrations, organic content and particle size were analysed in 10 soil cores sampled from paddy fields in November 2013, 20 km north of the Fukushima power plant. Our results demonstrate limited depth migration of (137)Cs with the majority concentrated in the uppermost layers of soils (<5 cm). More than 30 months after the accident, between 46.8 and 98.7% of the total (137)Cs inventories was found within the top 5 cm of the soil surface, despite cumulative rainfall totalling 3300 mm. Furthermore, there were no significant correlations between (137)Cs depth distribution and the other parameters. We attributed the maximum depth penetration of (137)Cs to grass cutting (73.6-98.5% of (137)Cs in the upper 5 cm) and farming operations (tillage - 46.8-51.6% of (137)Cs in the upper 5 cm). As this area is exposed to erosive events, ongoing decontamination works may increase soil erodibility. We therefore recommend the rapid removal of the uppermost - contaminated - layer of the soil after removing the vegetation to avoid erosion of contaminated material during the subsequent rainfall events. Further analysis is required to thoroughly understand the impacts of erosion on the redistribution of radiocesium throughout the Fukushima Prefecture. PMID:26026933

  16. Trees in Bangladesh paddy fields. 2. Survival of trees planted in crop fields

    Microsoft Academic Search

    D. Hocking; K. Islam

    1995-01-01

    The design and methods are described of farmer-managed action-research to test the survival and performance of trees planted in paddy fields of private farms in Bangladesh. Farmers received seedlings of indigenous and exotic trees with extension advice on planting methods and care. Planting was done in systematically designed randomized modules involving twelve thousand trees up to the end of 1990.

  17. Bacillus huizhouensis sp. nov., isolated from a paddy field soil.

    PubMed

    Li, Jibing; Yang, Guiqin; Wu, Min; Zhao, Yong; Zhou, Shungui

    2014-08-01

    A Gram-stain positive, facultative aerobic bacterium, designated as strain GSS03(T), was isolated from a paddy field soil. The cells were observed to be endospore forming, rod-shaped and motile with flagella. The organism was found to grow optimally at 35 °C at pH 7.0 and in the presence of 1 % NaCl. The strain was classified as a novel taxon within the genus Bacillus on the basis of phenotypic and phylogenetic analyses. The closest phylogenetic relatives were identified as Bacillus psychrosaccharolyticus DSM 6(T) (97.61 %), Bacillus muralis DSM 16288(T) (97.55 %), Bacillus asahii JCM 12112(T) (97.48 %), Bacillus simplex DSM 1321(T) (97.48 %) and "Bacillus frigoritolerans" DSM 8801(T) (97.38 %). The menaquinone was identified as MK-7, the major cellular fatty acid was identified as anteiso-C15:0 and the major cellular polar lipids as phosphatidylethanolamine, phosphatidylmonomethylethanolamine, diphosphatidylglycerol, phosphatidylglycerol and three unknown polar lipids. The DNA G+C content was determined to be 40.2 mol%. The DNA-DNA relatedness with the closest relatives was below 48 %. Therefore, on the basis of all the results, strain GSS03(T) is considered to represent a novel species within the genus Bacillus, for which the name Bacillus huizhouensis sp. nov. is proposed. The type strain is GSS03(T) (=KCTC 33172(T) =CCTCC AB 2013237(T)). PMID:24903955

  18. [Characteristics of paddy field nitrogen leakage and runoff in rice-duck farming system].

    PubMed

    Yu, Xiang; Wang, Qiang-sheng; Wang, Shao-hua; Liu, Zheng-hui; Wang, Xia-wen; Ding, Yan-feng

    2009-01-01

    A field experiment was conducted to study the characteristics of paddy field nitrogen (N) leakage and runoff under rice-duck farming (MRD), conventional farming (MR), and conventional farming with flooding (CK). Comparing with that under MR, the paddy field under MRD had a notable decrease of N (especially NO3- -N) concentration in its leaked liquid; but this concentration was tended to be increased, compared with that under CK. After 7-9 days of fertilization, the NH4+ -N and NO3- -N concentrations in paddy field surface water were higher under MRD than under MR. However, owing to the no draining and the higher band, the paddy field under MRD had a notable reduction of drainage, resulting in a marked decrease of N runoff than that under MR. Comparing with MR, the paddy field under MRD had an addition of nitrogen supply from duck dung, a reduction of N leakage and runoff, a lesser application of chemical nitrogen fertilizer, and more nitrogen uptake by rice plant. Both the reduction of N input and that of N output in rice-duck farming system were nearly equal in quantity. PMID:19449578

  19. Ammonia Volatilization Losses from Paddy Fields under Controlled Irrigation with Different Drainage Treatments

    PubMed Central

    He, Yupu; Yang, Shihong; Wang, Yijiang

    2014-01-01

    The effect of controlled drainage (CD) on ammonia volatilization (AV) losses from paddy fields under controlled irrigation (CI) was investigated by managing water table control levels using a lysimeter. Three drainage treatments were implemented, namely, controlled water table depth 1 (CWT1), controlled water table depth 2 (CWT2), and controlled water table depth 3 (CWT3). As the water table control levels increased, irrigation water volumes in the CI paddy fields decreased. AV losses from paddy fields reduced due to the increases in water table control levels. Seasonal AV losses from CWT1, CWT2, and CWT3 were 59.8, 56.7, and 53.0?kg?N?ha?1, respectively. AV losses from CWT3 were 13.1% and 8.4% lower than those from CWT1 and CWT2, respectively. A significant difference in the seasonal AV losses was confirmed between CWT1 and CWT3. Less weekly AV losses followed by TF and PF were also observed as the water table control levels increased. The application of CD by increasing water table control levels to a suitable level could effectively reduce irrigation water volumes and AV losses from CI paddy fields. The combination of CI and CD may be a feasible water management method of reducing AV losses from paddy fields. PMID:24741349

  20. Clay mineral status of paddy soils from the Tai Lake Region of China in relation to high paddy-rice productivity

    Microsoft Academic Search

    Kazuhiko Egashira; Soichi Iwashita; Shin-ichi Yamasaki

    1997-01-01

    Soil samples which were collected in the Tai Lake region of China during the tour organized after the 14th International Congress of Soil Science in 1990 were analyzed for the determination of the concentration of rare earth elements, particle-size distribution, and clay mineralogical composition. Paddy soils distributed in the plain and polder areas were derived from Xiashu loess. The concentration

  1. Uncertainties in estimating regional methane emissions from rice paddies due to data scarcity in the modeling approach

    NASA Astrophysics Data System (ADS)

    Zhang, W.; Zhang, Q.; Huang, Y.; Li, T. T.; Bian, J. Y.; Han, P. F.

    2014-06-01

    Rice paddies are a major anthropogenic source of the atmospheric methane. However, because of the high spatial heterogeneity, making accurate estimations of the methane emission from rice paddies is still a big challenge, even with complicated models. Data scarcity is one of the substantial causes of the uncertainties in estimating the methane emissions on regional scales. In the present study, we discussed how data scarcity affected the uncertainties in model estimations of rice paddy methane emissions, from county/provincial scale up to national scale. The uncertainties in methane emissions from the rice paddies of China was calculated with a local-scale model and the Monte Carlo simulation. The data scarcities in five of the most sensitive model variables, field irrigation, organic matter application, soil properties, rice variety and production were included in the analysis. The result showed that in each individual county, the within-cell standard deviation of methane flux, as calculated via Monte Carlo methods, was 13.5-89.3% of the statistical mean. After spatial aggregation, the national total methane emissions were estimated at 6.44-7.32 Tg, depending on the base scale of the modeling and the reliability of the input data. And with the given data availability, the overall aggregated standard deviation was 16.3% of the total emissions, ranging from 18.3-28.0% for early, late and middle rice ecosystems. The 95% confidence interval of the estimation was 4.5-8.7 Tg by assuming a gamma distribution. Improving the data availability of the model input variables is expected to reduce the uncertainties significantly, especially of those factors with high model sensitivities.

  2. Modelling field-data of preferential flow in paddy soil induced by earthworm burrows.

    PubMed

    Sander, Till; Gerke, Horst H

    2009-02-16

    Dye tracer studies revealed that earthworm burrows in the compacted plough pan of a Chinese paddy rice field can serve as preferential flow paths. It is, however, unclear whether the observed bypass of the compacted soil horizon might be explained by differences in hydraulic properties between the plough pan, the worm burrows with a surrounding denser drilosphere and the un-compacted subsoil, or by lower-permeable macropore walls. The objective is to separately analyse effects of the individual flow domains and to identify possible limiting factors (bottlenecks) in the flow system for better soil drainage management. Hydraulic properties are inversely estimated from in situ measurements of pressure heads and evaporation by using HYDRUS_1D code. Field data of 2D pressure head progression after dye tracer infiltration in the vicinity of worm burrows are simulated using HYDRUS_2D. The axisymmetric 2D flow model considers a highly permeable cylindrical macropore region in the centre of the flow domain, assuming Darcy's law is valid. The match between simulated and measured pressure head fields improved after including a lower-permeable drilosphere pore domain. Scenario simulations show that the inflow into the 'bypass-flow' domain are reduced by the homogenized topsoil (i.e., after puddling) and limited if the macropore domain is relatively shallow. The results suggest that basic structural features may in this concept be considered as one possibility to describe observed preferential flow patterns. The separate consideration of soil structural effects may help developing and improving management strategies for manipulation of preferential flow in soils of paddy fields. PMID:19064301

  3. Estimation of soil moisture in paddy field using Artificial Neural Networks

    E-print Network

    Arif, Chusnul; Setiawan, Budi Indra; Doi, Ryoichi

    2013-01-01

    In paddy field, monitoring soil moisture is required for irrigation scheduling and water resource allocation, management and planning. The current study proposes an Artificial Neural Networks (ANN) model to estimate soil moisture in paddy field with limited meteorological data. Dynamic of ANN model was adopted to estimate soil moisture with the inputs of reference evapotranspiration (ETo) and precipitation. ETo was firstly estimated using the maximum, average and minimum values of air temperature as the inputs of model. The models were performed under different weather conditions between the two paddy cultivation periods. Training process of model was carried out using the observation data in the first period, while validation process was conducted based on the observation data in the second period. Dynamic of ANN model estimated soil moisture with R2 values of 0.80 and 0.73 for training and validation processes, respectively, indicated that tight linear correlations between observed and estimated values of s...

  4. Can't See the Forest for the Rice: Factors Influencing Spatial Variations in the Density of Trees in Paddy Fields in Northeast Thailand

    NASA Astrophysics Data System (ADS)

    Watanabe, Moriaki; Vityakon, Patma; Rambo, A. Terry

    2014-02-01

    The widespread presence of trees in paddy fields is a unique feature of Northeast Thailand's agricultural landscape. A survey of spatial variability in the density of trees in paddy fields in the Northeast Region was conducted utilizing high resolution satellite images and found that the mean density in the whole region was 12.1 trees/ha (varying from a high of 44.6 trees/ha to a low of 0.8 trees/ha). In general, tree densities are higher in the southeastern part of the region and much lower in the northern central part. Tree density was influenced by multiple factors including: (1) the history of land development, with more recently developed paddy fields having higher densities, (2) topography, with fields located at higher topographical positions having a higher mean density of trees, (3) access to natural forest resources, with fields in areas located close to natural forests having higher densities, (4) amount of annual rainfall, with fields in areas with higher average annual rainfall having higher tree densities, and (5) landholding size, with fields in areas with larger-sized landholdings having more trees. However, there is a considerable extent of co-variation among these factors. Although trees remain an important element of the paddy field landscape in the Northeast, it appears that their density has been declining in recent years. If this trend continues, then the vast "invisible forest" represented by trees in paddy fields may truly disappear, with negative consequences for the villagers' livelihoods, biodiversity conservation, and carbon sequestration in the rural ecosystem.

  5. A grid-based rainfall-runoff model for flood simulation including paddy fields

    Microsoft Academic Search

    In-Kyun Jung; Jong-Yoon Park; Geun-Ae Park; Mi-Seon Lee; Seong-Joon Kim

    2011-01-01

    A grid-based, KIneMatic wave STOrm Runoff Model (KIMSTORM) is described. The model adopts the single flow-path algorithm and\\u000a routes the water balance during the storm period. Manning’s roughness coefficient adjustment function of the paddy cell was\\u000a applied to simulate the flood mitigation effect of the paddy fields for the grid-based, distributed rainfall-runoff modeling.\\u000a The model was tested in 2296 km2 dam

  6. Generation of methane from paddy fields and cattle in India, and its reduction at source

    NASA Astrophysics Data System (ADS)

    Bandyopadhyay, T. K.; Goyal, P.; Singh, M. P.

    Methane (CH4) is a saturated organic gas. About 500 Tg yr -1 methane is generated globally. It is evident that 70% of the total emission have anthropogenic sources. The paddy fields contribute a significant portion of the total methane generated. About 20% of the total methane is generated from the paddy fields. In India, methane efflux rate is negative to 49 mg m -2 hr -1. The mean CH4 flux from Indian paddy fields is calculated to be 4.0 Tgyr -1. Livestock, and in particular ruminants are one of the important sources of methane emission on a global scale. There are two sources of methane emission from live stock: (1) from digestive process of ruminants, (2) from animal wastes. The estimated value of methane emission from digestive process of ruminants in India accounts for 6.47 Tgyr -1, and animal wastes accounts for 1.60 Tgyr -1. Total generation of methane from animals in India is about 8.0 Tg yr -1 . In paddy fields the key of controlling methane emission lies in the control of irrigation water. The methane emission can be decreased drastically if the field is under dry conditions for a few days at the end of tillering. In the case of livestock, reduction of methane emission can be done by (1) increasing the intake of the animal, (2) modifying the composition of the diet, (3) eliminating protozoa in rumen, (4) improving fibre digestion efficiency and (5) inhibiting activity of methanogenic bacteria.

  7. Applying SWAT for TMDL programs to a small watershed containing rice paddy fields

    Microsoft Academic Search

    M. S. Kang; S. W. Park; J. J. Lee; K. H. Yoo

    2006-01-01

    The main objective of this study was to apply the soil and water assessment tool (SWAT) to develop total maximum daily load (TMDL) programs for a small watershed containing rice paddy fields in the Republic of Korea. The total maximum daily load system (TOLOS), based on ArcView SWAT (AVSWAT) using geographic information system (GIS) and remote sensing (RS), was incorporated

  8. Crop Uptake of Arsenic from Flooded Paddy Fields in the Mekong Delta

    NASA Astrophysics Data System (ADS)

    Mohr, K.; Boye, K.

    2014-12-01

    Arsenic is found naturally in the soils in the Mekong delta in Vietnam and Cambodia. It originates from erosion in the Himalayas. When similar levels of arsenic are present in well aerated soil, it is not dangerous, because it is strongly bound to soil particles and not readily plant available. Arsenic is released when the soil is saturated with water, and therefore contaminates crops grown in flooded fields. This results in people being exposed to unsafe levels of arsenic from their food, such as rice and lotus, which are normally grown under flooded conditions. Rice is a staple food in these regions, so the transfer of arsenic from soil, to water, and ultimately into the grain, poses a threat to human health. We have conducted a limited, preliminary field survey of arsenic levels in soil, flood water, and crops from distinctly different paddy fields in the lower Mekong delta in Vietnam and Cambodia. The purpose of the study was to identify soils and crops (or specific plant parts) that are especially prone to arsenic transfer from soil to crop, and vice versa (i.e. arsenic uptake is prevented in spite of being present in the soil). In addition to arsenic concentration in soil, plant and water, we are examining other elements, such as carbon, nitrogen, sulfur and iron, which give us clues about what chemical and microbial processes that control the overall arsenic uptake.

  9. Effect of residual biomass burning on CO2 flux at a paddy field in Japan

    NASA Astrophysics Data System (ADS)

    Taniguchi, Y.; Iwata, T.; Nakaya, K.

    2014-12-01

    Paddy field is one of the most important ecosystem in monsoon Asia, and takes a great important role in CO2 uptake. Carbon budget in agricultural fields is largely influenced by some artificial managements. After the harvest of crops, residual biomass is burned on fields, brought out from fields, or left and plowed into paddy soils. If the open burning is conducted on fields, one part of biomass carbon would be emitted to atmosphere as CO2, and the other part would be plowed into soils. In this study, an experimental paddy field was divided into two areas to investigate what impact is brought on the annual CO2 flux by the difference of disposal management of residual biomass after the harvest. At the one area, residual biomass was burned and plowed into soils after the harvest in late November 2011, 2012, and 2013. At the other area, residue was not burned and plowed into soils as usual. From three-years average of sampling surveys, carbon content of residue plowed into soils after the harvest was estimated 293±1 and 220±36 g C m-2 at no-burned and burned area, respectively. Continuous eddy-covariance measurements of CO2 fluxes at each area were conducted for three years. A little bit of difference in CO2 flux between two areas was shown during rice season.

  10. Impacts of the herbicide butachlor on the larvae of a paddy field breeding frog ( Fejervarya limnocharis ) in subtropical Taiwan

    Microsoft Academic Search

    Wan-Yi Liu; Ching-Yuh Wang; Tsu-Shing Wang; Gary M. Fellers; Bo-Chi Lai; Yeong-Choy Kam

    2011-01-01

    Butachlor is the most commonly used herbicide on paddy fields in Taiwan and throughout Southeast Asia. Since paddy fields\\u000a provide habitat for pond breeding amphibians, we examined growth, development, time to metamorphosis, and survival of alpine\\u000a cricket frog tadpoles (Fejervarya limnocharis) exposed to environmentally realistic concentrations of butachlor. We documented negative impacts of butachlor on survival,\\u000a development, and time to

  11. Comparison of greenhouse gas emissions from rice paddy fields under different nitrogen fertilization loads in Chongming Island, Eastern China.

    PubMed

    Zhang, Xianxian; Yin, Shan; Li, Yinsheng; Zhuang, Honglei; Li, Changsheng; Liu, Chunjiang

    2014-02-15

    Rice is one of the major crops of southern China and Southeast Asia. Rice paddies are one of the largest agricultural greenhouse gas (GHG) sources in this region because of the application of large quantities of nitrogen (N) fertilizers to the plants. In particular, the production of methane (CH4) is a concern. Investigating a reasonable amount of fertilizers to apply to plants is essential to maintaining high yields while reducing GHG emissions. In this study, three levels of fertilizer application [high (300 kg N/ha), moderate (210 kg N/ha), and low (150 kg N/ha)] were designed to examine the effects of variation in N fertilizer application rate on carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) emissions from the paddy fields in Chongming Island, Shanghai, China. The high level (300 kg N/ha) represented the typical practice adopted by the local farmers in the area. Maximum amounts of CH4 and N2O fluxes were observed upon high-level fertilizer application in the plots. Cumulative N2O emissions of 23.09, 40.10, and 71.08 mg N2O/m(2) were observed over the growing season in 2011 under the low-, moderate-, and high-level applications plots, respectively. The field data also indicated that soil temperatures at 5 and 10 cm soil depths significantly affected soil respiration; the relationship between Rs and soil temperature in this study could be described by an exponential model. Our study showed that reducing the high rate of fertilizer application is a feasible way of attenuating the global-warming potential while maintaining the optimum yield for the studied paddy fields. PMID:24295754

  12. Evaluation of two rodenticides in the paddy fields during Samba and Thaladi seasons.

    PubMed

    Baskaran, J; Kanakasabai, R; Neelanarayanan, P

    1995-02-01

    The single dose anticoagulant rodenticide, bromadiolone (0.005%) and the acute rodenticide, zinc phosphide (2%) were evaluated in the paddy fields during Samba and Thaladi seasons for two crop stages, viz. 20 and 40 days after transplantation. Three baiting methods namely, burrow, station and burrow+station were adopted for both rodenticides. Both the rodenticides were exposed for one and two days in the partitioned plots. In the plots with 20 days after transplantation, the two day exposure of both rodenticides in burrow+station baitings during both seasons cleared cent percent rodent population. The cost-benefit ratio of the employed rodenticides favoured zinc phosphide than bromadiolone. Thus, zinc phosphide is deemed to be an economic rodenticide than bromadiolone and it can be suggested for the control of rodent population with two day exposure by burrow+station baiting methods preferably 20 days after transplanted paddy fields in both seasons. PMID:7759123

  13. Species Composition, Distribution and Management of Trees in Rice Paddy Fields in Central Lao, PDR

    Microsoft Academic Search

    Y. Kosaka; S. Takeda; S. Prixar; S. Sithirajvongsa; K. Xaydala

    2006-01-01

    Presence of different types of trees dispersed singly or in small groups throughout the fields is a very common feature in\\u000a the extensive rice paddies of Laos and Thailand. Factors such as land-settlement history, proximity to forest, and role of\\u000a species in the local culture are known to influence the nature and distribution of tree species so retained. The extent

  14. Three-year measurement of methane emission from an Indonesian paddy field

    Microsoft Academic Search

    S. G. Nugroho; J. Lumbanraja; H. Suprapto; Sunyoto; H. Haraguchi; M. Kimura

    1996-01-01

    Yearly and seasonal (rainy and dry seasons) variations of CH4 emission from a Sumatra paddy field were measured for 3 years. The mean CH4 emission rates during the growth period were in the range of 16.0–26.1 mg CH4 m-2 h-1 for the chemical fertilizer plots and 23.3–34.9 mg CH4 m-2 h-1 for the plots with rice straw application, respectively. The

  15. Diversity of methanogenic archaeal communities in Japanese paddy field ecosystem, estimated by denaturing gradient gel electrophoresis

    Microsoft Academic Search

    Takeshi Watanabe; Makoto Kimura; Susumu Asakawa

    2010-01-01

    Diversity of methanogenic archaeal communities in Japanese paddy field ecosystem was evaluated by the denaturing gradient\\u000a gel electrophoresis (DGGE) after PCR amplification of the 16S rRNA genes (16S rDNAs), sequencing analysis and data evaluation\\u000a by principal component analysis. Data were obtained from samples collected from the plowed soil layer, rice roots, rice straws\\u000a incorporated in soil, plant residues (mixture of

  16. Deep rooting conferred by DEEPER ROOTING 1 enhances rice yield in paddy fields

    PubMed Central

    Arai-Sanoh, Yumiko; Takai, Toshiyuki; Yoshinaga, Satoshi; Nakano, Hiroshi; Kojima, Mikiko; Sakakibara, Hitoshi; Kondo, Motohiko; Uga, Yusaku

    2014-01-01

    To clarify the effect of deep rooting on grain yield in rice (Oryza sativa L.) in an irrigated paddy field with or without fertilizer, we used the shallow-rooting IR64 and the deep-rooting Dro1-NIL (a near-isogenic line homozygous for the Kinandang Patong allele of DEEPER ROOTING 1 (DRO1) in the IR64 genetic background). Although total root length was similar in both lines, more roots were distributed within the lower soil layer of the paddy field in Dro1-NIL than in IR64, irrespective of fertilizer treatment. At maturity, Dro1-NIL showed approximately 10% higher grain yield than IR64, irrespective of fertilizer treatment. Higher grain yield of Dro1-NIL was mainly due to the increased 1000-kernel weight and increased percentage of ripened grains, which resulted in a higher harvest index. After heading, the uptake of nitrogen from soil and leaf nitrogen concentration were higher in Dro1-NIL than in IR64. At the mid-grain-filling stage, Dro1-NIL maintained higher cytokinin fluxes from roots to shoots than IR64. These results suggest that deep rooting by DRO1 enhances nitrogen uptake and cytokinin fluxes at late stages, resulting in better grain filling in Dro1-NIL in a paddy field in this study. PMID:24988911

  17. Paddy field--a natural sequential anaerobic-aerobic bioreactor for polychlorinated biphenyls transformation.

    PubMed

    Chen, Chen; Yu, Chunna; Shen, Chaofeng; Tang, Xianjin; Qin, Zhihui; Yang, Kai; Hashmi, Muhammad Zaffar; Huang, Ronglang; Shi, Huixiang

    2014-07-01

    The environmental pollution and health risks caused by the improper disposal of electric and electronic waste (e-waste) have become urgent issues for the developing countries. One of the typical pollutants, polychlorinated biphenyls (PCBs), is commonly found in farmland in Taizhou, a major hotspot of e-waste recycling in China. This study investigated the amount of PCB residue in local farmlands. Biotransformation of PCBs was further studied under different water management conditions in paddy field with or without rice cultivation, with a special focus on the alternating flooded and drying processes. It was found that paddy field improved the attenuation of PCBs, especially for highly chlorinated congeners. In the microcosm experiment, 40% or more of the initial total PCBs was removed after sequential flood-drying treatments, compared to less than 10% in the sterilized control and 20% in the constant-drying system. Variation in the quantity of PCBs degrading and dechlorinating bacterial groups were closely related to the alteration of anaerobic-aerobic conditions. These results suggested that alternating anoxic-oxic environment in paddy field led to the sequential aerobic-anaerobic transformation of PCBs, which provided a favorable environment for natural PCB attenuation. PMID:24721413

  18. Heavy metal contamination of paddy soils and rice ( Oryza sativa L.) from Ko?ani Field (Macedonia)

    Microsoft Academic Search

    Nastja Rogan; Todor Serafimovski; Matej Dolenec; Goran Tasev; Tadej Dolenec

    2009-01-01

    This research focuses on the heavy metal contamination of the paddy soils and rice from Ko?ani Field (eastern Macedonia) resulting\\u000a from irrigation by riverine water impacted by past and present base-metal mining activities and acid mine drainage. Very high\\u000a concentrations of As, Cd, Cu, Pb and Zn were found in the paddy soils (47.6, 6.4, 99, 983 and 1,245 ?g g?1) and

  19. Microbial fuel cell as mitigation strategy for methane emissions from paddy field

    NASA Astrophysics Data System (ADS)

    Rizzo, Anacleto; Boano, Fulvio; Revelli, Roberto; Ridolfi, Luca

    2013-04-01

    Microbial fuel cells (MFCs) are bioelectrochemical systems able to generate electricity from wetland soils, including paddies, exploiting the microbial decomposition of organic matter. A MFC is composed of an anode buried in the anaerobic submerged soil linked to a cathode placed on the top of the soil in the aerobic ponding water. A biofilm develops on the anode, where bacteria release electrons, oxidizing dissolved organic carbon (DOC) and using oxygen available at the cathode as electron acceptor. MFC technology is now in an early development stage and the efficiency in electricity production is still low. However, MFC can also be applied for secondary aims, among which one of great interest is the reduction of methane (CH4) emissions from paddy fields. Indeed, DOC oxidation at the anode can be seen as an additional DOC sink in paddy soil environment, limiting the DOC availability for methanogens. In this work, a process-based mathematical model is proposed for a preliminary investigation of the efficiency of MFCs in limiting CH4 emissions. The model relies on a system of partial differential mass balance equations to describe the vertical dynamics of the chemical compounds leading to CH4 production. Many physico-chemical processes and features characteristic of paddy soil are included: paddy soil stratigraphy; spatio-temporal variations of plant-root compartment; water and heat transport; SOC decomposition; heterotrophic reactions in both aerobic and anaerobic conditions; root radial oxygen loss; root solute uptake; DOC root exudation; plant-mediated, ebullition, and diffusion gas exchange pathways. MFC is modeled as a DOC sink term, following a zero-order kinetic where the current density is assumed constant for the whole growing season. Different values of current density are tested, in accordance with values reported in literature about efficiency reached in paddy soils. Our results show a reduction of CH4 emissions up to -28.1%, -24.1%, and -26.5% of daily minimum, daily maximum and total over the whole growing season, respectively, confirming the potential validity of MFC as a novel CH4 mitigation strategy. Moreover, it is shown that transport processes limit the mitigation of CH4 emissions at high current density. Finally, in order to maximize the reduction of CH4 emissions, simulation results suggest to place the anode in the middle portion of the superficial layer.

  20. Seasonal and diurnal variations in net carbon dioxide flux throughout the year from soil in paddy field

    NASA Astrophysics Data System (ADS)

    Nishimura, Seiichi; Yonemura, Seiichiro; Minamikawa, Kazunori; Yagi, Kazuyuki

    2015-01-01

    contrast to upland croplands, carbon dioxide (CO2) emission from soils has rarely been investigated previously in fields with paddy rice cultivation. In this study, we hypothesized that CO2 emission from paddy soils is suppressed to be a low level due the soil submergence for months for paddy rice cultivation and conducted a continuous measurement of net CO2 flux from the soil/water surface of a paddy field throughout the year, including both the submerged and drained periods. The net CO2 flux was generally near zero during the submerged period with paddy rice cultivation and showed a slight CO2 influx in the daytime and efflux at nighttime, indicating dominance of photosynthetic CO2 uptake and respiratory CO2 release by aquatic weeds and algae in paddy water. The diurnal variations in net CO2 flux and dissolved CO2 concentration had negative correlations with the pH of paddy water. A remarkably high CO2 efflux was observed during the period with intermittent drainage in summer. Unexpectedly, the cumulative CO2 emissions throughout the year were not considerably lower than those reported in upland croplands ranging from 1309 to 2160 g CO2 m-2 yr-1, of which 41-48% was emitted from the first drainage in summer to the rice harvest in autumn. In summary, in this study, we revealed that CO2 emission from soil in paddy fields is strictly suppressed during the submerged period, but considerably enhanced by the succeeding drainage, which may negate the suppressed CO2 emission during the submerged period.

  1. Mapping paddy rice planting area in cold temperate climate region through analysis of time series Landsat 8 (OLI), Landsat 7 (ETM+) and MODIS imagery

    NASA Astrophysics Data System (ADS)

    Qin, Yuanwei; Xiao, Xiangming; Dong, Jinwei; Zhou, Yuting; Zhu, Zhe; Zhang, Geli; Du, Guoming; Jin, Cui; Kou, Weili; Wang, Jie; Li, Xiangping

    2015-07-01

    Accurate and timely rice paddy field maps with a fine spatial resolution would greatly improve our understanding of the effects of paddy rice agriculture on greenhouse gases emissions, food and water security, and human health. Rice paddy field maps were developed using optical images with high temporal resolution and coarse spatial resolution (e.g., Moderate Resolution Imaging Spectroradiometer (MODIS)) or low temporal resolution and high spatial resolution (e.g., Landsat TM/ETM+). In the past, the accuracy and efficiency for rice paddy field mapping at fine spatial resolutions were limited by the poor data availability and image-based algorithms. In this paper, time series MODIS and Landsat ETM+/OLI images, and the pixel- and phenology-based algorithm are used to map paddy rice planting area. The unique physical features of rice paddy fields during the flooding/open-canopy period are captured with the dynamics of vegetation indices, which are then used to identify rice paddy fields. The algorithm is tested in the Sanjiang Plain (path/row 114/27) in China in 2013. The overall accuracy of the resulted map of paddy rice planting area generated by both Landsat ETM+ and OLI is 97.3%, when evaluated with areas of interest (AOIs) derived from geo-referenced field photos. The paddy rice planting area map also agrees reasonably well with the official statistics at the level of state farms (R2 = 0.94). These results demonstrate that the combination of fine spatial resolution images and the phenology-based algorithm can provide a simple, robust, and automated approach to map the distribution of paddy rice agriculture in a year.

  2. Comparative metagenomics of anode-associated microbiomes developed in rice paddy-field microbial fuel cells.

    PubMed

    Kouzuma, Atsushi; Kasai, Takuya; Nakagawa, Gen; Yamamuro, Ayaka; Abe, Takashi; Watanabe, Kazuya

    2013-01-01

    In sediment-type microbial fuel cells (sMFCs) operating in rice paddy fields, rice-root exudates are converted to electricity by anode-associated rhizosphere microbes. Previous studies have shown that members of the family Geobacteraceae are enriched on the anodes of rhizosphere sMFCs. To deepen our understanding of rhizosphere microbes involved in electricity generation in sMFCs, here, we conducted comparative analyses of anode-associated microbiomes in three MFC systems: a rice paddy-field sMFC, and acetate- and glucose-fed MFCs in which pieces of graphite felt that had functioned as anodes in rice paddy-field sMFC were used as rhizosphere microbe-bearing anodes. After electric outputs became stable, microbiomes associated with the anodes of these MFC systems were analyzed by pyrotag sequencing of 16S rRNA gene amplicons and Illumina shotgun metagenomics. Pyrotag sequencing showed that Geobacteraceae bacteria were associated with the anodes of all three systems, but the dominant Geobacter species in each MFC were different. Specifically, species closely related to G. metallireducens comprised 90% of the anode Geobacteraceae in the acetate-fed MFC, but were only relatively minor components of the rhizosphere sMFC and glucose-fed MFC, whereas species closely related to G. psychrophilus were abundantly detected. This trend was confirmed by the phylogenetic assignments of predicted genes in shotgun metagenome sequences of the anode microbiomes. Our findings suggest that G. psychrophilus and its related species preferentially grow on the anodes of rhizosphere sMFCs and generate electricity through syntrophic interactions with organisms that excrete electron donors. PMID:24223712

  3. A study on characteristics of Methane emission from a periodically irrigated paddy field in Japan

    NASA Astrophysics Data System (ADS)

    Wakikuromaru, N.; Iwata, T.; Yagi, K.

    2014-12-01

    Methane (CH4) is generated by organic matter decomposition in the anaerobic soil. Paddy field is one of the most important eco-system in monsoon Asia. It is said that about 10% of CH4sources is paddy fields (IPCC AR4, 2007). In this study, methane emission from a single-rice crop field was estimated by long-term micrometeorological measurements. Methane emission was calculated by the aerodynamic gradient technique from January 2011 to August 2014. Intermittent water management was carried out during cultivation period at the observational site, HCH, located in Okayama, Japan. 3-days flood and 4-days drained condition were regularly repeated from late-June to early October. Seasonal variations of CH4flux for irrigation term from 2011 to 2013 were shown in Fig.1. Remarkably large fluxes were shown at early stage of irrigation term in 2011.It seemed to be caused by the relatively longer flooded condition that the first flooded period was 20 days. Flux in 2012 was smaller than in other year through the entire irrigation period. Rapid rise in flux for early August and gradual decrease between late August and September were shown in 2013. Fluxes under drained condition showed larger emission than under flooded condition. Cumulative CH4 emissions during cultivated period from 2011 to 2013 were estimated 15.7, 8.6, and 12.9 gC/m2, respectively.

  4. Characteristics of Nitrogen and Phosphorus Effluent Load from a Paddy-field District Implementing Crop Rotation

    NASA Astrophysics Data System (ADS)

    Hama, Takehide; Aoki, Takeru; Osuga, Katsuyuki; Nakamura, Kimihito; Sugiyama, Sho; Kawashima, Shigeto

    Implementation of collective crop rotation in a paddy-field district may increase nutrients effluent load. We have investigated a paddy-field district implementing collective crop rotation of wheat and soybeans, measured temporal variations in nutrients concentration of drainage water and the amount of discharged water for consecutive three years, and estimated nutrients effluent load from the district during the irrigation and non-irrigation periods. As a result, the highest concentration of nutrients was observed during the non-irrigation period in every investigation year. It was shown that high nutrients concentration of drainage water during the non-irrigation period was caused by runoff of fertilizer applied to wheat because the peaks of nutrients concentration of drainage water were seen in rainy days after fertilizer application in the crop-rotation field. The effluent load during the non-irrigation periods was 16.9-22.1 kgN ha-1 (nitrogen) and 0.84-1.42 kgP ha-1 (phosphorus), which respectively accounted for 46-66% and 27-54% of annual nutrients effluent load.

  5. Can arbuscular mycorrhiza and fertilizer management reduce phosphorus runoff from paddy fields?

    PubMed

    Zhang, Shujuan; Wang, Li; Ma, Fang; Zhang, Xue; Li, Zhe; Li, Shiyang; Jiang, Xiaofeng

    2015-07-01

    Our study sought to assess how much phosphorus (P) runoff from paddy fields could be cut down by fertilizer management and inoculation with arbuscular mycorrhizal fungi. A field experiment was conducted in Lalin River basin, in the northeast China: six nitrogen-phosphorus-potassium fertilizer levels were provided (0, 20%, 40%, 60%, 80%, and 100% of the recommended fertilizer supply), with or without inoculation with Glomus mosseae. The volume and concentrations of particle P (PP) and dissolved P (DP) were measured for each runoff during the rice growing season. It was found that the seasonal P runoff, including DP and PP, under the local fertilization was 3.7kg/ha, with PP, rather than DP, being the main form of P in runoff water. Additionally, the seasonal P runoff dropped only by 8.9% when fertilization decreased by 20%; rice yields decreased with declining fertilization. We also found that inoculation increased rice yields and decreased P runoff at each fertilizer level and these effects were lower under higher fertilization. Conclusively, while rice yields were guaranteed arbuscular mycorrhizal inoculation and fertilizer management would play a key role in reducing P runoff from paddy fields. PMID:26141895

  6. Factors Affecting Groundwater Chemistry in Abandoned Terraced Paddy Fields on Sado Island, Japan

    NASA Astrophysics Data System (ADS)

    Oyanagi, Nobuhiro; Nakata, Makoto; Matsuyama, Keiko; Tsujii, Norie; Tsuchida, Takeyoshi

    The factors affecting the groundwater level and chemistry in abandoned terraced paddy fields on Sado Island, Japan, were investigated. Seasonal changes of the groundwater level in site A, which is on the bottom of the slope, was slight throughout the year compared with that in site B, which is on the middle part of the gentle slope. EC, pH, and some components involved in mineral weathering (Na+, Ca2+ and alkalinity) in the groundwater from site A were higher than those from site B. These results showed that the infiltrating water from the upper part of the slope was the main source of the groundwater in site A. On the other hand, the impact of sea salt components (Na+ and Cl-) was evident in site B, because the concentration of these components increased during winter. Groundwater chemistry was also affected by other factors such as the dilution of groundwater caused by rainfall, sulfur redox, and nutrient uptake by vegetation. The effects of each factor on groundwater chemistry differed between sites because the topography of the two adjacent sites was different. The characteristics of water environment, such as the groundwater level and chemistry, should be considered in the management of abandoned terraced paddy fields on Sado Island.

  7. Environmental contamination and seasonal variation of metals in soils, plants and waters in the paddy fields around a Pb?Zn mine in Korea

    Microsoft Academic Search

    Myung Chae Jung; Iain Thornton

    1997-01-01

    The objective of this study is to investigate the extent and degree of heavy metal contamination of paddy fields influenced by metalliferous mining activity. Paddy soils, rice plants and irrigation waters were sampled along six traverse lines in the vicinity of the mine and nearby control site. Soil samples were taken 30, 80 and 150 days after rice transplanting, to

  8. Heavy Metals Uptake by Asian Swamp Eel, Monopterus albus from Paddy Fields of Kelantan, Peninsular Malaysia: Preliminary Study.

    PubMed

    Yin, Sow Ai; Ismail, Ahmad; Zulkifli, Syaizwan Zahmir

    2012-12-01

    Swamp eel, Monopterus albus is one of the common fish in paddy fields, thus it is suitable to be a bio-monitor for heavy metals pollution studies in paddy fields. This study was conducted to assess heavy metals levels in swamp eels collected from paddy fields in Kelantan, Malaysia. The results showed zinc [Zn (86.40 ?g/g dry weight)] was the highest accumulated metal in the kidney, liver, bone, gill, muscle and skin. Among the selected organs, gill had the highest concentrations of lead (Pb), cadmium (Cd) and nickel (Ni) whereas muscle showed the lowest total metal accumulation of Zn, Pb, copper (Cu), Cd and Ni. Based on the Malaysian Food Regulation, the levels of Zn and Cu in edible parts (muscle and skin) were within the safety limits. However, Cd, Pb and Ni exceeded the permissible limits. By comparing with the maximum level intake (MLI), Pb, Ni and Cd in edible parts can still be consumed. This investigation indicated that M. albus from paddy fields of Kelantan are safe for human consumption with little precaution. PMID:24575231

  9. Heavy Metals Uptake by Asian Swamp Eel, Monopterus albus from Paddy Fields of Kelantan, Peninsular Malaysia: Preliminary Study

    PubMed Central

    Yin, Sow Ai; Ismail, Ahmad; Zulkifli, Syaizwan Zahmir

    2012-01-01

    Swamp eel, Monopterus albus is one of the common fish in paddy fields, thus it is suitable to be a bio-monitor for heavy metals pollution studies in paddy fields. This study was conducted to assess heavy metals levels in swamp eels collected from paddy fields in Kelantan, Malaysia. The results showed zinc [Zn (86.40 ?g/g dry weight)] was the highest accumulated metal in the kidney, liver, bone, gill, muscle and skin. Among the selected organs, gill had the highest concentrations of lead (Pb), cadmium (Cd) and nickel (Ni) whereas muscle showed the lowest total metal accumulation of Zn, Pb, copper (Cu), Cd and Ni. Based on the Malaysian Food Regulation, the levels of Zn and Cu in edible parts (muscle and skin) were within the safety limits. However, Cd, Pb and Ni exceeded the permissible limits. By comparing with the maximum level intake (MLI), Pb, Ni and Cd in edible parts can still be consumed. This investigation indicated that M. albus from paddy fields of Kelantan are safe for human consumption with little precaution. PMID:24575231

  10. [Prevention efficiency of Exserohilum monoceras with chemical herbicides against Echinochloa crus-galli in paddy field].

    PubMed

    Chen, Yong; Ni, Hanwen; Zhang, Hongjun; Li, Xiaojing; Li, Jianqiang

    2005-06-01

    This paper studied the impact of several herbicides on the conidium germination of Exserohilum monoceras strain X27 in petri dish, and the synergistic effects of the pathogen and chemical herbicide quinclorac or propanil against Echinochloa crus-galli in greenhouse. The prevention efficiency of the tank-mixture of pathogen and quinclorac was also evaluated in paddy field. The results showed that test herbicides except quinclorac and bensulfulfuronmethyl could inhibit conidium germination and hypha growth to different degree. A significant synergism was observed between the pathogen and quinclorac. Adding quinclorac could obviously increase the prevention efficiency against Echinochloa crus-galli. Under field condition, the single use of pathogen could only control about 60% of the weed, while the efficiency of pathogen-quinclorac mixture could reach 90%. PMID:16180763

  11. Geofractionation of heavy metals and application of indices for pollution prediction in paddy field soil of Tumpat, Malaysia.

    PubMed

    Sow, Ai Yin; Ismail, Ahmad; Zulkifli, Syaizwan Zahmir

    2013-12-01

    The present study investigates the concentration of Pb, Cd, Ni, Zn, and Cu in the paddy field soils collected from Tumpat, Kelantan. Soil samples were treated with sequential extraction to distinguish the anthropogenic and lithogenic origin of Pb, Cd, Ni, Zn, and Cu. ELFE and oxidizable-organic fractions were detected as the lowest accumulation of Pb, Cd, Ni, Zn, and Cu. Therefore, all the heavy metals examined were concentrated, particularly in resistant fraction, indicating that those heavy metals occurred and accumulated in an unavailable form. The utilization of agrochemical fertilizers and pesticides might not elevate the levels of heavy metals in the paddy field soils. In comparison, the enrichment factor and geoaccumulation index for Pb, Cd, Ni, Zn, and Cu suggest that these heavy metals have the potential to cause environmental risk, although they present abundance in resistant fraction. Therefore, a complete study should be conducted based on the paddy cycle, which in turn could provide a clear picture of heavy metals distribution in the paddy field soils. PMID:23757028

  12. Influence of rice growth on the fate of polycyclic aromatic hydrocarbons in a subtropical paddy field: a life cycle study.

    PubMed

    Wang, Yan; Wang, Shaorui; Luo, Chunling; Xu, Yue; Pan, Suhong; Li, Jun; Ming, Lili; Zhang, Gan; Li, Xiangdong

    2015-01-01

    We measured the concentrations and profiles of polycyclic aromatic hydrocarbons (PAHs) in the soil, water, and rice tissues from a typical subtropical paddy system at various stages of rice growth over two growing seasons. Rice growth had a significant impact on the distribution and dissipation of PAHs in the paddy field. While rice was growing, the concentrations of PAHs in the soils decreased at an average decline rate of 5.3±2.9 ng PAHs g(-1) soild(-1), whereas, the concentrations of PAHs in rice tissues increased with growth time. However, the concentrations of PAHs in the rice leaves decreased during the heading stage of both two growing seasons. PAH profiles in soil, water, and different rice tissues also showed different patterns with the growing time of rice. Irrigation water was a significant source of PAHs to the paddy field. Rice growth enhanced the dissipation and transport of PAHs in the paddy system, while the sewage irrigation and straw burning after harvest added or returned PAHs to the system. For food safety precaution, sewage irrigation and straw burning should be well monitored and controlled. PMID:25460766

  13. Sexual difference of lifetime movement in adults of the Japanese skimmer, Orthetrum japonicum (Odonata: Libellulidae), in a forest-paddy field complex

    Microsoft Academic Search

    Mamoru Watanabe; Takayoshi Higashi

    1989-01-01

    The mark-and-recapture method was used to study the lifetime movement of the Japanese skimmer,Orthetrum japonicum, in a forest-paddy field complex in the warmtemperate zone of Japan. The flight season was from mid April to late June. The\\u000a age structure showed that the maiden flight occurred towards the forest from the emergence sites (paddy fields) for both sexes.\\u000a The insects returned

  14. Characterization of soil heavy metal pools in paddy fields in Taiwan: chemical extraction and solid-solution partitioning

    Microsoft Academic Search

    Paul F. Römkens; Horng-Yuh Guo; Chien-Liang Chu; Tsang-Sen Liu; Chih-Feng Chiang; Gerwin F. Koopmans

    2009-01-01

    Background, aim, and scope  Ongoing industrialization has resulted in an accumulation of metals like Cd, Cu, Cr, Ni, Zn, and Pb in paddy fields across\\u000a Southeast Asia. Risks of metals in soils depend on soil properties and the availability of metals in soil. At present, however,\\u000a limited information is available on how to measure or predict the directly available fraction of

  15. Alterations of biochemical indicators in hepatopancreas of the golden apple snail, Pomacea canaliculata, from paddy fields in Taiwan.

    PubMed

    Chiu, Yuh-Wen; Wu, Jui-Pin; Hsieh, Tsung-Chih; Liang, Shih-Hsiung; Chen, Chien-Min; Huang, Da-Ji

    2014-07-01

    The freshwater golden apple snail, Pomacea canaliculata, is one of the world's 100 worst invasive alien species. The snails' wide distribution, high abundance, and sensitivity to environmental pollution make them a potential bioindicator for environmental contamination. In this study, the biochemical status of golden apple snails collected from paddy fields throughout the island of Taiwan was examined. This study found that the biochemical status of apple snails collected from paddy fields differed from that of animals bred and maintained in the laboratory. Furthermore, certain biochemical endpoints of the snails collected from the paddy fields before and after agricultural activities were also different-hemolymphatic vitellogenin protein was induced in male snail after exposure to estrogen-like chemicals, the hepatic monooxygenase (1.97 +/- 0.50 deltaA(650mm) 30 min(-1) mg(-1) protein in control group) and glutathione S transferase (0.02 +/- 0.01 delta A(340mm) 30 min(-1) mg(-1) protein in control group) snails exposed to pesticides, as well as the hepatopancreatic levels of aspartate aminotransferase (450.00 +/- 59.40 U mg(-1) mg(-1) protein in control group) and alanine aminotransferase (233.27 +/- 42.09 U mg(-1) mg(-1) protein in control group) decreased the indicating that xenobiotics destroyed hepatopancreatic. The above findings reveal that apple snail could be used as a practical bioindicator to monitor anthropogenic environmental pollution. PMID:25004751

  16. Major and trace elements in paddy soil contaminated by Pb-Zn mining: a case study of Kocani Field, Macedonia.

    PubMed

    Dolenec, Tadej; Serafimovski, Todor; Tasev, Goran; Dobnikar, Meta; Dolenec, Matej; Rogan, Nastja

    2007-02-01

    The objective of this study was to assess the bulk chemical composition as well as the extent and severity of heavy metal contamination in the paddy soil of Kocani Field (eastern Macedonia). The results revealed that the paddy soil of the western part of Kocani Field is severely contaminated with Pb, Zn, As and Cd in the vicinity of the Zletovska River due to irrigation with riverine water that is severely affected by acid mine and tailing effluents from the Pb-Zn mine in Zletovo. The detected total concentrations of these metals are far above the threshold values considered to be phytotoxically excessive for surface soil. The paddy soil in the vicinity of the Zletovska River was also found to exhibit elevated levels of Ba, Th, U, V, W, Mo, Cu, Sb, Bi, Ag, Au, Hg and Tl, with concentrations above their generally accepted median concentration values obtained during this study. A correlation matrix revealed that the Mn and Fe oxides/hydroxides are the most important carrier phase for several trace elements, with the exception of rare earth elements (REEs). These also represent a major sink for the observed heavy metal pollution of the soil. REEs are mostly associated with two phases: light (L)REEs are bound to K-Al, while heavy (H)REEs are bound to Mg-bearing minerals. Although there is no direct evidence of a health risk, the paddy soil in the vicinity of Zletovska River needs further investigation and an assessment should be made of its suitability for agricultural use, particularly in view of the highly elevated concentrations of Pb, Zn, As and Cd. PMID:17120100

  17. Geochemical associations and availability of cadmium (Cd) in a paddy field system, northwestern Thailand.

    PubMed

    Kosolsaksakul, Peerapat; Farmer, John G; Oliver, Ian W; Graham, Margaret C

    2014-04-01

    The Mae Tao watershed, northwest Thailand, has become contaminated with cadmium (Cd) as a result of zinc ore extraction (Padaeng deposit) in the nearby Thanon-Thongchai mountains. Consumption of contaminated rice has led to documented human health impacts. The aim of this study was to elucidate transfer pathways from creek and canal waters to the paddy field soils near Baan Mae Tao Mai village and to determine the relationship between Cd speciation in the soil and uptake by rice plants. Transfer mainly occurred in association with particulate matter during flooding and channel dredging and, in contrast with many other studies, most of the soil Cd was associated with exchangeable and carbonate-bound fractions. Moreover, there was a linear relationship between soil total Cd and rice grain Cd (R(2) = 0.715), but a stronger relationship between both the Tessier-exchangeable soil Cd and the BCR-exchangeable soil Cd and rice grain Cd (R(2) = 0.898 and 0.862, respectively). PMID:24502996

  18. Mapping Spatial Variability of Soil Salinity in a Coastal Paddy Field Based on Electromagnetic Sensors

    PubMed Central

    Guo, Yan; Huang, Jingyi; Shi, Zhou; Li, Hongyi

    2015-01-01

    In coastal China, there is an urgent need to increase land area for agricultural production and urban development, where there is a rapid growing population. One solution is land reclamation from coastal tidelands, but soil salinization is problematic. As such, it is very important to characterize and map the within-field variability of soil salinity in space and time. Conventional methods are often time-consuming, expensive, labor-intensive, and unpractical. Fortunately, proximal sensing has become an important technology in characterizing within-field spatial variability. In this study, we employed the EM38 to study spatial variability of soil salinity in a coastal paddy field. Significant correlation relationship between ECa and EC1:5 (i.e. r >0.9) allowed us to use EM38 data to characterize the spatial variability of soil salinity. Geostatistical methods were used to determine the horizontal spatio-temporal variability of soil salinity over three consecutive years. The study found that the distribution of salinity was heterogeneous and the leaching of salts was more significant in the edges of the study field. By inverting the EM38 data using a Quasi-3D inversion algorithm, the vertical spatio-temporal variability of soil salinity was determined and the leaching of salts over time was easily identified. The methodology of this study can be used as guidance for researchers interested in understanding soil salinity development as well as land managers aiming for effective soil salinity monitoring and management practices. In order to better characterize the variations in soil salinity to a deeper soil profile, the deeper mode of EM38 (i.e., EM38v) as well as other EMI instruments (e.g. DUALEM-421) can be incorporated to conduct Quasi-3D inversions for deeper soil profiles. PMID:26020969

  19. Mapping spatial variability of soil salinity in a coastal paddy field based on electromagnetic sensors.

    PubMed

    Guo, Yan; Huang, Jingyi; Shi, Zhou; Li, Hongyi

    2015-01-01

    In coastal China, there is an urgent need to increase land area for agricultural production and urban development, where there is a rapid growing population. One solution is land reclamation from coastal tidelands, but soil salinization is problematic. As such, it is very important to characterize and map the within-field variability of soil salinity in space and time. Conventional methods are often time-consuming, expensive, labor-intensive, and unpractical. Fortunately, proximal sensing has become an important technology in characterizing within-field spatial variability. In this study, we employed the EM38 to study spatial variability of soil salinity in a coastal paddy field. Significant correlation relationship between ECa and EC1:5 (i.e. r >0.9) allowed us to use EM38 data to characterize the spatial variability of soil salinity. Geostatistical methods were used to determine the horizontal spatio-temporal variability of soil salinity over three consecutive years. The study found that the distribution of salinity was heterogeneous and the leaching of salts was more significant in the edges of the study field. By inverting the EM38 data using a Quasi-3D inversion algorithm, the vertical spatio-temporal variability of soil salinity was determined and the leaching of salts over time was easily identified. The methodology of this study can be used as guidance for researchers interested in understanding soil salinity development as well as land managers aiming for effective soil salinity monitoring and management practices. In order to better characterize the variations in soil salinity to a deeper soil profile, the deeper mode of EM38 (i.e., EM38v) as well as other EMI instruments (e.g. DUALEM-421) can be incorporated to conduct Quasi-3D inversions for deeper soil profiles. PMID:26020969

  20. [Cultivated landscape pattern change due to the rice paddy expansion in Northeast China: A case study in Fujin].

    PubMed

    Du, Guo-ming; Pan, Tao; Yin, Zhe-rui; Dong, Jin-wei

    2015-01-01

    On the background of global climate change, agriculture in North China has been experiencing substantial modifications to adapt to the ongoing regional warming. One of the most significant land use change is the conversation from upland cropland to paddy cropland, which is characterized by the dramatic changes of agricultural landscape pattern. In this study, we generated land use maps in Fujin City in 2000 and 2013 by using Landsat TM imagery, and analyzed the landscape pattern changes (cropland composite, special distribution, and patch characteristics, etc.) of croplands by using landscape indices and empirical approach. The results indicated a rapid cropland increase from 512400 hm2(reclamation ratio 60.4%) in 2000 to 699300 hm2(reclamation 82.4%) in 2013, especially, the paddy cropland proportion in the total cropland increased from 6.7% to more than half (54.1%) , that is, the agricultural land use mode had changed from the initial stage of paddy agriculture to the intermediate stage. The reclamation area and common agricultural area showed different paddy agriculture development characteristics: in 2000, the paddy field ratios in the common agricultural area and reclamation area were similar (5.5% and 8.3% respectively); however, in 2013, the paddy field ratio in the common agricultural area (33.6%) was significantly lower than that in reclamation area (83.4%). In 2000, the total number of cropland patches was 2311 in the study, including 1010 patches from the common agricultural area and 1301 patches from the reclamation area. The coefficient of variation (CV) , and shape index (SI) of cropland patches in upland cropland were always higher than in paddy cropland. Upland cropland had larger mean patch size with the plaque area index above 60% and higher connectivity. The patch density of upland cropland was lower than that of paddy cropland. In the conversions to the intermediate and later stages of paddy agriculture, the patch number of cropland increased rapidly with different rates in upland and paddy croplands. The CV of paddy cropland patches increased while fluctuated in upland cropland. The SI of paddy cropland increased first and then decreased, while that of upland cropland decreased continuously. The mean patch sizes of paddy and upland croplands increased and decreased respectively. The patch density increased in upland cropland while decreased in paddy cropland. The connectivity of upland cropland decreased while that of paddy cropland increased. The staggered degree of both cropland types was enhanced from 2000 to 2013. In general, the paddy agriculture was becoming the dominated agricultural land use mode in the study area while the convesions had different rates in two administrative regions (reclamation and common agricultural areas). PMID:25985672

  1. Understanding the ecological background of rice agriculture on the Ningshao Plain during the Neolithic Age: pollen evidence from a buried paddy field at the Tianluoshan cultural site

    NASA Astrophysics Data System (ADS)

    Li, Chunhai; Zheng, Yunfei; Yu, Shiyong; Li, Yongxiang; Shen, Huadong

    2012-03-01

    The progressive rise of atmospheric CH4 level since 5 ka has been hypothesized to result from human agricultural activities that turned forested lands, which would otherwise be a carbon sink, into paddy fields. Increasing numbers of Neolithic cultural sites unearthed in coastal eastern China, providing unique opportunities to test this hypothesis. Here, we present detailed pollen data from a buried paddy field at Tianluoshan cultural site on the Ningshao Plain, eastern China, to reconstruct the ecological conditions associated with the establishment of paddy fields. Stratigraphic data, radiocarbon ages, and pollen analyses show that vegetation underwent six phases of evolution and paddy fields were developed from 7000 to 4200 cal. yr BP. We found no evidence of slash-and-burn agriculture at the study site. Together with no presence of the irrigation system, our pollen data suggest the paddy fields at this site originated from wetlands. Hence, our findings do not support the hypothesis that anthropogenic-induced deforestation play ed a significant role in the rise of the atmospheric CH4 rise since the middle Holocene.

  2. Partitioning of evapotranspiration using high-frequency water vapor isotopic measurement over a rice paddy field

    NASA Astrophysics Data System (ADS)

    Wei, Zhongwang; Yoshimura, Kei; Okazaki, Atsushi; Kim, Wonsik; Liu, Zhongfang; Yokoi, Masaharu

    2015-05-01

    Partitioning ecosystem evapotranspiration (ET) into soil evaporation (E) and transpiration (T) is crucial for understanding hydrological processes. In this study, by using high-frequency isotope measurements and continuous surface water measurements, we investigated the isotope ratios in soil-vegetation-atmosphere transfer and the physical mechanisms involved over a paddy field for a full growing season. The isotopic signals of ?ET, ?T, and ?E were determined by the Keeling plot method, surface water isotopic measurements, and the Craig-Gordon model, respectively. The fraction of transpiration in evapotranspiration (FT) ranged from 0.2 to 1, with an almost continuous increase in the early growing season and a relatively constant value close to 1 later in the year. The result was supported by FT derived from simulated T and eddy correlation measured ET. The seasonal change in the transpiration fraction could be described quite well as a function of the LAI (FT = 0.67LAI0.25, R2 = 0.80), implying that transpiration plays a dominant role in the soil-vegetation-atmosphere continuum during the growing season. The two end-member uncertainty analysis suggested that further improvement in the estimation of ?T and ?ET is necessary for partitioning evapotranspiration using the isotopic method. In the estimation of ?ET, the assumptions underlying Keeling plot method were rarely met and the uncertainty was quite large. A high frequency of precise isotopic measurements in surface water was also necessary for ?T estimation. Furthermore, special care must be taken concerning the kinetic fractionation parameter in the Craig and Gordon Equation for ?E estimation under low-LAI conditions. The results demonstrated the robustness of using isotope measurements for partitioning evapotranspiration.

  3. Partitioning of evapotranspiration through high frequency water vapor isotopic measurement over a paddy field

    NASA Astrophysics Data System (ADS)

    Wei, Z.; Okazaki, A.; Yokoi, M.; Kim, W.; Liu, Z.; Yoshimura, K.

    2014-12-01

    Partitioning the ecosystem evapotranspiration (ET) into soil evaporation (E) and transpiration (T) is challenging and crucial to understand hydrological processes in land. In this study, we deployed a recently developed partitioning technique using high frequency in-situ water vapor isotopic measurement and surface/soil water sampling over a paddy field near Tokyo, Japan for a full growing season. We partitioned ET via estimating the isotopic signal of ET (?ET) and its two components, i.e. T (?T) and E (?E). ?ET was determined through the use of Keeling plot. Estimates of ?T was obtained by direct measurement of surface/soil isotopic measurement assuming a steady state of transpiration. ?E was estimated using the Craig-Gordon model in combination with surface and vapor water isotopic measurement. The T/ET ranged approximately from 0.3 to 1, almost kept increasing during early growing season, then kept a relative constant value close to 1 after that. T/ET was strongly controlled by green leaf area index (LAI) in day to day time scale (y=0.14ln(x)+0.66; R-squared=0.62). We also investigated the uncertainties in estimating these three terms (?ET, ?T, and ?E) and their effect on ET partitioning. The uncertainty analysis showed the uncertainty from ?E had a minor impact on the ET partitioning but mainly controlled by uncertainty from ?T and ?ET estimations. During early growing season, ET partitioning uncertainty was mainly due to uneven spatial distribution of surface water isotope (?T). As LAI increases, the impact of ?ET uncertainty became much larger than the other two terms. The results demonstrated the robustness of using isotope measurements for partitioning evapotranspiration.

  4. Assessment of heavy metals (Cd and Pb) and micronutrients (Cu, Mn, and Zn) of paddy (Oryza sativa L.) field surface soil and water in a predominantly paddy-cultivated area at Puducherry (Pondicherry, India), and effects of the agricultural runoff on the elemental concentrations of a receiving rivulet.

    PubMed

    Reddy, M Vikram; Satpathy, Deepmala; Dhiviya, K Shyamala

    2013-08-01

    The concentrations of toxic heavy metals-Cd and Pb and micronutrients-Cu, Mn, and Zn were assessed in the surface soil and water of three different stages of paddy (Oryza sativa L.) fields, the stage I-the first stage in the field soon after transplantation of the paddy seedlings, holding adequate amount of water on soil surface, stage II-the middle stage with paddy plants of stem of about 40 cm length, with sufficient amount of water on the soil surface, and stage III-the final stage with fully grown rice plants and very little amount of water in the field at Bahour, a predominantly paddy cultivating area in Puducherry located on the southeast Coast of India. Comparison of the heavy metal and micronutrient concentrations of the soil and water across the three stages of paddy field showed their concentrations were significantly higher in soil compared with that of water (p?fields probably because of accumulation and adsorption in soil. The elemental concentrations in paddy soil as well as water was in the ranking order of Cd?>?Mn?>?Zn?>?Cu?>?Pb indicating concentration of Cd was maximum and Pb was minimum. The elemental concentrations in both soil and water across the three stages showed a ranking order of stage II?>?stage III?>?stage I. The runoff from the paddy fields has affected the elemental concentrations of the water and sediment of an adjacent receiving rivulet. PMID:23435848

  5. Monitoring and Analysis of Nonpoint Source Pollution - Case study on terraced paddy fields in an agricultural watershed

    NASA Astrophysics Data System (ADS)

    Chen, Shih-Kai; Jang, Cheng-Shin; Yeh, Chun-Lin

    2013-04-01

    The intensive use of chemical fertilizer has negatively impacted environments in recent decades, mainly through water pollution by nitrogen (N) and phosphate (P) originating from agricultural activities. As a main crop with the largest cultivation area about 0.25 million ha per year in Taiwan, rice paddies account for a significant share of fertilizer consumption among agriculture crops. This study evaluated the fertilization of paddy fields impacting return flow water quality in an agricultural watershed located at Hsinchu County, northern Taiwan. Water quality monitoring continued for two crop-periods in 2012, around subject to different water bodies, including the irrigation water, drainage water, and shallow groundwater. The results indicated that obviously increasing of ammonium-N, nitrate-N and TP concentrations in the surface drainage water were observed immediately following three times of fertilizer applications (including basal, tillering, and panicle fertilizer application), but reduced to relatively low concentrations after 7-10 days after each fertilizer application. Groundwater quality monitoring showed that the observation wells with the more shallow water depth, the more significant variation of concentrations of ammonium-N, nitrate-N and TP could be observed, which means that the contamination potential of nutrient of groundwater is related not only to the impermeable plow sole layer but also to the length of percolation route in this area. The study also showed that the potential pollution load of nutrient could be further reduced by well drainage water control and rational fertilizer management, such as deep-water irrigation, reuse of return flow, the rational application of fertilizers, and the SRI (The System of Rice Intensification) method. The results of this study can provide as an evaluation basis to formulate effective measures for agricultural non-point source pollution control and the reuse of agricultural return flow. Keywords:Chemical fertilizer, Nitrogen, Phosphorus, Paddy field, Non-point source pollution.

  6. The effect of fertilization on cesium concentration of rice grown in a paddy field in Fukushima Prefecture in 2011 and 2012.

    PubMed

    Ohmori, Yoshihiro; Kajikawa, Masataka; Nishida, Sho; Tanaka, Nobuhiro; Kobayashi, Natsuko I; Tanoi, Keitaro; Furukawa, Jun; Fujiwara, Toru

    2014-01-01

    After the accident of the Fukushima 1 nuclear power plant in March 2011, radioactive cesium was released and paddy field in a wide area of Fukushima Prefecture was contaminated. To reduce radioactive Cs uptake by rice, it is important to understand factors that affect Cs uptake in rice. Here we describe our study in 2011 and 2012 to investigate Cs concentration in two rice cultivars, Koshihikari and Hitomebore, the top two cultivars in Fukushima prefecture, grown under different fertilizer conditions in the contaminated paddy field. Our study demonstrated that high nitrogen and low potassium conditions increase Cs concentrations both in straw and brown rice. PMID:24338063

  7. Mapping paddy rice using multi-temporal Landsat imagery in the Sanjiang Plain, Northeast China

    NASA Astrophysics Data System (ADS)

    Jin, C.; Xiao, X.; Dong, J.; Wang, Z.; Song, K.

    2013-12-01

    Accurate information on cultivation area and spatial distribution of paddy rice is required for the regional food security, agriculture water management, and methane emission estimate. The 500m MODIS-based paddy rice mapping algorithm has been well applied to map rice cropping area and intensity through identifying the unique phenology phase during the growing season - field flooding/seedling transplanting using the time-series datasets of Normalized Difference Vegetation Index (NDVI), Enhance Vegetation index (EVI), and Land Surface Water Index (LSWI). In this study, a total number of 119 scenes of Landsat imagery were collected over the entire Sanjiang Plain, Northeast China in 2010-2012. Paddy rice has shown distinct phenological and spectral characteristics against other land types from the multi-temporal Landsat imagery during the flooding/transplanting (early-May to late-June) and ripening (late-August to Mid-September) periods, respectively. A 30m Landsat paddy rice map of the Sanjiang Plain was generated by composing flooding/transplanting and ripening based algorithms using the multi-temporal vegetation indices (NDVI, EVI, LSWI) as input. The resultant Landsat-based paddy rice map has been evaluated and compared using other four paddy rice datasets: (1) ground truth points collected during 2011 field campaign; (2) 2011 agricultural census data of counties; (3) the National Land Cover Dataset (1: 100, 000 scale) derived from the Landsat and CBERS-2 in 2010/2011; and (4) 500m paddy rice map generated from the multi-temporal MODIS vegetation indices imagery. We found that the Landsat paddy rice map has high accuracy (both producer and user accuracy is above 85%) on the basis of ground truth point validation. Agricultural census data tended to underestimate paddy rice area by 60% compared the rice area summarized from the Landsat paddy rice map. In addition, the Landsat paddy rice map had good consistency with the MODIS paddy rice map with the correlation coefficient of 0.9. In conclusion, this study showed the value of multi-temporal Landsat imagery at appropriate pheonolgical phases for identifying paddy rice on the regional scale.

  8. Liquid chromatographic-diode-array detection multiresidue determination of rice herbicides in drinking and paddy-field water.

    PubMed

    Roehrs, Rafael; Zanella, Renato; Pizzuti, Ionara; Adaime, Martha B; Pareja, Lucía; Niell, Silvina; Cesio, María V; Heinzen, Horacio

    2009-01-01

    A sensitive, rapid, and simple multiresidue method for the simultaneous determination of six postemergence herbicides currently used in rice cultivation--metsulfuron methyl, bensulfuron methyl, pyrazosulfuron ethyl, bentazone, bispyribac sodium, and cyhalofop butyl--in drinking and paddy-field water is presented. Water samples were extracted with solid-phase extraction cartridges. Final determination was made by LC with diode-array detection. The extraction efficiencies of C18 and HLB cartridges were compared. The average recovery obtained for these compounds for the lowest spiked level (0.1 microg/L) varied from 70 to 122% for C18 and 75-119% for HLB, with RSDs of 11 and 8.3%, respectively. The method had good linearity, and the lower detection limit for the pesticides studied varied from 0.03 to 0.04 microg/L. The proposed method was also tested in paddy-field water, with recovery studies giving good results with low RSDs at 1.0 microg/L. PMID:19714989

  9. Temporal variations in arsenic uptake by rice plants in Bangladesh: The role of iron plaque in paddy fields irrigated with groundwater

    E-print Network

    van Geen, Alexander

    Temporal variations in arsenic uptake by rice plants in Bangladesh: The role of iron plaque May 2010 Available online xxxx Keywords: Arsenic Rice (Oryza sativa) Paddy soil Soil water Iron plaque The transfer of arsenic to rice grains is a human health issue of growing relevance in regions of southern Asia

  10. Classification of the field drainage and wetness by using aerial photographs in irrigated paddy rice and upland crop rotation field

    NASA Astrophysics Data System (ADS)

    Ritsuko, Fuchiyama; Takeshi, Ota; Michikazu, Fukuhara

    2013-04-01

    Information about field drainage/wetness is useful for farmers to plan field management in irrigated paddy rice and upland crop rotation field. Wet injury is a loss to farmers in upland crop farming, experience is the most common way of approaching this risk. In this study, we propose to provide efficient and objective classify and mapping method of such field drainage information using aerial photography. Study area (500 ha) is located in Ibaraki Prefecture, Japan. In this area, we acquired multitemporalaerial photographs (ADS40) three times after the rain on winter. Digital Number (DN) of Blue, Green, Red and Near Infrared band were used to analyze. To analyze the relationship between each band DN and soil moisture, mass soil water content of 0-5cm depth was determined using the 100ml core sample at 22 sites on shooting date. And to verify our classification of the drainage and wetness, volumetric soil water content was monitored using TDR sensor (Decagon, ECH2O) at 5cm, 10cm and 20 cm depth at 16 sites. First, optimum band was selected from correlation analysis of mass soil water content and DN. Next, optimum band DN of three aerial photographs at field area was grouped by cluster analysis (ISODATA method). We found a good positive correlation between mass soil water content and red band DN, by selecting optimum bands. 17 groups were found from cluster analysis using three aerial photographs with different soil moisture conditions. After that, we classified them into five levels of field drainage based on red band DN values. We generated maps of drainage/wetness based on these results. We compared volumetric soil water content at the monitoring site for the "Dry" and "Wet" points, water was drained quickly at the "Dry" site but it needed more than 1 week the volume soil water content back to revert before rain at the "Wet" site. By the result, we positively verified our classification. We used three aerial photographs with different soil moisture conditions as proxy of top soil moisture content. It is thought to be an indication of drainage/wetness. Generally, estimating soil water content at field scale from a remote sensing data was difficult. But this method can classify the study area relatively. We think it is enough as a soil information for farmers.

  11. Impact of Azospirillum sp. B510 Inoculation on Rice-Associated Bacterial Communities in a Paddy Field

    PubMed Central

    Bao, Zhihua; Sasaki, Kazuhiro; Okubo, Takashi; Ikeda, Seishi; Anda, Mizue; Hanzawa, Eiko; Kakizaki, Kaori; Sato, Tadashi; Mitsui, Hisayuki; Minamisawa, Kiwamu

    2013-01-01

    Rice seedlings were inoculated with Azospirillum sp. B510 and transplanted into a paddy field. Growth in terms of tiller numbers and shoot length was significantly increased by inoculation. Principal-coordinates analysis of rice bacterial communities using the 16S rRNA gene showed no overall change from B510 inoculation. However, the abundance of Veillonellaceae and Aurantimonas significantly increased in the base and shoots, respectively, of B510-inoculated plants. The abundance of Azospirillum did not differ between B510-inoculated and uninoculated plants (0.02–0.50%). These results indicate that the application of Azospirillum sp. B510 not only enhanced rice growth, but also affected minor rice-associated bacteria. PMID:24256970

  12. Biochar amendment reduces rice Cd uptake in polluted and unpolluted paddy soils: a long term field experiment

    NASA Astrophysics Data System (ADS)

    Bian, R.; Cui, L.; Pan, G.; Li, L.

