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1

[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

2

Paddy field, groundwater and land subsidence  

SciTech Connect

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

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

1995-12-31

3

Evaluation of the denitrification rate of terraced paddy fields  

NASA Astrophysics Data System (ADS)

SummaryRice is one of the most important staple foods in the world. Lowland paddy fields are well known for functioning as denitrification areas, but few studies have been conducted of paddy fields situated on hill slopes (terraced paddy fields). These terraced paddy fields have a characteristic artificial stepped shape, and this unique shape and periodic ponding from rice production may configure unique hydrological properties that might be different from lowland paddy fields. The shape and hydrological properties may also affect transport of nutrients such as nitrogen. This study is particularly focused on the denitrification rate in terraced paddy fields. To understand the hydrological properties of terraced paddy fields, a detailed water budget including the subsurface flow components was calculated. Combining the water budget components and chemical measurements of surface and subsurface water, a nitrogen budget was calculated. The results showed that about 10% of the total nitrogen input, mainly from fertilizers, was lost, suggesting the occurrence of denitrification in the area. The average denitrification rate of the study site was estimated at about 0.53-0.67 g N m-2 year-1. Spatial variations in the measured groundwater nitrate concentration suggest that denitrification is important in both the plough layer and the sloping area. The denitrification rate in the sloping area was estimated at 0.67-0.78 g N m-2 year-1, which is slightly higher than the estimates of denitrification rate in paddy lots, i.e., 0.56-0.61 g N m-2 year-1. The result indicates the importance of sloping areas for denitrification in terraced paddy fields.

Onishi, Takeo; Nakamura, Kimihito; Horino, Haruhiko; Adachi, Toru; Mitsuno, Toru

2012-05-01

4

Emission of Methyl halides from Japanese rice paddy fields.  

NASA Astrophysics Data System (ADS)

Rice paddy field is one of emission source of methyl halide (MeX: X = Cl, Br, I) which are concerned about stratospheric ozone depletion and enhanced aerosol formation. Although significant amounts of MeX which are estimated to be emitted from rice paddies affect to regional and global atmospheric environment, understandings and recent estimations of production and consumption mechanisms of MeX have large uncertainty with depending on environmental conditions. In this study, new flux data sets of MeX emissions from Japanese rice paddy fields were reported. The fluxes of MeX were compared with environmental data sets which included meteorological parameters (ambient air temperature, ambient MeX concentrations, humidity, solar irradiance), soil parameters (soil temperature, pH, redox potential, soil water contents) to understand the emission mechanisms of MeX. Gas fluxes of C2H4 were also measured, which indicate rice plants growth and ageing. Observations of MeX flux were conducted with using automated closed chamber sampling system in Tsukuba, Japan, during a cultivation season of rice from May 2005 to September 2005. Rice plants were cultivated under intermittent irrigation. Soil gases were collected manually by using evacuated 1L stainless canisters once a week and every 4 hours in certain day during this period. Other environmental parameters were automatically obtained every 10 minutes. Seasonal variation of gas emissions of C2H4 were observed in maximum tillering phase and heading phase. In addition, clearly diurnal flux trends of C2H4 depending on solar irradiance were observed. These results suggested rice plant was remarkably growing in these phase. Similarly, large amounts of gas emissions of MeBr and MeI were observed in the same phase. Diurnal flux trends of MeBr and MeI were associated with solar irradiance. Results were generally consistent with previous reports (Redeker et al., 2000). On the other hand, MeCl flux was increased in later periods than maximum periods of MeBr and MeI.

Komori, D.; Sudo, S.; Akiyama, H.; Nishimura, S.; Yagi, K.; Hayashi, K.; Tanaka, Y.; Yamada, K.; Toyoda, S.; Koba, K.; Yoshida, N.

2005-12-01

5

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

PubMed

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

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

2014-03-01

6

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

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

7

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

NASA Astrophysics Data System (ADS)

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

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

8

Effects of Agricultural Land Consolidation on Erosion Processes in Semi-Mountainous Paddy Fields of Japan  

Microsoft Academic Search

In semi-mountainous paddy fields of Japan, severe erosion occurs as a result of heavy rainfall or storm. In view of the considerable significance of agricultural land conservation for sustainable agriculture in semi-mountainous paddy fields, this study was conducted to show erosion phenomena and to consider the conservation effects of agricultural land consolidation which is carried out to make field sizes

Machito Mihara

1996-01-01

9

Nitrous oxide emissions in nonflooding period from fallow paddy fields.  

PubMed

The study was conducted to investigate the N2O emissions and dissolved N2O in the leachate during the nonflooding period in nongrowing paddy fields. Three kinds of paddy soils were repacked to soil columns and were supersaturated with water initially and dried gradually in a greenhouse to attain the N2O emissions flux during the incubation. Soils with the texture of silty clay-loam (Q and H) produced cracks during the drying of soil, but soil with the texture of silty loam (X) did not form the cracks. Cracked soils had similar amount of N2O emissions, and the mean N2O flux was 1,280.9 and 1,133.3 microg/(m2 x h) from Q and H soil, respectively, during the incubation; whereas the mean N2O flux from noncracked X soil was 426.3 microg/(m2 x h), i.e., significantly different from cracked soils. From cracked soils, the diurnal N2O emissions reached two peaks at 14:00 and 2:00, but such emissions peaked only at 2:00 from noncracked soil. The dissolved N2O concentrations in leachates from noncracked soil columns were greater than those from the cracked soil columns, and it indicated that the preferential flow might not affect the amounts of dissolved N2O in leachates during soil cracking. Supersaturated dissolved N2O in the leachate was potential source of N2O emissions. Fallow paddy fields have big risks of N2O emissions during nonflooding periods. PMID:19202873

Huang, Shuhui; Pant, Hari K; Lu, Jun

2008-01-01

10

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

PubMed Central

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

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

2013-01-01

11

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

12

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

Microsoft Academic Search

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

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

2004-01-01

13

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

14

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

NASA Astrophysics Data System (ADS)

Large quantities of radiocesium were deposited across a 3000 km2 area northwest of the Fukushima Dai-ichi nuclear power plant after the March 2011 accident. Although many studies have investigated the fate of radiocesium in soil in the months following the accident, the potential migration of this radioactive contaminant in rice paddy fields requires further examination after the typhoons that occurred in this region. Such investigations will help minimize potential human exposure in rice paddy fields or transfer of radioactive contaminants from soils to rice. Radionuclide activity concentrations and organic content were analysed in 10 soil cores sampled from paddy fields in November 2013, 20 km north of the Fukushima power plant. Our results demonstrate limited depth migration of radiocesium with the majority concentrated in the uppermost layers of soils (< 5 cm). More than 30 months after the accident, 81.5 to 99.7% of the total 137Cs inventories was still found within the < 5 cm of the soil surface, despite cumulative rainfall totalling 3300 mm. Furthermore, there were no significant correlations between radiocesium migration depth and total organic carbon content. We attributed the maximum depth penetration of 137Cs to maintenance (grass cutting - 97% of 137Cs in the upper 5 cm) and farming operations (tilling - 83% of 137Cs in the upper 5 cm). As this area is exposed to erosive events, ongoing decontamination works may increase soil erodibility. We therefore recommend the rapid removal of the uppermost - contaminated - layer of the soil after removing the vegetation to avoid erosion of contaminated material during the subsequent rainfall events. Remediation efforts should be concentrated on soils characterised by radiocesium activities > 10 000 Bq kg-1 to prevent the contamination of rice. Further analysis is required to clarify the redistribution of radiocesium eroded on river channels.

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

2014-09-01

15

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

Microsoft Academic Search

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

D. Hocking; K. Islam

1995-01-01

16

Metabolic degradation of imidacloprid in paddy field soil.  

PubMed

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

Akoijam, Romila; Singh, Balwinder

2014-10-01

17

[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

18

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

PubMed

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

Fernandes, J C; Henriques, F S

1990-01-01

19

Ammonia volatilization losses from paddy fields under controlled irrigation with different drainage treatments.  

PubMed

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

He, Yupu; Yang, Shihong; Xu, Junzeng; Wang, Yijiang; Peng, Shizhang

2014-01-01

20

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

PubMed Central

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

He, Yupu; Yang, Shihong; Wang, Yijiang

2014-01-01

21

Measuring and modeling the temporal dynamics of nitrogen balance in an experimental-scale paddy field  

NASA Astrophysics Data System (ADS)

Nitrogen balance involves many mechanisms and plays an important role to maintain the function of nature. Fertilizer application in agriculture activity is usually seen as a common and significant nitrogen input to environment. Improper fertilizer application on paddy field can result in great amount of various types of nitrogen losses. Hence, it is essential to understand and quantify the nitrogen dynamics in paddy field for fertilizer management and pollution control. In this study, we develop a model which considers major transformation processes of nitrogen (e.g. volatilization, nitrification, denitrification and plant uptake). In addition, we measured different types of nitrogen in plants, soil and water at plant growth stages in an experimental-scale paddy field in Taiwan. The measurement includes total nitrogen in plants and soil, and ammonium-N (NH4+-N), nitrate-N (NO3--N) and organic nitrogen in water. The measured data were used to calibrate the model parameters and validate the model for nitrogen balance simulation. The results showed that the model can accurately estimate the temporal dynamics of nitrogen balance in paddy field during the whole growth stage. This model might be helpful and useful for future fertilizer management and pollution control in paddy field.

Tseng, C.; Lin, Y.

2013-12-01

22

Delineating water management zones in a paddy rice field using a Floating Soil Sensing System  

Microsoft Academic Search

Paddy rice fields are kept inundated during most of the growing period. This requirement is challenging to achieve because of the lack of suitable technologies to detect rapidly percolation prone zones within these fields. The objective of this study was to evaluate a methodology to identify water leakage areas to support precision soil–water management at a within-field level. Therefore, a

Mohammad Monirul Islam; Timothy Saey; Eef Meerschman; Philippe De Smedt; Fun Meeuws; Ellen Van De Vijver; Marc Van Meirvenne

2011-01-01

23

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

PubMed

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

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

2014-05-15

24

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

Microsoft Academic Search

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 182807 to 242298 ha of paddy field in the first crop season ranged from 8062 to 12066 ton, and it was between 16261 and 25007 ton for

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

2003-01-01

25

Succession and phylogenetic composition of eubacterial communities in rice straw during decomposition on the surface of paddy field soil  

Microsoft Academic Search

To estimate the bacterial communities in rice straw left on the soil surface of paddy fields, polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis was conducted. Rice straw samples were placed on the soil surface in a Japanese paddy field under drained conditions after harvest and under flooded conditions after the transplanting of rice. The residual samples on the soil

Naoko Asari; Rie Ishihara; Yasunori Nakajima; Makoto Kimura; Susumu Asakawa

2007-01-01

26

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

NASA Astrophysics Data System (ADS)

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

Sander, Till; Gerke, Horst H.

2009-02-01

27

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

PubMed

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

Sander, Till; Gerke, Horst H

2009-02-16

28

Estimation of soil moisture in paddy field using Artificial Neural Networks  

E-print Network

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

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

2013-01-01

29

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

Microsoft Academic Search

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

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

2010-01-01

30

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

31

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

NASA Astrophysics Data System (ADS)

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

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

32

[Research on vertical distribution pattern and reserve of organic carbon in paddy field soil of Qianguo, Jilin].  

PubMed

Taking Qianguo paddy field of Jilin Province as investigation object, based on the soil test data of 7 different periods developed for 4 to 55 years, the vertical distribution of SOC content in the 1 m paddy field section was studied adopting the space scale method instead of time scale. The paddy soil carbon sink in last 20 years was discussed and the organic carbon storage of Qianguo paddy field soil was estimated. According to the second soil census data, the characteristics of soil SOC used in fields of different type were comparatively analyzed. The results showed that the paddy field SOC decreased from top to bottom by layer, which showed an increasing trend with the increase of development age; the organic carbon content in the surface soil layer (0-30 cm) (1 820.79 t) was 46.87% of the total organic carbon storage in deep soil (3 885.05 t), and the soil SOCD content was highly different depending on the type of field, ranked in descending order as paddy field, dry land, and saline field. The development of paddy field is a SOC accumulating carbon sink process, which is conducive to the transfer of organic carbon from the surface soil layer to the bottom soil layer. PMID:24028014

Tang, Jie; Zhang, Wen-Hui; Li, Zhao-Yang; Zhang, Nan; Hu, Meng

2013-07-01

33

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

PubMed

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

Kouzuma, Atsushi; Kaku, Nobuo; Watanabe, Kazuya

2014-12-01

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

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

36

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

NASA Astrophysics Data System (ADS)

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

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

37

A floating sensing system to evaluate soil and crop variability within flooded paddy rice fields  

Microsoft Academic Search

Continuous paddy rice cultivation requires fields to be flooded most of the time limiting seriously the collection of detailed\\u000a soil information. So far, no appropriate soil sensor technology for identifying soil variability of flooded fields has been\\u000a reported. Therefore, the primary objective was the development of a sensing system that can float, acquire and process detailed\\u000a geo-referenced soil information within

Mohammad Monirul Islam; Liesbet Cockx; Eef Meerschman; Philippe De Smedt; Fun Meeuws; Marc Van Meirvenne

38

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

Microsoft Academic Search

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

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

2011-01-01

39

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

40

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

PubMed

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

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

2013-10-01

41

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

42

Heavy metal contamination of paddy soils and rice (Oryza sativa L.) from Kocani Field (Macedonia).  

PubMed

This research focuses on the heavy metal contamination of the paddy soils and rice from Kocani Field (eastern Macedonia) resulting from irrigation by riverine water impacted by past and present base-metal mining activities and acid mine drainage. Very high concentrations of As, Cd, Cu, Pb and Zn were found in the paddy soils (47.6, 6.4, 99, 983 and 1,245 microg g(-1)) and the rice (0.53, 0.31, 5.8, 0.5 and 67 microg g(-1)) in the western part of Kocani Field, close to the Zletovska River, which drains the mining facilities of the Pb-Zn mine in Zletovo. In terms of health risk, the observed highest concentrations of these elements in the rice could have an effect on human health and should be the subject of further investigations. PMID:18777118

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

2009-08-01

43

Investigation of possible horizontal gene transfer from transgenic rice to soil microorganisms in paddy rice field.  

