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1

A study on pesticide runoff from paddy fields to a river in rural region--1: field survey of pesticide runoff in the Kozakura River, Japan.  

PubMed

Runoff characteristics of nine kinds of herbicides from paddy fields were surveyed in the Kozakura River, that is one of the tributaries flowing into the Lake of Kasumigaura, over a period of 23 April to 30 June (before and after rice transplantation) of year. The flow rates of river water and the concentrations of herbicides in the river water were measured every day in May and every 2 days in April and June at six survey sites along the river. The runoff characteristics of herbicides were elucidated by taking account of the rainfall data, the detailed application data (application date and quantities of herbicides applied to each paddy field in a region), and their physico-chemical properties. The runoff rates (the runoff/application amounts ratio) were calculated for each herbicide, resulting in the range of 8.2-22.4%. The runoff rates were correlated fairly well with octanol-water partition coefficient, logP(ow), rather than with water solubility of herbicides. PMID:15261539

Nakano, Yoshio; Miyazaki, Akane; Yoshida, Tomohiko; Ono, Kazusa; Inoue, Takanobu

2004-07-01

2

Biogenic volatile organic compound emission potential of forests and paddy fields in the Kinki region of Japan.  

PubMed

The standard biogenic volatile organic compound (BVOC) emissions from 10 Japanese plant species (Quercus serrata, Quercus crispula, Fagus crenata, Quercus acutissima Carruthers, Quercus glauca, Quercus myrsinaefolia, Cryptomeria japonica, Chamaecyparis obtusa, Pinus densiflora, and rice [Oryza sativa]) were measured. These species were selected due to their abundance in the estimated domain (47,000 km(2)) of the Kinki region. BVOC emission experiments were conducted in a growth chamber where temperature and light intensity can be controlled. Temperature was set at the average summer temperature in Osaka and at 5 degrees C above average. Light intensity was set at 1000, 335, and 0 micromol m(-2)s(-1) during day time. The amount of BVOC emission was high around noon due to the rise of ambient temperature. It was also found that the total emission rates and compositions of BVOC varied significantly among the plant species. Q. serrata, Q. crispula, F. crenata, Q. acutissima Carruthers, Q. glauca, and Q. myrsinaefolia emitted isoprene and showed emission dependence on light intensity and temperature. C. japonica, P. densiflora, C. obtusa, and O. sativa emitted monoterpenes and also showed emission dependence on temperature; however, only C. japonica and P. densiflora showed emission dependence on light intensity. Using BVOC emissions data from 10 plant species and forest data, BVOC emission potential maps were made. The emission of isoprene and monoterpenes from the Kinki region were estimated to be 596 and 54 ton h(-1), respectively. Seasonal and diurnal variations of BVOC emissions potential were also estimated. Of note, though the amount of monoterpenes from O. sativa is small, it contributes approximately 5% to the total monoterpene emissions due to the huge land area covered by paddy fields. PMID:18023428

Bao, Hai; Kondo, Akira; Kaga, Akikazu; Tada, Masaharu; Sakaguti, Katsutoshi; Inoue, Yoshio; Shimoda, Yoshiyuki; Narumi, Daisuke; Machimura, Takashi

2008-02-01

3

The Study of Runoff Loads from Lotus Paddy Fields  

NASA Astrophysics Data System (ADS)

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

Kuroda, Hisao; Kato, Tasuku; Nakasone, Hideo

4

Phosphine in paddy fields and the effects of environmental factors.  

PubMed

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

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

2013-11-01

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

Unique distribution of cyanobacterial podoviruses and their potential hosts in a paddy field of northeast China.  

PubMed

We first surveyed the DNA polymerase (pol) gene of cyanopodoviruses and the 16S-23S rRNA gene internal transcribed spacer (ITS) region of picocyanobacteria in a paddy field of northeast China. A total of 49 DNA pol clones and 76 ITS clones were obtained. The blast search results showed that all DNA pol clones and nearly 50% of the ITS clones had up to 76% and 50% identity/similarity to known sequences, respectively. Phylogenetic analyses showed that the DNA pol clones were narrowly distributed in the phylogenetic tree, and two new subclusters of cyanopodoviruses (PG-Pol-I and PG-Pol-II) specific to paddy field were discovered. In contrast, the distribution of ITS clones was very broad, and seven paddy-specific groups of picocyanobacteria (PG-Picocya-I-VII) were identified. In general, novel groups of cyanopodoviruses and picocyanobacteria were observed in this study, suggesting that coevolution between cyanopodoviruses and their hosts occurs in the paddy field. PMID:25088984

Wang, Guanghua; Liu, Junjie; Yu, Zhenhua; Jin, Jian; Liu, Xiaobing

2014-10-01

7

Mobility and Bioavailability of Technetium in Rice Paddy Fields  

SciTech Connect

Field observations and radiotracer experiments were carried out to investigate the behavior of 99Tc in paddy fields. The concentrations of global fallout 99Tc in soil collected from paddy fields in Japan were 6-88 milli-bequerels per kilogram (mBq/kg)-dry and activity ratios of 99Tc to 137Cs ranged from 1.1 x 10-3 to 7.0 x 10-3 with an average of (4.8 {+-} 2.1) x 10-3. (The theoretical activity ratio from nuclear fission yield is presently calculated as 3.3 x 10-4 with correction for radioactive decay.) This result implies that there was a tendency for 99Tc to accumulate in rice paddy fields. To understand the mechanisms of the accumulation, a sequential extraction method was applied over a 6-month period to waterlogged soils contaminated with TcO4-. From the results, it was clear that the TcO4- in soil under waterlogged conditions was readily changed to other insoluble physicochemical forms, such as TcO2, TcS2 and organically bound forms.

Uchida, S.; Tagami, K.

2003-02-24

8

Biodiversity and seasonal variation of the cyanobacterial assemblage in a rice paddy field in Fujian, China  

Microsoft Academic Search

Cyanobacteria are one of the main components of the microbiota in rice paddy fields and significantly contribute to its fertilization. The diversity and changes of the cyanobacterial assemblage were investigated during a rice growth season and after harvest in a paddy field located in Fujian Province, China. The cyanobacterial populations were analyzed by a semi-nested PCR, followed by denaturing gradient

Tieying Song; Lotta Mårtensson; Torsten Eriksson; Weiwen Zheng; Ulla Rasmussen

2005-01-01

9

Investigation of spatial distribution of radiocesium in a paddy field as a potential sink.  

PubMed

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

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

2013-01-01

10

Seasonal analysis of precipitation, drought and Vegetation index in Indonesian paddy field based on remote sensing data  

NASA Astrophysics Data System (ADS)

Paddy field is important agriculture crop in Indonesia. Rice is a food staple for 237,6 million Indonesian people. Paddy field growth is strongly influenced by water, but the amount of precipitation is unpredictable. Annual and interannual climate variability in Indonesia is unusual. In recent years remote sensing data has been used for measurement and monitoring of precipitation, drought and Vegetation index such as Global Satellite Mapping of Precipitation (GSMaP), Multi-purpose Transmission SATellite (MTSAT) and Moderate Resolution Imaging Spectroradiometer (MODIS). The objective of this research is to investigate seasonal variability of precipitation, drought and Vegetation index in Indonesian paddy field based on remote sensing data. The methodology consists of collecting of enhanced vegetation index (EVI) from MODIS data, mosaicking of image, collecting of region of interest of paddy field, collecting of precipitation and drought index based on Keetch Bryam Drought Index (KBDI) from GSMaP and MTSAT, and seasonal analysis. The result of this research has showed seasonal variability of precipitation, KBDI and EVI on Indonesia paddy field from 2007 until 2012. Precipitation begins from January until May and October until December, and KBDI begins to increase from June and peak in September only in South Sumatera precipitation almost in all month. Seasonal analysis has showed precipitation and KBDI affect on EVI that can indicate variety phenology of Indonesian paddy field. Peak of EVI occurs before peak of KBDI occurs and increasing of KBDI followed by decreasing of EVI. In 2010 all province got higher precipitation and smaller KBDI so EVI has three peaks such as in West Java that can indicated increasing of rice production.

Darmawan, S.; Takeuchi, W.; Shofiyati, R.; Sari, D. K.; Wikantika, K.

2014-06-01

11

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

12

Environmental behavior of profenofos under paddy field conditions.  

PubMed

The environmental behavior of 40% profenofos EC under paddy field conditions was studied. After application of 40% profenofos EC at 900 g a.i./ha level, the initial deposits of profenofos on rice plant, soil and water were found to be 32.700, 0.224 and 3.854 mg/kg respectively. Half-lives (t(1/2)) of profenofos on those substrates were observed to be 5.47, 3.75 and 3.42 days respectively. The residue levels of profenofos on rice straw, soil and rice grain were significantly affected by the dosage and frequency applied. The obtained results might help to recommend the suitable dose and calculate the safety period of profenofos application. PMID:20437027

He, Jiang; Fan, Mingtao; Liu, Xianjin

2010-06-01

13

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

14

Geochemical Transformation of Cadmium (Cd) from Creek to Paddy Fields in W Thailand  

NASA Astrophysics Data System (ADS)

Extensive Cd contamination of paddy soils in Tak Province, western Thailand, a consequence of Zn mining activities, was first established in 2005 and medical studies showed that the health of local communities was being impaired. Mae Tao, Tak Province, comprising many paddy fields and irrigation canals, has been selected for this study of the geochemical transformation of Cd from the contamination source in the mountainous region to the east of the study site through the community irrigation system to the paddy soils. The aim of this research is to (i) investigate the geochemical transformation of Cd as it is transported from the main irrigation creek through the canals and to the paddy fields, (ii) assess the availability of Cd to rice plants, which may be affected by both chemical and physical factors, and (iii) trial some practical treatments to minimise Cd concentrations in rice grains. Soils, irrigation canal sediments and water samples were collected during the dry season and at the onset of the rainy season. Rice samples were collected at harvesting time and samples of soil fertiliser were also obtained. Water samples were filtered, ultrafiltered and analysed by ICP-MS whilst sub-samples of dried, ground soils and sediments were first subjected to micro-wave assisted acid digestion (modified US EPA method 3052). XRD and SEM-EDX methods were used for mineralogical characterisation and selective chemical extractions have assisted in the characterisation of solid phase Cd associations. Soil Cd concentrations were in the range 2.5-87.6 µg g-1, with higher values being obtained for fields furthest from the main creek. Although current irrigation water Cd inputs are low (mean 1.9 ?g L-1; flood period), high loads of suspended particles still contribute additional Cd (4.2-9.8 µg L-1) to the paddy fields. For bioavailability assessment by a 3-step BCR sequential extraction, 70-90% Cd was in the exchangeable; HOAc-extractable fraction. That indicated that most of the Cd was in water soluble, exchangeable and carbonate-bound forms. For the fields with highest Cd concentration, SEM-EDX analysis identified two forms of Cd, i.e. Cd-Clay and Cd-CaCO3, in good agreement with the sequential extraction data. The predominance of easily extractable forms in the paddy field soils suggests that Cd may be readily absorbed by the rice plants. After harvesting, the Cd concentration in rice grains ranged from 0.05-4.0 µg g-1 and the concentration trends across the group of 18 fields matched well with the soil Cd data. Rice from nine out of the 18 fields contained Cd at greater than the safe level of 0.4 µg g-1.

Kosolsaksakul, Peerapat; Graham, Margaret; Farmer, John

2013-04-01

15

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

16

Coal fly ash and farmyard manure amendments in dry-land paddy agriculture field: Effect on N-dynamics and paddy productivity  

Microsoft Academic Search

A field study was conducted at a dry-land agricultural farm during paddy crop season to assess the effect of fly ash (FA) and farmyard manure (FYM) amendments on the dynamics of inorganic-N (NH4+ and NO3?), N-mineralization and nitrification rates and paddy yields. Four treatments, each consisted of three replicates, were established in completely randomized block design. The treatments were: control,

Jay Shankar Singh; Vimal Chandra Pandey; D. P. Singh

2011-01-01

17

Plant/microbe cooperation for electricity generation in a rice paddy field.  

PubMed

Soils are rich in organics, particularly those that support growth of plants. These organics are possible sources of sustainable energy, and a microbial fuel cell (MFC) system can potentially be used for this purpose. Here, we report the application of an MFC system to electricity generation in a rice paddy field. In our system, graphite felt electrodes were used; an anode was set in the rice rhizosphere, and a cathode was in the flooded water above the rhizosphere. It was observed that electricity generation (as high as 6 mW/m(2), normalized to the anode projection area) was sunlight dependent and exhibited circadian oscillation. Artificial shading of rice plants in the daytime inhibited the electricity generation. In the rhizosphere, rice roots penetrated the anode graphite felt where specific bacterial populations occurred. Supplementation to the anode region with acetate (one of the major root-exhausted organic compounds) enhanced the electricity generation in the dark. These results suggest that the paddy-field electricity-generation system was an ecological solar cell in which the plant photosynthesis was coupled to the microbial conversion of organics to electricity. PMID:18320186

Kaku, Nobuo; Yonezawa, Natsuki; Kodama, Yumiko; Watanabe, Kazuya

2008-05-01

18

Metabolic degradation of imidacloprid in paddy field soil.  

PubMed

The metabolic degradation and persistence of imidacloprid in paddy field soil were investigated following two applications of imidacloprid at 20 and 80 g a.i. ha(-1) at an interval of 10 days. The soil samples were collected at various time intervals. The limit of quantification for the analysis of imidacloprid and its metabolites was obtained at the concentration of 0.01 mg kg(-1). The initial deposits of total imidacloprid were found to be 0.44 and 1.61 mg kg(-1) following second applications. These residues could not be detected after 60 and 90 days following second applications of imidacloprid at lower and higher dosages, respectively. In soil, urea metabolite was found to be the maximum, followed by olefine, nitrosimine, 6-chloronicotinic acid, 5-hydroxy and nitroguanidine. The half-life values (t?/?) of imidacloprid were worked out to be 12.04 and 11.14 days, respectively, when applied at lower and higher doses, respectively. PMID:24891072

Akoijam, Romila; Singh, Balwinder

2014-10-01

19

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

20

[Effects of different multiple cropping systems on paddy field weed community under long term paddy-upland rotation].  

PubMed

Based on a long term field experiment, this paper studied the effects of different multiple cropping systems on the weed community composition and species diversity under paddy-upland rotation. The multiple cropping rotation systems could significantly decrease weed density and inhibited weed growth. Among the rotation systems, the milk vetch-early rice-late maize --> milk vetchearly maize intercropped with early soybean-late rice (CCSR) had the lowest weed species dominance, which inhibited the dominant weeds and decreased their damage. Under different multiple cropping systems, the main weed community was all composed of Monochoia vaginalis, Echinochloa crusgalli, and Sagittaria pygmae, and the similarity of weed community was higher, with the highest similarity appeared in milk vetch-early rice-late maize intercropped with late soybean --> milk vetch-early maize-late rice (CSCR) and in CCSR. In sum, the multiple cropping rotations in paddy field could inhibit weeds to a certain extent, but attentions should be paid to the damage of some less important weeds. PMID:24417111

Yang, Bin-Juan; Huang, Guo-Qin; Xu, Ning; Wang, Shu-Bin

2013-09-01

21

Water Management and N, P Losses From Paddy Fields in Southern Korea  

NASA Astrophysics Data System (ADS)

Assessment and control of nutrient losses from paddy fields is important to protect water quality of lakes and streams in Korea. A four-year field study was carried out to investigate water management practices and losses of nitrogen (N) and phosphorus (P) in rice paddy irrigation fields in southern Korea. The amount and water quality of rainfall, irrigation, surface drainage, and infiltration were measured and analyzed to estimate inputs and losses of N and P. The observed irrigation amount surpassed consumptive use, and approximately 52 to 69 percent of inflow (precipitation plus irrigation) was lost to surface drainage. Field data showed that significant amounts of irrigation water and rainfall were not effectively used for rice paddy culture. Water quality data indicated that drainage from paddy fields could degrade the recipient water environment. The nutrient balance indicated that significant amounts of nutrients (29.5 percent of total N and 8.6 percent of total P compared to input) were lost through sur face drainage. Furthermore, up to half the nutrient losses occurred during nonstorm periods. The study results indicate that inadequate water management influences N and P losses during both storm and nonstorm periods. Proper water management is required to reduce nutrient losses through surface drainage from paddy fields; this includes such measures as minimum irrigation, effective use of rainfall, adoption of proper drainage outlet structures, and minimized forced surface drainage.

Yoon, Kwang-Sik; Cho, Jae-Young; Choi, Jin-Kyu; Son, Jae-Gwon

2006-10-01

22

Heavy metal contents of paddy fields of Alcácer do Sal, Portugal.  

PubMed

Recent claims of metal contamination in the lower reaches of the Sado River, in the Alcácer do Sal region, Portugal, a major rice-producing area were investigated by carrying out metal surveys in the area. The elements Fe, Mn, Zn, Cu and Pb were measured in the soil and in rice plant parts--roots, shoots and grain--as well as in some weeds growing in the Sado banks, near the paddy fields. Results showed that the metal contents of paddy soils were similar to background concentrations, with the exception of Zn and Cu, which were above those concentrations and reached their highest levels at Vale de Guizo, the monitored station located furthest upstream in the Sado River. At some sites, plant roots accumulated relatively large amounts of Fe, Mn, Zn and Cu, but the shoot levels of these metals were within the normal range for rice plants. It is possible that varying, but significant, amounts of Fe associated with the roots were in the form of ferric hydroxide plaque covering their surfaces. Copper levels in the shoots of rice were below the normal contents cited for this plant in the literature. Metal levels of river sediments collected near Vale de Guizo seem to corroborate the possibility of some metal contamination in the Sado River, most probably derived from pyrites mining activity in the upper zone of the Sado basin. PMID:2305246

Fernandes, J C; Henriques, F S

1990-01-01

23

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

PubMed Central

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

He, Yupu; Yang, Shihong; Wang, Yijiang

2014-01-01

24

[Seasonal characteristics of CO2 fluxes from the paddy ecosystem in subtropical region].  

PubMed

CO2 fluxes from paddy ecosystem in subtropical hilly region were measured continuously using eddy covariance technique. Based on data rejecting, correcting and filling, the daily and annual CO2 fluxes were calculated from the instantaneous values, respectively. The objectives were to investigate the variation of CO2 fluxes on seasonal temporal scale, analyze the relationship between CO2 fluxes and environmental factors, and to quantify the annual net ecosystem exchange (NEE) from the paddy ecosystem. Results show the values of GPP, R(eco) and NEE are higher from Jun. to Sep. and lower in the other months. The NEE from May to Sep. accounted for above 80% of the annual value and is crucial to the whole annual value. Photosynthetically active radiation (PAR) and mean daily air temperature (T(a)) were two main influential factors for controlling the seasonal trend of GPP and NEE and could be described by binary linear functions, respectively. The annual NEE in paddy ecosystem was 2 475.6 g/(m2 x a). This is showed that paddy ecosystem was a carbon sink for the atmosphere in subtropical region. PMID:17489184

Zhu, Yong-Li; Tong, Cheng-Li; Wu, Jin-Shui; Wang, Ke-Lin; Wang, Qin-Xue; Ren, Xiu-E

2007-02-01

25

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

26

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

PubMed

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

Sander, Till; Gerke, Horst H

2009-02-16

27

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

28

Nitrogen fate and environmental consequence in paddy soil under rice-wheat rotation in the Taihu lake region, China  

Microsoft Academic Search

Field undisturbed tension-free monolith lysimeters and 15N-labeled urea were used to investigate the fate of fertilizer nitrogen in paddy soil in the Taihu Lake region under a summer\\u000a rice-winter wheat rotation system. We determined nitrogen recovered by rice and wheat, N remained in soil, and the losses\\u000a of reactive N (i.e., NH3, N2O, NO3\\u000a ?, organic N and NH4\\u000a +)

Xu Zhao; Ying-xin Xie; Zheng-qin Xiong; Xiao-yuan Yan; Guang-xi Xing; Zhao-liang Zhu

2009-01-01

29

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

30

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

31

Detection of Anammox Activity and 16S rRNA Genes in Ravine Paddy Field Soil  

PubMed Central

An anammox assay involving a 15N tracer and gas chromatography-mass spectrometry revealed that the potential anammox activity accounted for 1 to 5% of total N2 production in a ravine paddy field, Japan. Among four 4-cm-deep layers, the top layer showed the highest activity. Clone libraries showed that the DNA in the top layer contained sequences related to those of Candidatus ‘Brocadia fulgida’, Ca. ‘B. anammoxidans’, and Ca. ‘Kuenenia stuttgartiensis’. These results suggest that a specific population of anammox bacteria was present in paddy soils, although a small part of dinitrogen gas was emitted from the soil via anammox. PMID:22353769

Sato, Yoshinori; Ohta, Hiroyuki; Yamagishi, Takao; Guo, Yong; Nishizawa, Tomoyasu; Rahman, M. Habibur; Kuroda, Hisao; Kato, Task; Saito, Masanori; Yoshinaga, Ikuo; Inubushi, Kazuyuki; Suwa, Yuichi

2012-01-01

32

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.

33

Salinity and organic amendment effects on methane emission from a rain-fed saline paddy field  

Microsoft Academic Search

Organic amendment is a traditional practice for rehabilitating saline patches in north-east Thailand, but organic matter is known to enhance methane emission. However, a high degree of salinity might mitigate methane emission. The objective of the present study was to quantify the effects of salinity and organic amendments on methane emission from rain-fed paddy fields exposed to increasing salinity. A

Sakulrat Supparattanapan; Patcharee Saenjan; Cécile Quantin; Jean Luc Maeght; Olivier Grünberger

2009-01-01

34

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

35

Water and Mass Balances in Paddy Fields Area with a Cyclic Irrigation System Situated along Lake Kasumigaura  

NASA Astrophysics Data System (ADS)

Paddy fields are widely distributed along Lake Kasumigaura. Agricultural drainage water directly flows into the lake through bank-based water canal. Both the discharged loads to the lake from paddy fields and the inflow loads from the lake by irrigation water were measured during irrigation period. In this district, some of drained water from the paddy is reused for irrigation by the cyclic irrigation system. As a result, about 57% of irrigation water was occupied by the reuse of drained water. Net effluent loadings of COD, T-N, and T-P were -25 kg·ha-1, -2.4 kg·ha-1, and -0.07 kg·ha-1, respectively. Inflow loads to the paddy from the lake were greater than outflow loads from the paddy to the lake. Cyclic irrigation water system much contributed to the reduction of effluent load to the lake.

Kitamura, Tatsumi; Kuroda, Hisao; Yamamoto, Mamiko; Negishi, Masami; Tabuchi, Toshio

36

Behavior of Suspended Sediments with Radionuclide in the Paddy Field, Fukushima Japan  

NASA Astrophysics Data System (ADS)

After the nuclear reactor accident in Fukushima on March 11, 2011, huge amounts of radionuclide such as Caesium-137, which is an artificial radionuclide with a half-life of 30.17 years, has been produced. Most of the fallen Cs-137 infiltrated into soil together with rainfall and was absorbed by soil sediments. The potential concentration of radionuclides into paddy field, as investigated in this study, has consequency on health, agriculture and remediation of contaminated areas. Paddy field typically are flat, surrounded by dams (10-50 cm)delimiting small pools with a water level of approximately20cm. Therefore, they can potentially catch huge amounts of suspended sediments from incoming rivers. However, recent studies suggested the paddy field can be a source of suspended sediments in some conditions. In this study, we intended to investigate the characteristics of Cs137 associated to sediment into paddy field as well as its incoming and outgoing and flux of that in paddy field. The study site was set on the Yoshiguchi, Kawamata-cho, Fukushima prefecture(N 37 35' 26.15", E140 38' 14.97"). This place is located 30km from the damaged Fukushima nuclear reactor. Two plots were set: One was tillaged as usual (plot UE, 30x17m), while the upper 5 to 10 cm of the other plot's surface was scraped before tillage.(plot ST, 43x17m). The lower part of each plot has a Parshall flume with water gauge, turbidimeter and rain gauge. After tillage, water was put into the plot field and rice seedlings were transplanted. Every week we corrected a suspended sediment samples and measured Cs137 concentration. At the plot ST, out flow of the Cs137 density was less than 35% of that of UE plot.

Wakahara, T.; Onda, Y.; Kato, H.

2011-12-01

37

Effects of Fipronil Insecticide Application on Sympetrum sp. Larvae and Adults in Experimental Rice Paddy Field  

NASA Astrophysics Data System (ADS)

The effect of on sowing and before transplanting application of the phenyl pyrazole insecticide, fipronil, on the survivorship Sympetrum spp. was investigated in plots of an experimental rice paddy field. In addition, the effect of two pesticide applications on rice weevils was investigated. A total of nine paddy plots were used in this study: three were treated with fipronil at the before transplanting application , three at the on sowing application, and the three remaining plots were left untreated for use as controls. Fipronil concentrations in paddy water at the time of application in before transplanting and on sowing treatments reached 1.45 and 1.20 ?g/L, respectively. A comparison of experimental and control plots revealed a marked absence of Sympetrum frequens larvae, exuviae and adults from fipronil-treated fields. Adult density of Sympetrum sp. and members of Lestidae in paddy fields before transplanting application were considerably lower than in control plots. Our results show that before transplanting application is more effective than on sowing application for treating rice weevils, but that on sowing application may still be harm against dragonflies.

Jinguji, Hiroshi; Ueda, Tetsuyuki; Tsunoda, Manami; Aihara, Shoko; Saito, Mitsuo

38

Ammonia volatilization from the surface of a Japanese paddy field during rice cultivation  

Microsoft Academic Search

Ammonia (NH3) volatilization from the surface of a Japanese paddy field during rice cultivation was measured using the dynamic chamber method with a dry NH3 collector. A preliminary investigation showed that a dry NH3 collector with phosphoric-acid-impregnated filters could collect volatilized NH3 with sufficient efficiency. The experimental field included six lysimeter plots of Gray Lowland soil with a soil pH

Kentaro Hayashi; Seiichi Nishimura; Kazuyuki Yagi

2006-01-01

39

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

PubMed

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

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

2014-02-15

40

Purification of contaminated paddy fields by clean water irrigation over two decades.  

PubMed

Paddy fields near a mining site in north part of Guangdong Province, PR China, were severely contaminated by heavy metals as a result of wastewater irrigation from the tailing pond. The following clean water irrigation for 2 decades produced marked rinsing effect, especially on Pb and Zn. Paddy fields continuously irrigated with wastewater ever since mining started (50 years) had 1,050.0 mg kg?1 of Pb and 810.3 mg kg?1 of Zn for upper 20 cm soil, in comparison with 215.9 mg kg?1 of Pb and 525.4 mg kg?1 of Zn, respectively, with clean water irrigation for 20 years. Rinsing effect mainly occurred to a depth of upper 40 cm, of which the soil contained highest metals. Copper and Cd in the farmlands were also reduced due to clean water irrigation. Higher availability of Pb might partly account for more Pb transferred from the tailing pond to the farmland and also more Pb removal from the farmland as a result of clean water irrigation. Neither rice in the paddy field nor dense weeds in the uncultivated field largely took up the metals. However, they might contribute to activate metals differently, leading to a different purification extent. Rotation of rice and weed reduced metal retention in the farmland soil, in comparison with sole rice growth. Harvesting of rice grain (and partially rice stalk) only contributed small fraction of total amount of removed metal. In summary, heavy metal in paddy field resulting from irrigation of mining wastewater could be largely removed by clean water irrigation for sufficient time. PMID:23797601

Tai, Yiping; Lu, Huanping; Li, Zhian; Zhuang, Ping; Zou, Bi; Xia, Hanping; Wang, Faming; Wang, Gang; Duan, Jun; Zhang, Jianxia

2013-10-01

41

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

42

Effects of supplementary composts on microbial communities and rice productivity in cold water paddy fields.  

PubMed

Cold water paddy field soils are relatively unproductive, but can be ameliorated by supplementing inorganic fertilizer with animal waste-based composts. The yield of two rice cultivars was significantly raised by providing either chicken manure or cow dung-based compost. The application of these composts raised the soil pH as well as both the total nitrogen and ammonium nitrogen content, which improved the soil's fertility and raised its nitrification potential. The composts had a measurable effect on the abundance of nitrogen cycling related soil microbes, as measured by estimating the copy number of various bacterial and archaeal genes using quantitative real time PCR. The abundance of ammonia oxidizing archaea and bacteria was markedly encouraged by the application of chicken manure-based compost. Supplementation with the composts helped promote the availability of soil nitrogen in the cold water paddy field, thereby improving the soil's productivity and increasing the yield of the rice crop. PMID:25406532

Xie, Kaizhi; Xu, Peizhi; Yang, Shaohai; Lu, Yusheng; Jiang, Ruiping; Gu, Wenjie; Li, Wenying; Sun, Lili

2014-11-19

43

Plant\\/microbe cooperation for electricity generation in a rice paddy field  

Microsoft Academic Search

Soils are rich in organics, particularly those that support growth of plants. These organics are possible sources of sustainable\\u000a energy, and a microbial fuel cell (MFC) system can potentially be used for this purpose. Here, we report the application of\\u000a an MFC system to electricity generation in a rice paddy field. In our system, graphite felt electrodes were used; an

Nobuo Kaku; Natsuki Yonezawa; Yumiko Kodama; Kazuya Watanabe

2008-01-01

44

[Effects of controlled release fertilizers on N2O emission from paddy field].  

PubMed

With close chamber method, this paper studied the effects of controlled release fertilizer (CRF), non-coated compound fertilizer (Com) and conventional urea (CK) on N2O emission from paddy field. The results showed that within 10 days after transplanting, the ammonium and nitrate concentrations in the surface water of the plot treated with CRF were significantly different from those treated with Com. The partial coefficient between N2O emission rates and corresponding nitrate concentrations in the water was significantly high (r = 0.6834). Compared with Com, CRF was able to reduce N2O emission from the paddy field. Within 100 days after basal application, the N2O emission rate of treatment CRF was only 13.45%-21.26% of Corn and 71.17%-112.47% of CK. The N2O emission of Com was mainly concentrated in 1-25 d after basal fertilization and mid-aeration period, but that of CRF was remarkably lower during same period, while the peak of N2O emission of CK was postponed and reduced. It was concluded that both one-time fertilization of CRF and several-time fertilizations of conventional urea were able to reduce N2O emission from the paddy field. PMID:15707336

Li, Fangmin; Fan, Xiaolin; Liu, Fang; Wang, Qiang

2004-11-01

45

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

PubMed Central

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

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

2014-01-01

46

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

PubMed

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

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

2014-07-01

47

Paddy field mapping and yield estimation by satellite imagery and in situ observations  

NASA Astrophysics Data System (ADS)

Since Asian countries are responsible for approximately 90% of the world rice production and consumptions, rice is the most significant cereal crop in Asia. In order to ensure food security and take mitigation strategies or policies to manage food shortages, timely and accurate statistics of rice production are essential. It is time and cost consuming work to create accurate statistics of rice production by ground-based measurements. Hence, satellite remote sensing is expected to contribute food security through the systematic collection of food security related information such as crop growth or yield estimation. In 2011, Japan Aerospace Exploration Agency (JAXA) is collaborating with GISTDA (Geo-Informatics and Space Technology Development Agency, Thailand) in research projects of rice yield estimation by integrating satellite imagery and in situ data. Thailand is one of the largest rice production countries and the largest rice exporting country, therefore rice related statistics are imperative for food security and economy in the country. However, satellite observation by optical sensor in tropics including Thailand is highly limited, because the area is frequently covered by cloud. In contrast, Japanese microwave sensor, namely Phased-Array L-Band Synthetic Aperture Radar (PALSAR) on board Advanced Land Observing Satellite (ALOS) is suitable for monitoring cloudy area such as Southeast Asia, because PALSAR can penetrate clouds and collect land-surface information even if the area is covered by cloud. In this study, rice crop yield over Khon Kaen, northeast part of Thailand was estimated by combining satellite imagery and in-situ observation. This study consists of mainly two parts, paddy field mapping and yield estimation by numerical crop model. First, paddy field areas were detected by integrating PALSAR and AVNIR-2 data. PALSAR imagery has much speckle noise and the border of each landcover is ambiguous compared to that of optical sensor. To overcome this problem, we used AVNIR-2 data for object-based image analysis and derived each object was linked with backscatter coefficient of PALSAR. Then, paddy field areas were detected by using seasonal changes of backscatter coefficients. Derived paddy field map over Kohn Kean area was validated with ground-based measurements and it showed high accuracy. Finally, in order to estimate rice crop yield, numerical crop model was run with model parameters related to physiological aspect of rice and meteorological data collected by Automatic Weather Station (AWS) placed at study area, field survey and satellite products. This processing was implemented all over the detected paddy filed areas and overall yield was estimated by counting up each result. Consequently, it was found that the yield estimation was reasonable validated with agricultural statistics in Thailand.

