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1

Modeling for Management of Farmland in Rural Communities —— A Large-scale Paddy Field in the Hokkaido Region  

Microsoft Academic Search

In this paper, we construct a model for management of farmland in rural communities to examine the effect of change in farm laborers. Based on the rural community data of Ishikari and Sorachi regions in Hokkaido paddy fields, we empirically found that the decrease in and aging of farm laborers negatively contributes to farm management. The results also showed that

Nobuyoshi YASUNAGA; Isao HARA

2

Paddy field, groundwater and land subsidence  

SciTech Connect

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.

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

1995-12-31

3

Arsenic Behavior in Paddy Fields during the Cycle of Flooded and  

E-print Network

Arsenic Behavior in Paddy Fields during the Cycle of Flooded and Non-flooded Periods Y O S H I O. The results show that Fe (hydr)oxide hosts As in soil. Arsenic in irrigation waters is incorporated in Fe, which produces the staple food in the region. Arsenic concentration is generally less than 10 mg

4

Spatial variation of infiltration rate and compactness in paddy fields  

Microsoft Academic Search

Percolation loss of water in rice fields is a major cause of low water use efficiency. Variation of infiltration rate and\\u000a soil compactness in four paddy fields (with clay, silty clay, clay loam, and loam textures) was investigated in northern Iran.\\u000a In each field, in longitudinal and transverse directions, points located 0.5, 2.5, 6.5, 12.5, … m from the bunds

S. F. Mousavi; F. Kamyab-Talesh; M. R. Yazdani; S. H. Saghaian-Nejad

5

[Response of mineralization of dissolved organic carbon to soil moisture in paddy and upland soils in hilly red soil region].  

PubMed

Typical paddy and upland soils were collected from a hilly subtropical red-soil region. 14C-labeled dissolved organic carbon (14C-DOC) was extracted from the paddy and upland soils incorporated with 14C-labeled straw after a 30-day (d) incubation period under simulated field conditions. A 100-d incubation experiment (25 degrees C) with the addition of 14C-DOC to paddy and upland soils was conducted to monitor the dynamics of 14C-DOC mineralization under different soil moisture conditions [45%, 60%, 75%, 90%, and 105% of the field water holding capacity (WHC)]. The results showed that after 100 days, 28.7%-61.4% of the labeled DOC in the two types of soils was mineralized to CO2. The mineralization rates of DOC in the paddy soils were significantly higher than in the upland soils under all soil moisture conditions, owing to the less complex composition of DOC in the paddy soils. The aerobic condition was beneficial for DOC mineralization in both soils, and the anaerobic condition was beneficial for DOC accumulation. The biodegradability and the proportion of the labile fraction of the added DOC increased with the increase of soil moisture (45% -90% WHC). Within 100 days, the labile DOC fraction accounted for 80.5%-91.1% (paddy soil) and 66.3%-72.4% (upland soil) of the cumulative mineralization of DOC, implying that the biodegradation rate of DOC was controlled by the percentage of labile DOC fraction. PMID:24984493

Chen, Xiang-Bi; Wang, Ai-Hua; Hu, Le-Ning; Huang, Yuan; Li, Yang; He, Xun-Yang; Su, Yi-Rong

2014-03-01

6

Modeling methane emissions from paddy rice fields under elevated atmospheric carbon dioxide conditions  

NASA Astrophysics Data System (ADS)

Methane (CH4) emissions from paddy rice fields substantially contribute to the dramatic increase of this greenhouse gas in the atmosphere. Due to great concern about climate change, it is necessary to predict the effects of the dramatic increase in atmospheric carbon dioxide (CO2) on CH4 emissions from paddy rice fields. CH4MOD 1.0 is the most widely validated model for simulating CH4 emissions from paddy rice fields exposed to ambient CO2 (hereinafter referred to as aCO2). We upgraded the model to CH4MOD 2.0 by: (a) modifying the description of the influences of soil Eh and the water regime on CH4 production; (b) adding new features to reflect the regulatory effects of atmospheric CO2 upon methanogenic substrates, soil Eh during drainages, and vascular CH4 transport; and (c) adding a new feature to simulate the influences of nitrogen (N) addition rates on methanogenic substrates under elevated CO2 (hereinafter referred to as eCO2) condition. Validation with 109 observation cases under aCO2 condition showed that CH4MOD 2.0 possessed a minor systematic bias in the prediction of seasonally accumulated methane emissions (SAM). Validation with observations in free-air CO2 enrichment (FACE) experiments in temperate and subtropical climates showed that CH4MOD 2.0 successfully simulated the effects of eCO2 upon SAM from paddy rice fields incorporated with various levels of previous crop residues and/or N fertilizer. Our results imply that CH4MOD 2.0 provides a potential approach for estimating of the effects of elevated atmospheric CO2 upon CH4 emissions from regional or global paddy rice fields with various management practices in a changing climate.

Xie, Baohua; Zhou, Zaixing; Zheng, Xunhua; Zhang, Wen; Zhu, Jianguo

2010-01-01

7

Residual Rate and Escape Route Preference of Juvenile Carassius auratus grandoculis Reared in Paddy Fields  

NASA Astrophysics Data System (ADS)

Gathering paddy-reared juvenile fish (0-year fish) at the paddy's drain outlet at the time of the mid-summer drainage often results in many unharvested fish being left behind. To devise ways of reducing this wastage as much as possible, we performed two experiments during the irrigation season in modernized, consolidated paddy fields as follows. Experiment I: an investigation into the numbers of juvenile Carassius auratus grandoculis that succeeded in leaving a paddy field through the drain outlet. Experiment II: an investigation into their preferred route of escape from the paddy, either via the drain outlet or the water inlet, when both were available. In Experiment I, more than 39.1% of the number of fish that escaped from the paddy were still left behind in the paddy more than three days after the mid-summer drainage had begun. In Experiment II, most of the juveniles, i.e., 99.8% of the fish that escaped from the paddy, left from the water inlet. These results suggest that greater efficiency in reducing the numbers of unharvested juvenile fish in paddy culture may be achieved by first capturing fish at the drain outlet with the irrigation water shut off, and then partially refilling the paddy while using traps or other gear to catch the remaining fish that are attracted towards the water inlet.

Maehata, Masayoshi; Ohtsuka, Taisuke; Mizuno, Toshiaki; Kanao, Shigefumi

8

Risk assessment of ?-cyhalothrin on aquatic organisms in paddy field in China  

Microsoft Academic Search

This study was carried out to assess the risk of ?-cyhalothrin to aquatic organisms used in paddy field, and to provide assistance in the ecological risk management of ?-cyhalothrin. The acute toxicities of five individual formulations of ?-cyhalothrin to four aquatic species were investigated in the laboratory, as well as in a simulated paddy field–pond ecosystem, and the results implicated

Bao G. Gu; Hui M. Wang; William L. Chen; Dao J. Cai; Zheng J. Shan

2007-01-01

9

Prediction of the environmental concentration of pesticide in paddy field and surrounding surface water bodies  

Microsoft Academic Search

Pesticides are very important in European rice production. For appropriate environmental protection, it is useful to predict the potential impact of pesticides after application, in paddy fields, in paddy runoff, and in the surrounding water, by calculating predicted environmental concentrations (PECs). In this paper, a joint simulation is described, coupling a field-scale pesticide fate model (RICEWQ) and a transportation model

Zewei Miao; Laura Padovani; Carlo Riparbelli; Amy M. Ritter; Marco Trevisan; Ettore Capri

2003-01-01

10

Evaluating Attitudes towards Changes in Rural Landscape by Grazing Cattle on Abandoned Paddy Fields  

NASA Astrophysics Data System (ADS)

The appearance of cattle grazing abandoned paddy fields can be used to evaluate attitudes towards this land-use change. The semantic differential (SD) method was used families of a university student to evaluate and compare attitudes towards five types of rural landscape: pasture, pasture grazed by cattle, rice paddy field, abandoned paddy field converted to pasture and abandoned paddy field converted to pasture grazed by cattle. Cattle grazing abandoned paddy fields were determined to have a positive effect on the landscape. However, all grazing cattle created a negative attitude because of the unclean appearance of the landscape. Grazing cattle at high stocking rates in small areas could create a negative attitude because of the oppressive appearance of the landscape. The acceptance of grazing cattle was lower if the animals ware newly introduced to the landscape.

Yasuhito, Kitai; Toshihiro, Hattori; Hiroshi, Takahashi

11

[Residue dynamics of flubendiamide in paddy field].  

PubMed

Residue dynamics and terminal residue of flubendiamide 19.8% suspension concentrate (SC) in rice and field environment were measured by ultra performance liquid chromatography (UPLC). As flubendiamide and its metabolite were applied at a range of concentrations from 0.05 to 1.0 mg.kg-1, average recoveries of them in soil, water, rice straw, rice grain and rice hull samples ranged from 78.2% to 104.8%, with variation coefficients of 1.1% -4.4%. One-year and three-area results showed that the half-life of gradation for flubendiamide was 9. 8 to 17.3 d in water, 10. 8 to 22.4 d in soil, and 7.6 to 17.3 d in rice plants, respectively. Residues of metabolite NNI-des-iodo in water were detected, but not in soil or rice plants. When flubendiamide was applied at the recommended dose, its residue in rice grain on the 10th day after application was lower than 0.5 mg.kg-1, the maximum residue limit allowed by US for agricultural chemical residues in rice. PMID:23668149

Wang, Dian-Dian; Song, Ning-Hui; Wu, Wen-Zhu; You, Zong-Zheng; He, Jian; Shi, Li-Li

2013-02-01

12

Genetic Structure of Loach Population in Yatsu Paddy Field  

NASA Astrophysics Data System (ADS)

Using repeated sequences of microsatellite DNA, we investigated genetic variation and spatial structure of the loach Misgurnus anguillicaudatus population in drainage canals including a main stream in the Shitada River basin composed of Yatsu paddy fields, Chiba Prefecture. Loach population samples of nine to 48 individuals were collected from 54 sampling sites in eight canals and the main stream, and genotype data in eight microsatellite loci were obtained for each sample in the genetic analysis. The average number of alleles per locus was 3.9 to 9.0, and the average observed and expected heterozygosities were 0.444-0.647 and 0.463-0.628, respectively, across samples. All samples seemed to be random mating, which conformed to the Hardy-Weinberg equilibrium. Values of the fixation index FST, were estimated to range between 0-0.161 among all samples, and a part of these values were significant. The pattern of genetic differentiation between samples with principal component analysis indicated that samples in three distinct canals appeared to differentiate, suggesting that the genetic spatial structure of the loach population in Yatsu paddy fields must be complex.

Koizumi, Noriyuki; Takemura, Takeshi; Mori, Atsushi; Okushima, Shuji

13

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

Microsoft Academic Search

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

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

14

Immigration and Migration of Fish to Paddy Fields for Early Crop Rice  

NASA Astrophysics Data System (ADS)

Fish immigration and migration to early-planted paddy fields was investigated in Kaminanami-cho, in Matsusaka-city, Mie prefecture. Fish immigrated to paddy fields in the upper area through water inlets during the intake of water and they spawned eggs. Since it is rare that water is taken into paddy fields in the lower area, fish immigrated to there through water outlets when water from the drainage channel overflowed due to rainfall. Paddy fields in the lower area functioned as breeding and refuge areas. Oryzias latipes immigrated to paddy fields in the middle of April just after rice planting, and Misgurnus anguillicaudatus immigrated in May. The standard length of M. anguillicaudatus fries that emigrated from paddy fields to irrigation channels during mid-summer drainage in Kaminanami was significantly smaller than those in Kunitachi-city, Tokyo where rice is planted in early June. The small standard length of former may be attributed to a low water temperature; short term to be able to grow in paddy fields until mid-summer drainage. If accelerated cropping season make negative effect on fish spawning and growth, it will be more important to conserve spawning and growth areas in irrigation channels.

Minagawa, Akiko; Takaki, Kyoji; Goto, Masahiro; Taruya, Hiroyuki

15

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

Microsoft Academic Search

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.

D. Hocking; K. Islam

1995-01-01

16

Model Development for Nutrient Loading Estimates from Paddy Rice Fields in Korea  

Microsoft Academic Search

A field experiment was performed to evaluate water and nutrient balances in paddy rice culture operations during 2001–2002. The water balance analysis indicated that about half (50–60%) of the total outflow was lost by surface drainage, with the remainder occurring by evapotranspiration (490–530 mm). The surface drainage from paddy fields was mainly caused by rainfall and forced-drainage, and in particular, the

Ji-Hong Jeon; Chun G. Yoon; Jong-Hwa Ham; Kwang-Wook Jung

2004-01-01

17

Depth distribution of radiocesium in Fukushima paddy fields and implications for ongoing decontamination works  

NASA Astrophysics Data System (ADS)

Large quantities of radiocesium were deposited across a 3000 km2 area northwest of the Fukushima Dai-ichi nuclear power plant after 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 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 or transfer of radioactive contaminants from soils to rice. Radionuclide activity concentrations and organic content 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 radiocesium with the majority concentrated in the uppermost layers of soils (< 5 cm). More than 30 months after the accident, 81.5 to 99.7% of the total 137Cs inventories was still found within the < 5 cm of the soil surface, despite cumulative rainfall totalling 3300 mm. Furthermore, there were no significant correlations between radiocesium migration depth and total organic carbon content. We attributed the maximum depth penetration of 137Cs to maintenance (grass cutting - 97% of 137Cs in the upper 5 cm) and farming operations (tilling - 83% of 137Cs 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. Remediation efforts should be concentrated on soils characterised by radiocesium activities > 10 000 Bq kg-1 to prevent the contamination of rice. Further analysis is required to clarify the redistribution of radiocesium eroded on river channels.

Lepage, H.; Evrard, O.; Onda, Y.; Lefèvre, I.; Laceby, J. P.; Ayrault, S.

2014-09-01

18

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

PubMed

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

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

2014-08-01

19

¹³?Cs in irrigation water and its effect on paddy fields in Japan after the Fukushima nuclear accident.  

PubMed

There is concern that radiocesium deposited in the environment after the accident at the Fukushima Daiichi Nuclear Power Plant (FDNPP) in March 2011 will migrate to paddy fields through hydrological pathways and cause serious and long-lasting damage to the agricultural activities. This study was conducted in the Towa region of Nihonmatsu in the northern part of Fukushima Prefecture, Japan, (1) to quantify (137)Cs in stream water used to irrigate paddy fields by separating the dissolved and particulate components in water samples and then fractionating the particulate components bonded in different ways using a sequential extraction procedure, and (2) to determine the amounts of radiocesium newly added to paddy fields in irrigation water relative to the amounts of radiocesium already present in the fields from the deposition of atmospheric fallout immediately after the FDNPP accident. Three catchments were studied, and the (137)Cs activity concentrations in stream water samples were 79-198 mBq L(-1) under stable runoff conditions and 702-13,400 Bq L(-1) under storm runoff conditions. The residual fraction (F4, considered to be non-bioavailable) was dominant, accounting for 59.5-82.6% of the total (137)Cs activity under stable runoff conditions and 69.4-95.1% under storm runoff conditions. The (137)Cs newly added to paddy fields in irrigation water only contributed 0.03-0.05% of the amount already present in the soil (201-348 kBq m(-2)). This indicates that the (137)Cs inflow load in irrigation water is negligible compared with that already in the soil. However, the contribution from the potentially bioavailable fractions (F1+F2+F3) was one order of magnitude larger, accounting for 0.20-0.59%. The increase in the dissolved and soluble radiocesium fraction (F1) was especially large (3.0% to infinity), suggesting that radiocesium migration in irrigation water is increasing the accumulation of radiocesium in rice. PMID:24602909

Yoshikawa, Natsuki; Obara, Hitomi; Ogasa, Marie; Miyazu, Susumu; Harada, Naoki; Nonaka, Masanori

2014-05-15

20

Comparative environmental analyses of paddy fields in two lake catchment areas: Lake Taihu, China and Lake Biwa, Japan  

Microsoft Academic Search

Eutrophication in Taihu Lake has become a serious environmental problem. In this paper, environmental conditions in paddy fields in Taihu Lake's catchment area were compared with those in Lake Biwa's catchment area, which revealed issues on social development at different stages and raised questions over restoration of Taihu Lake from an environmental sociology perspective. Keywords-lake; eutrophication; paddy field; non-point source;

Yang Ping; Zhu Wei; Tan Xiao

2011-01-01

21

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

NASA Astrophysics Data System (ADS)

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.

Sander, Till; Gerke, Horst H.

2009-02-01

22

Assessment of land-use impact on streamflow via a grid-based modelling approach including paddy fields  

NASA Astrophysics Data System (ADS)

To investigate the hydrologic impacts of land-use changes on streamflow for an urbanizing watershed with paddy fields, a grid-based daily hydrologic model was adopted. The model was calibrated with two years (2000-2001) of observed streamflow data and validated using 5 months (2001) of measured soil moisture data and 1 year (2002) of observed streamflow data. After the model was tested, it was run to estimate impacts of urbanization on each hydrologic component with the land-use data sets for 1986, 1994, and 2002 generated from Landsat TM satellite images. Total runoff increased from 41.4% (1986) to 44.9% (2002) for a 5.4% increase in urban area, implying that direct runoff increase exceeded baseflow decrease. Urbanization affected the proportions of direct runoff for each land-use category more than the change in total runoff and the ratio of direct runoff to total runoff. The change proportions in direct runoff for urban areas, paddy fields, and forest were 14.3%, -9.8% and -6.7% respectively for a 5.4% increase, 4.6% decrease and 3.4% decrease in each land-use area respectively. The results indicate that paddy fields play an important role in runoff regulation, and the evaluation method can assist regional policy makers in developing land management strategies that minimize hydrologic impacts on streamflow. Copyright

Kim, Seong Joon; Kwon, Hyung Joong; Park, Geun Ae; Lee, Mi Seon

2005-12-01

23

Estimation of soil moisture in paddy field using Artificial Neural Networks  

E-print Network

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...

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

2013-01-01

24

Populations of methanogenic bacteria in paddy field soil under double cropping conditions (rice-wheat)  

Microsoft Academic Search

The methanogenic populations able to use H2-CO2, methanol, and acetate were investigated in paddy field soil in situ under double cropping conditions [rice (Oryza sativa L.) as a summer crop under flooded conditions and wheat (Triticum aestivum L.) as an upland winter crop] over 2 years approximately bimonthly by the most probable number method. Three fields, one without fertilizer, one

S. Asakawa; K. Hayano

1995-01-01

25

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

NASA Astrophysics Data System (ADS)

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.

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

26

Responses of seasonal and diurnal soil CO2 effluxes to land-use change from paddy fields to Lei bamboo (Phyllostachys praecox) stands  

NASA Astrophysics Data System (ADS)

Land-use change often markedly alters soil carbon (C) dynamics such as soil surface CO2 efflux. This study aims to test the hypotheses that converting paddy fields to bamboo stands would markedly reduce soil CO2 efflux and their temperature sensitivity (change of soil CO2 efflux rate by increasing 10 °C of temperature), and change the relationship between soil CO2 efflux and other environmental factors. A 12-month field study was conducted to measure the seasonal and diurnal soil CO2 effluxes in three adjacent paddy field-bamboo forest pairs with the automated soil CO2 flux system (LI-8100). Results showed that soil CO2 effluxes from both of the two land-uses had distinct seasonal patterns, and were reduced from 45.4 to 34.7 t CO2 ha-1 yr-1 in cumulative CO2 emissions when paddy fields were converted to bamboo stands. About 80% of the variation in soil respiration in the bamboo stands was explained by soil temperature; however, a positive relationship between soil CO2 efflux and soil temperature in the paddy field was observed only when the soil was not submerged under water, indicating that soil water saturation in the paddy fields altered the soil CO2 efflux-temperature relationship. A negative relationship (P < 0.01) between soil CO2 efflux and soil moisture was observed in the paddy fields, while no such relationship was observed in the bamboo stands. The apparent temperature sensitivity of soil respiration (Q10) was dependent on the depth of the soil temperature measurement and was increased by converting paddy fields to bamboo stands, rejecting the hypothesis. In Lei bamboo stands, the R2 for the soil respiration-temperature regression was higher using seasonal and diurnal CO2 efflux data together than using the seasonal data alone. We conclude that the conversion of paddy fields to Lei bamboo stands decreased the annual soil CO2 efflux but increased its temperature sensitivity, and altered the relationship between soil respiration and soil moisture. When calculating the Q10, the soil temperature measurement depth and data with diurnal timescale should be taken into account. If such land-use conversion effects are confirmed over the subtropical region in China in future research, this land-use conversion could increase C sequestration in the ecosystem and help mitigate climate change.

Zhang, Tao; Li, Yongfu; Chang, Scott X.; Jiang, Peikun; Zhou, Guomo; Zhang, Jiaojiao; Liu, Juan

2013-10-01

27

Microbial electricity generation in rice paddy fields: recent advances and perspectives in rhizosphere microbial fuel cells.  

PubMed

Microbial fuel cells (MFCs) are devices that use living microbes for the conversion of organic matter into electricity. MFC systems can be applied to the generation of electricity at water/sediment interfaces in the environment, such as bay areas, wetlands, and rice paddy fields. Using these systems, electricity generation in paddy fields as high as ?80 mW m(-2) (based on the projected anode area) has been demonstrated, and evidence suggests that rhizosphere microbes preferentially utilize organic exudates from rice roots for generating electricity. Phylogenetic and metagenomic analyses have been conducted to identify the microbial species and catabolic pathways that are involved in the conversion of root exudates into electricity, suggesting the importance of syntrophic interactions. In parallel, pot cultures of rice and other aquatic plants have been used for rhizosphere MFC experiments under controlled laboratory conditions. The findings from these studies have demonstrated the potential of electricity generation for mitigating methane emission from the rhizosphere. Notably, however, the presence of large amounts of organics in the rhizosphere drastically reduces the effect of electricity generation on methane production. Further studies are necessary to evaluate the potential of these systems for mitigating methane emission from rice paddy fields. We suggest that paddy-field MFCs represent a promising approach for harvesting latent energy of the natural world. PMID:25394406

Kouzuma, Atsushi; Kaku, Nobuo; Watanabe, Kazuya

2014-12-01

28

[Dynamic simulation of ammonia- and nitrate N leakage from paddy field under different N supply].  

PubMed

By using self-designed lysimeters, the dynamic changes of ammonia- and nitrate N leakage from the plowpan of paddy field under different N supply were studied, aimed to understand the N leakage loss from paddy field during rice growth period. A dynamic model was built to simulate the N translocation and transformation in rice plant, soil, and water by Vensim software. The data from the field experiment with N fertilization rates of 0, 75, 150, 225, 300, and 375 kg x hm(-2) in Yuhang district, Hangzhou City in 2003 were used for calibrating the model, and the data from the field experiment in 2007 were utilized for validating the model. The simulated N concentrations in the leakage fitted well with the observed data, suggesting that the simulated results were reliable and the model was applicable. PMID:19795646

Li, Jin-Wen; Zhong, Sheng; Wang, Mi; Yang, Jing-Ping; Xu, Wei

2009-06-01

29

Arsenic from Groundwater to Paddy Fields in Bangladesh: Solid–Liquid Partition, Sorption and Mobility  

Microsoft Academic Search

The arsenic contamination of Bangladesh groundwater involves heavy arsenic inputs to irrigated rice fields. Beside adsorption\\u000a on soil colloids, iron–arsenic co-precipitation phenomena can affect arsenic retention in soils. In paddy fields of Satkhira\\u000a District, Bangladesh, the study of the arsenic and iron forms in the irrigation waters and in soils at different times and\\u000a distances from the irrigation well evidenced

Maria Martin; Rakiba Ferdousi; K. M. Jakeer Hossain; Elisabetta Barberis

2010-01-01

30

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

Microsoft Academic Search

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

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

2011-01-01

31

Influence of biochar amendment on greenhouse gases emission and rice production in paddy field, China  

NASA Astrophysics Data System (ADS)

Biochar incorporating into agricultural soils as a strategy to increase soil carbon content and mitigate climate change received great attention. We present a field study about biochar amendment into paddy field in Sichuan province 2010, China. The objective was to evaluate the impacts of biochar incorporation on rice production and greenhouse gas emissions. Biochar used in this study was produced from wheat straw at temperature 350-550°C. Biochar incorporated into paddy field before rice transplanting. Methane (CH4), nitrous oxide (N2O) and carbon dioxide (CO2) fluxes were measured in situ using closed chamber method during whole rice growing season. Flux of greenhouse gases was monitored at about 7 day's interval. Two rates of N fertilizer (0 and 240 kg N/ha) were applied as urea in combination with 3 biochar rates (0, 20 and 40 t/ha). Amendment of biochar had no influence on rice yield even at the hightest rate of 40 t/ha. However, rice production was greatly relying on chemical N fertilization input. No interact effect was detected between biochar and N fertilizer. Amendment of biochar suppressed N2O emission. During the whole rice growing season, the total N2O emission from chemical fertilizer was reduce by 29% and 53% under biochar amendment rates of 20t/ha and 40t/ha respectively. Total amounts of CO2 and CH4 emitted from paddy fields during whole rice growing season were not greatly increased despite of much carbon brought into soil with biochar. However, biochar amendment slightly increased CO2 emission in the absence of N fertilizer. Our results showed that biochar amendment into paddy field did not increase the global warming potential (GPW) and greenhouse gases emission intensity (GHGI).

Liu, X.; Pan, G. X.; Li, L. Q.; Zhou, T.

2012-04-01

32

Bacterial community in plant residues in a Japanese paddy field estimated by RFLP and DGGE analyses  

Microsoft Academic Search

Plant residues (PRs) are “hot spots” of microbial activities in soil. PRs with the size more than 0.5mm were collected from a Japanese paddy field during rice cultivation period (from May to September) and fractionated into four categories by size (>4, 2–4, 1–2, and 0.5–1mm) using sieves. Restriction fragment length polymorphism (RFLP) and denaturing gradient gel electrophoresis (DGGE) patterns were

Tomoya Matsuyama; Yasunori Nakajima; Kazuo Matsuya; Makoto Ikenaga; Susumu Asakawa; Makoto Kimura

2007-01-01

33

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

NASA Astrophysics Data System (ADS)

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.

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

2013-04-01

34

Simulation of future global warming scenarios in rice paddies with an open-field warming facility  

PubMed Central

To simulate expected future global warming, hexagonal arrays of infrared heaters have previously been used to warm open-field canopies of upland crops such as wheat. Through the use of concrete-anchored posts, improved software, overhead wires, extensive grounding, and monitoring with a thermal camera, the technology was safely and reliably extended to paddy rice fields. The system maintained canopy temperature increases within 0.5°C of daytime and nighttime set-point differences of 1.3 and 2.7°C 67% of the time. PMID:22145582

2011-01-01

35

Seasonal trends and environmental controls of methane emissions in a rice paddy field in Northern Italy  

NASA Astrophysics Data System (ADS)

Rice paddy fields are one of the greatest anthropogenic sources of methane (CH4), the third most important greenhouse gas after water vapour and carbon dioxide. In agricultural fields, CH4 is usually measured with the closed chamber technique, resulting in discontinuous series of measurements performed over a limited area, that generally do not provide sufficient information on the short-term variation of the fluxes. On the contrary, aerodynamic techniques have been rarely applied for the measurement of CH4 fluxes in rice paddy fields. The eddy covariance (EC) technique provides integrated continuous measurements over a large area and may increase our understanding of the underlying processes and diurnal and seasonal pattern of CH4 emissions in this ecosystem. For this purpose a Fast Methane Analyzer (Los Gatos Research Ltd.) was installed in a rice paddy field in the Po Valley (Northern Italy). Methane fluxes were measured during the rice growing season with both EC and manually operated closed chambers. Methane fluxes were strongly influenced by the height of the water table, with emissions peaking when it was above 10-12 cm. Soil temperature and the developmental stage of rice plants were also responsible of the seasonal variation on the fluxes. The measured EC fluxes showed a diurnal cycle in the emissions, which was more relevant during the vegetative period, and with CH4 emissions being higher in the late evening, possibly associated with higher water temperature. The comparison between the two measurement techniques shows that greater fluxes are measured with the chambers, especially when higher fluxes are being produced, resulting in 30 % higher seasonal estimations with the chambers than with the EC (41.1 and 31.7 g CH4 m-2 measured with chambers and EC respectively) and even greater differences are found if shorter periods with high chamber sampling frequency are compared. The differences may be a result of the combined effect of overestimation with the chambers and of the possible underestimation by the EC technique.

Meijide, A.; Manca, G.; Goded, I.; Magliulo, V.; di Tommasi, P.; Seufert, G.; Cescatti, A.

2011-12-01

36

Modeling of Movement of Field Gudgeon, Gnathopogon elongatus elongatus, in Agricultural Canals in Yatsu Paddy Fields  

NASA Astrophysics Data System (ADS)

It is important as quantitative information for making a decision of project sites for networking of water area, to predict reproductive process of fish population when consolidating fish-ways on points dividing fish habitat. To that end, it is necessary to predict the number of individuals migrating to new habitats. Hence, modeling of movement of individuals is necessary as a first step in population modeling. We constructed a mathematical model of movement of field gudgeon in agricultural canals, comparing with observed data obtained by our surveys. A unit time span of this model is 50 days. This model is able to consider existence of 2 types of movement, namely, individuals of sedentary type and individuals of ambulant type. Parameters of the model were decided based on observed data which correspond to 1 unit span. Next, moving distances of 6 individuals for 4 unit span were calculated using those parameters. A histogram of calculated values was similar to that of observed data which correspond to 4 unit span. The model is expected to provide an important immigration component to a population dynamics model which is currently under development. The population model is needed to predict population recovery processes where areas of paddy fields are joined in larger networks through construction of fish-ways.

Takemura, Takeshi; Koizumi, Noriyuki; Mizutani, Masakazu; Mori, Atsushi; Watabe, Keiji

37

[Quantifying direct N2O emissions from paddy fields during rice growing season in China: model establishment].  

PubMed

Various water management regimes, such as continuous flooding (F), flooding-midseason drainage-reflooding (F-D-F), and flooding-midseason drainage-reflooding-moist intermittent irrigation but without water logging (F-D-F-M), are currently practiced in paddy rice production in China. These water regimes have incurred a sensitive change in direct N2O emission from rice paddy fields. In order to establish statistical models quantifying the country-specific emission factor and background emission of N2O in paddy fields during the rice growing season, we compiled and statistically analyzed field data on 71 N2O measurements from 17 field studies that were published in peer-reviewed Chinese and English journals. For each field study, we documented the seasonal N2O emission, the type and amount of organic amendment and fertilizer nitrogen application, the water management regime, the drainage duration, the field location and cropping season. Seasonal total N2O was, on average, equivalent to 0.02% of the nitrogen applied in the continuous flooding rice paddies. Under the water regime of F-D-F or the F-D-F-M, seasonal N2O emissions increased with N fertilizer applied in rice paddies. Applying an Ordinary Least Square (OLS) linear regression model resulted in an emission factor of 0.42% for N2O, and in unpronounced background N2 O emission under the water regime of F-D-F. Under the F-D-F-M water regime, N2O emission factor and N2O-N background emission were estimated to be 0.73% and 0.79 kg x hm(-2) during the paddy rice growing season, respectively. After considering three different water regimes in rice paddies in China, the emission factor of N for N2O and N2O-N background emission averaged 0.54% and 0.43 kg x hm(-2). The results of this study suggest that paddy rice relative to upland crop production could have contributed to mitigating N2O emissions from agriculture in China. The emission factor of N for N2O and its background emissions can be directly adopted to develop national inventory of N2O emissions from paddy fields during the rice growing season in China. PMID:19402475

Zou, Jian-Wen; Qin, Yan-Mei; Liu, Shu-Wei

2009-02-15

38

Effects of "open burning" on the greenhouse gas exchange from a single-rice paddy field in Japan  

NASA Astrophysics Data System (ADS)

Paddy fields are artificially maintained wetland and are one of the large source of CH4. Besides, a large quantity of N2O is emitted from the soil surface due to the decomposition of inorganic fertilizer. A long term continuous measurement of GHG fluxes between atmosphere and paddy ecosystem is effective method to clarify the contribution of paddy fields to recent rapid increase of GHG concentration. In this study, three techniques for flux measurement (eddy covariance, aerodynamic gradient, and chamber techniques) were applied to investigate the annual variation of three GHG (CO2, CH4 and N2O) exchanges at a single-rice paddy field for two years. An observational site is located on reclaimed land in the southern part of Okayama Prefecture, Japan. In addition, an experimental paddy field was divided into two areas to investigate what impact is brought on the annual GHG fluxes by the difference of disposal management of residual biomass after the harvest. Residual biomass was burned and plowed into soil at the one area on Nov. 29th, 2011, and residue was not burned and directly plowed into soil at the other area as usual. We illustrate some results for the control term before the burning experiment, and for the comparison term after the experiment.

Kawamoto, Y.; Akaike, Y.; Kunishio, A.; Murakami, H.; Ono, K.; Hayashi, K.; Iwata, T.

2012-12-01

39

Comparative Metagenomics of Anode-Associated Microbiomes Developed in Rice Paddy-Field Microbial Fuel Cells  

PubMed Central

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

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

2013-01-01

40

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

PubMed

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

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

2013-01-01

41

Difference in cesium accumulation among rice cultivars grown in the paddy field in Fukushima Prefecture in 2011 and 2012.  

PubMed

After the accident of the Fukushima 1 Nuclear Power Plant in March 2011, radioactive cesium was released and paddy fields in a wide area including Fukushima Prefecture were contaminated. To estimate the levels of radioactive Cs accumulation in rice produced in Fukushima, it is crucial to obtain the actual data of Cs accumulation levels in rice plants grown in the actual paddy field in Fukushima City. We herein conducted a two-year survey in 2011 and 2012 of radioactive and non-radioactive Cs accumulation in rice using a number of rice cultivars grown in the paddy field in Fukushima City. Our study demonstrated a substantial variation in Cs accumulation levels among the cultivars of rice. PMID:24338062

Ohmori, Yoshihiro; Inui, Yayoi; Kajikawa, Masataka; Nakata, Atsumi; Sotta, Naoyuki; Kasai, Koji; Uraguchi, Shimpei; Tanaka, Nobuhiro; Nishida, Sho; Hasegawa, Takahiro; Sakamoto, Takuya; Kawara, Yuko; Aizawa, Kayoko; Fujita, Haruka; Li, Ke; Sawaki, Naoya; Oda, Koshiro; Futagoishi, Ryuichiro; Tsusaka, Takahiro; Takahashi, Satomi; Takano, Junpei; Wakuta, Shinji; Yoshinari, Akira; Uehara, Masataka; Takada, Shigeki; Nagano, Hayato; Miwa, Kyoko; Aibara, Izumi; Ojima, Takuya; Ebana, Kaoru; Ishikawa, Satoru; Sueyoshi, Kuni; Hasegawa, Hiroshi; Mimura, Tetsuro; Mimura, Mari; Kobayashi, Natsuko I; Furukawa, Jun; Kobayashi, Daisuke; Okouchi, Toshiyasu; Tanoi, Keitaro; Fujiwara, Toru

2014-01-01

42

Improving water management practices to reduce nutrient export from rice paddy fields.  

PubMed

Nitrogen (N) and phosphorus (P) loss from rice paddy fields represents a significant threat to water quality in China. In this project, three irrigation-drainage regimes were compared, including one conventional irrigation-drainage regime, i.e. continuous submergence regime (CSR), and two improved regimes, i.e. the alternating submergence-nonsubmergence regime (ASNR) and the zero-drainage irrigation technology (ZDIT), to seek cost-effective practices for reducing nutrient loss. The data from these comparisons showed that, excluding the nutrient input from irrigation, the net exports of total N and total P via surface field drainage ranged from -3.93 to 2.39 kg ha and 0.17 to 0.95 g ha(-1) under the CSR operation, respectively, while N loss was -2.46 to -2.23 kg ha(-1) and P export was -0.65 to 0.31 kg ha(-1) under the improved regimes. The intensity of P export was positively correlated to the rate of P application. Reducing the draining frequency or postponing the draining operation would shift the ecological role of the paddy field from a nutrient export source to an interception sink when ASNR or the zero-drainage water management was used. In addition, since the rice yields are being guaranteed at no additional cost, the improved irrigation-drainage operations would have economic as well as environmental benefits. PMID:21473282

Zhang, Zhi-Jian; Yao, Ju-Xiang; Wang, Zhao-De; Xu, Xin; Lin, Xian-Yong; Czapar, George F; Zhang, Jian-Ying

2011-01-01

43

High abundance and diversity of nitrite-dependent anaerobic methane-oxidizing bacteria in a paddy field profile.  

PubMed

The discovery of nitrite-dependent anaerobic methane oxidation (n-damo) mediated by 'Candidatus Methylomirabilis oxyfera' with nitrite and methane as substrates has connected biogeochemical carbon and nitrogen cycles in a new way. The paddy fields often carry substantial methane and nitrate, thus may be a favorable habitat for n-damo bacteria. In this paper, the vertical-temporal molecular fingerprints of M. oxyfera-like bacteria, including abundance and community composition, were investigated in a paddy soil core in Jiangyin, near the Yangtze River. Through qPCR investigation, high abundance of M. oxyfera-like bacteria up to 1.0 × 10(8) copies (g d.w.s.)(-1) in summer and 8.5 × 10(7) copies (g d.w.s.)(-1) in winter was observed in the ecotone of soil and groundwater in the paddy soil core, which was the highest in natural environments to our knowledge. In the ecotone, the ratio of M. oxyfera-like bacteria to total bacteria reached peak values of 2.80% in summer and 4.41% in winter. Phylogenetic analysis showed n-damo bacteria in the paddy soil were closely related to M. oxyfera and had high diversity in the soil/groundwater ecotone. All of the results indicated the soil/groundwater ecotone of the Jiangyin paddy field was a favorable environment for the growth of n-damo bacteria. PMID:25109910

Zhou, Leiliu; Wang, Yu; Long, Xi-En; Guo, Jianhua; Zhu, Guibing

2014-11-01

44

Dry deposition velocity of sulfur dioxide over rice paddy in the tropical region  

NASA Astrophysics Data System (ADS)

The SO 2 deposition velocity over a canopy of irrigated rice paddy in a tropical area was evaluated using the Bowen ratio and Fick's equations. The experimental facilities were set up in Chachoengsao province in the central region of Thailand and data was collected for a period of one year. The results showed that the deposition velocity of SO 2 varies with the time of day, and it was highest around noon time and lowest at night. Furthermore, the value for the seasonal average of Vd was the highest in winter and the lowest in the rainy season. The obtained seasonal average values of Vd were 0.67, 1.25, and 1.51 cm/s in the winter, summer, and rainy seasons, respectively.

Jitto, P.; Vinitnantarat, S.; Khummongkol, P.

2007-07-01

45

Seasonal trends and environmental controls of methane emissions in a rice paddy field in Northern Italy  

NASA Astrophysics Data System (ADS)

Rice paddy fields are one of the greatest anthropogenic sources of methane (CH4), the third most important greenhouse gas after water vapour and carbon dioxide. In agricultural fields, CH4 is usually measured with the closed chamber technique, resulting in discontinuous series of measurements performed over a limited area, that generally do not provide sufficient information on the short-term variation of the fluxes. On the contrary, aerodynamic techniques have been rarely applied for the measurement of CH4 fluxes in rice paddy fields. The eddy covariance (EC) technique provides integrated continuous measurements over a large area and may increase our understanding of the underlying processes and diurnal and seasonal pattern of CH4 emissions in this ecosystem. For this purpose a Fast Methane Analyzer (Los Gatos Research Ltd.) was installed in an eddy-covariance field set-up in a rice paddy field in the Po Valley (Northern Italy). Methane fluxes were measured during the rice growing season, both with EC and with manually operated closed chambers. Methane fluxes were strongly influenced by the presence of the water table, with emissions peaking when it was above 10-12 cm. Further studies are required to evaluate if water table management could decrease CH4 emissions. The development of rice plants and soil temperature were also responsible of the seasonal variation on the fluxes. The EC measured showed a diurnal cycle in the emissions, which was more relevant during the vegetative period, and with CH4 emissions being higher in the late evening, possibly associated with higher water temperature. The comparison between both measurement techniques shows that greater fluxes are measured with the chambers, especially when higher fluxes are being produced, resulting in 30 % higher seasonal estimations with the chambers than with the EC (41.1 and 31.8 g CH4 m-2 measured with chambers and EC respectively). The differences may be a result of the combined effect of overestimation with the chambers, the possible underestimation by the EC technique and of not having considered the daily course of the fluxes for the calculation of seasonal emissions from chambers.

Meijide, A.; Manca, G.; Goded, I.; Magliulo, V.; di Tommasi, P.; Seufert, G.; Cescatti, A.

2011-09-01

46

?????????????????????????????????????????????????????????????????????????????????????????? EFFECT OF MIXED NITROGEN FERTILIZER ON CARBON SEQUESTRATION OF SOME PHOTO-INSENSITIVE RICE VARIETIES IN PADDY FIELD, PATHUM  

Microsoft Academic Search

This research studied regarding the carbon sequestration growing the photo- insensitive in the irrigated paddy fields within the central plain. In the sample mixed nitrogen fertilizers content were applied. The samples were collected during growth stages. The evaluation of carbon contents in the plants was done from the biomass. In addition, carbon contents in soils were studied in soil organic

THANI PROVINCE; Nuanchan Eaimpraphan; Charlie Navanugraha

47

Studies on the bacteria isolated anaerobically from paddy field soil III. Production of fatty acids and ammonia by Clostridium species  

Microsoft Academic Search

The volatile fatty acids produced by the representative strains of clostridia isolated from paddy field soil were surveyed. All the strains, except Cl. tertium, utilized only amino acids as the sole source of energy for growth. All of them produced acetic and butyric acids, and some of them produced propionic acid in addition. Iso-valeric and iso-butyric acids were also produced,

Kiyoshi Takeda; Choseki Furusaka

1975-01-01

48

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

USGS Publications Warehouse

Butachlor is the most commonly used herbicide on paddy fields in Taiwan and throughout Southeast Asia. Since paddy fields provide habitat for pond breeding amphibians, we examined growth, development, time to metamorphosis, and survival of alpine cricket frog tadpoles (Fejervarya limnocharis) exposed to environmentally realistic concentrations of butachlor. We documented negative impacts of butachlor on survival, development, and time to metamorphosis, but not on tadpole growth. The 96 h LC50 for tadpoles was 0.87 mg/l, much lower than the 4.8 mg/l recommended dosage for application to paddy fields. Even given the rapid breakdown of butachlor, tadpoles would be exposed to concentrations in excess of their 96 h LC50 for an estimated 126 h. We also documented DNA damage (genotoxicity) in tadpoles exposed to butachlor at concentrations an order of magnitude less than the 4.8 mg/l recommended application rate. We did not find that butachlor depressed cholinesterase activity of tadpoles, unlike most organophosphorus insecticides. We conclude that butachlor is likely to have widespread negative impacts on amphibians occupying paddy fields with traditional herbicide application.

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

2011-01-01

49

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

PubMed Central

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

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

2012-01-01

50

Response of CH4 emission of paddy fields to land management practices at a microcosmic cultivation scale in China.  

PubMed

The terrestrial ecosystem may be either a source or a sink of CH4 in rice paddies, depending, to a great extent, on the change of ecosystem types and land use patterns. CH4 emission fluxes from paddy fields under 4 cultivation patterns (conventional plain culture of rice (T1), no-tillage and ridge culture of rice (T2), no-tillage and ridge culture of rice and wheat (T3), and rice-wheat rotation (T4)) were measured with the closed chamber technique in 1996 and 1998 in Chongqing, China. The results showed that differences existed in CH4 emission from paddy fields under these land management practices. In 1996 and 1998, CH4 emission was 71.48% and 78.82% (T2), 65.93% and 57.18% (T3), and 61.53% and 34.22% (T4) of that in T1 during the rice growing season. During the non-rice growing season, CH4 emission from rice fields was 76.23% in T2 and 38.69% in TI. The accumulated annual CH4 emission in T2, T3 and T4 in 1996 decreased by 33.53%, 63.30% and 65.73%, respectively, as compared with that in T1. In 1998, the accumulated annual CH4 emission in T1, T2, T3 and T4 was 116.96 g/m2, 68.44 g/m2, 19.70 g/m2 and 11.80 g/m2, respectively. Changes in soil physical and chemical properties, in thermal and moisture conditions in the soil and in rice plant growth induced by different land use patterns were the dominant causes for the difference in CH4 emission observed. The relative contribution of various influencing factors to CH4 emission from paddy fields differed significantly under different land use patterns. However, the general trend was that chlorophyll content in rice leaves, air temperature and temperature at the 5 cm soil layer play a major role in CH4 emission from paddy fields and the effects of illumination, relative humidity and water layer depth in the paddy field and CH4 concentration in the crop canopy were relatively non-significant. Such conservative land use patterns as no-tillage and ridge culture of rice with or without rotation with wheat are thought to be beneficial to reducing CH4 emission from paddy fields and are, therefore, recommended as a significant solution to the problems of global (climatic) change. PMID:16158607

Shao, Jing-An; Huang, Xue-Xi; Gao, Ming; Wei, Chao-Fu; Xie, De-Ti; Cai, Zu-Cong

2005-01-01

51

[Controlling effects of multiple species coexistence on rice diseases, pests and weeds in paddy field ecosystem].  

