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1

Case Study on Nitrogen and Phosphorus Emissions from Paddy Field in Taihu Region  

Microsoft Academic Search

The agricultural non-point source pollution by nitrogen (N) and phosphorus (P) loss from typical paddy soil (whitish soil, Bai Tu in Chinese) in the Taihu Lake region was investigated through a case study. Results shown that the net load of nutrients from white soil is 34.1 kg ha-1 for total nitrogen (TN), distributed as 19.4 kg ha-1, in the rice

H. Y. Guo; J. G. Zhu; X. R. Wang; Z. H. Wu; Z. Zhang

2004-01-01

2

Case study on nitrogen and phosphorus emissions from paddy field in Taihu region.  

PubMed

The agricultural non-point source pollution by nitrogen (N) and phosphorus (P) loss from typical paddy soil (whitish soil, Bai Tu in Chinese) in the Taihu Lake region was investigated through a case study. Results shown that the net load of nutrients from white soil is 34.1 kg ha(-1) for total nitrogen (TN), distributed as 19.4 kg ha(-1), in the rice season and 14.7 kg ha(-1) in the wheat season, and for total phosphorus (TP) 1.75 kg ha(-1), distributed as 1.16 kg ha(-1) in the rice season and 0.58 kg ha(-1) in the wheat season. The major chemical species of N loss is different in the two seasons. NH4-N is main the form in the rice season (53% of TN). NO3-N is the main form in wheat season (46% of TN). Particle-P is the main form in both seasons, (about 56% of TP). The nutrient loss varied with time of the year. The main loss of nutrients happened in the 10 days after planting, 64% of TN and 42% of TP loss, respectively. Rainfall and fertilizer application are the key factors which influence nitrogen and phosphorus loss from arable land, especially rainfall events shortly after fertilizer application. So it is very important to improve the field management of the nutrients and water during the early days of planting. PMID:15499776

Guo, H Y; Zhu, J G; Wang, X R; Wu, Z H; Zhang, Z

2004-01-01

3

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

PubMed

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

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

2011-04-01

4

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  

Microsoft Academic Search

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

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

2004-01-01

5

Phosphorus cycling through phosphine in paddy fields  

Microsoft Academic Search

Phosphine emission fluxes from paddy fields, phosphine ambient levels in air, and the vertical profile of matrix-bound phosphine in soil have been measured throughout the growing season of rice in Beijing, China. It was found that both the seasonal and diurnal emission fluxes and ambient levels fluctuate significantly. During the drainage period, phosphine released from the soil with the highest

Sheng-Hui Han; Ya-Hui Zhuang; Ji-Ang Liu; Dietmar Glindemann

2000-01-01

6

Comparison of aquatic organisms communities between paddy fields under rice-duck (aigamo) farming and paddy fields under conventional farming  

Microsoft Academic Search

Farming using “aigamo” (rice-duck; crossbred of wild and domestic duck) is one of the popular organic farming methods for paddy rice in Japan. The diversity and community structure of aquatic organisms under rice-duck farming were investigated and compared with those under conventional farming. Adjacent paddy fields with these different farming methods were selected at two sites. The taxonomical groups and

Masatsugu Yamazaki; Nobuhiro Yasuda; Toshimasa Yamada; Koichi Ota; Makoto Kimura

2004-01-01

7

Spatial dependence and bioavailability of metal fractions in paddy fields on metal concentrations in rice grain at a regional scale  

Microsoft Academic Search

Purpose  Although the bioavailability of heavy metals has been widely investigated, little information is available on the spatial\\u000a correlations of heavy metals in soil–rice systems at a regional scale. A study of heavy metals in soil–rice systems at a present\\u000a rice production area could provide valuable information on the safety of rice production and provide guidelines beneficial\\u000a to agriculture management and

Keli Zhao; Xingmei Liu; Weiwen Zhang; Jianming Xu; Fan Wang

8

Nitrogen loss through lateral seepage in near-trench paddy fields.  

PubMed

A near-trench paddy field experiment with five urea application rates (0-360 kg N ha(-1) in 90-kg increments) was conducted on a paddy soil in the Taihu Lake Region of China to elucidate N losses through lateral seepage during three rice (Oryza sativa L.) growing seasons. The total N (Nt), NH4(+) -N, and NO3(-) -N concentrations in the lateral seepage water increased with increasing N rates. The seasonal Nt fluxes by lateral seepage varied from 6.8 to 25.6 kg N ha(-1) for urea application rates of 90 to 360 kg N ha(-1). Lateral seepage accounted for 4.7 to 6.6% of the Nt applied, implying that lateral seepage was an important pathway of N loss from near-trench paddy fields. The cumulative N loss via lateral seepage was significantly related to N fertilization rate (P = 0.05). Floodwater level was also identified as a main factor affecting N losses via lateral seepage from paddy fields, as indicated by a positive linear relationship (R2 = 0.43) between floodwater level and daily lateral flow during the flooded period (P = 0.05). Under the conditions of these experiments, a shallow floodwater depth of 50 mm, urea application rates of 90 kg N ha(-1) or less, and no rainfall within 1 wk after N application reduced N losses by lateral seepage from paddy fields. PMID:18396559

Liang, Xin-Qiang; Li, Hua; Chen, Ying-Xu; He, Miao-Miao; Tian, Guang-Ming; Zhang, Zhi-Jian

2008-01-01

9

BEHAVIOR OF FOUR HERBICIDES IN A PADDY FIELD: SIMULATION BY A LABORATORY MICROCOSM  

Microsoft Academic Search

The behaviour of commercial herbicide formulations containing pretilachlor, oxadiazon, cinosulfuron and azimsulfuron was studied in a laboratory model to investigate possible management practices for controlling herbicide losses from paddy fields. The model consisted of soil and water sampled from a North Italian paddy field. Flooding\\/draining simulations and herbicide treatments were performed on the paddy field model following agricultural practices for

10

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

NASA Astrophysics Data System (ADS)

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

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

2008-10-01

11

Exposure risk assessment and evaluation of the best management practice for controlling pesticide runoff from paddy fields. Part 1: Paddy watershed monitoring.  

PubMed

Rice pesticide concentrations in surface water along with hydrological balance and water management conditions were investigated in a paddy watershed of about 100 ha at the Sakura river basin in Tsukuba, Japan, for 3 years from April 2002. Monitoring on different hydrological scales ranging from a paddy plot up to a watershed determined the importance of water management associated with rainfall events and the cyclic irrigation for reducing pesticide discharge into aquatic environments. Surface drainage significantly increased as a response to rainfall events greater than about 1.5 cm day(-1). A total of 16 herbicides were detected in the stream water and their peak concentrations mostly occurred from early to mid-May following the pesticide application period. Two water management factors influencing the pesticide runoff from paddy fields were defined: excess water storage capacity (EWSC) and water holding period (WHP). Uncertainty analyses of pesticide discharge from a paddy plot for dymron (daimuron) and imazosulfuron (IMS) were performed using Monte Carlo simulation (MCS) with prescribed probability of rainfall and water management practice from observations over a period of 3 years. Application of an intermittent irrigation scheme with shallow water depth practice and high drainage gate to maintain the EWSC > 2 cm and increasing WHP from the current Japanese Agricultural Chemicals Regulation law of 3-4 days to at least 10 days were recommended for reducing the pesticide runoff from paddy fields in a monsoon region such as in Japan. The combination of good water management in field plots and small-scale water cycling is the best management practice for controlling pesticide discharge from paddy watersheds. PMID:17099930

Vu, Son Hong; Ishihara, Satoru; Watanabe, Hirozumi

2006-12-01

12

Spatial distribution and temporal variability of arsenic in irrigated rice fields in Bangladesh. 2. Paddy soil.  

PubMed

Arsenic-rich groundwater from shallow tube wells is widely used for the irrigation of boro rice in Bangladesh and West Bengal. In the long term this may lead to the accumulation of As in paddy soils and potentially have adverse effects on rice yield and quality. In the companion article in this issue, we have shown that As input into paddy fields with irrigation water is laterally heterogeneous. To assess the potential for As accumulation in soil, we investigated the lateral and vertical distribution of As in rice field soils near Sreenagar (Munshiganj, Bangladesh) and its changes over a 1 year cycle of irrigation and monsoon flooding. At the study site, 18 paddy fields are irrigated with water from a shallow tube well containing 397 +/- 7 microg L(-1) As. The analysis of soil samples collected before irrigation in December 2004 showed that soil As concentrations in paddy fields did not depend on the length of the irrigation channel between well and field inlet. Within individual fields, however, soil As contents decreased with increasing distance to the water inlet, leading to highly variable topsoil As contents (11-35 mg kg(-1), 0-10 cm). Soil As contents after irrigation (May 2005) showed that most As input occurred close to the water inlet and that most As was retained in the top few centimeters of soil. After monsoon flooding (December 2005), topsoil As contents were again close to levels measured before irrigation. Thus, As input during irrigation was at least partly counteracted by As mobilization during monsoon flooding. However, the persisting lateral As distribution suggests net arsenic accumulation over the past 15 years. More pronounced As accumulation may occur in regions with several rice crops per year, less intense monsoon flooding, or different irrigation schemes. The high lateral and vertical heterogeneity of soil As contents must be taken into account in future studies related to As accumulation in paddy soils and potential As transfer into rice. PMID:17937268

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

2007-09-01

13

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

NASA Astrophysics Data System (ADS)

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

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

14

Application of wavelet transform for extracting edges of paddy fields from remotely sensed images  

Microsoft Academic Search

For geographical information systems (GIS) to be useful in the management of Japanese paddy fields, it is vital to be able to prepare base maps that define sections of field. We attempted to prepare a base map by detecting the edges of submerged paddy fields from a SPOT image with the use of multi-resolution wavelet transform. The raw image of

T. Ishida; S. Itagaki; Y. Sasaki; H. Ando

2004-01-01

15

Geochemical and Geophysical Monitoring of Salinewater Intrusion in Korean Paddy Fields  

Microsoft Academic Search

The saline water intruded zone in paddy fields near the seashore can be diagnosed accurately by joint exploration with geophysical and geochemical methods. Using the electromagnetic (EM) sounding technique, the weakly consolidated zone which introduces saline water into such an area of near seashore paddy fields in Korea was detected from the variation of electrical conductivity distribution following field irrigation.

Sang-Ho Lee; Kyoung-Woong Kim; Ilwon Ko; Sang-Gyu Lee; Hak-Soo Hwang

2002-01-01

16

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

17

Dissipation of difenoconazole in rice, paddy soil, and paddy water under field conditions.  

PubMed

An analytical method for determining the residue of a broad-spectrum fungicide, difenoconazole, in soil and rice crop matrices is described. Mean recoveries and relative standard deviation (RSD) in paddy soil, water, rice plant, rice hull, and husked rice matrices at three spiking levels ranged 71.8-115.8% and 1.6-7.8%, respectively. The half-life of difenoconazole was determined at three different field sites in Guangxi, Hubei, and Zhejiang provinces in China via a dissipation experiment, in which a 30% aqueous suspension concentrate of difenoconazole and propiconazole (15% difenoconazole, 15% propiconazole) was applied at high dosages. The half-lives of difenoconazole in water, rice plant, and soil in Guangxi were 0.30, 2.59 and 23.26 days, 2.50, 1.77 and 2.82 days in Hubei, and 2.71, 1.39 and 6.61 days in Zhejiang, respectively. Difenoconazole concentrations in soil, rice hull, and husked rice samples were below the detection limit at pre-harvest intervals of 30, 40 and 50 days after fungicide application. The concentration in straw at pre-harvest intervals of 30, 40 and 50 days in the three experimental locations ranged from 0.037mg kg(-1) and 2.53mg kg(-1). PMID:23062559

Wang, K; Wu, J X; Zhang, H Y

2012-12-01

18

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

NASA Astrophysics Data System (ADS)

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

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

19

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

20

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

21

Influence of bird feces to water quality in paddy fields during winter season  

NASA Astrophysics Data System (ADS)

Thousands of migratory birds such as tundra swan came to the paddy fields for overwintering in recent years in the study area. They stayed in paddy fields during night time for sleeping and used around the fields as a feeding ground during day time. During the birds stay, it was observed that water pooled in the paddy fields gradually turned green and gave off a bad smell. In this study, we tried to estimate the influence of the bird’s feces to water quality in the paddy fields. The study area is in the southeastern portion of Matsue City in Shimane Prefecture, Japan. In several paddy fields, puddling procedure was executed after harvesting rice and then water was stored in the paddy fields during winter season. This is because of being easier of farming activities such as weeding next season and of avoiding using pesticide for weeding with rising of environmental awareness. Water in the paddy fields was collected once or twice a month from the target fields and analyzed nitrogen, phosphorus, and organic carbon in 2007. In the study in 2006, as water was sampled once a week and the changes in the water quality had been grasped, we paid attention to behavior of the birds in a day in the field investigation in 2007. The number of the birds was counted once an hour from visible 7 am to 6 pm once a month. In addition to this, fresh feces were sampled from the fields and analyzed the contents of nitrogen, phosphorus, and organic carbon in the feces. As results, average water qualities of TN, TP, and TOC from November 2007 to March 2008 showed very high concentrations compared with a river water concentration used as irrigation water. More than 70% of TN in the water was ammonia nitrogen. Moreover, comparing with a standard fertilizer amount of nitrogen and phosphorus for paddy fields during irrigation period, it was estimated that the amount of nitrogen excreted by the bird’s feces during the winter season was equivalent to the standard fertilizer amount and the amount of phosphorus was about 30% of the standard amount. From these results, it was concluded that feces and urine from the birds influenced a lot to the water quality in the paddy fields.

Somura, H.; Takeda, I.; Masunaga, T.; Mori, Y.; Ide, J.

2009-12-01

22

Spatial relationships among different forms of soil nutrients in a paddy field  

Microsoft Academic Search

Within-field soil variability has often been reported in Japanese paddy fields. In one of such fields, we examined the relationships of spatial variations among different forms of soil nutrients and their direct influence on rice growth. Samples of surface soils collected from 100 plots (5 x 10 m) in the field were analyzed for the contents of N, P, and

Naoki Moritsuka; Junta Yanai; Mikio Umeda; Takashi Kosaki

2004-01-01

23

[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

24

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.

He, Yupu; Yang, Shihong; Wang, Yijiang

2014-01-01

25

(137)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 79-198mBqL(-1) under stable runoff conditions and 702-13,400BqL(-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 (201-348kBqm(-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

Preliminary validation results of MODIS albedo products compared with temporal ground-measured albedos of paddy fields  

Microsoft Academic Search

In the present paper, the validation results of Mod- erate Resolution Imaging Spectroradiometer (MODIS) albedo products are reported. Measurements of shortwave band albedos have been conducted for paddy fields in Chiba, Japan from April to December of 2004. The accuracy of MODIS 1-km albedo products for paddy fields in Japan was found to be within approximately 0.03. In addition, the

Junichi Susaki; Koji Kajiwara; Yoshiaki Honda; Yoshifumi Yasuoka

2005-01-01

27

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

Microsoft Academic Search

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

Yang Ping; Zhu Wei; Tan Xiao

2011-01-01

28

Dynamics of microbial biomass nitrogen as influenced by organic matter application in paddy fields  

Microsoft Academic Search

The effects of annual application of rice straw or cow manure compost for 17–20 y on the dynamics of fertilizer N and soil organic N in Gley paddy fields were investigated by using the N tracer technique during the rice cropping season. The chloroform fumigation-extraction method was evaluated to determine the properties of soil microbial biomass under submerged field conditions

Fujiyoshi Shibahara; Shigekazu Yamamuro; Kazuyuki Inubushi

1998-01-01

29

Communities of methanogenic bacteria in paddy field soils with long-term application of organic matter  

Microsoft Academic Search

Methanogenic communities were investigated in paddy field soil that had received long-term (over 30 y) applications of organic matter. Methanogenic bacteria were enumerated by the most probable number (MPN) method and by the analysis of ether-linked lipids. Three fields, one with chemical fertilizer (CF), one with application of rice straw plus chemical fertilizer (RS), and one with application of rice

Susumu Asakawa; Masayo Akagawa-Matsushita; Yosuke Koga; Koichi Hayano

1998-01-01

30

Simulation of organic carbon dynamics at regional scale for paddy soils in China  

Microsoft Academic Search

Accurate simulation of soil organic carbon (SOC) dynamics is vitally important in researching the carbon cycle in terrestrial\\u000a ecosystems. Especially, the application of SOC model at the regional scale has major implications for regional and global\\u000a carbon cycling. This paper addresses the regional simulation for SOC in the surface layer (0~15 cm) of paddy soils in Wuxi\\u000a and Changzhou, Jiangsu Province,

Xue-Zheng Shi; Ru-Wei Yang; David C. Weindorf; Hong-Jie Wang; Dong-Sheng Yu; Yao Huang; Xian-Zhang Pan; Wei-Xia Sun; Li-Ming Zhang

2010-01-01

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.

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

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

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

33

The input-output balance of cadmium in a paddy field of Tokyo.  

PubMed

Field monitoring was practiced from 2001 to 2003 to evaluate the input (irrigation, atmospheric deposition, and fertilizer application) and the output (uptake and accumulation into the above-ground biomass of rice plants and leaching) of cadmium (Cd) in a contaminated paddy field in Tokyo. The cadmium concentrations of irrigated water, open-bulk precipitation, soil solution (leaching water), rice plants collected at the harvesting stage and the chemical fertilizer and the cow manure compost applied were determined. The Cd flux of each factor was calculated by multiplying the Cd concentration by the volume or mass of the media. The annual input-output balance of Cd in the paddy field in 2001 and 2002 was estimated to be -5.44 [corrected] g ha(-1) and -2.01 [corrected] g ha(-1), respectively, indicating the loss of Cd from the paddy field, although the losses accounted for only 0.24% [corrected] and 0.089% [corrected] of the total amount of Cd in the ploughed layer soil in 2001 and 2002, respectively. Among the factors involved, the input from fertilizers (including manure compost) and the output due to the uptake by rice plants played a major role in the balance. The former largely depended on the types and amounts of fertilizers applied, and the latter on the water management practices in the paddy field, such as flooding and drainage of the surface water. PMID:17207840

Kikuchi, Tetsuro; Okazaki, Masanori; Toyota, Koki; Motobayashi, Takashi; Kato, Makoto

2007-03-01

34

The fate of nitrogen compounds and heavy metals in studied semi-closed organic paddy fields  

Microsoft Academic Search

Agricultural development, cultivation management, and the application of fertilizer have affected the environment to such extent that organic farming has become an adopted trend to reduce the negative impact of all these factors. For a paddy field system, implemented activities in cultivation management are the essential factors that build up man-made materials such as nitrogen compounds and heavy metals. In

Ming-Chien Su; Nien-Hsin Kao

2012-01-01

35

Tunable diode laser measurements of methane fluxes from an irrigated rice paddy field in the Philippines  

SciTech Connect

The authors report the measurement of in situ methane emissions from a rice paddy during March 1992. They find that in general the flux of methane correlates with the soil temperature curves on a daily basis. Excursions are observed due to weeding, field drainage, and heavy rainstorms.

Simpson, I.J.; Thurtell, G.W.; Kidd, G.E. [Univ. of Guelph, Ontario (Canada)] [and others] [Univ. of Guelph, Ontario (Canada); and others

1995-04-20

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

Variability of Micro-elevation, Yield, and Protein Content within a Transplanted Paddy Field  

Microsoft Academic Search

Due to the nature of waterlogged fields used for rice production, we hypothesized that micro-elevation (micro-relief, micro-topography, or differences in elevation) is an important factor for site-specific management within rice fields. A 0.5-ha transplanted and weed-free paddy field was selected as the observation site, where there was micro-elevation in a range of 100 mm within the field. Combine-monitored grain yield

K. Shoji; T. Kawamura; H. Horio; K. Nakayama; N. Kobayashi

2005-01-01

38

[Determination of niclosamide ethanolamine residue in rice and paddy field by high performance liquid chromatography].  

PubMed

A high performance liquid chromatographic (HPLC) method was established for the analysis of niclosamide ethanolamine residue in rice and paddy field. The paddy water and plant were extracted with alkaline ethylacetate, while the paddy soil, rice husk and unpolished rice were first extracted with alkaline ethanol, and then with ethylacetate. The extracts were then cleaned-up by a Florisil column and detected by high performance liquid chromatography with an ultraviolet detector (UVD) on a Welchrom C18 column (250 mm x 4.6 mm, 5 microm). The calibration curve showed good linearity from 0.01 mg/L to 10.00 mg/L with the correlation coefficient more than 0. 999 8. The average recoveries of this method were from 93.47% to 100.9% with the relative standard deviations of 1.46% - 5.82% at the spiked levels of 0.01 - 5.00 mg/kg. This method is fast, simple, sensitive, reproducible and practical for the determination of niclosamide ethanolamine residue in paddy fields, and can meet the requirement of the determination of pesticide residues. PMID:22393698

Wu, Yihong; Gong, Daoxin; Peng, Xiao; Xie, Hui; Han, Baolu

2011-11-01

39

Phosphorus status of paddy soils from the central region of the Mekong River in Laos  

Microsoft Academic Search

Laos (14-22.5°N and 100-107.5°?) is a land-locked country located in the Indo-China Peninsula, adjacent to Vietnam, Cambodia, Thailand, Myanmar, and China. The total area of the country is 236,800 km and about 70% of the land is occupied by mountains. Paddy fields are distributed in flood plains along the Mekong River and its tributaries and in valley bottom plains dissected

Kazuhiko Egashira; Maki Tanouchi; Prasop Virakornphanich

1996-01-01

40

[Responses of soil organic carbon content and fractions to land-use conversion from paddy field to upland].  

PubMed

Natural 13C abundance determination method coupled with physical fractionation of soil organic carbon (SOC) was used to evaluate the responses of SOC and its fractions to long-term land-use conversion from paddy field to upland field (corn cultivation). Results showed that land-use conversion from paddy field to upland field led to significant decreases in the contents of SOC and total nitrogen (TN). Concentrations of total organic carbon (TOC) and TN were respectively greater by 76.7% and 47.6% in the paddy field than those in the corn field. Concentrations of occluded particulate organic matter (oPOM) and mineral-associated organic matter (MOM) on a whole soil basis were two times higher in the paddy field than those in the upland field, while no significant difference was found in free particulate organic matter (fPOM). Carbon concentrations of oPOM and MOM fractions on their own weight basis were significantly greater in the paddy field than those in the upland field, especially the oPOM fraction, which was 6 times higher in the former than that in the latter. It could be concluded that SOC protection exerted by soil aggregates in paddy soil was greater than that in upland soil. After a 19-year conversion from paddy field to corn field, delta13C values of SOC fractions significantly increased. Maize-derived carbon (C) accounted for 54.6%, 24.7%, and 19.0% in fPOM, oPOM and MOM, respectively. Mean residence time (MRT) of the initial rice-derived C increased in the order fPOM (24 a) < oPOM (67 a) < MOM (90 a). The above results further indicate that paddy field soil owns greater capability of carbon sequestration than upland soil mainly through increasing the contents of oPOM and MOM in the fractions of SOC. PMID:19545021

Huang, Shan; Rui, Wen-Yi; Peng, Xian-Xian; Liu, Wu-Ren; Zhang, Wei-Jian

2009-04-15

41

Characterization of contamination, source and degradation of petroleum between upland and paddy fields based on geochemical characteristics and phospholipid fatty acids.  

PubMed

To evaluate contamination caused by petroleum, surface soil samples were collected from both upland and paddy fields along the irrigation canals in the Hunpu wastewater irrigation region in northeast China. N-alkanes, terpanes, steranes, and phospholipid fatty acids (PLFA) in the surface soil samples were analyzed. The aliphatic hydrocarbon concentration was highest in the samples obtained from the upland field near an operational oil well; it was lowest at I-3P where wastewater irrigation promoted the downward movement of hydrocarbons. The Hunpu region was found contaminated by heavy petroleum from oxic lacustrine fresh water or marine deltaic source rocks. Geochemical parameters also indicated significantly heavier contamination and degradation in the upland fields compared with the paddy fields. Principal component analysis based on PLFA showed various microbial communities between petroleum contaminated upland and paddy fields. Gram-negative bacteria indicated by 15:0, 3OH 12:0, and 16:1(9) were significantly higher in the paddy fields, whereas Gram-positive bacteria indicated by i16:0 and 18:1(9)c were significantly higher in the upland fields (p < 0.05). These PLFAs were related to petroleum contamination. Poly-unsaturated PLFA (18:2omega6, 9; indicative of hydrocarbon-degrading bacteria and fungi) was also significantly elevated in the upland fields. This paper recommends more sensitive indicators of contamination and degradation of petroleum in soil. The results also provide guidelines on soil pollution control and remediation in the Hunpu region and other similar regions. PMID:23534234

Zhang, Juan; Wang, Renqing; Du, Xiaoming; Li, Fasheng; Dai, Jiulan

2012-01-01

42

[Estimation of N loss loading by runoff from paddy field during submersed period in Hangjiahu area].  

PubMed

As the largest bread basket in Zhejiang Province, Hangjiahu area is facing more and more serious water pollution, while the N loss loading by runoff from the paddy field during its submersed period is the main cause of the pollution. Through field experiment and fixed spot observation, the model of precipitation - runoff in Yangtze delta was testified, and the results showed that the precipitation - runoff model from HE Baogen was basically accorded with the fact after considering the impact of field overflow mouth, and the error was between - 19. 9% and + 18. 0%. The model of N concentration with precipitation - runoff in paddy field during submersed period was brought forward, with the R value being 0. 948. These two models consisted of the model of N loss loading by runoff from paddy field during submersed period. Based on this model as well as the past 30 years data of fertilization and precipitation, 1: 250,000 topography map, land use map, and water system map, the N loss loading and its distribution were estimated by using GIS method, and the results showed that the N loss loading was different from place to place, with an average of 35.26 kg N x hm(-2), and accounting for 12. 69% of the applied N. The N loss loading in Anji and Yuhang with obviously more precipitation was higher than that in other places, while Haining also had a serious N loss problem because of the huge amount of applied N. PMID:17209392

Tian, Ping; Chen, Yingxu; Tian, Guangming; Liang, Xinqiang; Zhang, Qiuling; Yu, Qiaogang; Li, Hua

2006-10-01

43

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

44

Distribution and identification of proteolytic Bacillus spp. in paddy field soil under rice cultivation.  

PubMed

Proteolytic bacteria in paddy field soils under rice cultivation were characterized and enumerated using azocoll agar plates. Bacillus spp. were the proteolytic bacteria that were most frequently present, comprising 59% of the isolates. They were always the numerically dominant proteolytic bacteria isolated from three kinds of fertilizer treatments (yearly application of rice-straw compost and chemical fertilizer, yearly application of chemical fertilizer, and no fertilizer application) and at three different stages of rice development (vegetative growth stage, maximal tillering stage, and harvest stage). Of the 411 proteolytic bacteria isolated, 124 isolates had stronger proteolytic activity than others on the basis of gelatin liquefaction tests and most of them were Bacillus spp. (100% in 1989 and 92.4% in 1991). Bacillus subtilis and Bacillus cereus were the main bacteria of this group and Bacillus mycoides, Bacillus licheniformis, and Bacillus megaterium were also present. We conclude that these Bacillus spp. are the primary source of soil protease in these paddy fields. PMID:8364803

Watanabe, K; Hayano, K

1993-07-01

45

Effects of residual biomass burning on the methane emission from a paddy field  

NASA Astrophysics Data System (ADS)

Methane (CH4) is generated by organic matter decomposition in anaerobic soil. It is said that about 20% of CH4 sources is paddy fields. At some paddy fields, residual biomass left after the harvest is burned and plowed into soil. And at the other fields, unburned residue is directly plowed. It is an unsolved problem what impact is brought on CH4 budget during following cultivated period by the difference in the plowed biomass amount in soil after the harvest. In this study, an experimental paddy field was divided into two areas. At one area biomass residue is burned and at the other area residue is directly plowed. On that basis, long-term continuous measurements of micrometeorological CH4 flux were conducted in both areas. Experimental site is located reclaimed land in the southern part of Okayama Prefecture, Japan. Single rice cropping cultivation has continued in a similar way every year. Intermittent irrigation water managements, or 3-days flooded and 4-days drained conditions, were carried out during almost all the period of rice cultivated term. CH4 flux was calculated by aerodynamic gradient technique. The open biomass burning experiment was conducted at one area in November 29, 2011. We illustrate some results for the control term before the burning experiment, and for the comparison term after the experiment.