Oyoshi, K.; Sobue, S.

2011-12-01

48

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

49

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

50

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

51

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

52

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

53

Microbial community responsible for the decomposition of rice straw in a paddy field: estimation by phospholipid fatty acid analysis  

Microsoft Academic Search

To estimate the microbial communities responsible for rice straw decomposition in paddy field, phospholipid fatty acid (PLFA) composition of leaf sheaths and blades was analyzed during the decomposition of both residues under upland conditions after harvest and under flooded conditions at the time of transplanting of rice plants. In addition, rice straw that had been placed in the field under

Asumi Nakamura; ChoCho Tun; Susumu Asakawa; Makoto Kimura

2003-01-01

54

[Responses of CO2 fluxes to light intensity and temperature in rice paddy field].  

PubMed

CO2 fluxes in rice paddy ecosystem in subtropical hilly region were measured continuously using eddy covariance technique. The objectives were to investigate the responses of CO2 fluxes to light intensity and temperature in the paddy ecosystem. Results showed a rectangular hyperbolic light-response function could be used to describe the relationship of CO2 flux and photosynthetic photon flux density (PPFD). The absolute values of CO2 fluxes increased with the increment of PPFD. When PPFD was higher than 1000 micromol/(m2 x s), the maximum was observed. CO2 fluxes responded differently to light between early and late rice. Values of quantum yield of late rice (0.0465-0.0999 micromol/micromol) were general higher than that of early rice (0.0176-0.0541 micromol/micromol). Moreover, the quantum yield and the maximum rate of photosynthesis assimilation in the blooming stage were higher than that in tillering and ripening stages. In nighttime, respiration from soil and plants (ecosystem respiration, Reco) changed exponentially with the increase of soil temperature at the depth of 5 cm (T5), 10 cm (T10), and 20 cm (T20), respectively. Whereas, T5 was more feasible than others to be considered as the temperature parameter for Reco calculation. During early rice growing season, Reco was more sensitive to temperature change than that during late rice growing season. PMID:18637359

Zhu, Yong-li; Wu, Jin-shui; Tong, Cheng-li; Wang, Ke-lin; Wang, Qin-xue

2008-04-01

55

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

NASA Astrophysics Data System (ADS)

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 variety of non-irrigated crops, allowing study of the C dynamics of paddy soil development in direct comparison to soils not used for lowland rice cultivation (non-paddy). Beside one soil profile at the mudflat, which represents the parent material, soil profiles of the chronosequence were sampled by horizon in triplicate, ranging from 50 to 2000 years of paddy soil use and from 50 to 700 year old non-paddy soils. All samples were analysed for 14C concentrations and for bulk density, total C (TC) as well as organic C (OC) and inorganic C (IC) concentrations, and the corresponding stocks were calculated. In addition, topsoils were subjected to a physical fractionation procedure to evaluate changes of OC saturation in particle size fractions during soil development. In the first 300 years, rice cultivation did not significantly change TC stocks of the soils compared to that of non-paddy soils. The fast decalcification in paddy soils was compensated by a similar gain of OC in the topsoil. Higher 14C concentrations indicate the original C of the sediment in paddy topsoils was replaced faster by recently photosynthesized C than in non-paddy topsoils. OC accumulation in paddy topsoils appears to be complete after 300 years. High increases of OC in paddy topsoils may be due to high OC inputs associated with retarded decomposition during flooding of paddy fields. After 300 years, the decalcification in paddy soils was not compensated anymore by further enrichment of OC in the topsoil. In addition, the paddy soils lost OC in the subsoil. The dense plough pan decreases OC transport from the paddy topsoil into the subsoil, while OC transport in non-paddy soils is unimpeded. Therefore, the replacement of the old sedimentary C by new OC was slower in the paddy subsoils than in the non-paddy soils as indicated by 14C data. The enrichment of OC in paddy topsoils in the first 300 years can be directly related to increasing OC contents and saturation levels in the silt- and clay-sized fractions. However, ongoing redistribution of OC between silt- and clay- sized fractions after 300 years indicates that small-scale processes of OC storage are still proceeding.

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

2010-12-01

56

Assessment of the air-soil partitioning of polycyclic aromatic hydrocarbons in a paddy field using a modified fugacity sampler.  

PubMed

Rice, one of the most widely cultivated crops, has received great attention in contaminant uptake from soil and air, especially for the special approaches used for its cultivation. The dry-wet alternation method can influence the air-soil partitioning of semivolatile organic compounds (SVOCs) in the paddy ecosystem. Here, we modified a fugacity sampler to investigate the air-surface in situ partitioning of ubiquitous polycyclic aromatic hydrocarbons (PAHs) at different growth stages in a suburban paddy field in South China. The canopy of rice can form a closed space, which acts like a chamber that can force the air under the canopy to equilibrate with the field surface. When we compared the fugacities calculated using a fugacity model of the partition coefficients to the measured fugacities, we observed similar trends in the variation, but significantly different values between different growing stages, especially during the flooding stages. However, the measured and calculated fugacity fractions were comparable when uncertainties in our calculations were considered, with the exception of the high molecular weight (HMW) PAHs. The measured fugacity fractions suggested that the HMW PAHs were also closed to equilibrium between the paddy field and atmosphere. The modified fugacity sampler provided a novel way of accurately determining the in situ air-soil partitioning of SVOCs in a wet paddy field. PMID:25453511

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

2015-01-01

57

Effect of plastic-film mulching on leaching of nitrate nitrogen in an upland field converted from paddy  

Microsoft Academic Search

A lysimeter experiment was conducted to examine the effects of plastic film mulching on the leaching rate of nitrate nitrogen (NO 3-N) from chemical fertilizer that was applied to an upland field that had been converted from paddy rice production. Leaching was monitored in two lysimeters filled with sandy loam soil, which contained low soil organic matter content, under different

Tomokazu Haraguchi; Atsushi Marui; Kozue Yuge; Yoshisuke Nakano; Ken Mori

2004-01-01

58

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

59

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

60

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

61

Phylogeny of numerically abundant culturable anaerobic bacteria associated with degradation of rice plant residue in Japanese paddy field soil  

Microsoft Academic Search

Culturable anaerobic bacterial populations on rice plant residue (straw and stubble with roots) in paddy field soil were found on the order of 109 CFU (colony-forming units) (g dry weight of plant residue)?1, and the percentages of spores were usually less than 1% of the total anaerobes. Anaerobic bacteria were isolated from each sample by picking up colonies on the

Hiroshi Akasaka; Tomoe Izawa; Katsuji Ueki; Atsuko Ueki

2003-01-01

62

Conversion of upland to paddy field specifically alters the community structure of archaeal ammonia oxidizers in an acid soil  

NASA Astrophysics Data System (ADS)

The function of ammonia-oxidizing archaea (AOA) and bacteria (AOB) depends on the major energy-generating compounds (i.e., ammonia and oxygen). The diversification of AOA and AOB communities along ecological gradients of substrate availability in a complex environment have been much debated but rarely tested. In this study, two ecosystems of maize and rice crops under different fertilization regimes were selected to investigate the community diversification of soil AOA and AOB upon conversion of an upland field to a paddy field and long-term field fertilization in an acid soil. Real-time quantitative polymerase chain reaction of ammonia monooxygenase (amoA) genes demonstrated that the abundance of AOA was significantly stimulated after conversion of upland to paddy soils for more than 100 yr, whereas a slight decline in AOB numbers was observed. Denaturing gradient gel electrophoresis fingerprints of amoA genes further revealed remarkable changes in the community compositions of AOA after conversion of aerobic upland to flooded paddy field. Sequencing analysis revealed that upland soil was dominated by AOA within the soil group 1.1b lineage, whereas the marine group 1.1a-associated lineage predominated in AOA communities in paddy soils. Irrespective of whether the soil was upland or paddy soil, long-term field fertilization led to increased abundance of amoA genes in AOA and AOB compared with control treatments (no fertilization), whereas archaeal amoA gene abundances outnumbered their bacterial counterparts in all samples. Phylogenetic analyses of amoA genes showed that Nitrosospira cluster-3-like AOB dominated bacterial ammonia oxidizers in both paddy and upland soils, regardless of fertilization treatment. The results of this study suggest that the marine group 1.1a-associated AOA will be better adapted to the flooded paddy field than AOA ecotypes of the soil group 1.1b lineage, and indicate that long-term flooding is the dominant selective force driving the community diversification of AOA populations in the acid soil tested.

Alam, M. S.; Ren, G. D.; Lu, L.; Zheng, Y.; Peng, X. H.; Jia, Z. J.

2013-08-01

63

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

PubMed

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

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

2015-01-01

64

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

65

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

2014-11-01

66

[Distribution characteristics of soil humus fractions stable carbon isotope natural abundance (delta 13C) in paddy field under long-term ridge culture].  

PubMed

A 16-year field experiment was conducted in a ridge culture paddy field in the hilly region of Sichuan Basin, aimed to investigate the distribution characteristics of stable carbon isotope natural abundance (delta 13C) in soil humus fractions. The soil organic carbon (SOC) content in the paddy field under different cultivation modes ranked in the order of wide ridge culture > ridge culture > paddy and upland rotation. In soil humus substances (HS), humin (HU) was the main composition, occupying 21% - 30% of the total SOC. In the extracted soil carbon, humic acid (HA) dominated, occupying 17% - 21% of SOC and 38% - 65% of HS. The delta 13C value of SOC ranged from -27.9 per thousand to -25.6 per thousand, and the difference of the delta 13C value between 0-5 cm and 20-40 cm soil layers was about 1.9 per thousand. The delta 13C value of HA under different cultivation modes was 1 per thousand - 2 per thousand lower than that of SOC, and more approached to the delta 13C value of rapeseed and rice residues. As for fulvic acid (FA), its delta 13C value was about 2 per thousand and 4 per thousand higher than that of SOC and HA, respectively. The delta 13C value of HU in plough layer (0-20 cm) and plow layer (20-40 cm) ranged from -23.7 per thousand - -24.9 per thousand and -22.6 per thousand - -24.2 per thousand, respectively, reflecting the admixture of young and old HS. The delta 13C value in various organic carbon fractions was HU>FA>SOC>rapeseed and rice residues>HA. Long-term rice planting benefited the increase of SOC content, and cultivation mode played an important role in affecting the distribution patterns of soil humus delta 13C in plough layer and plow layer. PMID:21774322

Tang, Xiao-hong; Luo, You-jin; Ren, Zhen-jiang; Lü, Jia-ke; Wei, Chao-fu

2011-04-01

67

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

68

Spatial variability of soil organic matter and nutrients in paddy fields at various scales in southeast China  

Microsoft Academic Search

The present study examines the spatial dependency of soil organic matter and nutrients in paddy fields at three different\\u000a scales using geostatistics and geographic information system techniques (GIS). The spatial variability of soil organic matter\\u000a (SOM), total nitrogen (TN) and available phosphorus (AP) has been characterized using a total of 460, 131 and 64 samples that\\u000a were, respectively, collected from

Xingmei Liu; Keli Zhao; Jianming Xu; Minghua Zhang; Bing Si; Fan Wang

2008-01-01

69

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

70

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

71

Purification and characterization of carboxymethyl cellulase from Bacillus sp. isolated from a paddy field.  

PubMed

A microorganism hydrolyzing carboxymethyl cellulose was isolated from a paddy field and identified as Bacillus sp. Production of cellulase by this bacterium was found to be optimal at pH 6.5, 37 degrees C and 150 rpm of shaking. This cellulase was purified to homogeneity by the combination of ammonium sulphate precipitation, DEAE cellulose, and sephadex G-75 gel filtration chromatography. The cellulase was purified up to 14.5 fold and had a specific activity of 246 U/mg protein. The enzyme was a monomeric cellulase with a relative molecular mass of 58 kDa, as determined by SDS-PAGE. The enzyme exhibited its optimal activity at 50 degrees C and pH 6.0. The enzyme was stable in the pH range of 5.0 to 7.0 and its stability was maintained for 30 min at 50 degrees C and its activity got inhibited by Hg2+, Cu2+, Zn2+, Mg2+, Na2+, and Ca2+. PMID:22708346

Vijayaraghavan, Ponnuswamy; Vincent, S G Prakash

2012-01-01

72

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

73

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

74

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

75

Phosphorus interception in floodwater of paddy field during the rice-growing season in TaiHu Lake Basin.  

PubMed

A field experiment located in TaiHu Lake Basin in China was conducted, by application of superphosphate or a mixture of superphosphate with manure, to elucidate the interception of P export during a typical rice growing season through 'zero-drainage water management' combined with sound irrigation, rainfall forecasting and field drying. P concentrations in floodwater rapidly declined before the first event of field drying, and subsequently tended to return to the background levels. Before the first field drying TPP was the predominant P form in floodwater on fields with no P input, DRP on plots that received superphosphate only, and DOP on plots treated with the mixture of superphosphate and manure. Thereafter TPP became the major form. No P export was found from the paddy fields, but a retention of 0.65kgha(-1), mainly due to soil P sorption. The results recommend the zero-drainage water management for full-scale areas for minimizing P export. PMID:16979805

Zhang, Zhijian; Zhang, Jianying; He, Ruo; Wang, Zhaode; Zhu, Yinmei

2007-01-01

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

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

78

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

79

Decrease of herbicide bromobutide and its debromo metabolite in paddy field soil during 24 weeks after application.  

PubMed

Variations in concentrations of herbicide bromobutide (RS)-2-bromo-N-(?,?-dimethylbenzyl)-3,3-dimethylbutyramide, and its metabolite bromobutide-debromo, N-(?,?-dimethylbenzyl)-3,3-dimethylbutyramide were investigated in soils from three paddy fields used for rice farming at 24 weeks after application. The bromobutide concentration was maximum within 24 h after application. That of bromobutide-debromo was maximum within 5-7 days of application. Each gradually decreased to below detection limits at 12-22 weeks after application. Bromobutide was detected up to 76-104 days after application in the paddy soils, whereas bromobutide-debromo was detected up to 125 days after application. The bromobutide composition was higher than 90 % within 6 days of application, decreasing to less than 5 % by 125 days of application. The decrease of bromobutide amount in the soil was inferred as the first-order reaction. The bromobutide half-life was calculated as 12-21 days (16 days mean) during 18-104 days following application. PMID:22476350

Morohashi, Masayuki; Nagasawa, Shunsuke; Enya, Nami; Ohno, Masaki; Suzuki, Kazuyuki; Kose, Tomohiro; Kawata, Kuniaki

2012-07-01

80

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

NASA Astrophysics Data System (ADS)

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

Ritsuko, Fuchiyama; Takeshi, Ota; Michikazu, Fukuhara

2013-04-01

81

Impact of Azospirillum sp. B510 inoculation on rice-associated bacterial communities in a paddy field.  

PubMed

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

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

2013-01-01

82

Exploring the applicability of field measurements of mid-infrared reflectance using a portable band-pass filter type radiometer to assess paddy rice yields  

Microsoft Academic Search

There are few case studies concerning field radiometric measurements in the mid-infrared (MIR) wavelengths for crop plants. This article describes radiometric experiments measuring reflectance in the MIR bands (3.425 ± 0.1 and 3.9 ± 0.1 ?m) to evaluate the number of panicles (NP, m) of ripening paddy rice using a portable band-pass filter type spectroradiometer. First, laboratory experiments were conducted

M. Shibayama; T. Sakamoto; A. Kimura

2011-01-01

83

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

84

[Effect of controlled release fertilizer on nitrous oxide emission from paddy field under plastic film mulching cultivation].  

PubMed

A field experiment was conducted to assess the effect of controlled release fertilizer on N2O emission in paddy field under plastic film mulching cultivation (PM) with water-saving irrigation. Results showed that in the rice growing season, cumulative N2O emissions from the plots applied with urea (PM+U) and with controlled release fertilizer (PM+CRF) were (38.2 +/- 4.4) and (21.5 +/- 5.2) mg N x m(-2), respectively. The N2O emission factors were 0.25% and 0.14% in the treatments PM+U and PM+CRF, respectively. The controlled release fertilizer decreased the total N2O emission by 43.6% compared with urea, of which 49.6% was reduced before the drying period. It also reduced the peak of N2O emission by 52.6%. However, it did not affect soil microbial biomass N and soil NH(4+)-N content at any rice growing stage, and grain yield either. No significant correlation was observed between N2O flux and soil Eh or soil temperature at the depth of 5 cm. PMID:24984495

Zhang, Yi; Lü, Shi-Hua; Ma, Jing; Xu, Hua; Yuan, Jiang; Dong, Yu-Jiao

2014-03-01

85

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

86

A three-year experiment confirms continuous immobilization of cadmium and lead in contaminated paddy field with biochar amendment.  

PubMed

Heavy metal contamination in croplands has been a serious concern because of its high health risk through soil-food chain transfer. A field experiment was conducted in 2010-2012 in a contaminated rice paddy in southern China to determine if bioavailability of soil Cd and Pb could be reduced while grain yield was sustained over 3 years after a single soil amendment of wheat straw biochar. Contaminated biochar particles were separated from the biochar amended soil and microscopically analyzed to help determine where, and how, metals were immobilized with biochar. Biochar soil amendment (BSA) consistently and significantly increased soil pH, total organic carbon and decreased soil extractable Cd and Pb over the 3 year period. While rice plant tissues' Cd content was significantly reduced, depending on biochar application rate, reduction in plant Pb concentration was found only in root tissue. Analysis of the fresh and contaminated biochar particles indicated that Cd and Pb had probably been bonded with the mineral phases of Al, Fe and P on and around and inside the contaminated biochar particle. Immobilization of the Pb and Cd also occurred to cation exchange on the porous carbon structure. PMID:24685528

Bian, Rongjun; Joseph, Stephen; Cui, Liqiang; Pan, Genxing; Li, Lianqing; Liu, Xiaoyu; Zhang, Afeng; Rutlidge, Helen; Wong, Singwei; Chia, Chee; Marjo, Chris; Gong, Bin; Munroe, Paul; Donne, Scott

2014-05-15

87

Spatial variability of soil organic matter and nutrients in paddy fields at various scales in southeast China  

NASA Astrophysics Data System (ADS)

The present study examines the spatial dependency of soil organic matter and nutrients in paddy fields at three different scales using geostatistics and geographic information system techniques (GIS). The spatial variability of soil organic matter (SOM), total nitrogen (TN) and available phosphorus (AP) has been characterized using a total of 460, 131 and 64 samples that were, respectively, collected from the Hangzhou-Jiaxing-Huzhou (HJH) Plain (10 km), Pinghu county (1,000 m) and a test plot area (100 m) within the Pinghu county, Zhejiang province of the southeast China. Semivariograms showed that the SOM and TN had moderate spatial dependency on the large scale of HJH plain and moderate scale of Pinghu county with long spatial correlation distances. At the moderate scale of Pinghu county and the small scale of a test plot area, the AP data did not show any spatial correlation, but had moderate spatial dependency in HJH plain. Spherical and exponential variogram models were best fitted to all these soil properties. Maps of SOM and TN were generated through interpolation of measured values by ordinary kriging, and AP by lognormal kriging. This study suggests that precision management of SOM and TN is feasible at all scales, and precision management of AP is feasible at large scales.

Liu, Xingmei; Zhao, Keli; Xu, Jianming; Zhang, Minghua; Si, Bing; Wang, Fan

2008-01-01

88

Effect of timing of joint application of hydroquinone and dicyandiamide on nitrous oxide emission from irrigated lowland rice paddy field.  

PubMed

A field experiment was conducted to study the effect of timing of joint application of urease inhibitor hydroquinone (HQ) and nitrification inhibitor dicyandiamide (DCD) on N(2)O emission from irrigated lowland rice paddy field. Four treatments including Treatment CK (the control with urea alone), HQ/DCD-1 (application of HQ and DCD together with fertilizer before transplanting), HQ/DCD-2 (HQ and DCD with fertilizer at tillering stage) and HQ/DCD-3 (HQ and DCD with fertilizer at panicle initiation stage) were designed and implemented separately during rice growth period. Seasonal peaks of N(2)O flux occurred during midseason drainage and significant negative correlation between N(2)O flux and water layer depth was observed (r=-0.69 to -0.75, P<0.01). Mean N(2)O flux was the highest in the control with urea alone, while joint addition of HQ and DCD with urea lowered mean N(2)O flux considerably (P<0.05). Total N(2)O emission during rice growth season in Treatment CK, HQ/DCD-1, HQ/DCD-2 and HQ/DCD-3 was 3.90, 2.98, 1.73 and 3.23kgN(2)O-N ha(-1), respectively. Application of HQ and DCD together with basal fertilizer, tillering fertilizer and panicle initiation fertilizer decreased the total N(2)O emission by 24%, 56% and 17%, respectively, while increased grain yield by 10%, 18% and 6%, respectively. Effect of application of inhibitors on N(2)O emission during the continuous period from incorporation of HQ and DCD to rice harvest was also studied, where results indicating that the highest inhibiting efficiency of inhibitors on N(2)O emission was recorded when HQ and DCD applied with fertilizer at tillering stage. PMID:19269003

Li, Xianglan; Zhang, Guangbin; Xu, Hua; Cai, Zucong; Yagi, Kazuyuki

2009-06-01

89

Quantifying methane emissions from rice fields in Tai-Lake region, China by coupling detailed soil database with biogeochemical model  

NASA Astrophysics Data System (ADS)

China's paddy rice accounts for about 22% of the world's rice fields, therefore it is crucial to accurately estimate the CH4 emissions at regional scale to gauge their contribution to global greenhouse gas effect. This paper reports an application of a biogeochemical model, DeNitrification and DeComposition or DNDC, for quantifying CH4 emissions from rice fields in Tai-Lake region of China by linking DNDC to a 1:50 000 soil database, which was derived from 1107 paddy soil profiles in the Second National Soil Survey of China in the 1980s-1990s. The modeled results estimate that the 2.34 M ha of paddy rice fields in Tai-Lake region emitted about CH4 of 5.67 Tg C for the period of 1982-2000, with the average CH4 flux ranged from 114 to 138 kg C ha-1y-1. The highest emission rate (659.24 kg C ha-1 y-1) occurred in the subgroup of "gleyed paddy soils", while the lowest (90.72 kg C ha-1y-1) were associated with the subgroup "degleyed paddy soils". The subgroup "hydromorphic paddy soils" accounted for about 52.82% of the total area of paddy soils, the largest of areas of all the soil subgroups, with the CH4 flux rate of 106.47 kg C ha-1y-1. On a sub-regional basis, the annual average CH4 flux in the Tai-Lake plain soil region and alluvial plain soil region was higher than that in low mountainous and hilly soil region and polder soil region. The model simulation was conducted with two databases using polygon or county as the basic unit. 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 CH4 emissions in Tai-Lake region. However, discrepancies exist between the results from the two methods, the relative deviation is -42.10% for the entire region, and the relative deviation ranged from -19.53% to 97.30% for most counties, which indicates that the more precise soil database was necessary to better simulate CH4 emissions from rice fields in Tai-Lake region using the DNDC model.

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

2008-12-01

90

Behavior of bromobutide in paddy water and soil after application.  

PubMed

Behavior of the herbicide bromobutide, (RS)-2-bromo-N-(?,?-dimethylbenzyl)-3,3-dimethylbutyramide, in paddy water and soil after application to paddy fields was investigated to evaluate the degradation to bromobutide-debromo, N-(?,?-dimethylbenzyl)-3,3-dimethylbutyramide, and runoff of the herbicide. The respective maximum concentrations of bromobutide and the metabolite were 1,640–2,230 and 11.1–15.8 ?g/L in the paddy water, and 2,210–4,140 ?g/kg dry and 74–119 ?g/kg dry in the paddy soil, respectively. The runoff ratios of the applied bromobutide from the paddy fields were calculated as 28 ± 16%. The respective mean values of the half-lives of bromobutide in the paddy water and the soil were 2.7 ± 0.34 days and 6.9 ± 2.6 days, respectively. PMID:22297629

Morohashi, Masayuki; Nagasawa, Shunsuke; Enya, Nami; Suzuki, Kazuyuki; Kose, Tomohiro; Kawata, Kuniaki

2012-04-01

91

[Comparing the ammonia volatilization characteristic of two typical paddy soil with total wheat straw returning in Taihu Lake region].  

PubMed

An experiment using monolith lysimeter was conducted to compare the characteristic of N loss by ammonia (NH3) volatilization between the gleyed paddy soil (G soil) and hydromorphic paddy soil (H soil) the Changshu National Agro-ecological Experimental Station of the Chinese Academy of Sciences(31 degrees 33' N, 123 degrees 38' E). Three treatments were designed for each soil type, i. e. control (no urea and straw applied), nitrogen solely and nitrogen plus wheat straw. Ammonia volatilization, flood water NH4(+) -N concentration, pH and top soil Eh were measured during the rice-growing season. Results showed that the NH3 volatilization flux and cumulative N losses by NH3 volatilization from G soil were significantly higher than those from H soil, the average cumulative N losses being about 41.8 kg x hm(-2) and 11.2 kg x hm(-2), or 15.2% and 3.8% of the fertilizer N, respectively. The average N loss by NH3 volatilization during the tillering stage was the highest among the three fertilization stages, accounting for 29.4% and 8.3% of the fertilizer N for G soil and H soil, respectively. Wheat straw returning significantly increased paddy filed NH3 volatilization losses. Comparing with the sole application of fertilizer-N, the cumulative N loss by NH3 volatilization of fertilizer-N in combination with wheat straw was increased by 19.8% and 20.6% for G soil and H soil, respectively. In addition, ammonia volatilization fluxes showed a positive relationship with the flood water NH4(+) -N concentration and pH for both soils, but the relationship with top soil Eh still needs further study. PMID:23487914

Wang, Jun; Wang, De-Jian; Zhang, Gang; Wang, Yuan

2013-01-01

92

Arsenic Behavior in Paddy Fields during the Cycle of Flooded and  

E-print Network

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

93

Paddy-field contamination with 134Cs and 137Cs due to Fukushima Dai-ichi Nuclear Power Plant accident and soil-to-rice transfer coefficients.  

PubMed

The transfer coefficient (TF) from soil to rice plants of (134)Cs and (137)Cs in the form of radioactive deposition from the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident in March 2011 was investigated in three rice paddy fields in Minami-Soma City. Rice crops were planted in the following May and harvested at the end of September. Soil cores of 30-cm depth were sampled from rice-planted paddy fields to measure (134)Cs and (137)Cs radioactivity at 5-cm intervals. (134)Cs and (137)Cs radioactivity was also measured in rice ears (rice with chaff), straws and roots. The rice ears were subdivided into chaff, brown rice, polished rice and rice bran, and the (134)Cs and (137)Cs radioactivity concentration of each plant part was measured to calculate the respective TF from the soil. The TF of roots was highest at 0.48 ± 0.10 in the field where the (40)K concentration in the soil core was relatively low, in comparison with TF values of 0.31 and 0.38 in other fields. Similar trends could be found for the TF of whole rice plants, excluding roots. The TF of rice ears was relatively low at 0.019-0.026. The TF of chaff, rice bran, brown rice and polished rice was estimated to be 0.049, 0.10-0.16, 0.013-0.017 and 0.005-0.013, respectively. PMID:23103577

Endo, Satoru; Kajimoto, Tsuyoshi; Shizuma, Kiyoshi

2013-02-01

94

A comparison of isotope fractionation of carbon and hydrogen from paddy field rice roots and soil bacterial enrichments during CO 2/H 2 methanogenesis  

NASA Astrophysics Data System (ADS)

To better understand the isotope biogeochemistry of paddy field CH 4, we investigated carbon and hydrogen isotope fractionation during CO 2 reduction by a methanogenic community enriched from California paddy field soil and rice plants. Results from analyses of terminal restriction fragment length polymorphism (T-RFLP) and sequences of the archaeal small-subunit (SSU) rRNA-encoding genes (rDNA) showed a difference in methanogenic community structure between the soil (dominated by Methanobacteriaceae) and roots (dominated by Methanospirillaceae) which was essentially the same for sampling dates 15 and 99 days after flooding (DAF). CO 2/H 2 methanogenesis by these microbial communities produced CH 4 with different isotope ratios and fractionation factors (? factors). The carbon isotope ? factors in an open system with a continuous supply of 0.5% H 2 were 1.050 ± 0.002 and 1.057 ± 0.001 for soil and root enrichment cultures at 15 DAF, and 1.052 ± 0.0.002 and 1.059 ± 0.002 for soil and root enrichment cultures at 99 DAF, respectively. These ? factors are similar to, but distinct from values previously obtained from cultures of mesophilic methanogens and are larger than calculated values (1.045) for paddy soil. Fractionation of hydrogen isotopes was also studied in a closed system under 80% H 2. The difference in ? factors between soil and root enrichment cultures remained clear. The hydrogen isotope fractionations between culture water and the product CH 4 were -327 ± 14‰ and -319 ± 18‰ for soil enrichments, and -389 ± 17‰ and -382 ± 21‰ for root enrichments at 15 DAF and 99 DAF, respectively.

Chidthaisong, Amnat; Chin, Kuk-Jeong; Valentine, David L.; Tyler, Stanley C.

2002-03-01

95

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

96

Durability of Drainage Improvement by Combination of Main Drain and Trench Drains with Vertical Drains in Clayey Field Converted from Paddy to Upland Use  

NASA Astrophysics Data System (ADS)

The drainage efficiency of a subsurface drainage system for avoidance of standing water on the plow pan of clayey field was evaluated. A subsurface drainage system with a main drain and orthogonally adjoined rice husk trench drains joined by vertical rice husk drains was constructed on a test plot and compared to an identical control plot of paddy field converted to upland use under soybean cultivation. The ratio of total underdrain discharge to rainfall in the improved plot greatly increased over two years compared to that in a control plot. In the improved plot, the peak underdrain discharge per hour associated with some heavy rainfalls was around 3 mm/h in the first year but decreased to about 2 mm/h in the second year. By improving drainage in the paddy field, standing water on the plow pan was quickly eliminated after rain events and the period of flooding on the plow pan during the soybean growing season was greatly reduced. However, underdrain discharge in the improved plot decreased greatly in the third year to be at the same level as in the control plot, and rain water flooded the plow pan for extended periods of time.

Adachi, Kazuhide; Ohno, Satoshi; Furuhata, Masami; Ogura, Chikara; Tanimoto, Takeshi

97

Biotypes resistant to herbicides in paddy fields in the Iberian Peninsula.  

PubMed

A consequence of modern agriculture and its dependence on herbicides, is the appearance of resistant weed populations. The first case of resistance on the Iberian Peninsula was found in Portugal and it was in a population of Alisma plantago-aquatica, resistant to bensulfuronmethyl, an ALS-inhibitor. For the same herbicide, control problems with Cyperus difformis were found in some Spanish rice fields. In the same rice field area, tolerance was observed in some Echinochloa spp. when auxinic herbicides (quinclorac) were used and some resistant Echinochloa spp. populations were found due to the long use of PS II inhibitors herbicides (propanil). The association of active ingredients, rotation of crops and adoption of mechanical control methods are the main strategies to combat resistance to herbicides. PMID:15149134

Bakkali, Y; Ruiz-Santaella, J P; Calha, I; Rocha, F; Zaragoza, C; De Prado, R

2003-01-01

98

Syntrophic acetate oxidation under thermophilic methanogenic condition in Chinese paddy field soil.  