    2012-04-01

    The bioavailability of Cd in agricultural soils has been a great health concern due to the potential risk through exposure of agro-food produced in Cd-contaminated fields. Yet, rice subject to Cd contamination appears to have expanded at the last decade due to irrigation with waste water and chemical fertilization in south china. This is supposed to raise the Cd accumulation of rice grain. Therefore, techniques to reduce Cd mobility and plant uptake have been a urgent demand for food safety in China.A field experiment was performed in a high-polluted (HP), mid-pollute (MP) and unpolluted (UP) paddy soil with biochar(BC) amendment in 2011. BC was applied in HP, MP and UP in 2008, 2009, 2009 with the rates of 0, 10, 20, 40t ha-1 in HP, MP and 0, 40t ha-1 in UP. The experiment was monitored in 2011. It was observed that BC amendment did not affect rice grain yield but significantly increased soil pH by 0.58-0.77, 1.30 units in MP, UP and there was no difference in HP. The Cacl2 extracted Cd in soil was decreased by 18.1%-28.9% in HP, 49.3%-67.5% in MP and 83.1% in UP, respectively. Meanwhile, H2O extractable Cd in soil was decreased by 20.0%-31.7% in HP, 32.7%-44.2% in MP and 25.0% in UP, respectively. With the BC treatment, rice grain Cd concentration was decreased 4.7%-17.6% in HP, 35.9%-53.4% in MP. Especially in UP field, the rice grain Cd concentration was decreased from 0.22mg kg-1 to 0.07mg kg-1 which was below National standard (0.20mg kg-1) in China. The straw and root Cd contents were also significantly decreased with BC application. Therefore, BC amendment in polluted and unpolluted fields can sustainably reduce rice Cd uptake and it may offer a basic option to reduce Cd levels in rice. Keywords: Biochar, Cd, bioavailability, paddy soil, food safety

  13. Effect of Different Fertilizer Application on the Soil Fertility of Paddy Soils in Red Soil Region of Southern China

    PubMed Central

    Dong, Wenyi; Zhang, Xinyu; Wang, Huimin; Dai, Xiaoqin; Sun, Xiaomin; Qiu, Weiwen; Yang, Fengting

    2012-01-01

    Appropriate fertilizer application is an important management practice to improve soil fertility and quality in the red soil regions of China. In the present study, we examined the effects of five fertilization treatments [these were: no fertilizer (CK), rice straw return (SR), chemical fertilizer (NPK), organic manure (OM) and green manure (GM)] on soil pH, soil organic carbon (SOC), total nitrogen (TN), C/N ratio and available nutrients (AN, AP and AK) contents in the plowed layer (0–20 cm) of paddy soil from 1998 to 2009 in Jiangxi Province, southern China. Results showed that the soil pH was the lowest with an average of 5.33 units in CK and was significantly higher in NPK (5.89 units) and OM (5.63 units) treatments (P<0.05). The application of fertilizers have remarkably improved SOC and TN values compared with the CK, Specifically, the OM treatment resulted in the highest SOC and TN concentrations (72.5% and 51.2% higher than CK) and NPK treatment increased the SOC and TN contents by 22.0% and 17.8% compared with CK. The average amounts of C/N ratio ranged from 9.66 to 10.98 in different treatments, and reached the highest in OM treatment (P<0.05). During the experimental period, the average AN and AP contents were highest in OM treatment (about 1.6 and 29.6 times of that in the CK, respectively) and second highest in NPK treatment (about 1.2 and 20.3 times of that in the CK). Unlike AN and AP, the highest value of AK content was observed in NPK treatments with 38.10 mg·kg?1. Thus, these indicated that organic manure should be recommended to improve soil fertility in this region and K fertilizer should be simultaneously applied considering the soil K contents. Considering the long-term fertilizer efficiency, our results also suggest that annual straw returning application could improve soil fertility in this trial region. PMID:23028550

  14. Seasonal and diurnal variations of atmospheric PAHs and OCPs in a suburban paddy field, South China: Impacts of meteorological parameters and sources

    NASA Astrophysics Data System (ADS)

    Wang, Yan; Li, Qilu; Wang, Shaorui; Wang, Yujie; Luo, Chunling; Li, Jun; Zhang, Gan

    2015-07-01

    The atmospheric contaminations of polycyclic aromatic hydrocarbons (PAHs), hexachlorocyclohexanes (HCHs), and DDTs have been extensively monitored for decades, but contaminations in agricultural paddy fields have rarely been reported. We measured the atmospheric PAH, HCH, and DDT constituents during different rice growth stages in a suburban paddy field in South China. Diurnal variations were found in the atmospheric concentrations of PAHs and HCHs, but not for DDTs. Additional nocturnal emissions and meteorological conditions, such as low nocturnal stable atmospheric boundary layers, may be mainly responsible for the higher PAH and HCH levels at night, respectively. Atmospheric concentrations of PAH, HCH, and DDT constituents varied with rice growth stage, but no regular seasonal variation was found, suggesting that rice growth has no significant influence on the atmospheric concentrations of these chemicals. A correlation analysis suggested that meteorological parameters, such as temperature, precipitation, mixing layer height, or wind speed, may directly or indirectly affect the air concentrations of PAHs, HCHs, and DDTs. Source apportionment showed that atmospheric PAHs, HCHs, and DDTs in the paddy field originated from mixed sources, and the contribution of each source varied with time. The isomer ratio of fluoranthene/(fluoranthene + pyrene) may result in an invalid diagnosis of PAHs.

  15. Surfactant dependent self-organization of Co3O4 nanowires on Ni foam for high performance supercapacitors: from nanowire microspheres to nanowire paddy fields

    NASA Astrophysics Data System (ADS)

    Zhang, Xuan; Zhao, Yongqing; Xu, Cailing

    2014-03-01

    Different surfactants were used in a typical hydrothermal process for controlling the morphology of the Co3O4 nanowire superstructure on Ni foam. It is easy for the Co3O4 nanowires to self-organize into nanowire microspheres on Ni foam in the absence of surfactants. And the nanowire microspheres gradually unfold into nanowire paddy fields with the addition of nonionic, cationic and anionic surfactants, respectively. The results of BET and electrochemical measurements show that the specific surface area and capacitance first decrease and then increase with the change in the Co3O4 superstructure morphology. Among these electrodes, the Co3O4 electrode with paddy like nanowires shows an outstanding specific capacitance of 1217.4 F g-1 and areal specific capacitance as high as 6087 mF cm-2 at 0.7 A g-1 with high mass loading (5 mg cm-2), good power capability (showing a high specific capacitance of 835.1 F g-1 (4176 mF cm-2) at 5 A g-1), excellent cycling stability and high columbic efficiency (~100%). This exceptional performance is benefited from the almost monodispersed nanowire morphology and high specific surface area (121.4 m2 g-1). At the same time, the asymmetric supercapacitor, employing the Co3O4 electrode with paddy-like nanowires as the positive electrode and the activated carbon electrode as the negative electrode, was successfully assembled. It shows a high specific energy and good long-term electrochemical stability. All these impressive results demonstrate that the Co3O4 electrode with paddy-like nanowires is promising for practical applications in supercapacitors.Different surfactants were used in a typical hydrothermal process for controlling the morphology of the Co3O4 nanowire superstructure on Ni foam. It is easy for the Co3O4 nanowires to self-organize into nanowire microspheres on Ni foam in the absence of surfactants. And the nanowire microspheres gradually unfold into nanowire paddy fields with the addition of nonionic, cationic and anionic surfactants, respectively. The results of BET and electrochemical measurements show that the specific surface area and capacitance first decrease and then increase with the change in the Co3O4 superstructure morphology. Among these electrodes, the Co3O4 electrode with paddy like nanowires shows an outstanding specific capacitance of 1217.4 F g-1 and areal specific capacitance as high as 6087 mF cm-2 at 0.7 A g-1 with high mass loading (5 mg cm-2), good power capability (showing a high specific capacitance of 835.1 F g-1 (4176 mF cm-2) at 5 A g-1), excellent cycling stability and high columbic efficiency (~100%). This exceptional performance is benefited from the almost monodispersed nanowire morphology and high specific surface area (121.4 m2 g-1). At the same time, the asymmetric supercapacitor, employing the Co3O4 electrode with paddy-like nanowires as the positive electrode and the activated carbon electrode as the negative electrode, was successfully assembled. It shows a high specific energy and good long-term electrochemical stability. All these impressive results demonstrate that the Co3O4 electrode with paddy-like nanowires is promising for practical applications in supercapacitors. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr06734c

  16. Mapping paddy rice planting area in wheat-rice double-cropped areas through integration of Landsat-8 OLI, MODIS, and PALSAR images

    PubMed Central

    Wang, Jie; Xiao, Xiangming; Qin, Yuanwei; Dong, Jinwei; Zhang, Geli; Kou, Weili; Jin, Cui; Zhou, Yuting; Zhang, Yao

    2015-01-01

    As farmland systems vary over space and time (season and year), accurate and updated maps of paddy rice are needed for studies of food security and environmental problems. We selected a wheat-rice double-cropped area from fragmented landscapes along the rural–urban complex (Jiangsu Province, China) and explored the potential utility of integrating time series optical images (Landsat-8, MODIS) and radar images (PALSAR) in mapping paddy rice planting areas. We first identified several main types of non-cropland land cover and then identified paddy rice fields by selecting pixels that were inundated only during paddy rice flooding periods. These key temporal windows were determined based on MODIS Land Surface Temperature and vegetation indices. The resultant paddy rice map was evaluated using regions of interest (ROIs) drawn from multiple high-resolution images, Google Earth, and in-situ cropland photos. The estimated overall accuracy and Kappa coefficient were 89.8% and 0.79, respectively. In comparison with the National Land Cover Data (China) from 2010, the resultant map better detected changes in the paddy rice fields and revealed more details about their distribution. These results demonstrate the efficacy of using images from multiple sources to generate paddy rice maps for two-crop rotation systems. PMID:25965027

  17. Mapping paddy rice planting area in wheat-rice double-cropped areas through integration of Landsat-8 OLI, MODIS, and PALSAR images.

    PubMed

    Wang, Jie; Xiao, Xiangming; Qin, Yuanwei; Dong, Jinwei; Zhang, Geli; Kou, Weili; Jin, Cui; Zhou, Yuting; Zhang, Yao

    2015-01-01

    As farmland systems vary over space and time (season and year), accurate and updated maps of paddy rice are needed for studies of food security and environmental problems. We selected a wheat-rice double-cropped area from fragmented landscapes along the rural-urban complex (Jiangsu Province, China) and explored the potential utility of integrating time series optical images (Landsat-8, MODIS) and radar images (PALSAR) in mapping paddy rice planting areas. We first identified several main types of non-cropland land cover and then identified paddy rice fields by selecting pixels that were inundated only during paddy rice flooding periods. These key temporal windows were determined based on MODIS Land Surface Temperature and vegetation indices. The resultant paddy rice map was evaluated using regions of interest (ROIs) drawn from multiple high-resolution images, Google Earth, and in-situ cropland photos. The estimated overall accuracy and Kappa coefficient were 89.8% and 0.79, respectively. In comparison with the National Land Cover Data (China) from 2010, the resultant map better detected changes in the paddy rice fields and revealed more details about their distribution. These results demonstrate the efficacy of using images from multiple sources to generate paddy rice maps for two-crop rotation systems. PMID:25965027

  18. Evidence for the cooccurrence of nitrite-dependent anaerobic ammonium and methane oxidation processes in a flooded paddy field.

    PubMed

    Shen, Li-Dong; Liu, Shuai; Huang, Qian; Lian, Xu; He, Zhan-Fei; Geng, Sha; Jin, Ren-Cun; He, Yun-Feng; Lou, Li-Ping; Xu, Xiang-Yang; Zheng, Ping; Hu, Bao-Lan

    2014-12-01

    Anaerobic ammonium oxidation (anammox) and nitrite-dependent anaerobic methane oxidation (n-damo) are two of the most recent discoveries in the microbial nitrogen cycle. In the present study, we provide direct evidence for the cooccurrence of the anammox and n-damo processes in a flooded paddy field in southeastern China. Stable isotope experiments showed that the potential anammox rates ranged from 5.6 to 22.7 nmol N2 g(-1) (dry weight) day(-1) and the potential n-damo rates varied from 0.2 to 2.1 nmol CO2 g(-1) (dry weight) day(-1) in different layers of soil cores. Quantitative PCR showed that the abundance of anammox bacteria ranged from 1.0 × 10(5) to 2.0 × 10(6) copies g(-1) (dry weight) in different layers of soil cores and the abundance of n-damo bacteria varied from 3.8 × 10(5) to 6.1 × 10(6) copies g(-1) (dry weight). Phylogenetic analyses of the recovered 16S rRNA gene sequences showed that anammox bacteria affiliated with "Candidatus Brocadia" and "Candidatus Kuenenia" and n-damo bacteria related to "Candidatus Methylomirabilis oxyfera" were present in the soil cores. It is estimated that a total loss of 50.7 g N m(-2) per year could be linked to the anammox process, which is at intermediate levels for the nitrogen flux ranges of aerobic ammonium oxidation and denitrification reported in wetland soils. In addition, it is estimated that a total of 0.14 g CH4 m(-2) per year could be oxidized via the n-damo process, while this rate is at the lower end of the aerobic methane oxidation rates reported in wetland soils. PMID:25261523

  19. Evidence for the Cooccurrence of Nitrite-Dependent Anaerobic Ammonium and Methane Oxidation Processes in a Flooded Paddy Field

    PubMed Central

    Shen, Li-dong; Liu, Shuai; Huang, Qian; Lian, Xu; He, Zhan-fei; Geng, Sha; Jin, Ren-cun; He, Yun-feng; Lou, Li-ping; Xu, Xiang-yang; Zheng, Ping

    2014-01-01

    Anaerobic ammonium oxidation (anammox) and nitrite-dependent anaerobic methane oxidation (n-damo) are two of the most recent discoveries in the microbial nitrogen cycle. In the present study, we provide direct evidence for the cooccurrence of the anammox and n-damo processes in a flooded paddy field in southeastern China. Stable isotope experiments showed that the potential anammox rates ranged from 5.6 to 22.7 nmol N2 g?1 (dry weight) day?1 and the potential n-damo rates varied from 0.2 to 2.1 nmol CO2 g?1 (dry weight) day?1 in different layers of soil cores. Quantitative PCR showed that the abundance of anammox bacteria ranged from 1.0 × 105 to 2.0 × 106 copies g?1 (dry weight) in different layers of soil cores and the abundance of n-damo bacteria varied from 3.8 × 105 to 6.1 × 106 copies g?1 (dry weight). Phylogenetic analyses of the recovered 16S rRNA gene sequences showed that anammox bacteria affiliated with “Candidatus Brocadia” and “Candidatus Kuenenia” and n-damo bacteria related to “Candidatus Methylomirabilis oxyfera” were present in the soil cores. It is estimated that a total loss of 50.7 g N m?2 per year could be linked to the anammox process, which is at intermediate levels for the nitrogen flux ranges of aerobic ammonium oxidation and denitrification reported in wetland soils. In addition, it is estimated that a total of 0.14 g CH4 m?2 per year could be oxidized via the n-damo process, while this rate is at the lower end of the aerobic methane oxidation rates reported in wetland soils. PMID:25261523

  20. Arsenic Behavior in Paddy Fields during the Cycle of Flooded and

    E-print Network

    , which produces the staple food in the region. Arsenic concentration is generally less than 10 mg the risk of As poisoning among people living in the area. Previous studies suggested that As concentration

  1. Analysis of Spatial Variability in a Korean Paddy Field Using Median Polish Detrending

    Technology Transfer Automated Retrieval System (TEKTRAN)

    There is developing interest in precision agriculture in Korea, despite the fact that typical fields are less than 1 ha in size. Describing within-field variability in typical Korean production settings is a fundamental first step toward determining the size of management zones and the inter-relatio...

  2. RADIOMETRIC ESTIMATION OF SOIL PROPERTIES USING MULTIPLE IMAGE SENSORS IN RICE PADDY AND DRYLAND FIELDS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An efficient way to detect spatial differences in crop and soil conditions at field scale is through image-based remote sensing. We report on three studies investigating the estimation of soil properties using bare-soil images. First, the ability of image data to estimate soil chemical property leve...

  3. The Effects of Rape Residue Mulching on Net Global Warming Potential and Greenhouse Gas Intensity from No-Tillage Paddy Fields

    PubMed Central

    Zhang, Zhi-Sheng; Cao, Cou-Gui; Guo, Li-Jin; Li, Cheng-Fang

    2014-01-01

    A field experiment was conducted to provide a complete greenhouse gas (GHG) accounting for global warming potential (GWP), net GWP, and greenhouse gas intensity (GHGI) from no-tillage (NT) paddy fields with different amounts of oilseed rape residue mulch (0, 3000, 4000, and 6000?kg dry matter (DM)?ha?1) during a rice-growing season after 3 years of oilseed rape-rice cultivation. Residue mulching treatments showed significantly more organic carbon (C) density for the 0–20?cm soil layer at harvesting than no residue treatment. During a rice-growing season, residue mulching treatments sequestered significantly more organic C from 687?kg?C?ha?1?season?1 to 1654?kg?C?ha?1?season?1 than no residue treatment. Residue mulching significantly increased emissions of CO2 and N2O but decreased CH4 emissions. Residue mulching treatments significantly increased GWP by 9–30% but significantly decreased net GWP by 33–71% and GHGI by 35–72% relative to no residue treatment. These results suggest that agricultural economic viability and GHG mitigation can be achieved simultaneously by residue mulching on NT paddy fields in central China. PMID:25140329

  4. The effects of rape residue mulching on net global warming potential and greenhouse gas intensity from no-tillage paddy fields.

    PubMed

    Zhang, Zhi-Sheng; Cao, Cou-Gui; Guo, Li-Jin; Li, Cheng-Fang

    2014-01-01

    A field experiment was conducted to provide a complete greenhouse gas (GHG) accounting for global warming potential (GWP), net GWP, and greenhouse gas intensity (GHGI) from no-tillage (NT) paddy fields with different amounts of oilseed rape residue mulch (0, 3000, 4000, and 6000 kg dry matter (DM) ha(-1)) during a rice-growing season after 3 years of oilseed rape-rice cultivation. Residue mulching treatments showed significantly more organic carbon (C) density for the 0-20 cm soil layer at harvesting than no residue treatment. During a rice-growing season, residue mulching treatments sequestered significantly more organic C from 687 kg C ha(-1) season(-1) to 1654 kg C ha(-1) season(-1) than no residue treatment. Residue mulching significantly increased emissions of CO2 and N2O but decreased CH4 emissions. Residue mulching treatments significantly increased GWP by 9-30% but significantly decreased net GWP by 33-71% and GHGI by 35-72% relative to no residue treatment. These results suggest that agricultural economic viability and GHG mitigation can be achieved simultaneously by residue mulching on NT paddy fields in central China. PMID:25140329

  5. Evaluation of allelopathic potential and quantification of momilactone A,B from rice hull extracts and assessment of inhibitory bioactivity on paddy field weeds.

    PubMed

    Chung, Ill Min; Kim, Jung Tae; Kim, Seung-Hyun

    2006-04-01

    Rice (Oryza sativa L.) hull extracts were used in a bioassay to evaluate the allelopathic potential of rice on the germination and growth of barnyard grass (Echinochloa crus-galli P. Beauv. var. oryzicola Ohwi), to quantify momilactone A and B levels in rice hull germplasm and to assess the inhibitory bioactivity of momilactone A and B as a potential natural source of herbicide for weed control in paddy fields. Four varieties of weeds including E. crus-galli P. Beauv. var. oryzicola Ohwi, Monochoria vaginalis var. plantaginea, Scirpus juncoides, and Eleocharis kuroguwai were tested in the paddy field. Of 99 rice varieties, the top five including Noindari exhibited inhibition effects greater than 50% in average inhibition of dry weight (AIDW). Noindari among them exerted the strongest effect (55.6%). The next five in the ranking exhibited inhibition effects of greater than 40%. Also, 46 varieties had inhibition effects between 20 and 40%, and 29 varieties had inhibition effects greater than 10%. Fourteen varieties had very low inhibitory effects (less than 10%), the lowest of which was Heunbe (4.7%). These varieties showed a mean inhibition of 19.8% for germination rate (GR), 9.9% for germination percentage (GP), 16.6% for leaf dry weight (LDW), 38.9% for straw dry weight (SDW), and 26.8% for root dry weight (RDW). Rice varieties were classified into six categories based on their total momilactones (TMs) (momilactone A + momilactone B). The highest level of momilactone A was found in the Baekna rice variety (34.7 microg g(-1)), and Baekgwangok contained the highest level of momilactone B (37.8 microg g(-1)). In allelopathic potential with genetic properties and morphological characteristics, the total inhibition rate (TIR) was 18.3% for Korean rice varieties, 19.0% for middle maturing varieties, 17.8% for colorless hull varieties, 18.3% for awn varieties, and 19.0% for colorless awn varieties. In addition, Korean varieties showed higher TMs (4.5 microg g(-1)) as compared with varieties that were late maturing (4.4 microg g(-1)), had colorless hulls (4.1 microg g(-1)), awns (4.7 microg g(-1)), and colorless awns (4.8 microg g(-1)). Momilactone A levels were generally higher than momilactone B levels. Total inhibition rates on barnyard grass correlated with average inhibitions of germination (AIG) (r2 = 0.62***), AIDW (r2 = 0.92***), and were affected by the inhibition rate of GP (r2 = 0.57***). Regions of origin for rice varieties correlated with the AIG (r2 = -0.23***), and maturing time showed a positive correlation with SDW (r2 = 0.15**) and RDW (r2 = 0.19**). Levels of momilactones were also correlated with the region of origin (r2 = -0.32***), maturing time (r2 = 0.13***), and awns (momilactone A, r2 = 0.23***; momilactone B, r2 = 0.14**), suggesting that rice varieties with awns, Korean varieties, and varieties with later maturing times contain higher levels of momilactone. Also, the investigation of the momilactone A and B bioactivity (0, 250, 500, 1000, 2000, and 4000 g a.i./ha) for weed control in paddy fields indicated that momilactones A and B exhibited no toxicity (0 in all concentrations) against rice plants, and the inhibitory bioactivity on weeds with momilactone A was higher than that of momilactone B. When compared with no momilactone control, the highest inhibitory effect (50%) on E. crus-galli P. Beauv. var. oryzicola Ohwi was shown on the 14th day after the application of momiactone A. The inhibitory effect increased with the concentration of the compound from 250 to 4000 g a.i./ha. Furthermore, momilactone A showed greater suppression than momliactone B toward toward E. crus-galli P. Beauv. var. oryzicola Ohwi, M. vaginalis var. plantaginea, S. juncoides, and E. kuroguwai. In broad weed species, momilactone A showed the highest inhibitory effect (90% in 4000 g a.i./ha) on S. juncoides, 14 days after the application as compared with no momilactone control. Further studies on allelopathic effects and momilactones from the germplasm of rice varieties using genetic properties and morphological characterist

  6. [Effects of combined applications of pig manure and chemical fertilizers on CH4 and N2O emissions and their global warming potentials in paddy fields with double-rice cropping].

    PubMed

    Wang, Cong; Shen, Jian-Lin; Zheng, Liang; Liu, Jie-Yun; Qin, Hong-Ling; Li, Yong; Wu, Jin-Shui

    2014-08-01

    A field experiment was carried out to study the effects of combined applications of pig manure and chemical fertilizers on CH4 and N2O emissions, which were measured using the static chamber/gas chromatography method, and their global warming potentials in typical paddy fields with double-rice cropping in Hunan province. The results showed that the combined applications of pig manure and chemical fertilizers did not change the seasonal patterns of CH4 and N2O emissions from paddy soils, but significantly changed the magnitudes of CH4 and N2O fluxes in rice growing seasons as compared with sole application of chemical fertilizers. During the two rice growing seasons, the cumulative CH4 emissions for the pig manure and chemical nitrogen (N) fertilizer each contributing to 50% of the total applied N (1/2N + PM) treatment were higher than those for the treatments of no N fertilizer (ON), half amount of chemical N fertilizer (1/2N) and 100% chemical N fertilizer (N) by 54.83%, 33.85% and 43.30%, respectively (P < 0.05), whilst the cumulative N2O emissions for the 1/2N + PM treatment were decreased by 67.50% compared with N treatment, but increased by 129.43% and 119.23% compared with ON and 1/2N treatments, respectively (P < 0.05). CH4 was the dominant contributor to the global warming potential (GWP) in both rice growing seasons, which contributed more than 99% to the integrated GWP of CH4 and N2O emissions for all the four treatments. Both GWP and yield-scaled GWP for the treatment of 1/2N + PM were significantly higher than the other three treatments. The yield-scaled GWP for the treatment of 1/2N + PM was higher than those for the N, 1/2N and ON treatments by 58.21%, 26.82% and 20. 63%, respectively. Therefore, combined applications of pig manure and chemical fertilizers in paddy fields would increase the GWP of CH4 and N2O emissions during rice growing seasons and this effect should be considered in regional greenhouse gases emissions inventory. PMID:25338388

  7. Effects of Tillage and Nitrogen Fertilizers on CH4 and CO2 Emissions and Soil Organic Carbon in Paddy Fields of Central China

    PubMed Central

    Zhi-Kui, Kou; Zhi-Sheng, Zhang; Jin-Ping, Wang; Ming-Li, Cai; Cou-Gui, Cao

    2012-01-01

    Quantifying carbon (C) sequestration in paddy soils is necessary to help better understand the effect of agricultural practices on the C cycle. The objective of the present study was to assess the effects of tillage practices [conventional tillage (CT) and no-tillage (NT)] and the application of nitrogen (N) fertilizer (0 and 210 kg N ha?1) on fluxes of CH4 and CO2, and soil organic C (SOC) sequestration during the 2009 and 2010 rice growing seasons in central China. Application of N fertilizer significantly increased CH4 emissions by 13%–66% and SOC by 21%–94% irrespective of soil sampling depths, but had no effect on CO2 emissions in either year. Tillage significantly affected CH4 and CO2 emissions, where NT significantly decreased CH4 emissions by 10%–36% but increased CO2 emissions by 22%–40% in both years. The effects of tillage on the SOC varied with the depth of soil sampling. NT significantly increased the SOC by 7%–48% in the 0–5 cm layer compared with CT. However, there was no significant difference in the SOC between NT and CT across the entire 0–20 cm layer. Hence, our results suggest that the potential of SOC sequestration in NT paddy fields may be overestimated in central China if only surface soil samples are considered. PMID:22574109

  8. Effects of Winter Cover Crops Straws Incorporation on CH4 and N2O Emission from Double-Cropping Paddy Fields in Southern China

    PubMed Central

    Tang, Hai-Ming; Xiao, Xiao-Ping; Tang, Wen-Guang; Wang, Ke; Sun, Ji-Min; Li, Wei-Yan; Yang, Guang-Li

    2014-01-01

    Residue management in cropping systems is believed to improve soil quality. However, the effects of residue management on methane (CH4) and nitrous oxide (N2O) emissions from paddy field in Southern China have not been well researched. The emissions of CH4 and N2O were investigated in double cropping rice (Oryza sativa L.) systems with straw returning of different winter cover crops by using the static chamber-gas chromatography technique. A randomized block experiment with three replications was established in 2004 in Hunan Province, China, including rice–rice–ryegrass (Lolium multiflorum L.) (Ry-R-R), rice–rice–Chinese milk vetch (Astragalus sinicus L.) (Mv-R-R) and rice–rice with winter fallow (Fa-R-R). The results showed that straw returning of winter crops significantly increased the CH4 emission during both rice growing seasons when compared with Fa-R-R. Ry-R-R plots had the largest CH4 emissions during the early rice growing season with 14.235 and 15.906 g m?2 in 2012 and 2013, respectively, when Ry-R-R plots had the largest CH4 emission during the later rice growing season with 35.673 and 38.606 g m?2 in 2012 and 2013, respectively. The Ry-R-R and Mv-R-R also had larger N2O emissions than Fa-R-R in both rice seasons. When compared to Fa-R-R, total N2O emissions in the early rice growing season were increased by 0.05 g m?2 in Ry-R-R and 0.063 g m?2 in Mv-R-R in 2012, and by 0.058 g m?2 in Ry-R-R and 0.068 g m?2 in Mv-R-R in 2013, respectively. Similar result were obtained in the late rice growing season, and the total N2O emissions were increased by 0.104 g m?2 in Ry-R-R and 0.073 g m?2 in Mv-R-R in 2012, and by 0.108 g m?2 in Ry-R-R and 0.076 g m?2 in Mv-R-R in 2013, respectively. The global warming potentials (GWPs) from paddy fields were ranked as Ry-R-R>Mv-R-R>Fa-R-R. As a result, straw returning of winter cover crops has significant effects on increase of CH4 and N2O emission from paddy field in double cropping rice system. PMID:25271923

  9. Effects of winter cover crops straws incorporation on CH4 and N2O emission from double-cropping paddy fields in southern China.

    PubMed

    Tang, Hai-Ming; Xiao, Xiao-Ping; Tang, Wen-Guang; Wang, Ke; Sun, Ji-Min; Li, Wei-Yan; Yang, Guang-Li

    2014-01-01

    Residue management in cropping systems is believed to improve soil quality. However, the effects of residue management on methane (CH4) and nitrous oxide (N2O) emissions from paddy field in Southern China have not been well researched. The emissions of CH4 and N2O were investigated in double cropping rice (Oryza sativa L.) systems with straw returning of different winter cover crops by using the static chamber-gas chromatography technique. A randomized block experiment with three replications was established in 2004 in Hunan Province, China, including rice-rice-ryegrass (Lolium multiflorum L.) (Ry-R-R), rice-rice-Chinese milk vetch (Astragalus sinicus L.) (Mv-R-R) and rice-rice with winter fallow (Fa-R-R). The results showed that straw returning of winter crops significantly increased the CH4 emission during both rice growing seasons when compared with Fa-R-R. Ry-R-R plots had the largest CH4 emissions during the early rice growing season with 14.235 and 15.906 g m(-2) in 2012 and 2013, respectively, when Ry-R-R plots had the largest CH4 emission during the later rice growing season with 35.673 and 38.606 g m(-2) in 2012 and 2013, respectively. The Ry-R-R and Mv-R-R also had larger N2O emissions than Fa-R-R in both rice seasons. When compared to Fa-R-R, total N2O emissions in the early rice growing season were increased by 0.05 g m(-2) in Ry-R-R and 0.063 g m(-2) in Mv-R-R in 2012, and by 0.058 g m(-2) in Ry-R-R and 0.068 g m(-2) in Mv-R-R in 2013, respectively. Similar result were obtained in the late rice growing season, and the total N2O emissions were increased by 0.104 g m(-2) in Ry-R-R and 0.073 g m(-2) in Mv-R-R in 2012, and by 0.108 g m(-2) in Ry-R-R and 0.076 g m(-2) in Mv-R-R in 2013, respectively. The global warming potentials (GWPs) from paddy fields were ranked as Ry-R-R>Mv-R-R>Fa-R-R. As a result, straw returning of winter cover crops has significant effects on increase of CH4 and N2O emission from paddy field in double cropping rice system. PMID:25271923

  10. Dissolved carbon and nitrogen dynamics in paddy fields under different water management practices and implications on green-house gas emissions

    NASA Astrophysics Data System (ADS)

    Miniotti, Eleonora; Said-Pullicino, Daniel; Bertora, Chiara; Pelissetti, Simone; Sacco, Dario; Grignani, Carlo; Lerda, Cristina; Romani, Marco; Celi, Luisella

    2013-04-01

    The alternation of oxidizing and reducing conditions in paddy soils results in considerable complexity in the biogeochemical cycling of elements and their interactions, influencing important soil processes. Water management practices may play an important role in controlling the loss of nutrients from rice paddies to surface and subsurface waters, as well as soil organic matter (SOM) stabilization and the emission of green-house gases (GHG) such as methane and nitrous oxide. The aim of this study was therefore to evaluate the interaction between changes in soil redox conditions and element cycling in temperate paddy soils as a function of different water management practices. The research was carried out within an experimental platform (1.2 ha) located at the Rice Research Center of Ente Nazionale Risi (Castello d'Agogna, PV, NW Italy) where three water management practices are being compared with two plots for each treatment. These included (i) rice cultivation under traditional submerged conditions (FLD); (ii) seeding under dry soil conditions and flooding delayed by about 40 days (DRY); (iii) seeding under dry soil conditions and rotational irrigation (IRR). Surface and subsurface (25, 50 and 75 cm) water samples were collected at regular intervals over the cropping season from V-notch weirs and porous ceramic suction cups installed in each plot, and subsequently analyzed for DOC, SUVA, Fe(II), ammonium and nitrate-N. Moreover, methane and nitrous oxide fluxes were measured in situ by the closed-chamber technique. DOC concentrations in soil solutions were generally higher in FLD and DRY treatments with respect to IRR throughout the cropping season. Higher DOC contents after field flooding in FLD and DRY treatments also corresponded with greater concentrations of reduced Fe, higher SUVA values, lower Eh values and higher pH values, suggesting that desorption of more aromatic, mineral-associated SOM could be responsible for the observed increase in DOC. These trends were not observed in the IRR treatment. The differences in DOC contents and in Eh trend between treatments could possibly explain the increasing trend in cumulative methane emissions in the order IRR<field study show that alternative water management practices may have important implications on nutrient availability, fertilizer efficiency, losses of DOC and nitrates to surface and subsurface waters, soil C stocks as well as GHG emissions. Suggesting alternative management practices therefore requires a holistic evaluation of the extent of all the processes involved. This research was partly supported by the Italian Ministry of Agriculture, Food and Forestry within the project POLORISO.

  11. The distribution of rare earth elements (REEs) in paddy soil and rice seeds from Ko?ani Field (eastern Macedonia) Razporeditev REE (redkih zemelj) v tleh riževih polj in rižu na obmo?ju Ko?anskega polja (vzhodna Makedonija)

    Microsoft Academic Search

    MaTej doleNec; GoraN Tasev; Tadej doleNec

    The concentrations of rare-earth elements (REEs) were analysed in paddy soil and rice grains collected from Ko?ani Field in eastern Macedonia. The results showed that the paddy soil originated from composite material mostly derived from igneous, volcanic, metamorphic and sedimentary rocks transported by the Bregalnica River and its tributaries and deposited in the Ko?ani depression. The elevated concentrations of heavy

  12. Mappping paddy rice agriculture in southern China using multi-temporal MODIS images

    NASA Astrophysics Data System (ADS)

    Xiao, X.; Boles, S.; Liu, J.; Zhuang, D.; Frolking, S.; Li, C.; Moore, B., III

    2004-05-01

    Information on spatial extent and seasonality of inundation and paddy rice fields are needed for water resource management, trace gases emission, and food security. In this study we reported an effort to use images from Moderate Resolution Imaging Spectroradiometer (MODIS) sensor onboard NASA EOS Terra satellite to map inundation and paddy rice fields in southern China. Paddy rice fields are characterized by a period of inundation and open canopy (a mixture of surface water and rice crops). We developed a temporal profile analysis procedure that uses time series data of improved vegetation indices to identify and map inundation and paddy rice fields. The MODIS-based algorithm uses both Enhanced Vegetation Index (EVI) and Land Surface Water Index (LSWI), and excludes those pixels that are covered by cloud and snow from the analysis. Permanent water body mask and digital elevation model were also used in the analysis. Using multi-temporal 8-day composite of MODIS images at 500-m spatial resolution in 2002, we generated a map of inundation and paddy rice fields in southern China. The MODIS-derived paddy rice map was compared with the other datasets of paddy rice agriculture, including the paddy rice map derived from analysis of Landsat ETM+ images in 1999/2000. The results from the comparison have indicated that the MODIS-based algorithm could potentially be applied at large spatial scale for mapping and monitoring of inundation and paddy rice agriculture.

  13. Mercury cycling in a flooded rice paddy

    NASA Astrophysics Data System (ADS)

    Rothenberg, Sarah E.; Feng, Xinbin

    2012-09-01

    In 2008 and 2009, mercury (Hg) cycling was investigated in a flooded rice paddy in the Wanshan Hg mining region of eastern Guizhou, China, in the rice-planted (2008 and 2009) and fallow (2009) sections of the same paddy. In the rice-planted section, pore water was more acidic and pore water methylmercury (MeHg) concentrations were higher compared to the fallow section. However, iron (Fe) and sulfur (S) cycling differed in 2008 and 2009, with higher sediment Fe concentrations in 2009, when pore water MeHg and sulfate concentrations were more strongly correlated in the rice-planted section. We explored whether elevated sediment Fe contributed to S cycling and hence, Hg(II)-methylation. Critical pH values for formation of FeS(s) were estimated. Based on pore water pH collected in both sections of the paddy, the fallow section was more often a sink for FeS(s), while FeS(s) did not form in the rice-planted section, although sulfide concentrations were low in both sections in both years (i.e.,<10 ?M). We hypothesized Fe(III) oxidized sulfide, and intermediate S species (e.g., polysulfides) were further oxidized to sulfate instead of forming FeS(s), thus prolonging sulfate reduction and promoting Hg(II)-methylation in the rice-planted section in 2009. Results suggested Fe(III) reduction increased electron acceptors for sulfate-reducing bacteria, which indirectly enhanced Hg(II)-methylation. Additionally, highest sediment MeHg concentrations were observed in the fallow section after the paddy was dried and re-wetted, indicating water-saving rice cultivation practices (e.g., alternating wetting and drying), may cause MeHg concentrations in paddy soil to spike, which should be further investigated.

  14. Ammonia volatilization from a paddy field following applications of urea: rice plants are both an absorber and an emitter for atmospheric ammonia.

    PubMed

    Hayashi, Kentaro; Nishimura, Seiichi; Yagi, Kazuyuki

    2008-02-15

    Ammonia (NH(3)) volatilization from a paddy field following applications of urea was measured. Two lysimeters of Gray Lowland soil with a pH (H(2)O) of 5.7 were used for the experiment. Urea was applied at a rate of 50 kg N ha(-1) by incorporation as the basal fertilization (BF) and at rates of 30 and 10 kg N ha(-1) by top-dressing as the first (SF1) and second (SF2) supplemental fertilizations, respectively. Two wind tunnels per lysimeter were installed just after BF; one was transplanted with rice plants (PR plot), and the other was without rice plants (NR plot). Weak volatilization was observed at the PR plots after BF. By contrast, strong volatilization was observed at the PR plots after SF1 with a maximum flux of 150 g N ha(-1) h(-1); however, almost no volatilization was observed after SF2. The NH(3) volatilization loss accounted for 2.1%, 20.9%, 0.5%, and 8.2% of the applied urea at each application, BF, SF1, SF2, and the total application, respectively, for which only the net fluxes as volatilization were accumulated. The NH(3) volatilization fluxes from the paddy water surface (F(vol)) at the NR plots were estimated using a film model for its verification. After confirmation of good correlation, the film model was applied to estimate F(vol) at the PR plots. The NH(3) exchange fluxes by rice plants (F(ric)) were obtained by subtracting F(vol) from the observed net NH(3) flux. The derived F(ric) showed that the rice plants emitted NH(3) remarkably just after SF1 when a relatively high rate of urea was applied, although they absorbed atmospheric NH(3) in the other periods. In conclusion, rice plants are essentially an absorber of atmospheric NH(3); however, they turn into an emitter of NH(3) under excess nutrition of ammoniacal nitrogen. PMID:18054067

  15. A Rice Gene for Microbial Symbiosis, Oryza sativa CCaMK, Reduces CH4 Flux in a Paddy Field with Low Nitrogen Input

    PubMed Central

    Bao, Zhihua; Watanabe, Aya; Sasaki, Kazuhiro; Okubo, Takashi; Tokida, Takeshi; Liu, Dongyan; Ikeda, Seishi; Imaizumi-Anraku, Haruko; Asakawa, Susumu; Sato, Tadashi; Mitsui, Hisayuki

    2014-01-01

    Plants have mutualistic symbiotic relationships with rhizobia and fungi by the common symbiosis pathway, of which Ca2+/calmodulin-dependent protein kinase (encoded by CCaMK) is a central component. Although Oryza sativa CCaMK (OsCCaMK) is required for fungal accommodation in rice roots, little is known about the role of OsCCaMK in rice symbiosis with bacteria. Here, we report the effect of a Tos17-induced OsCCaMK mutant (NE1115) on CH4 flux in low-nitrogen (LN) and standard-nitrogen (SN) paddy fields compared with wild-type (WT) Nipponbare. The growth of NE1115 was significantly decreased compared with that of the WT, especially in the LN field. The CH4 flux of NE1115 in the LN field was significantly greater (156 to 407% in 2011 and 170 to 816% in 2012) than that of the WT, although no difference was observed in the SN field. The copy number of pmoA (encodes methane monooxygenase in methanotrophs) was significantly higher in the roots and rhizosphere soil of the WT than in those of NE1115. However, the mcrA (encodes methyl coenzyme M reductase in methanogens) copy number did not differ between the WT and NE1115. These results were supported by a 13C-labeled CH4-feeding experiment. In addition, the natural abundance of 15N in WT shoots (3.05‰) was significantly lower than in NE1115 shoots (3.45‰), suggesting greater N2 fixation in the WT because of dilution with atmospheric N2 (0.00‰). Thus, CH4 oxidation and N2 fixation were simultaneously activated in the root zone of WT rice in the LN field and both processes are likely controlled by OsCCaMK. PMID:24441161

  16. Influence of nitrogen loading and plant nitrogen assimilation on nitrogen leaching and N?O emission in forage rice paddy fields fertilized with liquid cattle waste.

    PubMed

    Riya, Shohei; Zhou, Sheng; Kobara, Yuso; Sagehashi, Masaki; Terada, Akihiko; Hosomi, Masaaki

    2015-04-01

    Livestock wastewater disposal onto rice paddy fields is a cost- and labor-effective way to treat wastewater and cultivate rice crops. We evaluated the influence of nitrogen loading rates on nitrogen assimilation by rice plants and on nitrogen losses (leaching and N2O emission) in forage rice fields receiving liquid cattle waste (LCW). Four forage rice fields were subjected to nitrogen loads of 107, 258, 522, and 786 kg N ha(-1) (N100, N250, N500, and N750, respectively) using basal fertilizer (chemical fertilizer) (50 kg N ha(-1)) and three LCW topdressings (each 57-284 kg N ha(-1)). Nitrogen assimilated by rice plants increased over time. However, after the third topdressing, the nitrogen content of the biomass did not increase in any treatment. Harvested aboveground biomass contained 93, 60, 33, and 31 % of applied nitrogen in N100, N250, N500, and N750, respectively. The NH4 (+) concentration in the pore water at a depth of 20 cm was less than 1 mg N L(-1) in N100, N250, and N500 throughout the cultivation period, while the NH4 (+) concentration in N750 increased to 3 mg N L(-1) after the third topdressing. Cumulative N2O emissions ranged from -0.042 to 2.39 kg N ha(-1); the highest value was observed in N750, followed by N500. In N750, N2O emitted during the final drainage accounted for 80 % of cumulative N2O emissions. This study suggested that 100-258 kg N ha(-1) is a recommended nitrogen loading rate for nitrogen recovery by rice plants without negative environmental impacts such as groundwater pollution and N2O emission. PMID:25388561

  17. Sources Of Atmospheric Methane: Measurements in Rice Paddies and a Discussion

    Microsoft Academic Search

    Ralph J. Cicerone; James D. Shetter

    1981-01-01

    We have made field measurements of methane fluxes from rice paddies, fresh water lakes, and saltwater marshes to infer estimates of the size of these sources of atmospheric methane. The rice-paddy measurements, the first of their kind, show that the principal means of methane escape is through the plants themselves as opposed to transport across the water-air interface via bubbles

  18. Models for Estimating the Physical Properties of Paddy Soil Using Visible and Near Infrared Reflectance Spectroscopy

    NASA Astrophysics Data System (ADS)

    Gholizadeh, A.; Amin, M. S. M.; Bor?vka, L.; Saberioon, M. M.

    2014-07-01

    A fast and convenient soil analytical technique is needed for soil quality assessment and precision soil management. The main objective of this study was to evaluate the ability of visible (Vis) and near-infrared (NIR) refl ectance spectroscopy to predict paddy soil properties in a typical Malaysian paddy fi eld. To assess the utility of spectroscopy for soil physical characteristics (bulk density, moisture content, clay, silt and sand) prediction, 118 soil samples were used for laboratory analysis and optical measurement in the Vis-NIR region using an analytical spectral device (ASD) FieldSpec spectroradiometer (350-2500 nm). The Savitzky-Golay algorithm and stepwise multiple linear regression (SMLR) were then applied to preprocess, model, and predict the properties on the basis of their spectral refl ectance within the Vis-NIR range. One-third of the samples (40 samples) were withheld for validation purposes. The study revealed that Vis and NIR spectroscopy calibration models for all the measured soil physical characteristics provided a good fi t (R2 > 0.78); hence Vis and NIR (specifi cally NIR refl ectance) can be considered to be a reliable tool to assess soil physical properties of Malaysian paddy fi elds. The results of this study could contribute signifi cantly to developing site-specifi c management.

  19. Effects of vegetation on the emission of methane from submerged paddy soil

    Microsoft Academic Search

    A. Holzapfel-Pschorn; R. Conrad; W. Seiler

    1986-01-01

    Summary  Methane emission rates from rice-vegetated paddy fields followed a seasonal pattern different to that of weed-covered or unvegetated\\u000a fields. Presence of rice plants stimulated the emission of CH4 both in the laboratory and in the field. In unvegetated paddy fields CH4 was emitted almost exclusively by ebullition. By contrast, in rice-vegetated fields more than 90% of the CH4 emission was

  20. Understanding transitions in rice paddy extent and management in the Vietnamese Mekong River Delta using Landsat data

    NASA Astrophysics Data System (ADS)

    Kontgis, C. P.; Schneider, A.; Ozdogan, M.

    2014-12-01

    Rice is a staple food crop for the majority of the world's population, yet paddy fields are threatened by urban expansion, climate change, and degraded agricultural land. For example, Vietnam, the second largest exporter of rice globally, grows most of its rice in the Mekong River Delta at the country's southern tip, yet this low-lying and heavily populated area is proving susceptible to land cover changes in the area. To properly monitor and manage the rice crops in this region, remote sensing of satellite imagery has been particularly useful; however, most efforts to map regional paddy area utilize coarse resolution MODIS or AVHRR data since the high temporal resolution of these datasets can overcome missing data issues due to clouds. Here, we aim to map the landscape using finer-scale Landsat data by generating dense time stacks over multiple growing seasons. First, we exploit dense stacks of data for circa 2000 and circa 2010 to classify rice using vegetation trajectories (EVI and NDWI). Next, these pixel-based rice maps are combined with image-based segments (generated using the open-source Mean-shift region-growing segmentation algorithm, which has been proven to optimally identify clusters within an image) to generate a polygon-based rice map using the majority rule. Results show that this method can map rice paddy agriculture with over 90% accuracy at a much finer spatial resolution than has ever been produced. Finally, this work also aims to differentiate between double- and triple-cropped rice paddies in the region, again by exploiting EVI trajectories, in an effort to determine how management practices have changed over the decade-long study period. Increasing the number of annual cropping cycles over the area can lead to soil degradation and lower yields per harvest, albeit larger total annual yields, so monitoring these practices is vital to understanding the sustainability of these agricultural systems.

  1. Ancient paddy soils from the Neolithic age in China’s Yangtze River Delta

    Microsoft Academic Search

    Z. H. Cao; J. L. Ding; Z. Y. Hu; H. Knicker; I. Kögel-Knabner; L. Z. Yang; R. Yin; X. G. Lin; Y. H. Dong

    2006-01-01

    Identifying prehistoric irrigated rice fields and characterizing the beginning of paddy soil development are important for a better understanding of human development and agricultural history. In 2003, paddy soils and irrigated rice fields buried at a depth of 100–130 cm were excavated at Chuo-dun-shan in the Yangtze River Delta, close to Suzhou, China. The fields of sizes between 1.4 and 16 m2

  2. Development and test of SWAT for modeling hydrological processes in irrigation districts with paddy rice

    NASA Astrophysics Data System (ADS)

    Xie, Xianhong; Cui, Yuanlai

    2011-01-01

    SummaryThe water movement in irrigation districts, especially for paddy rice cultivation, is characterized by complicated factors. Soil and Water Assessment Tool (SWAT) is a popular tool for understanding the hydro-agronomic processes. However, it fails to simulate the hydrological processes and crop yields in paddy rice areas. In this study, we develop the SWAT model by incorporating new processes for irrigation and drainage. The evapotranspiration process in paddy fields is simulated on the basis of water storage conditions, and a controlling irrigation scheme is introduced to manage the irrigation and drainage operations. The irrigation function of local water storages, such as ponds and reservoirs, is extended for these storages in order to provide water in a timely manner to paddy fields. Moreover, an agronomic model is incorporated to estimate crop yields when available data sets are not satisfactory. The model is tested in Zhanghe Irrigation District, China. The simulated runoff matches well to the measurements and the results indicate the developed model is preferable to the original edition of SWAT. The estimate of the paddy rice yield is acceptable and the dynamics of water balance components approximately characterize the state of water movements in paddy fields. Therefore, the developed framework for SWAT is practical and capable of representing the hydrological processes in this irrigation district. Further work is still needed to more broadly test the model in areas with paddy rice cultivation.

  3. Paddy soil cracks: characteristics and their impact on preferential flow

    NASA Astrophysics Data System (ADS)

    Zhang, Zhongbin; Peng, Xinhua

    2015-04-01

    Paddy soils with harrowing and puddling easily crack under alternate flooding and drying cycles (AFD). These cracks in paddy field may become pathways of preferential flow, improving water infiltration and increasing the pollution risk of groundwater. The objectives of this study were to investigate the 2D and 3D characteristics of soil cracks in paddy fields; and to determine their impacts on preferential flow. Two paddy fields, one cultivated for 20 years (YPF) and the other cultivated for more than 100 years (OPF), were subjected to either alternate flooding and drying (AFD) or continuous flooding (CF) during rice growing season. After the harvest of late rice crop, soil surface cracks were recorded using digital camera; and 3D structure of soil cracks was scanned by computed tomography (CT). The characteristics of 2D and 3D soil cracks were quantified with the aid of image analysis. The influence of soil cracks on preferential flow was characterized by tension infiltrometer, dye tracer and ion breakthrough curve. Our main results in this study were summed up as follows: under AFD condition, for the 2D soil cracks, the YPF presented 10 fold more cracks in quantity but these cracks were finer and more complicated as compared to those generated in the OPF. The results of CT scanning showed that the presence of soil cracks under the AFD increased average macropore length but decreased the number of macropores significantly, and it also changed macropore size distribution and macropore area density distribution with soil depth. The 3D structures of soil cracks were complicated but can be quantified using CT. The depth of soil cracks in young paddy field (7.58 cm) was smaller than that in old paddy field (9.34 cm), but soil cracks in both fields did not reach the plough pan (about 15 cm). Soil cracks significantly increased soil hydraulic conductivity. They serviced as pathways for preferential flow only in plow layer, as evidenced by a large dyed area above plough pan but a small area below it. Both the shape of BTCs and fitting parameters demonstrated that soil cracks did not increase preferential flow below plow pan because they did not perforate through the dense plow pan. This study demonstrates that soil cracks in paddy fields significantly affect macropore structure but their impact on preferential flow may be poor when they do not penetrate through the plow pan.

  4. Characteristics of water reuse and its effects on paddy irrigation system water balance and the riceland ecosystem

    Microsoft Academic Search

    Giveson Zulu; Masaru Toyota; Shin-ichi Misawa

    1996-01-01

    Rapid industrial development in the rice-growing regions has increased competition for the scarce water resources. Water reuse (surface and subsurface agriculture drainage water, storm runoff, sewerage effluent and industrial wastewater recycling) is in widespread use as a method of supplementing the paddy water supply, therefore, there is a need to clarify its effects on the paddy system water balance and

  5. Solubility and Leaching Risks of Organic Carbon in Paddy Soils as Affected by Irrigation Managements

    PubMed Central

    Yang, Shihong; Wei, Qi; Gao, Xiaoli

    2013-01-01

    Influence of nonflooding controlled irrigation (NFI) on solubility and leaching risk of soil organic carbon (SOC) were investigated. Compared with flooding irrigation (FI) paddies, soil water extractable organic carbon (WEOC) and dissolved organic carbon (DOC) in NFI paddies increased in surface soil but decreased in deep soil. The DOC leaching loss in NFI field was 63.3?kg C ha?1, reduced by 46.4% than in the FI fields. It indicated that multi-wet-dry cycles in NFI paddies enhanced the decomposition of SOC in surface soils, and less carbon moved downward to deep soils due to less percolation. That also led to lower SOC in surface soils in NFI paddies than in FI paddies, which implied that more carbon was released into the atmosphere from the surface soil in NFI paddies. Change of solubility of SOC in NFI paddies might lead to potential change in soil fertility and sustainability, greenhouse gas emission, and bioavailability of trace metals or organic pollutants. PMID:23935423

  6. Methane emission from rice paddies

    Microsoft Academic Search

    W. Seiler; A. Holzapfel-Pschorn; R. Conrad; D. Scharffe

    1983-01-01

    Methane release rates from rice paddies have been measured in Andalusia, Spain, during almost a complete vegetation period in 1982 using the static box system. The release rates ranged between 2 and 14 mg\\/m2\\/h and exhibited a strong seasonal variation with low values during the tillering stage and shortly before harvest, while maximum values were observed at the end of

  7. Annual Changes of Paddy Rice Planting Areas in Northeastern Asia from MODIS images in 2000-2014

    NASA Astrophysics Data System (ADS)

    Xiao, X.; Zhang, G.; Dong, J.; Menarguez, M. A.; Kou, W.; Jin, C.; Qin, Y.; Zhou, Y.; Wang, J.; Moore, B., III

    2014-12-01

    Knowledge of the area and spatial distribution of paddy rice is important for assessment of food security, management of water resources, estimation of greenhouse gas (methane) emissions, and understanding avian influenza virus transmission. Over the past two decades, paddy rice cultivation has expanded northward in temperate and cold temperate zones, particularly in Northeastern China. There is a need to quantify and map changes in paddy rice planting areas in Northeastern Asia (Japan, North and South Korea, and northeast China) at annual interval. We developed a pixel- and phenology-based image analysis system, MODIS-RICE, to map the paddy rice in Northeastern Asia by using multi-temporal MODIS thermal and surface reflectance imagery. Paddy rice fields during the flooding and transplanting phases have unique physical and spectral characteristics, which make it possible for the development of an automated and robust algorithm to track flooding and transplanting phases of paddy rice fields over time. In this presentation, we will show the MODIS-based annual maps of paddy rice planting area in the Northeastern Asia from 2000-2014 (500-m spatial resolution). Accuracy assessments using high-resolution images show that the resultant paddy rice map of Northeastern Asia had a comparable accuracy to the existing products, including 2010 Landsat-based National Land Cover Dataset (NLCD) of China, the 2010 RapidEye-based paddy rice map in North Korea, and the 2010 AVNIR-2-based National Land Cover Dataset in Japan in terms of both area and spatial pattern of paddy rice. This study has demonstrated that our novel MODIS-Rice system, which use both thermal and optical MODIS data over a year, are simple and robust tools to identify and map paddy rice fields in temperate and cold temperate zones.

  8. Enzyme dynamics in paddy soils of the rice district (NE Italy) under different cropping patterns

    NASA Astrophysics Data System (ADS)

    Bini, Claudio; Nadimi-Goki, Mandana; Kato, Yoichi; Fornasier, Flavio; Wahsha, Mohammad; Spiandorello, Massimo

    2014-05-01

    The recent widespread interest on soil enzymes is due to the need to develop sensitive indicators of soil quality that reflect the effects of land management on soil and assist land managers in promoting long-term sustainability of terrestrial ecosystems. The activities of six important enzymes involved in C, N, P, and S cycling were investigated in a paddy soil from the Veneto region, Italy, in four different rotation systems (rice-rice-rice: R-R-R; soya-rice-rice: S-R-R; fallow-rice: F-R; pea-soya-rice: P-S-R) with three replications in April (after field preparation, field moist condition), June (after seedling, waterlogged soil condition), August (after tillering stage of rice, waterlogged soil condition) and October (after rice harvesting, drained soil condition) over the 2012 growing season. Our results demonstrated that enzyme activities varied with rotation systems and growth stages in paddy soil. Compared with field moist soil, drained soil condition resulted in a significant increase (P < 0.05) of ?-glucosidase, arylsulfatase, alkaline and acid phosphatases, leucine aminopeptidase (except of fallow-rice), and chitinase activities in all rotations, while compared with drained soil, early waterlogging (in month of June) significantly decreased (P moist soil> late waterlogged>early waterlogged. There was an inhibitory effect of waterlogging (except P-S-R rotation) for both alkaline and acid phosphatases due to high pH and redox conditions. However, the response of enzymes to waterlogging differed with the chemical species and the cropping pattern. The best rotation system for chitinase, leucine aminopeptidase and ?-glucosidase activity (C and N cycles) proved R-R-R, while for arylsulfatase, alkaline and acid phosphatases (P and S cycles) it was the S-R-R. Key Words: enzyme activity, paddy soil, Crop Rotation System, Italy __ Corresponding Author: Mandana Nadimi-Goki, Tel.: +39 3891356251 E-mail address: mandy.nadimi@gmail.com

  9. Uncultivated Methylocystis Species in Paddy Soil Include Facultative Methanotrophs that Utilize Acetate.

    PubMed

    Leng, Lingqin; Chang, Jiali; Geng, Kan; Lu, Yahai; Ma, Ke

    2015-07-01

    Methanotrophs are crucial in regulating methane emission from rice field systems. Type II methanotrophs in particular are often observed in high abundance in paddy soil. Some cultivated species of Methylocystis are able to grow on acetate in the absence of methane. We hypothesize that the dominant type II methanotrophs in paddy soil might facultatively utilize acetate for growth, which we evaluate in the present study. The measurement of methane oxidation rates showed that the methanotrophic activity in paddy soil was inhibited by the addition of acetate compared to the continuous supplementation of methane, but the paddy soil maintained the methane oxidation capacity and recovered following methane supplementation. Terminal restriction fragment length polymorphism analysis (T-RFLP) combined with cloning and sequencing of pmoA genes showed that Methylocystis was enriched after incubation with added acetate, while the type I methanotrophs Methylocaldum/Methylococcus and Methylobacter were enriched by methane supplementation. A comparison of pmoA sequences obtained in this study with those in the public database indicated that they were globally widespread in paddy soils or in associated with rice roots. Furthermore, we performed stable isotope probing (SIP) of pmoA messenger RNA (mRNA) to investigate the assimilation of (13)C-acetate by paddy soil methanotrophs. RNA-SIP revealed that Methylocystis-related methanotrophs which shared the same genotype of the above enriched species were significantly labelled. It indicates that these methanotrophs actively assimilated the labelled acetate in paddy soil. Altogether, these results suggested that uncultivated Methylocystis species are facultative methanotrophs utilizing acetate as a secondary carbon source in paddy soil. PMID:25475784

  10. Isolation and characterization of methane utilizing bacteria from wetland paddy ecosystem.

    PubMed

    Jhala, Y K; Vyas, R V; Shelat, H N; Patel, H K; Patel, H K; Patel, K T

    2014-06-01

    Methylotrophic bacteria which are known to utilize C1 compounds including methane. Research during past few decades increased the interest in finding out novel genera of methane degrading bacteria to efficiently utilize methane to decrease global warming effect. Moreover, evaluation of certain known plant growth promoting strains for their methane degrading potential may open up a new direction for multiple utility of such cultures. In this study, efficient methylotrophic cultures were isolated from wetland paddy fields of Gujarat. From the overall morphological, biochemical and molecular characterization studies, the isolates were identified and designated as Bacillus aerius AAU M 8; Rhizobium sp. AAU M 10; B. subtilis AAU M 14; Paenibacillus illinoisensis AAU M 17 and B. megaterium AAU M 29. Gene specific PCR analysis of the isolates, P. illinoisensis, B. aerius, Rhizobium sp. and B. subtilis showed presence of pmoA gene encoding ? subunit particulate methane monooxygenase cluster. B. megaterium, P. illinoisensis, Rhizobium sp. and Methylobacterium extrorquens showed presence of mmoX gene encoding ? subunit of the hydroxylase component of the soluble methane monooxygenase cluster. P. illinoisensis and Rhizobium sp. showed presence mxaF gene encoding ? subunit region of methanol dehydrogenase gene cluster showing that both isolates are efficient utilizers of methane. To the best of our knowledge, this is the first time report showing presence of methane degradation enzymes and genes within the known PGPB group of organisms from wet land paddy agro-ecosystem, which is considered as one of the leading methane producer. PMID:24469547

  11. The specific role of fungal community structure on soil aggregation and carbon sequestration: results from long-term field study in a paddy soil

    NASA Astrophysics Data System (ADS)

    Murugan, Rajasekaran; Kumar, Sanjay

    2015-04-01

    Soil aggregate stability is a crucial soil property that affects soil biota, biogeochemical processes and C sequestration. The relationship between soil aggregate stability and soil C cycling is well known but the influence of specific fungal community structure on this relationship is largely unknown in paddy soils. The aim of the present study was to evaluate the long-term fertilisation (mineral fertiliser-MIN; farmyard manure-FYM; groundnut oil cake-GOC) effects on soil fungal community shifts associated with soil aggregates under rice-monoculture (RRR) and rice-legume-rice (RLR) systems. Fungal and bacterial communities were characterized using phospholipid fatty acids, and glucosamine and muramic acid were used as biomarkers for fungal and bacterial residues, respectively. Microbial biomass C and N, fungal biomass and residues were significantly higher in the organic fertiliser treatments than in the MIN treatment, for all aggregate sizes under both crop rotation systems. In general, fungal/bacterial biomass ratio and fungal residue C/bacterial residue C ratio were significantly higher in macroaggregate fractions (> 2000 and 250-2000 ?m) than in microaggregate fractions (53-250 and <53 ?m). In both crop rotation systems, the long-term application of FYM and GOC led to increased accumulation of saprotrophic fungi (SF) in aggregate fractions > 2000 ?m. In contrast, we found that arbuscular mycorrhizal fungi (AMF) was surprisingly higher in aggregate fractions > 2000 ?m than in aggregate fraction 250-2000 ?m under MIN treatment. The RLR system showed significantly higher AMF biomass and fungal residue C/ bacterial residue C ratio in both macroaggregate fractions compared to the RRR system. The strong relationships between SF, AMF and water stable aggregates shows the specific contribution of fungi community on soil aggregate stability. Our results highlight the fact that changes within fungal community structure play an important role in shaping the soil aggregate stability and C sequestration in tropical agricultural ecosystems.

  12. Chromium stress in paddy: (i) nutrient status of paddy under chromium stress; (ii) phytoremediation of chromium by aquatic and terrestrial weeds.

    PubMed

    Sundaramoorthy, Perumal; Chidambaram, Alagappan; Ganesh, Kaliyaperumal Sankar; Unnikannan, Pachikkaran; Baskaran, Logalakshmanan

    2010-08-01

    A field experiment was conducted with paddy (Oryza sativa L.) irrigated with different concentrations (Control, 2.5, 5, 10, 25, 50, 75, 100 and 200 mg/l) of chromium. The changes in growth, yield, nutrient content and chromium accumulation in the paddy are reported. The growth of shoot, root, total leaf area, fresh weight, dry weight and yield of the paddy gradually decreased with increasing Cr concentration. Similarly, the uptake of macronutrients (N, P, K) and micronutrients (Mn, Cu, Zn, Fe) were also gradually decreased. However, the chromium accumulation gradually increased with the increasing concentrations of chromium. Among the aquatic plants tested, Eicchornia crassipes showed better performance in accumulating higher amount of chromium. Similarly, certain grasses and weeds such as Cyperus rotundus, Cyperus kylinga, Marselia quadrifolia and Ludwigia parvifloria were used for the phytoremediation of chromium polluted soil. Among them, Cyperus rotundus accumulated higher amount of chromium than the other plants tested. PMID:20688280

  13. Detection of fumonisin producing Fusarium verticillioides in paddy (Oryza sativa L.) using polymerase chain reaction (PCR)

    PubMed Central

    Maheshwar, P.K.; Moharram, S. Ahmed; Janardhana, G.R.

    2009-01-01

    The study reports the occurrence of fumonisin producing Fusarium verticillioides in 90 samples of stored paddy (Oryza sativa L.) collected from different geographical regions of Karnataka, India. Fumonisin producing F. verticillioides was identified based on micromorphological characteristics and PCR using two sets of primers. One set of primers was F. verticillioides species specific, which selectively amplified the intergenic space region of rDNA. The other set of primers was specific to fumonisin producing F. verticillioides. Eight paddy samples were positive for F. verticillioides. Eleven isolates obtained from these samples were capable of producing fumonisin. PMID:24031332

  14. Characterizing Spatiotemporal Dynamics of Methane Emissions from Rice Paddies in Northeast China from 1990 to 2010

    PubMed Central

    Zhang, Yuan; Su, Shiliang; Zhang, Feng; Shi, Runhe; Gao, Wei

    2012-01-01

    Background Rice paddies have been identified as major methane (CH4) source induced by human activities. As a major rice production region in Northern China, the rice paddies in the Three-Rivers Plain (TRP) have experienced large changes in spatial distribution over the recent 20 years (from 1990 to 2010). Consequently, accurate estimation and characterization of spatiotemporal patterns of CH4 emissions from rice paddies has become an pressing issue for assessing the environmental impacts of agroecosystems, and further making GHG mitigation strategies at regional or global levels. Methodology/Principal Findings Integrating remote sensing mapping with a process-based biogeochemistry model, Denitrification and Decomposition (DNDC), was utilized to quantify the regional CH4 emissions from the entire rice paddies in study region. Based on site validation and sensitivity tests, geographic information system (GIS) databases with the spatially differentiated input information were constructed to drive DNDC upscaling for its regional simulations. Results showed that (1) The large change in total methane emission that occurred in 2000 and 2010 compared to 1990 is distributed to the explosive growth in amounts of rice planted; (2) the spatial variations in CH4 fluxes in this study are mainly attributed to the most sensitive factor soil properties, i.e., soil clay fraction and soil organic carbon (SOC) content, and (3) the warming climate could enhance CH4 emission in the cool paddies. Conclusions/Significance The study concluded that the introduction of remote sensing analysis into the DNDC upscaling has a great capability in timely quantifying the methane emissions from cool paddies with fast land use and cover changes. And also, it confirmed that the northern wetland agroecosystems made great contributions to global greenhouse gas inventory. PMID:22235268

  15. [Microbial metabolism in typical flooded paddy soils ].

    PubMed

    Cai, Yuanfeng; Wu, Yucheng; Wang, Shuwei; Yan, Xiaoyuan; Zhu, Yongguan; Jia, Zhongjun

    2014-09-01

    [OBJECTIVE] The object of this study is to reveal the composition of active microorganism and their metabolic activities in flooded paddy soils with long-term fertilization ( Mineral nitrogen, phosphorus, and potassium, NPK) and without fertilizer (Control check, CK) by environmental transcriptomics. [METHODS] Flooded soil microcosms were incubated in the laboratory for two weeks, then total RNA were extracted from the soil for transcriptome sequencing. Resulting fastq files were uploaded to the Metagenomics Analysis Server (MG-RAST) for taxonomic analysis, gene annotation and function classification. [RESULTS] Transcripts from diverse active microorganism, including bacteria ( > 95% ) , archaea, eukaryotes and viruses, were detected in both flooded paddy soils of CK and NPK treatments. Most of the transcripts (active genes) of bacteria and archaea were derived from Proteobacteria (more than 50% of total bacterial transcripts) and Thaumarchaaeota (about 70% of total archaeal transcripts ) respectively in both treatments. Transcriptional activity of Acidobacteria in NPK treatment paddy soil was significantly higher than that in CK treatment paddy soil. As for other phyla of bacteria and archaea, there were no significant differences of transcriptional activity of them between CK and NPK treatment paddy soils. The highest expressed gene in both CK and NPK treatment paddy soils is ABC transporter encoding gene which related to the transmembrane transport of substances. Based on gene function category of COG (Clusters of Orthologous Genes), Subsystem and KEGG (Kyoto Encyclopedia of Genes and Genomes) database, we found that the main metabolic activities of microorganisms in both CK and NPK treatment paddy soils were related to energy production and conversion, carbohydrate metabolism, protein metabolism and amino acid metabolism, and the dominant KEGG pathways were oxidative phosphorylation and aminoacyl-tRNA biosynthesis. [ CONCLUSION] Composition of active microorganism in CK and NPK treatment paddy soils was generally similar, except Acidobacteria whose transcriptional activity was significantly different between these two treatment paddy soils. It was also very similar between CK and NPK treatment paddy soils considering the metabolic activities of microorganisms in them, for dominant metabolic processes in these two soils were both related to energy obtaining and protein metabolism. So, dominant metabolic activities of microorganism in flooded paddy soils used in this study were not altered significantly under long - term inorganic fertilization. PMID:25522592

  16. The estimation of rice paddy yield with GRAMI crop model and Geostationary Ocean Color Imager (GOCI) image over South Korea

    NASA Astrophysics Data System (ADS)

    Yeom, J. M.; Kim, H. O.

    2014-12-01

    In this study, we estimated the rice paddy yield with moderate geostationary satellite based vegetation products and GRAMI model over South Korea. Rice is the most popular staple food for Asian people. In addition, the effects of climate change are getting stronger especially in Asian region, where the most of rice are cultivated. Therefore, accurate and timely prediction of rice yield is one of the most important to accomplish food security and to prepare natural disasters such as crop defoliation, drought, and pest infestation. In the present study, GOCI, which is world first Geostationary Ocean Color Image, was used for estimating temporal vegetation indices of the rice paddy by adopting atmospheric correction BRDF modeling. For the atmospheric correction with LUT method based on Second Simulation of the Satellite Signal in the Solar Spectrum (6S), MODIS atmospheric products such as MOD04, MOD05, MOD07 from NASA's Earth Observing System Data and Information System (EOSDIS) were used. In order to correct the surface anisotropy effect, Ross-Thick Li-Sparse Reciprocal (RTLSR) BRDF model was performed at daily basis with 16day composite period. The estimated multi-temporal vegetation images was used for crop classification by using high resolution satellite images such as Rapideye, KOMPSAT-2 and KOMPSAT-3 to extract the proportional rice paddy area in corresponding a pixel of GOCI. In the case of GRAMI crop model, initial conditions are determined by performing every 2 weeks field works at Chonnam National University, Gwangju, Korea. The corrected GOCI vegetation products were incorporated with GRAMI model to predict rice yield estimation. The predicted rice yield was compared with field measurement of rice yield.

  17. Impact of Rice Paddy Areas Decrease on Local Climate over Taiwan

    NASA Astrophysics Data System (ADS)

    Lo, M. H.; Wen, W. H.; Chen, C. C.

    2014-12-01

    Agricultural irrigation practice is one of the important anthropogenic processes in the land surface modeling. Irrigation can decrease local surface temperature with alternating surface energy partitioning. Rice paddy is the major food crop in Asian monsoon region and rice is grown under flooded conditions during the growing season; hence, the rice paddy can be considered as an open water body, which has more impacts on the surface energy budget than other cropland does. In this study, we explore how the rice paddy area changes affect Taiwan's regional climate from both observational data and numerical modeling exercise. The Weather Research and Forecasting (WRF) model is utilized to explore impacts of rice paddy area changes on the regional climate, and energy and water budget changes. In addition, temperature datasets from six automatic weather stations in the northern Taiwan and two stations in the southern Taiwan are analyzed in this study to explore how the Daily Temperature Range (DTR) changes with the decreased rice paddy areas. Previous studies show that due to the urban heat island effect, aerosol direct and indirect effects, and global warming, the DTR has decreased in the past 4 decades observed from most of the weather stations around Taiwan. However, the declined rice paddy area may increase the DTR with higher Bowen ratio during the daytime. Preliminary results show that DTR is decreased in weather stations near the urban area, but increased in weather stations near fallow areas in the past 20 years. It shows that different land use changes may have opposite impacts on local and regional climate.