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

2012-12-01

46

DISSIPATION OF EPOXICONAZOLE IN THE PADDY FIELD UNDER SUBTROPICAL CONDITIONS OF TAIWAN  

Microsoft Academic Search

The environmental fate and distribution of fungicide epoxiconazole were studied by a rice paddy field model ecosystem. One week before the head-sprouting stage, rice plant was treated separately once with OPUS (tradename of epoxiconazole) 12% SC 2.1 kg ha and 1.4 kg ha , respectively. Soil, water and rice plant were sampled seven days intervals nine times after application. The

Haw-Tarn Lin; Sue-Sun Wong; Gwo-Chen Li

2001-01-01

47

Syntrophomonadaceae-Affiliated Species as Active Butyrate-Utilizing Syntrophs in Paddy Field Soil?†  

PubMed Central

DNA-based stable-isotope probing was applied to identify the active microorganisms involved in syntrophic butyrate oxidation in paddy field soil. After 14 and 21 days of incubation with [U-13C]butyrate, the bacterial Syntrophomonadaceae and the archaeal Methanosarcinaceae and Methanocellales incorporated substantial amounts of 13C label into their nucleic acids. Unexpectedly, members of the Planctomycetes and Chloroflexi were also labeled with 13C by yet-unclear mechanisms.

Liu, Pengfei; Qiu, Qiongfen; Lu, Yahai

2011-01-01

48

Wise use of paddy rice fields to partially compensate for the loss of natural wetlands  

Microsoft Academic Search

This paper reviews the scientific information related to climate change impacts on wetlands and functions of human-made wetlands\\u000a such as paddy rice field and treatment wetland are described to partially compensate for the loss of natural wetlands. Wetlands\\u000a are among the world’s most productive environments and are cradles of biological diversity, providing the water and primary\\u000a productivity upon which countless

Chun G. Yoon

2009-01-01

49

Fate of a genetically engineered escherichia coli bearing a plasmid in a paddy field microcosm  

Microsoft Academic Search

Escherichia coli DH5 a pBluescript II SK, bearing a plasmid which has a resistant gene to ampicillin as a genetically engineered bacteria (g?E. coli) and its parent E. coli DH5 a (p?E. coli), were introduced into a paddy field microcosm on the initial, 0.5th, 5th and 20th days after the microcosm was cultured. The population densities of both g?E. coli

Zen'Ichiro Kawabata; Kazuaki Matsui; Nobuyoshi Ishi

1997-01-01

50

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

Microsoft Academic Search

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

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

2006-01-01

51

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

52

Nitrous oxide emission measurement with acetylene inhibition method in paddy fields under flood conditions  

Microsoft Academic Search

Nitrous oxide (N2O) emission from flooded rice paddy fields was continuously measured by the closed chamber method at an experimental plot\\u000a in Thailand for a whole cultivation period. To characterize the N2O emission with regard to the denitrification N loss, the C2H2 inhibition method was applied. Flood water on the soil greatly suppressed the N2O emission. The N2O emission was

Toshiaki Iida; Sanjit Kumar Deb; Ram Gopal Kharbuja

2007-01-01

53

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

54

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

PubMed

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

55

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.

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

2014-01-01

56

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

57

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

58

Effects of residual biomass burning on the CO2 flux from a paddy field  

NASA Astrophysics Data System (ADS)

Paddy field is one of the most important eco-system in monsoon Asia, and takes a great important role in CO2 uptake. Carbon budget in agricultural field is influenced by some artificial management. After the harvest, residual biomass is burned on fields, brought out from fields, or remained and harrowed into the fields. If open burning was conducted in a field, one part of biomass carbon is emitted into atmosphere as CO2, and the other part is harrowed into soils. In this study, quantity of lost carbon according to burning of residual biomass were investigated at a single rice cropping field in western Japan, in which long-term continuous CO2 flux (NEE) measurement by the eddy-covariance technique was conducted. In addition, an experimental paddy field was divided into two areas to investigate what impact is brought on the annual CO2 flux by the difference of disposal management of residual biomass after the harvest. Residual biomass was burned and plowed into soil at the one area on Nov. 29th, 2011, and residue was not burned and directly plowed into soil at the other area as usual. We illustrate some results for the control term before the burning experiment, and for the comparison term after the experiment.

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

2012-12-01

59

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.

2011-01-01

60

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

PubMed

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

Rehmani, Muhammad Ishaq Asif; Zhang, Jingqi; Li, Ganghua; Ata-Ul-Karim, Syed Tahir; Wang, Shaohua; Kimball, Bruce A; Yan, Chuan; Liu, Zhenghui; Ding, Yanfeng

2011-01-01

61

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

62

Economic development, paddy field loss and rice output in China  

Microsoft Academic Search

Rice, mainly concentrated in southeast, south-middle, southwest and northeast region, is the most important grain crops in China. From 1985 to 2004, with rice sown area decreased, the rice output fluctuated; the share of rice output in total China rice output decreased from 31.99% to 23.82% in southeast region and from 46.04% to 45.45% in south-middle region; that of northeast

Pinghui Liu; Ziping Wu

63

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.

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

2013-01-01

64

[Effects of rice-duck farming system on biotic populations in paddy field].  

PubMed

A field experiment was conducted to study the effects of rice-duck farming on the related biotic populations in paddy field. The results showed that rice-duck farming had greater effects on the occurrence and damage of pests, pathogens and weeds, as well as the amount of pests' natural enemies in paddy field. The population of rice planthopper and leafhopper decreased by 64.8% and 78.5% after 12 and 42 days of duck-release, and the weeds decreased by 67.7% and 98.1% after 15 and 45 days of duck-release, respectively, compared with the control. The sheath blight index at the maximum tillering stage and full-heading stage in the rice-duck plots were 40.4% and 62.0% lower than those in the control plot, respectively. The population of spiders in duck-released field was increased obviously, which in turn decreased the damage of rice pests. PMID:18593042

Yu, Sheng-miao; Zhu, Lian-feng; Ouyang, You-nan; Xu, De-hai; Jin, Qian-yu

2008-04-01

65

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

NASA Astrophysics Data System (ADS)

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

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

66

Methane emission from fields with three various rice straw treatments in Taiwan paddy soils.  

PubMed

Flooded rice fields are one of the major biogenic methane sources. In this study, the effects of straw residual treatments on methane emission from paddy fields were discussed. The experimental field was located at Tainan District Agricultural Improvement Station in Chia-Yi county (23 degrees 25'08''N, 120degrees16'26''E) of southern Taiwan throughout the first and the second crop seasons in 2000. The seasonal methane fluxes in the first crop season with rice stubble removed, rice straw burned and rice straw incorporated were 4.41, 3.78 and 5.27 g CH4 m(-2), and the values were 32.8, 38.9 and 75.1 g CH4 m(-2) in the second crop season, respectively. In comparison of three management methods of rice straw residue, the incorporation of rice straw residue should show a significant tendency for enhancing methane emission in the second crop season. Moreover, stubble removed and straw burned treatments significantly reduced CH4 emissions by 28 approximately 56% emissions compared to straw incorporated plot. Concerning for air quality had led to legislation restricting rice straw burning, removing of rice stubble might be an appropriate methane mitigation strategy in Taiwan paddy soils. PMID:12856932

Liou, Rey-May; Huang, Shan-Ney; Lin, Chin-Wei; Chen, Shin-Hsiung

2003-07-01

67

Tunable diode laser measurements of methane fluxes from an irrigated rice paddy field in the Philippines  

NASA Astrophysics Data System (ADS)

This paper presents the first micrometeorological-based measurements of methane (CH4) emissions from Asian rice paddies of which we are aware. The research features the tunable diode laser trace gas analyzer system (TGAS) recently developed at the University of Guelph. CH4 fluxes were measured between March 9 and 24, 1992, from an irrigated rice paddy field at the International Rice Research Institute (IRRI), the Philippines. The daytime CH4 flux averaged 6.0 ?g m-2 s-1. The CH4 fluxes displayed a diurnal trend similar to daily soil temperature curves, with peak emissions of about 8 ?g m-2 s-1 in the early afternoon. A tenfold increase in CH4 emissions (to about 70?g m-2 s-1) during a brief weeding experiment resulted from soil disturbance. Up to 25 ?g m-2 s-1 of CH4 were released during a drying of the field, after which unsuitable soil redox potentials apparently suppressed methanogenesis. The CH4 flux was also arrested when the field was flooded with oxygen-rich water during a heavy rainstorm.

Simpson, I. J.; Thurtell, G. W.; Kidd, G. E.; Lin, M.; Demetriades-Shah, T. H.; Flitcroft, I. D.; Kanemasu, E. T.; Nie, D.; Bronson, K. F.; Neue, H. U.

1995-04-01

68

Effects of elevated CO2 and N fertilization on CH4 emissions from paddy rice fields  

NASA Astrophysics Data System (ADS)

The authors employed free-air carbon dioxide enrichment facilities for investigating the effects of elevating the present atmospheric CO2 by 200 ?mol mol-1 and increasing the application rate of urea-based fertilizers from 150 to 250 kg N ha-1 on CH4 emissions from paddy rice fields in southeastern China. The elevated CO2 significantly stimulated methane emission, which was mainly due to the stimulation in rice growth. Intensifying N fertilization mitigated the CH4 emission under the ambient CO2 but stimulated the CH4 emission under the elevated CO2. This suggests that N fertilization has a potential to stimulate both CH4 production and CH4 oxidation. Thus the net effect of N fertilization on CH4 emission from paddy rice fields most likely depends upon the counterbalance between the nitrogen-induced increases in CH4 production and CH4 oxidation, as a N excess may result in the inhibition of methane emission, whereas a N limitation may result in the stimulation of methane emission.

Xu, Zhongjun; Zheng, Xunhua; Wang, Yuesi; Han, Shenghui; Huang, Yao; Zhu, Jianguo; Butterbach-Bahl, Klaus

2004-09-01

69

[Prediction of methane emission of paddy field based on the support vector regression model].  

PubMed

The methane emission data of paddy fields was obtained by using the static chamber and gas chromatography, and six parameters including atmospheric temperature, soil temperature at 5 cm depth, pH of soil, Eh of soil, soil moisture and ground biomass were selected as the primary influencing factors of methane emission. The support vector regression (epsilon-SVR) model was built on the optimization of structural risk minimization, and the parameters of the epsilon-SVR model were optimized using Leave-one-out Cross Validation (LOOCV). The prediction accuracy of model was evaluated by k-fold cross validation with the mean relative error (MRE) and the root mean square error (RMSE). In addition, the accuracy of the epsilon-SVR model was analyzed by comparison with the Back Propagation-Artificial Neural Network (BP-ANN) model. The results indicated that the predicted value of the epsilon-SVR model with the parameters C and epsilon optimized by LOOCV was in good agreement with the measured value, and the average MRE of test samples was 44% and the average RMSE was 16.21 mg x (m2 x h)(-1) in the process of 11-fold cross validation. Compared with the BP-ANN model, the correlation coefficient was 0.863, and all the indicators were better. It demonstrated that the 8-SVR model could be applied to the prediction of methane emission of paddy fields. PMID:24191538

Chen, Qiang; Jiang, Wei-Guo; Chen, Xi; Yuan, Li-Hua; Wang, Wen-Jie; Pan, Ying-Zi; Wang, Wei; Liu, Xiao-Fu; Liu, Hai-Jiang

2013-08-01

70

The dynamics of arsenic in four paddy fields in the Bengal delta.  

PubMed

Irrigation with arsenic contaminated groundwater in the Bengal Delta may lead to As accumulation in the soil and rice grain. The dynamics of As concentration and speciation in paddy fields during dry season (boro) rice cultivation were investigated at 4 sites in Bangladesh and West Bengal, India. Three sites which were irrigated with high As groundwater had elevated As concentrations in the soils, showing a significant gradient from the irrigation inlet across the field. Arsenic concentration and speciation in soil pore water varied temporally and spatially; higher As concentrations were associated with an increasing percentage of arsenite, indicating a reductive mobilization. Concentrations of As in rice grain varied by 2-7 fold within individual fields and were poorly related with the soil As concentration. A field site employing alternating flooded-dry irrigation produced the lowest range of grain As concentration, suggesting a lower soil As availability caused by periodic aerobic conditions. PMID:21236535

Stroud, Jacqueline L; Norton, Gareth J; Islam, M Rafiqul; Dasgupta, Tapash; White, Rodger P; Price, Adam H; Meharg, Andrew A; McGrath, Steve P; Zhao, Fang-Jie

2011-04-01

71

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

Microsoft Academic Search

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

Myung Chae Jung; Iain Thornton

1997-01-01

72

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.

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

2012-01-01

73

Methane and nitrous oxide emissions from rice paddy fields as affected by nitrogen fertilisers and water management  

Microsoft Academic Search

Methane and N2O emissions affected by nitrogen fertilisers were measured simultaneously in rice paddy fields under intermittent irrigation in 1994. Ammonium sulphate and urea were applied at rates of 0 (control), 100 and 300 kg N ha-1. The results showed that CH4 emission, on the average, decreased by 42 and 60% in the ammonium sulphate treatments and 7 and 14%

Zucong Cai; Guangxi Xing; Xiaoyuan Yan; Hua Xu; Haruo Tsuruta; Kazuyuki Yagi; Katsuyuki Minami

1997-01-01

74

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

75

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

PubMed

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

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

2005-06-01

76

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

PubMed

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

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

2013-12-01

77

Rare earth element and clay minerals of paddy soils from the central region of the Mekong River, Laos  

Microsoft Academic Search

The rare earth elements (REE) content, particle-size distribution, and clay mineralogical composition were analyzed for the paddy soils collected from the central region of the Mekong River, Laos, to study the origin and inherent potentiality of soils. REE as the chondrite-normalized curve of the plot of Ce\\/Eu against Eu\\/Sm were found to be useful for grouping soils according to their

K. Egashira; K. Fujii; S. Yamasaki; P. Virakornphanich

1997-01-01

78

Spatial and temporal changes of cyanophage communities in paddy field soils as revealed by the capsid assembly protein gene g20.  

PubMed

Bacteriophages are ubiquitous in various environments. Our previous study revealed the diversity of the cyanophage community in paddy floodwater. In this study, the phylogeny and genetic diversity of cyanophage communities in paddy field soils were reported. The viral capsid assembly protein gene (g20) of cyanophage was amplified with the primers CPS1 and CPS8 from soil DNA extracted during two different sampling times at three sampling sites in Japan. The sequencing results indicated that about 93% of the clones were g20 genes. In total, 70 clones of g20 genes were obtained in this study, of which 69 clones were of cyanophage origin. As evaluated by g20 sequence assemblages in paddy field soils, the unifrac analyses results indicated that cyanophage communities changed among the sampling sites and times and differed from those communities detected in paddy floodwater. The phylogenetic analysis showed that the g20 sequences in paddy field soils were very diverse and distributed into Clusters ?, ? and ?, as well as four newly formed clusters. Within Clusters ? and ?, four unique subclusters were formed from the g20 clones that were only observed in this study. These findings suggested that the cyanophage communities in paddy field soils are different from those found in freshwater, marine water and paddy floodwater. PMID:21255050

Wang, Guanghua; Asakawa, Susumu; Kimura, Makoto

2011-05-01

79

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.

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

80

[Measurement difference in paddy field nitrogen leakage by using different type lysimeters].  

PubMed

Vertical and 'T' types of lysimeter were used to measure the concentrations of ammonia N, nitrate N, and total nitrogen (TN) in the leakage of paddy field in rice growth season under different N application levels. For ammonia N, its concentration measured with these two types of lysimeter all ranged in 0-8 mg x L(-1) in 2007 and 0-4 mg x L(-1) in 2006; for nitrate N, its concentration measured with vertical lysimeter was 0-4 mg x L(-1) in 2007 and basically the same in 2006, while that measured with 'T' type lysimeter was 0-20 mg x L(-1) in 2007 but lower in 2006. The TN concentration in the leakage was 0-60 mg x L(-1) in 2007, much higher than that (0-16 mg x L(-1)) in 2006. In the leakage, nitrate N was the dominant N form. The total leakage loss of N in whole rice growth season in 2007 was 15.81 kg x hm(-2) of TN and 9.33 kg x hm(-2) of nitrate N when measured with vertical lysimeter, and 7.21 kg x hm(-2) of TN and 4.25 kg x hm(-2) of nitrate N when measured with 'T' type lysimeter. Due to the difference in the pathways of ammonia-N and nitrate-N leakage, different methods for calculating N leakage should be employed when using the two types of lysimeter in measurement. The N leakage measured by vertical lysimeter was more close to that estimated by paddy plot-leaching measurement method. PMID:19803187

Wang, Mi; Chen, Zhi-Wei; Yang, Jing-Ping; Xu, Wei; Ge, Chang-Shui; Chen, Wen-Yue

2009-05-01

81

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

Microsoft Academic Search

To better understand the isotope biogeochemistry of paddy field CH4, we investigated carbon and hydrogen isotope fractionation during CO2 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

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

2002-01-01

82

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

Microsoft Academic Search

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

Mamoru Watanabe; Takayoshi Higashi

1989-01-01

83

Presence Tendency of Fish Species in Yatsu Paddy Field and Characterization for Indicator Species  

NASA Astrophysics Data System (ADS)

We analyzed presence tendency of fish species covering the result of surveys which had been performed every month for two years in Yatsu paddy fields, Chiba prefecture. In the result, there were 13 fish species and the number of loach, Misgurnus anguillicaudatus, was about 3/4 of the total number of all species. To analyze tendency of presence of fish species, we applied 3 methods. A few species stood out in the results from all 3 methods. We compared the environmental properties of the canals that these notable species represented with the properties of the other canals, or, the properties of canals in which those species were present with the properties of the other canals. At the result, in our target area, the analysis suggested that presence of many numbers of field gudgeon, Gnathopogon elongatus elongatus, would indicate higher possibility other species would be present and there would be better balanced species composition. And presence of field gudgeon would indicate a more suitable environment for not only field gudgeon but also other species would exist in the reach.

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

84

Land-use change and irrigation systems in the agricultural landscape of terraced paddy fields in Awaji Island, central Japan  

Microsoft Academic Search

We analyzed changes in land use from 1963 to 2000 in the northern part of Awaji Island in central Japan, using topographical\\u000a maps and aerial photographs. We compared these changes between two different irrigation systems: tazu, in which a community group jointly owns the rights to a water source, and private management. The study area consisted of\\u000a 57.3% paddy field,

Tomohiro Ichinose; I Gusti Agung Ayu Rai Asmiwyati; Miwa Kataoka; Nurhayati Hadi Susilo Arifin

2007-01-01

85

Density-dependent growth and reproduction of the apple snail, Pomacea canaliculata : a density manipulation experiment in a paddy field  

Microsoft Academic Search

To examine density dependence in the survival, growth, and reproduction of Pomacea canaliculata, we conducted an experiment in which snail densities were manipulated in a paddy field. We released paint-marked snails of\\u000a 15–20 mm shell height into 12 enclosures (pens) of 16 m2 at one of five densities – 8, 16, 32, 64, or 128 snails per pen. The survival

Koichi Tanaka; Tomonari Watanabe; Hiroya Higuchi; Kenji Miyamoto; Yoichi Yusa; Toru Kiyonaga; Hirotsugu Kiyota; Yoshito Suzuki; Takashi Wada

1999-01-01

86

Method of determination of some aromatic acids in soil solution from paddy fields by gas chromatography-mass spectrometry  

Microsoft Academic Search

A simplified method for the determination of benzoic 2-phenylpropionic, 3-phenylpropionic, and 4-phenylbutyric acids in paddy field soils using a gas chromatograph-mass spectrometer equipped with a capillary column is described. The entire procedure of this method involves the collection of the soil solution, extraction with chloroform, methylation of the acids with diazo- methane and analysis by gas chromatography-mass spectrometry. In this

Fukuyo Tanaka

1990-01-01

87

[Effects of winter cover crop on methane and nitrous oxide emission from paddy field].  

PubMed

Static chamber-GC technique was employed to study the effects of different treatment winter cover crops, including no-tillage and directly sowing ryegrass (T1), no-tillage and directly sowing Chinese milk vetch (T2), tillage and transplanting rape (T3), no-tillage and directly sowing rape (T4), and fallowing (CK), on the CH4 and N2O emission from double cropping rice paddy field. During the growth period of test winter cover crops, the CH4 and N2O emission in treatments T1-T4 was significantly higher than that in CK (P < 0.01). Treatments T1 and T3 not only had the largest CH4 emission (0.60 and 0.88 g x m(-2)), but also had the largest N2O emission (0.20 and 0.23 g x m(-2), respectively). After the winter cover crops returned to field, the CH4 emission from early and late rice fields in treatments T1, T2, T3, and T4 was larger than that in CK. In early rice field, treatments T1 and T2 had the largest CH4 emission (21.70 and 20.75 g x m(-2)); while in late rice field, treatments T3 and T4 had the largest one (58.90 and 54.51 g x m(-2) respectively). Treatments T1-T4 also had larger N2O emission from early and late rice fields than the CK did. The N2O emission from early rice field in treatments T1, T2, T3, and T4 was increased by 53.7%, 12.2%, 46.3%, and 29.3%, and that from late rice field in corresponding treatments was increased by 28.6%, 3.8%, 34.3%, and 27.6%, respectively, compared with CK. PMID:21443008

Tang, Hai-ming; Tang, Wen-guang; Shuai, Xi-qiang; Yang, Guang-li; Tang, Hai-tao; Xiao, Xiao-Ping

2010-12-01

88

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

PubMed

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

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

2014-07-01

89

Photolytic and photocatalytic degradation of quinclorac in ultrapure and paddy field water: identification of transformation products and pathways.  

PubMed

Quinclorac (QNC) is an effective but rather persistent herbicide commonly used in rice production. This herbicide presents a mean persistence in the environment so its residues are considered of environmental relevance. However, few studies have been conducted to investigate its environmental behavior and degradation. In the present work, direct photolysis and TiO(2) photocatalysis of the target compound in ultrapure and paddy field water were investigated. After 10h photolysis in ultrapure water, the concentration of QNC declined 26% and 54% at 250 and 700 W m(-2), respectively. However, the amount of quinclorac in paddy field water remained almost constant under the same irradiation conditions. QNC dissipated completely after 40 min of TiO(2) photocatalysis in ultrapure water, whereas 130 min were necessary to degrade 98% of the initial concentration in paddy field water. Possible QNC photolytic and photocatalytic degradation pathways are proposed after structure elucidation of the main transformation products, through liquid chromatography-electrospray ionization-quadrupole time-of-flight mass spectrometry and exact mass measurements. Pyridine ring hydroxylation at C-9 followed by ring opening and/or oxidative dechlorination were the key steps of QNC degradation. PMID:22316588

Pareja, Lucía; Pérez-Parada, Andrés; Agüera, Ana; Cesio, Verónica; Heinzen, Horacio; Fernández-Alba, Amadeo R

2012-05-01

90

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

91

DEVELOPMENT OF MULTI POLARIZATION SAR ALGORITHM FOR SOIL MOISTURE IN PADDY FIELD, CAMBODIA  

NASA Astrophysics Data System (ADS)

In Cambodia, agriculture is the important industry which engages many people. However, the water supplied only during rainy season is the source of water for agriculture. To use the limited water resources effectively, it is necessary to apply the water-resource management based on the meteorological prediction and the river runoff prediction. As the factor of these predictions, the soil moisture plays a key role in water and thermal transportation to the atmosphere, and the contribution of river runoff property. On the other hand, the soil moisture distribution with the paddy field scale is helpful in the agricultural activity and management. Therefore, Synthetic Aperture Radars (SAR) is expected to observe soil moisture with high spatial resolution in large area. Recently, some multi-polarization SAR have been in operation. The purpose of this study is to develop the algorithm to estimate soil moisture by using multi-polarization data acquired with the Phased Array type L-band Synthetic Aperture Radar (PALSAR) onboard the Advanced Land Observing Satellite (ALOS).

Aida, Kentaro; Koike, Toshio; Shi, Jiancheng

92

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

93

Diversity of cultivable methane-oxidizing bacteria in microsites of a rice paddy field: investigation by cultivation method and fluorescence in situ hybridization (FISH).  

PubMed

The diversity of cultivable methane-oxidizing bacteria (MOB) in the rice paddy field ecosystem was investigated by combined culture-dependent and fluorescence in situ hybridization (FISH) techniques. Seven microsites of a Japanese rice paddy field were the focus of the study: floodwater, surface soil, bulk soil, rhizosphere soil, root, basal stem of rice plant, and rice stumps of previous harvest. Based on pmoA gene analysis and transmission electron microscopy (TEM), four type I, and nine type II MOB isolates were obtained from the highest dilution series of enrichment cultures. The type I MOB isolates included a novel species in the genus Methylomonas from floodwater and this is the first type I MOB strain isolated from floodwater of a rice paddy field. In the type I MOB, two isolates from stumps were closely related to Methylomonas spp.; one isolate obtained from rhizosphere soil was most related to Methyloccocus-Methylocaldum-Methylogaea clade. Almost all the type II MOB isolates were related to Methylocystis methanotrophs. FISH confirmed the presence of both types I and II MOB in all the microsites and in the related enrichment cultures. The study reported, for the first time, the diversity of cultivable methanotrophs including a novel species of type I MOB in rice paddy field compartments. Refining growth media and culture conditions, in combination with molecular approaches, will allow us to broaden our knowledge on the MOB community in the rice paddy field ecosystem and consequently to implement strategies for mitigating CH? emission from this ecosystem. PMID:22446309

Dianou, Dayéri; Ueno, Chihoko; Ogiso, Takuya; Kimura, Makoto; Asakawa, Susumu

2012-01-01

94

Diversity of Cultivable Methane-Oxidizing Bacteria in Microsites of a Rice Paddy Field: Investigation by Cultivation Method and Fluorescence in situ Hybridization (FISH)  

PubMed Central

The diversity of cultivable methane-oxidizing bacteria (MOB) in the rice paddy field ecosystem was investigated by combined culture-dependent and fluorescence in situ hybridization (FISH) techniques. Seven microsites of a Japanese rice paddy field were the focus of the study: floodwater, surface soil, bulk soil, rhizosphere soil, root, basal stem of rice plant, and rice stumps of previous harvest. Based on pmoA gene analysis and transmission electron microscopy (TEM), four type I, and nine type II MOB isolates were obtained from the highest dilution series of enrichment cultures. The type I MOB isolates included a novel species in the genus Methylomonas from floodwater and this is the first type I MOB strain isolated from floodwater of a rice paddy field. In the type I MOB, two isolates from stumps were closely related to Methylomonas spp.; one isolate obtained from rhizosphere soil was most related to Methyloccocus-Methylocaldum-Methylogaea clade. Almost all the type II MOB isolates were related to Methylocystis methanotrophs. FISH confirmed the presence of both types I and II MOB in all the microsites and in the related enrichment cultures. The study reported, for the first time, the diversity of cultivable methanotrophs including a novel species of type I MOB in rice paddy field compartments. Refining growth media and culture conditions, in combination with molecular approaches, will allow us to broaden our knowledge on the MOB community in the rice paddy field ecosystem and consequently to implement strategies for mitigating CH4 emission from this ecosystem.

Dianou, Dayeri; Ueno, Chihoko; Ogiso, Takuya; Kimura, Makoto; Asakawa, Susumu

2012-01-01

95

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

96

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

PubMed

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

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

2014-01-01

97

Assessment of reclaimed wastewater irrigation impacts on water quality, soil, and rice cultivation in paddy fields.  