PubMed

The aim of the present work was to determine and compare the degradation of acetate in a Chinese rice field soil at 25°C and 50°C, respectively, and to identify specifically the active organisms involved in syntrophic acetate oxidation. Soil was preincubated anaerobically for 30 days to reduce alternative electron acceptors other than CO(2). The [2-(13)C] acetate (99% (13)C) was added twice: 0 day and 19 days after preincubation. Addition of [2-(13)C] acetate resulted in an immediate increase of (13)C labeled CH(4) but non-labeling of CO(2) at 25°C. The methanogen community was dominated by Methanosarcinaceae and Methanocellales at 25°C. In contrast, the addition of [2-(13)C] acetate at 50°C resulted in a rapid increase of (13)CO(2). The (13)C labeling of CH(4) gradually increased and reached a similar value to CO(2) (13% (13)C) at the end of incubation (40 days). Nearly all archaeal 16S rRNA genes detected at 50°C belonged to hydrogenotrophic Methanocellales. DNA-based stable isotope probing analysis revealed that the organisms related to Thermacetogenium lineage and the unclassified Thermoanaerobacteraceae group were intensively labeled with (13)C in the incubations at 50°C. Thus, acetate was converted to CH(4) and CO(2) through aceticlastic methanogenesis at 25°C, while syntrophic acetate oxidation occurred at 50°C. PMID:21470253

Rui, Junpeng; Qiu, Qiongfen; Lu, Yahai

2011-08-01

99

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

100

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

PubMed Central

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

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

2012-01-01

101

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

102

Gaseous emissions from flooded rice paddy agriculture  

NASA Astrophysics Data System (ADS)

Modification of continental land for agricultural use has increased over the last century. Atmospheric impact of this land use change has only been addressed for a few ecosystems and compounds. This paper provides, to date, the most comprehensive examination of gaseous emissions from rice paddies. We report seasonal emission ranges and integrated emission totals for 55 chemical species. This paper is the first to report emissions of isoprene, ethyl chloride, bromoform, alkyl nitrates, bromodichloromethane, hexane, and benzene from rice paddies. Emissions of alkyl nitrates, bromoform, ethyl chloride, and bromodichloromethane by terrestrial ecosystems have never before been observed. For species where emissions were observed we tentatively ascribe possible mechanisms of production; photochemical or biological production in the water column or rice plant mediated. For some compounds, during periods of maximum emissions, ambient rice paddy air concentrations may be concentrated enough to affect regional atmospheric chemistry.

Redeker, K. R.; Meinardi, S.; Blake, D.; Sass, R.

2003-07-01

103

Effect of infiltration rate on nitrogen dynamics in paddy soil after high-load nitrogen application containing 15N tracer  

Microsoft Academic Search

Flooded paddy fields perform many ecological and conservation functions and are also reported to facilitate livestock waste disposal. Paddy field infiltration rates are important for nitrogen dynamics. A laboratory study was conducted to compare the effects of infiltration rate on nitrogen dynamics including nitrogen leaching, soil adsorption, microorganism assimilation, plant uptake and denitrification. Two infiltration rates were applied to paddy

Sheng Zhou; Sho Sugawara; Shohei Riya; Masaki Sagehashi; Koki Toyota; Akihiko Terada; Masaaki Hosomi

2011-01-01

104

Endophytic Fungi from Paddy  

PubMed Central

Endophytic fungi were isolated from different parts of healthy paddy plants (Oryza sativa). The most common endophytic fungal genus recovered was Fusarium, followed by Aspergillus, Curvularia, Penicillium, Gilmaniella and Arthrobotrys foliicola. Fusarium and Curvularia had higher occurrences in the seeds compared with the other fungi. Aspergillus was recovered mostly from leaf blades and Penicillium from the leaf sheath. Gilmaniella and A. foliicola were isolated only from the roots and leaf blade, respectively. The assemblage of endophytic fungi in healthy tissues of paddy plants may indicate that some of the fungi are possible latent pathogens and some may become saprophytic. PMID:24575194

Zakaria, Latiffah; Yaakop, Amira Suriaty; Salleh, Baharuddin; Zakaria, Maziah

2010-01-01

105

Study of Dynamics of Floodwater Nitrogen and Regulation of Its Runoff Loss in Paddy Field-Based Two-Cropping Rice with Urea and Controlled Release Nitrogen Fertilizer Application  

Microsoft Academic Search

The article deals with the effects of urea and controlled release nitrogen fertilizer (CRNF) on dynamics of pH, electronic conductivity (EC), total nitrogen (TN), NH4+-N and NO3?-N in floodwater, and the regulation of runoff TN loss from paddy field-based two-cropping rice in Dongting Lake, China, and probes the best fertilization management for controlling N loss. Studies were conducted through modeling

JI Xiong-hui; ZHENG Sheng-xian; LU Yan-hong; LIAO Yu-lin

2007-01-01

106

Comparison of generalist predators in winter-flooded and conventionally managed rice paddies and identification of their limiting factors.  

PubMed

Winter-flooding of rice paddies without the application of agricultural chemicals is attracting attention as a new agricultural method for enhancing the habitat conditions of wintering waterfowl in rice paddy ecosystems throughout Japan and east Asia. Conditions in these paddies are expected to result in restoration of not only the winter habitats of waterfowl but also those of other taxonomic groups during the rice growing season. In this study, we tested whether the diversity of summer spiders--ubiquitous predators in rice paddies--was higher in the winter-flooded paddies than in the conventional ones by conducting field measurements in 31 winter-flooded and 7 conventional paddies. Limiting factors of spiders in the winter-flooded paddies were then examined. Results revealed that both the density and species richness of spiders were significantly higher in the winter-flooded paddies than in the conventional ones both before and after the insecticide application against pecky rice bug Stenotus rubrovittatus (Matsumura)(Hemiptera: Miridae) to conventional paddies. In addition, spider density and species richness in the winter-flooded paddies correlated with the availability of two prey groups--chironomids and other nematocera. These findings suggest that in the winter-flooded paddies the diversity of generalist predators is higher than in the conventional ones during the rice-growing season and that the combination of management at both the landscape and field level is likely more effective for increasing spider abundance in winter-flooded paddies. PMID:25140294

Takada, Mayura B; Takagi, Shun; Iwabuchi, Shigeki; Mineta, Takuya; Washitani, Izumi

2014-01-01

107

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

108

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

109

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

110

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

111

Effects of elevated ozone concentration on CH4 and N2 O emission from paddy soil under fully open-air field conditions.  

PubMed

We investigated the effects of elevated ozone concentration (E-O3 ) on CH4 and N2 O emission from paddies with two rice cultivars: an inbred Indica cultivar Yangdao 6 (YD6) and a hybrid one II-you 084 (IIY084), under fully open-air field conditions in China. A mean 26.7% enhancement of ozone concentration above the ambient level (A-O3 ) significantly reduced CH4 emission at tillering and flowering stages leading to a reduction of seasonal integral CH4 emission by 29.6% on average across the two cultivars. The reduced CH4 emission is associated with O3 -induced reduction in the whole-plant biomass (-13.2%), root biomass (-34.7%) and maximum tiller number (-10.3%), all of which curbed the carbon supply for below-ground CH4 production and its release from submerged soil to atmosphere. Although no significant difference was detected between the cultivars in the CH4 emission response to E-O3 , a larger decrease in CH4 emission with IIY084 (-33.2%) than that with YD6 (-7.0%) was observed at tillering stage, which may be due to the larger reduction in tiller number in IIY084 by E-O3 . Additionally, E-O3 reduced seasonal mean NOx flux by 5.7% and 11.8% with IIY084 and YD6, respectively, but the effects were not significant statistically. We found that the relative response of CH4 emission to E-O3 was not significantly different from those reported in open-top chamber experiments. This study has thus confirmed that increasing ozone concentration would mitigate the global warming potential of CH4 , and suggested consideration of the feedback mechanism between ozone and its precursor emission into the projection of future ozone effects on terrestrial ecosystem. This article is protected by copyright. All rights reserved. PMID:25403809

Tang, Haoye; Liu, Gang; Zhu, Jianguo; Kobayashi, Kazuhiko

2014-11-18

112

The rice REDUCED CULM NUMBER11 gene controls vegetative growth under low-temperature conditions in paddy fields independent of RCN1/OsABCG5.  

PubMed

Low temperature tolerance during vegetative growth is an important objective in rice (Oryza sativa L.) breeding programs. We isolated a novel reduced culm number mutant, designated reduced culm number11 (rcn11), by screening under low-temperature condition in a paddy fields. Since the shoot architecture of the rcn11 was very similar to that of the rcn1, we examined whether RCN11 is involved in RCN1/OsABCG5-associated vegetative growth control. The rcn11 mutant has no mutation in the RCN1/OsABCG5 gene and rcn11 has no effect on RCN1/OsABCG5 gene expression. In the rcn1 mutant, RCN1/OsABCG5 was upregulated showing that RCN1/OsABCG5 is controlled by negative feedback regulation. Absence of an effect of rcn11 on RCN1/OsABCG5 feedback regulation supported that RCN11 is not involved in the RCN1/OsABCG5-associated transport system. A genetic allelism test and molecular mapping study showed that rcn11 is independent of rcn1 on rice chromosome 3 and located on chromosome 8. The rcn1 rcn11 phenotype suggests that RCN11 acts on vegetative growth independent of RCN1/OsABCG5. A root development comparison between rcn1 and rcn11 in young seedlings represented that rcn11 reduced crown root number and elongation, whereas rcn1 reduced lateral root density and elongation. Thus, rcn11 will shed new light on vegetative growth control under low temperature. PMID:23987813

Funabiki, Atsushi; Takano, Sho; Matsuda, Shuichi; Tokuji, Yoshihiko; Takamure, Itsuro; Kato, Kiyoaki

2013-10-01

113

Irrigation and Drainage Components in a Paddy Plot with Fish Ladder  

NASA Astrophysics Data System (ADS)

There is few research examples in which the comprehensive water management in the paddy plot with a fish ladder, which connects paddy ponding water and a drainage canal and has a function of run of fishes, is examined considering the water budget in a paddy plot. Hence, the fish habitat and the water budget components were investigated in the paddy plot with a fish ladder. We considered the effects of water management for the enhancement of the fish conservation function of paddy fields on the water budget in a paddy plot. As a result, the increase of the lot management water requirement by the increases of irrigation and runoff drainage induced the expansion of opportunity running from the drainage canal and entering from the irrigation canal and enhanced fish habitat in a paddy plot. The water management for the enhancement of fish habitat, by which the ponding depth is kept at the height of a flashboard set up at the outlet of a paddy plot, will require 1.3-fold irrigation water and yield 1.6-fold drainage water as much as the conventional water management, as an example. Furthermore, we discussed the necessity for a new concept of irrigation and drainage components under the paddy water management considering the fish habitat conservation.

Nakamura, Kimihito; Fukami, Aya; Horino, Haruhiko; Nakagiri, Takao; Sakata, Satoshi

114

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

115

Influence of paddy and corn in different rotations on wheat yield, nutrient removal and soil properties  

Microsoft Academic Search

Summary In a 3 year field study, the effect of two rotations, paddy (Oryza sativa L.), wheat (Triticum aestivum L.), mung (Phaseolus aureus L.) and corn (Zea mays L.), wheat (Triticum aestivum L.), mung (Phaseolus aureus L.) on wheat yield and chemical, physical and biological properties of soil was evaluated. Grain yield of the wheat sown after paddy during 1972–73,

O. P. Meelu; Viraj Beri; K. N. Sharma; S. K. Jalota; B. S. Sandhu

1979-01-01

116

Pendimethalin in surface waters of rivers in the proximity of irrigated paddy fields by solid phase microextraction and gas chromatography  

Microsoft Academic Search

The aim of this study was to develop an analytical methodology for the determination of the herbicide pendimethalin in river waters in the towns of Turvo and Meleiro in the southern region of Santa Catarina State, Brazil. The method, based on solid phase microextraction (SPME) followed by separation and detection by gas chromatography (GC) and electron capture detection (ECD), respectively,

Léa L. Freitas; Ernani S. Sant’Anna; Eliane A. Suchara; Vanira S. Benato; Eduardo Carasek

2011-01-01

117

Pendimethalin in surface waters of rivers in the proximity of irrigated paddy fields by solid phase microextraction and gas chromatography  

Microsoft Academic Search

The aim of this study was to develop an analytical methodology for the determination of the herbicide pendimethalin in river waters in the towns of Turvo and Meleiro in the southern region of Santa Catarina State, Brazil. The method, based on solid phase microextraction (SPME) followed by separation and detection by gas chromatography (GC) and electron capture detection (ECD), respectively,

Léa L. Freitas; Ernani S. Sant’Anna; Eliane A. Suchara; Vanira S. Benato; Eduardo Carasek

2012-01-01

118

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

119

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

120

21 CFR 882.4700 - Neurosurgical paddie.  

Code of Federal Regulations, 2010 CFR

...Neurosurgical paddie. (a) A neurosurgical paddie is a pad used during surgery to protect nervous tissue, absorb fluids, or stop bleeding. (b) Classification. Class II (performance standards). [44 FR 51730-51778, Sept. 4, 1979, as amended...

2010-04-01

121

21 CFR 882.4700 - Neurosurgical paddie.  

Code of Federal Regulations, 2013 CFR

...Neurosurgical paddie. (a) A neurosurgical paddie is a pad used during surgery to protect nervous tissue, absorb fluids, or stop bleeding. (b) Classification. Class II (performance standards). [44 FR 51730, Sept. 4, 1979, as amended at 69 FR...

2013-04-01

122

21 CFR 882.4700 - Neurosurgical paddie.  

Code of Federal Regulations, 2012 CFR

...Neurosurgical paddie. (a) A neurosurgical paddie is a pad used during surgery to protect nervous tissue, absorb fluids, or stop bleeding. (b) Classification. Class II (performance standards). [44 FR 51730-51778, Sept. 4, 1979, as amended...

2012-04-01

123

21 CFR 882.4700 - Neurosurgical paddie.  

Code of Federal Regulations, 2014 CFR

...Neurosurgical paddie. (a) A neurosurgical paddie is a pad used during surgery to protect nervous tissue, absorb fluids, or stop bleeding. (b) Classification. Class II (performance standards). [44 FR 51730, Sept. 4, 1979, as amended at 69 FR...

2014-04-01

124

21 CFR 882.4700 - Neurosurgical paddie.  

Code of Federal Regulations, 2011 CFR

...Neurosurgical paddie. (a) A neurosurgical paddie is a pad used during surgery to protect nervous tissue, absorb fluids, or stop bleeding. (b) Classification. Class II (performance standards). [44 FR 51730-51778, Sept. 4, 1979, as amended...

2011-04-01

125

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

PubMed Central

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

Yang, Shihong; Wei, Qi; Gao, Xiaoli

2013-01-01

126

Global warming potential of emissions from rice paddies in Northeastern China  

Microsoft Academic Search

In this study, paddy fields in Jilin province which are flooded parcel of arable lands used for growing rice (Oryza sativa Linn.) were selected as the object. Long-term exploitation of paddy fields led to variations of soil organic carbon (SOC) and green\\u000a house gases (GHGs) emissions which might contribute to global warming. In order to calculate the amount of global

Xiaoming Xu; Jie Tang; Zhaoyang Li; Chang Liu; Weizheng Han

2011-01-01

127

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

128

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

Microsoft Academic Search

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,

Nobuhisa Koga; Ryosuke Tajima

2011-01-01

129

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

130

Microbial lipids in Paddy Soils of the Yangtze Area  

NASA Astrophysics Data System (ADS)

Geobiochemical studies of rice paddy soils and their effect on the global carbon cycle are of paramount importance. Paddy soils comprise manmade wetlands because soil flooding is a prerequisite for lowland rice cultivation. Except for sulphate-rich substrates, rice growth is not very sensitive to soil conditions prevailing prior to conversion of marine tidal flat sediments to paddy cultivation. Thus, soil management practices, such as artificial submergence or drainage, ploughing and puddling (i.e. ploughing a submerged soil), manuring, liming, and fertilization, are the major driving factors of paddy soil development. Soil organic matter (SOM) decomposition and humification proceeds in hydromorphic soils at a slower rate than in well-drained, aerated soils. Rice paddy soils thus also represent a suitable model system to study fundamental aspects of redox sensitive soil processes. These processes are of special interest because in flooded rice fields the anaerobic fermentation of SOM leads to the release of methane and to denitrification losses of inorganic nitrogen. 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. We here describe the biomarker geochemistry of six paddy soils that developed on marine tidal sediments and where cultivation started 50, 100, 300, 700, 1000 or 2000 years before present. As reference substrates recent marine and lacustrine sediments were selected. The differentiation of the lipid biomass was achieved by investigating glycerol dialkyl glycerol tetraethers (GDGT). These specific organic geochemical biomarkers allow for determining the abundance of fossil microbial consortia (archaea and bacteria input) into paddy soils, justified by the diversity of the archaeal and bacterial cell membrane constituents. The dominant proportion of the GDGT in soils and in the lacustrine sediment derived from bacterial branched isoalkane tetraethers (BIT) as described previously for dry-land soils [1]. Only the marine sediment contained significant amounts of isoprenoidal GDGT originating from eury- and crenarchaeota. This result contradicted our expectation that methanogenic euryarchaeota thriving in paddy soils should lead to high abundances of isoprenoidal GDGT, in particular calarchaeol. Additionally we compared concentration of isoprenoidal GDGT cell membrane lipids with the number of ammonia monooxygenase gene copies from ammonia-oxidizing archaea and bacteria (AOA and AOB amoA) determinated by phylogenetic analysis. Concentration of the isoprenoidal tetraether lipid crenarchaeol (ng per g of soil) correlated with the abundance of archaeal amoA gene copies (copies per g of soil). This agrees with a dominance of ammonia-oxidizing archaea (AOA) over ammonia-oxidizing bacteria (AOB) in paddy soil nitrification as previously shown for a variety of terrestrial soil types [2]. The distribution patterns of GDGTs revealed that microbial lipids have been converted from marine to paddy signatures within a period of only 50 years. [1] Weijers J.W.H., et al. (2007) Geochim. Cosmochim. Acta 71, 703-71 [2] Leininger S., et al. (2006) Nature 442, 806-809

Mueller-Niggemann, Cornelia; Bannert, Andrea; Schloter, Michael; Cao, Zhihong; Schwark, Lorenz

2010-05-01

131

Quantifying methane emissions from rice paddies in Northeast China by integrating remote sensing mapping with a biogeochemical model  

NASA Astrophysics Data System (ADS)

The Sanjiang Plain located in Northeastern China is one of the major rice producing regions in the country. However, differing from the majority rice regions in Southern China, the Sanjinag Plain possesses a much cooler weather. Could the rice paddies in this domain be an important source of global methane? To answer this question, we calculated methane (CH4) emissions from the region by integrating remote sensing mapping with a process-based biogeochemistry model, Denitrification and Decomposition or DNDC. To quantify regional CH4 emissions from the plain, we first tested the model against a two-year dataset of CH4 fluxes measured at a typical rice field within the domian. A sensitivity test was conducted to find out the most sensitive factors affecting CH4 emissions in the region. Based on the understanding gained from the validation and sensitivity tests, a geographic information system (GIS) database was constructed to hold the spatially differentiated input information to drive DNDC for its regional simulations. The GIS database included a rice map derived from the Landsat TM images, which provided crucial information about the spatial distribution of the rice fields within the domain of 10.93 million hectares. The modeled results showed that the total 1.44 million ha of rice paddies in the plain emitted 0.43-0.58 Tg CH4-C per year with spatially differentiated annual emission rates ranging between 100-800 kg CH4-C/ha, which are comparable with that observed in Southern China. The modeled data indicated that the high SOC contents, long crop season and high rice biomass enhanced CH4 production in the cool paddies. The modeled results proved that the northern wetland agroecosystems could make important contributions to global greenhouse gas inventory.

Zhang, Y.; Wang, Y. Y.; Su, S. L.; Li, C. S.

2011-01-01

132

Quantifying methane emissions from rice paddies in Northeast China by integrating remote sensing mapping with a biogeochemical model  

NASA Astrophysics Data System (ADS)

The Sanjiang Plain located in Northeastern China is one of the major rice producing regions in the country. However, differing from the majority rice regions in Southern China, the Sanjinag Plain possesses a much cooler climate. Could the rice paddies in this domain be an important source of global methane? To answer this question, methane (CH4) emissions from the region were calculated by integrating remote sensing mapping with a process-based biogeochemistry model, Denitrification and Decomposition or DNDC. To quantify regional CH4 emissions from the plain, the model was first tested against a two-year dataset of CH4 fluxes measured at a typical rice field within the domain. A sensitivity test was conducted to find out the most sensitive factors affecting CH4 emissions in the region. Based on the understanding gained from the validation and sensitivity tests, a geographic information system (GIS) database was constructed to hold the spatially differentiated input information to drive DNDC for its regional simulations. The GIS database included a rice map derived from the Landsat TM images acquired in 2006, which provided crucial information about the spatial distribution of the rice fields within the domain of 10.93 million ha. The modeled results showed that the total 1.44 million ha of rice paddies in the plain emitted 0.48-0.58 Tg CH4-C in 2006 with spatially differentiated annual emission rates ranging between 38.6-943.9 kg CH4-C ha-1, which are comparable with that observed in Southern China. The modeled data indicated that the high SOC contents, long crop season and high rice biomass enhanced CH4 production in the cool paddies. The modeled results proved that the northern wetland agroecosystems could make important contributions to global greenhouse gas inventory.

Zhang, Y.; Wang, Y. Y.; Su, S. L.; Li, C. S.

2011-05-01

133

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

PubMed

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

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

2014-12-01

134

Magnetic field strength of active region filaments  

NASA Astrophysics Data System (ADS)

Aims: We study the vector magnetic field of a filament observed over a compact active region neutral line. Methods: Spectropolarimetric data acquired with TIP-II (VTT, Tenerife, Spain) of the 10 830 Å spectral region provide full Stokes vectors that were analyzed using three different methods: magnetograph analysis, Milne-Eddington inversions, and PCA-based atomic polarization inversions. Results: The inferred magnetic field strengths in the filament are around 600-700 G by all these three methods. Longitudinal fields are found in the range of 100-200 G whereas the transverse components become dominant, with fields as high as 500-600 G. We find strong transverse fields near the neutral line also at photospheric levels. Conclusions: Our analysis indicates that strong (higher than 500 G, but below kG) transverse magnetic fields are present in active region filaments. This corresponds to the highest field strengths reliably measured in these structures. The profiles of the helium 10 830 Å lines observed in this active region filament are dominated by the Zeeman effect.

Kuckein, C.; Centeno, R.; Martínez Pillet, V.; Casini, R.; Manso Sainz, R.; Shimizu, T.

2009-07-01

135

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

136

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

PubMed Central

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

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

2012-01-01

137

[Simulation of methane emissions from rice fields in the Taihu Lake region, China by using different unit of soil database with the DNDC model].  

PubMed

Application of a biogeochemical model, DeNitrification and DeComposition or DNDC, was discussed to assess the impact of CH4 emissions on different soil database from rice fields in Taihu Lake region of China. The results showed that CH4 emissions of the polygon-based soil database of 1:50000, which contained 52034 polygons of paddy soils representing 1107 paddy soil profiles extracted from the latest national soil map (1:50000), were located within the ranges produced by the county-based soil database of 1:50000. However, total emissions of the whole area differed by about 1680 Gg CH4-C. Moreover, CH4 emissions of the polygon-based soil database of 1:50000 and the county-based soil database of 14,000,000, which was the most popular data source when DNDC model was applied in China, have a big estimation discrepancy among each county-based unit in spite of total emissions of the whole area by a difference of 180 Gg CH4-C. This indicated that the more precise soil database was necessary to better simulate CH4 emissions from rice fields in Taihu Lake region using the DNDC model. PMID:19799272

Zhang, Li-ming; Yu, Dong-sheng; Shi, Xue-zheng; Zhao, Li-min; Ding, Wei-xin; Wang, Hong-jie; Pan, Jian-jun

2009-08-15

138

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

139

Application of Hybrid Pattern Recognition for Discriminating Paddy Seeds of Different Storage Periods Based on Vis\\/NIRS  

Microsoft Academic Search

Hybrid pattern recognition was put forward to discriminate paddy seeds of four different storage periods based on visible\\/near\\u000a infrared reflectance spectroscopy (Vis\\/NIRS). The hybrid pattern recognition included extracting feature and building classifier.\\u000a A total of 210 samples of paddy seeds, which belonged to four classes, were used for collecting Vis\\/NIR spectra (325-1075\\u000a nm) using a field spectroradiometer. The hybrid pattern

Li Xiaoli; Cao Fang; He Yong

2007-01-01

140

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, Álvaro R B; Rádis-Baptista, Gandhi; Yamane, Tetsuo; Kikuchi, Jun

2014-01-01

141

Biogeochemical cycling of C, N, and water in paddy rice agriculture in Monsoon Asia  

NASA Astrophysics Data System (ADS)

We report latest results of an ongoing project to evaluate the biogeochemical cycling of C, N, and water in paddy rice agriculture in Monsoon Asia. The core project focus is application of the DNDC biogeochemical model to estimate greenhouse gas emissions from paddy rice, and possible impacts of changes in agricultural management on those emissions. Simulations are done at the scale of sub-national political units (county equivalents and/or provinces/states). One effort has been to develop geospatial input data sets of agricultural land use and management, including crop rotations, cropping intensity, water management (irrigated or rainfed), fertilizer use. We have worked with both statistical census data and MODIS space-borne remote sensing data to map paddy rice across the domain. A second effort has been model development for application to rainfed paddy agriculture, and model testing against field data from paddy sites in India. The final thrust is model application across the domain to estimate water use, crop yield, net C-sequestration in soils, and emissions of methane and nitrous oxide.

Frolking, S.; Li, C.; Xiao, X.; Babu, J. Y.; Boles, S.; Salas, W.

2006-05-01

142

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

NASA Technical Reports Server (NTRS)

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

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

2010-01-01

143

[Effects of long-term manure and crop residues incorporation on yield and phosphorus saturation in a paddy soil].  

PubMed

An 8-year field experiment was conducted in the Taihu Lake region of eastern China to investigate the effects of incorporation of straw and manure on the yield and phosphorus (P) accumulation in the paddy soil, and to evaluate the potential risk of P loss from soil to environment. The experiment had four fertilization treatments, i. e., chemical fertilizers alone (NPK), chemical fertilizers plus rice/wheat straw (NPK + S), chemical fertilizers plus 7.5 t x (hm2 x a)(-1) wet pig manure (NPK + M7.5), and chemical fertilizers plus 15.0 t x (hm2 x a)(-1) wet pig manure (NPK + M15). Among the four treatments, no significant differences were observed in the yield of rice or wheat. Long-term application of chemical fertilizers plus pig manure significantly increased the soil total P, the degree of P saturation (DPS), and the concentration of extractable P forms, including Olsen-P, Mehlich 3 extractable P, CaCl2 extractable P, and water extractable P, which became a potential source of eutrophication in Taihu Lake. In contrast to chemical fertilizers plus pig manure, there were no significant differences in the concentrations of extractable P forms between the NPK + S and NPK treatments. We concludes that chemical fertilizers [P 45 kg x (hm2 x a)(-1)] plus rice/wheat straw should be recommended in the paddy soil in the Taihu Lake region under the rice-wheat rotation system. PMID:24191569

Yan, Xiao; Wang, De-Jian; Zhang, Gang; Ran, Jing; Zheng, Ji-Cheng

2013-08-01

144

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

145

Carbon Dioxide Flux from Rice Paddy Soils in Central China: Effects of Intermittent Flooding and Draining Cycles  

PubMed Central

A field experiment was conducted to (i) examine the diurnal and seasonal soil carbon dioxide (CO2) fluxes pattern in rice paddy fields in central China and (ii) assess the role of floodwater in controlling the emissions of CO2 from soil and floodwater in intermittently draining rice paddy soil. The soil CO2 flux rates ranged from ?0.45 to 8.62 µmol.m?2.s?1 during the rice-growing season. The net effluxes of CO2 from the paddy soil were lower when the paddy was flooded than when it was drained. The CO2 emissions for the drained conditions showed distinct diurnal variation with a maximum efflux observed in the afternoon. When the paddy was flooded, daytime soil CO2 fluxes reversed with a peak negative efflux just after midday. In draining/flooding alternating periods, a sudden pulse-like event of rapidly increasing CO2 efflux occured in response to re-flooding after draining. Correlation analysis showed a negative relation between soil CO2 flux and temperature under flooded conditions, but a positive relation was found under drained conditions. The results showed that draining and flooding cycles play a vital role in controlling CO2 emissions from paddy soils. PMID:23437170

Liu, Yi; Wan, Kai-yuan; Tao, Yong; Li, Zhi-guo; Zhang, Guo-shi; Li, Shuang-lai; Chen, Fang

2013-01-01

146

Vector Magnetic Field in Emerging Flux Regions  

NASA Astrophysics Data System (ADS)

A crucial phase in magnetic flux emergence is the rise of magnetic flux tubes through the solar photosphere, which represents a severe transition between the very different environments of the solar interior and corona. Multi-wavelength observations with Flare Genesis, TRACE, SoHO, and more recently with the vector magnetographs at THEMIS and Hida (DST) led to the following conclusions. The fragmented magnetic field in the emergence region - with dipped field lines or bald patches - is directly related with Ellerman bombs, arch filament systems, and overlying coronal loops. Measurements of vector magnetic fields have given evidence that undulating "serpentine" fields are present while magnetic flux tubes cross the photosphere. See the sketch below, and for more detail see Pariat et al. (2004, 2007); Watanabe et al. (2008):

Schmieder, B.; Pariat, E.

147

Complex magnetic fields in an active region  

NASA Astrophysics Data System (ADS)

High-resolution observations of the full Stokes vector in Fe\\sc i spectral lines around 5250 Angstroms obtained at the Swedish Vacuum Solar Telescope on La Palma with the ZIMPOL I Stokes polarimeter in a complex active region reveal the presence of anomalously shaped Stokes profiles indicating the coexistence of at least two magnetic components within the same spatial resolution element. These Stokes profiles have been analyzed with an inversion code based on a 3-component atmospheric model with two magnetic and one field-free component. The fits to the observations in a magnetic region that resembles a small penumbra reveal the presence of a horizontal magnetic field component with an average field strength of /line{B}=840 G, a mean filling factor of /line?=0.12, and an average temperature /line{T}=5400 K at log {tau_ {5000}}=-1.5 embedded in the main ``penumbral'' magnetic field that has /line{B}=1500 G, /line?=0.56, and /line{T}=4900 K. The horizontal component exhibits a mean outflow of 2.7 km s(-1) which is mainly due to the Evershed flow. In a region where there are strong downflows up to 7 km s(-1) , we infer the possible presence of a shock front whose height changes along the slit. The height variation can be explained by a change of the gas pressure at the base of the photosphere below the shock front as proposed by Thomas & Montesinos (1991). Small plages with field strengths below 900 G have been observed in the vicinity of some pores. Finally, we present a puzzling field structure at the boundary between two adjacent pores. Ambiguous results suggest that although the inversion code is able to successfully invert even very complex Stokes profiles, we are far from a complete description of the field structure in complex magnetic regions. We warn that magnetograms and fits to data involving only a single magnetic component may hide the true complexity of the magnetic structure in at least some parts of active regions.

Bernasconi, P. N.; Keller, C. U.; Solanki, S. K.; Stenflo, J. O.

1998-01-01

148

Microbial communities responsible for the decomposition of rice straw compost in a Japanese rice paddy field determined by phospholipid fatty acid (PLFA) analysis  

Microsoft Academic Search

To identify the microbial communities responsible for the decomposition of rice straw compost in soil during the rice cultivation period, phospholipid fatty acid (PLFA) composition of rice straw compost was determined by periodically sampling the compost from a Japanese rice field under flooded conditions. About 21% of the compost was decomposed within a period of 3 months. The total amount

Takanori Tanahashi; Jun Murase; Kazuo Matsuya; Susumu Asakawa; Makoto Kimura

2004-01-01

149

Geoid for Austria - Regional gravity FIELD improved  

NASA Astrophysics Data System (ADS)

The project 'Geoid for Austria - Regional gravity FIELD improved' (GARFIELD) is a current initiative for the generation of a new high-quality gravity field solution for the Austrian region, which overcomes the inconsistencies between previous geoid solutions and geoid heights from GPS/leveling campaigns. The optimum combination of the complementary data types of satellite observations and all available terrestrial gravity field measurements in Austria and neighbouring countries will be essential. The Least Squares Collocation (LSC) approach will serve as reference method for the gravity field computation. In this context, GOCE gradients should be used as in-situ observations. Alternatively to LSC, a Gauss-Markov model with parametrization as Radial Basis Functions will be implemented. For a successful data combination, the Remove-Compute-Restore technique will be revised to avoid a double consideration of the topographic masses when performing long- and short-wavelength signal reductions. This contribution should give an overview about methods, developments and the current status of the project GARFIELD.