PubMed

In order to monitor the possibility of horizontal gene transfer between transgenic rice and microorganisms in paddy rice field, the gene flow from bifunctional fusion (TPSP) rice containing trehalose-6-phosphate synthase and phosphatase to microorganisms in soils was investigated. The soil samples collected every month from the paddy rice field during June, 2004 to March, 2006 were investigated by multiplex PCR, Southern hybridization, and amplified fragment length polymorphism (AFLP). The TPSP gene from soil genomics DNAs was not detected by PCR. Soil genomic DNAs were not shown its homologies on the Southern blotting data, indicating that gene-transfer did not occur during the last two years in paddy rice field. In addition, the AFLP band patterns produced by both soil genomic DNAs extracted from transgenic and non-transgenic rice field appeared similar to each other when analyzed by NTSYSpc program. Thus, these data suggest that transgenic rice does not give a significant impact on the communities of soil microorganisms although long-term observation may be needed. PMID:20134251

Kim, Sung Eun; Moon, Jae Sun; Kim, Jung Kyu; Choi, Won Sik; Lee, Sang Han; Kim, Sung Uk

2010-01-01

44

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

45

Cyanobacterial communities of rice straw left on the soil surface of a paddy field  

Microsoft Academic Search

To estimate diversity, seasonal variation, and phylogeny of the cyanobacterial communities in rice straw placed in nylon mesh\\u000a bags and left on the soil surface of a paddy field, total DNA was extracted from straw, amplified by polymerase chain reaction\\u000a targeting 16S rRNA genes of cyanobacteria, and the amplicons were separated by denaturing gradient gel electrophoresis (DGGE).\\u000a These DGGE bands

Naoko Asari; Rie Ishihara; Yasunori Nakajima; Makoto Kimura; Susumu Asakawa

2008-01-01

46

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

PubMed

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

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

2014-07-01

47

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

Microsoft Academic Search

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

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

2009-01-01

48

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

49

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

50

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

51

Analysis of the spatial variation in the net ecosystem production of rice paddy fields using the diagnostic biosphere model BEAMS  

NASA Astrophysics Data System (ADS)

To realistically understand spatial and temporal variations in the net ecosystem production (NEP) of rice paddies in Japan, we enhanced the existing diagnostic-type biosphere model with the addition of agricultural processes. Validated with a comparison of seasonal and annual variations over 5 years, the NEP estimations bore good agreement with the measurements. In regional-scale analyses, we targeted all rice paddy fields in Japan from January 2001 to December 2009. Before and after the model enhancement, the NEP showed very different spatial variations and absolute values, suggesting that the most effective improvements were the introduction of harvest and soil oxidation-reduction processes. In annual anomaly analyses covering a 9-year period, the NEP was found to be negative in 2003 and 2006 (-0.11 and -0.25 TgC/year) and positive in 2004 and 2007 (+0.02 and +0.21 TgC/year). We found that the negative values were caused by decreases in solar radiation and air temperature and the positive values were caused by increases in these two parameters and precipitation. In response to the NEP, our obtained harvested grain biomass values in 2003 and 2006 were lower than usual. The results were in good agreement with the results from reports of the Japan Meteorological Agency and the Ministry of Agriculture, Forestry, and Fisheries.

Sasai, T.; Nakai, S.; Setoyama, Y.; Ono, K.; Kato, S.; Mano, M.; Miyata, A.; Saigusa, N.; Nemani, R. R.; Nasahara, K. N.

2012-12-01

52

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

PubMed Central

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

2011-01-01

53

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

54

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

55

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

PubMed Central

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

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

2013-01-01

56

Kinetics of degradation and adsorption-desorption isotherms of thiobencarb and oxadiargyl in calcareous paddy fields.  

PubMed

Herbicides are an important source of contamination in paddy fields. Monitoring their fate and chemical interactions is therefore imperative for sustaining the environment and human health. To meet this purpose, field experiments were conducted to investigate kinetics of thiobencarb and oxadiargyl dissipation in soil and water of two paddy fields. Their adsorption and desorption isotherms were also determined in the soil samples. Variation in concentration was monitored for 60d in soil solution phase and for 315d in soil solid phase. In soil solution, concentrations of both herbicides were rapidly reduced within 5d and reached steady state within 20-30d. Analysis of experimental data resolved a half-life ?2-4d for both herbicides. In soil solid phase, adsorption reaction played a dominant role in the first 10d. Afterwards, degradation reactions regulated the process. Variation in concentration was minimized after about 150d for thiobencarb and 80d for oxadiargyl. The half-lives were calculated ?50d for thiobencarb and ?20d for oxadiargyl, indicating that association with soil particles protect them effectively against degradation reactions. Adsorption isotherms confirmed that both herbicides were strongly adsorbed on soil particles. Furthermore, desorption data indicated that after four successive desorption steps, less than 9% thiobencarb and 1% oxadiargyl were released. This denotes that electrolyte ions in solution cannot adequately compete with and replace adsorbed thiobencarb and oxadiargyl molecules. This would lead to a considerable hysteresis between adsorption and desorption isotherms as was observed experimentally. Overall, it was concluded that both herbicides are among non-persistent and immobile herbicides in the paddy soils. PMID:23461836

Mahmoudi, Mojtaba; Rahnemaie, Rasoul; Es-haghi, Ali; Malakouti, Mohammad J

2013-05-01

57

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

PubMed

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

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

2014-01-01

58

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

59

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

Microsoft Academic Search

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

Asumi Nakamura; ChoCho Tun; Susumu Asakawa; Makoto Kimura

2003-01-01

60

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

E-print Network

Temporal variations in arsenic uptake by rice plants in Bangladesh: The role of iron plaque in paddy fields irrigated with groundwater J.-M. Garnier a, , F. Travassac a , V. Lenoble a,b , J. Rose May 2010 Available online xxxx Keywords: Arsenic Rice (Oryza sativa) Paddy soil Soil water Iron plaque

van Geen, Alexander

61

Soil type-depending effect of paddy management: Organic carbon distribution and stocks  

NASA Astrophysics Data System (ADS)

Paddy soils may originate from many different types of soil but are highly modified by human activities. These soils are mostly managed under submerged conditions, a management which is assumed to favour carbon sequestration. Therefore, the present study aims to investigate the impact of paddy management on soil organic carbon distributions and stocks in major soil types that are typically used for rice cultivation in Asia. Fluvisol and Acrisol sites (sub-tropical monsoon climate, PR China) as well as Andosol, Vertisol and Ferralsol sites (tropical climate of Java, Indonesia) were compared, as they represent a large range of soil properties to be expected in Asian paddy fields. Paddy rice at all of these sites is cultivated under flooded conditions followed by an upland crop. To evaluate the impact of paddy management, paddy soils as well as adjacent agricultural soils which are not used for paddy rice production (non-paddy soils) were chosen. At each site, three soil profiles of paddy and non-paddy soils were sampled horizontally. All samples were analysed for bulk density and organic carbon (OC) concentrations, and the corresponding OC stocks were calculated. Paddy soils derived from Fluvisols and Acrisols(PR China) showed clearly higher OC concentrations in the topsoils, leading to higher cumulative OC stocks in paddy soils compared to the respective non-paddy soils. However, other soil types did not show the expected higher OC sequestration under paddy management. For example, paddy soils derived from Ferralsols and Vertisols of Java are characterised by very similar OC concentrations and OC stocks as compared to their respective non-paddy soils. Also paddy and non-paddy soils derived from Andosols (Java) showed similar OC concentrations and depth distributions; only the slightly higher bulk density values under paddy management lead to slightly higher OC stocks in these soils. As clearly shown by our results, we cannot necessarily assume that rice production under submerged conditions always leads to enhanced carbon sequestration. We conclude that not only the soil type, but also the climate region may control the mechanisms of OC accumulation and the impact of management on OC stocks and distributions.

Kölbl, Angelika; Drechsler, Susanne; Wissing, Livia; Schad, Peter; Rahayu Utami, Sri; Cao, Zhihong; Kögel-Knabner, Ingrid

2013-04-01

62

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

NASA Astrophysics Data System (ADS)

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

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

2011-09-01

63

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

PubMed Central

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

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

2012-01-01

64

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

65

Exchange of carbonyl sulfide (OCS) and dimethyl sulfide (DMS) between rice paddy fields and the atmosphere in subtropical China  

Microsoft Academic Search

Carbonyl sulfide (OCS) and dimethyl sulfide (DMS) are important trace gases contributing to sulfate aerosol formation in the lower and upper atmosphere and hence greatly impacting global radiative balance. In the present study the exchange of OCS and DMS between rice (Oryza sativa L.) paddy fields and the atmosphere was studied in subtropical China from November 2004 to July 2005.

Zhigang Yi; Xinming Wang; Guoying Sheng; Jiamo Fu

2008-01-01

66

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

67

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

68

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

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

69

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

PubMed

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

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

2015-01-01

70

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

PubMed

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

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

2007-05-01

71

Dissipation and residues of emamectin benzoate study in paddy under field conditions.  

PubMed

The objective of this experiment was not only to provide a simple residue analytical method to evaluate the safe application rate of Emamectin Benzoate for paddy crops but also to give a suitable recommended dosage in paddy crops. Paddy samples were detected using HPLC-MS/MS. The half-lives of emamectin benzoate in paddy plants, water and soil were 2.04-8.66 days, 2.89-4.95 days and 3.65-5.78 days with a dissipation rate of 90% over 7 days after application, respectively. Low residues and short half-life suggested that Emamectin Benzoate could be safely used in paddy crops with the suitable dosage and application. PMID:21928147

Li, Minghui; Chen, Weitao; Li, Mengyi; Han, Lijun

2011-12-01

72

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

PubMed Central

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

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

2014-01-01

73

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

PubMed

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

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

2014-11-01

74

Major and trace elements in paddy soil contaminated by Pb–Zn mining: a case study of Ko?ani Field, Macedonia  

Microsoft Academic Search

The objective of this study was to assess the bulk chemical composition as well as the extent and severity of heavy metal\\u000a contamination in the paddy soil of Ko?ani Field (eastern Macedonia). The results revealed that the paddy soil of the western\\u000a part of Ko?ani Field is severely contaminated with Pb, Zn, As and Cd in the vicinity of the

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

2007-01-01

75

Dynamics of methanogenic archaeal communities based on rRNA analysis and their relation to methanogenic activity in Japanese paddy field soils  

Microsoft Academic Search

We investigated the relationships between dynamics of methanogenic archaeal communities and methanogenic activities in Japanese paddy field soils by reverse transcription-PCR-denaturing gradient gel electrophoresis (RT-PCR-DGGE) and real-time PCR targeting 16S rRNA gene (16S rDNA) and 16S rRNA. The investigated paddy fields were managed on a double-cropping system, where rice was cultivated under flooded conditions in summer and wheat was cropped

Takeshi Watanabe; Makoto Kimura; Susumu Asakawa

2007-01-01

76

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

77

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

PubMed

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

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

2011-04-01

78

[Control effects of rice-duck farming and other weed management strategies on weed communities in paddy fields].  

PubMed

By the methods of community ecology, field studies were conducted to evaluate the control effects of three weed management strategies, i. e., rice-duck farming (RD), manual weeding (MW) and chemical weeding (CW), on the weed communities in paddy fields. The results showed that under rice-duck farming, the weed density in paddy fields decreased significantly, and the control effects on dominant weed species such as Monochoria vaginalis, Cyperus difformis, Sagittaria pygmaea were all above 95%, with an overall effect higher than CW and MW. Under RD, the species richness and Shannon-Wiener diversity indices decreased slightly, while Pielou community evenness indices increased markedly, indicating that the species composition of weed community was greatly improved, and the infestation of former dominant weed species was reduced. The structure of weed communities in paddy fields varied with different weed management strategies, e. g., under RD, Lindernia procumbens, Cyperus difformis and Fimbristylis miliacea constituted the major weed community, and the Whittaker index was significant higher than that of CW, MW and CK, which indicated that rice-duck farming had a greater effect on the structure of the weed communities. The same conclusion could be drawn from Sorensen's similarity indices and cluster analysis with Sorensen's index as the distance measurement. PMID:16180755

Wei, Shouhui; Qiang, Sheng; Ma, Bo; Wei, Jiguang; Chen, Jianwei; Wu, Jianqiang; Xie, Tongzhou; Shen, Xiaokun

2005-06-01

79

Farmers’ response to agricultural drought in paddy field of southern China: a case study of temporal dimensions of resilience  

Microsoft Academic Search

Seasonal water scarcity in southern China has been an issue of concern for many years. The increased frequency of low precipitation\\u000a in the growing season of rice created a flurry of discussions in the academic and policy arenas. These events severely disrupted\\u000a the supply of irrigation water for agriculture in paddy field areas and posed a substantial threat to farmers’

Yehong Sun; Hongjian Zhou; Jing’ai Wang; Yi Yuan

80

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

Microsoft Academic Search

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

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

2009-01-01

81

Distribution and mobility of heavy metals in paddy soils of the Ko?ani Field in Macedonia  

Microsoft Academic Search

Contamination of soils with heavy metals is widespread and poses a long-term risk to ecosystem health. Abandoned and active\\u000a mining sites contain residues from ore-processing operations that are characterised by high concentrations of heavy metals.\\u000a The distribution and mobility characteristics of heavy metals (As, Cd, Cu, Pb, and Zn) in paddy soil samples from Ko?ani Field\\u000a (Macedonia) using ICP-EAS and

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

2010-01-01

82

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

PubMed

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

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

2007-02-01

83

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

PubMed

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

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

2014-04-01

84

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

85

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

86

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. PMID:22446309

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

2012-01-01

87

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

88

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

89

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

90

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

91

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

PubMed

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

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

2009-10-01

92

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

93

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

94

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

PubMed

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 approximately 130microgl(-1) As and two control sites irrigated with water containing <15microgl(-1) As. At both sites irrigated with contaminated water, As concentrations in soil water increased from <10microgl(-1) to >1000microgl(-1) during the first five weeks of the growth season and then gradually declined to <10microgl(-1) during the last five weeks. At the two control sites, concentrations of As in soil water never exceeded 40microgl(-1). At both contaminated sites, the As content of roots and Fe plaque rose to 1000-1500mgkg(-1) towards the middle of the growth season. It then declined to approximately 300mgkg(-1) towards the end, a level still well above As concentration of approximately 100mgkg(-1) 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 significantly limits the 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, needs to be better understood because they are likely to influence the uptake of As in rice grains. PMID:20576285

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

2010-09-01

95

Homologous expression of cytosolic dehydroascorbate reductase increases grain yield and biomass under paddy field conditions in transgenic rice (Oryza sativa L. japonica).  