PubMed

The objective of this research was to monitor and assess the impact of reclaimed wastewater irrigation on water quality, soil, and rice cultivation by comparing the effects of various wastewater treatment levels on the growth and yield of rice. A randomized complete block design was used for the application methods of the wastewater effluents to paddy rice, with five treatments and six replications. The treatments were: control with groundwater irrigation (GW); irrigation with polluted water form a nearby stream (SW); and three treatments of reclaimed wastewater irrigation at different treatment levels. The three levels of wastewater treatments included wastewater effluents: (i) directly from the wastewater plant (WW); (ii) after passing through a sand filter (WSF); and (iii) after passing a sand filter followed by an ultraviolet treatment (WSFUV). Each plot was 4 x 4 m and was planted with rice (Oryza sativa L.) in 2002 and 2003. The results indicated that irrigation of rice with reclaimed municipal wastewater caused no adverse effects on the growth and yield of rice. The chemical compositions of the rice from all plots were within the normal ranges of brown rice quality in Korea. No adverse effects were observed on chemical concentrations including the heavy metals Cu, As, Cd, Zn, Hg, and Pb, in either the brown rice or the field. The results showed that treated municipal wastewater can be safely used as an alternative water source for the irrigation of rice, although continued monitoring will be needed to determine the long-term effects with regard to soil contamination and other potential health concerns. PMID:17365313

Kang, Moon Seong; Kim, Sang Min; Park, Seung Woo; Lee, Jeong Jae; Yoo, Kyung H

2007-03-01

98

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

SciTech Connect

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

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

2003-02-27

99

Assessment of reclaimed wastewater irrigation impacts on water quality, soil, and rice cultivation in paddy fields  

Microsoft Academic Search

The objective of this research was to monitor and assess the impact of reclaimed wastewater irrigation on water quality, soil, and rice cultivation by comparing the effects of various wastewater treatment levels on the growth and yield of rice. A randomized complete block design was used for the application methods of the wastewater effluents to paddy rice, with five treatments

Moon Seong Kang; Sang Min Kim; Seung Woo Park; Jeong Jae Lee; Kyung H. Yoo

2007-01-01

100

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

Microsoft Academic Search

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

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

2007-01-01

101

Source areas for a passively diffusing methane gas from South Asian paddy fields using the Flux Footprint Model  

NASA Astrophysics Data System (ADS)

The annual rate of methane emissions from paddy fields is uncertain due to the differences in climatic conditions, soil characteristics, duration and patterns of flooding, and other parameters. Thus it is important to identify and estimate the source patches of methane emissions from the paddy fields, and also the magnitude of the flux. The main aim of this work is to identify and quantify the specific source areas for passively diffusing methane gas from a typical South Asian Paddy Field. The SAM2 model is used to characterize each of the source patches corresponding to each of the methane fluxes computed by an indirect method, based on the analytical solution of the Eulerian advection-diffusion equation for vertical diffusion. The results of the model are presented as characteristic dimensions of the source patches: the maximum source location (i.e. the upwind distance of the surface element with the maximum-weight influence), the near and far ends of the source area, and its maximal lateral extension. Micrometeorological parameters like wind direction, wind speed, temperature, relative humidity and concentration of methane gas are measured at certain time intervals. These data are fed into the meteorological pre-processor to generate time dependent atmospheric scaling factors (Richardson Number, Monin-Obukhov Length etc.). These are used directly in SAM2 to generate the elliptic patches with P (the fraction of the total integrated source weight function) varying from 40% (stable) to 99% (unstable). The simulations of SAM2 are related directly to the non-dimensional surface-layer scaling variables by the well-known Levenburg-Marquardt Non-Linear Least Square Method in a parameterized model, which provides a user-friendly estimate of the surface area responsible for the measured methane concentration. The application of SAM2 allows us to draw conclusions about the appropriateness of the spatial representation and localness of methane concentration measurements.

Mukherjee, Ranjan; Sarkar, Ujjaini; Hobbs, Stephen E.

2012-02-01

102

Differences in ecological impacts of systemic insecticides with different physicochemical properties on biocenosis of experimental paddy fields.  

PubMed

The environmental risks of pesticides are typically determined by laboratory single-species tests based on OECD test guidelines, even if biodiversity should also be taken into consideration. To evaluate how realistic these assessments are, ecological changes caused by the systemic insecticides imidacloprid and fipronil, which have different physicochemical properties, when applied at recommended commercial rates on rice fields were monitored using experimental paddy mesocosms. A total of 178 species were observed. There were no significant differences in abundance of crop arthropods among the experimental paddies. However, zooplankton, benthic and neuston communities in imidacloprid-treated field had significantly less abundance of species than control and fipronil fields. Significant differences in abundance of nekton community were also found between both insecticide-treated paddies and control. Influences on the growth of medaka fish were also found in both adults and their fries. Both Principal Response Curve analysis (PRC) and Detrended Correspondence Analysis (DCA) showed the time series variations in community structure among treatments, in particular for imidacloprid during the middle stage of the experimental period. These results show the ecological effect-concentrations (LOEC ~ 1 ?g/l) of these insecticides in mesocosms, especially imidacloprid, are clearly different from their laboratory tests. We suggest that differences in the duration of the recovery process among groups of species are due to different physicochemical properties of the insecticides. Therefore, realistic prediction and assessment of pesticide effects at the community level should consider not only the sensitivity traits and interaction among species but also the differences in physicochemical characteristics of each pesticide. PMID:21877228

Hayasaka, Daisuke; Korenaga, Tomoko; Sánchez-Bayo, Francisco; Goka, Koichi

2012-01-01

103

Development of methane emission factors for Indian paddy fields and estimation of national methane budget.  

PubMed

A state-wise assessment of methane (CH(4)) budget for Indian paddies, based on a decadal measurement data across India is presented for the calendar year (CY) 1994, the base year for India's Initial National Communication (NATCOM) to the United Nations Framework Convention on Climate Change (UNFCCC), along with national trend from CY 1979 to 2006. The NATCOM CH(4) emission factors (EFs) for Indian paddy cultivation areas, generally having less than 0.7% of soil organic carbon (SOC), have been estimated as 17.48+/-4 g m(-2) for irrigated continuously flooded (IR-CF), 6.95+/-1.86 g m(-2) for rain-fed drought prone (RF-DP), 19+/-6 g m(-2) for rain-fed flood prone (RF-FP) and deep-water (DW), 6.62+/-1.89 g m(-2) for irrigated intermittently flooded single aeration (IR-IF-SA) and 2.01+/-1.49 g m(-2) for IR-IF multiple aeration (MA) paddy water regimes. The state-wise study for 1994 has indicated national CH(4) budget estimate of 4.09+/-1.19 Tg y(-1) and the trend from 1979 to 2006 was in the range of 3.62+/-1 to 4.09+/-1.19 Tg y(-1). Four higher emitting or "hot spot" states (West Bengal, Bihar, Madhya Pradesh and Uttar Pradesh) have accounted for 53.9% of total CH(4) emission with RF-FP paddy water regime as the major contributor. CH(4) emissions were enhanced by factors such as SOC ( approximately 1.5 times due to increase in SOC by approximately 1.8 times), paddy cultivars (approximately 1.5 times), age of seedlings (approximately 1.4 times), and seasons (approximately 1.8 times in Kharif or monsoon than in Rabi or winter season). PMID:18996564

Gupta, Prabhat K; Gupta, Vandana; Sharma, C; Das, S N; Purkait, N; Adhya, T K; Pathak, H; Ramesh, R; Baruah, K K; Venkatratnam, L; Singh, Gulab; Iyer, C S P

2009-01-01

104

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

105

Estimation of methane and nitrous oxide emission from paddy fields and uplands during 1990-2000 in Taiwan.  

PubMed

To investigate the greenhouse gases emissions from paddy fields and uplands, methane and nitrous oxide emissions were estimated from local measurement and the IPCC guidelines during 1990-2000 in Taiwan. Annual methane emission from 182,807 to 242,298 ha of paddy field in the first crop season ranged from 8,062 to 12,066 ton, and it was between 16,261 and 25,007 ton for 144,178-211,968 ha in the second crop season with local measurement. The value ranged from 12,132 to 17,465 ton, and from 16,046 to 24,762 ton of methane in the first and second crop season with the IPCC guidelines for multiple aeration treatments, respectively. Annual nitrous oxide emission was between 472 and 670 ton and between 236 and 359 ton in the first and second crop season, respectively. Methane and nitrous oxide emissions from uplands depend on crop, growth season, fertilizer application and environmental conditions. Annual methane emission from upland crops, vegetable, fruit, ornamental plants, forage crops and green manure crops was 138-252, 412-460, 97-100, 3-5, 4-5 and 3-51 ton, respectively. Annual nitrous oxide emission was 1,080-1,976, 1,784-1,994, 2,540-2,622, 31-54, 43-53 and 38-582 ton, respectively. Annual nitrous oxide emission ranged from 91 to 132 ton for 77,593-11,2095 ton of nitrogen-fixing crops, from 991 to 1,859 ton for 3,259,731-6,183,441 ton of non-nitrogen-fixing crops, and from 1.77 to 2.22 Gg for 921,169-1,172,594 ton of chemical fertilizer application. In addition, rice hull burning emitted 19.3-24.2 ton of methane and 17.2-21.5 ton of nitrous oxide, and corn stalk burning emitted 2.1-4.2 ton of methane and 1.9-3.8 ton of nitrous oxide. Methane emission from the agriculture sector was 26421-37914 ton, and nitrous oxide emission was 9810-11,649 ton during 1990-2000 in Taiwan. Intermittent irrigation in paddy fields reduces significantly methane emission; appropriate application of nitrogen fertilization and irrigation in uplands and paddy fields also decreases nitrous oxide emission. PMID:12852981

Yang, Shang-Shyng; Liu, Chung-Ming; Lai, Chao-Ming; Liu, Yen-Lan

2003-09-01

106

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

107

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

108

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

PubMed

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

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

2013-12-01

109

Carbon sequestration of paddy fields in Western Jilin of China during 1989–2004  

Microsoft Academic Search

The study area of this article, Western Jilin province of China, was a typical area responding to global changing in middle\\u000a latitude areas. In this paper, by interpreting the thematic mapper (TM) images of the study area in the years of 1989, 1996,\\u000a 2000 and 2004, the land use\\/cover change (LUCC) data were achieved, which included the area of paddy

Jie Tang; Xiaoming Xu; Zhaoyang Li; Weizheng Han

2012-01-01

110

Development of methane emission factors for Indian paddy fields and estimation of national methane budget  

Microsoft Academic Search

A state-wise assessment of methane (CH4) budget for Indian paddies, based on a decadal measurement data across India is presented for the calendar year (CY) 1994, the base year for India’s Initial National Communication (NATCOM) to the United Nations Framework Convention on Climate Change (UNFCCC), along with national trend from CY 1979 to 2006. The NATCOM CH4 emission factors (EFs)

Prabhat K. Gupta; Vandana Gupta; C. Sharma; S. N. Das; N. Purkait; T. K. Adhya; H. Pathak; R. Ramesh; K. K. Baruah; L. Venkatratnam; Gulab Singh; C. S. P. Iyer

2009-01-01

111

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

PubMed

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

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

2009-01-01

112

Forest bound estuaries are higher methane emitters than paddy fields: A case of Godavari estuary, East Coast of India  

NASA Astrophysics Data System (ADS)

In the Godavari estuary, ambient methane concentrations were monitored for a period of 5 years and the data reveals that the estuary sampling stations have shown a high average maximum value of methane 14.8 ppmv while nearby paddy field sampling stations the methane concentration were 3-4 fold lower than the estuary. The acidic nature of the estuary soils (pH 5.8-6.2) along with redox potential -120mV favours high methane emissions. The samples collected from the edge of the estuary have shown 0.12-0.15% of Fe wherein ambient methane concentrations were 4.8-5.6 ppmv. It was observed that the anoxic condition with high available iron in the soil improves anaerobic decomposition of organic matter to produce methane. The litter production from nearby mangrove vegetation in the estuary is approximately 22,000 tons/annum is a causative factor for higher methane emissions. Remote sensing data was used and developed thematic maps for spatial and temporal distribution of methane using geographical information system. The seasonal trend showed high ambient concentration of methane in winter season, which is mainly due to high moisture content, (OH?) radical and lower temperature. The results suggest that high organic matter (2.5-4.2%) along with soil conditions in the estuary are influencing for higher methane emissions, while in paddy fields the available organic matter for methanogenesis is limited.

Krupadam, Reddithota J.; Ahuja, Rashmi; Wate, Satish R.; Anjaneyulu, Yerramilli

113

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

114

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.

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

2013-01-01

115

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

PubMed Central

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

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

2010-01-01

116

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

PubMed

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

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

2013-01-01

117

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

118

Monitoring of selected pesticides residue levels in water samples of paddy fields and removal of cypermethrin and chlorpyrifos residues from water using rice bran.  

PubMed

Consumption of pesticides associated foods increased in recent decades in Bangladesh. Most of the pesticides come from paddy, as rice is the main food items here and about 70 % pesticides are used only on paddy fields. Water samples of paddy fields and Kaliganga River of Manikganj district were analyzed to provide base line data on cypermethrin, chlorpyrifos and diazinon residue by using high performance liquid chromatography. Levels of Cypermethrin, chlorpyrifos and diazinon detected in the paddy field water samples were (0.605 ± 0.011 ?g/L), (0.06 ± 0.001 ?g/L) and (0.039 ± 0.002 ?g/L), respectively. 0.11 ± 0.003 ?g/L of cypermethrin and 0.012 ± 0.0006 ?g/L of chlorpyrifos were also identified in the water samples of Kaligonga River. Diazinon residue was not detected in the river water samples. The detected concentrations of pesticide residues in the river water were below the accepted maximum residue limit (MRL) value of drinking water (0.1 ?g/l) adopted by the FAO/WHO Codex Alimentarius Commission. Cypermethrin and chlorpyrifos were chosen for decontamination through rice bran, as it was found in river water. Two gm rice bran could easily decontaminated 95.6 % and 96.4 % of cypermethrin and chlorpyrifos. The result of this study showed that pesticide residue was detected in water samples were below the MRLs value, which can easily be decontaminated through absorption of rice bran. PMID:22627618

Bhattacharjee, Shubhra; Fakhruddin, A N M; Chowdhury, M A Z; Rahman, M A; Alam, M K

2012-08-01

119

The genotype of the calcium/calmodulin-dependent protein kinase gene (CCaMK) determines bacterial community diversity in rice roots under paddy and upland field conditions.  

PubMed

The effects of the Oryza sativa calcium/calmodulin-dependent protein kinase OsCCaMK genotype (dominant homozygous [D], heterozygous [H], recessive homozygous [R]) on rice root-associated bacteria, including endophytes and epiphytes, were examined by using a Tos17 rice mutant line under paddy and upland field conditions. Roots were sampled at the flowering stage and were subjected to clone library analyses. The relative abundance of Alphaproteobacteria was noticeably decreased in R plants under both paddy and upland conditions (0.8% and 3.0%, respectively) relative to those in D plants (10.3% and 17.4%, respectively). Population shifts of the Sphingomonadales and Rhizobiales were mainly responsible for this low abundance in R plants. The abundance of Anaerolineae (Chloroflexi) and Clostridia (Firmicutes) was increased in R plants under paddy conditions. The abundance of a subpopulation of Actinobacteria (Saccharothrix spp. and unclassified Actinosynnemataceae) was increased in R plants under upland conditions. Principal coordinate analysis revealed unidirectional community shifts in relation to OsCCaMK gene dosage under both conditions. In addition, shoot length, tiller number, and plant weight decreased as the OsCCaMK gene dosage decreased under upland conditions. These results suggest significant impacts of OsCCaMK on both the diversity of root-associated bacteria and rice plant growth under both paddy and upland field conditions. PMID:21551283

Ikeda, Seishi; Okubo, Takashi; Takeda, Naoya; Banba, Mari; Sasaki, Kazuhiro; Imaizumi-Anraku, Haruko; Fujihara, Shinsuke; Ohwaki, Yoshinari; Ohshima, Kenshiro; Fukuta, Yoshimichi; Eda, Shima; Mitsui, Hisayuki; Hattori, Masahira; Sato, Tadashi; Shinano, Takuro; Minamisawa, Kiwamu

2011-07-01

120

The Genotype of the Calcium/Calmodulin-Dependent Protein Kinase Gene (CCaMK) Determines Bacterial Community Diversity in Rice Roots under Paddy and Upland Field Conditions ? †  

PubMed Central

The effects of the Oryza sativa calcium/calmodulin-dependent protein kinase OsCCaMK genotype (dominant homozygous [D], heterozygous [H], recessive homozygous [R]) on rice root-associated bacteria, including endophytes and epiphytes, were examined by using a Tos17 rice mutant line under paddy and upland field conditions. Roots were sampled at the flowering stage and were subjected to clone library analyses. The relative abundance of Alphaproteobacteria was noticeably decreased in R plants under both paddy and upland conditions (0.8% and 3.0%, respectively) relative to those in D plants (10.3% and 17.4%, respectively). Population shifts of the Sphingomonadales and Rhizobiales were mainly responsible for this low abundance in R plants. The abundance of Anaerolineae (Chloroflexi) and Clostridia (Firmicutes) was increased in R plants under paddy conditions. The abundance of a subpopulation of Actinobacteria (Saccharothrix spp. and unclassified Actinosynnemataceae) was increased in R plants under upland conditions. Principal coordinate analysis revealed unidirectional community shifts in relation to OsCCaMK gene dosage under both conditions. In addition, shoot length, tiller number, and plant weight decreased as the OsCCaMK gene dosage decreased under upland conditions. These results suggest significant impacts of OsCCaMK on both the diversity of root-associated bacteria and rice plant growth under both paddy and upland field conditions.

Ikeda, Seishi; Okubo, Takashi; Takeda, Naoya; Banba, Mari; Sasaki, Kazuhiro; Imaizumi-Anraku, Haruko; Fujihara, Shinsuke; Ohwaki, Yoshinari; Ohshima, Kenshiro; Fukuta, Yoshimichi; Eda, Shima; Mitsui, Hisayuki; Hattori, Masahira; Sato, Tadashi; Shinano, Takuro; Minamisawa, Kiwamu

2011-01-01

121

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

PubMed Central

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.

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

2013-01-01

122

Impact of plant genotype and nitrogen level on rice growth response to inoculation with Azospirillum sp. strain B510 under paddy field conditions  

Microsoft Academic Search

Twenty rice cultivars, including three genetically-distinct groups (japonica, indica-1, and indica-2), were evaluated for their response to inoculation with Azospirillum sp. strain B510 in paddy fields with standard nitrogen (SN) and low nitrogen (LN) fertilization. In the SN field, the tiller numbers in most indica-2 cultivars, 37?days after transplanting (DAT), were significantly increased by the B510 inoculation, whereas those in

Kazuhiro Sasaki; Seishi Ikeda; Shima Eda; Hisayuki Mitsui; Eiko Hanzawa; Chiharu Kisara; Yuri Kazama; Atsuhiko Kushida; Takuro Shinano; Kiwamu Minamisawa; Tadashi Sato

2010-01-01

123

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

124

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

125

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

PubMed

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

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

2013-03-01

126

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

Microsoft Academic Search

Ammonia (NH3) volatilization from a paddy field following applications of urea was measured. Two lysimeters of Gray Lowland soil with a pH (H2O) of 5.7 were used for the experiment. Urea was applied at a rate of 50 kg N ha?1 by incorporation as the basal fertilization (BF) and at rates of 30 and 10 kg N ha?1 by top-dressing as the

Kentaro Hayashi; Seiichi Nishimura; Kazuyuki Yagi

2008-01-01

127

Influence of Temperature and Oil Content on the Soil\\/Air Partition Coefficient for Hexachlorobenzene in Oil-Contaminated Rice Paddy Field Soil  

Microsoft Academic Search

The soil\\/air partition coefficients (KSA) for hexachlorobenzene (HCB) in oil-contaminated (crude oil and diesel) rice paddy field soils were measured in a solid fugacity meter at different oil concentrations over the temperature range of 5 to 30°C at 100% relative humidity. The results showed that values of KSA increased with a decrease of temperature. As for oil content, there is

Xin He; Shuo Chen; Xie Quan; Huimin Zhao; Yazhi Zhao

2011-01-01

128

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

PubMed

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

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

2012-08-01

129

[Effects of no-tillage and stubble-remaining on soil enzyme activities in broadcasting rice seedlings paddy field].  

PubMed

A field experiment was conducted to study the effects of four cultivation modes (conventional tillage, no-tillage, conventional tillage + stubble-remaining, and no-tillage + stubble-remaining) on the activities of urease, acid phosphatase, protease, and cellulose in different soil layers in a broadcasting rice seedlings paddy field. Under the four cultivation modes, the activities of test enzymes were higher in upper than in deeper soil layers, and had a greater difference between the soil layers under no-tillage + stubble-remaining. In upper soil layers, the activities of test enzymes were higher in the treatments of no-tillage than in the treatments of conventional tillage, being the highest under no-tillage + stubble-remaining and the lowest under conventional tillage. In deeper soil layers, the test enzyme activities were the highest under conventional tillage + stubble-remaining, followed by no-tillage + stubble-remaining, no-tillage, and conventional tillage. During the growth period of rice, soil urease and cellulose activities were lower at tillering stage, increased to the maximum at booting stage, and decreased then, soil acid phosphatase activity was higher at tillering stage but lower at elongating stage, whereas soil protease activity peaked at tillering and heading stages. PMID:22303669

Ren, Wan-Jun; Huang, Yun; Wu, Jin-Xiu; Liu, Dai-Yin; Yang, Wen-Yu

2011-11-01

130

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

PubMed

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

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

2007-01-01

131

Diversity of Bacteriophages Infecting Xanthomonas oryzae pv. oryzae in Paddy Fields and Its Potential to Control Bacterial Leaf Blight of Rice.  

PubMed

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

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

2014-06-28

132

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.

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

2012-01-01

133

Copper and Zinc in a paddy field and their potential ecological impacts affected by wastewater from a lead/zinc mine, P. R. China.  

PubMed

As well known, at normal levels, copper and zinc are essential micronutrients for plants, animals, and humans. However, excessive Cu and Zn are toxic and disturb a wide range of biochemical and physiological processes. Using Atomic Absorption Spectrophotometer (AAS; Perkin-Elmer 3030, USA), soil and rice plant (Oryza sativa L.) samples collected from a paddy field in Lechang lead-zinc mine area, Guangdong Province, China were analyzed and their potential ecological impacts to local human and livestock were evaluated. The results showed that the paddy soils were contaminated with Cu and Zn. Both metals in soils had low bio-available fractions for paddy plants, animal and human by three chemically analytical techniques. Generally, were concentrations of copper and zinc root > straw > stalk > grain with hull > grain without hull (i.e. unpolished rice) and in the normal ranges indicating no ecological risk for local livestock and residents. All positive correlation coefficients, however, between heavy metals in rice plant and total, exchangeable (step 1 in Tessier's method established in 1979) and DTPA-extractable fractions in soils were found in this study indicating that elevated heavy metal in soils would increase long-term exposition and possible consequence of ecological hazard through food chains. PMID:18074233

Yang, Qing-Wei; Lan, Chong-Yu; Shu, Wen-Sheng

2008-12-01

134

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

135

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

136

Bacterial diversity and bioaugmentation in floodwater of a paddy field in the presence of the herbicide molinate.  

PubMed

This work aimed at studying variations on the diversity and composition of the bacterial community of a rice paddy field floodwater, subjected to conventional management, namely by using the herbicide molinate. The promotion of the herbicide biodegradation either by the autochthonous microbiota or by a bioaugmentation process was also assessed. This study comprehended four sampling campaigns at key dates of the farming procedures (seeding, immediately and 6 days after application of the herbicide molinate, and after synthetic fertilization) and the subsequent physic-chemical and microbiological characterization (pH, DOC and molinate contents, total cells, cultivable bacteria and DGGE profiling) of the samples. Multivariate analysis of the DGGE profiles showed temporal variations in the bacterial community structure and the Shannon's index values indicated that the bacterial diversity reached its minimum at the molinate application day. The highest bacterial diversity coincided with the periods with undetectable concentrations of the herbicide, although microcosm assays suggested that other factors than molinate may have been responsible for the decrease of the bacterial diversity. The ability of autochthonous microorganisms to degrade molinate and the influence of the herbicide on the bacterial community composition were assessed in microcosm assays using floodwater collected at the same dates. Given molinate was not degraded by autochthonous microorganisms, and considering it represents an environmental contaminant, bioaugmentation microcosms were assayed aiming the assessment of the feasibility of a bioremediation process to clean contaminated floodwater. A molinate-mineralizing culture, previously isolated, promoted molinate removal, induced alterations in the autochthonous bacterial community structure and diversity, and was undetected after 7 days of incubation, suggesting the feasibility of the process. PMID:20862524

Barreiros, Luisa; Manaia, Célia M; Nunes, Olga C

2011-04-01

137

Methylomonas koyamae sp. nov., a type I methane-oxidizing bacterium from floodwater of a rice paddy field.  

PubMed

A novel methane-oxidizing bacterium, strain Fw12E-Y(T), was isolated from floodwater of a rice paddy field in Japan. Cells of strain Fw12E-Y(T) were Gram-negative, motile rods with a single polar flagellum and type I intracytoplasmic membrane arrangement. The strain grew only on methane or methanol as sole carbon and energy source. It was able to grow at 10-40 °C (optimum 30 °C), at pH 5.5-7.0 (optimum 6.5) and with 0-0.1% (w/w) NaCl (no growth above 0.5% NaCl). 16S rRNA gene sequence analysis showed that strain Fw12E-Y(T) is related most closely to members of the genus Methylomonas, but at low levels of similarity (95.0-95.4%). Phylogenetic analysis of pmoA and mxaF genes indicated that the strain belongs to the genus Methylomonas (97 and 92?% deduced amino acid sequence identities to Methylomonas methanica S1(T), respectively). The DNA G+C content of strain Fw12E-Y(T) was 57.1 mol%. Chemotaxonomic data regarding the major quinone (MQ-8) and major fatty acids (C(16:1) and C(14:0)) also supported its affiliation to the genus Methylomonas. Based on phenotypic, genomic and phylogenetic data, strain Fw12E-Y(T) is considered to represent a novel species of the genus Methylomonas, for which the name Methylomonas koyamae sp. nov. is proposed. The type strain is Fw12E-Y(T) (?=?JCM 16701(T)?=?NBRC 105905(T)?=?NCIMB 14606(T)). PMID:21984674

Ogiso, Takuya; Ueno, Chihoko; Dianou, Dayéri; Huy, Tran Van; Katayama, Arata; Kimura, Makoto; Asakawa, Susumu

2012-08-01

138

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

139

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

140

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

141

Salt crust development in paddy fields owing to soil evaporation and drainage: Contribution of chloride and deuterium profile analysis  

NASA Astrophysics Data System (ADS)

SummaryIn Northeast Thailand lowlands with shallow saline watertable, rainfed paddy fields often present high salt concentration in the dry season, forming patches or spots of salt crusts on the soil surface. In this context, the mechanisms implied in salt concentration during dry season were studied by establishing salt budget with evaporation and drainage estimates inside and outside a saline patch. Drainage was estimated by Hydrus-1D modelling constrained by an hydrodynamic characterization and the profile of water contents at the end of dry season. Evaporation rates at the end of the dry season were computed by interpreting natural detailed profiles of deuterium (D) and chloride (Cl) contents. Because of the drastic diminution of hydraulic conductivity at saturation with depth and the decrease of groundwater level at the end of the cropping season, simulated hydrological balance with Hydrus-1D pointed out zero cumulated fluxes for depths of 39.5 cm (outside the saline patch) and 37.5 cm (inside the saline patch). Therefore, all the chloride accumulated in the very upper layers during dry season comes from the chloride that was present in the 0-39.5 cm layers before the beginning of the drying. Inside the saline patch, the tentative Cl budget is coherent with the hypothesis of saturation of the profile by aquifer saline water during the flooding. Evaporation rates computed from the diffusion of chloride and deuterium at the end of the drying season, when the aquifer level was 1.4 m deep, range between 0.121 and 0.378 mm d -1. This does not sustain the assumption of a considerable salinity contribution from the aquifer during the dry season. Moreover, evaporation estimates based on Cl and D diffusion equilibrium showed depleted rates (38-63%) inside the saline patch due to salt accumulation in the first 12 cm of the soil. In the vapour transfer layer, estimated evaporation rate based on the vapour movement of D was in the same order of magnitude than computed rate assuming liquid Cl diffusion. This coincidence is attributed to the liquid fluxes that occurred during the expansion of the vapour transfer layer during the progression of the evaporation front.

Grünberger, Olivier; Macaigne, Peggy; Michelot, Jean-Luc; Hartmann, Christian; Sukchan, Somsak

2008-01-01

142

The relationships between the structure of paddy levees and the plant species diversity in cultural landscapes on the west side of Lake Biwa, Shiga, Japan  

Microsoft Academic Search

Paddy levees form networks of narrow linear habitats and play various roles in cultural landscapes. Traditional landscapes on the west side of Lake Biwa consist of paddy field terraces and both “stone” and “soil” levees that have been maintained by paddy field management using local resources. Paddy levees in this study site are principally classified into five different types. Our

Katsue Fukamachi; Hirokazu Oku; Aiko Miyake

2005-01-01

143

Optimizing grain yields reduces CH4 emissions from rice paddy fields.  