Rieser, Daniel; Pock, Christian; Mayer-Gürr, Torsten; Kühtreiber, Norbert

2013-04-01

150

Soil amendments and cultivar selection can improve rice yield in salt-influenced (tsunami-affected) paddy fields in Sri Lanka.  

PubMed

The tsunami disaster in the Indian Ocean in December 2004 caused devastation of agricultural soils by salt water over wide areas. Many rice fields located close to the coast were affected by the flood of seawater. Electric conductivity (EC) of soils in tsunami-affected rice fields was found to be higher compared to unaffected fields 2 years after the tsunami. Four soil amendments (gypsum, dolomite, cinnamon ash and rice-husk-charcoal) were tested for their influence on improving the yield parameters of rice grown in a tsunami-affected and a non-affected area. Yield parameters were compared with an untreated control of the same cultivar (AT362) and with a salt resistant rice variety (AT354). The salt resistant variety had the highest grain yield. The two amendments gypsum and rice-husk-charcoal led to an increase in grain yield compared to the untreated control, whereas dolomite and cinnamon ash had no significant effect on grain yield. PMID:19255858

Reichenauer, Thomas G; Panamulla, Sunil; Subasinghe, Siripala; Wimmer, Bernhard

2009-10-01

151

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

152

Radiocesium sorption in relation to clay mineralogy of paddy soils in Fukushima, Japan.  

PubMed

Relationships between Radiocesium Interception Potential (RIP) and mineralogical characteristics of the clay fraction isolated from 97 paddy soils (Hama-dori, n = 25; Naka-dori, n = 36; Aizu, n = 36) in Fukushima Prefecture, Japan were investigated to clarify the mineralogical factors controlling the (137)Cs retention ability of soils (half-life 30.1 y). Of all the fission products released by the Fukushima accident, (137)Cs is the most important long-term contributor to the environmental contamination. The RIP, a quantitative index of the (137)Cs retention ability, was determined for the soil clays. The composition of clay minerals in the soil clays was estimated from peak areas obtained using X-ray diffraction (XRD) analyses. The predominant clay mineral was smectite in soils from Hama-dori and Aizu, while this was variable for those from Naka-dori. Native K content of the soil clays was found to be an indicator of the amount of micaceous minerals. The average RIP for the 97 soil clays was 7.8 mol kg(-1), and ranged from 2.4 mol kg(-1) to 19.4 mol kg(-1). The RIP was significantly and positively correlated with native K content for each of the geographical regions, Hama-dori (r = 0.76, p < 0.001), Naka-dori (r = 0.43, p < 0.05), and Aizu (r = 0.76, P < 0.001), while it was not related to the relative abundance of smectite. The linear relationship between RIP and native K content not only indicate a large contribution of micaceous minerals to the (137)Cs retention ability of the soil clays, but also could be used to predict the (137)Cs retention ability of soil clays for other paddy fields in Fukushima and other areas. PMID:24055668

Nakao, Atsushi; Ogasawara, Sho; Sano, Oki; Ito, Toyoaki; Yanai, Junta

2014-01-15

153

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

154

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

155

Gaseous emissions from flooded rice paddy agriculture  

Microsoft Academic Search

Modification of continental land for agricultural use has increased over the last century. Atmospheric impact of this land use change has only been addressed for a few ecosystems and compounds. This paper provides, to date, the most comprehensive examination of gaseous emissions from rice paddies. We report seasonal emission ranges and integrated emission totals for 55 chemical species. This paper

K. R. Redeker; S. Meinardi; D. Blake; R. Sass

2003-01-01

156

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

157

Effect of Drying on Heavy Metal Fraction Distribution in Rice Paddy Soil  

PubMed Central

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

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

2014-01-01

158

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

159

Modeling the effect of rainfall intensity on soil-water nutrient exchange in flooded rice paddies and implications for nitrate fertilizer runoff to the Oita River in Japan  

NASA Astrophysics Data System (ADS)

paper examines the effect of rainfall intensity on nutrient exchange at the soil-water interface of rice paddy fields and the implications to nitrate runoff to the Oita River. The Oita River Basin on Kyushu Island in Japan covers 650 km2 of which 11% are used for agriculture (rice). During the monsoon season in June/July, the heavily fertilized paddy fields are flooded and large amounts of NO3-N are discharged to the Oita River. A model has been developed for the NO3-N release in the rice paddy fields. The model focuses on the effect of rainfall intensity. It assumes that in addition to increased surface runoff and infiltration, the monsoon rain enhances pore water flow and causes nitrate release from the soil by dynamic pressure fluctuations at the soil/water interface. The magnitude of NO3-N release from paddy fields is described by the simulated soil/water exchange velocity (W) which increases with rising rainfall intensity and hydraulic conductivity, and is on the order of 10-2 to 10-6 cm/s. When the river flow rises due to precipitation (monsoon), the NO3-N load rises almost proportionately to the river discharge, and with little delay. Measured unit NO3-N loads in the Oita River per day and m2 of paddy fields were nearly proportional to precipitation intensity R (R1.042) and so were modeled unit NO3-N release rates in the paddy fields (R1.095). This result suggests that raindrop-induced pumping is an important if not crucial process that enhances NO3-N runoff from rice paddy fields. An implication is that the nutrient loading of surface water bodies may grow as the occurrence of extreme rainfall events increases with climate change.

Higashino, Makoto; Stefan, Heinz G.

2014-11-01

160

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...

161

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  

Microsoft Academic Search

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

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

2009-01-01

162

Origin and properties of humus in the subsoil of irrigated rice paddies  

Microsoft Academic Search

To examine the effect of downward percolation of flooding water under reduced soil conditions on the binding type of humus in the plow layer soil of paddy fields, a model experiment was conducted. Changes in the binding type of humus were analyzed by successive extraction of humus with water, 0.25 m Na2SO4, 0.1 m Na4P207 (pH 7.0), 0.1 m Na4P207

Nagamitsu Maie; Akira Watanabe; Makoto Kimura

2001-01-01

163

Technical Inefficiency Effects Among Paddy Farmers in the Villages of the ‘Office du Niger’, Mali, West Africa  

Microsoft Academic Search

A stochastic frontier production function incorporating a model for technical inefficiency effects (Battese and Coelli, 1995) is applied to field data on paddy farmers from 29 villages in the ‘Office du Niger’ in Mali. Four ‘conventional factors’ (land, labor, fertilizer and machinery) are considered as inputs of production. The technical inefficiency effects in the stochastic frontier were related to firm-specific

Martine Audibert; F. Mitterrand

1997-01-01

164

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

165

Identification and isolation of active N2O reducers in rice paddy soil  

PubMed Central

Dissolved N2O is occasionally detected in surface and ground water in rice paddy fields, whereas little or no N2O is emitted to the atmosphere above these fields. This indicates the occurrence of N2O reduction in rice paddy fields; however, identity of the N2O reducers is largely unknown. In this study, we employed both culture-dependent and culture-independent approaches to identify N2O reducers in rice paddy soil. In a soil microcosm, N2O and succinate were added as the electron acceptor and donor, respectively, for N2O reduction. For the stable isotope probing (SIP) experiment, 13C-labeled succinate was used to identify succinate-assimilating microbes under N2O-reducing conditions. DNA was extracted 24?h after incubation, and heavy and light DNA fractions were separated by density gradient ultracentrifugation. Denaturing gradient gel electrophoresis and clone library analysis targeting the 16S rRNA and the N2O reductase gene were performed. For culture-dependent analysis, the microbes that elongated under N2O-reducing conditions in the presence of cell-division inhibitors were individually captured by a micromanipulator and transferred to a low-nutrient medium. The N2O-reducing ability of these strains was examined by gas chromatography/mass spectrometry. Results of the SIP analysis suggested that Burkholderiales and Rhodospirillales bacteria dominated the population under N2O-reducing conditions, in contrast to the control sample (soil incubated with only 13C-succinate). Results of the single-cell isolation technique also indicated that the majority of the N2O-reducing strains belonged to the genera Herbaspirillum (Burkholderiales) and Azospirillum (Rhodospirillales). In addition, Herbaspirillum strains reduced N2O faster than Azospirillum strains. These results suggest that Herbaspirillum spp. may have an important role in N2O reduction in rice paddy soils. PMID:21677691

Ishii, Satoshi; Ohno, Hiroki; Tsuboi, Masahiro; Otsuka, Shigeto; Senoo, Keishi

2011-01-01

166

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

167

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

NASA Technical Reports Server (NTRS)

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

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

1981-01-01

168

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...

169

Differential contributions of ammonia oxidizers and nitrite oxidizers to nitrification in four paddy soils.  

PubMed

Rice paddy fields are characterized by regular flooding and nitrogen fertilization, but the functional importance of aerobic ammonia oxidizers and nitrite oxidizers under unique agricultural management is poorly understood. In this study, we report the differential contributions of ammonia-oxidizing archaea (AOA), bacteria (AOB) and nitrite-oxidizing bacteria (NOB) to nitrification in four paddy soils from different geographic regions (Zi-Yang (ZY), Jiang-Du (JD), Lei-Zhou (LZ) and Jia-Xing (JX)) that are representative of the rice ecosystems in China. In urea-amended microcosms, nitrification activity varied greatly with 11.9, 9.46, 3.03 and 1.43??g NO3(-)-N?g(-1) dry weight of soil per day in the ZY, JD, LZ and JX soils, respectively, over the course of a 56-day incubation period. Real-time quantitative PCR of amoA genes and pyrosequencing of 16S rRNA genes revealed significant increases in the AOA population to various extents, suggesting that their relative contributions to ammonia oxidation activity decreased from ZY to JD to LZ. The opposite trend was observed for AOB, and the JX soil stimulated only the AOB populations. DNA-based stable-isotope probing further demonstrated that active AOA numerically outcompeted their bacterial counterparts by 37.0-, 10.5- and 1.91-fold in (13)C-DNA from ZY, JD and LZ soils, respectively, whereas AOB, but not AOA, were labeled in the JX soil during active nitrification. NOB were labeled to a much greater extent than AOA and AOB, and the addition of acetylene completely abolished the assimilation of (13)CO2 by nitrifying populations. Phylogenetic analysis suggested that archaeal ammonia oxidation was predominantly catalyzed by soil fosmid 29i4-related AOA within the soil group 1.1b lineage. Nitrosospira cluster 3-like AOB performed most bacterial ammonia oxidation in the ZY, LZ and JX soils, whereas the majority of the (13)C-AOB in the JD soil was affiliated with the Nitrosomona communis lineage. The (13)C-NOB was overwhelmingly dominated by Nitrospira rather than Nitrobacter. A significant correlation was observed between the active AOA/AOB ratio and the soil oxidation capacity, implying a greater advantage of AOA over AOB under microaerophilic conditions. These results suggest the important roles of soil physiochemical properties in determining the activities of ammonia oxidizers and nitrite oxidizers.The ISME Journal advance online publication, 10 October 2014; doi:10.1038/ismej.2014.194. PMID:25303715

Wang, Baozhan; Zhao, Jun; Guo, Zhiying; Ma, Jing; Xu, Hua; Jia, Zhongjun

2014-10-10

170

An analysis of the flow field in the region of the ASRM field joints  

Microsoft Academic Search

The flow field in the region of a solid rocket motor field joint is very important since fluid dynamic and mechanical propellant stresses can couple to cause a motor failure at a joint. Presented here is an examination of the flow field in the region of the Advanced Solid Rocket Motor (ASRM) field joints. The analyses were performed as a

Richard A. Dill; Harold R. Whitesides

1992-01-01

171

Potential contribution of anammox to nitrogen loss from paddy soils in southern china.  

PubMed

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

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

2015-02-01

172

Microbial community analysis in rice paddy soils irrigated by acid mine drainage contaminated water.  

PubMed

Five rice paddy soils located in southwest China were selected for geochemical and microbial community analysis. These rice fields were irrigated with river water which was contaminated by Fe-S-rich acid mine drainage. Microbial communities were characterized by high-throughput sequencing, which showed 39 different phyla/groups in these samples. Among these phyla/groups, Proteobacteria was the most abundant phylum in all samples. Chloroflexi, Acidobacteria, Nitrospirae, and Bacteroidetes exhibited higher relative abundances than other phyla. A number of rare and candidate phyla were also detected. Moreover, canonical correspondence analysis suggested that pH, sulfate, and nitrate were significant factors that shaped the microbial community structure. In addition, a wide diversity of Fe- and S-related bacteria, such as GOUTA19, Shewanella, Geobacter, Desulfobacca, Thiobacillus, Desulfobacterium, and Anaeromyxobacter, might be responsible for biogeochemical Fe and S cycles in the tested rice paddy soils. Among the dominant genera, GOUTA19 and Shewanella were seldom detected in rice paddy soils. PMID:25408313

Sun, Min; Xiao, Tangfu; Ning, Zengping; Xiao, Enzong; Sun, Weimin

2014-11-19

173

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

174

Fly ash effect on improving soil properties and rice productivity in Korean paddy soils.  

PubMed

Paddy soils in Korea generally require the addition of Si to enhance rice productivity. Coal combustion fly ash, which has a high available Si content and alkaline pH, was selected as a potential source of Si in this study. Two field experiments were carried out to evaluate rice (Oryza sativa) productivity in silt loam and loamy sand soils to which 0, 40, 80, and 120 Mg ha(-1) of fly ash were added with 2 Mg ha(-1) Si as a control. Fly ash increased the soil pH and available Si and P contents of both soils. The amount of available B increased to a maximum of 2.57 mg kg(-1), and the B content of the rice plants increased to a maximum of 52-53 mg kg(-1) following the addition of 120 Mg ha(-1) fly ash. The rice plants did not show toxicity effects. The highest rice yields were achieved following the addition of around 90 Mg ha(-1) fly ash. The application of fly ash increased Si, P and K uptake by the rice plants, but did not result in an excessive uptake of heavy metals in the submerged paddy soil. In conclusion, fly ash could be a good supplement to other inorganic soil amendments to improve the nutrient balance in paddy soils. PMID:16153826

Lee, Hyup; Ha, Ho Sung; Lee, Chang Hoon; Lee, Yong Bok; Kim, Pil Joo

2006-09-01

175

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

176

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

177

Wake Fields in the Super B Factory Interaction Region  

SciTech Connect

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

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

2011-06-02

178

Hydration Kinetics and Energy Analysis of parboiling Indica Paddy  

Microsoft Academic Search

Hydration of Indica paddy (variety IR-20) in hot water was studied as a function of time, pressure and vacuum followed by pressure at temperatures ranging from 25 to 75°C and time of soaking not exceeding 6h. Becker's diffusion equation was used to predict the soaking behaviour of paddy. Soaking at 196kPa and above, maintaining temperatures of 65°C, shows complete hydration

B. S. Sridhar; B. Manohar

2003-01-01

179

Reverse-transcriptional gene expression of anammox and ammonia-oxidizing archaea and bacteria in soybean and rice paddy soils of Northeast China.  

PubMed

The relative gene expression of hydrazine oxidoreductase encoding gene (hzo) for anaerobic ammonium oxidizing bacteria (anammox) and ammonia monooxygenase encoding gene (amoA) for both ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in Sanjiang Plain soybean and rice paddy soils of Northeast China was investigated by using real-time reverse-transcriptional quantitative PCR. Metabolically active populations of anammox, AOA, and AOB in rice paddy soils were evident by the presence and successful quantification of hzo mRNA and amoA mRNA genes. The expression ratio of amoA gene for both AOA and AOB varied between soybean soils and different rice paddy soils while the expression of hzo gene for anammox was detectable only in rice paddy soils by showing a diverse relative expression ratio in each soil sample. Gene expression of both archaeal and bacterial amoA genes in rice paddy soils differed among the three sampling depths, but that of hzo was not. Both archaeal and bacterial amoA genes showed an increase trend of expression level with continuation of rice paddy cultivation, but the low expression ratio of hzo gene indicated a relatively small contribution of anammox in overall removal of inorganic nitrogen through N2 even under anoxic and high nitrogen input in agriculture. Bacterial amoA gene from two soybean fields and three rice paddy fields were also analyzed for community composition by denaturing gradient gel electrophoresis fingerprint. Community shift was observed between soybean and paddy fields and within each of them. The consistent occurrence of three bands 5, 6, and 7 in all samples showed their high adaptability for both arid cultivation and continuous rice paddy cultivation. Our data suggest that AOA and AOB are playing a more important role in nitrogen transformation in agricultural soils in oxic or anoxic environment and anammox bacteria may also contribute but in a less extent to N transformation in these agricultural soils under anoxic condition. PMID:24077726

Wang, Jing; Dong, Hailiang; Wang, Weidong; Gu, Ji-Dong

2014-03-01

180

Agricultural Field in the Great Plains Region of Montana  

USGS Multimedia Gallery

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

181

Absence of Region 1\\/Region 2 field-aligned currents during prolonged quiet times  

Microsoft Academic Search

Using magnetic-field and precipitating-particle data from the DMSP\\/F7 satellite, it was found that, during extended periods of geomagnetic quiet, the large-scale field-aligned current (FAC) system known as Region 1\\/Region 2 either does not exist or is too small to be observable. A clear dayside cleft FAC system is observed on the preferred side of local noon for the indicated IMF

Frederick J. Rich; M. S. Gussenhoven

1987-01-01

182

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

NASA Astrophysics Data System (ADS)

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

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

2011-06-01

183

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

E-print Network

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

Scudder, Jack

184

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

185

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

186

Relationship between Birkeland current regions, particle precipitation, and electric fields  

NASA Technical Reports Server (NTRS)

The relationship of the large-scale dayside Birkeland currents to large-scale particle precipitation patterns, currents, and convection is examined using DMSP and Sondrestrom radar observations. It is found that the local time of the mantle currents is not limited to the longitude of the cusp proper, but covers a larger local time extent. The mantle currents flow entirely on open field lines. About half of region 1 currents flow on open field lines, consistent with the assumption that the region 1 currents are generated by the solar wind dynamo and flow within the surface that separates open and closed field lines. More than 80 percent of the Birkeland current boundaries do not correspond to particle precipitation boundaries. Region 2 currents extend beyond the plasma sheet poleward boundary; region 1 currents flow in part on open field lines; mantle currents and mantle particles are not coincident. On most passes when a triple current sheet is observed, the convection reversal is located on closed field lines.

De La Beaujardiere, O.; Watermann, J.; Newell, P.; Rich, F.

1993-01-01

187

WIND FIELD DEVELOPMENT FOR THE EPA REGIONAL OXIDANT MODEL  

EPA Science Inventory

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 the wind field i...

188

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

189

Distributional survey of large branchiopods of rice paddies in Shiga Prefecture, Japan: a Lake Biwa Museum project based on lay amateur participation  

Microsoft Academic Search

A distributional survey of the large branchiopod crustaceans of the rice paddies of Shiga Prefecture, Japan, was conducted by the Lake Biwa Museum in May and June of 1999 and 2000. Collecting kits were issued to over 100 lay Field Reporters, who returned all samples, usually dried, to the museum for processing. Their 242 species-lots were augmented by 146 from

Mark J. Grygier; Yasushi Kusuoka; Miyoshi Ida

2002-01-01

190

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

191

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

192

Risk Assessment of Heavy Metals Contamination in Paddy Soil, Plants, and Grains (Oryza sativa L.) at the East Coast of India  

PubMed Central

Heavy metals known to be accumulated in plants adversely affect human health. This study aims to assess the effects of agrochemicals especially chemical fertilizers applied in paddy fields, which release potential toxic heavy metals into soil. Those heavy metals get accumulated in different parts of paddy plant (Oryza sativa L.) including the grains. Concentrations of nonessential toxic heavy metals (Cd, Cr, and Pb) and the micronutrients (Cu, Mn, and Zn) were measured in the paddy field soil and plant parts. Mn and Cd are found to be accumulated more in shoot than in root. The metal transfer factors from soil to rice plant were significant for Pb, Cd, Cu, Cr, Mn, and Zn. The ranking order of bioaccumulation factor (BAF) for heavy metals was Zn > Mn > Cd > Cu > Cr > Pb indicating that the accumulation of micronutrients was more than that of nonessential toxic heavy metals. The concentrations of heavy metals were found to be higher in paddy field soils than that of the nearby control soil but below permissible limits. The higher Health Index (HI) values of rice consuming adults (1.561) and children (1.360) suggest their adverse health effects in the near future. PMID:24995308

Satpathy, Deepmala; Reddy, M. Vikram; Dhal, Soumya Prakash

2014-01-01

193

Chromospheric magnetic fields of an active region filament  

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

194

Effect of moisture regime on the redistribution of heavy metals in paddy soil.  

PubMed

Sequential extraction procedure was applied to assess the dynamics of solid-phase transformation of added Cu, Pb, Cd, and Hg in a typical Chinese paddy soil incubated under three moisture regimes (75% field capacity, wetting-drying cycle, and flooding). The heavy metals spiked in the soil were time-dependently transferred from the easily extractable fraction (the exchangeable fraction) into less labile fractions (Fe-Mn oxide- and organic matter-bound fractions), and thus reduced lability of the metals. No significant changes were found for the carbonate-bound and residual fractions of the heavy metals in the soil during the whole incubation. Change rate of the mobility factor (MF), a proportion of weakly bound fractions (exchangeable and carbonate-bound) in the total metal of soil, reflected the transformation rate of metal speciation from the labile fractions toward stable fractions. It was found that soil moisture regime did not change the direction and pathways of transformation of metal speciation, but it significantly affected the transformation rate. In general, the paddy soil under flooding regime had higher metal reactivity compared with 75% field capacity and wetting-drying cycle regimes, resulting in the more complete movement of metals toward stable fractions. This might be related to the increased pH, precipitation of the metals with sulfides and higher concentration of amorphous Fe oxides under submerged condition. PMID:21520813

Zheng, Shunan; Zhang, Mingkui

2011-01-01

195

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

196

Community structure and abundance of ammonia-oxidizing archaea and bacteria after conversion from soybean to rice paddy in albic soils of Northeast China.  

PubMed

Community composition of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in the albic soil grown with soybean and rice for different years was investigated by construction of clone libraries, denaturing gradient gel electrophoresis (DGGE), and quantitative polymerase chain reaction (q-PCR) by PCR amplification of the ammonia monooxygenase subunit A (amoA) gene. Soil samples were collected at two layers (0-5 and 20-25 cm) from a soybean field and four rice paddy fields with 1, 5, 9, and 17 years of continuous rice cultivation. Both the community structures and abundances of AOA and AOB showed detectable changes after conversion from soybean to rice paddy judged by clone library, DGGE, and q-PCR analyses. In general, the archaeal amoA gene abundance increased after conversion to rice cultivation, while bacterial amoA gene abundance decreased. The abundances of both AOA and AOB were higher in the surface layer than the bottom one in the soybean field, but a reverse trend was observed for AOB in all paddy samples regardless of the duration of paddy cultivation. Phylogenetic analysis identified nine subclusters of AOA and seven subclusters of AOB. Community composition of both AOA and AOB was correlated with available ammonium and increased pH value caused by flooding in multiple variance analysis. Community shift of AOB was also observed in different paddy fields, but the two layers did not show any detectable changes in DGGE analysis. Conversion from soybean to rice cultivation changed the community structure and abundance of AOA and AOB in albic agricultural soil, which requires that necessary cultivation practice be followed to manage the N utilization more effectively. PMID:24092004

Wang, Jing; Wang, Weidong; Gu, Ji-Dong

2014-03-01

197

Locating source regions of precursory seismo-electric fields and the mechanism generating electric field variations  

NASA Astrophysics Data System (ADS)

Electrodes consisting of a steel pipe in a deep borehole and a grounded wire surrounding the borehole were constructed to measure vertical electric fields, whereas conventional electrodes measure horizontal fields. Three years of monitoring showed that the anomalous variations in vertical underground electric fields preceding earthquakes and volcanic eruptions are much clearer than the variations in horizontal fields. The data also showed that there is much less man-made noise in the vertical fields. To determine whether these observed anomalies are forerunners of seismic disturbance, a system developed to locate precisely the source regions of underground vertical electric fields or volcanic tremors has been continuously operated. The system uses three or more time lags calculated by cross-correlating the electric fields or volcanic tremors recorded at four, or more, monitoring stations. If this system reveals the intensity distributions of the sources, prediction of imminent earthquakes and volcanic eruptions will become possible. To explain the mechanisms by which precursory electric field variations are generated, a model is proposed in which the electric field variations are generated by Earth current variations caused by increased electric conductivity in source regions before an earthquake. The conductivity is increased by free electrons and positive holes created on the fresh fracture surfaces caused by microcracks that occur before rock failure in the Earth's crust. The model can explain precursory electrical phenomena which are observed not only in the field before an earthquake but also in the laboratory before rock failure.

Takahashi, Kozo; Fujinawa, Yukio

1993-04-01

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

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

200

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

201

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

202

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

203

Eco-Stoichiometric Alterations in Paddy Soil Ecosystem Driven by Phosphorus Application  

PubMed Central

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

204

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

205

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

206

Water dissolved nitrous oxide from paddy agroecosystem in China  

Microsoft Academic Search

Although nitrous oxide emission from agricultural leaching and runoff is thought to constitute a globally important source of this greenhouse gas, water dissolved N2O in paddy ecosystems is poorly understood and scarcely reported where large amounts of fertilizer nitrogen are applied. This paper gives the results of a study assessing variability of the relationships between N2O and NO3? concentration in

Z. Q. Xiong; G. X. Xing; Z. L. Zhu

2006-01-01

207

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

208

[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

209

Inhibition experiments on nitrous oxide emission from paddy soils  

NASA Astrophysics Data System (ADS)

Rice fields using nitrogen-based fertilizers play an important role in the global N2O budget. However, our knowledge is still limited with regard to the mechanisms affecting the N2O emission and to the measures that can reduce the emission. This paper reports a study of N2O emission from paddy soils. The effects of urea, hydroquinone (HQ, a urease inhibitor), and dicyandiamide (DCD, a nitrification inhibitor) have been studied in pot experiments with and without rice plants and with and without addition of wheat straw. With no wheat straw amendment, all treatments with inhibitors, especially with HQ + DCD, had a much smaller N2O emission during the rice growing period than the urea treatment, whereas a substantially increased N2O emission was observed from a rice-free soil with inhibitors. The N2O emission from the rice-planted soil was exponentially positive correlated with the NO3--N concentration in the rice aboveground biomass. By comparing the total N2O emission from the rice-free soil and from the rice-planted soil, we found that urea application alone might induce an apparent plant-mediated N2O emission, being 0.39 +/- 0.08% of the applied urea N. Wheat straw incorporated into the flooded surface layer soil could increase the plant-mediated N2O emission significantly. However, application of HQ + DCD could reduce this emission (0.27 +/- 0.08% of the applied urea N, compared with 0.89 +/- 0.18% in the urea treatment). It also reduced the N2O emission from the rice-free soil and from the rice-planted soil. Stepwise regression analysis indicates that denitrification in the flooded surface layer soil was the main source of N2O emission from this wetland rice cultivation, particularly when wheat straw was added. A significantly nonlinear negative relation was found between the N2O emission and the CH4 emission when no wheat straw was added, but it was hard to quantify this trade-off relation when wheat straw was incorporated into the flooded surface layer soil.

Xu, Xingkai; Boeckx, Pascal; Zhou, Likai; Van Cleemput, Oswald

2002-08-01

210

Black carbon accrual during 2000 years of paddy-rice and non-paddy cropping in the Yangtze River Delta, China.  

PubMed

Rice straw burning has accompanied paddy management for millennia, introducing black carbon (BC) into soil as the residue of incomplete combustion. This study examined the contribution of BC to soil organic matter and the rate at which it accumulates in paddy soils as a result of prolonged paddy management. Soil depth profiles were sampled along a chronosequence of 0-2000 years of rice-wheat rotation systems and adjacent non-paddy systems (50-700 years) in the Bay of Hangzhou (Zhejiang province, China). The soil BC content and its degree of condensation were assessed using benzene-polycarboxylic acids (BPCAs) as geochemical markers. The results showed that despite regular long term BC input, BC only contributed 7-11% of total soil organic carbon (SOC) in the topsoil horizons. Nevertheless, along with SOC, paddy soils accumulated BC with increasing duration of management until 297 years to reach a steady-state of 13 t BC ha(-1). This was 1.8 times more than in non-paddy soils. The fate of BC in paddy soils (0-1 m) could be modeled revealing an average annual input of 44 kg ha(-1) yr(-1), and a mean residence time of 303 years. The subsoils contributed at least 50% to overall BC stocks, which likely derived from periods prior to land embankment and episodic burial of ancient topsoil, as also indicated by BPCA pattern changes. We conclude that there is a significant but limited accumulation of C in charred forms upon prolonged paddy management. The final contribution of BC to total SOC in paddy soils was similar to that in other aerobic ecosystems of the world. PMID:24227744

Lehndorff, Eva; Roth, Philipp J; Cao, Zhi H; Amelung, W

2014-06-01

211

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

NASA Astrophysics Data System (ADS)

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

Macalady, J.; Scow, K. M.

2001-12-01

212

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

E-print Network

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

California at Berkeley, University of

213

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

E-print Network

Parallel electric fields in the upward current region of the aurora: Numerical solutions R. E that a parallel electric field in the upward current region of the aurora is not confined to a single region along Direct observations of the parallel electric field by the Fast Auroral Snapshot satellite and the Polar

California at Berkeley, University of

214

Elucidating cadmium speciation and bioavailability in Thai paddy soils Saengdao Khaokaew1  

E-print Network

Elucidating cadmium speciation and bioavailability in Thai paddy soils GEOC 55 Saengdao Khaokaew1 flooding and draining of paddies can alter Cd chemistry (e.g., speciation, mobility and bioavailability). This research aims to explore the speciation and bioavailability of Cd under an alternating- flooding

Sparks, Donald L.