  18. Structure Slicing: Extending Logical Regions with Fields

    E-print Network

    Aiken, Alex

    of three Legion applications including S3D, a production combustion simulation that uses logical regions. Across-Cell and Across-Field Phases in S3D. fundamental dimension was missing from the design: describ- ing compound data types with multiple fields. Consider, for example, the combustion simulation S3D [11

  19. Towards Global Simulation of Irrigation in a Land Surface Model: Multiple Cropping and Rice Paddy in Southeast Asia

    NASA Technical Reports Server (NTRS)

    Beaudoing, Hiroko Kato; Rodell, Matthew; Ozdogan, Mutlu

    2010-01-01

    Agricultural land use significantly influences the surface water and energy balances. Effects of irrigation on land surface states and fluxes include repartitioning of latent and sensible heat fluxes, an increase in net radiation, and an increase in soil moisture and runoff. We are working on representing irrigation practices in continental- to global-scale land surface simulation in NASA's Global Land Data Assimilation System (GLDAS). Because agricultural practices across the nations are diverse, and complex, we are attempting to capture the first-order reality of the regional practices before achieving a global implementation. This study focuses on two issues in Southeast Asia: multiple cropping and rice paddy irrigation systems. We first characterize agricultural practices in the region (i.e., crop types, growing seasons, and irrigation) using the Global data set of monthly irrigated and rainfed crop areas around the year 2000 (MIRCA2000) dataset. Rice paddy extent is identified using remote sensing products. Whether irrigated or rainfed, flooded fields need to be represented and treated explicitly. By incorporating these properties and processes into a physically based land surface model, we are able to quantify the impacts on the simulated states and fluxes.

  20. Elevated ground-level O3 negatively influences paddy methanogenic archaeal community

    PubMed Central

    Feng, Youzhi; Lin, Xiangui; Yu, Yongchang; Zhang, Huayong; Chu, Haiyan; Zhu, Jianguo

    2013-01-01

    The current knowledge regarding the effect of global climate change on rice-paddy methane (CH4) emissions is incomplete, partly because information is limited concerning the mechanism of the microbial response to elevated ground-level ozone (O3). A field experiment was conducted in the China Ozone Free-Air Concentration Enrichment facility in a rice–wheat rotation system to investigate the responses of methanogenic archaeal communities to elevated ground-level O3 by culture-independent and -reliant approaches. We found that elevated ground-level O3 inhibited methanogenic activity and influenced the composition of paddy methanogenic communities, reducing the abundance and diversity of paddy methanogens by adversely affecting dominant groups, such as aceticlastic Methanosaeta, especially at the rice tillering stage. Our results indicated that continuously elevated ground-level O3 would negatively influence paddy methanogenic archaeal communities and its critical ecological function. These findings will contribute to a comprehensive understanding of the responses and feedbacks of paddy ecosystems to global climate change. PMID:24217205

  1. Season-long daily measurements of multifrequency (Ka, Ku, X, C, and L) and full-polarization backscatter signatures over paddy rice field and their relationship with biological variables

    Microsoft Academic Search

    Y. Inoue; T. Kurosu; H. Maeno; S. Uratsuka; T. Kozu; K. Dabrowska-Zielinska; J. Qi

    2002-01-01

    The objective of this study was to investigate the interaction between microwave backscatter signatures and rice canopy growth variables, as well as to provide definitive insight into the interaction between backscatter and vegetation based on a comprehensive data set collected under the unique crop conditions of paddy rice (background is water surface). Our unique data consisted of daily microwave backscattering

  2. Biogeochemical Typing of Paddy Field by a Data-Driven Approach Revealing Sub-Systems within a Complex Environment - A Pipeline to Filtrate, Organize and Frame Massive Dataset from Multi-Omics Analyses

    PubMed Central

    Ogawa, Diogo M. O.; Moriya, Shigeharu; Tsuboi, Yuuri; Date, Yasuhiro; Prieto-da-Silva, Álvaro R. B.; Rádis-Baptista, Gandhi; Yamane, Tetsuo; Kikuchi, Jun

    2014-01-01

    We propose the technique of biogeochemical typing (BGC typing) as a novel methodology to set forth the sub-systems of organismal communities associated to the correlated chemical profiles working within a larger complex environment. Given the intricate characteristic of both organismal and chemical consortia inherent to the nature, many environmental studies employ the holistic approach of multi-omics analyses undermining as much information as possible. Due to the massive amount of data produced applying multi-omics analyses, the results are hard to visualize and to process. The BGC typing analysis is a pipeline built using integrative statistical analysis that can treat such huge datasets filtering, organizing and framing the information based on the strength of the various mutual trends of the organismal and chemical fluctuations occurring simultaneously in the environment. To test our technique of BGC typing, we choose a rich environment abounding in chemical nutrients and organismal diversity: the surficial freshwater from Japanese paddy fields and surrounding waters. To identify the community consortia profile we employed metagenomics as high throughput sequencing (HTS) for the fragments amplified from Archaea rRNA, universal 16S rRNA and 18S rRNA; to assess the elemental content we employed ionomics by inductively coupled plasma optical emission spectroscopy (ICP-OES); and for the organic chemical profile, metabolomics employing both Fourier transformed infrared (FT-IR) spectroscopy and proton nuclear magnetic resonance (1H-NMR) all these analyses comprised our multi-omics dataset. The similar trends between the community consortia against the chemical profiles were connected through correlation. The result was then filtered, organized and framed according to correlation strengths and peculiarities. The output gave us four BGC types displaying uniqueness in community and chemical distribution, diversity and richness. We conclude therefore that the BGC typing is a successful technique for elucidating the sub-systems of organismal communities with associated chemical profiles in complex ecosystems. PMID:25330259

  3. The value of bat-boxes in the conservation of Pipistrellus pygmaeus in wetland rice paddies

    Microsoft Academic Search

    Carles Flaquer; Ignacio Torre; Ramon Ruiz-Jarillo

    2006-01-01

    Wetlands with rice paddies are key habitats in the conservation of biodiversity in the Mediterranean Region and are potentially suitable habitats for foraging bats, since they provide food (insects) and drinking places; nevertheless, many wetlands lack natural roosting sites. A bat-box program designed to ascertain bat-box preferences was initiated in 1999 in the Ebro Delta (NE Spain), one of the

  4. Global rain-fed, irrigated, and paddy croplands: A new high resolution map derived from remote sensing, crop inventories and climate data

    NASA Astrophysics Data System (ADS)

    Salmon, J. Meghan; Friedl, Mark A.; Frolking, Steve; Wisser, Dominik; Douglas, Ellen M.

    2015-06-01

    Irrigation accounts for 70% of global water use by humans and 33-40% of global food production comes from irrigated croplands. Accurate and timely information related to global irrigation is therefore needed to manage increasingly scarce water resources and to improve food security in the face of yield gaps, climate change and extreme events such as droughts, floods, and heat waves. Unfortunately, this information is not available for many regions of the world. This study aims to improve characterization of global rain-fed, irrigated and paddy croplands by integrating information from national and sub-national surveys, remote sensing, and gridded climate data sets. To achieve this goal, we used supervised classification of remote sensing, climate, and agricultural inventory data to generate a global map of irrigated, rain-fed, and paddy croplands. We estimate that 314 million hectares (Mha) worldwide were irrigated circa 2005. This includes 66 Mha of irrigated paddy cropland and 249 Mha of irrigated non-paddy cropland. Additionally, we estimate that 1047 Mha of cropland are managed under rain-fed conditions, including 63 Mha of rain-fed paddy cropland and 985 Mha of rain-fed non-paddy cropland. More generally, our results show that global mapping of irrigated, rain-fed, and paddy croplands is possible by combining information from multiple data sources. However, regions with rapidly changing irrigation or complex mixtures of irrigated and non-irrigated crops present significant challenges and require more and better data to support high quality mapping of irrigation.

  5. Microbial phototrophic fixation of atmospheric CO2 in China subtropical upland and paddy soils

    NASA Astrophysics Data System (ADS)

    Ge, Tida; Wu, Xiaohong; Chen, Xiaojuan; Yuan, Hongzhao; Zou, Ziying; Li, Baozhen; Zhou, Ping; Liu, Shoulong; Tong, Chengli; Brookes, Phil; Wu, Jinshui

    2013-07-01

    Autotrophic microorganisms, which can fix atmospheric CO2 to synthesize organic carbon, are numerous and widespread in soils. However, the extent and the mechanism of CO2 fixation in soils remain poorly understood. We incubated five upland and five paddy soils from subtropical China in an enclosed, continuously 14CO2-labeled, atmosphere and measured 14CO2 incorporated into soil organic matter (SOC14) and microbial biomass (MBC14) after 110 days. The five upland soils supported dominant crops soils (maize, wheat, sweet potato, and rapeseed) in the region, while all paddy soils were cultivated in a regime consisting of permanently-flooded double-cropping rice cultivation. The upland and paddy soils represented typical soil types (fluvisols and ultisols) and three landforms (upland, hill, and low mountain), ranging in total carbon from low (<10 g kg-1 soil organic carbon) to medium (10-20 g kg-1) to high (>20 g kg-1). Substantial amounts of 14CO2 were fixed into SOC14 (mean 20.1 ± 7.1 mg C kg-1 in upland soil, 121.1 ± 6.4 mg C kg-1 in paddy soil) in illuminated soils (12 h light/12 h dark), whereas no 14C was fixed in soils incubated in continuous darkness. We concluded that the microbial CO2 fixation was almost entirely phototrophic rather than chemotrophic. The rate of SOC14 synthesis was significantly higher in paddy soils than in upland soils. The SOC14 comprised means of 0.15 ± 0.01% (upland) and 0.65 ± 0.03% (paddy) of SOC. The extent of 14C immobilized as MBC14 and that present as dissolved organic C (DOC14) differed between soil types, accounting for 15.69-38.76% and 5.54-18.37% in upland soils and 15.57-40.03% and 3.67-7.17% of SOC14 in paddy soils, respectively. The MBC14/MBC and DOC14/DOC were 1.76-5.70% and 1.69-5.17% in the upland soils and 4.23-28.73% and 5.65-14.30% in the paddy soils, respectively. Thus, the newly-incorporated C stimulated the dynamics of DOC and MBC more than the dynamics of SOC. The SOC14 and MBC14 concentrations were highly significantly correlated (r = 0.946; P < 0.0001). We conclude that CO2 uptake by phototrophic soil microorganisms can contribute significantly to carbon assimilation in soil, and so warrants further future study.

  6. Methanogenic Pathway and Fraction of CH4 Oxidized in Paddy Fields: Seasonal Variation and Effect of Water Management in Winter Fallow Season

    PubMed Central

    Zhang, Guangbin; Liu, Gang; Zhang, Yi; Ma, Jing; Xu, Hua; Yagi, Kazuyuki

    2013-01-01

    A 2-year field and incubation experiment was conducted to investigate ?13C during the processes of CH4 emission from the fields subjected to two water managements (flooding and drainage) in the winter fallow season, and further to estimate relative contribution of acetate to total methanogenesis (Fac) and fraction of CH4 oxidized (Fox) based on the isotopic data. Compared with flooding, drainage generally caused CH4, either anaerobically or aerobically produced, depleted in 13C. There was no obvious difference between the two in transport fractionation factor (?transport) and ?13C-value of emitted CH4. CH4 emission was negatively related to its ?13C-value in seasonal variation (P<0.01). Acetate-dependent methanogenesis in soil was dominant (60–70%) in the late season, while drainage decreased Fac-value by 5–10%. On roots however, CH4 was mostly produced through H2/CO2 reduction (60–100%) over the season. CH4 oxidation mainly occurred in the first half of the season and roughly 10–90% of the CH4 was oxidized in the rhizosphere. Drainage increased Fox-value by 5–15%, which is possibly attributed to a significant decrease in production while no simultaneous decrease in oxidation. Around 30–70% of the CH4 was oxidized at the soil-water interface when CH4 in pore water was released into floodwater, although the amount of CH4 oxidized therein might be negligible relative to that in the rhizosphere. CH4 oxidation was also more important in the first half of the season in lab conditions and about 5–50% of the CH4 was oxidized in soil while almost 100% on roots. Drainage decreased Fox-value on roots by 15% as their CH4 oxidation potential was highly reduced. The findings suggest that water management in the winter fallow season substantially affects Fac in the soil and Fox in the rhizosphere and roots rather than Fac on roots and Fox at the soil-water interface. PMID:24069259

  7. Community Structure and Soil pH Determine Chemoautotrophic Carbon Dioxide Fixation in Drained Paddy Soils.

    PubMed

    Long, Xi-En; Yao, Huaiying; Wang, Juan; Huang, Ying; Singh, Brajesh K; Zhu, Yong-Guan

    2015-06-16

    Previous studies suggested that microbial photosynthesis plays a potential role in paddy fields, but little is known about chemoautotrophic carbon fixers in drained paddy soils. We conducted a microcosm study using soil samples from five paddy fields to determine the environmental factors and quantify key functional microbial taxa involved in chemoautotrophic carbon fixation. We used stable isotope probing in combination with phospholipid fatty acid (PLFA) and molecular approaches. The amount of microbial (13)CO2 fixation was determined by quantification of (13)C-enriched fatty acid methyl esters and ranged from 21.28 to 72.48 ng of (13)C (g of dry soil)(-1), and the corresponding ratio (labeled PLFA-C:total PLFA-C) ranged from 0.06 to 0.49%. The amount of incorporationof (13)CO2 into PLFAs significantly increased with soil pH except at pH 7.8. PLFA and high-throughput sequencing results indicated a dominant role of Gram-negative bacteria or proteobacteria in (13)CO2 fixation. Correlation analysis indicated a significant association between microbial community structure and carbon fixation. We provide direct evidence of chemoautotrophic C fixation in soils with statistical evidence of microbial community structure regulation of inorganic carbon fixation in the paddy soil ecosystem. PMID:25989872

  8. Elevated CO2 facilitates C and N accumulation in a rice paddy ecosystem.

    PubMed

    Guo, Jia; Zhang, Mingqian; Wang, Xiaowen; Zhang, Weijian

    2015-03-01

    Elevated CO2 can stimulate wetland carbon (C) and nitrogen (N) exports through gaseous and dissolved pathways, however, the consequent influences on the C and N pools are still not fully known. Therefore, we set up a free-air CO2 enrichment experiment in a paddy field in Eastern China. After five year fumigation, we studied C and N in the plant-water-soil system. The results showed: (1) elevated CO2 stimulated rice aboveground biomass and N accumulations by 19.1% and 12.5%, respectively. (2) Elevated CO2 significantly increased paddy soil TOC and TN contents by 12.5% and 15.5%, respectively in the 0-15cm layer, and 22.7% and 26.0% in the 15-30cm soil layer. (3) Averaged across the rice growing period, elevated CO2 greatly increased TOC and TN contents in the surface water by 7.6% and 11.4%, respectively. (4) The TOC/TN ratio and natural ?(15)N value in the surface soil showed a decreasing trend under elevated CO2. The above results indicate that elevated CO2 can benefit C and N accumulation in paddy fields. Given the similarity between the paddies and natural wetlands, our results also suggest a great potential for long-term C and N accumulation in natural wetlands under future climate patterns. PMID:25766010

  9. Behavior of cinosulfuron in paddy surface waters, sediments, and ground water.

    PubMed

    Ferrero, A; Vidotto, F; Gennari, M; Nègre, M

    2001-01-01

    Cinosulfuron (3-(4,6-dimethoxy-1,3,5-triazin-2-yl)-1-[2-(2-methoxyethoxy)-phenylsulfonyl]-urea) is a sulfonylurea herbicide used to control a wide range of broadleaf weeds in rice (Oryza sativa L.). A 2-yr field study was conducted in northwest Italy to determine the effect of cinosulfuron on surface and subsoil waters in rice paddies. Cinosulfuron was applied at 70 g a.i. ha(-1) on 35 ha of flooded rice. After the treatment, the change in herbicide concentration over time was studied by analyzing water and sediment samples in a test paddy field (2.16 ha, located in the treated area), water in a spring and a pond (both located near the test paddy), two wells (up- and downhill to the treated area), and two piezometers (along the test paddy levee). To better understand some of the field study results, cinosulfuron degradation was also evaluated in the laboratory in solutions buffered to different pH values. Two weeks after the treatment, the cinosulfuron concentration in the paddy water decreased by about 60%. No cinosulfuron was detected at about 2.5 mo after the treatment. The concentration in the sediment gradually increased after the treatment, reaching the highest value (13.53 microg kg(-1)) 3 wk later. The maximum cinosulfuron content in the spring and pond were 0.91 and 0.29 microg L(-1), respectively, and these were detected 60 to 90 days after treatment (DAT). The water collected in the piezometers reached the highest concentration (0.99 microg L(-1)) 29 DAT. Cinosulfuron was never detected in the wells. In the degradation study at different pH values, cinosulfuron degraded rapidly at low pH values. PMID:11215644

  10. Influence of the nonexchangeable potassium of mica on radiocesium uptake by paddy rice.

    PubMed

    Eguchi, Tetsuya; Ohta, Takeshi; Ishikawa, Tetsuya; Matsunami, Hisaya; Takahashi, Yoshihiko; Kubo, Katashi; Yamaguchi, Noriko; Kihou, Nobuharu; Shinano, Takuro

    2015-09-01

    A pot cultivation experiment was conducted to elucidate the influence of the nonexchangeable potassium (K) of mica on radiocesium ((137)Cs) uptake by paddy rice (Oryza sativa L. cv. Koshihikari), and to evaluate the potential of mica application as a countermeasure to reduce radiocesium transfer from soil to paddy rice. The increase in the exchangeable K concentrations of soils, measured before planting, due to mica (muscovite, biotite, and phlogopite) application was negligible. However, in trioctahedral mica (biotite and phlogopite)-treated soil, the release of nonexchangeable K from the mica interlayer maintained the soil-solution K at a higher level during the growing season in comparison to the control, and consequently decreased the (137)Cs transfer factor for brown rice (TF). The sodium tetraphenylboron (TPB)-extractable K concentration of the soils, measured before planting, was strongly negatively correlated with the TF, whereas the exchangeable K concentration of the soils, also measured before planting, was not correlated with the TF. Therefore, we conclude that TPB-extractable K is more reliable than exchangeable K as a basis of fertilizer recommendations for radiocesium-contaminated paddy fields. Phlogopite-treated soils exhibited higher TPB-extractable K concentrations and lower TF values than biotite-treated soils. We thus conclude that phlogopite application is an effective countermeasure to reduce radiocesium uptake in paddy rice. PMID:26026983

  11. Effect of drying on heavy metal fraction distribution in rice paddy soil.

    PubMed

    Qi, Yanbing; Huang, Biao; Darilek, Jeremy Landon

    2014-01-01

    An understanding of how redox conditions affect soil heavy metal fractions in rice paddies is important due to its implications for heavy metal mobility and plant uptake. Rice paddy soil samples routinely undergo oxidation prior to heavy metal analysis. Fraction distribution of Cu, Pb, Ni, and Cd from paddy soil with a wide pH range was investigated. Samples were both dried according to standard protocols and also preserved under anaerobic conditions through the sampling and analysis process and heavy metals were then sequentially extracted for the exchangeable and carbonate bound fraction (acid soluble fraction), iron and manganese oxide bound fraction (reducible fraction), organic bound fraction (oxidizable fraction), and residual fraction. Fractions were affected by redox conditions across all pH ranges. Drying decreased reducible fraction of all heavy metals. Curesidual fraction, Pboxidizable fraction, Cdresidual fraction, and Niresidual fraction increased by 25%, 33%, 35%, and >60%, respectively. Pbresidual fraction, Niacid soluble fraction, and Cdoxidizable fraction decreased 33%, 25%, and 15%, respectively. Drying paddy soil prior to heavy metal analysis overestimated Pb and underestimated Cu, Ni, and Cd. In future studies, samples should be stored after injecting N2 gas to maintain the redox potential of soil prior to heavy metal analysis, and investigate the correlation between heavy metal fraction distribution under field conditions and air-dried samples. PMID:24823670

  12. Effect of biochar amendment on yield and methane and nitrous oxide emissions from a rice paddy from Tai Lake plain, China

    Microsoft Academic Search

    Afeng Zhang; Liqiang Cui; Gengxing Pan; Lianqing Li; Qaiser Hussain; Xuhui Zhang; Jinwei Zheng; David Crowley

    2010-01-01

    A field trial was performed to investigate the effect of biochar at rates of 0, 10 and 40tha?1 on rice yield and CH4 and N2O emissions with or without N fertilization in a rice paddy from Tai Lake plain, China. The paddy was cultivated with rice (Oryza sativa L., cv. Wuyunjing 7) under a conventional water regime. Soil emissions of

  13. Alteration of certain soil microbiological and biochemical indices of a paddy soil under anthropogenic stress

    Microsoft Academic Search

    Abid Subhani; Liao Min; Huang Chang-Yong; Xie Zheng-miao

    2002-01-01

    A 21-day laboratory incubation experiment was conducted to investigate the impact of pesticides (insecticide, herbicide, fungicide)\\u000a on paddy field soil health under controlled moisture (flooded soil) and temperature (25°C) environment. The electron transport\\u000a system (ETS)\\/Dehydrogenase activity showed negative correlation with pesticides concentrations, decreased with increase of\\u000a pesticide concentration. The higher doses (5 to 10 times field rates) of pesticides significantly

  14. The influence of land use on the concentration and vertical distribution of PBDEs in soils of an e-waste recycling region of South China.

    PubMed

    Cheng, Zhineng; Wang, Yan; Wang, Shaorui; Luo, Chunling; Li, Jun; Chaemfa, Chakra; Jiang, Haoyu; Zhang, Gan

    2014-08-01

    The vertical distribution of polybrominated diphenyl ethers (PBDEs) in soil at four sites within an e-waste recycling region of South China was investigated. PBDE concentrations in soil ranged from 1.38 to 765 ng/g. There was a trend of decreasing PBDE concentration with soil depth, especially in the paddy field. However, high concentrations of BDE-209 were found in deeper soils indicating a highly preferential migration. There was a stronger correlation between PBDEs and total organic carbon (TOC), compared to dissolved organic carbon (DOC), which suggests that the association between non-dissolved organic carbon (NDOC) and PBDEs is stronger than for DOC. Different land use types, in particular differences in farming activities, significantly influenced the vertical distribution of PBDEs in soils. PBDEs displayed a higher leaching tendency in moist paddy soil than in drier soils. The frequent flooding condition in paddy field may facilitate the vertical transfer of PBDEs to the deeper soils. PMID:24832923

  15. Investigating Arsenic Mobilization Mechanisms as well as Complexation Between Arsenic and Polysulfides Associated With a Bangladeshi Rice Paddy

    NASA Astrophysics Data System (ADS)

    Lin, T.; Kampalath, R.; Jay, J.

    2009-12-01

    The presence of arsenic in the groundwater has led to the largest environmental poisoning in history. Although it is a worldwide issue that affects numerous countries, including Taiwan, Bangladesh, India, China, Mexico, Peru, Australia, and the United States, the issue is of greatest concern in the West Bengal region. In the Ganges Delta, as many as 2 million people are diagnosed with arsenicosis each year. The World Health Organization (WHO) estimates 200,000 to 270,000 arsenic-induced cancer-related deaths in Bangladesh alone. More than 100 million people in the country consume groundwater that exceeds the WHO limit as 50% of the 8 million wells contain groundwater with more than 10 ?g/L. Despite the tragic public health implications of this problem, we do not yet have a complete answer to the question of why dissolved arsenic concentrations are so high in the groundwater of the Ganges Delta. Since 1999, we have been intensively studying a field site in Munshiganj, Bangladesh with extremely high levels of arsenic in groundwater (up to 1.2 mg/L). Sediment cores were collected from two locations at the field site: 1) the rice paddy and 2) edge of a nearby irrigation pond. Recharge from irrigation ponds have recently been hypothesized to be an important site of arsenic mobilization. Recent work has proposed mineral dissolution under phosphorus-limited conditions as an important mechanism for arsenic mobilization. Using microcosms with paddy and pond sediment, we are comparing arsenic release via this mechanism with that resulting from reduction of iron hydroxides at our site. Concurrently, we are looking at enhanced solubility of As in the presence of polysulfides as the effects of elemental sulfur on As solubility have not been well researched. We hypothesize that the presence of elemental sulfur, and consequent formation of polysulfides, will substantially increase the solubility of orpiment in sulfidic water and that sorption of these complexes will significantly affect the mobility of these species of As in groundwater. We have shown substantial (order of magnitude) increases in metal solubility in bottle in the presence of elemental sulfur and sulfide compared to bottles in the presence of the same concentration of sulfide alone. This is presumably attributable to metal-polysulfide complexation. Further experiments measuring solubility over a range of pH and sulfide levels are necessary to model the data and determine complexation constants. By elucidating As mobilization mechanisms at an experimental rice paddy, this work could ultimately lead to solutions that minimize As exposure in critical populations.

  16. Large-scale unipolar regions generated from undeep magnetic fields

    NASA Astrophysics Data System (ADS)

    Callebaut, D. K.; Hady, A. A.; Karugila, G. K.; Khater, A. H.

    We explain the generation of the large-scale unipolar magnetic field regions (global magnetic regions) by the same dynamo action as for the generation of the sunspots and the polar faculae butterfly diagrams as given by Callebaut (2006). The previous global magnetic regions through meridional circulation now serve as the main seed fields (flux-transport dynamo for the global field regions), possibly supplemented by leftovers from the sunspots and some weak fields generated at the tachocline.

  17. Mineralization of metsulfuron-methyl in Chinese paddy soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A laboratory study was conducted to investigate the mineralization of metsulfuron-methyl (MSM) in paddy soils in response to soil moisture, temperature and soil properties. The results indicated that MSM mineralization was relatively limited in the paddy soils when soil temperature was low. Only 2.2...

  18. Naidid worms (Oligochaeta, Naididae) in paddy soils as affected by the application of legume mulch and\\/or tillage practice

    Microsoft Academic Search

    Hiroshi Yokota; Nobuhiro Kaneko

    2002-01-01

    Reproduction, intrinsic rate of natural increase and population density of naidid worms were investigated in submerged paddy fields and the laboratory. No tillage plus legume-mulching increased the population density of naidid worms. Soil treatments with neither tillage nor legume mulch, and tillage practice alone, did not increase the number of worms. Dero dorsalis Ferronnière was dominant in soil of the

  19. Spatial and temporal variations in the use of rice-paddy dominated landscapes by birds in Japan

    Microsoft Academic Search

    Tatsuya Amano; Yoshinobu Kusumoto; Yoshinori Tokuoka; Susumu Yamada; Eun-Young Kim; Shori Yamamoto

    2008-01-01

    Agricultural landscapes with spatial and temporal variations interact with each other to affect the existing biodiversity. Though rice fields provide important habitats for birds all over the world, studies so far have rarely explored the effects of landscape heterogeneity on bird species in rice paddy areas. This study investigated the effects of habitat cover and landscape variables on the species

  20. Alleviation of Soil Aluminum Phytotoxicity in a Typical Paddy Soil in Southern China by Using Weak Organic Acids

    Microsoft Academic Search

    Shuying Yang; Yingbin Zou; Xianghua Liu

    2009-01-01

    Weak organic acids including tartaric and citric acids were applied to a typical paddy soil in southern China to test their effects on rice in the field for three years. Their effects were also compared with top dressings of the two acids, basal application of diammonium acid phosphate, calcium carbonate, and the control. The results showed that rice grain yield

  1. Modeling of short-term runoff processes in heterogeneous watersheds dominated by abandoned paddies in hilly areas

    NASA Astrophysics Data System (ADS)

    Yoshida, T.; Masumoto, T.; Horikawa, N.; Minakawa, H.

    2012-12-01

    Large capacity of water storage in terraced paddies plays a crucial role in regional hydrological cycles of hilly areas in Japan, whose roles are reduction of flood peaks and prevention of land-slides for instance. However, rapid increase in abandoned terraced paddies causes substantial changes in rainfall-runoff relationship; and thereby potential risk of serious flood damage may arise in the downstream. The objectives of this study are twofold. One is to investigate changes in short-term runoff characteristics due to the increase of abandoned terrace paddies in hilly areas by hydrological observation. The other is to assess the interaction between basin-scale hydrological cycles and conditions of paddies with a distributed hydrological model. First, we set up three experimental watersheds based on land use and cultivation status of paddies: namely Cultivated Paddy-dominant Watershed (CPW), Abandoned Paddy-dominant Watershed (APW) and Forest Watershed (FW), whose areas are approximately 1km2. The retention capacity, runoff ratio and peak runoff coefficients for large discharges from each watershed were analyzed using rainfall and discharge data observed at 10-minute intervals. From the analysis, we revealed that the peak runoff coefficients of CPW and APW were 0.24 and 0.30, respectively. In addition, the runoff ratios of APW were, under wet conditions, found to be 31.4% higher than those of CPW at the maximum. These results indicate that abandonment of paddies lead to larger peak discharges and direct runoff, suggesting a higher flood risk in the area. Meanwhile, the maximum retention capacity of APW decreased by approximately 10mm compared with those of CPW and FW, suggesting lower water availability in dry periods. Next, we developed a distributed water circulation model and applied it to the three experimental watersheds. The model was configured by grid-cells of 100x100m, each of which consisted of three soil layers for runoff calculation. The model represents lateral flows in surface and saturated zone as well as generation of surface flow based on heterogeneous land uses and paddy cultivation in a grid-cell. To calculate the short-term runoff, first, long-term rainfall runoff calculations at 1-day intervals were carried out for each experimental watershed. Then, model state variables of three layers, which are root zone, unsaturated zone and saturated zone storage, were extracted for rainfall events that exceeded the predefined threshold, which is daily precipitation of 20 mm and rainfall intensity of 5 mm/h. Lastly, the extracted state variables were used as initial conditions for short-term runoff calculations at 10-min intervals in CPW and APW. The calculated short-term discharges closely agreed with the observed discharges. Especially, the differences in peak discharge between CPW and APW were well represented by the model. Following the model assessment, the comparison of calculated state variables between the experimental watersheds revealed that the storage volumes of saturated zones in the grid-cells where the abandoned paddies exist are higher than those with the cultivated paddies, suggesting higher water table depth around the abandoned paddies. The model experiments showed that those discrepancies in groundwater storage may affect the short-term runoff characteristics of small watersheds.

  2. Sources of atmospheric methane - Measurements in rice paddies and a discussion

    NASA Technical Reports Server (NTRS)

    Cicerone, R. J.; Shetter, J. D.

    1981-01-01

    Field measurements of methane fluxes from rice paddies, fresh water lakes, and saltwater marshes have been made to infer estimates of the size of these sources of atmospheric methane. The rice-paddy measurements, the first of their kind, show that the principal means of methane escape is through the plants themselves as opposed to transport across the water-air interface via bubbles or molecular diffusion. Nitrogen-fertilized plants release much more methane than unfertilized plants but even these measured rates are only one fourth as large as those inferred earlier by Koyama (1963, 1964) and on which all global extrapolations have been based to date. Measured methane fluxes from lakes and marshes are also compared to similar earlier data and it is found that extant data and flux-measurement methods are insufficient for reliable global extrapolations.

  3. Central Region Library Field Records Collection

    USGS Multimedia Gallery

    The USGS Denver Library, Field Records Collection is an archive of unpublished field notes, maps, correspondence, manuscripts, analysis reports, and other data created or collected by USGS Geologic Discipline scientists during field studies and other project work. Materials in the collection represe...

  4. Spatial and Temporal Variations of Rice Paddy as Influenced by Climate Change in the Sanjiang Plain, Northeastern China

    NASA Astrophysics Data System (ADS)

    Chen, J.; Liu, Q.; Ma, L.; Hou, S.; Tao, B.

    2014-12-01

    The Sanjiang Plain is located in the eastern part of Heilongjiang Province, Northeastern China, and represents one of major agricultural regions nationwide. Over past decades, this region has seen intensive cropland reclamation and a sharp shrinkage of natural vegetation and water bodies, driven by not only policy-making and economic development, but also a warming climate. However, it still remains unclear how climate change has influenced the magnitude and spatial patterns of land use changes. In this study, we examined spatial and temporal variations of rice paddy planting area during 1980-2008 through an integration of the remote-sensing images, the census data, and other existing land use/cover data sets. The daily gridded climate data sets were generated by using an interpolation method of thin plate smoothing splines, based on observations from over 70 meteorological stations across the study area. Our results suggest that the rice paddy planting area increased by more than 10-fold during 1980-2008, with more obvious upward trends during two sub-periods, i.e. 1995-1998 and 2004-2008. Further analyses indicated that the rice paddy planting area accounted for approximately 20.3% of total cropland area in 2008, increasing more than seven-fold as compared to 1980. When investigating spatially, we found that the planting boundary of rice paddy expanded northward for roughly 2 degree, comparing to 1984 when most of rice paddies were found in the north of the 48o N. Most of increases of rice paddy planting area occurred in the northeast of the study region. The climate analyses showed a significant warming trend, with a slightly decrease in precipitation. During the study period, the suitable areas for rice production increased about 25% and expanded northward clearly. Our study demonstrated how climate change influenced the magnitude and spatial patterns of rice paddy planting area in the Sanjiang Plain, which could provide scientific information for the environmental assessment and related policy-making. It implies that climate change could result in substantial land use/cover changes through climate adaption strategies that humans adopted. While, how to compromise those adaption strategies and environmental sustainability (e.g., preserving water resources and biodiversity) need further invstigation.

  5. A Simple Evaluation of Soil Quality of Waterlogged Purple Paddy Soils with Different Productivities

    PubMed Central

    Liu, Zhanjun; Zhou, Wei; Lv, Jialong; He, Ping; Liang, Guoqing; Jin, Hui

    2015-01-01

    Evaluation of soil quality can be crucial for designing efficient farming systems and ensuring sustainable agriculture. The present study aimed at evaluating the quality of waterlogged purple paddy soils with different productivities in Sichuan Basin. The approach involved comprehensive analyses of soil physical and chemical properties, as well as enzyme activities and microbial community structure measured by phospholipid fatty acid analysis (PLFA). A total of 36 soil samples were collected from four typical locations, with 12 samples representing high productivity purple paddy soil (HPPS), medium productivity purple paddy soil (MPPS) and low productivity purple paddy soil (LPPS), respectively. Most measured soil properties showed significant differences (P ? 0.05) among HPPS, MPPS and LPPS. Pearson correlation analysis and principal component analysis were used to identify appropriate soil quality indicators. A minimum data set (MDS) including total nitrogen (TN), available phosphorus (AP), acid phosphatase (ACP), total bacteria (TB) and arbuscular mycorrhizal fungi was established and accounted for 82.1% of the quality variation among soils. A soil quality index (SQI) was developed based on the MDS method, whilst HPPS, MPPS and LPPS received mean SQI scores of 0.725, 0.536 and 0.425, respectively, with a ranking of HPPS > MPPS > LPPS. HPPS showed relatively good soil quality characterized by optimal nutrient availability, enzymatic and microbial activities, but the opposite was true of LPPS. Low levels of TN, AP and soil microbial activities were considered to be the major constraints limiting the productivity in LPPS. All soil samples collected were rich in available N, K, Si and Zn, but deficient in available P, which may be the major constraint for the studied regions. Managers in our study area should employ more appropriate management in the LPPS to improve its rice productivity, and particularly to any potential limiting factor. PMID:25997107

  6. A simple evaluation of soil quality of waterlogged purple paddy soils with different productivities.

    PubMed

    Liu, Zhanjun; Zhou, Wei; Lv, Jialong; He, Ping; Liang, Guoqing; Jin, Hui

    2015-01-01

    Evaluation of soil quality can be crucial for designing efficient farming systems and ensuring sustainable agriculture. The present study aimed at evaluating the quality of waterlogged purple paddy soils with different productivities in Sichuan Basin. The approach involved comprehensive analyses of soil physical and chemical properties, as well as enzyme activities and microbial community structure measured by phospholipid fatty acid analysis (PLFA). A total of 36 soil samples were collected from four typical locations, with 12 samples representing high productivity purple paddy soil (HPPS), medium productivity purple paddy soil (MPPS) and low productivity purple paddy soil (LPPS), respectively. Most measured soil properties showed significant differences (P ? 0.05) among HPPS, MPPS and LPPS. Pearson correlation analysis and principal component analysis were used to identify appropriate soil quality indicators. A minimum data set (MDS) including total nitrogen (TN), available phosphorus (AP), acid phosphatase (ACP), total bacteria (TB) and arbuscular mycorrhizal fungi was established and accounted for 82.1% of the quality variation among soils. A soil quality index (SQI) was developed based on the MDS method, whilst HPPS, MPPS and LPPS received mean SQI scores of 0.725, 0.536 and 0.425, respectively, with a ranking of HPPS > MPPS > LPPS. HPPS showed relatively good soil quality characterized by optimal nutrient availability, enzymatic and microbial activities, but the opposite was true of LPPS. Low levels of TN, AP and soil microbial activities were considered to be the major constraints limiting the productivity in LPPS. All soil samples collected were rich in available N, K, Si and Zn, but deficient in available P, which may be the major constraint for the studied regions. Managers in our study area should employ more appropriate management in the LPPS to improve its rice productivity, and particularly to any potential limiting factor. PMID:25997107

  7. Ground cover rice production system facilitates soil carbon and nitrogen stocks at regional scale

    NASA Astrophysics Data System (ADS)

    Liu, M.; Dannenmann, M.; Lin, S.; Saiz, G.; Yan, G.; Yao, Z.; Pelster, D.; Tao, H.; Sippel, S.; Tao, Y.; Zhang, Y.; Zheng, X.; Zuo, Q.; Butterbach-Bahl, K.

    2015-02-01

    Rice production is increasingly challenged by irrigation water scarcity, however covering paddy rice soils with films (ground cover rice production system: GCRPS) can significantly reduce water demand as well as overcome temperature limitations at the beginning of the vegetation period resulting in increased grain yields in colder regions of rice production with seasonal water shortages. It has been speculated that the increased soil aeration and temperature under GCRPS may result in losses of soil organic carbon and nitrogen stocks. Here we report on a regional scale experiment, conducted by sampling paired adjacent Paddy and GCRPS fields at 49 representative sites in the Shiyan region, which is typical for many mountainous areas across China. Parameters evaluated included soil C and N stocks, soil physical and chemical properties, potential carbon mineralization rates, fractions of soil organic carbon and stable carbon isotopic composition of plant leaves. Furthermore, root biomass was quantified at maximum tillering stage at one of our paired sites. Against expectations the study showed that: (1) GCRPS significantly increased soil organic C and N stocks 5-20 years following conversion of production systems, (2) there were no differences between GCRPS and Paddy in soil physical and chemical properties for the various soil depths with the exception of soil bulk density, (3) GCRPS had lower mineralization potential for soil organic C compared with Paddy over the incubation period, (4) GCRPS showed lower ?15N in the soils and plant leafs indicating less NH3 volatilization in GCRPS than in Paddy; and (5) GCRPS increased yields and root biomass in all soil layers down to 40 cm depth. Our results suggest that GCRPS is an innovative rice production technique that not only increases yields using less irrigation water, but that it also is environmentally beneficial due to increased soil C and N stocks at regional scale.

  8. Potential contribution of anammox to nitrogen loss from paddy soils in Southern China.

    PubMed

    Yang, Xiao-Ru; Li, Hu; Nie, San-An; Su, Jian-Qiang; Weng, Bo-Sen; Zhu, Gui-Bing; Yao, Huai-Ying; Gilbert, Jack A; Zhu, Yong-Guan

    2015-02-01

    The anaerobic oxidation of ammonium (anammox) process has been observed in diverse terrestrial ecosystems, while the contribution of anammox to N2 production in paddy soils is not well documented. In this study, the anammox activity and the abundance and diversity of anammox bacteria were investigated to assess the anammox potential of 12 typical paddy soils collected in southern China. Anammox bacteria related to "Candidatus Brocadia" and "Candidatus Kuenenia" and two novel unidentified clusters were detected, with "Candidatus Brocadia" comprising 50% of the anammox population. The prevalence of the anammox was confirmed by the quantitative PCR results based on hydrazine synthase (hzsB) genes, which showed that the abundance ranged from 1.16 × 10(4) to 9.65 × 10(4) copies per gram of dry weight. The anammox rates measured by the isotope-pairing technique ranged from 0.27 to 5.25 nmol N per gram of soil per hour in these paddy soils, which contributed 0.6 to 15% to soil N2 production. It is estimated that a total loss of 2.50 × 10(6) Mg N per year is linked to anammox in the paddy fields in southern China, which implied that ca. 10% of the applied ammonia fertilizers is lost via the anammox process. Anammox activity was significantly correlated with the abundance of hzsB genes, soil nitrate concentration, and C/N ratio. Additionally, ammonia concentration and pH were found to be significantly correlated with the anammox bacterial structure. PMID:25416768

  9. Role of water flow in modeling methane emissions from flooded paddy soils

    NASA Astrophysics Data System (ADS)

    Rizzo, A.; Boano, F.; Revelli, R.; Ridolfi, L.

    2013-02-01

    Methane (CH4) is a potent greenhouse gas that is emitted from paddy fields, and the large CH4 fluxes represent a worldwide issue for the rice production eco-compatibility. In this work a model is proposed to investigate the role of water flows on CH4 emissions from flooded paddy soils. The model is based on a system of partial differential mass balance equations of the chemical species affecting CH4 fate, and water flows are modeled by the Darcy equation. Moreover, in order to properly model the dynamics of CH4, a number of physico-chemical processes and features not included in currently available CH4 emission models are considered: paddy soil stratigraphy; nutrient adsorption and root water uptake; gas transport and respiration within root aerenchyma compartment. The proposed model allows to simulate the spatio-temporal dynamics of chemical compounds within paddy soil as well as to quantify the influence of different processes on nutrient input/output budgets. Simulations without water flow have shown a considerable overestimation of CH4 emissions due to a different spatio-temporal dynamics of dissolved organic matter (DOC - source of energy for CH4 production). In particular, when water fluxes have not been modeled the overestimation can reach 54%, 41% and 67% of daily minimum, daily maximum, and total over the whole growing season CH4 emission, respectively. Moreover, the model results suggest that roots influence CH4 dynamics principally due to their nutrient uptake, while root effect on advective flow plays a minor role. Finally, the analysis of CH4 transport fluxes has shown the limiting effect of upward dispersive transport fluxes on the downward CH4 percolation.

  10. Soil Physicochemical and Biological Properties of Paddy-Upland Rotation: A Review

    PubMed Central

    Lv, Teng-Fei; Chen, Yong; Westby, Anthony P.; Ren, Wan-Jun

    2014-01-01

    Paddy-upland rotation is an unavoidable cropping system for Asia to meet the increasing demand for food. The reduction in grain yields has increased the research interest on the soil properties of rice-based cropping systems. Paddy-upland rotation fields are unique from other wetland or upland soils, because they are associated with frequent cycling between wetting and drying under anaerobic and aerobic conditions; such rotations affect the soil C and N cycles, make the chemical speciation and biological effectiveness of soil nutrient elements varied with seasons, increase the diversity of soil organisms, and make the soil physical properties more difficult to analyze. Consequently, maintaining or improving soil quality at a desirable level has become a complicated issue. Therefore, fully understanding the soil characteristics of paddy-upland rotation is necessary for the sustainable development of the system. In this paper, we offer helpful insight into the effect of rice-upland combinations on the soil chemical, physical, and biological properties, which could provide guidance for reasonable cultivation management measures and contribute to the improvement of soil quality and crop yield. PMID:24995366

  11. Sun's small-scale magnetic field : from quiet region to polar region

    NASA Astrophysics Data System (ADS)

    Jin, C. L.; Wang, J. X.; Zhao, M.

    2012-06-01

    In this contribution, we present our recent effort in understanding the solar small-scale magnetic field. Firstly, with the unique data from MDI/SOHO in an interval embodying solar cycle 23, we find three categories of small-scale magnetic elements, and their number variations shows no correlation, anti-correlation and correlation with sunspots, respectively. The possible sources for the three categories of small-scale magnetic elements are discussed. Secondly, by the observations from SOT on board Hinode, we study the properties of vector magnetic field in quiet Sun. The following results are summarized. (1) Two categories of horizontal magnetic elements are disclosed, and most of horizontal elements are associate with the emergence of U-loop. (2) The magnetic field of quiet region is obviously non-potential. The filigrees and network bright points are characterized by strong longitudinal field, large electric helicity and free energy density. (3) For quiet region, the intra-network region displays a predominance of weak field concentration, but network region shows the coexisting of weak field with strong field; For polar region, the strong field occupies 6.7% of the region. (4) On quiet region, the magnetic field mainly resides in the inter-granular lanes. By the observation, we reconstruct an average granular model, for which the detailed distributions of vector fields, Doppler velocity and intensity are obtained.

  12. Differential Magnetic Field Shear in an Active Region

    NASA Technical Reports Server (NTRS)

    Schmeider, B.; DeMoulin, P.; Aulanier, G.; Golub, Leon

    1997-01-01

    The three-dimensional extrapolation of magnetic field lines from a magnetogram obtained at Kitt Peak allows us to understand the global structure of the NOAA active region 6718, as observed in X-rays with the Normal Incidence X-ray Telescope (NIXT) and in Ha with the Multichannel Subtractive Double Pass spectrograph (MSDP) in Meudon on 1991 July 11. This active region was in a quiet stage. Bright X-ray loops connect plages having field strengths of approx. 300 G, while H-alpha fibriles connect penumbrae having strong spot fields to the surrounding network. Small, intense X-ray features in the moat region around a large spot, which could be called X-ray-bright points, are due mainly to the emergence of magnetic flux and merging of these fields with surrounding ones. A set of large-scale, sheared X-ray loops is observed in the central part of the active region. Based on the fit between the observed coronal structure and the field configurations (and assuming a linear force-free field), we propose a differential magnetic field shear model for this active region. The decreasing shear in outer portions of the active region may indicate a continual relaxation of the magnetic field to a lower energy state in the progressively older portions of the AR.

  13. Wake Fields in the Super B Factory Interaction Region

    SciTech Connect

    Weathersby, Stephen; /SLAC; Novokhatski, Alexander; /SLAC

    2011-06-02

    The geometry of storage ring collider interaction regions present an impedance to beam fields resulting in the generation of additional electromagnetic fields (higher order modes or wake fields) which affect the beam energy and trajectory. These affects are computed for the Super B interaction region by evaluating longitudinal loss factors and averaged transverse kicks for short range wake fields. Results indicate at least a factor of 2 lower wake field power generation in comparison with the interaction region geometry of the PEP-II B-factory collider. Wake field reduction is a consderation in the Super B design. Transverse kicks are consistent with an attractive potential from the crotch nearest the beam trajectory. The longitudinal loss factor scales as the -2.5 power of the bunch length. A factor of 60 loss factor reduction is possible with crotch geometry based on an intersecting tubes model.

  14. Speciation and Release Kinetics of Zinc in Contaminated Paddy Soils Saengdao Khaokaew,*,

    E-print Network

    Sparks, Donald L.

    Speciation and Release Kinetics of Zinc in Contaminated Paddy Soils Saengdao Khaokaew,*, Gautier activities can result in Zn and Cd contamination in environments, including paddy soils.1-5 Although Zn, around 2200 ha of paddy soils have been heavily contaminated by Cd and Zn.3,10 The total concentrations

  15. Agricultural Field in the Great Plains Region of Montana

    USGS Multimedia Gallery

    Agricultural fields and an abandoned farmstead in eastern Montana in the Great Plains region. The Great Plains region of the United States has experienced significant land-use change since European settlement, with vast swaths of grasslands converted to agricultural lands. Access to water, technolog...

  16. Regions associated with electron physics in asymmetric magnetic field reconnection

    E-print Network

    California at Berkeley, University of

    Regions associated with electron physics in asymmetric magnetic field reconnection F. S. Mozer1 it does for symmetric reconnection. Citation: Mozer, F. S., and P. L. Pritchett (2009), Regions associated properties have been used to search for this reconnection site [Vasyliunas, 1975; Mozer, 2005; Karimabadi et

  17. Fate and behavior of Benthiocarb--a herbicide in transplanted paddy under East-Indian climatic condition.

    PubMed

    Aktar, Md Wasim; Gupta, A; Gade, V; Bhattacharyya, Anjan

    2007-12-01

    A two season field experiment was conducted to study the magnitude of Benthiocarb residue in transplanted paddy field soil of plough layer (6''), beyond the plough layer (12'') as well as in harvested straw, grain and husk. Transplanted paddy fields were treated once with Benthiocarb (Saturn 50 EC) @1500 g.a.i., 2500 g.a.i. and 3000 g.a.i.ha(-1). Irrespective of any season, the initial deposits (4 h after spraying) of Benthiocarb in 6'' soil layer were found in varying range of 4.01-4.22 ppm, 5.98-6.56 ppm and 7.47-8.19 ppm at recommended (T(1)), intermediate (T(2)) and double the recommended doses (T(3)) respectively. In paddy field soil Benthiocarb residue dissipated 70% and 90% within 3 and 30 days respectively. Irrespective of any dose and season no residues were detected in 12'' soil layer as well as in straw, grain and husk samples at harvest. PMID:17999020

  18. Natural 15 N abundance of paddy rice ( Oryza sativa L.) grown with synthetic fertilizer, livestock manure compost, and hairy vetch

    Microsoft Academic Search

    Soek-In Yun; Sang-Sun Lim; Gwang-Sung Lee; Sang-Mo Lee; Han-Yong Kim; Hee-Myong Ro; Woo-Jung Choi

    Nitrogen isotope abundance (?\\u000a 15N) of paddy rice (Oryza sativa L.) grown for 110 days after transplanting (DAT) under field conditions with ammonium sulfate (AS with ?0.4‰ as a synthetic\\u000a fertilizer), pig manure compost (PMC with 15.3‰ as a livestock manure compost), and hairy vetch (HV with ?0.5‰ as a green\\u000a manure) was investigated to test the possible use of ?

  19. Computation of the Potential Magnetic Field in Solar Active Regions

    NASA Astrophysics Data System (ADS)

    Sadykov, V.; Zimovets, I.

    2014-10-01

    The Green's function solution of the Laplace equation for potential magnetic field in an external spherical region is found for special boundary conditions, namely, the derivatives of the potential along the selected direction. The set of programs which incorporates this solution to build potential magnetic field lines in solar active regions with the use of the photospheric line-of-sight field component is developed. The correctness of the method is testified with some model fields, and the optimal step size is found. 78 real solar active regions are analyzed and sets of potential magnetic field lines are calculated inside them with the use of the HMI/SDO and MDI/SOHO line-of-sight magnetograms as boundary conditions. The computed field lines are compared with flux tubes seen by the AIA/SDO and TRACE in the EUV range in each active region in an arbitrarily chosen time moment. It is found that the potential approximation is valid (applicable) only in 18 out of 78 cases, and thus is not very reliable. Also we try to find some correlations between applicability of the potential approximation for the selected regions and its McIntosh or Hale classes, and flare activity. No strong correlations are found.

  20. Effects of soil spatial resolution on quantifying CH4 and N2O emissions from rice fields in the Tai Lake region of China by DNDC model

    NASA Astrophysics Data System (ADS)

    Yu, D. S.; Yang, H.; Shi, X. Z.; Warner, E. D.; Zhang, L. M.; Zhao, Q. G.

    2011-06-01

    Fourteen grid data sets of different cell resolutions were generated, from 0.5 × 0.5 km to 64 × 64 km, to estimate CH4 and N2O emissions from paddy soils in the Tai Lake region of China using the Denitrification-Decomposition (DNDC) model. The grids were derived from a polygon-based data set (1:50,000 digital soil map/database), which was the most detailed soil database for the region. Comparison of simulated CH4 and N2O concentrations from input of the 14 grid data sets with the original polygon data demonstrated (1) no distinct variability (relative errors <5%) of the results when grid data sets of cell size ?2 km were used as input for the DNDC model; (2) slight variability (<10%) in the results when grid data sets with cell size in the range of 2 to 8 km were used as input; and (3) distinct variability (>10%) in the results when grid data sets with cell size of >8 km were applied as input. A grid data set with a cell size of 8 km was found to be optimal based on accuracy and computational efficiency of DNDC simulations. The results can be used as a guideline for optimizing field sampling strategies for locations where there is a lack of or insufficient soil data, whereby soil data can be collected through sampling in cell centers of designed grid frames.

  1. A paddy eco-ditch and wetland system to reduce non-point source pollution from rice-based production system while maintaining water use efficiency.

    PubMed

    Xiong, Yujiang; Peng, Shizhang; Luo, Yufeng; Xu, Junzeng; Yang, Shihong

    2015-03-01

    Non-point source (NPS) pollution from agricultural drainage has aroused widespread concerns throughout the world due to its contribution to eutrophication of water bodies. To remove nitrogen (N) and phosphorus (P) from agricultural drainage in situ, a Paddy Eco-ditch and Wetland System (PEDWS) was designed and built based on the characteristics of the irrigated rice district. A 2-year (2012-2013) field experiment was conducted to evaluate the performance of this system in Gaoyou Irrigation District in Eastern China. The results showed that the reduction in water input in paddy field of the PEDWS enabled the maintenance of high rice yield; it significantly increased irrigation water productivity (WPI), gross water productivity (WPG), and evapotranspiration water productivity (WPET) by 109.2, 67.1, and 17.6%, respectively. The PEDWS dramatically decreased N and P losses from paddy field. Compared with conventional irrigation and drainage system (CIDS), the amount of drainage water from PEDWS was significantly reduced by 56.2%, the total nitrogen (TN) concentration in drainage was reduced by 42.6%, and thus the TN and total phosphorus (TP) losses were reduced by 87.8 and 70.4%. PEDWS is technologically feasible and applicable to treat nutrient losses from paddy fields in situ and can be used in similar areas. PMID:25304242

  2. A statistical study of large-amplitude parallel electric fields in the upward current region of the auroral acceleration region

    E-print Network

    Scudder, Jack

    A statistical study of large-amplitude parallel electric fields in the upward current region electric fields Ek in the upward current region of the southern auroral acceleration zone, obtained-amplitude parallel electric fields in the upward current region of the auroral acceleration region, J. Geophys. Res

  3. Imazethapyr and imazapic, bispyribac-sodium and penoxsulam: zooplankton and dissipation in subtropical rice paddy water.

    PubMed

    Reimche, Geovane B; Machado, Sérgio L O; Oliveira, Maria Angélica; Zanella, Renato; Dressler, Valderi Luiz; Flores, Erico M M; Gonçalves, Fábio F; Donato, Filipe F; Nunes, Matheus A G

    2015-05-01

    Herbicides are very effective at eliminating weed and are largely used in rice paddy around the world, playing a fundamental role in maximizing yield. Therefore, considering the flooded environment of rice paddies, it is necessary to understand the side effects on non-target species. Field experiment studies were carried out during two rice growing seasons in order to address how the commonly-used herbicides imazethapyr and imazapic, bispyribac-sodium and penoxsulam, used at recommended dosage, affect water quality and the non-target zooplankton community using outdoor rice field microcosm set-up. The shortest (4.9 days) and longest (12.2 days) herbicide half-life mean, estimated of the dissipation rate (k) is shown for imazethapyr and bispyribac-sodium, respectively. Some water quality parameters (pH, conductivity, hardness, BOD5, boron, potassium, magnesium, phosphorus and chlorides) achieved slightly higher values at the herbicide treatment. Zooplankton community usually quickly recovered from the tested herbicide impact. Generally, herbicides led to an increase of cladocera, copepods and nauplius population, while rotifer population decreased, with recovery at the end of the experiment (88 days after herbicide treatment). PMID:25659307

  4. CATHOLIC THOUGHT AND CATHOLIC ACTION: DR PADDY RYAN MSC

    E-print Network

    Franklin, James

    , apologetics and controversy in the 1930s and early 1940s was almost a one-man show. The man was Father Paddy Ryan. If it was a question of attacking Communists, or replying to objections on radio, or debating, one contacted the Sacred Heart fathers at Kensington and got Father Ryan on the job. Born near Wodonga

  5. Seasonal mass balance of halogens in simulated rice paddies

    Microsoft Academic Search

    K. R. Redeker; S. L. Manley; L. Brothers; K. McDuffee; M. Walser; R. J. Cicerone

    2004-01-01

    Halogens released from soil reservoirs to the atmosphere play important roles in atmospheric chemistry, including ozone loss and aerosol formation. Closed system experiments to determine controlling factors in halogen movement between the pedosphere, hydrosphere, terrestrial biosphere, and atmosphere are needed. This paper presents results from a closed system experiment on simulated rice paddies. It was observed that most water-extractable (bioavailable),

  6. Evaluation of thermophilic fungal consortium for paddy straw composting.

    PubMed

    Kumar, Adesh; Gaind, Sunita; Nain, Lata

    2008-06-01

    Out of 10 thermophilic fungi isolated from wheat straw, farm yard manure, and soil, only three showed highest cellobiase, carboxymethyl cellulase, xylanase, and FPase activities. They were identified as Aspergillus nidulans (Th(4)), Scytalidium thermophilum (Th(5)), and Humicola sp. (Th(10)). A fungal consortium of these three fungi was used to compost a mixture (1:1) of silica rich paddy straw and lignin rich soybean trash. The composting of paddy straw for 3 months, during summer period in North India, resulted in a product with C:N ratio 9.5:1, available phosphorus 0.042% and fungal biomass 6.512 mg of N-acetyl glucosamine/100 mg of compost. However, a C:N ratio of 10.2:1 and highest humus content of 3.3% was achieved with 1:1 mixture of paddy straw and soybean trash. The fungal consortium was effective in converting high silica paddy straw into nutritionally rich compost thereby leading to economical and environment friendly disposal of this crop residue. PMID:17874191

  7. Mycoflora and trichothecene toxins of paddy grains from Egypt.

    PubMed

    Abdel-Hafez, S I; el-Kady, I A; Mazen, M B; el-Maghraby, O M

    1987-11-01

    120 species and 38 genera were collected from 64 samples of paddy grains on glucose- and cellulose-Czapek's agar at 28 degrees C. The total count of glycophilic and cellulose-decomposing fungi fluctuated between 216-29760; and 124-11320 colonies/g paddy grains on the two media, respectively. On glucose agar, the most common species were Aspergillus niger, A. flavus, A. sydowi, A. terreus, A. fumigatus, A. ochraceus, Penicillium chrysogenum, P. corylophilum, Fusarium oxysporum, Alternaria alternata, Cladosporium cladosporioides, Trichoderma viride and Mucor racemosus. On cellulose agar with pH 5.5 & 8.0, the most prevalent fungi were Stachybotrys chartarum, S. bisybi, Aspergillus niger, A. flavus, Fusarium oxysporum, Alternaria alternata, Drechslera sativus and Acremonium strictum. Extracts from 64 paddy samples were tested against brine shrimp larvae (Artemis salina). Of these 9 displayed varying degrees of toxicity. Trichothecene-toxins were detected in the extracts of three paddy samples only. Diacetoxyscirpenol and T-2 toxin were detected in two samples and only T-2 toxin in the other. PMID:3696188

  8. VECTOR MAGNETIC FIELDS OF A SOLAR POLAR REGION

    SciTech Connect

    Jin Chunlan; Wang Jingxiu, E-mail: cljin@nao.cas.cn, E-mail: wangjx@nao.cas.cn [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

    2011-05-01

    We study the vector magnetic fields of a solar polar region (PR) based on Solar Optical Telescope/Spectro-Polarimeter measurements. To better understand the polar magnetic properties, we compare the observed polar field with that in two solar quiet regions at the limb (QRL) and the disk center (QRD), and with that in a region of a low-latitude coronal hole (CHR). The following results are discussed: (1) The average vertical flux density of PR is 16 G, while the average horizontal flux density is 91 G. If we assume that the observed polar field suffers the same amount of limb weakening in polarization measurements as the Sun's quiet region, the average unsigned flux density in the pole would be 54 G, 60% stronger than that in the CHR. (2) The kG field in the PR occupies 6.7% of the region. The magnetic filling factor in the PR is characterized by a two-peak distribution, which appears at a field strength close to 100 G and 1000 G, respectively. (3) For the network elements, a correlation holds between the vertical and horizontal flux densities, suggesting the same physical entity is manifested by the observed stronger vertical and horizontal components. (4) The ratio of the magnetic flux in the minority polarity to that in the dominant polarity is approximately 0.5, implying that only 1/3 of the magnetic flux in the PR opens to the interplanetary space. Exemplified with CHR by a quasi-linear force-free extrapolation of the observed magnetic field, we find that the photospheric open flux is not always associated with strong vertical magnetic elements.

  9. Magnetic Field Modeling of Complex, Flare Productive Active Regions

    NASA Astrophysics Data System (ADS)

    Millholland, S. C.; Savcheva, A. S.; DeLuca, E. E.

    2014-12-01

    We present models and analysis of the magnetic field structure of three sigmoidal active regions (ARs). Sigmoids, forward or backward S-shaped EUV and X-ray emissions in the corona, are relevant as predictors of eruptive events such as flares and Coronal Mass Ejections. The regions were modeled using the Flux Rope Insertion Method, in which flux ropes, held in equilibrium by an overlying potential arcade, represent the sigmoids. The flux rope paths were inserted into a potential field following the filaments observed in 304Å. The models were then relaxed into a nonlinear force free (NLFFF) state using a magnetofrictional relaxation process. The first region studied is NOAA AR 12017, which produced an X1.0 flare at 2014/03/29 17:35. The second is NOAA AR 11283, which erupted with an X2.1 flare at 2011/09/06 22:12. For these regions, we show detailed comparisons of Quasi-Separatrix Layer (QSL) maps and observed flare ribbons. The slow evolution of an unstable solution at the time of the eruption produces a set of QSL solutions. Comparison of the photospheric mapping of the QSL with the flare ribbons will be a good measure of how well we have captured the magnetic structure of the particle acceleration region with our simple NLFFF models. The third is NOAA AR 11093. This region was a double decker filament composed of two branches over the same polarity inversion line. At 2010/08/07 17:55, the upper filament erupted with an M1.0 flare. This is the first time a double decker flux rope region has been modeled using these techniques. We show the interaction of the two inserted flux ropes and the evolution of the region through a series of NLFFF solutions to the evolving photospheric magnetic field. This work has been funded by the NSF-REU solar physics program at Smithsonian Astrophysical Observatory, grant number AGS-1263241.

  10. REGIONAL AIR POLLUTION STUDY: LAMBERT FIELD GRAPHICAL WEATHER SUMMARY

    EPA Science Inventory

    A graphical summary of National Weather Service (NWS) 3-hour weather observations from Lambert Field Airport, St. Louis, Missouri has been prepared for use by individuals involved in the analysis and application of Regional Air Pollution Study (RAPS) data. It is intended as a ref...

  11. ABRUPT LONGITUDINAL MAGNETIC FIELD CHANGES IN FLARING ACTIVE REGIONS

    SciTech Connect

    Petrie, G. J. D. [National Solar Observatory, 950 N. Cherry Avenue, Tucson, AZ 85719 (United States); Sudol, J. J. [West Chester University, West Chester, PA 19383 (United States)

    2010-12-01

    We characterize the changes in the longitudinal photospheric magnetic field during 38 X-class and 39 M-class flares within 65{sup 0} of disk center using 1 minute GONG magnetograms. In all 77 cases, we identify at least one site in the flaring active region where clear, permanent, stepwise field changes occurred. The median duration of the field changes was about 15 minutes and was approximately equal for X-class and for M-class flares. The absolute values of the field changes ranged from the detection limit of {approx}10 G to as high as {approx}450 G in two exceptional cases. The median value was 69 G. Field changes were significantly stronger for X-class than for M-class flares and for limb flares than for disk-center flares. Longitudinal field changes less than 100 G tended to decrease longitudinal field strengths, both close to disk center and close to the limb, while field changes greater than 100 G showed no such pattern. Likewise, longitudinal flux strengths tended to decrease during flares. Flux changes, particularly net flux changes near disk center, correlated better than local field changes with GOES peak X-ray flux. The strongest longitudinal field and flux changes occurred in flares observed close to the limb. We estimate the change of Lorentz force associated with each flare and find that this is large enough in some cases to power seismic waves. We find that longitudinal field decreases would likely outnumber increases at all parts of the solar disk within 65{sup 0} of disk center, as in our observations, if photospheric field tilts increase during flares as predicted by Hudson et al.

  12. Abrupt longitudinal magnetic field changes in flaring active regions

    E-print Network

    Petrie, G J D

    2010-01-01

    We characterize the changes in the longitudinal photospheric magnetic field during 38 X-class and 39 M-class flares within $65^{\\circ}$ of disk-center using 1-minute GONG magnetograms. In all 77 cases we identify at least one site in the flaring active region where clear, permanent, stepwise field changes occurred. The median duration of the field changes was about 15 minutes and was approximately equal for X-class and for M-class flares. The absolute values of the field changes ranged from the detection limit of $\\sim\\!\\!10$~G to as high as $\\sim\\!\\!450$~G in two exceptional cases. The median value was 69~G. Field changes were significantly stronger for X-class than for M-class flares and for limb flares than for disk-center flares. Longitudinal field changes less than 100~G tended to decrease longitudinal field strengths, both close to disk-center and close to the limb, while field changes greater than 100~G showed no such pattern. Likewise, longitudinal flux strengths tended to decrease during flares. Flux...

  13. Chromospheric magnetic fields of an active region filament

    NASA Astrophysics Data System (ADS)

    Xu, Z.; Solanki, S.; Lagg, A.

    2012-06-01

    Vector magnetic fields of an active region filament are co-spatially and co-temporally mapped in photosphere and upper chromosphere, by using spectro-polarimetric observations made by Tenerife Infrared Polarimeter (TIP II) at the German Vacuum Tower Telescope (VTT). A Zeeman-based ME inversion is performed on the full Stokes vectors of both the photospheric Si I 1082.7 nm and the chromospheric He I 1083.0 nm lines. We found that the strong magnetic fields, with the field strength of 600 - 800 G in the He I line formation height, are not uncommon among AR filaments. But such strong magnetic field is not always found in AR filaments.

  14. Chiral Effective Field Theory in the $\\Delta$-resonance region

    SciTech Connect

    Vladimir Pascalutsa

    2006-09-18

    I discuss the problem of constructing an effective low-energy theory in the vicinity of a resonance or a bound state. The focus is on the example of the $\\Delta(1232)$, the lightest resonance in the nucleon sector. Recent developments of the chiral effective-field theory in the $\\Delta$-resonance region are briefly reviewed. I conclude with a comment on the merits of the manifestly covariant formulation of chiral EFT in the baryon sector.

  15. Dynamic nuclear polarization in the hyperfine-field-dominant region.

    PubMed

    Lee, Seong-Joo; Shim, Jeong Hyun; Kim, Kiwoong; Yu, Kwon Kyu; Hwang, Seong-Min

    2015-06-01

    Dynamic nuclear polarization (DNP) allows measuring enhanced nuclear magnetic resonance (NMR) signals. Though the efficiency of DNP has been known to increase at low fields, the usefulness of DNP has not been throughly investigated yet. Here, using a superconducting quantum interference device-based NMR system, we performed a series of DNP experiments with a nitroxide radical and measured DNP spectra at several magnetic fields down to sub-microtesla. In the DNP spectra, the large overlap of two peaks having opposite signs results in net enhancement factors, which are significantly lower than theoretical expectations [30] and nearly invariant with respect to magnetic fields below the Earth's field. The numerical analysis based on the radical's Hamiltonian provides qualitative explanations of such features. The net enhancement factor reached 325 at maximum experimentally, but our analysis reveals that the local enhancement factor at the center of the rf coil is 575, which is unaffected by detection schemes. We conclude that DNP in the hyperfine-field-dominant region yields sufficiently enhanced NMR signals at magnetic fields above 1?T. PMID:25955437

  16. Dynamic nuclear polarization in the hyperfine-field-dominant region

    NASA Astrophysics Data System (ADS)

    Lee, Seong-Joo; Shim, Jeong Hyun; Kim, Kiwoong; Yu, Kwon Kyu; Hwang, Seong-min

    2015-06-01

    Dynamic nuclear polarization (DNP) allows measuring enhanced nuclear magnetic resonance (NMR) signals. Though the efficiency of DNP has been known to increase at low fields, the usefulness of DNP has not been throughly investigated yet. Here, using a superconducting quantum interference device-based NMR system, we performed a series of DNP experiments with a nitroxide radical and measured DNP spectra at several magnetic fields down to sub-microtesla. In the DNP spectra, the large overlap of two peaks having opposite signs results in net enhancement factors, which are significantly lower than theoretical expectations [30] and nearly invariant with respect to magnetic fields below the Earth's field. The numerical analysis based on the radical's Hamiltonian provides qualitative explanations of such features. The net enhancement factor reached 325 at maximum experimentally, but our analysis reveals that the local enhancement factor at the center of the rf coil is 575, which is unaffected by detection schemes. We conclude that DNP in the hyperfine-field-dominant region yields sufficiently enhanced NMR signals at magnetic fields above 1 ? T.

  17. Seasonal Variation of Methane Flux From a California Rice Paddy

    Microsoft Academic Search

    R. J. Cicerone; J. D. Shetter; C. C. Delwiche

    1983-01-01

    To allow increased understanding of the global budget of atmospheric methane, individual methane sources require investigation. We have measured methane emissions from a California rice paddy during the entire 1982 growing season. A very strong seasonal dependence was observed. Methane emissions were highest in the last 2-3 weeks before harvest; daily emissions reached 5 g CH,\\/m 2. Over the 100-day

  18. Effect of water and heat transport processes on methane emissions from paddy soils: a process-based model analysis

    NASA Astrophysics Data System (ADS)

    Rizzo, Anacleto; Boano, Fulvio; Revelli, Roberto; Ridolfi, Luca

    2013-04-01

    High CH4 fluxes are emitted from paddy fields worldwide and represent a considerable issue for the rice production eco-sustainability. Water and heat transport fluxes are known to strongly influence biogeochemical cycles in wetland environments, and therefore also CH4 emissions from paddy soils. Water percolation affects the dynamics of many compounds (e.g. DOC, O2) influencing CH4 fate. On the other hand, heat fluxes strongly influence CH4 production in submerged rice crops, and lowering ponding water temperature (LPWT) can reduce microbial activities and consequently decrease CH4 emissions. Moreover, as long as the optimal temperature range for rice growth is maintained, LPWT can lower CH4 emissions without rice yield limitation. Hence, a process-based model is proposed and applied to investigate the role of water flow on CH4 emissions, and to analyse the efficiency of LPWT as mitigation strategy for CH4 production and release. The process-based model relies on a system of partial differential mass balance equations to describe the vertical dynamics of the chemical compounds leading to CH4 production. Many physico-chemical processes and features characteristic of paddy soil are included: paddy soil stratigraphy; spatio-temporal variations of plant-root compartment; water and heat transport; SOC decomposition; heterotrophic reactions in both aerobic and anaerobic conditions; root radial oxygen loss; root solute uptake; DOC root exudation; plant-mediated, ebullition, and diffusion gas exchange pathways. LPWT is included as a temperature shift subtracted directly to the ponding water temperature. Model results confirm the importance of water flow on CH4 emission, since simulations that do not include water fluxes show a considerable overestimation of CH4 emissions due to a different DOC spatio-temporal dynamics. Particularly, when water fluxes are not modeled the overestimation can reach 67 % of the total CH4 emission over the whole growing season. Moreover, model results also suggest that roots influence CH4 dynamics principally due to their solute uptake, while root effect on advective flow plays a minor role. In addition, the analysis of CH4 transport fluxes show the limiting effect of upward dispersive transport fluxes on the downward CH4 percolation. Finally, LPWT is confirmed to be a valid mitigation strategy for CH4 emissions from paddy soils, since the reduction of CH4 emission reach about -50 % with a LPWT equal to only 2°C over the whole growing season.

  19. Magnetic fields in star-forming regions - Observations

    NASA Technical Reports Server (NTRS)

    Heiles, Carl; Goodman, Alyssa A.; Mckee, Christopher F.; Zweibel, Ellen G.

    1993-01-01

    We review the observational aspects of magnetic fields in dense, star-forming regions. First we discuss ways to observe the field. These include direct methods, which consist of the measurement of both linear and circular polarization of spectral line and continuum radiation; and indirect methods, consisting of the angular distribution of H2O masers on the sky and the measurement of ambipolar diffusion. Next we discuss selected observational results, focusing on detailed discussions of a small number of points rather than a generalized discussion that covers the waterfront. We discuss the Orion/BN-KL region in detail, both on the small and large scales. Next we discuss the derivation of the complete magnetic vector, including both the systematic and fluctuating component, from a large sample of Zeeman and linear polarization measurements for the L204 dark cloud. We examine the virial theorem as it applies to dark clouds in general and one dark cloud, Barnard 1, in particular. We critically discuss the numerous claims for alignment of cloud structural features with the plane-of-the-sky component of the magnetic field, and find that many of these have not been definitively established.