PubMed

Establishing a species-diversified cropping system to control crop diseases, insect pests and weeds is an important approach to sustainable agricultural development. This paper reviewed the researches on paddy field species-diversified cropping systems at home and abroad, and discussed the controlling effects and mechanisms of multiple species coexistence on rice diseases, pests and weeds control. The multiple species coexistence models such as rice-fish, rice-duck, rice-azolla-fish and rice-azolla-duck had effective controlling effects on Thanatephorus cucumeris (Frank) Donk, Nilaparata lugens Stal, Chaphalocrocis medinalis Gueneeand, and weeds. Other models like intercropping rice with Zizania caduciflora L. and with other wetland crops also had effective effects in controlling the occurrence and spread of Pyricularia grisea. It was suggested that further studies should be strengthened from the viewpoints of crop culture, molecular biology, and chemical ecolo- PMID:17650871

Wang, Han; Tang, Jian-jun; Xie, Jian; Chen, Xin

2007-05-01

52

From Laboratory to Field: OsNRAMP5-Knockdown Rice Is a Promising Candidate for Cd Phytoremediation in Paddy Fields  

PubMed Central

Previously, we reported that OsNRAMP5 functions as a manganese, iron, and cadmium (Cd) transporter. The shoot Cd content in OsNRAMP5 RNAi plants was higher than that in wild-type (WT) plants, whereas the total Cd content (roots plus shoots) was lower. For efficient Cd phytoremediation, we produced OsNRAMP5 RNAi plants using the natural high Cd-accumulating cultivar Anjana Dhan (A5i). Using a positron-emitting tracer imaging system, we assessed the time-course of Cd absorption and accumulation in A5i plants. Enhanced 107Cd translocation from the roots to the shoots was observed in A5i plants. To evaluate the phytoremediation capability of A5i plants, we performed a field experiment in a Cd-contaminated paddy field. The biomass of the A5i plants was unchanged by the suppression of OsNRAMP5 expression; the A5i plants accumulated twice as much Cd in their shoots as WT plants. Thus, A5i plants could be used for rapid Cd extraction and the efficient phytoremediation of Cd from paddy fields, leading to safer food production. PMID:24901230

Bashir, Khurram; Senoura, Takeshi; Sugimoto, Kazuhiko; Ono, Kazuko; Suzui, Nobuo; Kawachi, Naoki; Ishii, Satomi; Yin, Yong-Gen; Fujimaki, Shu; Yano, Masahiro; Nishizawa, Naoko K.; Nakanishi, Hiromi

2014-01-01

53

Radiocesium discharge from paddy fields with different initial scrapings for decontamination after the Fukushima Dai-ichi Nuclear Power Plant accident.  

PubMed

To explore the behavior of radionuclides released after the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident in March 2011, and the distribution of radiocesium in paddy fields, we monitored radiocesium (Cs) and suspended sediment (SS) discharge from paddy fields. We proposed a rating scale for measuring the effectiveness of surface soil removal. Our experimental plots in paddy fields were located ?40 km from the FDNPP. Two plots were established: one in a paddy field where surface soil was not removed (the "normally cultivated paddy field") and the second in a paddy field where the top 5-10 cm of soil was removed before cultivation (the "surface-removed paddy field"). The amounts of Cs and SS discharge from the paddy fields were continuously measured from June to August 2011. The Cs soil inventory measured 3 months after the FDNPP accident was approximately 200 kBq m(-2). However, after removing the surface soil, the concentration of Cs-137 decreased to 5 kBq m(-2). SS discharged from the normally cultivated and surface-removed paddy fields after puddling (mixing of soil and water before planting rice) was 11.0 kg and 3.1 kg, respectively, and Cs-137 discharge was 630?000 Bq (1240 Bq m(-2)) and 24?800 Bq (47.8 Bq m(-2)), respectively. The total amount of SS discharge after irrigation (natural rainfall-runoff) was 5.5 kg for the normally cultivated field and 70 kg for the surface-removed field, and the total amounts of Cs-137 discharge were 51?900 Bq (102 Bq m(-2)) and 165?000 Bq (317 Bq m(-2)), respectively. During the irrigation period, discharge from the surface-removed plot showed a twofold greater inflow than that from the normally cultivated plot. Thus, Cs inflow may originate from the upper canal. The topsoil removal process eliminated at least approximately 95% of the Cs-137, but upstream water contaminated with Cs-137 flowed into the paddy field. Therefore, to accurately determine the Cs discharge, it is important to examine Cs inflow from the upper channel. Furthermore, puddling and irrigation processes inhibit the discharge of radiocesium downstream. This indicates that water control in paddy fields is an important process in the prevention of river pollution and radionuclide transfer. PMID:25247992

Wakahara, Taeko; Onda, Yuich; Kato, Hiroaki; Sakaguchi, Aya; Yoshimura, Kazuya

2014-10-20

54

Laboratory and field dissipation of penoxsulam, tricyclazole and profoxydim in rice paddy systems.  

PubMed

Rice cultivation relies on pesticide applications to ensure high yields. However, the regular use of pesticides seriously affects the quality of neighboring surface water systems. Thus complete knowledge of the environmental fate and dissipation of pesticides in the paddy rice environment should become available. So far only a few studies have provided comprehensive assessment of the dissipation of pesticides under the submerged cultivation conditions followed in rice. Thus, laboratory and 2-year field studies were performed to assess the dissipation of two new generation rice herbicides (penoxsulam and profoxydim) and one of the most important rice fungicides (tricyclazole). A good agreement between laboratory and field experiments was observed with a faster dissipation of penoxsulam and tricyclazole under field conditions. Profoxydim was the least persistent chemical (DT50 soil<1d; DT50 water 0.5-1.2d), followed by penoxsulam which persisted for longer particularly in the water compartment (DT50water=3.8-5.9d). Tricyclazole was the most persistent pesticide, especially in the soil compartment with DT50 values of 44.5-84.6 (field) and 197d (laboratory). These results could be utilized for the assessment of the environmental risk associated with the use of those pesticides in rice cultivation and the determination of potential mitigation measures for minimizing the risk for contamination of neighboring natural water resources. PMID:23507498

Tsochatzis, E D; Tzimou-Tsitouridou, R; Menkissoglu-Spiroudi, U; Karpouzas, D G; Katsantonis, D

2013-05-01

55

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

Microsoft Academic Search

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

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

2009-01-01

56

Nannophya pygmaea (Odonata: Libellulidae), an endangered dragonfly in Korea, prefers abandoned paddy fields in the early seral stage.  

PubMed

To characterize habitats of Nannophya pygmaea Rambur (the northern pygmyfly; Odonata: Lilbellulidae), which is endangered in Korea, we analyzed characteristics of surface water and soil, landscape properties, and vegetation types in 22 habitats in eight areas of Korea where nymphs of N. pygmaea have been found since 2005. We divided the habitats into two groups: DS (dwelling site) habitats, where N. pygmaea was observed at the time of the study, and PDS (past dwelling site) habitats, where N. pygmaea recently lived but is no longer found. The habitats were mostly located in former paddy fields on mountain slopes that have been abandoned for 3-7 yr. The main water sources for these habitats were ground water and surface runoff, and the water level was stable at 3-7 cm in depth. The habitats ranged from 300 to 1000 m(2) and were dominated by Juncus effusus, which formed tussock mounds. According to the hydrosere model of succession, N. pygmaea appeared mostly in the early stages of plant succession (the period approximately 3-7 yr after the initiation of succession in former paddy fields) and N. pygmaea preferred habitats displaying the water and soil characteristics that are typical of the early stages of succession in abandoned paddy fields. These results indicate that the primary habitats of N. pygmaea in Korea are recently abandoned paddy fields that are in an oligotrophic state. As succession proceeds in these habitats, N. pygmaea disappears. A habitat management program should be launched to conserve the habitats and populations of N. pygmaea. PMID:20388254

Yoon, Jihyun; Nam, Jong Min; Kim, Heungtae; Bae, Yeon Jae; Kim, Jae Geun

2010-04-01

57

Elevated Ground-Level O 3 Changes the Diversity of Anoxygenic Purple Phototrophic Bacteria in Paddy Field  

Microsoft Academic Search

The knowledge of the impact of elevated ground-level O3 below ground the agro-ecosystem is limited. A field experiment in China Ozone Free-Air Concentration Enrichment (FACE-O3) facility on a rice–wheat rotation system was carried out to investigate responses of anoxygenic phototrophic purple bacteria\\u000a (AnPPB) to elevated ground-level O3. AnPPB community structures and sizes in paddy soil were monitored by molecular approaches

Youzhi Feng; Xiangui Lin; Yongchang Yu; Jianguo Zhu

58

Influence of transgenic rice expressing a fused Cry1Ab/1Ac protein on frogs in paddy fields.  

PubMed

As genetic engineering in plants is increasingly used to control agricultural pests, it is important to determine whether such transgenic plants adversely affect non-target organisms within and around cultivated fields. The cry1Ab/1Ac fusion gene from Bacillus thuringiensis (Bt) has insecticidal activity and has been introduced into rice line Minghui 63 (MH63). We evaluated the effect of transgenic cry1Ab/1Ac rice (Huahui 1, HH1) on paddy frogs by comparing HH1 and MH63 rice paddies with and without pesticide treatment. The density of tadpoles in rice fields was surveyed at regular intervals, and Cry1Ab/1Ac protein levels were determined in tissues of tadpoles and froglets collected from the paddy fields. In addition, Rana nigromaculata froglets were raised in purse nets placed within these experimental plots. The survival, body weight, feeding habits, and histological characteristics of the digestive tract of these froglets were analyzed. We found that the tadpole density was significantly decreased immediately after pesticide application, and the weight of R. nigromaculata froglets of pesticide groups was significantly reduced compared with no pesticide treatment, but we found no differences between Bt and non-Bt rice groups. Moreover, no Cry1Ab/1Ac protein was detected in tissue samples collected from 192 tadpoles and froglets representing all four experimental groups. In addition, R. nigromaculata froglets raised in purse seines fed primarily on stem borer and non-target insects, and showed no obvious abnormality in the microstructure of their digestive tracts. Based on these results, we conclude that cultivation of transgenic cry1Ab/1Ac rice does not adversely affect paddy frogs. PMID:25129148

Wang, Jia-Mei; Chen, Xiu-Ping; Liang, Yu-Yong; Zhu, Hao-Jun; Ding, Jia-Tong; Peng, Yu-Fa

2014-11-01

59

Persistence of metsulfuron-methyl in paddy field and detection of its residues in crop produce.  

PubMed

Among sulfonylurea herbicides, metsulfuron-methyl [methyl 2-(4-methoxy-6-methyl-1,3,5-triazine-2-ylcarbamoylsulfamoyl) benzoic acid] is widely used due to its selectivity against a wide range of weeds in cereal, pasture, and plantation crops. Use of persistent herbicides has increased risk of accumulation of residues in soil, groundwater, crop produce, food chain etc. Thus an experiment was conducted to see persistence of metsulfuron-methyl in paddy field under tropical conditions. Metsulfuron-methyl was applied at 2, 4, 5, and 8 a.i. g ha?1 rates after 25 days in transplanted rice as post emergence herbicide. Concentration of metsulfuron-methyl in soil at 30 days was found 0.008, 0.010, 0.011 and 0.016 ?g g?1 at 2, 4, 5 and 8 g a.i. ha?1 application rates, respectively. However, residue level of metsulfuron-methyl in soil, rice grains and straw at harvest was found below 0.001 ?g g?1. PMID:19609477

Sondhia, Shobha

2009-12-01

60

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

PubMed

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

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

2014-04-01

61

Paludibacter jiangxiensis sp. nov., a strictly anaerobic, propionate-producing bacterium isolated from rice paddy field.  

PubMed

A mesophilic, obligately anaerobic, propionate-producing fermentative bacterium, designated strain NM7(T), was isolated from rural rice paddy field. Cells of strain NM7(T) are Gram-negative, non-motile, non-spore-forming, short rods, and negative for catalase. The strain grew optimally at 37 °C (the range for growth 15-40 °C) and pH 7.0 (pH 5.0-7.5). The strain could grow fermentatively on various sugars, including arabinose, xylose, fructose, galactose, glucose, mannose, cellobiose, lactose, maltose, sucrose, pectin and starch. The main end products of glucose fermentation were acetate and propionate. Yeast extract was not required but stimulated the growth. Nitrate, sulfate, thiosulfate, elemental sulfur, sulfite, and Fe(III) nitrilotriacetate were not used as terminal electron acceptors. The G+C content of genomic DNA was 42.8 mol%. The major cellular fatty acids were C15:0, anteiso-C15:0, C16:0, and C17:0. The most abundant polar lipid of strain NM7(T) was phosphatidylethanolamine. 16S rRNA gene sequence analysis revealed that it belongs to the family Porphyromonadaceae of the phylum Bacteroidetes. The closest recognized species was Paludibacter propionicigenes (91.4 % similarity in 16S rRNA gene sequence). A novel species, Paludibacter jiangxiensis sp. nov., is proposed to accommodate strain NM7(T) (=JCM 17480(T) = CGMCC 1.5150(T) = KCTC 5844(T)). PMID:24419224

Qiu, Yan-Ling; Kuang, Xiao-Zhu; Shi, Xiao-Shuang; Yuan, Xian-Zheng; Guo, Rong-Bo

2014-03-01

62

Spatial and Temporal Variability of Macronutrients in a Lime-amended Acid Paddy Field  

NASA Astrophysics Data System (ADS)

Soil spatial variability is a natural occurring and or management induced feature that is important for site-specific management practices such as variable rate fertilization. Since rice paddy fields are flat and flooded, apparently they should be homogeneous and subsequently it could be thought that spatial variability in yields and soil attributes might be negligible. However, significant levels of variability in soil general properties, soil nutrients and rice yields have been observed even in small paddy fields. Describing spatial variability of within-field properties is a fundamental first step toward determining management strategies. The aim of this study was to analyze patterns of spatial variability in available macronutrients (NH4+-N, P and K) from an acid rice soil submitted to lime amendment. The experimental site was located at Corrientes province, Argentina. The climate is warm, subtropical with abundant rainfall the whole year round. The study soil was typic Plintacualf. Field trials were set up involving three treatments: control, without lime addition, plus two different dolomite doses of 625 and 1250 kg.ha-1. Before lime addition, soil pH was 3.7; organic matter content was 2.14 % and cation exchange capacity (CEC) was 21.7 Cmolc kg -1. Soil was sampled at three different stages, first before sowing in aerobic conditions and them two more times in anaerobiosis, i.e. by bunch formation and flowering. Ninety-six soil samples per treatment were taken during each of the three sampling periods. NH4+-N, P and K were routinely determined. Spatial variability was assessed through the analysis of semivariograms. Next, kriging maps were constructed and compared for successive sampling dates. The statistical variability of NH4+-N, P and K over the study period was low to medium, depending on treatment and sampling dates. Lime application produced a positive effect on the NH4+ availability at sowing time. Increased Olsen-P availability during sowing and tillering could be also attributed to lime addition, but a negative effect of liming on P availability was observed during flowering. Mehlich I extractable K was in general low to very low and decreased from sowing to flowering, irrespective of lime treatment. Semivariogram analysis showed a rather strong spatial dependence of NH4+, P and K concentrations and this all over the three study periods and for the three lime treatments. Empirical semivariograms could be adjusted quite well by a nugget component (C0) plus a spatial structure (C1), which was described by spherical or exponential models with a correlation range between 40 and 85 m. Geostatistical analysis provided insight into possible processes responsible of the observed spatial variability patterns within the rice soil. Kriging was useful in mapping macronutrient variability allowing identifying microrregions with high or low values of the target soil properties clearly showing the presence of small scale variability for the study soil attributes within each liming treatment and during each of the three sampling dates. Also the position of patches with maxima and minima values changed between successive sampling dates illustrating the lack of temporal stability of the pattern of spatial distribution for the study soil attributes. Results illustrate the potential for applying the principles of precision agriculture to control spatiotemporal variability in rice fields.

Vidal Vázquez, E.; Morales, L. A.; Paz González, A.

2012-04-01

63

Mechanical analysis of crack location under row-planted rice in clayey paddy fields  

NASA Astrophysics Data System (ADS)

Desiccation cracks play an important role in the drainage of excess water via subsurface drainage systems in clayey, puddled paddy fields. This study focuses on the linear inter-row cracks induced by the water absorption from row-planted rice. The shrinkage behavior of clayey, puddled soil, which can be regarded as the consolidation of saturated soil subject to negative pore water pressure (i.e., suction), was simulated by a numerical model based on the 2-dimensional consolidation theory. The model describes how absorption of soil moisture by row-planted crops induces soil deformation and the distribution of tensile effective stress. This model requires specific parameters regarding the mechanical and hydraulic properties. These parameters can be determined based on the e- log p relationship and the e- log k relationship. These calculations were performed using the finite element method (FEM). The validity of the model was verified by the results of laboratory experiments that modeled the phenomenon observed between the inter-row spaces. This experiment revealed occurrence of cracks induced by bidirectional water movement, as well as the correspondence between the locations of cracks and the predicted peaks of tensile effective stress. Thus, it was proved that linear inter-row cracks inevitably occur following the balance of increasing total tensile stress and suction. Further numerical simulations demonstrated that the distribution of tensile effective stress has either single or double peaks, depending on the condition. Greater transpiration flux, wider row spacing, and a thinner layer of puddled soil induce the double-peaked distribution of tensile effective stress. This phenomenon may correspond to the field observation that the linear inter-row cracks running parallel to the rows are single at a row spacing of less than 60 cm, but double at the wider row-spacing.

Yoshida, S.; Adachi, K.

2003-04-01

64

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)

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.

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

2012-03-01

65

DIRECT AND INDIRECT EFFECTS OF MICROBES ON TECHNETIUM INSOLUBILIZATION IN PADDY FIELDS  

SciTech Connect

Direct and indirect effects of microorganisms on technetium insolubilization in water covering waterlogged soils were studied. Seven soils were waterlogged and then the water covering the soils were collected for further tracer experiments. The samples in contact with air were incubated with 95mTcO4--at 25 C for 4 to 5 days. After incubation, the samples were sequentially separated into four fractions: one insoluble fraction (> 0.2 {micro}m) and three soluble fractions (TcO4 -, cationic, and other forms). The radioactivity of 95mTc in each fraction was measured with a NaI (Tl) scintillation counter. The insolubility of Tc was observed in the untreated samples. The maximum insolubilization radioactivity was 37% of the total radioactivity in P38, which was collected from a paddy field, gray lowland soil. Microscopic observations revealed that bacteria were the dominant species in the insoluble fraction of P38. For the other samples, less than 9% of the Tc was found in insoluble form. In order to clarify biological and nonbiological factor affecting the insolubility, a reducing agent or nutrients were added to the P38 sample. The amount of insoluble Tc was enhanced by the addition of nutrients, while the addition of the reducing agent resulted in a dramatic decrease in the amount of the insoluble Tc. Most of the 95mTcO4 - added to the filtered or autoclaved samples was present in the form of the pertechnetate anion, even in P38. The filtered and autoclaved samples contained metabolites and dead cell particles, respectively. These materials, therefore, did not affect the physicochemical changes in Tc. These results suggest that specific bacteria having the ability to render Tc insoluble even under not strictly anaerobic conditions directly contribute to the insolubility of Tc.

Ishii, N.; Tagami, K.; Uchida, S.

2003-02-27

66

A simulation model for investigating the effects of rice paddy fields on the runoff system  

Microsoft Academic Search

Rice production in Taiwan is likely to decrease because of two major threats: an increase in the industrial demand on water resources and cheaper imported rice resulting from the free trade policy which will be enforced when Taiwan joins the World Trade Organization. A shrinkage in rice paddy acreage raises environmental concerns, especially in relation to water conservation. Besides rice

Ray-Shyan Wu; Wen-Ray Sue; Chuan-Bin Chien; Ching-Ho Chen; Jia-Shien Chang; Kuei-Miao Lin

2001-01-01

67

Estimating the Microbial Risk of E. coli in Reclaimed Wastewater Irrigation on Paddy Field  

Microsoft Academic Search

Microbial risk was quantified to assess human health risk as a result of exposure to E. coli in reclaimed wastewater irrigation. Monitoring data on E. coli were collected from pond water in paddy rice plots during the growing season. Five treatments were used and each was triplicated\\u000a to evaluate the changes in E. coli concentrations in experiments performed in 2003

Youn-Joo An; Chun G. Yoon; Kwang-Wook Jung; Jong-Hwa Ham

2007-01-01

68

Dynamics of dissolved oxygen (DO) in ponded water of a paddy field  

Microsoft Academic Search

The transfer of heat and dissolved oxygen (DO) through water is important to understand the phenomenon of ponded water in a paddy soil. The heat from solar radiation is absorbed at the soil surface and transferred into the ponded water by convection. This study clarified the dynamics of DO, as well as the role of convection in water in DO

Mohamed Ismail Mohammed Mowjood; Tatsuaki Kasubuchi

1998-01-01

69

Effect of ammonium-based, non-sulfate fertilizers on CH 4 emissions from a paddy field with a typical Chinese water management regime  

NASA Astrophysics Data System (ADS)

The effects of ammonium-based, non-sulfate fertilizers, such as urea and/or ammonium phosphate (NH 4H 2PO 4), on methane (CH 4) emissions from paddy rice fields deserve attention, as they are being used increasingly for rice cultivation. A four-year field campaign was conducted in the Yangtze River Delta from 2004 to 2007 to assess the effects of different application rates of urea plus NH 4H 2PO 4 on the CH 4 emissions from a paddy rice field. The experimental field was under a typical Chinese water regime that follows a flooding-midseason drainage-reflooding-moist irrigation mode. Over the course of four years, the mean cumulative CH 4 emissions during the rice seasons were 221, 136 and 112 kg C ha -1 for nitrogen addition rates of 0, 150 and 250 kg N ha -1, respectively. Compared to the treatment without nitrogen amendments, the 150 kg N ha -1 decreased the CH 4 emissions by 6-59% ( P < 0.01 in one year, but not statistically significant in the others). When the addition rate was further increased to 250 kg N ha -1, the CH 4 emissions were significantly reduced by 35-53% ( P < 0.01) compared to the no-nitrogen treatment. Thus, an addition rate of 250 kg N ha -1, which has been commonly adopted in the delta region in the past two decades, can be regarded as an effective management measure as regards increasing rice yields while reducing CH 4 emissions. Considering that doses of ammonium-based, non-sulfate fertilizers higher than 250 kg N ha -1 currently are, and most likely will continue to be, commonly applied for paddy rice cultivation in the Yangtze River Delta and other parts of China, the inhibitory effects on CH 4 emissions from rice production are expected to be pronounced at the regional scale. However, further studies are required to provide more concrete evidence about this issue. Moreover, further research is needed to determine whether N management measures are also effective in view of net greenhouse gas fluxes (including CH 4, nitrous oxide, ammonia emissions, nitrate leaching and N loss from denitrification).

Dong, Haibo; Yao, Zhisheng; Zheng, Xunhua; Mei, Baoling; Xie, Baohua; Wang, Rui; Deng, Jia; Cui, Feng; Zhu, Jianguo

2011-02-01

70

Analysis of [FeFe]-hydrogenase genes for the elucidation of a hydrogen-producing bacterial community in paddy field soil.  

PubMed

Hydrogen (H2) is one of the most important intermediates in the anaerobic decomposition of organic matter. Although the microorganisms consuming H2 in anaerobic environments have been well documented, those producing H2 are not well known. In this study, we elucidated potential members of H2 -producing bacteria in a paddy field soil using clone library analysis of [FeFe]-hydrogenase genes. The [FeFe]-hydrogenase is an enzyme involved in H2 metabolism, especially in H2 production. A suitable primer set was selected based on the preliminary clone library analysis performed using three primer sets designed for the [FeFe]-hydrogenase genes. Soil collected in flooded and drained periods was used to examine the dominant [FeFe]-hydrogenase genes in the paddy soil bacteria. In total, 115 and 108 clones were analyzed from the flooded and drained paddy field soils, respectively. Homology and phylogenetic analysis of the clones showed the presence of diverse [FeFe]-hydrogenase genes mainly related to Firmicutes, Deltaproteobacteria, and Chloroflexi. Predominance of Deltaproteobacteria and Chloroflexi suggests that the distinct bacterial community possessed [FeFe]-hydrogenase genes in the paddy field soil. Our study revealed the potential members of H2 -producing bacteria in the paddy field soil based on their genetic diversity and the distinctiveness of the [FeFe]-hydrogenase genes. PMID:24261851

Baba, Ryuko; Kimura, Makoto; Asakawa, Susumu; Watanabe, Takeshi

2014-01-01

71

Arsenic concentrations in paddy soil and rice and health implications for major rice-growing regions of Cambodia.  

PubMed

Despite the global importance of As in rice, research has primarily focused on Bangladesh, India, China, and the United States with limited attention given to other countries. Owing to both indigenous As within the soil and the possible increases arising from the onset of irrigation with groundwater, an assessment of As in rice within Cambodia is needed, which offers a "base-case" comparison against sediments of similar origin that comprise rice paddy soils where As-contaminated water is used for irrigation (e.g., Bangladesh). Here, we evaluated the As content of rice from five provinces (Kandal, Prey Veng, Battambang, Banteay Meanchey, and Kampong Thom) in the rice-growing regions of Cambodia and coupled that data to soil-chemical factors based on extractions of paddy soil collected and processed under anoxic conditions. At total soil As concentrations ranging 0.8 to 18 ?g g(-1), total grain As concentrations averaged 0.2 ?g g(-1) and ranged from 0.1 to 0.37 with Banteay Meanchey rice having significantly higher values than Prey Veng rice. Overall, soil-extractable concentrations of As, Fe, P, and Si and total As were poor predictors of grain As concentrations. While biogeochemical factors leading to reduction of As(V)-bearing Fe(III) oxides are likely most important for predicting plant-available As, husk and straw As concentrations were the most significant predictors of grain-As levels among our measured parameters. PMID:24712677

Seyfferth, Angelia L; McCurdy, Sarah; Schaefer, Michael V; Fendorf, Scott

2014-05-01

72

Effects of changes in environmental conditions on atmospheric mercury exchange: Comparative analysis from a rice paddy field during the two spring periods of 2001 and 2002  

Microsoft Academic Search

The environmental mobilization characteristics of Hg were investigated in a rice paddy field in the Hari district of Kang Hwa Island, Korea during two field campaigns held in late March 2001 and late April 2002. In the course of these two field campaigns, we measured the concentration, concentration gradients (between two different heights of 1 and 5 m), and fluxes

Ki-Hyun Kim; Min-Young Kim; Joon Kim; Gangwoong Lee

2003-01-01

73

Combination system of full-scale constructed wetlands and wetland paddy fields to remove nitrogen and phosphorus from rural unregulated non-point sources.  

PubMed

Constructed wetlands (CWs) have been used effectively to remove nitrogen (N) and phosphorus (P) from non-point sources. Effluents of some CWs were, however, still with high N and P concentrations and remained to be pollution sources. Widely distributed paddy fields can be exploited to alleviate this concern. We were the first to investigate a combination system of three-level CWs with wetland paddy fields in a full scale to remove N and P from rural unregulated non-point sources. The removal efficiencies (REs) of CWs reached 57.3 % (37.4-75.1 %) for N and 76.3 % (62.0-98.4 %) for P. The CWs retained about 1,278 kg N ha(-1) year(-1) and 121 kg P ha(-1) year(-1). There was a notable seasonal change in REs of N and P, and the REs were different in different processing components of CWs. The removal rates of wetland paddy fields adopt "zero-drainage" water management according to local rainfall forecast and physiological water demand of crop growth reached 93.2 kg N ha(-1) year(-1) and 5.4 kg P ha(-1) year(-1). The rice season had higher potential in removing N and P than that in the wheat season. The whole combined system (0.56 ha CWs and 5.5 ha wetland paddy fields) removed 1,790 kg N year(-1) and 151 kg P year(-1), which were higher than those from CWs functioned alone. However, another 4.7-ha paddy fields were needed to fully remove the N and P in the effluents of CWs. The combination of CWs and paddy fields proved to be a more efficient nutrient removal system. PMID:23703587

Sun, Haijun; Zhang, Hailin; Yu, Zhimin; Wu, Jiasen; Jiang, Peikun; Yuan, Xiaoyan; Shi, Weiming

2013-12-01

74

Mapping paddy rice with multi-date moderate-resolution imaging spectroradiometer (MODIS) data in China  

Microsoft Academic Search

The objective of this study was to obtain spatial distribution maps of paddy rice fields using multi-date moderateresolution\\u000a imaging spectroradiometer (MODIS) data in China. Paddy rice fields were extracted by identifying the unique characteristic\\u000a of high soil moisture in the flooding and transplanting period with improved algorithms based on rice growth calendar regionalization.\\u000a The characteristic could be reflected by the

Hua-sheng Sun; Jing-feng Huang; Alfredo R. Huete; Dai-liang Peng; Feng Zhang

2009-01-01

75

Spatial variability of soil saturated hydraulic conductivity in paddy field in accordance to subsurface percolation  

Microsoft Academic Search

Insufficient puddling with inappropriate implements or imprecise time\\/intensity may alter saturated water flow in paddy soil\\u000a spatially or temporary due to change in aggregate size distribution, dry bulk density, saturated hydraulic conductivity, and\\u000a percolation rate of the soil. In this study, spatial variability of saturated hydraulic conductivity (K\\u000a s), a key parameter of the saturated water flow, in Fuchu Honmachi

K. Wijaya; T. Nishimura; B. I. Setiawan; S. K. Saptomo

2010-01-01

76

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

PubMed

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

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

2014-01-01

77

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

PubMed

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

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

2009-01-01

78

[Effects of labor-saving rice cultivation modes on the diversity of potential weed communities in paddy fields].  

PubMed

Aimed to understand the effects of various labor-saving rice cultivation modes on the diversity of potential weed communities in paddy fields, an investigation was made on the quantitative characteristics of the weed seed bank under dry direct seeding, water direct seeding, seedling throwing, mechanized-transplanting, wheat-rice interplanting, and conventional manual transplanting. Under dry direct seeding, the density of the weed seed bank was up to 228,416 seeds x m(-2), being significantly higher than that under the other five cultivation modes. Wheat-rice interplanting ranked the second place. The seed density of sedge weeds under dry direct seeding and that of broad leaf weeds under wheat-rice interplanting were significantly higher than the seed densities of various kinds of weeds under other cultivation modes. Conventional manual transplanting mode had the highest species richness, with Margalef index being 1.86. The diversity indices, including Shannon-Wiener index, Gini index, and Pielou evenness index under water direct seeding and wheat-rice interplanting were higher than those under other cultivation modes. Comparing with conventional manual transplanting mode, the other five cultivation modes had their own dominant species in the potential weed community, and thereby, different labor-saving rice cultivation modes should be applied by turns to control the potential weed community in paddy fields effectively and persistently. PMID:20077702

Li, Shu-Shun; Qiang, Sheng; Jiao, Jun-Sen

2009-10-01

79

Actual Condition of Paddy Field Levee Maintenance by Various Farm Households including Large-scale Farming in the Developed Land Renting Area  

NASA Astrophysics Data System (ADS)

The survey of interview, resource acquisition, photographic operation, and questionnaire were carried out in the “n” Community in the “y” District in Hakusan City in Ishikawa Prefecture to investigate the actual condition of paddy field levee maintenance in the area where land-renting market was proceeding, large-scale farming was dominant, and the problems of geographically scattered farm-land existed. In the study zone, 1) an agricultural production legal person rent-cultivated some of the paddy fields and maintained the levees, 2) another agricultural production legal person rent-cultivated some of the soy bean fields for crop changeover and land owners maintained the levees. The results indicated that sufficient maintenance was executed on the levees of the paddy fields cultivated by the agricultural production legal person, the soy bean fields for crop changeover, and the paddy fields cultivated by the land owners. Each reason is considered to be the managerial strategy, the economic incentive, the mutual monitoring and cross-regulatory mechanism, etc.

Sakata, Yasuyo

80

Elevated ground-level O(3) changes the diversity of anoxygenic purple phototrophic bacteria in paddy field.  

PubMed

The knowledge of the impact of elevated ground-level O(3) below ground the agro-ecosystem is limited. A field experiment in China Ozone Free-Air Concentration Enrichment (FACE-O(3)) facility on a rice-wheat rotation system was carried out to investigate responses of anoxygenic phototrophic purple bacteria (AnPPB) to elevated ground-level O(3). AnPPB community structures and sizes in paddy soil were monitored by molecular approaches including PCR-DGGE and real-time quantitative PCR based upon the pufM gene on three typical rice growth stages. Repetitive sequence-based PCR (rep-PCR) in combination with culture-reliant method was conducted to reveal changes in genotypic diversity. Elevated ground-level O(3) statistically reduce AnPPB abundance and percentage in total bacterial community in flooded rice soil via decreasing their genotypic diversity and metabolic versatility. Concomitantly, their community composition changed after rice anthesis stage under elevated ground-level O(3). Our results from AnPPB potential responses imply that continuously elevated ground-level O(3) in the future would eventually harm the health of paddy ecosystem through negative effect on soil microorganisms. PMID:21698401

Feng, Youzhi; Lin, Xiangui; Yu, Yongchang; Zhu, Jianguo

2011-11-01

81

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

PubMed Central

The transfer of arsenic to rice grains is a human health issue of growing relevance in regions of southern Asia where shallow groundwater used for irrigation of paddy fields is elevated in As. In the present study, As and Fe concentrations in soil water and in the roots of rice plants, primarily the Fe plaque surrounding the roots, were monitored during the 4-month growing season at two sites irrigated with groundwater containing ~130 ?g/L As and two control sites irrigated with water containing <15 ?g/L As. At both sites irrigated with contaminated water, As concentrations in soil water increased from <10 ?g/L to >1000 ?g/L during the first five weeks of the growth season and then gradually declined to <10 ?g/L during the last five weeks. At the two control sites, concentrations of As in soil water never exceeded 40 ?g/L. At both contaminated sites, the As content of roots and Fe plaque rose to 1000-1500 mg/kg towards the middle of the growth season. It then declined to ~300 mg/kg towards the end, a level still well above As concentration of ~100 mg/kg in roots and plaque measured throughout the growing season at the two control sites. These time series, combined with simple mass balance considerations, demonstrate that the formation of Fe plaque on the roots of rice plants by micro-aeration significant limits uptake of As by rice plants grown in paddy fields. Large variations in the As and Fe content of plant stems at two of the sites irrigated with contaminated water and one of the control sites were also recorded. The origin of these variations, particularly during the last month of the growth season, need to be better understood because they are likely to influence uptake of As in rice grains. PMID:20576285

Garnier, J.-M.; Travassac, F.; Lenoble, V.; Rose, J.; Zheng, Y.; Hossain, M.S.; Chowdhury, S. H.; Biswas, A. K.; Ahmed, K.M.; Cheng, Z.; van Geen, A.

2010-01-01

82

Emissions of CH4 and N2O under Different Tillage Systems from Double-Cropped Paddy Fields in Southern China  

PubMed Central

Understanding greenhouse gases (GHG) emissions is becoming increasingly important with the climate change. Most previous studies have focused on the assessment of soil organic carbon (SOC) sequestration potential and GHG emissions from agriculture. However, specific experiments assessing tillage impacts on GHG emission from double-cropped paddy fields in Southern China are relatively scarce. Therefore, the objective of this study was to assess the effects of tillage systems on methane (CH4) and nitrous oxide (N2O) emission in a double rice (Oryza sativa L.) cropping system. The experiment was established in 2005 in Hunan Province, China. Three tillage treatments were laid out in a randomized complete block design: conventional tillage (CT), rotary tillage (RT) and no-till (NT). Fluxes of CH4 from different tillage treatments followed a similar trend during the two years, with a single peak emission for the early rice season and a double peak emission for the late rice season. Compared with other treatments, NT significantly reduced CH4 emission among the rice growing seasons (P<0.05). However, much higher variations in N2O emission were observed across the rice growing seasons due to the vulnerability of N2O to external influences. The amount of CH4 emission in paddy fields was much higher relative to N2O emission. Conversion of CT to NT significantly reduced the cumulative CH4 emission for both rice seasons compared with other treatments (P<0.05). The mean value of global warming potentials (GWPs) of CH4 and N2O emissions over 100 years was in the order of NTregions. PMID:23750250

Zhang, Hai-Lin; Bai, Xiao-Lin; Xue, Jian-Fu; Chen, Zhong-Du; Tang, Hai-Ming; Chen, Fu

2013-01-01

83

Emissions of CH4 and N2O under different tillage systems from double-cropped paddy fields in Southern China.  

PubMed

Understanding greenhouse gases (GHG) emissions is becoming increasingly important with the climate change. Most previous studies have focused on the assessment of soil organic carbon (SOC) sequestration potential and GHG emissions from agriculture. However, specific experiments assessing tillage impacts on GHG emission from double-cropped paddy fields in Southern China are relatively scarce. Therefore, the objective of this study was to assess the effects of tillage systems on methane (CH4) and nitrous oxide (N2O) emission in a double rice (Oryza sativa L.) cropping system. The experiment was established in 2005 in Hunan Province, China. Three tillage treatments were laid out in a randomized complete block design: conventional tillage (CT), rotary tillage (RT) and no-till (NT). Fluxes of CH4 from different tillage treatments followed a similar trend during the two years, with a single peak emission for the early rice season and a double peak emission for the late rice season. Compared with other treatments, NT significantly reduced CH4 emission among the rice growing seasons (P<0.05). However, much higher variations in N2O emission were observed across the rice growing seasons due to the vulnerability of N2O to external influences. The amount of CH4 emission in paddy fields was much higher relative to N2O emission. Conversion of CT to NT significantly reduced the cumulative CH4 emission for both rice seasons compared with other treatments (P<0.05). The mean value of global warming potentials (GWPs) of CH4 and N2O emissions over 100 years was in the order of NTregions. PMID:23750250

Zhang, Hai-Lin; Bai, Xiao-Lin; Xue, Jian-Fu; Chen, Zhong-Du; Tang, Hai-Ming; Chen, Fu

2013-01-01

84

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

E-print Network

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

van Geen, Alexander

85

Fate and transport of bensulfuron-methyl and imazosulfuron in paddy fields: experiments and model simulation  

Microsoft Academic Search

Experiments were conducted to determine the fate of bensulfuron-methyl (BSM) and imazosulfuron (IMS) under paddy conditions.\\u000a Initially, laboratory experiments were conducted and the photolysis half-lives of the two herbicides were found to be much\\u000a shorter than their hydrolysis half-lives in aqueous solutions. In the aerobic water–soil system, dissipation followed first-order\\u000a kinetics with water half-lives of 9.1 and 11.0 days and soil

Kazuhiro TakagiFerdinand; Ferdinand F. Fajardo; Masumi Ishizaka; Thai Khanh Phong; Hirozumi Watanabe; Julien Boulange

86

Phylogenetic diversity and assemblage of major capsid genes (g23) of T4-type bacteriophages in paddy field soils during rice growth season in Northeast China  

Microsoft Academic Search

Although bacteriophages (phages) are ubiquitous and the most abundant biological entities on Earth, the genetic information on their diversity and community composition in natural environments, particularly in soils, is limited. This study elucidated the diversity and composition of T4-type phages by analyzing partial major capsid gene (g23) sequences in DNA extracts from five paddy field soils in Northeast China during

Junjie Liu; Guanghua Wang; Qiang Wang; Judong Liu; Jian Jin; Xiaobing Liu

2012-01-01

87

High-frequency water vapor isotope measurements with a laser spectrometer in a paddy field during growing season and application for evapotranspiration partitioning  

NASA Astrophysics Data System (ADS)

Knowledge of the partitioning evapotranspiration (ET) into evaporation (E) and transpiration (T) components is crucial to improve water use efficiency in irrigated land, especially in paddy field. However, much less is known about the relative contribution of each component owing to difficulties in field observations. In this study, we estimate the fractions of evaporation and transpiration contributing to the total evapotranspiration flux in a paddy field of Tuskuba, Japan (36° 03' 14.3" N, 140° 01' 36.9" E) using high-frequency laser spectrometer (Picarro L2120-i Analyzer). The isotopic composition of evapotranspiration flux (?ET) is determined by Keeling plot method based on water vapor isotope measurements of 1-minute interval on a diurnal time scale. The surface water isotope ratios is used to estimate the isotopic compositions of transpiration flux (?T) and evaporation flux (?E) with Craig-Gordon model. The results indicate that the transpiration is highly related to the leaf area index and drastically increase in growing season. The transpiration is the strongest in June and July, representing more than 90% of the total evapotranspiration flux. However, evaporation is dynamically controlled by water temperature at nighttime and appears to predominate the total nighttime evapotranspiration flux. These results are well consistent with those calculated from eddy correlation method and suggest the importance of nighttime evaporation in estimating diurnal flux. This finding may contribute to solving the closure energy imbalance problem in foregoing experimental studies in paddy field. Our present study provided a simple method for investigating water balance of paddy field and corroborated that water isotope is a powerful diagnostic tool in understanding the water exchange processes.

Wei, Z.; Maeda, H.; Okazaki, A.; Noda, K.; Kiguchi, M.; Koike, M.; Kim, W.; Yokoi, M.; Yoshimura, K.

2013-12-01

88

Internal aeration of paddy field rice (Oryza sativa) during complete submergence---importance of light and floodwater O2.  

PubMed

Flash floods can submerge paddy field rice (Oryza sativa), with adverse effects on internal aeration, sugar status and survival. Here, we investigated the in situ aeration of roots of rice during complete submergence, and elucidated how underwater photosynthesis and floodwater pO(2) influence root aeration in anoxic soil. In the field, root pO(2) was measured using microelectrodes during 2 d of complete submergence. Leaf gas films that formed on the superhydrophobic leaves were left intact, or experimentally removed, to elucidate their effect on internal aeration. In darkness, root pO(2) declined to very low concentrations (0.24 kPa) and was strongly correlated with floodwater pO(2). In light, root pO(2) was high (14 kPa) and primarily a function of the incident light determining the rates of underwater net photosynthesis. Plants with intact leaf gas films maintained higher underwater net photosynthesis relative to plants without gas films when the submerged shoots were in light. During complete submergence, internal aeration of rice in the field relies on underwater photosynthesis during the day and entry of O(2) from the floodwater during the night. Leaf gas films enhance photosynthesis during submergence leading to improved O(2) production and sugar status, and therefore contribute to the submergence tolerance of rice. PMID:23215967

Winkel, Anders; Colmer, Timothy D; Ismail, Abdelbagi M; Pedersen, Ole

2013-03-01

89

[Effects of long-term applying sulfur- and chloride-containing chemical fertilizers on weed growth in paddy field].  