215

Secondary calcification of paddy soils in southern china: Morphological and substantive characteristics  

Microsoft Academic Search

Secondary calcification processes have been studied in three paddy soils (Anthrosols or Aquazems) of southern China. It is shown that the soils' amendment with lime powder and the periodic ponding of rice paddies with carbonate-rich water lead to the considerable transformation of the initial soils. The general properties of these soils and their morphological, micromorphological, and mineralogical features have been

I. V. Kovda; M. P. Lebedeva; N. P. Chizhikova; G. L. Zhang; Z. T. Gong; D. C. Li; V. I. Vasenev

2011-01-01

216

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

217

Heavy metal concentrations and their possible sources in paddy soils of a modern agricultural zone, southeastern China  

Microsoft Academic Search

In a typical modern agricultural Zone of southeastern China, Haining City, 224 topsoil samples were collected from paddy fields\\u000a to measure the total concentrations of copper (Cu), lead (Pb), zinc (Zn), cadmium (Cd), chromium (Cr), mercury (Hg), arsenic\\u000a (As) and cobalt (Co). The total concentrations ranged from 15.30 to 78.40 mg kg?1 for Cu, 20.10 to 41.40 mg kg?1 for Pb, 54.98 to 224.4 mg kg?1

Chunfa Wu; Limin Zhang

2010-01-01

218

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

219

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

220

Paddy rice productivity under climate and land-use change in northern Japan  

NASA Astrophysics Data System (ADS)

An evaluation of the best rice cultivar under climate change is an important issue because the projected climate change has a potential to bring a negative impact on crop yield. In this study, we estimate an impact of climate change on rice yield and potential best cultivar in northern Japan where the larger paddy field is located than other regions in Japan. Two global climate model data, MIROC5 (RCP 4.5) and MRI-AGCM (SRES A1B), are applied as the future scenario. These data are too coarse to resolve the regional differences in northern Japan; we conduct the downscale experiments by a regional climate model (JMA-NHM) with a 10-km grid spacing. Considering that rice yield is sensitive to warm season climate, we conduct the downscaling from 28th May to 1st September during 1981-2000 and 2081-2099. The biases of downscaled two scenarios are corrected to match their cumulative distribution functions (CDF) of present climate with that of the station-based observation. The derived CDF-based biases are also used to correct the future scenarios. These corrected scenarios are applied to rice growth model (NIAES-Rice). To take account for the impacts of land use change (LUC) on climate and rice yield, we consider the additional temperature changes due to the LUC. As a reference, we add the LUC-induced temperature change in southwest Japan because the data are available from the previous study. We first check the climate change in northern Japan. General tendencies derived from the bias-corrected-downscaled future climates are that 1) surface warming was approximately twice in low elevation area relative to mountainous area and 2) downward shortwave radiation homogeneously increased 7-8 W m-2. Then, we evaluated the simulated yield through comparing with observation. Using observed ambient conditions as input data, the NIAES-Rice model provides the reasonable performance in simulating the rice yield with biases ranging from -19.0 to 29.2 % in prefecture base. Climate changes enhance the rice yield for 'Koshihikari' from 372.4 to 388.1 g/10a. The cultivar is planted in half of prefectures in Japan. For each analysis grid, we chose the cultivar that held the largest yield among the 10 analyzed cultivars and found that the location of cultivar that achieves the largest yields shifted northward in future climate. Also, the grids that cultivar developed in central Japan become the largest yield among 10 cultivars increase more than triple in the future climate. A LUC-induced temperature impact on prefecture-based yield corresponds to about 18 % of the climate-change-induced yield change, ranging from 0.6 to 33.5 % for six prefectures in the analyzed area. There is unclear tendency between the present rice yield amount and the intensity of LUC impact. However, surface warming due to urbanization decrease the rice yield in all six prefectures. Thus land use management and planting cultivar change are essential for stable food security.

Yoshida, R.; Fukui, S.; Shimada, T.; Hasegawa, T.; Iwasaki, T.

2013-12-01

221

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

E-print Network

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

Scudder, Jack

222

Twisted Solar Active Region Magnetic Fields as Drivers of Space Weather: Observational  

E-print Network

Twisted Solar Active Region Magnetic Fields as Drivers of Space Weather: Observational and dynamics of magnetic fields on the Sun's photosphere and outer layers ­ notably those within solar active discuss here a novel technique for measuring twist in the magnetic field lines of solar active regions

Mackay, Duncan

223

[Land cover and landscape pattern changes in Poyang Lake region of China in 1980-2010].  

PubMed

Based on the land cover datasets of Poyang Lake region in 1980, 2005, and 2010, and by using GIS, RS, and landscape ecology approaches, this paper studied the land cover and landscape pattern changes in this region from 1980 to 2010, and quantitatively analyzed the land cover types change degree, patch area index, patch shape index, margin density index, and landscape diversity index. In 1980-2010, the main land cover types in this region were paddy field, inland water, evergreen broadleaf forest, and urban built-up area, and their areas and spatial patterns varied dramatically. Overall, the areas of inland water and urban built-up area had a significant increase, while those of paddy field and dry farmland decreased somewhat. Due to the effects of population growth and economic development, the landscape fragmentation degree and landscape diversity index presented a decreasing trend, but the decrement was small, which implied that the previous environmental management of this region had exerted important roles, but a long term challenge was still faced with between the regional environmental protection and sustainable development. PMID:23898669

Wang, Juan-le; Ran, Ying-ying; Zhang, Yong-jie; Cao, Xiao-ming; Yang, Fei

2013-04-01

224

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

225

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

226

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

E-print Network

Dune field pattern formation and recent transporting winds in the Olympia Undae Dune Field, north] HighResolution 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

Bourke, Mary C.

227

Influence of changed vegetations fields on regional climate simulations in the Barents Sea Region  

Microsoft Academic Search

In the context of the EU-Project BALANCE (http:\\/\\/balance-eu.info) the regional climate model REMO was used for extensive calculations of the Barents Sea climate to investigate the vulnerability\\u000a of this region to climate change. The regional climate model REMO simulated the climate change of the Barents Sea Region between\\u000a 1961 and 2100 (Control and Climate Change run, CCC-Run). REMO on ~50 km

Holger Göttel; Jörn Alexander; Elke Keup-Thiel; Diana Rechid; Stefan Hagemann; Tanja Blome; Annett Wolf; Daniela Jacob

2008-01-01

228

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

229

Effect of Long-Term Paddy-Upland Yearly Rotations on Rice (Oryza sativa) Yield, Soil Properties, and Bacteria Community Diversity  

PubMed Central

A 10-year-long field trial (between 2001 and 2010) was conducted to investigate the effect of paddy-upland rotation on rice yield, soil properties, and bacteria community diversity. Six types of paddy-upland crop rotations were evaluated: rice-fallow (control; CK), rice-rye grass (RR), rice-potato with rice straw mulches (RP), rice-rapeseed with straw incorporated into soil at flowering (ROF), rice-rapeseed incorporated in soil after harvest (ROM), and rice-Chinese milk vetch (RC). Analysis of terminal restriction fragment length polymorphism (T-RFLP) was used to determine microbial diversity among rotations. Rice yield increased for upland crops planted during the winter. RC had the highest average yield of 7.74?t/ha, followed by RR, RP, ROM, and ROF. Soil quality differences among rotations were found. RC and RP improved the soil mean weight diameter (MWD), which suggested that rice rotated with milk vetch and potato might improve the paddy soil structure. Improved total nitrogen (TN) and soil organic matter (SOM) were also found in RC and RP. The positive relationship between yield and TN/SOM might provide evidence for the effect of RC rotation on rice yield. A strong time dependency of soil bacterial community diversity was also found. PMID:22919301

Chen, Song; Zheng, Xi; Wang, Dangying; Chen, Liping; Xu, Chunmei; Zhang, Xiufu

2012-01-01

230

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

NASA Astrophysics Data System (ADS)

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

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

231

Correlation between magnetic and electric field perturbations in the field-aligned current regions deduced from DE 2 observations  

NASA Technical Reports Server (NTRS)

The satellite-observed high correlations between magnetic and electric field perturbations in the high-latitude field-aligned current regions are investigated by examining the dependence of the relationship between Delta-B and E on spatial scale, using the electric and magnetic field data obtained by DE 2 in the polar regions. The results are compared with the Pedersen conductivity inferred from the international reference ionosphere model and the Alfven wave velocity calculated from the in situ ion density and magnetic field measurements.

Ishii, M.; Sugiura, M.; Iyemori, T.; Slavin, J. A.

1992-01-01

232

Geology and regional setting of Kuparuk Oil Field, Alaska  

SciTech Connect

The Kuparuk oil field is located on the Alaskan Arctic plain in the Colville-Prudhoe basin, 10 to 30 mi (16 to 48 km) west of the Prudhoe Bay field. The 24/sup 0/ API crude is similar in type to that in the Permo-Triassic reservoirs in the Prudhoe Bay field; however, it is from the Lower Cretaceous Kuparuk Formation. This reservoir is located in a basin between the Colville and Prudhoe highs. The origin of the oil is believed to be predominantly Lower sequence formations with migration occurring possibly via the Prudhoe Bay field. The dominant trapping mechanism is stratigraphic pinch-out and truncation of the reservoir at a local unconformity along the southern and western flanks of a southeast-plunging antiform. Structural dip closure exists along the northern and eastern flanks. The reservoir sandstones occur within sequences which become cleaner and coarser upward, and are thought to be shallow marine in origin with a provenance to the northeast. They are interpreted to be infrarift sediments on what is now a passive, Atlantic-type continental margin. Two of the four major lithostratigraphic units mapped within the Kuparuk Formation exhibit good reservoir characteristics and extend over an area in excess of 200 mi/sup 2/ (518 km/sup 2/). The cumulative net pay in the Kuparuk field ranges up to 90 ft, and the estimate of movable oil-in-place is 4.4 billion stock tank bbl. There is no gas cap. The field exhibits a variable oil-water contact ranging from -6,530 ft (-1,990 m) in the southeast to -6,700 ft (-2,042 m) in the north. After secondary waterflooding, the potential recoverable reserves are estimated to be about 1.0 to 1.5 billion stock tank bbl. Kuparuk field, therefore, ranks as one of the largest oil fields in the United States.

Carman, G.J.; Hardwick, P.

1983-06-01

233

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

E-print Network

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

California at Berkeley, University of

234

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

E-print Network

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

Higuchi, Tomoyuki

235

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

E-print Network

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

Sanahuja, Blai

236

Secondary calcification of paddy soils in southern china: Morphological and substantive characteristics  

Microsoft Academic Search

Secondary calcification processes have been studied in three paddy soils (Anthrosols or Aquazems) of southern China. It is\\u000a shown that the soils’ amendment with lime powder and the periodic ponding of rice paddies with carbonate-rich water lead to\\u000a the considerable transformation of the initial soils. The general properties of these soils and their morphological, micromorphological,\\u000a and mineralogical features have been

I. V. Kovda; M. P. Lebedeva; N. P. Chizhikova; G. L. Zhang; Z. T. Gong; D. C. Li; V. I. Vasenev

2011-01-01

237

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

238

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

239

The Impact of Fertilizer Subsidy on Paddy Cultivation in Sri Lanka  

E-print Network

The Government of Sri Lanka has been subsidizing fertilizer for more than four decades. This study attempts to analyse the impact of fertilizer subsidies with reference to paddy cultivation in Sri Lanka. The issue is analysed by employing three separate demand functions for major fertilizers by using simple regression model. Regression results indicate that changes in the prices of fertilizer and paddy do not have a significant effect on fertilizer usage, which points to the fact that the fertilizer subsidy is not a key determinant of the use of fertilizer in paddy cultivation. The study also found that there is a relatively higher correlation between fertilizer usage and paddy price than between fertilizer usage and fertilizer price. These findings suggest that the fertilizer subsidy could be withdrawn gradually over time. In its place, appropriate infrastructure and institutional facilities that are required to increase productivity in paddy cultivation and an effective mechanism for marketing the output that would result in favourable prices for paddy may be introduced for a more effective outcome. (JEL N551, Q19) I.

H. K. J. Ekanayake

240

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

Microsoft Academic Search

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

Sabine Stanley; Jeremy Bloxham

2004-01-01

241

Controls on porphyroblast size along a regional metamorphic field gradient  

Microsoft Academic Search

Garnet-bearing schists from the Waterville Formation of south-central Maine provide an opportunity to examine the factors\\u000a governing porphyroblast size over a range of metamorphic grade. Three-dimensional sizes and locations for all garnet porphyroblasts\\u000a were determined for three samples along the metamorphic field gradient spanning lowest garnet through sillimanite grade, using\\u000a high-resolution X-ray computed tomography. Comparison of crystal size distributions to

David M. Hirsch

2008-01-01

242

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

E-print Network

Coronal Currents, Magnetic Fields and Heating in a Solar Active Region Jeongwoo Lee Astronomy of available telescopes. For example, Gary and Hurford (1994) are able to derive the magnetic field strength relationship between specific microwave frequencies and coronal magnetic field strengths can be exploited (e

White, Stephen

243

Magnetic Field Strengths and Structures from Radio Observations of Solar Active Regions  

Microsoft Academic Search

Radio observations of some active regions (ARs) obtained with the Nobeyama radioheliograph at lambda=1.76 cm are used for estimating the magnetic field strength in the upper chromosphere, based on thermal bremsstrahlung. The results are compared with the magnetic field strength in the photosphere from observations with the Solar Magnetic Field Telescope (SMFT) at Huairou Solar Observing Station of Beijing Astronomical

Chang-Xi Zhang; G. B. Gelfreikh; Jing-Xiu Wang

2002-01-01

244

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

245

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

246

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

247

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

NASA Astrophysics Data System (ADS)

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

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

2010-05-01

248

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

249

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

250

Fields and Flares: Understanding the Complex Magnetic Topologies of Solar Active Regions  

NASA Astrophysics Data System (ADS)

Sunspots are regions of decreased brightness on the visible surface of the Sun (photosphere) that are associated with strong magnetic fields. They have been found to be locations associated with solar flares, which occur when energy stored in sunspot magnetic fields is suddenly released. The processes involved in flaring and the link between sunspot magnetic fields and flares is still not fully understood, and this thesis aims to gain a better understanding of these topics. The magnetic field evolution of a number of sunspot regions is examined using high spatial resolution data from the Hinode spacecraft. The research presented in this thesis gives insight into both photospheric and coronal magnetic field evolution of flaring regions. Significant increases in vertical field strength, current density, and field inclination angle towards the vertical are observed in the photosphere just hours before a flare occurs, which is on much shorter timescales than previously studied. First observations of spatial changes in field inclination across a magnetic neutral line (generally believed to be a typical source region of flares) are also discovered. 3D magnetic field extrapolation methods are used to study the coronal magnetic field, using the photospheric magnetic field data as a boundary condition. Magnetic energy and free magnetic energy are observed to increase significantly a few hours before a flare, and decrease afterwards, which is a similar trend to the photospheric field parameter changes observed. Evidence of partial Taylor relaxation is also detected after a flare, as predicted by several previous studies. The results outlined in this thesis show that this particular field of research is vital in furthering our understanding of the magnetic nature of sunspots and its link to flare processes.

Murray, Sophie A.

2013-01-01

251

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

E-print Network

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

Sparks, Donald L.

252

Evolution of the Tharsis region of Mars: insights from magnetic field observations  

Microsoft Academic Search

Mars Global Surveyor (MGS) observations of crustal magnetic fields over Tharsis provide new constraints on models for the thermal and magmatic evolution of this region. We analyze the distribution of magnetic field anomalies over Tharsis surface units of Noachian, Hesperian and Amazonian age. These data suggest that early Noachian crust underlies the Tharsis province, and formed contemporaneously with the existence

Catherine L. Johnson; Roger J. Phillips

2005-01-01

253

Regional electric field induced by electroconvulsive therapy: A finite element simulation study  

Microsoft Academic Search

The goal of this study is to investigate the regional distribution of the electric field (E-field) strength induced by electroconvulsive therapy (ECT), and to contrast clinically relevant electrode configurations through finite element (FE) analysis. An FE human head model incorporating tissue heterogeneity and white matter anisotropy was generated based on structural magnetic resonance imaging (MRI) and diffusion tensor MRI (DT-MRI)

Won Hee Lee; Zhi-De Deng; Tae-Seong Kim; A. F. Laine; S. H. Lisanby; A. V. Peterchev

2010-01-01

254

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

255

Mechanism of formation of a dipole magnetic field in the central regions of active galaxies  

NASA Astrophysics Data System (ADS)

A model of the formation of large-scale magnetic fields of dipole configuration in the central regions (r ? 100 pc) of active galaxies is studied. It is assumed that these regions contain a rapidly rotating, highly ionized gas (? ? 5·10-15 sec, Ne ? 103 cm-3). Ionized matter escapes from the center of the region with a velocity of several hundred km/sec and is entrained by the rotation of the surrounding medium. Biermann's "battery" effect [L. Biermann, Z. Naturforsch., 5a, 65 (1950)] operates under such conditions, and circular electric currents are formed in the medium, which amplify the dipole magnetic fields. During the active phase of a galaxy, about 108 years, the magnetic field strength at the boundary of this region may reach 10-4 10-3 G.

Andreasyan, R. R.

1996-01-01

256

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

257

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

PubMed

The discovery of Uranus' and Neptune's non-dipolar, non-axisymmetric magnetic fields destroyed the picture--established by Earth, Jupiter and Saturn--that planetary magnetic fields are dominated by axial dipoles. Although various explanations for these unusual fields have been proposed, the cause of such field morphologies remains unexplained. Planetary magnetic fields are generated by complex fluid motions in electrically conducting regions of the planets (a process known as dynamo action), and so are intimately linked to the structure and evolution of planetary interiors. Determining why Uranus and Neptune have different field morphologies is not only critical for studying the interiors of these planets, but also essential for understanding the dynamics of magnetic-field generation in all planets. Here we present three-dimensional numerical dynamo simulations that model the dynamo source region as a convecting thin shell surrounding a stably stratified fluid interior. We show that this convective-region geometry produces magnetic fields similar in morphology to those of Uranus and Neptune. The fields are non-dipolar and non-axisymmetric, and result from a combination of the stable fluid's response to electromagnetic stress and the small length scales imposed by the thin shell. PMID:15014493

Stanley, Sabine; Bloxham, Jeremy

2004-03-11

258

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

SciTech Connect

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

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

2012-11-20

259

Venus nightside ionospheric holes - The signatures of parallel electric field acceleration regions  

NASA Technical Reports Server (NTRS)

Attention is given to the existence of 'holes', that is, regions of density depletion in the nightside Venus ionosphere associated with regions of radial magnetic fields. The properties of the electrons within the core of these holes are thought to suggest an acceleration process along the magnetic field lines, a process also suggested by the Venera 9 and 10 observations of energetic ions in the Venus tail. On the basis of the observational information, these Venusian plasma depletions are attributed to the presence of parallel electric fields similar to those observed in the terrestrial auroral ionosphere. The resulting electric field accelerates electrons down the field lines, heating the depleted thermal electron population within the hole and producing ionization below the hole. At the same time, ionospheric ions are accelerated outward toward the plasmasheet.

Grebowsky, J. M.; Curtis, S. A.

1981-01-01

260

In situ electrokinetic remediation of As-, Cu-, and Pb-contaminated paddy soil using hexagonal electrode configuration: a full scale study.  

PubMed

We investigated the in situ applicability of the electrokinetic process with a hexagonal electrode configuration in order to remediate arsenic (As)-, copper (Cu)-, and lead (Pb)-contaminated paddy rice field soil at a field scale (width 17 m, length 12.2 m, and depth 1.6 m). An iron electrode was used in order to prevent the severe acidification of the soil near the anode. We selected ethylenediaminetetraacetic acid (EDTA) as a pursing electrolyte to enhance the extraction of Cu and Pb. The system removed 44.4 % of the As, 40.3 % of the Cu, and 46.6 % of the Pb after 24 weeks of operation. Fractionation analysis showed that the As bound to amorphous ion (Fe) and aluminum (Al) oxyhydroxides was changed into a form of As specifically bound. In the case of Cu and Pb, the fraction bound to Fe-Mn oxyhydroxide primarily decreased. The EDTA formed negatively charged complexes with Cu and Pb, and those complexes were transported toward the anode. The energy consumption was very low compared to that on a small scale because there was less energy consumption due to Joule heating. These results show that the in situ electrokinetic process could be applied in order to remediate paddy rice fields contaminated with multiple metals. PMID:25103944

Jeon, Eun-Ki; Jung, Ji-Min; Kim, Woo-Seung; Ko, Sung-Hwan; Baek, Kitae

2015-01-01

261

Model for the Coupled Evolution of Subsurface and Coronal Magnetic Fields in Solar Active Regions  

NASA Astrophysics Data System (ADS)

According to Babcock's theory of the solar dynamo, bipolar active regions are ?-shaped loops emerging from a toroidal field located near the base of the convection zone. In this paper, a mean field model for the evolution of a twisted ?-loop is developed. The model describes the coupled evolution of the magnetic field in the convection zone and the corona after the loop has fully emerged into the solar atmosphere. Such a coupled evolution is required to fully understand what happens to the coronal and subsurface fields as magnetic flux cancels at polarity inversion lines on the photosphere. The jump conditions for the magnetic field at the photosphere are derived from the magnetic stress balance between the convection zone and corona. The model reproduces the observed spreading of active region magnetic flux over the solar surface. At polarity inversion lines, magnetic flux submerges below the photosphere, but the component of magnetic field along the inversion line cannot submerge, because the field in the upper convection zone is nearly radial. Therefore, magnetic shear builds up in the corona above the inversion line, which eventually leads to a loss of equilibrium of the coronal fields and the ``lift-off'' of a coronal flux rope. Fields that submerge are transported back to the base of the convection zone, leading to the repair of the toroidal flux rope. Following Martens and Zwaan, interactions between bipoles are also considered.

van Ballegooijen, A. A.; Mackay, D. H.

2007-04-01

262

Monitoring rice cropping systems using China environment satellite data in Poyang Lake region  

NASA Astrophysics Data System (ADS)

Threshold method was utilized to discriminate rice cropping systems based on the noticeable variation of Normalized Difference Vegetation Index (NDVI) during key growth stages in Poyang Lake Region, China. This area is dominated by double- and single rice cropping systems which tend to change due to the frequent ecosystem management policies. We used a new satellite data from the CCD camera sensor with 30 m spatial resolution onboard the China Environmental Satellite HJ-1A and B. The HJ -1A/B with a better temporal resolution of four days provides more data options for effective and timely agriculture monitoring. The result showed that there is evident difference of NDVI between single and late rice during mid October when they are in different growth stages. The areas of single and late rice in 2011 were 2988.6 km2 and 3105.9 km2, respectively. Paddy field distribution map and local paddy rice calendar are requisite to move the threshold method into other multiple rice cropping regions. The study suggests that the China Environmental Satellite HJ-1A/B have the potential to rice cropping system in the double to triple rice cropping systems area. With many advantages of HJ-1A/B, like, finer spatial and temporal resolution, bigger imaging swath, it may make rice cropping system monitoring more feasible and operational.

Li, Peng; Jiang, Luguang; Feng, Zhiming

263

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

SciTech Connect

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

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

2012-11-15

264

Microhabitat use by Hyla japonica and Pelophylax porosa brevipoda at Levees in rice paddy areas of Japan.  

PubMed

In Japan, rice paddies have acted as substitute habitats for pond-breeding frogs. However, frog populations are declining due to the loss of habitat and environmental changes in rice paddy areas. Frogs need both aquatic and terrestrial habitats to complete their life history; in rice paddy areas, levees that surround rice paddies provide terrestrial habitats for basking, foraging, and shelter from predators. Studying microhabitat use at levees is important to elucidating the ecological roles of levees and to properly managing them to support frog populations. In this study, we conducted surveys in lowland modernized rice paddy areas in Shiga Prefecture in which a common species, Hyla japonica, and an endangered species, Pelophylax porosa brevipoda, were found. We captured frogs at levees and recorded environmental factors related to levee vegetation, rice paddy conditions, and weather. We constructed generalized linear mixed models to examine the effects of environmental factors on juvenile and adult H. japonica and on small and large juveniles, females, and males of P. p. brevipoda. Our results showed distinct microhabitat uses at levees in different species, sexes, and body sizes. In general, abundance was high at levees with vegetation that provided shelter. The water depth in rice paddies negatively influenced juvenile H. japonica and large juvenile and small female P. p. brevipoda, and positively influenced small male P. p. brevipoda. The maintenance of a mosaic structure of levees was important not only to support frog populations but also to maintain frog diversity in the area. PMID:23646944

Naito, Risa; Sakai, Masaru; Natuhara, Yosihiro; Morimoto, Yukihiro; Shibata, Shozo

2013-05-01

265

Parasegetibacter terrae sp. nov., isolated from paddy soil and emended description of the genus Parasegetibacter.  

PubMed

A Gram-stain-negative, variable-shaped, non-flagellated, yellow-pigmented, aerobic bacterium designated SGM2-10T was isolated from a paddy soil sample from Suwon region, South Korea. Phylogenetic analysis based on 16S rRNA sequences indicated that the isolate was most closely related with Parasegetibacter luojiensis RHYL-37T. The 16S rRNA gene sequence of strain SGM2-10T showed the highest sequence similarities with Parasegetibacter luojiensis RHYLT (95.1% sequence similarity), Flavitalea populi HY-50RT (95.0) and Flavitalea gansuensis JCN-23T (94.4%). No other species in the family Chitinophagaceae exceeded 94.1?% 16S rRNA gene sequence similarity with strain SGM2-10T. The major fatty acids of strain SGM2-10T were iso-C15:0 (28.6%), iso-C15:1 G (21.5%) and iso-C17:0 3-OH (14.2%). The only menaquinone was MK-7. The polar lipids were composed of phosphatidylethanolamine (PE), seven unknown lipids and ten unknown aminolipids. The G+C content of the DNA of strain SGM2-10T was 46.7 mol%. On the basis of the results of the polyphasic characterization presented in this study, it is concluded that strain SGM2-10T represents a novel species of the genus Parasegetibacter, for which the name Parasegetibacter terrae is proposed. The type strain is SGM2-10T (= KACC 17341T = JCM 19942T). The description of the genus Parasegetibacter has also been emended. PMID:25288279

Kim, Soo-Jin; Ahn, Jae-Hyung; Weon, Hang-Yeon; Hong, Seung-Beom; Seok, Soon-Ja; Kwon, Soon-Wo

2014-10-01

266

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

267

IAG Working Group on Regional Dense Velocity Fields: First Results and Steps Ahead  

NASA Astrophysics Data System (ADS)

The IAG Working Group (WG) on "Regional Dense Velocity Fields" was created within IAG sub-commission 1.3 "Regional Reference Frames" at the IUGG General Assembly in Perugia in 2007. The goal of the Working Group is to densify the latest realization of the ITRS and provide regional dense velocity information in a common global reference frame. For that purpose, working group members join efforts with the regional sub-commissions (AFREF, NAREF, SIRGAS, EUREF, …) and analysis groups processing data from local/regional continuous and episodic GNSS stations. Up to now, dedicated region coordinators have gathered velocity solutions (in accordance with the WG requirements) for their region and combined these solutions with the sub-commission regional solutions to produce a regional cumulative combined solution. Two combination coordinators performed a first test combination of these regional solutions together with global solutions in order to identify the main problems when producing a dense velocity field based on multiple cumulative position and velocity solutions. First comparisons between different velocity solutions show an RMS agreement between 0.3 mm/yr and 0.5 mm/yr resp. for the horizontal and vertical velocities. In some cases, significant disagreements between the velocities of some of the networks are seen, but these are primarily caused by the inconsistent handling of discontinuity epochs and solution numbers. Consequently, this test identified the urgent need for a consensus on the attribution of discontinuity epochs for stations common to several solutions. Due to the use of different analysis strategies and software packages by the individual contributors, finding such a consensus is a challenge as most probably not the same discontinuities are seen by different people. A possible way to go ahead for the Working Group could be to combine solutions at the weekly level. This approach is one of the alternative procedures which are presently under discussion within the WG. More details on the WG are available from http://epncb.oma.be/IAG/.

Bruyninx, Carine

2010-05-01

268

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

E-print Network

Speciation and Release Kinetics of Zinc in Contaminated Paddy Soils Saengdao Khaokaew,*, Gautier is an important nutrient for plants, but it can be toxic at high concentrations. The solubility and speciation. This study determined Zn speciation and release kinetics in Cd-Zn cocontami- nated alkaline and acidified

Sparks, Donald L.

269

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

270

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

EPA Science Inventory

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

271

Effect of rice plants on methane production and rhizospheric metabolism in paddy soil  

Microsoft Academic Search

In order to elucidate the effects of rice plants on CH4 production, we conducted experiments with soil slurries and planted rice microcosms. Methane production in anoxic paddy soil slurries was stimulated by the addition of rice straw, of unsterile or autoclaved rice roots, and of the culture fluid in which rice plants had axenically been cultivated. The addition of these

Simone Dannenberg; Ralf Conrad

1999-01-01

272

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

273

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

274

In field archaeology, analysis of an excavat-ed region is a meticulous process requiring  

E-print Network

In field archaeology, analysis of an excavat- ed region is a meticulous process requiring archaeologists to augment tradi- tional analysis approaches. We introduce new archaeological analysis tools (CAVE).2 These tools I give archaeologists access to formerly inaccessible parts of the archaeological

Laidlaw, David

275

Strength distribution of solar magnetic fields in photospheric quiet Sun regions  

Microsoft Academic Search

Context: The magnetic topology of the solar photosphere in its quietest regions is hidden by the difficulties to disentangle magnetic flux through the resolution element from the field strength of unresolved structures. The observation of spectral lines with strong coupling with hyperfine structure, like the observed Mn i line at 553.7 nm, allows such differentiation. Aims: To analyse the distribution

J. C. Ramírez Vélez; A. López Ariste; M. Semel

2008-01-01

276

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

SciTech Connect

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

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

2011-01-01

277

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

278

All-Regions Tunable High Harmonic Enhancement by a Periodic Static Electric Field  

SciTech Connect

Simulations show that a static electric field periodically distributed in space can be used to control the production of coherent light by high-order harmonic generation in a wide spectral range covering extreme-ultraviolet and soft x-ray radiation. The radiation yield is selectively enhanced due to symmetry breaking induced by a static electric field on the interaction between the driving laser and the medium. The spectral position of the enhancement is tuned by varying the periodicity of the static electric field which matches twice the coherence length of the harmonics in the desired region. We find that the static electric field strength inducing enhancement decreases for shorter wavelengths and predict an increase of more than two orders of magnitude for harmonics in the water window spectral range with a static electric field as weak as 1.12 MV/cm.

Serrat, Carles [ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, 08860 Castelldefels (Barcelona) (Spain); DTDI-Universitat de Vic, Carrer de la Laura 13, 08500 Vic (Barcelona) (Spain); Biegert, Jens [ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, 08860 Castelldefels (Barcelona) (Spain); ICREA-Institucio Catalana de Recerca i Estudis Avancats, 08010 Barcelona (Spain)

2010-02-19

279

Magnetic fields in methanol maser condensations based on data for related regions. Seven sources: Astrophysical parameters  

NASA Astrophysics Data System (ADS)

The astrophysical parameters of seven OH maser condensations are estimated based on magnetic fields obtained from polarization observations carried out on the Nan cay Radio Telescope (France) in the 1665 and 1667 MHz lines in four Stokes parameters. Regions in the studied sources containing the observed clusters of maser condensations, as well as clusters of Class I and II methanol masers, have been identified. The associations of the masers are real; i.e., the magnetic field in the clusters can also extend to groups of methanol masers. The linear dimensions of these associations have been found. The ratio of the mass to the magnetic flux, ratio of the thermal to the magnetic pressure, and virial relationships between energies (kinetic, magnetic, and gravitational) in the regions containing the OH andmethanol masers have been obtained. In sources whose magnetic fields have been determined fairly reliably, the ratio of the mass to the magnetic flux exceeds a critical value, and the energies of chaotic motions and of the magnetic field are considerably smaller than the gravitational binding energy. On the other hand, in all cases, the ratio of the thermal to the magnetic pressure is <1, suggesting that the clouds may be in amagnetically dominated regime. This inconsistency is related to probable uncertainties in the the magnetic field values and the estimated distances to the sources, which may lead to overestimation of the sizes of the regions studied.

Bayandina, O. S.; Alakoz, A. V.; Val'tts, I. E.

2014-07-01

280

A study of the crust stress field for the Aegean region (Greece)  

NASA Astrophysics Data System (ADS)

The in situ stress field may be assessed from data such as the fault plane solutions of the earthquakes occurring in the region and by estimation of a stress field compatible with the kinematic behavior of the crust. The regional kinematics may be derived from the velocity field estimated from GPS data and other geodetic observations. In the present work an investigation of the stress field of the Aegean Sea is carried out following two approaches; both use the same tectonic characteristics for the Hellenic region and the same assumptions referring to the mechanical properties of the medium. In the first approach, the yearly rate of the in situ crustal stresses, based on a two-dimensional FE linear analysis, are evaluated solving for the inverse problem, given the GPS observed displacement field for the broader Aegean region. The results have been compared with published papers and with stresses obtained from available focal mechanism solutions. In the second approach the borders of the probable lithospheric micro-plates and the active faults are considered as discontinuities in an elastic half-space representing the earth's crust. The Coulomb stress changes due to the tectonic slip are evaluated, providing an insight of the way these tectonic elements interact. Assuming succeeding activation of the tectonic structures of the region the accumulation of the Coulomb stress changes has been estimated. The accumulated Coulomb shear stress distribution provides a criterion for the selection of the more realistic boundary conditions for the FE modeling. In this respect, the two approaches complement each other and enrich the final picture discussed here.