PubMed

Dehydroascorbate reductase (DHAR, EC 1.8.5.1) maintains redox pools of ascorbate (AsA) by recycling oxidized AsA to reduced AsA. To investigate whether DHAR affects rice yield under normal environmental conditions, cDNA-encoding DHAR (OsDHAR1) was isolated from rice and used to develop OsDHAR1-overexpressing transgenic rice plants, under the regulation of a maize ubiquitin promoter. Incorporation and expression of the transgene in transgenic rice plants was confirmed by genomic polymerase chain reaction (PCR), semi-quantitative reverse transcription PCR (RT-PCR), western blot, and enzyme activity. The expression levels were at least twofold higher in transgenic (TG) rice plants than in control wild-type (WT) rice plants. In addition, OsDHAR1-overexpression in seven-independent homologous transgenic plants, as compared to WT plants, increased photosynthetic capacity and antioxidant enzyme activities under paddy field conditions, which led to an improved AsA pool and redox homeostasis. Furthermore, OsDHAR1 overexpression significantly improved grain yield and biomass due to the increase of culm and root weights and to enhance panicle and spikelet numbers in the same seven independent TG rice plants during the farming season (2010 and 2011) in South Korea. The OsDHAR protein contained the redox-active site (Cys20), as well as the conserved GSH-binding region, GSH-binding motif, glutathione-S-transferase (GST) N-terminal domain, C-terminal domain interface, and GST C-terminal domain. Therefore, our results indicate that OsDHAR1 overexpression, capable of functioning in AsA recycling, and protein folding increases environmental adaptation to paddy field conditions by the improving AsA pool and redox homeostasis, which enhances rice grain yield and biomass. PMID:23519921

Kim, Young-Saeng; Kim, Il-Sup; Bae, Mi-Jung; Choe, Yong-Hoe; Kim, Yul-Ho; Park, Hyang-Mi; Kang, Hong-Gyu; Yoon, Ho-Sung

2013-06-01

96

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

PubMed Central

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

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

2013-01-01

97

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

PubMed

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

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

2011-11-01

98

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

99

Assessment of factors influencing groundwater-level change using groundwater flow simulation, considering vertical infiltration from rice-planted and crop-rotated paddy fields in Japan  

NASA Astrophysics Data System (ADS)

Assessing factors that influence groundwater levels such as land use and pumping strategy, is essential to adequately manage groundwater resources. A transient numerical model for groundwater flow with infiltration was developed for the Tedori River alluvial fan (140 km2), Japan. The main water input into the groundwater body in this area is irrigation water, which is significantly influenced by land use, namely paddy and upland fields. The proposed model consists of two models, a one-dimensional (1-D) unsaturated-zone water flow model (HYDRUS-1D) for estimating groundwater recharge and a 3-D groundwater flow model (MODFLOW). Numerical simulation of groundwater flow from October 1975 to November 2009 was performed to validate the model. Simulation revealed seasonal groundwater level fluctuations, affected by paddy irrigation management. However, computational accuracy was limited by the spatiotemporal data resolution of the groundwater use. Both annual groundwater levels and recharge during the irrigation periods from 1975 to 2009 showed long-term decreasing trends. With the decline in rice-planted paddy field area, groundwater recharge cumulatively decreased to 61 % of the peak in 1977. A paddy-upland crop-rotation system could decrease groundwater recharge to 73-98 % relative to no crop rotation.

Iwasaki, Yumi; Nakamura, Kimihito; Horino, Haruhiko; Kawashima, Shigeto

2014-12-01

100

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

101

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

102

Trace analysis of pesticides in paddy field water by direct injection using liquid chromatography–quadrupole-linear ion trap-mass spectrometry  

Microsoft Academic Search

A multiresidue method was developed for the quantification and confirmation of 70 pesticides in paddy field water. After its filtration, water was injected directly in a liquid chromatograph coupled to a hybrid triple quadrupole-linear ion trap-mass spectrometer (QqLIT). The list of target analytes included organophosphates, phenylureas, sulfonylureas, carbamates, conazoles, imidazolinones and others compounds widely used in different countries where rice

Lucía Pareja; M. J. Martínez-Bueno; Verónica Cesio; Horacio Heinzen; A. R. Fernández-Alba

2011-01-01

103

Avian diversity and feeding guilds in a secondary forest, an oil palm plantation and a paddy field in riparian areas of the kerian river basin, perak, malaysia.  

PubMed

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

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

2011-12-01

104

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

105

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

PubMed

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

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

2014-05-15

106

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

NASA Astrophysics Data System (ADS)

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

Zhang, Xuan; Zhao, Yongqing; Xu, Cailing

2014-03-01

107

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

108

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

PubMed

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

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

2014-12-01

109

Effects of indigenous arbuscular mycorrhizal fungi in paddy fields on rice growth and N, P, K nutrition under different water regimes  

Microsoft Academic Search

A pot experiment was conducted under two soil conditions, namely (i) Original paddy soil and (ii) Diluted soil (paddy soil diluted with andosol subsoil; Paddy soil: Andosol subsoil=1:4) to investigate the effects of arbuscular mycorrhizal fungi (AMF) and water regimes on dry matter production, grain yield, AMF colonization, AMF sporulation, and mineral nutrition of wetland rice (Oryza sativa L.). Plants

Mohammad Zakaria Solaiman; Hiroshi Hirata

1995-01-01

110

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

Microsoft Academic Search

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

D. Hocking; K. Islam

1994-01-01

111

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

112

Arsenic Behavior in Paddy Fields during the Cycle of Flooded and  

E-print Network

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

113

Infiltration process and groundwater table raising in a paddy field area  

Microsoft Academic Search

The water coming from the soil surface after the saturation of the soil stratum over the groundwater table at field saturation raises the groundwater level. The soil structure and the soil texture characterize the infiltration process. The resultant of the gravitational force and the capillary forces gives the energy to the water molecules to push the entrapped air out of

Mauro Greppi

2004-01-01

114

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

115

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

PubMed Central

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

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

2014-01-01

116

Net ecosystem exchange, gross primary production, and ecosystem respiration of carbon dioxide during barley growing season in rice-barley paddy field of Korea  

NASA Astrophysics Data System (ADS)

This study was conducted to measure carbon dioxide exchange between customarily cultivated rice-barley double cropping paddy field and the atmosphere during barley growing season (October 2012 and June 2013) and to estimate carbon dioxide fluxes using agro-meteorological factors (temperature, net radiation etc. ) and barley biomass. The carbon dioxide fluxes were quantified by eddy covariance technique in paddy fields with rice-barley double cropping system, located at the Gimje flux site in the southwestern coast of Korea. The total values of net ecosystem carbon dioxide exchange (NEE), gross primary production (GPP), and ecosystem respiration (Re) were -100.6, 782.7, and 682.5 g C m-2 during barley growing season, respectively. The NEE was tended to keep between 0 and 5 g C m-2 d-1 from sowing date (Oct. 21, 2012) to winter rest stage (Dec. 3, 2012 to Feb. 22, 2013), and gradually decreased in tillering stage (Feb. 23, 2013 to May 5, 2013) with its maximum around heading date, and then started to increase in ripening stage (May 6, 2013 to Jun. 8, 2013). The soil temperature was strongly correlated with the Re (r2=0.86), while the net radiation showed the weak relationship with the GPP during the emergence, seedling, and winter rest stage. The aboveground biomass of barley was significantly correlated with the values of NEE (r2=0.79), GPP (r2=0.83), and Re (r2=0.77), respectively.

Jung, M.; Shim, K.; Min, S.; Kim, Y.; Kim, S.; So, K.

2013-12-01

117

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

PubMed Central

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

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

2012-01-01

118

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

PubMed Central

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

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

2014-01-01

119

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

PubMed

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

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

2014-01-01

120

[Effects of different organic manure sources and their combinations with chemical fertilization on soil nematode community structure in a paddy field of East China].  

PubMed

A comparative study was conducted to investigate the effects of different fertilization modes on the soil nematode community structure in a paddy field with paddy rice and wheat rotation in Jintan County (31 degrees 39'41.8" N, 119 degrees 28'23.5" E) of Jiangsu Province, East China. Six treatments were installed, i. e., no fertilization (CK), 100% chemical NPK fertilization (F), pig manure compost plus 50% chemical fertilization (PF), straw returning plus 100% chemical fertilization (SF), pig manure compost and straw returning plus 50% chemical fertilization (PSF), and application of commercial pig manure-inorganic complex fertilizer (PMF). The soil samples were collected from the field after the paddy rice harvested in autumn. The two continuous years study showed that the soil nematode community structure varied with fertilization treatments and years. The combined application of chemical fertilizers and organic manures increased the total number of soil nematodes, decreased the abundance of soil bacterivorous nematodes, and made the abundance of predator- and omnivore nematodes increased significantly. No significant differences were observed in the abundance of soil fungivorous nematodes among all the treatments. Chemical fertilization alone and the application of commercial pig manure-inorganic complex fertilizer had no obvious suppression effect on the soil phytophagous nematodes. The abundance of soil bacteriavorous nematodes under the combined application of chemical fertilizers and organic manures was relatively increased in the second year, as compared with that in the first year, while the abundance of soil phytophagous nematodes (Hirschmanniella) was relatively decreased in the second year. From the aspect of nematode ecological indices, the Margalef diversity index (H) under the combined application of chemical fertilizers and organic manures in the second year had an increasing trend, while the NCR index had less change. The Wasilewka index had a relative increase in the second year, while the plant-parasitic index had a relative decrease. It was suggested that the application of organic manure could increase the abundance of soil microbivorous nematodes, and made the soil environment tend to be healthy. PMID:24697072

Liu, Ting; Ye, Cheng-Long; Chen, Xiao-Yun; Ran, Wei; Shen, Qi-Rong; Hu, Feng; Li, Hui-Xin

2013-12-01

121

Gaseous emissions from flooded rice paddy agriculture  

NASA Astrophysics Data System (ADS)

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

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

2003-07-01

122

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

PubMed

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

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

2014-01-01

123

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

124

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

PubMed

Plants have mutualistic symbiotic relationships with rhizobia and fungi by the common symbiosis pathway, of which Ca(2+)/calmodulin-dependent protein kinase (encoded by CCaMK) is a central component. Although Oryza sativa CCaMK (OsCCaMK) is required for fungal accommodation in rice roots, little is known about the role of OsCCaMK in rice symbiosis with bacteria. Here, we report the effect of a Tos17-induced OsCCaMK mutant (NE1115) on CH4 flux in low-nitrogen (LN) and standard-nitrogen (SN) paddy fields compared with wild-type (WT) Nipponbare. The growth of NE1115 was significantly decreased compared with that of the WT, especially in the LN field. The CH4 flux of NE1115 in the LN field was significantly greater (156 to 407% in 2011 and 170 to 816% in 2012) than that of the WT, although no difference was observed in the SN field. The copy number of pmoA (encodes methane monooxygenase in methanotrophs) was significantly higher in the roots and rhizosphere soil of the WT than in those of NE1115. However, the mcrA (encodes methyl coenzyme M reductase in methanogens) copy number did not differ between the WT and NE1115. These results were supported by a (13)C-labeled CH4-feeding experiment. In addition, the natural abundance of (15)N in WT shoots (3.05‰) was significantly lower than in NE1115 shoots (3.45‰), suggesting greater N2 fixation in the WT because of dilution with atmospheric N2 (0.00‰). Thus, CH4 oxidation and N2 fixation were simultaneously activated in the root zone of WT rice in the LN field and both processes are likely controlled by OsCCaMK. PMID:24441161

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

2014-03-01

125

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

PubMed Central

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

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

2014-01-01

126

Mercury cycling in a flooded rice paddy  

NASA Astrophysics Data System (ADS)

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

Rothenberg, Sarah E.; Feng, Xinbin

2012-09-01

127

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

NASA Astrophysics Data System (ADS)

The environmental mobilization characteristics of Hg were investigated in a rice paddy field in the Hari district of Kang Hwa Island, Korea during two field campaigns held in late March 2001 and late April 2002. In the course of these two field campaigns, we measured the concentration, concentration gradients (between two different heights of 1 and 5 m), and fluxes of Hg with the aid of micrometeorological approaches. The results of our experiments consistently indicate that the study area behaved as both source and sink of Hg, yielding a net emission rate of 183 (1st) to 28 ng m-2 h-1 (2nd campaign). It was however found that the soil-air exchange patterns of Hg during the two study periods, although investigated in similar seasonal cycles, contrast to a large extent. Upward emission prevailed in both the frequency and magnitude during the 1st study period, but dry deposition was seen more dominantly in terms of frequency during the 2nd study period. In light of the fact that the occurrence patterns of Asian Dust events differed greatly between the two study periods, the possible role of long-range transport of airborne pollutants (LRTAP) as sources of Hg into the study area has also been examined using information on air mass movement patterns. Because observed differences in Hg flux patterns generally reflect changes in environmental conditions across study periods, the bi-directional exchange patterns of Hg during the two field campaigns were explained in relation to highly diverse environmental conditions that persisted in each study period.

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

2003-10-01

128

Influence of nitrogen loading and plant nitrogen assimilation on nitrogen leaching and N2O emission in forage rice paddy fields fertilized with liquid cattle waste.  

PubMed

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

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

2015-04-01

129

Quantification and modelling of water flow in rain-fed paddy fields in NE Thailand: Evidence of soil salinization under submerged conditions by artesian groundwater  

NASA Astrophysics Data System (ADS)

SummaryWater flow and solute transport in soils forms an essential part in many groundwater hydrology studies. This is especially true for Northeast Thailand, where the agricultural land is affected by the soil salinity, which is a widespread and an increasing phenomenon affecting 25% of the agricultural land. Salinization appears as scattered discrete patches of 10-100 m2 in the lowlands, illustrated by white efflorescences during the dry season and bare soil during the cropping season. A field study was undertaken in farm plots to measure the water flow and solute transport within the soil surface and the vadose zone, both inside and outside a saline patch. The water flow was measured on the soil surface with lysimeters and infiltration rings, and was derived in the soil from the hydraulic gradients measured with tensiometers placed at different depths. The salt transport was evaluated with water traps also placed at different depths, where the soil water's electrical conductivity was measured throughout the rainy season. Field study results demonstrated that the accumulation of saline solutions in rain fed paddy fields, occurred mainly during the rainy season while the soil surface remained flooded. During this period the saline water table rose towards the soil surface independently of infiltration into the soil. It happened in specific places where the compacted soil layer, generally ubiquitous in the area at a depth of 40-50 cm, is interrupted. Therefore salinity appeareds in discret points as patches. Artesian upward flow already described in this area (Haworth et al., 1966; Williamson et al., 1989; Imaizumi et al., 2002) is most probably responsible for this water table rise, thereby affecting crop productivity. Numerical modelling of water flow using HYDRUS-3D further supported these results and showed that managing the depth of flooding within the plot can significantly reduce the outbreak of these saline plumes.