PubMed

An investigation was made at a double-rice paddy field in the Qiyang Red Soil Field Experimental Station, Hunan Province, China to study the species and biomass of weeds growing in rice (Oryza sativa L.) growth season after 34-year application of sulfur (SO4(2-)) and chloride (Cl(-))-containing chemical fertilizers under the same application rates of nitrogen (N), phosphorus (P), and potassium (K). Long-term application of Cl(-)-containing chemical fertilizer resulted in the greatest species number of weeds and the highest biomass of floating weeds and wet weeds, compared with long-term application of SO4(2-) and Cl(-) +SO4(2-)-containing chemical fertilizers. In early rice growth season, the biomass of weeds after applying Cl(-)-containing chemical fertilizer was 51.4% and 17.6% higher than that after applying Cl(-) + SO4(2-) and SO4(2-)-containing chemical fertilizers, respectively; in late rice growth season, the increment was 144% and 242%, respectively. More floating weeds were observed after applying Cl(-) + SO4(2-) and SO4(2-)-containing chemical fertilizers, but few of them were found after applying Cl(-)-containing chemical fertilizer. The total dry mass of weeds and the dry mass of wet weeds were positively correlated with soil Cl(-) content (r = 0.764, P < 0.01 and r = 0.948, P < 0.01, respectively), but negatively correlated with soil SO4(2-)-S content (r = 0.849, P < 0.01 and r = 0.641, P < 0.05). Soil alkali-hydrolyzable N and available P, under the co-effects of soil SO4(2-)-S, Cl(-), and pH, had indirect effects on the total dry mass of weeds. By adopting various fertilization measures to maintain proper soil pH and alkali-hydrolyzable N and available P contents, increase soil SO42(-)-S content, and decrease soil Cl(-) content, it could be possible to effectively inhibit the growth of wet weeds and to decrease the total biomass of weeds in double-rice paddy field. PMID:21774323

Shen, Pu; Gao, Ju-sheng; Xu, Ming-gang; Li, Dong-chu; Niu, De-kui; Qin, Dao-zhu

2011-04-01

90

Development and validation of an analytical method for determination of endocrine disruptor, 2,4-D, in paddy field water.  

PubMed

The acidic herbicides are an important class of chemical compounds that are used to control a variety of weeds that threaten many crops. Owing to their low microbial activity levels, the acidic herbicides exhibit a residual activity remaining for periods of up to several months in soils and water. The principal objective of this study was to develop an analytical method based on liquid-liquid and solid-phase extraction followed by HPLC, for the determination of 2,4-D in paddy field water. The residues were verified via tandem mass spectrometry (MS/MS) in negative-ion electrospray ionization (ESI) mode. Linearity was good over a concentration range of 1-100?µg/L with a correlation coefficient (r(2) ) of 0.999. The mean recovery rates of triplicate results ranged from 85.2 to 90.85%. The limits of detection and quantitation were 0.4 and 1.0?µg/L, respectively. The method proposed herein was applied to field samples acquired from Hampyung and Sunchang counties, Republic of Korea. The analyte was detected at a concentration range of 6.8-12.8 and 3.55-24.0?µg/L, respectively. PMID:21204114

Park, Ji-Yeon; Choi, Jeong-Heui; Abd El-Aty, A M; Kim, Bo Mi; Park, Jong-Hyouk; Choi, Woo Jung; Shim, Jae-Han

2011-09-01

91

Avian Diversity and Feeding Guilds in a Secondary Forest, an Oil Palm Plantation and a Paddy Field in Riparian Areas of the Kerian River Basin, Perak, Malaysia  

PubMed Central

The diversity and the feeding guilds of birds in three different habitats (secondary forest, oil palm plantation and paddy field) were investigated in riparian areas of the Kerian River Basin (KRB), Perak, Malaysia. Point-count observation and mist-netting methods were used to determine bird diversity and abundance. A total of 132 species of birds from 46 families were recorded in the 3 habitats. Species diversity, measured by Shannon’s diversity index, was 3.561, 3.183 and 1.042 in the secondary forest, the paddy field and the oil palm plantation, respectively. The vegetation diversity and the habitat structure were important determinants of the number of bird species occurring in an area. The relative abundance of the insectivore, insectivore-frugivore and frugivore guilds was greater in the forest than in the monoculture plantation. In contrast, the relative abundance of the carnivore, granivore and omnivore guilds was higher in the plantation. The results of the study show that the conversion of forest to either oil palm plantation or paddy fields produced a decline in bird diversity and changes in the distribution of bird feeding guilds. PMID:24575217

Azman, Nur Munira; Latip, Nurul Salmi Abdul; Sah, Shahrul Anuar Mohd; Akil, Mohd Abdul Muin Md; Shafie, Nur Juliani; Khairuddin, Nurul Liyana

2011-01-01

92

Assessing the potential impact of fly ash amendments on Indian paddy field with special emphasis on growth, yield, and grain quality of three rice cultivars.  

PubMed

Proper disposal and/or recycling of different industrial waste materials have long been recognized as a prime environmental concern throughout the world, and fly ash is major amongst them. In the present study, we tried to assess the feasibilities of possible effective and safe utilization of fly ash as soil amendment in Indian paddy field and its impact on rice plants, especially at growth and yield level. Our results showed that certain doses of fly ash amendments have significantly improved the physico-chemical and mineralogical properties of paddy field soil, and at lower level of amendments, fly ash induced the growth performances of three rice cultivars too. Grain yield and grain quality also responded similarly as per the growth responses. However, differential cultivar response was observed accordingly, and cultivar Sugandha-3 showed higher yield as compared with cultivars Sambha and Saryu-52. Based on the observed results, it was concluded that up to a certain level, fly ash amendments could be beneficial for Indian paddy field and can be utilized as feasible management strategy for the disposal of this major industrial waste. PMID:21901311

Singh, Anupama; Sarkar, Abhijit; Agrawal, S B

2012-08-01

93

[Characteristics of CO2, CH4 and N2O emissions from winter-fallowed paddy fields in hilly area of South China].  

PubMed

With closed static chamber and modified gas chromatograph (HP5890 II), the in situ measurements were made on the CO2, CH4 and N2O emissions from winter-fallowed paddy fields in the hilly area of South China. Gas samples were taken simultaneously from the fields with and without rice stubble. The results showed that both of the fields had the peak value of CO2 flux in the late afternoon. In the fields with and without rice stubble, the CH4 flux was positive in the day time while negative in the night, and the N2O flux in the day time was 1.79 and 1.58 times as much as that in the night, respectively. The diurnal average CO2 flux in the field with rice stubble was significantly higher than that in bare field (P < 0.05). Correlation analysis demonstrated that the CO2 flux in winter-fallowed paddy fields had significant correlations with soil temperature, aboveground temperature, and air temperature, suggesting that temperature was the main factor affecting the CO2 emission from rice field after harvesting. During the observation time (from 2003-11-10 to 2004-01-18), the average CO2, CH4 and N2O fluxes in the field with rice stubble were (180.69 +/- 21.21) mg x m(-2) x h(-1), (-0.04 +/- 0.01) mg x m(-2) x h(-1) and (21.26 +/- 19.31) microg x m(-2) x h(-1), respectively. Compared with bare field, the CO2 flux in the field with rice stubble was 13.06% higher, CH4 absorption increased by 50%, while N2O flux was 60.75% lower. It was concluded that the winter fallowed paddy field in hilly area of South China was the source of atmospheric CO2 and N2O, and the sink of atmospheric CH4. PMID:17396500

Liu, Hui; Zhao, Ping; Sun, Gu-chou; Lin, Yong-biao; Rao, Xing-quan; Wang, Yue-si

2007-01-01

94

Diversity of bacteriophages infecting Xanthomonas oryzae pv. oryzae in paddy fields and its potential to control bacterial leaf blight of rice.  

PubMed

Bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv. oryzae (Xoo) is a very serious disease in rice-growing regions of the world. In spite of their economic importance, there are no effective ways of protecting rice plants from this disease. Bacteriophages infecting Xoo affect the population dynamics of the pathogen and consequently the occurrence of the disease. In this study, we investigated the diversity, host range, and infectivity of Xoo phages, and their use as a bicontrol agent on BLB was tested. Among the 34 phages that were isolated from floodwater in paddy fields, 29 belonged to the Myoviridae family, which suggests that the dominant phage in the ecosystem was Myoviridae. The isolated phages were classified into two groups based on plaque size produced on the lawn of Xoo. In general, there was a negative relationship between plaque size and host range, and interestingly the phages having a narrow host range had low efficiency of infectivity. The deduced protein sequence analysis of htf genes indicated that the gene was not a determinant of host specificity. Although the difference in host range and infectivity depending on morphotype needs to be addressed, the results revealed deeper understanding of the interaction between the phages and Xoo strains in floodwater and damp soil environments. The phage mixtures reduced the occurrence of BLB when they were treated with skim milk. The results indicate that the Xoo phages could be used as an alternative control method to increase the control efficacy and reduce the use of agrochemicals. PMID:24651644

Chae, Jong-Chan; Hung, Nguyen Bao; Yu, Sang-Mi; Lee, Ha Kyung; Lee, Yong Hoon

2014-06-28

95

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

PubMed Central

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

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

2012-01-01

96

Quantifying methane emissions from rice fields in the Taihu Lake region, China by coupling a detailed soil database with biogeochemical model  

NASA Astrophysics Data System (ADS)

As China has approximately 22% of the world's rice paddies, the regional quantification of CH4 emissions from these paddies is important in determining their contribution to the global greenhouse gas effect. This paper reports the use of a biogeochemical model (DeNitrification and DeComposition or DNDC) for quantifying CH4 emissions from rice fields in the Taihu Lake region of China. For this application, the DNDC model was linked to a 1:50 000 soil database derived from 1107 paddy soil profiles compiled during the Second National Soil Survey of China in the 1980s-1990s. The simulated results showed that the 2.3 Mha of paddy rice fields in the Taihu Lake region emitted the equivalent of 5.7 Tg C from 1982-2000, with the average CH4 flux ranging from 114 to 138 kg C ha-1 y-1. As for soil subgroups, the highest emission rate (660 kg C ha-1 y-1) was linked to gleyed paddy soils accounting for about 4.4% of the total area of paddy soils. The lowest emission rate (91 kg C ha-1 y-1) was associated with degleyed paddy soils accounting for about 18% of the total area of paddy soils. The most common soil in the area was hydromorphic paddy soils, which accounted for about 53% of the total area of paddy soils with a CH4 flux of 106 kg C ha-1 y-1. On a regional basis, the annual averaged CH4 flux in the Taihu Lake plain soil region and alluvial plain soil region were higher than that in the low mountainous and hilly soil region and the polder soil region. The model simulation was conducted with two databases using polygons or counties as the basic units. The county-based database contained soil information coarser than the polygon system built based on the 1:50 000 soil database. The modeled results with the two databases found similar spatial patterns of CH4 emissions in the Taihu Lake region. However, discrepancies exist between the results from the two methods. The total CH4 emissions generated from the polygon-based database is 2.6 times the minimum CH4 emissions generated from the county-based database, and is 0.98 times the maximum CH4 emissions generated from the county-based database. The average value of the relative deviation ranged from -20% to 98% for most counties, which indicates that a more precise soil database is necessary to better simulate CH4 emissions from rice fields in the Taihu Lake region using the DNDC model.

Zhang, L.; Yu, D.; Shi, X.; Weindorf, D.; Zhao, L.; Ding, W.; Wang, H.; Pan, J.; Li, C.

2009-05-01

97

Effects of raising frogs and putting pest-killing lamps in paddy fields on the prevention of rice pests and diseases  

NASA Astrophysics Data System (ADS)

Frogs in paddy fields become less and less due to applying large amounts of pesticides and human hunting for a long time, which causes the aggravation of rice pests and diseases. A field experiment was carried out in the suburb of Shanghai to study the effects of artificially raising frogs and putting frequency oscillation pest-killing lamps in paddy fields on the prevention of rice pests and diseases. The field experiment includes three treatments. Treatment I: 150 frogs, each 20 g in weight, per 100 m2 were put in the fields; Treatment II: a frequency oscillation pest-killing lamp was put in the fields; Treatment III: no frogs and pest-killing lamps were put in the fields. All the experimental fields were operated based on the organic faming system. The amount of organic manure, 7500 kg/hm2, was applied to the fields as base fertilizer before sowing in early June, 2013. No any chemical fertilizers and pesticides were used during the entire period of rice growth. Each treatment is in triplicate and each plot is 67 m2 in area. The results are as follows: (1) During the entire growth period, the incidences of rice pests and diseases with Treatment I and II are significantly lower than those with CK (Treatment III). The incidence of chilo suppressalis with Treatment I, II and III is 0, 0.46% and 1.69%, respectively; that of cnaphalocrocis medinalis is 7.67%, 6.62% and 10.10%, respectively; that of rice sheath blight is 0, 11.11% and 5.43%, respectively; that of rice planthopper is 4.25 per hill, 5.75 per hill and 11 per hill, respectively. (2) The grain yield of the three treatments is significantly different. That of Treatment I, II and III is 5157.73 kg/hm2, 4761.60 kg/hm2 and 3645.14kg/hm2 on average, respectively. (3) Affected by frog activities, the contents of NH4-N, available P and available K in the soil with Treatment I are significantly raised. All the above suggest that artificially raising frogs in paddy fields could effectively prevent rice pests and diseases, especially reduce the incidences of rice sheath blight and chilo suppressalis, and setting pest-killing lamps could also effectively control rice pests, but not rice sheath blight, which contribute to the increase of grain yield largely. Moreover, the activity of frogs in paddy fields could improve soil fertility and increase bio-diversity. Acknowledgements: This work was supported by the National Natural Science Foundation of China (No. 41130526).

Teng, Qing; Hu, Xue-Feng; Luo, Fan; Cao, Ming-Yang

2014-05-01

98

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

PubMed

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

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

2014-12-15

99

From tidal wetland to paddy rice fields - Changes in soil microbial communities during 2000 years of rice cultivation  

NASA Astrophysics Data System (ADS)

In many areas of China tidal wetlands have been converted into agricultural land for lowland rice cultivation. However, the consequences and effects on soil microbial communities are poorly understood. Therefore, we investigated bacterial and archaeal communities involved in nitrification and denitrification based on diversity and abundance pattern of the corresponding functional genes in a tidal wetland and two paddy soils cultivated for 50 years respectively 2000 years with rice. The abundances of all measured genes increased from the tidal wetland to the 2000 years paddy soil in reference to one gram of soil due to a significant increase of the microbial biomass. When relating the functional gene copies to the extracted microbial biomass highest copy numbers were observed in the paddy soil with 50 years of rice cultivation history with exception of the archaeal nitrification gene amoA. T-RFLP data of the archaeal amoA gene and the bacterial denitrification gene nosZ revealed significant differences in community composition in the three investigated soils. Overall, our results indicate clear changes in abundance and diversity pattern of microbial communities participating in nitrogen cycling during rice paddy evolution.

Bannert, Andrea; Kleineidam, Kristina; Frenzel, Peter; Ho, Adrian; Schloter, Michael

2010-05-01

100

Trees in Bangladesh paddy fields and homesteads: participatory action research towards a model design  

Microsoft Academic Search

This paper describes the background, context and process of farmer consultation and participation in research leading to a model design for planting trees in crop fields and homesteads on small private farms in Bangladesh. Planting trees in crop fields is a cultural and technical innovation under development through participatory action-research. Tree planting on homesteads was also a high priority for

D. Hocking; K. Islam

1994-01-01

101

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

PubMed

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

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

2014-01-01

102

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

PubMed Central

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

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

2014-01-01

103

[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

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

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

2014-08-01

104

Simulation of global warming potential (GWP) from rice fields in the Tai-Lake region, China by coupling 1:50,000 soil database with DNDC model  

NASA Astrophysics Data System (ADS)

Quantifying greenhouse gas (GHG) emissions from wetland ecosystems is a relatively new issue in global climate change studies. China has approximately 22% of the world's rice paddies and 38% of the world's rice production, which are crucial to accurately estimate the global warming potential (GWP) at regional scale. This paper reports an application of a biogeochemical model (DeNitrification and DeComposition or DNDC) for quantifying GWP from rice fields in the Tai-Lake region of China. For this application, DNDC is linked to a 1:50,000 soil database, which was derived from 1107 paddy soil profiles compiled during the Second National Soil Survey of China in the 1980-1990s. The simulated results show that the 2.34 Mha of paddy soil cultivated in rice-wheat rotation in the Tai-Lake region emitted about -1.48 Tg C, 0.84 Tg N and 5.67 Tg C as CO 2, N 2O, and CH 4 respectively, with a cumulative GWP of 565 Tg CO 2 equivalent from 1982 to 2000. As for soil subgroups, the highest GWP (26,900 kg CO 2 equivalent ha -1 yr -1) was linked to gleyed paddy soils accounting for about 4.4% of the total area of paddy soils. The lowest GWP (5370 kg CO 2 equivalent ha -1 yr -1) was associated with submergenic paddy soils accounting for about 0.32% of the total area of paddy soils. The most common soil in the area was hydromorphic paddy soils, which accounted for about 53% of the total area of paddy soils with a GWP of 12,300 kg CO 2 equivalent ha -1 yr -1. On a regional basis, the annual averaged GWP in the polder, Tai-Lake plain, and alluvial plain soil regions was distinctly higher than that in the low mountainous and Hilly soil regions. As for administrative areas, the average annual GWP of counties in Shanghai city was high. Conversely, the average annual GWP of counties in Jiangsu province was low. The high variability in soil properties throughout the Tai-Lake region is important and affects the net greenhouse gas emissions. Therefore, the use of detailed soil data sets with high-resolution digital soil maps is essential to improve the accuracy of GWP estimates with process-based models at regional and national scales.

Zhang, Liming; Yu, Dongsheng; Shi, Xuezheng; Weindorf, David C.; Zhao, Limin; Ding, Weixin; Wang, Hongjie; Pan, Jianjun; Li, Changsheng

105

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

PubMed

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

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

2014-01-01

106

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

PubMed Central

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

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

2014-01-01

107

A 3-year field measurement of methane and nitrous oxide emissions from rice paddies in China: Effects of water regime, crop residue, and fertilizer application  

NASA Astrophysics Data System (ADS)

A 3-year field experiment was conducted to simultaneously measure methane (CH4) and nitrous oxide (N2O) emissions from rice paddies under various agricultural managements including water regime, crop residue incorporation, and synthetic fertilizer application. In contrast with continuous flooding, midseason drainage incurred a drop in CH4 fluxes while triggering substantial N2O emission. Moreover, N2O emissions after midseason drainage depended strongly on whether or not fields were waterlogged due to intermittent irrigation. Urea application tended to reduce CH4 emissions but significantly increased N2O emissions. Under a water regime of flooding-midseason drainage-reflooding-moist intermittent irrigation but without water logging (F-D-F-M), both wheat straw and rapeseed cake incorporation increased CH4 emissions by 252%, and rapeseed cake increased N2O by 17% while wheat straw reduced N2O by 19% compared to controls. Seasonal average fluxes of CH4 ranged from 25.4 mg m-2 d-1 when no additional residue was applied under the water regime of flooding-midseason drainage-reflooding to 116.9 mg m-2 d-1 when wheat straw was applied at 2.25 t ha-1 under continuous irrigation flooding. Seasonal average fluxes of N2O varied between 0.03 mg N2O-N m-2 d-1 under continuous flooding and 5.23 mg N2O-N m-2 d-1 under the water regime of F-D-F-M. Both crop residue-induced CH4, ranging from 9 to 15% of the incorporated residue C, and N2O, ranging from 0.01 to 1.78% of the applied N, were dependent on water regime in rice paddies. Estimations of net global warming potentials (GWPs) indicate that water management by flooding with midseason drainage and frequent water logging without the use of organic amendments is an effective option for mitigating the combined climatic impacts from CH4 and N2O in paddy rice production.

Zou, Jianwen; Huang, Yao; Jiang, Jingyan; Zheng, Xunhua; Sass, Ronald L.

2005-06-01

108

[Study on canopy spectral characteristics of paddy polluted by heavy metals].  

PubMed

Because of frequent mining, heavy metals are brought into environment like soils, water and atmosphere, resulting heavy metal contamination in the agricultural region beside mines. Heavy metals contamination causes vegetation stress like destruction of chloroplast structure, chlorophyll content decrease, blunt photosynthesis, etc. Spectral responses to changes in chlorophyll content and photosynthesis make it possible that remote sensing is applied in monitoring heavy metals stress on paddy plants. Field spectroradiometer was used to acquire canopy reflectance spectra of paddy plants contaminated by heavy metals released from local mining. The present study was conducted to (1) investigate discrimination of canopy reflectance spectra of heavy metal polluted and normal paddy plants; (2) extract spectral characteristics of contaminated paddy plants and compare them. By means of correlation analysis, sensitive bands (SB) were firstly picked out from canopy spectra. Secondly, on the basis of these sensitive bands, normalized difference vegetation indices (NDVI) were established, and then red edge position (REP) was extracted from canopy spectra via curve fitting of inverted Gaussian model. As a result of correlation analysis, 460, 560, 660 and 1 100 nm were considered respectively as sensitive band for Pb, Zn, Cu and As concentration in paddy leaves. Furthermore, heavy metal concentrations (Pb, Zn, Cu and As) were significantly correlated with NDVIs (Pb, NDV(510, 810); Zn, NDVI(510, 870; Cu, NDVI(660, 870); As, NDVI(510, 810)). Heavy metals were also significantly correlated with REP, however, the inflexion termed as spectral critical value (SCV) between low and high heavy metals concentrations should be considered during applying REP in remote sensing monitoring. Moreover, NDVI and REP are much better than SB in terms of capability of expressing spectral information. Therefore, heavy metals contamination in paddy plants can be remotely monitored via ground spectroradiometer when NDVI and REP are selected as spectral characteristics. PMID:20384139

Ren, Hong-Yan; Zhuang, Da-Fang; Pan, Jian-Jun; Shi, Xue-Zheng; Shi, Run-He; Wang, Hong-Jie

2010-02-01

109

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)

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.

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

2013-04-01

110

A rice gene for microbial symbiosis, Oryza sativa CCaMK, reduces CH4 flux in a paddy field with low nitrogen input.  

PubMed

Plants have mutualistic symbiotic relationships with rhizobia and fungi by the common symbiosis pathway, of which Ca(2+)/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 (13)C-labeled CH4-feeding experiment. In addition, the natural abundance of (15)N 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

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

2014-03-01

111

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

PubMed Central

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

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

112

Active Region Magnetic Fields. I. Plage Fields  

Microsoft Academic Search

We present observations taken with the Advanced Stokes Polarimeter (ASP) in active-region plages and study the frequency distribution of the magnetic field strength (B), inclination with respect to vertical ( gamma ), azimuthal orientation ( chi ), and filling factor (f). The most common values at disk center are B = 1400 G, gamma < 10 deg, no preferred east-west

V. Martinez Pillet; B. W. Lites; A. Skumanich

1997-01-01

113

Mercury cycling in a flooded rice paddy  

NASA Astrophysics Data System (ADS)

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.

Rothenberg, Sarah E.; Feng, Xinbin

2012-09-01

114

Restoration of methane oxidation abilities of desiccated paddy soils after re-watering  

Microsoft Academic Search

Restoration of CH4-oxidation activities of desiccated paddy soils and the NH4+ effect after watering were investigated in laboratory incubations. Fresh paddy soil collected from an intermittently flooded rice field in Wuxi, Jiangsu province, showed a parabolic relationship between CH4-oxidation activity and soil moisture with an optimum CH4-oxidation rate at 71% water-holding capacity (WHC), while the paddy soil collected from a

Z. Cai; A. R. Mosier

2002-01-01

115

Terrimicrobium sacchariphilum gen. nov., sp. nov., an anaerobic bacterium of the class 'Spartobacteria' in the phylum Verrucomicrobia, isolated from a rice paddy field.  

PubMed

A strictly anaerobic, mesophilic, carbohydrate-fermenting bacterium, designated NM-5T, was isolated from a rice paddy field. Cells of strain NM-5(T) were Gram-stain-negative, non-motile, non-spore-forming, short rods (0.5-0.7 µm×0.6-1.2 µm). The strain grew optimally at 37 °C (growth range 20-40 °C) and pH 7.0 (pH 5.5-8.0). The strain could grow fermentatively on arabinose, xylose, fructose, galactose, glucose, ribose, mannose, cellobiose, lactose, maltose and sucrose. The main end-products of glucose fermentation were acetate and propionate. Organic acids, alcohols and amino acids were not utilized for growth. Yeast extract was not required but stimulated the growth. Nitrate, sulfate, thiosulfate, elemental sulfur, sulfite, and Fe (III) nitrilotriacetate were not used as terminal electron acceptors. The DNA G+C content was 46.3 mol%. The major cellular fatty acids were iso-C14:0, C18:0 and C16:0. 16S rRNA gene sequence analysis revealed that strain NM-5T belongs to the class 'Spartobacteria', subdivision 2 of the bacterial phylum Verrucomicrobia. Phylogenetically, the closest species was 'Chthoniobacter flavus' (89.6% similarity in 16S rRNA gene sequence). A novel genus and species, Terrimicrobium sacchariphilum gen. nov., sp. nov., is proposed. The type strain of the type species is NM-5T (=JCM 17479T=CGMCC 1.5168T). PMID:24535138

Qiu, Yan-Ling; Kuang, Xiao-zhu; Shi, Xiao-shuang; Yuan, Xian-zheng; Guo, Rong-bo

2014-05-01

116

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

Microsoft Academic Search

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

Ralph J. Cicerone; James D. Shetter

1981-01-01

117

Comparison of three models for simulating N2O emissions from paddy fields under water-saving irrigation  

NASA Astrophysics Data System (ADS)

N2O emissions simulated by WNMM, DAYCENT and Crop-DNDC models were compared to the observed data sets from rice-wheat rotation systems under water-saving irrigation at Kunshan City, Jiangsu Province, China. On the basis of the correlation and paired t-test for evaluation, the simulation of N2O emission by Crop-DNDC and WNMM models provided better agreement with the observed data than by DAYCENT model. The daily time step, Crop-DNDC model was consistently the best for predicting daily N2O emissions (R2 = 0.892, n = 28, p > 0.05), and WNMM model performed better (R2 = 0.87, n = 28, p > 0.05). The Crop-DNDC model simulated the seasonal cumulative N2O emissions were the closest to the measured value of 1.07 kg N ha-1, and WNMM and DAYCENT models predicted 8.4% and 15.0% more N2O emissions than that in field experiments. The three models predicted well the seasonal cycle of soil temperature, soil moisture and could provide reliable estimations. The simulation of daily average soil temperature at 10 cm were consistently with the field observed data, which by Crop-DNDC (R2 = 0.92, n = 67, p > 0.05) and WNMM (R2 = 0.91, n = 67, p > 0.05). The comparison of observed to simulated results indicated that soil WFPS was simulated by Crop-DNDC (R2 = 0.52, n = 50, p > 0.05), WNMM (R2 = 0.56, n = 50, p > 0.05) and DAYCENT (R2 = 0.37, n = 50, p > 0.05). Accurate simulation of soil moisture, soil temperature and accurate partitioning of gaseous nitrogen loss into NO, N2O and N2 are challenges for all models.

Wu, Xiarui; Zhang, Ao

2014-12-01

118

Field application of electrokinetic remediation for multi-metal contaminated paddy soil using two-dimensional electrode configuration.  

PubMed

In this study, we evaluated the feasibility of in situ electrokinetic remediation for arsenic (As)-, copper (Cu)-, and lead (Pb)-contaminated soil, in a pilot-scale field application with two-dimensional electrode configurations. Square and hexagonal configurations with different electrode spacing, 1 m and 2 m, were investigated under a constant 100 V. A square configuration with electrode spacing of 2 m removed 61.5 % of As, 11.4 % of Cu, and 0.9 % of Pb, respectively, and a hexagonal configuration with the same spacing showed a higher removal efficiency in top (59 % of As, 0-0.5 m) and middle (53 % of As, 0.5-1.0 m) layers, but much lower removal efficiency in the bottom layer (1-1.5 m), which was thought to be due to groundwater flow through periodic rise and fall of tides. Fractionation analysis showed that As bound to Fe-Mn oxyhydroxide was the main form of As removed by the electrokinetic process. The two-dimensional configuration wasted less electrical energy by Joule heating, and required fewer electrode installations, compared to the one-dimensional electrode configuration. PMID:24338001

Kim, Woo-Seung; Jeon, Eun-Ki; Jung, Ji-Min; Jung, Hong-Bae; Ko, Sung-Hwan; Seo, Chang-Il; Baek, Kitae

2014-03-01

119

Abundance and community composition of methanotrophs in a Chinese paddy soil under long-term fertilization practices  

Microsoft Academic Search

Background, aim, and scope  As the second most important greenhouse gas, methane (CH4) is produced from many sources such as paddy fields. Methane-oxidizing bacteria (methanotrophs) consume CH4 in paddy soil and, therefore, reduce CH4 emission to the atmosphere. In order to estimate the contribution of paddy fields as a source of CH4, it is important to monitor the effects of fertilizer

Yong Zheng; Li-Mei Zhang; Yuan-Ming Zheng; Hongjie Di; Ji-Zheng He

2008-01-01

120

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

Microsoft Academic Search

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

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

1986-01-01

121

Photodegradation of Imidacloprid and Fipronil in Rice–Paddy Water  

Microsoft Academic Search

Photodegradation of insecticides, imidacloprid and fipronil, in rice–paddy water under the ambient temperature was investigated.\\u000a The initial concentrations were set at 58.8 and 3.1 ?g\\/L for imidacloprid and fipronil, respectively, according to their reported\\u000a initial concentrations in the rice–paddy field. The half-lives (DT50) of imidacloprid and fipronil were 24.2 and 36.7 h, respectively. Fipronil desulfinyl was detected as a major metabolite\\u000a and

Dang Quoc Thuyet; Hirozumi Watanabe; Kenichi Yamazaki; Kazuhiro Takagi

2011-01-01

122

Modeling of basin-wide water management for dry-season paddy irrigation with large reservoirs in the Mekong River Basin  

NASA Astrophysics Data System (ADS)

Northeast Thailand, one of the regions in the Mekong River Basin, has less rainfall than adjacent countries and its rainfall is heavily concentrated in rainy seasons (almost 90% of annual rainfall). Therefore, this area is characterized as semi-arid region especially during dry seasons. In this region, rain-fed paddies account for about 90% and this leads to unstable rice production. Against these backgrounds, a number of large irrigation projects have been carried out since the 1970s to increase agricultural productivity. In these projects, a lot of irrigation facilities such as large/medium reservoirs, diversion weirs and irrigation canals were constructed for stable water supply in dry seasons. These projects enable farmers to pursue double rice cropping as rainy- and dry-season cropping in this region. Paddy field irrigation, however, exerts a great influence on water circulation of river basins in Monsoon Asia and modeling of these processes is crucial to understand the hydrological cycle especially in areas where irrigated agriculture is dominant. In this study, to quantify the hydrological cycle in irrigation-dominant basins, we applied a distributed hydrological model incorporating paddy irrigation schemes to the Mun River Basin, one of the tributaries of the Mekong River, in Northeast Thailand, and analyzed water circulation considering complex water use by agricultural activities. The model used in this study consists of four sub-models, such as referential evapotranspiration, cropping pattern/area, agricultural water use, and runoff model in order to estimate various information on agricultural water use. Additionally, water allocation and reservoir operation models were integrated into the hydrological model to account for the water circulation in large irrigation areas. For the analysis, the basin is divided into 10km-mesh and each mesh contains the ratio of 5 land-use category as forest, rain-fed paddy, irrigated paddy, upland field and water area. Irrigation and crop patterns are set as agricultural conditions in each mesh, and then irrigation water and actual evapotranspiration can be estimated according to crop stage and soil moisture. We also modeled water management of 160 reservoirs (10 large reservoirs and 150 medium reservoirs) and water allocation process of 10 large irrigated areas in the basin. The results obtained in this study are as follows: 1) The reservoir operation model reproduced water management such as impoundment of flood discharge during rainy seasons and release of irrigation water controlled by water requirement in downstream irrigation area during dry seasons. 2) The paddy water use and the water allocation models estimated water withdrawals at diversion weirs and water supply in paddy fields depending on water demands in large irrigation areas. 3) Based on the difference in water use patterns between rainy and dry seasons, the cropping model represented the actual conditions of rice planting pattern in both seasons. These results show that the interaction among the sub-models (reservoir operation, paddy water use, water allocation and so on) enables this hydrological model to represent the detailed processes of paddy water use and to evaluate the interaction between hydrological cycle and agricultural activities through anthropogenic water management for paddy irrigation.

Kudo, R.; Masumoto, T.; Horikawa, N.; Yoshida, T.

2012-12-01

123

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

Microsoft Academic Search

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

Giveson Zulu; Masaru Toyota; Shin-ichi Misawa

1996-01-01

124

Methane emission from rice paddies  

Microsoft Academic Search

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

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

1983-01-01

125

Fertilization increases paddy soil organic carbon density*  

PubMed Central

Field experiments provide an opportunity to study the effects of fertilization on soil organic carbon (SOC) sequestration. We sampled soils from a long-term (25 years) paddy experiment in subtropical China. The experiment included eight treatments: (1) check, (2) PK, (3) NP, (4) NK, (5) NPK, (6) 7F:3M (N, P, K inorganic fertilizers+30% organic N), (7) 5F:5M (N, P, K inorganic fertilizers+50% organic N), (8) 3F:7M (N, P, K inorganic fertilizers+70% organic N). Fertilization increased SOC content in the plow layers compared to the non-fertilized check treatment. The SOC density in the top 100 cm of soil ranged from 73.12 to 91.36 Mg/ha. The SOC densities of all fertilizer treatments were greater than that of the check. Those treatments that combined inorganic fertilizers and organic amendments had greater SOC densities than those receiving only inorganic fertilizers. The SOC density was closely correlated to the sum of the soil carbon converted from organic amendments and rice residues. Carbon sequestration in paddy soils could be achieved by balanced and combined fertilization. Fertilization combining both inorganic fertilizers and organic amendments is an effective sustainable practice to sequestrate SOC. PMID:22467369

Wang, Shao-xian; Liang, Xin-qiang; Luo, Qi-xiang; Fan, Fang; Chen, Ying-xu; Li, Zu-zhang; Sun, Huo-xi; Dai, Tian-fang; Wan, Jun-nan; Li, Xiao-jun

2012-01-01

126

Fly ash application in nutrient poor agriculture soils: impact on methanotrophs population dynamics and paddy yields.  

PubMed

There are reports that the application of fly ash, compost and press mud or a combination thereof, improves plant growth, soil microbial communities etc. Also, fly ash in combination with farmyard manure or other organic amendments improves soil physico-chemical characteristics, rice yield and microbial processes in paddy fields. However, the knowledge about the impact of fly ash inputs alone or in combination with other organic amendments on soil methanotrophs number in paddy soils is almost lacking. We hypothesized that fly ash application at lower doses in paddy agriculture soil could be a potential amendment to elevate the paddy yields and methanotrophs number. Here we demonstrate the impact of fly ash and press mud inputs on number of methanotrophs, antioxidants, antioxidative enzymatic activities and paddy yields at agriculture farm. The impact of amendments was significant for methanotrophs number, heavy metal concentration, antioxidant contents, antioxidant enzymatic activities and paddy yields. A negative correlation was existed between higher doses of fly ash-treatments and methanotrophs number (R(2)=0.833). The content of antioxidants and enzymatic activities in leaves of higher doses fly ash-treated rice plants increased in response to stresses due to heavy metal toxicity, which was negatively correlated with rice grain yield (R(2)=0.944) and paddy straw yield (R(2)=0.934). A positive correlation was noted between heavy metals concentrations and different antioxidant and enzymatic activities across different fly ash treated plots.The data of this study indicate that heavy metal toxicity of fly ash may cause oxidative stress in the paddy crop and the antioxidants and related enzymes could play a defensive role against phytotoxic damages. We concluded that fly ash at lower doses with press mud seems to offer the potential amendments to improving soil methanotrophs population and paddy crop yields for the nutrient poor agriculture soils. PMID:23260239

Singh, Jay Shankar; Pandey, Vimal Chandra

2013-03-01

127

OPTIMUM STRATEGY FOR FLUIDIZED BED PADDY DRYING  

Microsoft Academic Search

A feasibility study of paddy drying by fluidization technique was conducted. Operating parameters affecting product quality, drying capacity and energy consumption were investigated. Experimental results showed that drying rate of a paddy kernel was controlled by diffusion. However, drying capacity of a dryer increased with specific air flow rates and drying air temperatures. Energy consumption was reduced when specific air

Somchart Soponronnarit; Somkiat Prachayawarakorn

1994-01-01

128

Geostatistical Estimations of Regional Hydraulic Conductivity Fields  

Microsoft Academic Search

Direct and indirect measurements of hydraulic conductivity (K) are commonly performed, providing information on the magnitude of this parameter at the local scale (tens of centimeters to hundreds of meters) and at shallow depths. By contrast, field information on hydraulic conductivities at regional scales of tens to hundreds of kilometers and at greater depths is relatively scarce. Geostatistical methods allow

D. Patriarche; M. C. Castro; P. Goovaerts

2004-01-01

129

Impacts of climate change on paddy rice yield in a temperate climate.  

PubMed

The crop simulation model is a suitable tool for evaluating the potential impacts of climate change on crop production and on the environment. This study investigates the effects of climate change on paddy rice production in the temperate climate regions under the East Asian monsoon system using the CERES-Rice 4.0 crop simulation model. This model was first calibrated and validated for crop production under elevated CO2 and various temperature conditions. Data were obtained from experiments performed using a temperature gradient field chamber (TGFC) with a CO2 enrichment system installed at Chonnam National University in Gwangju, Korea in 2009 and 2010. Based on the empirical calibration and validation, the model was applied to deliver a simulated forecast of paddy rice production for the region, as well as for the other Japonica rice growing regions in East Asia, projecting for years 2050 and 2100. In these climate change projection simulations in Gwangju, Korea, the yield increases (+12.6 and + 22.0%) due to CO2 elevation were adjusted according to temperature increases showing variation dependent upon the cultivars, which resulted in significant yield decreases (-22.1% and -35.0%). The projected yields were determined to increase as latitude increases due to reduced temperature effects, showing the highest increase for any of the study locations (+24%) in Harbin, China. It appears that the potential negative impact on crop production may be mediated by appropriate cultivar selection and cultivation changes such as alteration of the planting date. Results reported in this study using the CERES-Rice 4.0 model demonstrate the promising potential for its further application in simulating the impacts of climate change on rice production from a local to a regional scale under the monsoon climate system. PMID:23504792

Kim, Han-Yong; Ko, Jonghan; Kang, Suchel; Tenhunen, John

2013-02-01

130

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

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

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

2014-01-01

131

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

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

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

2014-01-01

132

Superheated steam fluidised bed paddy drying  

Microsoft Academic Search

Fluidised bed paddy drying using superheated steam is a newly alternative approach instead of using the conventional hot air. The mechanism of mass transfer for paddy drying in a range of initial moisture content between 25% and 44.5% d.b. is strongly controlled by internal moisture movement inside the kernel and a two-series exponential equation is suitably used to explain its

Chaiyong Taechapairoj; Isares Dhuchakallaya; Somchart Soponronnarit; Somboon Wetchacama; Somkiat Prachayawarakorn

2003-01-01

133

Changes in the Mineral Assemblage of Paddy Soils upon Redox Cycles  

NASA Astrophysics Data System (ADS)

Rice is one of the major cereal crops of global agriculture. World wide more than 10% of the arable land is used for rice production, mainly under temporarily waterlogged conditions. This leads to distinct redox cycles, governing the biogeochemistry of paddy soils. Yet, long-term effects of alternating redox conditions on the soil mineral matrix and properties are still not fully understood. The objective of the project is to elucidate the processes of mineral transformation as related to changing redox conditions and to time of rice cultivation. Long-term effects of rice cultivation on the mineral assemblage were studied along a chronosequence of paddy soils (100, 700 and 2000a paddy soils) developed in comparable parent material in the province of Zhejiang, China. Top soils were analysed for the mineral assemblage and physicochemical properties using x-ray diffraction and chemical analyses, respectively. All studied clay fractions showed a similar clay mineral assemblage (illite, chlorite, kaolinite, vermiculite, smectite). Differences among the paddy sites though could not be related to the time of cultivation. The CECpot of the clay fraction slightly increased from 100 to 2000 a paddy usage, which was partly attributed to a concurrent increase of Corg. With age the Feo/Fed-ratio in both the Alp and Ardp-horizon increased, with a maximum in the Ardp of the 2000 a paddy field. We conclude, that due to an increasing number of redox-cycles, long-term cultivation enhances the formation of microcrystalline Fe-hydroxides in the A-horizons of paddy soils. Chronological changes in the clay mineral assemblage could not be observed in this study.

Vogelsang, Vanessa; Fiedler, Sabine; Jahn, Reinhold

2010-05-01

134

Environmental profile of paddy rice cultivation with different straw management.  

PubMed

Italy is the most important European country in terms of paddy rice production. North Italian districts such as Vercelli, Pavia, Novara, and Milano are known as some of the world's most advanced rice cultivation sites. In 2013 Italian rice cultivation represented about 50% of all European rice production by area, and paddy fields extended for over 216,000 ha. Cultivation of rice involves different agricultural activities which have environmental impacts mainly due to fossil fuels and agrochemical requirements as well as the methane emission associated with the fermentation of organic material in the flooded rice fields. In order to assess the environmental consequences of rice production in the District of Vercelli, the cultivation practices most frequently carried out were inventoried and evaluated. The general approach of this study was not only to gather the inventory data for rice production and quantify their environmental impacts, but also to identify the key environmental factors where special attention must be paid. Life Cycle Assessment methodology was applied in this study from a cradle-to-farm gate perspective. The environmental profile was analyzed in terms of seven different impact categories: climate change, ozone depletion, human toxicity, terrestrial acidification, freshwater eutrophication, marine eutrophication, and fossil depletion. Regarding straw management, two different scenarios (burial into the soil of the straw versus harvesting) were compared. The analysis showed that the environmental impact was mainly due to field emissions, the fuel consumption needed for the mechanization of field operations, and the drying of the paddy rice. The comparison between the two scenarios highlighted that the collection of the straw improves the environmental performance of rice production except that for freshwater eutrophication. To improve the environmental performance of rice production, solutions to save fossil fuel and reduce the emissions from fertilizers (leaching, volatilization) as well as methane emissions should be implemented. PMID:25038430

Fusi, Alessandra; Bacenetti, Jacopo; González-García, Sara; Vercesi, Annamaria; Bocchi, Stefano; Fiala, Marco

2014-10-01

135

Elevated ground-level O3 negatively influences paddy methanogenic archaeal community  

PubMed Central

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

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

2013-01-01

136

Transport of Soil Halides through Rice Paddies: A Viable Mechanism for Rapid Dispersion of the Soil Halide Reservoir  

NASA Astrophysics Data System (ADS)

On short time scales (1-10 years) soil halide concentrations have been assumed to be primarily driven by leaching and deposition processes. Recent results however, have shown that terrestrial plants volatilize soil halides in the form of methyl halides. Emissions of methyl chloride, methyl bromide and methyl iodide represent major pathways for delivery of inorganic halogen radicals to the atmosphere. Inorganic halogen radicals destroy ozone in the stratosphere and modify the oxidative capacity of the lower atmosphere. We have previously shown that rice paddies emit methyl halides and that emissions depend on growth stage of the rice plant as well as field water management. We show here that rice grown in a greenhouse at UCI is capable of volatilizing and/or storing up to 30%, 5%, and 10% of the available chloride, bromide and iodide within the top meter of soil. The percent of plant tissue halide volatilized as methyl halide over the course of the season is calculated to be 0.05%, 0.25% and 85.0% for chloride, bromide and iodide. We compare our greenhouse soil halide concentrations to other commercial rice fields around the world and estimate the e-folding time for soil halides within each region. We suggest that rice agriculture is the driving removal mechanism for halides within rice paddies and that terrestrial plants play a larger role in global cycling of halides than previously estimated.

Redeker, K. R.; Manley, S.; Wang, N.; Cicerone, R.

2002-05-01

137

Persistence Behaviour of Thiamethoxam and Lambda Cyhalothrin in Transplanted Paddy  

Microsoft Academic Search

A field study was conducted in Pre-Kharif season 2007 on paddy to determine the persistence of thiamethoxam (12.6%) and lambda\\u000a cyhalothrin (9.4%) [in a ‘Readymix’ formulation Alika 247 ZC], following the application of 33 g. a.i. ha?1 (T1) and 66 g. a.i. ha?1 (T2). Spraying of insecticide was done during milking stage of the crop (63 days after transplantation). Thiamethoxam and lambda\\u000a cyhalothrin

Suhrid Ranjan Barik; Pritam Ganguly; Samir Kumar Kunda; Ramen Kumar Kole; Anjan Bhattacharyya

2010-01-01

138

Long-term field fertilization alters the diversity of autotrophic bacteria based on the ribulose-1,5-biphosphate carboxylase/oxygenase (RubisCO) large-subunit genes in paddy soil.  