PubMed

Microbial production in anoxic wetland rice soils is a major source of atmospheric CH4 the most important non-CO2 greenhouse gas. Much higher CH4 emissions from well managed irrigated rice fields in the wet than in the dry season could not be explained by seasonal differences in temperature. We hypothesized that high CH4 emissions in the wet season are caused by low grain to biomass ratios. In a screenhouse experiment, removing spikelets to reduce the plants' capacity to store photosynthetically fixed C in grains increased CH4 emissions, presumably via extra C inputs to the soil. Unfavorable conditions for spikelet formation in the wet season may similarly explain high methane emissions. The observed relationship between reduced grain filling and CH4 emission provides opportunities to mitigate CH4 emissions by optimizing rice productivity. PMID:12189212

Denier Van Der Gon, H A C; Kropff, M J; Van Breemen, N; Wassmann, R; Lantin, R S; Aduna, E; Corton, T M; Van Laar, H H

2002-09-17

144

Rural wastewater irrigation and nitrogen removal by the paddy wetland system in the Tai Lake region of China  

Microsoft Academic Search

Background, aim, and scope  A large area of water eutrophication in the Tai Lake region of China was associated with nitrogen (N) and phosphorus (P) pollution,\\u000a mainly due to the discharge of untreated rural wastewater (RW) into the surface water (SW) near villages of this region. A\\u000a field experiment was conducted, using irrigation of RW plus urea fertilization under equal nitrogen

Song Li; Hua Li; Xingqiang Liang; Yingxu Chen; Zhihong Cao; Zhihong Xu

2009-01-01

145

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.

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

2012-01-01

146

Methane flux from irrigated paddy and dryland rice fields, and from seasonally dry tropical forest and Savanna soils of India  

Microsoft Academic Search

Methane flux was measured from four tropical, Indian ecosystems: dryland, irrigated rice, seasonally dry forest and savanna. Flux from the irrigated rice paddies was in the range 2.14–8.23mgCH4m?2h?1 during the crop period. In contrast, the dryland rice soil consumed 0.12–0.90mgCH4m?2h?1. Application of wheat straw+fertilizer stimulated CH4 production in irrigated rice soil while it reduced CH4 consumption in dryland rice plots.

J. S. Singh; A. S. Raghubanshi; V. S. Reddy; S. Singh; A. K. Kashyap

1998-01-01

147

Beta-Glucosidase Activity in Paddy Soils of the Taihu Lake Region, China 1 1 Project supported by the National Natural Science Foundation of China (No. 40371066) and the National Key Basic Research Support Foundation of China (No. G1999011808)  

Microsoft Academic Search

The profile distribution of ?-gulcosidase activity in twelve typical paddy soil profiles with high productivity in the Taihu Lake region of China were investigated. Activities of ?-gulcosidase in the plow layers were in the range of 52.68–137.02 ?g PNP g?1 soil h?1 with a mean of 89.22 ?g PNP g?1 soil h?1. However, most plow layers ranged from 70 to

Xiao-Chang WANG; Qin LU

2006-01-01

148

[Responses of enzyme activities in different particle-size aggregates of paddy soil in Taihu Lake region of China to long-term fertilization].  

PubMed

Taking a long-term fertilized paddy soil in Taihu Lake region as research object, the enzyme activities in <2, 2-20, 20-200, and 200-2000 microm aggregates under no fertilization (NF), chemical fertilization (CF), chemical fertilization plus straw return (CFS), and chemical fertilization plus pig manure (CFM) were investigated. Fertilization promoted the formation of 200-2000 microm aggregates significantly. The enzyme activities differed with aggregates' particle-size. Urease and invertase activities were the highest in <2 microm aggregates, whereas the activities of cellulase, polyphenoloxidase and FDA hydrolase were the highest in 200-2000 microm aggregates. Fertilization, especially the combined fertilization of inorganic and organic fertilizers, increased the activities of urease, invertase, cellulase and FDA hydrolase in 200-2000 microm aggregates significantly. With the geometric mean (GMea) of the five test enzyme activities as the integrative index of soil enzyme activities, it was found that under fertilization, the GMea was significantly higher in 200-2000 microm aggregates, suggesting the high sensitivity of enzyme activities in larger particle-size aggregates to fertilization practices. Long-term inorganic plus organic fertilization could enhance the soil bio-function via the promotion of the formation of larger particle-size aggregates and the enzyme activities in these aggregates. PMID:20030140

Niu, Wen-jing; Li, Lian-qing; Pan, Gen-xing; Song, Xiang-yun; Li, Zhi-peng; Liu, Xiao-yu; Liu, Yong-zhuo

2009-09-01

149

The effect of pesticides on the denitrificatitn in paddy soil  

Microsoft Academic Search

The formation of nitrate in paddy fields is undesirable, because it will be lost through denitrification or leaching. Drained condition before flooding encourages the formation of nitrate, the loss of which after flooding is inevitable.

Shingo Mitsui; Iwao Watanabe; Makoto Honma; Seiichiro Honda

1964-01-01

150

Optimal waveband identification for estimation of leaf area index of paddy rice*  

PubMed Central

The objectives of the study were to select suitable wavebands for rice leaf area index (LAI) estimation using the data acquired over a whole growing season, and to test the efficiency of the selected wavebands by comparing them with feature positions of rice canopy spectra. In this study, the field experiment in 2002 growing season was conducted at the experimental farm of Zhejiang University, Hangzhou, China. Measurements of hyperspectral reflectance (350~2 500 nm) and corresponding LAI were made for a paddy rice canopy throughout the growing season. And three methods were employed to identify the optimal wavebands for paddy rice LAI estimation: correlation coefficient-based method, vegetation index-based method, and stepwise regression method. This research selected 15 wavebands in the region of 350~2 500 nm, which appeared to be the optimal wavebands for the paddy rice LAI estimation. Of the selected wavebands, the most frequently occurring wavebands were centered around 554, 675, 723, and 1 633 nm. They were followed by 444, 524, 576, 594, 804, 849, 974, 1 074, 1 219, 1 510, and 2 194 nm. Most of them made physical sense and had their counterparts in spectral known feature positions, which indicates the promising potential of the 15 selected wavebands for the retrieval of paddy rice LAI.

Wang, Fu-min; Huang, Jing-feng; Zhou, Qi-fa; Wang, Xiu-zhen

2008-01-01

151

Optimal waveband identification for estimation of leaf area index of paddy rice.  

PubMed

The objectives of the study were to select suitable wavebands for rice leaf area index (LAI) estimation using the data acquired over a whole growing season, and to test the efficiency of the selected wavebands by comparing them with feature positions of rice canopy spectra. In this study, the field experiment in 2002 growing season was conducted at the experimental farm of Zhejiang University, Hangzhou, China. Measurements of hyperspectral reflectance (350 approximately 2500 nm) and corresponding LAI were made for a paddy rice canopy throughout the growing season. And three methods were employed to identify the optimal wavebands for paddy rice LAI estimation: correlation coefficient-based method, vegetation index-based method, and stepwise regression method. This research selected 15 wavebands in the region of 350~2 500 nm, which appeared to be the optimal wavebands for the paddy rice LAI estimation. Of the selected wavebands, the most frequently occurring wavebands were centered around 554, 675, 723, and 1 633 nm. They were followed by 444, 524, 576, 594, 804, 849, 974, 1 074, 1 219, 1 510, and 2 194 nm. Most of them made physical sense and had their counterparts in spectral known feature positions, which indicates the promising potential of the 15 selected wavebands for the retrieval of paddy rice LAI. PMID:19067463

Wang, Fu-min; Huang, Jing-feng; Zhou, Qi-fa; Wang, Xiu-zhen

2008-12-01

152

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.

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

2010-01-01

153

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

PubMed

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

Hayashi, Kentaro; Nishimura, Seiichi; Yagi, Kazuyuki

2008-02-15

154

Suppressive effect of magnesium oxide materials on cadmium accumulation in winter wheat grain cultivated in a cadmium-contaminated paddy field under annual rice-wheat rotational cultivation.  

PubMed

The effectiveness of two kinds of magnesium oxide (MgO) materials, commercial MgO (2250 kg ha(-1)) and a material derived from MgO and magnesium silicate minerals named 'MgO-SH-A' (2250 and 4500 kg ha(-1)1), in suppression of uptake and accumulation of cadmium (Cd) into grain of winter wheat (Triticum aestivum L. cv. Ayahikari) was examined in a Cd-contaminated alluvial paddy field under annual rice-wheat rotational system. The MgO materials were mixed into the plough-layer soil only once prior to the preceding rice cultivation. Cadmium concentration in wheat grain produced from the non-amendment control exceeded the maximum limit of Cd in wheat grain adopted by FAO/WHO (0.2 mg kg(-1)). All of the treatments with the MgO materials significantly lowered plant available Cd fraction in the plough-layer soil. However, only the treatment with the commercial MgO at 2250 kg ha(-1) produced wheat grain whose Cd concentration was not only significantly lower than that from the control but also less than 0.2 mg kg(-1). It is suggested that the significant suppressive effect of the commercial MgO on Cd accumulation in wheat grain would be mainly attributed to its high soil neutralizing capacity as compared to that of MgO-SH-A. PMID:19304384

Kikuchi, Tetsuro; Okazaki, Masanori; Motobayashi, Takashi

2009-08-30

155

Delivery management water requirement for irrigation ditches associated with large-sized paddy plots in Korea  

Microsoft Academic Search

Delivery management water requirement (DMWR) is the use of bypass water in paddy field irrigation to help maintain desired water levels in irrigation canals and to distribute water to paddy plots in a uniform manner. Diverted irrigation water (DIW), DMWR, and the DMWR\\/DIW ratio were investigated for concrete lined irrigation ditches with large-sized paddy plots (100 m×100 m) during irrigation periods (May

Jin-Soo Kim; Seung-Young Oh; Kwang-Young Oh; Jae-Won Cho

2005-01-01

156

Strategies for Controlling the Apple Snail Pomacea canaliculata (Lamarck) (Gastropoda: Ampullariidae) in Japanese Direct-Sown Paddy Fields  

Microsoft Academic Search

The apple snail Pomacea canaliculata becomes a much more serious pest in direct-sown rice fields than in transplanted fields. In south Japan, it represents an important constraint on the implementation of direct seeding. Described here are possible measures to control the snails and suggestions for its management in Japanese direct-sown rice fields. Crop rotation with upland crops is a practical

Takashi WADA

2004-01-01

157

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-5(T), 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-5(T) 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-5(T) (?=?JCM 17479(T)?=?CGMCC 1.5168(T)). PMID:24535138

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

2014-05-01

158

Organophosphorus and carbamate pesticide residues detected in water samples collected from paddy and vegetable fields of the Savar and Dhamrai Upazilas in Bangladesh.  

PubMed

Several types of organophosphorous and carbamate pesticides have been used extensively by the farmers in Bangladesh during the last few decades. Twenty seven water samples collected from both paddy and vegetable fields in the Savar and Dhamrai Upazilas in Bangladesh were analyzed to determine the occurrence and distribution of organo-phosphorus (chlorpyrifos, malathion and diazinon) and carbamate (carbaryl and carbofuran) pesticide residues. A high performance liquid chromatograph instrument equipped with a photodiode array detector was used to determine the concentrations of these pesticide residues. Diazinon and carbofuran were detected in water samples collected from Savar Upazila at 0.9 ?g/L and 198.7 ?g/L, respectively. Malathion was also detected in a single water sample at 105.2 ?g/L from Dhamrai Upazila. Carbaryl was the most common pesticide detected in Dhamrai Upazila at 14.1 and 18.1 ?g/L, while another water sample from Dhamrai Upazila was contaminated with carbofuran at 105.2 ?g/L. Chlorpyrifos was not detected in any sample. Overall, the pesticide residues detected were well above the maximum acceptable levels of total and individual pesticide contamination, at 0.5 and 0.1 ?g/L, respectively, in water samples recommended by the European Economic Community (Directive 98/83/EC). The presence of these pesticide residues may be attributed by their intense use by the farmers living in these areas. Proper handling of these pesticides should be ensured to avoid direct or indirect exposure to these pesticides. PMID:23202689

Chowdhury, Md Alamgir Zaman; Banik, Sanjoy; Uddin, Borhan; Moniruzzaman, Mohammed; Karim, Nurul; Gan, Siew Hua

2012-09-01

159

Organophosphorus and Carbamate Pesticide Residues Detected in Water Samples Collected from Paddy and Vegetable Fields of the Savar and Dhamrai Upazilas in Bangladesh  

PubMed Central

Several types of organophosphorous and carbamate pesticides have been used extensively by the farmers in Bangladesh during the last few decades. Twenty seven water samples collected from both paddy and vegetable fields in the Savar and Dhamrai Upazilas in Bangladesh were analyzed to determine the occurrence and distribution of organo-phosphorus (chlorpyrifos, malathion and diazinon) and carbamate (carbaryl and carbofuran) pesticide residues. A high performance liquid chromatograph instrument equipped with a photodiode array detector was used to determine the concentrations of these pesticide residues. Diazinon and carbofuran were detected in water samples collected from Savar Upazila at 0.9 ?g/L and 198.7 ?g/L, respectively. Malathion was also detected in a single water sample at 105.2 ?g/L from Dhamrai Upazila. Carbaryl was the most common pesticide detected in Dhamrai Upazila at 14.1 and 18.1 ?g/L, while another water sample from Dhamrai Upazila was contaminated with carbofuran at 105.2 ?g/L. Chlorpyrifos was not detected in any sample. Overall, the pesticide residues detected were well above the maximum acceptable levels of total and individual pesticide contamination, at 0.5 and 0.1 ?g/L, respectively, in water samples recommended by the European Economic Community (Directive 98/83/EC). The presence of these pesticide residues may be attributed by their intense use by the farmers living in these areas. Proper handling of these pesticides should be ensured to avoid direct or indirect exposure to these pesticides.

Chowdhury, Md. Alamgir Zaman; Banik, Sanjoy; Uddin, Borhan; Moniruzzaman, Mohammed; Karim, Nurul; Gan, Siew Hua

2012-01-01

160

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

161

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

Microsoft Academic Search

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

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

2008-01-01

162

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

163

Microbial biomass in paddy soil  

Microsoft Academic Search

The authors investigated the role of microorganisms in paddy soil ecosystems and the influence of fertilizer and manure applications on the soil microbial biomass in paddy soils based on direct count using a fluorescence microscope. The results are summarized as follows.1) The number of bacteria in the plough layer was 6.6 × 10-7.6x 10\\/g oven dry soil in the Konosu

Akira Hasebe; Shinjiro Kanazawa; Yasuo Takai

1984-01-01

164

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

165

Analysis of percolation and seepage through paddy bunds  

Microsoft Academic Search

This study investigates percolation and seepage through the bunds of flat and terraced paddies. Field experiments were conducted in Hsin-Pu of Hsin-Chu County, Taiwan, to measure the soil water content of various types of bund. Measurements revealed that the soil was unsaturated along the sloped surface of the terrace. Experimental results also indicated that seepage face flow did not develop

Han-Chen Huang; Chen-Wuing Liu; Shih-Kai Chen; Jui-Sheng Chen

2003-01-01

166

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

167

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

168

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

169

HPLC method development and validation of chromafenozide in paddy.  

PubMed

A simple and efficient HPLC-UV method was developed and validated for determination of chromafenozide in paddy as there was no previous report on record in this regard. The residue analysis method of chromafenozide, its dissipation and final residue in paddy along with soil were also studied after field treatment. Residues of chromafenozide were extracted and purified from paddy and soil followed by liquid/liquid partitioning, chromatographic column and determination by HPLC equipped with PDA detector. The separation was performed on a Phenomenex Luna RP C(18) (250 × 4.6 mm i.d, 5 ?m particle size) column at room temperature. The mean accuracy of analytical method were 94.92 %, 95.38 %, 94.67 % and 96.90 % in straw, grain, soil and field water respectively. The precision (repeatability) was found in the range of 1.30 %-9.25 % for straw/grain, 1.27 %-11.19 % in soil; 1.0 %-9.25 % in field water. The precision (reproducibility) in straw/grain was ranging from 2.2 % to 12.1 %, in soil it from 2.0 % to 11.7 %. The minimum detectable concentration was 0.01 mg kg(-1). The degradation of chromafenozide formulation in rice, soil and water was determined and results showed that chromafenozide as wettable powder formulation degraded with the half-lives of about 4.4 and 2.9 days in paddy plant and soil respectively for double recommended dose. The results indicated that the developed method is easier and faster then could meet the requirements for determination of chromafenozide in paddy. PMID:23052574

Ditya, Papia; Das, S P; Bhattacharyya, Anjan

2012-12-01

170

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

171

Occurrence and partitioning of cadmium, arsenic and lead in mine impacted paddy rice: Hunan, China.  

PubMed

Paddy rice has been likened to nictiana sp in its ability to scavenge cadmium (Cd) from soil, whereas arsenic (As) accumulation is commonly an order of magnitude higher than in other cereal crops. In areas such as those found in parts of Hunan province in south central China, base-metal mining activities and rice farming coexist. Therefore there is a considerable likelihood that lead (Pb), in addition to Cd and As, will accumulate in rice grown in parts of this region above levels suitable for human consumption. To test this hypothesis, a widespread provincial survey of rice from mine spoilt paddies (n = 100), in addition to a follow-up market grain survey (n = 122) conducted in mine impacted areas was undertaken to determine the safety of local rice supply networks. Furthermore, a specific Cd, As, and Pb biogeochemical survey of paddy soil and rice was conducted within southern China, targeting sites impacted by mining of varying intensities to calibrate rice metal(loid) transfer models and transfer factors that can be used to predict tissue loading. Results revealed a number of highly significant correlations between shoot, husk, bran, and endosperm rice tissue fractions and that rice from mining areas was enriched in Cd, As, and Pb. Sixty-five, 50, and 34% of all the mine-impacted field rice was predicted to fail national food standards for Cd, As, and Pb, respectively. Although, not as elevated as the grains from the mine-impacted field survey, it was demonstrated that metal(loid) tainted rice was entering food supply chains intended for direct human consumption. PMID:19244995

Williams, Paul N; Lei, Ming; Sun, Guoxin; Huang, Qing; Lu, Ying; Deacon, Claire; Meharg, Andrew A; Zhu, Yong-Guan

2009-02-01

172

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

PubMed

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

Singh, Jay Shankar; Pandey, Vimal Chandra

2013-03-01

173

Depression of methane production potential in paddy soils by subsurface drainage systems  

Microsoft Academic Search

Subsurface drainage systems (pipe\\/tile drain systems) in paddy fields have been used in Japan since the 1960s for appropriate water management to encourage rice growing. Water management using the drainage systems probably accelerates the aerobic decomposition of organic matter in the paddy soils, and the management using the systems also accelerates leaching of water-soluble fractions in the soils. To evaluate

Yuichiro Furukawa; Yutaka Shiratori; Kazuyuki Inubushi

2008-01-01

174

Mass balance analysis in Korean paddy rice culture  

Microsoft Academic Search

A field experimental study was performed during the growing season of 2001 to evaluate water and nutrient balances in paddy\\u000a rice culture. Three plots of standard fertilization (SF), excessive fertilization (EF, 150% of SF), and reduced fertilization\\u000a (RF, 70% of SF) were used and the size of treatment plot was 3,000 m2, respectively. The hydrologic and water quality was field monitored

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

2003-01-01

175

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

176

Movement and retention of propanil N-(3,4-dichlorophenyl)propanamide in a paddy-riverine wetland system in Sri lanka  

Microsoft Academic Search

Propanil N-(3,4,-dichlorophenyl)propanamide is commonly used as a post-emergent herbicide in paddy rice cultivation in Sri Lanka. This study examined propanil concentrations in paddy soil and water, in water and substrate of adjacent wetlands receiving runoff from the paddy and in tissues of two wetland macrophytes common in those wetlands. Field sampling was carried out during the wet season of 1993–1994

Ajantha Perera; James R Burleigh; Craig B Davis

1999-01-01

177

Organic and inorganic carbon in paddy soil as evaluated by mid-infrared photoacoustic spectroscopy.  

PubMed

Paddy soils are classified as wetlands which play a vital role in climatic change and food production. Soil carbon (C), especially soil organic C (SOC), in paddy soils has been received considerable attention as of recent. However, considerably less attention has been given to soil inorganic carbon (SIC) in paddy soils and the relationship between SOC and SIC at interface between soil and the atmosphere. The objective of this research was to investigate the utility of applying Fourier transform mid-infrared photoacoustic spectroscopy (FTIR-PAS) to explore SOC and SIC present near the surface (0-10 µm) of paddy soils. The FTIR-PAS spectra revealed an unique absorption region in the wavenumber range of 1,350-1,500 cm(-1) that was dominated by C-O (carbonate) and C-H bending vibrations (organic materials), and these vibrations were used to represented SIC and SOC, respectively. A circular distribution between SIC and SOC on the surface of paddy soils was determined using principal component analysis (PCA), and the distribution showed no significant relationship with the age of paddy soil. However, SIC and SOC were negatively correlated, and higher SIC content was observed near the soil surface. This relationship suggests that SIC in soil surface plays important roles in the soil C dynamics. PMID:22912863

Changwen, Du; Jianmin, Zhou; Goyne, Keith W

2012-01-01

178

Clomazone dissipation, adsorption and translocation in four paddy topsoils.  

PubMed

Laboratory experiments about the dissipation, adsorption and translocation in four paddy topsoils were conducted in this paper. From the results it can be concluded as follows: the dissipation rate of clomazone differed greatly in different paddy soil derived from different parent materials. The half-lives for clomazone degradation in paddy soils ranged from 5.7 to 22.0 d. The order of clomazone dissipation rate was reddish yellow paddy soil > alluvial sandy paddy soil > yellow clayey paddy soil > purple sandy paddy soil. Clomazone sorption quantity was significantly correlated with organic carbon (R2 = 0.62) and clay content(R2 = 0.67) in the tested paddy soils. Positive correlation was found between apparent Kd value and cation exchange content(CEC). The consequences for the adsorption of different soils were purple sandy paddy soil > yellow clayey paddy soil > reddish yellow paddy soil > alluvial sandy paddy soil. Under the simulated rainfall of 200 mm through four different unsaturated soil lysimeters over 24 h, clomazone was readily to be leached into lower surface soil and there was about 2.6%--4.2% of applied clomazone leached out of 20 cm cultivated soil layer. Translocation experiments showed that the order of clomazone leaching ability was: alluvial sandy paddy soil > reddish yellow paddy soil > yellow clayey paddy soil > purple sandy paddy soil. Simple regression results manifested that factors like CEC, organic carbon, clay, and adsorption rate constant had been negatively correlated with the percentage of clomazone loss from soil lysimeters. PMID:15495980

Li, Lian-fang; Li, Guo-xue; Yang, Ren-bin; Guo, Zheng-yuan; Liao, Xiao-yong

2004-01-01

179

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

PubMed

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

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

2014-06-01

180

[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

181

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.

182

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

183

Organochlorine pesticides in soils under different land usage in the Taihu Lake region, China  

Microsoft Academic Search

A field study was conducted in the Taihu Lake region, China in 2004 to reveal the organochlorine pesticide concentrations in soils after the ban of these substances in the year 1983. Thirteen organochlorine pesticides (OCPs) were analyzed in soils from paddy field, tree land and fallow land. Total organochlorine pesticide residues were higher in agricultural soils than in uncultivated fallow

Fang WANG; Xin JIANG; Yong-rong BIAN; Fen-xia YAO; Hong-jian GAO; Gui-fen YU; Jean Charles MUNCH; Reiner SCHROLL

2007-01-01

184

Modeling complexity in simulating pesticide fate in a rice paddy.  

PubMed

Modeling approaches for pesticide regulation are required to provide generic and conservative evaluations on pesticide fate and exposure based on limited data. This study investigates the modeling approach for pesticide simulation in a rice paddy, by developing a component-based modeling system and characterizing the dependence of pesticide concentrations on individual fate processes. The developed system covers the modeling complexity from a "base model" which considers only the essential processes of water management, water-sediment exchange, and aquatic dissipation, to a "full model" for all commonly simulated processes. Model capability and performance were demonstrated by case studies with 5 pesticides in 13 rice fields of the California's Sacramento Valley. With registrant-submitted dissipation half-lives, the base model conservatively estimated dissolved pesticide concentrations within one order of magnitude of measured data. The full model simulations were calibrated to characterize the key model parameters and processes varying with chemical properties and field conditions. Metabolism in water was identified as an important process in predicting pesticide fate in all tested rice fields. Relative contributions of metabolism, hydrolysis, direct aquatic photolysis, and volatilization to the overall pesticide dissipation were significantly correlated to the model sensitivities to the corresponding physicochemical properties and half-lives. While modeling results were sensitive to metabolism half-lives in water for all fields, significances of metabolism in sediment and water-sediment exchange were only observed for pesticides with pre-flooding applications or with rapid dissipation in sediment. Results suggest that, in addition to the development of regional modeling scenarios for rice production, the registrant-submitted maximum values for the aquatic dissipation half-lives could be used for evaluating pesticide for regulatory purposes. PMID:23021519

Luo, Yuzhou; Spurlock, Frank; Gill, Sheryl; Goh, Kean S

2012-12-01

185

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

PubMed

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

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

2010-08-01

186

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.

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

2012-01-01

187

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

188

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

189

Carbon dioxide flux from rice paddy soils in central China: effects of intermittent flooding and draining cycles.  

PubMed

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

190

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.

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

2012-01-01

191

VISUALIZING WATER QUALITY TRENDS IN CHIANG MAI RICE PADDIES: POSSIBLE LINKS BETWEEN ENVIRONMENT AND HEALTH RISKS  

Microsoft Academic Search

Liver fluke (Opisthorchis viverrini) infection is a health concern throughout Thailand. Liver flukes use the Bithynia spp. snails, which inhabit rice paddy fields, as first intermediate hosts in their life cycle. Water quality and environmental factors could have an effect on snail distribution and their incidence of parasitic infection. Another area of health concern is the presence of Escherichia coli

Amy M. Krueger; Kim N. Irvine

192

Behavior of Cinosulfuron in Paddy Surface Waters, Sediments, and Ground Water  

Microsoft Academic Search

To better understand some of the field study results, cinosulfuron sie and Foy, 1986; Fredrickson and Shea, 1986; Vega et degradation was also evaluated in the laboratory in solutions buffered to different pH values. Two weeks after the treatment, the cinosulf- al., 1992; Dinelli et al., 1997; Gaynor et al., 1997). Studies uron concentration in the paddy water decreased by

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

2001-01-01

193

Control of arsenic toxicity in rice plants grown on an arsenic?polluted paddy soil  

Microsoft Academic Search

Paddy soils of over 500 hectares had been polluted by arsenic (As) from tailings at an abandoned lead?zinc mine at Shaoxing, Zhejiang, China. Several field experiments were conducted to establish measures for reducing As toxicity to rice plants. The results obtained were as follows. Fresh Chinese milkvetch (Astragalus sinicus L.) was not supposed to be used as green manure in

Zheng Miao Xie; Chang Yong Huang

1998-01-01

194

Methanogenic pathway and fraction of CH(4) oxidized in paddy fields: seasonal variation and effect of water management in winter fallow season.  

PubMed

A 2-year field and incubation experiment was conducted to investigate ?(13)C 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 (13)C. There was no obvious difference between the two in transport fractionation factor (?transport ) and ?(13)C-value of emitted CH4. CH4 emission was negatively related to its ?(13)C-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

195

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.

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

2013-01-01

196

Interfield and intrafield variability of methyl halide emissions from rice paddies  

NASA Astrophysics Data System (ADS)

Methyl halide gases are important sources of atmospheric inorganic halogen radicals. We measured methyl halide emissions from three rice fields over two full growing seasons. Rice paddy emissions of methyl chloride, methyl bromide and methyl iodide are insignificant until field flooding. Rice growth stage determines methyl bromide and methyl iodide emissions while methyl chloride emissions are comparable between planted and unplanted plots. Houston, Texas, and Maxwell, California, field integrated seasonal fluxes of methyl chloride, methyl bromide and methyl iodide are consistent (values range from 2.3 to 3.9, 0.8 to 1.1, and 28.1 to 62.0 mg m-2, respectively) despite differences in multiple field parameters. We also examined field emission variability using 12 chamber placements. Methyl bromide and methyl iodide emissions within homogenous rice paddies require at least three replicates to determine field mean fluxes within 20%, and for methyl chloride emissions, over 10 replications per field are necessary.

Redeker, K. R.; Andrews, J.; Fisher, F.; Sass, R.; Cicerone, R. J.