Hammecker, Claude; Maeght, Jean-Luc; Grünberger, Olivier; Siltacho, Siwaporn; Srisruk, Kriengsak; Noble, Andrew

2012-08-01

130

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

PubMed

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

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

2015-04-01

131

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. PMID:23202689

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

2012-01-01

132

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

133

Wastewater treatment by using kenaf in paddy soil and effect of dissolved oxygen concentration on efficiency  

Microsoft Academic Search

We previously reported that kenaf (Hibiscus cannabinus L.) planted in a zeolite-bed filter-ditch system provided highly effective treatment of wastewater. Here we compared that system with treatment in fallow paddy fields irrigated in different ways in a greenhouse. Paddy soil was a useful alternative to zeolite as the bed filter material. The efficiency of removal of N and P under

Kaoru Abe; Yasuo Ozaki

2007-01-01

134

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

135

Unique viral capsid assembly protein gene ( g20 ) of cyanophages in the floodwater of a Japanese paddy field  

Microsoft Academic Search

In order to evaluate the genetic diversity of cyanophage communities of rice fields, viral capsid assembly protein gene (g20) was amplified with primers CPS1 and CPS8. The DNA was extracted three times from viral concentrates obtained from floodwater\\u000a samples collected in each of four different plots (no fertilizer; P and K chemical fertilizers; N, P, and K chemical fertilizers;\\u000a and

Guanghua Wang; Jun Murase; Susumu Asakawa; Makoto Kimura

2010-01-01

136

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

NASA Astrophysics Data System (ADS)

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

Wu, Xiarui; Zhang, Ao

2014-12-01

137

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

PubMed

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

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

2014-03-01

138

Organochlorine pesticide residues in paddy fish in Malaysia and the associated health risk to farmers*  

PubMed Central

Paddy fish (Trichogaster pectoralis Regan) were collected from five sampling locations in a major paddy-growing area of Malaysia and analysed for organochlorine residues. During the same period, ten farming families, chosen at random from each of the five sampling sites, were interviewed. Information was obtained about the quantity of paddy fish consumed, the amount and type of pesticide used on the paddy-field, and the frequency of application. The pesticide residues found in the fish samples were aldrin/dieldrin, chlordane, HCH, and DDT. Only the projected maximum intake level for aldrin/dieldrin approached the acceptable daily intake as recommended by FAO/WHO; other residue levels were relatively low. However, this study considered only fish; the total daily intake of pesticide residues by the Malaysian paddy farmer may be considerably increased by consumption of other contaminated food. PMID:6610493

Chen, Donald F.; Meier, Peter G.; Hilbert, Morton S.

1984-01-01

139

Mapping of arsenic pollution with reference to paddy cultivation in the middle Indo-Gangetic Plains.  

PubMed

A detailed field study was carried out to monitor (i) the arsenic contents in irrigation groundwater and paddy soil and (ii) the accumulation of arsenic in the roots and grains of different paddy varieties grown in the arsenic-contaminated middle Indo-Gangetic Plains of Northern India. Results showed the highest arsenic contamination in the irrigation groundwater (312 ?g l(-1)) and in paddy soil (35 mg kg(-1)) values that were significantly exceeded the recommended threshold values of 100 ?g l(-1) (EU) and 20 mg kg(-1) (FAO), respectively. The paddy soil arsenic content ranged from 3 to 35 mg kg(-1) with a mean value of 15 mg kg(-1). The soil arsenic content was found to be influenced by the soil texture, carbon, macronutrients, phosphorus, sulfur, hydrolases, and oxidoreductases properties of the paddy soils as revealed in the principal component analyses. Higher root accumulation (>10 mg kg(-1)) of arsenic was observed in 6 of the 17 paddy varieties grown in the study area. The range of arsenic content accumulated in the paddy roots was 4.1 to 16.2 mg kg(-1) dry weight (dw) and in the grains 0.179 to 0.932 mg kg(-1) dw. Out of 17 paddy varieties, eight had 0?>?.55 mg kg(-1) grain arsenic content and were found unsafe for subsistence maximum daily tolerable dietary intake (MTDI) by human beings according to the regulatory standards. PMID:25796519

Srivastava, Pankaj Kumar; Singh, Manvi; Gupta, Manjul; Singh, Nandita; Kharwar, Ravindra Nath; Tripathi, Rudra Deo; Nautiyal, Chandra Shekhar

2015-04-01

140

Environmental controls over methyl halide emissions from rice paddies  

Microsoft Academic Search

This paper examines primary controlling factors that affect methyl halide emissions from rice paddy ecosystems. Observations of four cultivars under multiple growth conditions during studies in commercial fields and the University of California, Irvine, greenhouse lead to the conclusion that daily emissions of methyl halides are primarily determined by the growth stage of the rice plant, with the exception that

K. R. Redeker; R. J. Cicerone

2004-01-01

141

Arsenic Dynamics in Porewater of an Intermittently Irrigated Paddy  

E-print Network

) with arsenic- contaminated groundwater is leading to increased As levels in soils and rice, and to concerns an important role in regulating As uptake by rice plants under oxic and reducing conditionsArsenic Dynamics in Porewater of an Intermittently Irrigated Paddy Field in Bangladesh L I N D A C

Wehrli, Bernhard

142

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

PubMed Central

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

Yang, Shihong; Wei, Qi; Gao, Xiaoli

2013-01-01

143

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

Microsoft Academic Search

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

Giveson Zulu; Masaru Toyota; Shin-ichi Misawa

1996-01-01

144

Paddy soil — A suitable target for monitoring heavy metal pollution by magnetic proxies  

NASA Astrophysics Data System (ADS)

A preliminary magnetic study around Meishan steel mill in Nanjing (SE China) was carried out combining geochemical analysis with scanning electron microscopy (SEM) to prove that paddy soil can be a suitable target for environmental study on heavy metal pollution. Magnetic background investigation showed a strong variation in this area due to different land uses and soil types. Magnetic susceptibilities (MS) measured on forest soils are much higher than in paddy fields, and values below 20 cm of the soil surface in forest with parent material of Xiashu loess are several times higher than in paddy soil with parent material of fluvisol. Measurements on vertical profiles show that paddy soil has a very low and stable magnetic background with mass-specific MS around 15 × 10 - 8 m 3 kg - 1 . A strong enhancement of MS values is found in the upper ~ 20 cm of paddy soil predominated by multidomain and pseudo single domain magnetite. However, relatively low S-ratios (0.57 to 0.85) reveal a significant contribution of imperfect anti-ferromagnetic minerals. Detailed research on a paddy soil core at site C719 near the steel mill indicates strong correlation between magnetic mineral concentration-related parameters (?, ARM, SIRM) and heavy metal concentrations of Cu, Pb and Zn. In addition, typical anthropogenic Fe-spherules are detected in top paddy soil by means of SEM, which indicates that the increase of susceptibility in upper soil is mainly caused by steel mill emission. Mapping of MS in paddy fields across the steel mill area shows a decrease of MS with the distance to the major emission zone. Positive correlation between ? and Zn is found by measuring surface soil samples around the steel mill. Because of low background and high homogeneity of the ~ 20 cm uppermost mixing layer paddy fields are especially suitable for magnetic surface mapping of heavy metal pollution.

Yan, H. T.; Hu, S. Y.; Blaha, U.; Rösler, W.; Duan, X. M.; Appel, E.

2011-10-01

145

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

146

Anaerobic ammonia oxidation in a fertilized paddy soil  

PubMed Central

Evidence for anaerobic ammonium oxidation in a paddy field was obtained in Southern China using an isotope-pairing technique, quantitative PCR assays and 16S rRNA gene clone libraries, along with nutrient profiles of soil cores. A paddy field with a high load of slurry manure as fertilizer was selected for this study and was shown to contain a high amount of ammonium (6.2–178.8?mg?kg?1). The anaerobic oxidation of ammonium (anammox) rates in this paddy soil ranged between 0.5 and 2.9?nmolN per gram of soil per hour in different depths of the soil core, and the specific cellular anammox activity observed in batch tests ranged from 2.9 to 21?fmol per cell per day. Anammox contributed 4–37% to soil N2 production, the remainder being due to denitrification. The 16S rRNA gene sequences of surface soil were closely related to the anammox bacteria ‘Kuenenia', ‘Anammoxoglobus' and ‘Jettenia'. Most of the anammox 16S rRNA genes retrieved from the deeper soil were affiliated to ‘Brocadia'. The retrieval of mainly bacterial amoA sequences in the upper part of the paddy soil indicated that nitrifying bacteria may be the major source of nitrite for anammox bacteria in the cultivated horizon. In the deeper oxygen-limited parts, only archaeal amoA sequences were found, indicating that archaea may produce nitrite in this part of the soil. It is estimated that a total loss of 76?g?N?m?2 per year is linked to anammox in the paddy field. PMID:21593796

Zhu, Guibing; Wang, Shanyun; Wang, Yu; Wang, Chaoxu; Risgaard-Petersen, Nils; Jetten, Mike SM; Yin, Chengqing

2011-01-01

147

Study on paddy rice yield estimation based on multisource data and the Grey system theory  

NASA Astrophysics Data System (ADS)

The paddy rice is our important crops. In study of the paddy rice yield estimation, compared with the scholars who usually only take the remote sensing data or meteorology as the influence factors, we combine the remote sensing and the meteorological data to make the monitoring result closer reality. Although the gray system theory has used in many aspects, it is applied very little in paddy rice yield estimation. This study introduces it to the paddy rice yield estimation, and makes the yield estimation model. This can resolve small data sets problem that can not be solved by deterministic model. It selects some regions in Jianghan plain for the study area. The data includes multi-temporal remote sensing image, meteorological and statistic data. The remote sensing data is the 16-day composite images (250-m spatial resolution) of MODIS. The meteorological data includes monthly average temperature, sunshine duration and rain fall amount. The statistical data is the long-term paddy rice yield of the study area. Firstly, it extracts the paddy rice planting area from the multi-temporal MODIS images with the help of GIS and RS. Then taking the paddy rice yield as the reference sequence, MODIS data and meteorological data as the comparative sequence, computing the gray correlative coefficient, it selects the yield estimation factor based on the grey system theory. Finally, using the factors, it establishes the yield estimation model and does the result test. The result indicated that the method is feasible and the conclusion is credible. It can provide the scientific method and reference value to carry on the region paddy rice remote sensing estimation.

Deng, Wensheng; Wang, Wei; Liu, Hai; Li, Chen; Ge, Yimin; Zheng, Xianghua

2009-10-01

148

Intra- versus inter-site macroscale variation in biogeochemical properties along a paddy soil chronosequence  

NASA Astrophysics Data System (ADS)

In order to assess the intrinsic heterogeneity of paddy soils, a set of biogeochemical soil parameters was investigated in five field replicates of seven paddy fields (50, 100, 300, 500, 700, 1000, and 2000 yr of wetland rice cultivation), one flooded paddy nursery, one tidal wetland (TW), and one freshwater site (FW) from a coastal area at Hangzhou Bay, Zhejiang Province, China. All soils evolved from a marine tidal flat substrate due to land reclamation. The biogeochemical parameters based on their properties were differentiated into (i) a group behaving conservatively (TC, TOC, TN, TS, magnetic susceptibility, soil lightness and colour parameters, ?13C, ?15N, lipids and n-alkanes) and (ii) one encompassing more labile properties or fast cycling components (Nmic, Cmic, nitrate, ammonium, DON and DOC). The macroscale heterogeneity in paddy soils was assessed by evaluating intra- versus inter-site spatial variability of biogeochemical properties using statistical data analysis (descriptive, explorative and non-parametric). Results show that the intrinsic heterogeneity of paddy soil organic and minerogenic components per field is smaller than between study sites. The coefficient of variation (CV) values of conservative parameters varied in a low range (10% to 20%), decreasing from younger towards older paddy soils. This indicates a declining variability of soil biogeochemical properties in longer used cropping sites according to progress in soil evolution. A generally higher variation of CV values (>20-40%) observed for labile parameters implies a need for substantially higher sampling frequency when investigating these as compared to more conservative parameters. Since the representativeness of the sampling strategy could be sufficiently demonstrated, an investigation of long-term carbon accumulation/sequestration trends in topsoils of the 2000 yr paddy chronosequence under wetland rice cultivation restricted was conducted. Observations cannot be extrapolated to global scale but with coastal paddy fields developed on marine tidal flat substrates after land reclamation in the Zhejiang Province represent a small fraction (<1%) of the total rice cropping area. The evolutionary trend showed that the biogeochemical signatures characteristic for paddy soils were fully developed in less than 300 yr since onset of wetland rice cultivation. A six-fold increase of topsoil TOC suggests a substantial gain in CO2 sequestration potential when marine tidal wetland substrate developed to 2000 yr old paddy soil.

Mueller-Niggemann, C.; Bannert, A.; Schloter, M.; Lehndorff, E.; Schwark, L.

2012-03-01

149

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

150

Basin-wide Projection for Paddy Irrigation in Monsoon Asia Based on a Distributed Hydrological Model and Climate Change Scenarios  

NASA Astrophysics Data System (ADS)

1. Introduction A large amount of water in Monsoon Asia is used for rice paddy, and the mechanism of water use varies widely by region. Agricultural water exerts a great influence on the hydrological cycle in river basins and modeling of this process is crucial to understand the hydrological cycle especially in areas where irrigated agriculture is dominant. Such agricultural water uses, however, were not fully combined in the previous runoff models, although this process is essential for assessing the impact of climate change on agriculture in Monsoon Asia. In this study, impact assessment of climate change on paddy field irrigation was carried out in the Seki River basin located in the northern part of Japan, using a distributed hydrological model incorporating various paddy water uses. 2. Distributed hydrological model incorporating various agricultural water uses The model used in this study consists of four sub-models, such as evapotranspiration, cropping pattern/area, agricultural water use, and runoff, so that it enables to estimate cropping area, paddy water requirements, actual intake at main irrigation facilities at any point of the basin, in addition to actual evapotranspiration, soil water content, runoff amount that are normally calculated by many prevailing runoff models. A target basin is divided into 1km-messhed cells and each cell 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 also set as agricultural practices in each cell, and then irrigation amount and actual evapotranspiration can be estimated according to cropping stage and soil moisture. 3. Climate change scenarios and its bias correction Future climate scenarios simulated by MIROC (SRES-A1B), which is one of the GCMs developed by CCSR/NIES/FRCGC in Japan, were used as input data into the hydrological model. Coarse resolution by GCM was nested into 1km resolution by a simple linear interpolation. Bias correction was carried out by a statistical method for the meteorological elements such as precipitation, temperature, relative humidity and wind velocity which were calculated by MIROC. Furthermore, monthly daily-maximum precipitation as extreme events was corrected with the Gumbel distribution. 4. Results and discussion The results in this study are as follows: 1) Snow water equivalence during the winter season will decrease by global warming in near future (2046-2065) and the end of 21th century (2081-2100). As a result, this will lead to a decrease in snowmelt runoff in early spring. 2) Agricultural intake at the “Itakura” head works would decrease especially on May and June owing to the decrease in snowmelt runoff mentioned above. 3) The agricultural water would not be supplied in lower part of irrigated area sufficiently, while increasing in evapotranspiration from paddy field. Therefore, this may result in imbalance of agricultural water in these areas.4) The distributed hydrological model incorporating various agricultural water uses can foretell detailed impacts of climate change on irrigation as well as that of discharge.