  20. Effects of Copper Availability on Methanotroph Growth and Activity in Rice Paddy Soil

    NASA Astrophysics Data System (ADS)

    Macalady, J.; Scow, K. M.

    2001-12-01

    Methanotrophs (aerobic, obligate methane-oxidizing bacteria) represent the largest sink for methane in the terrestrial environment, oxidizing a significant fraction of methane produced in anoxic regions of flooded soils and sediments before it reaches the atmosphere. Two unrelated methane monooxygenase (MMO) enzymes observed in methanotrophs have different kinetics, and have isotope fractionation effects for methane C which vary by about 12 per mil. Expression of the two enzymes in methanotroph cell cultures is controlled by copper, leading to the hypothesis that copper availability in soils could influence methane isotope fractionation in wetlands and rice paddies. Soil incubations using added copper chelate indicate that methanotroph growth and methane oxidation rates in a California rice soil are not limited by copper. Copper to methanotroph biomass ratios were in the range predicted for the expression of the particulate form of MMO (pMMO), the enzyme associated with the larger isotope fractionation factor (approx. -25 per mil).

  1. Fine structure of the magnetic field in active regions

    NASA Astrophysics Data System (ADS)

    Pustilnik, Lev; Beskrovnaya, Nina; Ikhsanov, Nazar

    High-resolution observations with SOHO, SDO, TRACE, HINODE suggest that the solar magnetic field in active regions has a complicated fine structure. There is a large number of thin magnetic arcs extended from the photosphere to corona with almost constant cross-section. We explore a possibility to model the complex of interacting arcs in terms of a dynamical percolating network. A transition of the system into flaring can be triggered by the flute instability of prominences and/or coronal condensations. We speculate around an assumption that the energy release in active regions is governed by the same scenario as dynamical current percolation through a random resistors network in which the saltatory conduction is controlled by a local current level.

  2. Plasma Equilibrium in a Magnetic Field with Stochastic Regions

    SciTech Connect

    J.A. Krommes and Allan H. Reiman

    2009-04-23

    The nature of plasma equilibrium in a magnetic field with stochastic regions is examined. It is shown that the magnetic differential equation that determines the equilibrium Pfirsch-Schluter currents can be cast in a form similar to various nonlinear equations for a turbulent plasma, allowing application of the mathematical methods of statistical turbulence theory. An analytically tractable model, previously studied in the context of resonance-broadening theory, is applied with particular attention paid to the periodicity constraints required in toroidal configurations. It is shown that even a very weak radial diffusion of the magnetic field lines can have a significant effect on the equilibrium in the neighborhood of the rational surfaces, strongly modifying the near-resonant Pfirsch-Schluter currents. Implications for the numerical calculation of 3D equilibria are discussed

  3. [Quantitative characteristics and source analysis of heavy metals in paddy soils in downstream of the Second Songhua River, Jilin Province].

    PubMed

    Zhu, Li-lu; Yan, Bai-xing; Wang, Li-xia

    2010-11-01

    In autumn 2008, a total of 65 plough layer soil samples were collected from the paddy fields in Qianguo Irrigation Area located at the downstream of the Second Songhua River. These paddy fields were irrigated with water from the River, and had different irrigation histories. The Cu, Pb, Zn, Cd, Ni, As, and Hg concentrations in the soil samples were determined, and the accumulation characteristics, input approaches, and pollution sources of these heavy metals were analyzed. The Cu, Pb, Zn, Cd, Ni, As, and Hg concentrations in the samples were 14.1-28.4 mg x kg(-1), 37.6-57.4 mg x kg(-1), 53.3-84.4 mg x kg(-1), 0.044-0.367 mg x kg(-1), 18.4-37.0 mg x kg(-1), 3.25-12.11 mg x kg(-1), and 0.031-0.155 mg x kg(-1), respectively. The Pb, Hg, and Cd exhibited an obvious accumulation trend, with their concentrations being 100.0%, 38.7%, and 66.1% higher than the baselines, respectively, while Cu, Zn, Ni, and As had less accumulation. With the increase of irrigation history, the Pb concentration showed a decreasing trend, while the Hg concentration was in reverse. There was no significant correlation between the Cd concentration and the irrigation history. According to source analysis, soil Pb mainly originated from the atmospheric Pb deposition via historical use of leaded gasoline, soil Hg was from the polluted irrigation water from the Second Songhua River, and soil Cd was from the use of chemical fertilizers, pesticides, and other agrochemicals. Though the Pb, Hg, and Cd had obviously accumulated in the paddy fields in Qianguo Irrigation Area, their potential ecological risk was still low, and would not pose threat on the local agricultural production and food security. PMID:21361025

  4. Two-field high-scale inflation in a sub-Planckian region of field space

    SciTech Connect

    Berg, Marcus [Oskar Klein Center for Cosmoparticle Physics and Department of Physics, Stockholm University, Albanova University Center, SE-106 91 Stockholm (Sweden); Pajer, Enrico [Institute for High Energy Phenomenology, Newman Laboratory of Elementary Particle Physics, Cornell University, Ithaca, New York 14853 (United States); Sjoers, Stefan [Oskar Klein Center for Cosmoparticle Physics and Department of Physics, Stockholm University, Albanova University Center, SE-106 91 Stockholm (Sweden); Institute for High Energy Phenomenology, Newman Laboratory of Elementary Particle Physics, Cornell University, Ithaca, New York 14853 (United States)

    2010-05-15

    We present a simple two-field model of inflation and show how to embed it in string theory as a straightforward generalization of axion monodromy models. Phenomenologically, the predictions are equivalent to those of chaotic inflation, and, in particular, include observably large tensor modes. The whole high-scale large-field inflationary dynamics takes place within a region of field space that is parametrically sub-Planckian in diameter, hence improving our ability to control quantum corrections and achieve slow-roll inflation.

  5. The influence of paddy soil bacterial diversity affected by heavy metals contamination of Dabaoshan Mine

    Microsoft Academic Search

    Kaizhi Xie; Peizhi Xu; Shaohai Yang; Shuanhu Tang; Fabao Zhang; Xu Huang; Wenjie Gu; Hui Zhang

    2011-01-01

    We studied the paddy soil affected by acid drainage of Dabaoshan polymetallic ore in north Guangdong. Using real -time PCR and PCR-DGGE technique, we explored the influence of the soil bacterial community diversity at different degrees of heavy metals contamination of heavy metal and available content. The results showed that: the number of bacteria, paddy soil bacteria diversity, Shannon-Wiener index

  6. Impact of irrigating rice paddies with groundwater containing arsenic in Bangladesh

    E-print Network

    van Geen, Alexander

    Impact of irrigating rice paddies with groundwater containing arsenic in Bangladesh A. van Geen a with little arsenic is used for irrigation, or during the dry season (January­May), when groundwater elevated in arsenic is used instead. In the upper 5 cm of paddy soil, accumulation of 13±12 mg/kg acid-leachable As (n

  7. ESTIMATION OF KOREAN PADDY FIELD SOIL PROPERTIES USING OPTICAL REFLECTANCE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An optical sensing approach based on diffuse reflectance has shown potential for rapid and reliable on-site estimation of soil properties. Important sensing ranges and the resulting regression models useful for soil property estimation have been reported. In this study, a similar approach was applie...

  8. Parallel electric fields in the upward current region of the aurora: Indirect and direct observations

    E-print Network

    California at Berkeley, University of

    Parallel electric fields in the upward current region of the aurora: Indirect and direct current region of the aurora focusing on the structure of electric fields at the boundary between account of the electric fields in the upward current region of the aurora as observed by the Fast Auroral

  9. Generation and Suppression of E Region Artificial Field Aligned Irregularities

    NASA Astrophysics Data System (ADS)

    Miceli, R. J.; Hysell, D. L.; Munk, J.; Han, S.

    2012-12-01

    Artificial field-aligned plasma density irregularities (FAIs) were generated in the E region of the ionosphere above the High Frequency Active Auroral Research Program (HAARP) facility during campaigns in May and August of 2012 and were quantified using a 30 MHz coherent scatter radar in Homer, Alaska. The purpose of the experiment was to analyze the X-mode suppression of FAIs generated from O-mode heating and to measure the threshold required to excite thermal parametric instabilities. The irregularities were excited by gradually increasing the power of a zenith pointing O-mode emission transmitted at a frequency of 2.75 MHz. To suppress the irregularities, a second X-mode emission at a higher frequency was added on alternating power cycles. The Homer radar measured the signal-to-noise ratio, Doppler shift, and spectral width of echoes reflected from the irregularities. We will calculate the threshold electric field required to excite the irregularities and compare with similar experiments in order to better understand the thermal parametric instability.

  10. Regional TEC mapping with Random Field Priors and Kriging

    NASA Astrophysics Data System (ADS)

    Sayin, I.; Arikan, F.; Arikan, O.

    2008-10-01

    Total Electron Content (TEC) is an important parameter in monitoring ionospheric variability. In a given region, TEC can be obtained only by interpolation of measurements due to sparsity of the useful data. The lack of a complete ionospheric model hinders the choice of the optimum interpolation algorithm. A plausible solution to this problem can be found by investigating the performance of alternative interpolation algorithms on synthetically generated TEC surfaces for various sampling scenarios. The synthetic TEC data should represent the possible trends and variations of ionosphere. In this study, the performance of Random Field Priors (RFP) and Kriging interpolation algorithms are investigated over the parameter set of spatially correlated synthetic TEC data for various variance, range and trend options. Synthetic TEC data are sampled with regular and random sampling patterns, for number of samples from sparse to dense samplings. Interpolation scenarios are generated to investigate the improvement of the interpolation accuracy of the methods for each parameter. It is observed that for the random sampling patterns, when the trend is not modeled correctly, the errors of the algorithms increase and when the trend is modeled correctly, the reconstruction errors decrease. For the regular sampling patterns, the trend model does not affect the accuracy of the methods, and the reconstruction errors are close to lower bound error values. An example reconstruction is also provided over GPS-derived TEC, and error variances are compared over Kriging and Random Field Prior algorithms.

  11. Assessment of soil biological quality index (QBS-ar) in different crop rotation systems in paddy soils

    NASA Astrophysics Data System (ADS)

    Nadimi-Goki, Mandana; Bini, Claudio; haefele, Stephan

    2013-04-01

    New methods, based on soil microarthropods for soil quality evaluation have been proposed by some Authors. Soil microarthropods demonstrated to respond sensitively to land management practices and to be correlated with beneficial soil functions. QBS Index (QBS-ar) is calculated on the basis of microarthropod groups present in a soil sample. Each biological form found in the sample receives a score from 1 to 20 (eco-morphological index, EMI), according to its adaptation to soil environment. The objective of this study was to evaluate the effect of various rotation systems and sampling periods on soil biological quality index, in paddy soils. For the purpose of this study surface soil samples (0-15 cm depth) were collected from different rotation systems (rice-rice-rice, soya-rice-rice, fallow-rice and pea-soya-rice) with three replications, and four sampling times in April (after field preparation), June (after seedling), August (after tillering stage) and October (after rice harvesting). The study area is located in paddy soils of Verona area, Northern Italy. Soil microarthropods from a total of 48 samples were extracted and classified according to the Biological Quality of Soil Index (QBS-ar) method. In addition soil moisture, Cumulative Soil Respiration and pH were measured in each site. More diversity of microarthropod groups was found in June and August sampling times. T-test results between different rotations did not show significant differences while the mean difference between rotation and different sampling times is statistically different. The highest QBS-ar value was found in the fallow-rice rotation in the forth soil sampling time. Similar value was found in soya-rice-rice rotation. Result of linear regression analysis indicated that there is significant correlation between QBS-ar values and Cumulative Soil Respiration. Keywords: soil biological quality index (QBS-ar), Crop Rotation System, paddy soils, Italy

  12. Origin and geometry of upward parallel electric fields in the auroral acceleration region

    Microsoft Academic Search

    F. S. Mozer; A. Hull

    2001-01-01

    Electric fields, magnetic fields, and plasmas measured on the Polar satellite are studied to determine the altitude extent of the upward field-aligned current portion of the auroral acceleration region and the physical processes that populate it with parallel electric fields. This region extends upward to a geocentric altitude of 3 or 3.5 Earth radii at premidnight local times during the

  13. Regional Stress Field in the Maghreb Region From an Updated Focal Mechanism Catalog (1954-2014)

    NASA Astrophysics Data System (ADS)

    Lamara, Samir; Friederich, Wolfgang

    2015-04-01

    In order to investigate the regional stress field in the Maghreb region we construct a focal mechanism catalog for earthquakes that occurred from 1954 to 2014. To this intent, all available moment tensor solutions of past earthquakes obtained from different sources were checked, compared and corrected. Furthermore, the focal solutions of all recent earthquakes with magnitude down to 4 and for which data is available were calculated using a new method based on waveform fitting of observed seismograms and synthetics calculated for a range of fault angles and hypocenter depths. Observed seismograms of all stations for a given earthquake were thus collected, processed and subject to a rigorous quality control according to the corresponding signal-to-noise ratio. An average 1-D earth model for the Maghreb-western Mediterranean region was also constructed to calculate synthetics. The misfits between these observed seismograms and a set of synthetics calculated for every value of fault angles (strike, dip and rake) and hypocenter depths were calculated after respectively, a phase fitting obtained by shifting the seismograms to the best cross-correlation between data and synthetics, and amplitudes scaling. The best configuration of fault angles and hypocenter depths was then selected according to the smallest average misfit over all stations. If a systematic time shift was noticeable for all stations or most of them, an additional relocation step was done to obtain the most accurate earthquake's epicenter. Most of the earthquakes included in the catalog define several spatial clusters for which the assumption of homogeneous stress can be fulfilled. Hence, a stress inversion for each cluster was performed and a stress ratio indicating the dominance of compressional or tensional stresses as well as the directions and dips of the tensional, intermediate and compressional axis were obtained.

  14. Study on paddy rice planting area and yield monitoring based on MODIS: a case study of the Jianghan Plain

    NASA Astrophysics Data System (ADS)

    Mei, Xin; Liu, Hai

    2008-12-01

    The paddy rice is humanity's important crop. Jianghan plain is the important paddy rice planting area in China. However, comparing with others, the study of paddy rice remote sensing is less in there. This study takes the MODIS data from 2001 to 2007 as the main data resources, combines with the land use data, depends on the kind of paddy rice growing periods, and extracts the paddy rice planting area. According to the test, the accuracy surpasses 85%. It attained each various time average NDVI, EVI value by the each year various times paddy rice NDVI, EVI. Then this study takes the grey system theory as a new method, and introduces it to the paddy rice remote sensing monitoring. Taking the paddy rice yield per unit area as the referenced sequence and the each year various times paddy rice NDVI, EVI as the comparative sequence, calculating the gray correction degree, finally the study selects the best time to remote sensing monitoring for the paddy rice yield, and makes the yield estimation model.

  15. Effects of Different Application Methods of Methane Fermentation Digested Liquid into the Paddy Plot on Soil Nitrogen Behavior and Rice Yield

    NASA Astrophysics Data System (ADS)

    Watanabe, Satoko; Nakamura, Kimihito; Seok Ryu, Chan; Iida, Michihisa; Kawashima, Shigeto

    Methane fermentation technique with the treatment of animal waste and food waste is drawing public attention as a good option for the utilization of biomass resources and it is investigated how to apply the by-product of fermentation (methane fermentation digested liquid) to agricultural fields as a fertilizer. It is important to determine an adequate method of applying digested liquid to a paddy plot as fertilizer taking into account the concentrations of soil nitrogen components and rice yield. The objective of this study is to compare the performances of three methods of applying digested liquid to paddy plots in terms of the nitrogen transformation in soil, rice yield, and nitrogen load in effluent. The three methods were pouring (with irrigation water), spreading onto the surface of a plot, and injection into paddy soil. It was found that the ammonium nitrogen concentration and the dissolved organic nitrogen concentration in soil of the spreading plot were higher than that for the pouring plot and that for the injecting plot. The rice yield was higher in the spreading plot than in the injecting and pouring plots. And, there was a significant correlation between the rice yield and the dissolved organic nitrogen just before and after the panicle initiation stage. There were no differences in the nitrogen effluent loads with surface drainage.

  16. Wide Field Imaging of the Hubble Deep Field-South Region III: Catalog

    NASA Technical Reports Server (NTRS)

    Palunas, Povilas; Collins, Nicholas R.; Gardner, Jonathan P.; Hill, Robert S.; Malumuth, Eliot M.; Rhodes, Jason; Teplitz, Harry I.; Woodgate, Bruce E.

    2002-01-01

    We present 1/2 square degree uBVRI imaging around the Hubble Deep Field - South. These data have been used in earlier papers to examine the QSO population and the evolution of the correlation function in the region around the HDF-S. The images were obtained with the Big Throughput Camera at CTIO in September 1998. The images reach 5 sigma limits of u approx. 24.4, B approx. 25.6, V approx. 25.3, R approx. 24.9 and I approx. 23.9. We present a catalog of approx. 22,000 galaxies. We also present number-magnitude counts and a comparison with other observations of the same field. The data presented here are available over the world wide web.

  17. Large parallel electric fields in the upward current region of the aurora: Evidence for ambipolar effects

    E-print Network

    Scudder, Jack

    Large parallel electric fields in the upward current region of the aurora: Evidence for ambipolarV/m) measured by the electric field instrument on Polar in the upward current part of the auroral acceleration. Scudder, and C. C. Chaston, Large parallel electric fields in the upward current region of the aurora

  18. Magnetic fields in massive star-forming regions and the magnetic structure of the Milky Way

    Microsoft Academic Search

    Vincent Louis Fish

    2004-01-01

    We have observed hydroxyl masers in 15 massive star- forming regions using full-polarization VLBL Magnetic fields deduced from Zeeman pairs imply ordered fields, although unknown maser physics and evidence for Faraday rotation make full three-dimensional field reconstruction impossible. Maser clustering on 1015 cm scales suggest that some hydroxyl masers form in the region between the ionization and shock fronts around

  19. Magnetic field visualization of magnetic minerals and grain boundary regions using magneto-optical imaging

    E-print Network

    Podladchikov, Yuri

    Magnetic field visualization of magnetic minerals and grain boundary regions using magneto field visualization of magnetic minerals and grain boundary regions using magneto-optical imaging, J technique since the gray level on the images can be directly mapped to the local value of magnetic field

  20. Heavy Metal Pollution Enhances Soil Respiration and Reduces Carbon Storage in a Chinese Paddy Soil

    NASA Astrophysics Data System (ADS)

    Pan, Genxing; Li, Zhipeng; Liu, Yongzhuo; Smith, Pete; Crowley, David; Zheng, Jufeng

    2010-05-01

    China's paddy soils are crucial both for food security through high cereal productivity, and for climate mitigation through high soil carbon storage. These functions are increasingly threatened by widespread heavy metal pollution, resulting from rapid industrial development. Heavy metal-polluted soils generally have a reduced microbial biomass and reduced soil respiration, as well as reduced functional diversity through changes in microbial community structure. Here we show that heavy metal pollution enhances soil respiration and CO2 efflux from a Chinese rice paddy soil, and leads to a soil organic carbon (SOC) loss, which is correlated with a decline in the fungal-to-bacterial ratio of the reduced soil microbial community. The pollution-induced SOC loss could offset 70% of the yearly SOC increase from China's paddy soils. Thus, heavy metal pollution impacts long term productivity and the potential for C sequestration in China's paddy soils.

  1. Regional Ecorisk Field investigation, upper Clark Fork River Basin

    SciTech Connect

    Pastorok, R.; LaTier, A.; Ginn, T. [PTI Environmental Services, Bellevue, WA (United States)

    1995-12-31

    The Regional Ecorisk Field Investigation was conducted at the Clark Fork River Superfund Site (Montana) to evaluate the relationships between plant communities and tailings deposits in riparian habitats and to evaluate food-chain transfer of trace elements to selected wildlife species. Stations were selected to represent a range of vegetation biomass (or cover) values and apparent impact of trace elements, with some areas of lush vegetation, some areas of mostly unvegetated soil (e.g., < 30 percent plant cover), and a gradient in between. For the evaluation of risk to wildlife, bioaccumulation of metals was evaluated in native or naturalized plants, terrestrial invertebrates, and the deer mouse (Peromyscus maniculatus). Potential reproductive effects in the deer mouse were evaluated by direct measurements. For other wildlife species, bioaccumulation data were interpreted in the context of food web exposure models. Total biomass and species richness of riparian plant communities are related to tailings content of soil as indicated by pH and metals concentrations. Risk to populations of omnivorous small mammals such as the deer mouse was not significant. Relative abundance and reproductive condition of the deer mouse were normal, even in areas of high metals enrichment. Based on exposure models and site-specific tissue residue data for dietary species, risk to local populations of predators such as red fox and American kestrel that feed on deer mice and terrestrial invertebrates is not significant. Risk to herbivores related to metals bioaccumulation in plant tissues is not significant. Population level effects in deer and other large wildlife are not expected because of the large home ranges of such species and compensatory demographic factors.

  2. Effects of biochar addition on N 2 O and CO 2 emissions from two paddy soils

    Microsoft Academic Search

    Jinyang Wang; Man Zhang; Zhengqin Xiong; Pingli Liu; Genxing Pan

    Impacts of biochar addition on nitrous oxide (N2O) and carbon dioxide (CO2) emissions from paddy soils are not well documented. Here, we have hypothesized that N2O emissions from paddy soils could be depressed by biochar incorporation during the upland crop season without any effect\\u000a on CO2 emissions. Therefore, we have carried out the 60-day aerobic incubation experiment to investigate the

  3. ????????????????????????????????????????????????????????????????????????????????????????? ???????????? DRYING KINETICS MODEL OF PADDY DEHYDRATION USING AGRICULTURAL RESIDUES AND SILICA GEL ???????? ?????,1* ?????? ?????????????,2 ??? ??????? ?????????????3

    Microsoft Academic Search

    Yuttana Tirawanichakul; Supawan Tirawanichakul

    The aim of this work was to improve the mathematical model of paddy dehydration by adsorption technique utilizing agricultural residues, i.e. rice husk, sago palm rachis and coconut husk, and silica gel. The experiments show that the suitable volumetric mixing ratios of paddy to adsorbent are 1.0:1.5 and 1.0:1.0 for agricultural residue and silica gel adsorbents respectively. The coconut and

  4. Methane Emissions From Global Paddy Rice Agriculture - a New Estimate Based on DNDC Model Simulations

    NASA Astrophysics Data System (ADS)

    Hagen, S. C.; Li, C.; Salas, W.; Ingraham, P.; Li, J.; Beach, R.; Frolking, S.

    2012-12-01

    Roughly one-quarter of global methane emissions to the atmosphere come from the agricultural sector. Agricultural emissions are dominated by livestock (ruminants) and paddy-rice agriculture. We report on a new estimate of global methane emissions from paddy rice c.2010, based on DNDC model simulations of rice cropping around the world. We first generated a global map of rice cropping at 0.5°-resolution, based on existing global crop maps and various other published data. For each 0.5° grid cell that has rice agriculture, we simulated all rice cropping systems that our mapping indicated to be occurring there - irrigated and/or rainfed; single-rice, double-rice, triple-rice, and/or rice-rotated with other upland crops - under local climate and soil conditions, with assumptions about crop management (e.g., fertilizer type and amount, irrigation, flooding frequency and duration, manure application, tillage, crop residue management). We estimate global paddy rice emissions at 23 Tg CH4/yr from 120 Mha of rice paddies (land area) and 160 Mha of rice cropping (harvested area) for the baseline management scenario. We also report on the spatial distribution of these emissions, and the impacts of various management alternatives (flooding methods, fertilizer types, crop residue incorporation etc.) on yield, soil carbon sequestration and emissions of methane and nitrous oxide. For example, simulations with continuous flooding on all paddies increased simulated global paddy rice emissions to 33 Tg CH4/yr, while simulations where all fertilizer was applied as ammonium sulfate reduced simulated global paddy rice emissions to about 19 Tg CH4/yr. Simulated global paddy rice yield was about 320 Tg C in grain.

  5. A spatial aggregation index for effective fallow decision in paddy irrigation demand planning

    Microsoft Academic Search

    Ming-Daw Su; Mei-Chun Lin; Chun-Hung Lin; Shih-Fu Wang; Tzai-Hung Wen; Hsin-I Hsieh

    As irrigation demands usually take the largest share of water supply, paddy fallow is considered as a drought relieving measure\\u000a in some Asian paddy growing countries by transferring the water saved to the municipal and industrial sectors. But the relationship\\u000a between fallow area and irrigation demand reduction is not necessarily linear, there may be more than dozens combinations\\u000a of fallow

  6. Seasonal mass balance of halogens in simulated rice paddies

    NASA Astrophysics Data System (ADS)

    Redeker, K. R.; Manley, S. L.; Brothers, L.; McDuffee, K.; Walser, M.; Cicerone, R. J.

    2004-06-01

    Halogens released from soil reservoirs to the atmosphere play important roles in atmospheric chemistry, including ozone loss and aerosol formation. Closed system experiments to determine controlling factors in halogen movement between the pedosphere, hydrosphere, terrestrial biosphere, and atmosphere are needed. This paper presents results from a closed system experiment on simulated rice paddies. It was observed that most water-extractable (bioavailable), halogens were swept downward from the surface during the initial watering pulse (~50, 70, and 75% of chloride, bromide, and iodide in unadulterated soils). Soil halogens were sequestered by rice plants with 28, 4, and 24% of the remaining bioavailable chlorine, bromine, and iodine processed by the plant tissue by the end of the season. Of the bioavailable halogens taken into the rice plant, less than 1% of chlorine or bromine is volatilized as a methyl halide while over 90% of iodide is emitted as gaseous CH3I.

  7. Microscopic Structural Changes in Paddy Straw Pretreated with Trichoderma reesei MTCC 164 and Coriolus versicolor MTCC 138.

    PubMed

    Phutela, Urmila Gupta; Sahni, Nidhi

    2013-06-01

    The present study reports the pretreatment of paddy straw by Trichoderma reesei MTCC 164 and Coriolus versicolor MTCC 138 to observe the changes in chemical composition and its correlation with change of surface structure, morphology and porosity of paddy straw. Compared with untreated straw, cellulose decreased by 15.9 and 19.3 % in T. reesei MTCC 164 and C. versicolor MTCC 138 pretreated paddy straw respectively. Lignin content increased by 41.4 % in T. reesei pretreated paddy straw whereas decreased by 19.1 % in C. versicolor pretreated straw. The microscopic structural changes were examined by scanning electron microscopy under reasonable conditions. Results showed that digestibility of paddy straw are increased by treating paddy straw with both the cultures. Both surface area and pore size of treated straw were increased partially due to solubilization of silica components. PMID:24426113

  8. TRANSITION REGION MAGNETIC FIELD AND POLAR MAGNETIC DISTURBANCES

    Microsoft Academic Search

    D. H. Fairfield; L. J. Jr. Cahill

    1966-01-01

    The Explorer 12 measurements of the magnetic field outside the magnetosphere are compared with ground magnetograms from arctic observatories. Results indicate that an exterior field with a southerly component tends to be associated with ground disturbance, whereas a northward field is associated with quiet conditions. Examples are presented show- ing how a north-to-south field-direction change accompanies an increase in ground

  9. Regional assemblages of Lygus (Heteroptera: Miridae) in Montana canola fields

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sweep net sampling of canola (Brassica napus L.) was conducted in 2002 and 2003 to determine Lygus (Heteroptera: Miridae) species composition and parasitism levels in four regions of Montana. Regardless of region or seasonal change, Lygus elisus (Van Duzee) was the dominant species in all canola fi...

  10. UNAVCO Plate Boundary Observatory 2007 Student Field Assistant Program in the Alaska Region

    Microsoft Academic Search

    A. Marzulla; S. Gasparich; B. Pauk; K. Feaux; M. Jackson

    2007-01-01

    The UNAVCO, Inc. Plate Boundary Observatory (PBO) Student Field Assistant Program strives to engage students in further study and careers in the Earth Sciences. Student Field Assistants from a variety of educational backgrounds ranging from high school graduates to master's level students spend a three to five month field season working in tandem with UNAVCO regional Field Engineers. The students

  11. A new cell projection algorithm based on feature region of 3D medical data field

    Microsoft Academic Search

    Xinwu Li; Chongyang Hao; Yangyu Fan; Miao Mao; Xiaoxiang Liu

    2004-01-01

    Considering the fuzzy characteristics of medical data field and requests of practicability, the paper presents a novel cell projection algorithm based on edge transition region of medical 3D data field. First, 3D data field is pretreated to a unitary and integral field, and the paper extends the method of segmenting 2D image and makes it can be used to extract

  12. Characteristics of parallel electric fields in the downward current region of the aurora

    E-print Network

    California at Berkeley, University of

    Characteristics of parallel electric fields in the downward current region of the aurora L downward current region. The observed parallel electric fields have amplitudes reaching nearly 1 V, Colorado 80309 Received 19 December 2001; accepted 7 May 2002 Direct measurements of parallel electric

  13. Impact of the solar wind dynamic pressure on the Region 2 field-aligned currents

    E-print Network

    Higuchi, Tomoyuki

    Impact of the solar wind dynamic pressure on the Region 2 field-aligned currents S. Nakano,1,2 G and the solar wind dynamic pressure is investigated using magnetic field data from Defense Meteorological in the magnetosphere varies with the solar wind dynamic pressure. Therefore, we can expect that the Region 2 currents

  14. Radial Heliospheric Magnetic Fields in Solar Wind Rarefaction Regions: Ulysses Observations

    E-print Network

    Sanahuja, Blai

    Radial Heliospheric Magnetic Fields in Solar Wind Rarefaction Regions: Ulysses Observations D it observed solar wind shears from the incursions of high-latitude fast solar wind toward the low-latitude slow solar wind. We look for nearly radial field orientations commonly observed in rarefaction regions

  15. Climatic parameters of wind-field variability in the Black Sea region: Numerical reanalysis of regional atmospheric circulation

    Microsoft Academic Search

    V. V. Efimov; A. E. Anisimov

    2011-01-01

    A reanalysis of atmospheric circulation in the Black Sea region is performed with a high spatial resolution of 25 × 25 km\\u000a for the period from 1958 to 2001. Climatic wind speed fields are estimated, as are their spatial structure and seasonal variability.\\u000a Mesoscale regions of cyclonic and anticyclonic speed vorticity, which are connected with edge effects and orography, are

  16. Bacillus haikouensis sp. nov., a facultatively anaerobic halotolerant bacterium isolated from a paddy soil.

    PubMed

    Li, Jibing; Yang, Guiqin; Lu, Qin; Zhao, Yong; Zhou, Shungui

    2014-10-01

    A Gram-stain positive, rod-shaped, endospore-forming and facultatively anaerobic halotolerant bacterium, designated as C-89(T), was isolated from a paddy field soil in Haikou, Hainan Province, People's Republic of China. Optimal growth was observed at 37 °C and pH 7.0 in the presence of 4% NaCl (w/v). The predominant menaquinone was identified as MK-7, the major cellular fatty acids were identified as anteiso-C(15:0) and iso-C(15:0), and the major cellular polar lipids were identified as phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylglycerol and two unknown phospholipids. The peptidoglycan type was determined to be based on meso-DAP. Based on 16S rRNA gene sequence similarity, the closest phylogenetic relatives were identified as Bacillus vietnamensis JCM 11124(T) (98.8% sequence similarity), Bacillus aquimaris JCM 11545(T) (98.6%) and Bacillus marisflavi JCM 11544(T) (98.5%). The DNA G+C content of strain C-89(T) was determined to be 45.4 mol%. The DNA-DNA relatedness values of strain C-89(T) with its closest relatives were below 18%. Therefore, on the basis of phylogenetic, chemotaxonomic, and phenotypic results, strain C-89(T) can be considered to represent a novel species within the genus Bacillus, for which the name Bacillus haikouensis sp. nov., is proposed. The type strain is C-89(T) (=KCTC 33545(T) = CCTCC AB 2014076(T)). PMID:25100188

  17. Convective-region geometry as the cause of Uranus' and Neptune's unusual magnetic fields

    Microsoft Academic Search

    Sabine Stanley; Jeremy Bloxham

    2004-01-01

    The discovery of Uranus' and Neptune's non-dipolar, non-axisymmetric magnetic fields destroyed the picture-established by Earth, Jupiter and Saturn-that planetary magnetic fields are dominated by axial dipoles. Although various explanations for these unusual fields have been proposed, the cause of such field morphologies remains unexplained. Planetary magnetic fields are generated by complex fluid motions in electrically conducting regions of the planets

  18. Sequestration of organic nitrogen in a paddy soil chronosequence as assessed by amino sugars molecular markers

    NASA Astrophysics Data System (ADS)

    Roth, Philipp; Lehndorff, E.; Cao, Z.; Amelung, W.

    2010-05-01

    Available nitrogen is a limiting factor in paddy rice systems due to ammonia volatilization, denitrification and stabilization in organic complexes. Soil organic nitrogen (SON) might therefore constitute a critical component of the nitrogen cycle in rice systems. The objective of this study was to elucidate the role of microorganisms for the sequestration of paddy N in organic forms. For this purpose we analyzed amino sugars as markers for the residues of bacteria and fungi in a chronosequence of soils that were used for paddy rice production for a period of 0 to 2000 years in the Hangzhou bay area in Southeast China. Within the soil profile, amino sugar concentrations were generally highest in the puddled Ap horizon and decreased with increasing depth along with organic carbon concentrations regardless of the time of rice cultivation. Nevertheless, a sharp increase of total amino sugar concentration from 0.1 g kg-1 to 0.3 g kg-1 was observed in the Ah horizon when comparing tidal wetland to salt marsh that had been impoldered 30 years ago, indicating an increasing importance of microbial residues in SON stabilization following the conversion of the semiaquatic marsh to a terrestrial system. With increased time of paddy rice cropping, amino sugar concentrations continued to increase up to a maximum of 2.1 g kg-1 after 300 years of paddy cultivation but declined again to 1 g kg-1 in soils with 700-2000 years history of cultivation despite increasing organic matter accumulation. Changes in the composition of the amino sugars were also most pronounced at initial stages of paddy rice management. The proportions of glucosamine (abundant in fungal chitin) decreased during the first 50 years of cultivation relative to mainly galactosamine (abundant in bacterial gums) and muramic acid (abundant in bacterial peptidoglycan), that remained at constantly low levels. At later stages of paddy rice cultivation, the ratios of glucosamine to galactosamine and to muramic acid re-increased. We conclude that microorganisms significantly contribute to the sequestration of paddy N in organic forms during the first 300 years of cropping, within an increasing contribution of bacteria as cropping time proceeds. At even longer periods of paddy rice cultivation, there appears to be a backshift to lower concentrations of microbial residues with higher proportions of fungal N remaining.

  19. Nitrogen loss through anaerobic ammonium oxidation coupled to iron reduction from paddy soils in a chronosequence.

    PubMed

    Ding, Long-Jun; An, Xin-Li; Li, Shun; Zhang, Gan-Lin; Zhu, Yong-Guan

    2014-09-16

    Anaerobic ammonium oxidation coupled to iron(III) reduction (termed Feammox) with dinitrogen, nitrite, or nitrate as the end-product is a recently discovered process of nitrogen cycling. However, Feammox has not been described in paddy soils, which are rich in iron(III) oxides and subjected to intensive nitrogen fertilization. Here, evidence for Feammox in a paddy soil chronosequence with a gradient of microbially reducible iron(III) levels was obtained in Southern China using (15)N-labeled ammonium-based isotopic tracing and acetylene inhibition techniques. Our study demonstrated the occurrence of Feammox in the chronosequence, and direct dinitrogen production was shown to be the dominant Feammox pathway. Within the chronosequence, three paddy soils with higher microbially reducible iron(III) levels had higher Feammox rates (ranged from 0.17 to 0.59 mg N kg(-1) d(-1)) compared to an uncultivated soil (0.04 mg N kg(-1) d(-1)). It is estimated that a loss of 7.8-61 kg N ha(-1) year(-1) is associated with Feammox in the examined paddy soils. Overall, we discover that rice cultivation could enrich microbially reducible iron(III), accelerate Feammox reaction and thus fuel nitrogen loss from soils, and suggest that Feammox could be a potentially important pathway for nitrogen loss in paddy soils. PMID:25158120

  20. Asymmetry of the ion diffusion region Hall electric and magnetic fields during guide field reconnection: observations and comparison with simulations.

    PubMed

    Eastwood, J P; Shay, M A; Phan, T D; Øieroset, M

    2010-05-21

    In situ measurements of magnetic reconnection in the Earth's magnetotail are presented showing that even a moderate guide field (20% of the reconnecting field) considerably distorts ion diffusion region structure. The Hall magnetic and electric fields are asymmetric and shunted away from the current sheet; an appropriately scaled particle-in-cell simulation is found to be in excellent agreement with the data. The results show the importance of correctly accounting for the effects of the magnetic shear when attempting to identify and study magnetic reconnection diffusion regions in nature. PMID:20867032

  1. Diazinon accumulation and dissipation in Oryza sativa L. following simulated agricultural runoff amendment in flooded rice paddies

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Flooded post-harvest rice paddies were examined as potential best management practices for reducing diazinon (organophosphate insecticide) concentrations in stormwater runoff. Two rice paddies were cultivated in Oryza sativa L. and amended with a 3hr, 0.1% simulated stormwater diazinon runoff event....

  2. Monday, November 5, 2007 Cadmium Speciation and Release Kinetics in a Thai Paddy Soil Subjected to Varying Redox Regimes.

    E-print Network

    Sparks, Donald L.

    controlling Cd speciation and bioavailability in paddy soils, and soil pH influences the transport and fateMonday, November 5, 2007 92-3 Cadmium Speciation and Release Kinetics in a Thai Paddy Soil, and Donald Sparks1. (1) Department of Plant and Soil Sciences and the Center for Critical Zone Research

  3. Upscaling methane emissions from rice paddies: Problems and possibilities

    NASA Astrophysics Data System (ADS)

    van Bodegom, P. M.; Verburg, Peter H.; Denier van der Gon, Hugo A. C.

    2002-03-01

    Global methane emission estimates depend highly on the models, techniques, and databases used. Since emissions cannot be measured directly at large scales, it is impossible to judge which estimate is more realistic. In this paper, different aspects of uncertainty in upscaling methane emissions from rice paddies are discussed. These aspects are visualized by a case study on the spatial upscaling of methane emissions from the island of Java, Indonesia. The first aspect concerns process information. An approach to incorporate this information in a simplified but process-based way in predictive models is discussed. Sources of uncertainty include the methane emissions measurements, processes quantification, process simplification, and the use of data transfer functions. Data availability of input parameters, the second aspect, is uncertain because of differences between different data sources, the use of data sources for purposes not originally planned for, and the scale at which data are available. Data interpolation in combination with nonlinear model responses introduces scaling errors, the third aspect. Data accuracy introduced the highest uncertainties in emission estimates but is rarely accounted for in the estimation of global emissions.

  4. Rate control of ammonia volatilization from rice paddies

    NASA Astrophysics Data System (ADS)

    Bouwmeester, Reinier J. B.; Vlek, Paul L. G.

    As part of a research program aimed at improving the efficiency of fertilizer N in flooded rice, an assessment is being made of the losses of NH 3 by volatilization. A model was developed to analyze the influence of floodwater chemistry and meteorological conditions. The complicated process of ammonia transfer across the gas-liquid interface was described using this model in conjunction with current theories of chemical reaction kinetics, evaporation from natural waters and atmospheric boundary layers. The model was shown to approximate with fair accuracy a data set obtained in a laboratory wind-water tunnel, simulating rice paddy conditions. Results of the analysis show the rate of ammonia volatilization to increase with increasing ammoniacal-N concentrations and pH of the floodwater as well as wind velocity and temperature, while it decreased with increasing fetch. The effects of wind, temperature and pH on the rate of ammonia volatilization are of the same order of magnitude. Some practical implications of the results are discussed.

  5. Sorption isotherms and isosteric heats of sorption of Malaysian paddy.

    PubMed

    Mousa, Wael; Ghazali, Farinazleen Mohamad; Jinap, S; Ghazali, Hasanah Mohd; Radu, Son

    2014-10-01

    Understanding the water sorption characteristics of cereal is extremely essential for optimizing the drying process and ensuring storage stability. Water relation of rough rice was studied at 20, 30, 40 and 50 °C over relative humidity (RH.) between 0.113 and 0.976 using the gravimetric technique. The isotherms displayed the general sigmoid, Type II pattern and exhibited the phenomenon of hysteresis where it was more pronounced at lower temperatures. The sorption characteristics were temperature dependence where the sorption capacity of the paddy increased as the temperature was decreased at fixed (RH). Among the models assessed for their ability to fit the sorption data, Oswin equation was the best followed by the third order polynomial, GAB, Smith, Chung-Pfost, and Henderson models. The monolayer moisture content was higher for desorption than adsorption and tend to decrease with the increase in temperature. Given the temperature dependence of the sorption isotherms the isosteric heats of sorption were calculated using Claussius-Clapeyron equation. The net isosteric heats decreased as the moisture content was increased and heats of desorption were greater than that of adsorption. PMID:25328208

  6. Helical Magnetic Fields in Solar Active Regions: Theory vs. Observations

    E-print Network

    K. Petrovay; P. Chaterjee; A. Choudhuri

    2007-02-02

    The mean value of the normalized current helicity in solar active regions is on the order of 1e-8 1/m, negative in the northern hemisphere, positive in the southern hemisphere. Observations indicate that this helicity has a subsurface origin. Possible mechanisms leading to a twist of this amplitude in magnetic flux tubes include the solar dynamo, convective buffeting of rising flux tubes, and the accretion of weak external poloidal flux by a rising toroidal flux tube. After briefly reviewing the observational and theoretical constraints on the origin of helicity, we present a recently developed detailed model for poloidal flux accretion.

  7. Capturing field-scale variability in crop performance across a regional-scale climosequence

    NASA Astrophysics Data System (ADS)

    Brooks, E. S.; Poggio, M.; Anderson, T. R.; Gasch, C.; Yourek, M. A.; Ward, N. K.; Magney, T. S.; Brown, D. J.; Huggins, D. R.

    2014-12-01

    With the increasing availability of variable rate technology for applying fertilizers and other agrichemicals in dryland agricultural production systems there is a growing need to better capture and understand the processes driving field scale variability in crop yield and soil water. This need for a better understanding of field scale variability has led to the recent designation of the R. J. Cook Agronomy Farm (CAF) (Pullman, WA, USA) as a United States Department of Agriculture Long-Term Agro-Ecosystem Research (LTAR) site. Field scale variability at the CAF is closely monitored using extensive environmental sensor networks and intensive hand sampling. As investigating land-soil-water dynamics at CAF is essential for improving precision agriculture, transferring this knowledge across the regional-scale climosequence is challenging. In this study we describe the hydropedologic functioning of the CAF in relation to five extensively instrumented field sites located within 50 km in the same climatic region. The formation of restrictive argillic soil horizons in the wetter, cooler eastern edge of the region results in the development of extensive perched water tables, surface saturation, and surface runoff, whereas excess water is not an issue in the warmer, drier, western edge of the region. Similarly, crop and tillage management varies across the region as well. We discuss the implications of these regional differences on field scale management decisions and demonstrate how we are using proximal soil sensing and remote sensing imagery to better understand and capture field scale variability at a particular field site.

  8. Field evidence in the Koryak Mountains Lake Mainitz region of far eastern Russia

    E-print Network

    Ingólfsson, Ólafur

    ABSTRACT Field evidence in the Koryak Mountains­ Lake Mainitz region of far eastern Russia supports and glaciofluvial terraces, common to all valleys at 13­13.8 m above river level, yield 36Cl ex- posure ages ranging

  9. Soil mineral surfaces of paddy soils are accessible for organic carbon accumulation after decalcification

    NASA Astrophysics Data System (ADS)

    Wissing, Livia

    2013-04-01

    We studied organic carbon (OC) accumulation due to organo-mineral associations during soil development on calcareous parent material. Two chronosequences in Zhejiang Province, PR China, were investigated; one under paddy cultivation with a maximum soil age of 2000 years, and the other under upland crops where the oldest soil was 700 years old. Bulk soils and soil fractions of the uppermost A horizons were analyzed for OC concentrations and radio carbon contents. Total pedogenic iron (Fed) concentration was determined by dithionite extraction and the proportion of oxalate extractable iron (Feox) was extracted by using the method of Schwertmann (1964). The specific surface area (SSA) of soil minerals was measured by the BET-N2 method (Brunauer et al., 1938) under four conditions: untreated, after organic matter removal, after iron removal and after removal of both. Within 700/2000 years of pedogenesis, we observed no change in clay mineral composition and no additional formation of the SSA of soil minerals. But the soils differed in the degree of decalcification, OC accumulation and in the formation of iron. Paddy soil management led to an enhanced decalcification and larger OC accumulation. Management-induced redox cycles caused larger proportions of Feox in paddy soils. Their large SSA, added to the surface area of clay minerals, provided additional options for OC covering. Unexpectedly, there was no evidence of formation of secondary minerals during soil development, which could provide new surfaces for OC accumulation. However, the study revealed higher OC coverings of mineral surfaces after decalcification in paddy soils. As carbonate and Ca2+ ions seemed to interconnect clay minerals, making their surface accessible to OC, the faster dissolution of carbonate and leaching of Ca2+ ions in paddy soils made additional clay mineral surfaces available to OC. In contrast, the surface area of minerals in non-paddy soils, in which decalcification was much lower, seemed to be partly inaccessible for OC covering due to strong microaggregation by cementation with carbonate and Ca2+-bridging. The smaller accumulation of mineral-associated SOM in non-paddy soils was additionally confirmed by the retarded replacement of the inherited carbon. The accelerated decalcification of paddy soils led to enhanced accessibility of mineral surfaces for OC covering, which intensified OC accumulation from the early stages of soil formation onward. References Brunauer, S., Emmett, P.H., Teller, E., (1938). Adsorption of gases in multimolecular layers. J. Am. Chem. Soc. 60 (2), 309-319. Schwertmann, U., 1964. Differenzierung der Eisenoxide des Bodens durch Extraktion mit Ammoniumoxalat-Lösung. Zeitschrift für Pflanzenernährung, Düngung, Bodenkunde 105 (3), 194-202.

  10. Thundercloud electric field modeling for the ionosphere-Earth region. 1: Dependence on cloud charge distribution

    Microsoft Academic Search

    Peter I. Y. Velinov; Peter T. Tonev

    1995-01-01

    The transmission of DC electric fields by thunderclouds with charge distributions is investigated analytically for the region between the ionosphere and the Earth surface. In such a way the hitherto existing presentations of thunderclouds by electric charge centers (monopole presentation) are generalized to much more adequate three-dimensional model charge regions. A modified ellipsoidal Gaussian profile for the charge distribution of

  11. Positron annihilation studies in the field induced depletion regions of metal-oxide-semiconductor structures

    E-print Network

    Rubloff, Gary W.

    Positron annihilation studies in the field induced depletion regions of metal February 1992) The centroid shifts of positron annihilation spectra are reported from the depletion regions-gaussian positron implantation profile. Inadequacy of the present analysis scheme is evident from the derived

  12. Nonlinear mechanisms in microwave photodetectors operated with high intrinsic region electric fields

    Microsoft Academic Search

    Keith J. Williams

    1994-01-01

    Measurements and simulations to determine the contributing nonlinear mechanisms in microwave photodetectors operated with high intrinsic region electric fields are presented. An important component of the nonlinear behavior is attributed to absorption in undepleted material adjacent to the depletion region, limiting the attainable device linearity. With as little as 10 nm of undepleted absorbing material, the second harmonic of a

  13. Scaling up from field to region for wind erosion prediction using a field-scale wind erosion model and GIS

    USGS Publications Warehouse

    Zobeck, T.M.; Parker, N.C.; Haskell, S.; Guoding, K.

    2000-01-01

    Factors that affect wind erosion such as surface vegetative and other cover, soil properties and surface roughness usually change spatially and temporally at the field-scale to produce important field-scale variations in wind erosion. Accurate estimation of wind erosion when scaling up from fields to regions, while maintaining meaningful field-scale process details, remains a challenge. The objectives of this study were to evaluate the feasibility of using a field-scale wind erosion model with a geographic information system (GIS) to scale up to regional levels and to quantify the differences in wind erosion estimates produced by different scales of soil mapping used as a data layer in the model. A GIS was used in combination with the revised wind erosion equation (RWEQ), a field-scale wind erosion model, to estimate wind erosion for two 50 km2 areas. Landsat Thematic Mapper satellite imagery from 1993 with 30 m resolution was used as a base map. The GIS database layers included land use, soils, and other features such as roads. The major land use was agricultural fields. Data on 1993 crop management for selected fields of each crop type were collected from local government agency offices and used to 'train' the computer to classify land areas by crop and type of irrigation (agroecosystem) using commercially available software. The land area of the agricultural land uses was overestimated by 6.5% in one region (Lubbock County, TX, USA) and underestimated by about 21% in an adjacent region (Terry County, TX, USA). The total estimated wind erosion potential for Terry County was about four times that estimated for adjacent Lubbock County. The difference in potential erosion among the counties was attributed to regional differences in surface soil texture. In a comparison of different soil map scales in Terry County, the generalised soil map had over 20% more of the land area and over 15% greater erosion potential in loamy sand soils than did the detailed soil map. As a result, the wind erosion potential determined using the generalised soil map Was about 26% greater than the erosion potential estimated by using the detailed soil map in Terry County. This study demonstrates the feasibility of scaling up from fields to regions to estimate wind erosion potential by coupling a field-scale wind erosion model with GIS and identifies possible sources of error with this approach.

  14. Bias Corrections for Regional Estimates of the Time-averaged Geomagnetic Field

    Microsoft Academic Search

    C. Constable; C. L. Johnson

    2009-01-01

    We assess two sources of bias in the time-averaged geomagnetic field (TAF) and paleosecular variation (PSV): inadequate temporal sampling, and the use of unit vectors in deriving temporal averages of the regional geomagnetic field. For the first temporal sampling question we use statistical resampling of existing data sets to minimize and correct for bias arising from uneven temporal sampling in

  15. Parallel electric fields in the upward current region of the aurora: Numerical solutions

    E-print Network

    California at Berkeley, University of

    Parallel electric fields in the upward current region of the aurora: Numerical solutions R. E layer that carries a substantial fraction roughly 5% to 50% of the auroral potential. A numerical Direct observations of the parallel electric field by the Fast Auroral Snapshot satellite and the Polar

  16. New features of electron diffusion regions observed at subsolar magnetic field reconnection sites

    E-print Network

    California at Berkeley, University of

    . S. Mozer,1 S. D. Bale,1 J. P. McFadden,1 and R. B. Torbert2 Received 15 July 2005; revised 11: Mozer, F. S., S. D. Bale, J. P. McFadden, and R. B. Torbert (2005), New features of electron diffusion for regions having [Mozer, 2005]: [3] - A non-zero parallel electric field (because such a field is required

  17. Measurement of temperature field in the region near to the radiator by using digital holography

    Microsoft Academic Search

    Yan Li; Dayong Wang; Guangjun Wang; Yizhuo Zhang; Changgeng Liu

    2009-01-01

    A simple method for measurement of temperature field in the region near to the metal plate of the radiator is demonstrated by using digital holography in the Lensless Fourier transform configuration (LFT). The temperature is measured within the boundary layer of the convective flow field. The deviation of the temperature produced by this method, from that obtained by the thermocouple

  18. Markov random fields for textures recognition with local invariant regions and their geometric

    E-print Network

    Paris-Sud XI, Université de

    Markov random fields for textures recognition with local invariant regions and their geometric the parameters with a recent technique based on the mean field principle. Preliminary results for texture recognition [14], texture classification [8] and texture recognition [9]1. They are distinctive, robust

  19. Lobe cell convection and field-aligned currents poleward of the region 1 current system

    E-print Network

    Eriksson, Stefan

    Lobe cell convection and field-aligned currents poleward of the region 1 current system S. Eriksson presented in support of lobe cell convection from an ionospheric perspective this far from the noon sector evidence for six large-scale field-aligned currents (FACs) rather than the usual system of four FACs

  20. A region of intense plasma wave turbulence on auroral field lines

    NASA Technical Reports Server (NTRS)

    Gurnett, D. A.; Frank, L. A.

    1976-01-01

    This report presents a detailed study of the plasma wave turbulence observed by HAWKEYE-1 and IMP-6 on high latitude auroral field lines and investigates the relationship of this turbulence to magnetic field and plasma measurements obtained in the same region.

  1. Maximum torque control of an induction machine in the field weakening region

    Microsoft Academic Search

    Sang-Hoon Kim; Seung-Ki Sul

    1995-01-01

    In this paper, a new approach to the induction machine control that ensures the production of maximum torque per ampere over the entire field weakening region is presented. Considering the limitations of voltage and current, the optimal current condition for yielding the maximum torque is obtained. Also, since the onset of the field weakening operation is automatically adjusted according to

  2. Midlatitude E region field-aligned irregularities observed with the MU radar

    Microsoft Academic Search

    Mamoru Yamamoto; Shoichiro Fukao; Susumu Kato; Ronald F. Woodman; Tadahiko Ogawa

    1991-01-01

    The present study investigates fine structures of E region field-aligned irregularities observed on June 24 and 25, 1989, with the MU radar at Shigaraki, Japan. Doppler spectra were obtained every 20 s with a range resolution of 600 m. Field-perpendicular echoes appeared from 2130 to 2330 LT and from 0400 to 1100 LT, times that correspond to the postsunset and

  3. Effects of water management, connectivity, and surrounding land use on habitat use by frogs in rice paddies in Japan.

    PubMed

    Naito, Risa; Yamasaki, Michimasa; Lmanishi, Ayumi; Natuhara, Yosihiro; Morimoto, Yukihiro

    2012-09-01

    In Japan, rice paddies play an important role as a substitute habitat for wetland species, and support rich indigenous ecosystems. However, since the 1950s, agricultural modernization has altered the rice paddy environment, and many previously common species are now endangered. It is urgently necessary to evaluate rice paddies as habitats for conservation. Among the species living in rice paddies, frogs are representative and are good indicator species, so we focused on frog species and analyzed the influence of environmental factors on their habitat use. We found four frog species and one subspecies (Hyla japonica, Pelophylax nigromaculatus, Glandirana rugosa, Lithobates catesbeianus, and Pelophylax porosa brevipoda) at our study sites in Shiga prefecture. For all but L. catesbeianus, we analyzed the influence of environmental factors related to rice paddy structure, water management and availability, agrochemical use, connectivity, and land use on breeding and non-breeding habitat use. We constructed generalized additive mixed models with survey date as the smooth term and applied Akaike's information criterion to choose the bestranked model. Because life histories and biological characteristics vary among species, the factors affecting habitat use by frogs are also expected to differ by species. We found that both breeding and non-breeding habitat uses of each studied species were influenced by different combinations of environmental factors and that in most cases, habitat use showed seasonality. For frog conservation in rice paddies, we need to choose favorable rice paddy in relation to surrounding land use and apply suitable management for target species. PMID:22943781

  4. Flexible gas insulated transmission line having regions of reduced electric field

    DOEpatents

    Cookson, Alan H. (Pittsburgh, PA); Fischer, William H. (Wilkins Township, Allegheny County, PA); Yoon, Kue H. (Pittsburgh, PA); Meyer, Jeffry R. (Penn Hills Township, Allegheny County, PA)

    1983-01-01

    A gas insulated transmission line having radially flexible field control means for reducing the electric field along the periphery of the inner conductor at predetermined locations wherein the support insulators are located. The radially flexible field control means of the invention includes several structural variations of the inner conductor, wherein careful controlling of the length to depth of surface depressions produces regions of reduced electric field. Several embodiments of the invention dispose a flexible connector at the predetermined location along the inner conductor where the surface depressions that control the reduced electric field are located.

  5. MAGNETIC FIELD TOPOLOGY AND THE THERMAL STRUCTURE OF THE CORONA OVER SOLAR ACTIVE REGIONS

    SciTech Connect

    Schrijver, Carolus J.; DeRosa, Marc L.; Title, Alan M., E-mail: schryver@lmsal.co [Lockheed Martin Advanced Technology Center, Palo Alto, CA 94304 (United States)

    2010-08-20

    Solar extreme ultraviolet (EUV) images of quiescent active-region coronae are characterized by ensembles of bright 1-2 MK loops that fan out from select locations. We investigate the conditions associated with the formation of these persistent, relatively cool, loop fans within and surrounding the otherwise 3-5 MK coronal environment by combining EUV observations of active regions made with TRACE with global source-surface potential-field models based on the full-sphere photospheric field from the assimilation of magnetograms that are obtained by the Michelson Doppler Imager (MDI) on SOHO. We find that in the selected active regions with largely potential-field configurations these fans are associated with (quasi-)separatrix layers (QSLs) within the strong-field regions of magnetic plage. Based on the empirical evidence, we argue that persistent active-region cool-loop fans are primarily related to the pronounced change in connectivity across a QSL to widely separated clusters of magnetic flux, and confirm earlier work that suggested that neither a change in loop length nor in base field strengths across such topological features are of prime importance to the formation of the cool-loop fans. We discuss the hypothesis that a change in the distribution of coronal heating with height may be involved in the phenomenon of relatively cool coronal loop fans in quiescent active regions.

  6. Spatial distribution and controlling factors of heavy metals contents in paddy soil and crop grains of rice-wheat cropping system along highway in East China.

    PubMed

    Feng, Jinfei; Zhao, Jian; Bian, Xinmin; Zhang, Weijian

    2012-10-01

    There is consensus concerning the heavy metal pollution from traffic emission on roadside agricultural land. However, few efforts have been paid on examining the contamination characteristics of heavy metals in roadside paddy-upland rotation field, and especially in combination with detailed quantitative analysis. In this study, we investigated the concentrations of heavy metals (Pb, Cd, Cr and Zn) in soil and crop grains of the rice-wheat cropping system along a major highway in East China in 2008 and analyzed the spatial distribution characteristics of heavy metals and their influencing factors with GIS and Classification and Regression Trees (CART). Significantly elevated levels of heavy metals in soil, rice and wheat grains indicated the heavy metals contamination of traffic emission in roadside rice-wheat rotation field. The contamination levels of Cd, Cr and Zn in wheat grain were higher than rice grain, while that of Pb showed an opposite trend. Obvious dissimilarities in the spatial distributions of heavy metals contents were found between in the soil, rice and wheat grains, indicating that the heavy metals contents in the roadside crop grains were not only determined by the concentrations of heavy metals in the paddy soil. Results of CART analysis showed that the spatial variation of the heavy metals contents in crop grains was mainly affected by the soil organic matter or soil pH, followed by the distance from highway and wind direction. Our findings have important implications for the environmental assessment and crop planning for food security along the highway. PMID:22527116

  7. BIOAVAILABILITY AND SAFETY ISSUES OF HEAVY METALS IN PADDY SOIL-RICE CONTINUUM IN KOREA

    Microsoft Academic Search

    Won-Il Kim; Jae E. Yang; Goo-Bok Jung; Byung-Jun Park; Sang-Won Park; Jin-Kyoung Kim; Oh-Kyung Kwon; Gab-Hee Ryu

    There is an increasing concern over heavy metal contamination of agricultural soils and the successive translocation of metals to rice in Korea. Rice is one of the most important crops in the country. Thus, it is very important to monitor the status and trend of heavy metal contamination in paddy soils and rice periodically. It is also important to verify

  8. The Research of Paddy Rice Moisture Lossless Detection Based on L-M BP Neural Network

    NASA Astrophysics Data System (ADS)

    Sun, Jun; Mao, Hanping; Liu, Jinjuan; Zhang, Bin

    The method of the quantitative analysis on the paddy rice moisture condition is studied, which is based on the spectral reflectivity of the leaf crest layer. Several subsections are carried on the entire spectrum curve by the equidistance, The sensitive characteristic wave-length is selected based on the table of molecular spectrum sensitive wave band, obtains the characteristic spectral reflection index value to take as the characteristic value. The convergence rate of the BP neural network is slow, so the L-M algorithm is introduced to carry on the renewal of the neural network weights. The paddy rice water moisture quantitative analysis forecast model is established by making use of the fast study function of the L-M algorithm neural network. The forecasting results indicate that the highest prediction error of the paddy rice water content is 6.72% and the average error rate is 4.23%. The prediction effect is better than the traditional BP network arithmetic, and it can be used in the lossless inspection of paddy rice moisture.

  9. SPECIATION AND RELEASE KINETICS OF CADMIUM AND ZINC IN PADDY SOILS

    E-print Network

    Sparks, Donald L.

    Sukreeyapongse for soil information at Cd contamination sites, Mr. Piboon Kanghae for his help interest in soil science has been also fueled by the unfortunate Cd contamination that occurredSPECIATION AND RELEASE KINETICS OF CADMIUM AND ZINC IN PADDY SOILS by Saengdao Khaokaew

  10. CADMIUM SOLUBILITY IN PADDY SOILS: EFFECTS OF SOIL OXIDATION, METAL SULFIDES AND COMPETITIVE IONS.

    EPA Science Inventory

    Cadmium (Cd) is a non-essential element for human nutrition and is an agricultural soil contaminant. Cadmium solubility in paddy soils affects Cd accumulation in the grain of rice. This is a human health risk, exacerbated by the fact that rice grains are deficient in iron (Fe) an...

  11. Aging well: methanotrophic potential and community structure along a paddy soil chronosequence of 2000 years.

    NASA Astrophysics Data System (ADS)

    Ho, Adrian; Frenzel, Peter

    2010-05-01

    Given that rice paddies are anthropogenic methane sources and the inevitable need to increase rice production to sustain human population growth, it is pertinent to identify the effects of long term agriculture on the selection of methanotrophs. Methanotrophs play a crucial role in mitigating methane emission from rice paddies. Therefore, we analyzed the methanotroph community along a chronosequence of paddy soils from China covering recently reclaimed sites to paddies under permanent agriculture since 2000 years (Cheng et al., 2009; doi:10.1016/j.geoderma.2009.03.016). Maximum potential methane oxidation rate (PMOR) increased monotonically with age. Our results also showed that long-term agriculture imposes a selection pressure on different groups of methanotrophs. In contrast to younger soils, type Ib methanotrophs were observed to multiply in correspondence with increasing PMOR in ancient soils, while other groups showed a relatively stable community composition as revealed by pmoA-based fingerprints (T-RFLP) and quantitative PCR. Cloning and sequencing the pmoA (a key gene in methane oxidation), the soils were found to harbour known and putative methanotrophs, ammonium-oxidizing bacteria, and interestingly, sequences affiliated to Crenothrix, a methane oxidizer with an unusual pmoA (Stoecker et al., 2006; doi:10.1073/pnas.0506361103). In summary, long-term agriculture shapes the community and allows for an elevated level of potential methane oxidation.

  12. Adsorption–Desorption Characteristics of Mercury in Paddy Soils of China

    Microsoft Academic Search

    Y. D. Jing; Z. L. He; X. E. Yang

    2008-01-01

    Mercury (Hg) has received considerable attention because of its association with various human health problems. Adsorption-desorption behavior of Hg at contaminated levels in two paddy soils was investigated. Th e two representative soils for rice production in China, locally referred to as a yellowish red soil (YRS) and silty loam soil (SLS) and classifi ed as Gleyi- Stagnic Anthrosols in

  13. Cadmium Speciation and Release Kinetics in a Thai Paddy Soil Subjected to Varying Redox Regimes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Understanding the factors controlling Cd speciation and bioavailability in flooded, drained, and alternate flooded/drained paddy soil will be crucial to developing and implementing best management practices needed for productive agricultural areas. Transformation of Cd species can occur in response...

  14. The effect on methane emission by different soil enzyme activity in paddy soil

    Microsoft Academic Search

    Jing Ling; Liangji Deng; Xiaolin Huang; Yan Li; Gan Jiang

    2011-01-01

    In this study, with the paddy soil by different fertilized in Chengdu Plain, we have researched the correlation between soil cataloes, phosphates and unease activity and CH4 emission. The results showed that: (1) in the rice growth period, the Soil cataloes, phosphates and unease activity for each treatment got the trend that decreasing first and then increasing, decreasing finally. The

  15. Effects of magnetic field intensity on carbon diffusion coefficient in pure iron in ?-Fe temperature region

    NASA Astrophysics Data System (ADS)

    Wu, Yan; Duan, Guosheng; Zhao, Xiang

    2015-03-01

    Effects of magnetic field intensity on carbon diffusion coefficient in pure iron in the ?-Fe temperature region were investigated using carburizing technology. The carbon penetration profiles from the iron surface to interior were measured by field emission electron probe microanalyzer. The carbon diffusion coefficient in pure iron carburized with different magnetic field intensities was calculated according to the Fick's second law. It was found that the magnetic field intensity could obviously affect the carbon diffusion coefficient in pure iron in the ?-Fe temperature region, and the carbon diffusion coefficient decreased obviously with the enhancement of magnetic field intensity, when the magnetic field intensity was higher than 1 T, the carbon diffusion coefficient in field annealed specimen was less than half of that of the nonfield annealed specimen, further enhancing the magnetic field intensity, the carbon diffusion coefficient basically remains unchanged. The stiffening of lattice due to field-induced magnetic ordering was responsible for an increase in activation barrier for jumping carbon atoms. The greater the magnetic field intensity, the stronger the inhibiting effect of magnetic field on carbon diffusion.

  16. Hyperspectral remote sensing of paddy crop using insitu measurement and clustering technique

    NASA Astrophysics Data System (ADS)

    Moharana, S.; Dutta, S.

    2014-11-01

    Rice Agriculture, mainly cultivated in South Asia regions, is being monitored for extracting crop parameter, crop area, crop growth profile, crop yield using both optical and microwave remote sensing. Hyperspectral data provide more detailed information of rice agriculture. The present study was carried out at the experimental station of the Regional Rainfed Low land Rice Research Station, Assam, India (26.1400° N, 91.7700° E) and the overall climate of the study area comes under Lower Brahmaputra Valley (LBV) Agro Climatic Zones. The hyperspectral measurements were made in the year 2009 from 72 plots that include eight rice varieties along with three different level of nitrogen treatments (50, 100, 150 kg/ha) covering rice transplanting to the crop harvesting period. With an emphasis to varieties, hyperspectral measurements were taken in the year 2014 from 24 plots having 24 rice genotypes with different crop developmental ages. All the measurements were performed using a spectroradiometer with a spectral range of 350-1050 nm under direct sunlight of a cloud free sky and stable condition of the atmosphere covering more than 95 % canopy. In this study, reflectance collected from canopy of rice were expressed in terms of waveforms. Furthermore, generated waveforms were analysed for all combinations of nitrogen applications and varieties. A hierarchical clustering technique was employed to classify these waveforms into different groups. By help of agglomerative clustering algorithm a few number of clusters were finalized for different rice varieties along with nitrogen treatments. By this clustering approach, observational error in spectroradiometer reflectance was also nullified. From this hierarchical clustering, appropriate spectral signature for rice canopy were identified and will help to create rice crop classification accurately and therefore have a prospect to make improved information on rice agriculture at both local and regional scales. From this hierarchical clustering, spectral signature library for rice canopy were identified which will help to create rice crop classification maps and critical wave bands like green (519,559 nm), red (649 nm), red edge (729 nm) and NIR region (779,819 nm) were marked sensitive to nitrogen which will further help in nitrogen mapping of paddy agriculture over therefore have the prospect to make improved informed decisions.

  17. Fate of 14C-labeled dissolved organic matter in paddy and upland soils in responding to moisture.

    PubMed

    Chen, Xiangbi; Wang, Aihua; Li, Yang; Hu, Lening; Zheng, Hua; He, Xunyang; Ge, Tida; Wu, Jinshui; Kuzyakov, Yakov; Su, Yirong

    2014-08-01

    Soil organic matter (SOM) content in paddy soils is higher than that in upland soils in tropical and subtropical China. The dissolved organic matter (DOM) concentration, however, is lower in paddy soils. We hypothesize that soil moisture strongly controls the fate of DOM, and thereby leads to differences between the two agricultural soils under contrasting management regimens. A 100-day incubation experiment was conducted to trace the fate and biodegradability of DOM in paddy and upland soils under three moisture levels: 45%, 75%, and 105% of the water holding capacity (WHC). (14)C labeled DOM, extracted from the (14)C labeled rice plant material, was incubated in paddy and upland soils, and the mineralization to (14)CO2 and incorporation into microbial biomass were analyzed. Labile and refractory components of the initial (14)C labeled DOM and their respective half-lives were calculated by a double exponential model. During incubation, the mineralization of the initial (14)C labeled DOM in the paddy soils was more affected by moisture than in the upland soils. The amount of (14)C incorporated into the microbial biomass (2.4-11.0% of the initial DOM-(14)C activity) was less affected by moisture in the paddy soils than in the upland soils. At any of the moisture levels, 1) the mineralization of DOM to (14)CO2 within 100 days was 1.2-2.1-fold higher in the paddy soils (41.9-60.0% of the initial DOM-(14)C activity) than in the upland soils (28.7-35.7%), 2) (14)C activity remaining in solution was significantly lower in the paddy soils than in the upland soils, and 3) (14)C activity remaining in the same agricultural soil solution was not significantly different among the three moisture levels after 20 days. Therefore, moisture strongly controls DOM fate, but moisture was not the key factor in determining the lower DOM in the paddy soils than in the upland soils. The UV absorbance of DOM at 280 nm indicates less aromaticity of DOM from the paddy soils than from the upland soils. At any of the moisture levels, much more labile DOM was found in paddy soils (34.3-49.2% of the initial (14)C labeled DOM) compared with that in upland soils (19.4-23.9%). This demonstrates that the lower DOM content in the paddy soil compared with that in the upland soil is probably determined by the less complex components and structure of the DOM. PMID:24836136

  18. Soil type determines the abundance and community structure of ammonia-oxidizing bacteria and archaea in flooded paddy soils

    Microsoft Academic Search

    Xin Chen; Li-Mei Zhang; Ju-Pei Shen; Zhihong Xu; Ji-Zheng He

    2010-01-01

    Purpose  Ammonia oxidation plays an important role in global nitrogen cycle. However, little information is available on ammonia oxidizers\\u000a in paddy soils. This study aimed to understand the controlling factors of ammonia oxidizers in the paddy soils.\\u000a \\u000a \\u000a \\u000a \\u000a Materials and methods  Three types of paddy soils were collected from southwest [Chongqing City (CQ)], central [Honghu City (HH)], and northeast\\u000a [Panjin City (PJ)] of

  19. Estimation of ionospheric electric fields and currents from a regional magnetometer array

    SciTech Connect

    Murison, M.; Richmond, A.D.; Matsushita, S.; Baumjohann, W.

    1985-04-01

    We investigate the technique of calculating ionospheric electric fields and currents and field-aligned currents using an equivalent current function obtained from a regional array of ground-based magnetometers at high latitudes (Scandinavian Magnetometer Array). Like similar calculations previously done on a global scale, the derived electric fields and currents are found to depend on the model of ionospheric conductivity assumed. Unlike the global scale calculations, the regional calculations are also dependent on the assumed boundary conditions. Additional information on the electric fields, currents, and/or conductivities is required, besides the ground magnetic variations, to obtain unique estimations of the ionospheric electrodynamic features. In the present case, ionospheric drift measurements from one of the Scandinavian Twin Auroral Radar Experiment radars help constrain the calculations. Analysis of an equivalent current function at 1835 UT on October 7, 1976, representing Harang discontinuity conditions, suggests that upward field-aligned current probably existed near the boundary between eastward and westward electrojets.

  20. pH regulates ammonia-oxidizing bacteria and archaea in paddy soils in Southern China.