Mitsakaki, Christiana; Sakellariou, Michael G.; Tsinas, Demitris

2013-06-01

281

Regional tree growth reductions due to ambient ozone: evidence from field experiments. [Populus deltoides; Robinia pseudoacacia  

SciTech Connect

Observations from extensive regions in Europe and North America suggest that many forests may be in early stages of ecosystem decline. The authors present experimental evidence from open-top chamber field studies indicating that ambient ozone at levels below the ambient air quality standard (235 ..mu..g m/sup -3/) causes significant reductions (19%) in the growth of sapling poplars (hybrid Populus). While ozone-induced reductions in growth have been observed under laboratory and greenhouse conditions, demonstration of this effect under field conditions is critical to the establishment of ozone standards. Growth reductions for Populus deltoides and Robinia pseudoacacia were not significant. Reductions in productivity and height growth occurred without visible symptoms of foliar injury and at ozone concentrations below current standards. If this invisible injury is typical in other tree species, the extent of ozone-induced forest damage may presently be greatly underestimated. Additional field studies on a regional basis are needed.

Wang, D.; Bormann, F.H.; Karnosky, D.F.

1986-11-01

282

F-region dynamo current as deduced from the magnetic-field observations by CHAMP  

NASA Astrophysics Data System (ADS)

Thermospheric neutral winds generate dynamo currents through ion-neutral collision. In ease of the equatorial F-region dynamo the current forms a meridional circuit in each hemisphere, leading to asymmetric zonal deflections of the geomagnetic field [Lühr and Maus, 2006]. Us-u ing magnetic observations of the CHAMP satellite, we investigate variations of the F-region dynamo current with season, longitude, local time, and solar activity. Dynamo currents show pronounced seasonal/longitudinal (S/L) variations. Around noon they show different longitu-dinal structures in each season. At dusk its S/L variation shows a rough correlation with that of the evening pre-reversal enhancement (PRE) of vertical drift. The dynamo current increases with solar activity. All the results imply that magnetic field data can be a useful proxy for ionospheric E-fields. Precise magnetic observations and accurate models will further improve this technique.

Park, Jaeheung; Luehr, Hermann; Rother, Martin; Min, Kyoung; Michaelis, Ingo

283

Strength distribution of solar magnetic fields in photospheric quiet Sun regions  

E-print Network

The magnetic topology of the solar photosphere in its quietest regions is hidden by the difficulties to disentangle magnetic flux through the resolution element from the field strength of unresolved structures. The observation of spectral lines with strong coupling with hyperfine structure, like the observed MnI line at 553.7 nm, allows such differentiation. The main aim is to analyse the distribution of field strengths in the network and intranetwork of the solar photosphere through inversion of the MnI line at 553.7 nm. An inversion code for the magnetic field using the Principal Component Analysis (PCA) has been developed. Statistical tests are run on the code to validate it. The code has to draw information from the small-amplitude spectral feature oppearing in the core of the Stokes V profile of the observed line for field strengths below a certain threshold, coinciding with lower limit of the Paschen-Back effect in the fine structure of the involved atomic levels. The inversion of the observed profiles, using the circular polarization (V) and the intensity (I), shows the presence of magnetic fields strengths in a range from 0 to 2 kG, with predominant weak strength values. Mixed regions with mean strength field values of 1130 and 435 Gauss are found associated with the network and intranetwork respectively. The MnI line at 553 nm probes the field strength distribution in the quiet sun and shows the predominance of weak, hectoGauss fields in the intranetwork, and strong, kiloGauss fields in the network. It also shows that both network and intranetwork are to be understood at our present spatial resolutions as field distributions of which we hint the mean properties.

J. C. Ramirez Velez; A. Lopez Ariste; M. Semel

2008-06-08

284

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.

285

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

NASA Astrophysics Data System (ADS)

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 of dune crest length, spacing, defect density, and orientation indicates that the pattern is complex, representing two constructional generations of dunes. The oldest and best-organized generation forms the primary crestlines and is transverse to circumpolar easterly winds. Gross bed form-normal analysis of the younger pattern of crestlines indicates that it emerged with both circumpolar easterly winds and NE winds and is reworking the older pattern. Mapping of secondary flow fields over the dunes indicates that the most recent transporting winds were from the NE. The younger pattern appears to represent an influx of sediment to the dune field associated with the development of the Olympia Cavi reentrant, with NE katabatic winds channeling through the reentrant. A model of the pattern reformation based upon the reconstructed primary winds and resulting secondary flow fields shows that the development of the secondary pattern is controlled by the boundary condition of the older dune topography.

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

2010-08-01

286

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

287

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

SciTech Connect

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

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

2011-09-10

288

ARE DECAYING MAGNETIC FIELDS ABOVE ACTIVE REGIONS RELATED TO CORONAL MASS EJECTION ONSET?  

SciTech Connect

Coronal mass ejections (CMEs) are powered by magnetic energy stored in non-potential (current-carrying) coronal magnetic fields, with the pre-CME field in balance between outward magnetic pressure of the proto-ejecta and inward magnetic tension from overlying fields that confine the proto-ejecta. In studies of global potential (current-free) models of coronal magnetic fields-Potential Field Source Surface (PFSS) models-it has been reported that model field strengths above flare sites tend to be weaker when CMEs occur than when eruptions fail to occur. This suggests that potential field models might be useful to quantify magnetic confinement. One straightforward implication of this idea is that a decrease in model field strength overlying a possible eruption site should correspond to diminished confinement, implying an eruption is more likely. We have searched for such an effect by post facto investigation of the time evolution of model field strengths above a sample of 10 eruption sites. To check if the strengths of overlying fields were relevant only in relatively slow CMEs, we included both slow and fast CMEs in our sample. In most events we study, we find no statistically significant evolution in either (1) the rate of magnetic field decay with height, (2) the strength of overlying magnetic fields near 50 Mm, or (3) the ratio of fluxes at low and high altitudes (below 1.1 R{sub Sun }, and between 1.1 and 1.5 R{sub Sun }, respectively). We did observe a tendency for overlying field strengths and overlying flux to increase slightly, and their rates of decay with height to become slightly more gradual, consistent with increased confinement. The fact that CMEs occur regardless of whether the parameters we use to quantify confinement are increasing or decreasing suggests that either (1) the parameters that we derive from PFSS models do not accurately characterize the actual large-scale field in CME source regions, (2) systematic evolution in the large-scale magnetic environment of CME source regions is not, by itself, a necessary condition for CMEs to occur, or both.

Suzuki, J. [Department of Astronomy, University of California, Berkeley, CA 94720-7450 (United States); Welsch, B. T.; Li, Y. [Space Sciences Laboratory, University of California, Berkeley, CA 94720-7450 (United States)

2012-10-10

289

Approach of regional gravity field modeling from GRACE data for improvement of geoid modeling for Japan  

NASA Astrophysics Data System (ADS)

The latest gravimetric geoid model for Japan, JGEOID2004, suffers from errors at long wavelengths (around 1000 km) in a range of +/- 30 cm. The model was developed by combining surface gravity data with a global marine altimetric gravity model, using EGM96 as a foundation, and the errors at long wavelength are presumably attributed to EGM96 errors. The Japanese islands and their vicinity are located in a region of plate convergence boundaries, producing substantial gravity and geoid undulations in a wide range of wavelengths. Because of the geometry of the islands and trenches, precise information on gravity in the surrounding oceans should be incorporated in detail, even if the geoid model is required to be accurate only over land. The Kuroshio Current, which runs south of Japan, causes high sea surface variability, making altimetric gravity field determination complicated. To reduce the long-wavelength errors in the geoid model, we are investigating GRACE data for regional gravity field modeling at long wavelengths in the vicinity of Japan. Our approach is based on exclusive use of inter- satellite range-rate data with calibrated accelerometer data and attitude data, for regional or global gravity field recovery. In the first step, we calibrate accelerometer data in terms of scales and biases by fitting dynamically calculated orbits to GPS-determined precise orbits. The calibration parameters of accelerometer data thus obtained are used in the second step to recover a global/regional gravity anomaly field. This approach is applied to GRACE data obtained for the year 2005 and resulting global/regional gravity models are presented and discussed.

Kuroishi, Y.; Lemoine, F. G.; Rowlands, D. D.

2006-12-01

290

Biochar amendment decreased global warming potential of a Cd/Pb contaminated paddy ecosystem from the Tai Lake plain, China  

NASA Astrophysics Data System (ADS)

Nitrous oxide (N2O), carbon dioxide (CO2) and methane (CH4) are concerned as the predominant biogenic greenhouse gases (GHGs) in the net GHGs balance of agro-ecosystems. Predicting the net exchanges of these gases in a systemic approach would be critical for assessing the effects on GHGs mitigation of environmental conditions and crop management. Previous studies have shown a great potential of biochar amendment to mitigate GHGs emission from croplands. Here, we report a field experiment on biochar effects on rice production, net ecosystem exchange (NEE) and global warming potential (GWP) in cadmium (Cd) and lead (Pb) contaminated paddy field. Biochar was amended in 2009 before rice transplanting at rate of 0, 10, 20 and 40 t ha-1 and soil emission of CO2, ecosystem emissions of CH4 and N2O were monitored with closed chamber method at 7 days interval throughout the whole rice growing season (WRGS) in 2010. Soil samples were collected after rice harvest in 2010 for analysis of soil property changes with biochar amendment. Biochar amendment increased soil pH, soil organic carbon, total N but decreased soil bulk density. DTPA Cd and Pb were decreased by 25.3%, 21.3% and 48.7%, and by 11.9%, 17.3% and 23.6% under biochar amendment at rates of 10 t ha-1, 20 t ha-1 and 40 t ha-1, respectively. Total soil CO2 emission of WRGS was decreased by 16% and 24% under biochar amendment respectively at 20 and 40 t ha-1. There was a weak correlation of total CO2 emission with DTPA Pb concentration (p=0.0642). Total WRGS ecosystem emission of N2O was reduced by 11%, 33% and 50% under biochar amendment at 10 t ha-1, 20 t ha-1 and 40 t ha-1, respectively while an increase by 31% in that of CH4 emission was observed only under biochar amendment at 40 t ha-1.Overall, an consistent increase in ecosystem carbon sink was observed across all treatments of biochar amendment as the overall GWP of the ecosystem was decreased by 54% and 63% under biochar amendment at 20 t ha-1 and 40 t ha-1, respectively. Key words: biochar, net ecosystem exchange, global warming potential, cadmium and lead contaminated paddy field

Zhang, A.; Hussian, Q.; Li, L.; Zheng, J.; Pan, G.; Zhang, X.; Bian, R.

2012-04-01

291

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

292

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

293

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...

294

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...

295

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...

296

Modeling of regional meteorological fields with high spatial resolution for West Siberia  

NASA Astrophysics Data System (ADS)

As well known, global climate changes are inhomogeneous that is most clearly pronounced in the northern regions of the Earth. To study these inhomogeneities and trends, it is necessary to analyze climate changes in the ?? century in the specific region. Now data of different reanalyses (USA, Europe, Japan), as well as observational data from weather stations, are used for such an analysis. Modeling data validity is mostly determined by amount of assimilated measurement data and by weather station network density. For example, for the 2nd edition of USA reanalysis, data of only 300 weather stations of Russian Federation have been used, where most stations are located in European part of the country. Comparison of meteorological fields obtained using reanalysis to measurements of Rosgidromet weather stations gives significant discrepancy. Reanalyses spatial resolution does not allow studying local inhomogeneities that inherent to regional climate changes. Therefore to study local climate dynamics in Siberian region, it is necessary to calculate meteorological fields with higher spatial resolution. Modern mesoscale meteorological models that use reanalyses archives and assimilate measurements of weather stations can solve this problem. We calculated fields of climatic characteristics for West Siberia for the period from 1960 to 2000. The regional weather forecast WRF model (http://www.mmm.ucar.edu/modeling/wrf/index.php) and data assimilation system WRF-VAR (WRFDA) have been installed and debugged on the base of multiprocessor computational complex. Vertical boundary conditions, as well as initial conditions are formed using ERA-40 reanalysis data. NCEP data and USGS map with spatial resolution of 9.25 km are used for the lower boundary, measurements of weather stations, located within calculation area, are used for observation nudging. As a result of the model run, we have meteorological fields, which are reanalysis fields' projections with high spatial resolution (10 km) corrected by weather stations' measurements. Primary analysis of the data obtained allows us to depict changes of climatic characteristics in local areas not as smoothed disturbances (as in reanalysis fields), but as local inhomogeneities that have specific geographical reference to specific regional ecosystem. Key parameters characterizing the main local climate dynamics trends will be chosen for further analysis and processing. The work has been partially supported by SB RAS integration projects Nos. 50 and 66.

Bogomolov, Vasiliy; Gordov, Evgeny

2010-05-01

297

Lignin decomposition and microbial community in paddy soils: effects of alternating redox conditions  

NASA Astrophysics Data System (ADS)

Paddy soils are characterised by interchanging cycles of anaerobic and aerobic conditions. Such fluctuations cause continuous changes in soil solution chemistry as well as in the composition and physiological responses of the microbial community. Temporary deficiency in oxygen creates conditions favourable to facultative or obligates anaerobic bacteria, while aerobic communities can thrive in the period of water absence. These alterations can strongly affect soil processes, in particular organic matter (OM) accumulation and mineralization. In submerged soils, lignin generally constitutes a major portion of the total OM because of hampered degradation under anoxic conditions. The alternating redox cycles resulting from paddy soil management might promote both degradation and preservation of lignin, affecting the overall composition and reactivity of total and dissolved OM. We sampled soils subjected to cycles of anoxic (rice growing period) and oxic (harvest and growth of other crops) conditions since 700 and 2000 years. We incubated suspended Ap material, sampled from the two paddy plus two corresponding non-paddy control soils under oxic and anoxic condition, for 3 months, interrupted by a short period of three weeks (from day 21 to day 43) with reversed redox conditions. At each sampling time (day 2, 21, 42, 63, 84), we determined lignin-derived phenols (by CuO oxidation) as well as phospholipids fatty acids contents and composition. We aimed to highlight changes in lignin decomposition as related to the potential rapid changes in microbial community composition. Since the studied paddy soils had a long history of wet rice cultivation, the microbial community should be well adapted to interchanging oxic and anoxic cycles, therefore fully expressing its activity at both conditions. In non-paddy soil changes in redox conditions caused modification of quantity and composition of the microbial community. On the contrary, in well-established paddy soils the microbial community appeared to be affected by alternating redox conditions more in quantity that in quality. Bacteria represented the largest portion of the living microorganisms, responding promptly to changes in soil redox status. However we did not detect any sign of lignin biodegradation. Relative short (3 weeks) changes in redox conditions had no effect on lignin decomposition or oxidation state. Also, lignin was not altered during oxic incubation. Since fungi represented only small portion of the microbial biomass in the studied soils, they were obviously not capable to cause much degradation, even under favourable conditions. On the contrary, changes in redox conditions strongly affected lignin extractability, regardless of the initial content and direction of change in both paddy and non-paddy soils. This was likely a result of (partial) dissolution and/or pH-induced changes of the surface properties of Fe and Mn hydrous oxides causing the release of mineral-associated lignin-derived phenols. Thus, we speculate that oxidised lignin fragments produced during the (oxic) dry period do not remain in the soils but percolate with water drainage during the flooding period.

Cerli, Chiara; Liu, Qin; Hanke, Alexander; Kaiser, Klaus; Kalbitz, Karsten

2013-04-01

298

Short and long-term greenhouse gas and radiative forcing impacts of changing water management in Asian rice paddies  

Microsoft Academic Search

Fertilized rice paddy soils emit methane while flooded, emit nitrous oxide during flooding and draining transitions, and can be a source or sink of carbon dioxide. Changing water management of rice paddies can affect net emissions of all three of these greenhouse gases. We used denitrification-decomposition (DNDC), a process-based biogeochemistry model, to evaluate the annual emissions of CH4 ,N 2O,

STEVE F ROLKING; C H ANG; R OB B RASWELL

2004-01-01

299

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

300

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

301

Modeling coronal magnetic field using spherical geometry: cases with several active regions  

E-print Network

The magnetic fields in the solar atmosphere structure the plasma, store free magnetic energy and produce a wide variety of active solar phenomena, like flare and coronal mass ejections(CMEs). The distribution and strength of magnetic fields are routinely measured in the solar surface(photosphere). Therefore, there is considerable interest in accurately modeling the 3D structure of the coronal magnetic field using photospheric vector magnetograms. Knowledge of the 3D structure of magnetic field lines also help us to interpret other coronal observations, e.g., EUV images of the radiating coronal plasma. Nonlinear force-free field (NLFFF) models are thought to be viable tools for those task. Usually those models use Cartesian geometry. However, the spherical nature of the solar surface cannot be neglected when the field of view is large. In this work, we model the coronal magnetic field above multiple active regions using NLFFF extrapolation code using vector magnetograph data from the Synoptic Optical Long-term...

Tadesse, Tilaye; Olson, K; MacNeice, P J

2013-01-01

302

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

303

Strength distribution of solar magnetic fields in photospheric quiet Sun regions  

Microsoft Academic Search

The magnetic topology of the solar photosphere in its quietest regions is\\u000ahidden by the difficulties to disentangle magnetic flux through the resolution\\u000aelement from the field strength of unresolved structures. The observation of\\u000aspectral lines with strong coupling with hyperfine structure, like the observed\\u000aMnI line at 553.7 nm, allows such differentiation.\\u000a The main aim is to analyse the

J. C. Ram ´ õrez Velez; A. Lopez Ariste; M. Semel

2008-01-01

304

Experiments on dynamic behavior of near-field region in variable property jet with swirling flow  

Microsoft Academic Search

The dynamic behavior of the near-field region in a coaxial variable property jet has been experimentally investigated under\\u000a a swirling flow produced by rotating cylindrical inner and outer tubes, focusing on how the swirl of the outer jet affects\\u000a the formation of a stagnation point in the swirling inner jet. The inner and outer jets rotate in the same direction.

Suguru Matsubara; Hiroshi Gotoda; Ahmad Adzlan; Toshihisa Ueda

2011-01-01

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

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

307

Magnetic field in Photodissociation Regions (PDRs) : A case study of PDR in NGC 2024  

NASA Astrophysics Data System (ADS)

We present images of C110? and H110? radio recombination line (RRL) emission at 4.8 GHz and images of H166?, C166? and X166? RRL emission at 1.4 GHz, observed toward the starforming region NGC 2024. The 1.4 GHz image with angular resolution ˜ 70 arcsec is obtained using VLA data. The 4.8 GHz image with angular resolution ˜ 17 arcsec is obtained by combining VLA and GBT data. These images reveal that the spatial distributions of C110? line emission is confined to the southern rim of the HII region close to the ionization front whereas the C166? line emission is extended in the north-south direction across the HII region. The LSR velocity of the C110? line is 10.3 kms similar to that of lines observed from molecular material located at the far side of the HII region. This similarity suggests that the photo dissociation region (PDR) responsible for C110? line emission is at the far side of the HII region. The LSR velocity of C166? is 8.8 kms. This velocity is comparable with the velocity of molecular absorption lines observed from the foreground gas, suggesting that the PDR is at the near side of the HII region. Non-LTE models for carbon line forming regions are presented. Typical properties of the foreground PDR are T_{PDR} ˜ 100 K, n_e^{PDR} ˜ 5 &mccedil;three, n_H ˜ 1.7 × 10^4 &mccedil;three, path length l ˜ 0.06 pc and those of the far side PDR are T_{PDR} ˜ 200 K, n_e^{PDR} ˜ 50 &mccedil;three, n_H ˜ 1.7 × 10^5 &mccedil;three, l ˜ 0.03 pc. Our modeling indicates that the far side PDR is located within the HII region. Using the method proposed by Roshi (2007), we estimate magnetic field strength in the foreground PDR to be 60 ?G and that in the far side PDR to be 220 ?G. Our field estimates compare well with the values obtained from OH Zeeman observations toward NGC 2024.

Anish Roshi, D.; Goss, Miller; Jeyakumar, S.

2015-01-01

308

Distribution of the crustal magnetic field in Sichuan-Yunnan region, southwest China.  

PubMed

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

309

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

310

Observations of the longitudinal magnetic field in the transition region and photosphere of a sunspot  

NASA Technical Reports Server (NTRS)

The Ultraviolet Spectrometer and Polarimeter on the Solar Maximum Mission spacraft has observed for the first time the longitudinal component of the magnetic field by means of the Zeeman effect in the transition region above a sunspot. The data presented here were obtained on three days in one sunspot, have spatial resolutions of 10 arcsec and 3 arcsec, and yield maximum field strengths greater than 1000 G above the umbrae in the spot. The method of analysis, including a line-width calibration feature used during some of the observations, is described in some detail in an appendix; the line width is required for the determination of the longitudinal magnetic field from the observed circular polarization. The transition region data for one day are compared with photospheric magnetograms from the Marshall Space Flight Center. Vertical gradients of the magnetic field are compared from the two sets of data; the maximum gradients of 0.41 to 0.62 G/km occur above the umbra and agree with or are smaller than values observed previously in the photosphere and low chromosphere.

Henze, W., Jr.; Tandberg-Hanssen, E.; Hagyard, M. J.; West, E. A.; Woodgate, B. E.; Shine, R. A.; Beckers, J. M.; Bruner, M.; Hyder, C. L.; West, E. A.

1982-01-01

311

Rocket-borne particle, field, and plasma observations in the cleft region. [ionospheric sounding  

NASA Technical Reports Server (NTRS)

Results are reported for comprehensive observations of magnetic and electric fields together with ambient and suprathermal plasmas above the dayside auroral oval with rocket-borne instrumentation which penetrated the cleft region. Measurements were also obtained equatorward and poleward of the cleft. Convection velocities as inferred from electric-field measurements were generally toward noon equatorward of the cleft and were antisunward over the polar cap. Observations of electron temperatures, electric fields, and low-frequency electrostatic noise provide strong evidence of a plasma instability (Farley-Buneman) in the E-layer associated with the appearance of the 'slant E condition' identified in ground-acquired ionograms. The positions of these measurements relative to that of the cleft were firmly established via the determination of the plasma environment with an electrostatic analyzer.

Ungstrup, E.; Bahnsen, A.; Olesen, J. K.; Primdahl, F.; Spangslev, F.; Heikkila, W. J.; Klumpar, D. M.; Winningham, J. D.; Fahleson, U.; Falthammar, C.-G.

1975-01-01

312

[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

313

Filling factors and magnetic field strengths of nanoflare-heated coronal active regions: Yohkoh and MDI observations  

Microsoft Academic Search

The scaling laws describing the relationship between thermal and magnetic properties of active regions are derived using the concept that solar coronal active regions are heated by numerous small flare-like events (nanoflares). Thus, a coronal active region is viewed as an ensemble of hot elementary filaments created within the coronal magnetic field by random impulsive heating events. The scaling laws

R. Jain; S. Yashiro

2002-01-01

314

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

315

Effect of variety and moisture content on some engineering properties of paddy rice  

Microsoft Academic Search

The effect of variety and moisture content on some engineering properties of five improved paddy rice varieties was investigated\\u000a within moisture content range of 10% and 30% dry basis (d.b.). Increase in moisture content was found to increase the linear\\u000a dimensions, mass of 100 seeds, surface area, apparent volume, true volume, arithmetic mean diameter, effective geometric diameter,\\u000a sphericity, angle of

Abdul-Rasaq A. Adebowale; Lateef O. Sanni; Hameed O. Owo; Olayinka R. Karim

2011-01-01

316

Characterization of Microbial Consortia in Paddy Rice Soil by Phospholipid Analysis  

Microsoft Academic Search

Microbial biomass and community structure in paddy rice soil during the vegetation period of rice were estimated by analysis\\u000a of their phospholipid fatty acids (PLFA), hydroxy fatty acids of lipopolysaccharides (LPS-HYFA), and phospholipid ether lipids\\u000a (PLEL) directly extracted from the soil. A clear change in the composition of the community structure at different sampling\\u000a periods was observed, indicated by the

Q. Bai; A. Gattinger; L. Zelles

2000-01-01

317

Biological Nitrogen Fixation by Native Microorganisms in a Waste-Amended Paddy Soil  

Microsoft Academic Search

Biological nitrogen (N2) fixation (BNF) is an important aspect of sustainable and environmentally-friendly food production and long-term crop productivity. It has been established that free-living N2-fixing microbes and Endophytic bacteria play a vital role in the maintenance of soil fertility in flooded rice culture. The potential use of these microorganisms as a natural biofertilizer under an acidic paddy soil was

H. El-Sharkawi; T. Honna; S. Yamamoto; A. Eneji

2007-01-01

318

Effects of paddy water and some photosensitizers on the photolysis of the fungicide isoprothiolane  

Microsoft Academic Search

The fungicide isoprothiolane (diisopropyl l, 3?dithiolan?2?yl?idenemalonate) decomposed slowly in deionized water under ultraviolet light or sunlight irradiation. Rice?paddy water greatly accelerated the photodegradation. This photosensitizing effect was comparable to that of 2% acetone. Soil extracts, rice?plant extracts, and chlorophylls showed little effect for the isoprothiolane photolysis. Tryptophan showed a relatively weak accelerating effect after a considerable lag time. Riboflavin exerted

Morifusa Eto

1980-01-01

319

Artificial Neural Network for Assessment of Grain Losses for Paddy Combine Harvester a Novel Approach  

Microsoft Academic Search

\\u000a Paddy is a staple food for more than 93 countries and it will stay of life for future generations. Harvesting is one of the\\u000a vital operations in crop production and timely harvesting is essential for getting maximum yield. Moisture content and forward\\u000a speed are the two factors to overcome the post harvest losses and minimise the quantitative losses. In this

Sharanakumar Hiregoudar; R. Udhaykumar; K. T. Ramappa; Bijay Shreshta; Venkatesh Meda; M. Anantachar

320

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

321

Increase of available phosphorus by fly-ash application in paddy soils  

SciTech Connect

Fly ash from the coal- burning industry may be a potential inorganic soil amendment to increase rice productivity and to restore the soil nutrient balance in paddy soil. In this study, fly ash was applied at rates of 0, 40, 80, and 120 Mg ha{sup -1} in two paddy soils (silt loam in Yehari and loamy sand in Daegok). During rice cultivation, available phosphorus (P) increased significantly with fly ash application, as there was high content of P (786 mg kg{sup -1}) in the applied fly ash. In addition, high content of silicon (Si) and high pH of fly ash contributed to increased available-P content by ion competition between phosphate and silicate and by neutralization of soil acidity, respectively. With fly-ash application, water-soluble P (W-P) content increased significantly together with increasing aluminum- bound P (Al- P) and calcium- bound P (Ca- P) fractions. By contrast, iron- bound P (Fe- P) decreased significantly because of reduction of iron under the flooded paddy soil during rice cultivation. The present experiment indicated that addition of fly ash had a positive benefit on increasing the P availability.

Lee, C.H.; Lee, H.; Lee, Y.B.; Chang, H.H.; Ali, M.A.; Min, W.; Kim, S.; Kim, P.J. [Gyeongsang National University, Jinju (Republic of Korea). Division of Applied Life Science

2007-07-01

322

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

PubMed

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

Li, Jianrui; Xu, Yingming

2015-03-01

323

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

PubMed

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

Li, Jianrui; Xu, Yingming

2014-11-13

324

Characterization of the IMF By-dependent field-aligned currents in the cleft region based on DE 2 observations  

NASA Technical Reports Server (NTRS)

The magnetic field and plasma data from 47 passes of DE-2 are used to study the IMF By-dependent distribution of field-aligned currents in the cleft region. It is proposed that the low-latitude cleft current (LCC) region is not an extension of the region 1 or region 2 current system and that a pair of LCCs and high-latitude cleft currents (HCCs) constitutes the cleft field-aligned current regime. The proposed pair of cleft field-aligned currents is explained with a qualitative model in which this pair of currents is generated on open field lines that have just been reconnected on the dayside magnetopause. The electric fields are transmitted along the field lines to the ionosphere, creating a poleward electric field and a pair of field-aligned currents when By is positive; the pair of field-aligned currents consists of a downward current at lower latitudes and an upward current at higher latitudes. In the By negative case, the model explains the reversal of the field-aligned current direction in the LCC and HCC regions.

Taguchi, S.; Sugiura, M.; Winningham, J. D.; Slavin, J. A.

1993-01-01

325

Fault patterns in Benin River and Makaraba Fields: A regional play type for the Niger Delta  

SciTech Connect

Using 830 km{sup 2} of excellent 3-D seismic data, we determined the fault patterns that are responsible for hydrocarbon entrapment in the Benin River and Makaraba fields, onshore northwestern Niger Delta. Both fields are trapped downthrown to the major listric GbokoMaka growth fault system, which trends E18{degrees}S for over 40 km, and has at least 2000 m of displacement to the southwest. Several major splay faults break off the main trend in a southeasterly direction, creating a series of fault-bounded structural compartments. Each of these compartments opens to the southeast and has a structural attic at the junction of the splay fault with the main fault trend. These compartments create large-scale traps for hydrocarbons migrating from east to west up the gentle regional dip within the Miocene Ughelli depobelt. The Benin River field is trapped in the major compartment between the GbokoMaka fault and the Benin River splay fault. The large Makaraba field is similarly trapped between the GbokoMaka and MakaWest faults. Such traps require an upthrown fault seal at the master fault and a downthrown fault seal at the splay fault. In the Makamba field, the trap potential is enhanced by rollover into the GbokoMaka fault. The same structural style is also evident along several other major fault trends to the north and the south, and probably represents an important play type in the onshore western Niger delta.

Adeyekun, A.B.; Faparusi, B.D.; Nunns, A.G. [Chevron Nigeria Ltd., Lagos (Nigeria)] [and others

1995-08-01

326

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

327

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

PubMed Central

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

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

2012-01-01

328

Structure of magnetic fields in NOAA active regions 0486 and 0501 and in the associated interplanetary ejecta  

E-print Network

data in order to compare the orientations of the magnetic fields on the solar surface and at 1AU and the strength of the magnetic field in an interplanetary ejecta. A good correspon- dence was also found betweenStructure of magnetic fields in NOAA active regions 0486 and 0501 and in the associated

Yurchyshyn, Vasyl

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

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

331

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

332

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

333

Regional hydrology of the Dixie Valley geothermal field, Nevada: preliminary interpretations of chemical and isotopic data  

SciTech Connect

Chemical and isotopic analyses of Dixie Valley regional waters indicate several distinct groups ranging in recharge age from Pleistocene (<20 ka) to recent (<50a). Valley groundwater is older than water from perennial springs and artesian wells in adjacent ranges, with Clan Alpine range (east) much younger (most <50a) than Stillwater range (west; most >1000a). Geothermal field fluids ({approximately}12-14 ka) appear derived from water similar in composition to non-thermal groundwater observed today in valley artesian wells (also -14 ka). Geothermal fluid interaction with mafic rocks (Humboldt Lopolith) appears to be common, and significant reaction with granodiorite may also occur. Despite widespread occurrence of carbonate rocks, large scale chemical interaction appears minor. Age asymmetry of the ranges, more extensive interaction with deep-seated waters in the west, and distribution of springs and artesian wells suggest the existence of a regional upward hydrologic gradient with an axis in proximity to the Stillwater range.

Counce, D; Dunlap, C; Goff, F; Huebner, M; Janik, C; Johnson, S; Nimz, G

1999-08-16

334

Simulating Turbulent Wind Fields for Offshore Turbines in Hurricane-Prone Regions (Poster)  

SciTech Connect

Extreme wind load cases are one of the most important external conditions in the design of offshore wind turbines in hurricane prone regions. Furthermore, in these areas, the increase in load with storm return-period is higher than in extra-tropical regions. However, current standards have limited information on the appropriate models to simulate wind loads from hurricanes. This study investigates turbulent wind models for load analysis of offshore wind turbines subjected to hurricane conditions. Suggested extreme wind models in IEC 61400-3 and API/ABS (a widely-used standard in oil and gas industry) are investigated. The present study further examines the wind turbine response subjected to Hurricane wind loads. Three-dimensional wind simulator, TurbSim, is modified to include the API wind model. Wind fields simulated using IEC and API wind models are used for an offshore wind turbine model established in FAST to calculate turbine loads and response.

Guo, Y.; Damiani, R.; Musial, W.