PubMed

Carbon dioxide (CO(2)) assimilation by autotrophic bacteria is an important process in the soil carbon cycle with major environmental implications. The long-term impact of fertilizer on CO(2) assimilation in the bacterial community of paddy soils remains poorly understood. To narrow this knowledge gap, the composition and abundance of CO(2)-assimilating bacteria were investigated using terminal restriction fragment length polymorphism and quantitative PCR of the cbbL gene [that encodes ribulose-1,5-biphosphate carboxylase/oxygenase (RubisCO)] in paddy soils. Soils from three stations in subtropical China were used. Each station is part of a long-term fertilization experiment with three treatments: no fertilizer (CK), chemical fertilizers (NPK), and NPK combined with rice straw (NPKM). At all of the stations, the cbbL-containing bacterial communities were dominated by facultative autotrophic bacteria such as Rhodopseudomonas palustris, Bradyrhizobium japonicum, and Ralstonia eutropha. The community composition in the fertilized soil (NPK and NPKM) was distinct from that in unfertilized soil (CK). The bacterial cbbL abundance (3-8?×?10(8) copies g soil(-1)) and RubisCO activity (0.40-1.76 nmol CO(2) g soil(-1) min(-1)) in paddy soils were significantly positively correlated, and both increased with the addition of fertilizer. Among the measured soil parameters, soil organic carbon and pH were the most significant factors influencing the community composition, abundance, and activity of the cbbL-containing bacteria. These results suggest that long-term fertilization has a strong impact on the activity and community of cbbL-containing bacterial populations in paddy soils, especially when straw is combined with chemical fertilizers. PMID:22159889

Yuan, Hongzhao; Ge, Tida; Wu, Xiaohong; Liu, Shoulong; Tong, Chengli; Qin, Hongling; Wu, Minna; Wei, Wenxue; Wu, Jinshui

2012-08-01

139

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

PubMed Central

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

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

2013-01-01

140

2000 years of paddy soil development - gain and loss of soil carbon  

Microsoft Academic Search

The long-term impact of lowland rice growing on C stocks in soils was evaluated in the coastal region of subtropical China. During the past 2000 years new farmland was created through consecutive land reclamation by protective dikes, providing a unique chronosequence of soil formation under agricultural use. Parts of the land were used for paddy rice, other parts for a

A. Koelbl; K. Kalbitz; S. Fiedler; T. Braeuer; P. M. Grootes; Z. Cao; R. Jahn; V. Vogelsang; L. Wissing; I. Koegel-Knabner

2010-01-01

141

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

Microsoft Academic Search

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

Carles Flaquer; Ignacio Torre; Ramon Ruiz-Jarillo

2006-01-01

142

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

NASA Astrophysics Data System (ADS)

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.

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

143

Phylogenetic Distribution of the Capsid Assembly Protein Gene (g20) of Cyanophages in Paddy Floodwaters in Northeast China  

PubMed Central

Numerous studies have revealed the high diversity of cyanophages in marine and freshwater environments, but little is currently known about the diversity of cyanophages in paddy fields, particularly in Northeast (NE) China. To elucidate the genetic diversity of cyanophages in paddy floodwaters in NE China, viral capsid assembly protein gene (g20) sequences from five floodwater samples were amplified with the primers CPS1 and CPS8. Denaturing gradient gel electrophoresis (DGGE) was applied to distinguish different g20 clones. In total, 54 clones differing in g20 nucleotide sequences were obtained in this study. Phylogenetic analysis showed that the distribution of g20 sequences in this study was different from that in Japanese paddy fields, and all the sequences were grouped into Clusters ?, ?, ? and ?. Within Clusters ? and ?, three new small clusters (PFW-VII?-IX) were identified. UniFrac analysis of g20 clone assemblages demonstrated that the community compositions of cyanophage varied among marine, lake and paddy field environments. In paddy floodwater, community compositions of cyanophage were also different between NE China and Japan. PMID:24533125

Jing, Ruiyong; Liu, Junjie; Yu, Zhenhua; Liu, Xiaobing; Wang, Guanghua

2014-01-01

144

Arsenic release from paddy soils during monsoon flooding  

NASA Astrophysics Data System (ADS)

Bangladesh relies heavily on groundwater for the irrigation of dry-season rice. However, the groundwater used for irrigation often contains high concentrations of arsenic, potentially jeopardizing the future of rice production in the country. In seasonally flooded fields, topsoil arsenic concentrations decrease during the monsoon season, suggesting that flooding attenuates arsenic accumulation in the soils. Here we examine the chemistry of soil porewater and floodwater during the monsoon season in rice paddies in Munshiganj, Bangladesh, to assess whether flooding releases significant quantities of arsenic from the soils. We estimate that between 51 and 250mgm-2 of soil arsenic is released into floodwater during the monsoon season. This corresponds to a loss of 13-62% of the arsenic added to soils through irrigation each year. The arsenic was distributed throughout the entire floodwater column by vertical mixing and was laterally removed when the floodwater receded. We conclude that monsoon floodwater removes a large amount of the arsenic added to paddy soils through irrigation, and suggest that non-flooded soils are particularly at risk of arsenic accumulation.

Roberts, Linda C.; Hug, Stephan J.; Dittmar, Jessica; Voegelin, Andreas; Kretzschmar, Ruben; Wehrli, Bernhard; Cirpka, Olaf A.; Saha, Ganesh C.; Ashraf Ali, M.; Badruzzaman, A. Borhan M.

2010-01-01

145

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...

2009-04-09

146

[Diversity of microbial genes in paddy soil stressed by cadmium using DGGE].  

PubMed

Variations of diversity of microbial genes in submerged paddy soil stressed by heavy metal cadmium were studied using modern molecular biotechnology which includes directly extracting total DNA from paddy soil, amplifying 16S rDNA and their V3 variable region by PCR, the denaturing gradient gel electrophoresis (DGGE). Two methods for extraction and purification of microbial DNA were compared. Bacterial communities were quantified by analyzing the DGGE band patterns. The genetic clusters and correlative comparison of bacterial communities were analyzed based on the DGGE finger-print. The results showed that there are some significant differences between bacterial communities in paddy soils treated with different concentrations of cadmium. The information about effect of cadium on microbial population based on molecular biological techniques are conformed with that from traditional methods, but that obtained about variations of microbial genes in paddy soil is much more than results based on the latter methods. It could provide a new way and foundation to research microbial gene diversity in contaminated environment. PMID:15623038

Duan, Xue-jun; Min, Hang

2004-09-01

147

Fate of pesticides in combined paddy rice-fish pond farming systems in northern Vietnam.  

PubMed

During the last decades, high population growth and export-oriented economics in Vietnam have led to a tremendous intensification of rice production, which in turn has significantly increased the amount of pesticides applied in rice cropping systems. Since pesticides are toxic by design, there is a natural concern on the impact of their presence in the environment on human health and environmental quality. The present study was designed to examine the water regime and fate of pesticides (fenitrothion, dimethoate) during two consecutive rice crop seasons in combined paddy rice-fish pond farming systems in northern Vietnam. Major results revealed that 5 and 41% (dimethoate), and 1 and 17% (fenitrothion) of the applied mass of pesticides were lost from the paddy field to the adjacent fish pond during spring and summer crop seasons, respectively. The decrease of pesticide concentration in paddy surface water was very rapid with dissipation half-life values of 0.3 to 0.8 and 0.2 d for dimethoate and fenitrothion, respectively. Key factors controlling the transport of pesticides were water solubility and paddy water management parameters, such as hydraulic residence time and water holding period. Risk assessment indicates that the exposure to toxic levels of pesticides for aquaculture (, ) is significant, at least shortly after pesticide application. PMID:22370414

Anyusheva, Maria; Lamers, Marc; La, Nguyen; Nguyen, Van Vien; Streck, Thilo

2012-01-01

148

The economics of irrigated paddy in Usangu Basin in Tanzania: water utilization, productivity, income and livelihood implications  

NASA Astrophysics Data System (ADS)

Globally, there is a general lack of consensus on how the available water resources can be allocated efficiently and equitably among its competing uses. In irrigated agriculture, this decodes to the central question of how this sector can be balanced in the manner that it produces more ‘crops per drop’ using less water and releasing adequate water for use by other sectors while concurrently enhancing rural income and livelihoods. This requires that the values and costs of irrigated agriculture, at all levels, are well understood and appropriate interventions made. Based on this ground, this paper presents an economic analysis of the value of irrigated paddy in Usangu basin. It attempts to answer the question of what will be the effects if farmers in Usangu stop producing irrigated paddy. The analysis shows that: (a) about 576 mm 3 of water--currently consumed in paddy irrigation, or 345.6 mm 3--traded inter-regionally as “virtual water” would be utilized in alternative ways, either as evaporation from seasonal swamps within the basin or made available for other intersectoral uses, (b) there will be a shrinkage in the annual paddy supply (both at the local and national levels) of about 105,000 t of paddy (66,000 t of rice)-equivalent to 14.4% of the total annual paddy production in Tanzania, (c) an opportunity cost of about US15.9 million will be incurred annually (equivalent to US530.95 per annum per household practicing irrigated paddy in Usangu), and d) the country’s current account of the balance of payments will be affected by an average of US$15.9 million per annum. The effect will either be in form of annual decline in rice exports or increase in imports depending on the country’s supply and demand for rice.

Kadigi, Reuben M. J.; Kashaigili, Japhet J.; Mdoe, Ntengua S.

149

Active Region Emissions and Coronal Field Extrapolations  

Microsoft Academic Search

With vector magnetographs set to fly on the Solar--B mission, the extrapolation of photospheric magnetic fields into the corona will be increasingly important. As the techniques of coronal field extrapolations grow more sophisticated, we require a more powerful means to test them and to make full use of the information they contain. Radio data can play an important role in

J. Lee; S. M. White; M. R. Kundu; Z. Mikic

1999-01-01

150

A Case Study for Salt Injury on Paddy Rice due to Ground Liquefaction Caused by the 2011 off the Pacific Coast of Tohoku Earthquake in Japan  

NASA Astrophysics Data System (ADS)

About 24000 ha of farmlands were heavily damaged by the 2011 off the Pacific Coast of Tohoku Earthquake in the following two patterns; (i) an invasion of the sea water caused by tsunami in the coastal agricultural areas, (ii) a ground liquefaction around inland rivers. In the past case, ground liquefaction caused damage, for example, cracks or mixing sand boil into topsoil. This is the first report on a case of salt injury to paddy rice due to ground liquefaction. Rice paddies along the downstream of the Tone River were suffered from a large amount of sand boils due to the ground liquefaction. At one paddy fields at 50 km from mouth of the Tone River, farmers temporarily repaired their paddy fields and planted rice in may, 2011. The surface of the rice paddy field was speckled with sand boils. A week after planting, the authors incidentally found salt injury on the growth of rice plant at the paddy fields. Sand boil contained much more chlorine ion, sodium, sulfide ion than preexisting top soil. This data suggested that sand boil contained salt moved from underground to the surface of paddy fields. During May and September in 2011, the salt injury paddy fields was supplied irrigation water pumping from drainage canal, because irrigation facilities was destroyed by ground liquefaction. The electrical conductivity (EC) of water in the drainage canal ranged from 2 to 8, much higher than the salt-tolerant limit for rice. Consequently, the yield of the rice in the salt injury rice field due to ground liquefaction ranged from 55 to 107 kg/10a, much lower than the usual (about 450 kg/10a). The result of the yield was 55 kg/10a got around sand boil, on the other hand, the yield was 107 kg/10a got preexisting top soil area using drainage water contained salt. The yield of the whole paddy fields which size was 50 a was bad, but the yield around sand boil area was much worse. This case reported that chemical components in the boiled materials should be paid more attention if rice paddies will damaged by grond liquefaction.

Zukemura, C.; Kitagawa, I.; Wakasugi, K.; Haraguchi, N.

2012-12-01

151

STOCHASTIC METHODOLOGY FOR REGIONAL WIND FIELD MODELING  

EPA Science Inventory

Three-dimensional regional scale (1000 km) air quality simulation models require hourly inputs of U and V wind components for each vertical layer of the model and for each grid cell in the horizontal. he standard North American meteorological observation network is used to derive...

152

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

NASA Astrophysics Data System (ADS)

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.

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

2009-12-01

153

??????????????????????????????????????? The moisture reduction of Paddy by Bamboo charcoal powder  

Microsoft Academic Search

The aim of this research is to study the moisture reduction of paddy by using bamboo charcoal powder as adsorption media. As well known that bamboo charcoal has an good ability for moisture adsorption, therefore; this work is also choose its for removing water from paddy until close to the storage moisture content. Effect of bulk density of bamboo charcoal

Songchai Wiriyaumpaiwong; Ittipol Thampiban; Panya Pamenapo

154

Detection of Desulfotomaculum in an Italian rice paddy soil by 16S ribosomal nucleic acid analyses  

Microsoft Academic Search

Two specific primers were developed for the amplification of 16S rRNA genes of Desulfotomaculum lineage 1 to detect members of the genus Desulfotomaculum in rice field soil. The combination of both primers in PCR allowed the specific amplification and cloning of ten 16S rDNA sequences of this group from rice paddy soil DNA extracts. The phylogenetic analysis showed that these

Stephan Stubner; Katja Meuser

2000-01-01

155

Modelling the earth's magnetic field from global to regional scales  

E-print Network

Modelling the earth's magnetic field from global to regional scales J.-J. Schott1 and E. Thébault2 15, 2010 Abstract To appear as: Schott, J.J and E. Thébault, Modelling the earth's magnetic field modelling of the Earth's magnetic field. The ubiquity of this topic through sessions is a nice tribute paid

Thébault, Erwan

156

Magnetic and velocity fields of active regions  

NASA Astrophysics Data System (ADS)

We have observed about 15 active regions on the Sun, with the Advanced Stokes Polarimeter and Dick Dunn Telescope at NSO/SP to map the Stokes parameters in the photospheric Fe 6302.5 Å and chromospheric Mg i 5173 Å lines, during 1999-2002. The observations are corrected for dark current, gain, instrumental polarization and cross-talk using ASP pipeline. The wavelength calibration is carried out using the O_2 telluric line 6302 Å which is also present in the observations. The photospheric and chromospheric longitudinal magnetograms are made from the Stokes V profiles, which were inter-calibrated with the Kitt Peak magnetograms. The plasma motions are inferred from the line bisector measurements at different positions of the spectral line. In this paper we present the height dependence of Doppler velocity scatter plots of a sunspot in the photospheric Fe i 6302 Å line.

Choudhary, D. P.; Gosain, S.

157

Impact of Rice Paddies Plantation on Surface Water Quality in Kelantan, Malaysia  

Microsoft Academic Search

Many parts of the agricultural land in Kelantan, Ma laysia are used for paddy and most of developed wat er resources are used for paddy irrigation. A study on the impact of rice paddies plantation on surface w ater quality was carried out in paddy plantation at Lada ng Merdeka Ismail Mulong, Kelantan. The objective of the study was to

Abdul Manaff Mahmood; Noriah Abdullah

158

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

Microsoft Academic Search

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

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

2008-01-01

159

Evaluation of soil quality parameters in a tropical paddy soil amended with rice residues and tree litters  

Microsoft Academic Search

Laboratory and greenhouse experiments were conducted to study the effects of applications of rice residue and Pongamia pinnata and Azadirachta indica leaf litters on biochemical properties (extraction yield of humus, composition of humus, microbial biomass carbon, activities of urease and acid phosphatase) of a lowland rice soil under flooded conditions. Bulk soil sample collected from the Mandya paddy fields was

B. K. Rajashekhara Rao; R. Siddaramappa

2008-01-01

160

Transformation of marine sediment to paddy soil: Primary marine, lacustrine, and land plant lipids  

NASA Astrophysics Data System (ADS)

More than fifty percent of the world's population feeds on rice. The continuous population increase and urban sprawl leads to an ever-increasing demand for new rice cultivation area, in particular China. For centuries suitable coastal areas in China have been exploited for land reclamation, i.e. conversion of coastal marine and lacustrine marshlands into rice paddy fields. Flooded rice paddies are considered one of the major biogenic sources of methane into the atmospheric. Methane is thought to be about 30 times more efficient as greenhouse gas, when compared to carbon dioxide. Overall, rice fields are assumed to contribute app. 10-25% to global CH4 production. It is thus paramount importance to study the effects of increasing rice cultivation and land reclamation in China. For global carbon cycle investigation, it is crucial whether paddy soils, due to their large extent and higher carbon turnover, serve as carbon (CO2) sinks or sources. Here we present results from a chronosequence study of paddy soils with different and well known starting dates of cultivation, in the Zhejiang province (Yangtze River delta) by land reclamation through the building of protective dikes over the past 2000 years. Two end members of natural sediments subjected to land reclamation, a marine tidal mudflat in the Yangtze delta and a coastal lake, represent the substrate on which the paddy soil evolution started. Dike systems were constructed 2000, 1000, 700, 300, 100, and 50 years before present. We are thus able to follow the evolution of rice paddy soils developed on marine sediments using eight well defined tie-points. This chronosequence is then used for assessing the relative proportion of primary marine or lacustrine organic matter preserved in present day soils and to identify the amount and composition of organic matter added since cultivation started. Paddy soil management introduces rice plants debris and exudates as well as rice-associated microbial biomass (covered in a separate contribution) into soils. Management practises involve burning of rice straw on fields, thus adding biomass combustion residues that either may be particularly stable (e.g. PAH) or highly reactive (alkenes resulting from dehydration of alcohols). Bulk parameters reveal that the five field replicates taken at each site are highly compatible, with standard deviations usually between 0.1 to 5.0 % depending on site and/or parameter. This is better than expected and proves that the samples are representative for each cropping site. The n- and isoalkane composition also proved to be very systematic and reproducible. The marine end-member shows a broad n-alkane envelope from nC13 to nC40, with a maximum of nC31 and low abundance of nC17 and nC32+ alkanes. The lacustrine site also reveals a broad n-alkane envelope and a maximum of nC31 but shows higher relative abundance of nC17, nC23 and nC25 alkanes in addition to a C20-HBI. These biomarkers for aquatic macrophytes and diatoms were also found in minor proportions in paddy soils due to flooding with lacustrine water. Paddy n-alkane patterns were dominated by nC29 which systematically increased in abundance for older paddy soils. Paddy soil n-alkane patterns from the chronosequence are similar and related to the marine pattern. Combustion of rice straw on the field is a common management practise for nutrient return to soils. A rice straw ash sample collected in the field revealed a series of nC13 to nC37 n-alkane/alkene doublets with low odd over even predominance. As no alkenes were found in paddy soils, very fast diagenetic conversion of reactive alkenes must occur. Soil organic matter and aliphatics content increased six fold over a cultivation time of 2000 years, identifying paddies as CO2 sinks in the global carbon cycle.

Mueller-Niggemann, Cornelia; Cao, Zhihong; Schwark, Lorenz

2010-05-01

161

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

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

162

Efficacy of Aquatain, a Monomolecular Film, for the Control of Malaria Vectors in Rice Paddies  

PubMed Central

Background Rice paddies harbour a large variety of organisms including larvae of malaria mosquitoes. These paddies are challenging for mosquito control because their large size, slurry and vegetation make it difficult to effectively apply a control agent. Aquatain, a monomolecular surface film, can be considered a suitable mosquito control agent for such breeding habitats due to its physical properties. The properties allow Aquatain to self-spread over a water surface and affect multiple stages of the mosquito life cycle. Methodology/Principal Findings A trial based on a pre-test/post-test control group design evaluated the potential of Aquatain as a mosquito control agent at Ahero rice irrigation scheme in Kenya. After Aquatain application at a dose of 2 ml/m2 on rice paddies, early stage anopheline larvae were reduced by 36%, and late stage anopheline larvae by 16%. However, even at a lower dose of 1 ml/m2 there was a 93.2% reduction in emergence of anopheline adults and 69.5% reduction in emergence of culicine adults. No pupation was observed in treated buckets that were part of a field bio-assay carried out parallel to the trial. Aquatain application saved nearly 1.7 L of water in six days from a water surface of 0.2 m2 under field conditions. Aquatain had no negative effect on rice plants as well as on a variety of non-target organisms, except backswimmers. Conclusions/Significance We demonstrated that Aquatain is an effective agent for the control of anopheline and culicine mosquitoes in irrigated rice paddies. The agent reduced densities of aquatic larval stages and, more importantly, strongly impacted the emergence of adult mosquitoes. Aquatain also reduced water loss due to evaporation. No negative impacts were found on either abundance of non-target organisms, or growth and development of rice plants. Aquatain, therefore, appears a suitable mosquito control tool for use in rice agro-ecosystems. PMID:21738774

Bukhari, Tullu; Takken, Willem; Githeko, Andrew K.; Koenraadt, Constantianus J. M.

2011-01-01

163

Observation of methane fluxes using eddy covariance technique and relaxed eddy accumulation techniques simultaneously over rice paddies in Taiwan  

NASA Astrophysics Data System (ADS)

In the past decades, more and more attention was given to the increase of atmospheric methane concentration from the scientific community. Methane is one of greenhouse gases with a global warming potential 21 times greater than carbon dioxide on a 100-year horizon. Rice paddy fields were considered as a major source for methane and so far there are few studies where the eddy covariance (EC) technique has been used to measure methane fluxes from rice paddy fields, especially in Asia. Therefore, in this study we used EC technique and relaxed eddy accumulation (REA) method simultaneously to observe the methane fluxes over rice paddy, fertilized with pig manure, in Taiwan from 22th February to 5th June in 2012. A suit of Micrometeorologial variables and water table depth were measured in conjunction with the fluxes. The results showed that the rice paddy field was source of methane during most of the study period and the observed methane fluxes ranged between - 0.5 and 13 ?g m-2 s-1. and the maximum values usually occurred in the afternoon. A significant methane emission was observed in the first one and a half month after transplanting. Comparison of daily methane fluxes measured by EC and REA showed generally good agreement between both methods with a coefficient of determination of 0.81, although the magnitude of methane fluxes measured by REA were slightly lower than those by EC. During the continuous flooded period, the methane fluxes can be depicted well by a function of soil temperature with an exponential form. Sudden pulses of methane fluxes were observed when drained for the removal of obstruction which hindered the methane diffuse from the soil to the atmosphere. During fallow period between growth periods, the paddy fields was a sink of methane where the methane uptake was about 0.5?g m-2 s-1 around noon.

Tang, M.; Tsai, J.; Tsuang, B.; Feng, P.; Kuo, P.

2012-12-01

164

Computation of the Potential Magnetic Field in Solar Active Regions  

NASA Astrophysics Data System (ADS)

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.

Sadykov, V.; Zimovets, I.

2014-10-01

165

WSRT Observations of the Hubble Deep Field Region  

E-print Network

We present deep WSRT 1.4 GHz observations of the Hubble Deep Field region. At the 5 sigma level, the WSRT clearly detects 85 regions of radio emission in a 10' x 10' field centred on the HDF. Eight of these regions fall within the HDF itself, four of these are sources that have not previously been detected at 1.4 GHz, although two of these are VLA detections at 8.5GHz. The two new radio sources detected by the WSRT are identified with relatively bright (I<21m) moderate redshift spiral and irregular type galaxies. In the full field, the WSRT detects 22 regions of emission that were not previously detected by the VLA at 1.4GHz. At least two of these are associated with nearby, extended star-forming galaxies.

M. A. Garrett; A. G. de Bruyn; M. Giroletti; W. A. Baan; R. T. Schilizzi

2000-08-31

166

Soil physicochemical and biological properties of paddy-upland rotation: a review.  

PubMed

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

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

2014-01-01

167

Identification of active denitrifiers in rice paddy soil by DNA- and RNA-based analyses.  

PubMed

Denitrification occurs markedly in rice paddy fields; however, few microbes that are actively involved in denitrification in these environments have been identified. In this study, we used a laboratory soil microcosm system in which denitrification activity was enhanced. DNA and RNA were extracted from soil at six time points after enhancing denitrification activity, and quantitative PCR and clone library analyses were performed targeting the 16S rRNA gene and denitrification functional genes (nirS, nirK and nosZ) to clarify which microbes are actively involved in denitrification in rice paddy soil. Based on the quantitative PCR results, transcription levels of the functional genes agreed with the denitrification activity, although gene abundance did not change at the DNA level. Diverse denitrifiers were detected in clone library analysis, but comparative analysis suggested that only some of the putative denitrifiers, especially those belonging to the orders Neisseriales, Rhodocyclales and Burkholderiales, were actively involved in denitrification in rice paddy soil. PMID:22972387

Yoshida, Megumi; Ishii, Satoshi; Fujii, Daichi; Otsuka, Shigeto; Senoo, Keishi

2012-01-01

168

Identification of Active Denitrifiers in Rice Paddy Soil by DNA- and RNA-Based Analyses  

PubMed Central

Denitrification occurs markedly in rice paddy fields; however, few microbes that are actively involved in denitrification in these environments have been identified. In this study, we used a laboratory soil microcosm system in which denitrification activity was enhanced. DNA and RNA were extracted from soil at six time points after enhancing denitrification activity, and quantitative PCR and clone library analyses were performed targeting the 16S rRNA gene and denitrification functional genes (nirS, nirK and nosZ) to clarify which microbes are actively involved in denitrification in rice paddy soil. Based on the quantitative PCR results, transcription levels of the functional genes agreed with the denitrification activity, although gene abundance did not change at the DNA level. Diverse denitrifiers were detected in clone library analysis, but comparative analysis suggested that only some of the putative denitrifiers, especially those belonging to the orders Neisseriales, Rhodocyclales and Burkholderiales, were actively involved in denitrification in rice paddy soil. PMID:22972387

Yoshida, Megumi; Ishii, Satoshi; Fujii, Daichi; Otsuka, Shigeto; Senoo, Keishi

2012-01-01

169

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

PubMed Central

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

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

2014-01-01

170

Assessing energy efficiencies and greenhouse gas emissions under bioethanol-oriented paddy rice production in northern Japan.  

PubMed

To establish energetically and environmentally viable paddy rice-based bioethanol production systems in northern Japan, it is important to implement appropriately selected agronomic practice options during the rice cultivation step. In this context, effects of rice variety (conventional vs. high-yielding) and rice straw management (return to vs. removal from the paddy field) on energy inputs from fuels and consumption of materials, greenhouse gas emissions (fuel and material consumption-derived CO(2) emissions as well as paddy soil CH(4) and N(2)O emissions) and ethanol yields were assessed. The estimated ethanol yield from the high-yielding rice variety, "Kita-aoba" was 2.94 kL ha(-1), a 32% increase from the conventional rice variety, "Kirara 397". Under conventional rice production in northern Japan (conventional rice variety and straw returned to the paddy), raising seedlings, mechanical field operations, transportation of harvested unhulled brown rice and consumption of materials (seeds, fertilizers, biocides and agricultural machinery) amounted to 28.5 GJ ha(-1) in energy inputs. The total energy input was increased by 14% by using the high-yielding variety and straw removal, owing to increased requirements for fuels in harvesting and transporting harvested rice as well as in collecting, loading and transporting rice straw. In terms of energy efficiency, the variation among rice variety and straw management scenarios regarding rice varieties and rice straw management was small (28.5-32.6 GJ ha(-1) or 10.1-14.0 MJ L(-1)). Meanwhile, CO(2)-equivalent greenhouse gas emissions varied considerably from scenario to scenario, as straw management had significant impacts on CH(4) emissions from paddy soils. When rice straw was incorporated into the soil, total CO(2)-equivalent greenhouse gas emissions for "Kirara 397" and "Kita-aoba" were 25.5 and 28.2 Mg CO(2) ha(-1), respectively; however, these emissions were reduced notably for the two varieties when rice straw was removed from the paddy fields in an effort to mitigate CH(4) emissions. Thus, rice straw removal avers itself a key practice with respect to lessening the impacts of greenhouse gas emissions in paddy rice-based ethanol production systems in northern Japan. More crucially, the rice straw removed is available for ethanol production and generation of heat energy with a biomass boiler, all elements required for biomass-to-ethanol transformation steps including saccharification, fermentation and distillation. This indicates opportunities for further improvement in energy efficiency and reductions in greenhouse gas emissions under whole rice plant-based bioethanol production systems. PMID:21126818

Koga, Nobuhisa; Tajima, Ryosuke

2011-03-01

171

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...

172

Modelling the fate of pesticides in paddy rice-fish pond farming system in Northern Vietnam  

NASA Astrophysics Data System (ADS)

During the last decade rice production in Vietnam has tremendously increased due to the introduction of new high yield, short duration rice varieties and an increased application of pesticides. Since pesticides are toxic by design, there is a natural concern on the possible impacts of their presence in the environment on human health and environment quality. In North Vietnam, lowland and upland rice fields were identified to be a major non-point source of agrochemical pollution to surface and ground water, which are often directly used for domestic purposes. Field measurements, however, are time consuming, costly and logistical demanding. Hence, quantification, forecast and risk assessment studies are hampered by a limited amount of field data. One potential way to cope with this shortcoming is the use of process-based models. In the present study we developed a model for simulating short-term pesticide dynamics in combined paddy rice field - fish pond farming systems under the specific environmental conditions of south-east Asia. Basic approaches and algorithms to describe the key underlying biogeochemical processes were mainly adopted from the literature to assure that the model reflects the current standard of scientific knowledge and commonly accepted theoretical background. The model was calibrated by means of the Gauss-Marquardt-Levenberg algorithm and validated against measured pesticide concentrations (dimethoate and fenitrothion) during spring and summer rice crop season 2008, respectively, of a paddy field - fish pond system typical for northern Vietnam. First simulation results indicate that our model is capable to simulate the fate of pesticides in such paddy - fish pond farming systems. The model efficiency for the period of calibration, for example, was 0.97 and 0.95 for dimethoate and fenitrothion, respectively. For the period of validation, however, the modeling efficiency slightly decreased to 0.96 and 0.81 for dimethoate and fenitrothion, respectively. In our presentation we will picture key model features and algorithms and demonstrate that our model provides a useful and appropriate tool for analyzing and quantifying the transport and behavior of pesticides in paddy rice farming systems.

Lamers, M.; Nguyen, N.; Streck, T.

2012-04-01

173

Drying characteristics of paddy in an integrated dryer.  

PubMed

Drying characteristics of paddy (long grain variety PR-118 procured from PAU, Ludhiana) in an integrated dryer using single as well as combined heating source was studied at different air temperatures. The integrated dryer comprises three different air heating sources such as solar, biomass and electrical. Drying of paddy occurred in falling rate period. It was observed that duration of drying of paddy from 22 to 13 % moisture content (w.b.) was 5-9 h depending upon the source of energy used. In order to select a suitable drying curve, six thin layer-drying models (Newton, Page, Modified Page, Henderson and Pabis, Logarithmic and Wang and Singh) were fitted to the experimental moisture ratio data. Among the mathematical models investigated, Wang and Singh model best described the drying behaviour of paddy using solar, biomass and combined heating sources with highest coefficient of determination (r (2)) values and least chi-square, ? (2), mean bias error (MBE) and root mean square error (RMSE) values. However, Page model adequately described the drying behavior of paddy using electrical heating source. PMID:24741181

Manikantan, M R; Barnwal, P; Goyal, R K

2014-04-01

174

Methane emission from single cropping rice paddies amended different manures  

SciTech Connect

Methane emission fluxes were determined from single cropping rice paddies amended with different manures through a productively comparative experiment. The average fluxes in the whole growth season ranged from 3.92 to 10.96 mg/m{sup 2}.hr. The compost amended paddies gave the highest emission fluxes of 10.26 mg/m{sup 2}.hr, while the fluxes from the other manure amended paddies ranked as follows: horse dung biogas digester sediment 10.02, chemical fertilizer only 8.81, nightsoil biogas sediment 7.76, chicken dropping biogas digester sediment 4.48 and pig dung biogas digester sediment 3.92 mg/m{sup 2}.hr. The latter 3 sediments gave the significant less ({alpha} < 0.05) fluxes than compost. The highest fluxes peaks of all treated paddies appeared unanimously between the stages of the midtillering and the earing, with a half of total CH{sub 4} emissions were produced in this period which could be chosen as the key period for control of CH{sub 4} emission from the single cropping rice paddies. The positive correlation of the fluxes with the temperatures in 5 cm soil layers and the negative correlation of the fluxes with the rice yields, the soil N and P{sub 2}O{sub 5} contents were also observed.

Du Daodeng; Tao Zhan [Agro-Environ. Prot. Inst., Tianjin (China)

1996-12-31

175

Phase unwrapping using region-based markov random field model.  

PubMed

Phase unwrapping is a classical problem in Magnetic Resonance Imaging (MRI), Interferometric Synthetic Aperture Radar and Sonar (InSAR/InSAS), fringe pattern analysis, and spectroscopy. Although many methods have been proposed to address this problem, robust and effective phase unwrapping remains a challenge. This paper presents a novel phase unwrapping method using a region-based Markov Random Field (MRF) model. Specifically, the phase image is segmented into regions within which the phase is not wrapped. Then, the phase image is unwrapped between different regions using an improved Highest Confidence First (HCF) algorithm to optimize the MRF model. The proposed method has desirable theoretical properties as well as an efficient implementation. Simulations and experimental results on MRI images show that the proposed method provides similar or improved phase unwrapping than Phase Unwrapping MAx-flow/min-cut (PUMA) method and ZpM method. PMID:21096819

Dong, Ying; Ji, Jim

2010-01-01

176

The history, development, and regional significance of Ruston Field  

SciTech Connect

The Ruston gas field lies just north of Ruston, Lincoln Parish, Louisiana, 70 mi east of Shreveport, Louisiana. The field covers a surface area of 64.5 sections or approximately 41,280 ac. The Ruston lies within a trend containing many Lower Cretaceous and Upper Jurassic gas reservoirs on the northern flank of the Gulf Coast geosyncline, along the northern flank of the North Louisiana Salt Dome basin. Within the belt of production, several prolific Cotton Valley strandline plays exist at Ruston along with many different Hosston pays. More than 40 zones produce natural gas and oil from seven formations in the field. Several of the sands are totally structurally controlled, but many have a minor to major stratigraphic trapping component. Ultimate recovery from the field is estimated to be 1,600,000 bbl of oil, 1,730,000 bbl of condensate and 614 bcf of gas. The most prolific reservoir is the strandline Cotton Valley [open quotes]D[close quotes] sand averaging over 12 bcf per well, a total of over 195 bcf of gas, and more than 600,000 bbl of condensate. The best well in the fields is the Arkansas Louisiana Gas No. 2 Dowling in Sec. 30, T19N, R2W, which has produced 22 bcf of gas and 110,000 bbl of condensate. The upper, middle, and lower Hosston produce at Ruston. The lower Hosston produces from approximately 14 fields in northern Louisiana and from 11 wells in the field. The middle Hosston produces from approximately 28 fields in the basin and has made over 46 bcf of gas from six sands. The upper Hosston is regionally the most extensive in northern Louisiana producing from approximately 41 fields. At Ruston, the Hosston has produced over 15 bcf of gas from seven sands.

Lott, J.A.; Herrmann, L.A.; Davenport, R.E. (Palmer Petroleum, Inc., Shreveport, LA (United States))

1993-09-01

177

Evaluation of N and P mass balance in paddy rice culture along Kahokugata Lake, Japan, to assess potential lake pollution  

Microsoft Academic Search

Kahokugata Lake, a closed lake, has been subject to eutrophication. This research was conducted to clarify the actual phenomena\\u000a and evaluation of the discharges of N and P from paddy test fields in the lowlands into Kahokugata Lake. A comprehensive mass\\u000a balance of N and P was obtained from 4 years of study. About N, the mean value of harvested unhulled

Toshisuke Maruyama; Iwao Hashimoto; Kazuo Murashima; Hiroshi Takimoto

2008-01-01

178

The effects of irrigation regimes on the water use, dry matter production and physiological responses of paddy rice  

Microsoft Academic Search

In most cases, rice production is associated with flooding irrigation and the efficiency of irrigated water use (WUEi) is\\u000a generally lower for production of rice than for other crops. We have examined the effects of various irrigation regimes on\\u000a water consumption in a well-puddled paddy field, as well as on dry matter production, grain yield and physiological responses\\u000a of the

Jun Lu; Taiichiro Ookawa; Tadashi Hirasawa

2000-01-01

179

Nitrogen contents of rice panicle and paddy by hyperspectral remote sensing.  

PubMed

The nitrogen content or crude protein content in rice grains is one of the important indices to evaluate the nutrition and taste quality of rice. Normal determination of their contents by chemical methods is highly expensive and time consuming. The hyperspectral reflectances of the canopy, flag leaf and panicle of 5 rice varieties are measured by a ASD FieldSpec Pro FR in field under 3 nitrogen support levels in maturing process. The nitrogen contents of stems, leaves, flag leaves, panicles and rice paddy and their crude protein contents are determined. The correlation among them is analyzed. The panicles nitrogen contents (%) are very significantly correlate not only to that of stems, leaves and flag leaves and chlorophyll contents (mg g(-1)) of flag leaves at milking and maturing stages, but also to the spectral reflectance rho(lambda), the first derivative spectra D(lambda) and RVI of canopy, flag leaf and panicle itself. The nitrogen contents (%) of rice paddy are very significantly correlative to that of stems and leaves and the spectral reflectance rho(lambda), the first derivative spectra D(lambda) and RVI of canopy at some wave bands at booting, milking and maturing stages. For the squared multiple correlation coefficients (R2) of estimating the nitrogen contents of panicle and paddy by canopies spectra, we find R2 > 0.80 at milking stage, R2 > 0.75 at maturing stage, but for the estimation of panicle by the spectra of flag leaf and panicle itself, we have R2 > 0.65. It indicates that it can be feasible for estimating the contents of nitrogen and crude protein in rice grains by hyperspectral remote sensing. It provide basis for monitoring rice quality by remote sensing. PMID:19093505

Tang, Yan-Lin; Huang, Jing-Feng; Cai, Shao-Hong; Wang, Ren-Chao

2007-12-15

180

Continuous model of the regional velocity field for Poland  

NASA Astrophysics Data System (ADS)

The poster presents modern determinations of the regional velocity field for Poland. The research is based on the ASG-EUPOS, Polish multifunctional GNNS network and performed within the developmental project of the Polish Ministry of Science and Higher Education. The network of the satellite-based sites consisted of above 130 Polish sites together with the selected number of European sites operating within EPN (EUREF Permanent Network). Data came from three-year period, which is the minimum number for the horizontal velocity determinations. The velocities were calculated within the discrete network related to the GNSS sites' distribution and then interpolated to the regular grid. The discussion on the interpolation methods is also included. To the interpolation of the velocity field kriging, spline and other functions were used. Assessment of the accuracy of the velocity on the interpolated points and tests of significance were also described. Developed models of the velocities field could indicate geodynamical activity on the area of Poland.

Bogusz, J.; Figurski, M.; Kontny, B.; Grzempowski, P.; Klos, A.

2012-04-01

181

Large scale photospheric magnetic field: The diffusion of active region fields  

NASA Technical Reports Server (NTRS)

The large-scale phototospheric magnetic field was computed by allowing observed active region fields to diffuse and to be sheared by differential rotation in accordance with the Leighton (1969) magneto-kinematic model of the solar cycle. The differential rotation of the computed field patterns as determined by autocorrelation curves is similar to that of the observed photospheric field, and poleward of 20 deg. latitude both are significantly different from the differential rotation of the long-lived sunspots (Newton and Nunn, 1951) used as an input into the computations.

Schatten, K. H.; Leighton, R. B.; Howard, R.; Wilcox, J. M.

1972-01-01

182

A 3-year continuous record on the influence of daytime, season, and fertilizer treatment on methane emission rates from an Italian rice paddy  

Microsoft Academic Search

CH4 emission rates have been measured in an Italian rice paddy between 1984 and 1986, covering three vegetation periods. For these measurements a fully automated, computerized sampling and analyzing system was developed which allowed the simultaneous determination of CH4 emission rates at 16 different field plots. CH4 emission rates showed strong diurnal and seasonal variations. Diurnal changes correlated with changes

H. Schuetz; A. Holzapfel-Pschorn; R. Conrad; H. Rennenberg; W. Seiler

1989-01-01

183

Arsenic mobilization and immobilization in paddy soils  

NASA Astrophysics Data System (ADS)

Arsenic is oftentimes of geogenic origin and in many cases bound to iron(III) minerals. Iron(III)-reducing bacteria can harvest energy by coupling the oxidation of organic or inorganic electron donors to the reduction of Fe(III). This process leads either to dissolution of Fe(III)-containing minerals and thus to a release of the arsenic into the environment or to secondary Fe-mineral formation and immobilisation of arsenic. Additionally, aerobic and anaerobic iron(II)-oxidizing bacteria have the potential to co-precipitate or sorb arsenic during iron(II) oxidation at neutral pH that is usually followed by iron(III) mineral precipitation. We are currently investigating arsenic immobilization by Fe(III)-reducing bacteria and arsenic co-precipitation and immobilization by anaerobic iron(II)-oxidizing bacteria in batch, microcosm and rice pot experiments. Co-precipitation batch experiments with pure cultures of nitrate-dependent Fe(II)-oxidizing bacteria are used to quantify the amount of arsenic that can be immobilized during microbial iron mineral precipitation, to identify the minerals formed and to analyze the arsenic binding environment in the precipitates. Microcosm and rice pot experiments are set-up with arsenic-contaminated rice paddy soil. The microorganisms (either the native microbial population or the soil amended with the nitrate-dependent iron(II)-oxidizing Acidovorax sp. strain BoFeN1) are stimulated either with iron(II), nitrate, or oxygen. Dissolved and solid-phase arsenic and iron are quantified. Iron and arsenic speciation and redox state in batch and microcosm experiments are determined by LC-ICP-MS and synchrotron-based methods (EXAFS, XANES).

Kappler, A.; Hohmann, C.; Zhu, Y. G.; Morin, G.

2010-05-01

184

Soil removal as a decontamination practice and radiocesium accumulation in tadpoles in rice paddies at Fukushima.  

PubMed

We investigated the biological accumulation of radiocesium in tadpoles [Rana (Pelophylax) porosa porosa] in rice paddies with and without decontamination practice at Fukushima. Radiocesium was accumulated in surface part of soils both in the control and decontaminated paddies one year after decontamination. Mean (134)Cs and (137)Cs concentrations in tadpoles in the control and decontaminated paddies were 3000 and 4500, and 600 and 890 Bq/kg dry weight, respectively. Radiocesium concentrations in surface soil (0-5 cm depth) and tadpoles in the decontaminated paddy were five times smaller than in the control paddy. These results suggest that decontamination practice can reduce radiocesium concentrations in both soil and tadpoles. However, at the decontaminated paddy, radiocesium concentrations in surface soils became 3.8 times greater one year after decontamination, which indicates that monitoring the subsequent movement of radiocesium in rice paddies and surrounding areas is essential for examining contamination propagation. PMID:24463474

Sakai, Masaru; Gomi, Takashi; Nunokawa, Masanori; Wakahara, Taeko; Onda, Yuichi

2014-04-01

185

Behavior of butachlor and pyrazosulfuron-ethyl in paddy water using micro paddy lysimeters under different temperature conditions in spring and summer.  

PubMed

The behavior of butachlor and pyrazosulfuron-ethyl in paddy water was investigated using micro paddy lysimeters with prescribed hydrological conditions under ambient temperature in spring and summer for simulating two rice crop seasons. Although they were not significantly different, the dissipation of both herbicides in paddy water in the summer experiment was faster than in the spring experiment. The half-lives (DT(50)) in paddy water for spring and summer experiments were 3.2 and 2.5 days for butachlor, and 3.1 and 1.6 days for pyrazosulfuron-ethyl, respectively. PMID:22696099

Ok, Junghun; Doan, Nguyen Hai; Watanabe, Hirozumi; Thuyet, Dang Quoc; Boulange, Julien

2012-08-01

186

Videomagnetograph studies of solar magnetic fields. II - Field changes in an active region  

NASA Technical Reports Server (NTRS)

Using the Caltech videomagnetograph, we obtained a 6.5-hr movie of the magnetic fields in a young active region. The major contribution to the short term magnetic evolution of the region was provided by many discrete magnetic points which move in apparently random directions with typical velocities of 0.4 - 1.0 km/sec. The majority of these features appear to be footpoints of new EFR's, which emerge at an observed rate of one to two per hour. The pattern of the motions suggests that the magnetic evolution of a growing region cannot be principally due to photospheric convective cells.

Schoolman, S. A.

1973-01-01

187

Plasma Equilibrium in a Magnetic Field with Stochastic Regions  

SciTech Connect

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

J.A. Krommes and Allan H. Reiman

2009-04-23

188

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

SciTech Connect

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.