2002-12-01

197

Central Region Library Field Records Collection  

USGS Multimedia Gallery

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

2009-04-09

198

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

199

Restoring the Health of Paddy Soil by Using Straw Compost and Biofertilizers to Increase Fertilizer Efficiency and Rice Production with Sobari (System of Organic Based Aerobic Rice Intensification) Technology  

Microsoft Academic Search

Current conditions indicate that about 70% of paddy fields in Indonesia has been experiencing severe degradation of land and can be categorized as an illness (sick soils), therefore, efforts to restore health and increase the productivity of paddy soil in a sustainable manner can be done by integrating fertilizer-based integrated management organic and biological fertilizers (biofertilizers) with SOBARI (system of

Tien Turmuktini; Endang Kantikowati; Betty Natalie; Mieke Setiawati; Yuyun Yuwariah; Benny Joy

2012-01-01

200

Pedo-transfer function for saturated hydraulic conductivity of lowland paddy soils  

Microsoft Academic Search

In paddy field, soil saturated hydraulic conductivity (K\\u000a s) plays as an important component in the calculation of irrigation requirement of the water balance equation and also for\\u000a irrigation efficiency. Several laboratory and field methods can be used to determine K\\u000a s. Laboratory and field determinations are usually time consuming, expensive and labour intensive. Pedo-transfer functions\\u000a (PTF) serve to translate

W. Aimrun; M. S. M. Amin

2009-01-01

201

Atmospheric methane observed from space over the Asian monsoon: implications for emission from Asian rice paddies  

NASA Astrophysics Data System (ADS)

More than 40% of anthropogenic emissions of methane, the second most important greenhouse gas, is estimated to be from agricultural sources, including rice cultivation. Unfortunately, the strength of individual sources of methane remains uncertain, despite the importance of its effect in global warming. Here we focus on the Asian monsoon region to improve our understanding of methane emission from rice paddy fields. This region contains about 90% of the world’s rice fields. We analyze the temporal and spatial distribution of atmospheric methane concentrations observed from space and compare it with ground-based measurements and bottom-up emission inventory data coupled with rice field maps. Recently, Frankenberg et al. [2008] derived an updated version of methane concentration from the Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY: SCIA hereafter) instrument onboard ENVISAT. This showed a clear signature of methane enhancement over the Asian monsoon. As SCIA retrievals include all involve column densities, we carefully examined potential biases and variability due to the gradient of methane concentration over source regions by comparing these data with ground-based measurements at 53 stations of the WDCGG network. After evaluating the bias and variability of methane concentration over the source regions, we examined selected areas where rice paddies were highly concentrated, and the methane emission inventories were estimated to be large. The sampled areas were North and South India, Bangladesh, Myanmar, Thailand, South China, and the Sichuan Basin. All of these are known to be major rice cultivation areas. The time series of monthly mean SCIA retrievals were compared with the emission inventory data for rice cultivation archived in the GISS dataset and Yan et al. [2009], as well as with precipitation data (Huffman et al., 1997). The phase of seasonal variation of SCIA retrievals corresponded closely to those of emission inventories. High methane concentrations were observed in the later period of the rainy season for each area. The amplitude of seasonal variation was large compared with the possible bias over the source regions, demonstrating the reliability of the analysis. We are planning to extend the analysis to the methane data observed by the Thermal And Near infrared Sensor for carbon Observations Fourier Transform Spectrometer (TANSO-FTS) onboard the Greenhouse gases Observing SATellite (GOSAT). GOSAT was launched successfully on January 23, 2009, and has been operating continuously since then. The TANSO-FTS will provide important information on methane emission from rice paddies with good spatial resolution (10 km in diameter). Preliminary results from this instrument will also be presented. References: Frankenberg, et al. (2008), Geophys. Res. Lett., 35, doi:10.1029/2008GL034300. Huffman et al. (1997), Bull. Am. Meteorol. Soc. Vol. 78, 5-20. Yan et al., (2009), Global Biogeochem. Cycles, 23, GB2002, doi:10.1029 /2008GB003299.

Hayashida, S.; Yoshizaki, S.; Frankenberg, C.; Yan, X.

2010-12-01

202

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.

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

2014-01-01

203

Phylogenetic distribution of the capsid assembly protein gene (g20) of cyanophages in paddy floodwaters in Northeast China.  

PubMed

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

204

DRYING KINECTICS OF PADDY USING THERMOGRAVIMETRIC ANALYSIS  

Microsoft Academic Search

The thermogravimetry (TG) and derivative thermogravimetry (DTG) were used to study the drying kinetics of the paddy. TG experiments were carried out at different heating rates (1, 3, 10 K\\/min) to study the drying kinetics. The Activation energy and pre exponential factors from the Arrhenious equation were calculated for the drying curves using ASTM and OZAWA-FLYNN WALL analysis. The results

M. Madhava; P. Srinivasa Rao; T. K. Goswami

2001-01-01

205

E and F region electric fields over dip equator  

NASA Astrophysics Data System (ADS)

The horizontal east-west drift velocity of ionization irregularities in E region, and the vertical drift velocity of electrons in F region over Jicamarca (dip latitude approximately 1 deg N) are used to estimate the average diurnal variation of the east-west components of the electric fields in these two regions. The F region field is estimated from the vertical drift velocity by using the relationship derived earlier by Woodman (1970). The E region field is estimated from the horizontal east-west drift velocity by using a relationship derived by using realistic electrojet and conductivity models. The E region electric field thus obtained is found to be weaker at least by a factor of three than that estimated by Balsley and Woodman (1971). A comparative study shows that the east-west electric field in the F region is, most of the time, stronger than that in the E region, and also that the ratio of the E region field to the F region field systematically increases from forenoon to afternoon hours, and from pre-midnight to post-midnight hours.

Prakash, S.; Muralikrishna, P.

1981-04-01

206

Arsenic release from paddy soils during monsoon flooding  

NASA Astrophysics Data System (ADS)

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

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

2010-01-01

207

Simulating concentration of bensulphuron-methyl in a drainage canal of a paddy block using a rice pesticide model.  

PubMed

A pesticide fate and transport model (PCPF-B) was developed to predict the runoff of pesticides from paddy plots to a drainage canal in a paddy block based on the plot scale model (PCPF-1). The block-scale model now comprises three modules: (1) a module for pesticide application, (2) a module for pesticide behaviour in paddy fields, and (3) a module for pesticide concentration in the drainage canal. The PCPF-B model was first evaluated using published data in a single plot and then was applied to predict the concentration of bensulphuron-methyl in one paddy block in the Sakura river basin, Ibaraki, Japan, where a detailed field survey was conducted. The PCPF-B model simulated well the concentration of bensulphuron-methyl in individual paddy plots. It also reflected the runoff pattern of bensulphuron-methyl at the block outlet, although overestimation of bensulphuron-methyl concentrations occurred due to uncertainty in water balance estimation. A sensitivity analysis showed that the soil adsorption coefficient of the herbicide had the greatest influence on the concentrations and cumulative loss of bensulphuron-methyl to the drainage canal. PMID:21473270

Phong, Thai Khanh; Hiramatsu, Kazuaki; Watanabe, Hirozumi

2011-01-01

208

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.

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

2014-01-01

209

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

PubMed

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

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

2014-08-01

210

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...

211

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

212

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

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

213

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

NASA Astrophysics Data System (ADS)

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

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

2009-12-01

214

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

215

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

Microsoft Academic Search

Paddy soil samples taken from different sites in an old primitive electronic-waste (e-waste) processing region were examined for eco-toxicity and metal contamination. Using the environmental quality standard for soils (China, Grade II) as reference, soil samples of two sites were weakly contaminated with trace metal, but site G was heavily contaminated with Cd (6.37mgkg?1), and weakly contaminated with Cu (256.36mgkg?1)

Zhang Jun-hui; Min Hang

2009-01-01

216

Large Scale Photospheric Magnetic Field the Diffusion of Active Region Fields.  

National Technical Information Service (NTIS)

The large-scale phototospheric magnetic field was computed by allowing observed active region fields to diffuse and to be sheared by differential rotation in accordance with the Leighton (1969) magneto-kinematic model of the solar cycle. The differential ...

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

1972-01-01

217

Relation between the active region magnetic field and solar flares  

NASA Astrophysics Data System (ADS)

A weak active region (NOAA 11158) appeared on the solar disk near the eastern limb. This region increased rapidly and, having reached the magnetic flux higher than 1022 Mx, produced an X-class flare. Only weak field variations at individual points were observed during the flare. An analysis of data with a resolution of 45 s did not indicate any characteristic features in the photospheric field dynamics during the flare. When the flux became higher than 3 × 1022 Mx, active region NOAA 10720 produced six X-class flares. The field remained quiet during these flares. An increase in the magnetic flux above ˜1022 Mx is a necessary, but not sufficient, condition for the appearance of powerful flares. Simple active regions do not produce flares. A flare originates only when the field distribution in an active region is complex and lines of polarity inversion have a complex shape. Singular lines of the magnetic field can exist only above such active regions. The current sheets, in the magnetic field of which the solar flare energy is accumulated, originate in the vicinity of these lines.

Podgorny, A. I.; Podgorny, I. M.; Meshalkina, N. S.

2013-11-01

218

Regions associated with electron physics in asymmetric magnetic field reconnection  

Microsoft Academic Search

Spatial relationships between regions containing signatures of electron physics in asymmetric reconnection with a guide field are examined using simulations and space observations that are in excellent agreement. These electron physics regions do not completely overlap, are not confined to sizes ~electron skin depth, and do not surround the X-line. The electron ideal Ohm's law, E+UexB = 0, is violated

F. S. Mozer; P. L. Pritchett

2009-01-01

219

Regions associated with electron physics in asymmetric magnetic field reconnection  

Microsoft Academic Search

Spatial relationships between regions containing signatures of electron physics in asymmetric reconnection with a guide field are examined using simulations and space observations that are in excellent agreement. These electron physics regions do not completely overlap, are not confined to sizes ?electron skin depth, and do not surround the X-line. The electron ideal Ohm's law, E + Ue × B

F. S. Mozer; P. L. Pritchett

2009-01-01

220

Kinetic behaviour of tritium water in the simulated paddy.  

National Technical Information Service (NTIS)

The dynamic process of movement and transportation for tritium water in the simulated paddy have been investigated. The results showed that after the paddy water was filled the tritium water not only was transferred to the components of the system but als...

S. Wang C. Chen Y. Zhang Z. Sun D. Huang

1993-01-01

221

Growth and nitrogen uptake of padd.y rice as influenced by fermented manure liquid and squeezed manure liquid  

Microsoft Academic Search

A field experiment was conducted to estimate the effects of fermented manure liquid (FL) and squeezed manure liquid (SL) on the growth and nitrogen (N) uptake of paddy rice and to determine the threshold dose for application to irrigated rice. The rice plants were grown in plots without fertilizer application (NF) or with chemical fertilizer application (60, 60, 60 kg

Kun-Zhi Li; Tatsuya Inamura; Mikio Umeda

2003-01-01

222

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

Microsoft Academic Search

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

Hiroshi Yokota; Nobuhiro Kaneko

2002-01-01

223

Characteristics of indicator microorganisms in paddy rice plots after reclaimed water irrigation.  

PubMed

A study was performed to examine the effects of reclaimed-water irrigation on microorganism concentration in the ponded-water of paddy rice plots. Several treatments were used and each one was triplicated to evaluate the change of indicator microorganisms (total coliforms (TC), faecal coliforms (FC), and E. coli) concentrations in 2003 and 2004 growing seasons. Their concentrations increased significantly after irrigation, but decreased by approximately 45% in 24 h. It implies that agricultural activities such as ploughing and fertilising need to be practiced one or two days after irrigation, considering health risks. Treatments with UV-disinfected water irrigation, demonstrated significantly lower concentrations than others, including control plots where natural water was irrigated. The monitoring result from actual paddy rice fields and experimental paddy plots showed that concentrations of indicator microorganisms ranged from 10(2) to 10(5) MPN/100 mL. The field scale water reuse research project is in progress and national guidelines for reclaimed-water irrigation are under preparation in Korea. A comprehensive assessment of existing agricultural practices and a thorough monitoring in the fields as well as treatment plots are recommended to make national guidelines more representative. PMID:17305149

Jung, K W; Yoon, C G; Jang, J H; Jeon, J H

2007-01-01

224

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

225

Critical region analysis of scalar fields in arbitrary dimensions  

NASA Astrophysics Data System (ADS)

The exploration of multidimensional scalar fields is commonly based on the knowledge of the topology of their isosurfaces. The latter is established through the analysis of critical regions of the studied fields. A new method, based on homology theory, for the detection and classification of critical regions in multidimensional scalar fields is proposed in this paper. The use of computational homology provides an efficient and successful algorithm that works in all dimensions and allows to generalize visual classification techniques based solely on the notion of connectedness which appears insufficient in higher dimensions. We present the algorithm, discuss details of its implementation, and illustrate it by experimentations in two, three, and four dimensional spaces.

Allili, Madjid; Ethier, Marc; Kaczynski, Tomasz

2010-01-01

226

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.

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

2011-01-01

227

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

228

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

229

VECTOR MAGNETIC FIELDS OF A SOLAR POLAR REGION  

SciTech Connect

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

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

2011-05-01

230

Zoning of the Circumpolar Region after the potential fields character  

NASA Astrophysics Data System (ADS)

Basic digital maps of the magnetic anomaly and gravity fields of Arctic, compiled as a part of the international project [Gaina et al., 2011], were updated in the Russian part of the region in 2010-2011. Zoning of anomalous potential fields in Arctic using updated Russian digital mapping projects was made. Main tasks are: 1 - substantiation of the types and boundaries of geological structures in the Circumpolar Region after the character of magnetic anomaly and gravity fields; 2 - analysis and comparison of the magnetic anomaly and gravity fields within the Arctic Basin and its continental margins in order to reveal similarities in the character of potential fields and tectonic structures. Analysis was performed visually using GIS ESRI ArcMap v.9.3. Previously, all digital materials on anomalous magnetic field and anomalous gravity field were compiled into a single project jointly with auxiliary materials: geological map, map of surface topography and ocean depths, map of sedimentary cover, map of crustal thickness, and fragments of different-scale tectonic maps available for the Circumpolar Region. When delineating areas, the following ranking system (in decreasing order) was accepted: anomalous province, anomalous area, and anomalous district. Anomalous provinces represent the largest areas of anomalous fields, characterized by a common morphostructural plan. Typically, they correspond to global objects, such as continents, oceans or their considerable parts. Anomalous areas within the provinces correspond to major territories with their own specific features (first of all, they differ from each other in amplitude-frequency characteristics and in anomaly configuration), but at the same time preserving main features within the distinguished area. In the tectonic sense, they correspond to regional geological elements such as platforms, oceanic basins, large folded areas, etc. Anomalous districts within anomalous areas correspond to groups of anomalies presumably of the same origin, and therefore have similar characteristics. In the tectonic sense, they correspond to geological objects such as shields, plates, individual fold belts, sedimentary basins, etc. The following features are taken as a basis for anomalous fields typification: field morphostructure, intensity, and anomaly sign. Digital coding of six types of anomalous fields morphostructures and six types of combinations of intensity and anomaly sign is proposed. As a result of this work, an integrated scheme of potential fields zoning in the Circumpolar Arctic linked with the tectonic zoning scheme was created.

Litvinova, T.; Kashubin, S.; Petrov, O.

2012-04-01

231

Regional methods for trend detection: Assessing field significance and regional consistency  

NASA Astrophysics Data System (ADS)

This paper describes regional methods for assessing field significance and regional consistency for trend detection in hydrological extremes. Four procedures for assessing field significance are compared on the basis of Monte Carlo simulations. Then three regional tests, based on a regional variable, on the regional average Mann-Kendall test, and a new semiparametric approach, are tested. The latter was found to be the most adequate to detect consistent changes within homogeneous hydro-climatic regions. Finally, these procedures are applied to France, using daily discharge data arising from 195 gauging stations. No generalized change was found at the national scale on the basis of the field significance assessment of at-site results. Hydro-climatic regions were then defined, and the semiparametric procedure applied. Most of the regions showed no consistent change, but three exceptions were found: in the northeast flood peaks were found to increase, in the Pyrenees high and low flows showed decreasing trends, and in the Alps, earlier snowmelt-related floods were detected, along with less severe drought and increasing runoff due to glacier melting. The trend affecting floods in the northeast was compared to changes in rainfall, using rainfall-runoff simulation. The results showed flood trends consistent with the observed rainfall.

Renard, B.; Lang, M.; Bois, P.; Dupeyrat, A.; Mestre, O.; Niel, H.; Sauquet, E.; Prudhomme, C.; Parey, S.; Paquet, E.; Neppel, L.; Gailhard, J.

2008-08-01

232

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

233

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.

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

2014-01-01

234

Effects of four rice paddy herbicides on algal cell viability and the relationship with population recovery.  

PubMed

Paddy herbicides are a high-risk concern for aquatic plants, including algae, because they easily flow out from paddy fields into rivers, with toxic effects. The effect on algal population dynamics, including population recovery after timed exposure, must be assessed. Therefore, we demonstrated concentration-response relationships of four paddy herbicides for algal growth inhibition and mortality, and the relationship between the effect on algal cell viability and population recovery following exposure. We used SYTOX Green dye assay and flow cytometry to assess cell viability of the alga Pseudokirchneriella subcapitata. Live cells could be clearly distinguished from dead cells during herbicide exposure. Our results showed that pretilachlor and quinoclamine had both algicidal and algistatic effects, whereas bensulfuron-methyl only had an algistatic effect, and pentoxazone only had an algicidal effect. Then, a population recovery test following a 72-h exposure was conducted. The algal population recovered in all tests, but the periods required for recovery differed among exposure concentrations and herbicides. The periods required for recovery were inconsistent with the dead cell ratio at the beginning of the recovery test; that is, population recovery could not be described only by cell viability. Consequently, the temporal effect of herbicides and subsequent recovery of the algal population could be described not only by the toxicity characteristics but also by toxicokinetics, such as rate of uptake, transport to the target site, and elimination of the substance from algal cells. PMID:21590715

Nagai, Takashi; Ishihara, Satoru; Yokoyama, Atsushi; Iwafune, Takashi

2011-08-01

235

Assessment of pesticide residues in freshwater areas affected by rice paddy effluents in Southern Japan.  

PubMed

Pesticide residues in five freshwater areas that are directly affected by rice paddy effluents in southern Japan were measured to determine their maximum concentrations and temporal variations. Water samples were collected every week during the 2005 rice planting season in Kagoshima Prefecture and stations were established in Amori River, Sudo River, Nagaida River (that drains into the bigger Kotsuki River), rice paddy drainage canal, and wastewater reservoir (that collects effluents from rice paddy fields). Of the 14 target pesticides examined, a total of 11 were detected in all stations. Mefenacet, fenobucarb, and flutolanil were the three pesticides with the highest maximum concentrations and were also detected frequently. Analysis of temporal variations of pesticides showed that herbicides had relatively higher concentrations in the earlier stages of the rice planting season, while insecticides and fungicides had relatively higher concentrations at the later stages. There was no significant difference among stations with regards to the temporal patterns of the top three pesticides. The calculated toxic units were less than 1 in all stations, implying low or negligible environmental risk of pesticides detected to freshwater organisms. PMID:19089593

Añasco, Nathaniel; Uno, Seiichi; Koyama, Jiro; Matsuoka, Tatsuro; Kuwahara, Naoya

2010-01-01

236

Responses of the bacterial community to chronic gamma radiation in a rice paddy ecosystem.  

PubMed

Purpose: Public concern about radiation protection of the environment and non-human species is increasing. The potential impact of chronic gamma radiation on the bacterial community in a rice paddy ecosystem was investigated. Materials and methods: Paddy field microcosm samples were continuously exposed at a dose rate of 1 Gy day(-1) for five days after which the bacterial community structures in them were compared with those of unirradiated control samples by denaturing gradient gel electrophoresis (DGGE) of the 16S ribosomal ribonucleic acid (rRNA) gene. Dissolved ions in ponding waters of the microcosm samples were determined by ion chromatography. Results: The DGGE band profiles were clearly different between the control and exposure samples. Sequencing of selected DGGE bands revealed that a specific species of the genus Clostridium and of the genus Massilia were grown under radiation exposure. Additionally, the concentrations of sulphate ion in the ponding water of the microcosm samples increased under radiation exposure. Concentrations of Na(+), Ca(2+), and F(-) inversely decreased. Conclusions: The data presented suggest that chronic gamma radiation affects the bacterial community structure and material cycles in the rice paddy ecosystem. PMID:21284570

Ishii, Nobuyoshi; Fuma, Shoichi; Tagami, Keiko; Honma-Takeda, Shino; Shikano, Shuichi

2011-07-01

237

The influence of radar look direction on precise identification of rice-planted fields using RADARSAT data  

NASA Astrophysics Data System (ADS)

Satellite radar sensors like RADARSAT have capability to acquire data regardless of cloud cover The capability can estimate rice-planted fields independent of weather conditions It is important for estimation of the rice-planted fields to discriminate the low backscatter area as inundated paddy fields on the radar image However there is a possibility that the backscattering from an inundated paddy field increases due to corner reflection between the water surface and a ridge of paddy It causes an error in estimation of rice-planted fields By assuming the shape of a paddy field to be a rectangle this paper examined the influence of the radar look direction for identifying an inundated paddy field using RADARSAT image The radar look direction is almost uniform in a same RADARSAT image However the influence of the radar look direction is depended on the longitudinal direction of paddy field in inundated paddy fields The radar look direction for each paddy field was calculated by the farmland outline vector data which expressed numerically the shape and the spatial location of paddy field in this paper The farmland outline vector data was created by delineating the boundary of a paddy field in the test site using QuickBird image Paddy fields in the test site were classified to several longitudinal directions First it was determined by visual interpretation of QuickBird image whether a paddy field was rice-planted or not Then the averaged RADASAT backscatter coefficient for each paddy field was calculated using the farmland outline vector data Finally in

Takahashi, K.; Rikimaru, A.

238

ICON rice seed treatment toxicity to crayfish (Procambarus clarkii) in experimental rice paddies.  

PubMed

Outdoor pools (2.3 x 2.3 m) were used to simulate typical rice agricultural practices in Louisiana, USA, to evaluate the toxicity of ICON (active ingredient [a.i.] fipronil) and its degradates to crayfish (Procambarus clarkii). Six paddies were planted with seed treated with ICON 6.2 FS at an exaggerated application rate of 0.05 kg a.i./ha (recommended rate, 0.042 kg a.i./ha), simulating three rice-planting scenarios. Two reference paddies were planted with untreated seed. Crayfish were exposed to tail water within 24 to 48 h after seeding, simulating standard Louisiana agricultural and water management practices. At 50 d after planting, a separate group of crayfish was caged in situ for 14 d to evaluate toxicity. An additional 50 crayfish were added to two paddies approximately 100 d after rice planting and held for 29 weeks to evaluate bioaccumulation. Residues of fipronil and its degradates in water and soil were similar to residue concentrations measured from rice fields in Louisiana. Tail water from the treated paddies was not toxic to crayfish. The fipronil 96-h median lethal concentration (LC50) for adult crayfish was 180 microg/L, which would provide at least a sixfold safety factor between the maximum fipronil concentration in tail water and the crayfish LC50. In situ exposures of crayfish also were not toxic. Concentrations of fipronil and its degradates after 29 weeks of exposure were less than 5 microg/kg in crayfish tail muscle tissue. These results demonstrate that label instructions adequately protect crayfish in a rice-crayfish cropping scenario when ICON is applied at maximum application rates as a seed treatment. PMID:12503761

Biever, Ronald C; Hoberg, James R; Jacobson, Brian; Dionne, Emily; Sulaiman, Mohammed; McCahon, Peter

2003-01-01

239

REGIONAL AIR POLLUTION STUDY: LAMBERT FIELD GRAPHICAL WEATHER SUMMARY  

EPA Science Inventory

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

240

Mapping of electric field structures from the equatorial F region to the underlying E region  

NASA Technical Reports Server (NTRS)

The theories of electrostatic fields in the equatorial ionosphere attributed to Farley (1960) and Spreiter and Briggs (1961) are reviewed, and a hybrid of these theories is applied to investigate how spread F irrregularities map down to the underlying E region. It is found that structures larger than 1 km map easily through the E region, while smaller structures do not. This implies that in general, subkilometer F region irregularities cannot directly generate image striations in the underlying E region, a result which affects previous investigations of the role of images in equatorial spread F.

Labelle, J.

1985-01-01

241

ABRUPT LONGITUDINAL MAGNETIC FIELD CHANGES IN FLARING ACTIVE REGIONS  

SciTech Connect

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

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

2010-12-01

242

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

243

X-ray Point Sources in Galactic Center Region Fields  

NASA Astrophysics Data System (ADS)

We report the recent progress of the Chandra Multiwavelength Plane (ChaMPlane) survey in the Galactic Center region fields. These fields include deep Chandra observations of three low extinction windows near the Galactic Center - Baade's window, Stanek window, and Limiting window (100 ksec each, see van den Berg et al. for a detailed description of these three fields) and the Chandra archival data of Sgr A* (750 ksec), Sgr B2 field (100 ksec) and the shallow survey (2x12 ksec) of the Galactic Center strip (Wang et al 2002, Nature, 415, 148). We classify the spectral types of X-ray sources by quantile analysis, and we explore the source population using logN-logS and spatial distributions based on their spectral type. This project is supported by Chandra grant GO5-6091X.

Hong, J.; Grindlay, J.; van den Berg, M.; Laycock, S.; Koenig, X.; Zhao, P.; Schlegel, E.

2005-12-01

244

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

245

Chromospheric Magnetic Field of Exploding Solar Active Regions  

NASA Astrophysics Data System (ADS)

How changes in the three-dimensional magnetic field of solar active region are related to Coronal Mass Ejections (CME) is an important question for contemporary solar physics. Complex active regions are the predominant source of powerful high-speed CMEs, which can result in strong geomagnetic storms. In this paper we present the properties of chromospheric magnetic field of active regions that produced solar flares and CMEs using observations of the Synoptic Optical Long-term Investigations of the Sun (SOLIS) facility operated by the National Solar Observatory. Currently, the SOLIS Vector Spectromagnetograph (VSM) is the only instrument that is capable of obtaining full Stokes profiles in both the photospheric Fe I ?630.2 nm and chromospheric Ca II ?854.2 nm lines on a daily basis. VSM also has the capability of making rapid scans covering an area sufficiently large to contain an active region. We shall present the Stokes profile characteristics of photospheric and chromospheric lines of few CME source regions.

Choudhary, Debi P.

2013-07-01

246

The Magnetic Vector Structure of an Active Region Plage Field  

NASA Astrophysics Data System (ADS)

We present scans of the active region plage associated with NOAA 10953, recorded with the Tenerife Infrared Polarimeter 2 (TIP-2) mounted behind the German Vacuum Tower Telescope (VTT) on Tenerife and the SOT-SP instrument on-board the HINODE spacecraft. TIP-2 recorded the full Stokes vector close to the diffraction limit of the telescope over a 20 angstroem wavelength range containing six magnetically sensitive FeI lines in the infrared including the g=3 line FeI 15648.5. With these lines we use the advantage that the Zeeman splitting dominates over the Doppler broadening for kG fields. The iron lines used by HINODE are FeI 6301.501and FeI 6302.494. We analyzed the data by applying a Milne-Eddington type inversion to it. In the context of a two-component model we found a bimodal distribution of field strengths, strong fields whose field strength distribution peaks at 1400 [G] and a weak field distribution, which may be associated with quiet sun regions bordering on the plage.

Meling, M. H. M.; Lagg, A.; Solanki, S. K.

2008-09-01

247

An Extensive Survey of Gaseous Emissions from Rice Paddy Agriculture  

NASA Astrophysics Data System (ADS)

Rice agriculture currently occupies nearly 1% of the available land surface area of the globe. Increased population over the next few decades will drive the need for further expansion of global agriculture. Understanding atmospheric chemistry and climate change requires us to study small changes in relatively poorly quantified gases. In order to fully describe the effects of changing land use it is imperative to understand the relative shift in emissions post and prior to agricultural use for all relevant compounds. During the 2000 growing season we sampled over a commercial rice field in Houston TX. Our study surveyed over 45 separate compounds (up to C7), covering alkanes, alkenes, aromatics, isoprene, DMS, halocarbons, CFCs, and alkyl nitrates. We compare and include results from previous studies to complement our emissions. We include emissions from control plots (unplanted with rice, but flooded) that allows us to determine whether emissions are rice-plant dependent or are inherent in the rice paddy environment itself. Biomass burning estimates are calculated for fields where residue burning is practiced.

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

2002-05-01

248

Observed pre flare characteristics of active region magnetic fields  

NASA Astrophysics Data System (ADS)

I will present data and results on observations of flare-related magnetic conditions in solar active regions The following topics will be discussed Static non-potential magnetic characteristics before flares such as magnetic gradients shear and twist 2 spatio-temporal dynamics of the photospheric magnetic flux such as flows and flux emergence 3 evolution of magnetic structures leading to and following flares A special attention will be payed to new approaches to quantify complexity of the photospheric magnetic fields in terms of intermittency magnetic power spectra and probability distribution functions Discovered correlation between the parameters and the flare activity in active regions provides new insights into understanding of the nature of magnetic coupling between the sub-photospheric layers where the magnetic field is generated and the corona where eruptions occur

Yurchyshyn, V.