    PubMed

    Li, Hu; Weng, Bo-Sen; Huang, Fu-Yi; Su, Jian-Qiang; Yang, Xiao-Ru

    2015-07-01

    Ammonia-oxidizing archaea (AOA) and bacteria (AOB) play important roles in nitrogen cycling. However, the effects of environmental factors on the activity, abundance, and diversity of AOA and AOB and the relative contributions of these two groups to nitrification in paddy soils are not well explained. In this study, potential nitrification activity (PNA), abundance, and diversity of amoA genes from 12 paddy soils in Southern China were determined by potential nitrification assay, quantitative PCR, and cloning. The results showed that PNA was highly variable between paddy soils, ranging from 4.05?±?0.21 to 9.81?±?1.09 mg NOx-N kg(-1) dry soil day(-1), and no significant correlation with soil parameters was found. The abundance of AOA was predominant over AOB, indicating that AOA may be the major members in aerobic ammonia oxidation in these paddy soils. Community compositions of AOA and AOB were highly variable among samples, but the variations were best explained by pH. AOA sequences were affiliated to the Nitrosopumilus cluster and Nitrososphaera cluster, and AOB were classified into the lineages of Nitrosospira and Nitrosomonas, with Nitrosospira being predominant over Nitrosomonas, accounting for 83.6 % of the AOB community. Moreover, the majority of Nitrosomonas was determined in neutral soils. Canonical correspondence analysis (CCA) analysis further demonstrated that AOA and AOB community structures were significantly affected by pH, soil total organic carbon, total nitrogen, and C/N ratio, suggesting that these factors exert strong effects on the distribution of AOB and AOA in paddy soils in Southern China. In conclusion, our results imply that soil pH was a key explanatory variable for both AOA and AOB community structure and nitrification activity. PMID:25744648

  1. MODELING MAGNETIC FIELD STRUCTURE OF A SOLAR ACTIVE REGION CORONA USING NONLINEAR FORCE-FREE FIELDS IN SPHERICAL GEOMETRY

    SciTech Connect

    Guo, Y.; Ding, M. D. [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China); Liu, Y.; Sun, X. D. [W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305 (United States); DeRosa, M. L. [Lockheed Martin Advanced Technology Center, 3251 Hanover Street, Palo Alto, CA 94304 (United States); Wiegelmann, T., E-mail: guoyang@nju.edu.cn [Max-Planck-Institut fuer Sonnensystemforschung, Max-Planck-Strasse 2, D-37191 Katlenburg-Lindau (Germany)

    2012-11-20

    We test a nonlinear force-free field (NLFFF) optimization code in spherical geometry using an analytical solution from Low and Lou. Several tests are run, ranging from idealized cases where exact vector field data are provided on all boundaries, to cases where noisy vector data are provided on only the lower boundary (approximating the solar problem). Analytical tests also show that the NLFFF code in the spherical geometry performs better than that in the Cartesian one when the field of view of the bottom boundary is large, say, 20 Degree-Sign Multiplication-Sign 20 Degree-Sign . Additionally, we apply the NLFFF model to an active region observed by the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory (SDO) both before and after an M8.7 flare. For each observation time, we initialize the models using potential field source surface (PFSS) extrapolations based on either a synoptic chart or a flux-dispersal model, and compare the resulting NLFFF models. The results show that NLFFF extrapolations using the flux-dispersal model as the boundary condition have slightly lower, therefore better, force-free, and divergence-free metrics, and contain larger free magnetic energy. By comparing the extrapolated magnetic field lines with the extreme ultraviolet (EUV) observations by the Atmospheric Imaging Assembly on board SDO, we find that the NLFFF performs better than the PFSS not only for the core field of the flare productive region, but also for large EUV loops higher than 50 Mm.

  2. Calculating Non-Potentiality in Solar Active Regions Using SDO/HMI Vector Magnetic Field Data

    NASA Astrophysics Data System (ADS)

    Bobra, M.; Hoeksema, J. T.

    2010-12-01

    Non-potential magnetic fields in solar active regions are thought to be associated with flare occurrence. In this study, we parametrize the non-potentiality of several active regions, using data from the Helioseismic and Magnetic Imager (HMI) aboard the Solar Dynamics Observatory (SDO), and correlate these parameters with flare occurrence. In particular, we focus on a parameter that we call the Gradient-Weighted Inversion Line Length (GWILL). Using data from SOHO/MDI, Mason et al. found that GWILL generally tends to increase before a solar flare. We investigate whether extending the analysis of Mason et. al. to a three-dimensional field enables us to derive better near real-time indicators of flare occurrence. Before HMI, the availability of vector magnetograms was sparse at best. HMI provides continuous vector magnetogram data at a 12-minute cadence. As such, this study represents the first parametrization of non-potentiality in solar active regions using continuous vector magnetic field data.

  3. Field Performance Prediction Method Based On Contrast Metric Of Target Sub Regions

    NASA Astrophysics Data System (ADS)

    Wang, Xiao-Rui; Liu, Xin; Zhang, Jian-Qi

    2007-07-01

    The field performance prediction of infrared imaging system is an important subject in infrared imaging field. In this paper, a novel method for predicting TA (target acquisition) performance is proposed, which combines the TOD (triangle orientation discrimination) threshold curve with an improved contrast metric based on the temperature in target sub regions. Specifically, the target is first subdivided into some sub regions with different target/background differential temperatures according to its thermal structure distribution. The number of equivalent triangle patterns across each sub region is calculated utilizing its effective size, the apparent temperature difference line, and the TOD curve. Further, the total number of equivalent triangle patterns over the integral target is achieved. Combining the TOD criteria, the target acquisition ranges for different discrimination (detection, recognition, and identification) levels are obtained by solving a set of equations. Comparisons with the preliminary experimental results show that this new TA approach can provide reasonable prediction of field performance.

  4. Flat field concave holographic grating with broad spectral region and moderately high resolution.

    PubMed

    Wu, Jian Fen; Chen, Yong Yan; Wang, Tai Sheng

    2012-02-01

    In order to deal with the conflicts between broad spectral region and high resolution in compact spectrometers based on a flat field concave holographic grating and line array CCD, we present a simple and practical method to design a flat field concave holographic grating that is capable of imaging a broad spectral region at a moderately high resolution. First, we discuss the principle of realizing a broad spectral region and moderately high resolution. Second, we provide the practical method to realize our ideas, in which Namioka grating theory, a genetic algorithm, and ZEMAX are used to reach this purpose. Finally, a near-normal-incidence example modeled in ZEMAX is shown to verify our ideas. The results show that our work probably has a general applicability in compact spectrometers with a broad spectral region and moderately high resolution. PMID:22307123

  5. Phase space structure of the electron diffusion region in reconnection with weak guide fields

    SciTech Connect

    Ng, J.; Egedal, J.; Le, A. [Department of Physics, and Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Daughton, W. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    2012-11-15

    Kinetic simulations of magnetic reconnection provide detailed information about the electric and magnetic structure throughout the simulation domain, as well as high resolution profiles of the essential fluid parameters including the electron and ion densities, flows, and pressure tensors. However, the electron distribution function, f(v), within the electron diffusion region becomes highly structured in the three dimensional velocity space and is not well resolved by the data available from the particle-in-cell (PIC) simulations. Here, we reconstruct the electron distribution function within the diffusion region at enhanced resolution. This is achieved by tracing electron orbits in the fields taken from PIC simulations back to the inflow region where an analytic form of the magnetized electron distribution is known. For antiparallel reconnection, the analysis reveals the highly structured nature of f(v), with striations corresponding to the number of times electrons have been reflected within the reconnection current layer, and exposes the origin of gradients in the electron pressure tensor important for momentum balance. The structure of the reconnection region is strongly tied to the pressure anisotropy that develops in the electrons upstream of the reconnection region. The addition of a guide field changes the nature of the electron distributions, and the differences are accounted for by studying the motion of single particles in the field geometry. Finally, the geometry of small guide field reconnection is shown to be highly sensitive to the ion/electron mass ratio applied in the simulation.

  6. Magnetic field in the end region of the SSC quadrupole magnet

    SciTech Connect

    Caspi, S.; Helm, M.; Laslett, L.J.

    1991-06-01

    Recent advances in methods of computing magnetic fields have made it possible to study the field in the end region of the SS quadrupole magnet in detail. The placement of conductor in the straight section, away from the ends, was designed to produce a practically pure quadrupole field in the two-dimensional sense. The ends of the coils were designed to produce a practically pure quadrupole field in the integral sense using a method that ignores the presence of the iron yoke. Subsequently, the effect of presence of the yoke on the field was analyzed. The paper presents the end configuration together with the computed integrated multipole components, local multipole components, and local field components. A comparison with measurements is included. 5 refs., 5 figs., 1 tab.

  7. Magnetic field in the end region of the SSC quadrupole magnet

    SciTech Connect

    Caspi, S.; Helm, M.; Laslett, L.J. (Lawrence Berkeley Lab., CA (United States))

    1992-01-01

    Recent advances in methods of computing magnetic fields have made it possible to study the field in the end region of the SSC quadrupole magnet in detail. The placement of conductor in the straight section, away from the ends, was designed to produce a practically pure quadrupole field in the two-dimensional sense. The ends of the coils were designed to produce a practically pure quadrupole field in the integral sense using a method that ignores the presence of the iron yoke. Subsequently, the effect of the presence of the yoke on the field was analyzed. The paper presents the end configuration together with the computer integrated multipole components, local multipole components, and local field components. A comparison with measurements is included.

  8. Measurement of temperature field in the region near to the radiator by using digital holography

    NASA Astrophysics Data System (ADS)

    Li, Yan; Wang, Dayong; Wang, Guangjun; Zhang, Yizhuo; Liu, Changgeng

    2009-07-01

    A simple method for measurement of temperature field in the region near to the metal plate of the radiator is demonstrated by using digital holography in the Lensless Fourier transform configuration (LFT). The temperature is measured within the boundary layer of the convective flow field. The deviation of the temperature produced by this method, from that obtained by the thermocouple is rather small. It has shown that the method is reasonable and efficient.

  9. Heat and moisture dynamics in raised field systems of the lake Titicaca region (Bolivia)

    Microsoft Academic Search

    Diego Sánchez de Lozada; Philippe Baveye; Susan Riha

    1998-01-01

    Pre-Hispanic cultures constructed more than 82?000ha of raised fields for agricultural production in the Lake Titicaca Region, in the current day Bolivia and Peru. Raised fields consist of platforms (up to 1.2m high and 2–20m wide), elevated relative to the original soil surface and surrounded by canals (1.6–4.5m wide). In the last decade, archaeologists have promoted the adoption of raised

  10. On a plasma sheath separating regions of oppositely directed magnetic field

    Microsoft Academic Search

    E. G. Harris

    1962-01-01

    Summary  An exact solution of the Vlasov equations is found which describes a layer of plasma confined between two regions of oppositely\\u000a directed magnetic field. The electrons and ions have Maxwellian distributions on the plane where the magnetic field vanishes.\\u000a In the coordinate system, in which the electron and ion drift velocities are equal in magnitude but opposite in direction,\\u000a the

  11. Periodic auroral forms and geomagnetic field oscillations in the 1400 MLT region

    SciTech Connect

    Potemra, T.A. (Johns Hopkins Univ., Laurel, MD (United States)); Vo, H.; Venkatesan, D.; Cogger, L.L. (Univ. of Calgary, Alberta (Canada)); Erlandson, R.E.; Zanetti, L.J.; Bythrow, P.F.; Anderson, B.J. (Johns Hopkins Univ., Laurel, MD (United States))

    1990-05-01

    The UV images obtained with the Viking satellite often show bright features which resemble beads or pearls aligned in the east-west direction between noon and 1800 MLT. Viking acquired a series of 25 UV images during a 28-min period on July 29, 1986, which showed a distinct series of periodic bright features in this region. Magnetic field and hot plasma measurements obtained by Viking confirm that the UV emissions are colocated with the field line projection of an upward-flowing region 1 Birkeland current and precipitating energetic ({approximately}200 eV) electrons. The magnetic field and electric field measurements show transverse oscillations with a nearly constant period of about 3.5 min from 67{degree} invariant latitude equatorward up to the location of the large-scale Birkeland current system near 76{degree} invariant latitude. The electric field oscillations lead the magnetic field oscillations by about a quarter-period. The authors interpret the observed oscillations as standing Alfven waves driven at a frequency near the local resonance frequency by a large-scale wave in the boundary layer. They propose that the energy flux of the precipitating low-energy electrons in this afternoon region is modulated by this boundary wave and produces the periodic UV emission features. The results of this study support the view that large-scale oscillations of magnetospheric boundaries, possibly associated with the Kelvin-Helmholtz instability, can modulate currents, particles, and auroral forms.

  12. Knob fields in the Terra Cimmeria/Terra Sirenum region of Mars: Stratigraphy, mineralogy and morphology

    NASA Astrophysics Data System (ADS)

    Wendt, Lorenz; Bishop, Janice L.; Neukum, Gerhard

    2013-07-01

    We investigate the stratigraphy, morphology and mineralogy of five major knob fields in the region between Terra Cimmeria and Terra Sirenum on Mars based on HRSC, CTX, MOC and HiRISE imagery together with hyperspectral data from CRISM. The knob fields comprise Ariadnes Colles, Atlantis Chaos and Gorgonum Chaos and further, unnamed fields of mounds. They have been mapped in previous studies as Hesperian or Amazonian units and are located within the shoreline of the proposed "Eridania lake", the putative source of Ma'adim Vallis. The mounds contain Mg/Fe-bearing phyllosilicates and locally Al-rich phyllosilicates. Our geological mapping shows that the knob fields have a late Noachian age, which indicates later phyllosilicate formation than typically observed on Mars. The knob fields formed by alteration of the "Electris deposit", an airfall deposit possibly rich in basaltic glass (Grant, J.A., Schultz, P.H. [1990]. Icarus 84, 166-195), in local depressions, possibly in the Eridania lake. The spectroscopic detection of phyllosilicates here may indicate that liquid water persisted longer in this region than elsewhere on Mars. The knob fields are embayed by the Hesperian ridged plains. Numerous valleys carve into the ridged plains and document that the aqueous history of this region continued into the Hesperian and Amazonian. The study area is traversed by the Sirenum Fossae. These graben appear to post-date the aqueous activity in the study area except in the Gorgonum basin, where a lake developed after their formation.

  13. [Characteristics and Inputs of Cd Contamination in Paddy Soils in Typical Mining and Industrial Areas in Youxian County, Hunan Province].

    PubMed

    Zhang, Min; Wang Mei-e; Chen, Wei-ping; Niu, Jun-jie

    2015-04-01

    In order to explore input pathways and pollution characteristics of Cd contamination in paddy soil in Youxian, Hunan Province, Cd contents in paddy soils, sediments of irrigation canals, typical mineral and industrial products such as coal, gangue and cement were analyzed. It was suggested that the average contents of Cd both in surface paddy soil and the corresponding natural soil were higher than the soil quality standard 0.3 mg x kg(-1). Cd contents in gangue and cement were similar as those in the corresponding natural soils. The atmosphere deposition of Cd was the highest in factory area. The profiles of Cd in 0-100 cm paddy soil and 0-40 cm in natural soils varied significantly from the upper to the lower layer. Cd contents in 0-40 cm layer in paddy soil were much higher than those in corresponding natural soils in mineral and mineral-factory areas. The potentiality for downward movement of Cd in soils in mineral area was the highest among the three studied areas. It suggested Cd contents in surface paddy soil were higher in upwind areas than those in downwind areas in mineral-factory and factory areas. It could be concluded that the main input pathways of Cd in mineral and mineral-factory. areas were from irrigation water, while contribution of atmosphere deposition in mineral-factory and factory areas was also very significant. PMID:26164922

  14. Stess field in Brazil: First and Second-Order Stress Patterns: Examples of Regional Forces Controlling the Stress Field

    NASA Astrophysics Data System (ADS)

    Dias, F.; Assumpcao, M.

    2012-12-01

    The knowledge of stress field is fundamental not only to understand driving forces and plate deformation as also it helps in the study of intraplate seismicity. In Brazil, we find reverse, strike-slip and normal mechanisms that indicates a variable stress field. The stress field has been mainly obtained using focal mechanism results and a few breakout data and in-situ measurements. However the stress field is still poorly known in Brazil. Recent earthquake focal mechanisms were determinate using P-wave modeling of seismogram stacks of several teleseismic stations ( > 30°) grouped according to distance and azimuth and first motion polarities. Every record was visually inspected and those with a good signal/noise ratio (SNR) were grouped in latitude-longitude windows of ten degrees and stacked. We usually consider groups with at least two stations, but, in sometimes a good record of single station with different azimuth was also used to constrain the focal depth. The P, pP, sP wavetrains of the stacked signals were modelled using the hudson96 program of Herrman seismology package (Herrman, 2002). We also determinate moment tensor of same events in the central region. The major difficulty is to determinate focal mechanism of low magnitudes events (< 4.0 mb) using distants seismograph stations. The central region shows a purely compressional pattern which are predicted by regional theoretical models (Richardson & Coblentz, 1996 and the TD0 model of Lithgow& Bertelloni, 2004). Meanwhile in the Amazonic region we find a SHmax from E-W to SE-NW probably caused by Caribbean and South American plates interaction (Meijer, 1995). In NE region, the compression rotates following the coast line which indicates an important component regional present in stress field spreading effects due to the continental/oceanic crustal (Assumpção, 1998) and cases of stress caused by sedimentary load in Amazon Fan in agreement local theoretical models (Watts et al., 2009). We determinate the focal mechanism of several events in Brazil using different techniques according to the available data. We find examples of stress perturbations induced by local effects (e.g. flexure and continental spreading) . The results of this work should be useful for futures stress field numerical modeling. References: Assumpção,M.,1998.Seismicity and stresses in the Brazilian passive margin. Bull. Seism. Soc. Am., 88 (1),160-169. Coblentz, D.D. and Richardson, R.M. 1996. Analysis of the South America intraplate stress field. Journal of Geophysical Research 101: 8.643-8.657. Herrmann, R. B. (2002). Computer programs in seismology, St. Louis University Earthquake Center, St. Louis, Missouri, www.eas.slu .edu/eqc/eqccps.html. Lithgow-Bertelloni, C., & J.H. Guynn, 2004. Origin of the lithospheric stress field. J. Geophys. Res., 109, B01408, doi:10.1029/2003JB002467. Meijer, P.T., 1995. Dynamics of active continental margins: the Andes and the Aegean regions. PhD Thesis, Utrecht University, The Netherlands. Watts, A. B., M. Rodger, C. Peirce, C. J. Greenroyd, and R. W. Hobbs (2009), Seismic structure, gravity anomalies, and flexure of the Amazon continental margin, NE Brazil, J. Geophys. Res., 114, B07103, doi:10.1029/2008JB006259.

  15. Bow shock contributions to region 1 field-aligned current: A new result from global MHD simulations

    Microsoft Academic Search

    X. C. Guo; C. Wang; Y. Q. Hu; J. R. Kan

    2008-01-01

    We present a new result, based on a global MHD simulation model, that the bow shock contributes significantly to the region 1 field-aligned current (FAC) under strong southward interplanetary magnetic field conditions. More than 50 percent of the total region 1 FAC may originate from the bow shock in certain circumstances. Stronger southward interplanetary magnetic field, higher solar wind speed,

  16. Producing Large Transient Electromagnetic Fields in a Small Region: An Electromagnetic Implosion

    Microsoft Academic Search

    Carl E. Baum

    One approach to producing a large, fast transient electromagnetic field in a small region consists of focusing an incoming approximately spherical wave on the position of interest. This paper discusses some of the design features involving a prolate spheroidal reflector for this purpose.

  17. VECTOR MAGNETIC FIELDS AND CURRENT HELICITIES IN CORONAL HOLES AND QUIET REGIONS

    SciTech Connect

    Yang Shuhong; Zhang Jun; Li Ting [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Ding Mingde, E-mail: shuhongyang@nao.cas.cn, E-mail: zjun@nao.cas.cn, E-mail: liting@nao.cas.cn, E-mail: dmd@nju.edu.cn [Department of Astronomy, Nanjing University, Nanjing 210093 (China)

    2011-01-01

    In the solar photosphere, many properties of coronal holes (CHs) are not known, especially vector magnetic fields. Using observations from Hinode, we investigate vector magnetic fields, current densities, and current helicities in two CHs, and compare them with two normal quiet regions (QRs) for the first time. We find that the areas where large current helicities are located are mainly co-spatial with strong vertical and horizontal field elements both in shape and in location. In the CHs, horizontal magnetic fields, inclination angles, current densities, and current helicities are larger than those in the QRs. The mean vertical current density and current helicity in the CHs and QRs, averaged over all the observed areas including the CHs and QRs, are approximately 0.008 A m{sup -2} and 0.005 G{sup 2} m{sup -1}, respectively. The mean current density in magnetic flux concentrations where the vertical fields are stronger than 100 G is as large as 0.012 {+-} 0.001 A m{sup -2}, consistent with that in the flare productive active regions. Our results imply that the magnetic fields, especially the strong fields, both in the CHs and in the QRs are nonpotential.

  18. Anaerobic N mineralization in paddy soils in relation to inundation management, physicochemical soil fractions, mineralogy and soil properties

    NASA Astrophysics Data System (ADS)

    Sleutel, Steven; Kader, Mohammed Abdul; Ara Begum, Shamim; De Neve, Stefaan

    2013-04-01

    Anaerobic N mineralization measured from (saturated) repacked soil cores from 25 paddy fields in Bangladesh and was previously found to negatively related to soil N content on a relative basis. This suggests that other factors like soil organic matter (SOM) quality or abiotic factors instead control the anaerobic N mineralization process. We therefore assessed different physical and chemical fractions of SOM, management factors and various soil properties as predictors for the net anaerobic N mineralization. 1° First, we assessed routinely analyzed soil parameters (soil N and soil organic carbon, texture, pH, oxalate- and pyrophosphate-extractable Fe, Al, and Mn, fixed-NH4 content). We found no significant influences of neither soil mineralogy nor the annual length of inundation on soil N mineralization. The anaerobic N mineralization correlated positively with Na-pyrophosphate-extractable Fe and negatively with pH (both at P<0.01). At this stage it is, however, not known if these relations between net evolution of NH4 and pH and Fe content are causal or indirect. 2° Second, the 25 samples collected from farmers' fields were physically fractionated into particulate OM and silt and clay associated OM. The silt and clay sized OM was further chemically fractionated by oxidation with 6%NaOCl to isolate an oxidation-resistant OM fraction, followed by extraction of mineral bound OM with 10%HF thereby isolating the HF-resistant OM. None of the physicochemical SOM fractions were found useful predictors anaerobic N mineralization. The linkage between these chemical soil N fractions and N supplying processes actually occurring in the soil thus appears to be weak. Regardless, we hypothesize that variation in strength of N-mineral and N-OM linkages is likely to explain variation in bio-availability of organic N and proneness to mineralization. Yet, in order to separate kinetically different soil N fractions we then postulated that an alternative approach would be required, which instead isolates soil N fractions on the basis of bonding strength. In this respect bonding strength should be seen as opposite of proneness to dissolution of released N into water, the habitat of soil microorganisms mediating soil N mineralization. We hypothesize that soil N extracted by water at increasing temperatures would reflect such N fractions with increasing bonding strength, in turn equivalent to decreasing bio-availability. Although water has frequently been used to extract labile SOM, its use has mostly been limited to 100°C. 3° Third we developed sub critical water extraction (SCWE) at 100°C, 150°C and 200°C to isolate SOM fractions from the set of 25 paddy soil samples. In all cases, SCWE organic carbon (SCWE-OC) and N (SCWE-N) increased exponentially with the increase of temperature. SCWE preferentially extracted N over OC with increasing temperature. The efficiency of SCWE and the selectivity towards N were both lower in soils with increasingly reactive clay mineralogy. No correlations were found between the SCWE fractions and anaerobic N mineralization rate. In conclusion, SOM quantity and SOM quality, here represented by C and N distribution over physicochemical fractions, don't seem to dominantly determine anaerobic N mineralization in primarily young floodplain paddy soils. Other factors with exceeding control (pH and pyrophosphate extractable Fe) appear to exist. Possibly, the specific young genesis stage of most of the soils included (termed 'floodplain' soils) results in a limited availability of readily reducible Fe. Being an important alternative electron acceptor under submerged conditions, the availability of Fe, which is also controlled by pH, may be a bottleneck in the anaerobic N mineralization process. This needs to be further investigated by controlled incubation experiments with detailed follow-up of pH, redox potential, Fe in solution and mineral N.

  19. Self-similar fragmentation regulated by magnetic fields in a region forming massive stars.

    PubMed

    Li, Hua-bai; Yuen, Ka Ho; Otto, Frank; Leung, Po Kin; Sridharan, T K; Zhang, Qizhou; Liu, Hauyu; Tang, Ya-Wen; Qiu, Keping

    2015-04-23

    Most molecular clouds are filamentary or elongated. For those forming low-mass stars (<8 solar masses), the competition between self-gravity and turbulent pressure along the dynamically dominant intercloud magnetic field (10 to 100 parsecs) shapes the clouds to be elongated either perpendicularly or parallel to the fields. A recent study also suggested that on the scales of 0.1 to 0.01 parsecs, such fields are dynamically important within cloud cores forming massive stars (>8 solar masses). But whether the core field morphologies are inherited from the intercloud medium or governed by cloud turbulence is unknown, as is the effect of magnetic fields on cloud fragmentation at scales of 10 to 0.1 parsecs. Here we report magnetic-field maps inferred from polarimetric observations of NGC 6334, a region forming massive stars, on the 100 to 0.01 parsec scale. NGC 6334 hosts young star-forming sites where fields are not severely affected by stellar feedback, and their directions do not change much over the entire scale range. This means that the fields are dynamically important. The ordered fields lead to a self-similar gas fragmentation: at all scales, there exist elongated gas structures nearly perpendicular to the fields. Many gas elongations have density peaks near the ends, which symmetrically pinch the fields. The field strength is proportional to the 0.4th power of the density, which is an indication of anisotropic gas contractions along the field. We conclude that magnetic fields have a crucial role in the fragmentation of NGC 6334. PMID:25822792

  20. Influence of asymmetries and guide fields on the magnetic reconnection diffusion region in collisionless space plasmas

    NASA Astrophysics Data System (ADS)

    Eastwood, J. P.; Phan, T. D.; Øieroset, M.; Shay, M. A.; Malakit, K.; Swisdak, M.; Drake, J. F.; Masters, A.

    2013-12-01

    Collisionless magnetic reconnection is considered to be one of the most important plasma phenomena because it governs the transport of energy, momentum and plasma in a wide variety of situations. In particular, understanding the central diffusion region is crucial to gaining a full understanding of the physics of reconnection. Although most diffusion region studies have historically focussed on simple reconnection geometries (antiparallel fields and symmetric reconnecting plasmas), in recent years significant progress has been made in understanding the impact of plasma asymmetries, guide fields and flow shear on collisionless diffusion region physics. Here we present a review of this recent progress, which is based both on supercomputer simulations and increasingly detailed multi-point satellite measurements of collisionless magnetic reconnection in space plasmas.

  1. Regional Field Verification -- Case Study of Small Wind Turbines in the Pacific Northwest: Preprint

    SciTech Connect

    Sinclair, K.

    2005-05-01

    The U.S. Department of Energy/National Renewable Energy Laboratory's (DOE/NREL) Regional Field Verification (RFV) project supports industry needs for gaining initial field operation experience with small wind turbines and verify the performance, reliability, maintainability, and cost of small wind turbines in diverse applications. In addition, RFV aims to help expand opportunities for wind energy in new regions of the United States by tailoring projects to meet unique regional requirements and document and communicate the experience from these projects for the benefit of others in the wind power development community and rural utilities. Between August 2003 and August 2004, six turbines were installed at different host sites. At least one year of data has been collected from five of these sites. This paper describes DOE/NREL's RFV project, reviews some of the lessons learned with regards to small wind turbine installations, summarizes operations data from these sites, and provides preliminary BOS costs.

  2. Nightside Region-2 electric field evolution during substorm growth and expansion phases

    NASA Astrophysics Data System (ADS)

    Zou, S.; Lyons, L.; Boudouridis, A.; Ruohoniemi, M.

    2007-12-01

    Observations of the strong coupling of Harang reversal region dynamics to substorm evolutions suggest that nightside Region-2 physics is closely related with substorm dynamics. We use SuperDARN HF radar and DMSP observations to evaluate the Region-2 electric field evolution for nine substorm events. Auroral images from the IMAGE spacecraft, when available, are superposed with these ionospheric convection patterns to better illustrate the relation between the Region-2 electric fields near the Harang reversal region and the substorm dynamics. Based on these nine events, we found that the Harang reversal forms and becomes well defined during the growth phase of all the nine substorms. Azimuthal flows equatorward of the Harang reversal increase and reach at least ~500 m/s. These observational evidences indicate that shielding, subauroral ion drifts (SAIDS), and the Harang reversal evolve together as part of the growth phase development of the Region-2 system and they become well developed during the substorm growth phase. In addition, we find that substorm onset seems to occur slightly poleward of the center of the Harang flow shear and in the weak equatorward flows near the western edge of the dawn convection cell.

  3. Rotating coil field measurement of superconducting magnet for BEPCII interaction region

    NASA Astrophysics Data System (ADS)

    Peng, Quanling; Ren, Fanglin; Yin, Baogui; Wu, Yingzhi; Dong, Lan; Sun, Zhirui

    2011-06-01

    Two multifunction superconducting magnets in the interaction region (IR) for Beijing electron positron collider upgrade project (BEPCII) have been measured in BESIII detector hall in 2007. Each superconducting magnet package contains multiple concentric layers with several function magnets called as a vertical focusing quadrupole (SCQ), a horizontal corrector (HDC/SCB), a vertical corrector (VDC), a skew quadrupole (SKQ) and three anti-solenoids (AS1, AS2 and AS3) to compensate the experimental detector solenoid field. All these function magnets SCQs, SCB/HDCs, VDCs and SKQs have been measured using two rotating coils. Their integral fields, their high order harmonics contents and the local fields along the beam line are obtained in detail with the rotating coil probe system. Comparing the results to the stretched wire, the differences for the integral fields are less than 0.2%. As a result, the method presented in this paper can be used as an absolute field measurement in our lab.

  4. Earth's Magnetic Field Monitoring in the AMAS Region with the NANOSATC-BR1 Nanosatellite

    NASA Astrophysics Data System (ADS)

    Bilibio, Andreos Vestena; Schuch, Nelson Jorge; Denardini, Clezio Marcos; Mendes, Odim; Marchezi, Jose Paulo; Cupertino Durao, Otavio S.

    The objectives of the Southern Regional Space Research Center's Solar Physics and Interplanetary Medium & Magnetosphere Laboratory is to study Geomagnetic field techniques in experimental measurements and monitoring changes in the South Atlantic Magnetic Anomaly (SAMA) region by continuous measurements of the three orthogonal components of Geomagnetic field: H (North-South), D (East- West) and Z (vertical down). The observation measurements are made at the Southern Space Observatory - SSO/CRS/INPE - MCTI in São Martinho da Serra (29.43º S, 53.82º W, elevation 488m), southern Brazil. Nanosatellites, such as CubeSats, have been used in many scientific space applications. The NANOSATC-BR1 is the second nanosatellite of the NANOSATC-BR, Development of CubeSats Program, a Brazilian Partnership between INPE/MCTI & UFSM. The NANOSATC-BR1 Project has been planed, designed and executed in the facilities built on the partnership between CRS/INPE/MCTI and the Federal University of Santa Maria (LACESM/CT-UFSM), with its undergraduate students. The nanosatellite has three payloads: two integrated circuits (designed in Brazil for space use) to be tested for radiation resistance and a fluxgate magnetometer (model XEM - 12.10 FGM), that will be used for geomagnetic field measurements over the AMAS region. The magnetometer is a magnetic field sensor based on the Hall effect. The instrument will perform data collection in a frequency of three samples per seconds, with a resolution of 15 nT for magnetic field intensity. The intention for future studies is to do comparison between SSO data and monitoring the spatial and temporal variation of magnetic field intensity in AMAS region.

  5. Processes involved in formation and emission of methane in rice paddies

    Microsoft Academic Search

    Helmut Schütz; Wolfgang Seiler; Ralf Conrad

    1989-01-01

    The seasonal change of the rates of production and emission of methane were determined under in-situ conditions in an Italian rice paddy in 1985 and 1986. The contribution to total emission of CH4 of plant-mediated transport, ebullition, and diffusion through the flooding water was quantified by cutting the plants and by trapping emerging gas bubbles with funnels. Both production and

  6. Interactions between selected PAHs and the microbial community in rhizosphere of a paddy soil

    Microsoft Academic Search

    Yu H. Su; Xue Y. Yang

    2009-01-01

    This study investigated the interaction of three polycyclic aromatic hydrocarbons (PAHs), i.e., naphthalene (NAP), phenanthrene (PHN), and pyrene (PYR), with the microbial community in the rhizosphere of a paddy soil and the influence of the rice (Oryza sativa) rhizosphere on the microbial community structure. A range of initial NAP, PHN and PYR levels in soil (50–200, 18–72, and 6.6–26.6 mg kg?1,

  7. Effect of Size of Paddy Straw on Nutrient Utilization in Goats

    Microsoft Academic Search

    M. K. Das; S. Biswas; T. K. Ghosh

    1992-01-01

    Sixteen Black Bengal goats (10–12 months of age) were divided into 4 equal groups and fed 1 cm (T1), 2 cm (T2), 3 cm (T3) and 4 cm (T4) long paddy straw ad libitum along with 90 g ground nut cake for a period of 90 days. Daily dry matter intake was similar in all the groups. The digestibilities of

  8. Survey of flue gas desulfurization systems, Paddy's Run Station, Louisville Gas and Electric. Final report

    Microsoft Academic Search

    Isaacs

    1975-01-01

    The report gives results of a survey of the flue gas desulfurization (FGD) system on Unit 6 of Louisville Gas and Electric Co.'s Paddy's Run Power Station. The closed-loop system, which was started up in April 1973, uses a slurry of carbide lime in a marble-bed scrubber. The carbide lime, a waste by-product from a nearby acetylene manufacturing plant, contains

  9. TWIST AND CONNECTIVITY OF MAGNETIC FIELD LINES IN THE SOLAR ACTIVE REGION NOAA 10930

    SciTech Connect

    Inoue, S. [National Institute of Information and Communications Technology (NICT), 4-2-1, Nukui-Kitamachi, koganei, Tokyo 184-8795 (Japan); Kusano, K.; Yamamoto, T. T. [Solar-Terrestrial Environment Laboratory, Nagoya University Furo-cho, Chikusa-ku, Nagoya, 464-8601 (Japan); Magara, T. [Department of Astronomy and Space Science, School of Space Research, Kyung Hee University, 1, Seocheon-dong, Giheung-gu, Yongin, Gyeonggi-do, 446-701 (Korea, Republic of); Shiota, D., E-mail: inosato@nict.go.jp [Advanced Science Institute, RIKEN - Institute of Physics and Chemical Research, Wako, Saitama 351-0198 (Japan)

    2011-09-10

    Twist and connectivity of magnetic field lines in the flare-productive active region NOAA 10930 are investigated in terms of the vector magnetograms observed by the Solar Optical Telescope on board the Hinode satellite and the nonlinear force-free field (NLFFF) extrapolation. First, we show that the footpoints of magnetic field lines reconstructed by the NLFFF correspond well to the conjugate pair of highly sheared flare ribbons on the Ca II images, which were observed by Hinode as an X3.4 class flare on 2006 December 13. This demonstrates that the NLFFF extrapolation may be used to analyze the magnetic field connectivity. Second, we find that the twist of magnetic field lines anchored on the flare ribbons increased as the ribbons moved away from the magnetic polarity inversion line in the early phase of the flare. This suggests that magnetic reconnection might commence from a region located below the most strongly twisted field. Third, we reveal that the magnetic flux twisted more than a half turn and gradually increased during the last one day prior to the onset of the flare, and that it quickly decreased for two hours after the flare. This is consistent with the store-and-release scenario of magnetic helicity. However, within this active region, only a small fraction of the flux was twisted by more than one full turn and the field lines that reconnected first were twisted less than one turn. These results imply that the kink mode instability could hardly occur, at least before the onset of flare. Based on our results, we discuss the trigger process of solar flares.

  10. Characteristics of ionospheric convection and field-aligned current in the dayside cusp region

    NASA Technical Reports Server (NTRS)

    Lu, G.; Lyons, L. R.; Reiff, P. H.; Denig, W. F.; Beaujardiere, O. De LA; Kroehl, H. W.; Newell, P. T.; Rich, F. J.; Opgenoorth, H.; Persson, M. A. L.

    1995-01-01

    The assimilative mapping of ionospheric electrodynamics (AMIE) technique has been used to estimate global distributions of high-latitude ionospheric convection and field-aligned current by combining data obtained nearly simultaneously both from ground and from space. Therefore, unlike the statistical patterns, the 'snapshot' distributions derived by AMIE allow us to examine in more detail the distinctions between field-aligned current systems associated with separate magnetospheric processes, especially in the dayside cusp region. By comparing the field-aligned current and ionospheric convection patterns with the corresponding spectrograms of precipitating particles, the following signatures have been identified: (1) For the three cases studied, which all had an IMF with negative y and z components, the cusp precipitation was encountered by the DMSP satellites in the postnoon sector in the northern hemisphere and in the prenoon sector in the southern hemisphere. The equatorward part of the cusp in both hemispheres is in the sunward flow region and marks the beginning of the flow rotation from sunward to antisunward. (2) The pair of field-aligned currents near local noon, i.e., the cusp/mantle currents, are coincident with the cusp or mantle particle precipitation. In distinction, the field-aligned currents on the dawnside and duskside, i.e., the normal region 1 currents, are usually associated with the plasma sheet particle precipitation. Thus the cusp/mantle currents are generated on open field lines and the region 1 currents mainly on closed field lines. (3) Topologically, the cusp/mantle currents appear as an expansion of the region 1 currents from the dawnside and duskside and they overlap near local noon. When B(sub y) is negative, in the northern hemisphere the downward field-aligned current is located poleward of the upward current; whereas in the southern hemisphere the upward current is located poleward of the downward current. (4) Under the assumption of quasi-steady state reconnection, the location of the separatrix in the ionosphere is estimated and the reconnection velocity is calculated to be between 400 and 550 m/s. The dayside separatrix lies equatorward of the dayside convection throat in the two cases examined.

  11. Chronologic Studies of Lava Flow Fields in the Southern Tharsis Region of Mars

    NASA Astrophysics Data System (ADS)

    Crown, D. A.; Berman, D. C.; Herrick, E.

    2014-12-01

    The current investigation examines the styles and sequences of volcanism in the southern Tharsis region of Mars. High-resolution images are being used to produce geologic and flow field maps of the region south of Arsia Mons and in Daedalia Planum. Mars Reconnaissance Orbiter Context Camera (CTX; ~5 m/pixel) images allow reconstruction of complex volcanic surfaces, including delineation of individual flow lobes and superposition relationships within a flow field. Flow field mapping reveals complex flow patterns and local interfingering and overlapping relationships. Populations of small, superposed impact craters are used to derive relative and absolute age constraints for individual flows and flow sequences. Mapping has revealed differences in flow morphology, flow age, and flow surface texture across the region. Results to-date show a general progression from younger (~100 My-old) flows with elongate, sinuous morphologies to the northeast (closer to Arsia Mons) to older (~500 My- to ~1 Gy-old) broader lobes and sheet flows to the southwest. At the southern margin of the Tharsis region, older (~3.7 Gy) volcanic plains have been identified where Tharis flows contact the ancient highlands.

  12. Three-dimensional magnetic field topology in a region of solar coronal heating.

    PubMed

    Solanki, S K; Lagg, A; Woch, J; Krupp, N; Collados, M

    2003-10-16

    Flares and X-ray jets on the Sun arise in active regions where magnetic flux emerges from the solar interior amd interacts with the ambient magnetic field. The interactions are believed to occur in electric current sheets separating regions of opposite magnetic polarity. The current sheets located in the corona or upper chromosphere have long been thought to act as an important source of coronal heating, requiring their location in the corona or upper chromosphere. The dynamics and energetics of these sheets are governed by a complex magnetic field structure that, until now, has been difficult to measure. Here we report the determination of the full magnetic vector in an interaction region near the base of the solar corona. The observations reveal two magnetic features that characterize young active regions on the Sun: a set of rising magnetic loops and a tangential discontinuity of the magnetic field direction, the latter being the observational signature of an electric current sheet. This provides strong support for coronal heating models based on the dissipation of magnetic energy at current sheets. PMID:14562096

  13. Extensive lava flow fields on Venus: Preliminary investigation of source elevation and regional slope variations

    NASA Technical Reports Server (NTRS)

    Magee-Roberts, K.; Head, James W., III; Lancaster, M. G.

    1992-01-01

    Large-volume lava flow fields have been identified on Venus, the most areally extensive of which are known as fluctus and have been subdivided into six morphologic types. Sheetlike flow fields (Type 1) lack the numerous, closely spaced, discrete lava flow lobes that characterize digitate flow fields. Transitional flow fields (Type 2) are similar to sheetlike flow fields but contain one or more broad flow lobes. Digitate flow fields are divided further into divergent (Types 3-5) and subparallel (Type 6) classes on the basis of variations in the amount of downstream flow divergence. As a result of our previous analysis of the detailed morphology, stratigraphy, and tectonic associations of Mylitta Fluctus, we have formulated a number of questions to apply to all large flow fields on Venus. In particular, we would like to address the following: (1) eruption conditions and style of flow emplacement (effusion rate, eruption duration), (2) the nature of magma storage zones (presence of neutral buoyancy zones, deep or shallow crustal magma chambers), (3) the origin of melt and possible link to mantle plumes, and (4) the importance of large flow fields in plains evolution. To answer these questions we have begun to examine variations in flow field dimension and morphology; the distribution of large flow fields in terms of elevation above the mean planetary radius; links to regional tectonic or volcanic structures (e.g., associations with large shield edifices, coronae, or rift zones); statigraphic relationships between large flow fields, volcanic plains, shields, and coronae; and various models of flow emplacement in order to estimate eruption parameters. In this particular study, we have examined the proximal elevations and topographic slopes of 16 of the most distinctive flow fields that represent each of the 6 morphologic types.

  14. SITE IVESTIGATIONS (SI) AND FIELD INVESTIGATIONS (FI) OF REGION 4 SUPERFUND HAZARDOUS WASTE SITES: AUGUST 2007 ? SEPTEMBER 2008

    EPA Science Inventory

    Site Investigations (SIs) and Field Investigations (FIs) conducted by the Region 4 Science and Ecosystem Support Division (SESD) require developing and implementing work plans which include a Project Operations Plan, Field Sampling and Analysis Plan, Quality Assurance Project Pla...

  15. SITE IVESTIGATIONS (SI) AND FIELD INVESTIGATIONS (FI) OF REGION 4 SUPERFUND HAZARDOUS WASTE SITES: OCTOBER 2005 ? SEPTEMBER 2006

    EPA Science Inventory

    Site Investigations (SIs) and expanded Field Investigations (FIs) conducted by the Region 4 Science and Ecosystem Support Division (SESD) require developing and implementing work plans which include a Project Operations Plan, Field Sampling and Analysis Plan, Quality Assurance Pl...

  16. SITE INVESTIGATIONS (SI) AND FIELD INVESTIGATIONS (FI) OF REGION 4 SUPERFUND HAZARDOUS WASTE SITES: OCTOBER 2006 ? JULY 2007

    EPA Science Inventory

    Site Investigations (SIs) and Field Investigations (FIs) conducted by the Region 4 Science and Ecosystem Support Division (SESD) require developing and implementing work plans which include a Project Operations Plan, Field Sampling and Analysis Plan, Quality Assurance Project Pla...

  17. An assessment of energy use efficiency and sensitivity analysis of inputs in rice paddy production

    NASA Astrophysics Data System (ADS)

    Mohammadi, A.; Rafiee, S.; Jafari, A.; Keyhani, A.

    2012-04-01

    This research studies the energy balance between the inputs and the output and estimation of inputs sensitivity for paddy production in Golestan province, Iran. The sensitivity of energy inputs was estimated using the marginal physical productivity (MPP) method and partial regression coefficients on rice yield. The results indicated that total energy inputs were found to be 29668 MJ ha-1. The results showed that among energy inputs, the share of chemical fertilizers was highest with 39% followed by water for irrigation with 32%. Energy use efficiency and energy productivity were found to be 2.5 and 0.2 ¬kg MJ-1, respectively. Sensitivity analysis indicates that highest MPP was for machinery energy, followed by human labour energy. The MPP estimated for biocides energy was found negative, indicating that biocides energy consumption is high in paddy production. It is suggested that specific policy is to be taken to increase yield by raising partial productivity of energy inputs without depending on mainly non-renewable energy sources such as chemical fertilizers and biocides that create environmental risk problems. Keywords:Energy input, Sensitivity analysis, Chemical fertilizers, Paddy

  18. The Dynamics of Energy and CO2 Transport above a Subtropical Rice Paddy

    NASA Astrophysics Data System (ADS)

    Hsieh, Cheng-I.; Huang, Cheng-Wei; Cheng, Shih-Min

    2014-05-01

    An eddy-covariance system was established to understand the dynamics of turbulent transport of sensible heat, water vapor, and CO2 above a subtropical rice paddy in north Taiwan (24°48'07.958"N, 121°47'58.665"E). The results showed that, during crop season, about 25% of net radiation was used for latent heat flux, 10% for sensible heat flux, and the rest (65%) was absorbed by the water and soil in the rice paddy. However, during fallow period, where there was no rice in the paddy, both water vapor and sensible heat fluxes occupied about 18% of the net radiation. Also, Penman-Monteith equation was found to reproduce the water vapor flux well with surface resistance close to 190 s m-1. We also found that, under small Bowen ratio (< 0.2) conditions, water vapor and CO2 were transported more efficiently than heat. However, when Bowen ration was large (> 0.5), sensible heat was transported about 10% more efficiently than water vapor and CO2. During crop season the maximum CO2 uptake was about 22 micro mol m-2 s-1. In fallow period, the maximum CO2 emission rate from the soil-water surface was around 5 micro mol m-2 s-1, which was about the same as the growing season.

  19. Immobilization of Cd in a paddy soil using moisture management and amendment.

    PubMed

    Li, Jianrui; Xu, Yingming

    2015-03-01

    To offer basis for remediation of Cd-polluted paddy soil under reasonable water condition, pot experiment was conducted to study the effects of moisture management and amendment on the immobilization of Cd in paddy soil. Application of sepiolite in combination with phosphate fertilizer reduced exchangeable Cd by 18.2%, 13.7% and 12.5%, brown rice Cd by 52.3%, 46.0% and 46.8%, under continuous flooding, conventional irrigation and wetting irrigation, respectively, compared to the control groups. Under no amendments, the content of Fe(II) in root coating in the continuous flooding treatment was 2.3 and 3.6 times of that in the conventional and wetting irrigation treatments, but Cd content in root coating in the continuous flooding treatment was only 82.6% and 73.8% of that in the conventional and wetting irrigation treatments. Amendments application increased Fe(II) in root coating by 40.1%, 70.2% and 78.0%, but reduced the Cd content in root coating by 35.3%, 42.4% and 38.6% under continuous flooding, conventional irrigation and wetting irrigation, respectively. The lower availability of Cd in soil and the competition for adsorption sites in root coating of rice plant between Cd(2+) and Fe(2+) etc. reduced form bivalent ions in paddy soil resulted in lower Cd concentrations in brown rice in amended soil treatments. PMID:25497757

  20. Immobilization of Cd in paddy soil using moisture management and amendment.

    PubMed

    Li, Jianrui; Xu, Yingming

    2015-04-01

    To offer scientific data support for remediation of Cd-contaminated paddy soils under reasonable water condition, pot experiment was conducted to study the effects of moisture management and amendments on Cd immobilization in a paddy soil. Application of biochar combined with organic fertilizer reduced the exchangeable Cd by 20.4, 15.7, and 13.0% and brown rice Cd by 43.8, 35.5, and 42.1% under continuous flooding, conventional irrigation, and wetting irrigation, respectively, compared to the controls. Under no amendments, the content of Fe(II) in root coating in the continuous flooding treatment was 2.3 and 3.6 times of that in the conventional and wetting irrigation treatments, but Cd in root coating in the continuous flooding treatment was only 82.6 and 73.8% of that in the conventional and wetting irrigation treatments. Applying amendments increased the Fe(II) in root coating by 27.3, 59.1, and 65.0% but reduced the Cd in root coating by 33.6, 26.5, and 25.1% under continuous flooding, conventional irrigation, and wetting irrigation, respectively. The lower bioavailability of Cd in paddy soil and the competition for adsorption sites in root coating of rice plant between Cd(2+) and Fe(2+) reduced from bivalent ions jointly caused the lower brown rice Cd in amended soils. PMID:25388557

  1. Effect of ferrihydrite biomineralization on methanogenesis in an anaerobic incubation from paddy soil

    NASA Astrophysics Data System (ADS)

    Zhuang, Li; Xu, Jielong; Tang, Jia; Zhou, Shungui

    2015-05-01

    Microbial reduction of Fe(III) can be one of the major factors controlling methane production from anaerobic sedimentary environments, such as paddy soils and wetlands. Although secondary iron mineralization following Fe(III) reduction is a process that occurs naturally over time, it has not yet been considered in methanogenic systems. This study performed a long-term anaerobic incubation of a paddy soil and ferrihydrite-supplemented soil cultures to investigate methanogenesis during ferrihydrite biomineralization. The results revealed that the long-term effect of ferrihydrite on methanogenesis may be enhancement rather than suppression documented in previous studies. During initial microbial ferrihydrite reduction, methanogenesis was suppressed; however, the secondary minerals of magnetite formation was simultaneous with facilitated methanogenesis in terms of average methane production rate and acetate utilization rate. In the phase of magnetite formation, microbial community analysis revealed a strong stimulation of the bacterial Geobacter, Bacillus, and Sedimentibacter and the archaeal Methanosarcina in the ferrihydrite-supplemented cultures. Direct electric syntrophy between Geobacter and Methanosarcina via conductive magnetite is the plausible mechanism for methanogenesis acceleration along with magnetite formation. Our data suggested that a change in iron mineralogy might affect the conversion of anaerobic organic matter to methane and might provide a fresh perspective on the mitigation of methane emissions from paddy soils by ferric iron fertilization.

  2. The Dynamics of Energy and CO2 Transport above a Subtropical Rice Paddy

    NASA Astrophysics Data System (ADS)

    Hsieh, C. I.

    2014-12-01

    An eddy-covariance system was established to understand the dynamics of turbulent transport of sensible heat, water vapor, and CO2 above a subtropical rice paddy in north Taiwan (24°48'07.958"N, 121°47'58.665"E). The results showed that, during crop season, about 25% of net radiation was used for latent heat flux, 10% for sensible heat flux, and the rest (65%) was absorbed by the water and soil in the rice paddy. However, during fallow period, where there was no rice in the paddy, both water vapor and sensible heat fluxes occupied about 18% of the net radiation. Also, Penman-Monteith equation was found to reproduce the water vapor flux well with surface resistance close to 190 s m-1. We also found that, under small Bowen ratio (< 0.2) conditions, water vapor and CO2 were transported more efficiently than heat. However, when Bowen ration was large (> 0.5), sensible heat was transported about 10% more efficiently than water vapor and CO2. During crop season the maximum CO2 uptake was about 22 micro mol m-2 s-1. In fallow period, the maximum CO2 emission rate from the soil-water surface was around 5 micro mol m-2 s-1, which was about the same as the growing season.

  3. Rice (Oryza sativa L) plantation affects the stability of biochar in paddy soil.

    PubMed

    Wu, Mengxiong; Feng, Qibo; Sun, Xue; Wang, Hailong; Gielen, Gerty; Wu, Weixiang

    2015-01-01

    Conversion of rice straw into biochar for soil amendment appears to be a promising method to increase long-term carbon sequestration and reduce greenhouse gas (GHG) emissions. The stability of biochar in paddy soil, which is the major determining factor of carbon sequestration effect, depends mainly on soil properties and plant functions. However, the influence of plants on biochar stability in paddy soil remains unclear. In this study, bulk and surface characteristics of the biochars incubated without rice plants were compared with those incubated with rice plants using a suite of analytical techniques. Results showed that although rice plants had no significant influence on the bulk characteristics and decomposition rates of the biochar, the surface oxidation of biochar particles was enhanced by rice plants. Using (13)C labeling we observed that rice plants could significantly increase carbon incorporation from biochar into soil microbial biomass. About 0.047% of the carbon in biochar was incorporated into the rice plants during the whole rice growing cycle. These results inferred that root exudates and transportation of biochar particles into rice plants might decrease the stability of biochar in paddy soil. Impact of plants should be considered when predicting carbon sequestration potential of biochar in soil systems. PMID:25944542

  4. Flow-Field Survey in the Test Region of the SR-71 Aircraft Test Bed Configuration

    NASA Technical Reports Server (NTRS)

    Mizukami, Masashi; Jones, Daniel; Weinstock, Vladimir D.

    2000-01-01

    A flat plate and faired pod have been mounted on a NASA SR-71A aircraft for use as a supersonic flight experiment test bed. A test article can be placed on the flat plate; the pod can contain supporting systems. A series of test flights has been conducted to validate this test bed configuration. Flight speeds to a maximum of Mach 3.0 have been attained. Steady-state sideslip maneuvers to a maximum of 2 deg have been conducted, and the flow field in the test region has been surveyed. Two total-pressure rakes, each with two flow-angle probes, have been placed in the expected vicinity of an experiment. Static-pressure measurements have been made on the flat plate. At subsonic and low supersonic speeds with no sideslip, the flow in the surveyed region is quite uniform. During sideslip maneuvers, localized flow distortions impinge on the test region. Aircraft sideslip does not produce a uniform sidewash over the test region. At speeds faster than Mach 1.5, variable-pressure distortions were observed in the test region. Boundary-layer thickness on the flat plate at the rake was less than 2.1 in. For future experiments, a more focused and detailed flow-field survey than this one would be desirable.

  5. Evolution of Magnetic Field in the Flaring Active Region 11158 Observed by SDO/HMI

    NASA Astrophysics Data System (ADS)

    Sun, Xudong; Hoeksema, T.; Liu, Y.; Wiegelmann, T.; Hayashi, K.

    2011-05-01

    We report the evolution of the magnetic field in NOAA AR11158 over 5 days (2011 Feb 12-16) using preliminary vector magnetograms from the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamic Observatory (SDO). This region consisted of two pairs of major sunspots and displayed a complex quadrupolar field topology. It produced multiple major flares and eruptions, including the first X-class flare of the current solar cycle. Strong shear motion and flux emergence were both present, with apparent emergence preceding each major flare. We reconstruct the coronal field from a series of vector data using a non-linear force-free (NLFF) extrapolation. The estimated free magnetic energy shows a great increase during the early emergence of the current-carrying flux, while a significant, permanent decrease ( 0.5e32 erg, or 20%) is found after the X-class flare despite continuous flux injection. We relate this decrease to a previously reported, sudden change of the photospheric field after the flare. The extrapolated coronal field structure correspondingly becomes more "compact": the low-lying of field appears more sheared and stores more free energy, and higher-altitude field decays faster with height and becomes more potential. The coronal field overall becomes less-energetic.

  6. Forces and Straw Cutting Performance of Double Disc Furrow Opener in No-Till Paddy Soil

    PubMed Central

    Ahmad, Fiaz; Weimin, Ding; Qishuo, Ding; Hussain, Mubshar; Jabran, Khawar

    2015-01-01

    Conservation tillage is an energy efficient and low cost tillage system to improve soil environment compared with conventional tillage systems. However, the rice residue management becomes an “impossible to achieve” task due to high soil moisture content at harvest time and the thickness of rice straw. Disc type furrow openers are used for both seed drilling as well as straw cutting during no tillage sowing. A study was conducted to evaluate the draft requirement and straw cutting performances of different sized furrow openers in no-till paddy soil conditions. Double disc furrow opener was tested on an in-field traction bench for three working depths, i.e. 30, 60 and 90 mm, and three forwarding speeds, i.e. 0.1, 0.2 and 0.3 m/s. The draft and vertical forces on the disc were recorded with load cells. These sensors were connected to a data acquisition system developed with hardware and software. The results revealed that the size of the furrow opener, operating depth and the forwarding speed had significant effects (P<0.05) on the horizontal and vertical forces, and the straw cutting performance. Mean values of the draft were 648.9, 737.2 and 784.6 N for the opener with diameters of 330, 450 and 600 mm respectively, and the vertical forces for similar openers were 904.7, 1553.9 and 1620.4 N, respectively. Furthermore, the mean straw cutting efficiencies for the double disc opener with diameters of 330, 450 and 600 mm were 39.36, 78.47 and 65.46%, respectively. The opener with 450 mm diameter provided higher straw cutting efficiency as compared to 600 mm diameter disc, while lowest straw cutting efficiency was observed with 330 mm diameter disc. The 450 mm diameter opener provided the highest straw cutting efficiency (88.6%) at 90 mm working depth and expressed optimum performance compared with other furrow openers. PMID:25822984

  7. Decline in Topsoil Microbial Quotient, Fungal Abundance and C Utilization Efficiency of Rice Paddies under Heavy Metal Pollution across South China

    PubMed Central

    Liu, Yongzhuo; Zhou, Tong; Crowley, David; Li, Lianqing; Liu, Dawen; Zheng, Jinwei; Yu, Xinyan; Pan, Genxing; Hussain, Qaiser; Zhang, Xuhui; Zheng, Jufeng

    2012-01-01

    Agricultural soils have been increasingly subject to heavy metal pollution worldwide. However, the impacts on soil microbial community structure and activity of field soils have been not yet well characterized. Topsoil samples were collected from heavy metal polluted (PS) and their background (BGS) fields of rice paddies in four sites across South China in 2009. Changes with metal pollution relative to the BGS in the size and community structure of soil microorganisms were examined with multiple microbiological assays of biomass carbon (MBC) and nitrogen (MBN) measurement, plate counting of culturable colonies and phospholipids fatty acids (PLFAs) analysis along with denaturing gradient gel electrophoresis (DGGE) profile of 16S rRNA and 18S rRNA gene and real-time PCR assay. In addition, a 7-day lab incubation under constantly 25°C was conducted to further track the changes in metabolic activity. While the decrease under metal pollution in MBC and MBN, as well as in culturable population size, total PLFA contents and DGGE band numbers of bacteria were not significantly and consistently seen, a significant reduction was indeed observed under metal pollution in microbial quotient, in culturable fungal population size and in ratio of fungal to bacterial PLFAs consistently across the sites by an extent ranging from 6% to 74%. Moreover, a consistently significant increase in metabolic quotient was observed by up to 68% under pollution across the sites. These observations supported a shift of microbial community with decline in its abundance, decrease in fungal proportion and thus in C utilization efficiency under pollution in the soils. In addition, ratios of microbial quotient, of fungal to bacterial and qCO2 are proved better indicative of heavy metal impacts on microbial community structure and activity. The potential effects of these changes on C cycling and CO2 production in the polluted rice paddies deserve further field studies. PMID:22701725

  8. C and N accumulations in soil aggregates determine nitrous oxide emissions from cover crop treated rice paddy soils during fallow season.

    PubMed

    Pramanik, Prabhat; Haque, Md Mozammel; Kim, Sang Yoon; Kim, Pil Joo

    2014-08-15

    Combination of leguminous and non-leguminous plant residues are preferably applied in rice paddy soils to increase the rate of organic matter mineralization and to improve plant growth. However, organic matter addition facilitates methane (CH4) emission from rice paddy soil. Mineralization of organic nitrogen (N) increases NO3-N concentrations in soil, which are precursors for the formation of nitrous oxide (N2O). However, N2O is a minor greenhouse gas emitted from submerged rice field and hence is not often considered during calculation of total global warming potential (GWP) during rice cultivation. The hypothesis of this study was that fluxes of N2O emissions might be changed after removal of flooded water from rice field and the effect of cover crops on N2O emissions in the fallow season might be interesting. However, the effects of N-rich plant residues on N2O emission rates in the fallow season and its effect on annual GWP were not studied before. In this experiment, combination of barley (non-leguminous) and hairy vetch (leguminous) biomasses were applied at 9 Mg ha(-1) and 27 Mg ha(-1) rates in rice paddy soil. Cover crop application significantly increased CH4 emission flux while decreased N2O emissions during rice cultivation. The lowest N2O emission was observed in 27 Mg ha(-1) cover crop treated plots. Cover crop applications increased N contents in soil aggregates especially in smaller aggregates (<250 ?m), and that proportionately increased the N2O emission potentials of these soil aggregates. Fluxes of N2O emissions in the fallow season were influenced by the N2O emission potentials of soil aggregates and followed opposite trends as those observed during rice cultivation. Therefore, it could be concluded that the doses of cover crop applications for rice cultivation should not be optimized considering only CH4, but N2O should also be considered especially for fallow season to calculate total GWP. PMID:24880551

  9. Four large-scale field-aligned current systmes in the dayside high-latitude region

    NASA Technical Reports Server (NTRS)

    Ohtani, S.; Potemra, T. A.; Newell, P.T.; Zanetti, L. J.; Iijima, T.; Watanabe, M.; Blomberg, L. G.; Elphinstone, R. D.; Murphree, J. S.; Yamauchi, M.

    1995-01-01

    A system of four current sheets of large-scale field-aligned currents (FACs) was discovered in the data set of simultaneous Viking and Defense Meteorological Satellire Program-F7 (DMSP-F7) crossing of the dayside high-latitude region. This paper reports four examples of this system that were observed in the prenoon sector. The flow polarities of FACs are upward, downward, upward, and downward, from equatorward to poleward. The lowest-latitude upward current is flowing mostly in the central plasma sheet (CPS) precipitation region, often overlapping with the boundary plasma sheet (BPS) at its poleward edge, andis interpreted as a region 2 current. The pair of downward and upward FACs in the middle of te structure are collocated with structured electron precipitation. The precipitation of high-energy (greater than 1 keV) electrons is more intense in the lower-latitude downward current sheet. The highest-latitude downward flowing current sheet is located in a weak, low-energy particle precipitation region, suggesting that this current is flowing on open field lines. Simulaneous observations in the postnoon local time sector reveal the standard three-sheet structure of FACs, sometimes described as region 2, region 1, and mantle (referred to the midday region O) currents. A high correlation was found between the occurrence of the four FAC sheet structure and negative interplanetary magnetic field (IMF) B(sub Y). We discuss the FAC structurein terms of three types of convection cells: the merging, viscous, andlobe cells. During strongly negative IMF B(sub Y), two convection reversals exist in the prenoon sector; one is inside the viscous cell, and the other is between the viscous cell and the lobe cell. This structure of convection flow is supported by the Viking electric field and auroral UV image data. Based on the convection pattern, the four FAC sheet structure is interpreted as the latitude overlap of midday and morning FAC systems. We suggest that the for-current sheet structure is common in a certain prenoon localtime sector during strongly negative IMF B(sub Y).

  10. Magnetic fields of active galactic nuclei and quasars with regions of polarized broad H ? lines

    NASA Astrophysics Data System (ADS)

    Silant'ev, N. A.; Gnedin, Yu. N.; Buliga, S. D.; Piotrovich, M. Yu.; Natsvlishvili, T. M.

    2013-01-01

    Estimates of magnetic fields for a number of active galactic nuclei are presented. These estimates are based on the observed polarization degrees and position angles of broad H ? lines and in the nearby continuum and on asymptotic analytical formulas for the Stokes parameters of the radiation emerging from a magnetized accretion disk (the Milne problem in a magnetized atmosphere). The characteristic observed feature of the wavelength dependence of the polarization degree inside the line—a minimum at the center and a fast increase of the position angle from one wing to another—can be explained by the superposition of resonance emission from two or more clouds located in the right (Keplerian velocity directed away from the observer) and left (Keplerian velocity directed toward the observer) parts of the orbit in the rotating magnetized accretion disk. The main component in our mechanism is the azimuthal magnetic field in the disk. The presence of a magnetic field perpendicular to the disk plane (which is usually weaker than the azimuthal field) results in the asymmetry of the distribution of the polarization degree and position angle inside the line. The inferred magnetic field strengths at the galactocentric distances where broad lines are emitted can be used to estimate the magnetic fields in the region of the centermost stable orbit and at the horizon of the central black hole, using the power-law dependence of the magnetic field strength corresponding to the standard model of the accretion disk.

  11. The Dynamical Character of the Holocene Paleomagnetic Field: Evidence from the North America Region

    NASA Astrophysics Data System (ADS)

    Lund, S.; Burton, M. E.

    2013-12-01

    We have developed a new compilation of paleomagnetic time series spanning the past 8000 years - PSVMOD2.0. PSVMOD2.0 now consists of 185 PSV time series (inclination, declination, or intensity) from 85 global sites, including 30 full-vector records (inclination, declination, intensity). In almost all cases, the sediment relative paleointensity records have been normalized to absolute intensity values based on comparisions to nearby absolute archeomagnetic records. Time series data have advantages over isolated spot measurements in that they can provide an independent assessment of data quality, chronology and accuracy by comparisons between successive epochs and between spatially adjacent records. We are using these time series for two types of field analysis: spherical harmonic analysis and high-resolution, regional studies of field variability. We have broken up PSVMOD2.0 into seven study regions for individual studies. We present here new results from one region - North America. A subset of our North American time series was previously studied by Lund (JGR, 1996). Lund (1996) used unit-vector directions (no paleointensity) from 9 sites comprising 18 time series. We are using 21 sites with 53 time series (inclination, declination, and paleointensity), of which 12 sites have full vector records. Our sites cover twice the spatial region of the Lund (1996) study. We have replicated all of the conclusions of Lund (1996) documenting no appreciable long-term drift of the field and evidence for strong looping of the directional field. We have also found clear evidence for two time-scales of open looping and our paleointensity studies let us note for the first time that the directional circularity is matched by centennial-millennial scale intensity variability.

  12. Stator flux orientation control of induction machines in the field weakening region

    Microsoft Academic Search

    X. Xu; R. de Doncker; D. W. Novotny

    1988-01-01

    The behavior of a director stator-flux-oriented (SFO) system in the field weakening region is studied and compared with that of a direct rotor-flux-oriented (RFO) system. The steady-state analysis shows that the SFO system always retains maximum torque capability, not matter how large the error in the parameters. In contrast, RFO is sensitive to variations in leakage and magnetizing inductances. When

  13. Field-aligned electron beams observed simultaneously with upflowing ion beams in the auroral acceleration region

    Microsoft Academic Search

    R. Yoshioka; W. Miyake; T. Mukai; M. Ito

    2000-01-01

    Upgoing, counterstreaming, and downgoing field-aligned electron beams observed simultaneously with upward ion beams in the auroral acceleration region on Akebono (Exos-D) satellite are studied statistically. These electron beams are narrowly collimated within the local loss cone, generally have lower energies per charge than the potential drop above the satellite, and are associated only with low-energy (<2 keV) ion beams. Their

  14. Accurate torque control of saturated interior permanent magnet synchronous motors in the field-weakening region

    Microsoft Academic Search

    Michael M. Bech; Torben S. Frederiksen; Per Sandholdt

    2005-01-01

    This paper focuses on accurate torque control of saturated interior permanent magnet (IPM) synchronous motors operating in the field-weakening region, where the maximum torque per ampere strategy cannot be used. First, a simple-but yet accurate-torque calculation method that takes saturation effects into account is devised: the torque developed at an arbitrary (id, iq) may be calculated using only six parameters,

  15. Photospheric Electric Fields and Energy Fluxes in the Eruptive Active Region NOAA 11158

    E-print Network

    Kazachenko, Maria D; Welsch, Brian T; Liu, Yang; Sun, Xudong

    2015-01-01

    How much electromagnetic energy crosses the photosphere in evolving solar active regions? With the advent of high-cadence vector magnetic field observations, addressing this fundamental question has become tractable. In this paper, we apply the "PTD-Doppler-FLCT-Ideal" (PDFI) electric field inversion technique of Kazachenko et al. (2014) to a 6-day HMI/SDO vector magnetogram and Doppler velocity sequence, to find the electric field and Poynting flux evolution in NOAA active region 11158, which produced an X2.2 flare early on 2011 February 15. We find photospheric electric fields ranging up to $1.5$ V/cm. The Poynting fluxes range up to $2\\times10^{10}$ ergs$\\cdot$cm$^{-2}$s$^{-1}$ with mean values around $10^8$-$10^9$ ergs$\\cdot$cm$^{-2}$s$^{-1}$. Integrating the instantaneous energy flux over space and time, we find that the total magnetic energy accumulated above the photosphere from emergence to the moment before the X2.2 flare to be $E=10.6\\times10^{32}$ ergs, which is partitioned as $2.0\\times10^{32}$ er...