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

189

Development and application of SWAT to paddy rice district at watershed scale  

NASA Astrophysics Data System (ADS)

In irrigation district, especially in paddy rice fields, agricultural irrigation water use has a great influence on the natural water cycle process at watershed scale. In this study, SWAT model was modified to simulate irrigation water demand and quantify the irrigation return flow coefficient and the irrigation impact coefficient in paddy rice fields. Due to the lack of irrigation observed data, a multi-water source module was add to SWAT to build several feasible extraction scenarios, and a new algorithm of automatic irrigation application was implemented too. According to the simulation accuracy, the optimal scenario was selected to use in the new SWAT model, and then was applied to Changge Irrigation District in Hulan River Basin, northeast China. Comparisons between the enhanced model and old one were conducted at outlet cite, sifangtai. The results showed that the proposed SWAT has higher precision during calibration and validation periods, Nash coefficient of the simulated monthly flow was from 0.74 and 0.69 to 0.88 and 0.80 respectively. in addition, the annual averaged irrigation water and return water were 78 million m3 and 41 million m3, the irrigation return flow coefficient was 0.52, average consumption of irrigation water accounted for 10% of the total runoff. In general, the developed model had been greatly improved as compared to original model. Keywords: SWAT model, hydrological modeling, rice, irrigation return flow coefficient, irrigation impact coefficient

Shi, Yuzhi; Zhang, Chi; Zhou, Huicheng

2010-05-01

190

Response of a rice paddy soil methanogen to syntrophic growth as revealed by transcriptional analyses.  

PubMed

Members of Methanocellales are widespread in paddy field soils and play the key role in methane production. These methanogens feature largely in these organisms’ adaptation to low H2 and syntrophic growth with anaerobic fatty acid oxidizers. The adaptive mechanisms, however, remain unknown. In the present study, we determined the transcripts of 21 genes involved in the key steps of methanogenesis and acetate assimilation of Methanocella conradii HZ254, a strain recently isolated from paddy field soil. M. conradii was grown in monoculture and syntrophically with Pelotomaculum thermopropionicum (a propionate syntroph) or Syntrophothermus lipocalidus (a butyrate syntroph). Comparison of the relative transcript abundances showed that three hydrogenase-encoding genes and all methanogenesis-related genes tested were upregulated in cocultures relative to monoculture. The genes encoding formylmethanofuran dehydrogenase (Fwd), heterodisulfide reductase (Hdr), and the membrane-bound energy-converting hydrogenase (Ech) were the most upregulated among the evaluated genes. The expression of the formate dehydrogenase (Fdh)-encoding gene also was significantly upregulated. In contrast, an acetate assimilation gene was downregulated in cocultures. The genes coding for Fwd, Hdr, and the D subunit of F420-nonreducing hydrogenase (Mvh) form a large predicted transcription unit; therefore, the Mvh/Hdr/Fwd complex, capable of mediating the electron bifurcation and connecting the first and last steps of methanogenesis, was predicted to be formed in M. conradii. We propose that Methanocella methanogens cope with low H2 and syntrophic growth by (i) stabilizing the Mvh/Hdr/Fwd complex and (ii) activating formatedependent methanogenesis. PMID:24837392

Liu, Pengfei; Yang, Yanxiang; Lü, Zhe; Lu, Yahai

2014-08-01

191

The Spatial Integration of Paddy Markets in Vietnam  

Microsoft Academic Search

This paper examines whether there is spatial integration between and within paddy markets in the north and south of Vietnam. The empirical model developed uses estimates of transfer costs to generalise Ravallion's model of spatial market integration to allow for threshold effects. A sequential testing strategy is used to test for market segmentation, the number of thresholds, long-run integration, informational

Bob Baulch; Henrik Hansen; Le Dang Trung; Tran Ngo Minh Tam

2008-01-01

192

Adiabatic theory in regions of strong field gradients. [in magnetosphere  

NASA Technical Reports Server (NTRS)

The theory for the generalized first invariant for adiabatic motion of charged particles in regions where there are large gradients in magnetic or electric fields is developed. The general condition for an invariant to exist in such regions is that the potential well in which the particle oscillates change its shape slowly as the particle drifts. It is shown how the Kruskal (1962) procedure can be applied to obtain expressions for the invariant and for drift velocities that are asymptotic in a smallness parameter epsilon. The procedure is illustrated by obtaining the invariant and drift velocities for particles traversing a perpendicular shock, and the generalized invariant is compared with the magnetic moment, and the drift orbits with the actual orbits, for a particular case. In contrast to the magnetic moment, the generalized first invariant is better for large gyroradii (large kinetic energies) than for small gyroradii. Expressions for the invariant when an electrostatic potential jump is imposed across the perpendicular shock, and when the particle traverses a rotational shear layer with a small normal component of the magnetic field are given.

Whipple, E. C.; Northrop, T. G.; Birmingham, T. J.

1986-01-01

193

[The neck -- a sonographically interesting region for many medical fields].  

PubMed

The soft tissues of the neck can be examined at the highest resolution with ultrasound probes of high frequencies due to their superficial position. There are many clinically important diagnostic issues concerning the thyroid gland, the parathyroid, lymph nodes, vessels of the neck, salivary glands and other structures of the field of ENT and even the nerves of this region. Numerous different medical departments therefore work in this field either together or I a parallel fashion. In addition to different sub-specialties of internal medical and surgical departments, radiologists, neurologists, ENT doctors, gnathologists and radio-oncologists are all active here. Even intensive care personnel and anaesthesiologists use ultrasound for sonographically guided punctures. It is therefore obvious that the cervical region is of special importance for an interdisciplinary journal, constituting a large part of publications. In the last 2 (1/2) years, we published two articles about cervical lymph nodes , eight concerning the topic of vessels , two articles about salivary glands and three dealing with the parathyroid glands . The present issue again contains three publications concerning this area, characteristically from three different medical specialties, each of great significance for various medical fields. An important article deals with deQuervain thyroiditis . Albeit this is not a common disease, any clinician working on the cervical region should be well aware of this entity, as the patients concerned often go through a medical "odyssey" with different specialists before the right diagnosis is made. An important addition to sonographical interventional techniques is percutaneous instillation therapy for focal autonomous adenomas of the thyroid : it is fast acting and effective, representing a genuine therapeutic alternative to surgery or radioactive iodine treatment in many cases. The case report on a - fortunately non-permanent - partial laryngeal necrosis resulting from the instillation of 96 % alcohol demonstrates the potential damage an established method can cause if applied without expertise. It is therefore mandatory to be aware of potential side effects and carry out the intervention proficiently, strictly keeping in mind the indication for therapy. A further case report demonstrates in an impressive way the importance of cervical sonography for the detection and landmarking of parathyroid adenomas. The fact that the author is a surgeon might serve as valid proof, as the surgery of parathyroid glands almost solely depended on the experience and the explorative skill of the surgeon until recently. PMID:15852171

Seitz, K

2005-04-01

194

[Effects of biochar application on greenhouse gas emission from paddy soil and its physical and chemical properties].  

PubMed

A field experiment was conducted to investigate the effects of rice straw returning and rice straw biochar and life rubbish biochar application on the greenhouse gas (CH4, CO2 and N2O) emission from paddy soil, its physical and chemical properties, and rice grain yield. Compared with rice straw returning, applying rice straw biochar decreased the cumulative CH4 and N2O emissions from paddy soil significantly by 64.2% - 78.5% and 16.3% - 18.4%, respectively. Whether planting rice or not, the cumulative N2O emission from paddy soil under the applications of rice straw biochar and life rubbish biochar was decreased significantly, compared with that without biochar amendment. Under the condition of no rice planting, applying life rubbish biochar reduced the cumulative CO2 emission significantly by 25.3%. Rice straw biochar was superior to life rubbish biochar in improving soil pH and available potassium content. Both rice straw biochar and life rubbish biochar could increase the soil organic carbon content significantly, but had less effects on the soil bulk density, total nitrogen and available phosphorus contents, cation exchange capacity (CEC), and grain yield. It was suggested that compared with rice straw returning, straw biochar was more effective in improving rice grain yield. PMID:24380334

Liu, Yu-xue; Wang, Yao-feng; Lü, Hao-hao; Chen, Yi; Tang, Xu; Wu, Chun-yan; Zhong, Zhe-ke; Yang, Sheng-mao

2013-08-01

195

Active Region Magnetic Field Modeling Guided by Coronal Loops and Surface Fields  

NASA Astrophysics Data System (ADS)

Dynamic events such as solar flares, filament eruptions, and mass ejections are powered by the evolving coronal magnetic field. However, the ways in which energy is stored in, and released from, the coronal magnetic field are poorly understood, in large part because the field configuration cannot be determined directly from observations and has eluded the successful application of routine modeling based on surface magnetograms. Recently, we have demonstrated that the Quasi-Grad-Rubin (QGR) method for modeling the current-carrying field associated with active regions shows promise. In Malanushenko et al. (2014, ApJ 783:102) we have used the QGR method to construct the magnetic field at several times during the evolution of AR11158 during February 2011. The QGR method does not require vector magnetograms, and instead uses the trajectories of observed coronal loops to constrain the locations of electric currents within the modeling domain. In this study, we continue to assess the utility of QGR by applying this method to additional active regions from the current activity cycle, making use of SDO/HMI line-of-sight magnetograms and imagery from the extreme ultraviolet channels of SDO/AIA.

DeRosa, Marc L.; Malanushenko, Anna; Schrijver, Carolus J.; Wheatland, Michael S

2014-06-01

196

Kinetic distribution of 14C-metsulfuron-methyl residues in paddy soils under different moisture conditions.  

PubMed

Rice paddy soils undergo several cycles of drying and wetting during a growing season. A laboratory study was conducted to determine the effect of soil moisture conditions on the distribution and kinetics of extractable and bound residues of 14C-metsulfuron-methyl in six Chinese paddy soils during 84 d of incubation at 15 degrees C with moisture contents varying from 20 to 50% of the field water-holding capacity. The amount of extractable residues consistently increased and bound residues decreased with increasing soil moisture content. At the end of the incubation experiments, extractable residues and bound residues accounted for 34.5 to 84.4% and 11.6 to 53.3% of applied radioactivity in soils, respectively. Soil pH and soil microbial biomass carbon were the most predominant factors affecting the formation and relative distribution of herbicide residues between extractable and bound residue forms. In high-pH soils, bound residues decreased and extractable residues increased, suggesting an increased leaching risk for metsulfuron-methyl in alkaline soils. High precipitation rates, along with the common practice of liming in southeastern China, may lead to enhanced herbicide leaching as well as phytotoxicity to rotation plants and should be considered in overall pest management practices. PMID:19141806

Wang, H Z; Gan, J; Zhang, J B; Xu, J M; Yates, S R; Wu, J J; Ye, Q F

2009-01-01

197

Seasonal Transition of Active Bacterial and Archaeal Communities in Relation to Water Management in Paddy Soils  

PubMed Central

Paddy soils have an environment in which waterlogging and drainage occur during the rice growing season. Fingerprinting analysis based on soil RNA indicated that active microbial populations changed in response to water management conditions, although the fundamental microbial community was stable as assessed by DNA-based fingerprinting analysis. Comparative clone library analysis based on bacterial and archaeal 16S rRNAs (5,277 and 5,436 clones, respectively) revealed stable and variable members under waterlogged or drained conditions. Clones related to the class Deltaproteobacteria and phylum Euryarchaeota were most frequently obtained from the samples collected under both waterlogged and drained conditions. Clones related to syntrophic hydrogen-producing bacteria, hydrogenotrophic methanogenic archaea, rice cluster III, V, and IV, and uncultured crenarchaeotal group 1.2 appeared in greater proportion in the samples collected under waterlogged conditions than in those collected under drained conditions, while clones belonging to rice cluster VI related to ammonia-oxidizing archaea (AOA) appeared at higher frequency in the samples collected under drained conditions than in those collected under waterlogged conditions. These results suggested that hydrogenotrophic methanogenesis may become active under waterlogged conditions, whereas ammonia oxidation may progress by rice cluster VI becoming active under drained conditions in the paddy field. PMID:24005888

Itoh, Hideomi; Ishii, Satoshi; Shiratori, Yutaka; Oshima, Kenshiro; Otsuka, Shigeto; Hattori, Masahira; Senoo, Keishi

2013-01-01

198

Effects of open drainage ditch design on bacterial and fungal communities of cold waterlogged paddy soils  

PubMed Central

A field experiment established in 1980 was conducted to evaluate the effects of open drainage ditch applied for water removal on bacterial and fungal communities of cold waterlogged paddy soils in 2011. In this experiment, traditional plate counting and temperature gradient gel electrophoresis were employed to characterize the abundance and diversity of soil bacterial and fungal communities. Four different distances from the open drainage ditch, 5, 15, 25 and 75 m with different degrees of drainage were designed for this study. Maximum populations of culturable aerobic bacteria and fungi were at 15-m distance while minimum populations were at 75-m distance. Significant differences (p < 0.05) in fungal populations were observed at all distances from open drainage ditch. The highest diversity of the bacterial community was found at a distance of 25 m, while that of the fungal community was observed at a distance of 5 m. Sequencing of excised TGGE bands indicated that the dominant bacteria at 75-m distance belonged to anaerobic or microaerobic bacteria. Relationships between microbial characteristics and soil physicochemical properties indicated that soil pH and available nitrogen contents were key factors controlling the abundance of culturable aerobic bacteria and fungi, while soil water capacity also affected the diversity of fungal community. These findings can provide the references for better design and advanced management of the drainage ditches in cold waterlogged paddy soils. PMID:24516468

Qiu, Shanlian; Wang, MK; Wang, Fei; Chen, Jichen; Li, Xiaoyan; Li, Qinghua; Lin, Cheng; Lin, Xinjian

2013-01-01

199

Eco-stoichiometric alterations in paddy soil ecosystem driven by phosphorus application.  

PubMed

Agricultural fertilization may change processes of elemental biogeochemical cycles and alter the ecological function. Ecoenzymatic stoichiometric feature plays a critical role in global soil carbon (C) metabolism, driving element cycles, and mediating atmospheric composition in response to agricultural nutrient management. Despite the importance on crop growth, the role of phosphorous (P) in compliance with eco-stoichiometry on soil C and nitrogen (N) sequestration in the paddy field remains poorly understood in the context of climate change. Here, we collected soil samples from a field experiment after 6 years of chemical P application at a gradient of 0 (P-0), 30 (P-30), 60 (P-60), and 90 (P-90) kg ha(-1) in order to evaluate the role of P on stoichiometric properties in terms of soil chemical, microbial biomass, and eco-enzyme activities as well as greenhouse gas (GHG: CO2, N2O and CH4) emissions. Continuous P input increased soil total organic C and N by 1.3-9.2% and 3%-13%, respectively. P input induced C and N limitations as indicated by the decreased ratio of C:P and N:P in the soil and microbial biomass. A synergistic mechanism among the ecoenzymatic stoichiometry, which regulated the ecological function of microbial C and N acquisition and were stoichiometrically related to P input, stimulated soil C and N sequestration in the paddy field. The lower emissions of N2O and CH4 under the higher P application (P-60 and P-90) in July and the insignificant difference in N2O emission in August compared to P-30; however, continuous P input enhanced CO2 fluxes for both samplings. There is a technical conflict for simultaneously regulating three types of GHGs in terms of the eco-stoichiometry mechanism under P fertilization. Thus, it is recommended that the P input in paddy fields not exceed 60 kg ha(-1) may maximize soil C sequestration, minimize P export, and guarantee grain yields. PMID:23667435

Li, Xia; Wang, Hang; Gan, Shaohua; Jiang, Daqian; Tian, Guangming; Zhang, Zhijian

2013-01-01

200

Seasonal Variation of Methane Flux From a California Rice Paddy  

Microsoft Academic Search

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

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

1983-01-01

201

Lignocellulolytic enzyme production from submerged fermentation of paddy straw  

Microsoft Academic Search

Five strains of cellulolytic bacteria and four strains of Phanerochaete chrysosporium were evaluated for the lignocellulolytic enzyme production during submerged fermentation (SmF) of paddy straw. Extra-cellular\\u000a enzyme assay for CMCase, FPase, Cellobiase, Xylanase, Lignin peroxidase and Laccase enzymes was performed after 7 and 15 days\\u000a of submerged fermentation. Cellulomonas cellulans MTCC 23, Cytophaga hutchinsonii NCIM 2338 and Phanerochaete chrysosporium MTCC

B. K. Mishra; A. K. Pandey Lata

2007-01-01

202

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

NASA Technical Reports Server (NTRS)

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.

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

203

Sensor Measurements and Sediment Incubations Indicate Diurnal Redox Cycling Associate With Arsenic Mobilization at a Bangladeshi Rice Paddy  

NASA Astrophysics Data System (ADS)

The presence of arsenic in the groundwater has led to the largest environmental poisoning in history; tens of millions of people in the Ganges Delta continue to drink groundwater that is dangerously contaminated with arsenic (As). Rice fields receive large loads of arsenic with irrigation water and provide recharge to the underlying aquifer. It is currently not known whether rice fields are a sink or source of arsenic in the hydrologic system. In the dry season, as As(III)-containing minerals are oxidized, As(V) is released and will adhere to Fe hydr(oxide) minerals. When sediments are inundated with water, reducing conditions will then drive reduction of Fe hydr(oxides) and release of As. 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). To better understand geochemical and microbial processes leading to As mobilization in surface sediment, we deployed sensors to take temporally dense measurements across our experimental rice paddy. Data collected in both 2006 and 2007 showed trends in geochemical parameters indicating that diurnal, possibly plant-induced, processes may be important. Over a two month period, nitrate concentrations decrease consistently each day as ammonium levels increase, presumably through temperature driven reductive processes. Nitrate concentrations in the subsurface then increase while ammonium levels decrease, possibly due to root oxygen leakage or rapid infiltration of oxygen rich surface water. Using sediment from the rice paddy and artificial irrigation water, laboratory microcosms were constructed to simulate the diurnal cycles observed at the field site. In carbon-ammended treatments, Fe and As cycling can occur on the order of days. Oscillations in redox conditions on diurnal as well as seasonal time scales may be important in the mobilization of arsenic into aquifers. By elucidating As mobilization mechanisms at an experimental rice paddy, this work could ultimately lead to solutions that minimize As exposure in critical populations.

Lin, T.; Lin, C.; Ramanathan, N.; Neumann, R.; Harvey, C.; Jay, J.

2007-12-01

204

Regional Ecorisk Field investigation, upper Clark Fork River Basin  

SciTech Connect

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.

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

1995-12-31

205

TRANSITION REGION MAGNETIC FIELD AND POLAR MAGNETIC DISTURBANCES  

Microsoft Academic Search

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

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

1966-01-01

206

Partitioning of arsenic in soil-crop systems irrigated using groundwater: a case study of rice paddy soils in southwestern Taiwan.  

PubMed

The accumulation of As in rice due to groundwater irrigation in paddy fields represents a serious health hazard in South and Southeast Asia. In Taiwan, the fate of As in long-term irrigated paddy fields is poorly understood. Groundwater, surface soil, and rice samples were collected from a paddy field that was irrigated with As-containing groundwater in southwestern Taiwan. The purpose of this study is to elucidate the source and sink of As in the paddy field by comparing the As fractions in the soils that were obtained by a sequential extraction procedure (SEP) with the As uptake of rice. The risks associated with eating rice from the field can thus be better understood. The concentration of As in groundwater varied with time throughout the growing seasons of rice, but always exceeded the permitted maximum (10 ?g L(-1)) for drinking water by the WHO. The As concentration increased with the concentration of Fe in the groundwater, supporting the claim that a large amount of As was concentrated in the Fe flocs collected from the internal wall of the groundwater pump. The results of the SEP revealed that As bound with amorphous and crystalline hydrous oxides exhibited high availability in the soils. The root of rice accumulated the largest amount of As, followed by the straw, husk, and grain. Although the As concentration in the rice grain was less than 1.0 mg kg(-1), the estimated intake level was close to the maximum tolerable daily intake of As, as specified by the WHO. PMID:22094052

Hsu, Wen-Ming; Hsi, Hsing-Cheng; Huang, You-Tuan; Liao, Chien-Sen; Hseu, Zeng-Yei

2012-02-01

207

Problems, Treatment, and Prevention of Paddy Rice Bacterial Disease of Leaf Spot in Kuangtung Province.  

National Technical Information Service (NTIS)

The bacterial paddy rice disease of leaf spot is widespread in Kuangtung Province. The loss in yield of the affected paddies is generally 5-25%, but when the disease is serious, the loss may reach above 30%. One of the major primary source of infection is...

H. Fan

1966-01-01

208

Methane emission during a cultivation period from an Italian rice paddy  

Microsoft Academic Search

CH4 release rates from rice paddies were measured in Vercelli, Italy, in 1983 during a complete vegetation period, using a static box system. The rice paddies were found to be a source of atmospheric methane during the time of flooding. The CH4 release rates range between a few milligrams of CH4 per square meter per hour and 51 mg CH4

A. Holzapfel-Pschorn; W. Seiler

1986-01-01

209

Impact of irrigating rice paddies with groundwater containing arsenic in Bangladesh  

E-print Network

Impact of irrigating rice paddies with groundwater containing arsenic in Bangladesh A. van Geen a, University of Dhaka, Bangladesh Received 1 November 2005; received in revised form 4 January 2006; accepted from 4 rice paddies in Bangladesh during the wet growing season (May­ November), when surface water

van Geen, Alexander

210

A statistical study on property of spatial magnetic field for solar active region  

NASA Astrophysics Data System (ADS)

Magnetic fields dominate most solar activities, there exist direct relations between solar flare and the distributions of magnetic field, and also its corresponding magnetic energy. In this paper, the statistical results about the relationships between the spatial magnetic field and solar flare are given basing on vector magnetic field observed by the Solar Magnetic Field Telescope (SMFT) at Huairou Solar Observing Station (HSOS). The spatial magnetic fields are obtained by extrapolated photosphere vector magnetic field observed by SMFT. There are 23 active regions with flare eruption are chosen as data samples, which were observed from 1997 to 2007. The results are as follows: 1. Magnetic field lines become lower after flare for 16 (69 %) active regions; 2. The free energy are decreased after flare for 17 (74 %) active regions. It can conclude that for most active regions the changes of magnetic field after solar flare re coincident with the previous observations and studies.

Liu, S.

2014-06-01

211

Investigation of radial electric field in the edge region and magnetic field structure in the Large Helical Device  

NASA Astrophysics Data System (ADS)

In the Large Helical Device experiments, a significant pressure gradient is observed in the edge region where the three-dimensional magnetohydrodynamics equilibrium analysis predicts the stochastization of magnetic field lines. Therefore, experimental investigation of this edge plasma behavior is attracting much interest to identify either the plasma response to stochastic magnetic fields or the topological change of magnetic fields due to the plasma. In this study, we have investigated the relation of the stochastization of magnetic field lines to the radial electric field, Er. When magnetic field lines become stochastic or open and connected to the vessel, electrons are lost along these field lines while ions are trapped. Then, a strong Er shear from negative to positive appears at the boundary. Two magnetic configurations with different widths of the stochastic layer in the vacuum are studied for low-? discharges. It has been found that the position of a strong Er shear appears outside of the last closed flux surface. When comparing the vacuum magnetic field, the positions of strong Er shear are observed in the edge of the stochastic layer. In the stochastic region, the scatter of stochastic field lines is studied. The position of a strong Er shear appears in the region where the outward scatter of the field lines increases. In that region, stochastic field lines intersect the regions with long and short connection lengths. Although the connection length is longer than the electron mean free path, the scatter of stochastic field lines with short connection lengths appear in the regions with positive Er. These results are compared with moderate-? discharges, where a large plasma response is expected. The prediction of the vacuum magnetic field qualitatively agree with the experimental observations but quantitative differences are found.

Suzuki, Y.; Ida, K.; Kamiya, K.; Yoshinuma, M.; Tsuchiya, H.; Inagaki, S.; Sakakibara, S.; Watanabe, K. Y.; Narushima, Y.; Ohdachi, S.; Yamada, I.; Yasuhara, R.; Tanaka, K.; Akiyama, T.; Yamada, H.; the LHD Experiment Group

2013-12-01

212

Bangladesh gas line battles rice paddies  

SciTech Connect

Bangladesh is seeing a potential savings to its national economy in the construction of a new 107-mile pipeline. The pipeline will bring natural gas from the newly tapped fields of Bakhrabad near Dhaka to the country's main port and industrial center at Chittagong. Industries in Chittagong are instigating a conversion program from oil to gas, saving more than $100 million a year. The paddyfields, with their high water-tables have slowed site work and made progress at times difficult. In addition, there have been quite a few water crossings, which hampered progress.

Not Available

1983-08-01

213

Methane and nitrous oxide emissions from three paddy rice based cultivation systems in Southwest China  

NASA Astrophysics Data System (ADS)

To understand methane (CH4) and nitrous oxide (N2O) emissions from permanently flooded rice paddy fields and to develop mitigation options, a field experiment was conducted in situ for two years (from late 2002 to early 2005) in three rice-based cultivation systems, which are a permanently flooded rice field cultivated with a single time and followed by a non-rice season (PF), a rice-wheat rotation system (RW) and a rice-rapeseed rotation system (RR) in a hilly area in Southwest China. The results showed that the total CH4 emissions from PF were 646.3±52.1 and 215.0±45.4 kg CH4 hm-2 during the rice-growing period and non-rice period, respectively. Both values were much lower than many previous reports from similar regions in Southwest China. The CH4 emissions in the rice-growing season were more intensive in PF, as compared to RW and RR. Only 33% of the total annual CH4 emission in PF occurred in the non-rice season, though the duration of this season is two times longer than the rice season. The annual mean N2O flux in PF was 4.5±0.6 kg N2O hm-2 yr-1. The N2O emission in the rice-growing season was also more intensive than in the non-rice season, with only 16% of the total annual emission occurring in the non-rice season. The amounts of N2O emission in PF were ignorable compared to the CH4 emission in terms of the global warming potential (GWP). Changing PF to RW or RR not only eliminated CH4 emissions in the non-rice season, but also substantially reduced the CH4 emission during the following rice-growing period (ca. 58%, P<0.05). However, this change in cultivation system substantially increased N2O emissions, especially in the non-rice season, by a factor of 3.7 to 4.5. On the 100-year horizon, the integrated GWP of total annual CH4 and N2O emissions satisfies PF?RR?RW. The GWP of PF is higher than that of RW and RR by a factor of 2.6 and 2.7, respectively. Of the total GWP of CH4 and N2O emissions, CH4 emission contributed to 93%, 65% and 59% in PF, RW and RR, respectively. These results suggest that changing PF to RW and RR can substantially reduce not only CH4 emission but also the total GWP of the CH4 and N2O emissions.

Jiang, Changsheng; Wang, Yuesi; Zheng, Xunhua; Zhu, Bo; Huang, Yao; Hao, Qingju

2006-05-01

214

Characteristics of F-region dynamo currents deduced from CHAMP magnetic field measurements  

Microsoft Academic Search

Using magnetic field observations of the CHAMP satellite we provide the first comprehensive study of F-region dynamo currents as a function of season, local time, geographic longitude, and solar activity. From bipolar variations of the zonal magnetic field component the density of vertical current driven by the F-region dynamo is deduced. The current strength is smallest around June solstice, which

Hermann Lühr; Kyoung Wook Min

2010-01-01

215

Relationship between Region 2 field-aligned current and the ring current: Model results  

E-print Network

and the ring current, either through one of the two GEM events or the 12 August 2000 storm. It is shownRelationship between Region 2 field-aligned current and the ring current: Model results Y. Zheng,1] Detailed investigations on the relationship between the ring current and Region 2 field-aligned currents

California at Berkeley, University of

216

Mineralization of metsulfuron-methyl in Chinese paddy soils.  

PubMed

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 2.2-6.0% of the applied (14)C mineralized after 84d of incubation at 15 degrees C. The mineralization of MSM was enhanced by increasing soil moisture and soil temperature. Soil moisture would have different impact on the response of MSM mineralization to variation in soil temperature. An increase of 10 degrees C accelerated the average rate of MSM mineralization by 2.3 times at 50% water-holding capacity (WHC) and 1.9 times at 40% WHC. Regression analysis showed that soil pH, organic carbon contents, microbial biomass carbon contents, and silt/clay fractions were the dominant factors affecting MSM mineralization, with pH as the most important factor. The relatively slow mineralization rate of MSM suggested long persistence of this herbicide in soil, thus increasing its potential ecological risk, especially when applied in alkaline soils and in cold areas. PMID:19906402

Wang, Haizhen; Xu, Jianming; Yates, Scott R; Zhang, Jiabao; Gan, Jay; Ma, Jincai; Wu, Jianjun; Xuan, Richeng

2010-01-01

217

Effect of Cropping History on Water Retention Characteristics of Clayey Paddy Soil under Low Water Potential Conditions  

NASA Astrophysics Data System (ADS)

The water content and water potential of soil samples from paddy fields with varied cropping histories were measured under low water potential conditions. The relationships between the water content and the water potential were fitted to power equations. Analyses of the results for the fresh soils showed that the coefficient a (the water content at water potential of -1MPa) (CA) and the absolute value of the exponential index b (AB) of the fitted power equation was smaller in the soils under the cultivation of upland crops than the wetland rice. On the other hand, the difference in CA and AB for air-dried soil was not revealed between the soils under the upland crop cultivation and the soils under the wetland rice cultivation. The difference in CA for the fresh soil and for the air-dried soil and the difference in AB for the fresh soil and for air-dried soil were found to increase with continuous cropping of wetland rice, and decrease in response to continuous cropping of upland crops. These finding suggest these indices can presume cropping histories of rotational paddy fields.

Adachi, Kazuhide; Yoshida, Shuichiro; Ohno, Satoshi; Obara, Hiroshi

218

Inconsistent Changes in Microbial Community Structure and Abundance with Biochar Amendment in Rice Paddy Soils from South China  

NASA Astrophysics Data System (ADS)

Effects of biochar amendment on soil microbiota had not yet been well understood. We conducted a cross site field study on biochar amendment to rice paddies from south China in 2010. The experiment was performed with four treatments including N fertilization only (C0N), N fertilization plus biochar at 20t/ha (C1N) and at 40t/ha (C2N) as well as a control without N fertilization and biochar (C0N0) consistently with three sites. Biochar was spread at soil surface and incorporated into soil and thoroughly mixed to depth of about 12cm before padding for rice seedling transplantation. Rice production was conducted with conventional water and nutrient management practices adapting to local climate and cultivar conditions. Topsoil samples were collected from each treatment plot across sites for chemical properties and molecular analysis after rice harvest in autumn of 2010. Contents of organic carbon, total N as well as soil microbial biomass carbon were determined with recommended methods. Quantitative real-time PCR coupled with 16S rRNA gene and 18S rRNA gene denaturing gradient gel electrophoresis (DGGE) were respectively employed to trace changes in abundance and structure of bacteria and fungi community with biochar amendment. Increase in microbial biomass carbon (SMBC) was not observed in one site but by 10-20% in other two sites while SOC contents were increased by 25-45% in all sites under biochar treatments. Copy numbers of bacterial genes were different between the sites but no changes with biochar treatment in a single site. However, cluster analysis revealed a more or less decreased similarity of bacterial community to the control (ranging from 75% to 85%) by biochar treatment in a single site. Nevertheless, a number of special bands appeared both in bacterial and fungal DGGE patterns under biochar treatments, though varying with site also. While the fungi copy numbers markedly varied both with sites and with biochar treatments, lower similarity and greater number of special bands than bacterial were found in fungal DGGE patterns. This may indicate a higher sensitivity of fungi in rice paddies to biochar, a high stable carbon source. This study suggests a long term monitoring protocol for assessing the potential biological risk of biochar amendment in rice paddy soils from China. Keywords: Biochar, microbial biomass carbon, microbial community structure, DGGE, Quantitative real-time PCR, rice paddy soils

Chen, J.; Qu, J.; Liu, X.; Zheng, J.; Li, L.; Pan, G.

2012-04-01

219

Field-aligned currents observed by Double Star TC-2 in polar region  

NASA Astrophysics Data System (ADS)

It is significant to study the Field-Aligned Currents FACs in the whole magnetosphere-ionosphere coupling system Coordinating observation of the Double Star Program DSP and the Cluster mission provides us a very good opportunity for this study In this paper with the magnetic field measurements by FGM instrument on board the DSP TC-2 satellite we study the FACs in TC-2 s orbit that is in the middle altitude above the polar region We establish a field-aligned coordinate system by using the Tsyganenko 96 model and identify the FACs by subtracting the model field from the measured field We make a distinction between region 1 and region 2 FACs with the detrended data in the field-aligned coordinate system Based on the selected FACs the properties of the FACs in mid-altitude with that in low-altitude and high-altitude are compared FACs above the southern polar region are also studied

Shi, J. K.; Cheng, Z. W.; Guo, J. G.; Zhang, T. L.; Chris, C.; Liu, Z. X.

220

A synthesis of the Air Pollution Over the Paris Region (ESQUIF) field campaign  

E-print Network

A synthesis of the Air Pollution Over the Paris Region (ESQUIF) field campaign Robert Vautard,1 the Paris area during the Air Pollution Over the Paris Region (ESQUIF) project. From 1998 to 2000, 12, aircraft measurements Citation: Vautard, R., et al., A synthesis of the Air Pollution Over the Paris Region

Menut, Laurent

221

Field Trip to Enfield Glen, NY Finger Lakes Region  

NSDL National Science Digital Library

Ithaca NY is currently located in a tranquil mid-continental geologic setting. But Ithaca's past was anything but tranquil. Would you believe that we once sat beneath a mile-thick sheet of ice? Or that it was once the bottom of the ocean? In a zone of high seismic activity? Or volcanic eruptions? It's all true. On this field trip to Enfield Glen, in Upper Treman State Park, we will make measurements and observations that allow us to reconstruct some of the events in the geologic past of this locality. Was New York always on the east coast of North America? Come on, let's find out.

Moore, Alexandra

222

Static electric-field effects in the photodetachment of Cs P resonance region  

E-print Network

Static electric-field effects in the photodetachment of CsÃ? at the 3 P resonance region A. A number s : 32.80.Gc, 32.60. i I. INTRODUCTION A strong external static electric field affects the decay model allows the exact analytical treatment of both negative-ion decay in a static field 1 and PD

Thumm, Uwe

223

Comparison of transient horizontal magnetic fields in a plage region and in the quiet Sun  

E-print Network

Properties of transient horizontal magnetic fields (THMFs) in both plage and quiet Sun regions are obtained and compared. Spectro-polarimetric observations with the Solar Optical Telescope (SOT) on the Hinode satellite were carried out with a cadence of about 30 seconds for both plage and quiet regions located near disk center. We select THMFs that have net linear polarization (LP) higher than 0.22%, and an area larger than or equal to 3 pixels, and compare their occurrence rates and distribution of magnetic field azimuth. We obtain probability density functions (PDFs) of magnetic field strength and inclination for both regions.The occurrence rate in the plage region is the same as for the quiet Sun. The vertical magnetic flux in the plage region is ~8 times larger than in the quiet Sun. There is essentially no preferred orientation for the THMFs in either region. However, THMFs in the plage region with higher LP have a preferred direction consistent with that of the plage-region's large-scale vertical field pattern. PDFs show that there is no difference in the distribution of field strength of horizontal fields between the quiet Sun and the plage regions when we avoid the persistent large vertical flux concentrations for the plage region. The similarity of the PDFs and of the occurrence rates in plage and quiet regions suggests that a local dynamo process due to the granular motion may generate THMFs all over the sun. The preferred orientation for higher LP in the plage indicates that the THMFs are somewhat influenced by the larger-scale magnetic field pattern of the plage.

Ryohko Ishikawa; Saku Tsuneta

2008-12-09

224

Field-aligned Ion Motions in the Transient Region between Polar Ionospheric E- and F-regions  

NASA Astrophysics Data System (ADS)

We focus on field-aligned ion motions around the boundary between polar ionospheric E- and F-regions (from 140 to 250 km heights). Here we define a "transient region" as the boundary. Ionospheric parameters were obtained with the European Incoherent Scatter (EISCAT) Kiruna-Sodankylä-Troms\\o (KST) UHF radar (931 MHz, 69.35°N, 19.14°E, 66.12° invariant latitude) in northern Scandinavia. The observation mode of the KST radar was so-called Common Program One (CP-1) mode where the antenna at Troms\\o is pointed along the local magnetic field line there. This mode provides us with ion velocity, electron density, and electron and ion temperatures with high time- (order of minutes) and altitude- (about 3 km) resolutions along the radar beam. In addition, this mode conducts a tristatic measurement of ion velocity at 278 km thus the electric field vector assuming ExB drift. We used EISCAT data sets obtained for about one solar cycle (~ 11 years). In order to get an overview of the spectral behavior of the variations in field-aligned ion motions, a Lomb periodgram and a Fast Fourier Transform (FFT) were applied to EISCAT radar data sets that were selected every 24 hour intervals. The reason why we used two spectral analysis methods was to estimate effects of gaps in EISCAT radar data. Results from both spectral analysis showed that dominant oscillation periods at the lower (upper) region of transient region was 12 (24) hours. The phase and amplitude of 24/12 hours variations in the field-aligned ion velocity in the transient region had similar height profiles to those of thermospheric tide predicted by model calculation (Forbes, 1982) when electric field magnitude observed with the EISCAT radar was relatively small. Directions and magnitude of height gradient of field-aligned ion velocity in the transient region had also 24- and 12-hours periodic oscillations. These tendencies were dominant regardless of electric field magnitude. Because the pressure gradient force along the magnetic field line was considerably small to accelerate ions up to observed level even during high auroral activity (Fujii et al., 2002), thermospheric tidal motions could be a major cause that maintained the 24- and 12-hours oscillations of field-aligned ion velocity. Amplitude and phase of 24- and 12-hours oscillations strongly depended on the electric field magnitude. This suggests that electromagnetic force such as ion drag and pressure gradient caused by Joule and particle heating can generate and/or modulate thermospheric tides in the transient region. Forbes, Atmospheric tides 2. The solar and lunar semidiurnal components, JGR, 87, 5241-5252, 1982. Fujii, R., S. Oyama, S. C. Buchert, S. Nozawa, and N. Matuura, Field-aligned ion motions in the E and F regions, JGR, 107, A5, 2002.

Oyama, S.; Nozawa, S.; Murayama, Y.; Fujii, R.; Shinagawa, H.

2002-12-01

225

Interaction region analysis for a high-field hadron collider  

SciTech Connect

The primary goal of the interaction region (IR) is to demagnify the transverse beam dimension to a small spot size at the interaction point (IP) to reach the required luminosity. With an experimental drift space of {+-}25 m and a quadrupole focusing strength of 360 T/m at the triplets, a {Beta}* of 0.1 m can be achieved at a beam energy of 50 TeV. Only two families of sextupoles are needed to globally correct the chromaticity. Since the momentum spread of the beam is small ({sigma}{sub p} {approx} 2 x 10{sup -5}), a relatively large (about 20) linear chromaticity can be tolerated so that higher-order chromatic aberration produced by the low-{Beta}* optics is negligible. With a crossing angle of 70 {mu}r and a beam separation of 5 {sigma}, the required minimum aperture of the triplet magnets is about 3 cm. The luminosity reduction resulted from such a crossing angle is about 13%. Crab crossing can be used to further reduce {Beta}* to below 0.05 m. At the same time, luminosity degradation caused by the angle crossing is eliminated. With crab cavities positioned near the triplet operating at a voltage of a few MV, the required voltage of the 379 MHz storage rf system can be reduced from the nominal 100 MV to below 10 MV. The requirements on the accuracy of the positioning of the crab cavities and the operating voltage are both moderate. More than two families of sextupoles are needed for global chromatic compensation only when, {Beta}* approaches 0.05 m and below.

Wei, Jie; Peggs, S.G. [Brookhaven National Lab., Upton, NY (United States); Goderre, G.P. [Fermi National Accelerator Lab., Batavia, IL (United States)

1996-12-01

226

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

Microsoft Academic Search

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

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

227

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

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

228

Phylogenetic diversity of dissimilatory ferric iron reducers in paddy soil of Hunan, South China  

Microsoft Academic Search

Purpose  Dissimilatory iron-reducing bacteria have been described by both culture-dependent and -independent methods in various environments,\\u000a including freshwater, marine sediments, natural wetlands, and contaminated aquifers. However, little is known about iron-reducing\\u000a microbial communities in paddy soils. The goal of this study was to characterize iron-reducing microbial communities in paddy\\u000a soil. Moreover, the effect of dissolved and solid-phase iron (III) species on

Xin-Jun Wang; Jing Yang; Xue-Ping Chen; Guo-Xin Sun; Yong-Guan Zhu

2009-01-01

229

Dune field pattern formation and recent transporting winds in the Olympia Undae Dune Field, north polar region of Mars  

Microsoft Academic Search

High-Resolution Imaging Science Experiment (HiRISE) imagery of the central Olympia Undae Dune Field in the north polar region of Mars shows a reticulate dune pattern consisting of two sets of nearly orthogonal dune crestlines, with apparent slipfaces on the primary crests, ubiquitous wind ripples, areas of coarse-grained wind ripples, and deflated interdune areas. Geomorphic evidence and dune field pattern analysis

Ryan C. Ewing; Aymeric-Pierre B. Peyret; Gary Kocurek; Mary Bourke

2010-01-01

230

Development of bulk density, total C distribution and OC saturation in fine mineral fractions during paddy soil evolution  

NASA Astrophysics Data System (ADS)

Paddy soils are described as important accumulator for OM (Zhang and He, 2004). In southeast China, paddy soils have the second highest OM stocks (Zhao et al, 1997) and thus a large proportion of the terrestrial carbon is conserved in wetland rice soils. The paddy soil management is believed to be favorable for accumulation of organic matter, as its content in paddy soils is statistically higher than that of non-paddy soils (Cai, 1996). However, the mechanism of OM storage and the development of OM distribution during paddy soil evolution is largely unknown. The aim of the project is to identify the role of organo-mineral complexes for the stabilization of organic carbon during management-induced paddy soil formation in a chronosequence ranging from 50 to 2000 years of paddy soil use. The soil samples were analysed for bulk density, total organic carbon (TOC) and total inorganic carbon (TIC) concentrations of bulk soils and the concentration of organic carbon as well as the organic carbon stocks of physical soil fractions. First results indicate distinctly different depth distributions between paddy and non-paddy (control) sites. The paddy soils are characterized by relatively low bulk densities in the puddled layer (between 0.9 and 1.3 g cm-3) and high values in the plough pan (1.4 to 1.6 g cm-3) and the non-paddy soils by relatively homogeneous values throughout the profiles (1.3 to 1.4 g cm-3). In contrast to the carbonate-rich non-paddy sites, we found a significant loss of carbonates during paddy soil formation, resulting in decalcification of the upper 20 cm after 100 yr of paddy soil use, and decalcification of the total soil profile in 700, 1000 and 2000 yr old paddy soils. The calculation of the organic carbon stocks of each horizon indicate that paddy sites always have higher values in topsoils compared to non-paddy sites, and show increasing values with increasing soil age. The capacity of fine mineral fractions to preserve OC was calculated according to Hassink (1997). The potential capacity of paddy soil fraction to preserve OC is independently from soil age between 30 and 35.4 g OC (kg soil)-1. However, the calculated saturation level increases from 11.7 to 19.9 g OC (kg soil)-1 from 50 to 2000 y old paddy sites respectively. With increasing duration of paddy soil use, the fine fractions indicate an increasing saturation level from 33.1% to 56.2% of the potential capacity to preserve OC. This underlines the importance of fine fractions for increasing OC storage during paddy soil evolution. Conclusively, paddy soil management leads to an accelerated soil development compared to non-irrigated cropland sites. In addition, increasing OC stocks, especially in the fine mineral associated OM fractions underline the relevance of paddy soil management for OC sequestration. References Cai Z. (1996). Effect of land use on organic carbon storage in soils in eastern China. Water Air Soil Pollut 91, 383-393. Hassink J. (1997). The capacity of soil to preserve organic C and N by their association with clay and silt particles. Plant and Soil 191, 77-87. Zhang M., He Z. (2004). Long-term changes in organic carbon and nutrients of an Ultisol under rice cropping in southeast China. Geoderma 118, 167-179. Zhao C. (1996). Effect of land use on organic carbon storage in soils in eastern China. Water Air Soil Pollut 91, 383-393.