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

2010-12-01

151

5th World Aqua Congress, New Delhi, India, November 16-18, 2011 ASSESSING WATER USE EFFICIENCY WITH HYDRODYNAMIC OF PADDY  

E-print Network

balance and mean tracer test velocities are in the same range, the solute transport through tracer test WITH HYDRODYNAMIC OF PADDY CULTIVATION AND RETURN FLOW USING TRACER TESTS Boisson Alexandre1 ., Perrin Jérôme2 on the hydrodynamics of paddy fields to fully understand solute transport. We assess infiltration using a water balance

Paris-Sud XI, Université de

152

Structure Slicing: Extending Logical Regions with Fields  

E-print Network

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

Aiken, Alex

153

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

PubMed Central

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

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

2012-01-01

154

[Microbial metabolism in typical flooded paddy soils ].  

PubMed

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

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

2014-09-01

155

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

156

Diversity and abundance of arsenic biotransformation genes in paddy soils from southern china.  

PubMed

Microbe-mediated arsenic (As) biotransformation in paddy soils determines the fate of As in soils and its availability to rice plants, yet little is known about the microbial communities involved in As biotransformation. Here, we revealed wide distribution, high diversity, and abundance of arsenite (As(III)) oxidase genes (aioA), respiratory arsenate (As(V)) reductase genes (arrA), As(V) reductase genes (arsC), and As(III) S-adenosylmethionine methyltransferase genes (arsM) in 13 paddy soils collected across Southern China. Sequences grouped with As biotransformation genes are mainly from rice rhizosphere bacteria, such as some Proteobacteria, Gemmatimonadales, and Firmicutes. A significant correlation of gene abundance between arsC and arsM suggests that the two genes coexist well in the microbial As resistance system. Redundancy analysis (RDA) indicated that soil pH, EC, total C, N, As, and Fe, C/N ratio, SO4(2-)-S, NO3(-)-N, and NH4(+)-N were the key factors driving diverse microbial community compositions. This study for the first time provides an overall picture of microbial communities involved in As biotransformation in paddy soils, and considering the wide distribution of paddy fields in the world, it also provides insights into the critical role of paddy fields in the As biogeochemical cycle. PMID:25738639

Zhang, Si-Yu; Zhao, Fang-Jie; Sun, Guo-Xin; Su, Jian-Qiang; Yang, Xiao-Ru; Li, Hu; Zhu, Yong-Guan

2015-04-01

157

Intra-versus inter-site macroscale variation in biogeochemical properties along a paddy soil chronosequence  

NASA Astrophysics Data System (ADS)

In order to assess the intrinsic heterogeneity of paddy soils, a set of biogeochemical soil parameters was investigated in five field replicates of seven paddy fields (50, 100, 300, 500, 700, 1000, and 2000 yr of wetland rice cultivation), one flooded paddy nursery, one tidal wetland (TW), and one freshwater site (FW) from a coastal area at Hangzhou Bay, Zhejiang Province, China. All soils evolved from a marine tidal flat substrate due to land reclamation. The biogeochemical parameters based on their properties were differentiated into (i) a group behaving conservatively (TC, TOC, TN, TS, magnetic susceptibility, soil lightness and colour parameters, ?13C, ?15N, lipids and n-alkanes) and (ii) one encompassing more labile properties or fast cycling components (Nmic, Cmic, nitrate, ammonium, DON and DOC). The macroscale heterogeneity in paddy soils was assessed by evaluating intra- versus inter-site spatial variability of biogeochemical properties using statistical data analysis (descriptive, explorative and non-parametric). Results show that the intrinsic heterogeneity of paddy soil organic and minerogenic components per field is smaller than between study sites. The coefficient of variation (CV) values of conservative parameters varied in a low range (10 % to 20 %), decreasing from younger towards older paddy soils. This indicates a declining variability of soil biogeochemical properties in longer used cropping sites according to progress in soil evolution. A generally higher variation of CV values (>20-40 %) observed for labile parameters implies a need for substantially higher sampling frequency when investigating these as compared to more conservative parameters. Since the representativeness of the sampling strategy could be sufficiently demonstrated, an investigation of long-term carbon accumulation/sequestration trends in topsoils of the 2000 year paddy chronosequence under wetland rice cultivation was conducted. The evolutionary trend showed that the biogeochemical signatures characteristic for paddy soils were fully developed in less than 300 yr since onset of wetland rice cultivation. A six-fold increase of topsoil TOC suggests a substantial gain in CO2 sequestration potential when marine tidal wetland substrate developed to 2000 year old paddy soil.

Mueller-Niggemann, C.; Bannert, A.; Schloter, M.; Lehndorff, E.; Schwark, L.

2011-10-01

158

Transfer of 137Cs to rice plants from various paddy soils contaminated under flooded conditions at different growth stages  

Microsoft Academic Search

Soil blocks from 18 paddy fields around three Korean nuclear power plant sites were put into lysimeters. Greenhouse experiments were carried out to investigate the 137Cs transfer from these paddy soils to rice plants for its deposition at different growth stages. A solution of 137Cs was applied to the flooded lysimeters at 2–3 different stages. The applied 137Cs was mixed

Y. H. Choi; K. M. Lim; H. G. Park; D. W. Park; H. S. Kang; H. S. Lee

2005-01-01

159

Interfield and intrafield variability of methyl halide emissions from rice paddies  

Microsoft Academic Search

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

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

2002-01-01

160

Polar Field Reversals and Active Region Decay  

NASA Astrophysics Data System (ADS)

We study the relationship between polar field reversals and decayed active region magnetic flux. Photospheric active region flux is dispersed by differential rotation and turbulent diffusion, and is transported poleward by meridional flows and diffusion. Using NSO Kitt Peak synoptic magnetograms, we investigate in detail the relationship between the transport of decayed active region flux to high latitudes and changes in the polar field strength, including reversals in the magnetic polarity at the poles. By means of stack plots of low- and high-latitude slices of the synoptic magnetograms, the dispersal of flux from low to high latitudes is tracked, and the timing of this dispersal is compared to the polar field changes. In the most abrupt cases of polar field reversal, a few activity complexes (systems of active regions) are identified as the main cause. The poleward transport of large quantities of decayed lagging-polarity flux from these complexes is found to correlate well in time with the abrupt polar field changes. In each case, significant latitudinal displacements were found between the positive and negative flux centroids of the complexes, consistent with Joy's law bipole tilt with lagging-polarity flux located poleward of leading-polarity flux. This work is carried out through the National Solar Observatory Summer Research Assistantship (SRA) Program. The National Solar Observatory is operated by the Association of Universities for Research in Astronomy, Inc. (AURA) under cooperative agreement with the National Science Foundation.

Petrie, Gordon; Ettinger, Sophie

2015-04-01

161

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

162

Environmental profile of paddy rice cultivation with different straw management.  

PubMed

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

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

2014-10-01

163

Some aspects of fluidized bed combustion of paddy husk  

Microsoft Academic Search

Some agricultural wastes--for example, bagasse, paddy husk, etc.--are frequently used as fuels, paddy husk appearing, in particular, to be quite suitable for fluidized bed combustion. The conventional method of combustion of paddy husk in grate-type furnaces is slow and inefficient. This paper reports certain aspects of the fluidized bed combustion of paddy husk. Fluidized bed combustion was carried out by

S. C. Bhattacharya; Narendra Shah; Zaman Alikhani

1984-01-01

164

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

PubMed Central

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

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

2013-01-01

165

Detection and estimation of mixed paddy rice cropping patterns with MODIS data  

NASA Astrophysics Data System (ADS)

In this paper, we developed a more sophisticated method for detection and estimation of mixed paddy rice agriculture from Moderate Resolution Imaging Spectroradiometer (MODIS) satellite data. Previous research demonstrated that MODIS data can be used to map paddy rice fields and to distinguish rice from other crops at large, continental scales with combined Enhanced Vegetation Index (EVI) and Land Surface Water Index (LSWI) analysis during the flooding and rice transplanting stage. Our approach improves upon this methodology by incorporating mixed rice cropping patterns that include single-season rice crops, early-season rice, and late-season rice cropping systems. A variable EVI/LSWI threshold function, calibrated to more local rice management practices, was used to recognize rice fields at the flooding stage. We developed our approach with MODIS data in Hunan Province, China, an area with significant flooded paddy rice agriculture and mixed rice cropping patterns. We further mapped the aerial coverage and distribution of early, late, and single paddy rice crops for several years from 2000 to 2007 in order to quantify temporal trends in rice crop coverage, growth and management systems. Our results were validated with finer resolution (2.5 m) Satellite Pour l'Observation de la Terre 5 High Resolution Geometric (SPOT 5 HRG) data, land-use data at the scale of 1/10,000 and with county-level rice area statistical data. The results showed that all three paddy rice crop patterns could be discriminated and their spatial distribution quantified. We show the area of single crop rice to have increased annually and almost doubling in extent from 2000 to 2007, with simultaneous, but unique declines in the extent of early and late paddy rice. These results were significantly positive correlated and consistent with agricultural statistical data at the county level ( P < 0.01).

Peng, Dailiang; Huete, Alfredo R.; Huang, Jingfeng; Wang, Fuming; Sun, Huasheng

2011-02-01

166

Ancient paddy soils from the Neolithic age in China's Yangtze River Delta  

NASA Astrophysics Data System (ADS)

Identifying prehistoric irrigated rice fields and characterizing the beginning of paddy soil development are important for a better understanding of human development and agricultural history. In 2003, paddy soils and irrigated rice fields buried at a depth of 100-130 cm were excavated at Chuo-dun-shan in the Yangtze River Delta, close to Suzhou, China. The fields of sizes between 1.4 and 16 m2 were surrounded with ridges that were connected to ditches/ponds via outlets to control the water level within the fields. Many carbonized and partly carbonized rice grains with an age of 3,903 B.C.(measured 14C age 5,129±45 a BP) were recovered. The surface layers of these buried paddy fields showed a high content of soil organic matter and a considerable high density of rice opals. The latter were identified to derive from Oryza spp. Solid-state 13C nuclear magnetic resonance spectroscopy revealed aromatic carbon (C) as the predominant organic C form in the fossil surface layer. This is expected, if the major source represents burnt rice and straw. In summary, our data are in agreement with new evidences indicating that in China, paddy soils and irrigated rice cultivation were initiated and developed more than 6,000 years ago.

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

2006-05-01

167

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

Microsoft Academic Search

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

Carles Flaquer; Ignacio Torre; Ramon Ruiz-Jarillo

2006-01-01

168

The Phylogeny of Fluorescent Pseudomonads in an Unflooded Rice Paddy Soil  

Technology Transfer Automated Retrieval System (TEKTRAN)

The purpose of this research was to determine the diversity and distribution of fluorescent pseudomonads in an unflooded rice paddy soil. A region of the 16S ribosomal RNA gene from isolates was amplified using PCR and subsequently analyzed by sequence analysis for bacterial identification and phyl...

169

Phylogenetically distinct phylotypes modulate nitrification in a paddy soil.  

PubMed

Paddy fields represent a unique ecosystem in which regular flooding occurs, allowing for rice cultivation. However, the taxonomic identity of the microbial functional guilds that catalyze soil nitrification remains poorly understood. In this study, we provide molecular evidence for distinctly different phylotypes of nitrifying communities in a neutral paddy soil using high-throughput pyrosequencing and DNA-based stable isotope probing (SIP). Following urea addition, the levels of soil nitrate increased significantly, accompanied by an increase in the abundance of the bacterial and archaeal amoA gene in microcosms subjected to SIP (SIP microcosms) during a 56-day incubation period. High-throughput fingerprints of the total 16S rRNA genes in SIP microcosms indicated that nitrification activity positively correlated with the abundance of Nitrosospira-like ammonia-oxidizing bacteria (AOB), soil group 1.1b-like ammonia-oxidizing archaea (AOA), and Nitrospira-like nitrite-oxidizing bacteria (NOB). Pyrosequencing of (13)C-labeled DNA further revealed that (13)CO2 was assimilated by these functional groups to a much greater extent than by marine group 1.1a-associated AOA and Nitrobacter-like NOB. Phylogenetic analysis demonstrated that active AOB communities were closely affiliated with Nitrosospira sp. strain L115 and the Nitrosospira multiformis lineage and that the (13)C-labeled AOA were related to phylogenetically distinct groups, including the moderately thermophilic "Candidatus Nitrososphaera gargensis," uncultured fosmid 29i4, and acidophilic "Candidatus Nitrosotalea devanaterra" lineages. These results suggest that a wide variety of microorganisms were involved in soil nitrification, implying physiological diversification of soil nitrifying communities that are constantly exposed to environmental fluctuations in paddy fields. PMID:25724959

Zhao, Jun; Wang, Baozhan; Jia, Zhongjun

2015-05-01

170

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

171

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

172

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

PubMed

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

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

2009-10-01

173

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

174

Seasonal variations in methane flux and [delta][sup 13]CH[sub 4] values for rice paddies in Japan and their implications  

SciTech Connect

An important source of methane to the atmosphere is from rice paddy fields. This paper presents isotopic data and interpretations from two seasons of measurements of rice paddy methane flux from fields located in Japan. Possible causes for the variation in the stable carbon isotopic signal of methane throughout the growing season are suggested. The consequences for developing a global isotopic atmospheric methane budget are also discussed. 54 refs., 3 figs., 2 tabs.

Tyler, S.C.; Cicerone, R.J. (Univ. of California, Irvine, CA (United States)); Brailsford, G.W. (National Institute of Water and Atmospheric Research, Lower Hutt (New Zealand)); Yagi, K.; Minami, K. (National Institute of Agro-Environmental Sciences, Tsukuba (Japan))

1994-03-01

175

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

PubMed

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

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

2015-03-01

176

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

177

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

178

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

PubMed Central

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

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

2014-01-01

179

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

PubMed

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

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

2012-01-01

180

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

PubMed

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

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

2014-01-01

181

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

182

Evaluation of soil characteristics potentially affecting arsenic concentration in paddy rice ( Oryza sativa L.)  