2014-04-01

335

Regional frequency analysis conditioned on large-scale atmospheric or oceanic fields  

NASA Astrophysics Data System (ADS)

studies report that hydrologic regimes are modulated by large-scale modes of climate variability such as the El Niño Southern Oscillation (ENSO) or the North Atlantic Oscillation (NAO). Climate-informed frequency analysis models have therefore been proposed to condition the distribution of hydrologic variables on climate indices. However, standard climate indices may be poor predictors in some regions. This paper therefore describes a regional frequency analysis framework that conditions the distribution of hydrologic variables directly on atmospheric or oceanic fields, as opposed to predefined climate indices. This framework is based on a two-level probabilistic model describing both climate and hydrologic data. The climate data set (predictor) is typically a time series of atmospheric of oceanic fields defined on a grid over some area, while the hydrologic data set (predictand) is typically a regional data set of station data (e.g., annual average flow at several gauging stations). A Bayesian estimation framework is used, so that a natural quantification of uncertainties affecting hydrologic predictions is available. A case study aimed at predicting the number of autumn flood events in 16 catchments located in Mediterranean France using geopotential heights at 500 hPa over the North-Atlantic region is presented. The temporal variability of hydrologic data is shown to be associated with a particular spatial pattern in the geopotential heights. A cross-validation experiment indicates that the resulting probabilistic climate-informed predictions are skillful: their reliability is acceptable and they are much sharper than predictions based on standard climate indices and baseline predictions that ignore climate information.

Renard, Benjamin; Lall, Upmanu

2014-12-01

336

Self-aligned graphene field-effect transistors with polyethyleneimine doped source/drain access regions  

NASA Astrophysics Data System (ADS)

We report a method of fabricating self-aligned, top-gated graphene field-effect transistors (GFETs) employing polyethyleneimine spin-on-doped source/drain access regions, resulting in a 2X reduction of access resistance and a 2.5X improvement in device electrical characteristics, over undoped devices. The GFETs on Si/SiO2 substrates have high carrier mobilities of up to 6300 cm2/Vs. Self-aligned spin-on-doping is applicable to GFETs on arbitrary substrates, as demonstrated by a 3X enhancement in performance for GFETs on insulating quartz substrates, which are better suited for radio frequency applications.

Movva, Hema C. P.; Ramón, Michael E.; Corbet, Chris M.; Sonde, Sushant; Fahad Chowdhury, Sk.; Carpenter, Gary; Tutuc, Emanuel; Banerjee, Sanjay K.

2012-10-01

337

Rocket-borne wave, field, and plasma observations in unstable polar cap E-region  

NASA Technical Reports Server (NTRS)

This paper presents initial results from the first comprehensively instrumented rocket flown through a Farley-unstable polar cap E-region. Ground-based ionosondes and magnetometers at two locations and HF radar backscatter at the launch site were used to determine the presence of a geographically widespread ionospheric plasma instability. The observed wave direction, electric field, and current density fit the predictions of the linear theory of the Farley instability, whereas the gradient-drift instability seems to be excluded by the geometry of the observations.

Olesen, J. K.; Primdahl, F.; Spangslev, F.; Ungstrup, E.; Bahnsen, A.; Fahleson, U.; Falthammar, C.-G.; Pedersen, A.

1976-01-01

338

Spatial-Temporal Variation and Primary Ecological Drivers of Anopheles sinensis Human Biting Rates in Malaria Epidemic-Prone Regions of China  

PubMed Central

Background Robust malaria vector surveillance is essential for optimally selecting and targeting vector control measures. Sixty-two vector surveillance sites were established between 2005 and 2008 by the national malaria surveillance program in China to measure Anopheles sinensis human biting rates. Using these data to determine the primary ecological drivers of malaria vector human biting rates in malaria epidemic-prone regions of China will allow better targeting of vector control resources in space and time as the country aims to eliminate malaria. Methods We analyzed data from 62 malaria surveillance sentinel sites from 2005 to 2008. Linear mixed effects models were used to identify the primary ecological drivers for Anopheles sinensis human biting rates as well as to explore the spatial-temporal variation of relevant factors at surveillance sites throughout China. Results Minimum semimonthly temperature (? = 2.99; 95% confidence interval (CI) 2.07- 3.92), enhanced vegetation index (? =1.07; 95% CI 0.11–2.03), and paddy index (the percentage of rice paddy field in the total cultivated land area of each site) (? = 0.86; 95% CI 0.17–1.56) were associated with greater An. Sinensis human biting rates, while increasing distance to the nearest river was associated with lower An. Sinensis human biting rates (? = ?1.47; 95% CI ?2.88, ?0.06). The temporal variation (?t02=1.35) in biting rates was much larger than the spatial variation (?s02=0.83), with 19.3% of temporal variation attributable to differences in minimum temperature and enhanced vegetation index and 16.9% of spatial variance due to distance to the nearest river and the paddy index. Discussion Substantial spatial-temporal variation in An. Sinensis human biting rates exists in malaria epidemic-prone regions of China, with minimum temperature and enhanced vegetation index accounting for the greatest proportion of temporal variation and distance to nearest river and paddy index accounting for the greatest proportion of spatial variation amongst observed ecological drivers. Conclusions Targeted vector control measures based on these findings can support the ongoing malaria elimination efforts in China more effectively. PMID:25611483

Ren, Zhoupeng; Wang, Duoquan; Hwang, Jimee; Bennett, Adam; Sturrock, Hugh J. W.; Ma, Aimin; Huang, Jixia; Xia, Zhigui; Feng, Xinyu; Wang, Jinfeng

2015-01-01

339

Improved confinement region without large magnetohydrodynamic activity in TPE-RX reversed-field pinch plasma  

NASA Astrophysics Data System (ADS)

We found that spontaneous improved confinement was brought about depending on the operating region in the Toroidal Pinch Experiment-Reversed eXperiment (TPE-RX) reversed-field pinch plasma [Y. Yagi et al., Fusion Eng. Des. 45, 421 (1999)]. Gradual decay of the toroidal magnetic field at plasma surface Btw reversal makes it possible to realize a prolonged discharge, and the poloidal beta value and energy confinement time increase in the latter half of the discharge, where reversal and pinch parameters become shallow and low, respectively. In the latter half of the discharge, the plasma current and volume-averaged toroidal magnetic field increase again, the electron density slowly decays, the electron temperature and soft X-ray radiation intensity increase, and the magnetic fluctuations are markedly reduced. In this period of improved confinement, the value of (-Btw)/Bpw, where Bpw is the poloidal magnetic field at the plasma surface, stays almost constant, which indicates that the dynamo action occurs without large magnetohydrodynamic activities.

Yambe, Kiyoyuki; Hirano, Yoichi; Sakakita, Hajime; Koguchi, Haruhisa

2014-11-01

340

Reconstruction of the solar coronal magnetic field, from active region to large scale  

NASA Astrophysics Data System (ADS)

The low solar corona is dominated by the magnetic field which is created inside the sun by a dynamo process and then emerges into the atmosphere. This magnetic field plays an important role in most structures and phenomena observed at various wavelengths such as prominences, small and large scale eruptive events, and continuous heating of the plasma, and therefore it is important to understand its three-dimensional properties in order to elaborate efficient theoretical models. Unfortunately, the magnetic field is difficult to measure locally in the hot and tenuous corona. But this can be done at the level of the cooler and denser photosphere, and several instruments with high resolution vector magnetographs are currently available (THEMIS, Imaging Vector Magnetograph (IVM), the Advanced Stokes Polarimeter (ASP), SOLIS, HINODE, Solar Dynamics Observatory (SDO), or will be shortly available by future telescopes such as EST and solar missions as SOLAR-ORBITER. This has lead solar physicists to develop an approach which consists in " reconstructing" the coronal magnetic field from boundary data given on the photosphere. We will discuss some of the issues encountered in solving this problem as well our recent progress and results at the scale of active region scales or the larger one such as full sun scale.

Amari, T.; Canou, A.; Delyon, F.; Aly, J. J.; Frey, P.; Alauzet, F.

2011-12-01

341

The Interplay of Turbulence and Magnetic Fields in Star-Forming Regions: Simulations and Observations  

NASA Astrophysics Data System (ADS)

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 (?0 = 0.5) and supercritical (?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 ~1 pc) to match that observed across extinction regions in Perseus. Generally, the simulated core (~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; Basu, Shantanu

2009-07-01

342

Radar observations of artificial E-region field-aligned irregularities  

NASA Astrophysics Data System (ADS)

Artificial E region field aligned plasma density irregularities (FAIs) were generated using HAARP in four different experimental modes and observed with a coherent scatter radar imager located 450 km to the southwest where it could detect field-aligned backscatter. The experiments were conducted in July of 2008, during the Polar Aeronomy and Radio Science Summer School (PARS), during quiet conditions in the daytime when the E layer was dense and absorption was modest. The echoes observed during zenith and magnetic zenith heating experiments were deflected from their nominally anticipated horizontal positions toward the midpoint position. The occurrence of hysteresis when heating with amplitude modulated pulses implied the development of the resonance instability, although the threshold for the onset of instability appeared to be higher than what has been predicted theoretically. Heating experiments involving pump frequencies slightly above and below the second electron gyroharmonic frequency produced no significant differences in the observed echoes. Finally, heating with a pump frequency slightly above the E region critical frequency appears to have produced FAIs at two distinct altitudes where the upper-hybrid resonance condition could be satisfied.

Nossa, E.; Hysell, D. L.; Fallen, C. T.; Watkins, B. J.

2009-07-01

343

Explosive events in connection with small scale flux emergence in open field regions  

NASA Astrophysics Data System (ADS)

In recent years observations have shown that the emergence of new magnetic flux from the convection zone into the open field regions in the corona may generate spectacular jet phenomena. A smaller number of jets seem to end their near steady state phase in one or more spectacular eruptions where material is accelerated away from the solar surface reaching fairly high velocities. To investigate the jet phenomena, we have conducted a number of numerical MHD experiments that investigate the general interaction between an emerging bipolar flux region and the open coronal magnetic field. Under the correct conditions, this generates a well defined jet phase and the model explains many of the general characteristics of the typical Eiffel tower jets. Towards the end phase of the jet, the remains of the emerged flux system may experience some violent eruptions. This talk will discuss the general characteristics of these eruptions, aiming at providing an explanation to why they occur, and how they develop in general. These jets and eruptions may be what is taking place in some of the so-called breakout models described in a number of recent observational papers.

Galsgaard, Klaus; Moreno-Insertis, Fernando, , Prof

344

Speciation and Release Kinetics of Cadmium in Alkali and Acidic Paddy Soils: Application of X-Ray Absorption Spectroscopy Monday, November 2, 2009: 10:30 AM  

E-print Network

and S speciation in alkaline and acidified Cd-Zn co-contaminated paddy soils. Bulk extended X-ray absorption fine species in the alkaline soil, while CdS and CdCO3 are the major species in the acidified soil. XSpeciation and Release Kinetics of Cadmium in Alkali and Acidic Paddy Soils: Application of X

Sparks, Donald L.

345

Long-term nitrogen fertilization of paddy soil shifts iron-reducing microbial community revealed by RNA-(13)C-acetate probing coupled with pyrosequencing.  

PubMed

Iron reduction is an important biogeochemical process in paddy soils, yet little is known about the microbial coupling between nitrogen and iron reduction. Here, we investigated the shift of acetate-metabolizing iron-reducers under long-term nitrogen fertilization using (13)C-acetate-based ribosomal RNA (rRNA)-stable isotope probing (SIP) and pyrosequencing in an incubation experiment, and the shift of putative iron-reducers in original field samples were investigated by 16S rRNA gene-based pyrosequencing. During SIP incubations, in the presence of iron(III) oxyhydroxides, more iron(II) formation and less methane production were detected in nitrogen-fertilized (N) compared with non-fertilized (NF) soil. In (13)C-rRNA from microcosms amended with ferrihydrite (FER), Geobacter spp. were the important active iron-reducers in both soils, and labeled to a greater extent in N (31% of the bacterial classified sequences) than NF soils (11%). Pyrosequencing of the total 16S rRNA transcripts from microcosms at the whole community level further revealed hitherto unknown metabolisms of potential FER reduction by microorganisms including Pseudomonas and Solibacillus spp. in N soil, Dechloromonas, Clostridium, Bacillus and Solibacillus spp. in NF soil. Goethite (GOE) amendment stimulated Geobacter spp. to a lesser extent in both soils compared with FER treatment. Pseudomonas spp. in the N soil and Clostridium spp. in the NF soil may also be involved in GOE reduction. Pyrosequencing results from field samples showed that Geobacter spp. were the most abundant putative iron-reducers in both soils, and significantly stimulated by long-term nitrogen fertilization. Overall, for the first time, we demonstrate that long-term nitrogen fertilization promotes iron(III) reduction and modulates iron-reducing bacterial community in paddy soils. PMID:25171335

Ding, Long-Jun; Su, Jian-Qiang; Xu, Hui-Juan; Jia, Zhong-Jun; Zhu, Yong-Guan

2015-03-01

346

Integral field spectroscopy of HII region complexes: the outer disc of NGC6946  

NASA Astrophysics Data System (ADS)

Integral field spectroscopy obtained with the Potsdam Multi-Aperture Spectrophotometer Fiber Package (PPak) and the 3.5-m telescope at the Calar Alto Observatory has been used to study an outer HII region complex in the well-studied galaxy NGC6946. This technique provides detailed maps of the region in different emission lines, yielding spatially resolved information about the physical properties of the gas. The configuration was chosen to cover the whole spectrum from 3600 up to 10000Å, allowing the measurement of the near-infrared [SIII] lines. We selected four luminous knots to perform a detailed integrated spectroscopic analysis of these structures and of the whole PPak field of view (FOV). For all the knots the electron density has been found to be very similar and below 100cm-3. The [OIII] electron temperature was measured in knots A, B, C and in the integrated PPak field, and was found to be around 8000K. The temperatures of [OII] and [SIII] were estimated in the four cases. The elemental abundances computed from the `direct method' are typical of high-metallicity disc HII regions, with a mean value of 12+log(O/H) = 8.65, comparable to what has been found in this galaxy by other authors for regions at similar galactocentric distance. Therefore a remarkable abundance uniformity is found despite the different excitations found throughout the nebula. However, due to the quality of the data, the electron temperatures and metallicities obtained have associated errors comparable to the typical dispersion found in empirical calibrations. Wolf-Rayet (WR) features have been detected in three of the knots, leading to a derived total number of WR stars of 125, 22 and 5 for knots A, C and B, respectively. The ratios of the numbers of WR to O stars are consistent with the prediction of Starburst99 for individual bursts with an age about 4Myr. Knot D, with no WR features, shows weak H? emission, low excitation and the lowest H? equivalent width, all of which points to a more evolved state. The integrated spectrum of the whole PPak FOV shows high excitation and a relatively evolved age that does not correspond to the individual knot evolutionary stages. Some effects associated with the loss of spatial resolution are also evidenced by the higher ionizing temperature that is deduced from the ?' parameter measured in the integrated PPak spectrum with respect to that of the individual knots.

García-Benito, R.; Díaz, A.; Hägele, G. F.; Pérez-Montero, E.; López, J.; Vílchez, J. M.; Pérez, E.; Terlevich, E.; Terlevich, R.; Rosa-González, D.

2010-11-01

347

[Study of exciton generation region of phosphorescent light emitting devices based on the changing electric field].  

PubMed

The changes of exciton generation region are influenced by varying electric field, which affect the color and efficiency performance of devices. Firstly, The authors fabricated two types of phosphorescent light emitting devices, device 1:ITO/PEDOT : PSS/PVK : Ir(ppy)s : DCJTB (100:2:1 wt)/BCP(10 nm)/Alq3 (15 nm)/Al, and device 2: ITO/PEDOT : PSS/ PVK : Ir(ppy)3 (100:2 wt)/BCP (10 nm)/Alq3(15 nm)/Al. The authors investigated the influences of electric field on exciton generation region in single-layer and multi-doped structure devices. Analysis of the electroluminescence spectrum under different voltages indicates that the emitting of Ir(ppy)3, PVK and DCJTB was enhanced with the increase in applied voltages. Compared to Ir(ppy)3, the emitting of PVK and DCJTB was prominently enhanced. This is because under high electric field it is easier high energy carrier to generate high energy exciton, and the emitting of wide-band-gap material PVK is stronger; on the other hand, the authors investigated the results from the aspect of energy band gap. DCJTB is narrow-band-gap material, which can capture carrier comparatively easily and emit stronger light. At the same time, we obtained a new emission peak located at 460 nm, which becomes comparatively weak with increasing voltage. In order to explore the reason, we fabricated the device: ITO/ PEDOT: PSS/PVK : BCP : Ir(ppy)3 (x:y:2 wt)/Alq3 (15 nm)/Al. The 460 nm emission peak doesn't disappear by changing the mass ratio of x and y. The authors speculate that the emission peak relates to PVK and BCP. PMID:19950620

Liu, Xu-dong; Zhao, Su-ling; Song, Dan-dan; Zhan, Hong-ming; Yuan, Guang-cai; Xu, Zheng

2009-09-01

348

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

349

Reconnaissance of ground-water resources in the Western Coal Field Region, Kentucky  

USGS Publications Warehouse

In the Western Coal Field region of Kentucky, water is obtained from consolidated sedimentary rocks of Mississippian and Pennsylvanian ages and from unconsolidated sediments of Cenozoic age. Pennsylvanian rocks crop out in more than 95 percent of the area and consist of shale and sandstone interbedded with some limestone and coal. The Pennsylvanian strata are divided into five formations. They are, in ascending order: the Caseyville sandstone and the Tradewater, Carbondale, Lisman, and Henshaw formations. The Anvil Rock sandstone member of the Lisman formation and the Caseyville sandstone are the only bedrock aquifers in the region that are known to yield more than 100 gpm (gallons per minute) to wells. Most bedrock wells produce enough water for a modern domestic supply, more than 500 gpd (gallons per day), and few yield so little water as to be inadequate for hand pumps and bailers, less than 100 gpd. Unconsolidated Cenozoic deposits range from latest Pliocene(?) to Recent in age and consist of clay, silt, sand, and gravel. High gravels, tentatively considered to be late Pliocene and early Pleistacene in age by McFarlan (1950, p. 125), and loess of Pleistocene age are locally exposed, but nearly all of the alluvium is of late Pleistocene and Recent ages. The alluvium along the Ohio River generally yields from a few hundred to as much as 1,000 gpm to single vertical wells and as much as several thousand gallons per minute to wells that have multiple horizontal screens. Alluvium in the tributaries of the Ohio River generally is finer grained than that of the Ohio Valley. The highest known yield from a well in the alluvium of the tributaries is 56 gpm; other wells yield enough for domestic supplies. Availability of ground water in the region depends on the character and thickness of the aquifer penetrated, and, where the aquifer is bedrock on the depth of the water-bearing bed, and to a certain extent on the topographic situation. Most bedrock aquifers in the Western Coal Field region are sandstone and may vary greatly in thickness and composition within short distances. The region is divided into five areas of ground-water availability. Area 1 is confined to the Ohio Valley, most of which is underlain by relatively thick sections of sand and gravel that yield at least 50 gpm to most wells at depths of less than 150 feet. In area 2 most wells yield enough water for a modern domestic supply from depths of less than 300 feet. This area includes the largest part of the bedrock outcrop in the region, some of the alluvial area along the Ohio River, and much of the alluvial areas along the larger tributaries. In area 3 most wells yield enough water from depths of less than 300 feet to supply domestic needs when a hand pump is used. This area covers the bedrock parts of the region that are underlain by shale, sandy shale, and limestone, and the section where few wells are known to yield large supplies of water. In area 4 most wells fail to supply enough water for domestic use from depths of less than 300 feet, probably because they penetrate thick sections of unfractured shale or well-cemented sandstone. In area 5 the yield of wells is unpredictable, commonly because of faulting. The water in the shallow bedrock aquifers of the region is mostly of the sodium bicarbonate or the calcium bicarbonate type. Saline water has been encountered at depths as shallow as 100 feet, but fresh water has been obtained at depths approaching 1,000 feet. Water from the bedrock is soft to moderately hard, but it may contain undesirable amounts of iron. Most water from the alluvium is of the calcium bicarbonate type and is generally harder and contains more iron than water from the bedrock.

Maxwell, Bruce William; Devaul, Robert Washburn

1962-01-01

350

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

351

The Three-Dimensional Structure of Magnetic Fields and Electric Currents in an Active Region  

NASA Astrophysics Data System (ADS)

Active Region NOAA 9661 consisting of various magnetic features (alpha spot, delta spot, pores, and plages) was observed simultaneously in three spectral lines (FeI 630.25, 630.15, and MgI 517.27) using full Stokes spectro-polarimetry with Advanced Stokes Polarimeter at NSO/SP. The formation heights of the three spectral lines span from photosphere to the low chromosphere. The magnetic field vectors are inverted from Stokes parameters using advanced inversion codes. In particular, HeLIx code is used to invert MgI's observation because it is dedicated for chromospheric Stokes inversion. The inverted magnetic field vectors in multiple atmospheric layers enable us to derive the three dimensional structure of the magnetic fields, electric current densities, current helicities, and their height gradients. Acknowledgments: This work is supported by NASA under grants NNX08AQ32G and NNX08AQ89G, and by NSF under grants ATM 05-48952 and ATM 07-16950.

Deng, Na; Choudhary, D.; Lagg, A.; Jing, J.; Wang, H.

2009-05-01

352

A quantum cascade laser in a transverse magnetic field. A model of the open triple-barrier active region  

NASA Astrophysics Data System (ADS)

A theory of spectral parameters and active dynamic conductivity of the quantum cascade laser is proposed in the model of a triple-barrier active region of an individual cascade in a transverse magnetic field. In correspondence with the experiment, it is shown that, with an increase in the magnetic field to 8 T, the radiation peak is shifted to the region of higher energies and its integral intensity sharply decreases.

Tkach, N. V.; Boyko, I. V.; Seti, Ju. A.; Zegrya, G. G.

2013-06-01

353

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

354

Studies on mosquitoes (Diptera: Culicidae) and anthropic environment. 5--breeding of Anopheles albitarsis in flooded rice fields in south-eastern Brazil.  

PubMed

Studies on breeding Anopheles albitarsis and association with rice growth in irrigated paddy fields were carried out during the rice cultivation cycle from December 1993 to March 1994. This period corresponded to the length of time of permanent paddy flooding. Breeding occurred in the early stage up until five weeks after transplantation when rice plant height was small. That inverse correlation may give potential direction to control measures. PMID:7660032

Forattini, O P; Kakitani, I; Massad, E; Marucci, D

1994-10-01

355

Effects of water-saving irrigation practices and drought resistant rice variety on greenhouse gas emissions from a no-till paddy in the central lowlands of China.  

PubMed

As pressure on water resources increases, alternative practices to conserve water in paddies have been developed. Few studies have simultaneously examined the effectiveness of different water regimes on conserving water, mitigating greenhouse gases (GHG), and maintaining yields in rice production. This study, which was conducted during the drought of 2013, examined all three factors using a split-plot experiment with two rice varieties in a no-till paddy managed under three different water regimes: 1) continuous flooding (CF), 2) flooded and wet intermittent irrigation (FWI), and 3) flooded and dry intermittent irrigation (FDI). The Methane (CH?) and nitrous oxide (N?O) emissions were measured using static chamber-gas measurements, and the carbon dioxide (CO?) emissions were monitored using a soil CO? flux system (LI-8100). Compared with CF, FWI and FDI irrigation strategies reduced CH? emissions by 60% and 83%, respectively. In contrast, CO? and N?O fluxes increased by 65% and 9%, respectively, under FWI watering regime and by 104% and 11%, respectively, under FDI managed plots. Although CO? and N?O emissions increased, the global warming potential (GWP) and greenhouse gas intensity (GHGI) of all three GHG decreased by up to 25% and 29% (p<0.01), respectively, using water-saving irrigation strategies. The rice variety also affected yields and GHG emissions in response to different water regimes. The drought-resistance rice variety (HY3) was observed to maintain yields, conserve water, and reduce GHG under the FWI irrigation management compared with the typical variety (FYY299) planted in the region. The FYY299 only had significantly lower GWP and GHGI when the yield was reduced under FDI water regime. In conclusion, FWI irrigation strategy could be an effective option for simultaneously saving water and mitigating GWP without reducing rice yields using drought-resistant rice varieties, such as HY3. PMID:25461105

Xu, Ying; Ge, Junzhu; Tian, Shaoyang; Li, Shuya; Nguy-Robertson, Anthony L; Zhan, Ming; Cao, Cougui

2015-02-01

356

REALISTIC NON-LINEAR MODEL AND FIELD QUALITY ANALYSIS IN RHIC INTERACTION REGIONS.  

SciTech Connect

The existence of multipole components in the dipole and quadrupole magnets is one of the factors limiting the beam stability in the RHIC operations. So, a realistic non-linear model is crucial for understanding the beam behavior and to achieve the ultimate performance in RHIC. A procedure is developed to build a non-linear model using the available multipole component data obtained from measurements of RHIC magnets. We first discuss the measurements performed at different stages of manufacturing of the magnets in relation to their current state in RHIC. We then describe the procedure to implement these measurement data into tracking models, including the implementation of the multipole feed down effect due to the beam orbit offset from the magnet center. Finally, the field quality analysis in the RHIC interaction regions (IR) is presented.

BEEBE-WANG,J.; JAIN, A.

2007-06-25

357

A Near-IR Spectroscopic Survey of the Central Regions of Field Ellipticals  

NASA Astrophysics Data System (ADS)

We propose to obtain central region K-band spectra for a sample of N ~ 30 field elliptical galaxies. An analysis of the central near-IR colors of these galaxies suggests that some of these galaxies may contain first-ascent giant branches (FGB) similar to the unusual FGB seen in the metal-rich Galactic globular clusters Liller 1 and NGC 6440. We wish to test this hypothesis by measuring the equivalent widths of the Na I 2.207(micron) and Ca I 2.263(micron) as well as the CO 2.36(micron) index. These new EW and CO index measurements will be compared to previously published data for K and M giants in the Local Solar Neighborhood, Baade's Window, and the Liller 1 and NGC 6440 clusters.

Silva, David; Bothun, Gregory

1999-02-01

358

Effects of alternating wetting and drying versus continuous flooding on chromium fate in paddy soils.  

PubMed

Anthropogenic chromium (Cr) pollution in soils poses a great threat to human health through the food chain. It is imperative to understand Cr fate under the range of conditions suitable for rice growth. In this study, the effects of irrigation managements on dynamics of porewater Cr(VI) concentrations in rice paddies and Cr distribution in rice were investigated with pot experiments under greenhouse conditions. Soil redox potential in continuous flooding (CF) treatments showed that reducing conditions remained for the whole duration of rice growing period, while soil redox potential in alternating wetting and drying (AWD) treatments showed that soil conditions alternately changed between reducing and oxic. As soil redox potential is an important factor affecting Cr(VI) reduction in paddy soils, dynamics of Cr(VI) concentration were clearly different under different irrigation managements. In CF treatments, porewater Cr(VI) concentrations decreased with time after planting, while in AWD treatments porewater Cr(VI) concentrations were increased and decreased alternately response to the irrigation cycles. Chromium(VI) concentrations in the CF treatments were lower than those in AWD treatments for most part of rice-growing season. Moreover, Cr concentrations in rice tissues were significantly influenced by irrigation with relatively higher values in the AWD treatments, which might be attributed to the higher porewater Cr(VI) concentrations in AWD treatments. Therefore, it would be better to use CF than AWD management in Cr-contaminated paddy soils to reduce Cr accumulation in rice, and thus to reduce the potential risk to human health. PMID:25546832

Xiao, Wendan; Ye, Xuezhu; Yang, Xiaoe; Li, Tingqiang; Zhao, Shouping; Zhang, Qi

2015-03-01

359

Cattle Manure Enhances Methanogens Diversity and Methane Emissions Compared to Swine Manure under Rice Paddy.  

PubMed

Livestock manures are broadly used in agriculture to improve soil quality. However, manure application can increase the availability of organic carbon, thereby facilitating methane (CH4) production. Cattle and swine manures are expected to have different CH4 emission characteristics in rice paddy soil due to the inherent differences in composition as a result of contrasting diets and digestive physiology between the two livestock types. To compare the effect of ruminant and non-ruminant animal manure applications on CH4 emissions and methanogenic archaeal diversity during rice cultivation (June to September, 2009), fresh cattle and swine manures were applied into experimental pots at 0, 20 and 40 Mg fresh weight (FW) ha-1 in a greenhouse. Applications of manures significantly enhanced total CH4 emissions as compared to chemical fertilization, with cattle manure leading to higher emissions than swine manure. Total organic C contents in cattle (466 g kg-1) and swine (460 g kg-1) manures were of comparable results. Soil organic C (SOC) contents were also similar between the two manure treatments, but dissolved organic C (DOC) was significantly higher in cattle than swine manure. The mcrA gene copy numbers were significantly higher in cattle than swine manure. Diverse groups of methanogens which belong to Methanomicrobiaceae were detected only in cattle-manured but not in swine-manured soil. Methanogens were transferred from cattle manure to rice paddy soils through fresh excrement. In conclusion, cattle manure application can significantly increase CH4 emissions in rice paddy soil during cultivation, and its pretreatment to suppress methanogenic activity without decreasing rice productivity should be considered. PMID:25494364

Kim, Sang Yoon; Pramanik, Prabhat; Bodelier, Paul L E; Kim, Pil Joo

2014-01-01

360

Microbiological biodiversity in poultry and paddy straw wastes in composting systems  

PubMed Central

Immense quantity of waste is generated in association with poultry meat egg and crop production. The potential risks due to disposal of these wastes are magnified as a result of dense refinement of poultry production and the decreasing amount of land available for waste disposal. The study aims at studying the microbiological biodiversity of poultry waste and paddy straw based co-composting system. The predominant microflora of the poultry manure were bacteria, fungi, enteric bacteria and spore forming bacteria whose population was high at the initiation of composting but decreased significantly as the compost approached maturity. The initial load of inherent enteric groups of bacteria in poultry waste, that also includes some pathogenic ones, is considerably reduced and some new vital groups contributed to compost quality as the microbiological biodiversity sets in the system and becomes stable. Major fraction of nitrogen of poultry waste was subjected to ammonia volatilization and a fraction of it conserved by co-composting it in conjunction with wastes having low nitrogen contents. In the treatment T1 and T5, where poultry manure and paddy straws alone were composted, 60 and 30 percent of organic carbon, respectively, was lost over a period of six months. Whereas in treatments T2,T3 and T4, poultry manure and paddy straw were co-composted in the ratio of 3:1, 2:2 and 1:3, respectively, 51.4,45.0 and 37.0 percent of carbon, respectively, was lost during decomposition. The C: N ratio in all the treatments decreased significantly to 18.3 for T1, 24.7 for T2, 27.0 for T3, 34.9 for T4 and 38.5 for T5 at the end of composting period. PMID:24031831

Devi, Sunita; Sharma, C.R.; Singh, Kamlesh

2012-01-01

361

Cattle Manure Enhances Methanogens Diversity and Methane Emissions Compared to Swine Manure under Rice Paddy  

PubMed Central

Livestock manures are broadly used in agriculture to improve soil quality. However, manure application can increase the availability of organic carbon, thereby facilitating methane (CH4) production. Cattle and swine manures are expected to have different CH4 emission characteristics in rice paddy soil due to the inherent differences in composition as a result of contrasting diets and digestive physiology between the two livestock types. To compare the effect of ruminant and non-ruminant animal manure applications on CH4 emissions and methanogenic archaeal diversity during rice cultivation (June to September, 2009), fresh cattle and swine manures were applied into experimental pots at 0, 20 and 40 Mg fresh weight (FW) ha?1 in a greenhouse. Applications of manures significantly enhanced total CH4 emissions as compared to chemical fertilization, with cattle manure leading to higher emissions than swine manure. Total organic C contents in cattle (466 g kg?1) and swine (460 g kg?1) manures were of comparable results. Soil organic C (SOC) contents were also similar between the two manure treatments, but dissolved organic C (DOC) was significantly higher in cattle than swine manure. The mcrA gene copy numbers were significantly higher in cattle than swine manure. Diverse groups of methanogens which belong to Methanomicrobiaceae were detected only in cattle-manured but not in swine-manured soil. Methanogens were transferred from cattle manure to rice paddy soils through fresh excrement. In conclusion, cattle manure application can significantly increase CH4 emissions in rice paddy soil during cultivation, and its pretreatment to suppress methanogenic activity without decreasing rice productivity should be considered. PMID:25494364

Kim, Sang Yoon; Pramanik, Prabhat; Bodelier, Paul L. E.; Kim, Pil Joo

2014-01-01

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

Tropical E region field aligned irregularities: Simultaneous observations of continuous and quasiperiodic echoes  

NASA Astrophysics Data System (ADS)

The antenna beam at 13°N off zenith direction of the Indian mesosphere-stratosphere-troposphere (MST) radar at Gadanki (13.5°N, 79.2°E) is orthogonal to geomagnetic field lines at 110 km altitude. This beam was used to observe E region field-aligned irregularities during July-August 1994, February and June 1996, and July-September 1997 with a range resolution of 600 m. On a few occasions the radar was operated at 150 m range resolution also. Observations showed continuous and multiple echo regions during nighttime. However, out of the 15 nights of observations, quasiperiodic (QP) echoes were also detected on the nights of July 20-21, 1994, and September 3-4, 1997. In this paper, major features of these quasiperiodic echoes in the form of height-time maps of echo intensity are presented. On July 20-21, 1994, quasiperiodic echoes with a periodicity of about 2-4 min from the altitude between 102 and 116 km appeared as tilted striations in the height-time-intensity maps. The rate of descent of altitude associated with these tilted striations was in the range of 40-60 m s-1. The fluctuations in the Doppler velocity along the length of striations resembled a wave structure with vertical wavelength of the order of 18-20 km. Observations on September 3-4, 1997, suggest that these high-frequency waves initially modulate the Es layer up to an altitude as high as 120 km and produce the quasiperiodic variation in the echoes. As time progresses, the period of QP echoes as well as the echo expanse decreases, and finally the normal continuous layer emerges.