249

Chiral Effective Field Theory in the ?-RESONANCE Region  

NASA Astrophysics Data System (ADS)

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

Pascalutsa, Vladimir

2007-10-01

250

Satellite and Field Derived Aboveground Carbon Stock in Tropical Regions  

NASA Astrophysics Data System (ADS)

Forests store the vast majority of terrestrial carbon, but variability in space and time is substantial. Accurate and repeatable estimates of aboveground carbon stored in tropical vegetation are important for compensation mechanism for Reducing Emissions from Deforestation and Degradation (REDD). Remotely sensed data have been used extensively to estimate land cover and land cover change and in an effort to overcome the limitations posed by systematic field surveys, remote sensing has been used as a basis for inferring forest structure and aboveground biomass over large areas. However, direct biomass mapping in tropical regions has proven to be difficult. Here we present a multi stage approach that provides spatio-temporally consistent estimates of aboveground carbon across the tropical forest region. The method leverages a combination of field and space borne LiDAR that provides accurate information at the plot level, and remote sensing data that are continuous in space over large areas. We collected co-located field measurements based on a specifically designed protocol that facilitate the integration of field data with remote sensing and used these field measurements to calibrate waveform metrics derived from the GLAS instrument on board the Ice, Cloud and Elevation Satellite (ICESAT). A least square model provided estimates of carbon at any GLAS location with an RMS Error of 24.3 Mg C/ha, in essence providing a consistent sample over the entire tropical forest region. A cloud free mosaic of reflectance data recorded from the Moderate resolution Imaging Spectroradiometer (MODIS) sensors onboard NASA’s TERRA and AQUA satellites was used to extend the large sample of GLAS-derived biomass values to map form, i.e. continuous “wall to wall” estimates with a spatial resolution of 500 meters. These data sets can be used as a carbon baseline and, when combined with existing land cover change maps, provide estimates of carbon dioxide emissions associated with deforestation and forest degradation.

Baccini, A.; Goetz, S. J.; Walker, W. S.; Laporte, N. T.; Sun, M.; Sulla-Menashe, D. J.; Friedl, M. A.; Beck, P. S.; Kellndorfer, J. M.; Houghton, R. A.

2010-12-01

251

Plant available silicon in South-east Asian rice paddy soils - relevance of agricultural practice and of abiotic factors  

NASA Astrophysics Data System (ADS)

Background Silicon (Si) plays a crucial role in rice production. Si content of rice plants exceeds the content of other major nutrients such as nitrogen, phosphorous or potassium. Recent studies showed that in some environments external supply of Si can enhance the growth of rice plants. Rice plants express specific Si transporters to absorb Si from soil solutions in form of silicic acid, which precipitates in tissue cells forming amorphous silica bodies, called phytoliths. The phytoliths are returned to soils with plant residues. They might be a main source of plant available silicic acid in soils. Aims In this study we assess the effects of rice paddy cultivation on the stocks of `reactive` Si fractions in mineral topsoils of rice paddy fields in contrasting landscapes. The `reactive` Si fractions are presumed to determine the release of plant-available silicic acid in soils. We consider the relevance of abiotic factors (mineral assemblage; soil weathering status) and agricultural practice for these fractions. Agricultural practices, which were assumed to affect the stocks of `reactive` Si were (i) the usage of different rice varieties (which might differ in Si demand), (ii) straw residue management (i.e., whether straw residues are returned to the fields or removed and used e.g. as fodder), and (iii) yield level and number of crops per year. Material and methods Soils (top horizon of about 0-20 cm depth) were sampled from rice paddy fields in 2 mountainous and 5 lowland landscapes of contrasting geologic conditions in Vietnam and the Philippines. Ten paddy fields were sampled per landscape. The rice paddy management within landscapes differed when different farmers and/or communities managed the fields. We analysed the following fractions of `reactive` Si in the soils: acetate-extractable Si (dissolved and easily exchangeable Si), phosphate-extractable Si (adsorbed Si), oxalate extractable Si (Si associated with poorly-ordered sesquioxides), NaOH extractable Si (amorphous Si), and biogenic Si bodies (`phytoliths`). Thereby extractions with phosphate, oxalate, and NaOH were conducted sequentially. Results and conclusions First results from the two highland landscapes show that the stocks of `reactive` Si fractions differ considerably within the landscapes (i.e., by a factor of up to 3). The differences between landscapes are, however, even more pronounced (factors of 3-8), which can be attributed to differences in the weathering status of the soils. Our preliminary conclusion is that soil weathering status is the main determinant of the stocks of `reactive` Si in paddy topsoils. Agricultural practice can, however, also exert significant effects. In landscapes with highly weathered soils, the sustained supply of Si to rice plants might therefore largely depend on appropriate agricultural practices.

Marxen, A.; Klotzbücher, T.; Vetterlein, D.; Jahn, R.

2012-12-01

252

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

253

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.

Li, Xia; Wang, Hang; Gan, ShaoHua; Jiang, DaQian; Tian, GuangMing; Zhang, ZhiJian

2013-01-01

254

Integral field spectroscopy of H II regions in M33  

NASA Astrophysics Data System (ADS)

Integral field spectroscopy is presented for star-forming regions in M33. A central area of 300 × 500 pc2 and the external H II region IC 132, at a galactocentric distance ˜19 arcmin (4.69 kpc), were observed with the Potsdam Multi-Aperture Spectrophotometer instrument at the 3.5-m telescope of the Centro Astronómico Hispano-Alemán (CAHA, aka Calar Alto Observatory). The spectral coverage goes from 3600 Å to 1 ?m to include from [O II] ?3727 Å to the near-infrared lines required for deriving sulphur electron temperature and abundance diagnostics. Local conditions within individual H II regions are presented in the form of emission-line fluxes and physical conditions for each spatial resolution element (spaxel) and for segments with similar H? surface brightness. A clear dichotomy is observed when comparing the central to outer disc H II regions. While the external H II region has higher electron temperature plus larger H? equivalent width, size and excitation, the central region has higher extinction and metal content. The dichotomy extends to the Baldwin-Phillips-Terlevich (BPT) diagnostic diagrams that show two orthogonal broad distributions of points. By comparing with pseudo-3D photoionization models, we conclude that the bulk of observed differences are probably related to a different ionization parameter and metallicity. Wolf-Rayet (WR) features are detected in IC 132, and resolved into two concentrations whose integrated spectra were used to estimate the characteristic number of WR stars. No WR features were detected in the central H II regions despite their higher metallicity.

López-Hernández, Jesús; Terlevich, Elena; Terlevich, Roberto; Rosa-González, Daniel; Díaz, Ángeles; García-Benito, Rubén; Vílchez, José; Hägele, Guillermo

2013-03-01

255

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

256

Magnetic fields in star-forming regions - Observations  

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

257

Predictive Model for Phosphorus Accumulation in Paddy Soils with Long-Term Inorganic Fertilization  

Microsoft Academic Search

Prediction of accumulation of available phosphorus (P) in paddy soils is crucial for the best management of P fertilizers. Based on the long-term double-rice rotation systems, a predictive model for accumulation rates of Olsen P in paddy soils with chemical fertilization was developed. In paddy soils with more than 40 kg applied P ha, the accumulation of Olsen P in

J. M. Li; J. S. Gao; J. Liu; M. G. Xu; Y. B. Ma

2012-01-01

258

Differentiated Response of Denitrifying Communities to Fertilization Regime in Paddy Soil  

Microsoft Academic Search

The impact of fertilization regimes on sequential denitrifying communities was investigated in a rice paddy field with 17 years\\u000a continuous fertilization, located in Taoyuan Agro-ecosystem Research Station (110°72? E, 28°52? N), China. The diversity,\\u000a community composition, and size of denitrifying genes of narG, qnorB, and nosZ were determined using molecular tools including terminal restriction fragment length polymorphism, quantitative polymerase\\u000a chain reaction

Zhe Chen; Jinbo Liu; Minna Wu; Xiaoli Xie; Jinshui Wu; Wenxue Wei

259

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

260

Analysis of supersonic combustion flow fields with embedded subsonic regions  

NASA Technical Reports Server (NTRS)

The viscous characteristic analysis for supersonic chemically reacting flows was extended to include provisions for analyzing embedded subsonic regions. The numerical method developed to analyze this mixed subsonic-supersonic flow fields is described. The boundary conditions are discussed related to the supersonic-subsonic and subsonic-supersonic transition, as well as a heuristic description of several other numerical schemes for analyzing this problem. An analysis of shock waves generated either by pressure mismatch between the injected fluid and surrounding flow or by chemical heat release is also described.

Dash, S.; Delguidice, P.

1972-01-01

261

Analysing the accuracy of airborne gravity field observations and their contribution to regional gravity field models  

NASA Astrophysics Data System (ADS)

Airborne gravity field observations show different accuracies and data gaps due to flight turbulences; their irregular spatial distribution leads to a variable spatial resolution. However, the measurements contain precious information of the Earth's gravitational potential in the high frequency domain, i.e. degree values of at least 1000 and thus deliver a valuable contribution to enrich gravity field models. We present regional gravity field models for Northern Germany computed from BKG/DNSC airborne data sets based on two different flight campaigns in 2006 and 2007/08. Our intention is to detect and overcome less accurate measurements, data gaps and inconsistencies in spatial resolutions. For the generation of regional gravity field models we use series expansions in terms of localising basis functions. Entire error propagation enables analysing variances and covariances of the estimated series coefficients and further of evaluated functionals of the Earth's gravity field. Furthermore, we present the combination of the airborne measurements with partly overlapping terrestrial and altimetry data sets as well as with observations from global satellite gravity field missions such as GOCE. For the relative weighting of the different observation types we use the method of variance component estimation. We study the resulting regional gravity field models using (1) only high-resolution airborne data, (2) the combination with terrestrial data and (3) a combination with altimetry and GOCE data which are more sensitive in the mid and low frequency domain. Furthermore, we compare the results with regional models without the airborne data sets in order to analyse the impact and the contribution of the high-resolution airborne observations.

Lieb, Verena; Schmidt, Michael; Dettmering, Denise; Liebsch, Gunter

2014-05-01

262

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

263

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

264

A soil core sampler for paddy soils and some physical properties of the soils under waterlogged condition  

Microsoft Academic Search

IntroductionRecent investigations in soil science have shown that physical properties of paddy soils are of great importance to rice-production. There is extensive literature on the chemical property of paddy soils, but little information on the physical property of paddy soils, especially under waterlogged condition. For studying the physical property of flooded paddy soils, it is necessary to collect the soil

Keizaburo Kawaguchi; Daizo Kita; Kazutake Kyuma

1956-01-01

265

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

266

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.

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

2014-01-01

267

[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

268

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

269

Mössbauer spectroscopic characterization of iron compounds in paddy soil  

NASA Astrophysics Data System (ADS)

Chemical states of iron and their vertical distribution in paddy soil, which was derived from weathered volcanic ashes, have been investigated by57Fe Mössbauer spectroscopy. The relative amount of paramagnetic Fe3+ has no dependence on depth, whereas that of magnetic Fe3+ decreases with an increase in depth. The paramagnetic Fe2+ can be divided into two fractions which show an opposite dependence on depth from each other. The depth profile of the iron components clearly reflects the chemical conditions characteristic of the paddy environment, and the origin of the iron components is also discussed.

Matsuo, Motoyuki; Kobayashi, Takaaki; Tsurumi, Makoto

1994-12-01

270

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

NASA Technical Reports Server (NTRS)

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 first step in assessing the design of the ASRM forward and aft field joints in order to assure the proper operation of the motor prior to further development of test firing. The analyses presented here were performed by employing a two-dimensional axisymmetric assumption. Fluent/BFC, a three dimensional full Navier-Stokes flow field code, was used to make the numerical calculations. This code utilizes a staggered grid formulation along with the SIMPLER numerical algorithm. Wall functions are used to determine the character of the laminar sublayer, and a standard kappa-epsilon turbulence model is used to close the fluid dynamic equations. The analyses performed to this date verify that the ASRM field joint design operates properly. The fluid dynamic stresses at the field joints are small due to the inherent design of the field joints. A problem observed in some other solid rocket motors is that large fluid dynamic stresses are generated at the motor joint on the downstream propellant grain due to forward facing step geometries. The design of the ASRM field joints are such that this is not a problem as shown by the analyses. Also, the analyses of the inhibitor stub left protruding into the port flow from normal propellant burn back show that more information is necessary to complete these analyses. These analyses were performed as parametric analyses in relation to the height of the inhibitor stub left protruding into the motor port. A better estimate of the amount of the inhibitor stub remaining at later burn times must be determined since the height which the inhibitor stub protrudes into the port flow drastically affects the fluid dynamics induced stresses on the propellant grain at the field joints.

Dill, Richard A.; Whitesides, Harold R.

1992-01-01

271

Magnetic field measurements in and above a limb active region  

NASA Astrophysics Data System (ADS)

We analyze spectropolarimetric data of a limb active region (NOAA 11302) obtained on September 22nd 2011 using the Facility Infrared Spectrometer (FIRS) at the Dunn Solar Telescope (DST). Stokes profiles including lines of Si I 1028.7 nm and He I 1083 nm were obtained in three scans over a 45"x75" area. Simultaneous narrow band Ca II K and G-band intensity data were acquired with a cadence of 5s at the DST. The He I data show not only typical active region polarization signatures, but also signatures in plumes -- cool post flare loops -- which extend many Mm into the corona across the visible limb. The plumes have remarkably uniform brightness, and the plume plasma is significantly Doppler shifted as it drains from the corona. Using carefully constructed observing and calibration sequences and applying Principal Component Analysis to remove instrumental artifacts, we achieved a polarization sensitivity approaching 0.02%. With this sensitivity we attempt to diagnose the vector magnetic fields and plasma properties of chromospheric and cool coronal material in and above NOAA 11302. Inversions using various radiative transfer models in the HAZEL code are remarkably consistent with the idea that plume spectra are formed in a simple, slab-like geometry, but that the ``disk'' spectra are formed under more traditional models (Milne-Eddington). The inverted magnetic data of He I lines are compared with photospheric inversions of DST Si I and Fe I data from the Solar Dynamics Observatory.

Philip, Judge

2013-07-01

272

Generation and Suppression of E Region Artificial Field Aligned Irregularities  

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

273

Biogenic nitric oxide emission from saline sodic soils in a semiarid region, northeastern China: A laboratory study  

NASA Astrophysics Data System (ADS)

It is well-known that nitric oxide (NO) is an important component in nitrogen biogeochemical cycling produced through biological process of nitrification and denitrification in soils, but the production and the consumption processes of NO in sodic saline soil are less understood. Through a series of laboratory experiments focusing on NO biogenic emissions from four kinds of saline sodic soils of different land use in western Songnen Plain northestern China, we found that the optimum soil moisture for the maximum NO production and emission were 14.0%, 9.0%, 9.5%, and 18% water-filled pore space (WFPS) for soil samples from natural pasture, man-made pasture, paddy field of saline sodic soil mixed sandy soil, and paddy field of pure saline sodic soil, respectively. For a given moisture, NO fluxes increased exponentially with soil temperature at any given soil moisture. The optimum soil moisture for the maximum NO emission for a certain soil type, however, was constant and independent of soil temperature. The NO consumption processes for different land uses were similar in all studied saline sodic soils since the difference of NO consumption rate constant in these soils was small (ranged from 1.07 × 10-6 to 7.45 × 10-6 m3 kg-1 s-1). The NO emission potential for paddy field soils was about 1.2-2-fold higher than pasture soils. On the basis of laboratory results and field monitoring data of soil water content and soil temperature, the average NO fluxes from these saline sodic soils in the region were estimated to be 1.3-4.9 ng m-2 s-1 for an entire plant growth period. NO fluxes for pastures mainly occurred in the dry season and were about threefold higher than that for paddy fields, which was strongly influenced by field management.

Yu, Junbao; Meixner, Franz X.; Sun, Weidong; Liang, Zhengwei; Chen, Yuan; Mamtimin, Buhalqem; Wang, Guoping; Sun, Zhigao

2008-12-01

274

A deeply branched novel phylotype found in Japanese paddy soils  

Microsoft Academic Search

Novel 16S rDNA clones which possibly constitute a sister clade from the two known archaeal lineages, Crenarchaeota and Euryarchaeota, were found in paddy soil environments. Overall signature sequences showed that the clone sequences shared a majority of signature sequence features with the Archaea and Eukarya. However, there were at least nine nucleotides which distinguished the novel clones from the domains

Hongik Kim; Daiske Honda; Satoshi Hanada; Norihiro Kanamori; Satoshi Shibata; Taro Miyaki; Kazunori Nakamura; Hiroshi Oyaizu

275

Floodplain modeling for Paddy's Run at the DOE Fernald Site  

Microsoft Academic Search

The restoration work for an intermittent stream, Paddy's Run, in the boundaries of the U.S. Department of Energy (DOE) Fernald Site, Ohio, managed by Fluor Fernald, involved floodplain expansion and the installation of grade control structures. Floodplain expansion was accomplished by removing earth berms at key locations where the stream was previously channeled. Cross-vane structures were constructed at selected locations

Marek H. Zaluski; Mark A. Ewanic; Steve D. Dunstan

2007-01-01

276

Spatial distribution of SOM parameters during paddy soil evolution  

NASA Astrophysics Data System (ADS)

During the past 2000 years new farmland was created through consecutive land reclamation by protective dikes in the Zhejiang province (Yangtze River Delta, PR China). The consecutive construction of dikes provides a unique chronosequence of soil formation under agricultural use. Parts of the land are used for paddy rice, other parts for a variety of non-irrigated crops (control sites). These soils document the effect of soil redox conditions on the evolution of soil organic matter (SOM) parameters and their spatial distribution during pedogenesis. We hypothesised that the spatial pattern of SOM parameters will change with increasing duration of paddy soil use, leading to a spatial homogenisation due to frequent puddling of topsoils. The subsoils are assumed to be characterised by a higher spatial heterogeneity due to an increased number of redox cycles and ongoing transport processes in the undisturbed subsoil layers. We sampled three plots within the chronosequence (50, 300 and 1000 years of paddy cultivation) to investigate the development of the spatial dependence of SOM parameters. A regular, orthogonal grid with a size of 25 x 25 m and consisting of 70 sampling positions was used at each plot. Three soil depths were sampled, including the puddled topsoil, the plough layer, and a mixed subsoil layer. The measurements included total C and N as well as organic C (OC) concentrations, soil colour and magnetic susceptibility. In each soil layer of the 50 and 300 y old paddy plots, no spatial dependencies of the SOM parameters were found, but a significant spatial dependence was found in each soil layer of the 1000y old paddy site. The spatial distribution of OC and N in the topsoil showed a higher range, a higher (semi-)variance and a stronger spatial dependence compared to the subsoil. Furthermore, the spatial pattern of OC and N is considerably different between top- and subsoil, indicating that OC distributions below the plough layer are controlled by different processes compared to the puddled topsoil. We conclude that paddy soil formation is associated with the development of the spatial distribution of SOM. This process takes at least several hundred years. The spatial pattern of SOM in paddy topsoils is assumed to be management controlled, whereas pedogenic processes are most likely responsible for SOM distributions in subsoils. We assume the compacted plough layer to be responsible for the decoupling of the SOM distribution between topsoil and subsoil.

Kölbl, Angelika; Müller-Niggemann, Cornelia; Schwark, Lorenz; Cao, Zhihong; Fu, Jianrong; Kögel-Knabner, Ingrid

2010-05-01

277

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.

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

2013-01-01

278

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.

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

2013-01-01

279

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

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

280

An Approach to Assessing Flood Risk in Low-lying Paddy Areas of Japan considering Economic Damage on Rice  

NASA Astrophysics Data System (ADS)

Hiroki Minakawa, Takao Masumoto National Institute for Rural Engineering (NIRE), NARO, Japan Flooding is one type of nature disaster, and is caused by heavy rainfall events. In the future, the risk of flooding is predicted to increase due to global climate change. Immediate measures such as strengthening drainage capacity are needed to minimize the damage caused by more frequent flooding, so a quantitative evaluation method of flood risks is needed to discuss countermeasure against these problems. At the same time, rice is an important crop for food production in Japan. However, paddy fields are often damaged by flooding because they are principally spread in lower part of the basin. Therefore, it is also important to assess the damages to paddy fields. This study discusses a method for evaluating a relationship between the risk of flood damage and the scale of heavy rainfall. We also developed a method of estimating the economic effect of a reduction in rice yield by flooding. First, we developed a drainage analysis model that incorporates kinematic and diffusive runoff models for calculating water level in channels and paddies. Next, heavy rainfall data for drainage analyses were generated by using a diurnal rainfall pattern generator. The generator can create hourly data of heavy rainfall, and internal pattern of them is different each. These data were input to the drainage model to estimate flood risk. Simultaneously, we tried to clarify economic losses of a rice yields caused by flooding. Here, the reduction scale in rice yield which shows relations between flooding situation (e.g. water level, duration of submersion etc.) and damage of rice is available to calculate reduction of rice yield. In this study, we created new reduction scales through a pseudo-flooding experiment under real inundation conditions. The methodology of the experiment was as follow: We chose the popular Japanese rice cultivar Koshihikari for this experiment. An experimental arena was constructed in a rice paddy plot, which consisted of two zones, one in which the rice was cultivated as usual with normal water levels, and a flood zone, which was used for submerging rice plants. The flood zone, which was designed to reproduce actual flood disaster conditions in paddy fields, can be filled with water to a depth of 0.3, 0.6 or 0.9 m above ground level, and is divided into two plots, a clean water part and a turbid water part. Thus, the experimental conditions can vary according to 1) the development stage of rice, 2) complete or incomplete submersion, 3) clean or turbid water, and 4) duration of submergence. Finally, the reduction scales were formulated by using the resultant data and it was found that rice is most sensitive to damage during the development stage. Flood risk was evaluated by using calculated water level on each paddy. Here, the averaged duration of inundation to a depth of more than 0.3 m was used as the criteria for flood occurrence. The results indicated that the duration increased with larger heavy rainfall amounts. Furthermore, the damage to rice was predicted to increase especially in low-lying paddy fields. Mitigation measures, such as revising drainage planning and/or changing design standards for the capacity of drainage pumps may be necessary in the future.

Minakawa, H.; Masumoto, T.

2013-12-01

281

The Research on the Judgment of Paddy Rice's Nitrogen Deficiency Based on Image  

NASA Astrophysics Data System (ADS)

Because of the unreliability judgment of paddy rice's nitrogen deficiency depending on the traditional artificial naked eye, in this article, the way of the paddy rice's nitrogen deficiency examination based on image is put forward, to achieve the precise fast lossless detection and judgment on the paddy rice's nitrogen. Based on the sorting function of SMV, paddy rice leaf's visible images are gathered, the texture features of image are extracted, the RBF nuclear function is chosen, the penalty coefficient C and the regularity coefficient ??are set, and the SVM sorting model is constructed. The recurrence sentencing rate to the training sample achieves 100%. The examination is caught on the test sample, and the accuracy rate of examination recognition achieve 95%, which indicates that the method of paddy rice's nitrogen lossless examination judgment by image is effective and feasible to achieve the precise fast judgment on paddy rice's nitrogen.

Sun, Jun; Mao, Hanping; Yang, Yiqing

282

The Research on the Judgment of Paddy Rice's Nitrogen Deficiency Based on Image  

NASA Astrophysics Data System (ADS)

Because of the unreliability judgment of paddy rice’s nitrogen deficiency depending on the traditional artificial naked eye, in this article, the way of the paddy rice’s nitrogen deficiency examination based on image is put forward, to achieve the precise fast lossless detection and judgment on the paddy rice’s nitrogen. Based on the sorting function of SMV, paddy rice leaf's visible images are gathered, the texture features of image are extracted, the RBF nuclear function is chosen, the penalty coefficient C and the regularity coefficient ??are set, and the SVM sorting model is constructed. The recurrence sentencing rate to the training sample achieves 100%. The examination is caught on the test sample, and the accuracy rate of examination recognition achieve 95%, which indicates that the method of paddy rice’s nitrogen lossless examination judgment by image is effective and feasible to achieve the precise fast judgment on paddy rice’s nitrogen.

Sun, Jun; Mao, Hanping; Yang, Yiqing

283

A Predictive Model for Phosphorus Accumulation in Paddy Soils with Long-term Inorganic Fertilization  

Microsoft Academic Search

Prediction of accumulation of available phosphorus (P) in paddy soils is crucial for the best management of P fertilizers. Based on the long-term double-rice rotation systems, a predictive model for accumulation rates of Olsen-P in paddy soils with chemical fertilization was developed. In paddy soils with more than 40 kg applied Pha, the accumulation of Olsen-P in the soils could

J. M. Li; J. S. Gao; J. Liu; M. G. Xu; Y. B. Ma

2012-01-01

284

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

285

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

NASA Astrophysics Data System (ADS)

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

Liu, S.

2014-02-01

286

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

NASA Astrophysics Data System (ADS)

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

Liu, S.

2014-06-01

287

A true-field magnetogram in a solar plage region  

NASA Technical Reports Server (NTRS)

The Near-Infrared Magnetograph is used to make the first 2D image of true magnetic field strength in the solar photosphere. The magnitude of the magnetic field vector is derived with a typical formal precision of + or - 75 G (2 sigma) from circularly polarized spectra of a highly Zeeman-sensitive iron line at 6388.6/cm. The true-field map demonstrates that the properties of 'kilogauss' flux tubes vary coherently on a variety of spatial scales within the 1-arcmin field of view. The measured fields span the range 1000-1700 G. The amplitude of the polarized signal implies that the spatial filling factor of the flux tubes can approach 0.3 at the seeing-limited resolution of 2 arcsec. Magnetic field strength and magnetic flux are statistically related in the sense that weak-field areas are weak-flux areas, but strong fields are present in both strong-flux and weak-flux areas. This implies a degree of independence in the relationship between the filling factor of flux tubes and their individual properties, such as field strength, pressure, and temperature.

Rabin, Douglas

1992-01-01

288

Photospheric Magnetic Field Changes Associated with Transition Region Explosive Events  

Microsoft Academic Search

From a comparison of the Solar and Heliospheric Observatory SUMER spectral data and a time series of Big Bear Solar Observatory magnetograms, we present observational clues to the physical origin of transition region explosive events. First, explosive events rarely occur in the interior of strong magnetic flux concentrations but rather are preferentially found in regions with weak and mixed polarity

Jongchul Chae; Haimin Wang; Chik-Yin Lee; Philip R. Goode; Udo Schuehle

1998-01-01

289

Region-based line field design using harmonic functions.  

PubMed

Field design has wide applications in graphics and visualization. One of the main challenges in field design has been how to provide users with both intuitive control over the directions in the field on one hand and robust management of its topology on the other hand. In this paper, we present a design paradigm for line fields that addresses this challenge. Rather than asking users to input all singularities as in most methods that offer topology control, we let the user provide a partitioning of the domain and specify simple flow patterns within the partitions. Represented by a selected set of harmonic functions, the elementary fields within the partitions are then combined to form continuous fields with rich appearances and well-determined topology. Our method allows a user to conveniently design the flow patterns while having precise and robust control over the topological structure. Based on the method, we developed an interactive tool for designing line fields from images, and demonstrated the utility of the fields in image stylization. PMID:21690652

Yao, Chih-Yuan; Chi, Ming-Te; Lee, Tong-Yee; Ju, Tao

2012-06-01

290

Satellite gravity gradiometry: Secular gravity field change over polar regions  

Microsoft Academic Search

The ESA Gravity and steady state Ocean and Circulation Explorer, GOCE, mission will utilise the principle of satellite gravity gradiometry to measure the long to medium wavelengths in the static gravity field. Previous studies have demonstrated the low sensitivity of GOCE to ocean tides and to temporal gravity field variations at the seasonal scale. In this study we investigate the

Philip Moore; Matt A. King

2010-01-01

291

Methane emissions from rice paddies : experiments and modelling  

Microsoft Academic Search

This thesis describes model development and experimentation on the comprehension and prediction of methane (CH 4<\\/sub> ) emissions from rice paddies. The large spatial and temporal variability in CH 4<\\/sub> emissions and the dynamic non-linear relationships between processes underlying CH 4<\\/sub> emissions impairs the applicability of empirical relations. Mechanistic concepts are therefore starting point of analysis throughout the thesis.The process

Bodegom van P. M

2000-01-01

292

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

293

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

Microsoft Academic Search

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

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

2000-01-01

294

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

295

Evidence of deflected super-Alfvénic electron jet in a reconnection region with weak guide field  

NASA Astrophysics Data System (ADS)

numerical simulations demonstrated that electron diffusion region develops into two-scale structure, i.e., the inner electron diffusion region and the outer electron diffusion region. The outer diffusion region is manifested as super-Alfvénic electron jet embedded in central current sheet. However, the electron jets are deflected from neutral sheet with a weak guide field. In this paper we present the in situ evidence of deflected super-Alfvénic electron jet in a reconnection region with a weak guide field in the Earth's magnetotail. The electron-scale jet was detected at about 37 ion inertial lengths from the X line. There was a strong electric field at the jet. The strong electric field at the jet was primarily balanced by Hall electric field, as the intense current was mainly carried by magnetized electrons. Another event in the magnetosheath also supports our conclusion that guide field deflects the electron jet away the neutral sheet.