Wissing, Livia; Kölbl, Angelika; Cao, Zhi-Hong; Kögel-Knabner, Ingrid

2010-05-01

231

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

USGS Publications Warehouse

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.

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

2000-01-01

232

Abstract--Local mean-field models (MFMs) describe regional brain activities by some connected differential  

E-print Network

Abstract-- Local mean-field models (MFMs) describe regional brain activities by some connected. This method was used to investigate the role of slow modulatory variable in our EMFM when a typical anesthetic

Paris-Sud XI, Université de

233

Crustal melting in the Himalayan orogen : field, geochemical and geochronological studies in the Everest region, Nepal  

E-print Network

A combination of field studies and geochemical techniques were used to investigate the timing and processes involved in leucogranite generation in the Everest region of the Himalayan orogen. Geochemical investigations ...

Viskupic, Karen M. (Karen Marie), 1975-

2003-01-01

234

Field container as a regional strategy for revitalizing the Los Angeles River  

E-print Network

This thesis is the study of the Los Angeles River as a multi-layered field with urban condensers that revitalize the river, connect and revitalize the municipal districts bordering the river, and restructure the region to ...

Ghole, Saba (Saba Ashfaq)

2007-01-01

235

Electromagnetic field of a vertical electric dipole in the presence of a three-layered region  

Microsoft Academic Search

The electromagnetic field generated by a vertical electric dipole in the air over the surface of a two-layered region is determined for continuous-wave excitation. The region of interest consists of a conductor or dielectric with high permittivity, coated with an electrically thin layer of a dielectric under a half-space of air. Simple explicit formulas are derived for the field at

Ronald W. P. King; Sheldon S. Sandler

1994-01-01

236

Evaluation of potential effects of soil available phosphorus on soil arsenic availability and paddy rice inorganic arsenic content.  

PubMed

The transfer of arsenic from paddy field to rice is a major exposure route of the highly toxic element to humans. The aim of our study is to explore the effects of soil available phosphorus on As uptake by rice, and identify the effects of soil properties on arsenic transfer from soil to rice under actual field conditions. 56 pairs of topsoil and rice samples were collected. The relevant parameters in soil and the inorganic arsenic in rice grains were analyzed, and then all the results were treated by statistical methods. Results show that the main factors influencing the uptake by rice grain include soil pH and available phosphorus. The eventual impact of phosphorus is identified as the suppression of As uptake by rice grains. The competition for transporters from soil to roots between arsenic and phosphorus in rhizosphere soil has been a dominant feature. PMID:24598788

Jiang, Wei; Hou, Qingye; Yang, Zhongfang; Zhong, Cong; Zheng, Guodong; Yang, Zhiqiang; Li, Jie

2014-05-01

237

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

E-print Network

Magnetic field visualization of magnetic minerals and grain boundary regions using magneto to characterize magnetic minerals embedded in a nonmagnetic matrix. We have studied magnetite grains and magnetite-magnetite grain boundary regions in samples of skarns and serpentinites. Distributions of the remanent magnetic

Podladchikov, Yuri

238

Field Operations and Federal and Regional Policy Changes. Satellite Technology Demonstration, Technical Report No. 0334.  

ERIC Educational Resources Information Center

The Satellite Technology Demonstration (STD), through its unique field services network (the STD's Utilization Component), was able to develop and insure Project credibility among its many regional, state, and local participants. How the field service mechanism was used to maintain positive relationships between the STD and its many constituents…

Anderson, Frank; And Others

239

Coronal Currents, Magnetic Fields and Heating in a Solar Active Region  

E-print Network

coronal currents and heating of the corona. This extrapolation fully takes into account the nonuni­ form heating. Key words: Sun: corona --- Sun: magnetic fields --- Sun: radio radiation 1. INTRODUCTION OneCoronal Currents, Magnetic Fields and Heating in a Solar Active Region Jeongwoo Lee Astronomy

White, Stephen

240

Numerical analyses of trapped field magnet and stable levitation region of HTSC  

Microsoft Academic Search

Stable levitation with a permanent magnet and a bulk high Tc superconductor (HTSC) is examined numerically by using the critical state model and the frozen field model. Differences between a permanent magnet and a trapped field magnet are discussed in terms of the levitation force property. The stable levitation region of the HTSC on a ring magnet and on a

M. Tsuchimoto; T. Kojima; H. Waki; T. Honma

1995-01-01

241

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

E-print Network

field (HMF) measured by the Ulysses spacecraft during its mid-latitude transits of the heliosphere when where the HMF tends to be enhanced, the rarefaction regions with nearly radial magnetic fields tend of the HMF tended to be rather uniform in all HMF directions (0

Sanahuja, Blai

242

Flexible gas insulated transmission line having regions of reduced electric field  

DOEpatents

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.

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

243

Numerical analyses of trapped field magnet and stable levitation region of HTSC  

SciTech Connect

Stable levitation with a permanent magnet and a bulk high {Tc} superconductor (HTSC) is examined numerically by using the critical state model and the frozen field model. Differences between a permanent magnet and a trapped field magnet are first discussed from property of levitation force. Stable levitation region of the HTSC on a ring magnet and on a solenoid coil are calculated with the numerical methods. Obtained results are discussed from difference of the magnetic field configuration.

Tsuchimoto, M.; Kojima, T.; Waki, H.; Honma, T. [Hokkaido Univ., Sapporo (Japan)] [Hokkaido Univ., Sapporo (Japan)

1995-05-01

244

A characterization of the scattered acoustic intensity field in the resonance region for simple spheres.  

PubMed

The properties of the scattered acoustic vector fields generated by simple spheres illuminated by monotonic continuous wave (CW) plane waves are investigated. Analytical solutions are derived from general acoustic pressure scattering models and analyzed for wave numbers in the resonance region. Of particular interest is the understanding of the characteristics of the scattered acoustic vector field in the near-to-far-field transition region. The separable active and reactive components of the acoustic intensity are used to investigate the structural features of the scattered field components. Numerical results are presented for the near and transition regions for a rigid sphere. A method of mapping nulls in the scattered intensity field components is described. The analysis is then extended to include a simple fluid-filled boundary and finally the evacuated thin-walled shell. Near field acoustic intensity field structures are compared against mechanical material properties of vacuous shells. The ability to extract scattered field features is illustrated with measurements obtained from a recent in-air experiment using an anechoic chamber and acoustic vector sensor probes to measure the scattered acoustic vector field from rigid spheres. PMID:21568382

Barton, Robert J; Smith, Kevin B; Vincent, Harold T

2011-05-01

245

Effect of geometry on the nose-region flow-field of shuttle entry-configurations  

NASA Technical Reports Server (NTRS)

In order to determine the convective heat-transfer distribution for the nose region of the space shuttle entry configurations, a three-dimensional flow-field is described which may include extensive regions of separated flow. Because of the complexity of the flow field for the nose region, experimental data are needed to define the relation between the nose geometry and the resultant flow field. According to theoretical solutions of the three-dimensional boundary layer, the boundary layer separates from the leeward generator of a blunted cone at an alpha equal to the cone half-angle. Separation results from the transverse pressure gradient, i.e., the velocity derivative due to crossflow. The boundary layer limiting streamlines converge toward the singular point of sep aration. The separated region is bounded by an ordinary line of separation.

Bertin, J. J.; Faria, H. T.

1973-01-01

246

Fresnel-region fields and antenna noise-temperature calculations for advanced microwave sounding units  

NASA Technical Reports Server (NTRS)

A transition from the antenna noise temperature formulation for extended noise sources in the far-field or Fraunhofer-region of an antenna to one of the intermediate near field or Fresnel-region is discussed. The effort is directed toward microwave antenna simulations and high-speed digital computer analysis of radiometric sounding units used to obtain water vapor and temperature profiles of the atmosphere. Fresnel-region fields are compared at various distances from the aperture. The antenna noise temperature contribution of an annular noise source is computed in the Fresnel-region (D squared/16 lambda) for a 13.2 cm diameter offset-paraboloid aperture at 60 GHz. The time-average Poynting vector is used to effect the computation.

Schmidt, R. F.

1982-01-01

247

Radiographic film dosimetry for IMRT fields in the nearsurface buildup region.  

PubMed

Radiographic film dosimetry provides fast, convenient 2-D dose distributions, but is challenged by the dependence of film response on scatter conditions (i.e., energy dependence). Verification of delivered dose in the surface buildup region is important for intensity modulated radiation therapy (IMRT) when volumes of interest encroach on these regions (e.g., head/neck, breast). The current work demonstrates that film dosimetry can accurately predict the dose in the buildup region for IMRT, since 1) film dosimetry can be performed with sufficient accuracy for small fields and 2) IMRT is delivered by a series of "small" segments (step and shoot IMRT). This work evaluates the accuracy of X-OMAT V (XV) and Extended Dose Range (EDR) film for measurements from 2 mm to 15 mm depths for small fields and clinical IMRT beams. Film measurements have been compared to single point measurements made with a stereotactic diode and parallel plate ionization chamber (P11) and thermoluminescent dosimeters (TLD) at various depths for square (diode, P11) and IMRT (diode, TLD) fields. Film calibration was performed using an 8-field step exposure on a single film at 5 cm depth, which has been corrected to represent either small field or large field depth dependent film calibration techniques. Up to 10% correction for film response variation as a function of depth was required for measurements in the buildup region. A depth-dependent calibration can sufficiently improve the accuracy for IMRT calculation verification (i.e., < or = 5% uncertainty). A small field film calibration technique was most appropriate for IMRT field measurements. Improved buildup region dose measurements for clinical IMRT fields promotes improved dose estimation performance for (inverse) treatment planning and allows more quantitative treatment delivery validation. PMID:19020480

Roberson, Peter L; Moran, Jean M; Kulasekere, Ravi

2008-01-01

248

Observations of Magnetic Fields in Giant Molecular Clouds and in the Surrounding Interstellar Regions  

NASA Astrophysics Data System (ADS)

The formation of Giant Molecular Clouds (GMCs) is a poorly understood step in the star formation process. Magentic fields may play a role in GMC formation. We report the results of an observational study of magnetic fields in GMCs and in the less dense interstellar regions that surround them. SPARO (Submillimeter Polarimeter for Antarctic Remote Observations) is an instrument designed to measure 450 micron polarization using the two-meter Viper telescope located at South Pole station. It obtains excellent sensitivity to large-scale polarized emission. Using SPARO, we measured projected magnetic field directions in four GMCs: NGC6334, Carina, G333.6-0.2, and G331.5-0.1. There is a clearly defined mean field direction for each cloud. To obtain the magnetic field directions in the less dense regions, we used Heiles' optical "Stellar polarization catalogs agglomeration" (Astron. J., 2000). We estimated the mean field directions for about a dozen regions, each about 300pc in extent, including two that are centered near NGC6334 and Carina. For those two clouds, we find agreement between the field direction revealed by optical polarimetry and that measured using SPARO. The other two GMCs are too far to be studied using the Heiles catalog. Our results suggest that the physical processes leading to the formation of GMCs preserve the mean field direction. This work was supported by the National Science Foundation's Office of Polar Programs.

Li, H.; Griffin, G. S.; Krejny, M.; Novak, G.; Loewenstein, R. F.; Newcomb, M. G.; Calisse, P. G.; Chuss, D. T.

2005-12-01

249

Open-pit coal-mining effects on rice paddy soil composition and metal bioavailability to Oryza sativa L. plants in Cam Pha, northeastern Vietnam.  

PubMed

This study quantified Cd, Pb, and Cu content, and the soil-plant transfer factors of these elements in rice paddies within Cam Pha, Quang Ninh province, northeastern Vietnam. The rice paddies are located at a distance of 2 km from the large Coc Sau open-pit coal mine. Electron microprobe analysis combined with backscattered electron imaging and energy-dispersive spectroscopy revealed a relatively high proportion of carbon particles rimmed by an iron sulfide mineral (probably pyrite) in the quartz-clay matrix of rice paddy soils at 20-30 cm depth. Bulk chemical analysis of these soils revealed the presence of Cd, Cu, and Pb at concentrations of 0.146±0.004, 23.3±0.1, and 23.5±0.1 mg/kg which exceeded calculated background concentrations of 0.006±0.004, 1.9±0.5, and 2.4±1.5 mg/kg respectively at one of the sites. Metals and metalloids in Cam Pha rice paddy soils, including As, Cd, Cr, Cu, Hg, Mn, Ni, Pb, and Zn, were found in concentrations ranging from 0.2±0.1 to 140±3 mg/kg, which were in close agreement with toxic metal contents in mine tailings and Coc Sau coal samples, suggesting mining operations as a major cause of paddy soil contamination. Native and model Oryza sativa L. rice plants were grown in the laboratory in a growth medium to which up to 1.5 mg/kg of paddy soil from Cam Pha was added to investigate the effects on plant growth. A decrease in growth by up to 60% with respect to a control sample was found for model plants, whereas a decrease of only 10% was observed for native (Nep cai hoa vang variety) rice plants. This result suggests an adaptation of native Cam Pha rice plants to toxic metals in the agricultural lands. The Cd, Cu, and Pb contents of the native rice plants from Cam Pha paddies exceeded permitted levels in foods. Cadmium and Pb were highest in the rice plant roots with concentrations of 0.84±0.02 and 7.7±0.3 mg/kg, suggesting an intake of these metals into the rice plant as shown, for example, by Cd and Pb concentrations of 0.09±0.01 and 0.10±0.04 mg/kg respectively in the rice grain endosperm. The adaptation of native rice plants, combined with bioaccumulation ratios of 1±0.6 to 1.4±0.7 calculated for Cd transfer to the rice grain endosperm, and maximum Cd transfer factors of 4.3±2.1 to the plant roots, strongly suggest a continuous input of some toxic metals from coal-mining operations to agricultural lands in the region of Cam Pha. In addition, our results imply a sustained absorption of metals by native rice plant varieties, which may lead to metal accumulation (e.g., Cd) in human organs and in turn to severe disease. PMID:23990254

Martinez, Raul E; Marquez, J Eduardo; Hòa, Hoàng Th? Bích; Gieré, Reto

2013-11-01

250

Surface electrostatic field below weak precipitation and stratiform regions of mid-latitude storms  

NASA Astrophysics Data System (ADS)

The electrostatic field is measured below thunderstorms at two sites in south-western France thanks to a field mill. It is recorded with a 1-s time resolution, simultaneously to the precipitation current measured with a specific sensor. The variations of both parameters are analyzed for two cases out of three storms considered in the study. Cloud-to-Ground (CG) lightning data from Météorage network and scans from a C-band radar included in the French network ARAMIS are used to characterize the storms. The magnitude of the electrostatic field can reach large values below the weak precipitation regions compared to the convective regions: between 5 and 6 kV m- 1, and between 2 and 3 kV m- 1, respectively. The field polarity is commonly negative (downward field) but it can reverse as the rainfall carries positive charge to the ground. So, the mirror effect is generally observed between the electrostatic field and the precipitation current. The electrostatic field magnitude can indicate the presence of large amounts of charge within the weak precipitation region above, although the lightning ground strokes remain relatively far. The fast field variations produced by CG flashes are analyzed. A strong dissymmetry for both CG polarities is observed: the + CG flashes can produce larger field discontinuities (~ 10 kV m- 1) even when their striking points are at about a distance of 40 km from the sensor, while the - CG flashes produce discontinuities lower than 4 kV m- 1 even when the striking points are within 4 km around the sensor. This indicates that either the charge removed by a + CG flash can be horizontally displaced with respect to the ground stroke location, or it can be much larger compared to that removed by a negative CG flash. Our observations suggest the surface electrostatic field measured below these regions may provide valuable information for estimating local lightning risk.

Soula, S.; Georgis, J. F.

2013-10-01

251

Sorption isotherms and isosteric heats of sorption of Malaysian paddy.  

PubMed

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

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

2014-10-01

252

The magnetic field of the H II region NGC 6334A from Faraday rotation  

NASA Astrophysics Data System (ADS)

We have studied the polarization characteristics and Faraday rotation of the extragalactic radio source J17204-3554, which appears projected on the north lobe of the Galactic H II region NGC 6334A. From observations made with the Very Large Array at 6.0 and 3.6 cm in three different epochs (1994, 1997 and 2006), we estimate a rotation measure of +5100 ± 900 rad m-2 for the extragalactic source. This large rotation measure implies a line-of-sight average magnetic field of B??+ 36 ± 6 ?G, the largest obtained by this method for an H II region. NGC 6334A is significantly denser than other H II regions studied and this larger magnetic field is expected on the grounds of magnetic flux conservation. The ratio of thermal to magnetic pressure is ˜5 in the range of values determined for more diffuse H II regions.

Rodríguez, L. F.; Gómez, Y.; Tafoya, D.

2012-02-01

253

Regional long-term co-operation in the field of nuclear and radiation emergency preparedness.  

PubMed

Emergency preparedness is generally covered by methodical and coordinative activities of the International Atomic Energy Agency (IAEA) in Member States of the IAEA and by the European Commission (EC) in EU Member and EU Accession Countries. However, the regional harmonisation of emergency arrangements is an important trend of emergency preparedness. The present paper gives a couple of illustrative examples for a regional co-operation in the field of emergency preparedness in Central Europe and an overview on international exercises in this region. The penultimate section contains an outlook on future activities regarding regional co-operation in Central Europe. The following topics have been suggested inter alia: the harmonisation of intervention criteria and countermeasures, co-ordination in the field of information of the public, comprehensive bi lateral and multilateral exercises, exchange of experts between the national nuclear emergency centres and inter-comparison calculations of the computer codes. PMID:15238659

Sladek, V; Metke, E; Janko, K; Hohenberg, J-K; Hofer, P

2004-01-01

254

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

PubMed

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

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

2012-02-01

255

Abundance and community structure of sulfate reducing prokaryotes in a paddy soil of southern China under different fertilization regimes  

Microsoft Academic Search

Flooded rice paddy soils represent a typical anaerobic freshwater habitat of microorganisms. The abundance and community structure of sulfate reducing prokaryotes (SRP) were investigated in order to understand their response to different fertilization practices in rice paddy, including control without fertilizers (CT) and arrangements of different chemical fertilizers of nitrogen (N), phosphorus (P) and potassium (K): N, NP, NK and

Xin-Zhan Liu; Li-Mei Zhang; James I. Prosser; Ji-Zheng He

2009-01-01

256

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

NASA Astrophysics Data System (ADS)

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.

Dias, F.; Assumpcao, M.

2012-12-01

257

Magnetic field in the end region of the SSC quadrupole magnet  

SciTech Connect

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.

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

1991-06-01

258

On a plasma sheath separating regions of oppositely directed magnetic field  

Microsoft Academic Search

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

E. G. Harris

1962-01-01

259

Combined Sewer Network in Hilly Region: Field Survey and Pollutant Overflow Optimization  

Microsoft Academic Search

\\u000a Combined sewer networks in hilly regions present unusual and unexplored issues due to the high flow velocity which characterizes\\u000a sloped systems. This work aims to present the results of a field survey carried out at the experimental combined sewer urban\\u000a drainage system of Volterra (Tuscany, Italy, total surface 146 ha, maximum slope 14%). Field data have been used to calibrate

Stefano Pagliara; Iacopo Carnacina; Michele Palermo

260

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

Microsoft Academic Search

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

Diego Sánchez de Lozada; Philippe Baveye; Susan Riha

1998-01-01

261

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

NASA Astrophysics Data System (ADS)

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.

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

2009-07-01

262

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

NASA Astrophysics Data System (ADS)

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.

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

2013-07-01

263

How is magnetic-field configuration related to upflows in active regions?  

NASA Astrophysics Data System (ADS)

Using three-dimensional magnetohydrodynamic (MHD) simulations, we demonstrate the flux emergence to derive features of magnetic-field configuration formed on the Sun. These features depend on a twist parameter of magnetic field: strongly or weakly twisted fields. We focus on a flux expansion factor which represents the expansion rate of the cross section along a flux tube. We derive the expansion factor, magnetic field, current density (twist of the magnetic field) and effective gravity of coronal loops in a self-consistently formed active region via flux emergence, and investigate how these quantities are related to the flow system of the active region. We found clear correlations among the strength of the vertical magnetic field, current density, expansion factor, and upflow location. On the basis of simulation results, we also study the plasma properties of a real active region which is observed by Nobeyama Radioheliograph (NoRH), X-Ray Telescope (XRT), and Extreme Ultraviolet Imaging Spectrometer (EIS) onboard Hinode. We discuss how these simulation and observation results tell about the mechanism of the solar wind.

Lee, H.; Magara, T.; An, J.; Kang, J.

2012-12-01

264

Nitrogen cycling in rice paddy environments: past achievements and future challenges.  

PubMed

Nitrogen is generally the most limiting nutrient for rice production. In rice paddy soils, various biochemical processes can occur regarding N cycling, including nitrification, denitrification, and nitrogen fixation. Since its discovery in the 1930s, the nitrification-denitrification process has been extensively studied in Japan. It may cause N loss from rice paddy soils, while it can also reduce environmental pollutions such as nitrate leaching and emission of nitrous oxide (N(2)O). In this review article, we first summarize the early and important findings regarding nitrification-denitrification in rice paddy soils, and then update recent findings regarding key players in denitrification and N(2)O reduction. In addition, we also discuss the potential occurrence of other newly found reactions in the N cycle, such as archaeal ammonia oxidization, fungal denitrification, anaerobic methane oxidation coupled with denitrification, and anaerobic ammonium oxidation. PMID:22008507

Ishii, Satoshi; Ikeda, Seishi; Minamisawa, Kiwamu; Senoo, Keishi

2011-01-01

265

[Phylogenetic diversity of dissimilatory Fe(III)-reducing bacteria in paddy soil].  

PubMed

Microorganism-mediated dissimilatory Fe (III) reduction is recognized as the dominant mechanism for Fe(III) reduction to Fe(II) in non-sulfidogenic anaerobic environments, but the microorganisms involved, especially in paddy soil, are still poorly understood. In this paper, an enrichment culture was conducted to study the phylogenetic diversity of Fe (III)-reducing bacteria in paddy soil, with acetate or hydrogen as the electron donor and with ferrihydrite or goethite as the electron acceptor, and by the methods of terminal-restriction fragment length polymorphism (T-RFLP) technology and 16S rRNA genes cloning and sequencing. No matter what the electron donor and electron acceptor were supplemented, the most abundant microorganisms were Geobacter and Clostridiales, and Rhodocyclaceae were also abundant, when acetate was supplemented as electron donor, which suggested that besides Geobacter, Clostridiales and Rhodocyclaceae could be also the important Fe(III)-reducing bacteria in paddy soil. PMID:22263478

Li, Hui-juan; Peng, Jing-jing

2011-10-01

266

Martian ionospheric conductivities in the magnetic pileup and crustal field regions  

NASA Astrophysics Data System (ADS)

The Martian ionosphere is permeated by an extremely variable magnetic field that results from both the interplanetary magnetic field and the palaeomagnetic fields that emanate from magnetized portions of the planet's crust. This spatially and temporally varying magnetic field directly affects the ion and electron gyrofrequencies. In turn, the magnetic field and gyrofrequencies, together with the collision frequencies and the electron concentration, determine the parallel, Pedersen and Hall conductivities that characterize current flow in the ionosphere. We present the findings of an investigation of these conductivities undertaken using data obtained by the Mars Global Surveyor (MGS) and Mars Express (MEX) spacecraft. The magnetic field data were collected by MGS during the aerobraking phase of its mission, while the modelled electron concentration is consistent with data obtained by MEX. Results are shown from a region with strong crustal fields and also from an area where the magnetic pileup region may be identified clearly. The altitudinal dependence of the calculated conductivities is generally characterized by three maxima, corresponding to ion Pedersen, electron Hall and electron Pedersen conductivity layers.

Dhillon, Ranvir; Opgenoorth, Hermann; Rosenqvist, Lisa; Lester, Mark; Brain, David; Withers, Paul; Edberg, Niklas; Milan, Steve

2010-05-01

267

The magnetic field structure in high-mass star formation regions  

NASA Technical Reports Server (NTRS)

We present a preliminary analysis of far-IR polarimetric observations, which were made to study the magnetic field structure in the high-mass star formation regions of M42, NGC2024, and W3. These observations were made from the Kuiper Airborne Observatory (KAO), using the University of Chicago far-IR polarimeter, Stokes.

Davidson, Jacqueline A.; Schleuning, D.; Dotson, J. L.; Dowell, C. Darren; Hildebrand, Roger H.

1995-01-01

268

Phase singularities of the longitudinal field components in the focal region  

E-print Network

frequency is incident on the lens with the electric field polarized in the x direction. The notation that can be annihilated when the aperture angle of the lens is changed. © 2004 Optical Society of America in the focal region of such a system. For the case of a monochromatic, lin- early polarized plane wave

Visser, Taco D.

269

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

E-print Network

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

Ingólfsson, �lafur

270

[Distribution characteristics of soil cadmium in different textured paddy soil profiles and its relevance with cadmium uptake by crops].  

PubMed

Adopting atomic absorption spectrometry (novAA400), the present study investigated the distribution characteristics of soil cadmium (Cd) in different textured paddy soil profiles under rice-wheat rotation and its correlation with Cd uptake by rice and wheat in Chengdu Plain through repeatedly taking soil and plant samples at the fixed sites in the field. The results revealed that Cd in the paddy soil profiles was mainly concentrated at the plough layer (0-15 cm) that obviously featured 'Cd accumulates towards the rooting layer'. Soil total Cd and available Cd (1 mol x L(-1) MgCl2 extraction) in the profile declined with soil depths and its average values at 30-45 cm only accounted for 47.60% and 39.49% of those at 0-15 cm. The potential downward movement of Cd in the different textured soil profiles was observed as sandy loam > heavy loam > loam. There was no significant correlation between soil pH and available Cd(r = - 0.46) at 0-15 cm soil depth, while significantly negative correlations between soil pH and available Cd were observed at 15-30 cm (r = -0.78) and 30-45 cm (r = -0.86). The results further demonstrated that the Cd contents in either grain or straw of rice and wheat were not well correlated with soil total Cd at any soil depth (r = -0.092-0.383 for rice and r = 0.174-0.424 for wheat), but significantly correlated with soil available Cd at 0-15 cm and at 15-30 cm (r = 0.766*-0.953**) despite insignificant correlation at 30-45 cm (r = 0.526-0.584). It is strongly suggested that the soil available Cd can be used as a better criterion than the total soil Cd to rate Cd contaminated soils in relation to safety of agricultural products. PMID:23697136

Qin, Yu-Sheng; Zhan, Shao-Jun; Yu, Hua; Tu, Shi-Hua; Wang, Zheng-Yin

2013-02-01

271

Sources of nitrous and nitric oxides in paddy soils: nitrification and denitrification.  

PubMed

Rice-paddies are regarded as one of the main agricultural sources of N 2O and NO emissions. To date, however, specific N2O and NO production pathways are poorly understood in paddy soils. (15)N-tracing experiments were carried out to investigate the processes responsible for N2O and NO production in two paddy soils with substantially different soil properties. Laboratory incubation experiments were carried out under aerobic conditions at moisture contents corresponding to 60% of water holding capacity. The relative importance of nitrification and denitrification to the flux of N2O was quantified by periodically measuring and comparing the enrichments of the N2O, NH(+)4-N and NO(-)3-N pools. The results showed that both N2O and NO emission rates in an alkaline paddy soil with clayey texture were substantially higher than those in a neutral paddy soil with silty loamy texture. In accordance with most published results, the ammonium N pool was the main source of N2O emission across the soil profiles of the two paddy soils, being responsible for 59.7% to 97.7% of total N2O emissions. The NO(-)3-N pool of N2O emission was relatively less important under the given aerobic conditions. The rates of N2O emission from nitrification (N2On) among different soil layers were significantly different, which could be attributed to both the differences in gross N nitrification rates and to the ratios of nitrified N emitted as N2O among soil layers. Furthermore, NO fluxes were positively correlated with the changes in gross nitrification rates and the ratios of NO/N2O in the two paddy soils were always greater than one (from 1.26 to 6.47). We therefore deduce that, similar to N2O, nitrification was also the dominant source of NO in the tested paddy soils at water contents below 60% water holding capacity. PMID:25079271

Lan, Ting; Han, Yong; Roelcke, Marco; Nieder, Rolf; Car, Zucong

2014-03-01

272

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

SciTech Connect

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.

Sinclair, K.

2005-05-01

273

Evidence of regional structural controls on vent distribution - Springerville volcanic field, Arizona  

NASA Astrophysics Data System (ADS)

Several quantitative methods (including univariate statistics, cluster analysis, the Hough transform, and the two-point azimuth method) are used to search for vent clusters and alignments in the late Tertiary-Quaternary Springerville volcanic field (SVF) in Arizona. The results of the vent distribution analysis are compared with structural data collected in the field, showing that there is a relationship between observed patterns in the cinder cone distribution and the regional crustal structure. The results of the analysis clarify the relationship beetween the SVF volcanism and the neotectonic structures which dominate the geology of the region and yield clues regarding the mechanism governing the timing and the location of the cinder cone emplacement within the field.

Connor, Charles B.; Condit, Christopher D.; Crumpler, Larry S.; Aubele, Jayne C.

1992-08-01

274

Calm before the spawn: global coral spawning patterns are explained by regional wind fields  

PubMed Central

Most corals in tropical localities broadcast their gametes into the water column, yet we have a poor understanding of what forces reproductive schedules. Moreover, recent studies show considerable geographical variation in the duration of the coral spawning season. For example, on the Great Barrier Reef, corals display tight coupling, while corals in Kenya spawn over seven months. This study reconciles the regional variance by testing the hypothesis that regional wind fields are the corals' ultimate reproductive proxy. Regions with short calm periods should be more tightly coupled than regions with calm periods extending for several months. Regional wind fields were assessed at seven localities, between 1997 and 2006, using the 11 GHz channel radiometer tropical microwave imager (TMI) onboard the tropical rainfall measuring mission (TRMM). There was a direct positive relationship between the duration of regional calm periods and the coupling of mass coral spawning. Ultimate long-term evolutionary advantages of releasing gametes during calm periods ensure fertilization and facilitate larval retention and local recruitment. Coupling mass spawning with seasonally calm periods agrees strongly with recent genetic evidence of local dispersal and high local retention. PMID:19892757

van Woesik, R.

2010-01-01

275

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

NASA Astrophysics Data System (ADS)

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.

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

276

Extreme accumulation on Patagonian ice fields revealed by high-resolution regional climate modeling  

NASA Astrophysics Data System (ADS)

Gravimetric observations and differential DEM's indicate that the Patagonian ice fields are currently thinning and retreating. Little is known, however, on the mechanisms that drive this ice mass loss. In particular, surface mass balance (SMB) of the ice fields is poorly constrained, because the wet southern Andes climate complicates performing in-situ measurements. Instead, regional climate modeling may provide the first, independent estimate of the ice field's SMB. Here we present results from a high-resolution (5.5 km) regional atmospheric climate and multi-layer snow model (RACMO2), forced by ERA-Interim atmospheric and ocean surface fields (1979-2013). The model is evaluated using existing weather stations, precipitation gauges, and available glacier firn cores. Our results confirm the occurrence of extremely high accumulation on the higher portions of both ice fields (10-35 m w.e. of snow per year). Precipitation is abundant throughout the entire year, and driven by quasi-continuous atmospheric westerlies, in combination with significant orographic forcing. On the other hand, we find strong ablation on the outlet glacier tongues, although these are only partly resolved by the model grid. Integrated over the ice fields, we find no significant recent trend in the SMB.

Lenaerts, J.; van Wessem, M.; van den Broeke, M. R.; van Ulft, L.; van Meijgaard, E.; Schaefer, M.; Van De Berg, W.

2013-12-01

277

Closed-loop tests of a regional gravity field modelling approach using radial basis functions  

NASA Astrophysics Data System (ADS)

Since many high-resolution observations, e.g. from terrestrial and airborne gravimetry are only available in regional areas, regional gravity field modelling becomes more and more important as an extension of the traditional global modelling of the Earth's gravitational potential. However, a lot of open questions have to be answered and problems concerning a consistent model combination and application have to be solved. In contrast to global approaches using spherical harmonic functions, the choice of the set of basis functions for regional analysis is a central question. There exist various possibilities as wavelets, covariance functions, Slepian functions or mascons, whose advantages and disadvantages are not yet fully understood and completely studied. In the context of inter-comparing different approaches within the ICCT JSG0.3 we tested radial basis functions as one possible method for regional gravity field modelling. We set up a closed-loop computation using simulated gravity field observations for terrestrial, airborne and satellite measurement techniques. In this study we compute series expansion in terms of radial basis functions for various cases. Hereby we consider different spectral and spatial resolutions, we test different point grids for the location of the functions, we use input data sets from one observation type as well as from different types and we test different weighting procedures for the combined solutions. All results are compared with validation data sets on geographical grids at topographical height for two different study areas in Europe and South America. The analyses of the closed-loop tests give information on the internal accuracy of our regional gravity field modelling strategy. This helps to understand the interactions and relationships between different parameterizations and implementations.

Lieb, Verena; Buße, Kirsten; Schmidt, Michael; Dettmering, Denise; Bouman, Johannes

2014-05-01

278

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

PubMed

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

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

2012-09-01

279

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

NASA Technical Reports Server (NTRS)

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.

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

2000-01-01

280

The magnetic field structure of the central region in M 31  

NASA Astrophysics Data System (ADS)

Context. The Andromeda Galaxy (M 31) is the nearest grand-design spiral galaxy. Thus far, most studies in the radio regime concentrated on the 10 kpc ring. The central region of M 31 has significantly different properties than the outer parts: The star formation rate is low, and inclination and position angle are largely different from the outer disk. Aims: The existing model of the magnetic field in the radial range 6 ? r ? 14 kpc is extended to the innermost part r ? 0.5 kpc to ultimately achieve a picture of the entire magnetic field in M 31. Methods: We combined observations taken with the VLA at 3.6 cm and 6.2 cm with data from the Effelsberg 100-m telescope to fill the missing spacings of the synthesis data. The resulting polarization maps were averaged in sectors to analyse the azimuthal behaviour of the polarized intensity (PI), rotation measure (RM), and apparent pitch angle (?obs). We developed a simplified 3D model for the magnetic field in the central region to explain the azimuthal behaviour of the three observables. Results: Our 3D model of a quadrupolar or dipolar dynamo field can explain the observed patterns in PI, RM, and ?obs, while a 2D configuration is not sufficient to explain the azimuthal behaviour. In addition and independent of our model, the RM pattern shows that the spiral magnetic field in the inner 0.5 kpc points outward, which is opposite to that in the outer disk, and has a pitch angle of ?33°, which is much larger than that of 8°-19° in the outer disk. Conclusions: The physical conditions in the central region differ significantly from those in the 10 kpc ring. In addition, the orientation of this region with respect to the outer disk is completely different. The opposite magnetic field directions suggest that the central region is decoupled from the outer disk, and we propose that an independent dynamo is active in the central region. FITS files of the recombined Stokes IQU images at the two frequencies are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/571/A61

Gießübel, R.; Beck, R.

2014-11-01

281

Eco-toxicity and metal contamination of paddy soil in an e-wastes recycling area.  

PubMed

Paddy soil samples taken from different sites in an old primitive electronic-waste (e-waste) processing region were examined for eco-toxicity and metal contamination. Using the environmental quality standard for soils (China, Grade II) as reference, soil samples of two sites were weakly contaminated with trace metal, but site G was heavily contaminated with Cd (6.37 mg kg(-1)), and weakly contaminated with Cu (256.36 mg kg(-1)) and Zn (209.85 mg kg(-1)). Zn appeared to be strongly bound in the residual fraction (72.24-77.86%), no matter the soil was metal contaminated or not. However, more than 9% Cd and 16% Cu was present in the non-residual fraction in the metal contaminated soils than in the uncontaminated soil, especially for site G and site F. Compared with that of the control soil, the micronucleus rates of site G and site F soil treatments increased by 2.7-fold and 1.7-fold, respectively. Low germination rates were observed in site C (50%) and site G (50%) soil extraction treated rice seeds. The shortest root length (0.2377 cm) was observed in site G soil treated groups, which is only 37.57% of that of the control soil treated groups. All of the micronucleus ratio of Vicia faba root cells, rice germination rate and root length after treatment of soil extraction indicate the eco-toxicity in site F and G soils although the three indexes are different in sensitivity to soil metal contamination. PMID:19042085

Jun-hui, Zhang; Hang, Min

2009-06-15

282

Observations of photospheric magnetic fields and shear flows in flaring active regions  

NASA Technical Reports Server (NTRS)

Horizontal flows in the photosphere and subsurface convection zone move the footpoints of coronal magnetic field lines. Magnetic energy to power flares can be stored in the corona if the flows drive the fields far from the potential configuration. Videodisk movies were shown with 0.5 to 1 arcsecond resolution of the following simultaneous observations: green continuum, longitudinal magnetogram, Fe I 5576 A line center (mid-photosphere), H alpha wings, and H alpha line center. The movies show a 90 x 90 arcsecond field of view of an active region at S29, W11. When viewed at speeds of a few thousand times real-time, the photospheric movies clearly show the active region fields being distorted by a remarkable combination of systematic flows and small eruptions of new flux. Magnetic bipoles are emerging over a large area, and the polarities are systematically flowing apart. The horizontal flows were mapped in detail from the continuum movies, and these may be used to predict the future evolution of the region. The horizontal flows are not discernable in H alpha. The H alpha movies strongly suggest reconnection processes in the fibrils joining opposite polarities. When viewed in combination with the magnetic movies, the cause for this evolution is apparent: opposite polarity fields collide and partially cancel, and the fibrils reconnect above the surface. This type of reconnection, driven by subphotospheric flows, complicates the chromospheric and coronal fields, causing visible braiding and twisting of the fibrils. Some of the transient emission events in the fibrils and adjacent plage may also be related.

Tarbell, T.; Ferguson, S.; Frank, Z.; Title, A.; Topka, K.

1988-01-01

283

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...

284

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...

285

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...

286

Ozone formation along the California-Mexican border region during Cal-Mex 2010 field campaign  

NASA Astrophysics Data System (ADS)

The purpose of this study is to evaluate the ozone (O3) formation along the California-Mexico border region using the WRF-CHEM model in association with the Cal-Mex 2010 field campaign. Four two-day episodes in 2010 are chosen based on plume transport patterns: 1) May 15-16 (plume north), 2) May 29-30 (plume southwest), 3) June 4-5 (plume east), and 4) June 13-14 (plume southeast). Generally, the predicted O3 spatial patterns and temporal variations agree well with the observations at the ambient monitoring sites in the San Diego-Tijuana region, but in the Calexico-Mexicali region, the model frequently underestimates the observation. In the San Diego-Tijuana region, the morning anthropogenic precursor emissions in the urbanized coastal plain are carried inland and mixed with the local biogenic emissions during transport, causing the high O3 level over the mountain region. Biogenic emissions enhance the O3 concentrations by up to 40 ppb over the mountain region in the afternoon. The factor separation approach is used to evaluate the contributions of trans-boundary transport of emissions from California and Baja California to the O3 level in the California-Mexico border region. The Baja California emissions play a minor role in the O3 formation in the San Diego region and do not seem to contribute to the O3 exceedances in the region, but have large potential to cause O3 exceedances in the Calexico region. The California emissions can considerably enhance the O3 level in the Tijuana region. Generally, the California emissions play a more important role than the Baja California emissions on O3 formation in the border region (within 40 km to the California-Mexico border). On average, the O3 concentrations in the border region are decreased by 2-4 ppb in the afternoon due to the interactions of emissions from California and Baja California. Further studies need to be conducted to improve the sea breeze simulations in the border region for evaluating O3 formation.

Li, Guohui; Bei, Naifang; Zavala, Miguel; Molina, Luisa T.

2014-05-01

287

Evaluation of Atmospheric Electric Field as Increasing Seismic Activity Indicator on the example of Caucasus Region  

E-print Network

The present paper deals with reliability of a gradient of atmospheric electric field potential as an indicator of seismic activity increase. With this in view, records of atmospheric electric field potential gradients of Caucasus region for 1953-1992 with respect to periods before average and large earthquakes, which took place in the same time interval, were considered. It is worth to pay attention to the fact that the avalanche-like unstable model of fault formation based on theoretical model of self-generated seismo-electromagnetic oscillations of LAI system explains convincingly spectral succession of electromagnetic emission frequency of the periods preceding earthquakes.

Kachakhidze, M K; Kachakhidze, N K

2012-01-01

288

Evaluation of Atmospheric Electric Field as Increasing Seismic Activity Indicator on the example of Caucasus Region  

NASA Astrophysics Data System (ADS)

The present paper deals with reliability of a gradient of atmospheric electric field potential as an indicator of seismic activity increase. With this in view, records of atmospheric electric field potential gradients of Caucasus region for 1953-1992 with respect to periods before average and large earthquakes, which took place in the same time interval, were considered. It is worth to pay attention to the fact that the avalanche-like unstable model of fault formation based on theoretical model of self-generated seismo-electromagnetic oscillations of LAI system explains convincingly spectral succession of electromagnetic emission frequency of the periods preceding earthquakes.

Kachakhidze, M. K.; Kereselidze, Z. A.; Kachakhidze, N. K.

2013-01-01

289

Merged interaction regions and large-scale magnetic field fluctuations during 1991: Voyager 2 observations  

NASA Technical Reports Server (NTRS)

This paper analyzes Voyager 2 observations of the magnetic field between 33.6 AU and 36.2 AU during 1991 when extraordinary events were observed on the Sun and in the heliosphere. The magnetic field strength signal B(t) has the unusual form of two large transient merged interaction regions (MIRs) on a fluctuating background. The two MIRs moved past the spacecraft in 32 days and 18 days, respectively. The mean field strength in each transient MIR was approx. equals 2.6 times the mean field during the remaining part of the year (0.11 nT). Each of the MIRs is related to a fast stream. The magnetic field is strong throughout each stream, suggesting that the strong fields are carried by the streams as well as produced by shock and stream compression. The fluctuations in B(t) during 1991 are not multifractal, and the MIRs cannot be approximated as multifractal clusters of intense magnetic fields. The distribution of the hour-averaged magnetic field strengths is approximately lognormal over 90% of its intermediate range, and it has an exponential tail for B greater than the average magnetic field strength. The elevation angles of B have a normal distribution with a standard deviation of 16 deg +/- 4 deg. The distributions of the azimuthal angles of B in the ranges 1 deg - 180 deg and 180 deg - 360 deg are approximately normal over a more limited range, and non-Gaussian tails associated with nearly radial magnetic fields; the standard deviations are approx. equal to 40 deg. Individual sectors are present throughout most of the interval, even in the MIRs, but there is no recurrent sector pattern. A model of the large-scale fluctuations in 1991 will have to include both determinaistic and statistical factors.

Burlaga, L. F.; Ness, N. F.

1994-01-01

290

??????????????????????????????????????????????? ?????????????????????????????????????????????????????????? Paddy Soil Fertility Improvement for Rice Production through the Utilization of Chemical Fertilizer and Filter Cake  

Microsoft Academic Search

Filter cake is by - product of cane sugar manufacture. It consists of plant nutrient which is useful for soil fertility improvement. According to low fertility of most paddy soils, an experiment had been conducted with combination of chemical fertilizer application and filter cake incorporation for soil fertility and yield improvement in two different soil types in wet season during

Lop Buri

291

Mapping paddy rice agriculture in South and Southeast Asia using multi-temporal MODIS images  

Microsoft Academic Search

In this paper, we developed a new geospatial database of paddy rice agriculture for 13 countries in South and Southeast Asia. These countries have ?30% of the world population and ?2\\/3 of the total rice land area in the world. We used 8-day composite images (500-m spatial resolution) in 2002 from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor onboard the

Xiangming Xiao; Stephen Boles; Steve Frolking; Changsheng Li; Jagadeesh Y. Babu; William Salas; Berrien Moore

2006-01-01

292

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

NASA Astrophysics Data System (ADS)

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.