Microsoft Academic Search

Paddy rice may contribute considerably to the human intake of As. The knowledge of soil characteristics affecting the As content of the rice plant enables the development of agricultural measures for controlling As uptake.During field surveys in 2004 and 2006, plant samples from 68 fields (Italy, Po-area) revealed markedly differing As concentration in polished rice. The soil factors total As(aqua

Katja Bogdan; Manfred K. Schenk

2009-01-01

183

Seasonal variations of the vegetation index of the rice field and forest in the Tohoku area of Japan  

Microsoft Academic Search

AVHRR-derived normalized vegetation index (NDVI) is used to examine the paddy field and forest in the northern part of Japan. Twelve sites of the paddy fields and eleven sites of the forest are selected and time series of the NDVI are produced for each of the sites. Two types of NDVI variation pattern are recognized for the paddy field and

H. Kawamura; Y. Edamatsu

1993-01-01

184

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

185

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

186

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

NASA Astrophysics Data System (ADS)

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

Higashino, Makoto; Stefan, Heinz G.

2014-11-01

187

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

188

CH 4 emission and oxidation in Chinese rice paddies  

Microsoft Academic Search

In the paper, the characteristics of CH4 emission from the rice paddies, its temporary and spatial variations as well as factors regulating CH4 emission and oxidation are reviewed with an emphasis on CH4 emission from rice paddies in China. The observed four types of diel variation and two type of seasonal variation can be explained by the variations of methane

Wang Mingxing; Li Jing

2002-01-01

189

Mineralization of metsulfuron-methyl in Chinese paddy soils  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

190

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...

191

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

192

Field Sampling Manual Regional Monitoring Program for Trace Substances  

E-print Network

Field Sampling Manual for the Regional Monitoring Program for Trace Substances P r e p a r e d f o AKNOWLEDGEMENTS This document was produced with the assistance from the following Regional Monitoring Program 1 PROGRAM OVERVIEW

193

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

PubMed Central

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

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

2011-01-01

194

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

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

195

[Effects of different fertilizer species on carbon and nitrogen leaching in a reddish paddy soil].  

PubMed

Enhanced fertilization could decrease nitrogen utilization rate and increase carbon and nitrogen leaching, leading to water pollution in agricultural ecosystem. A long-term field experiment had been established on a reddish paddy soil of Qianyanzhou Ecological Experimental Station (114 degrees 53'E, 26 degrees 48'N) in Jiangxi Province in 1998. Soil solution samples were collected by clay tube and vacuum pump. Four fertilizer species treatments were selected: control with no fertilizer (CK), straw return (ST), nitrogen, phosphorus and potassium mineral fertilizers (NPK) and pig manure (OM), aiming to evaluate the effects of different species of fertilizer on carbon and nitrogen leaching in a double rice cropping system. The results showed that: (1) ammonium nitrogen (NH4(+) -N) was the major type of N in soil leachate in reddish paddy soil. The application of NPK could significantly increase the ammonium nitrogen concentration (1.2 mg x L(-1) +/- 0.1 mg x L(-1)) compared with the CK, ST and OM treatments, and the application of OM could significantly increase the dissolved organic carbon (DOC) concentration (27.3 mg x L(-1) +/- 1.6 mg x L(-1)) in soil leachate. The carbon and nitrogen leaching were more notable in the vegetative growth stage than the reproductive growth stage of rice (P < 0.05); (2) the long-term application of NPK and OM increased the NH4(+) -N, DOC, soil organic carbon (SOC) and total nitrogen (TN) contents. The NPK was best beneficial to improve TN contents and OM to improve SOC contents. (3) The DOC contents in soil leachate and SOC in paddy soil had a positive correlation (P < 0.01), while NH4(+) -N contents in soil leachate and TN contents in paddy soil had a positive correlation (P < 0.01). PMID:25338383

Liu, Xi-Yu; Zou, Jing-Dong; Xu, Li-Li; Zhang, Xin-Yu; Yang, Feng-Ting; Dai, Xiao-Qin; Wang, Zhong-Qiang; Sun, Xiao-Min

2014-08-01

196

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

PubMed

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

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

2015-02-01

197

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

PubMed

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

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

2015-03-01

198

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

PubMed Central

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

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

2014-01-01

199

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

200

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

201

Formation of active region and quiescent prominence magnetic field configurations  

NASA Technical Reports Server (NTRS)

To investigate the formation of prominences, researchers studied chromospheric mass injection into an overlying coronal dipole magnetic field using a 2-D ideal magnetohydrodynamic (MHD) numerical model. Researchers propose that active region prominences are formed by chromospheric plasmas injected directly into the overlying coronal magnetic field and that quiescent prominences are formed by plasmas evaporated at the interface between spicules and corona. Hence, for the simulation of an active region prominence magnetic field we inject the mass from one side, but use a symmetric mass injection to form a quiescent prominence field configuration. Researchers try to find optimum conditions for the formation of Kippenhahn-Schuluter(K-S)type field configuration for stable support of the injection plasmas. They find that the formation of K-S type field configuration by mass injection requires a delicate balance between injection velocity, density, and overlying magnetic fields. These results may explain why a prominence does not form on every neutral line.

An, C.-H.; Bao, J. J.; Wu, S. T.

1986-01-01

202

Agricultural Field in the Great Plains Region of Montana  

USGS Multimedia Gallery

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

203

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

204

Computation of the Potential Magnetic Field in Solar Active Regions  

NASA Astrophysics Data System (ADS)

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

Sadykov, V.; Zimovets, I.

2014-10-01

205

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

206

Methane emission from single cropping rice paddies amended different manures  

SciTech Connect

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

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

1996-12-31

207

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

208

Remediation of cadmium-contaminated paddy soils by washing with chemicals: effect of soil washing on cadmium uptake by soybean.  

PubMed

We conducted a pot experiment to evaluate the effect of soil washing with CaCl(2) on Cd absorption by two soybean cultivars. The results were as follows: (1) Soybean growth was not significantly different in washed and unwashed soils, but the seed Cd concentration for both cultivars decreased significantly, up to 25%, in the washed soils compared with the unwashed soils. (2) In the washed soils, the Cd concentration in the soil solution indicated an obviously lower value from sowing to the flowering stage; however, the change in Cd speciation was not evident in the CaCl(2)-washed soil solution. Consequently, the effect of soil washing using CaCl(2) on Cd-contaminated paddy soils can be expected to continue after a CaCl(2)-washed paddy field is converted to an upland field. PMID:17141294

Maejima, Yuji; Makino, Tomoyuki; Takano, Hiroyuki; Kamiya, Takashi; Sekiya, Naoki; Itou, Tadashi

2007-03-01

209

Methane and nitrous oxide emissions from rice paddy soil as influenced by timing of application of hydroquinone and dicyandiamide  

Microsoft Academic Search

A pot trial and a field experiment were conducted to study the effect of timing of application of nitrification inhibitor\\u000a dicyandiamide (DCD) on N2O and CH4 emissions from rice paddy soil. Four treatments including Treatment CK1, DCD-1 (application of DCD with basal fertilizer), DCD-2 (DCD with tillering fertilizer) and DCD-3 (DCD with panicle initiation\\u000a fertilizer), were designed and implemented in

Xianglan Li; Xiaoyan Zhang; Hua Xu; Zucong Cai; Kazuyuki Yagi

2009-01-01

210

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

Microsoft Academic Search

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

Toshisuke Maruyama; Iwao Hashimoto; Kazuo Murashima; Hiroshi Takimoto

2008-01-01

211

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

E-print Network

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

Scudder, Jack

212

On the Weakening of Chromospheric Magnetic Field in Active Regions  

E-print Network

Simultaneous measurement of line-of-sight (LOS) magnetic and velocity fields at the photosphere and chromosphere are presented. Fe I line at $\\lambda6569$ and $H_{\\alpha}$ at $\\lambda6563$ are used respectively for deriving the physical parameters at photospheric and chromospheric heights. The LOS magnetic field obtained through the center-of-gravity method show a linear relation between photospheric and chromospheric field for field strengths less than 700 G. But in strong field regions, the LOS magnetic field values derived from $H_{\\alpha}$ are much weaker than what one gets from the linear relationship and also from those expected from the extrapolation of the photospheric magnetic field. We discuss in detail the properties of magnetic field observed in $H_{\\alpha}$ from the point of view of observed velocity gradients. The bisector analysis of $H_{\\alpha}$ Stokes $I$ profiles show larger velocity gradients in those places where strong photospheric magnetic fields are observed. These observations may support the view that the stronger fields diverge faster with height compared to weaker fields.

K. Nagaraju; K. Sankarasubramanian; K. E. Rangarajan

2008-01-21

213

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

PubMed

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

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

2015-03-01

214

What supports the parallel electric field in Birkeland current regions?  

NASA Astrophysics Data System (ADS)

Quasi-steady electric fields parallel to the background magnetic field exist in both upward and downward Birkeland-current regions above the aurora. These fields, together with the turbulence found on auroral field lines, energize the plasma particles as they flow either away from or toward the earth. In general, these parallel electric fields are supported by one or more strong double layers, the mirror force, the generalized pressure gradient, and the anomalous resistivity due to the turbulence. Recently, we have developed a new kinetic and multi-moment fluid theory for the Birkeland current system that contains the effect of plasma turbulence [1, 2]. Applying the new theory [1, 2] to observations in the long-range potential region of a downwardcurrent sheet, we show that anomalous resistivity accounts for only a small portion of the parallel electric field and that the contributions from the mirror-force and generalized pressuregradient terms in the generalized Ohm's law for the problem are more important. Calculations in the double layer and transition propagation region for a downward-current sheet show that a strong double layer forms, propagates upward at the local ion-acoustic speed, is destabilized as the current density falls below the local critical value, and reforms at a lower altitude. These results have important implications in other regions of space such as magnetospheric reconnection sites and solar coronal loops where parallel electric fields are likely to exist. [1] J. R. Jasperse et al. (2006), Phys. Plasmas 13, 072903 [2] J. R. Jasperse et al. (2006), Phys. Plasmas 13, 112902

Jasperse, John; Basu, Bamandas; Lund, Eric

215

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...

216

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

PubMed

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

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

2014-04-01

217

Arsenic mobilization and immobilization in paddy soils  

NASA Astrophysics Data System (ADS)

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

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

2010-05-01

218

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

PubMed Central

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

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

2014-01-01

219

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

PubMed

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

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

2015-05-01

220

A very strong magnetic field region in NOAA 11035  

NASA Astrophysics Data System (ADS)

NOAA 11035 was a fairly typical active region that emerged near the central meridian 13-14 December 2009, early in solar cycle 24. During the active region’s rapid emergence and evolution, a deeply-rooted magnetic bipole emerged into the pre-existing leading polarity with spectacular consequences. Multi-wavelength imaging and spectropolarimetry from FIRS, IBIS, Hinode, TRACE, and SOHO allow for a comprehensive investigation of the physical processes present in this region. Intrusion of the opposite polarity into the leading sunspot’s penumbra resulted in a region of highly concentrated horizontal magnetic field, with a peak field strength larger than 3600 G based on Milne-Eddington inversion of Fe I spectropolarimetry at 6302 and 15650 Å. Photospheric velocity measurements show blueshifts of 4 km/sec along the neutral line, which are coincident with a dark chromospheric structure in He I 10830 and H I 6563 Å. We conclude that these signatures are the result of continuous magnetic reconnection near photospheric heights.

Jaeggli, Sarah Amelia

2015-04-01

221

REGIONAL-SCALE WIND FIELD CLASSIFICATION EMPLOYING CLUSTER ANALYSIS  

SciTech Connect

The classification of time-varying multivariate regional-scale wind fields at a specific location can assist event planning as well as consequence and risk analysis. Further, wind field classification involves data transformation and inference techniques that effectively characterize stochastic wind field variation. Such a classification scheme is potentially useful for addressing overall atmospheric transport uncertainty and meteorological parameter sensitivity issues. Different methods to classify wind fields over a location include the principal component analysis of wind data (e.g., Hardy and Walton, 1978) and the use of cluster analysis for wind data (e.g., Green et al., 1992; Kaufmann and Weber, 1996). The goal of this study is to use a clustering method to classify the winds of a gridded data set, i.e, from meteorological simulations generated by a forecast model.

Glascoe, L G; Glaser, R E; Chin, H S; Loosmore, G A

2004-06-17

222

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

223

Quasistatic electric field structures and field-aligned currents in the polar cusp region  

NASA Astrophysics Data System (ADS)

Cluster data have been examined for quasi-stationary electric field structures and field-aligned currents (FACs) in the vicinity of the dayside cusp region. We have related the measurements to the Region 1/Region 2 (R1/R2) current system and the cusp current system. It has been theoretically proposed that the dayside R1 current may be located on open field lines, and experimental evidence has been shown for R1 currents partially on open field lines. We document that R1 currents may flow entirely on open field lines. The electric field structures are found to occur at plasma density gradients in the cusp. They are associated with strong FACs with current directions that are consistent with the cusp currents. This indicates that the electric field structures are closely coupled to the cusp current system. The electric equipotential structures linking the perpendicular electric fields seen at Cluster altitudes to field-aligned electric fields at lower altitudes fall into one of two categories: S shape or U shape. Both types are found at both the equatorward edge of the cusp ion dispersion and at the equatorward edge of injection events within the cusp. Previous studies in the nightside auroral region attributed the S-shaped potential structures to the boundary transition between the low-density polar cap and the high-density plasma sheet, concluding that the shape of the electric potential structure depends on whether the plasma populations on each side of the structure can support intense currents. This explanation is not applicable for the S-shaped structures observed in the dayside cusp region.

Jacobsen, K. S.; Moen, J. I.; Pedersen, A.

2010-10-01

224

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

SciTech Connect

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

Vladimir Pascalutsa

2006-09-18

225

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

226

Equatorial E and F region zonal electric fields in the postsunset period  

Microsoft Academic Search

The E and F region eastward electric fields in the postsunset period obtained from VHF backscatter radar and ionosonde observations respectively at the magnetic equatorial station at Trivandrum are colnpared. It is found that the F region eastward electric field is greater than the E region electric field indicating latitudinal gradients in the E region electric field. Enhancement of equatorial

S. S. Hari; K. S. Viswanathan; K. S. V. Subbarao; B. V. Krishna Murthy

1996-01-01

227

The history, development, and regional significance of Ruston Field  

SciTech Connect

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

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

1993-09-01

228

Intense field ionization of diatomic molecules in the tunneling region.  