Zhou, Meng; Deng, Xiaohua; Tang, Rongxin; Pang, Ye; Xu, Xiaojun; Yuan, Zhigang; Huang, Shiyong

2014-03-01

296

Reduced methane emissions from large-scale changes in water management of China's rice paddies during 1980-2000  

Microsoft Academic Search

Decreased methane emissions from paddy rice may have contributed to the decline in the rate of increase of global atmospheric methane (CH4) concentration over the last 20 years. In China, midseason paddy drainage, which reduces growing season CH4 fluxes, was first implemented in the early 1980s, and has gradually replaced continuous flooding in much of the paddy area. We constructed

Changsheng Li; Jianjun Qiu; Steve Frolking; Xiangming Xiao; William Salas; Berrien Moore; Steve Boles; Yao Huang; Ronald Sass

2002-01-01

297

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

298

Chemical characteristics and potential source of fulvic acids leached from the plow layer of paddy soil  

Microsoft Academic Search

To understand better the chemical characteristics and source of dissolved organic matter (DOM) leached from the plow layer of rice paddies, a lysimeter study was conducted, which simulated submerged paddy topsoil during rice growth. The fulvic acid (FA) fraction in the percolation water from the lysimeter was collected by adsorption onto insoluble polyvinylpyrrolidone (PVP), and the temporal variations in its

Nagamitsu Maie; Akira Watanabe; Makoto Kimura

2004-01-01

299

Factors impacting yields in rain-fed paddies of the lower Mekong River Basin  

Microsoft Academic Search

The Mekong River Basin (MRB) is the biggest basin in Monsoon Asia. About 80% of the agricultural lands, which occupy about 40% of the basin are rain-fed paddy rice area. Therefore, it is assumed that changes in rain-fed paddy rice production affect the total agricultural production to a great degree in the Mekong River Basin. While there are many factors

Katsuyuki Shimizu; Takao Masumoto; Thanh Hai Pham

2006-01-01

300

Happiness and its Influencing Factors among Paddy Farmers in Granary Area of MADA  

Microsoft Academic Search

The study aims to study the factors associated with the level of happiness among paddy farmer's household in the granary area of Kedah. The study used quantitative research technique by using interview questionnaire to obtain data at the household level. Structural Equation Modeling (SEM) used to analyze the factors affecting happiness of the paddy farmers statistically. The study found that

Roslina Kamaruddin; Jamal Ali; Nariman Mohd. Saad

2013-01-01

301

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

302

The strain rate field in the eastern Mediterranean region, estimated by repeated GPS measurements  

Microsoft Academic Search

We use the combined GPS velocity field of the eastern Mediterranean for the period 1988 to 1996 to determine crustal deformation strain rates in a region comprising the Hellenic arc, the Aegean Sea, and western Anatolia. We interpret the velocity field and determine the strain rate tensor by the spatial derivatives of the collocated motion vectors. The region following the

Hans-Gert Kahle; Christian Straub; Robert Reilinger; Simon McClusky; Robert King; Kenneth Hurst; George Veis; Kim Kastens; Paul Cross

1998-01-01

303

Magnetic and Gravitational Fields of the Baikal Region as Related to Its Seismicity.  

National Technical Information Service (NTIS)

The Baikal region is one of the most seismic areas of the globe, because of crustal re-working (reactivation) of the Caledonian platform. This document describes the gravity field of the transbaikal, the magnetic field of the Baikal region, and the patter...

A. P. Bulmasov

1967-01-01

304

Observation of the transition from the near-field to the far-field region for broadband terahertz radiation  

Microsoft Academic Search

Summary form only given. In the antenna theory, it has long been well known that the space surrounding an antenna can be divided into the near- and far-field region. But in the terahertz (THz) optoelectronics community, this had not received much attention until recently when Budiarto et al. (1998) observed the near-field effect in the measurement of THz radiation from

S.-G. Park; M. R. Melloch; A. M. Weiner

1999-01-01

305

Asymmetry of the Ion Diffusion Region Hall Electric and Magnetic Fields during Guide Field Reconnection: Observations and Comparison with Simulations  

SciTech Connect

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

Eastwood, J. P. [Blackett Laboratory, Imperial College London, London SW7 2AZ (United Kingdom); Shay, M. A. [Bartol Research Institute, Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716 (United States); Phan, T. D.; Oieroset, M. [Space Sciences Laboratory, University of California, Berkeley, California 94720 (United States)

2010-05-21

306

The Magnetic Field Distribution in Active Regions in the Quiet Time and during Large Solar Flares  

NASA Astrophysics Data System (ADS)

Many controversial results about magnetic field behavior in active regions during solar flares are published. The magnetic field dynamics of active regions that produce large (X class) flares are investigated in this paper. The magnetic flux is obtained by using the results of calculations of the normal magnetic component in the active region. It is shown that the main condition for appearance of an X clas s flare is the big magnetic flux (' > 1022Mx) of active region. This condition is necessary but not a sufficient. The large flare appears above an active region, if the magnetic field distribution is very complex. A simple active region with the bipolar magnetic field distribution does not produce a flare. There are no singular magnetic lines above a bipolar region, which can be responsible for a current sheet creation before the flare. During a solar flare, when the accumulated energy is fast released, the conservation of the magnetic field distribution in the active region during the majority of flares takes place. This surprising fact follows from the analysis of the array data obtained with the SOHO and SDO space crafts. The presented results support the flare theory based on the slow magnetic energy accumulation in the coronal current sheet before a flare and its explosive realize due to current sheet instability. The scheme of the current sheet creation is discussed, which explains the magnetic field dissipation in the corona without perturbations of magnetic field distribution on the Sun surface during

Podgorny, I. M.; Podgorny, A. I; Meshalkina, N. S.

2014-03-01

307

Remediation of cadmium-contaminated paddy soils by washing with calcium chloride: verification of on-site washing.  

PubMed

We developed a new, three-step soil-wash method to remediate Cd-contaminated paddy fields. The method comprises (1) chemically washing the field soil with a CaCl2 solution; (2) washing the treated soil with water to eliminate residual Cd and CaCl2; and (3) on-site treatment of wastewater using a portable wastewater treatment system. Cd concentrations in the treated water were below Japan's environmental quality standard (0.01 mg Cd L-1), and the removal of Cd from the exchangeable fraction was 55% and from the acid-soluble fraction 15%. While soil fertility properties were affected by the soil washing, adverse effects were not crucial and could be corrected. The washing had no affect on rice growth, and reduced the average Cd concentration in rice grains by about two-thirds compared to a control plot. These results confirmed the effectiveness of the soil-wash method in remediating Cd-contaminated paddy fields. PMID:17141928

Makino, Tomoyuki; Kamiya, Takashi; Takano, Hiroyuki; Itou, Tadashi; Sekiya, Naoki; Sasaki, Kouta; Maejima, Yuji; Sugahara, Kazuo

2007-05-01

308

Polar region Birkeland current, convection, and aurora for northward interplanetary magnetic field  

SciTech Connect

Viking magnetic field, electric field, and image data have been used to assess polar region phenomena for steady state northward interplanetary magnetic field (IMF) conditions. Regions of polar Birkeland current and convection and their extent from the vicinity of the magnetic pole are determined. Also discussed are mechanisms that could produce polar aurora in general; two suggestions are (1) converging electric fields from convection patterns alone and (2) the bifurcation of the magnetotail with its associated plasma transport from convection patterns. Macroscopic (> 1{degree} latitude) systems of Birkeland currents and convection in the polar regions have been established for a case on April 9, 1986, from Viking spacecraft data. The current systems were confined to the highest latitudes of the polar regions and occurred during strongly northward IMF with a significantly negative B{sub x}. An arc extends across the polar region within the dawn cell of Birkeland current. The arc is located at a sunward to antisunward convection reversal that corresponds to a converging electric field. A converging electric field ({gradient} {center dot} E < 0) alone is suggested as the cause of this polar arc. The signature of both transverse disturbance vectors indicates that the polar region dawn NBZ Birkeland current does not connect to the dayside auroral region. It is inferred that the dawn polar region convection cell associated with this Birkeland current is also limited in the sunward direction and does not connect to the dayside auroral region convection.

Zanetti, L.J.; Potemra, T.A.; Erlandson, R.E.; Bythrow, P.F.; Anderson, B.J. (Johns Hopkins Univ., Laurel, MD (United States)); Murphree, J.S. (Univ. of Calgary, Alberta (Canada)); Marklund, G.T. (Royal Inst. of Tech., Stockholm (Sweden))

1990-05-01

309

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

310

Influence of mechanical vibrations on the field quality measurements of LHC interaction region quadrupole magnets  

Microsoft Academic Search

The high gradient quadrupole magnets being developed by the US-LHC Accelerator Project for the LHC Interaction Regions have stringent field quality requirements. The field quality of these magnets will be measured using a rotating coil system presently under development. Mechanical vibrations of the coil during field quality measurements are of concern because such vibrations can introduce systematic errors in measurement

J. DiMarco; H. Glass; P. Schlabach; C. Sylvester; J. C. Tompkins; J. Krzywinski

2000-01-01

311

Combined impacts of freeze-thaw processes on paddy land and dry land in Northeast China.  

PubMed

The quantity of spring snowmelt infiltration and runoff, which affects the hydrology of the freeze zone, depends on the antecedent soil water content (SWC) conditions at the time of the soil's freezing. An understanding of the characteristics of frozen soil is essential for spring sowing in the agricultural freeze zones. The main goal of this study was to evaluate the differences in the freeze-thaw process and the freeze-thaw-induced water redistribution between the paddy and dry lands in a freeze zone. For this purpose, a field study was conducted in the winter of 2011-2012 for two types of farmlands in Northeast China. To illustrate the soil's frost dynamics over time, the measured SWCs at different depths (15, 30, 60, and 90 cm) were transformed into different expressions including the SWC dynamic, the frozen soil's profile, and the freezing and thawing front trace. The freezing characteristics in the paddy land, in contrast to that in the dry land, had a higher freezing point temperature, a larger amount of water movement to the upper layer, and a 2.76 mm larger accumulation of water in the upper layer. However, the increase of SWC (which is equivalent to thawing) was evidently faster than the decrease of SWC (which is equivalent to freezing). The water in the frozen soil's profile was most likely redistributed towards the freezing front before soil temperature (ST) falls below the freezing point. The findings may partially explain the soil's freeze-thaw characteristics for the different stages as well as the combined impact of these characteristics with farmland use types on soil hydrology; the findings may also provide a foundation for forecasting the hydrologic response of the freeze-thaw process and provide guidance for management strategies dealing with seasonally frozen agricultural soils. PMID:23584030

Chen, Siyang; Ouyang, Wei; Hao, Fanghua; Zhao, Xuchen

2013-07-01

312

Magnetic Field Improvement in End Region of Rectangular Planar DC Magnetron Based on Particle Simulation  

NASA Astrophysics Data System (ADS)

For a rectangular planar direct current (DC) magnetron, anomalous target erosion may occur in the curve-out region and inner side of the curved region. One key factor is that the magnetic field in the end region is weaker than that in the straight region, and another important factor may be that there is a circumferential component of the magnetic field in the curved region. Through a calculation of three-dimensional magnetic field for the rectangular magnetron, a magnet structure shimmed by permanent magnet bars and ferromagnetic bars is proposed to solve the above problems. Through a three-dimensional non-self-consistent particle simulation and the Yamamura/Tawara formula, the target erosion profile could be predicted. The simulation results show that for an improved uniformity in magnetic field, the entire target utilization could be much enhanced.

Qiu, Qingquan; Li, Qingfu; Su, Jingjing; Jiao, Yu; Jim, Finley

2008-12-01

313

Cumulative ecological impacts of two successive annual treatments of imidacloprid and fipronil on aquatic communities of paddy mesocosms.  

PubMed

Agricultural landscapes, including paddies, play an important role in maintaining biodiversity, but this biodiversity has been under the threat of toxic agro-chemicals. Our knowledge about how aquatic communities react to, and recover from, pesticides, particularly in relation to their residues, is deficient, despite the importance of such information for realistic environmental impact assessment of pesticides. The cumulative ecological impacts on aquatic paddy communities and their recovery processes after two successive annual applications of two systemic insecticides, imidacloprid and fipronil, were monitored between mid-May and mid-September each year. The abundance of benthic organisms during both years was significantly lower in both insecticide-treated fields than in the controls. Large-impacts of fipronil on aquatic arthropods were found after the two years. Growth of medaka fish, both adults and their juveniles, was affected by the application of the two insecticides. A Principal Response Curve analysis (PRC) showed the escalation and prolongation of changes in aquatic community composition by the successive annual treatments of each insecticide over two years. Residues of fipronil in soil, which are more persistent than those of imidacloprid, had a high level of impact on aquatic communities over time. For some taxonomic groups, particularly for water surface-dwelling and water-borne arthropods, the second annual treatment had far greater impacts than the initial treatment, indicating that impacts of these insecticides under normal use patterns cannot be accurately assessed during short-term monitoring studies, i.e., lasting less than one year. It is concluded that realistic prediction and assessment of pesticide effects at the community level should also include the long-term ecological risks of their residues whenever these persist in paddies over a year. PMID:22521688

Hayasaka, D; Korenaga, T; Suzuki, K; Saito, F; Sánchez-Bayo, F; Goka, K

2012-06-01

314

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

315

Influence of non-stationary field of magnetospheric convection on the D-region  

NASA Technical Reports Server (NTRS)

Perturbations of F region electron density caused by the extension of magnetospheric convection electric field to middle latitudes are already well known. For the D region of the first observations are believed to be reported by Eliseyev, Kashpar and Nikitin (1988). On several occasions, following the southward turning of the Bz-component of interplanetary magnetic field (IMF) small disturbances of the D region electron density were detected at night by steep-incidence VLF sounding, which may be attributed to the influence of the penetrated convection electric field (CEF). Some evidence is given of a local time dependence of the CEF effect in the D region and a rather good correlation is demonstrated at the initial stage of disturbance between high latitude magnetic field variations and simultaneous perturbation of the midlatitude ionospheric reflection height.

Eliseyev, A. YU.; Kashpar, Yu. V.; Nikitin, A. A.

1989-01-01

316

Regional Mapping of the Lunar Crustal Magnetic Field: Correlation of Strong Anomalies with Curvilinear Albedo Markings  

NASA Technical Reports Server (NTRS)

Using high-resolution regional Lunar Prospector magnetometer magnetic field maps, we report here a close correlation of the strongest individual crustal anomalies with unusual curvilinear albedo markings of the Reiner Gamma class.

Hood, L. L.; Yingst, A.; Zakharian, A.; Lin, R. P.; Mitchell, D. L.; Halekas, J.; Acuna, M. H.; Binder, A. B.

2000-01-01

317

Blindness Due to Sellar Region Tumor Caused Apoplexy; Visual Field Investigation Helps the Diagnosis.  

National Technical Information Service (NTIS)

Chiasmal region tumor caused apoplexy is not uncommon. As its clinical picture varies and is complicated, early diagnosis is usually difficult. 7 cases are reported with marked visual loss, the presenting symptom. Visual fields all revealed definite chias...

L. Yuanxiu

1980-01-01

318

Application of a Generalized Leibniz Rule for Calculating Electromagnetic Fields within Continuous Source Regions.  

National Technical Information Service (NTIS)

In deriving the electric and magnetic fields in a continuous source region by differentiating the vector potential, the central obstacle is the dependence of the integration limits on the differentiation variable. Here, an alternative derivation is presen...

M. Silberstein

1989-01-01

319

Precise plant height monitoring and biomass estimation with Terrestrial Laser Scanning in paddy rice  

NASA Astrophysics Data System (ADS)

Optimizing crop management is a major topic in the field of precision agriculture as the growing world population puts pressure on the efficiency of field production. Accordingly, methods to measure plant parameters with the needed precision and within-field resolution are required. Studies show that Terrestrial Laser Scanning (TLS) is a suitable method to capture small objects like crop plants. In this contribution, the results of multi-temporal surveys on paddy rice fields with the TLS system Riegl LMS-Z420i are presented. Three campaigns were carried out during the key vegetative stage of rice plants in the growing period 2012 to monitor the plant height. The TLS-derived point clouds are interpolated to visualize plant height above ground as crop surface models (CSMs) with a high resolution of 0.01 m. Spatio-temporal differences within the data of one campaign and between consecutive campaigns can be detected. The results were validated against manually measured plant heights with a high correlation (R2 = 0.71). Furthermore, the dependence of actual biomass from plant height was evaluated. To the present, no method for the non-destructive determination of biomass is found yet. Thus, plant parameters, like the height, have to be used for biomass estimations. The good correlation (R2 = 0.66) leads to the assumption that biomass can be estimated from plant height measurements. The results show that TLS can be considered as a very promising tool for precision agriculture.

Tilly, N.; Hoffmeister, D.; Cao, Q.; Lenz-Wiedemann, V.; Miao, Y.; Bareth, G.

2013-10-01

320

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

Microsoft Academic Search

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

Ronald W. P. King; Sheldon S. Sandler

1994-01-01

321

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

Microsoft Academic Search

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

Sinclair

2005-01-01

322

Effect of long-term paddy-upland yearly rotations on rice (Oryza sativa) yield, soil properties, and bacteria community diversity.  

PubMed

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

323

Criteria for and statistics of electron diffusion regions associated with subsolar magnetic field reconnection  

NASA Astrophysics Data System (ADS)

The definition of "electron diffusion regions" and criteria for identifying them in magnetic field reconnection events are given. By employing these criteria and further constraints on the measured parallel electric field, 117 electron diffusion regions have been found in searching through 3 years of Polar satellite subsolar data. They exist in filamentary currents in which parallel electric fields and depressed plasma densities are found and where the electron beta is generally less than 1. The average parallel electric field in these events is about 30% of the average 38 mV/m perpendicular field. The size of these regions is the order of the electron skin depth or less. These electron diffusion regions are topological boundaries in the electron and magnetic field line flows because the components of E × B/B2 on their opposite sides are frequently different. These regions are found throughout the magnetopause but mainly at the magnetospheric separatrix. The divergence of the pressure tensor in the Generalized Ohm's Law may be the leading term that balances the parallel electric field if the observed large plasma density variations (and hence electron pressure variations) were spatial and not temporal. The picture resulting from this data is of a magnetopause that is highly structured and filamentary and very different from a linear, laminar, symmetric structure sometimes considered in theories or simulations. However, it is emphasized that events such as those described have been found in fewer than 20% of the magnetopauses examined, so the conventional picture may be more prevalent.

Mozer, F. S.

2005-12-01

324

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

325

A low-complexity region-based video coder using backward morphological motion field segmentation  

Microsoft Academic Search

We introduce a novel region-based video compression framework based on morphology to efficiently capture motion correspondences between consecutive frames in an image sequence. Our coder is built on the observation that the motion field associated with typical image sequences can be segmented into component motion subfield “clusters” associated with distinct objects or regions in the scene, and further, that these

Xuguang Yang; Kannan Ramchandran

1999-01-01

326

Region-based video coding using backward motion-field segmentation  

Microsoft Academic Search

We introduce a novel region-based video compression framework based on morphology to efficiently capture motion correspondences between consecutive frames in an image sequence. Our coder is built on the observation that the motion field associated with typical image sequences can be segmented into component motion subfield 'clusters' associated with distinct objects or regions in the scene, and further that these

Xuguang Yang; Kannan Ramchandran

1997-01-01

327

Regional Field Verification - Operational Results from Four Small Wind Turbines in the Pacific Northwest  

Microsoft Academic Search

The purpose of the Department of Energy\\/National Renewable Energy Laboratory's (DOE\\/NREL) Regional Field Verification (RFV) project is to support industry needs for gaining initial field operation experience with small wind turbines and to verify the performance, reliability, maintainability, and cost of small wind turbines in diverse applications. In addition, RFV aims to help expand opportunities for wind energy in new

K. Sinclair; J. Raker

2006-01-01

328

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

329

Flexible gas insulated transmission line having regions of reduced electric field  

DOEpatents

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

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

1983-01-01

330

Density cavity in magnetic reconnection diffusion region in the presence of guide field  

NASA Astrophysics Data System (ADS)

Understanding the structure of the diffusion region of magnetic reconnection is crucial to pinpoint the mechanism of energy conversion from magnetic field to plasma. Characteristics of a diffusion region with guide field (i.e., component reconnection) may be significantly different from those of a diffusion region without guide field (i.e., antiparallel reconnection). In this study, we attempt to understand the structure of a diffusion region with guide field by studying the density cavity along separatrix. We present an event in which a density cavity was detected by the Cluster spacecraft in a diffusion region in the presence of guide field. The cavity was located around the separatrix region on the southern hemisphere of the neutral sheet and earthward of the X-line and was coincident with strong magnetic field compression. The width of the cavity was on the ion inertial scale. This cavity contained a relatively strong antiparallel current, which was mainly contributed by parallel streaming electrons with energy of 1-10 keV. Enhancements of lower hybrid wave and electromagnetic whistler wave were observed inside the cavity. These waves are probably excited by parallel streaming electrons along separatrix via electron beam instability. Two-dimensional electromagnetic particle-in-cell simulation was employed to study the structure of the density cavity. The location and scale of the cavity and the signature of electric current and electron velocity are consistent with our observations. It is found that there was displacement between the position of electron density minimum and out-of-plane magnetic field maximum in reconnection with guide field. However, this displacement is much less than that in reconnection without guide field. There was no significant acceleration for electrons to reach energy larger than 30 keV at the cavity.

Zhou, M.; Pang, Y.; Deng, X. H.; Yuan, Z. G.; Huang, S. Y.

2011-06-01

331

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

NASA Technical Reports Server (NTRS)

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

Schmidt, R. F.

1982-01-01

332

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

333

Magnetic field observations as Voyager 1 entered the heliosheath depletion region.  

PubMed

Magnetic fields measured by Voyager 1 (V1) show that the spacecraft crossed the boundary of an unexpected region five times between days 210 and ~238 in 2012. The magnetic field strength B increased across this boundary from ?0.2 to ?0.4 nanotesla, and B remained near 0.4 nanotesla until at least day 270, 2012. The strong magnetic fields were associated with unusually low counting rates of >0.5 mega-electron volt per nuclear particle. The direction of B did not change significantly across any of the five boundary crossings; it was very uniform and very close to the spiral magnetic field direction, which was observed throughout the heliosheath. The observations indicate that V1 entered a region of the heliosheath (the heliosheath depletion region), rather than the interstellar medium. PMID:23811226

Burlaga, L F; Ness, N F; Stone, E C

2013-07-12

334

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

PubMed

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

Phutela, Urmila Gupta; Sahni, Nidhi

2013-06-01

335

Pioneer 7 observations of plasma flow and field reversal regions in the distant geomagnetic tail  

NASA Technical Reports Server (NTRS)

The present paper gives the results of an extensive analysis of plasma and magnetic-field data from Pioneer 7 taken in the geomagnetic tail approximately 1000 earth radii downstream from earth. The principal observations are: (1) measurable fluxes of protons in the tail, flowing away from earth, sometimes with a double-peaked velocity distribution; (2) field reversal regions in which the field changes from radial to antiradial by a vector rotation in the north-south plane; and (3) general characteristics of the tail similar to those observed near earth with good correlation between taillike magnetic fields and plasma.

Walker, R. C.; Lazarus, A. J.; Villante, U.

1975-01-01

336

A model study of how electric field structures affect the polar cap F region  

NASA Technical Reports Server (NTRS)

The ionospheric polar F region's response to a series of electric field structures is studied theoretically, modeling individual electric field structures as elongated two-cell Volland patterns. A semiempirical model of a single electric field structure is developed, and specific structure polar cap electric field models are described. The results of using these models as an input to the Utah State University time-dependent ionospheric model (TDIM) are presented. The implications of the results for present-day 'smooth' input simulations are considered.

Sojka, J. J.; Schunk, R. W.

1988-01-01

337

Technical classification of the clay mineralogical composition of paddy soils using multivariate analysis in reference to rice production  

Microsoft Academic Search

Clay mineralogical analysis of paddy soils in Nagasaki Prefecture indicated the presence of smectite, vermiculite, clay mica, chlorite, 2:1 mineral-chlorite intergrade, and kaolin mineral. The application of Q-mode factor analysis to the paddy soils using the contents of 6 minerals in the clay fraction and the clay content of the soil as variables enabled to classify 71 paddy soils into

Kazuhiko Egashira; Koji Osaka; Seishiro Nakashima

1992-01-01

338

The Mexico City Outflow and Its Regional Influence: A Regional Model Study in INTEX- B/MIRAGE Field Experiment  

NASA Astrophysics Data System (ADS)

During the NASA INTEX-B and NSF MIRAGE field experiments in Spring of 2006, we applied a regional chemical transport model, STEM-2K3, to make nested forecasts coupled with a global model RAQMS by using its output as lateral and top boundary conditions. WRF mesoscale meteorological model was used to drive the regional model. The model predicted reasonable results compared with NASA DC-8 and NCAR C- 130 aircraft measurements over Mexico and Southern USA. Sulfate is the major ion in the Mexico City plume. Biomass/biofuel burning contributed to black carbon, though it became aged quickly during the transport process. Since aerosols and their precursors were usually co-emitted with gaseous pollutants from Mexico City, their interactions via direct reaction and radiative impacts became evident. The aerosol influence on photolysis rates depend not only on the aerosol optical depth, but also on the absorption portion or single scatter albedo (SSA). Sensitivity studies were performed to reveal the influence of aerosol SSA on photochemical processes over Mexico City and its downwind region. Due to the relatively high altitude of Mexico City, its outflow usually existed in middle troposphere over downwind regions. The radiative impact became a important portion of the influence of Mexico City plumes on downwind surface. The model study over Mexico City surface sites was also evaluated.

Tang, Y.; Carmichael, G. R.; Mena, M.; D'Allura, A.; Chai, T.; Pierce, R. B.; Al-Saadi, J. A.

2006-12-01

339

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

PubMed

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

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

2012-02-01

340

Modeling Cleft-Region Particle Precipitation Using the Interplanetary Magnetic Field and Generalized Auroral Electrojet Indices  

NASA Astrophysics Data System (ADS)

Cleft-region particle precipitation affects several ionospheric processes including ionospheric outflow and ionospheric plasma formations. Cleft-region particle precipitation has been shown to be dependent on the interplanetary magnetic field (IMF) clock angle, the dayside-merging rate/local magnetic field changes, and the characteristic energy of the particles. The OVATION-SM particle precipitation model between 0800 and 1600 MLT is modified to include IMF clock angle effects and model individual characteristic energies. The resulting cleft-region particle precipitation model will be shown as well as data-model comparisons with Polar UVI dayside data. The inclusion of characteristic energy dependence and IMF clock angle effects is expected to provide better dayside auroral power predictions and better spatial-temporal location of the cleft-region.

Mitchell, E. J.; Newell, P. T.; Ridley, A. J.

2013-12-01

341

Main Features of Quasi-Electrostatic Fields in Atmospheric Regions due to Lightning Discharge  

NASA Astrophysics Data System (ADS)

The most important features of the strong quasi-electrostatic fields, generated in the region ionosphereground after a single lightning discharge, due to succeeding redistribution of capacitive spatial charges, are studied in this work. The investigation of these fields is of great importance, particularly since they are considered to be responsible for generation of red sprites in the mesosphere and lower ionosphere over thunderstorms. As experimental measurements show, these quasi-electrostatic fields can cause, more often than sprites, electron heating and conductivity modifications in the mesosphere and ionosphere as well. The temporal behavior and relaxation time of the quasi-electrostatic fields, as well as their spatial extent and orientation are studied. For this purpose an analytical model based on the Maxwell equations under conditions of curl-free electric field is proposed. Such conditions are fulfilled short (less than a millisecond) after beginning of a lightning discharge and last until another discharge. Isotropic conductivity in the region of interest is assumed. Computations are made for the time-course of the quasi-electrostatic fields up to the lower ionosphere. The dynamics of spatial charges in this region, responsible for the quasi-electrostatic fields, is analyzed also. The quasi-electrostatic fields at an altitude observed reach their maximum at a time close to the local relaxation time. Up to the ionosphere this maximum is of an order of V/m per 1 Coulomb of a charge transported by lightning. The field decreases immediately after reaching its maximum in the mesosphere; however, at stratospheric and tropospheric altitudes its maximum forms a plateau, which becomes wider at lower heights. The relaxation of the quasi-electrostatic field at altitudes above 40 km is essentially slower than the local relaxation time of an electrical charge.