Choudhary, R. K.; Mahajan, K. K.

1999-02-01

364

Dependence of spectral width of ionospheric F region HF echoes on electric field  

NASA Astrophysics Data System (ADS)

The EISCAT Svalbard radar (ESR) monitors plasma parameters in the ionospheric region that is frequently located near the polar cap boundary. The SuperDARN radar at Hankasalmi, Finland, detects coherent echoes from this region, and these echoes typically show increased spectral width. We consider data of joint ESR and SuperDARN observations to show that the spectral width of HF echoes tends to increase with the ionospheric electric field. This relationship is explained in terms of nonlinear evolution of the E × B gradient drift instability with energy cascade from hundreds of meter wavelengths to meter wavelengths. We assume that decameter waves (seen by the Hankasalmi radar) with relatively large amplitude decay through a three-wave interaction with shorter wavelengths and estimate that the decay time of the decameter waves/irregularities is determined by the parameters of the shorter-wavelength structures. We associate the decameter wave decay time with the correlation time, and thus the spectral width, of HF echoes.

Kozlovsky, A.; Shalimov, S.; Koustov, A. V.; Lukianova, R.; Turunen, T.

2011-07-01

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

Monitoring and Modeling Water and Energy Fluxes in North China Plain: From Field to Regional Scales  

NASA Astrophysics Data System (ADS)

North China Plain is one of the mostly water deficit region in the world. Even though the total water withdrawal from surface and groundwater exceeded its renewable ability for long years, due to its importance to balance the food budget in China, large amount of groundwater is still extracted every year for intensive irrigation. With winter wheat and summer maize double-cropping system, the grain yield of NCP can reach a very high level of around 15 t/ha annually, which is largely depended on timely irrigation. As a result, the ceaseless over exploitation of groundwater caused serious environmental and ecological problems, e.g. nearly all the rivers run drying-up at plain areas, groundwater declined, land subsidence, and wetland shrank. The decrease in precipitation over past half century reinforced the water shortage in NCP. The sustainability of both the water resources and agriculture became the most important issue in this region. A key issue to the sustainable use of water resources is to improve the water use efficiency and reduce agricultural water consumptions. This study will introduce the efforts we put to clarify the water and heat balances in irrigated agricultural lands and its implications to crop yield, hydrology, and water resources evolution in NCP. We established a multi-scale observation system in NCP to study the surface water and heat processes and agricultural aspect of hydrological cycle in past years. Multi-disciplinary methods are adopted into this research such as micro-meteorologic, isotopic, soil hydrologic methods at the field scale, and remote sensing and modeling for study the water fluxes over regional scale. Detailed research activities and interesting as well as some initial results will be introduced at the workshop.

Shen, Y.

2012-12-01

367

Soil Solution Sampling for Organic Acids in Rice Paddy Soils  

Microsoft Academic Search

Low molecular weight organic acids (OA), which are intermediates in the anaerobic decomposition of straw incorporated into submerged soils, have been implicated in causing toxicity to young rice (Oryza sativa L.) seedlings. The objective of this study was to develop a method for measuring OA in soil solution in field and greenhouse studies. Three methods of soil solution sampling were

Olivyn R. Angeles; Sarah E. Johnson; Roland J. Buresh

2005-01-01

368

Spatio-Temporal Scaling of Turbulent Photospheric Line-of-Sight Magnetic Field in Active Region NOAA 11158  

NASA Astrophysics Data System (ADS)

We studied the structure and dynamics of the turbulent photospheric magnetic field in active region NOAA 11158 by characterizing spatial and temporal scaling properties of the line-of-sight (LOS) component. Using high-resolution high-cadence LOS magnetograms from SDO/HMI, we measured the power-law exponents ? and ? that describe Fourier power spectra in wavenumber ( k) and frequency ( f) domains, and we investigated their evolution during the passage of the active region through the field of view of HMI. The flaring active region NOAA 11158 produces a one-dimensional spatial power spectral density that approximately follows a k -2 power law - a spectrum that suggests parallel MHD fluctuations in an anisotropic turbulent medium. In addition, we found that the values of ? capture systematically change in the configuration of the LOS photospheric magnetic field during flaring activity in the corona. Position-dependent values of the temporal scaling exponent ? showed that, on an average, the core of the active region scales with ?>3 surrounded by a diffusive region with an approximately f -2-type spectrum. Our results indicate that only about 1 - 3 % of the studied LOS photospheric magnetic flux displays ?? ?, implying that Taylor's hypothesis of frozen-in-flow turbulence is typically invalid for this scalar field in the presence of turbulent photospheric flows. In consequence, both spatial and temporal variations of the plasma and magnetic field must be included in a complete description of the turbulent evolution of active regions.

Guerra, J. A.; Pulkkinen, A.; Uritsky, V. M.; Yashiro, S.

2015-02-01

369

Thermodynamic coupling of heat and matter flows in near-field regions of nuclear waste repositories  

SciTech Connect

In near-field regions of nuclear waste repositories, thermodynamically coupled flows of heat and matter can occur in addition to the independent flows in the presence of gradients of temperature, hydraulic potential, and composition. The following coupled effects can occur: thermal osmosis, thermal diffusion, chemical osmosis, thermal filtration, diffusion thermal effect, ultrafiltration, and coupled diffusion. Flows of heat and matter associated with these effects can modify the flows predictable from the direct effects, which are expressed by Fourier's law, Darcy's law, and Fick's law. The coupled effects can be treated quantitatively together with the direct effects by the methods of the thermodynamics of irreversible processes. The extent of departure of fully coupled flows from predictions based only on consideration of direct effects depends on the strengths of the gradients driving flows, and may be significant at early times in backfills and in near-field geologic environments of repositories. Approximate calculations using data from the literature and reasonable assumptions of repository conditions indicate that thermal-osmotic and chemical-osmotic flows of water in semipermeable backfills may exceed Darcian flows by two to three orders of magnitude, while flows of solutes may be reduced greatly by ultrafiltration and chemical osmosis, relative to the flows predicted by advection and diffusion alone. In permeable materials, thermal diffusion may contribute to solute flows to a smaller, but still significant, extent.

Carnahan, C.L.

1983-11-01

370

The origin of morphological asymmetries in bipolar active regions. [magnetic field in solar convective envelope  

NASA Technical Reports Server (NTRS)

A series of 3D numerical simulations was carried out to examine the dynamical evolution of emerging flux loops in the solar convective envelope. The innermost portions of the loops are anchored beneath the base of the convective zone by the subadiabatic temperature gradient of the underlying overshoot region. It is found that, as the emerging loops approach the photosphere, the magnetic field strength of the leading side of each rising loop is about twice as large as that of the following side at the same depth. The evacuation of plasma out of the leading side of the rising loop results in an enhanced magnetic field strength there compared with the following side. It is argued that this result provides a natural explanation for the fact that the preceding (leading) polarity tends to have a less organized and more fragmented appearance, and that the preceding spots tend to be larger in area and fewer in number, and have a longer lifetime than the following spots.

Fan, Y.; Fisher, G. H.; Deluca, E. E.

1993-01-01

371

Spatial distributions of electromagnetic field variations and injection regions during the 20 November 2007 sawtooth event  

NASA Astrophysics Data System (ADS)

We report multi-spacecraft and ground-based observations of a "sawtooth" event on 20 November 2007. For this event, data from three THEMIS, two GOES, and four LANL spacecraft are available as well as those from extensively distributed ground magnetometers and all-sky imagers. In the present paper we focus on the spatial extents of the electromagnetic and particle signatures of the first "tooth". In this event, auroral images and ground magnetic bays showed two activations: a pseudo onset and a major onset (we use the term pseudo onset since the former auroral brightening did not significantly expand poleward). Ground magnetic bay observations indicate that the substorm current wedge (SCW) developed after the major onset in an azimuthally wide region of ~14-3 h MLT. Similarly, broad magnetic bay distribution was observed also for the pseudo onset prior to the major onset. Furthermore, around the pseudo onset, magnetic dipolarisations were observed from 0.5 to 5 h MLT. These observations illustrate that, during sawtooth events, activities following not only the major onset but also the pseudo onset can extend more widely than those during usual substorms. Remarkable electromagnetic field fluctuations embedded in the dipolarisation trend were seen at 0.5 and 2.5 h MLT. In particular, comprehensive plasma and field data from THEMIS showed the presence of a long-excited weak magnetosonic wave and an impulsive large-amplitude Alfvén wave with an earthward Poynting flux at around the eastward edge of the SCW; the latter was sufficiently strong for powering aurora (140 mW/m2 when mapped to the ionosphere). These two activations of the electromagnetic wave were identified, corresponding to the pseudo onset and the major onset. On the other hand, the dipolarisation at geosynchronous 0 h MLT was observed only after the major onset, despite its closer location to the centre of the auroral activity in terms of the MLT; this indicates that the inner radial limit of the dipolarisation region at the pseudo onset was tailward of geosynchronous altitude at 0 h MLT. The outer radial limit of the electron injection region was also found at ~10 RE by conjunction measurements with THEMIS satellites. These radial distributions are not significantly different to those expected for usual substorms.

Kasahara, S.; Miyashita, Y.; Takada, T.; Fujimoto, M.; Angelopoulos, V.; Frey, H. U.; Bonnell, J.; McFadden, J. P.; Larson, D.; Glassmeier, K. H.; Auster, H. U.; Magnes, W.; Mann, I.

2009-10-01

372

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

373

Quiescent Reconnection Rate Between Emerging Active Regions and Preexisting Field, with Associated Heating: NOAA AR 11112  

NASA Astrophysics Data System (ADS)

When magnetic flux emerges from beneath the photosphere, it displaces the preexisting field in the corona, and a current sheet generally forms at the boundary between the old and new magnetic domains. Reconnection in the current sheet relaxes this highly stressed configuration to a lower energy state. This scenario is most familiar and most often studied in flares, where the flux transfer is rapid. We present here a study of steady, quiescent flux transfer occurring at a rate three orders of magnitude lower than that in a large flare. In particular, we quantify the reconnection rate and the related energy release that occurred as the new polarity emerged to form NOAA Active Region 11112 ( SOL16 October 2010T00:00:00L205C117) within a region of preexisting flux. A bright, low-lying kernel of coronal loops above the emerging polarity, observed with the Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory and the X-ray Telescope onboard Hinode, originally showed magnetic connectivity only between regions of newly emerged flux when overlaid on magnetograms from the Helioseismic and Magnetic Imager. Over the course of several days, this bright kernel advanced into the preexisting flux. The advancement of an easily visible boundary into the old flux regions allows measuring the rate of reconnection between old and new magnetic domains. We compare the reconnection rate with the inferred heating of the coronal plasma. To our knowledge, this is the first measurement of steady, quiescent heating related to reconnection. We determined that the newly emerged flux reconnects at a fairly steady rate of 0.38×1016 Mx s-1 over two days, while the radiated power varies between (2 - 8)×1025 erg s-1 over the same time. We found that as much as 40 % of the total emerged flux at any given time may have reconnected. The total amounts of transferred flux (˜ 1×1021 Mx) and radiated energy (˜ 7.2×1030 ergs) are comparable to that of a large M- or small X-class flare, but are stretched out over 45 hours.

Tarr, Lucas A.; Longcope, Dana W.; McKenzie, David E.; Yoshimura, Keiji

2014-09-01

374

Paddy straw as a substrate for the cultivation of Lingzhi or Reishi medicinal mushroom, Ganoderma lucidum (W.Curt.:Fr.) P. Karst. in India.  

PubMed

Lingzhi or Reishi medicinal mushroom, Ganoderma lucidum, is generally cultivated on hardwood logs or sawdust/woodchips based formulations. More than 100 million tonnes of paddy straw is being produced in India per year, and almost 50% of the straw is potentially available for growing mushrooms. In the present study an attempt was made to use paddy straw as a substrate to cultivate G. lucidim. Different proportions of paddy straw were mixed with 0, 22.5%, 45%, and 67.5% sawdust and 10% rice bran. Spawn run period, fruiting initiation period, yield, moisture content, dry recovery, and fruiting body characteristics were recorded and compared. Fructification was observed with all the substrate formulations and they did not show any significant difference in yield. The highest biological efficiency (BE) (29.9%) was observed with the combination sawdust:paddy straw:rice bran 22.5:67.5:10, followed by saw dust:paddy straw:rice bran 45:45:10 with BE 27.3%. The current study demonstrated for the first time that the cultivation of G. lucidum is possible with paddy straw as the base substrate and indicated the enormous potential of paddy straw for the cultivation of G. lucidum. PMID:22164770

Veena, S S; Pandey, Meera

2011-01-01

375

The physical and mathematical modelling of the flow field in the mold region in continuous casting systems: Part II. The mathematical representation of the turbulent flow field  

Microsoft Academic Search

A mathematical representation is developed for the turbulent flow field, temperature field, and tracer distribution in the\\u000a upper region of the liquid pool in continuous casting. The problem is formulated through the statement of the two-dimensional\\u000a turbulent flow equa-tions, which were then solved numerically, using the adaptation of a technique described by Spalding and\\u000a coworkers. The computed results for the

J. Szekely; R. T. Yadoya

1973-01-01

376

Modelling and analysis of compressive strength properties of parboiled paddy and milled rice  

NASA Astrophysics Data System (ADS)

The present investigation deals with analyzing the compressive strength properties of two varieties (Tarom and Fajr) of parboiled paddy and milled rice including: ultimate stress, modulus of elasticity, rupture force and rupture energy. Combined artificial neural network and genetic algorithm were also applied to model these properties. The parboiled samples were prepared with three soaking temperatures (25, 50 and 75°C) and three steaming times (10, 15 and 20 min). The samples were then dried to final moisture contents of 8, 10 and 12% (w.b.). In general, Tarom variety had higher compressive strength properties for paddy and milled rice than Fajr variety. With increase in steaming time from 10 to 20 min, all mentioned properties increased significantly, whereas these properties were decreased with increasing moisture content from 8 to 12% (w.b.). Coupled artificial neural network and genetic algorithm model with one hidden layer, three inputs (soaking temperature, steaming time and moisture content), was developed to predict the compressive strength properties as model outputs. Results indicated that this model could predict these properties with high correlation and low mean squared error.

Nasirahmadi, Abozar; Abbaspour-Fard, Mohammad H.; Emadi, Bagher; Khazaei, Nasser Behroozi

2014-03-01

377

[Nutrient management strategy of paddy rice-upland crop rotation system].  

PubMed

Paddy rice-upland crop rotation system is a major cropping system in China, and practiced widely along the Yangtze River basin. A unique feature of this system is the annual conversion of soil from aerobic to anaerobic and then back to aerobic condition, which can result in the changes of soil physical, chemical, and biological prosperities among seasons, making a special agroecosystem. The major challenges faced by this system include declining or stagnating productivity, increasing shortage of irrigation water, improper management of nutrients, low efficiency of resource utilization, and environmental pollution. Based on an overview of the characteristics and problems of paddy rice-upland crop rotation system, this paper put forward a strategy of practicing integrated nutrient management to solve the contradictions between nutrient input, crop production and environmental risk. The key points of this strategy included nutrient management from the whole rotation system perspective, integrated use of nutrients from various sources (chemical fertilizers, organic fertilizers, and nutrients from the environment), synchronization of nutrient supply and crop nutrient demand, application of different management technologies based on the characteristics of different nutrient resources, and integration of nutrient management with other cropping system technologies like water saving and high-yielding cultivation, etc. PMID:18472447

Fan, Ming-Sheng; Jiang, Rong-Feng; Zhang, Fu-Suo; Lü, Shi-Hua; Liu, Xue-Jun

2008-02-01

378

Phytoremediation of arsenic contaminated paddy soils with Pteris vittata markedly reduces arsenic uptake by rice.  

PubMed

Arsenic (As) accumulation in food crops such as rice is of major concern. To investigate whether phytoremediation can reduce As uptake by rice, the As hyperaccumulator Pteris vittata was grown in five contaminated paddy soils in a pot experiment. Over a 9-month period P. vittata removed 3.5-11.4% of the total soil As, and decreased phosphate-extractable As and soil pore water As by 11-38% and 18-77%, respectively. Rice grown following P. vittata had significantly lower As concentrations in straw and grain, being 17-82% and 22-58% of those in the control, respectively. Phytoremediation also resulted in significant changes in As speciation in rice grain by greatly decreasing the concentration of dimethylarsinic acid (DMA). In two soils the concentration of inorganic As in rice grain was decreased by 50-58%. The results demonstrate an effective stripping of bioavailable As from contaminated paddy soils thus reducing As uptake by rice. PMID:21840633

Ye, Wen-Ling; Khan, M Asaduzzaman; McGrath, Steve P; Zhao, Fang-Jie

2011-12-01

379

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

380

Genome Sequence of the Verrucomicrobium Opitutus terrae PB90-1, an Abundant Inhabitant of Rice Paddy Soil Ecosystems?  

PubMed Central

Bacteria of the deeply branching phylum Verrucomicrobia are rarely cultured yet commonly detected in metagenomic libraries from aquatic, terrestrial, and intestinal environments. We have sequenced the genome of Opitutus terrae PB90-1, a fermentative anaerobe within this phylum, isolated from rice paddy soil and capable of propionate production from plant-derived polysaccharides. PMID:21398538

van Passel, Mark W. J.; Kant, Ravi; Palva, Airi; Copeland, Alex; Lucas, Susan; Lapidus, Alla; Glavina del Rio, Tijana; Pitluck, Sam; Goltsman, Eugene; Clum, Alicia; Sun, Hui; Schmutz, Jeremy; Larimer, Frank W.; Land, Miriam L.; Hauser, Loren; Kyrpides, Nikolaos; Mikhailova, Natalia; Richardson, P. Paul; Janssen, Peter H.; de Vos, Willem M.; Smidt, Hauke

2011-01-01

381

The environmental efficiency of non-certified organic farming in China: a case study of paddy rice production  

E-print Network

The environmental efficiency of non-certified organic farming in China: a case study of paddy rice. Our analysis reveals that organic farming loses its environmental performance at high nitrogen levels, especially during the initial expansion period of organic farming. Because newly converted organic farmers

Spino, Claude

382

STUDIES OF FLUE GAS DESULFURIZATION AT LOUISVILLE GAS AND ELECTRIC'S PADDY'S RUN STATION: VOLUME I. CARBIDE AND COMMERCIAL LIME TESTING  

EPA Science Inventory

The report gives results of tests to determine the technical factors accounting for the success of the flue gas desulfurization (FGD) system at Louisville Gas and Electric Co.'s Paddy's Run Unit 6. (Between its start-up in the Spring of 1973 and the Fall of 1976, the Unit 6 FGD s...

383

The water system of traditional rice paddies as an important habitatof the giant water bug, Lethocerus deyrollei (Heteroptera: Belostomatidae)  

Microsoft Academic Search

The population dynamics of Lethocerus deyrollei, including the seasonal change in the habitat utilization, were studied in five types of waters, permanent and temporary pools, ditch, rice paddy and marsh in a Satoyama, the traditional landscape in Japan consisting of mixtures of coppice woodlands, farmlands, and settlements, in northern Osaka, from June, 1999 to December, 2001. A mark and recapture

Yasuo Mukai; Naoto Baba; Minoru Ishii

2005-01-01

384

Predicting the risk of wild boar damage to rice paddies using presence-only data in Chiba Prefecture, Japan  

Microsoft Academic Search

Population sizes of wild boar (Sus scrofa) and the damage they cause to crops have been increasing in Japan. Reliable techniques are needed to estimate the potential for damage at the landscape scale. Here, we predict the risk of damage to rice (Oryza sativa) paddies by wild boar in Chiba Prefecture, Japan, by means of three different modelling methods –

Masayuki Saito; Hiroshi Momose; Tosaku Mihira; Seiji Uematsu

2012-01-01

385

Coal fly ash and phospho-gypsum mixture as an amendment to improve rice paddy soil fertility  

SciTech Connect

Rice is a plant that requires high levels of silica (Si). As a silicate NOD source to rice, coal fly ash (hereafter, fly ash), which has an alkaline pH and high available silicate and boron (B) contents, was mixed with phosphor-gypsum (hereafter, gypsum, 50%, wt wt{sup -1}), a by-product from the production of phosphate fertilizer, to improve the fly ash limitation. Field experiments were carried out to evaluate the effect of the mixture on soil properties and rice (Oryza sativa) productivity in silt loam (SiL) and loamy sand (LS) soils to which 0 (FG 0), 20 (FG 20), 40 (FG 40), and 60 (FG 60) Mg ha{sup -1} were added. The mixture increased the amount of available silicate and exchangeable calcium (Ca) contents in the soils and the uptake of silicate by rice plant. The mixture did not result in accumulation of heavy metals in soil and an excessive uptake of heavy metals by the rice grain. The available boron content in soil increased with the mixture application levels up to 1.42 mg kg{sup -1} following the application of 60 Mg ha{sup -1} but did not show toxicity. The mixture increased significantly rice yield and showed the highest yields following the addition of 30-40 Mg ha{sup -1} in two soils. It is concluded that the fly ash and gypsum mixture could be a good source of inorganic soil amendments to restore the soil nutrient balance in rice paddy soil.

Lee, Y.B.; Ha, H.S.; Lee, C.H.; Kim, P.J. [Gyeongsang National University, Jinju (Republic of Korea)

2008-04-15

386

Variation of grain Cd and Zn concentrations of 110 hybrid rice cultivars grown in a low-Cd paddy soil.  

PubMed

Enhanced Cd uptake and Zn depletion in rice grains and high potential for food Cd exposure by the high-yielding hybrid cultivars of China had been addressed. A field experiment was conducted in 2006 to determine the difference in grain Cd and Zn between cultivars. Total 110 cultivars including super rice and common hybrid rice cultivars were grown on a single paddy soil (Entic Haplaquept) with a neutral reaction and low total Cd content. Grain Cd and Zn concentrations were determined with graphite atomic adsorption spectrophotometer (GFAAS) and flame atomic adsorption spectrophotometer (AAS) respectively. Wide variation of Cd content in grain was found in a range of 0.004-0.057 mg/kg, while the Zn content in a range of 10.25-30.06 mg/kg among the cultivars. Higher Cd but lower Zn concentration in grains of super rice cultivars was observed compared to the common hybrid ones. A highly significant positive linear correlation of grain Cd/Zn with grain Cd was found for super rice and common hybrid cultivars, meanwhile much higher slope for these hybrid cultivars than the reported non-hybrid cultivars was also observed. Using the limit value of the Chinese chemical guidelines for foods (MOHC and SSC, 2005), calculated potential risk of food Cd exposure with "Zn hungry" through diet intake was prominent with all the studied 110 hybrid rice cultivars, possessing high potential health problems for rice production in South China using the super rice cultivars. Breeding of genotypes of rice cultivars with low grain Cd and low Cd/Zn ratio is needed for rice production in acidic red soils where Cd bioavailability is prevalently high. PMID:19402417

Shi, Jing; Li, Lianqing; Pan, Genxing

2009-01-01

387

Plastic stress field in the Alps region: comparison of modelling and WSM data  

NASA Astrophysics Data System (ADS)

Modelling of stresses in tectonic plates is usually based on the elastic assumption. However, stress-states in some regions of the crust, in particular in mountain areas, can be better described on the basis of limiting equilibrium theories. The current study is aimed to investigate whether plastic Mohr-Coulomb models can be applied for a part of the Eurasian tectonic plate between the lakes Geneva and Constance (the Alps). For this purpose, patterns of stress trajectories are calculated and compared with the WSM data (release 2008) on stress orientations. The problem of stress identification is solved by employing a variant of the Stress Trajectories Element Method (STEM) that also uses the WSM data on stress orientations. Stress magnitudes remain unknown prior to the solution, which differs this research from the conventional approaches. Firstly, discrete data on stress orientations (scattered in the whole region between the two lakes) have been converted into continuous one along a chosen boundary. This is necessary in order to specify boundary conditions that are formulated on an open contour in terms of stress orientations and their normal derivatives. The proposed variant of the STEM deals with finite difference formulations for two Cauchy's boundary value problems for identification of the slip lines and the stress trajectories within characteristic triangles. The method also introduces the concept of alternations of the Cauchy's problems for stress trajectories and slip lines, which allows covering a larger area. For given strength parameters (friction angles and cohesion) a unique pattern of stress trajectories is determined. This field is further compared against the WSM data available inside the region. The comparisons are made for different strength parameters, which allow the best fit to the data. Moreover, because of the fact that the maximum shear stress is governed by the Mohr-Coulomb criterion, the complete stress tensor is found with accuracy of one additive constant. This work is a part of the STEM project supported by EPSRC (UK), grant EP/E032494/1. The authors acknowledge this support.

Haderka, Peter; Galybin, Alexander N.

2010-05-01

388

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

389

Intestinal Helminthic Infections in Striped Field Mice, Apodemus agrarius, from Two Southern Regions of Korea  

PubMed Central

The present study was performed to know the infection status of intestinal helminths in a most common species of field mice, Apodemus agrarius, from 2 southern regions of Korea. Total 133 and 103 mice were collected by the mouse trap in Hapcheon-gun, Gyeongsangnam-do and Gurye-gun, Jeollanam-do, respectively, from July 2005 to June 2006. The small intestine of each mouse was resected and longitudinally opened with a pair of scissors. The intestinal contents were washed with 0.85% saline until the supernatant became clear. Helminths were collected with naked eyes or under a stereomicroscope from the sediment of the intestinal content. More than 11 species of helminths (4 nematode spp., 5 trematode spp., and 2 cestode spp.) were recovered. Among these, heligmosomoid nematodes (97.5%) was the most highly and heavily infected species. As the members of trematodes, Plagiorchis muris, Brachylaima sp., Echinostoma hortense, Echinostoma cinetorchis, and unidentified echinostome larvae were found in the small intestines of 35 (14.8%), 12 (5.1%), 6 (2.5%), 1 (0.4%), and 1 (0.4%) mice respectively. Two species of tapeworms, Hymenolepis nana and Hymenolepis diminuta were also detected in 79 (33.5%) and 21 (8.9%) mice, respectively. Conclusively, heligmosomoid nematodes were the most prevalent (dominant) species among more than 11 helminth species detected, and Brachylaima sp. fluke is newly added in the list of intestinal trematodes in Korea. PMID:25246721

Na, Byoung-Kuk; Song, Hyeon-Je; Kim, Chung-Mo; Nam, Gi-Jin

2014-01-01

390

A Near-IR Spectroscopic Survey of the Central Regions of Field Ellipticals: Continued  

NASA Astrophysics Data System (ADS)

We propose to obtain central region K-band spectra for a sample of N ~ 30 field elliptical galaxies. An analysis of the central near-IR colors of these galaxies suggests that some of these galaxies may contain first-ascent giant branches (FGB) similar to the unusual FGB seen in the metal-rich Galactic globular clusters Liller 1 and NGC 6440. We wish to test this hypothesis by measuring the equivalent widths of the Na I 2.207(micron) and Ca I 2.263(micron) as well as the CO 2.36(micron) index. These new EW and CO index measurements will be compared to previously published data for K and M giants in the Local Solar Neighborhood, Baade's Window, and the Liller 1 and NGC 6440 clusters. These spectra can also be used to assess cosmic dispersion in the elliptical galaxy stellar population properties, which has important implications for SBF distance measurements and the study of high- redshift galaxies.

Silva, David; Bothun, Gregory

2000-02-01

391

Exposure to pulse-modulated radio frequency electromagnetic fields affects regional cerebral blood flow.  

PubMed

We investigated the effects of radio frequency electromagnetic fields (RF EMF) similar to those emitted by mobile phones on waking regional cerebral blood flow (rCBF) in 12 healthy young men. Two types of RF EMF exposure were applied: a 'base-station-like' and a 'handset-like' signal. Positron emission tomography scans were taken after 30 min unilateral head exposure to pulse-modulated 900 MHz RF EMF (10 g tissue-averaged spatial peak-specific absorption rate of 1 W/kg for both conditions) and sham control. We observed an increase in relative rCBF in the dorsolateral prefrontal cortex on the side of exposure. The effect depended on the spectral power in the amplitude modulation of the RF carrier such that only 'handset-like' RF EMF exposure with its stronger low-frequency components but not the 'base-station-like' RF EMF exposure affected rCBF. This finding supports our previous observation that pulse modulation of RF EMF is necessary to induce changes in the waking and sleep EEG, and substantiates the notion that pulse modulation is crucial for RF EMF-induced alterations in brain physiology. PMID:15787706

Huber, R; Treyer, V; Schuderer, J; Berthold, T; Buck, A; Kuster, N; Landolt, H P; Achermann, P

2005-02-01

392

Intestinal helminthic infections in striped field mice, Apodemus agrarius, from two southern regions of Korea.  

PubMed

The present study was performed to know the infection status of intestinal helminths in a most common species of field mice, Apodemus agrarius, from 2 southern regions of Korea. Total 133 and 103 mice were collected by the mouse trap in Hapcheon-gun, Gyeongsangnam-do and Gurye-gun, Jeollanam-do, respectively, from July 2005 to June 2006. The small intestine of each mouse was resected and longitudinally opened with a pair of scissors. The intestinal contents were washed with 0.85% saline until the supernatant became clear. Helminths were collected with naked eyes or under a stereomicroscope from the sediment of the intestinal content. More than 11 species of helminths (4 nematode spp., 5 trematode spp., and 2 cestode spp.) were recovered. Among these, heligmosomoid nematodes (97.5%) was the most highly and heavily infected species. As the members of trematodes, Plagiorchis muris, Brachylaima sp., Echinostoma hortense, Echinostoma cinetorchis, and unidentified echinostome larvae were found in the small intestines of 35 (14.8%), 12 (5.1%), 6 (2.5%), 1 (0.4%), and 1 (0.4%) mice respectively. Two species of tapeworms, Hymenolepis nana and Hymenolepis diminuta were also detected in 79 (33.5%) and 21 (8.9%) mice, respectively. Conclusively, heligmosomoid nematodes were the most prevalent (dominant) species among more than 11 helminth species detected, and Brachylaima sp. fluke is newly added in the list of intestinal trematodes in Korea. PMID:25246721

Sohn, Woon-Mok; Na, Byoung-Kuk; Song, Hyeon-Je; Kim, Chung-Mo; Nam, Gi-Jin

2014-08-01

393

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 stru