NASA Astrophysics Data System (ADS)

There are two theoretical approaches to study the strong field ionization of molecules.One is based on a static picture in which the electron is considered to tunnel out through a potential barrier (ADK Theory [1]). In this approach the time dependence of laser field is taken into account by averaging the static ionization rate over time. A simple ionization formula can be obtained and it well predicts the experimental result in the tunneling region. Another theoretical approach is the time-dependent picture based on an S-matrix formulism. An essential feature of this approach is Strong Field Approximation (SFA). We expect that in the tunneling region the SFA will give similar analytical expression as in the ADK theory. Much work has been done in the atomic case to demonstrate that the SFA asymptotically gives ADK tunneling rate [2]. Here we study the strong field ionization of simple diatomic molecules in which the electronic wave functions will be represented by linear combination of atomic orbitals (LCAO). We will consider the ionization rate in tunnelling regime for diatomic molecules and investigate the interference effects between different atomic orbitals. We will compare our asymptotic formula with numerical calculation for simple systems. [1]Ammosov, Delone, Krainov Sov. Phys. Jept. 64 1191 [2]L. V. Keldysh Sov. Phys.Jept. 20 1307

Long, Zi Jian; Liu, Wing-Ki

2007-06-01

229

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

NASA Technical Reports Server (NTRS)

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

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

1972-01-01

230

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

231

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

PubMed

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

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

2013-01-01

232

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

PubMed Central

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

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

2013-01-01

233

Neptune's polar cusp region - Observations and magnetic field analysis  

NASA Technical Reports Server (NTRS)

This paper confirms and extends the results of Szabo et al. (1991) (which demonstrated some similarities of the Neptune's polar cusp region to the earth's cusp), but uses a different approach requiring plasma and vector magnetic field quantities. In addition, various MHD properties of the cusp-magnetopause boundary, which separates the cusp from the magnetosheath allowing thermal anisotropy, are obtained, including the magnetopause (MP) normal, mass, and normal momentum flux, the boundary speed (and thickness), and their relationships. Results demonstrate that the MP velocity is composed of two components: a propagation speed and the other component consistent with the rotational motion of the magnetosphere.

Lepping, R. P.; Burlaga, L. F.; Lazarus, A. J.; Vasyliunas, V. M.; Szabo, A.; Steinberg, J.; Ness, N. F.; Krimigis, S. M.

1992-01-01

234

Plasma Equilibrium in a Magnetic Field with Stochastic Regions  

SciTech Connect

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

J.A. Krommes and Allan H. Reiman

2009-04-23

235

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

236

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

237

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

238

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

NASA Astrophysics Data System (ADS)

The presence of arsenic in the groundwater has led to the largest environmental poisoning in history; tens of millions of people in the Ganges Delta continue to drink groundwater that is dangerously contaminated with arsenic (As). Rice fields receive large loads of arsenic with irrigation water and provide recharge to the underlying aquifer. It is currently not known whether rice fields are a sink or source of arsenic in the hydrologic system. In the dry season, as As(III)-containing minerals are oxidized, As(V) is released and will adhere to Fe hydr(oxide) minerals. When sediments are inundated with water, reducing conditions will then drive reduction of Fe hydr(oxides) and release of As. We have been intensively studying a field site in Munshiganj, Bangladesh with extremely high levels of arsenic in groundwater (up to 1.2 mg/L). To better understand geochemical and microbial processes leading to As mobilization in surface sediment, we deployed sensors to take temporally dense measurements across our experimental rice paddy. Data collected in both 2006 and 2007 showed trends in geochemical parameters indicating that diurnal, possibly plant-induced, processes may be important. Over a two month period, nitrate concentrations decrease consistently each day as ammonium levels increase, presumably through temperature driven reductive processes. Nitrate concentrations in the subsurface then increase while ammonium levels decrease, possibly due to root oxygen leakage or rapid infiltration of oxygen rich surface water. Using sediment from the rice paddy and artificial irrigation water, laboratory microcosms were constructed to simulate the diurnal cycles observed at the field site. In carbon-ammended treatments, Fe and As cycling can occur on the order of days. Oscillations in redox conditions on diurnal as well as seasonal time scales may be important in the mobilization of arsenic into aquifers. By elucidating As mobilization mechanisms at an experimental rice paddy, this work could ultimately lead to solutions that minimize As exposure in critical populations.

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

2007-12-01

239

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

240

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

NASA Astrophysics Data System (ADS)

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

Macalady, J.; Scow, K. M.

2001-12-01

241

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

Microsoft Academic Search

Paddy soils are described as important accumulator for OM (Zhang and He, 2004). In southeast China, paddy soils have the second highest OM stocks (Zhao et al, 1997) and thus a large proportion of the terrestrial carbon is conserved in wetland rice soils. The paddy soil management is believed to be favorable for accumulation of organic matter, as its content

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

2010-01-01

242

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

243

78 FR 26651 - Redelegation of Authority to Regional Public Housing Directors and Public Housing Field Office...  

Federal Register 2010, 2011, 2012, 2013, 2014

...to Regional Public Housing Directors and Public Housing Field Office Directors AGENCY: Office of the Assistant...functions, powers, and duties as the Secretary deems necessary...the Regional Public Housing Directors and PIH Field Office...

2013-05-07

244

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

PubMed

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

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

2012-02-01

245

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

246

Response of a Rice Paddy Soil Methanogen to Syntrophic Growth as Revealed by Transcriptional Analyses  

PubMed Central

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

Liu, Pengfei; Yang, Yanxiang; Lü, Zhe

2014-01-01

247

Impact of irrigating rice paddies with groundwater containing arsenic in Bangladesh  

E-print Network

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

van Geen, Alexander

248

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

249

Kinetic Distribution of 14C-Metsulfuron-methyl Residues in Paddy Soils under Different Moisture Conditions  

Technology Transfer Automated Retrieval System (TEKTRAN)

Rice paddy soils undergo several cycles of drying and wetting during a growing season. A laboratory study was conducted to determine the effect of soil moisture conditions on the distribution and kinetics of extractable and bound residues of 14C-metsulfuron-methyl in six Chinese paddy soils during 8...

250

77 FR 4862 - Agency Requests for Renewal of a Previously Approved Information Collection: SBTRC Regional Field...  

Federal Register 2010, 2011, 2012, 2013, 2014

...Collection: SBTRC Regional Field Offices Intake Form (DOT F...Hosted by the SBTRC Regional Field Offices, such as small business...Respondents: SBTRC Regional Field Offices. Estimated Number of...respondents, by the use of electronic means, including the use of...

2012-01-31

251

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

E-print Network

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

California at Berkeley, University of

252

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

E-print Network

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

California at Berkeley, University of

253

Estimation of Korean paddy field soil properties using optical reflectance  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

254

Arsenic speciation in rice paddy soils  

Technology Transfer Automated Retrieval System (TEKTRAN)

Arsenic can undergo several chemical and microbial transformations in soil, including oxidation/reduction, methylation/demethylation, and volatilization, which could impact arsenic bioavailability for plant uptake. An experiment was conducted in field plots at Stuttgart, AR to determine whether arse...

255

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

256

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

257

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

258

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

259

Speciation and release kinetics of zinc in contaminated paddy soils.  

PubMed

Zinc is an important nutrient for plants, but it can be toxic at high concentrations. The solubility and speciation of Zn is controlled by many factors, especially soil pH and Eh, which can vary in lowland rice culture. This study determined Zn speciation and release kinetics in Cd-Zn cocontaminated alkaline and acidified paddy soils, under various flooding periods and draining conditions, by employing synchrotron-based techniques and a stirred-flow kinetic method. Results showed almost no change in Zn speciation and release kinetics in the two soils, although the soils were subjected to different flooding periods and draining conditions. The mineral phases in which Zn is immobilized in the soil samples were constrained by linear least squares fitting (LLSF) analyses of bulk X-ray absorption fine structure (XAFS) spectra. Only two main phases were identified by LLSF, i.e., Zn-layered double hydroxides (Zn/Mg-hydrotalcite-like, and ZnAl-LDH) and Zn-phyllosilicates (Zn-kerolite). Under all soil pHs, flooding, and draining conditions, less than 22% of Zn was desorbed from the soil after a two-hour desorption experiment. The information on Zn chemistry obtained in this study will be useful in finding the best strategy to control Cd and Zn bioavailability in the Cd-Zn cocontaminated paddy soils. PMID:22423594

Khaokaew, Saengdao; Landrot, Gautier; Chaney, Rufus L; Pandya, Kaumudi; Sparks, Donald L

2012-04-01

260

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

261

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

E-print Network

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

Scudder, Jack

262

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

Microsoft Academic Search

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

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

1992-01-01

263

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

264

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

E-print Network

Dune field pattern formation and recent transporting winds in the Olympia Undae Dune Field, north] HighResolution Imaging Science Experiment (HiRISE) imagery of the central Olympia Undae Dune Field in the north polar region of Mars shows a reticulate dune pattern consisting of two sets of nearly orthogonal

Bourke, Mary C.

265

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

266

Electric Fields and Plasma Processes in the Auroral Downward Current Region, Below, Within, and Above the Acceleration Region  

Microsoft Academic Search

The downward field-aligned current region plays an active role in magnetosphere-ionosphere coupling processes associated with\\u000a aurora. A quasi-static electric field structure with a downward parallel electric field forms at altitudes between 800 km\\u000a and 5000 km, accelerating ionospheric electrons upward, away from the auroral ionosphere. A wealth of related phenomena, including\\u000a energetic ion conics, electron solitary waves, low-frequency wave activity,

G. T. Marklund

2009-01-01

267

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

PubMed Central

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

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

2012-01-01

268

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

Microsoft Academic Search

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

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

2008-01-01

269

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

NASA Astrophysics Data System (ADS)

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

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

2010-05-01

270

Resonance Free Regions in Magnetic Scattering by Two Solenoidal Fields at Large Separation  

E-print Network

Resonance Free Regions in Magnetic Scattering by Two Solenoidal Fields at Large Separation Ivana the problem of quantum resonances in magnetic scattering by two solenoidal fields at large separation in two : Resonances for scattering by solenoidal fields Keywords : Resonances; magnetic scattering; solenoidal fields

Alexandrova, Ivana

271

A Regional Public Health Field Placement Program: making an IMPACT.  

PubMed

Beginning in 2010, the U.S. Department of Health and Human Services, Health Resources and Services Administration, made provisions in its Public Health Training Center cooperative agreements for field placements. This article describes best practices and lessons learned establishing and managing the South Central Public Health Partnership's Interns and Mentors Program for ACTion (IMPACT) Field Placement Program, which was initially funded through the Centers for Disease Control and Prevention's Centers for Public Health Preparedness Cooperative agreement in 2002. The IMPACT program is based on a six-step process that has been developed and refined over its 10-year history: (a) identifying field placement opportunities, (b) marketing field experience opportunities to students, (c) selecting students seeking field experience opportunities, (d) placing students with practice partners, students with practice partners, (e) evaluating student progress toward field experience objectives, and (f) evaluating the program. This article describes the program's structure and processes, delineates the roles of its academic and practice partners, discusses evidence of its effectiveness, and describes lessons learned from its decade-long history. Hopefully, this information will facilitate the establishment, management and evaluation of internship and field placement programs in other Public Health Training Centers and academic public health programs. PMID:24578369

McCormick, Lisa C; Hites, Lisle; Jenkins, Crystal; Chauvin, Sheila W; Rucks, Andrew C; Ginter, Peter M

2014-03-01

272

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

273

Increase of Available Phosphorus by Fly?Ash Application in Paddy Soils  

Microsoft Academic Search

Fly ash from the coal?burning industry may be a potential inorganic soil amendment to increase rice productivity and to restore the soil nutrient balance in paddy soil. In this study, fly ash was applied at rates of 0, 40, 80, and 120 Mg ha in two paddy soils (silt loam in Yehari and loamy sand in Daegok). During rice cultivation, available phosphorus

Chang Hoon Lee; Hyup Lee; Yong Bok Lee; Hong Hee Chang; Muhamad Aslam Ali; Wonki Min; Suk Kim; Pil Joo Kim

2007-01-01

274

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

NASA Astrophysics Data System (ADS)

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

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

2010-05-01

275

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

E-print Network

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

Sanahuja, Blai

276

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

E-print Network

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

Higuchi, Tomoyuki

277

Evaluation of edge-diffracted fields including equivalent currents for the caustic regions  

Microsoft Academic Search

The fields diffracted by a body made up of finite axially symmetric cone frustums are obtained using the concepts of the geometrical theory of diffraction. The backscattered field for plane-wave incidence on such a target is obtained with particular emphasis on those regions that are usually avoided, namely, the caustic region and its immediate vicinity. The method makes use of

CHARLES E. RYAN

1969-01-01

278

Analysis of focal region field of the offset-parabolic reflector for space-borne radiometers  

Microsoft Academic Search

The paper presents the analysis of the focal region field of an offset parabolic reflector antenna. The current induced on the reflector surface by an incident plane wave has been used to compute the field at the focal region. The analysis has been carried out for a reflector of diameter 1.8 meters by varying the f \\/d ratio and offset

Dhaval Pujara; Soumybrata Chakrabarty; Shashi Bhusan Sharma

2007-01-01

279

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

E-print Network

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

California at Berkeley, University of

280

Field alignment of quadrupole magnets for the LHC interaction regions  

Microsoft Academic Search

High-gradient superconducting quadrupole magnets are being developed by the US LHC Accelerator Project for the Interaction Regions of the Large Hadron Collider. Determination of the magnetic axis for alignment of these magnets will be performed using a single stretched wire system. These measurements will be done both at room and cryogenic temperatures with very long wire lengths, up to 20

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

2000-01-01

281

Regional TEC mapping with Random Field Priors and Kriging  

Microsoft Academic Search

Total Electron Content (TEC) is an important parameter in monitoring ionospheric variability. In a given region, TEC can be obtained only by interpolation of measurements due to sparsity of the useful data. The lack of a complete ionospheric model hinders the choice of the optimum interpolation algorithm. A plausible solution to this problem can be found by investigating the performance

I. Sayin; F. Arikan; O. Arikan

2008-01-01

282

Probable regional geothermal field reconnaissance in the Aegean region from modern multi-temporal night LST imagery  

Microsoft Academic Search

The Hellenic Peninsula and the adjacent Aegean and Ionian seas are segmented into regions on the basis of Terra satellite-MODIS\\u000a instrument derived land surface temperatures (LST) to test if they can be used in the field reconnaissance for potential geothermal\\u000a targets, each region representing a different thermal signature. The method has been used successfully to identify hot spot\\u000a and geothermal

D. ZouziasGeorge; George Ch. Miliaresis; K. St. Seymour

2011-01-01

283

Evaluation of soil characteristics potentially affecting arsenic concentration in paddy rice (Oryza sativa L.).  