Tonev, P. T.

2006-03-01

342

The calculation of electromagnetic fields in the Fresnel and Fraunhofer regions using numerical integration methods  

NASA Technical Reports Server (NTRS)

Some results obtained with a digital computer program written at Goddard Space Flight Center to obtain electromagnetic fields scattered by perfectly reflecting surfaces are presented. For purposes of illustration a paraboloidal reflector was illuminated at radio frequencies in the simulation for both receiving and transmitting modes of operation. Fields were computed in the Fresnel and Fraunhofer regions. A dual-reflector system (Cassegrain) was also simulated for the transmitting case, and fields were computed in the Fraunhofer region. Appended results include derivations which show that the vector Kirchhoff-Kottler formulation has an equivalent form requiring only incident magnetic fields as a driving function. Satisfaction of the radiation conditions at infinity by the equivalent form is demonstrated by a conversion from Cartesian to spherical vector operators. A subsequent development presents the formulation by which Fresnel or Fraunhofer patterns are obtainable for dual-reflector systems. A discussion of the time-average Poynting vector is also appended.

Schmidt, R. F.

1971-01-01

343

Velocity, Density, and Magnetic Field Structure in High-Mass Star Forming Regions  

NASA Astrophysics Data System (ADS)

To understand the detailed structure of four representative high-mass star forming regions, we have performed a comparative analysis of magnetic field structure; mass and velocity structure; and local features such as HII regions, outflows, and infrared sources. This work considers areas 5-15arcmin on a side in Orion A (BN/KL and Bar regions), NGC 2024, W3 Main, and M17. Primary data include (13) CO J=1-0 maps with 50arcsec spatial resolution and 0.1 km\\:s(-1) velocity resolution as well as 100 micron dust emission polarization maps with 35arcsec resolution (provided by J.L. Dotson, C.D. Dowell, D. Schleuning, and R.H. Hildebrand). These recently obtained emission polarization maps represent reliable probes of the projected magnetic field direction in dense clouds. We isolate velocity components in the spectra and then go on to analyze patterns in linewidth, component velocity, column density, polarization percentage, polarization direction, and dispersion in polarization position angle. Our analysis also makes use of field strength measurements and other data in the literature to form a coherent physical picture of what is happening in each source. By comparing the relative importance of magnetic, kinetic, and gravitational energies as well as the dynamical significance of such energetic features as HII regions and outflows, we evaluate the role of the magnetic field in each region.

Kannappan, S. J.; Goodman, A. A.

1995-12-01

344

Electric field structure inside the secondary island in the reconnection diffusion region  

NASA Astrophysics Data System (ADS)

Secondary islands have recently been intensively studied because of their essential role in dissipating energy during reconnection. Secondary islands generally form by tearing instability in a stretched current sheet, with or without guide field. In this article, we study the electric field structure inside a secondary island in the diffusion region using large-scale two-and-half dimensional particle-in-cell (PIC) simulation. Intense in-plane electric fields, which point toward the center of the island, form inside the secondary island. The magnitudes of the in-plane electric fields Ex and Ez inside the island are much larger than those outside the island in the surrounding diffusion region. The maximum magnitudes of the fields are about three times the B0VA, where B0 is the asymptotic magnetic field strength and VA is the Alfvén speed based on B0 and the initial current sheet density. Our results could explain the intense electric field (~100 mV/m) inside the secondary island observed in the Earth's magnetosphere. The electric field Ex inside the secondary island is primarily balanced by the Hall term (j × B)/ne, while Ez is balanced by a combination of (j × B)/ne, -(vi × B), and the divergence of electron pressure tensor, with (j × B)/ne term being dominant. This large Hall electric field is due to the large out-of-plane current density jy inside the island, which consists mainly of accelerated electrons forming a strong bulk flow in the -y direction. The electric field Ey shows a bipolar structure across the island, with negative Ey corresponding to negative Bz and positive Ey corresponding to positive Bz. It is balanced by (j × B)/ne and the convective electric field. There are significant parallel electric fields, forming a quadrupolar structure inside the island, with maximum amplitude of about 0.3B0VA.

Zhou, M.; Deng, X. H.; Huang, S. Y.

2012-04-01

345

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

346

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

NASA Astrophysics Data System (ADS)

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

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

2009-07-01

347

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

NASA Astrophysics Data System (ADS)

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 Investigations of the Sun survey (SOLIS)/Vector Spectromagnetograph (VSM) as a boundary conditions. We compare projections of the resulting magnetic field lines solutions with their respective coronal EUV-images from the Atmospheric Imaging Assembly (SDO/AIA) observed on October 15, 2011 and November 13, 2012. This study has found that the NLFFF model in spherical geometry reconstructs the magnetic configurations for several active regions which agrees to some extent with observations. During October 15, 2011 observation, there are substantial number of trans-equatorial loops carrying electric current.

Tadesse, Tilaye; Wiegelmann, T.; MacNeice, P. J.; Olson, K.

2013-09-01

348

Development of Management Guidelines to Prevent Pollution by Irrigation Return Flow from Rice Fields.  

National Technical Information Service (NTIS)

A three year field and laboratory study was conducted to determine the influence of management practices on the quantity and quality of irrigation return flow from rice paddies. Continuous and intermittent irrigation techniques were used on replanted fiel...

K. W. Brown L. Deuel J. Price D. DeMichele W. R. Teague

1978-01-01

349

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

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

350

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

SciTech Connect

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

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

1990-05-01

351

On some properties of force-free magnetic fields in infinite regions of space  

NASA Technical Reports Server (NTRS)

Techniques for solving boundary value problems (BVP) for a force free magnetic field (FFF) in infinite space are presented. A priori inequalities are defined which must be satisfied by the force-free equations. It is shown that upper bounds may be calculated for the magnetic energy of the region provided the value of the magnetic normal component at the boundary of the region can be shown to decay sufficiently fast at infinity. The results are employed to prove a nonexistence theorem for the BVP for the FFF in the spatial region. The implications of the theory for modeling the origins of solar flares are discussed.

Aly, J. J.

1984-01-01

352

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

SciTech Connect

A system of four current sheets of large-scale field-aligned currents (FACs) was discovered in the data set of simultaneous Viking and DMSP-F7 crossings of the dayside high-latitude region. This paper reports four examples of this system that were observed in the prenoon sector. The flow polarities of FACs are upward, downward, upward, and downward, from equatorward to poleward. The lowest-latitude upward current is flowing mostly in the CPS precipitation region, often overlapping with the BPS at its poleward edge, and is interpreted as a region 2 current. The pair of downward and upward FACs in the middle of the structure are collocated with structured electron precipitation. The precipitation of high-energy (>1 keV) electrons is more intense in the lower-latitude downward current sheet. The highest-latitude downward flowing current sheet is located in a weak, low-energy particle precipitation region, suggesting that this current is flowing on open field lines. Simultaneous observations in the postnoon local time sector reveal the standard three-sheet structure of FACs, sometimes described as region 2, region 1, and mantle (referred to the midday region 0) currents. A high correlation was found between the occurrence of the four FAC sheet structure and negative interplanetary magnetic field (IMF) B{sub Y}. The authors discuss the FAC structure in terms of three types of convection cells: the merging, viscous, and lobe cells. During strongly negative IMF B{sub Y}, two convection reversals exist in the prenoon sector; one is inside the viscous cell, and the other is between the viscous cell and the lobe cell. This structure of convection flow is supported by the Viking electric field and auroral UV image data. Based on the convection pattern, the four FAC sheet structure is interpreted as the latitudinal overlap of midday and morning FAC systems. 47 refs., 12 figs., 1 tab.

Ohtani, S.; Potemra, T.A.; Newell, P.T. [Johns Hopkins Univ., Laurel, MD (United States)] [and others] [Johns Hopkins Univ., Laurel, MD (United States); and others

1995-01-01

353

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

PubMed

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

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

2013-11-01

354

Paddy ground truth data collection and evaluation for land cover mapping  

NASA Astrophysics Data System (ADS)

Ground truth data have grid cells that consist of single land cover classification (pure grid cell), and they are useful as the training data in classifying global land cover. Previous studies showed many global land cover map, however, they have rarely reported locations and collection method of the training data that they might use. Paddy is indispensable classification for global land cover mapping but there is no established method for collecting paddy ground truth data. In this study we collected paddy ground truth candidate data from the existing 1km-resolution China national land use data, which was produced using 30m-resolution LANDSAT/TM data. Since the land use data recorded classification area ratio in each grid cell, it is efficient to collect paddy's pure grid cells. We collected pure grid cells of paddy and segmented them into small areas, and obtained paddy ground truth candidate sites. After the sites whose area >= nine grid cells (=9 km2) were selected, we examined the selected sites' Normalized Difference Vegetation Index (NDVI) time-series changes in 2003 using TERRA/Moderate Resolution Imaging Spectroradiometer (MODIS) 16-days composite data. Furthermore, we chose the sites whose NDVI standard deviation =< 0.1 through 2003, as a result, the number of the selected sites was 271. The 271 candidate sites were assigned to nine China climatic zones, and the sites that are located near climatic boundaries were eliminated. The site whose area is largest in each climatic zone was tried to be selected. Finally, ten sites of paddy ground truth data were collected.

Sato, Hiroshi P.; Tateishi, Ryutaro; Xiao, Jieying

2006-12-01

355

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

NASA Astrophysics Data System (ADS)

The UNAVCO, Inc. Plate Boundary Observatory (PBO) Student Field Assistant Program strives to engage students in further study and careers in the Earth Sciences. Student Field Assistants from a variety of educational backgrounds ranging from high school graduates to master's level students spend a three to five month field season working in tandem with UNAVCO regional Field Engineers. The students work closely with senior staff to reconnaissance, install, and maintain a network of 875 permanent Global Positioning System (GPS) stations in one of the five PBO regions covering the western United States, including Alaska. Practical skills, such as power tool use, drilling, welding, firearms training, and proper field safety procedures, are taught and expected of the students. Installation and maintenance of new and existing GPS stations composes the bulk of the student's responsibilities and duties. When not in the field, students prepare gear and arrange logistics for site installations and maintenance as well as enter metadata and complete installation reports from recently constructed sites. An understanding of the operations of the GPS receivers and the scientific benefit of the network allows for an appreciation and great attention to detail during installation of the sites. Student assistance in the Alaska region during 2007 PBO AK field season was critical to the successful installation of 36 new GPS stations throughout Alaska. Significant benchmarks of the field season included installing six logistically difficult stations in Prince William Sounds, completing the Denali Fault GPS network, four new tiltmeters on Akutan Volcano, completing all installs on the Seward Peninsula as well as several new GPS stations throughout the western interior of the state. Alaska is a prominent area for much movement and deformation as the Pacific Plate subducts beneath the North American Plate resulting in an area of high volcanic activity and heightened crustal deformation. The GPS network that is being constructed aims to better understand much of these earth processes and their effects. To date, the Alaska Region has recently completed its 4th field season and has installed 106 out of a planned 140 stations. During Year 5 of the PBO project, the Alaska PBO regional office will complete the installation of all remaining 34 planned GPS stations including 12 stations on Unimak Island. The 2008 field season will be the last year in the installation phase and will incorporate maintenance of some of the first GPS stations installed in the network during the first and second years of the five year project.

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

2007-12-01

356

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

357

A model of SVC radiation in magnetic dipole field and radiation varying with magnetic field. I - Active region model and SVC radiation source model  

Microsoft Academic Search

The present model of slowly-varying-component (SVC) radiation in a magnetic dipole field employs the latest EUV data on the chromosphere-corona transition region. It is assumed that the plasma conditions above an active region are varying continuously from the center of the region to the adjacent quiet region. The plasma's three physical parameters (electron temperature and density, and magnetic field) are

Ren-Yang Zhao

1991-01-01

358

Ionosphere and ground-based response to field-aligned currents near the magnetospheric cusp regions  

SciTech Connect

A special campaign was conducted at the Sondre Stromfjord incoherent scatter radar facility in October 1985 to study hydromagnetic and atmospheric gravity were phenomena near the cusp regions of the magnetosphere. During a day when the convection reversal boundary was measured just to the north of the radar, a field-aligned current filament of inferred amplitude --2 x 10V A was measured at the boundary. Both ion and electron heating appeared to accompany the current filament. Magnetic field data acquired in the southern conjugate hemisphere are used to conclude that the current filament was probably on closed field lines. The current filament may be evidence of the magnetosphere boundary layer on closed field lines, perhaps produced by the injection of magnetosheath plasmoids onto the field lines by a flux transfer-type reconnection process. copyright American Geophysical Union

Lanzerotti, L.J.; Hunsucker, R.D.; Rice, D.; Lee, L.C.; Wolfe, A.; Maclennan, C.; Medford, L.V.

1987-07-01

359

Education and Training Needs in the Field of Local Development in the Lower Danube Macro Region  

Microsoft Academic Search

The present paper is the result of an effort made by the authors to explore the needs of education and training in the field of local development, according to the situation in Romanian and Bulgarian Danube bordering regions, aiming at designing joint projects to address such needs between the universities to which authors are affiliated. Local development is here understood

Lauren?iu T?chiciu; Nicola Yankov; Alina Elena Balalia

2010-01-01

360

A speed estimator for sensorless vector control of induction machines in the field weakening region  

Microsoft Academic Search

A number of speed estimation schemes for sensorless vector control of induction machines utilise a mathematical model of the machine in the estimation process. Operation of a sensorless indirect rotor flux oriented machine in the field weakening region requires that the variable degree of main flux saturation is recognised and compensated in the speed estimator. The paper describes implementation of

Emil Levi; Mingyu Wang

2000-01-01

361

Dynamics of the thermal field in the transition region of a solid state laser  

Microsoft Academic Search

tering of material) the transition region of operation is most important; hence it is important to carry out a more detailed analysis of the dynamics of the equilibration of the thermal field in the lasing element, taking into account the inhomogeneity of the heat generation distribution in it. In the present work we have carried out an analysis of the

V. A. Buchenkov; Yu. N. Mikhailov; L. N. Soms; A. I. Stepanov; A. M. Fisher

1981-01-01

362

Estimation of Regional Methane Emission from Rice Fields Using Simple Atmospheric Diffusion Models  

Microsoft Academic Search

Two atmospheric diffusion models, the box model ad the ATDL (Atmospheric Turbulent and Diffusion Laboratory) model, were used to calculate regional methane (CH4) emissions of rice fields in the Beijing area. Compared with conventional closed chamber measurements, the box model overestimated CH4 emission because of meteorological conditions--the ground inverse layer was not favorable for the application of the model during

J. G. Liu; Y. H. Zhang; K. S. Shao; M. Shao; L. M. Zeng; S. H. Lu; S. Slanina; H. A. C. Denier van der Gon

2000-01-01

363

Cusp region particle precipitation and ion convection for northward interplanetary magnetic field  

Microsoft Academic Search

Data from Atmosphere Explorer D for periods of strong northward interplanetary magnetic field show the following characteristic behavior in the dayside magnetospheric cusp region: energy-time spectrograms of suprathermal positive ion fluxes exhibit a characteristic 'V' pattern as the spacecraft moves toward higher latitudes; that is, with the peak in the energy spectrum falling in energy and then rising again. Convection

J. L. Burch; P. H. Reiff; R. W. Spiro; R. A. Heelis; S. A. Fields

1980-01-01

364

Cusp region particle precipitation and ion convection for northward interplanetary magnetic field  

Microsoft Academic Search

Data from Atmosphere Explorer D for periods of strong northward interplanetary magnetic field show the following characteristic behavior in the dayside magnetospheric cusp region: Energy-time spectrograms of suprathermal positive ion fluxes exhibit a characteristic 'V' pattern as the spacecraft moves toward higher latitudes; that is, with the peak in the energy spectrum falling in energy and then rising again. Convection

J. L. Burch; P. H. Reiff; R. W. Spiro; R.A. Heelis; S. A. Fields

1980-01-01

365

Morphological Motion Field Representation for Region-Based Image Sequence Coding  

Microsoft Academic Search

We introduce a novel region-based video compression framework that uses amorphological operation to efficiently capture motion correspondences betweenconsecutive frames in an image sequence. Our coder is built on the observationthat the motion field associated with typical image sequences can be segmentedinto component motion subfield "clusters" associated with distinct objects orregions in the scene, and further that these clusters can be

Xuguang Yang; Kannan Ramchandran

1996-01-01

366

The magnetic field structure in high-mass star formation regions  

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

367

Phosphorus removal of rural wastewater by the paddy-rice-wetland system in Tai Lake Basin.  

PubMed

A field experiment was conducted to remove the potential eutrophication effect of P from rural wastewater (RW) during the whole rice growing season of 2007. The experiments consisted of five treatments, namely black water (BW), domestic wastewater (DW), grey water (GW), surface lake water (SW) and surface lake water without P application as a check (CK), with three replicates in a randomized block design. Commercial fertilizer and RW were applied to furnish 40 kg Pha(-1) except CK. Results showed total P (TP) concentration had significantly declined after P application, from October 15 there were no significant increases in TP concentration in the floodwater. TP removal rates from RW was significantly higher (Ppaddy-rice-wetland system and can be widely used to improve the yield of rice. PMID:19596516

Li, S; Li, H; Liang, X Q; Chen, Y X; Wang, S X; Wang, F E

2009-11-15

368

Rice Crop Monitoring by Earth Observation Data in the Asian Region  

NASA Astrophysics Data System (ADS)

Food security is a critical issue for the international community. In June 2011, the meeting of G20 agriculture ministers was held to discuss global food security and they agreed on an "Action Plan on Food Price Volatility and Agriculture". This plan includes a GEO Global Agricultural Monitoring (GEO-GLAM) initiative which utilizes remote sensing to improve projections of crop production and weather forecasting. Hence, satellite remote sensing is expected to contribute national, regional and global food security through the systematic and efficient collection of food security related information such as agro-meteorological condition, crop growth or yield estimation. Food security related information is utilized to take mitigation strategies or policies to manage food shortages or trading, and ensure food security. Especially in Asia, rice is the most important cereal crop because Asian countries are responsible for approximately 90% of the world rice productions and consumptions. There- fore, Asian countries are expected to contribute GLAM through the construction of rice crop monitoring system. We demonstrated the estimation of rice production, the crop phenology monitoring by Earth Observation (EO) data. The aim of this study is to establish a prototype system designed to provide paddy rice area and yield estimation. Generally, crop yield estimation is consist of two components, cultivated area and yield per area. The cultivated areas of paddy field are detected by the seasonal pattern of SAR data over paddy field. This means paddy field is filled with water just before planting rice, then covered by dense vegetation in growing season. The paddy filed map was derived from the seasonal Advanced Land Observation Satellite (ALOS) Phased Array type L-band Synthetic Aperture Radar (PALSAR) data with a simple threshold method. Then, to estimate rice productivity, we applied a simple rice crop model. The input data to the model are physical and chemical properties of the soil, physiological crop characteristics, and daily weather such as photosynthetic active radiation, precipitation, wind velocity and humidity. Some of these parameters were acquired by satellite observations and others are by in-situ measurements. Table 1 shows the result of rice yield estimation of the pilot study area. The results were highly consistent with the validation data of in-situ measurements and the accuracy of paddy acreage and rice yield are 98.6% and 81.9%, respectively. The prototype system to estimate rice yield was developed only for the small pilot area. To expand the system to the whole country for national food security and statistics, crop calendar which identifies the timing of planting or harvesting of each area is needed to estimate productivity of rice. The Asian region has a large variety of the crop intensity such as single or double and sometimes triple cropping and the pattern is mostly relies on the water availability. Since crop intensity affects the rice yield, it is imperative for rice yield estimates to identify crop intensity. High revisit frequency of EO data such as MODIS is useful for identifying crop intensity. Spatial distribution of crop intensities over the Thailand were identified by applying spectrum analysis to the historical MODIS data, then, we demonstrated the relationships between crop intensity and productivity in Thailand with provincial level.

Oyoshi, K.; Sobue, S.; Tomiyama, N.; Okumura, T.; Rakwatin, P.

2012-12-01

369

Thermal instabilities in the edge region of reversed-field pinches  

SciTech Connect

Thermal stability of the edge region of reversed-field pinch configurations is analyzed within the context of a two-fluid model. Two major sources of instability are identified in combination with a parallel electric field: either an electron temperature gradient and/or a density gradient that leads to rapid growth (of several to many ohmic heating rates) over a region of several millimeters around the mode-rational surfaces in the edge region. The basic signature of both instabilities is electrostatic. In the case of the density gradient mode, the signature relies on the effects of electron compressibility, whereas the temperature gradient mode can be identified as the current-convective instability by taking the limit of zero diamagnetic drift, density gradient, thermal force, drift heat flux, and electron compressibility.

Goedert, J.; Mondt, J.P.

1984-04-01

370

Magnetic declination control of the equatorial F region dynamo electric field development and spread F  

SciTech Connect

We have carried out a comparative study of the evening prereversal enhancements in the equatorial F region vertical ionization drift velocities (V/sub z/) over Fortaleza (4 /sup 0/S, 38 /sup 0/W), Brazil, and Jicamarca (12 /sup 0/S, 77 /sup 0/W), Peru, two magnetic equatiorial stations in the American zone. The results show profound dissimilarities in the seasonal trends in the times and widths of the V/sub z/ prereversal peak, which reflect in the spread F characteristics as well, at the two stations. The dissimilarities are shown to be arising mainly from the difference in the magnetic field declination angles that causes differences in the conjugate E region sunset durations and, hence, in the F region polarization electric field development rates at the two stations.

Abdu, M.A.; Bittencourt, J.A.; Batista, I.S.

1981-12-01

371

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

PubMed

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

van Woesik, R

2010-03-01

372

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

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

373

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

374

Electric field structure inside the secondary island in reconnection diffusion region  

NASA Astrophysics Data System (ADS)

Secondary islands have recently been intensively studied because of its essential role in energy dissipation during reconnection. It is generally formed due to tearing instability in a stretched current sheet with or without guide field. In this presentation we study the electric field structure inside the secondary island in diffusion region by large scale two-and-half dimensional Particle-In-Cell (PIC) simulation. Intense in-plane electric fields, which point toward the center of island, are formed inside the secondary island. The magnitudes of in-plane electric field Ex and Ez inside the island are much larger than those outside the island in diffusion region. Their maximum magnitudes are about 3 times the B0VA, where B0 is the asymptotic magnetic field strength and VA is the Alfvén speed based on B0 and initial current sheet density. Our results could explain the intense electric field (~100mV/m) inside the secondary island observed in the Earth magnetosphere. Ex inside the secondary island is primarily balanced by the Hall term (j×B)/ne, while Ez is balanced by a combination of (j×B)/ne, -(vi×B) and divergence of electron pressure tensor with (j×B)/ne term dominates. This large Hall electric field is due to the large out-of-plane current density jy inside the island, which is mainly carried by accelerated electrons forming strong bulk flow in the -y direction. Ey shows bipolar structure across the island, with negative Ey corresponding to negative Bz and vice versa. It is balanced by (j×B)/ne and convective electric field. There are significant parallel electric fields, forming quadrupolar structure, inside the island with largest amplitude about 0.3B0VA.

Zhou, M.; Deng, X. H.; Huang, S. Y.

2012-04-01

375

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

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

376

The emission of biogenic sulphur gases from incubated Chinese paddy soil and its relationship with carbon dioxide  

Microsoft Academic Search

Biogeic sulphur gases emitted from terrestrial ecosystem may play an important role in the global sulphur cycle and have a profound influence on global climate change. In this paper, the emissions of volatile sulphur gases and carbon dioxide from incubated paddy soil were measured. The paddy soils were collected from Nanjing and Yangzhou, China. Six species of sulphur?containing gases were

Zhen Yang; Li Kong; Shiming Wang

1997-01-01

377

Mapping and modelling of greenhouse gas emissions from rice paddies with satellite radar observations and the DNDC biogeochemical model  

Microsoft Academic Search

Rice is an important agricultural production system with more than 80 million ha of irrigated rice paddies in annual production globally. As water resources become scarcer, the competition between urban development and agriculture for available water will intensify. Paddy rice cropland distribution and management intensity will need to evolve over the coming decades to accommodate increased production demand with decreasing

WILLIAM SALASa; Stephen Boles; Changsheng Li; Jagadeesh Babu Yeluripati; Xiangming Xiao; Steve Frolking; Pamela Green

2007-01-01

378

[On-farm conservation and utilization of paddy rice, wheat and maize landrace varieties in 15 unique ethnic groups in Yunnan, China].  

PubMed

On-farm conservation and utilization of crop landraces have been proposed as means of conserving plant germplasm, in contrast to ex situ germplasm conservation, but little is known about the effectiveness of this approach. This paper reports the findings from a survey conducted in 15 unique ethnic groups of the Yunnan Province on the conservation and utilization of paddy rice, wheat (including wheat, barley, oats, and rye) and maize landrace varieties through participatory rural appraisal (PRA) and questionnaires. The surveyed regions covered 306 villages (the village group) from 237 administrative villages in 124 towns (township) distributed in 36 counties of 11 prefectures (city) in Yunnan Province. The survey showed that 44.8%, 77.5%, and 37.3% of the visited villages had lost their paddy rice, wheat, and maize landraces, respectively. A total of 901 landraces were collected, including 371 rice, 119 wheat, and 411 maize varieties, respectively. There were 2.9 on-farm varieties on average per village, 3.3, 8.0 and 5.2 varieties on average per 100 households, 1 000 peasants and 100 Ha farmland areas, respectively. Among the 306 villages, two villages (Laomian and Qingkou) maintained the highest crop diversity with 18 varieties (including 10 rice and 8 maize varieties) and 14 paddy rice varieties. Also, on-farm varieties in different ethnic groups varied significantly from each other, ranging from 16 to 120 varieties per group. The diversity of paddy rice varieties was the highest, ranging from 1 to 72, and the diversity was mainly distributed in southern, southwest Yunnan of tropical, subtropical ethnic regions. The wheat varieties ranged from 0 to 47 and distributed in northern, northwest Yunnan of high altitude, temperature, and cold ethnic regions. The maize varieties ranged from 4 to 40. These patterns of variation in on-farm varieties are directly associated with traditional culture and custom for the ethnic minorities and reflect the lack of improved varieties for the local special environments. These findings confirm the role of on-farm conservation in plant genetic resources in China and provide baseline information for better on-farm conservation and utilization of plant germplasm in China. PMID:23208144

Xu, Fu-Rong; Yang, Ya-Yun; Zhang, En-Lai; A, Xin-Xiang; Tang, Cui-Feng; Dong, Chao; Zhang, Fei-Fei; Liu, Xu; Dai, Lu-Yuan

2012-11-01

379

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

PubMed

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

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

2003-10-16

380

C and N accumulations in soil aggregates determine nitrous oxide emissions from cover crop treated rice paddy soils during fallow season.  

PubMed

Combination of leguminous and non-leguminous plant residues are preferably applied in rice paddy soils to increase the rate of organic matter mineralization and to improve plant growth. However, organic matter addition facilitates methane (CH4) emission from rice paddy soil. Mineralization of organic nitrogen (N) increases NO3-N concentrations in soil, which are precursors for the formation of nitrous oxide (N2O). However, N2O is a minor greenhouse gas emitted from submerged rice field and hence is not often considered during calculation of total global warming potential (GWP) during rice cultivation. The hypothesis of this study was that fluxes of N2O emissions might be changed after removal of flooded water from rice field and the effect of cover crops on N2O emissions in the fallow season might be interesting. However, the effects of N-rich plant residues on N2O emission rates in the fallow season and its effect on annual GWP were not studied before. In this experiment, combination of barley (non-leguminous) and hairy vetch (leguminous) biomasses were applied at 9Mgha(-1) and 27Mgha(-1) rates in rice paddy soil. Cover crop application significantly increased CH4 emission flux while decreased N2O emissions during rice cultivation. The lowest N2O emission was observed in 27Mgha(-1) cover crop treated plots. Cover crop applications increased N contents in soil aggregates especially in smaller aggregates (<250?m), and that proportionately increased the N2O emission potentials of these soil aggregates. Fluxes of N2O emissions in the fallow season were influenced by the N2O emission potentials of soil aggregates and followed opposite trends as those observed during rice cultivation. Therefore, it could be concluded that the doses of cover crop applications for rice cultivation should not be optimized considering only CH4, but N2O should also be considered especially for fallow season to calculate total GWP. PMID:24880551

Pramanik, Prabhat; Haque, Md Mozammel; Kim, Sang Yoon; Kim, Pil Joo

2014-08-15

381

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

382

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

383

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

384

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...

385

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...

386

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...

387

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

NASA Technical Reports Server (NTRS)

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

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

1988-01-01