Ho, Adrian; Frenzel, Peter

2010-05-01

293

Study of Temperature and Moisture Distribution in Paddy in a Triangular Spouted Bed Dryer  

Microsoft Academic Search

A triangular spouted-bed dryer has been designed as part of a hexagonal continuous dryer for paddy. In the triangular-bed dryer, the spout of drying air is placed in one corner of the drying chamber. Combining six triangular units with the spout located in the center of the dryer allows a continuous process and reduces energy consumption due to the reduction

Wiyanto Bambang Bie; George Srzednicki; Robert H. Driscoll

2007-01-01

294

IntroductIon Rice paddies are one of the most productive and depend-  

E-print Network

44 IntroductIon Rice paddies are one of the most productive and depend- able agricultural systems. For example, the operation of a rice scheme typically involves use of fertilizers, herbicides, pesticides, and machinery. Rice, which is the dominant plant species, is under artificial rather than natural selection

de Villiers, Marienne

295

Microbial community composition controls the effects of climate change on methane emission from rice paddies.  

PubMed

Rice paddies are one of the most important sources of CH4 emission from the terrestrial ecosystem. A Free-air CO2 Enrichment (FACE) experiment, which included a soil warming treatment, was conducted in a rice paddy at Shizukuishi, Japan. In this study, the changes in CH4 emission from a rice paddy, caused by global climate change, were explored in relation to the structural changes that have occurred in the methanogenic archaeal communities found in the soil and roots. The composition of the archaeal community was examined by terminal restriction fragment length polymorphism (T-RFLP) using the 16S rRNA gene, while its abundance was measured by real-time PCR using the methyl coenzyme M reductase (mcrA) gene. The archaeal community in the roots showed considerable change, characterized by the dominance of hydrogenotrophic methanogens and a corresponding decrease in acetoclastic methanogens. Seasonal changes in CH4 flux were closely related to the changes in methanogen abundance in the roots. Elevated CO2 caused an increase in root mass, which increased the abundance of methanogens leading to a rise in CH4 emissions. However, soil warming stimulated CH4 emissions by increasing CH4 production per individual methanogen. These results demonstrated that climate warming stimulates CH4 emission in a rice paddy by altering the abundance and activity of methanogenic archaea in the roots. PMID:23760936

Liu, Guang Cheng; Tokida, Takesi; Matsunami, Toshinori; Nakamura, Hirofumi; Okada, Masumi; Sameshima, Ryoji; Hasegawa, Toshihiro; Sugiyama, Shu-Ichi

2012-12-01

296

Testing for Food Market Integration: A Study of the Vietnamese Paddy Market  

Microsoft Academic Search

This study examines whether there is spatial integration between and within paddy markets in the North and South of Vietnam. The empirical model developed uses estimates of transfer costs to generalize Ravallion's model of spatial market integration to allow for threshold effects. A sequential testing strategy is used to test for market segmentation, the number of thresholds, long-run integration, informational

Tran Ngo; Minh Tam; Bob Baulch; Henrik Hansen

2007-01-01

297

[Distribution characteristics of aggregates organic carbon in a paddy soil chronosequence].  

PubMed

By the method of physical fractionation of organic matter, this paper studied the distribution characteristics of organic carbon in different particle size aggregates in a paddy soil chronosequence on the south bank of Hangzhou Bay, East China. In the plow layers of the paddy soil chronosequence, micro-aggregates (<0. 25 mm) dominated, and the proportion of large micro-aggregates (0.053-0.25 mm) decreased with increasing rice cultivation year. In the micro-aggregates (<0. 053 mm and 0. 053-0. 25 mm), the organic carbon content increased with increasing rice cultivation time; and in the aggregates (0. 053-2 mm), the ratio of the organic carbon in different particle size fractions to the bulk soil organic carbon increased with decreasing particle size, and the organic carbon mainly distributed in large micro-aggregates (0. 053 -0. 25 mm). With increasing rice cultivation time, soil particulate organic carbon decreased, indicating that the paddy soil with a longer rice cultivation history had a stronger capability of carbon sequestration than the soil with a shorter rice cultivation history, and the early cultivated paddy soil still had great potential for carbon sequestration. PMID:23755486

Wang, Xin-Xin; Fu, Jian-Rong; Zou, Ping; Chen, Wei; Ye, Jing; Yu, Qiao-Gang; Jiang, Li-Na; Wang, Qiang

2013-03-01

298

Deleterious effects of fungi isolated from paddy soils on seminal root of rice  

Microsoft Academic Search

Soil samples were collected from rice paddies at 22 locations in northeastern Honshu, Japan. In 20 of the samples, seedling growth of rice was improved by soil pasteurization (aerated steaming at 60°C for 30?min), although no typical disease symptoms were observed in the seedlings grown in the untreated soil samples. In most locations, rice seedlings grew better in a potting

Hiromitsu Furuya; Keisuke Tubaki; Tsutomu Matsumoto; Shin-ichi Fuji; Hideki Naito

2005-01-01

299

Chemical and morphological changes of porous hydrated calcium silicate in paddy soil  

Microsoft Academic Search

The chemical and morphological changes of porous hydrated calcium silicate material (PS) during the dissolution process in paddy soil were investigated by using both a scanning electron microscope (SEM) and an energy dispersive X-ray (EDX) analysis. The results showed that original PS consisted of agglomerate of various sizes with almost the same elemental composition. The SEM images at a high

Akiko Yamamoto; Masahiko Saigusa; Masami Nanzyo

2000-01-01

300

Effect of Interhemispheric Field-Aligned Currents on Region-1 Currents  

NASA Astrophysics Data System (ADS)

asymmetry in ionospheric conductivity between two hemispheres results in the formation of additional, interhemispheric field-aligned currents (FACs) flowing between conjugate ionospheres within two auroral zones. These interhemispheric currents are especially significant during summer-winter conditions when there is a significant asymmetry in ionospheric conductivity in two hemispheres. In such conditions, these currents may be comparable in magnitude with the Region 1 (R1) field-aligned currents. In this case, the R1 current is the sum of two FACs: one is going from/to the solar wind, and another is flowing between conjugate ionospheres. These interhemispheric currents can also cause the formation of auroras extended along the nightside polar cap boundary, which may be related to the so-called "double auroral oval." In this study, we present the results of analytical and numerical solutions for the interhemispheric currents and their effect on the Region 1 currents.

Lyatskaya, Sonya; Lyatsky, Wladislaw; Khazanov, George V.

2014-06-01

301

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

Microsoft Academic Search

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

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

2010-01-01

302

Large and small-scale magnetic fields in star-forming regions  

NASA Astrophysics Data System (ADS)

We present numerical and observational studies aimed at analyzing the potential of multi-wavelength high-spatial resolution continuum polarization measurements for constraining the multi-scale structure of magnetic fields in the interior and environment of molecular clouds. Numerical simulations: We developed an extended, adaptive grid version of the 3D Monte-Carlo radiation transfer code MC3D (Wolf et al., 1999, 2003) for multi-wavelength polarization simulations. On the basis of theoretical dust grain models, polarization due to dichroic extinction and reemission as well as scattering is considered. Multi-scale magneto-hydrodynamical (MHD) simulations of the interstellar medium (ISM) provide the complex distributions of the density, temperature, and magnetic field in star-forming regions. This type of sophisticated synthetic polarization modeling will allow us to prepare and properly analyze existing and future observations of the three-dimensional magnetic field structure in the ISM. Various kinds of dust grain properties and advanced MHD scenarios are considered to cover the broad variety of observable ISM characteristics. Observations: Bok globules represent an ideal environment to study the influence of magnetic fields on the process of low-mass star formation. The magnetic field strength and structure in the dense inner regions of the globules can be determined by observing the polarized reemission radiation of aligned dust grains in the sub-mm wavelength range. The magnetic field in the outer, less dense parts of the globules can be traced by observing polarized radiation of background stars in the optical or near-IR. We present polarimetric observations of two Bok globules, CB68 and B335, carried out in the near-IR (ISAAC/VLT) and in the optical (IFOSC/IGO). Together with archival sub-mm data (SCUBA/JCMT), we trace the magnetic fields in these objects from 10^3 AU scales up to 10^5-10^6 scales for the first time.

Reissl, Stefan; Bertrang, Gesa; Wolf, Sebastian; Banerjee, Robi; Das, Himadri Sekhar; Seifried, Daniel; Körtgen, Bastian

2013-07-01

303

Evaluation of regional numerical weather prediction model surface fields over the Middle Atlantic Bight  

NASA Astrophysics Data System (ADS)

Coastal ocean models often rely on the surface fields from numerical weather prediction (NWP) models for realistic surface boundary conditions, but the errors in these fields are poorly understood. We evaluate the surface meteorological and flux fields provided by three of the regional NWP models in operation during 1996 and 1997 at the U.S. National Centers for Environmental Prediction (NCEP): the Eta-48, Eta-29, and Rapid Update Cycle (RUC-1) models. These model fields are compared to in situ measurements made from an air-sea interaction buoy deployed from July 1996 to June 1997 at a midshelf location in the Middle Atlantic Bight during the Coastal Mixing and Optics experiment. In addition, data from six National Data Buoy Center buoys are used to evaluate spatial errors in the model fields. The Eta-29 and RUC-1 models overestimate the net ocean-to-atmosphere heat flux by an average 83 and 74 W m-2, respectively, with notable errors in each of the individual heat flux components. The poorly resolved sea surface temperature fields used in the 1996-1997 regional NWP models lead to significant errors in the latent and sensible heat fluxes over the continental shelf and slope. Moreover, wind speeds are slightly overestimated in the Eta-48 and Eta-29 models while the RUC-1 model underestimates them by more than 1 m s-1. All of the models have mean wind direction errors of 7° to 13° east of north. In light of these evaluations, considerations for improving the accuracy of the surface flux fields for use in future ocean modeling studies are discussed.

Baumgartner, Mark F.; Anderson, Steven P.

1999-08-01

304

Four large-scale field-aligned current systmes in the dayside high-latitude region  

NASA Technical Reports Server (NTRS)

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).

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

305

Estimating Regional Hydraulic Conductivity Fields—A Comparative Study of Geostatistical Methods  

Microsoft Academic Search

Geostatistical estimations of the hydraulic conductivity field (K) in the Carrizo aquifer, Texas, are performed over three regional domains of increasing extent: 1) the domain corresponding\\u000a to a three-dimensional groundwater flow model previously built (model domain); 2) the area corresponding to the 10 counties\\u000a encompassing the model domain (County domain), and; 3) the full extension of the Carrizo aquifer within

Delphine Patriarche; Maria Clara Castro; Pierre Goovaerts

2005-01-01

306

Field experiment of subgrade vibration induced by passing train in a seasonally frozen region of Daqing  

Microsoft Academic Search

The vibration characteristics and attenuation of the subgrade caused by passing trains in a seasonally frozen region of Daqing,\\u000a China are investigated. Three field experiments were conducted during different times through the year, in normal, freezing\\u000a and thawing periods, respectively, and the influence of the season, train speed and train type, is described in this paper.\\u000a The results show that:

Xianzhang Ling; Feng Zhang; Zhanyuan Zhu; Lin Ding; Qingli Hu

2009-01-01

307

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

Microsoft Academic Search

Magneto-optical imaging based on the Faraday effect has been used to characterize magnetic minerals embedded in a nonmagnetic matrix. We have studied magnetite grains and magnetite-magnetite grain boundary regions in samples of skarns and serpentinites. Distributions of the remanent magnetic field were measured across at the surface of polished thin sections kept at room temperature. The magneto-optical images resolve directly

Alexander V. Bobyl; Yuri Y. Podladchikov; Håkon Austrheim; Bjørn Jamtveit; Tom H. Johansen; Daniel V. Shantsev

2007-01-01

308

The Southern African Regional Science Initiative (SAFARI 2000): overview of the dry season field campaign  

Microsoft Academic Search

The Southern African Regional Science Initiative (SAFARI 2000) is an international science project investigating the earth-atmosphere-human system in southern Africa. The programme was conducted over a two-year period from March 1999 to March 2001. The dry season field campaign (August-September 2000) was the most intensive activity and involved over 200 scientists from eighteen countries. The main objectives were to charac-

J. T. Suttles; J. Haywood; M. C. Helmlinger; C. Hely; P. V. Hobbs; B. N. Holben; J. Ji; M. D. King; T. Landmann; W. Maenhaut; L. Otter; B. Pak; S. J. Piketh; S. Platnick; J. Privette; D. Roy; A. M. Thompson; D. Ward; R. Yokelson

2002-01-01

309

A method to determine regional lunar gravity fields from earth-based satellite tracking data  

Microsoft Academic Search

A method to determine regional gravity fields of the Moon from Earth-based Doppler and range satellite tracking data residuals of a low Moon-orbiting satellite has been developed and thoroughly tested in a controlled simulation environment. A short-arc approach, where one arc consists of the time it takes the satellite to cross the grid of interest on the lunar surface, is

S. Goossens; P. N. A. M. Visser; B. A. C. Ambrosius

2005-01-01

310

A modified EK method with an I ? \\/I 2 lixiviant assisted and approaching cathodes to remedy mercury contaminated field soils  

Microsoft Academic Search

Wanshan mercury mine is the largest cinnabar deposit in Guizhou, China. Few effective methods had been achieved to remedy\\u000a Hg heavily contaminated field soils. In this paper, a modified EK method with approaching cathodes (AC-EK) and an I?\\/I2 lixiviant was described to remedy mercury-contaminated field soils near Wanshan mercury mine. Paddy Soil I and Paddy Soil\\u000a II were sampled and

Zhemin Shen; Jianda Zhang; Liya Qu; Zeqin Dong; Shenshen Zheng; Wenhua Wang

2009-01-01

311

The impact of changes in irrigation practices on the distribution of foraging egrets and herons (Ardeidae) in the rice fields of central Japan  

Microsoft Academic Search

Traditionally rice Oryza sativa fields in Japan are irrigated by diverting river water through shallow earth ditches using sluices and weirs. However this ‘old-style’ method is being replaced rapidly by a ‘new-style’ system in which water is pumped into paddy fields via taps and drained into deep concrete-sided canals. Concern has been expressed that the changes may cause paddy fields

Masahiro Fujioka

1998-01-01

312

An improved permanent magnet quadrupole design with larger good field region for high intensity proton linacs  

NASA Astrophysics Data System (ADS)

The Low Energy High Intensity Proton Accelerator (LEHIPA), being developed at the Bhabha Atomic Research Centre (BARC) will produce a 20 MeV, 30 mA, continuous wave (CW) proton beam. At these low velocities, space-charge forces dominate, and could lead to larger beam sizes and beam halos. Hence in the design of the focusing lattice of the LEHIPA drift tube linac (DTL) using permanent magnet quadrupoles (PMQs), a larger good field region is preferred. Here we study, using the two dimensional (2D) and three dimensional (3D) simulation codes PANDIRA and RADIA, four different types of cylindrical PMQ designs: 16-segment trapezoidal Halbach configuration, bullet-nosed geometry and 8- and 16-segment rectangular geometries. The trapezoidal Halbach geometry is used in a variety of accelerators since it provides very high field gradients in small bores, while the bullet-nosed geometry, which is a combination of the trapezoidal and rectangular designs, is used in some DTLs. This study shows that a larger good field region is possible in the 16-segment rectangular design as compared to the Halbach and bullet-nosed designs, making it more attractive for high-intensity proton linacs. An improvement in good-field region by ˜16% over the Halbach design is obtained in the optimized 16-segment rectangular design, although the field gradient is lower by ˜20%. Tolerance studies show that the rectangular segment PMQ design is substantially less sensitive to the easy axis orientation errors and hence will be a better choice for DTLs.

Mathew, Jose V.; Rao, S. V. L. S.; Krishnagopal, S.; Singh, P.

2013-11-01

313

Computational Analysis of the Flow Field Near the Boat-tail Region of Annular Plug Nozzles  

NASA Astrophysics Data System (ADS)

Flow fields over annular plug nozzles are computationally simulated and the boat-tail drag characteristics are clarified and discussed based on the simulation results. The plug nozzle configuration is taken from the ATREX (Air Turbo Ramjet) engine under development at the ISAS. The simulations are carried out for the axi-symmetric nozzle configuration using compressible Navier-Stokes equations. The computed result shows that there exists a low pressure region downstream of the Prandtl-Meyer expansion on the boat-tail region and the separation shock wave appears due to the interaction of the main flow and the nozzle plume downstream. The result also shows that the primary cause of the boat-tail drag turns out to be the low pressure region downstream of the Prandtl-Meyer expansion. The flow field with the secondary flow injection is then simulated and the computed result shows that the pressure in the region in front of the separation shock wave increases and the secondary flow injection successfully reduces the boat-tail drag. The effect of the turbulence model used in the computation is discussed to ensure the reliability of the solutions.

Fujii, Kozo; Imai, Kazuhiro; Sato, Tetsuya

314

[Speciation and bioavailability of heavy metals in paddy soil irrigated by acid mine drainage].  

PubMed

Based on field investigation and laboratory analysis, the speciation and bioavailability of the heavy metals (Cd, Cu, Pb, and Zn) was studied. These metals were tested from 16 soil samples taken from paddy soils irrigated by acid mine drainage in the lower stream of Dabaoshan mine area, Guangdong Province, China. The toxicity characteristic leaching procedure (TCLP) and three-step community bureau of reference (BCR) sequential extraction procedure methods were used to analyse the bioavailability of heavy metals. TCLP is currently recognized as an international method for evaluation of heavy metal pollution in soils. Two methods were compared in bioavailability by stepwise multiple linear regression analysis. Cd was dominated mainly by the acid-extractable and residual fractions, and followed by the order of acid-extractable > residual > oxidisable > reducible. Cu was dominated mainly by the residual fraction, and decreased in the following order: residual > reducible > acid-extractable > oxidisable. Pb was dominantly released in the reducible and residual fractions, they account for 86.54% of the total contents, and decreased in the following order: reducible > residual > acid-extractable > oxidisable. Zn was dominated mainly by the residual fraction, it takes more than 50% of the total contents, and followed by the order of residual > acid-extractable > reducible > oxidisable. The levels of Cd, Cu, Pb and Zn extracted by TCLP were 0.17-0.89, 8.12-70.33, 3.16-90.33 and 10.24-106.85 mg x kg(-1), respectively, and the average concentrations of Cd, Cu, Pb and Zn were 0.41, 36.60, 15.97 and 50.78 mg x kg(-1), respectively. The concentrations of Cd, Cu, Ph and Zn in rice seeds were 0.183-0.947, 3.542-5.997, 0.285-1.532 and 17.54-41.10 mg x kg(-1), respectively. Comparing to the national standards on heavy metals in foods by the Chinese Ministry of Health, the contents of Cu and Zn in rice seeds didn't exceed the upper limit, while the contents of Cd and Pb in rice seeds exceed the upper limit by 87.50% and 81.25%, respectively. Results of the stepwise multiple linear regression analysis revealed that contents of Cd and Zn in seeds of rice were significantly influenced by contents of acid-extractable Cd and Zn, that contents of Cu in seeds of rice were significantly influenced by contents of acid-extractable and oxidisable Cu, and the contents of Pb in seeds of rice were significantly influenced by contents of reducible Pb and organic matter. Contents of four metals in seeds of rice were significantly influenced by contents of metals extracted by TCLP, and the influences of total content, pH and organic matter were not significant. In short, TCLP method was fast, simple and suitable for evaluation of bioavailability of heavy metals in sewage-irrigated paddy soils by acid mine drainage. PMID:19432348

Xu, Chao; Xia, Bei-Cheng; Wu, Hai-Ning; Lin, Xiao-Fang; Qiu, Rong-Liang

2009-03-15

315

Distribution of the Crustal Magnetic Field in Sichuan-Yunnan Region, Southwest China  

PubMed Central

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

Bai, Chunhua; Kang, Guofa; Gao, Guoming

2014-01-01

316

Fault region localization (FRL): collaborative product and process improvement based on field performance  

NASA Astrophysics Data System (ADS)

Customer feedback in the form of warranty/field performance is an important and direct indicator of quality and robustness of a product. Linking warranty information to manufacturing measurements can identify key design parameters and process variables (DPs and PVs) that are related to warranty failures. Warranty data has been traditionally used in reliability studies to determine failure distributions and warranty cost. This paper proposes a novel Fault Region Localization (FRL) methodology to map warranty failures to manufacturing measurements (hence to DPs/PVs) to diagnose warranty failures and perform tolerance revaluation. The FRL methodology consists of two parts: 1. Identifying relations between warranty failures and DPs and PVs using the Generalized Rough Set (GRS) method. GRS is a supervised learning technique to identify specific DPs and PVs related to the given warranty failures and then determining the corresponding Warranty Fault Regions (WFR), Normal Region (NR) and Boundary region (BND). GRS expands traditional Rough Set method by allowing inclusion of noise and uncertainty of warranty data classes. 2. Revaluating the original tolerances of DPs/PVs based on the WFR and BND region identified. The FRL methodology is illustrated using case studies based on two warranty failures from the electronics industry.

Mannar, Kamal; Ceglarek, Darek

2005-11-01

317

[Spatial variability and management zone of soil major nutrients in tobacco fields in Qiannan mountainous region].  

PubMed

Spatial variability and management zone of soil major nutrients in tobacco fields in Qian-nan mountainous region were analyzed using geostatistics and fuzzy c-mean algorithm. Results indicated that the level of soil organic matter (OM) was moderate, and alkalytic nitrogen (AN), available phosphorus (AP) and available potassium (AK) were rich according to tobacco soil nutrient classification standards. Coefficients of variation (CV) of OM, AN, AP and AK were moderate. Contents of OM, AN, AP and AK fitted log-normal distributions. Correlation analysis showed moderate correlations between OM and AN, AP and AK. OM and AN were best described by Gaussian semivariogram models, while AP and AK were described by exponential models. The four nutrients displayed moderate spatial autocorrelation. There were significant differences among lag distances of four soil nutrients. OM, AN, AP and AK in the majority of studied regions varied at moderate to very rich levels, and deficiencies of OM, AN, AP and AK only accounted for 0.93%, 0.53%, 0.24% and 7.91% of the total studied region, respectively. Based on the results, the studied region was divided into two management zones (MZ), namely MZ1 and MZ2, accounting for 69. 8% and 30. 2% of the studied region respectively. The soil levels of OM, AN, AP and AK in MZ1 were significantly lower than those in MZ2 (P < 0.01). PMID:25223027

Wu, De-Chuan; Luo, Hong-Xiang; Song, Ze-Min; Guo, Guang-Dong; Chen, Yong-An; Li, Yu-Xiang; Jiang, Yu-Ping; Li, Zhang-Hai

2014-06-01

318

Properties of magnetic field fluctuations in boundary regions of the Earth's magnetosphere  

NASA Astrophysics Data System (ADS)

Statistical properties of magnetic field fluctuations in boundary regions of the Earth’s magnetosphere at different timescales were considered. Data with high resolution (22,5 Hz) obtained by Cluster mission from 2004 to 2010 were used. As a characteristic of the fluctuations on various time scales, changes in the shape and parameters of the probability density function and wave analysis were studied. In order for investigations of features of the probability density functions of magnetic field fluctuations we analyzed the statistical properties of the absolute value of magnetic field variations in the different regions of near earth space. Amplitude of fluctuations in the magnetosheath just after crossing bow shock exceeds in a few time amplitude of fluctuations for non-perturbed solar wind or the foreshock. The analysis of the height of maximum of the probability density functions and of the kurtosis values have shown the presence of different asymptotic modes which are characterized by different power laws. The use of the technique of probability density function for magnetic fluctuations has shown that at high frequencies the structure of turbulence differs from that in the low-frequency region. The critical scale corresponds to the scales of the Larmor radius of ions. The research of the statistical properties of boundary layers allows to determine the role of turbulent processes in the interaction of plasma flows with the magnetic obstacles, whether these are fields of planets, stars, or laboratory traps, and to reveal the actual mechanisms of the energy transformation in collisionless plasma. The work is done in the frame of complex program of NAS of Ukraine on space researches for 2012-1016, within the framework of the educational program No.2201250 “Education, Training of students, PhD students, scientific and pedagogical staff abroad” launched by the Ministry of Education and Science of Ukraine and under a partial support of the grant No. F 53.2/039.

Kozak, Liudmyla; Savin, Sergey; Lui, Anthony Tat Yin; Igor, Gala

319

Advantages and Limitations of Cluster Analysis in Interpreting Regional GPS Velocity Fields in California and Elsewhere  

NASA Astrophysics Data System (ADS)

Regional Global Positioning System (GPS) velocity observations are providing increasingly precise mappings of actively deforming continental lithosphere. Cluster analysis, a venerable data analysis method, offers a simple, visual exploratory tool for the initial organization and investigation of GPS velocities (Simpson et al., 2012 GRL). Here we describe the application of cluster analysis to GPS velocities from three regions, the Mojave Desert and the San Francisco Bay regions in California, and the Aegean in the eastern Mediterranean. Our goal is to illustrate the strengths and shortcomings of the method in searching for spatially coherent patterns of deformation, including evidence for and against block-like behavior in these 3 regions. The deformation fields from dense regional GPS networks can often be concisely described in terms of relatively coherent blocks bounded by active faults, although the choice of blocks, their number and size, is subjective and usually guided by the distribution of known faults. Cluster analysis applied to GPS velocities provides a completely objective method for identifying groups of observations ranging in size from 10s to 100s of km in characteristic dimension based solely on the similarities of their velocity vectors. In the three regions we have studied, statistically significant clusters are almost invariably spatially coherent, fault bounded, and coincide with elastic, geologically identified structural blocks. Often, higher order clusters that are not statistically significant are also spatially coherent, suggesting the existence of additional blocks, or defining regions of other tectonic importance (e.g. zones of localized elastic strain accumulation near locked faults). These results can be used to both formulate tentative tectonic models with testable consequences and to suggest focused new measurements in under-sampled regions. Cluster analysis applied to GPS velocities has several potential limitations, aside from the fact that any data set, even random data, can be clustered. First of all, the gap test for significance, when used to identify the number of clusters yielding the greatest significance level, typically selects a small number of clusters in a given region, usually 5 or less. Visual inspection of higher order clusters beyond this number may reveal suggestions of smaller blocks, distributed strain, or geologic structures, which can be sometimes be enhanced by applying the method to smaller, more focused sub-regions. Finally, GPS data precision and spatial density limit the degree to which distinct clusters can be resolved, pointing to the importance of higher precision (e.g. semi-continuous and continuous GPS sites) and the incorporation, if possible, of other data types , for example, InSAR deformation maps into the method.

Thatcher, W. R.; Savage, J. C.; Simpson, R.

2012-12-01

320

Voyager Observations of the Heliosheath Depletion Region and the Magnetic Fields Preceding it (Invited)  

NASA Astrophysics Data System (ADS)

Voyager 1 (V1) entered the heliosheath depletion region (HDR) for the first time on day 210, 2012 and the third time on day 238, 2012. Voyager 1 remained in the HDR until at least day 127, 2013. The magnetic field intensity (B) in the HDR has been >0.4 nT and the direction of the magnetic field has been within 10° of the Parker spiral field. Nevertheless a small long-term trend away from the Parker spiral direction was observed in the HDR. Trends in the magnetic field intensity were also observed. The fluctuations of the 48 sec averages of B are near the noise and digitization level of the instrument. One feature in B was related to electron plasma oscillations observed by the plasma wave experiment on V1. The sequence of events strongly suggests that the magnetic field perturbation is an outward propagating interplanetary shock, and that the electron plasma oscillations are upstream waves driven by an electron beam from the shock, such as is commonly observed in the inner region of the heliosphere. Voyager 1 crossed a sector boundary from ~203.62 to 210.20, 2012, just prior to entering the HDR the first time on day 2010. The character of the sector boundary was similar to that of the two sector boundaries preceding it during 2011 and 2012. No change in polarity was observed at the other four crossings of the HDR boundary. On average, B increased in the heliosheath from mid-2010 until V1 entered the HDR, but there were very large fluctuations of B on a scale of tens of days, ranging from ~0.05 nT to ~0.35 nT. No well-defined magnetic wall or magnetic barrier was observed by V1 in the heliosheath prior to entering the HDR.

Burlaga, L. F.; Ness, N.; Gurnett, D. A.; Kurth, W. S.

2013-12-01

321

A Review of Magnetic Anomaly Field Data for the Arctic Region: Geological Implications  

NASA Technical Reports Server (NTRS)

Due to its inaccessibility and hostile physical environment remote sensing data, both airborne and satellite measurements, has been the main source of geopotential data over the entire Arctic region. Ubiquitous and significant external fields, however, hinder crustal magnetic field studies These potential field data have been used to derive tectonic models for the two major tectonic sectors of this region, the Amerasian and Eurasian Basins. The latter is dominated by the Nansen-Gakkel or Mid-Arctic Ocean Ridge and is relatively well known. The origin and nature of the Alpha and Mendeleev Ridges, Chukchi Borderland and Canada Basin of the former are less well known and a subject of controversy. The Lomonosov Ridge divides these large provinces. In this report we will present a summary of the Arctic geopotential anomaly data derived from various sources by various groups in North America and Europe and show how these data help us unravel the last remaining major puzzle of the global plate tectonic framework. While magnetic anomaly data represent the main focus of this study recently derived satellite gravity data are playing a major role in Arctic studies.

Taylor, Patrick T.; vonFrese, Ralph; Roman, Daniel; Frawley, James J.

1999-01-01

322

A Review of Magnetic Anomaly Field Data for the Arctic Region: Geological Implications  

NASA Technical Reports Server (NTRS)

Due to its inaccessibility and hostile physical environment remote sensing data, both airborne and satellite measurements, has been the main source of geopotential data over the entire Arctic region. Ubiquitous and significant external fields, however, hinder crustal magnetic field studies. These potential field data have been used to derive tectonic models for the two major tectonic sectors of this region, the Amerasian and Eurasian Basins. The latter is dominated by the Nansen-Gakkel or Mid-Arctic Ocean Ridge and is relatively well known. The origin and nature of the Alpha and Mendeleev Ridges, Chukchi Borderland and Canada Basin of the former are less well known and a subject of controversy. The Lomonosov Ridge divides these large provinces. In this report we will present a summary of the Arctic geopotential anomaly data derived from various sources by various groups in North America and Europe and show how these data help us unravel the last remaining major puzzle of the global plate tectonic framework. While Magnetic anomaly data represent the main focus of this study recently derived satellite gravity data (Laxon and McAdoo, 1998) are playing a major role in Arctic studies.

Taylor, Patrick T.; vonFrese, Ralph; Roman, Daniel; Frawley, James J.

1999-01-01

323

The magnetic field structure of the central region in M31  

E-print Network

The Andromeda Galaxy (M31) is the nearest grand-design spiral galaxy. Thus far most studies in the radio regime concentrated on the 10 kpc ring. The central region of M31 has significantly different properties than the outer parts: The star formation rate is low, and inclination and position angle are largely different from the outer disk. The existing model of the magnetic field in the radial range 6picture of the entire magnetic field in M31. We combined observations taken with the VLA at 3.6 cm and 6.2 cm with data from the Effelsberg 100-m telescope to fill the missing spacings of the synthesis data. The resulting polarization maps were averaged in sectors to analyse the azimuthal behaviour of the polarized intensity (PI), rotation measure (RM), and apparent pitch angle (\\phi_obs). We developed a simplified 3-D model for the magnetic field in the central region to explain the azimuthal behaviour of the three observab...

Gießübel, René

2014-01-01

324

A general adaptation strategy for climate change impacts on paddy cultivation: special reference to the Japanese context  

Microsoft Academic Search

Climate changes due to global warming may affect paddy cultivation considerably. Climate changes directly affect rice plant\\u000a growth, and within paddy cultivation catchments, alter the hydrological regime including flood patterns and water availability\\u000a for irrigation, and drainage. Although increased atmospheric CO2 concentrations in the future may enhance plant growth through the CO2 fertilization effect, impacts of climate change on agriculture

Tsugihiro Watanabe; Takashi Kume

2009-01-01

325

[Profile of soil microbial biomass carbon in different types of subtropical paddy soils].  

PubMed

The soil microbial biomass carbon (C(mic)), one of the most active components of soil organic carbon (C(org)), is an effective indicator of soil quality. In the present study, five subtropical paddy soils developed from different parent materials were selected, and the distribution of C(mic) through the profiles was studied, as well as the relationship of C(mic) with C(org) and soil nutrients. The results showed that the contents of C(org) and C(mic) decreased markedly with increasing soil depth, ranging from 2.45 g x kg(-1) to 26.19 g x kg(-1) and from 4.55 mg x kg(-1) to 1 691.75 mg x kg(-1), respectively. They mainly concentrated in the surface layer (plough horizon and plough pan). The content of C(mic) varied significantly in paddy soils developed from different parent materials, with the highest one in yellow clayey soil, and the lowest ones in alluvial sandy soil and reddish yellow clayey soil. This was on the contrary to the distribution of C(org) in the surface paddy soils, since the reddish yellow clayey soil and alluvial sandy soil showed higher contents while other types of paddy soils exhibited similar contents of C(org). Notwithstanding, C(mic) was still controlled by the quantity of C(org) and positively correlated with C(org). The ratio of C(mic) to C(org)(C(mic)/C((org)) decreased with increasing soil depth and differed in the plough horizon between different paddy soils, with lower values in alluvial sandy soil (2.11%) and reddish yellow clayey soil (1.37%) but higher value in reddish yellow clayey soil I (8.24%). It indicated that the microbial substrate availability in alluvial sandy soil and reddish yellow clayey soil was lower than those in reddish yellow clayey soils. The content of C(mic) was significantly positively correlated with total nitrogen, alkali-hydrolyzable N and Olsen-P, but was irrelevant to available K. It is implied that the C(mic) was not only controlled by C(org), but also complicatedly interacted with soil nutrients in paddy soils. PMID:23798145

Sheng, Hao; Zhou, Ping; Yuan, Hong; Liao, Chao-Lin; Huang, Yun-Xiang; Zhou, Qin; Zhang, Yang-Zhu

2013-04-01

326

WIDE-FIELD INFRARED SURVEY EXPLORER OBSERVATIONS OF THE EVOLUTION OF MASSIVE STAR-FORMING REGIONS  

SciTech Connect

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.

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

327

An Experimental Study of the Near Field Region of a Free Jet with Passive Mixing Tabs  

NASA Technical Reports Server (NTRS)

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.

Bohl, D. G.; Foss, J. F.

1997-01-01

328

Wide-Field Infrared Survey Explorer Observations of the Evolution of Massive Star-Forming Regions  

NASA Technical Reports Server (NTRS)

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.

Koenig, X. P.; Leisawitz, D. T.; Benford, D. J.; Rebull, L. M.; Padgett, D. L.; Asslef, R. J.

2012-01-01

329

Wide-Field Infrared Survey Explorer Observations of the Evolution of Massive Star-Forming Regions  

NASA Technical Reports Server (NTRS)

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.

Koenig, X. P.; Leisawitz, D. T.; Benford, D. J.; Rebull, L. M.; Padgett, D. L.; Assef, R. J.

2011-01-01

330

The influence of continuous rice cultivation and different waterlogging periods on the morphology, clay mineralogy, Eh, pH and K in paddy soils  

NASA Astrophysics Data System (ADS)

The effect of different rice plantation periods on the properties of selected soils on an alluvial plain was studied. Soils were sampled in fields cultivated for 6, 16, 26, and over forty years. In each rice cultivated and nonrice cultivated field, three soil profiles and six nearby auger holes were studied. This study indicated that continuous rice cultivation changed the soil moisture regime from xeric to aquic, the soil color from brown to grayish, and the surface horizons from mollic to ochric epipedon. With increasing duration of cultivation, the abundance of redoximorphic features increased and the soil structure changed from granular or blocky to massive. Therefore, the soil order changed from Mollisols to Inceptisols. No illuviation and eluviation of clay minerals occurred as a consequence of the rice cultivation. X-ray diffraction analysis showed that the clay minerals in the nonrice cultivated field were illite, vermiculite, montmorillonite, kaolinite, and chlorite, and, in the rice field, they were illite, montmorillonite, kaolinite, and chlorite, respectively. However, with increasing the period of cultivation, the amount of illite and vermiculite decreased while the amount of montmorillonite increased. The pH values of the saturated soil surface during the middle stage of rice growth shifted toward neutrality. The Eh of the surface horizons of the paddy soils under the field conditions were +40, -12, -84, and -122 mV, respectively, while the Eh in the nonpaddy soils were close to +90 mV. The amounts of organic matter and available Fe, Mn, Zn, and Cu increased, while the available K decreased in the paddy soils.

Bahmaniar, M. A.

2008-01-01

331

Generation of parallel electric fields in the Jupiter-Io torus wake region  

NASA Astrophysics Data System (ADS)

Infrared and ultraviolet images have established that auroral emissions at Jupiter caused by the electromagnetic interaction with Io not only produce a bright spot, but an emission trail that extends in longitude from Io's magnetic footprint. Electron acceleration that produces the bright spot is believed to be dominated by Alfvén waves whereas we argue that the trail or wake aurora results from quasi-static parallel electric fields associated with large-scale, field-aligned currents between the Io torus and Jupiter's ionosphere. These currents ultimately transfer angular momentum from Jupiter to the Io torus. We examine the generation and the impact of the quasi-static parallel electric fields in the Io trail aurora. A critical component to our analysis is a current-voltage relation that accounts for the low-density plasma along the magnetic flux tubes that connect the Io torus and Jupiter. This low-density region, ˜ 2 R J from Jupiter's center, can significantly limit the field-aligned current, essentially acting as a “high-latitude current choke.” Once parallel electric fields are introduced, the governing equations that couple Jupiter's ionosphere to the Io torus become nonlinear and, while the large-scale behavior is similar to that expected with no parallel electric field, there are substantial deviations on smaller scales. The solutions, bound by properties of the Io torus and Jupiter's ionosphere, indicate that the parallel potentials are on the order of 1 kV when constrained by peak energy fluxes of a few milliwatts per square meter. The parallel potentials that we predict are significantly lower than earlier reports.

Ergun, R. E.; Ray, L.; Delamere, P. A.; Bagenal, F.; Dols, V.; Su, Y.-J.

2009-05-01

332

Generation of Parallel Electric Fields in the Jupiter-Io Torus Wake Region  

NASA Astrophysics Data System (ADS)

Infrared and ultraviolet images have established that auroral emissions at Jupiter caused by the electromagnetic interaction with Io not only produce a bright spot, but an emission trail that extends in longitude from Io's magnetic footprint. Electron acceleration that produces the bright spot is believed to be dominated by Alfvén waves whereas we argue that the trail or wake aurora results from quasi-static parallel electric fields associated with large-scale, field-aligned currents between the Io torus and Jupiter's ionosphere. These currents ultimately transfer angular momentum from Jupiter to the Io torus. We examine the generation and the impact of the quasi-static parallel electric fields in the Io trail aurora. A critical component to our analysis is a current-voltage relation that accounts for the low-density plasma along the magnetic flux tubes that connect the Io torus and Jupiter. This low density region, ~ 2 RJ from Jupiter's center, can significantly limit the field-aligned current, essentially acting as a "high-latitude current choke". Once parallel electric fields are introduced, the governing equations that couple Jupiter's ionosphere to the Io torus become nonlinear and, while the large-scale behavior is similar to that expected with no parallel electric field, there are substantial deviations on smaller scales. The solutions, bound by properties of the Io torus and Jupiter's ionosphere, indicate that the parallel potentials are on the order of 1 kV when constrained by peak energy fluxes of ~1 miliWatt per meter squared. The parallel potentials that we predict are significantly lower than earlier reports.

Ergun, R. E.; Ray, L.; Delamere, P. A.; Bagenal, F.; Dols, V.; Su, Y.

2008-12-01

333

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

NASA Astrophysics Data System (ADS)

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.

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

2013-04-01

334

Sequential observations of the local neutral wind field structure associated with E region plasma layers  

NASA Astrophysics Data System (ADS)

The first sequential rocket experiment to study intermediate layers in over 30 years was launched from Wallops Island, Virginia on the night of 29-30 June 2003. Using an onsite digisonde to determine the presence of sporadic E and conditions indicating the possible presence of an intermediate layer, four rockets were launched over a 4-hour period. Three of the rockets launched with at least an hour separation; they each contained chemical release experiments and plasma impedance probes. All four payloads encountered two plasma layers on both the ascent and descent of the flights. The lower-altitude layer, located at approximately 100 km, is clearly a sporadic E layer. The higher-altitude layer, located between 120 and 130 km, displays many characteristics of an intermediate layer, but it exhibits little downward motion over time. The neutral wind profiles resulting from the chemical tracer experiment are presented here along with the vertical drift velocities derived from the wind measurements. These are compared with the electron density profiles. They show a good agreement between the convergent regions in the velocity profiles and the location of the sporadic E layers. However, agreement between the center of the convergent vertical drift regions and the location of the higher-altitude layer is poor. The inclusion in the drift calculation of electric field data from the instrumented rocket significantly improves the overall agreement between the convergent vertical drift region center and the intermediate layer center. The convergent region is within 4 km of the intermediate layer. Further, the density depletions surrounding the layers coincide with the regions of divergent drift. The relatively large discrepancy observed between the shear in the vertical drift and the location of the intermediate layer implies that other factors such as horizontal motion structure variations may be important. Thus intermediate layer formation theory and subsequent evolution is still not fully understood.

Bishop, R. L.; Earle, G. D.; Larsen, M. F.; Swenson, C. M.; Carlson, C. G.; Roddy, P. A.; Fish, C.; Bullett, T. W.

2005-04-01

335

High-frequency expression for the field in the caustic region of a cylindrical reflector using Maslov's method  

NASA Astrophysics Data System (ADS)

High-frequency expressions in the caustic region are derived for the wave reflected by a circular and a parabolic cylindrical reflector using Maslov's method when a plane wave is incident obliquely. Maslov's method is a systematic procedure for predicting the field in the caustic region combining the simplicity of ray and generality of the transform method. Numerical computations are made for the field pattern around the caustic or cusp region and the variation of peak positions of the reflected field with respect to the incident angle.

Hongo, Kohei; Ji, Yu

1987-06-01

336

Field Studies of Broadband Aerosol Optical Extinction in the Ultraviolet Spectral Region  

NASA Astrophysics Data System (ADS)

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.

Washenfelder, R. A.; Attwood, A.; Brock, C. A.; Brown, S. S.

2013-12-01

337

THE INTERPLAY OF TURBULENCE AND MAGNETIC FIELDS IN STAR-FORMING REGIONS: SIMULATIONS AND OBSERVATIONS  

SciTech Connect

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.

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

338

Influence of surgical reduction of intraocular pressure on regions of the visual field with different levels of sensitivity  

Microsoft Academic Search

PURPOSE: To determine whether the ability to document improvement in visual fields after intraocular pressure (IOP) reduction can be enhanced by focusing on regions of the field with different levels of sensitivity.DESIGN: Cohort study.METHODS: This is a retrospective study.SETTING: Yale Eye Center.STUDY POPULATION: The visual fields (Octopus G2) of 30 eyes of 30 patients undergoing trabeculectomy.OBSERVATION PROCEDURE: Visual fields were

Sarwat Salim; Augusto Paranhos; Maurea Lima; M. Bruce Shields

2001-01-01

339

E-learning: Design Strategies for Promoting Sustainable Practices in Paddy Farming 1  

E-print Network

Malaysia aims to transform its current agricultural practices to modern, innovative and sustainable levels. There are many issues highlighted to improve the sustainability of agricultural practices. However, this is not an easy task because there are several problems that the society and farmers will face, especially in enhancing their lifestyles as well as their ecosystems. Introducing Information and Communication Technology (ICT) application like electronic learning (e-learning) is a novel way to educate and promote the young generation to appreciate sustainable agriculture. Therefore, the main objective of this paper is to discuss a design of a prototype of persuasive learning in virtual paddy as a tool to promote sustainable practices in paddy farming. Before designing a prototype, the current practices of sustainable agriculture should be collected. After that, a pilot test will be conducted with the help of an expert user.