  16. Distribution of the Crustal Magnetic Field in Sichuan-Yunnan Region, Southwest China

    PubMed Central

    Bai, Chunhua; Kang, Guofa; Gao, Guoming

    2014-01-01

    Based on the new and higher degree geomagnetic model NGDC-720-V3, we have investigated the spatial distribution, the altitude decay characteristics of the crustal magnetic anomaly, the contributions from different wavelength bands to the anomaly, and the relationship among the anomaly, the geological structure, and the geophysical field in Sichuan-Yunnan region of China. It is noted that the most outstanding feature in this area is the strong positive magnetic anomaly in Sichuan Basin, a geologically stable block. Contrasting with this feature, a strong negative anomaly can be seen nearby in Longmen Mountain block, an active block. This contradiction implies a possible relationship between the magnetic field and the geological activity. Completely different feature in magnetic field distribution is seen in the central Yunnan block, another active region, where positive and negative anomalies distribute alternatively, showing a complex magnetic anomaly map. Some fault belts, such as the Longmen Mountain fault, Lijiang-Xiaojinhe fault, and the Red River fault, are the transitional zones of strong and weak or negative and positive anomalies. The corresponding relationship between the magnetic anomaly and the geophysical fields was confirmed. PMID:25243232

  17. Satellite observations of electric fields in the South Atlantic anomaly region during the July 2000 magnetic storm

    Microsoft Academic Search

    C. S. Lin; H. C. Yeh

    2005-01-01

    During the great magnetic storm of 15 July 2000 the ROCSAT-1 low Earth-orbiting satellite detected an unusually large region of density depletion at low latitudes (<35°) in the ionosphere in corotation with the South Atlantic anomaly (SAA). Adjacent to the region of density dropout was a region of density enhancement with irregularities. We report characteristics of convective electric fields deduced

  18. Spatial-Temporal Variation and Primary Ecological Drivers of Anopheles sinensis Human Biting Rates in Malaria Epidemic-Prone Regions of China

    PubMed Central

    Ren, Zhoupeng; Wang, Duoquan; Hwang, Jimee; Bennett, Adam; Sturrock, Hugh J. W.; Ma, Aimin; Huang, Jixia; Xia, Zhigui; Feng, Xinyu; Wang, Jinfeng

    2015-01-01

    Background Robust malaria vector surveillance is essential for optimally selecting and targeting vector control measures. Sixty-two vector surveillance sites were established between 2005 and 2008 by the national malaria surveillance program in China to measure Anopheles sinensis human biting rates. Using these data to determine the primary ecological drivers of malaria vector human biting rates in malaria epidemic-prone regions of China will allow better targeting of vector control resources in space and time as the country aims to eliminate malaria. Methods We analyzed data from 62 malaria surveillance sentinel sites from 2005 to 2008. Linear mixed effects models were used to identify the primary ecological drivers for Anopheles sinensis human biting rates as well as to explore the spatial-temporal variation of relevant factors at surveillance sites throughout China. Results Minimum semimonthly temperature (? = 2.99; 95% confidence interval (CI) 2.07- 3.92), enhanced vegetation index (? =1.07; 95% CI 0.11–2.03), and paddy index (the percentage of rice paddy field in the total cultivated land area of each site) (? = 0.86; 95% CI 0.17–1.56) were associated with greater An. Sinensis human biting rates, while increasing distance to the nearest river was associated with lower An. Sinensis human biting rates (? = ?1.47; 95% CI ?2.88, ?0.06). The temporal variation (?t02=1.35) in biting rates was much larger than the spatial variation (?s02=0.83), with 19.3% of temporal variation attributable to differences in minimum temperature and enhanced vegetation index and 16.9% of spatial variance due to distance to the nearest river and the paddy index. Discussion Substantial spatial-temporal variation in An. Sinensis human biting rates exists in malaria epidemic-prone regions of China, with minimum temperature and enhanced vegetation index accounting for the greatest proportion of temporal variation and distance to nearest river and paddy index accounting for the greatest proportion of spatial variation amongst observed ecological drivers. Conclusions Targeted vector control measures based on these findings can support the ongoing malaria elimination efforts in China more effectively. PMID:25611483

  19. Orientation of hatchling loggerhead sea turtles to regional magnetic fields along a transoceanic migratory pathway.

    PubMed

    Fuxjager, Matthew J; Eastwood, Brian S; Lohmann, Kenneth J

    2011-08-01

    Young loggerhead sea turtles (Caretta caretta) from the east coast of Florida, USA, undertake a transoceanic migration around the North Atlantic Gyre, the circular current system that flows around the Sargasso Sea. Previous experiments indicated that loggerhead hatchlings, when exposed to magnetic fields replicating those that exist at five widely separated locations along the migratory pathway, responded by swimming in directions that would, in each case, help turtles remain in the gyre and advance along the migratory route. In this study, hatchlings were exposed to several additional magnetic fields that exist along or outside of the gyre's northern boundary. Hatchlings responded to fields that exist within the gyre currents by swimming in directions consistent with their migratory route at each location, whereas turtles exposed to a field that exists north of the gyre had an orientation that was statistically indistinguishable from random. These results are consistent with the hypothesis that loggerhead turtles entering the sea for the first time possess a navigational system in which a series of regional magnetic fields sequentially trigger orientation responses that help steer turtles along the migratory route. By contrast, hatchlings may fail to respond to fields that exist in locations beyond the turtles' normal geographic range. PMID:21753042

  20. Paddy Soil Stability and Mechanical Properties as Affected by Long-Term Application of Chemical Fertilizer and Animal Manure in Subtropical China

    Microsoft Academic Search

    Jiang-Tao LI; Bin ZHANG

    2007-01-01

    Wet stability, penetration resistance (PR), and tensile strength (TS) of paddy soils under a fertilization experiment for 22 years were determined to elucidate the function of soil organic matter in paddy soil stabilization. The treatments included no fertilization (CK), normal chemical fertilization (NPK), double the NPK application rates (2NPK), and NPK mixed with organic manure (NPK+OM).Compared with CK, fertilization increased

  1. Long-term nitrogen fertilization of paddy soil shifts iron-reducing microbial community revealed by RNA-13C-acetate probing coupled with pyrosequencing

    PubMed Central

    Ding, Long-Jun; Su, Jian-Qiang; Xu, Hui-Juan; Jia, Zhong-Jun; Zhu, Yong-Guan

    2015-01-01

    Iron reduction is an important biogeochemical process in paddy soils, yet little is known about the microbial coupling between nitrogen and iron reduction. Here, we investigated the shift of acetate-metabolizing iron-reducers under long-term nitrogen fertilization using 13C-acetate-based ribosomal RNA (rRNA)-stable isotope probing (SIP) and pyrosequencing in an incubation experiment, and the shift of putative iron-reducers in original field samples were investigated by 16S rRNA gene-based pyrosequencing. During SIP incubations, in the presence of iron(III) oxyhydroxides, more iron(II) formation and less methane production were detected in nitrogen-fertilized (N) compared with non-fertilized (NF) soil. In 13C-rRNA from microcosms amended with ferrihydrite (FER), Geobacter spp. were the important active iron-reducers in both soils, and labeled to a greater extent in N (31% of the bacterial classified sequences) than NF soils (11%). Pyrosequencing of the total 16S rRNA transcripts from microcosms at the whole community level further revealed hitherto unknown metabolisms of potential FER reduction by microorganisms including Pseudomonas and Solibacillus spp. in N soil, Dechloromonas, Clostridium, Bacillus and Solibacillus spp. in NF soil. Goethite (GOE) amendment stimulated Geobacter spp. to a lesser extent in both soils compared with FER treatment. Pseudomonas spp. in the N soil and Clostridium spp. in the NF soil may also be involved in GOE reduction. Pyrosequencing results from field samples showed that Geobacter spp. were the most abundant putative iron-reducers in both soils, and significantly stimulated by long-term nitrogen fertilization. Overall, for the first time, we demonstrate that long-term nitrogen fertilization promotes iron(III) reduction and modulates iron-reducing bacterial community in paddy soils. PMID:25171335

  2. Magnetic Field Diagnostics and Spatio-Temporal Variability of the Solar Transition Region

    NASA Astrophysics Data System (ADS)

    Peter, H.

    2013-12-01

    Magnetic field diagnostics of the transition region from the chromosphere to the corona faces us with the problem that one has to apply extreme-ultraviolet (EUV) spectro-polarimetry. While for the coronal diagnostics techniques already exist in the form of infrared coronagraphy above the limb and radio observations on the disk, one has to investigate EUV observations for the transition region. However, so far the success of such observations has been limited, but various current projects aim to obtain spectro-polarimetric data in the extreme UV in the near future. Therefore it is timely to study the polarimetric signals we can expect from these observations through realistic forward modeling. We employ a 3D magneto-hydrodynamic (MHD) forward model of the solar corona and synthesize the Stokes I and Stokes V profiles of C iv (1548 Å). A signal well above 0.001 in Stokes V can be expected even if one integrates for several minutes to reach the required signal-to-noise ratio, and despite the rapidly changing intensity in the model (just as in observations). This variability of the intensity is often used as an argument against transition region magnetic diagnostics, which requires exposure times of minutes. However, the magnetic field is evolving much slower than the intensity, and therefore the degree of (circular) polarization remains rather constant when one integrates in time. Our study shows that it is possible to measure the transition region magnetic field if a polarimetric accuracy on the order of 0.001 can be reached, which we can expect from planned instrumentation.

  3. Characterization of the IMF By-dependent field-aligned currents in the cleft region based on DE 2 observations

    NASA Technical Reports Server (NTRS)

    Taguchi, S.; Sugiura, M.; Winningham, J. D.; Slavin, J. A.

    1993-01-01

    The magnetic field and plasma data from 47 passes of DE-2 are used to study the IMF By-dependent distribution of field-aligned currents in the cleft region. It is proposed that the low-latitude cleft current (LCC) region is not an extension of the region 1 or region 2 current system and that a pair of LCCs and high-latitude cleft currents (HCCs) constitutes the cleft field-aligned current regime. The proposed pair of cleft field-aligned currents is explained with a qualitative model in which this pair of currents is generated on open field lines that have just been reconnected on the dayside magnetopause. The electric fields are transmitted along the field lines to the ionosphere, creating a poleward electric field and a pair of field-aligned currents when By is positive; the pair of field-aligned currents consists of a downward current at lower latitudes and an upward current at higher latitudes. In the By negative case, the model explains the reversal of the field-aligned current direction in the LCC and HCC regions.

  4. Regional Field Verification - Operational Results from Four Small Wind Turbines in the Pacific Northwest

    SciTech Connect

    Sinclair, K.; Raker, J.

    2006-01-01

    The purpose of the Department of Energy/National Renewable Energy Laboratory's (DOE/NREL) Regional Field Verification (RFV) project is to support industry needs for gaining initial field operation experience with small wind turbines and to verify the performance, reliability, maintainability, and cost of small wind turbines in diverse applications. In addition, RFV aims to help expand opportunities for wind energy in new regions of the United States by tailoring projects to meet unique regional requirements, and document and communicate the experience from these projects for the benefit of others in the wind power development community and rural utilities. Under RFV, Bergey Excel S (10kW) wind turbines were installed at sites in the Pacific Northwest as part of Northwest Sustainable Energy for Economic Development's (NWSEED) Our Wind Cooperative. Each installation was instrumented with data acquisition systems to collect a minimum of two years of operating data. The four turbines highlighted in this paper were installed between 2003 and 2004. At least two years of operational data have been collected from each of these sites by Northwest SEED. This paper describes DOE/NREL's RFV project and summarizes operational data from these sites.

  5. On the role of the point grid in regional gravity field analysis

    NASA Astrophysics Data System (ADS)

    Schall, Judith; Eicker, Annette; Kusche, Jürgen

    2014-05-01

    In order to motivate regional analysis in gravity field modelling, as contrasted with spherical harmonic modelling, it is often suggested that the resolution of regional models can be adapted to the data coverage, density and variability. However, in practice most regional approaches do not fully take advantage of this. The model resolution is closely connected to the nodal point grid, i.e. the locations of the base functions. Since formal optimization of the point grid poses a non-trivial task (the problem is non-linear and not fixed in dimension), the grid is most often simply defined a-priori, e.g. dense and uniform with an extra margin extending the data area. This choice is very flexible regarding differing data scenarios, but it quickly leads to over-parameterization and numerical problems. Contrary, our hypothesis is that an optimized, small and well-distributed grid leads to a more stable solution, which at the same time better explains the data. Here, we propose an approach to globally optimize the point grid in a radial base function approach, i.e. the number and locations of base functions, jointly with the usual model parameters. We make use of tools from Bayesian statistics; precisely, we use the Metropolis-Hastings-Green algorithm, which is an extension of the well-known Metropolis-Hastings sampler to cases when the target density is variable in dimension. We will present the theoretical background and provide numerical results from the field of GOCE data analysis.

  6. Development of active regions: flows, magnetic-field patterns and bordering effect

    E-print Network

    Getling, A V; Buchnev, A A

    2015-01-01

    A qualitative analysis is given to the data on the full magnetic and velocity vector fields in a growing sunspot group, recorded nearly simultaneously with the Solar Optical Telescope on the Hinode satellite. Observations of a young bipolar subregion developing within AR 11313 were carried out on 9-10 October 2011. Our aim was to form am idea about the consistency of the observed pattern with the well-known rising-tube model of the formation of bipolar acrive regions and sunspot groups. We find from our magnetograms that the distributions of the vertical [B_v] and the horizontal [B_h] component of the magnetic field over the area of the magnetic subregion are spatially well correlated; in contrast, the rise of a flux-tube loop would result in a qualitatively different pattern, with the maxima of the two magnetic-field components spatially separated: the vertical field would be the strongest where either spot emerges, while the maximum horizontal-field strengths would be reached in between them. A specific fea...

  7. Fault patterns in Benin River and Makaraba Fields: A regional play type for the Niger Delta

    SciTech Connect

    Adeyekun, A.B.; Faparusi, B.D.; Nunns, A.G. [Chevron Nigeria Ltd., Lagos (Nigeria)] [and others

    1995-08-01

    Using 830 km{sup 2} of excellent 3-D seismic data, we determined the fault patterns that are responsible for hydrocarbon entrapment in the Benin River and Makaraba fields, onshore northwestern Niger Delta. Both fields are trapped downthrown to the major listric GbokoMaka growth fault system, which trends E18{degrees}S for over 40 km, and has at least 2000 m of displacement to the southwest. Several major splay faults break off the main trend in a southeasterly direction, creating a series of fault-bounded structural compartments. Each of these compartments opens to the southeast and has a structural attic at the junction of the splay fault with the main fault trend. These compartments create large-scale traps for hydrocarbons migrating from east to west up the gentle regional dip within the Miocene Ughelli depobelt. The Benin River field is trapped in the major compartment between the GbokoMaka fault and the Benin River splay fault. The large Makaraba field is similarly trapped between the GbokoMaka and MakaWest faults. Such traps require an upthrown fault seal at the master fault and a downthrown fault seal at the splay fault. In the Makamba field, the trap potential is enhanced by rollover into the GbokoMaka fault. The same structural style is also evident along several other major fault trends to the north and the south, and probably represents an important play type in the onshore western Niger delta.

  8. Auroral Region Ionospheric Currents From Champ and Ground Based Magnetic Field Data

    NASA Astrophysics Data System (ADS)

    Ritter, P.; Lühr, H.; Viljanen, A.

    One important contribution to the magnetic field measured at satellite height is due to the external current systems. Above the polar regions the scalar data sampled by the Overhauser Magnetometer on CHAMP are used to study the horizontal Ionospheric Hall Current system. A series of line currents, placed at high latitudes at a height of 110, km is fitted to the spatial variations of the residual magnetic field across these re- gions. The observed current distribution depends on the local time of the satellite track. At dawn/dusk orbits the Polar ElectroJet (PEJ) can be detected clearly in the northern and southern auroral region. Its variation with time is evidently correlated with the AE activity index. The results obtained from CHAMP measurements are compared to the currents determined from ground based observations of the Scandinavian IMAGE magnetometer network. During periods of increased activity both current estimates are in good agreement. At quiet times uncorrected lithospheric magnetic fields cause spurious current features in the satellite results.

  9. Effects of water-saving irrigation practices and drought resistant rice variety on greenhouse gas emissions from a no-till paddy in the central lowlands of China.

    PubMed

    Xu, Ying; Ge, Junzhu; Tian, Shaoyang; Li, Shuya; Nguy-Robertson, Anthony L; Zhan, Ming; Cao, Cougui

    2015-02-01

    As pressure on water resources increases, alternative practices to conserve water in paddies have been developed. Few studies have simultaneously examined the effectiveness of different water regimes on conserving water, mitigating greenhouse gases (GHG), and maintaining yields in rice production. This study, which was conducted during the drought of 2013, examined all three factors using a split-plot experiment with two rice varieties in a no-till paddy managed under three different water regimes: 1) continuous flooding (CF), 2) flooded and wet intermittent irrigation (FWI), and 3) flooded and dry intermittent irrigation (FDI). The Methane (CH?) and nitrous oxide (N?O) emissions were measured using static chamber-gas measurements, and the carbon dioxide (CO?) emissions were monitored using a soil CO? flux system (LI-8100). Compared with CF, FWI and FDI irrigation strategies reduced CH? emissions by 60% and 83%, respectively. In contrast, CO? and N?O fluxes increased by 65% and 9%, respectively, under FWI watering regime and by 104% and 11%, respectively, under FDI managed plots. Although CO? and N?O emissions increased, the global warming potential (GWP) and greenhouse gas intensity (GHGI) of all three GHG decreased by up to 25% and 29% (p<0.01), respectively, using water-saving irrigation strategies. The rice variety also affected yields and GHG emissions in response to different water regimes. The drought-resistance rice variety (HY3) was observed to maintain yields, conserve water, and reduce GHG under the FWI irrigation management compared with the typical variety (FYY299) planted in the region. The FYY299 only had significantly lower GWP and GHGI when the yield was reduced under FDI water regime. In conclusion, FWI irrigation strategy could be an effective option for simultaneously saving water and mitigating GWP without reducing rice yields using drought-resistant rice varieties, such as HY3. PMID:25461105

  10. Crustal Structure Beneath the Lake Ontario Region from Inverse Models of Potential Field and Seismic Data

    NASA Astrophysics Data System (ADS)

    Navarrete, L. C.; Benoit, M. H.; Ebinger, C. J.; Horowitz, F.

    2014-12-01

    The regions surrounding Lake Ontario (e.g. the Adirondack mountain region and its northern border with Canada) are among the most seismically active regions in the Eastern US. However, only scant knowledge exists of the location and geometry of faults, suture zones, or crustal thickness variations that may localize strain in the crust beneath sections of New York, Pennsylvania and Ontario. Our aim is to determine the crustal density and magnetic susceptibility contrasts (e.g., steep faults, intrusive bodies, Moho topography) which give rise to anomaly patterns and to place constraints on their geometries and locations. With a better understanding of these structures, we will examine how the distribution of the faults and steep contacts throughout the region compare with zones of active seismicity. Utilizing the North American Gravity Database, we created a profile that crosses a narrow Bouguer anomaly with steep gradients surrounded by Bouguer anomaly highs transecting the lake and extending onshore east of Rochester, subparallel to the seismically active Clarendon-Linden fault. Euler deconvolution and 'worm' analyses show that this narrow anomaly is bounded by east-dipping faults that extend to mid-crustal levels. We perform receiver function analyses of Earthscope TA stations in the region in order to constrain crustal thickness and lateral variations in Vp/Vs. These receiver functions at onshore sites in the area show complex Moho structure which partially explains our anomaly.Additionally, a vintage seismic profile coupled with the Lake Ontario bathymetry dataset was used to place constraints on sedimentary strata thicknesses and to identify structures within Proterozoic basement. Predictive models of crustal variations were created from a potential field profile, receiver functions, and a seismic profile to test interpretations. The Moho topography alone does not fully explain the short wavelength gravity anomaly, and a sedimentary basin of 3-5 km in depth is also needed to explain the observed Bouguer gravity anomaly patterns. We use these techniques to extend density mapping throughout the region.

  11. WIDE-FIELD INFRARED SURVEY EXPLORER OBSERVATIONS OF THE EVOLUTION OF MASSIVE STAR-FORMING REGIONS

    SciTech Connect

    Koenig, X. P.; Leisawitz, D. T.; Benford, D. J.; Padgett, D. L. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Rebull, L. M. [Spitzer Science Center (SSC), California Institute of Technology, M/S 220-6, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Assef, R. J. [Jet Propulsion Laboratory, MS 169-530, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States)

    2012-01-10

    We present the results of a mid-infrared survey of 11 outer Galaxy massive star-forming regions and 3 open clusters with data from the Wide-field Infrared Survey Explorer (WISE). Using a newly developed photometric scheme to identify young stellar objects and exclude extragalactic contamination, we have studied the distribution of young stars within each region. These data tend to support the hypothesis that latter generations may be triggered by the interaction of winds and radiation from the first burst of massive star formation with the molecular cloud material leftover from that earlier generation of stars. We dub this process the 'fireworks hypothesis' since star formation by this mechanism would proceed rapidly and resemble a burst of fireworks. We have also analyzed small cutout WISE images of the structures around the edges of these massive star-forming regions. We observe large (1-3 pc size) pillar and trunk-like structures of diffuse emission nebulosity tracing excited polycyclic aromatic hydrocarbon molecules and small dust grains at the perimeter of the massive star-forming regions. These structures contain small clusters of emerging Class I and Class II sources, but some are forming only a single to a few new stars.

  12. An Experimental Study of the Near Field Region of a Free Jet with Passive Mixing Tabs

    NASA Technical Reports Server (NTRS)

    Bohl, D. G.; Foss, J. F.

    1997-01-01

    An experimental study was performed to determine the flow characteristics of a tabbed free jet. Results were acquired in the near field (nominally 2 tab widths upstream to 2 tab widths downstream of the exit plane) of a tabbed jet. Upstream pressure results showed static pressure distributions in both the x-and y-directions along the top surface of the tunnel. Hot-wire measurements showed rapid expansion of the core fluid into the ambient region. Two counter rotating regions of streamwise vorticity were shown on each side of the primary tab. An enhancement of the tabbed jet concept was proposed and tested. Specifically, two tabs, half the scale of the primary tab, were added to the primary tab to provide attachment surfaces for the normally occurring ejection of fluid. The secondary tabs caused a slight increase in the streamwise vorticity created from the upstream static pressure gradient while significantly increasing the re-oriented boundary layer vorticity. The combined pumping effect of the two counter rotating regions of vorticity caused a significant increase in the transport of the jet core fluid into the surrounding region.

  13. Wide-Field Infrared Survey Explorer Observations of the Evolution of Massive Star-Forming Regions

    NASA Technical Reports Server (NTRS)

    Koenig, X. P.; Leisawitz, D. T.; Benford, D. J.; Rebull, L. M.; Padgett, D. L.; Asslef, R. J.

    2012-01-01

    We present the results of a mid-infrared survey of II outer Galaxy massive star-forming regions and 3 open clusters with data from the Wide-field Infrared Survey Explorer (WISE). Using a newly developed photometric scheme to identify young stellar objects and exclude extragalactic contamination, we have studied the distribution of young stars within each region. These data tend to support the hypothesis that latter generations may be triggered by the interaction of winds and radiation from the first burst of massive star formation with the molecular cloud material leftover from that earlier generation of stars. We dub this process the "fireworks hypothesis" since star formation by this mechanism would proceed rapidly and resemble a burst of fireworks. We have also analyzed small cutout WISE images of the structures around the edges of these massive star-forming regions. We observe large (1-3 pc size) pillar and trunk-like structures of diffuse emission nebulosity tracing excited polycyclic aromatic hydrocarbon molecules and small dust grains at the perimeter of the massive star-forming regions. These structures contain small clusters of emerging Class I and Class II sources, but some are forming only a single to a few new stars.

  14. Chiral effective-field theory in the Delta(1232) region : II. radiative pion photoproduction

    SciTech Connect

    Vladimir Pascalutsa; Marc Vanderhaeghen

    2007-10-12

    We present a theoretical study of the radiative pion photoproduction on the nucleon ($\\gamma N \\rightarrow \\pi N \\gamma'$) in the $\\De$-resonance region, with the aim to determine the magnetic dipole moment (MDM) of the $\\Delta^+(1232)$. The study is done within the framework of chiral effective-field theory where the expansion is performed (to next-to-leading order) in the $\\delta$ power-counting scheme which is an extension of chiral perturbation theory to the $\\Delta$-resonance energy region. We present in detail the results for the absorptive part of the $\\Delta$ MDM, as well as a sensitivity study for the radiative pion photoproduction observables on the real part of the $\\Delta$ MDM. We find that an asymmetry for circular polarization of the photon beam may provide a model-independent way to measure the $\\Delta$ MDM.

  15. Regional hydrology of the Dixie Valley geothermal field, Nevada: preliminary interpretations of chemical and isotopic data

    SciTech Connect

    Counce, D; Dunlap, C; Goff, F; Huebner, M; Janik, C; Johnson, S; Nimz, G

    1999-08-16

    Chemical and isotopic analyses of Dixie Valley regional waters indicate several distinct groups ranging in recharge age from Pleistocene (<20 ka) to recent (<50a). Valley groundwater is older than water from perennial springs and artesian wells in adjacent ranges, with Clan Alpine range (east) much younger (most <50a) than Stillwater range (west; most >1000a). Geothermal field fluids ({approximately}12-14 ka) appear derived from water similar in composition to non-thermal groundwater observed today in valley artesian wells (also -14 ka). Geothermal fluid interaction with mafic rocks (Humboldt Lopolith) appears to be common, and significant reaction with granodiorite may also occur. Despite widespread occurrence of carbonate rocks, large scale chemical interaction appears minor. Age asymmetry of the ranges, more extensive interaction with deep-seated waters in the west, and distribution of springs and artesian wells suggest the existence of a regional upward hydrologic gradient with an axis in proximity to the Stillwater range.

  16. Simulating Turbulent Wind Fields for Offshore Turbines in Hurricane-Prone Regions (Poster)

    SciTech Connect

    Guo, Y.; Damiani, R.; Musial, W.

    2014-04-01

    Extreme wind load cases are one of the most important external conditions in the design of offshore wind turbines in hurricane prone regions. Furthermore, in these areas, the increase in load with storm return-period is higher than in extra-tropical regions. However, current standards have limited information on the appropriate models to simulate wind loads from hurricanes. This study investigates turbulent wind models for load analysis of offshore wind turbines subjected to hurricane conditions. Suggested extreme wind models in IEC 61400-3 and API/ABS (a widely-used standard in oil and gas industry) are investigated. The present study further examines the wind turbine response subjected to Hurricane wind loads. Three-dimensional wind simulator, TurbSim, is modified to include the API wind model. Wind fields simulated using IEC and API wind models are used for an offshore wind turbine model established in FAST to calculate turbine loads and response.

  17. Regional frequency analysis conditioned on large-scale atmospheric or oceanic fields

    NASA Astrophysics Data System (ADS)

    Renard, Benjamin; Lall, Upmanu

    2015-04-01

    Many studies report that hydrologic regimes are modulated by large-scale modes of climate variability such as the El Niño Southern Oscillation (ENSO) or the North Atlantic Oscillation (NAO). Climate-informed frequency analysis models have therefore been proposed to condition the distribution of hydrologic variables on climate indices. However, standard climate indices may be poor predictors in some regions. This paper therefore describes a regional frequency analysis framework that conditions the distribution of hydrologic variables directly on atmospheric or oceanic fields, as opposed to predefined climate indices. This framework is based on a 2-level probabilistic model describing both climate and hydrologic data. The climate dataset (predictor) is typically a time series of atmospheric of oceanic fields defined on a grid over some area, while the hydrologic dataset (predictand) is typically a regional dataset of station data (e.g. annual peak flow at several gauging stations). A Bayesian estimation framework is used, so that a natural quantification of uncertainties affecting hydrologic predictions is available. A case study aimed at predicting the number of autumn flood events in 16 catchments located in Mediterranean France using geopotential heights at 500 hPa over the North-Atlantic region is presented. The temporal variability of hydrologic data is shown to be associated with a particular spatial pattern in the geopotential heights. A cross-validation experiment indicates that the resulting probabilistic climate-informed predictions are skillful: their reliability is acceptable and they are much sharper than predictions based on standard climate indices and baseline predictions that ignore climate information.

  18. Evaluation of soil quality indicators in paddy soils under different crop rotation systems

    NASA Astrophysics Data System (ADS)

    Nadimi-Goki, Mandana; Bini, Claudio; Haefele, Stephan; Abooei, Monireh

    2013-04-01

    Evaluation of soil quality indicators in paddy soils under different crop rotation systems Soil quality, by definition, reflects the capacity to sustain plant and animal productivity, maintain or enhance water and air quality, and promote plant and animal health. Soil quality assessment is an essential issue in soil management for agriculture and natural resource protection. This study was conducted to detect the effects of four crop rotation systems (rice-rice-rice, soya-rice-rice, fallow-rice and pea-soya-rice) on soil quality indicators (soil moisture, porosity, bulk density, water-filled pore space, pH, extractable P, CEC, OC, OM, microbial respiration, active carbon) in paddy soils of Verona area, Northern Italy. Four adjacent plots which managed almost similarly, over five years were selected. Surface soil samples were collected from each four rotation systems in four times, during growing season. Each soil sample was a composite of sub-samples taken from 3 points within 350 m2 of agricultural land. A total of 48 samples were air-dried and passed through 2mm sieve, for some chemical, biological, and physical measurements. Statistical analysis was done using SPSS. Statistical results revealed that frequency distribution of most data was normal. The lowest CV% was related to pH. Analysis of variance (ANOVA) and comparison test showed that there are significant differences in soil quality indicators among crop rotation systems and sampling times. Results of multivariable regression analysis revealed that soil respiration had positively correlation coefficient with soil organic matter, soil moisture and cation exchange capacity. Overall results indicated that the rice rotation with legumes such as bean and soybean improved soil quality over a long time in comparison to rice-fallow rotation, and this is reflected in rice yield. Keywords: Soil quality, Crop Rotation System, Paddy Soils, Italy

  19. Effects of alternating wetting and drying versus continuous flooding on chromium fate in paddy soils.

    PubMed

    Xiao, Wendan; Ye, Xuezhu; Yang, Xiaoe; Li, Tingqiang; Zhao, Shouping; Zhang, Qi

    2015-03-01

    Anthropogenic chromium (Cr) pollution in soils poses a great threat to human health through the food chain. It is imperative to understand Cr fate under the range of conditions suitable for rice growth. In this study, the effects of irrigation managements on dynamics of porewater Cr(VI) concentrations in rice paddies and Cr distribution in rice were investigated with pot experiments under greenhouse conditions. Soil redox potential in continuous flooding (CF) treatments showed that reducing conditions remained for the whole duration of rice growing period, while soil redox potential in alternating wetting and drying (AWD) treatments showed that soil conditions alternately changed between reducing and oxic. As soil redox potential is an important factor affecting Cr(VI) reduction in paddy soils, dynamics of Cr(VI) concentration were clearly different under different irrigation managements. In CF treatments, porewater Cr(VI) concentrations decreased with time after planting, while in AWD treatments porewater Cr(VI) concentrations were increased and decreased alternately response to the irrigation cycles. Chromium(VI) concentrations in the CF treatments were lower than those in AWD treatments for most part of rice-growing season. Moreover, Cr concentrations in rice tissues were significantly influenced by irrigation with relatively higher values in the AWD treatments, which might be attributed to the higher porewater Cr(VI) concentrations in AWD treatments. Therefore, it would be better to use CF than AWD management in Cr-contaminated paddy soils to reduce Cr accumulation in rice, and thus to reduce the potential risk to human health. PMID:25546832

  20. [Study on mechanism of SOM stabilization of paddy soils under long-term fertilizations].

    PubMed

    Luo, Lu; Zhou, Ping; Tong, Cheng-Li; Shi, Hui; Wu, Jin-Shui; Huang, Tie-Ping

    2013-02-01

    Fourier transform infrared spectroscopy (FTIR) was applied to study the structure of soil organic matter (SOM) of paddy soils under long-term different fertilization treatments. The aim was to clarify the different distribution of SOM between different fertilization methods and between topsoil and subsoil, and to explore the stability mechanism of SOM under different fertilization treatments. The results showed that the content of topsoil organic carbon (SOC) was the highest under organic-inorganic fertilizations, with the increment of SOC by 18.5%, 12.9% and 18.4% under high organic manure (HOM), low organic manure (LOM) and straw returning (STW) respectively compared with no fertilization treatment (CK). The long-term fertilizations also changed the chemical structure of SOM. As compared with CK, different fertilization treatments increased the functional group absorbing intensity of chemical resistance compounds (aliphatic, aromaticity), carbohydrate and organo-silicon compounds, which was the most distinctive under treatments of HOM, LOM and STW. For example, the absorbing intensity of alkyl was 0.30, 0.25 and 0.29 under HOM, LOM and STW, respectively. These values were increased by 87% , 56% and 81% as compared with that under CK treatment. The functional group absorbing intensity of SOM in the topsoil was stronger than that in the subsoil, with the most distinctive difference under HOM, LOM and STW treatments. The present research indicated that the enhanced chemical resistance of functional group of SOM may contribute to the high contents of SOC in the paddy soils under long-term organic-inorganic fertilizations, which also suggested a chemical stabilization mechanism of SOM in the paddy soils. PMID:23668142

  1. Microbiological biodiversity in poultry and paddy straw wastes in composting systems

    PubMed Central

    Devi, Sunita; Sharma, C.R.; Singh, Kamlesh

    2012-01-01

    Immense quantity of waste is generated in association with poultry meat egg and crop production. The potential risks due to disposal of these wastes are magnified as a result of dense refinement of poultry production and the decreasing amount of land available for waste disposal. The study aims at studying the microbiological biodiversity of poultry waste and paddy straw based co-composting system. The predominant microflora of the poultry manure were bacteria, fungi, enteric bacteria and spore forming bacteria whose population was high at the initiation of composting but decreased significantly as the compost approached maturity. The initial load of inherent enteric groups of bacteria in poultry waste, that also includes some pathogenic ones, is considerably reduced and some new vital groups contributed to compost quality as the microbiological biodiversity sets in the system and becomes stable. Major fraction of nitrogen of poultry waste was subjected to ammonia volatilization and a fraction of it conserved by co-composting it in conjunction with wastes having low nitrogen contents. In the treatment T1 and T5, where poultry manure and paddy straws alone were composted, 60 and 30 percent of organic carbon, respectively, was lost over a period of six months. Whereas in treatments T2,T3 and T4, poultry manure and paddy straw were co-composted in the ratio of 3:1, 2:2 and 1:3, respectively, 51.4,45.0 and 37.0 percent of carbon, respectively, was lost during decomposition. The C: N ratio in all the treatments decreased significantly to 18.3 for T1, 24.7 for T2, 27.0 for T3, 34.9 for T4 and 38.5 for T5 at the end of composting period. PMID:24031831

  2. Nitrogen mineralization in paddy soils of the Chinese Taihu Region under aerobic conditions

    Microsoft Academic Search

    Marco Roelcke; Yong Han; Zucong Cai; Jörg Richter

    2002-01-01

    In order to make more efficient use of mineral nitrogen fertilizers, the mineralization of organic N has to be fully understood and taken into account when meeting the nitrogen demand of crops. Aerobic long-term incubation experiments (147 days) based on the method by Stanford and Smith (1972, Soil Sci Soc Am Proc 36: 465), modified by Nordmeyer and Richter (1985,

  3. Quasi-static evolution of the reconstructed magnetic field of an emerging and eruptive active region

    NASA Astrophysics Data System (ADS)

    Canou, A.; Amari, T.

    2012-06-01

    We study the evolution of the emerging and eruptive Active Region (AR) 10930 for which the coronal magnetic field is reconstructed as a nonlinear force-free field along with vector magnetograms obtained from Hinode/SOT/SP data. We show that the AR evolves quasi-statically during several days through a sequence of equilibria until the time of the eruption. In addition this sequence emphasizes the formation and expansion of a coronal Twisted Flux Rope (TFR) which is related to other observed coronal structures. On the other hand, the pre-eruptive and post-eruptive magnetic configurations show that the pre-eruptive TFR plays a crucial role during the eruption.

  4. Velocity Fields in H II Regions Using High Resolution Imaging Fabry-Perot Spectrometer

    NASA Astrophysics Data System (ADS)

    Seema, P.

    1996-05-01

    The thesis comprises of two parts: I. Instrumentation II. Observations, results and discussion. An imaging Fabry-Perot spectrometer (IFPS) is designed and constructed for the studies on kinematics of extended astronomical objects (Seema et al., 1992). IFPS comprises of a field aperture, collimating lens and a two dimensional imaging sensor called Imaging Photon Detector (IPD). It is the first time that IPD which uses a resistive anode for position determination is being used in the spectroscopic studies of astronomical objects. Observations were made on Orion and Trifid nebula covering a wide field of view using a 35cm Celestron-14 telescope (f/11 cassegrain) at Gurushikhar, Mt.Abu, India. Orion Nebula: Observations were made in [OIII] 5007A, line with a spectral resolution of 6 km/sec and spatial resolution of 4" covering a field of view of 10.5', to study (i) general velocity flow (ii) high velocity flow and (iii)random motions. Line profiles generated for about 2000 positions showed an asymmetric shape with (a)a narrow component 20 +- 3 km/sec and (b) a broad component 50 +- 3 km/sec. The two components could be interpreted in terms of the interaction of the ionized gas (from the trapezium stars) with the condensations present in the nebula, resulting in the secondary flows. The iso-velocity contour map generated for both the components showed velocity flow in agreement with the champagne flow model (Tenorio-Tagle 1982). A model emission line profile constructed assuming a champagne flow in [OIII] 5007A, line for a position 2' away from theta-1 C Ori showed a reasonably good agreement with the narrow component of the observed profile. Certain high velocity flow (~50 km/s) regions are observed to be superimposed on the main flow of the narrow component. These flows are either radiation pressure driven stellar winds or jets generated during the formation phase of Young stellar objects. The radial velocity was found to be low with no high velocity flow regions in the dark bay indicating that there could be obstructing material to the expanding gas in this region. Velocity profile was generated for the first time across the Orion 'bar' ionization front. The high velocity flows are found only in certain clumps along the bar showing that the bar ionization front is found to be diffuse in [OIII] 5007A, line. The actual velocity obtained by us around the bar ionization front is estimated to be more than 100 km/s, indicating that O++ is produced by shock ionization (at least in part). Turbulence: The structure function B for a region r about 100" around theta-1 C Ori for both the narrow and the broad components showed a correlation of the form B proportional to r. We interpret that this deviation from the standard Kolmogorov model (1941) could be caused due to the presence of compressibility in the fluid (i.e., violation of one of the assumptions in Kolmogorov's model). For regions around theta-2 A Ori, the behaviour of the structure function is found to be irregular. Trifid nebula: Velocity field studies were made for about 48 positions on the nebula in [OIII] 5007A, line covering a field of view of 24'. The isovelocity map in a region 2' around the central hot star HD 164492 showed a picture of symmetric flow in velocities with no density gradients as was observed in the case of Orion nebula. A general red-shift in the radial velocities is observed in the south west direction with a velocity change of 50 km/s. There is a symmetric localized flow with a red-shift velocity of 40 km/s observed about 2.3' southwest of HD 164492 corresponding to a bow shock feature adjoining a condensation. (SECTION: Dissertation Summaries)

  5. Reconstruction of the solar coronal magnetic field, from active region to large scale

    NASA Astrophysics Data System (ADS)

    Amari, T.; Canou, A.; Delyon, F.; Aly, J. J.; Frey, P.; Alauzet, F.

    2011-12-01

    The low solar corona is dominated by the magnetic field which is created inside the sun by a dynamo process and then emerges into the atmosphere. This magnetic field plays an important role in most structures and phenomena observed at various wavelengths such as prominences, small and large scale eruptive events, and continuous heating of the plasma, and therefore it is important to understand its three-dimensional properties in order to elaborate efficient theoretical models. Unfortunately, the magnetic field is difficult to measure locally in the hot and tenuous corona. But this can be done at the level of the cooler and denser photosphere, and several instruments with high resolution vector magnetographs are currently available (THEMIS, Imaging Vector Magnetograph (IVM), the Advanced Stokes Polarimeter (ASP), SOLIS, HINODE, Solar Dynamics Observatory (SDO), or will be shortly available by future telescopes such as EST and solar missions as SOLAR-ORBITER. This has lead solar physicists to develop an approach which consists in " reconstructing" the coronal magnetic field from boundary data given on the photosphere. We will discuss some of the issues encountered in solving this problem as well our recent progress and results at the scale of active region scales or the larger one such as full sun scale.

  6. Electric field control of E region coherent echoes: Evidence from radar observations at the South Pole

    NASA Astrophysics Data System (ADS)

    Makarevich, Roman A.; Forsythe, V. V.; Kellerman, A. C.

    2015-03-01

    Characteristics and formation mechanisms of E region plasma irregularities at high latitudes are investigated using observations with the newly deployed Super Dual Auroral Radar Network (SuperDARN) radar at the South Pole Antarctic station (SPS) near a magnetic latitude (MLAT) of 75°S. It is shown that E region echo occurrence at SPS exhibits a diurnal variation that is significantly different from those at auroral and polar cap latitudes. Moreover, analysis of major spectral populations also showed a distinct and previously unreported diurnal pattern. The plasma drift velocity estimates are derived at E region ranges of SPS, leveraging the SPS radar's position well within the MLAT region where SuperDARN convection estimates are well constrained by the data. It is shown that E region irregularity occurrence increases when the convection direction is within the SPS field of view and/or when the plasma drift component is comparable with the nominal ion-acoustic speed Cs of 350 m/s. This is the expected behavior for irregularities generated directly by the modified two-stream plasma instability (MTSI). On the other hand, irregularity velocity dependence on convection velocity showed an unexpected saturation at velocity values smaller than nominal Cs. It is demonstrated that the convection velocity at which irregularity velocity starts to differ from the convection component and to approach a maximum value is dependent on the magnetic aspect angle. Moreover, the maximum velocity value itself also depends on the aspect angle. The observed behavior is discussed in context of recent models that involve evolving aspect angles as a key characteristic of MTSI saturation.

  7. Field Studies of Broadband Aerosol Optical Extinction in the Ultraviolet Spectral Region

    NASA Astrophysics Data System (ADS)

    Washenfelder, R. A.; Attwood, A.; Brock, C. A.; Brown, S. S.

    2013-12-01

    Aerosols influence the Earth's radiative budget by scattering and absorbing incoming solar radiation. The optical properties of aerosols vary as a function of wavelength, but few measurements have reported the wavelength dependence of aerosol extinction cross sections and complex refractive indices. In the case of brown carbon, its wavelength-dependent absorption in the ultraviolet spectral region has been suggested as an important component of aerosol radiative forcing. We describe a new field instrument to measure aerosol optical extinction as a function of wavelength, using cavity enhanced spectroscopy with a broadband light source. The instrument consists of two broadband channels which span the 360-390 and 385-420 nm spectral regions using two light emitting diodes (LED) and a grating spectrometer with charge-coupled device (CCD) detector. We deployed this instrument during the Fire Lab at Missoula Experiment during Fall 2012 to measure biomass burning aerosol, and again during the Southern Oxidant and Aerosol Study in summer 2013 to measure organic aerosol in the Southeastern U.S. In both field experiments, we determined aerosol optical extinction as a function of wavelength and can interpret this together with size distribution and composition measurements to characterize the aerosol optical properties and radiative forcing.

  8. THE INTERPLAY OF TURBULENCE AND MAGNETIC FIELDS IN STAR-FORMING REGIONS: SIMULATIONS AND OBSERVATIONS

    SciTech Connect

    Kirk, Helen; Johnstone, Doug [Department of Physics and Astronomy, University of Victoria, Victoria, BC, V8P 1A1 (Canada); Basu, Shantanu [Department of Physics and Astronomy, University of Western Ontario, 1151 Richmond Street, London, ON, N6A 3K7 (Canada)], E-mail: hkirk@uvastro.phys.uvic.ca

    2009-07-10

    We analyze a suite of thin-sheet magnetohydrodynamical simulations based on the formulation of Basu, Ciolek, Dapp, and Wurster. These simulations allow us to examine the observational consequences to a star-forming region of varying the input level of turbulence (between thermal and a Mach number of 4) and the initial magnetic field strength corresponding to a range of mass to flux ratios between subcritical ({mu}{sub 0} = 0.5) and supercritical ({mu}{sub 0} = 10). The input turbulence is allowed to decay over the duration of the simulation. We compare the measured observable quantities with those found from surveying the Perseus molecular cloud. We find that only the most turbulent of simulations (high Mach number and weak magnetic field) have sufficient large-scale velocity dispersion (at {approx}1 pc) to match that observed across extinction regions in Perseus. Generally, the simulated core ({approx}0.02 pc) and line-of-sight velocity dispersions provide a decent match to observations. The motion between the simulated core and its local environment, however, is far too large in simulations with high large-scale velocity dispersion.

  9. Simultaneous observations of E-region coherent backscatter and electric field amplitude at F-region heights with the Millstone Hill UHF Radar

    NASA Astrophysics Data System (ADS)

    Foster, J. C.; Erickson, P. J.

    2000-10-01

    A combined coherent backscatter-incoherent scatter experiment with the Millstone Hill UHF radar provided simultaneous observations of electric field magnitude and coherent backscatter parameters on the same L shell. A carefully-designed geometry used sidelobe coherent contamination from two-stream irregularities at 110 km altitude, appearing at ranges corresponding to F-region altitudes in the main beam, in conjunction with simultaneous uncontaminated F-region observations of the E?×B? drift velocity in adjacent range gates. Both logarithmic coherent power and the magnitude of the coherent phase velocity Vph vary linearly with |E?|. With the assumption that the coherent phase velocity is approximately the perturbed ion sound speed in the heated E region, we find an excellent agreement between the electron temperature inferred from Vph and previous incoherent-scatter results relating E-region Te to E. A maximum value of ˜3100 K has been found for such wave-induced E-region heating.

  10. Nonlinear Force-Free and Potential-Field Models of Active-Region and Global Coronal Fields during the Whole Heliosphere Interval

    NASA Astrophysics Data System (ADS)

    Petrie, G. J. D.; Canou, A.; Amari, T.

    2011-12-01

    Between 24 March 2008 and 2 April 2008, the three active regions (ARs) NOAA 10987, 10988 and 10989 were observed daily by the Synoptic Optical Long-term Investigations of the Sun (SOLIS) Vector Spectro-Magnetograph (VSM) while they traversed the solar disk. We use these measurements and the nonlinear force-free magnetic field code XTRAPOL to reconstruct the coronal magnetic field for each active region and compare model field lines with images from the Solar Terrestrial RElations Observatory (STEREO) and Hinode X-ray Telescope (XRT) telescopes. Synoptic maps made from continuous, round-the-clock Global Oscillations Network Group (GONG) magnetograms provide information on the global photospheric field and potential-field source-surface models based on these maps describe the global coronal field during the Whole Heliosphere Interval (WHI) and its neighboring rotations. Features of the modeled global field, such as the coronal holes and streamer-belt locations, are discussed in comparison with extreme ultra-violet and coronagraph observations from STEREO. The global field is found to be far from a minimum, dipolar state. From the nonlinear models we compute physical quantities for the active regions such as the photospheric magnetic and electric current fluxes, the free magnetic energy and the relative helicity for each region each day where observations permit. The interconnectivity of the three regions is addressed in the context of the potential-field source-surface model. Using local and global quantities derived from the models, we briefly discuss the different observed activity levels of the regions.

  11. Analysis and prediction of the critical regions of antimicrobial peptides based on conditional random fields.

    PubMed

    Chang, Kuan Y; Lin, Tung-pei; Shih, Ling-Yi; Wang, Chien-Kuo

    2015-01-01

    Antimicrobial peptides (AMPs) are potent drug candidates against microbes such as bacteria, fungi, parasites, and viruses. The size of AMPs ranges from less than ten to hundreds of amino acids. Often only a few amino acids or the critical regions of antimicrobial proteins matter the functionality. Accurately predicting the AMP critical regions could benefit the experimental designs. However, no extensive analyses have been done specifically on the AMP critical regions and computational modeling on them is either non-existent or settled to other problems. With a focus on the AMP critical regions, we thus develop a computational model AMPcore by introducing a state-of-the-art machine learning method, conditional random fields. We generate a comprehensive dataset of 798 AMPs cores and a low similarity dataset of 510 representative AMP cores. AMPcore could reach a maximal accuracy of 90% and 0.79 Matthew's correlation coefficient on the comprehensive dataset and a maximal accuracy of 83% and 0.66 MCC on the low similarity dataset. Our analyses of AMP cores follow what we know about AMPs: High in glycine and lysine, but low in aspartic acid, glutamic acid, and methionine; the abundance of ?-helical structures; the dominance of positive net charges; the peculiarity of amphipathicity. Two amphipathic sequence motifs within the AMP cores, an amphipathic ?-helix and an amphipathic ?-helix, are revealed. In addition, a short sequence motif at the N-terminal boundary of AMP cores is reported for the first time: arginine at the P(-1) coupling with glycine at the P1 of AMP cores occurs the most, which might link to microbial cell adhesion. PMID:25803302

  12. Modelling and analysis of compressive strength properties of parboiled paddy and milled rice

    NASA Astrophysics Data System (ADS)

    Nasirahmadi, Abozar; Abbaspour-Fard, Mohammad H.; Emadi, Bagher; Khazaei, Nasser Behroozi

    2014-03-01

    The present investigation deals with analyzing the compressive strength properties of two varieties (Tarom and Fajr) of parboiled paddy and milled rice including: ultimate stress, modulus of elasticity, rupture force and rupture energy. Combined artificial neural network and genetic algorithm were also applied to model these properties. The parboiled samples were prepared with three soaking temperatures (25, 50 and 75°C) and three steaming times (10, 15 and 20 min). The samples were then dried to final moisture contents of 8, 10 and 12% (w.b.). In general, Tarom variety had higher compressive strength properties for paddy and milled rice than Fajr variety. With increase in steaming time from 10 to 20 min, all mentioned properties increased significantly, whereas these properties were decreased with increasing moisture content from 8 to 12% (w.b.). Coupled artificial neural network and genetic algorithm model with one hidden layer, three inputs (soaking temperature, steaming time and moisture content), was developed to predict the compressive strength properties as model outputs. Results indicated that this model could predict these properties with high correlation and low mean squared error.

  13. Comparisons of direct extraction methods of microbial DNA from different paddy soils

    PubMed Central

    Islam, Md. Rashedul; Sultana, Tahera; Melvin Joe, M.; Cho, Jang-Cheon; Sa, Tongmin

    2012-01-01

    Molecular analyses for the study of soil microbial communities often depend on the direct extraction of DNA from soils. The present work compares the effectiveness of three different methods of extracting microbial DNA from seven different paddy soils. Comparison among different DNA extraction methods against different paddy soil samples revealed a marked variation in DNA yields from 3.18–20.17 ?g DNA/g of dry soil. However, irrespective of the soil samples and extraction methods the DNA fragment size was >10 kb. Among the methods evaluated, method-C (chemical–enzymatic–mechanical) had better cell lysis efficiency and DNA yield. After purification of crude DNA by Purification Kit, A260/A230 and A260/A280 ratios of the DNA obtained by method-C reached up to 2.27 and 1.89, respectively, sustaining the efficacy of this technique in removing humic acid, protein and other contaminants. Results of the comprehensive evaluation of DNA extraction methods suggest that method-C is superior to other two methods (chemical–enzymatic and chemical–mechanical), and was the best choice for extraction of total DNA from soil samples. Since soil type and microbial community characteristics influence DNA recovery, this study provides guidance for choosing appropriate extraction and purification methods according to experimental goals. PMID:23961194

  14. Linkage between community diversity of sulfate-reducing microorganisms and methylmercury concentration in paddy soil.

    PubMed

    Liu, Yu-Rong; Zheng, Yuan-Ming; Zhang, Li-Mei; He, Ji-Zheng

    2014-01-01

    Sulfate-reducing microorganisms (SRM) have been thought to play a key role in mercury (Hg) methylation in anoxic environments. The current study examined the linkage between SRM abundance and diversity and contents of methylmercury (MeHg) in paddy soils collected from a historical Hg mining area in China. Soil profile samples were collected from four sites over a distance gradient downstream the Hg mining operation. Results showed that MeHg content in the soil of each site significantly decreased with the extending distance away from Hg mine. Soil MeHg content was correlated positively with abundance of SRM and the contents of organic matter (OM), NH4(+), SO4(2-), and Hg. The abundances of SRM based on dissimilatory (bi) sulfite reductase (dsrAB) gene at 0-40 cm depths were higher than those at 40-80 cm depth at all sites. The SRM community composition varied in the soils of different sampling sites following terminal restriction fragment length polymorphism (T-RFLP) and phylogenetic analyses, which appeared to be correlated with contents of MeHg, OM, NH4(+), and SO4(2-) through canonical correspondence analysis. The dominant groups of SRM in the soils examined belonged to Deltaproteobacteria and some unknown SRM clusters that could have potential for Hg methylation. These results advance our understanding of the relationship between SRM and methylmercury concentration in paddy soil. PMID:23900947

  15. Magnetic field evolution of active regions and sunspots in connection with chromospheric and coronal activities

    NASA Astrophysics Data System (ADS)

    Shimizu, Toshifumi

    2011-08-01

    Ca II H imaging observations by the Hinode Solar Optical Telescope (SOT) have revealed that the chromosphere is extremely dynamic and that ejections and jets are well observed in moat region around sunspots. X-ray and EUV observations show frequent occurrence of microflaring activities around sunspots; small emerging flux or moving magnetic features approaching opposite pre-existing magnetic flux can be identified on the footpoints for half of microflares studied, while no encounters of opposite polarities are observed at footpoints for the others even with SOT high spatial magnetorams (Kano et al. 2010). Another observations tell the involvement of twisted magnetic fields in the microflares accompanied by no polarity encounters at the footpoints. Some type of sunspot light bridges shows recurrent occurrence of chromospheric ejections, and photospheric vector magnetic field data suggests that twsited magnetic flux tubes lying along light bridge play vital roles in producing such ejections (Shimizu et al. 2009). This presentation reviewed observational findings from these studies. We will need to understand the 3D configuration of magnetic fields for better understanding of activity triggers in the solar atmosphere.

  16. Stress Field in Brazil with Focal Mechanism: Regional and Local Patterns

    NASA Astrophysics Data System (ADS)

    Dias, F.; Assumpcao, M.

    2013-05-01

    The knowledge of stress field is fundamental not only to understand driving forces and plate deformation but also in the study of intraplate seismicity. The stress field in Brazil has been determined mainly using focal mechanisms and a few breakout data and in-situ measurements. However the stress field still is poorly known in Brazil. The focal mechanisms of recent earthquakes (magnitude lower than 5 mb) were studied using waveform modeling. We stacked the record of several teleseismic stations ( delta > 30°) stacked groups of stations separated according to distance and azimuth. Every record was visually inspected and those with a good signal/noise ratio (SNR) were grouped in windows of ten degrees distance and stacked. The teleseismic P-wave of the stacked signals was modeled using the hudson96 program of Herrmann seismology package (Herrmann, 2002) and the consistency of focal mechanism with the first-motion was checked. Some events in central Brazil were recorded by closer stations (~ 1000 km) and the moment tensor was determined with the ISOLA code (Sokos & Zahradnik, 2008). With the focal mechanisms available in literature and those obtained in this work, we were able to identify some patterns: the central region shows a purely compressional pattern (E-W SHmax), which is predicted by regional theoretical models (Richardson & Coblentz, 1996 and the TD0 model of Lithgow & Bertelloni, 2004). Meanwhile in the Amazon we find an indication of SHmax oriented in the SE-NW direction, probably caused by the Caribbean plate interaction (Meijer, 1995). In northern coastal region, the compression rotates following the coastline, which indicates an important local component related to spreading effects at the continental/oceanic transition (Assumpção, 1998) and flexural stresses caused by sedimentary load in Amazon Fan. We determine the focal mechanism of several events in Brazil using different techniques according to the available data. The major difficulty is to determine focal mechanism of low magnitudes events (< 5.0 mb) using distant s seismograph stations. We find examples of stress perturbations induced by local effects (e.g. flexure and continental spreading). The results of this work should be useful for future numerical modeling of intraplate stress field. Assumpção,M.,1998.Seismicity and stresses in the Brazilian passive margin. Bull. Seism. Soc. Am., 88(1),160-169. Herrmann, R. B. (2002). Computer programs in seismology, St. Louis University Earthquake Center, St. Louis, Missouri, www.eas.slu .edu/eqc/eqccps.html. Lithgow-Bertelloni, C., & J.H. Guynn, 2004. Origin of the lithospheric stress field. J. Geophys. Res., 109, B01408, doi:10.1029/2003JB002467. Meijer, P.T., 1995. Dynamics of active continental margins: the Andes and the Aegean regions. PhD Thesis, Utrecht University, The Netherlands. Sokos, E., Zahradnik, J., (2008). ISOLA a Fortran code and a Matlab GUI to perform multiple-point source inversion of seismic data, Computers and Geosciences, 34, 967-97. Watts, A. B., M. Rodger, C. Peirce, C. J. Greenroyd, and R. W. Hobbs (2009). Seismic structure, gravity anomalies, and flexure of the Amazon continental margin, NE Brazil, J. Geophys. Res., 114, B07103, doi:10.1029/2008JB006259.

  17. Assessment of electric field distribution in anisotropic cortical and subcortical regions under the influence of tDCS.

    PubMed

    Shahid, Salman; Wen, Peng; Ahfock, Tony

    2014-01-01

    The focus of this study is to estimate the contribution of regional anisotropic conductivity on the spatial distribution of an induced electric field across gray matter (GM), white matter (WM), and subcortical regions under transcranial direct current stimulation (tDCS). The assessment was conducted using a passive high-resolution finite element head model with inhomogeneous and variable anisotropic conductivities derived from the diffusion tensor data. Electric field distribution was evaluated across different cortical as well as subcortical regions under four bicephalic electrode configurations. Results indicate that regional tissue heterogeneity and anisotropy cause the pattern of induced fields to vary in orientation and strength when compared to the isotropic scenario. Different electrode montages resulted in distinct distribution patterns with noticeable variations in field strengths. The effect of anisotropy is highly montage dependent and directional conductivity has a more profound effect in defining the strength of the induced field. The inclusion of anisotropy in the GM and subcortical regions has a significant effect on the strength and spatial distribution of the induced electric field. Under the (C3-Fp2) montage, the inclusion of GM and subcortical anisotropy increased the average percentage difference in the electric field strength of brain from 5% to 34% (WM anisotropy only). In terms of patterns distribution, the topographic errors increased from 9.9% to 40% (WM anisotropy only) across the brain. PMID:24122951

  18. Welcome Letter: Thank you for your interest in working with the Paddy Power IT team. The rapidly

    E-print Network

    Cadar, Cristian

    more than ever before. We do not see IT as a service to the business but rather, service, scale, leveragability and value for money. We expect the IT Department to double in size's biggest and most successful bookmaker. Paddy Power provides online betting and gaming services, offers

  19. Predicting the risk of wild boar damage to rice paddies using presence-only data in Chiba Prefecture, Japan

    Microsoft Academic Search

    Masayuki Saito; Hiroshi Momose; Tosaku Mihira; Seiji Uematsu

    2012-01-01

    Population sizes of wild boar (Sus scrofa) and the damage they cause to crops have been increasing in Japan. Reliable techniques are needed to estimate the potential for damage at the landscape scale. Here, we predict the risk of damage to rice (Oryza sativa) paddies by wild boar in Chiba Prefecture, Japan, by means of three different modelling methods –

  20. The water system of traditional rice paddies as an important habitatof the giant water bug, Lethocerus deyrollei (Heteroptera: Belostomatidae)

    Microsoft Academic Search

    Yasuo Mukai; Naoto Baba; Minoru Ishii

    2005-01-01

    The population dynamics of Lethocerus deyrollei, including the seasonal change in the habitat utilization, were studied in five types of waters, permanent and temporary pools, ditch, rice paddy and marsh in a Satoyama, the traditional landscape in Japan consisting of mixtures of coppice woodlands, farmlands, and settlements, in northern Osaka, from June, 1999 to December, 2001. A mark and recapture

  1. Genome Sequence of the Verrucomicrobium Opitutus terrae PB90-1, an Abundant Inhabitant of Rice Paddy Soil Ecosystems?

    PubMed Central

    van Passel, Mark W. J.; Kant, Ravi; Palva, Airi; Copeland, Alex; Lucas, Susan; Lapidus, Alla; Glavina del Rio, Tijana; Pitluck, Sam; Goltsman, Eugene; Clum, Alicia; Sun, Hui; Schmutz, Jeremy; Larimer, Frank W.; Land, Miriam L.; Hauser, Loren; Kyrpides, Nikolaos; Mikhailova, Natalia; Richardson, P. Paul; Janssen, Peter H.; de Vos, Willem M.; Smidt, Hauke

    2011-01-01

    Bacteria of the deeply branching phylum Verrucomicrobia are rarely cultured yet commonly detected in metagenomic libraries from aquatic, terrestrial, and intestinal environments. We have sequenced the genome of Opitutus terrae PB90-1, a fermentative anaerobe within this phylum, isolated from rice paddy soil and capable of propionate production from plant-derived polysaccharides. PMID:21398538

  2. On the High- and Low- Altitude Limits of the Auroral Electric Field Region

    NASA Technical Reports Server (NTRS)

    Reiff, P. H.; Lu, G.; Burch, J. L.; Winningham, J. D.; Frank, L. A.; Craven, J. D.; Peterson, W. K.; Heelis, R. A.

    1993-01-01

    Using measurements from the High Altitude Plasma Instrument (HAPI) on the Dynamics-Explorer 1 (DE-1) spacecraft and the Low Altitude Plasma Instrument (LAPI) on Dynamics Explorer 2 (DE 2), we investigate both die high altitude and low altitude extents of the auroral acceleration region. To infer the high altitude limit, we searched the HAPI data base for evidence of upward-directed auroral electric fields located above the spacecraft when the HAPI spacecraft is above 9000 km altitude. We find that such acceleration is common when DE-1 flies through die auroral oval at an altitude of 9,000-11,000 km. At altitudes above 11,000 km, the fraction of the orbits with evidence of at least a 1000 V potential drop above the spacecraft falls, becoming essentially zero above an altitude of 15,000 km. Above that altitude, small (100 V) potential drops are frequently observed, but only rarely are approx. 1 kV potentials observed, typically associated with polar cap or 'theta' arcs or westward traveling surges. To investigate the low-altitude limit of the auroral acceleration region, we use conjunctions of DE 1 and DE 2 along auroral field lines and match the upgoing fluxes of ionospheric ions observed by DE 2 with the flux of accelerated upgoing ions observed at DE 1. Calculating the ionospheric scale height from the ion and electron temperatures and assuming that the parallel flow velocity is independent of height above 800 km, we calculate the altitude at which the upwelling ionospheric ions are effectively completely lost to upward acceleration. The initial lowest-altitude acceleration process could be either a perpendicular acceleration or a parallel electric field, but it must be sufficient to give the entire distribution escape energy. We find that in the two cases studied, near the region of peak auroral potential drop the altitude of this acceleration was around 1700 km (near the O/H neutral crossover altitude), but was significantly higher (approx. 2000 km) near the edges of the arc, where the potential was lower. The composition of the upgoing ion beam was consistent with these heights, being predominately H(+) near the edges and O(+) near the peak.

  3. Paleosecular Variation and Time-Averaged Field Behavior: Global and Regional Signatures

    NASA Astrophysics Data System (ADS)

    Johnson, C. L.; Cromwell, G.; Tauxe, L.; Constable, C.

    2012-12-01

    We use an updated global dataset of directional and intensity data from lava flows to investigate time-averaged field (TAF) and paleosecular variation (PSV) signatures regionally and globally. The data set includes observations from the past 10 Ma, but we focus our investigations on the field structure over past 5 Ma, in particular during the Brunhes and Matuyama. We restrict our analyses to sites with at least 5 samples (all of which have been stepwise demagnetized), and for which the estimate of the Fisher precision parameter, k, is at least 50. The data set comprises 1572 sites from the past 5 Ma that span latitudes 78oS to 71oN; of these ?40% are from the Brunhes chron and ?20% are from the Matuyama chron. Age control at the site level is variable because radiometric dates are available for only about one third of our sites. New TAF models for the Brunhes show longitudinal structure. In particular, high latitude flux lobes are observed, constrained by improved data sets from N. and S. America, Japan, and New Zealand. We use resampling techniques to examine possible biases in the TAF and PSV incurred by uneven temporal sampling, and the limited age information available for many sites. Results from Hawaii indicate that resampling of the paleodirectional data onto a uniform temporal distribution, incorporating site ages and age errors leads to a TAF estimate for the Brunhes that is close to that reported for the actual data set, but a PSV estimate (virtual geomagnetic pole dispersion) that is increased relative to that obtained from the unevenly sampled data. The global distribution of sites in our dataset allows us to investigate possible hemispheric asymmetries in field structure, in particular differences between north and south high latitude field behavior and low latitude differences between the Pacific and Atlantic hemispheres.

  4. An asymptotic result for the transition region field associated with the plane wave diffraction by smooth, convex surfaces

    Microsoft Academic Search

    P. H. Pathak; W. D. Burnside

    1975-01-01

    The problem of high frequency (H.F.) diffraction by smooth convex surfaces can be analysed in a straightforward manner by the geometrical theory of diffraction (GTD). According to the GTD, the surface diffracted rays accurately describe the field behaviour deep in the shadow region behind the obstacle, whereas the usual incident and reflected rays describe the dominant field contribution in the

  5. Calculation of the vectorial field distribution in a stratified focal region of a high numerical aperture imaging system

    Microsoft Academic Search

    A. S. van de Nes; L. Billy; S. F. Pereira; J. J. M. Braat

    2004-01-01

    We present an algorithm for calculating the field distribution in the focal region of stratified media which is fast and easy to implement. Using this algorithm we study the effect on the electric field distribution of an air gap separating a solid immersion lens and a sample, where we analyse the maximum distance for out-of-contact operation. Also, we study how

  6. Sediment and phosphorus fluxes - monitoring and modelling from field to regional scale - connectivity implications

    NASA Astrophysics Data System (ADS)

    Bauer, Miroslav; Zumr, David; Krása, Josef; Dostál, Tomáš; Jáchymová, Barbora; Rosendorf, Pavel

    2015-04-01

    Sediment and phosphorus fluxes - monitoring and modelling from field to regional scale - connectivity implications Miroslav Bauer1), David Zumr1), Josef Krása1), Tomáš Dostal1), Barbora Jáchymová1), Pavel Rosendorf2) Czech Technical University in Prague1, Water Research Institute of T.G.M. 2, Agricultural landscape management has a strong influences on sediment and nutrients flow paths from field to streams and reservoirs. According to many studies water erosion driven phosphorus can play important role in total phosphorous budgets in catchments and accelerate eutrophication process in vulnerable reservoirs. Research team of CTU Prague focuses on research of sediment transport processes from a small plot scale to regional scale. Using field rainfall simulator the data are collected to assess the fluxes in the scale from one to several square meters and to analyze the plot size effect on the runoff, solid particles and phosphorous transport processes (see corresponding posters of Jachymova et al., Kavka et al., Laburda et al., Zumr et al.). Running fully agricultural experimental catchment of 49 ha (Nucice, Czech Republic) and experimental soil erosion plots (Bykovice, Czech Republic) we analyze runoff and soil erosion with the aim to upscale the results from single plot studies to the catchment scale. Soil erosion is also monitored by means of spatially distributed soil sampling and photogrammetry analyses. The water flow pathways via subsurface and surface runoff and the temporary variable catchment connectivity are studied here. Finally the research team produced unique large extent study, performed by WATEM/SEDEM model adopted for erosion driven phosphorus fluxes modelling, for the area of 1/3 of the Czech Republic (ca 31500 km2) in the resolution (pixel size) of 10 by 10 meters, with estimated connectivity from single field to outlet reservoirs of large catchments, including stream topology, sediment trapping efficiencies of all ponds and reservoirs within the system. All these studies were dealing with connectivity issues, land-use boundary effects, detailed morphology consequences and (not last) data accuracy implications. In the presentation these issues for a various monitoring and modelling scales will be raised. The paper was prepared within the project of Czech Science Foundation No. 13-20388P using project results of VG20122015092, QI102A265, QJ330118, QJ1230056 and SGS14/180/OHK1/3T/11 grants.

  7. Measurement of the three-dimensional tip region flow field in an axial compressor

    SciTech Connect

    Stauter, R.C. (United Technologies Research Center, East Hartford, CT (United States))

    1993-07-01

    A two-color, five-beam LDV system has been configured to make simultaneous three-component velocity measurements of the flow field in a two-stage axial compressor model. The system has been used to make time-resolved measurements both between compressor blade rows and within the rotating blade passages in an axial compressor. The data show the nature and behavior of the complex, three-dimensional flow phenomena present in the tip region of a compressor as the convect downstream. In particular, the nature of the tip leakage vortex is apparent, being manifested by high blockage as well as the expected vortical motion. The data indicate that the radial flows associated with the tip leakage vortex begin to decrease while within the rotor passage, and that they temporarily increase aft of the passage.

  8. Integral Field Spectroscopy of the Extended Emission-Line Region of 4C 37.43

    E-print Network

    Fu, Hai

    2007-01-01

    We present Gemini integral field spectroscopy and Keck II longslit spectroscopy of the extended emission-line region (EELR) around the quasar 4C 37.43. The velocity structure of the ionized gas is complex and cannot be explained globally by a simple dynamical model. The spectra from the clouds are inconsistent with shock or ``shock + precursor'' ionization models, but they are consistent with photoionization by the quasar nucleus. The best-fit photoionization model requires a low-metallicity (12+log(O/H) density clouds are transient and can be re-generated through compressing the diffuse medium by low-speed shocks (V_S \\lesssim 100 \\kms). Our photoionization model gives a total mass for the ionized gas of about 3x10^{10} M_sun, and the total kinetic energy implied by this mass and the observed velocity f...

  9. Integral Field Spectroscopy of Extended Emission-Line Regions around QSOs

    E-print Network

    Fu, H; Fu, Hai; Stockton, Alan

    2006-01-01

    Luminous extended emission-line regions (EELRs) on kpc scales surround a substantial fraction of steep-spectrum radio-loud QSOs. Although their existence has been known for over three decades, there are still major uncertainties on the physical processes responsible for their complex morphology and kinematics. We are obtaining deep integral field spectroscopy for a sample of EELRs around QSOs at zdensity, temperature, metallicity) and reliable intensity ratios of diagnostic emission lines from individual clouds that comprise an EELR. Here we present results from the observations of the EELR of quasar 4C 37.43. We show maps of gas kinematics measured from the [O III] 5007 line and line-ratio diagnostic diagrams comparing the data with predictions from ionization models. We find that the ionized gas shows rather complex global...

  10. Pre-flare dynamics of chromospheric structures and magnetic field in the active region NOAA 9077

    NASA Astrophysics Data System (ADS)

    Golovko, A. A.; Salakhutdinova, I. I.; Khlystova, A. I.

    2002-12-01

    The object of the study was the active region (AR) NOAA 9077, which produced three flares of importance X. At Baikal Observatory, the observations of full disc solar chromosphere in H-alpha line with Halle birefringent filter, were carried out on July 10-14. The magnetograms of the AR, of Beijing Observatory, were used as additional data. A characteristic property of the AR 9077 evolution was the emergence of new magnetic flux on July 10-11 and the absence of any indications thereof on July 12-14 prior to a powerful flare. However, another process of fast changes in the magnetic field was revealed - magnetic cancellation, which proceeded at about the same rate as did the new flux emergence. The magnetic flux imbalance increased towards south polarity predominance during July 10-12, followed by its fast decrease before the major flare. The flares were preceded by fine structure of chromosphere changes.

  11. Mass Motions Under the Influence of the Magnetic Field in Solar Active Regions

    NASA Astrophysics Data System (ADS)

    Georgakilas, A. A.

    1992-03-01

    We have studied the development of active region arch structures in H? and mass motions associated with them. Our emphasis was on the spatial structure and the temporal evolution of the velocity. We reconstructed the velocity vector along the arch filaments and computed models for the material flow. A large developing active region (Mc Math No 16315) was observed for six days from September 25 to September 30 1979. The observations were obtained with a Halle H? filter (0.5 Passband) mounted on the 50 cm "Tourelle" refractor of the Pic-du-Midi Observatory. On the first day of our observations the active region consisted of only two well developed spots, while on the sixth day it had many large spots and its structure was quite complex. We also used observations of an arch filament system (AFS) in NOAA region 4819 made on June 22, 1987 covering a time interval of 15 m 27 sec. These observations were obtained with the Multichannel Double Pass Spectograph (MSDP) mounted on the 50 cm "Tourelle" refractor of the Pic-du-Midi observatory. The MSDP provides 10 simultaneous intensity images of the same region, 0.256 Angstrem apart in the H? line. We developed a method for the computation of the line-of-sight velocity from photographs at H?+- 0.5 Angstrem, under the assumption of Becker's cloud model and resonable assumptions about the Doppler width and optical depth of the arches. For the MSDP data we reconstructed line profiles and monochromatic images and we measured Doppler velocities. Furthemore, using Becker's cloud model, we derived physical parameters and in particular the line of sight velocity. from the line of sight component of the velocity we computed the horizontal and the vertical components along the arch filaments. For this purpose we reconstructed the three dimensional shape of the loops, assuming that they were symmetric with respect to the apex. Finally we have studied the motion of an inviscid isothermal plasma under the influence of gravity in an translational symmetric magnetic field. We considered a time varying flow along a steady loop. The solutions of the MHD eauations were compared with the observations of the material flow in the arch filaments.

  12. Two-color field for the generation of an isolated attosecond pulse in water-window region.

    PubMed

    Chen, Wenxiang; Chen, Guanglong; Kim, Dong Eon

    2011-10-10

    For the investigation of various ultrafast electron dynamics, an isolated attosecond pulse in a broad spectral range is necessary. The generation of isolated attosecond pulses demands the manipulation of the electric field of a laser. We propose a two-color field scheme for generating an isolated attosecond pulse in the water-window region. Two-color fields are generated by mixing two equally-strong pulsed color fields. The investigation shows that an isolated attosecond pulse with a photon energy of near 500 eV and a pulse duration of 125 - 188 attoseconds can be generated using 10 - 15 fs FWHM laser fields. PMID:21997069

  13. Spatio-Temporal Scaling of Turbulent Photospheric Line-of-Sight Magnetic Field in Active Region NOAA 11158

    NASA Astrophysics Data System (ADS)

    Guerra, J. A.; Pulkkinen, A.; Uritsky, V. M.; Yashiro, S.

    2015-02-01

    We studied the structure and dynamics of the turbulent photospheric magnetic field in active region NOAA 11158 by characterizing spatial and temporal scaling properties of the line-of-sight (LOS) component. Using high-resolution high-cadence LOS magnetograms from SDO/HMI, we measured the power-law exponents ? and ? that describe Fourier power spectra in wavenumber ( k) and frequency ( f) domains, and we investigated their evolution during the passage of the active region through the field of view of HMI. The flaring active region NOAA 11158 produces a one-dimensional spatial power spectral density that approximately follows a k -2 power law - a spectrum that suggests parallel MHD fluctuations in an anisotropic turbulent medium. In addition, we found that the values of ? capture systematically change in the configuration of the LOS photospheric magnetic field during flaring activity in the corona. Position-dependent values of the temporal scaling exponent ? showed that, on an average, the core of the active region scales with ?>3 surrounded by a diffusive region with an approximately f -2-type spectrum. Our results indicate that only about 1 - 3 % of the studied LOS photospheric magnetic flux displays ?? ?, implying that Taylor's hypothesis of frozen-in-flow turbulence is typically invalid for this scalar field in the presence of turbulent photospheric flows. In consequence, both spatial and temporal variations of the plasma and magnetic field must be included in a complete description of the turbulent evolution of active regions.

  14. Evolution of the magnetic fields of solar flare active regions from the geometry and topology of HMI/SDO magnetograms

    NASA Astrophysics Data System (ADS)

    Knyazeva, I. S.; Makarenko, N. G.

    2014-03-01

    The testing and development of topological approaches to the analysis of solar magnetic fields are considered. A technique based on the geometry of random fields, mathematical morphology and topology, and scale-space analyses are applied to describe and diagnose the pre-flare dynamics of the magnetic fields of solar active regions using HMI/SDO magnetograms. The results show that this formalism can be used to diagnose pre-flare dynamics over time intervals that are of practical interest.

  15. Dependence of spectral width of ionospheric F region HF echoes on electric field

    NASA Astrophysics Data System (ADS)

    Kozlovsky, A.; Shalimov, S.; Koustov, A. V.; Lukianova, R.; Turunen, T.

    2011-07-01

    The EISCAT Svalbard radar (ESR) monitors plasma parameters in the ionospheric region that is frequently located near the polar cap boundary. The SuperDARN radar at Hankasalmi, Finland, detects coherent echoes from this region, and these echoes typically show increased spectral width. We consider data of joint ESR and SuperDARN observations to show that the spectral width of HF echoes tends to increase with the ionospheric electric field. This relationship is explained in terms of nonlinear evolution of the E × B gradient drift instability with energy cascade from hundreds of meter wavelengths to meter wavelengths. We assume that decameter waves (seen by the Hankasalmi radar) with relatively large amplitude decay through a three-wave interaction with shorter wavelengths and estimate that the decay time of the decameter waves/irregularities is determined by the parameters of the shorter-wavelength structures. We associate the decameter wave decay time with the correlation time, and thus the spectral width, of HF echoes.

  16. Integral Field Spectroscopy of the Extended Emission-Line Region of 3C 249.1

    E-print Network

    Hai Fu; Alan Stockton

    2006-06-29

    We present Gemini Multiobject Spectrograph integral field spectroscopy of the extended emission-line region associated with quasar 3C 249.1. The kinematics of the ionized gas measured from the [O III] $\\lambda$5007 line is rather complex and cannot be explained globally by a simple dynamical model, but some clouds can be modeled individually as having locally linear velocity gradients. The temperatures of the ionized gas appear uniform (varying from ~12000 to 15000 K), while the densities vary from a few tens to a few hundreds cm^{-3}. The emission mechanism of all of the emission clouds, as indicated by the line-ratio diagnostics, is consistent both with "shock + precursor" and pure photoionization models. The total mass of the ionized gas is on the order of 10^9 M_Sun. We estimate the bulk kinetic energy and momentum of the extended emission-line region of 2.5*10^{57} ergs and 10^{50} dyne s, and a dynamical timescale of ~10 Myr. By comparing the injection rates of kinetic energy and momentum of different galactic wind models with the observation, we argue that the emission-line clouds are most likely a direct result from the feedback of the quasar. We also discuss the nature of the extended X-ray emission surrounding the quasar.

  17. Integral Field Spectroscopy of the Extended Emission-Line Region of 4C 37.43

    E-print Network

    Hai Fu; Alan Stockton

    2007-05-30

    We present Gemini integral field spectroscopy and Keck II longslit spectroscopy of the extended emission-line region (EELR) around the quasar 4C 37.43. The velocity structure of the ionized gas is complex and cannot be explained globally by a simple dynamical model. The spectra from the clouds are inconsistent with shock or ``shock + precursor'' ionization models, but they are consistent with photoionization by the quasar nucleus. The best-fit photoionization model requires a low-metallicity (12+log(O/H) density clouds are transient and can be re-generated through compressing the diffuse medium by low-speed shocks (V_S \\lesssim 100 \\kms). Our photoionization model gives a total mass for the ionized gas of about 3x10^{10} M_sun, and the total kinetic energy implied by this mass and the observed velocity field is ~2x10^{58} ergs. The fact that luminous EELRs are confined to steep-spectrum radio-loud quasars, yet show no morphological correspondence to the radio jets, suggests that the driving force producing the 4C 37.43 EELR was a roughly spherical blast wave initiated by the production of the jet. That such a mechanism seems capable of ejecting a mass comparable to that of the total interstellar medium of the Milky Way suggests that ``quasar-mode'' feedback may indeed be an efficient means of regulating star formation in the early universe.

  18. Integral Field Spectroscopy of Extended Emission-line Regions around QSOs

    NASA Astrophysics Data System (ADS)

    Fu, H.; Stockton, A.

    2007-10-01

    Luminous extended emission-line regions (EELRs) on kpc scales surround a substantial fraction of steep-spectrum radio-loud QSOs. Although their existence has been known for over three decades, there are still major uncertainties on the physical processes responsible for their complex morphology and kinematics. We are obtaining deep integral field spectroscopy for a sample of EELRs around QSOs at z?0.5 with the Integral Field Unit (IFU) of the GMOS on the Gemini North telescope, aiming at extracting accurate kinematics of the EELRs, measuring important physical parameters (eg density, temperature, metallicity) and reliable intensity ratios of diagnostic emission lines from individual clouds that comprise an EELR. Here we present results from the observations of the EELR of quasar 4C 37.43. We show maps of gas kinematics measured from the [O III] ?5007 line and line-ratio diagnostic diagrams comparing the data with predictions from ionization models. We find that the ionized gas shows rather complex global kinematics, while linear velocity gradients are often seen in individual clouds. Pure photoionization by the QSO continuum is the most likely ionization mechanism for most of the EELR clouds.

  19. Analysis of magnetic fields in a plage region using a spatially coupled 2D inversion technique

    NASA Astrophysics Data System (ADS)

    Buehler, David; Lagg, Andreas; Solanki, Sami K.; Van Noort, Michiel

    The properties of magnetic features (MFCs) within a plage region in the vicinity of a sunspot were investigated at high spatial resolution. Stokes spectra of the 630nm line pair recorded by the spectropolarimeter aboard Hinode were inverted using an extended version of the SPINOR code. The code preformed a spatially coupled inversion of the Stokes spectra using three log(tau) nodes in optical depth. No magnetic filling factors was employed. The analysis of the inversion results reveals that the MFCs have typical field strengths of 1500G at log(tau)=-0.9 and inclinations between 10-15 degrees in all three log(tau) nodes. The MFCs expand by forming magnetic canopies composed of weaker and more inclined magnetic fields. The expansion of the magnetic field and temperature stratification of MFCs with optical depth is in good agreement with a thin flux tube model. Whilst the gas inside magnetic flux concentrations is typically at rest, the majority of MFCs were surrounded by a ring of downflows with an average value of 2.5km/s at log(tau)=0. The ring gradually shifts outwards following the expansion of the MFC. Within the downflow rings of MFCs small magnetic patches of opposite polarity to that of the main MFC were identified, which are predominantly situated beneath the canopy of its main MFC. We found evidence for a strong broadening of the Stokes profiles within MFCs and their surrounding downflow rings (expressed by a microturbulence in the inversion). This indicates the presence of strong unresolved velocities.

  20. Experimental studies on remanence acquisition processes and regional geomagnetic field variability from archeointensity studies

    NASA Astrophysics Data System (ADS)

    Mitra, Ritayan

    The dissertation comprises two separate topics. Chapters 2 and 3 are experimental studies on remanence acquisition processes. Chapters 4 and 5 investigate the geomagnetic field variability in Africa and India between 1000 BCE and 1000 CE. Chapter 2 is a study in which the role of flocculation in sedimentary magnetization is analyzed with the help of laboratory redeposition experiments and a simple numerical model. At small floc sizes DRM acquisition is likely to be non-linear but it may record the directions with higher fidelity. In environments having bigger flocs the sediments are likely to record either intensities or directions with high fidelity, but not both. Also flocculation may inhibit a large fraction of magnetic grains from contributing to the net remanence and this might have consequences for intensity normalization in sediments. Chapter 3 presents a fresh perspective on the long standing debate of the nature of magnetocrystalline anisotropy in Mid-Ocean Ridge Basalts (MORBs). A new parameter, IRAT, defined as the ratio of the isothermal remanences in antiparallel directions is used to differentiate between uniaxial single domain grains (IRAT ˜1) and multiaxial single domain grains (IRAT<1). The theoretical predictions were first validated with standard samples and then multiple MORB samples were analyzed. The observed IRAT ratios indicate a dominant non-uniaxial anisotropy in the MORBs. Chapters 4 and 5 are archeointensity studies from two data poor regions of the world viz., Africa and India. With stringent data selection criteria and well established archeological constraints these datasets provide important constraints on the field intensity from 1000 BCE to 1000 CE in Africa and 500 BCE to 1000 CE in India. The African dataset has a higher age resolution than the Indian dataset. The African dataset matches well with the global CALS3k.4 model and shows significant non-axial-dipolar contribution in the region. The Indian dataset is not of a similar resolution but shows that the field might have dropped by as much as 40% in the first half of the first century BCE and remained low during the first century CE.

  1. Field Significance of Performance Measures in the Context of Regional Climate Model Verification

    NASA Astrophysics Data System (ADS)

    Ivanov, Martin; Warrach-Sagi, Kirsten; Wulfmeyer, Volker

    2015-04-01

    The purpose of this study is to rigorously evaluate the skill of dynamically downscaled global climate simulations. We investigate a dynamical downscaling of the ERA-Interim reanalysis using the Weather Research and Forecasting (WRF) model, coupled with the NOAH land surface model within the scope of EURO-CORDEX. WRF has a horizontal resolution of 11° and contains the following physics: the Yonsei university atmospheric boundary layer parameterization, the Morrison two-moment microphysics, the Kain-Fritsch-Eta convection and the Community Atmosphere Model radiation schemes. Daily precipitation is verified over Germany for summer and winter against high-resolution observation data from the German weather service for the first time. The ability of WRF to reproduce the statistical distribution of daily precipitation is evaluated using metrics based on distribution characteristics. Skill against the large-scale ERA-Interim data gives insight into the potential, additional skill of dynamical downscaling. To quantify it, we transform the absolute performance measures to relative skill measures against ERA-Interim. Their field significance is rigorously estimated and locally significant regions are highlighted. Statistical distributions are better reproduced in summer than in winter. In both seasons WRF is too dry over mountain tops due to underestimated and too rare high and underestimated and too frequent small precipitations. In winter WRF is too wet at windward sides and land-sea transition regions due to too frequent weak and moderate precipitation events. In summer it is too dry over land-sea transition regions due to underestimated small and too rare moderate precipitations, and too wet in some river valleys due to too frequent high precipitations. Additional skill relative to ERA-Interim is documented for overall measures as well as measures regarding the spread and tails of the statistical distribution, but not regarding mean seasonal precipitation. The added value is spatially more widespread and regards more performance measures in summer, while in winter it is concentrated in mountains. Precipitation intensity is generally improved, deterioration is only documented in summer in land-sea transition regions due to the underestimated small intensities. The frequencies of all precipitation categories are improved in summer. In winter the moderate category shows no skill; significant deterioration is observable due to overprediction of wet-days on windward sides, of small precipitation events in the northern lowlands and of high precipitation events in the North-West coast and the heaths north of the Ore mountains as well as underprediction of high precipitation events in some concave topography forms. This study demonstrates in a rigorous manner the clear additional value of dynamical downscaling over global climate simulations.

  2. Simultaneous Observations of E-Region Coherent Backscatter and Electric Field Amplitude at F-Region Heights with the

    E-print Network

    Foster, John C.

    Abstract A combined coherent backscatter - incoherent scatter experiment was performed with the Millstone observations of electric field magnitude and coherent backscatter parameters on the same L shell. A carefully to Vph. With the assumption that the coherent phase velocity is approximately the perturbed ion sound

  3. Evolution of Magnetic Field and Energy in a Major Eruptive Active Region Based on SDO/HMI Observation

    NASA Astrophysics Data System (ADS)

    Sun, Xudong; Hoeksema, J. Todd; Liu, Yang; Wiegelmann, Thomas; Hayashi, Keiji; Chen, Qingrong; Thalmann, Julia

    2012-04-01

    We report the evolution of the magnetic field and its energy in NOAA active region 11158 over five days based on a vector magnetogram series from the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamic Observatory (SDO). Fast flux emergence and strong shearing motion led to a quadrupolar sunspot complex that produced several major eruptions, including the first X-class flare of Solar Cycle 24. Extrapolated nonlinear force-free coronal fields show substantial electric current and free energy increase during early flux emergence near a low-lying sigmoidal filament with a sheared kilogauss field in the filament channel. The computed magnetic free energy reaches a maximum of ~2.6 × 1032 erg, about 50% of which is stored below 6 Mm. It decreases by ~0.3 × 1032 erg within 1 hr of the X-class flare, which is likely an underestimation of the actual energy loss. During the flare, the photospheric field changed rapidly: the horizontal field was enhanced by 28% in the core region, becoming more inclined and more parallel to the polarity inversion line. Such change is consistent with the conjectured coronal field "implosion" and is supported by the coronal loop retraction observed by the Atmospheric Imaging Assembly (AIA). The extrapolated field becomes more "compact" after the flare, with shorter loops in the core region, probably because of reconnection. The coronal field becomes slightly more sheared in the lowest layer, relaxes faster with height, and is overall less energetic.

  4. Nitrous Oxide Concentration Profiles and the Natural Abundance of 15N-N2O in a Paddy Soil During the Wheat Growing Season

    NASA Astrophysics Data System (ADS)

    Xiong, Z.; Khalil, A. M.; Shearer, M.; Butenhoff, C.; Xing, G.

    2006-12-01

    Soil is an important source of nitrous oxide. Significant temporal and spatial trends exist in the production and emission in paddy fields where upland winter wheat is grown. A multilevel sampling probe (0-5cm, 5-10cm, 10- 15cm, and 15-20 cm) was designed to sample the air in the soil. Changes in N2O gas concentrations in 24 profiles were studied at 10-day intervals during the wheat growing period, for 16 total sampling dates. Surface fluxes were studied simultaneously from 24 field plots (4m x 5m). The natural abundance of 15N2O in eight profiles was measured three times during the wheat season by using a MAT 253 isotope mass chromatograph. Dynamic soil ammonium and nitrate concentrations in the plough layer and profile soil redox potential were also monitored throughout the wheat season. We present the first in situ data of such gradients over time for a paddy field seeded with wheat. Results indicate that N2O was produced at the lower levels of 10cm-15cm and 15-20cm, and that denitrification was the dominant process for N2O production even under the aerobic wheat cropping condition. N2O at 10-15cm depth has the most negative natural abundance of 15N. Profiles with higher concentrations of soil nitrate give more negative values of natural abundance of 15N2O. The lower levels of 10cm-15cm and 15cm-20cm give the highest concentrations during the whole wheat growing season. The maximum concentration of 14.8 mL m-3 and the maximum flux of 126 micro g N m-2 h-1 were found in January and April, respectively. N2O concentrations are significantly correlated between all layers over time. Spatial variations exist in N2O emissions and concentration profiles, but temporal variations are greater. The N2O emission peaks did not always coincide with soil concentration peaks. These results suggest that to understand the underlying processes, we need to measure both surface fluxes and soil concentrations simultaneously. This research was supported by the Office of Science (BER), US Department of Energy, Grant No. DE-FG02- 04ER63913, and the Institute of Soil Sciences, Chinese Academy of Sciences.

  5. Effects of Enzyme Complex Supplementation to a Paddy-based Diet on Performance and Nutrient Digestibility of Meat-type Ducks

    PubMed Central

    Kang, P.; Hou, Y. Q.; Toms, Derek; Yan, N. D.; Ding, B. Y.; Gong, Joshua

    2013-01-01

    Paddy rice is rarely used as a feed because of its high fiber content. In this study, two experiments were conducted to study the effects of supplementing an enzyme complex consisting of xylanase, beta-glucanase and cellulase, to paddy-based diets on the performance and nutrient digestibility in meat-type ducks. In the both experiments, meat-type ducks (Cherry Valley) were randomly assigned to four treatments. Treatment 1 was a basal diet of corn-soybean; treatment 2 was a basal diet of corn-paddy-soybean; treatment 3, had enzyme complex added to the corn-paddy-soybean basal diet at levels of 0.5 g/kg diet; and treatment 4, had enzyme complex added to the corn-paddy-soybean diet at levels of 1.0 g/kg diet. The results showed that the enzyme complex increased the ADG, and decreased the ADFI and F/G significantly (p<0.05) in the ducks, and the ADFI for the ducks fed the corn-paddy-soybean diet showed no difference compared to the ducks fed corn-soybean diets at all stages of the experiment (p<0.05). When corn was partially replaced by paddy, the digestibility of CP and NDF was decreased and increased, respectively (p<0.05), and the level of enzyme complex had a significant effect on both CP and NDF digestibility (p<0.05). As for the AME, addition of enzyme complex increased it significantly (p<0.05), but both diet types and levels of enzyme complex had no effect (p>0.05). The outcome of this research indicates that the application of enzyme complex made up of xylanase, beta-glucanase, and cellulase, in the corn-paddy-soybean diet, can improve performance and nutrition digestibility in meat-type ducks. PMID:25049784

  6. Regional-Scale Salt Tectonics Modelling: Bench-Scale Validation and Extension to Field-Scale

    NASA Astrophysics Data System (ADS)

    Crook, A. J. L.; Yu, J. G.; Thornton, D. A.

    2010-05-01

    The role of salt in the evolution of the West African continental margin, and in particular its impact on hydrocarbon migration and trap formation, is an important research topic. It has attracted many researchers who have based their research on bench-scale experiments, numerical models and seismic observations. This research has shown that the evolution is very complex. For example, regional analogue bench-scale models of the Angolan margin (Fort et al., 2004) indicate a complex system with an upslope extensional domain with sealed tilted blocks, growth fault and rollover systems and extensional diapers, and a downslope contractional domain with squeezed diapirs, polyharmonic folds and thrust faults, and late-stage folding and thrusting. Numerical models have the potential to provide additional insight into the evolution of these salt driven passive margins. The longer-term aim is to calibrate regional-scale evolution models, and then to evaluate the effect of the depositional history on the current day geomechanical and hydrogeologic state in potential target hydrocarbon reservoir formations adjacent to individual salt bodies. To achieve this goal the burial and deformational history of the sediment must be modelled from initial deposition to the current-day state, while also accounting for the reaction and transport processes occurring in the margin. Accurate forward modeling is, however complex, and necessitates advanced procedures for the prediction of fault formation and evolution, representation of the extreme deformations in the salt, and for coupling the geomechanical, fluid flow and temperature fields. The evolution of the sediment due to a combination of mechanical compaction, chemical compaction and creep relaxation must also be represented. In this paper ongoing research on a computational approach for forward modelling complex structural evolution, with particular reference to passive margins driven by salt tectonics is presented. The approach is an extension of a previously published approach (Crook et al., 2006a, 2006b) that focused on predictive modelling of structure evolution in 2-D sandbox experiments, and in particular two extensional sand box experiments that exhibit complex fault development including a series of superimposed crestal collapse graben systems (McClay, 1990) . The formulation adopts a finite strain Lagrangian method, complemented by advanced localization prediction algorithms and robust and efficient automated adaptive meshing techniques. The sediment is represented by an elasto-viscoplastic constitutive model based on extended critical state concepts, which enables representation of the combined effect of mechanical and chemical compaction. This is achieved by directly coupling the evolution of the material state boundary surface with both the mechanically and chemically driven porosity change. Using these procedures the evolution of the geological structures arises naturally from the imposed boundary conditions without the requirement of seeding using initial imperfections. Simulations are presented for regional bench-scale models based on the analogue experiments presented by Fort et al. (2004), together with additional insights provided by the numerical models. It is shown that the behaviour observed in both the extensional and compressional zones of these analogue models arises naturally in the finite element simulations. Extension of these models to the field-scale is then discussed and several simulations are presented to highlight important issues related to practical field-scale numerical modelling.

  7. Application of SVM on satellite images to detect hotspots in Jharia coal field region of India

    NASA Astrophysics Data System (ADS)

    Gautam, R. S.; Singh, D.; Mittal, A.; Sajin, P.

    The present paper deals with the application of Support Vector Machine (SVM) and image analysis techniques on NOAA/AVHRR satellite image to detect hotspots on the Jharia coal field region of India. One of the major advantages of using these satellite data is that the data are free with very good temporal resolution; while, one drawback is that these have low spatial resolution (i.e., approximately 1.1 km at nadir). Therefore, it is important to do research by applying some efficient optimization techniques along with the image analysis techniques to rectify these drawbacks and use satellite images for efficient hotspot detection and monitoring. For this purpose, SVM and multi-threshold techniques are explored for hotspot detection. The multi-threshold algorithm is developed to remove the cloud coverage from the land coverage. This algorithm also highlights the hotspots or fire spots in the suspected regions. SVM has the advantage over multi-thresholding technique that it can learn patterns from the examples and therefore is used to optimize the performance by removing the false points which are highlighted in the threshold technique. Both approaches can be used separately or in combination depending on the size of the image. The RBF (Radial Basis Function) kernel is used in training of three sets of inputs: brightness temperature of channel 3, Normalized Difference Vegetation Index (NDVI) and Global Environment Monitoring Index (GEMI), respectively. This makes a classified image in the output that highlights the hotspot and non-hotspot pixels. The performance of the SVM is also compared with the performance obtained from the neural networks and SVM appears to detect hotspots more accurately (greater than 91% classification accuracy) with lesser false alarm rate. The results obtained are found to be in good agreement with the ground based observations of the hotspots. This type of work will be quite helpful in the near future to develop a hotspots monitoring system using these operational satellites data.

  8. Pesticide multiresidue determination in rice paddy water by gas chromatography coupled with triple quadrupole mass spectrometry.

    PubMed

    Pereira, Mateus B; Facco, Janice F; Zemolin, Gabriela M; Martins, Manoel L; Prestes, Osmar D; Zanella, Renato; Adaime, Martha B

    2014-01-01

    Pollution of water sources by pesticides is a result of intensive use of these compounds, and the establishment of analytical methods for monitoring programs is very important. This paper presents a method for the determination of multiclass pesticide residues in rice paddy water based on SPE and GC/MS/MS. The validation results were satisfactory. All compounds showed adequate linearity (r2 >or= 0.99), and analysis by GC/MS/MS with a triple quadrupole mass spectrometer gave high selectivity and sensitivity. With the proposed SPE step an LOD of 0.06 microg/L was achieved. Recoveries from blank samples spiked at 0.2, 04, and 0.8 microg/L were between 70 and 120% with RSD <20% for most analyzed compounds, despite their different chemical nature, indicating good accuracy and precision. The proposed method is efficient for pesticide residue determination, including some metabolites, and gave good performance when applied to real samples. PMID:25145127

  9. Effect of processing paddy on digestibility of rice starch by in vitro studies.

    PubMed

    Chitra, M; Singh, Vasudeva; Ali, S Z

    2010-08-01

    Paddy (Oryza sativa L) (variety 'IR - 64'), was parboiled, puffed by sand roasting and flaked by edge runner and roller flaker and variations in physical and physicochemical properties were studied. Moisture contents were lower (5.8-10.8%) in processed rice products compared to raw materials (11.8%). Ratio of rice to sand in the case of puffed rice preparation was optimized. The equilibrium moisture content was 27.4% in raw rice while it was much higher (38.9-81.0%) in processed rice. Sedimentation volume was lowest (6.2 ml) in raw rice and highest (18.8 ml) in popped rice. Starch content was 84.8 and 76.5-83% in raw and processed rice, respectively. In vitro starch digestibility was highest in roller flaker flakes and lowest in raw milled rice. Among the ready to eat products, popped rice showed least starch digestibility (?30%). PMID:23572662

  10. Effects of organic nitrification inhibitors on methane and nitrous oxide emission from tropical rice paddy

    NASA Astrophysics Data System (ADS)

    Datta, A.; Adhya, T. K.

    2014-08-01

    We have studied the effects of application of different nitrification inhibitors on methane (CH4) and nitrous oxide (N2O) emissions from rice paddy and associated soil chemical and biological dynamics during wet and dry seasons of rice crop in a tropical climate of eastern India. The experiment consisted of four treatments viz. (i) Prilled urea amended control (ii) urea + Dicyandiamide (DCD), (iii) urea + Nimin and (iv) urea + Karanjin. CH4 emission was significantly higher from the DCD (372.36 kg ha-1) and Karanjin (153.07 kg ha-1) applied plots during the wet and dry season, respectively. N2O emission was significantly inhibited in the Nimin applied plots during both seasons (69% and 85% over control during wet season and dry season respectively). CH4 and N2O emissions per Mg of rice grain yield were lowest from the Nimin applied plots during both seasons. Global warming potential (GWP) of the plot treated with DCD (13.93) was significantly higher during the experimental period. CH4 production potential was significantly higher from the nitrification inhibitor applied plots compared to control. While, CH4 oxidation potential followed the order; urea + Nimin > urea + Karanjin > urea + DCD > control. Application of Nimin significantly increased the methanotrophic bacterial population in the soil during the maximum tillering to flowering stage and may be attributed to low CH4 emission from the plots. Denitrification enzyme activity (DEA) of the soil was significantly low from the Nimin and Karanjin applied plots. Results suggest that apart from being potent nitrification inhibitors, Nimin and Karanjin also have the potential to reduce the denitrification activity in the soil. This in turn, would reduce N2O emission from flooded paddy where both nitrification and denitrification processes causes N2O emission.

  11. Effects of Carbon in Flooded Paddy Soils: Implications for Microbial Activity and Arsenic Mobilization

    NASA Astrophysics Data System (ADS)

    Avancha, S.; Boye, K.

    2014-12-01

    In the Mekong delta in Cambodia, naturally occurring arsenic (originating from erosion in the Himalaya Mountains) in paddy soils is mobilized during the seasonal flooding. As a consequence, rice grown on the flooded soils may take up arsenic and expose people eating the rice to this carcinogenic substance. Microbial activity will enhance or decrease the mobilization of arsenic depending on their metabolic pathways. Among the microbes naturally residing in the soil are denitrifying bacteria, sulfate reducers, metal reducers (Fe, Mn), arsenic reducers, methanogens, and fermenters, whose activity varies based on the presence of oxygen. The purpose of the experiment was to assess how different amendments affect the microbial activity and the arsenic mobilization during the transition from aerobic to anaerobic metabolism after flooding of naturally contaminated Cambodian soil. In a batch experiment, we investigated how the relative metabolic rate of naturally occurring microbes could vary with different types of organic carbon. The experiment was designed to measure the effects of various sources of carbon (dried rice straw, charred rice straw, manure, and glucose) on the microbial activity and arsenic release in an arsenic-contaminated paddy soil from Cambodia under flooded conditions. All amendments were added based on the carbon content in order to add 0.036 g of carbon per vial. The soil was flooded with a 10mM TRIS buffer solution at pH 7.04 in airtight 25mL serum vials and kept at 25 °C. We prepared 14 replicates per treatment to sample both gas and solution. On each sampling point, the solution replicates were sampled destructively. The gas replicates continued on and were sampled for both gas and solution on the final day of the experiment. We measured pH, total arsenic, methane, carbon dioxide, and nitrous oxide at 8 hours, 1.5 days, 3.33 days, and 6.33 days from the start of the experiment.

  12. Wavelength selection and spectral discrimination for paddy rice, with laboratory measurements of hyperspectral leaf reflectance

    NASA Astrophysics Data System (ADS)

    Song, Shalei; Gong, Wei; Zhu, Bo; Huang, Xin

    2011-09-01

    The objective of this research is to select the most sensitive wavelengths for the discrimination of the imperceptible spectral variations of paddy rice under different cultivation conditions. The paddy rice was cultivated under four different nitrogen cultivation levels and three water irrigation levels. There are 2151 hyperspectral wavelengths available, both in hyperspectral reflectance and energy space transformed spectral data. Based on these two data sets, the principal component analysis (PCA) and band-band correlation methods were used to select significant wavelengths with no reference to leaf biochemical properties, while the partial least squares (PLS) method assessed the contribution of each narrow band to leaf biochemical content associated with each loading weight across the nitrogen and water stresses. Moreover, several significant narrow bands and other broad bands were selected to establish eight kinds of wavelength (broad-band) combinations, focusing on comparing the performance of the narrow-band combinations instead of broad-band combinations for rice supervising applications. Finally, to investigate the capability of the selected wavelengths to diagnose the stress conditions across the different cultivation levels, four selected narrow bands (552, 675, 705 and 776 nm) were calculated and compared between nitrogen-stressed and non-stressed rice leaves using linear discriminant analysis (LDA). Also, wavelengths of 1158, 1378 and 1965 nm were identified as the most useful bands to diagnose the stress condition across three irrigation levels. Results indicated that good discrimination was achieved. Overall, the narrow bands based on hyperspectral reflectance data appear to have great potential for discriminating rice of differing cultivation conditions and for detecting stress in rice vegetation; these selected wavelengths also have great potential use for the designing of future sensors.

  13. Specific features of gas-discharge closing when a shock wave passes through the region of an applied electric field

    NASA Astrophysics Data System (ADS)

    Lapushkina, T. A.; Erofeev, A. V.

    2015-03-01

    The influence of a low-temperature plasma on the intensity and propagation rate of strong shock waves with a Mach number M = 6-8 has been analyzed. Propagation of a shock wave through the region of an electric field caused by voltage preliminarily fed to special electrodes built into the direct-channel walls where the shock wave passes has been considered in the current stage. It is found that the gas discharge in the region of an applied electric field is closed by an individual gas-discharge channel arising after the shock wave and propagating through the region of applied voltage at a lower speed compared with the shock wave. Neither the gas-discharge channel with a turbulent structure nor the region of homogeneous gas discharge arising after it affect the shock-wave structure and propagation rate.

  14. Population development of the mosquitofish, Gambusia affinis , in rice fields

    Microsoft Academic Search

    Louis W. Blotsfordl; Bruce Vondracekl; Thomas C. Wainwright; Alison L. Linden; Robert G. Kopel; David E. Reed; Joseph J. Cech

    1987-01-01

    Development of mosquitofish,Gambusia affinis, stocks in rice fields following stocking for mosquito control is poorly understood and highly variable. To characterize population development and explain observed variability, size distributions and total numbers of mosquitofish stocks were followed from stocking through the end of the summer rice season in several experimental rice paddies. Instead of the highly variable, logistic growth implied

  15. Examination of the dominant azimuthal structures in the near-field pressure region of a high-speed turbulent jet

    NASA Astrophysics Data System (ADS)

    Hall, AndrÉ.}

    2005-11-01

    Numerous experiments have been conducted on characterizing the near-field region of the turbulent axisymmetric jet. The modal distribution of the velocity field has been shown to be characterized by a substantial amount of energy, both in the lower Fourier-azimuthal modes (0,1,& 2), as well as the higher modes (4,5,& 6). The near-field pressure region has demonstrated energy in the lower azimuthal modes (0,1,& 2) only. Capturing the signature of higher modes known to be present in the velocity field, in the pressure field, would be valuable in a controls application. In particular if sensed at the jet lip. Experiments are conducted using a jet nozzle 50.8mm in diameter at exit, with a flow temperature of 25^oC, balanced with ambient conditions. Fluctuating pressure measurements are captured by an azimuthal array of 15 Kulite transducers, at an exit velocity of Mach 0.85 (Re=9.8E5). The array is repositioned downstream at several streamwise locations in the fully turbulent, high Reynolds number compressible flow field in an attempt to capture the higher modes found in the velocity field. If no signature of higher modes is found in the fluctuating pressure field at locations where the higher modes are present in the velocity field, these experiments will confirm that pressure cannot resolve these higher modal events. A transfer function between the two distributions can also be evaluated.

  16. Geochemical associations and availability of cadmium (Cd) in a paddy field system, Northwestern Thailand 

    E-print Network

    Kosolsaksakul, Peerapat

    2014-11-27

    The Mae Tao watershed, northwestern Thailand, has become contaminated with cadmium (Cd) from the zinc mining activities area in the nearby Thanon-Thongchai mountains. Consumption of Cd-contaminated rice has led to ...

  17. Integral Field Spectroscopy of Extended Emission-Line Regions around QSOs

    E-print Network

    Hai Fu; Alan Stockton

    2006-12-15

    Luminous extended emission-line regions (EELRs) on kpc scales surround a substantial fraction of steep-spectrum radio-loud QSOs. Although their existence has been known for over three decades, there are still major uncertainties on the physical processes responsible for their complex morphology and kinematics. We are obtaining deep integral field spectroscopy for a sample of EELRs around QSOs at zdensity, temperature, metallicity) and reliable intensity ratios of diagnostic emission lines from individual clouds that comprise an EELR. Here we present results from the observations of the EELR of quasar 4C 37.43. We show maps of gas kinematics measured from the [O III] 5007 line and line-ratio diagnostic diagrams comparing the data with predictions from ionization models. We find that the ionized gas shows rather complex global kinematics, while linear velocity gradients are often seen in individual clouds. Pure photoionization by the QSO continuum is the most likely ionization mechanism for most of the EELR clouds.

  18. Intestinal Helminthic Infections in Striped Field Mice, Apodemus agrarius, from Two Southern Regions of Korea

    PubMed Central

    Na, Byoung-Kuk; Song, Hyeon-Je; Kim, Chung-Mo; Nam, Gi-Jin

    2014-01-01

    The present study was performed to know the infection status of intestinal helminths in a most common species of field mice, Apodemus agrarius, from 2 southern regions of Korea. Total 133 and 103 mice were collected by the mouse trap in Hapcheon-gun, Gyeongsangnam-do and Gurye-gun, Jeollanam-do, respectively, from July 2005 to June 2006. The small intestine of each mouse was resected and longitudinally opened with a pair of scissors. The intestinal contents were washed with 0.85% saline until the supernatant became clear. Helminths were collected with naked eyes or under a stereomicroscope from the sediment of the intestinal content. More than 11 species of helminths (4 nematode spp., 5 trematode spp., and 2 cestode spp.) were recovered. Among these, heligmosomoid nematodes (97.5%) was the most highly and heavily infected species. As the members of trematodes, Plagiorchis muris, Brachylaima sp., Echinostoma hortense, Echinostoma cinetorchis, and unidentified echinostome larvae were found in the small intestines of 35 (14.8%), 12 (5.1%), 6 (2.5%), 1 (0.4%), and 1 (0.4%) mice respectively. Two species of tapeworms, Hymenolepis nana and Hymenolepis diminuta were also detected in 79 (33.5%) and 21 (8.9%) mice, respectively. Conclusively, heligmosomoid nematodes were the most prevalent (dominant) species among more than 11 helminth species detected, and Brachylaima sp. fluke is newly added in the list of intestinal trematodes in Korea. PMID:25246721

  19. Root-Derived Short-Chain Suberin Diacids from Rice and Rape Seed in a Paddy Soil under Rice Cultivar Treatments

    PubMed Central

    Ji, Haishi; Ding, Yuanjun; Liu, Xiaoyu; Li, Lianqing; Zhang, Dengxiao; Li, Zichuan; Sun, Jingling; Lashari, Muhammad Siddique; Joseph, Stephen; Meng, Yuanduo; Kuzyakov, Yakov; Pan, Genxing

    2015-01-01

    Suberin-derived substituted fatty acids have been shown to be potential biomarkers for plant-derived carbon (C) in soils across ecosystems. Analyzing root derived suberin compounds bound in soil could help to understand the root input into a soil organic carbon pool. In this study, bound lipids were extracted and identified in root and topsoil samples. Short-chain suberin diacids were quantified under rice (Oryza sativa L.) and rape (Brassica campestris) rotations with different cultivar combinations in a Chinese rice paddy. After removal of free lipids with sequential extraction, the residual bound lipids were obtained with saponification and derivatization before analysis using gas chromatography–mass spectrometry (GC-MS). Diacids C16 and C18 in bound lipids were detected both in rice and rape root samples, while diacids C20 and C22 were detected only in rape root samples. Accordingly, diacids were quantified in both rhizosphere and bulk soil (0–15 cm). The amount of total root-derived diacids in bulk soil varied in a range of 5.6–9.6 mg/kg across growth stages and crop seasons. After one year-round rice-rape rotation, root-derived suberin diacids were maintained at a level of 7–9 mg/kg in bulk soil; this was higher under a super rice cultivar LY than under a hybrid cultivar IIY. While concentrations of the analyzed diacids were generally higher in rhizosphere than in bulk soil, the total diacid (DA) concentration was higher at the time of rape harvest than at rice harvest, suggesting that rape roots made a major contribution to the preservation of diacids in the paddy. Moreover, the net change in the concentration and the ratios of C16:0 DA to C18:1 DA, and of C16:0 DA to C18:0 DA, over a whole growing season, were greater under LY than under IIY, though there was no difference between cultivars within a single growth stage. Overall, total concentration of root-derived suberin diacids was found to be positively correlated to soil organic carbon concentration both for bulk soil and rhizosphere. However, the turnover and preservation of the root suberin biomolecules with soil property and field conditions deserve further field studies. PMID:25961557

  20. Root-Derived Short-Chain Suberin Diacids from Rice and Rape Seed in a Paddy Soil under Rice Cultivar Treatments.

    PubMed

    Ji, Haishi; Ding, Yuanjun; Liu, Xiaoyu; Li, Lianqing; Zhang, Dengxiao; Li, Zichuan; Sun, Jingling; Lashari, Muhammad Siddique; Joseph, Stephen; Meng, Yuanduo; Kuzyakov, Yakov; Pan, Genxing

    2015-01-01

    Suberin-derived substituted fatty acids have been shown to be potential biomarkers for plant-derived carbon (C) in soils across ecosystems. Analyzing root derived suberin compounds bound in soil could help to understand the root input into a soil organic carbon pool. In this study, bound lipids were extracted and identified in root and topsoil samples. Short-chain suberin diacids were quantified under rice (Oryza sativa L.) and rape (Brassica campestris) rotations with different cultivar combinations in a Chinese rice paddy. After removal of free lipids with sequential extraction, the residual bound lipids were obtained with saponification and derivatization before analysis using gas chromatography-mass spectrometry (GC-MS). Diacids C16 and C18 in bound lipids were detected both in rice and rape root samples, while diacids C20 and C22 were detected only in rape root samples. Accordingly, diacids were quantified in both rhizosphere and bulk soil (0-15 cm). The amount of total root-derived diacids in bulk soil varied in a range of 5.6-9.6 mg/kg across growth stages and crop seasons. After one year-round rice-rape rotation, root-derived suberin diacids were maintained at a level of 7-9 mg/kg in bulk soil; this was higher under a super rice cultivar LY than under a hybrid cultivar IIY. While concentrations of the analyzed diacids were generally higher in rhizosphere than in bulk soil, the total diacid (DA) concentration was higher at the time of rape harvest than at rice harvest, suggesting that rape roots made a major contribution to the preservation of diacids in the paddy. Moreover, the net change in the concentration and the ratios of C16:0 DA to C18:1 DA, and of C16:0 DA to C18:0 DA, over a whole growing season, were greater under LY than under IIY, though there was no difference between cultivars within a single growth stage. Overall, total concentration of root-derived suberin diacids was found to be positively correlated to soil organic carbon concentration both for bulk soil and rhizosphere. However, the turnover and preservation of the root suberin biomolecules with soil property and field conditions deserve further field studies. PMID:25961557

  1. Regional and reservoir-scale analysis of fault systems and structural development of Pagerungan Gas Field, East Java Sea, Indonesia

    SciTech Connect

    Davies, R.K.; Medwedeff, D.A. [Arco Exploration and Production Technology, Plano, TX (United States)

    1996-12-31

    Pagerungan gas field lies on a complexly faulted and folded anticline just north of the major Sakala-Paliat Fault System (SPFS) offshore Bali. The Eocene clastic reservoir is affected by two generations of faults: Eocene normal and Neogene compressional faults. Fault geometry, timing and connectivity is determined by combining regional and field-scale methods. Restored regional structure maps and sections indicate the field is located on the L. Eocene, footwall-paleo-high of the south-dipping SPFS. Within the field, smaller normal faults nucleated sub-parallel to the SPFS with both synthetic and antithetic dips. Neogene to Present compression folded the strata creating closure in the field, reversed slip on selected preexisting normal faults, and nucleated new reverse fault sets. Some normal faults are completely inverted, others have net normal offset after some reverse slip, and still others are not reactivated. Reverse faults strike sub-parallel to earlier formed normal faults. The eastern and western parts of the field are distinguished by the style and magnitude of early compressional deformation. 3D seismic analysis indicates the geometry of reservoir faults is similar to the regional fault systems: sub-parallel segments share displacement at their terminations either by distributed deformation in the rock between adjacent terminations or through short cross-faults oriented at a high angle to the principal fault sets. Anomalous trends in the contours of throw projected onto fault surfaces predict the connectivity of complex fault patterns. Integration of regional and field-scale analysis provides the most accurate prediction of fault geometry and lays the foundation for field development.

  2. Regional and reservoir-scale analysis of fault systems and structural development of Pagerungan Gas Field, East Java Sea, Indonesia

    SciTech Connect

    Davies, R.K.; Medwedeff, D.A. (Arco Exploration and Production Technology, Plano, TX (United States))

    1996-01-01

    Pagerungan gas field lies on a complexly faulted and folded anticline just north of the major Sakala-Paliat Fault System (SPFS) offshore Bali. The Eocene clastic reservoir is affected by two generations of faults: Eocene normal and Neogene compressional faults. Fault geometry, timing and connectivity is determined by combining regional and field-scale methods. Restored regional structure maps and sections indicate the field is located on the L. Eocene, footwall-paleo-high of the south-dipping SPFS. Within the field, smaller normal faults nucleated sub-parallel to the SPFS with both synthetic and antithetic dips. Neogene to Present compression folded the strata creating closure in the field, reversed slip on selected preexisting normal faults, and nucleated new reverse fault sets. Some normal faults are completely inverted, others have net normal offset after some reverse slip, and still others are not reactivated. Reverse faults strike sub-parallel to earlier formed normal faults. The eastern and western parts of the field are distinguished by the style and magnitude of early compressional deformation. 3D seismic analysis indicates the geometry of reservoir faults is similar to the regional fault systems: sub-parallel segments share displacement at their terminations either by distributed deformation in the rock between adjacent terminations or through short cross-faults oriented at a high angle to the principal fault sets. Anomalous trends in the contours of throw projected onto fault surfaces predict the connectivity of complex fault patterns. Integration of regional and field-scale analysis provides the most accurate prediction of fault geometry and lays the foundation for field development.

  3. Initial results on the correlation between the magnetic and electric fields observed from the DE-2 satellite in the field-aligned current regions

    NASA Technical Reports Server (NTRS)

    Sugiura, M.; Maynard, N. C.; Farthing, W. H.; Heppner, J. P.; Ledley, B. G.; Cahill, L. J., Jr.

    1982-01-01

    Initial results of the electric and magnetic field observations from the DE-2 satellite show a remarkably good correlation between the north-south component of the electric field and the east-west component of the magnetic field in many passes of the field-aligned current regions. For a dayside cusp pass on August 15, 1981 the coefficient of correlation between these components was 0.996. A preliminary inspection of the available data from the first 6 months of the DE operation indicates that the similarity between the electric and magnetic field signatures of the field-aligned currents is a commonly observed feature at all local times. This high correlation is interpreted to be an indication that the closure of the field-aligned current is essentially meridional. When the correlation between these components is not good, the closure current is likely to be flowing along the auroral belt. When the correlation between the electric and magnetic fields is high, it is possible to estimate the height-integrated Pedersen conductivity from the observed field components.

  4. New Features of Time Domain Electric-Field Structures in the Auroral Acceleration Region

    Microsoft Academic Search

    F. S. Mozer; R. Ergun; M. Temerin; C. Cattell; J. Dombeck; J. Wygant

    1997-01-01

    The Polar Satellite carries the first three-axis electric field detector flown in the magnetosphere. Its direct measurement of electric field components perpendicular and parallel to the local magnetic field has revealed new classes and features of electric field structures associated with the plasma acceleration that produces discrete auroras and that populates the magnetosphere with plasma of ionospheric origin. These structures,

  5. Arsenic binding to iron(II) minerals produced by an iron(III)-reducing Aeromonas strain isolated from paddy soil.

    PubMed

    Wang, Xin-Jun; Chen, Xue-Ping; Kappler, Andreas; Sun, Guo-Xin; Zhu, Yong-Guan

    2009-11-01

    An iron reducing bacterial strain was isolated from a paddy soil and identified as a member of the Aeromonas group by 16S rRNA gene sequence analysis. When the cells were growing with dissolved Fe(III) as electron acceptor in the presence of As(V), Fe(II) minerals (siderite and vivianite) were formed and dissolved As was removed efficiently from solution. When the cells were growing with the Fe(III) hydroxide mineral (ferrihydrite) as electron acceptor in the presence of As(V), ferrihydrite was reduced and dissolved As(V) concentrations decreased sharply. Our results demonstrated firstly that members of the Aeromonas group can reduce Fe(III) in paddy soils, and secondly that iron reduction does not necessarily lead to arsenic mobilization. However, As immobilization can occur in environments that contain significant concentrations of counter ions such as bicarbonate and phosphate. PMID:19572768

  6. Calibration of Daycent biogeochemical model for rice paddies in three agro-ecological zones in Peninsular India to optimize cropping practices and predict GHG emissions

    NASA Astrophysics Data System (ADS)

    Rajan, S.; Kritee, K.; Keough, C.; Parton, W. J.; Ogle, S. M.

    2014-12-01

    Rice is a staple for nearly half of the world population with irrigated and rainfed lowland rice accounting for about 80% of the worldwide harvested rice area. Increased atmospheric CO2 and rising temperatures are expected to adversely affect rice yields by the end of the 21st century. In addition, different crop management practices affect methane and nitrous oxide emissions from rice paddies antagonistically warranting a review of crop management practices such that farmers can adapt to the changing climate and also help mitigate climate change. The Daily DayCent is a biogeochemical model that operates on a daily time step, driven by four ecological drivers, i.e. climate, soil, vegetation, and management practices. The model is widely used to simulate daily fluxes of various gases, plant productivity, nutrient availability, and other ecosystem parameters in response to changes in land management and climate. We employed the DayCent model as a tool to optimize rice cropping practices in Peninsular India so as to develop a set of farming recommendations to ensure a triple win (i.e. higher yield, higher profit and lower GHG emissions). We applied the model to simulate both N2O and CH4 emissions, and crop yields from four rice paddies in three different agro-ecological zones under different management practices, and compared them with measured GHG and yield data from these plots. We found that, like all process based models, the biggest constraint in using the model was input data acquisition. Lack of accurate documentation of historic land use and management practices, missing historical daily weather data, and difficulty in obtaining digital records of soil and crop/vegetation parameters related to our experimental plots came in the way of our execution of this model. We will discuss utilization of estimates based on available literature, or knowledge-based values in lieu of missing measured parameters in our simulations with DayCent which could prove to be a solution to overcome data limitations in modeling with DayCent and other process based models for developing regions of the world.

  7. Breast Cancer Regional Radiation Fields for Supraclavicular and Axillary Lymph Node Treatment: Is a Posterior Axillary Boost Field Technique Optimal?

    SciTech Connect

    Wang Xiaochun [Department of Radiation Physics, University of Texas, M. D. Anderson Cancer Center, Houston, TX (United States)], E-mail: xiaochunw@mdanderson.org; Yu, T.K. [Department of Radiation Oncology, University of Texas, M. D. Anderson Cancer Center, Houston, TX (United States); Salehpour, Mohammad; Zhang, Sean X.; Sun, T.L. [Department of Radiation Physics, University of Texas, M. D. Anderson Cancer Center, Houston, TX (United States); Buchholz, Thomas A. [Department of Radiation Oncology, University of Texas, M. D. Anderson Cancer Center, Houston, TX (United States)

    2009-05-01

    Purpose: To assess whether using an anterior oblique supraclavicular (SCV) field with a posterior axillary boost (PAB) field is an optimal technique for targeting axillary (AX) lymph nodes compared with two computed tomography (CT)-based techniques: (1) an SCV field with an anterior boost field and (2) intensity-modulated radiotherapy (IMRT). Methods and Materials: Ten patients with CT simulation data treated with postmastectomy radiation that included an SCV field were selected for the study. Supraclavicular nodes and AX Level I-III nodes within the SCV field were contoured and defined as the treatment target. Plans using the three techniques were generated and evaluated for each patient. Results: The anterior axillary boost field and IMRT resulted in superior dose coverage compared with PAB. Namely, treatment volumes that received 105%, 80%, and 30% of prescribed dose for IMRT plans were significantly less than those for the anterior axillary boost plans, which were significantly less than PAB. For PAB and anterior axillary boost plans, there was a linear correlation between treatment volume receiving 105% of prescribed dose and maximum target depth. Furthermore, the IMRT technique resulted in better lung sparing and dose conformity to the target than anterior axillary boost, which again was significantly better than PAB. The maximum cord dose for IMRT was small, but higher than for the other two techniques. More monitor units were required to deliver the IMRT plan than the PAB plan, which was more than the anterior axillary boost plan. Conclusions: The PAB technique is not optimal for treatment of AX lymph nodes in an SCV field. We conclude that CT treatment planning with dose optimization around delineated target volumes should become standard for radiation treatments of supraclavicular and AX lymph nodes.

  8. Abundance and diversity of nitrogen-fixing bacteria in rhizosphere and bulk paddy soil under different duration of organic management

    Microsoft Academic Search

    Wang Shu; Gonzalez Perez Pablo; Ye Jun; Huang Danfeng

    Denaturing gradient gel electrophoresis (DGGE) and quantitative real-time PCR (qPCR) approaches were used to assess respectively\\u000a the molecular diversity and quantity of the nifH gene sequences in rhizosphere and bulk paddy soil under conventional management and different duration of organic management\\u000a (2, 3, 5, 9 years). The phylogenetic distribution of clones based on nifH gene sequence showed that taxonomic groups were

  9. Global distribution of natural freshwater wetlands and rice paddies, their net primary productivity, seasonality and possible methane emissions

    Microsoft Academic Search

    I. Aselmann; P. J. Crutzen

    1989-01-01

    A global data set on the geographic distribution and seasonality of freshwater wetlands and rice paddies has been compiled, comprising information at a spatial resolution of 2.5° by latitude and 5° by longitude. Global coverage of these wetlands total 5.7×106 km2 and 1.3×106 km2, respectively. Natural wetlands have been grouped into six categories following common terminology, i.e. bog, fen, swamp,

  10. Abundance, composition and activity of ammonia oxidizer and denitrifier communities in metal polluted rice paddies from South China.

    PubMed

    Liu, Yuan; Liu, Yongzhuo; Ding, Yuanjun; Zheng, Jinwei; Zhou, Tong; Pan, Genxing; Crowley, David; Li, Lianqing; Zheng, Jufeng; Zhang, Xuhui; Yu, Xinyan; Wang, Jiafang

    2014-01-01

    While microbial nitrogen transformations in soils had been known to be affected by heavy metal pollution, changes in abundance and community structure of the mediating microbial populations had been not yet well characterized in polluted rice soils. Here, by using the prevailing molecular fingerprinting and enzyme activity assays and comparisons to adjacent non-polluted soils, we examined changes in the abundance and activity of ammonia oxidizing and denitrifying communities of rice paddies in two sites with different metal accumulation situation under long-term pollution from metal mining and smelter activities. Potential nitrifying activity was significantly reduced in polluted paddies in both sites while potential denitrifying activity reduced only in the soils with high Cu accumulation up to 1300 mg kg-1. Copy numbers of amoA (AOA and AOB genes) were lower in both polluted paddies, following the trend with the enzyme assays, whereas that of nirK was not significantly affected. Analysis of the DGGE profiles revealed a shift in the community structure of AOA, and to a lesser extent, differences in the community structure of AOB and denitrifier between soils from the two sites with different pollution intensity and metal composition. All of the retrieved AOB sequences belonged to the genus Nitrosospira, among which species Cluster 4 appeared more sensitive to metal pollution. In contrast, nirK genes were widely distributed among different bacterial genera that were represented differentially between the polluted and unpolluted paddies. This could suggest either a possible non-specific target of the primers conventionally used in soil study or complex interactions between soil properties and metal contents on the observed community and activity changes, and thus on the N transformation in the polluted rice soils. PMID:25058658

  11. Draft Genome Sequence of Geobacter sp. Strain OR-1, an Arsenate-Respiring Bacterium Isolated from Japanese Paddy Soil

    PubMed Central

    Ehara, Ayaka; Suzuki, Haruo

    2015-01-01

    Here, we report a draft genome sequence of Geobacter sp. strain OR-1, an arsenate-respiring bacterium isolated from Japanese paddy soil. It contained two distinct arsenic islands, one including genes for a respiratory arsenate reductase (Arr) as well as for arsenic resistance (arsD-arsA-acr3-arsR-arrA-arrB) and the second containing only genes for arsenic resistance. PMID:25635012

  12. Variations in the microalgal structure in paddy soil in Osaka, Japan: comparison between surface and subsurface soils

    Microsoft Academic Search

    Yuko Fujita; Hiroyuki Nakahara

    2006-01-01

    Seasonal variations in microalgal communities were compared between surface and subsurface paddy soils in Osaka, Japan. Soil\\u000a samples were collected from depths of 0–1 (surface), 8–9, and 17–18 cm. Diatom cells were counted directly, and the numbers\\u000a of other microalgae were estimated using a culture method. The microalgal community as well as the soil properties changed\\u000a drastically in the surface

  13. Phylogenetic Diversity of Lactic Acid Bacteria Associated with Paddy Rice Silage as Determined by 16S Ribosomal DNA Analysis

    Microsoft Academic Search

    Saïd Ennahar; Yimin Cai; Yasuhito Fujita

    2003-01-01

    A total of 161 low-GC-content gram-positive bacteria isolated from whole-crop paddy rice silage were classified and subjected to phenotypic and genetic analyses. Based on morphological and biochemical char- acters, these presumptive lactic acid bacterium (LAB) isolates were divided into 10 groups that included members of the genera Enterococcus, Lactobacillus, Lactococcus, Leuconostoc, Pediococcus, and Weissella. Analysis of the 16S ribosomal DNA

  14. Integral Field Spectroscopy of the Extended Emission-Line Region of 4C 37.43

    NASA Astrophysics Data System (ADS)

    Fu, Hai; Stockton, Alan

    2007-09-01

    We present Gemini integral field spectroscopy and Keck II long-slit spectroscopy of the extended emission-line region (EELR) around the quasar 4C 37.43. The velocity structure of the ionized gas is complex and cannot be explained globally by a simple dynamical model. The spectra from the clouds are inconsistent with shock or ``shock + precursor'' ionization models, but they are consistent with photoionization by the quasar nucleus. The best-fit photoionization model requires a low-metallicity [12+log(O/H)<~8.7] two-phase medium, consisting of a matter-bounded diffuse component with a unity filling factor (N~1 cm-3, T~15,000 K), in which are embedded small, dense clouds (N~400 cm-3, T~104 K). The high-density clouds are transient and can be regenerated through compressing the diffuse medium by low-speed shocks (VS<~100 km s-1). Our photoionization model gives a total mass for the ionized gas of about 3×1010 Msolar, and the total kinetic energy implied by this mass and the observed velocity field is ~2×1058 erg. The fact that luminous EELRs are confined to steep-spectrum radio-loud QSOs, yet show no morphological correspondence to the radio jets, suggests that the driving force producing the 4C 37.43 EELR was a roughly spherical blast wave initiated by the production of the jet. That such a mechanism seems capable of ejecting a mass comparable to that of the total interstellar medium of the Milky Way suggests that ``quasar-mode'' feedback may indeed be an efficient means of regulating star formation in the early universe. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Particle Physics and Astronomy Research Council (United Kingdom), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), CNPq (Brazil), and CONICET (Argentina). Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the financial support of the W. M. Keck Foundation.

  15. Horizontal structure of the electric field in the stratiform region of an Oklahoma mesoscale convective system

    NASA Astrophysics Data System (ADS)

    Mo, Qixu; Detwiler, Andrew G.; Hallett, John; Black, Robert

    2003-04-01

    This analysis combines vertical electric field components Ez observed by two research aircraft flying horizontally at two levels, with vertical soundings of thermodynamic parameters and Ez made by five balloons, to produce a quasi-three-dimensional view of the space charge distribution in the trailing stratiform cloud region behind a mesoscale convective system (MCS) that developed in central Oklahoma late in the afternoon of 2 June 1991. The balloons were launched serially at one-hour intervals from two sites separated by 80 km along a north-south line as the MCS moved eastward, yielding two east-west time-height cross-sections of the Ez structure within the quasi-steady state trailing stratiform region behind the MCS. The balloon measurements are consistent with a vertical stack of five rearward- and downward-sloping horizontal sheets of charge of alternating polarity, beginning at the bottom with a negative charge layer below the 0°C level and a positive layer near the 0°C level. This structure persisted for more than 2 hours. The two aircraft flew back and forth along a north-south line through the balloon launch sites during the balloon launch period. Aircraft measurements demonstrated that the vertical electric field (Ez) at constant altitude varied in the north-south direction. The peak magnitudes of Ez deduced from the airborne instrument systems agreed with the magnitudes deduced from the balloon measurements at the aircraft altitudes of 4.5 km and 5.8 km AGL. Rapid reversals in polarity of Ez with peak magnitude >50 kV m-1 observed by the aircraft at 4.5 km, just above the 0°C level, confirms the thin concentrated positive charge layer observed there by balloons and suggests that this charge layer is undulating above and below 4.5 km altitude, at least in the north-south direction. Microphysically, this layer contained large aggregates and pockets of low cloud liquid water concentration. At the 5.8 km level, the polarity of Ez was always positive but the magnitude varied from zero to 25 kV m-1. Aircraft-observed Ez at both altitudes varied on horizontal scales of ˜10 km or greater at both levels, suggesting that the charge density derived using the one-dimensional infinite-layer Gauss's law approximation applied to the balloon soundings of Ez is valid in this study. These observations show that layers of charge can persist for hours as they advect rearward in a storm-relative sense, possibly due to continuing in situ charge separation, and/or due to weak dispersion, slow recombination and slow settling of charge attached to low mobility low terminal velocity ice hydrometeors.

  16. Accurate calculation of magnetic fields in the end regions of superconducting accelerator magnets using the BEM-FEM coupling method

    Microsoft Academic Search

    S. Kurz; Stephan Russenschuck

    1999-01-01

    In this paper a new technique for the accurate calculation of magnetic fields in the end regions of superconducting accelerator magnets is presented. This method couples boundary elements (BEM) which discretize the surface of the iron yoke and finite elements (FEM) for the modelling of the nonlinear interior of the yoke. The BEM-FEM method is therefore specially suited for the

  17. Solar Flux and Solar Wind Dependence of Dayside Photoelectron Fluxes in the Mars Strong Crustal Field Region

    Microsoft Academic Search

    M. W. Liemohn; J. Frank; D. L. Mitchell

    2004-01-01

    Observed characteristics of photoelectrons in the dayside ionosphere of Mars are examined. During the mapping and extended phases of its mission, the Mars Global Surveyor satellite routinely passes over the region of intense crustal magnetic fields in the southern hemisphere of Mars. When this occurs on the dayside (2 p.m. local time), the magnetometer and electron reflectometer instrument usually measures

  18. LYMAN Field Area Paper, June 2007 Page 1 of 53 Travel Time Reliability in Regional Transportation Planning

    E-print Network

    Bertini, Robert L.

    LYMAN Field Area Paper, June 2007 Page 1 of 53 Travel Time Reliability in Regional Transportation Abstract Travel time reliability is an important measure of congestion and can serve as baseline of travel time reliability and its value as a congestion measure. It then presents the methodology

  19. Formation and Eruption of an Active Region Sigmoid. I. A Study by Nonlinear Force-free Field Modeling

    NASA Astrophysics Data System (ADS)

    Jiang, Chaowei; Wu, S. T.; Feng, Xueshang; Hu, Qiang

    2014-01-01

    We present a comprehensive study of the formation and eruption of an active region (AR) sigmoid in AR 11283. To follow the quasi-static evolution of the coronal magnetic field, we reconstruct a time sequence of static fields using a recently developed nonlinear force-free field model constrained by vector magnetograms. A detailed analysis of the fields compared with observations suggests the following scenario for the evolution of the region. Initially, a new bipole emerges into the negative polarity of a preexisting bipolar AR, forming a null-point topology between the two flux systems. A weakly twisted flux rope (FR) is then built up slowly in the embedded core region, largely through flux cancellation, forming a bald patch separatrix surface (BPSS). The FR grows gradually until its axis runs into a torus instability (TI) domain, and the BPSS also develops a full S-shape. The combined effects of the TI-driven expansion of the FR and the line tying at the BP tear the FR into two parts with the upper portion freely expelled and the lower portion remaining behind the postflare arcades. This process dynamically perturbs the BPSS and results in the enhanced heating of the sigmoid and the rope. The accelerated expansion of the upper-portion rope strongly pushes its envelope flux near the null point and triggers breakout reconnection at the null, which further drives the eruption. We discuss the important implications of these results for the formation and disruption of the sigmoid region with an FR.

  20. A new GLM-based method for mapping tree cover continuous fields using regional MODIS reflectance data

    Microsoft Academic Search

    Markus Schwarz; Niklaus E. Zimmermann

    2005-01-01

    Knowledge about land cover and its change is an important input for the monitoring and modeling of ecological and environmental processes from the regional to the global scale. Considerable efforts have been made to develop global continuous fields for different land cover types at large spatial scales based on NOAA-AVHRR and TERRA-MODIS data and a range of techniques have been

  1. Formation and eruption of an active region sigmoid. I. A study by nonlinear force-free field modeling

    SciTech Connect

    Jiang, Chaowei; Feng, Xueshang [SIGMA Weather Group, State Key Laboratory for Space Weather, Center for Space Science and Applied Research, Chinese Academy of Sciences, Beijing 100190 (China); Wu, S. T.; Hu, Qiang, E-mail: cwjiang@spaceweather.ac.cn, E-mail: fengx@spaceweather.ac.cn, E-mail: wus@uah.edu, E-mail: qh0001@uah.edu [Center for Space Plasma and Aeronomic Research, The University of Alabama in Huntsville, Huntsville, AL 35899 (United States)

    2014-01-01

    We present a comprehensive study of the formation and eruption of an active region (AR) sigmoid in AR 11283. To follow the quasi-static evolution of the coronal magnetic field, we reconstruct a time sequence of static fields using a recently developed nonlinear force-free field model constrained by vector magnetograms. A detailed analysis of the fields compared with observations suggests the following scenario for the evolution of the region. Initially, a new bipole emerges into the negative polarity of a preexisting bipolar AR, forming a null-point topology between the two flux systems. A weakly twisted flux rope (FR) is then built up slowly in the embedded core region, largely through flux cancellation, forming a bald patch separatrix surface (BPSS). The FR grows gradually until its axis runs into a torus instability (TI) domain, and the BPSS also develops a full S-shape. The combined effects of the TI-driven expansion of the FR and the line tying at the BP tear the FR into two parts with the upper portion freely expelled and the lower portion remaining behind the postflare arcades. This process dynamically perturbs the BPSS and results in the enhanced heating of the sigmoid and the rope. The accelerated expansion of the upper-portion rope strongly pushes its envelope flux near the null point and triggers breakout reconnection at the null, which further drives the eruption. We discuss the important implications of these results for the formation and disruption of the sigmoid region with an FR.

  2. INTERMITTENCY AND MULTIFRACTALITY SPECTRA OF THE MAGNETIC FIELD IN SOLAR ACTIVE REGIONS

    SciTech Connect

    Abramenko, Valentyna; Yurchyshyn, Vasyl [Big Bear Solar Observatory, 40386 North Shore Lane, Big Bear City, CA 92314 (United States)

    2010-10-10

    We present the results of a study of intermittency and multifractality of magnetic structures in solar active regions (ARs). Line-of-sight magnetograms for 214 ARs of different flare productivity observed at the center of the solar disk from 1997 January until 2006 December are utilized. Data from the Michelson Doppler Imager (MDI) instrument on board the Solar and Heliospheric Observatory operating in the high resolution mode, the Big Bear Solar Observatory digital magnetograph, and the Hinode SOT/SP instrument were used. Intermittency spectra were derived from high-order structure functions and flatness functions. The flatness function exponent is a measure of the degree of intermittency. We found that the flatness function exponent at scales below approximately 10 Mm is correlated with flare productivity (the correlation coefficient is -0.63). The Hinode data show that the intermittency regime is extended toward small scales (below 2 Mm) as compared to the MDI data. The spectra of multifractality, derived from the structure functions and flatness functions, are found to be broader for ARs of higher flare productivity as compared to those of low flare productivity. The magnetic structure of high-flaring ARs consists of a voluminous set of monofractals, and this set is much richer than that for low-flaring ARs. The results indicate the relevance of the multifractal organization of the photospheric magnetic fields to the flaring activity. The strong intermittency observed in complex and high-flaring ARs is a hint that we observe a photospheric imprint of enhanced sub-photospheric dynamics.

  3. [Soil arsenic content and its health risk assessment for agricultural products in the region surrounding Shimen arsenic sulphide mine].

    PubMed

    Li, Lian-fang; Zeng, Xi-bai; Bai, Ling-yu; Li, Shu-hui

    2010-11-01

    A systematic investigation was carried out on the arsenic content in the soils and plants surrounding Shimen arsenic sulphide mine. The arsenic content in top soils (0-20 cm) was averagely 99.51 mg x kg(-1), being 5.34 times higher than that of the background value in Hunan Province and 8.70 times higher than that of local farmland soil. The topsoil arsenic content in paddy field and dry land was 43.51 and 115.1 mg x kg(-1), respectively, being 0.45 and 1.87 times higher than that of the grade II level (paddy field 30 mg x kg(-1); dry land 40 mg x kg(-1)) commended by the National Soil Quality (GB 15618-1995), and the corresponding arsenic exceeding rate was 62.5% and 50.0%, respectively. The arsenic content in edible parts of foodstuff, vegetables, and fruits was 0.16, 0.06, and 0.01 mg x kg(-1), respectively, and the arsenic exceeding rate of crop samples compared to food security standard ranked in the order of foodstuff > vegetables > fruits. Rice and sweet potato were relatively seriously contaminated by arsenic. The highest arsenic content of rice was up to 0.84 mg x kg(-1), which was 4.6 times higher than that of the National Standard, with the exceeding rate of 62.5%. Statistical analysis demonstrated that there was a positive correlation between the arsenic contents of soil and plant. The average daily intake of arsenic by local people through the consumption of the crops was 6.416 microg x kg(-1) x d(-1), which was much higher than the standard commended by WHO, and the related health risk index was 21.39, which was 14.39 times higher than that in the control region. PMID:21361022

  4. Diversity of aerobic anoxygenic phototrophic bacteria in paddy soil and their response to elevated atmospheric CO2

    PubMed Central

    Feng, Youzhi; Lin, Xiangui; Mao, Tingting; Zhu, Jianguo

    2011-01-01

    Summary Aerobic anoxygenic phototrophic bacteria (AAnPB) are recognized as an important group driving the global carbon cycling. However, the diversity of AAnPB in terrestrial environment remains largely unknown as well as their responses to the elevated atmospheric CO2. By using culture?independent techniques, the diversity of AAnPB in paddy soil and the changes in response to the rising atmospheric CO2 were investigated within China FACE (Free?air CO2 enrichment) platform. There was a phylogenetically diverse AAnPB community with large population size residing in paddy soil. The community structure of AAnPB in bulk and rhizospheric soils stayed almost identical, while the population size was higher in rhizospheric [2.0–2.5?×?108 copy number of pufM genes g?1 dry weight soil (d.w.s.)] than that in bulk (0.7–0.8?×?108?g?1?d.w.s.) soils. Elevated atmospheric CO2 appeared to significantly stimulate AAnPB abundance (up to 1.4–1.5?×?108?g?1?d.w.s.) and result in a higher AAnPB percentage in total bacterial community (from 0.5% up to 1.5%) in bulk soil, whereas no significant effect was observed in rhizospheric soil. Our results would extend the functional ecotypes of AAnPB and indicate that environmental changes associated with the rising atmospheric CO2 might affect AAnPB community in paddy soil. PMID:21255374

  5. Phyllosphere Bacterial Community of Floating Macrophytes in Paddy Soil Environments as Revealed by Illumina High-Throughput Sequencing

    PubMed Central

    Xie, Wan-Ying

    2014-01-01

    The phyllosphere of floating macrophytes in paddy soil ecosystems, a unique habitat, may support large microbial communities but remains largely unknown. We took Wolffia australiana as a representative floating plant and investigated its phyllosphere bacterial community and the underlying driving forces of community modulation in paddy soil ecosystems using Illumina HiSeq 2000 platform-based 16S rRNA gene sequence analysis. The results showed that the phyllosphere of W. australiana harbored considerably rich communities of bacteria, with Proteobacteria and Bacteroidetes as the predominant phyla. The core microbiome in the phyllosphere contained genera such as Acidovorax, Asticcacaulis, Methylibium, and Methylophilus. Complexity of the phyllosphere bacterial communities in terms of class number and ?-diversity was reduced compared to those in corresponding water and soil. Furthermore, the bacterial communities exhibited structures significantly different from those in water and soil. These findings and the following redundancy analysis (RDA) suggest that species sorting played an important role in the recruitment of bacterial species in the phyllosphere. The compositional structures of the phyllosphere bacterial communities were modulated predominantly by water physicochemical properties, while the initial soil bacterial communities had limited impact. Taken together, the findings from this study reveal the diversity and uniqueness of the phyllosphere bacterial communities associated with the floating macrophytes in paddy soil environments. PMID:25362067

  6. Multi-year monitoring of paddy rice planting area in Northeast China using MODIS time series data.

    PubMed

    Shi, Jing-jing; Huang, Jing-feng; Zhang, Feng

    2013-10-01

    The objective of this study was to investigate the tempo-spatial distribution of paddy rice in Northeast China using moderate resolution imaging spectroradiometer (MODIS) data. We developed an algorithm for detection and estimation of the transplanting and flooding periods of paddy rice with a combination of enhanced vegetation index (EVI) and land surface water index with a central wavelength at 2130 nm (LSWI2130). In two intensive sites in Northeast China, fine resolution satellite imagery was used to validate the performance of the algorithm at pixel and 3×3 pixel window levels, respectively. The commission and omission errors in both of the intensive sites were approximately less than 20%. Based on the algorithm, annual distribution of paddy rice in Northeast China from 2001 to 2009 was mapped and analyzed. The results demonstrated that the MODIS-derived area was highly correlated with published agricultural statistical data with a coefficient of determination (R(2)) value of 0.847. It also revealed a sharp decline in 2003, especially in the Sanjiang Plain located in the northeast of Heilongjiang Province, due to the oversupply and price decline of rice in 2002. These results suggest that the approaches are available for accurate and reliable monitoring of rice cultivated areas and variation on a large scale. PMID:24101210

  7. Arsenic in rice (Oryza sativa L.) related to dynamics of arsenic and silicic acid in paddy soils.

    PubMed

    Bogdan, Katja; Schenk, Manfred K

    2008-11-01

    Paddy rice is a global staple food which in some circumstances can contain high levels of the toxic element arsenic (As). In order to elucidate factors influencing As dissolution in the soil solution during paddy rice cultivation, rice (Oryza sativa L. "Selenio") was cultivated to maturity in six paddy soils in the greenhouse in 2005 and 2006. Concentrations of Mn, Fe, As, P, and silicic acid in soil solution and As concentrations in rice straw and polished rice grain were determined. There was a close relationship between Fe and As concentrations in the soil solution, suggesting that the major part of dissolved As originated from reduced iron-(hydr)oxide. However, in addition to the factors causing As dissolution in the soil, other factors influenced the uptake of As by rice. The inhibitory effect of indigenous silicic acid in the soil solution on As uptake was clearly shown. This implied that soils with high plant available Si contents resulted in low plant As contents and that Si application to soils may decrease the As content of rice. PMID:19031876

  8. Variability in responses of bacterial communities and nitrogen oxide emission to urea fertilization among various flooded paddy soils.