Zakirah Othman; Amran Muhammad

340

Response of the solar atmosphere to magnetic field evolution in a coronal hole region  

NASA Astrophysics Data System (ADS)

Context: Coronal holes (CHs) are deemed to be the sources of the fast solar wind streams that lead to recurrent geomagnetic storms and have been intensively investigated, but not all the properties of them are well known. Aims: We study the response of the solar atmosphere to the magnetic field evolution in a CH region, such as magnetic flux emergence and cancellation for both network (NT) and intranetwork (IN) regions. Methods: We study an equatorial CH observed simultaneously by HINODE and STEREO on July 27, 2007. The HINODE/SP maps are adopted to derive the physical parameters of the photosphere and to investigate the magnetic field evolution and distribution. The G band and Ca ii H images with high tempo-spatial resolution from HINODE/BFI and the multi-wavelength data from STEREO/EUVI are utilized to study the corresponding atmospheric response of different overlying layers. Results: We explore an emerging dipole located at the CH boundary. Mini-scale arch filaments (AFs) accompanying the emerging dipole were observed with the Ca ii H line. During the separation of the dipolar footpoints, three AFs appeared and expanded in turn. The first AF divided into two segments in its late stage, while the second and third AFs erupted in their late stages. The lifetimes of these three AFs are 4, 6, 10 min, and the two intervals between the three divisions or eruptions are 18 and 12 min, respectively. We display an example of mixed-polarity flux emergence of IN fields within the CH and present the corresponding chromospheric response. With the increase of the integrated magnetic flux, the brightness of the Ca ii H images exhibits an increasing trend. We also study magnetic flux cancellations of NT fields located at the CH boundary and present the chromospheric and coronal response. We notice that the brighter regions seen in the 171 Å images are relevant to the interacting magnetic elements. By examining the magnetic NT and IN elements and the response of different atmospheric layers, we obtain close positive linear correlations between the NT magnetic flux densities and the brightness of both G band (correlation coefficient 0.85) and Ca ii H (correlation coefficient 0.58).

Yang, S. H.; Zhang, J.; Jin, C. L.; Li, L. P.; Duan, H. Y.

2009-07-01

341

NOTE: Dosimetric effects on the penumbra region of irregular multi-leaf collimated fields  

NASA Astrophysics Data System (ADS)

The dosimetric effect in the penumbra region for multi-leaf collimator (MLC) fields was studied using a Varian 21 EX linear accelerator. The beam profiles in the cross-line and in-line directions for MLC field configurations of varying lengths of protruded leaves, which are adjacent (on one or both sides) to the beam profile axes, were measured using a 6 MV photon beam. It was found that there is a decrease of dose in the 'edge' region of the protruded leaves' side in the cross-line profile, when the protruded leaves (upper and/or lower side) were moved out from 0.5 cm to 3 cm towards the central beam axis. When both the upper and lower portions of leaves were moved out forming a gap for the profile, the dose at the 'edge' region in the cross-line direction was decreased by about 20% and 6%, with the protruded length of leaves being 0.5 cm and 1 cm, respectively. The penumbra width of the cross-line profile increased with the protruded length of leaves when the gap width was 0.5 cm, and it was independent of the length when the width was increased larger than 1 cm. The Pinnacle treatment planning system could calculate the decrease of dose observed experimentally in the cross-line profile, but an underestimation of about 30% was found when using version 6.2b, which did not consider the leaf rounded end and tongue-and-groove effect. While the newly commissioned 7.4f, which considered the two aforementioned effects, made an improvement, it still underestimated the dose by 25% compared to the measurement. For the in-line profiles, both versions estimated the penumbra width well.

Chow, James C. L.; Wettlaufer, Brent; Jiang, Runqing

2006-02-01

342

Dosimetric effects on the penumbra region of irregular multi-leaf collimated fields.  

PubMed

The dosimetric effect in the penumbra region for multi-leaf collimator (MLC) fields was studied using a Varian 21 EX linear accelerator. The beam profiles in the cross-line and in-line directions for MLC field configurations of varying lengths of protruded leaves, which are adjacent (on one or both sides) to the beam profile axes, were measured using a 6 MV photon beam. It was found that there is a decrease of dose in the 'edge' region of the protruded leaves' side in the cross-line profile, when the protruded leaves (upper and/or lower side) were moved out from 0.5 cm to 3 cm towards the central beam axis. When both the upper and lower portions of leaves were moved out forming a gap for the profile, the dose at the 'edge' region in the cross-line direction was decreased by about 20% and 6%, with the protruded length of leaves being 0.5 cm and 1 cm, respectively. The penumbra width of the cross-line profile increased with the protruded length of leaves when the gap width was 0.5 cm, and it was independent of the length when the width was increased larger than 1 cm. The Pinnacle treatment planning system could calculate the decrease of dose observed experimentally in the cross-line profile, but an underestimation of about 30% was found when using version 6.2b, which did not consider the leaf rounded end and tongue-and-groove effect. While the newly commissioned 7.4f, which considered the two aforementioned effects, made an improvement, it still underestimated the dose by 25% compared to the measurement. For the in-line profiles, both versions estimated the penumbra width well. PMID:16424573

Chow, James C L; Wettlaufer, Brent; Jiang, Runqing

2006-02-01

343

Analysis of temperature field in the Banderas Bay Region between June 2009 to June 2012  

NASA Astrophysics Data System (ADS)

We present the spatial and temporary analysis of temperature fields monitored hourly and monthly throughout the year in the Banderas Bay region between the period June 2009 to June 2011. The study area is the atmospheric basin of Banderas Bay, between of Puerto Vallarta Jal. and Puerto Vallarta New Nay., in 20.66381 N,-105.20574W. The data used was obtained from the Atmospheric Monitoring Network in the Banderas Bay region, which comprises of at least 10 automatic weather stations distributed heterogeneously throughout the study area, which provide data on major meteorological variables at 10 minute intervals. It has been observed that the behavior throughout the year of major weather variables are determined by local processes (valley and breeze circulation) primarily and macro-scale phenomena (presence of the North Pacific anticyclone and trade winds). Greater thermal amplitude in the mountain regions of the River Ameca Valley, compared to coastal zones, with the latter influenced by the sea surface temperature. We registered small heat islands in urbane areas, which gives background information for future studies on pollution, health, prevention of natural disasters etc.

Carrillo-Gonzalez, F. M.; Cornejo-Lopez, V. M.; Morales-Hernández, J. C.

2012-12-01

344

Drying Strategies based on Diffusion model and Energy Analysis for Fluidized-Bed Drying of Paddy  

Microsoft Academic Search

The main objective of this work was to determine the effective moisture diffusivity of long grain rice kernel during fluidized-bed drying (FBD) with inlet air temperatures from 40-150°C by 10°C\\/step and to investigate the energy consumption of FBD system. Three initial moisture content of the local indica paddy was set at 25%, 28.8% and 32.5% dry-basis. By non-linear regression method,

Supawan Tirawanichakul; Somkiat Prachayawarakorn; Somchart Soponronnarit

345

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

Microsoft Academic Search

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

Isaacs

1975-01-01

346

Processes involved in formation and emission of methane in rice paddies  

Microsoft Academic Search

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

Helmut Schütz; Wolfgang Seiler; Ralf Conrad

1989-01-01

347

A Theoretical Study of the Runaway Electron Energy Spectrum Inside the High Field Regions of Thunderclouds  

NASA Astrophysics Data System (ADS)

Runaway electrons are produced in Earth's atmosphere when the particles rate of energy gain from an externally applied electric field exceeds the rate of energy loss it experiences from various interactions in air. In this presentation, we theoretically study the creation, propagation, and properties of runaway electrons during the avalanche process. Specifically, we use analytical and numerical models to study the runaway electron energy spectrum, and predict its shape and dependence on the electric field strength and air density. We also develop simple relationships between avalanche variables, including the electron avalanche length, radiation length, and minimum runaway electron kinetic energy. In order to guide the calculations presented here, a Monte Carlo simulation code is used, which was created by Dr. Joseph Dwyer at Florida Institute of Technology. The simulation includes all the relevant physics involved in propagating an energetic electron through air under the influence of an electric field. One motivation for this project is to express the results of the Monte Carlo simulation analytically, giving a better perspective on the nature of the avalanche region inside thunderclouds. Although the kinetic theory for runaway electrons has been studied previously (e.g., Roussel-Dupre et al. [1994], and Gurevich et al. [1992]), the equations derived are quite complex. Here, we present a simplified transport equation based on the classical continuity equation in phase space, and develop the proper form for describing the acceleration/deceleration and collisional processes that runaway electrons experience while propagating through air. Analytical results of the steady state distribution are possible with the help of several mathematical techniques, simplifications and assumptions. In particular, we find that when the bremsstrahlung energy losses are included, the high energy portion of the electron distribution is greatly affected. Finally, a numerical solution is presented which includes all the relevant collisions and sources, painting a complete picture of runaway electron physics in the avalanche region.

Cramer, E. S.; Dwyer, J. R.; Arabshahi, S.; Liu, N.; Vodopiyanov, I. B.; Rassoul, H.

2013-12-01

348

Acute toxicity of rice paddy herbicides simetryn, mefenacet, and thiobencarb to Silurana tropicalis tadpoles.  

PubMed

I examined the toxicity of rice paddy herbicides simetryn, mefenacet, and thiobencarb to amphibians by conducting acute toxicity tests with tadpoles of Silurana tropicalis, which has attracted as a new model species instead of Xenopus laevis. The tadpoles at stages 49 and 50 were exposed to the herbicides at several concentrations during 96 h, and median lethal concentration (LC50) values were calculated at 24-h intervals. The LC50 values of simetryn, mefenacet, and thiobencarb were 16.9-3.70 mg/L (79.3-17.4 microM), 3.06-2.70 mg/L (10.3-9.04 microM), and 1.77-0.752 mg/L (6.85-2.92 microM), respectively. The most toxic herbicide was thiobencarb followed by mefenacet and simetryn. As for thiobencarb, the sensitivity of S. tropicalis was similar to that of X. laevis reported previously. This suggests that S. tropicalis as well as X. laevis can act as a model species in acute toxicity tests. The LC50 values of the three herbicides were very close to or at most two orders of magnitude higher than the maximum concentrations likely to occur in paddy water. Therefore, the three herbicides can be harmful to amphibian larvae living in paddy water. PMID:20537391

Saka, Masahiro

2010-09-01

349

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

350

Niche differentiation of ammonia oxidizers and nitrite oxidizers in rice paddy soil.  

PubMed

The dynamics of populations and activities of ammonia-oxidizing and nitrite-oxidizing microorganisms were investigated in rice microcosms treated with two levels of nitrogen. Different soil compartments (surface, bulk, rhizospheric soil) and roots (young and old roots) were collected at three time points (the panicle initiation, heading and maturity periods) of the season. The population dynamics of bacterial (AOB) and archaeal (AOA) ammonia oxidizers was assayed by determining the abundance (using qPCR) and composition (using T-RFLP and cloning/sequencing) of their amoA genes (coding for a subunit of ammonia monooxygenase), that of nitrite oxidizers (NOB) by quantifying the nxrA gene (coding for a subunit of nitrite oxidase of Nitrobacter spp.) and the 16S rRNA gene of Nitrospira spp. The activity of the nitrifiers was determined by measuring the rates of potential ammonia oxidation and nitrite oxidation and by quantifying the copy numbers of amoA and nxrA transcripts. Potential nitrite oxidation activity was much higher than potential ammonia oxidation activity and was not directly affected by nitrogen amendment demonstrating the importance of ammonia oxidizers as pace makers for nitrite oxidizer populations. Marked differences in the distribution of bacterial and archaeal ammonia oxidizers, and of Nitrobacter-like and Nitrospira-like nitrite oxidizers were found in the different compartments of planted paddy soil indicating niche differentiation. In bulk soil, ammonia-oxidizing bacteria (Nitrosospira and Nitrosomonas) were at low abundance and displayed no activity, but in surface soil their activity and abundance was high. Nitrite oxidation in surface soil was dominated by Nitrospira spp. By contrast, ammonia-oxidizing Thaumarchaeota and Nitrobacter spp. seemed to dominate nitrification in rhizospheric soil and on rice roots. In contrast to soil compartment, the level of N fertilization and the time point of sampling had only little effect on the abundance, composition and activity of the nitrifying communities. The results of our study show that in rice fields population dynamics and activity of nitrifiers is mainly differentiated by the soil compartments rather than by nitrogen amendment or season. PMID:23437806

Ke, Xiubin; Angel, Roey; Lu, Yahai; Conrad, Ralf

2013-08-01

351

Stress Field in Brazil with Focal Mechanism: Regional and Local Patterns  

NASA Astrophysics Data System (ADS)

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.

Dias, F.; Assumpcao, M.

2013-05-01

352

On the Origin of Helicity in Solar ActiveRegion Magnetic Fields Alexei A. Pevtsov and Richard C. Canfield  

E-print Network

a simple model of the formation of the overall twist that is present in solar active­region magnetic fields, Canfield, Pevtsov & Acton 1995, Rust & Kumar 1996). Such structures can readily be modeled from observed

Pevtsov, Alexei A.

353

Self-reinforcing process of the reconnection electric field in the electron diffusion region and onset of collisionless magnetic reconnection  

NASA Astrophysics Data System (ADS)

The onset of collisionless magnetic reconnection is considered to be controlled by electron dynamics in the electron diffusion region, where the reconnection electric field is balanced mainly by the off-diagonal electron pressure tensor term. Two-dimensional particle-in-cell simulations are employed in this paper to investigate the self-reinforcing process of the reconnection electric field in the electron diffusion region, which is found to grow exponentially. A theoretical model is proposed to demonstrate such a process in the electron diffusion region. In addition the reconnection electric field in the pileup region, which is balanced mainly by the electromotive force term, is also found to grow exponentially and its growth rate is twice that in the electron diffusion region.

Lu, Quanming; Lu, San; Huang, Can; Wu, Mingyu; Wang, Shui

2013-08-01

354

Environmental conditions and characteristics of ice supersaturated regions from global field campaigns  

NASA Astrophysics Data System (ADS)

Cirrus clouds play important roles in the Earth's climate and weather and their influences extend from the global scale (~30% coverage of the Earth's surface) to the microscale (e.g., interactions with aerosols). Cirrus cloud formation occurs in ice supersaturated regions (ISSRs), where the relative humidity with respect to ice (RHi) is greater than 100%. Recent observations show that cirrus clouds have a very small (~1 km) horizontal median length, yet the origin of such small scale structure is not known. The magnitude of cirrus clouds' radiative forcing is greatly influenced by cloud properties such as the coverage, thickness, ice crystal number concentration and size distribution. The microscale structure of ISSRs is critical for the microphysical processes in cirrus clouds, since the local conditions of ISSRs (e.g. temperature and RHi) influence the properties of ice crystals and their interactions with aerosols. However, the spatial structure of ISSRs and its controlling factors are still unknown below the mesoscale. To this end, we analyzed the spatial structure and environments of ISSRs — the prerequisite stage of cirrus cloud formation — based on in situ, high resolution (1 Hz, ~230 m) aircraft observations from 87°N to 67°S from five different field campaigns that span the tropics, mid-latitudes, and polar regions: NSF START08, HIPPO 1-5, PREDICT, TORERO, and DC3 field campaigns. By analyzing a large number (>7000) of individual case studies of ice supersaturated regions, we reveal the patchy nature of ISSRs with their median lengths being very small (~ 1 km) regardless of the location. The patchiness of ISSRs is found to largely correlate with water vapor (H2O) spatial heterogeneities, while the correlations with temperature (T) and vertical velocity (w) heterogeneities are much less dominant. The large influence of H2O heterogeneities on ISSR patchiness not only happens in supersaturated conditions but also extends to subsaturated conditions. The dominance of H2O over the spatial relative humidity field holds from the microscale (~230 m) to the mesoscale (~120 km) over various ranges of temperature (205-302K), water vapor (2-39,000 ppmv) and pressure (133-1,014 hPa). These findings suggest that H2O heterogeneities play crucial roles in determining the RHi spatial heterogeneities even before ISSRs are formed. Neglecting H2O heterogeneities in simplified ISSR evolution schemes results in different ISSR structures than those observed, which in turn changes the predicted properties of cirrus clouds.

Zondlo, M. A.; Diao, M.; Zhang, Q.; DiGangi, J.; O'Brien, A.

2012-12-01

355

The Helioseismic and Magnetic Imager (HMI) Vector Magnetic Field Pipeline: SHARPs -- Space-weather HMI Active Region Patches  

E-print Network

A new data product from the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO) called Space-weather HMI Active Region Patches (SHARPs) is now available. SDO/HMI is the first space-based instrument to map the full-disk photospheric vector magnetic field with high cadence and continuity. The SHARP data series provide maps in patches that encompass automatically tracked magnetic concentrations for their entire lifetime; map quantities include the photospheric vector magnetic field and its uncertainty, along with Doppler velocity, continuum intensity, and line-of-sight magnetic field. Furthermore, keywords in the SHARP data series provide several parameters that concisely characterize the magnetic-field distribution and its deviation from a potential-field configuration. These indices may be useful for active-region event forecasting and for identifying regions of interest. The indices are calculated per patch and are available on a twelve-minute cadence. Quick-look data are avail...

Bobra, Monica G; Hoeksema, J Todd; Turmon, Michael J; Liu, Yang; Hayashi, Keiji; Barnes, Graham; Leka, K D

2014-01-01

356

Screening of Cyanobacteria (Blue-Green algae) from Rice Paddy Soil for Antifungal Activity against Plant Pathogenic Fungi  

PubMed Central

Soil cyanobacteria isolated from the rice paddy fields of 10 different locations across Korea were evaluated by agar plate diffusion test for antifungal activity. Aqueous, petroleum ether, and methanol extracts from one hundred and forty two cyanobacterial strains belonging to the 14 genera were examined for antifungal properties against seven phytopathogenic fungi causing diseases in hot pepper (Capsicum annuum L). Of total cyanobacteria, nine cyanobacteria (6.34%) exhibited antifungal effects. The nine cyanobacteria selected with positive antifungal activities were two species of Oscillatoria, two of Anabaena, three of Nostoc, one of Nodularia, and one of Calothrix. Alternaria alternata and Botrytis cinerea were inhibited by nine and eight species of cyanobacteria, respectively. Rhizopus stolonifer was suppressed by only methanol extract of Nostoc commune FK-103. In particular, Nostoc commune FK-103 and Oscillatoria tenuis FK-109 showed strong antifungal activities against Phytophthora capsici. Their antifungal activity at the late exponential growth phase is related to the growth temperature and not associated with the growth parameters such as cell biomass and chlorophyll-? concentration. The high inhibition levels of antibiotics were 22.5 and 31.8 mm for N. commune FK-103 and O. tenuis FK-109, respectively. The optimal temperature for antibiotic productivity was 35?. PMID:24039487

2006-01-01

357

Screening of Cyanobacteria (Blue-Green algae) from Rice Paddy Soil for Antifungal Activity against Plant Pathogenic Fungi.  

PubMed

Soil cyanobacteria isolated from the rice paddy fields of 10 different locations across Korea were evaluated by agar plate diffusion test for antifungal activity. Aqueous, petroleum ether, and methanol extracts from one hundred and forty two cyanobacterial strains belonging to the 14 genera were examined for antifungal properties against seven phytopathogenic fungi causing diseases in hot pepper (Capsicum annuum L). Of total cyanobacteria, nine cyanobacteria (6.34%) exhibited antifungal effects. The nine cyanobacteria selected with positive antifungal activities were two species of Oscillatoria, two of Anabaena, three of Nostoc, one of Nodularia, and one of Calothrix. Alternaria alternata and Botrytis cinerea were inhibited by nine and eight species of cyanobacteria, respectively. Rhizopus stolonifer was suppressed by only methanol extract of Nostoc commune FK-103. In particular, Nostoc commune FK-103 and Oscillatoria tenuis FK-109 showed strong antifungal activities against Phytophthora capsici. Their antifungal activity at the late exponential growth phase is related to the growth temperature and not associated with the growth parameters such as cell biomass and chlorophyll-? concentration. The high inhibition levels of antibiotics were 22.5 and 31.8 mm for N. commune FK-103 and O. tenuis FK-109, respectively. The optimal temperature for antibiotic productivity was 35?. PMID:24039487

Kim, Jeong-Dong

2006-09-01

358

Learned timing of motor behavior in the smooth eye movement region of the frontal eye fields  

PubMed Central

Summary Proper timing is a critical aspect of motor learning. We report a relationship between a representation of time and an expression of learned timing in neurons in the smooth eye movement region of the frontal eye fields (FEFSEM). During pre-learning pursuit of target motion at a constant velocity, each FEFSEM neuron is most active at a distinct time relative to the onset of pursuit tracking. In response to an instructive change in target direction, a neuron expresses the most learning when the instruction occurs near the time of its maximal participation in pre-learning pursuit. Different neurons are most active, and undergo the most learning, at distinct times during pursuit. We suggest that the representation of time in the FEFSEM drives learning that is temporally linked to an instructive change in target motion, and that this may be a general function of motor areas of the cortex. PMID:21220106

Li, Jennifer X.; Lisberger, Stephen G.

2011-01-01

359

Cortical afferents to the smooth-pursuit region of the macaque monkey’s frontal eye field  

Microsoft Academic Search

In primates, the frontal eye field (FEF) contains separate representations of saccadic and smooth-pursuit eye movements. The smooth-pursuit region (FEFsem) in macaque monkeys lies principally in the fundus and deep posterior wall of the arcuate sulcus, between the FEF saccade region (FEFsac) in the anterior wall and somatomotor areas on the posterior wall and convexity. In this study, cortical afferents

Gregory B. Stanton; Harriet R. Friedman; Elisa C. Dias; Charles J. Bruce

2005-01-01

360

Transforming Your Regional Economy through Uncertainty and Surprise: Learning from Complexity Science, Network Theory and the Field  

NASA Astrophysics Data System (ADS)

The field of regional development blossomed in the last decade, as researchers and practitioners increasingly asserted that the region was the most effective geographic unit for supporting the excellence and innovation of entrepreneurs. See, for example, the many studies by the European Union and the work by Michael Porter.

Holley, June

361

What are regional ocean climatologies? Ocean climatology is a compendium of time-averaged fields of essential oceanographic  

E-print Network

What are regional ocean climatologies? Ocean climatology is a compendium of time-averaged fields of the ocean climatology from data was well ahead of capabilities of ocean numerical models and other practical REGIONAL CLIMATOLOGY OF GREENLAND- ICELAND-NORWEGIAN SEAS 2013 www.nodc.noaa.gov recently upscaled to 1/4°x

362

GPS velocity field across the Ossetia region of the Great Caucasus  

NASA Astrophysics Data System (ADS)

The Ossetia part of the Great Caucasus is located within the Trans-Caucasian uplift. According to modern understanding this large structure is the northern ending of the planetary-scale structure - the East-African-Trans-Caucasus rift zone. This region, being one of the most tectonically active regions of the Caucasus, was not covered by satellite geodetic measurements made in the Caucasus and surrounding areas since the early 1990s. This work presents results of the development of the network of survey-mode sites and GPS velocity field of this region, which is also part of the international project under leadership of R. Reilinger (MIT) for studying geodynamics of the eastern Mediterranean and Caucasus. The network established during the campaigns of 2010-2013 crosses from north to south the main tectonic structures of the Ossetia part of the Great Caucasus: the northern and southern slopes of the Great Caucasus ridge, the Tibsky thrust fault, the Northern Caucasian step, the Orkhevsky thrust fault, the Georgian block. The main profile of the network is oriented from north-east to south-west. The other two profiles are transverse to the main one and are oriented from west to east. The first of them is located along the southern and northern borders of the Orkhevskii thrust fault, covering the area of the Racha 1991 earthquake, with release to the Gagra-Dzhava zone. The second of them passes along the northern slope of Great Caucasus Ridge. The GPS data included 25 sites were processed using the GAMIT/GLOBK software. Velocity uncertainties for many sites are less then 1 mm/year. GPS velocities are presented in two reference systems: ITRF08 and fixed Eurasia. In terrestrial system of coordinates ITRF08 the horizontal motions of Ossetia region are characterized by the steady north-east trend with velocities of 25-30 mm/year, that as a whole coincides with velocities estimation of modern movements of the North Caucasus. With respect to Eurasia one can note the prevalence of submeridional oriented motions, what is the result of pressure of the Arabian lithospheric plate on Eurasia. Nevertheless, there is noticeable spreading of the GPS-derived velocities, in value and direction, which reflects local features of tectonic structure of the region. The resulting velocities provide the first relatively complete and detailed pattern of modern horizontal displacements of some elements within the Caucasian mountain structure. This work is supported by the Russian Foundation for Basic Research under Grant No 12-05-00711.

Milyukov, Vadim; Mironov, Alexey; Steblov, Grigory; Drobishev, Valery; Hubaev, Hariton; Kusraev, Anatoliy; Shevchenko, Vladimir

2014-05-01

363

Structure of magnetic fields in NOAA active regions 0486 and 0501 and in the associated interplanetary ejecta  

E-print Network

magnetic fields associ- ated with the storms in October ­ November 2003. We used space and ground basedStructure of magnetic fields in NOAA active regions 0486 and 0501 and in the associated consecutive days, caused intense ge- omagnetic storms. In this paper we analyze solar and interplanetary

Yurchyshyn, Vasyl

364

The Southern African Regional Science Initiative (SAFARI 2000): Overview of the Dry Season Field Campaign  

NASA Technical Reports Server (NTRS)

The Southern African Regional Science Initiative (SAFARI 2000) is an international project investigating the earth atmosphere -human system in southern Africa. The programme was conducted over a two year period from March 1999 to March 2001. The dry season field campaign (August-September 2000) was the most intensive activity involved over 200 scientist from eighteen countries. The main objectives were to characterize and quantify biogenic, pyrogenic and anthropogenic aerosol and trace gas emissions and their transport and transformations in the atmosphere and to validate NASA's Earth Observing System's Satellite Terra within a scientific context. Five aircraft-- two South African Weather Service Aeorcommanders, the University of Washington's CV-880, the U.K. Meteorological Office's C-130, and NASA's ER-2 --with different altitude capabilities, participated in the campaign. Additional airborne sampling of southern African air masses, that had moved downwind of the subcontinent, was conducted by the CSIRO over Australia. Multiple Observations were made in various geographical sections under different synoptic conditions. Airborne missions were designed to optimize the value of synchronous over-flights of the Terra Satellite platform, above regional ground validation and science targets. Numerous smaller scale ground validation activities took place throughout the subcontinent during the campaign period.

Swap, R. J.; Annegarn, H. J.; Suttles, J. T.; Haywood, J.; Helmlinger, M. C.; Hely, C.; Hobbs, P. V.; Holben, B. N.; Ji, J.; King, M. D.

2002-01-01

365

PROBING THE SHALLOW CONVECTION ZONE: RISING MOTION OF SUBSURFACE MAGNETIC FIELDS IN THE SOLAR ACTIVE REGION  

SciTech Connect

In this Letter, we present a seismological detection of a rising motion of magnetic flux in the shallow convection zone of the Sun, and show estimates of the emerging speed and its decelerating nature. In order to evaluate the speed of subsurface flux that creates an active region, we apply six Fourier filters to the Doppler data of NOAA AR 10488, observed with the Solar and Heliospheric Observatory/Michelson Doppler Imager, to detect the reduction of acoustic power at six different depths from -15 to -2 Mm. All the filtered acoustic powers show reductions, up to 2 hr before the magnetic flux first appears at the visible surface. The start times of these reductions show a rising trend with a gradual deceleration. The obtained velocity is first several km s{sup -1} in a depth range of 15-10 Mm, then {approx}1.5 km s{sup -1} at 10-5 Mm, and finally {approx}0.5 km s{sup -1} at 5-2 Mm. If we assume that the power reduction is actually caused by the magnetic field, the velocity of the order of 1 km s{sup -1} is well in accordance with previous observations and numerical studies. Moreover, the gradual deceleration strongly supports the theoretical model that the emerging flux slows down in the uppermost convection zone before it expands into the atmosphere to build an active region.

Toriumi, Shin; Yokoyama, Takaaki [Department of Earth and Planetary Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Ilonidis, Stathis [W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305-4085 (United States); Sekii, Takashi, E-mail: toriumi@eps.s.u-tokyo.ac.jp [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)

2013-06-10

366

Integral Field Spectroscopy of the Extended Emission-Line Region of 4C 37.43  

E-print Network

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) 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.

Hai Fu; Alan Stockton

2007-05-30

367

An improved model of the lightning electromagnetic field interaction with the D-region ionosphere  

NASA Astrophysics Data System (ADS)

We present an improved time-domain model of the lightning electromagnetic pulse (EMP) interaction with the lower ionosphere. This improved model inherently accounts for the Earth's curvature, includes an arbitrary number of ion species, and uses a convolutional Perfectly Matched Layer (PML) boundary. We apply an improved model of electron heating due to the lightning EMP and electrostatic fields, and we include ionization, attachment, and detachment. In addition to modeling lightning, this model can be used for long-distance VLF wave propagation in the Earth-ionosphere waveguide, heating of the lower ionosphere by VLF transmitters, and heating in the F-region ionosphere by lightning. In this paper we present three initial results of this model. First, we compare results of ionospheric heating and electron density disturbances with and without electron detachment taken into account. We find that detachment is important only for the QE effects on time scales longer than 1 ms. Second, we find a simple explanation for the recently-reported “elve doublets”, which we find are an effect of the rise and fall times of the lightning waveform. In particular, we find that all elves are doublets, and the rise and fall times of the current pulse control the brightness and separation in time of the two successive halves of the elve. Third, we find a similar simple explanation for “ring” sprites, whole columns appear in a circle symmetric around the discharge axis. We find that ring sprites can be initiated for particular current waveforms, where the QE and EMP fields in the mesosphere produce a maximum reduced field away from the discharge axis.

Marshall, R. A.

2012-03-01

368

Experimental studies on remanence acquisition processes and regional geomagnetic field variability from archeointensity studies  

NASA Astrophysics Data System (ADS)

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.

Mitra, Ritayan

369

Automatic Paddy Rice Mapping Interface Using Arcengine and LANDSAT8 Imagery (case Study in North Part of Iran)  

NASA Astrophysics Data System (ADS)

Recognition of paddy rice boundaries is an essential step for many agricultural processes such as yield estimation, cadastre and water management. In this study, an automatic rice paddy mapping is proposed. The algorithm is based on two temporal images: an initial period of flooding and after harvesting. The proposed method has several steps include: finding flooded pixels and masking unwanted pixels which contain water bodies, clouds, forests, and swamps. In order to achieve final paddy map, indexes such as Normalized Difference Vegetation Index (NDVI) and Land Surface Water Index (LSWI) are used. Validation is performed by rice paddy boundaries, which were drawn by an expert operator in Google maps. Due to this appraisal good agreement (close to 90%) is reached. The algorithm is applied to Gilan province located in the north part of Iran using Landsat 8 date 2013. Automatic Interface is designed based on proposed algorithm using Arc Engine and visual studio. In the Interface, inputs are Landsat bands of two time periods including: red (0.66 ?m), blue (0.48 ?m), NIR (0.87 ?m), and SWIR (2.20 ?m), which should be defined by user. The whole process will run automatically and the final result will provide paddy map of desire year.

Bahramvash Shams, Sh.

2014-10-01

370

First observational evidence for opposite zonal electric fields in equatorial E and F region altitudes during a geomagnetic storm period  

NASA Astrophysics Data System (ADS)

The strong westward electrojet and simultaneous upward drift of the equatorial ionospheric peak observed over South-East Asia and Indian equatorial regions during the prolonged Dst minimum phase of an intense geomagnetic storm during 14-15 December 2006 are investigated for the altitudinal variation of zonal electric field polarity using ground based and space-borne observations. The results show first observational evidence for simultaneous existence of daytime westward and eastward zonal electric fields at equatorial E and F region altitudes, respectively, in a wide longitude sector. While the westward electric fields at E region altitudes cause westward electrojet, at the same time, the eastward zonal electric fields at F region altitudes cause the upward drift of the equatorial ionospheric peak and reinforcement of the equatorial ionization anomaly (EIA) even in the topside ionosphere (˜660 km). The reversal of the electric fields is found to occur at ˜280 km height. A clear bifurcation of F region plasma at ˜280 km is evident in the iso-electron density contours due to these oppositely polarized zonal electric fields, which manifests as an unusually deep cusp between F1 and F2 layers on equatorial ionograms.

Tulasi Ram, S.; Balan, N.; Veenadhari, B.; Gurubaran, S.; Ravindran, S.; Tsugawa, T.; Liu, H.; Niranjan, K.; Nagatsuma, T.

2012-09-01

371

Systematic optimization of exterior measurement locations for the determination of interior magnetic field vector components in inaccessible regions  

NASA Astrophysics Data System (ADS)

An experiment may face the challenge of real-time determination of the magnetic field vector components present within some interior region of the experimental apparatus over which it is impossible to directly measure the field components during the operation of the experiment. As a solution to this problem, we propose a general concept which provides for a unique determination of the field components within such an interior region solely from exterior measurements at fixed discrete locations. The method is general and does not require the field to possess any type of symmetry. We describe our systematic approach for optimizing the locations of these exterior measurements which maximizes their sensitivity to successive terms in a multipole expansion of the field.

Nouri, N.; Plaster, B.

2014-12-01

372

Regional-Scale Salt Tectonics Modelling: Bench-Scale Validation and Extension to Field-Scale  

NASA Astrophysics Data System (ADS)

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.

Crook, A. J. L.; Yu, J. G.; Thornton, D. A.

2010-05-01

373

VHF Radar Observations of Nighttime F-Region Field-Aligned Irregularities Over Kototabang, Indonesia  

NASA Astrophysics Data System (ADS)

We report continuous observations of the nighttime F-region field-aligned irregularities (FAIs) over Indonesia. A VHF radar with operating frequency of 30.8 MHz and peak power of 20 kW has been operated at Kototabang (0.20°S, 100.32°E; dip latitude 10.4°S), Indonesia since February 2006. Five beams were allocated between ±54° in azimuth around geographic south (126°-234°). From the continuous observation from February 2006 to November 2007, we found that FAIs appeared frequently at pre- midnight between March and May and at post-midnight between May and August. The pre-midnight FAIs coincided well with GPS scintillation observed at the same site. Seasonal and local time variations of the pre-midnight FAI occurrence are consistent with those of equatorial plasma bubbles reported in previous studies (e.g., Maruyama and Matuura, 1984). These results indicate that the pre-midnight FAIs could be associated with the equatorial plasma bubbles. On the other hand, seasonal and local time variations of the post-midnight FAIs were inconsistent with those of the plasma bubbles. The features of the post-midnight FAIs can be summarized as follows: (1) The post-midnight FAIs are not accompanied by GPS scintillations. (2) Most of the post-midnight FAI regions do not show propagation, but some of them propagate westward. (3) Echo intensity of the post-midnight FAIs was weaker than that of the pre-midnight FAIs. These features are similar to those of the FAI echoes that have been observed at mid- latitude (e.g., Fukao et al., 1991). At Kototabang, Fukao et al. (2004) have firstly observed FAIs that resemble those at mid-latitude. The present paper reports statistical characteristics of the mid-latitude-type FAIs observed at Kototabang.

Otsuka, Y.; Shiokawa, K.; Ogawa, T.; Drs, E.

2009-05-01

374

VHF radar observations of nighttime F-region field-aligned irregularities over Kototabang, Indonesia  

NASA Astrophysics Data System (ADS)

We report, for the first time, continuous observations of the nighttime F-region field-aligned irregularities (FAIs) over Indonesia. A VHF radar with operating frequency of 30.8 MHz and peak power of 20 kW has been operated at Kototabang (0.20°S, 100.32°E; dip latitude 10.4°S), Indonesia since February 2006. Five beams were allocated between ±54° in azimuth around geographic south (126°-234°). From the continuous observation from February 2006 to November 2007, we found that FAIs appeared frequently at pre-midnight between March and May and at post-midnight between May and August. The pre-midnight FAIs coincided well with GPS scintillation observed at the same site. Seasonal and local time variations of the pre-midnight FAI occurrence are consistent with those of equatorial plasma bubbles reported in previous studies (e.g., Maruyama and Matuura, 1984). These results indicate that the pre-midnight FAIs could be associated with the equatorial plasma bubbles. On the other hand, seasonal and local time variations of the post-midnight FAIs were inconsistent with those of the plasma bubbles. The features of the post-midnight FAIs can be summarized as follows: (1) The post-midnight FAIs are not accompanied by GPS scintillations. (2) Most of the post-midnight FAI regions do not show propagation, but some of them propagate westward. (3) Echo intensity of the post-midnight FAIs was weaker than that of the pre-midnight FAIs. These features are similar to those of the FAI echoes that have been observed at mid-latitude (e.g., Fukao et al., 1991). At Kototabang, Fukao et al. (2004) have firstly observed FAIs that resemble those at mid-latitude. The present paper reports statistical characteristics of the mid-latitude-type FAIs observed at Kototabang.

Otsuka, Y.; Ogawa, T.; Effendy

2009-04-01

375

Dense Regional Velocity Field Realization Based on the Integration of the National Active Gnss Networks  

NASA Astrophysics Data System (ADS)

The European contribution to the IAG Working Group on Dense Velocity Fields should rely on the integration of the dense national permanent GNSS networks. In Europe the situation is more complex than in other regions because numerous countries operate independent networks. Fortunately the EUREF Permanent Network (EPN) and its products can be used as backbone infrastructureand the separate national GNSS data processing practically rely on the strategy defined for the EPN analysis. In order to avoid any inconsistencies the combination will be done on the weekly SINEX level. The national weekly SINEX submissions are combined with the actual weekly EPN SINEX solution, than a multiyear cumulative solution is created, which already includes all input. Before the creation of the integrated cumulative solution several quality and homogeneity tests (strategies, models, naming, data availability, site stability, weighting) are being performed. The integration is done with the CATREF software using the Minimum Constraint approach. The preparatory work is already in progress, the data from several countries is already investigated and promising test results have been created. The ongoing EPN densification action is one of the leading activity of EUREF for the next few years. The derived position and velocity product will be an essential material for geokinematic studies and also for the better definition and realization of ETRS89 reference frame. In order to cover the greatest part of the continent all European countries are invited to submit their weekly GNSS SINEX solutions. In this paper a status report is presented, where the issues to be solved are emphasized, but also the latest velocity field solution is shown.

Kenyeres, A.

2013-12-01

376

The morphology of flare phenomena, magnetic fields, and electric currents in active regions. III - NOAA active region 6233 (1990 August)  

NASA Technical Reports Server (NTRS)

We investigate the spatial relationship between vertical electric currents and flare phenomena in NOAA Active Region 6233, which was observed 1990, August 28-31 at Mees Solar Observatory. The two flares studied are the 1N/M1.8 flare on August 28, 22:30 UT and the 1N/M1.6 flare on August 29, 20:35 UT. Using Stokes polarimetry we make magnetograms of the region and compute the vertical current density. Using H-alpha imaging spectroscopy we identify sites of intense nonthermal electron precipitation or of high coronal pressure. The precipitation in these flares is barely strong enough to be detectable. We find that both precipitation and high pressure tend to occur near vertical currents, but that neither phenomenon is cospatial with current maxima. In contrast with the conclusion of other authors, we argue that these observations do not support a current-interruption model for flares, unless the relevant currents are primarily horizontal. The magnetic morphology and temporal evolution of these flares suggest that an erupting filament model may be relevant, but this model does not explicitly predict the relationship between precipitation, high pressure, and vertical currents.

De La Beaujardiere, J.-F.; Canfield, Richard C.; Leka, K. D.

1993-01-01

377

Measles vaccine effectiveness under field conditions. A case control study in Tabora region, Tanzania.  

PubMed

A case-control study was carried out among 225 cases and 450 controls aged below 60 months between July and September 1991, with the aim of determining measles vaccine effectiveness (VE) under field conditions in Tabora region, Tanzania. VE was found to be 84% (95% confidence interval (CI) 61-93%) among children vaccinated between 9 and 59 months, and 73% (95% CI: 11-92%) in children vaccinated at the age of 6 to 8 months. Loosening the diagnostic criteria and/or establishing vaccination status from vaccine registers rather than Road to Health cards, lowered vaccine effectiveness results. The protective effectivity among children vaccinated from 6 months and above and those vaccinated from 9 months and above, was 79% (95% CI: 55-90%) and 84% (95% CI: 61-93%) respectively. A relatively higher VE was found in children vaccinated at rural health centres and hospitals, 89% (95% CI: 56-97%) compared with dispensaries, 70% (95% CI: 22-88%). It is high time for the current age at vaccination to be reviewed in the country. It should be noted, however, that the present observations and conclusions are based on a study of limited numbers of persons. Repetition at a large scale would seem indicated. PMID:8553440

Simba, D O; Msamanga, G I

1995-01-01

378

Age of granodiorite porphyry and beresite from the Darasun gold field, eastern Transbaikal region, Russia  

NASA Astrophysics Data System (ADS)

The Darasun ore field situated in the southern West Stanovoi Terrane near the Mongolia-Okhotsk Suture comprises the Darasun (>100 t Au), Talatui (˜38.2 t Au), and Teremki (3 t Au) lode gold deposits. In the opinion of many researchers, the Darasun deposit is spatially and paragenetically linked to granodiorite porphyry of the Amudzhikan Complex and related metasomatic rocks (beresites). Whole-rock samples of granodiorite porphyry, monomineralic fractions of plagioclase, K-feldspar, and biotite, as well as sericite from beresite (26 samples in total), were analyzed by the Rb-Sr method. Eight biotite and sericite samples were analyzed by the K-Ar method. The Rb-Sr mineral isochrons obtained for individual granodiorite porphyry samples yielded initial 87Sr/86Sr ratios varying from 0.70560 to 0.70591. The consistent results of both methods allowed us to accept the ages of granodiorite porphyry and beresite as 160.5 ± 0.4 and 159.6 ± 1.5 Ma, respectively. The age of granodiorite porphyry of the Amudzhikan Complex of 160.5 ± 0.4 Ma corresponds to the boundary between the Early and Middle Jurassic and marks the completion of collision between the East Siberian and Mongolia-China continents and related orogeny. Since that time, the eastern Transbaikal region has been involved in the postorogenic (within-plate) stage of evolution, characterized by the formation of large gold, uranium, and other ore deposits.

Chernyshev, I. V.; Prokof'ev, V. Yu.; Bortnikov, N. S.; Chugaev, A. V.; Goltsman, Yu. V.; Lebedev, V. A.; Larionova, Yu. O.; Zorina, L. D.

2014-02-01

379

Determination of Topology Skeleton of Magnetic Fields in a Solar Active Region  

E-print Network

The knowledge of magnetic topology is the key to understand magnetic energy release in astrophysics. Based on observed vector magnetograms, we have determined threedimensional (3D) topology skeleton of the magnetic fields in active region NOAA 10720. The skeleton consists of six 3D magnetic nulls and a network of corresponding spines, fans, and null-null lines. For the first time, we have identified a spiral magnetic null in Sun's corona. The magnetic lines of force twisted around the spine of the null, forming a 'magnetic wreath' with excess of free magnetic energy and resembling observed brightening structures at extraultraviolet (EUV) wavebands. We found clear evidence of topology eruptions which are referred to as the catastrophic changes of topology skeleton associated with a coronal mass ejection (CME) and an explosive X-ray flare. These results shed new lights in exploring the structural complexity and its role in explosive magnetic activity. In solar astrophysics and space science, the concept of flux rope has been widely used in modelling explosive magnetic activity, although their observational identity is obscure or, at least, lacking of necessary details. The current work suggests that the magnetic wreath associated with the 3D spiral null is likely an important class of the physical entity of flux ropes.

Hui Zhao; Jing-Xiu Wang; Jun Zhang; Chi-Jie Xiao; Hai-Min Wang

2007-12-20

380

Cadmium solubility in paddy soils: effects of soil oxidation, metal sulfides and competitive ions.  

PubMed

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) and zinc (Zn) for human nutrition. To find ways of limiting this potential risk, we investigated factors influencing Cd solubility relative to Fe and Zn during pre-harvest drainage of paddy soils, in which soil oxidation is accompanied by the grain-filling stage of rice growth. This was simulated in temperature-controlled "reaction cell" experiments by first excluding oxygen to incubate soil suspensions anaerobically, then inducing aerobic conditions. In treatments without sulfur addition, the ratios of Cd:Fe and Cd:Zn in solution increased during the aerobic phase while Cd concentrations were unaffected and the Fe and Zn concentrations decreased. However, in treatments with added sulfur (as sulfate), up to 34 % of sulfur (S) was precipitated as sulfide minerals during the anaerobic phase and the Cd:Fe and Cd:Zn ratios in solution during the aerobic phase were lower than for treatments without S addition. When S was added, Cd solubility decreased whereas Fe and Zn were unaffected. When soil was spiked with Zn the Cd:Zn ratio was lower in solution during the aerobic phase, due to higher Zn concentrations. Decreased Cd:Fe and Cd:Zn ratios during the grain filling stage could potentially limit Cd enrichment in paddy rice grain due to competitive ion effects for root uptake. PMID:21277005

de Livera, Jennifer; McLaughlin, Mike J; Hettiarachchi, Ganga M; Kirby, Jason K; Beak, Douglas G

2011-03-15