    PubMed

    Wang, Ning; Ding, Long-Jun; Xu, Hui-Juan; Li, Hong-Bo; Su, Jian-Qiang; Zhu, Yong-Guan

    2015-03-01

    Fertilization affects bacterial communities and element biogeochemical cycling in flooded paddy soils and the effect might differ among soil types. In this study, five paddy soils from Southern China were subjected to urea addition to explore impacts of fertilization on nitrogen oxide (N2O) emission and bacterial community composition under the flooding condition. 16S rRNA gene-based illumina sequencing showed no obvious shifts in bacterial community composition of five soils after urea addition. However, some genera were affected by fertilization addition and the influenced genera varied among soils. During the late period (day 8-19) of flooding incubation without urea addition, N2O emission rates were elevated for all soils. However, urea effects on N2O emission were different among flooded soils. For soils where nirS and nirK gene abundances increased with urea addition, N2O emission was significantly increased compared to control treatment. Redundancy analysis showed that dissolved organic carbon, ammonium (NH4 (+)), ferrous iron (Fe(2+)) and nitrate (NO3 (-)) in pore water explained 33.4% of the variation in soil bacterial community composition, implying that urea regimes influenced the relative abundance of some bacterial populations possibly by regulating soil characteristics and then influencing N2O emission. These results provided insights into soil type-dependent effect of fertilization on the overall bacterial communities and nitrogen oxide emission in flooded paddy soils. PMID:25764461

  9. Accurate Calculation of Magnetic Fields in the End Regions of Superconducting Accelerator Magnets using the BEM-FEM Coupling Method

    E-print Network

    Kurz, S

    1999-01-01

    In this paper a new technique for the accurate calculation of magnetic fields in the end regions of superconducting accelerator magnets is presented. This method couples Boundary Elements (BEM) which discretize the surface of the iron yoke and Finite Elements (FEM) for the modelling of the nonlinear interior of the yoke. The BEM-FEM method is therefore specially suited for the calculation of 3-dimensional effects in the magnets, as the coils and the air regions do not have to be represented in the finite-element mesh and discretization errors only influence the calculation of the magnetization (reduced field) of the yoke. The method has been recently implemented into the CERN-ROXIE program package for the design and optimization of the LHC magnets. The field shape and multipole errors in the two-in-one LHC dipoles with its coil ends sticking out of the common iron yoke is presented.

  10. Direct, spectroscopic measurement of electric fields in a plasma-RF antenna interaction region in Tore Supra

    SciTech Connect

    Klepper, C Christopher [ORNL] [ORNL; Hillis, Donald Lee [ORNL] [ORNL; Isler, Ralph C [ORNL] [ORNL; Hillairet, J. [French Atomic Energy Commission (CEA), Institute for Magnetic Fusion Research (IRFM)] [French Atomic Energy Commission (CEA), Institute for Magnetic Fusion Research (IRFM); Martin, E. H. [North Carolina State University] [North Carolina State University; Colas, L. [French Atomic Energy Commission (CEA), Cadarache, St. Paul lez Durance] [French Atomic Energy Commission (CEA), Cadarache, St. Paul lez Durance; Ekedahl, A. [French Atomic Energy Commission (CEA), Institute for Magnetic Fusion Research (IRFM)] [French Atomic Energy Commission (CEA), Institute for Magnetic Fusion Research (IRFM); Goniche, M. [French Atomic Energy Commission (CEA), Institute for Magnetic Fusion Research (IRFM)] [French Atomic Energy Commission (CEA), Institute for Magnetic Fusion Research (IRFM); Lotte, Ph. [French Atomic Energy Commission (CEA), Cadarache, St. Paul lez Durance] [French Atomic Energy Commission (CEA), Cadarache, St. Paul lez Durance; Colledani, G. [French Atomic Energy Commission (CEA), Institute for Magnetic Fusion Research (IRFM)] [French Atomic Energy Commission (CEA), Institute for Magnetic Fusion Research (IRFM); Martin, V. [French Atomic Energy Commission (CEA), Institute for Magnetic Fusion Research (IRFM)] [French Atomic Energy Commission (CEA), Institute for Magnetic Fusion Research (IRFM); Panayotis, Stephanie [French Atomic Energy Commission (CEA), Institute for Magnetic Fusion Research (IRFM)] [French Atomic Energy Commission (CEA), Institute for Magnetic Fusion Research (IRFM); Pegourie, B. [French Atomic Energy Commission (CEA), Cadarache, St. Paul lez Durance] [French Atomic Energy Commission (CEA), Cadarache, St. Paul lez Durance; Harris, Jeffrey H [ORNL] [ORNL

    2013-01-01

    Balmer-series spectral line profiles of deuterium emission near a lower-hybrid (3.7 GHz) wave, high power (1-4 MW) launcher were measured with high-spectral resolution in the Tore Supra tokamak and fitted to an atomic physics model which includes both Zeeman and dynamic Stark effects. The magnetic field is static and the electric field is assumed to be monochromatic at 3.7 GHz. The determined strength and direction of the high-frequency electric field is found to be in good agreement with the results of a simulation that computes the propagation of these lower hybrid waves into the plasma in the region around the launch antenna and specifically in the region of estimated peak emission contributing to the measurement. This agreement indicates feasibility for the use of dynamic Stark effect spectroscopy to study interaction at the plasma antenna interactions in a fusion plasma environment. (C) 2013 Elsevier B. V. All rights reserved.

  11. Transport behavior and rice uptake of radiostrontium and radiocesium in flooded paddy soils contaminated in two contrasting ways.

    PubMed

    Choi, Yong-Ho; Lim, Kwang-Muk; Jun, In; Keum, Dong-Kwon; Han, Moon-Hee; Kim, In-Gyu

    2011-12-15

    In order to investigate the transport behavior and rice uptake of radiostrontium and radiocesium in flooded rice fields, lysimeter experiments with two paddy soils were performed in a greenhouse. A solution containing (85)Sr and (137)Cs was applied in two different ways - being mixed with the top soil 27 d before transplanting or being dropped to the surface water 1d after transplanting. Rice uptake was quantified with two kinds of transfer factor - TF(m) (dimensionless) and TF(a) (m(2)kg(-1)-dry) for the pre- and post-transplanting depositions, respectively. For brown rice, the TF(m) values of (85)Sr and (137)Cs differed between the soils by factors of 2 (1.6×10(-2) and 2.5×10(-2)) and 7 (2.2×10(-2) and 1.5×10(-1)), respectively. Corresponding factors by the TF(a) values were 2 (2.5×10(-4) and 4.4×10(-4)) for (85)Sr and 3 (1.1×10(-3) and 2.9×10(-3)) for (137)Cs. Straws had several times higher TF(m) and TF(a) values of (85)Sr than of (137)Cs. The surface-water concentrations were substantially higher for the TF(a) than for the TF(m), indicating the possibility of a much higher plant-base uptake for the TF(a). In the TF(a) soils, (137)Cs and, to a lesser degree, (85)Sr were severely localized towards the soil surface, probably leading to an increased root uptake. The activity loss due to plant uptake and water percolation was generally inconsiderable. Time-dependent K(d) values of (85)Sr measured in a parallel experiment ranged from 20 to 170, whereas (137)Cs had much higher K(d) values. The use of TF(a) values instead of TF(m) values turned out to be a reasonable approach to the evaluation of a vegetation-period deposition. PMID:22071438

  12. Improved description of Earth’s external magnetic fields and their source regions using satellite data 

    E-print Network

    Shore, Robert Michael

    2013-11-28

    In near-Earth space, highly spatio-temporally variant magnetic fields result from solar-terrestrial magnetic interaction. These near-Earth external fields currently represent the largest source of error in efforts to ...

  13. B fields in OB stars (BOB): The discovery of a magnetic field in a multiple system in the Trifid nebula, one of the youngest star forming regions

    NASA Astrophysics Data System (ADS)

    Hubrig, S.; Fossati, L.; Carroll, T. A.; Castro, N.; González, J. F.; Ilyin, I.; Przybilla, N.; Schöller, M.; Oskinova, L. M.; Morel, T.; Langer, N.; Scholz, R. D.; Kharchenko, N. V.; Nieva, M.-F.

    2014-04-01

    Aims: Recent magnetic field surveys in O- and B-type stars revealed that about 10% of the core-hydrogen-burning massive stars host large-scale magnetic fields. The physical origin of these fields is highly debated. To identify and model the physical processes responsible for the generation of magnetic fields in massive stars, it is important to establish whether magnetic massive stars are found in very young star-forming regions or whether they are formed in close interacting binary systems. Methods: In the framework of our ESO Large Program, we carried out low-resolution spectropolarimetric observations with FORS 2 in 2013 April of the three most massive central stars in the Trifid nebula, HD 164492A, HD 164492C, and HD 164492D. These observations indicated a strong longitudinal magnetic field of about 500-600 G in the poorly studied component HD 164492C. To confirm this detection, we used HARPS in spectropolarimetric mode on two consecutive nights in 2013 June. Results: Our HARPS observations confirmed the longitudinal magnetic field in HD 164492C. Furthermore, the HARPS observations revealed that HD 164492C cannot be considered as a single star as it possesses one or two companions. The spectral appearance indicates that the primary is most likely of spectral type B1-B1.5 V. Since in both observing nights most spectral lines appear blended, it is currently unclear which components are magnetic. Long-term monitoring using high-resolution spectropolarimetry is necessary to separate the contribution of each component to the magnetic signal. Given the location of the system HD 164492C in one of the youngest star formation regions, this system can be considered as a Rosetta Stone for our understanding of the origin of magnetic fields in massive stars. Based on observations obtained in the framework of the ESO Prg. 191.D-0255(A,B).

  14. Regional lymph node radiotherapy in breast cancer: single anterior supraclavicular field vs. two anterior and posterior opposed supraclavicular fields

    PubMed Central

    Houshyari, Mohammad; Kashi, Amir Shahram Yousefi; Varaki, Sakineh Soleimani; Rakhsha, Afshin; Blookat, Eftekhar Rajab

    2015-01-01

    Background: The treatment of lymph nodes engaged in breast cancer with radiotherapy leads to improved locoregional control and enhanced survival rates in patients after surgery. The aim of this study was to compare two treatment techniques, namely single anterior posterior (AP) supraclavicular field with plan depth and two anterior and posterior opposed (AP/PA) supraclavicular fields. In the study, we also examined the relationships between the depth of supraclavicular lymph nodes (SCLNs) and the diameter of the wall of the chest and body mass index (BMI). Methods: Forty patients with breast cancer were analyzed using computed tomography (CT) scans. In planning target volume (PTV), the SCLNs and axillary lymph nodes (AXLNs) were contoured, and, with the attention to PTV, supraclavicular (SC) depth was measured. The dosage that reached the aforementioned lymph nodes and the level of hot spots were investigated using two treatment methods, i.e., 1) AP/PA and 2) AP with three-dimensional (3D) planning. Each of these methods was analyzed using the program Isogray for the 6 MV compact accelerator, and the diameter of the wall of the chest was measured using the CT scan at the center of the SC field. Results: Placing the plan such that 95% of the target volume with 95% or greater of the prescribed dose of 50 Gy (V95) had ?95% concordance in both treatment techniques. According to the PTV, the depth of SCLNs and the diameter of the wall of the chest were 3–7 and 12–21cm, respectively. Regression analysis showed that the mean SC depth (the mean Plan depth) and the mean diameter of the wall of the chest were related directly to BMI (p<0.0001, adjusted R2=0.67) and (p<0.0001, adjusted R2=0.71), respectively. Conclusion: The AP/PA treatment technique was a more suitable choice of treatment than the AP field, especially for overweight and obese breast cancer patients. However, in the AP/PA technique, the use of a single-photon, low energy (6 MV) caused more hot spots than usual. PMID:26120411

  15. Proper Motions of OH Masers and Magnetic Fields in Massive Star-forming Regions

    Microsoft Academic Search

    Vincent L. Fish; Mark J. Reid

    2007-01-01

    We present data of proper motions of OH masers in the massive star-forming regions ON 1, K3-50, and W51 Main\\/South. OH maser motions in ON 1 are consistent with expansion at approximately 5 km s-1, likely tracing the expanding ultracompact H II region. Motions in K3-50 are faster and may be indicating the final stages of OH maser emission in

  16. Effect of variety and moisture content on some engineering properties of paddy rice.

    PubMed

    Adebowale, Abdul-Rasaq A; Sanni, Lateef O; Owo, Hameed O; Karim, Olayinka R

    2011-10-01

    The effect of variety and moisture content on some engineering properties of five improved paddy rice varieties was investigated within moisture content range of 10% and 30% dry basis (d.b.). Increase in moisture content was found to increase the linear dimensions, mass of 100 seeds, surface area, apparent volume, true volume, arithmetic mean diameter, effective geometric diameter, sphericity, angle of repose, porosity and static coefficient of friction while bulk density and true density decreased with increase in moisture content. Static coefficient of friction was found to increase as moisture content increased from 0.34-0.46, 0.35-0.59, 0.36-0.46 and 0.34-0.45, respectively on plywood, galvanized steel, mild steel and glass structural surfaces. The highest static coefficient was found on galvanized steel. Angle of repose was found to increase as moisture content increases. The study concludes that variety and changes in moisture content significantly (P?

  17. Pesticide residues in two frog species in a paddy agroecosystem in Palakkad district, Kerala, India.

    PubMed

    Kittusamy, Ganesan; Kandaswamy, Chandrasekar; Kandan, Nambirajan; Subramanian, Muralidharan

    2014-12-01

    Pesticides residues were quantified in 109 frogs comprising two species (Fejervarya limnocharis and Hoplobatrachus crassus) from organic and conventional paddy farms in Kerala, India. Seven frogs from conventional but none from the organic farms revealed deformities. Levels of total Organochlorines (OCs) (33.22 ng/g) and Synthetic Pyrethroid, Fenvalerate-II (26.91/42.15 ng/g) in deformed F. limnocharis and H. crassus were significantly greater than in healthy frogs. Among OCs in healthy frogs, traces of ? (gamma)-HCH (hexachlorocyclohexane) (2.12 ng/g) were found only in F. limnocharis from organic farm. Among Organophosphates, Phorate (1.02 ng/g) and Quinalphos (2.62 ng/g) were present in traces in deformed F. limnocharis, while Parathion ethyl (1.02 ng/g) was detected in deformed H. crassus. The data indicate that the high level of pesticides may have contributed to the deformity of frogs. Therefore, an elaborative study will be essential to conserve amphibians in India. PMID:25173364

  18. Minimization of the field diffracted from a convex impedance body to the shadow region

    Microsoft Academic Search

    A. A. Zvyagintsev; A. I. Ivanov

    2002-01-01

    This work presents a method of body impedance (or covering) distribution determination, under which the field of the first antenna is the lowest on the second one. It is based on well-known asymptotic methods of field determination - the Geometrical Theory of Diffraction (GTD), Uniform Asymptotic Theory (UAT) and Ritz method for functional minimization.

  19. Dosimetric Assessment of the Field Abutment Region in Head and Neck Treatments Using a Multileaf Collimator

    Microsoft Academic Search

    Khaled Abdel-Hakim; Tetsuo Nishimura; Michikatsu Takaih; Shuji Suzuki; Harumi Sakahara

    2003-01-01

    Background and Purpose: The use of conventional asymmetric collimators for junctioning of abutted fields can lead to significant dose inhomogeneity, due to jaw misalignment. However, recent technologic advances enable us to fabricate much finer leafpositioning accuracy. Consequently, it is anticipated that the use of multileaf collimator (MLC) will potentially improve dose homogeneity at the junction of abutted fields. In this

  20. Electric field reversal in near-cathode region of glow discharge in helium

    Microsoft Academic Search

    A. A. Kudryavtsev; S. U. Nisimov; E. I. Prokhorova; A. G. Slyshov

    2011-01-01

    Longitudinal distributions of plasma parameters in a short (free of positive column) glow discharge in helium show evidence for the formation of a potential well for thermal electrons and the reversal of electric field in plasma of negative glow and Faraday dark space. Depending on the reduced discharge length pL, one or two points of field reversal can appear, which

  1. Transient behavior of a flare-associated solar wind. I - Gas dynamics in a radial open field region

    NASA Technical Reports Server (NTRS)

    Nagai, F.

    1984-01-01

    A numerical investigation is conducted into the way in which a solar wind model initially satisfying both steady state and energy balance conditions is disturbed and deformed, under the assumption of heating that correspoonds to the energy release of solar flares of an importance value of approximately 1 which occur in radial open field regions. Flare-associated solar wind transient behavior is modeled for 1-8 solar radii. The coronal temperature around the heat source region rises, and a large thermal conductive flux flows inward to the chromosphere and outward to interplanetary space along field lines. The speed of the front of expanding chromospheric material generated by the impingement of the conduction front on the upper chromosphere exceeds the local sound velocity in a few minutes and eventually exceeds 100 million cm/sec.

  2. POLAR Observations of Field Aligned O+ Flows at 5000 km Altitude Over the Polar Regions with Comparison to Auroral Images

    NASA Technical Reports Server (NTRS)

    Stevenson, B. A.; Horwitz, J. L.; Germany, G.; Craven, Paul D.; Moore, Thomas E.; Giles, B. L.; Parks, G. K.; Su, Y. J.

    2000-01-01

    Measurements of thermal 0+ ion parameters from the Thermal Ion Dynamics Experiment (TIDE) on POLAR obtained near 5000 km altitude are compared with auroral images from the Ultra Violet Imager (UVI), for southern perigee passes. Ion parameters, including parallel velocity, density, and flux are combined with multiple dayside and nightside auroral images to investigate relationships between O+ field aligned flows and the structure and brightness seen in the auroral forms. Results indicate field aligned upflowing O+ ions over regions of bright auroral activity and downward flows over dark regions. These and other relationships will be presented for several POLAR passes when both ion measurements and auroral images are observed under favorable conditions for comparison.

  3. High Resolution Simulations of the Plunging Region in a Pseudo-Newtonian Potential: Dependence on Numerical Resolution and Field Topology

    E-print Network

    John F. Hawley; Julian H. Krolik

    2001-10-04

    New three dimensional magnetohydrodynamic simulations of accretion disk dynamics in a pseudo-Newtonian Paczynski-Wiita potential are presented. These have finer resolution in the inner disk than any previously reported. Finer resolution leads to increased magnetic field strength, greater accretion rate, and greater fluctuations in the accretion rate. One simulation begins with a purely poloidal magnetic field, the other with a purely toroidal field. Compared to the poloidal initial field simulation, a purely toroidal initial field takes longer to reach saturation of the magnetorotational instability and produces less turbulence and weaker magnetic field energies. For both initial field configurations, magnetic stresses continue across the marginally stable orbit; measured in units corresponding to the Shakura-Sunyaev alpha parameter, the stress grows from ~0.1 in the disk body to as much as ~10 deep in the plunging region. Matter passing the inner boundary of the simulation has ~10% greater binding energy and ~10% smaller angular momentum than it did at the marginally stable orbit. Both the mass accretion rate and the integrated stress fluctuate widely on a broad range of timescales.

  4. Instantaneous and time-averaged flow fields of multiple vortices in the tip region of a ducted propulsor

    Microsoft Academic Search

    Ghanem F. Oweis; Steven L. Ceccio

    2005-01-01

    The instantaneous and time-averaged flow fields in the tip region of a ducted marine propulsor are examined. In this flow, a primary tip-leakage vortex interacts with a secondary, co-rotating trailing edge vortex and other co- and counter-rotating vorticity found in the blade wake. Planar particle imaging velocimetry (PIV) is used to examine the flow in a plane approximately perpendicular to

  5. Magnetic Field Clumping in Massive Star-Forming Regions as Determined from Excited-State OH Absorption and Maser Emission

    Microsoft Academic Search

    Vincent L. Fish; Mark J. Reid; Karl M. Menten

    2005-01-01

    We have observed six high-mass star-forming regions in the 2 Pi 3\\/2, J = 7\\/2\\u000alines of OH using the GBT in order to investigate whether the magnetic field,\\u000aand hence the density, measured in absorption differs from that implied by\\u000amaser Zeeman splitting. We detect absorption in both the 13441 and 13434 MHz\\u000amain lines in all six sources.

  6. Magnetic Field Clumping in Massive Star-forming Regions as Determined from Excited-State OH Absorption and Maser Emission

    Microsoft Academic Search

    Vincent L. Fish; Mark J. Reid; Karl M. Menten

    2005-01-01

    We have observed six high-mass-star-forming regions in the 2Pi3\\/2, J=7\\/2 lines of OH using the Green Bank Telescope (GBT) in order to investigate whether the magnetic field, and hence the density, measured in absorption differs from that implied by maser Zeeman splitting. We detect absorption in both the 13,441 and 13,434 MHz main lines in all six sources. Zeeman splitting

  7. An analytic solution for groundwater uptake by phreatophytes spanning spatial scales from plant to field to regional

    Microsoft Academic Search

    David R. Steward; Trevor S. Ahring

    2009-01-01

    Phreatophytes are important to the overall hydrologic water budget, providing pathways from the uptake of groundwater with\\u000a its nutrients and chemicals to subsequent discharge to the root zone through hydraulic lift and to the atmosphere through\\u000a evapotranspiration. An analytic mathematical model is developed to model groundwater uptake by individual plants and fields\\u000a of plant communities and the regional hydrology of

  8. Plasma wave, magnetic field and energetic ion observations in the ion pick-up region of Comet Giacobini-Zinner

    Microsoft Academic Search

    I. G. Richardson; S. W. H. Cowley; K.-P. Wenzel; F. L. Scarf; E. J. Smith; B. T. Tsurutani; T. R. Sanderson; R. J. Hynds

    1989-01-01

    Simultaneous plasma wave, magnetic field, and energetic ion observations made by the ICE spacecraft in the extended ion pick-up region surrounding comet Giacobini-Zinner are examined to determine the conditions under which two characteristic wave emissions, electrostatic waves at a few kHz, and electromagnetic waves at a few tens of Hz, are generated. The data are consistent with the view that

  9. Hyperdeformation in the cranked relativistic mean field theory: The Z=40-58 region of the nuclear chart

    SciTech Connect

    Afanasjev, A. V.; Abusara, H. [Department of Physics and Astronomy, Mississippi State University, Mississippi 39762 (United States)

    2008-07-15

    The systematic investigation of hyperdeformation (HD) at high spin in the Z=40-58 region of the nuclear chart was performed in the framework of the cranked relativistic mean-field theory. The properties of the moments of inertia of the HD bands, the role of the single-particle and necking degrees of freedom at HD, the spins at which the HD bands become yrast, the possibility to observe discrete HD bands, and so on are discussed in detail.

  10. Genetic relationships of grizzly bears (Ursus arctos) in the Prudhoe Bay region of Alaska: inference from microsatellite DNA, mitochondrial DNA, and field observations

    Microsoft Academic Search

    M. Cronin; R. Shideler; J. Hechtel; C. Strobeck; D. Paetkau

    1999-01-01

    Grizzly bears are abundant in the region of the Prudhoe Bay oil fields in northern Alaska. We used field observations and molecular genetic data to identify parent- offspring and sibling relationships among bears in this region. We determined ge- notypes at 14 microsatellite DNA loci and the cytochrome b gene of mitochondrial DNA (mtDNA) for 36 bears. We identified 17

  11. Extended Nijboer-Zernike representation of the vector field in the focal region of an aberrated

    E-print Network

    fields are equally used in leading edge optical lithography op- erating at a deep UV wavelength like 193 cells, cell nuclei and genetic material using advanced high-resolution microscopy. High-aperture focused

  12. The individual and relative contributions of different regions of the visual field to visual search 

    E-print Network

    Greenwood Mears, Ruth

    2012-06-27

    The individual and relative contributions of foveal, central and peripheral vision to object-scene search were assessed using the window and scotoma paradigms. The visual field simulation (window or scotoma and a control), ...

  13. Statistical field estimation and scale estimation for complex coastal regions and archipelagos

    E-print Network

    Agarwal, Arpit

    2009-01-01

    A fundamental requirement in realistic computational geophysical fluid dynamics is the optimal estimation of gridded fields and of spatial-temporal scales directly from the spatially irregular and multivariate data sets ...

  14. 77 FR 4862 - Agency Requests for Renewal of a Previously Approved Information Collection: SBTRC Regional Field...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-31

    ...meetings/ conferences, and services to businesses as completed during the quarter. The Quarterly Report Form provides a more composite and comprehensive review of the Field Offices' activities over a longer time frame. The information will be used to...

  15. MARS Electromagnetic Sounding Experiment (MARSES): Comparative Field Exploration on Devon Island and Other Regions

    NASA Technical Reports Server (NTRS)

    Ozorovich, Y. R.; Linkin, V. M.; Smythe, W. D.; Stoker, C.; Lee, P.; Zoubkov, B.; Babkin, F.

    2000-01-01

    MARSES is the sounding instrument developed for searching subsurface water, water-ice or permafrost layers. Preliminary results for field investigation has been gained during Devon Island expedition which surface structure is close to Martian conditions.

  16. Electric field reversal in near-cathode region of glow discharge in helium

    NASA Astrophysics Data System (ADS)

    Kudryavtsev, A. A.; Nisimov, S. U.; Prokhorova, E. I.; Slyshov, A. G.

    2011-09-01

    Longitudinal distributions of plasma parameters in a short (free of positive column) glow discharge in helium show evidence for the formation of a potential well for thermal electrons and the reversal of electric field in plasma of negative glow and Faraday dark space. Depending on the reduced discharge length pL, one or two points of field reversal can appear, which determines the sign of the anode fall.

  17. Evolution of Magnetic Field in the Flaring Active Region AR 11158 Based on SDO/HMI Observation

    NASA Astrophysics Data System (ADS)

    Sun, X.; Hoeksema, J. T.; Liu, Y.; Wiegelmann, T.; Hayashi, K.

    2011-12-01

    We report the evolution of magnetic field and its energy in NOAA active region 11158 based on a vector magnetogram series from the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamic Observatory (SDO). Over 5 days, the quadrupolar sunspot complex produced multiple eruptions, including the first X-class flare of the current solar cycle. Extrapolated non-linear force-free coronal fields suggest substantial electric current and free energy injection during early flux emergence along a newly-formed, pronounced filament. About 75% of the inferred free energy is stored below 10 Mm; the total decreased by 0.25E32 erg (10%) within 1 hour of the X-class flare, which is likely an underestimation of the actual energy loss. During the flare, photospheric flux underwent rapid redistribution: horizontal flux density was enhanced by 28% in the AR core region. Extrapolation shows that such change is consistent with the conjectured coronal field "implosion". Multiple coronal loops retraction were indeed observed for 5 minutes over 10 Mm during the impulsive phase. Modeling indicates that the coronal field becomes more compact after the flare, its lower layers more energetic but overall less so.

  18. Effects of External Radiation Fields on Line Emission—Application to Star-forming Regions

    NASA Astrophysics Data System (ADS)

    Chatzikos, Marios; Ferland, G. J.; Williams, R. J. R.; Porter, Ryan; van Hoof, P. A. M.

    2013-12-01

    A variety of astronomical environments contain clouds irradiated by a combination of isotropic and beamed radiation fields. For example, molecular clouds may be irradiated by the isotropic cosmic microwave background, as well as by a nearby active galactic nucleus. These radiation fields excite atoms and molecules and produce emission in different ways. We revisit the escape probability theorem and derive a novel expression that accounts for the presence of external radiation fields. We show that when the field is isotropic the escape probability is reduced relative to that in the absence of external radiation. This is in agreement with previous results obtained under ad hoc assumptions or with the two-level system, but can be applied to complex many-level models of atoms or molecules. This treatment is in the development version of the spectral synthesis code CLOUDY. We examine the spectrum of a Spitzer cloud embedded in the local interstellar radiation field and show that about 60% of its emission lines are sensitive to background subtraction. We argue that this geometric approach could provide an additional tool toward understanding the complex radiation fields of starburst galaxies.

  19. Effects of external radiation fields on line emission—application to star-forming regions

    SciTech Connect

    Chatzikos, Marios; Ferland, G. J. [University of Kentucky, Lexington, KY 40506 (United States); Williams, R. J. R. [AWE plc, Aldermaston, Reading RG7 4PR (United Kingdom); Porter, Ryan [Department of Physics and Astronomy and Center for Simulational Physics, University of Georgia, Athens, GA 30602-2451 (United States); Van Hoof, P. A. M., E-mail: mchatzikos@gmail.com [Royal Observatory of Belgium, Avenue Circulaire 3, B-1180 Uccle (Belgium)

    2013-12-20

    A variety of astronomical environments contain clouds irradiated by a combination of isotropic and beamed radiation fields. For example, molecular clouds may be irradiated by the isotropic cosmic microwave background, as well as by a nearby active galactic nucleus. These radiation fields excite atoms and molecules and produce emission in different ways. We revisit the escape probability theorem and derive a novel expression that accounts for the presence of external radiation fields. We show that when the field is isotropic the escape probability is reduced relative to that in the absence of external radiation. This is in agreement with previous results obtained under ad hoc assumptions or with the two-level system, but can be applied to complex many-level models of atoms or molecules. This treatment is in the development version of the spectral synthesis code CLOUDY. We examine the spectrum of a Spitzer cloud embedded in the local interstellar radiation field and show that about 60% of its emission lines are sensitive to background subtraction. We argue that this geometric approach could provide an additional tool toward understanding the complex radiation fields of starburst galaxies.

  20. What Supports the Parallel Electic Field in the Turbulent Birkeland Current Regions of the Earth's Magnetosphere? a New Paradigm

    NASA Astrophysics Data System (ADS)

    Jasperse, John

    Recent data from the FREJA, FAST and CLUSTER satellites have greatly increased our under-standing of the magnetic field-aligned (Birkeland) current system in the earth's magnetosphere. These satellite data and the early literature on anomalous transport in turbulent plasmas are briefly reviewed. Quasi-steady electric fields parallel to the background geomagnetic field exist in both upward and downward Birkeland current regions above the aurora. These fields, to-gether with the turbulence found on auroral field lines, energize the plasma particles as they flow either away from or toward the earth. In general, these parallel electric fields are sup-ported by: (1) one or more strong double layers; (2) the mirror force; (3) the generalized, parallel pressure gradient; and (4) anomalous transport effects due to turbulence. Recently, and for the first time, we have developed a fully self-consistent, multimoment fluid theory for the Birkeland current system that contains the effect of plasma turbulence [J. R. Jasperse et al. (2006), Phys. Plasmas 13, 072903, and J. R. Jasperse et al. (2006), Phys. Plasmas 13, 112902]. Applying the new theory to observations in a downward-current sheet, we are able to assess the relative importance of the four, above-mentioned contributions to the self-consistent, parallel electric field. We find that the anomalous resistivity itself produces a very small contribution to the parallel electric field; however the presence of electrostatic, ion-cyclotron turbulence has a very large effect on the on the altitude dependence of the entire quasi-steady solution. The magnitude of the parallel electric field is enlarged by nearly a factor of 50 compared to its value when turbulence is absent. We also find that the potential increase associated with the strong double layer that forms in downward currents can be evaluated using satellite data and the multimoment fluid theory.

  1. On the Association of Topologies of the Photospheric Magnetic Fields and Sub-photospheric Flows of Active Regions

    NASA Astrophysics Data System (ADS)

    Maurya, Ram Ajor

    Solar magnetic fields are believed to be generated near the solar tachocline jointly by differential rotation and turbulent motion, which are further transported toward the photosphere by convective flows. Therefore, we expect linear correlation between the topologies of the photospheric magnetic fields and the sub-photospheric flows. If observed magnetic fields conserve their helicity when they rise through the convection zone, the variation of kinetic helicity in the convection zone may be used as an observational tool for study the solar interior. Another important aspect of studying these parameters is due to their role in the energetic transients, e.g., flares and CMES. In order to examine the correlation between the two kinds of topologies, we analysed the photospheric and sub-photospheric properties of several active regions of the solar cycle 23 and 24. We computed the near sub-photospheric flows and topology parameters (e.g., vorticity, kinetic helicity) using local heliosiesmic techniques employed to the Doppler velocity observations. The photospheric magnetic field topology parameters, e.g., magnetic and current helicities, were determined from the magnetic field observations. We found opposite hemispheric trend in the topologies of the sub-photospheric flows and the photospheric magnetic fields. Details of the analysis will be presented in the paper.

  2. NONLINEAR FORCE-FREE FIELD MODELING OF A SOLAR ACTIVE REGION USING SDO/HMI AND SOLIS/VSM DATA

    SciTech Connect

    Thalmann, J. K.; Wiegelmann, T. [Max-Plank-Institut fuer Sonnensystemforschung, Max-Planck-Str. 2, 37191 Katlenburg-Lindau (Germany); Pietarila, A. [National Solar Observatory, 950 N. Cherry Avenue, Tucson, AZ 85719 (United States); Sun, X., E-mail: thalmann@mps.mpg.de [W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305 (United States)

    2012-08-15

    We use SDO/HMI and SOLIS/VSM photospheric magnetic field measurements to model the force-free coronal field above a solar active region, assuming magnetic forces dominate. We take measurement uncertainties caused by, e.g., noise and the particular inversion technique, into account. After searching for the optimum modeling parameters for the particular data sets, we compare the resulting nonlinear force-free model fields. We show the degree of agreement of the coronal field reconstructions from the different data sources by comparing the relative free energy content, the vertical distribution of the magnetic pressure, and the vertically integrated current density. Though the longitudinal and transverse magnetic flux measured by the VSM and HMI is clearly different, we find considerable similarities in the modeled fields. This indicates the robustness of the algorithm we use to calculate the nonlinear force-free fields against differences and deficiencies of the photospheric vector maps used as an input. We also depict how much the absolute values of the total force-free, virial, and the free magnetic energy differ and how the orientation of the longitudinal and transverse components of the HMI- and VSM-based model volumes compare to each other.

  3. Sampling approach for estimation of crop acreage under cloud cover satellite data in hilly regions

    NASA Astrophysics Data System (ADS)

    Sahoo, Prachi Misra; Rai, Anil; Krishnamoorthy, Sudhakar; Handique, B. K.; Rao, P. P. N.; Oza, M. P.; Parihar, J. S.

    2006-12-01

    Crop acreage estimation in hilly regions is till date a challenge for the remote sensing community due to the problems of undulating topography, inaccessibility to vast areas, smaller field size, practice of shifting cultivation, accounting for area falling under hill shades and valleys. Remote sensing alone may not be able to provide reliable estimate of crop acreage in these areas. In addition to this if these regions are humid or tropical for which it is difficult to get cloud free data then the problem becomes even more complicated. Many studies has been conducted in past for cloud/shadow removal but to estimate the crop area under the cloud cover has not been attempted. In this study at attempt has been made to estimate area under paddy crop in a district of Meghalaya by using sampling approach devised by integrating remote sensing, GIS and ground survey data taking into account the problem of hilly regions mentioned above. In addition to this technique for estimating the area under cloud /shadow using the previous year data and only on the basis of current year data is also proposed.

  4. Large-scale auroral distribution and the open-field-line region

    SciTech Connect

    Murphree, J.; Anger, C.; Meng, C.I.; Akasofu, S.

    1984-01-01

    An example of global auroral distribution is presented that is clearly more circular than oval and is thus fit to an offset circle. The area surrounded by the aurora is also compared with the open region constructed by a model of the open magnetosphere for the IMF condition about 1 h prior to the auroral observation.

  5. REGIONAL FIELD STUDY DESIGN FOR EVALUATION OF EULERIAN ACIDIC DEPOSITION MODELS

    EPA Science Inventory

    The U.S. Environmental Protection Agency and the Electric Power Research Institute, the Ontario Ministry of the Environment, and the Atmospheric Environmental Services have funded the development of two complex regional scale Eulerian acid deposition models, RADM and ADOM. There ...

  6. Longitudinal variation of the E-region electric fields caused by atmospheric tides

    Microsoft Academic Search

    S. L. England; S. Maus; T. J. Immel; S. B. Mende

    2006-01-01

    demonstrated that this could be explained by a longitudinal variation in the diurnal amplitude of atmospheric tides in the E-region ionosphere. An increase in the observed separation of the airglow arcs and a coincident strong increase in the peak ion density in the arcs is indicative of an effect that takes place while ion production is still occurring, such as

  7. The Importance of the Magnetic Field from an SMA-CSO-combined Sample of Star-forming Regions

    NASA Astrophysics Data System (ADS)

    Koch, Patrick M.; Tang, Ya-Wen; Ho, Paul T. P.; Zhang, Qizhou; Girart, Josep M.; Chen, Huei-Ru Vivien; Frau, Pau; Li, Hua-Bai; Li, Zhi-Yun; Liu, Hau-Yu Baobab; Padovani, Marco; Qiu, Keping; Yen, Hsi-Wei; Chen, How-Huan; Ching, Tao-Chung; Lai, Shih-Ping; Rao, Ramprasad

    2014-12-01

    Submillimeter dust polarization measurements of a sample of 50 star-forming regions, observed with the Submillimeter Array (SMA) and the Caltech Submillimeter Observatory (CSO) covering parsec-scale clouds to milliparsec-scale cores, are analyzed in order to quantify the magnetic field importance. The magnetic field misalignment ?—the local angle between magnetic field and dust emission gradient—is found to be a prime observable, revealing distinct distributions for sources where the magnetic field is preferentially aligned with or perpendicular to the source minor axis. Source-averaged misalignment angles lang|?|rang fall into systematically different ranges, reflecting the different source-magnetic field configurations. Possible bimodal lang|?|rang distributions are found for the separate SMA and CSO samples. Combining both samples broadens the distribution with a wide maximum peak at small lang|?|rang values. Assuming the 50 sources to be representative, the prevailing source-magnetic field configuration is one that statistically prefers small magnetic field misalignments |?|. When interpreting |?| together with a magnetohydrodynamics force equation, as developed in the framework of the polarization-intensity gradient method, a sample-based log-linear scaling fits the magnetic field tension-to-gravity force ratio lang? B rang versus lang|?|rang with lang? B rang = 0.116 · exp (0.047 · lang|?|rang) ± 0.20 (mean error), providing a way to estimate the relative importance of the magnetic field, only based on measurable field misalignments |?|. The force ratio ? B discriminates systems that are collapsible on average (lang? B rang < 1) from other molecular clouds where the magnetic field still provides enough resistance against gravitational collapse (lang? B rang > 1). The sample-wide trend shows a transition around lang|?|rang ? 45°. Defining an effective gravitational force ~1 - lang? B rang, the average magnetic-field-reduced star formation efficiency is at least a factor of two smaller than the free-fall efficiency. For about one fourth of the sources the average efficiency drops to zero. The force ratio ? B can further be linked to the normalized mass-to-flux ratio, yielding an estimate for the latter one without the need of field strength measurements. Across the sample, a transition from magnetically supercritical to subcritcal is observed with growing misalignment lang|?|rang.

  8. Regional Neural Response Differences in the Determination of Faces or Houses Positioned in a Wide Visual Field

    PubMed Central

    Wu, Jinglong; Chen, Kewei; Imajyo, Satoshi; Ohno, Seiichiro; Kanazawa, Susumu

    2013-01-01

    In human visual cortex, the primary visual cortex (V1) is considered to be essential for visual information processing; the fusiform face area (FFA) and parahippocampal place area (PPA) are considered as face-selective region and places-selective region, respectively. Recently, a functional magnetic resonance imaging (fMRI) study showed that the neural activity ratios between V1 and FFA were constant as eccentricities increasing in central visual field. However, in wide visual field, the neural activity relationships between V1 and FFA or V1 and PPA are still unclear. In this work, using fMRI and wide-view present system, we tried to address this issue by measuring neural activities in V1, FFA and PPA for the images of faces and houses aligning in 4 eccentricities and 4 meridians. Then, we further calculated ratio relative to V1 (RRV1) as comparing the neural responses amplitudes in FFA or PPA with those in V1. We found V1, FFA, and PPA showed significant different neural activities to faces and houses in 3 dimensions of eccentricity, meridian, and region. Most importantly, the RRV1s in FFA and PPA also exhibited significant differences in 3 dimensions. In the dimension of eccentricity, both FFA and PPA showed smaller RRV1s at central position than those at peripheral positions. In meridian dimension, both FFA and PPA showed larger RRV1s at upper vertical positions than those at lower vertical positions. In the dimension of region, FFA had larger RRV1s than PPA. We proposed that these differential RRV1s indicated FFA and PPA might have different processing strategies for encoding the wide field visual information from V1. These different processing strategies might depend on the retinal position at which faces or houses are typically observed in daily life. We posited a role of experience in shaping the information processing strategies in the ventral visual cortex. PMID:23991147

  9. Regional neural response differences in the determination of faces or houses positioned in a wide visual field.

    PubMed

    Wang, Bin; Yan, Tianyi; Wu, Jinglong; Chen, Kewei; Imajyo, Satoshi; Ohno, Seiichiro; Kanazawa, Susumu

    2013-01-01

    In human visual cortex, the primary visual cortex (V1) is considered to be essential for visual information processing; the fusiform face area (FFA) and parahippocampal place area (PPA) are considered as face-selective region and places-selective region, respectively. Recently, a functional magnetic resonance imaging (fMRI) study showed that the neural activity ratios between V1 and FFA were constant as eccentricities increasing in central visual field. However, in wide visual field, the neural activity relationships between V1 and FFA or V1 and PPA are still unclear. In this work, using fMRI and wide-view present system, we tried to address this issue by measuring neural activities in V1, FFA and PPA for the images of faces and houses aligning in 4 eccentricities and 4 meridians. Then, we further calculated ratio relative to V1 (RRV1) as comparing the neural responses amplitudes in FFA or PPA with those in V1. We found V1, FFA, and PPA showed significant different neural activities to faces and houses in 3 dimensions of eccentricity, meridian, and region. Most importantly, the RRV1s in FFA and PPA also exhibited significant differences in 3 dimensions. In the dimension of eccentricity, both FFA and PPA showed smaller RRV1s at central position than those at peripheral positions. In meridian dimension, both FFA and PPA showed larger RRV1s at upper vertical positions than those at lower vertical positions. In the dimension of region, FFA had larger RRV1s than PPA. We proposed that these differential RRV1s indicated FFA and PPA might have different processing strategies for encoding the wide field visual information from V1. These different processing strategies might depend on the retinal position at which faces or houses are typically observed in daily life. We posited a role of experience in shaping the information processing strategies in the ventral visual cortex. PMID:23991147

  10. Anaerobic arsenite oxidation by an autotrophic arsenite-oxidizing bacterium from an arsenic-contaminated paddy soil.

    PubMed

    Zhang, Jun; Zhou, Wuxian; Liu, Bingbing; He, Jian; Shen, Qirong; Zhao, Fang-Jie

    2015-05-19

    Microbe-mediated arsenic (As) redox reactions play an important role in the biogeochemical cycling of As. Reduction of arsenate [As(V)] generally leads to As mobilization in paddy soils and increased As availability to rice plants, whereas oxidation of arsenite [As(III)] results in As immobilization. A novel chemoautotrophic As(III)-oxidizing bacterium, designated strain SY, was isolated from an As-contaminated paddy soil. The isolate was able to derive energy from the oxidation of As(III) to As(V) under both aerobic and anaerobic conditions using O2 or NO3(-) as the respective electron acceptor. Inoculation of the washed SY cells into a flooded soil greatly enhanced As(III) oxidation to As(V) both in the solution and adsorbed phases of the soil. Strain SY is phylogenetically closely related to Paracoccus niistensis with a 16S rRNA gene similarity of 96.79%. The isolate contains both the denitrification and ribulose 1,5-bisphosphate carboxylase/oxygenase gene clusters, underscoring its ability to denitrify and to fix CO2 while coupled to As(III) oxidation. Deletion of the aioA gene encoding the As(III) oxidase subunit A abolished the As(III) oxidation ability of strain SY and led to increased sensitivity to As(III), suggesting that As(III) oxidation is a detoxification mechanism in this bacterium under aerobic and heterotrophic growth conditions. Analysis of the aioA gene clone library revealed that the majority of the As(III)-oxidizing bacteria in the soil were closely related to the genera Paracoccus of ?-Proteobacteria. Our results provide direct evidence for As(III) oxidation by Paracoccus species and suggest that these species may play an important role in As(III) oxidation in paddy soils under both aerobic and denitrifying conditions. PMID:25905768

  11. In Situ Measurement of Some Soil Properties in Paddy Soil Using Visible and Near-Infrared Spectroscopy

    PubMed Central

    Wenjun, Ji; Zhou, Shi; Jingyi, Huang; Shuo, Li

    2014-01-01

    In situ measurements with visible and near-infrared spectroscopy (vis-NIR) provide an efficient way for acquiring soil information of paddy soils in the short time gap between the harvest and following rotation. The aim of this study was to evaluate its feasibility to predict a series of soil properties including organic matter (OM), organic carbon (OC), total nitrogen (TN), available nitrogen (AN), available phosphorus (AP), available potassium (AK) and pH of paddy soils in Zhejiang province, China. Firstly, the linear partial least squares regression (PLSR) was performed on the in situ spectra and the predictions were compared to those with laboratory-based recorded spectra. Then, the non-linear least-square support vector machine (LS-SVM) algorithm was carried out aiming to extract more useful information from the in situ spectra and improve predictions. Results show that in terms of OC, OM, TN, AN and pH, (i) the predictions were worse using in situ spectra compared to laboratory-based spectra with PLSR algorithm (ii) the prediction accuracy using LS-SVM (R2>0.75, RPD>1.90) was obviously improved with in situ vis-NIR spectra compared to PLSR algorithm, and comparable or even better than results generated using laboratory-based spectra with PLSR; (iii) in terms of AP and AK, poor predictions were obtained with in situ spectra (R2<0.5, RPD<1.50) either using PLSR or LS-SVM. The results highlight the use of LS-SVM for in situ vis-NIR spectroscopic estimation of soil properties of paddy soils. PMID:25153132

  12. Effects of rapeseed residue on lead and cadmium availability and uptake by rice plants in heavy metal contaminated paddy soil.

    PubMed

    Ok, Yong Sik; Usman, Adel R A; Lee, Sang Soo; Abd El-Azeem, Samy A M; Choi, Bongsu; Hashimoto, Yohey; Yang, Jae E

    2011-10-01

    Rapeseed (Brassica napus L.) has been cultivated for biodiesel production worldwide. Winter rapeseed is commonly grown in the southern part of Korea under a rice-rapeseed double cropping system. In this study, a greenhouse pot experiment was conducted to assess the effects of rapeseed residue applied as a green manure alone or in combinations with mineral N fertilizer on Cd and Pb speciation in the contaminated paddy soil and their availability to rice plant (Oryza sativa L.). The changes in soil chemical and biological properties in response to the addition of rapeseed residue were also evaluated. Specifically, the following four treatments were evaluated: 100% mineral N fertilizer (N100) as a control, 70% mineral N fertilizer+rapeseed residue (N70+R), 30% mineral N fertilizer+rapeseed residue (N30+R) and rapeseed residue alone (R). The electrical conductivity and exchangeable cations of the rice paddy soil subjected to the R treatment or in combinations with mineral N fertilizer treatment, N70+R and N30+R, were higher than those in soils subjected to the N100 treatment. However, the soil pH value with the R treatment (pH 6.3) was lower than that with N100 treatment (pH 6.9). Use of rapeseed residue as a green manure led to an increase in soil organic matter (SOM) and enhanced the microbial populations in the soil. Sequential extraction also revealed that the addition of rapeseed residue decreased the easily accessible fraction of Cd by 5-14% and Pb by 30-39% through the transformation into less accessible fractions, thereby reducing metal availability to the rice plant. Overall, the incorporation of rapeseed residue into the metal contaminated rice paddy soils may sustain SOM, improve the soil chemical and biological properties, and decrease the heavy metal phytoavailability. PMID:21764102

  13. Relationships among seismic velocity, metamorphism, and seismic and aseismic fault slip in the Salton Sea Geothermal Field region

    NASA Astrophysics Data System (ADS)

    McGuire, Jeffrey J.; Lohman, Rowena B.; Catchings, Rufus D.; Rymer, Michael J.; Goldman, Mark R.

    2015-04-01

    The Salton Sea Geothermal Field is one of the most geothermally and seismically active areas in California and presents an opportunity to study the effect of high-temperature metamorphism on the properties of seismogenic faults. The area includes numerous active tectonic faults that have recently been imaged with active source seismic reflection and refraction. We utilize the active source surveys, along with the abundant microseismicity data from a dense borehole seismic network, to image the 3-D variations in seismic velocity in the upper 5 km of the crust. There are strong velocity variations, up to ~30%, that correlate spatially with the distribution of shallow heat flow patterns. The combination of hydrothermal circulation and high-temperature contact metamorphism has significantly altered the shallow sandstone sedimentary layers within the geothermal field to denser, more feldspathic, rock with higher P wave velocity, as is seen in the numerous exploration wells within the field. This alteration appears to have a first-order effect on the frictional stability of shallow faults. In 2005, a large earthquake swarm and deformation event occurred. Analysis of interferometric synthetic aperture radar data and earthquake relocations indicates that the shallow aseismic fault creep that occurred in 2005 was localized on the Kalin fault system that lies just outside the region of high-temperature metamorphism. In contrast, the earthquake swarm, which includes all of the M > 4 earthquakes to have occurred within the Salton Sea Geothermal Field in the last 15 years, ruptured the Main Central Fault (MCF) system that is localized in the heart of the geothermal anomaly. The background microseismicity induced by the geothermal operations is also concentrated in the high-temperature regions in the vicinity of operational wells. However, while this microseismicity occurs over a few kilometer scale region, much of it is clustered in earthquake swarms that last from hours to a few days and are localized near the MCF system.

  14. Force-free field modeling of twist and braiding-induced magnetic energy in an active-region corona

    SciTech Connect

    Thalmann, J. K. [Institute of Physics/IGAM, University of Graz, Universitätsplatz 5, A-8010 Graz (Austria); Tiwari, S. K.; Wiegelmann, T., E-mail: julia.thalmann@uni-graz.at [Max Plank Institute for Solar System Research, Max-Planck-Str. 2, D-37191 Katlenburg-Lindau (Germany)

    2014-01-01

    The theoretical concept that braided magnetic field lines in the solar corona may dissipate a sufficient amount of energy to account for the brightening observed in the active-region (AR) corona has only recently been substantiated by high-resolution observations. From the analysis of coronal images obtained with the High Resolution Coronal Imager, first observational evidence of the braiding of magnetic field lines was reported by Cirtain et al. (hereafter CG13). We present nonlinear force-free reconstructions of the associated coronal magnetic field based on Solar Dynamics Observatory/Helioseismic and Magnetic Imager vector magnetograms. We deliver estimates of the free magnetic energy associated with a braided coronal structure. Our model results suggest (?100 times) more free energy at the braiding site than analytically estimated by CG13, strengthening the possibility of the AR corona being heated by field line braiding. We were able to appropriately assess the coronal free energy by using vector field measurements and we attribute the lower energy estimate of CG13 to the underestimated (by a factor of 10) azimuthal field strength. We also quantify the increase in the overall twist of a flare-related flux rope that was noted by CG13. From our models we find that the overall twist of the flux rope increased by about half a turn within 12 minutes. Unlike another method to which we compare our results, we evaluate the winding of the flux rope's constituent field lines around each other purely based on their modeled coronal three-dimensional field line geometry. To our knowledge, this is done for the first time here.

  15. Geology, oil fields, and future petroleum potential of Santa Barbara channel region, California

    Microsoft Academic Search

    J. F. Curran; K. B. Hall; R. F. Herron

    1971-01-01

    The Santa Barbara Channel region is the westerly part of the Transverse Ranges geomorphic province of California. It includes the submerged seaward extension of the Ventura Basin and the continental slope to a distance of 70 miles off shore. A nearly complete post-Jurassic sedimentary section is present. The total section ranges in thickness from 19,200 to 67,600 ft. Potential reservoir

  16. Surficial geology of the Safsaf region, south-central Egypt, derived from remote-sensing and field data

    USGS Publications Warehouse

    Davis, P.A.; Breed, C.S.; McCauley, J.F.; Schaber, G.G.

    1993-01-01

    We used a decorrelation-stretched image of Landsat Thematic Mapper (TM) Bands 1, 4, and 7 and field data to map and describe the main surficial units in the hyperarid Safsaf region in south-central Egypt. We show that the near-infrared bands on Landsat TM, which are sensitive to very subtle changes in mineralogy common to arid regions, significantly improve the geologist's capability to discriminate geologic units in desert regions. These data also provide the spatial and spectral information necessary to determine the migration patterns and provenance of eolian materials. The Safsaf area was the focus of our post flight field studies using Shuttle Imaging Radar (SIR) data following the discovery of buried paleochannels in North Africa. Most of the channels discernible on SIR images are not expressed in TM data, but traces of a few channels are present in both the SIR and the TM data within the Wadi Safsaf area. Here we present a detailed digital examination of the SIR and the TM-band reflectance and reflectance-ratio data at three locations of the more obvious surface expressions of the buried channels. Our results indicate that the TM expressions of the channels are not purely topographic but are more compositional in nature. Two possibilities may account for the TM expressions of the buried channels: 1) concentrations of windblown, iron-rich materials that accumulated along subtle curvilinear topograpohic traps, or 2) curvilinear exposures of an iron-rich underlying unit of the flat sand sheet. ?? 1993.

  17. Analysis of Unstable Two-Phase Region in Wurtzite Group III Nitride Ternary Alloy Using Modified Valence Force Field Model

    NASA Astrophysics Data System (ADS)

    Takayama, Toru; Yuri, Masaaki; Itoh, Kunio; Baba, Takaaki; Harris, James S.

    2000-09-01

    The Group III-nitride ternary system is studied with respect to an unstable two-phase region in the phase field. The unstable two-phase region is analyzed using a strictly regular solution model. The interaction parameter used in the analysis is obtained from a strain energy calculation using the valence force field model, modified for both wurtzite and zinc-blende structures to avoid overestimation of the strain energy. The structural deviation from an ideal wurtzite structure in InN, GaN, and AlN is also taken into account in our model. According to the calculated results of the interaction parameters, the critical temperature for wurtzite InGaN, InAlN, and GaAlN are found to be 1967 K, 3399 K, and 181 K, respectively. This suggests that, at a typical growth temperature of 800-1000°C a wide unstable two-phase region exists in both InGaN and InAlN@. In order to show the validity of our calculation results, we compare the calculated results and the experimental results using the calculation of the interaction parameter for the InGaAs system. The calculated results agree well with the experimental results.

  18. Globally convergent trust-region methods for self-consistent field electronic structure calculations.

    PubMed

    Francisco, Juliano B; Martínez, José Mario; Martínez, Leandro

    2004-12-01

    As far as more complex systems are being accessible for quantum chemical calculations, the reliability of the algorithms used becomes increasingly important. Trust-region strategies comprise a large family of optimization algorithms that incorporates both robustness and applicability for a great variety of problems. The objective of this work is to provide a basic algorithm and an adequate theoretical framework for the application of globally convergent trust-region methods to electronic structure calculations. Closed shell restricted Hartree-Fock calculations are addressed as finite-dimensional nonlinear programming problems with weighted orthogonality constraints. A Levenberg-Marquardt-like modification of a trust-region algorithm for constrained optimization is developed for solving this problem. It is proved that this algorithm is globally convergent. The subproblems that ensure global convergence are easy-to-compute projections and are dependent only on the structure of the constraints, thus being extendable to other problems. Numerical experiments are presented, which confirm the theoretical predictions. The structure of the algorithm is such that accelerations can be easily associated without affecting the convergence properties. PMID:15634038

  19. Tectonic implications of the GPS velocity field in the northern Adriatic region

    E-print Network

    Stein, Seth

    leaving no significant deformation above 0.5 mm/yr in the Western and Northern Carpathians, and European but also because they impose far-field stresses on the broad Alpine-Dinaric-Carpathian system. Although the general evolution of the Carpathian-Pannonian complex is well constrained [Csontos et al., 1992

  20. Particle acceleration and radiation by direct electric fields in flaring complex solar active regions

    E-print Network

    Anastasiadis, Anastasios

    Particle acceleration and radiation by direct electric fields in flaring complex solar active-Meudon, 92195 Meudon Cedex, FRANCE Abstract The acceleration and radiation of solar energetic particles with the existing observations. 1 Introduction The approach used for particle acceleration models proposed for solar

  1. Reconstruction of Coastal-Scale Ocean Fields in an Upwelling Region

    Microsoft Academic Search

    Y. Zhang; J. G. Bellingham; R. Davis; D. Fratantoni; S. Ramp

    2007-01-01

    Coastal upwelling is an ecologically important ocean process. In this presentation, we first extract the upwelling mode in Monterey Bay from satellite and aircraft sea surface temperature (SST) measurements during the AOSN II Experiment in August 2003. Then we evaluate autonomous underwater vehicles' (AUVs') capability of capturing the upwelling mode and reconstructing the ocean field. The upwelling mode features colder

  2. Finite element calculation of fields around the end region of a turbine generator test rig

    Microsoft Academic Search

    J. F. Eastham; D. Rodger; H. C. Lai; H. Nouri

    1993-01-01

    The use of surface impedance elements and the use of volume elements when modeling at test rig using the MEGA package are compared. The test rig is representative of a turbine generator. The work is supported by practical measurements. Experimental results indicate that it is possible to model 3-D fields in large-scale objects containing nonlinear conducting iron using finite elements.

  3. Selection of the flux reference for induction machine drives in the field weakening region

    Microsoft Academic Search

    Xingyi Xu; Donald W. Novotny

    1992-01-01

    In a conventional rotor flux-oriented (RFO) induction machine drive, the flux reference is usually made proportional to the inverse of the rotor speed for field-weakening operation. It is indicated in this paper, however, that such a variation cannot maintain optimal (maximum) torque capability of the machine over the entire speed range. It is further indicated that a nearly optimal torque

  4. SCALING FROM FIELD TO REGION FOR WIND EROSION PREDICTION USING WEPS AND GIS.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The USDA-ARS Wind Erosion Prediction System (WEPS) is a process-based model that has the ability to simulate soil erosion and emissions of fine particulates from agricultural soils. WEPS was designed for field application, but erosion estimates are often required to assess emission inventories at th...

  5. CHARACTERISTICS AND EVOLUTION OF THE MAGNETIC FIELD AND CHROMOSPHERIC EMISSION IN AN ACTIVE REGION CORE OBSERVED BY HINODE

    SciTech Connect

    Brooks, David H.; Warren, Harry P. [Space Science Division, Code 7673, Naval Research Laboratory, Washington, DC 20375 (United States); Winebarger, Amy R., E-mail: dhbrooks@ssd5.nrl.navy.mi [Department of Physics, Alabama A and M, 4900 Meridian Street, Normal, AL 35762 (United States)

    2010-09-10

    We describe the characteristics and evolution of the magnetic field and chromospheric emission in an active region core observed by the Solar Optical Telescope (SOT) on Hinode. Consistent with previous studies, we find that the moss is unipolar, the spatial distribution of magnetic flux evolves slowly, and that the magnetic field is only moderately inclined. We also show that the field-line inclination and horizontal component are coherent, and that the magnetic field is mostly sheared in the inter-moss regions where the highest magnetic flux variability is seen. Using extrapolations from spectropolarimeter magnetograms, we show that the magnetic connectivity in the moss is different from that in the quiet Sun because most of the magnetic field extends to significant coronal heights. The magnetic flux, field vector, and chromospheric emission in the moss also appear highly dynamic but actually show only small-scale variations in magnitude on timescales longer than the cooling times for hydrodynamic loops computed from our extrapolations, suggesting high-frequency (continuous) heating events. Some evidence is found for flux (Ca II intensity) changes on the order of 100-200 G (DN) on timescales of 20-30 minutes that could be taken as indicative of low-frequency heating. We find, however, that only a small fraction (10%) of our simulated loops would be expected to cool on these timescales, and we do not find clear evidence that the flux changes consistently produce intensity changes in the chromosphere. Using observations from the EUV Imaging Spectrometer (EIS), we also determine that the filling factor in the moss is {approx}16%, consistent with previous studies and larger than the size of an SOT pixel. The magnetic flux and chromospheric intensity in most individual SOT pixels in the moss vary by less than {approx}20% and {approx}10%, respectively, on loop cooling timescales. In view of the high energy requirements of the chromosphere, we suggest that these variations could be sufficient for the heating of 'warm' EUV loops, but that the high basal levels may be more important for powering the hot core loops rooted in the moss. The magnetic field and chromospheric emission appear to evolve gradually on spatial scales comparable to the cross-field scale of the fundamental coronal structures inferred from EIS measurements.

  6. Mars Pathfinder Landing Site Workshop II: Characteristics of the Ares Vallis Region and Field Trips in the Channeled Scabland, Washington

    NASA Astrophysics Data System (ADS)

    Golombek, M. P.; Edgett, K. S.; Rice, J. W., Jr.

    1995-09-01

    Mars Pathfinder will place a single lander on the surface of Mars on July 4, 1997, following a December 1996 launch. As a result of the very successful first Mars Pathfinder Landing Site Workshop, the project has selected the Ares Vallis outflow channel in Chryse Planitia as the landing site. This location is where a large catastrophic outflow channel debouches into the northern lowlands. A second workshop and series of field trips, entitled Mars Pathfinder Landing Site Workshop 2: Characteristics of the Ares Vallis Region and Field Trips in the Channeled Scabland, Washington, were held in Spokane and Moses Lake, Washington. The purpose of the workshop was to provide a focus for learning as much as possible about the Ares Vallis region on Mars before landing there. The rationale is that the more that can be learned about the general area prior to landing, the better scientists will be able interpret the observations made by the lander and rover and place them in the proper geologic context. The field trip included overflights and surface investigations of the Channeled Scabland (an Earth analog for the martian catastrophic outflow channels), focusing on areas particularly analogous to Ares Vallis and the landing site. The overflights were essential for placing the enormous erosional and depositional features of the Channeled Scabland into proper three-dimensional context. The field trips were a joint educational outreach activity involving K-12 science educators, Mars Pathfinder scientists and engineers, and interested scientists from the Mars scientific community. Part 1 of the technical report on this workshop includes a description of the Mars Pathfinder mission, abstracts accepted for presentation at the workshop, an introduction to the Channeled Scabland, and field trip guides for the overflight and two field trips. This part, Part 2, includes the program for the workshop, summaries of the workshop technical sessions, a summary of the field trips and ensuing discussions, late abstracts of workshop presentations, reports on the education and public outreach activities carried out by the educators, and a list of the workshop and field trip participants.

  7. Mars Pathfinder Landing Site Workshop 2: Characteristics of the Ares Vallis Region and Field Trips in the Channeled Scabland, Washington

    NASA Technical Reports Server (NTRS)

    Golombek, M. P. (Editor); Edgett, K. S. (Editor); Rice, J. W. , Jr. (Editor)

    1995-01-01

    Mars Pathfinder will place a single lander on the surface of Mars on July 4, 1997, following a December 1996 launch. As a result of the very successful first Mars Pathfinder Landing Site Workshop, the project has selected the Ares Vallis outflow channel in Chryse Planitia as the landing site. This location is where a large catastrophic outflow channel debouches into the northern lowlands. A second workshop and series of field trips, entitled Mars Pathfinder Landing Site Workshop 2: Characteristics of the Ares Vallis Region and Field Trips in the Channeled Scabland, Washington, were held in Spokane and Moses Lake, Washington. The purpose of the workshop was to provide a focus for learning as much as possible about the Ares Vallis region on Mars before landing there. The rationale is that the more that can be learned about the general area prior to landing, the better scientists will be able interpret the observations made by the lander and rover and place them in the proper geologic context. The field trip included overflights and surface investigations of the Channeled Scabland (an Earth analog for the martian catastrophic outflow channels), focusing on areas particularly analogous to Ares Vallis and the landing site. The overflights were essential for placing the enormous erosional and depositional features of the Channeled Scabland into proper three-dimensional context. The field trips were a joint educational outreach activity involving K-12 science educators, Mars Pathfinder scientists and engineers, and interested scientists from the Mars scientific community. Part 1 of the technical report on this workshop includes a description of the Mars Pathfinder mission, abstracts accepted for presentation at the workshop, an introduction to the Channeled Scabland, and field trip guides for the overflight and two field trips. This part, Part 2, includes the program for the workshop, summaries of the workshop technical sessions, a summary of the field trips and ensuing discussions, late abstracts of workshop presentations, reports on the education and public outreach activities carried out by the educators, and a list of the workshop and field trip participants.

  8. Focal mechanisms in the southern Aegean from temporary seismic networks - implications for the regional stress field and ongoing deformation processes

    NASA Astrophysics Data System (ADS)

    Friederich, W.; Brüstle, A.; Küperkoch, L.; Meier, T.; Lamara, S.; Egelados Working Group

    2014-05-01

    The lateral variation of the stress field in the southern Aegean plate and the subducting Hellenic slab is determined from recordings of seismicity obtained with the CYCNET and EGELADOS networks in the years from 2002 to 2007. First motions from 7000 well-located microearthquakes were analysed to produce 540 well-constrained focal mechanisms. They were complemented by another 140 derived by waveform matching of records from larger events. Most of these earthquakes fall into 16 distinct spatial clusters distributed over the southern Aegean region. For each cluster, a stress inversion could be carried out yielding consistent estimates of the stress field and its spatial variation. At crustal levels, the stress field is generally dominated by a steeply dipping compressional principal stress direction except in places where coupling of the subducting slab and overlying plate come into play. Tensional principal stresses are generally subhorizontal. Just behind the forearc, the crust is under arc-parallel tension whereas in the volcanic areas around Kos, Columbo and Astypalea tensional and intermediate stresses are nearly degenerate. Further west and north, in the Santorini-Amorgos graben and in the area of the islands of Mykonos, Andros and Tinos, tensional stresses are significant and point around the NW-SE direction. Very similar stress fields are observed in western Turkey with the tensional axis rotated to NNE-SSW. Intermediate-depth earthquakes below 100 km in the Nisyros region indicate that the Hellenic slab experiences slab-parallel tension at these depths. The direction of tension is close to east-west and thus deviates from the local NW-oriented slab dip presumably owing to the segmentation of the slab. Beneath the Cretan sea, at shallower levels, the slab is under NW-SE compression. Tensional principal stresses in the crust exhibit very good alignment with extensional strain rate principal axes derived from GPS velocities except in volcanic areas, where both appear to be unrelated, and in the forearc where compressional principal stresses are very well aligned with compressional principal strain rates. This finding indicates that, except for volcanic areas, microseismic activity in the southern Aegean is not controlled by small-scale local stresses but rather reflects the regional stress field. The lateral and depth variations of the stress field reflect the various agents that influence tectonics in the Aegean: subduction of the Hellenic slab, incipient collision with continental African lithosphere, roll back of the slab in the southeast, segmentation of the slab, arc volcanism and extension of the Aegean crust.

  9. OBSERVATION OF A NON-RADIAL PENUMBRA IN A FLUX EMERGING REGION UNDER CHROMOSPHERIC CANOPY FIELDS

    SciTech Connect

    Lim, Eun-Kyung; Yurchyshyn, Vasyl; Goode, Philip [Big Bear Solar Observatory, New Jersey Institute of Technology, 40386 North Shore Lane, Big Bear City, CA 92314-9672 (United States); Cho, Kyung-Suk, E-mail: eklim@kasi.re.kr [Korea Astronomy and Space Science Institute 776, Daedeokdae-ro, Yuseong-gu, Daejeon 305-348 (Korea, Republic of)

    2013-05-20

    The presence of a penumbra is one of the main properties of a mature sunspot, but its formation mechanism has been elusive due to a lack of observations that fully cover the formation process. Utilizing the New Solar Telescope at the Big Bear Solar Observatory, we observed the formation of a partial penumbra for about 7 hr simultaneously at the photospheric (TiO; 7057 A) and the chromospheric (H{alpha} - 1 A) spectral lines with high spatial and temporal resolution. From this uninterrupted, long observing sequence, we found that the formation of the observed penumbra was closely associated with flux emergence under the pre-existing chromospheric canopy fields. Based on this finding, we suggest a possible scenario for penumbra formation in which a penumbra forms when the emerging flux is constrained from continuing to emerge, but rather is trapped at the photospheric level by the overlying chromospheric canopy fields.

  10. The impact of strong radiation fields on protostars in the R CrA region

    NASA Astrophysics Data System (ADS)

    Lindberg, J. E.; Jorgensen, J. K.; Herschel DIGIT Team

    2011-05-01

    We have started a multi-wavelength survey of a couple of low-mass Young Stellar Objects (YSOs) in the star forming region R Coronae Australis situated close to the Herbig Ae star R Coronae Australis. The presence of a massive star gives us a nice opportunity to study the effects from nearby stars on the chemistry around low-mass YSOs. We have studied the excited molecular gas in the region in both millimetre (H_2CO, CH_3OH, c-C_3H_2, DCN, SiO, etc.) using SMA and APEX; and far-infrared (CO, OH, H_2O) using Herschel Space Observatory. In millimetre, the molecular emission does not show a normal outflow pattern, but rather a clumpy ridge pointing towards the Herbig Ae star. This might imply that the molecular gas around the YSOs is directly affected by the proximity to this star. The Herschel data show very strong OH emission compared to similar star forming regions, which could indicate that the excitation of the gas is affected by the presence of the Herbig Ae star. Relatively strong and extended CO emission is also detected. Comparing the Herschel and the SMA/APEX data allows examination of two different temperature regimes of the molecular gas. The forest of CO rotation lines seen in the Herschel data show two warm temperature components for both YSOs (T˜ 350-800 K). The SMA/APEX data instead traces much colder gas, on the order of 20-60 K. We clearly see that the CO 21-20 (2414 GHz) and H_2CO 303-202 (218 GHz) emission make out two different parts of the surroundings of the YSOs.

  11. Chromatic compensation in the near-field region: shape and size tunability

    Microsoft Academic Search

    G. Mínguez-Vega; M. Fernández-Alonso; E. Tajahuerce; J. Lancis; Z. Jaroszewicz; P. Andrés

    2005-01-01

    We report a diffractive-lens triplet with which to achieve wavelength compensation in the near field diffracted by any aperture. On the one hand, the all-diffractive triplet allows us to tune, in a sequential way, the Fresnel-irradiance shape to be achromatized by changing the focal length of one diffractive lens. On the other hand, we can adjust the scale of the

  12. Observation from space of meteorological fields at the scale of regional Numerical Weather Forecast models

    Microsoft Academic Search

    G. Perona; R. Notarpietro; M. Gabella; A. Speranza

    2003-01-01

    In this paper we report the results of feasibility studies concerning the use of radars on polar orbiting space-platforms for the direct observation of meteorological fields (in particular large-scale vertical velocity) that are crucial in the initialisation and verification of models for NWF (Numerical Weather Forecast). Specifically, we have made reference to LAM (Limited Area Models) with horizontal grid-size of

  13. Proper Motions of OH Masers and Magnetic Fields in Massive Star-Forming Regions

    Microsoft Academic Search

    Vincent L. Fish; Mark J. Reid

    2007-01-01

    We present data of proper motions of OH masers in the massive star-forming\\u000aregions ON 1, K3-50, and W51 Main\\/South. OH maser motions in ON 1 are\\u000aconsistent with expansion at approximately 5 km\\/s, likely tracing the expanding\\u000aultracompact H II region. Motions in K3-50 are faster and may be indicating the\\u000afinal stages of OH maser emission in the

  14. Structure and Dynamics of the Sub-corotating Region of Saturn's Magnetosphere: Cassini Magnetic Field Observations.

    NASA Astrophysics Data System (ADS)

    Smith, E. J.; Dougherty, M. K.

    2014-12-01

    Measurements of the azimuthal magnetic field component, B?, enable the study of the sub-corotating magnetosphere, the associated global current system, the ionospheric Pedersen current, IP, and a comparison with the Cowley-Vasyliunas model. The study is strongly dependent on Cassini's highly elliptical orbits that restrict useful observations to specific orbits and parts of orbits to avoid weak azimuthal fields associated with the magnetopause or other magnetospheric currents. An example is the selection of thirteen identical orbits near 22 +/- 2 hours Local Time and restriction of the data to 4 to 10 Saturn radii. Inferred IP profiles between 10° and 25° ionospheric co-latitude, ?i , when averaged, are similar in shape to model predictions with a peak value of 5 million amperes. However, the individual profiles vary sig