PubMed

Paddy rice may contribute considerably to the human intake of As. The knowledge of soil characteristics affecting the As content of the rice plant enables the development of agricultural measures for controlling As uptake. During field surveys in 2004 and 2006, plant samples from 68 fields (Italy, Po-area) revealed markedly differing As concentration in polished rice. The soil factors total As(aqua regia), pH, grain size fractions, total C, plant available P(CAL), poorly crystalline Fe(oxal.) and plant available Si(Na-acetate) content that potentially affect As content of rice were determined. A multiple linear regression analysis showed a significant positive influence of the total As(aqua regia) and plant available P(CAL) content and a negative influence of the poorly crystalline Fe(oxal.) content of the soil on the As content in polished rice and rice straw. Si concentration in rice straw varied widely and was negatively related to As content in straw and polished rice. PMID:19482396

Bogdan, Katja; Schenk, Manfred K

2009-10-01

284

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

PubMed

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

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

2014-05-01

285

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

E-print Network

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

Menut, Laurent

286

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

Microsoft Academic Search

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

Sabine Stanley; Jeremy Bloxham

2004-01-01

287

Interpreting Mars ionospheric anomalies over crustal magnetic field regions using a 2-D ionospheric model  

NASA Astrophysics Data System (ADS)

spatially inhomogeneous, small-scale crustal magnetic fields of Mars influence the escape of planetary atmospheric species and the interaction of the solar wind with the ionosphere. Understanding the plasma response to crustal magnetic field regions can therefore provide insight to ionospheric structure and dynamics. To date, several localized spatial structures in ionospheric properties that have been observed over regions of varying magnetic field at Mars have yet to be explained. In this study, a two-dimensional ionospheric model is used to simulate the effects of field-aligned plasma transport in regions of strong crustal magnetic fields. Resulting spatial and diurnal plasma distributions are analyzed and found to agree with observations from several spacecraft and offer compelling interpretations for many of the anomalous ionospheric behaviors observed at or near regions of strong crustal magnetic fields on Mars.

Matta, Majd; Mendillo, Michael; Withers, Paul; Morgan, Dave

2015-01-01

288

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

289

FAST Observations of Upward Accelerated Electron Beams and the Downward Field-Aligned Current Region  

Microsoft Academic Search

4 Auroral processes result from the exchange of energy and momentum be- tween the magnetosphere and ionosphere, and the current systems arising from this exchange. Field-aligned potential drops in the upward field-aligned current (FAC) region of the auroral zone maintain a required current density in the face of opposing mirror forces. But field-aligned potential drops occur in downward current regions

R. C. Elphic; J. Bonnell; R. J. Strangeway; C. W. Carlson; J. P. McFadden; R. E. Ergun

290

Possible Connection of Geological Composition With Geomagnetic Field Change In Kopaonik Thrust Region  

Microsoft Academic Search

This paper should consider interpretation of geomagnetic field changes on the basis of possible connection with geological composition of deformation zone. Analysis of total magnetic field intensity data from 38 surveys, carried out in the period may 1980 ­ november 2001 in Kopaonik thrust region, central Serbia, reveals anomalous behaviour of local field changes in particular time intervals. These data

Mirjana Popeskov; Milena Cukavac; Caslav Lazovic

2002-01-01

291

A numerical method for extending ray trace calculations of radio fields into strong focusing regions  

Microsoft Academic Search

This paper presents a practical method for computing radio fields in regions of strong focusing, using ray intercept data provided by a standard ray-tracing program. The procedure extends the usefulness of the ray trace by allowing fields to be computed near caustics and cusps where ray density calculations fail. Using a plane wave decomposition of the field components, phase integrals

R. E. Warren; R. N. DeWitt; C. R. Warber

1982-01-01

292

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

E-print Network

Static electric-field effects in the photodetachment of CsÃ? at the 3 P resonance region A. A number s : 32.80.Gc, 32.60. i I. INTRODUCTION A strong external static electric field affects the decay,9 whereby the electron wave reflected by the static-electric-field potential is scattered by the atomic resi

Thumm, Uwe

293

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.

Alexandra Moore

294

H II REGION DRIVEN GALACTIC BUBBLES AND THEIR RELATIONSHIP TO THE GALACTIC MAGNETIC FIELD  

SciTech Connect

The relative alignments of mid-infrared traced Galactic bubbles are compared to the orientation of the mean Galactic magnetic field in the disk. The orientations of bubbles in the northern Galactic plane were measured and are consistent with random orientations-no preferential alignment with respect to the Galactic disk was found. A subsample of H II region driven Galactic bubbles was identified, and as a single population they show random orientations. When this subsample was further divided into subthermal and suprathermal H II regions, based on hydrogen radio recombination linewidths, the subthermal H II regions showed a marginal deviation from random orientations, but the suprathermal H II regions showed significant alignment with the Galactic plane. The mean orientation of the Galactic disk magnetic field was characterized using new near-infrared starlight polarimetry and the suprathermal H II regions were found to preferentially align with the disk magnetic field. If suprathermal linewidths are associated with younger H II regions, then the evolution of young H II regions is significantly affected by the Galactic magnetic field. As H II regions age, they cease to be strongly linked to the Galactic magnetic field, as surrounding density variations come to dominate their morphological evolution. From the new observations, the ratios of magnetic-to-ram pressures in the expanding ionization fronts were estimated for younger H II regions.

Pavel, Michael D.; Clemens, D. P., E-mail: pavelmi@bu.edu, E-mail: clemens@bu.edu [Institute for Astrophysical Research, Boston University, 725 Commonwealth Ave., Boston, MA 02215 (United States)

2012-12-01

295

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

E-print Network

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

Ryohko Ishikawa; Saku Tsuneta

2008-12-09

296

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

297

Adsorption characteristics of Cu and Zn onto various size fractions of aggregates from red paddy soil.  

PubMed

Soil aggregate is the basic structure unit of soils and the ability of various size fractions are different in the aspect of adsorbing and transferring heavy metals in the environment. In this study, bulk soil from red paddy field was partitioned into four aggregate-size fractions and their adsorption characteristics for Cu and Zn were studied. Our results showed that: Pseudo-second order model was more successful to fit the adsorption process in the kinetic experiments and the isothermal experiments data can be described well with the Freundlich model as a whole. Due to higher contents in organic matter, CEC and free iron oxide, the <0.002mm fraction was found to have the highest initial sorption rate and maximum adsorption capacity. The adsorption amount of metals increased as the increasing of pH and the percentage of adsorbed metal susceptible to desorption into 0.01M NaNO3 was greater for Zn than for Cu, while their variation trends were quite opposite. More specific adsorption sites in the <0.002mm fraction lead to more desorption amount for this particle size of soil at low pH condition. After 60 days of incubation, Cu and Zn were observed to enrich in the clay-size aggregates with fractions more stable than other particles. PMID:24295769

Huang, Bin; Li, Zhongwu; Huang, Jinquan; Guo, Liang; Nie, Xiaodong; Wang, Yan; Zhang, Yan; Zeng, Guangming

2014-01-15

298

HELIOSHEATH MAGNETIC FIELDS BETWEEN 104 AND 113 AU IN A REGION OF DECLINING SPEEDS AND A STAGNATION REGION  

SciTech Connect

We examine the relationships between the magnetic field and the radial velocity component V{sub R} observed in the heliosheath by instruments on Voyager 1 (V1). No increase in the magnetic field strength B was observed in a region where V{sub R} decreased linearly from 70 km s{sup -1} to 0 km s{sup -1} as plasma moved outward past V1. An unusually broad transition from positive to negative polarity was observed during a Almost-Equal-To 26 day interval when the heliospheric current sheet (HCS) moved below the latitude of V1 and the speed of V1 was comparable to the radial speed of the heliosheath flow. When V1 moved through a region where V{sub R} Almost-Equal-To 0 (the 'stagnation region'), B increased linearly with time by a factor of two, and the average of B was 0.14 nT. Nothing comparable to this was observed previously. The magnetic polarity was negative throughout the stagnation region for Almost-Equal-To 580 days until 2011 DOY 235, indicating that the HCS was below the latitude of V1. The average passage times of the magnetic holes and proton boundary layers were the same during 2009 and 2011, because the plasma moved past V1 during 2009 at the same speed that V1 moved through the stagnation region during 2011. The microscale fluctuations of B in the stagnation region during 2011 are qualitatively the same as those observed in the heliosheath during 2009. These results suggest that the stagnation region is a part of the heliosheath, rather than a 'transition region' associated with the heliopause.

Burlaga, L. F. [NASA Goddard Space Flight Center, Code 673, Greenbelt, MD 20771 (United States); Ness, N. F., E-mail: lburlagahsp@verizon.net, E-mail: nfnudel@yahoo.com [Institute for Astrophysics and Computational Sciences, Catholic University of America, Washington, DC 20064 (United States)

2012-04-10

299

Track of fate and primary metabolism of trifloxystrobin in rice paddy ecosystem.  

PubMed

Trifloxystrobin, a strobilurin fungicide, has been widely applied to control fungal diseases in various crops, especially in rice cultivation. However, its residual profile in rice paddy that was highly linked to its ecological risk still remains poorly understood. To elucidate the fate and primary metabolism of trifloxystrobin in rice paddy, a simple and efficient analytical method was developed using the DisQuE extraction kit combined with GC-?ECD and GC-EI-MS/MS analyses. As a result, methodological recoveries of trifloxystrobin fortified in paddy water, soil and rice straw ranging from 0.005 to 2mgkg(-1) (mgL(-1) for water) were acquired from 87.6% to 109.1% with relative standard deviation (RSD) from 1.9% to 9.5% (n=5), and the limit of detection (LOD, signal to noise (S/N)=3) and the limit of quantification (LOQ, S/N=10) were 6.3×10(-4)mgL(-1) and 2.09×10(-3)mgL(-1), respectively, which indicates the favorable accuracy, precision and sensitivity of the method for effective monitoring of the trace amounts of residual trifloxystrobin in the rice paddy. Furthermore, dissipation of residual trifloxystrobin was in accordance with the first-order rate equation, showing the half-lives from 0.7 to 7.5days, illustrating that trifloxystrobin generally degraded in a rapid rate in the rice paddy. Additionally, trifloxystrobin acid identified as the primary metabolite of trifloxystrobin in the rice paddy via GC-EI-MS/MS analysis was found to be dominantly accumulated in the paddy water and maintained up to 2.41mgL(-1) within 14days, suggesting that long-term and frequent application of this fungicide may pose a high risk towards aquatic organisms in surrounding aqueous ecosystems through paddy drainage. Taken together, our data serve as a useful tool for monitoring residual trifloxystrobin in rice paddy ecosystem and also provide a basis for in-depth understanding of environmental behavior and ecological risk posed by this fungicide. PMID:25770954

Cao, Mengchao; Li, Shuying; Wang, Quansheng; Wei, Peng; Liu, Yanan; Zhu, Guonian; Wang, Mengcen

2015-06-15

300

Controls on porphyroblast size along a regional metamorphic field gradient  

NASA Astrophysics Data System (ADS)

Garnet-bearing schists from the Waterville Formation of south-central Maine provide an opportunity to examine the factors governing porphyroblast size over a range of metamorphic grade. Three-dimensional sizes and locations for all garnet porphyroblasts were determined for three samples along the metamorphic field gradient spanning lowest garnet through sillimanite grade, using high-resolution X-ray computed tomography. Comparison of crystal size distributions to previous data sets obtained by stereological methods for the same samples reveals significant differences in mode, mean, and shape of the distributions. Quantitative textural analysis shows that the garnets in each rock crystallized in a diffusion-controlled nucleation and growth regime. In contrast to the typical observation of a correlation between porphyroblast size and position along a metamorphic field gradient, porphyroblast size of the lowest-grade specimen is intermediate between the high- and middle-grade specimens’ sizes. Mean porphyroblast size does not correlate with peak temperatures from garnet-biotite Fe-Mg exchange thermometry, nor is post-crystallization annealing (Ostwald Ripening) required to produce the observed textures, as was previously proposed for these rocks. Robust pseudosection calculations fail to reproduce the observed garnet core compositions for two specimens, suggesting that these calc-pelites experienced metasomatism. For each of these two specimens, Monte Carlo calculations suggest potential pre-metasomatism bulk compositions that replicate garnet core compositions. Pseudosection analyses allow the estimation of the critical temperatures for garnet growth: ˜481, ˜477, and ˜485°C for the lowest-garnet-zone, middle-garnet-zone, and sillimanite-zone specimens, respectively. Porphyroblast size appears to be determined in this case by a combination of the heating rate during garnet crystallization, the critical temperature for the garnet-forming reaction and the kinetics of nucleation. Numerical simulations of thermally accelerated, diffusion-controlled nucleation, and growth for the three samples closely match measured crystal size distributions. These observations and simulations suggest that previous hypotheses linking the garnet size primarily to the temperature at the onset of porphyroblast nucleation can only partially explain the observed textures. Also important in determining porphyroblast size are the heating rate and the distribution of favorable nucleation sites.

Hirsch, David M.

2008-04-01

301

Controls on Porphyroblast Size Along a Regional Metamorphic Field Gradient  

NASA Astrophysics Data System (ADS)

Garnet-bearing schists from the Waterville Formation of south-central Maine provide an opportunity to examine the factors governing porphyroblast size over a range of metamorphic grade. Three-dimensional sizes and locations for all garnet porphyroblasts were determined for three samples along the metamorphic field gradient spanning lowest garnet through sillimanite grade, using high-resolution X-ray computed tomography. Comparison of crystal size distributions to previous data sets obtained by stereological methods for the same samples reveals significant differences in mode, mean, and shape of the distributions. Quantitative textural analysis shows that the garnets in each rock crystallized in a diffusion-controlled nucleation and growth regime. In contrast to the typical observation of a correlation between porphyroblast size and position along a metamorphic field gradient, porphyroblast size of the lowest-grade specimen is intermediate between the high- and middle-grade specimens' sizes. Mean porphyroblast size does not correlate with peak temperatures from garnet-biotite Fe-Mg exchange thermometry, which would be expected if porphyroblast sizes were strongly affected by post-crystallization annealing (Ostwald ripening), as previously proposed for these rocks. Robust pseudosection calculations fail to reproduce the observed garnet core compositions for two specimens, indicating that these calc-pelites experienced metasomatism. For each of these two specimens, Monte Carlo calculations suggest potential pre-metasomatism bulk compositions that replicate garnet core compositions. Pseudosection analyses coupled with semi-quantitative pressure-temperature paths allow the estimation of the critical temperatures for garnet growth: ~472° C for the lowest-garnet-zone and middle-garnet-zone specimens, and ~492° C for the sillimanite-zone specimen. Porphyroblast size appears to be determined in this case by a combination of the critical temperature for the garnet forming reaction and variations in the rates of nucleation and heating. Numerical simulations of thermally accelerated, diffusion-controlled nucleation and growth for the three samples closely match measured crystal size distributions. These observations and simulations suggest that previous hypotheses linking the temperature at the onset of porphyroblast nucleation to the resulting crystal size can only partially explain the observed textures. Also important in determining porphyroblast size are the heating rate and the distribution of favorable nucleation sites.

Hirsch, D. M.

2007-05-01

302

Interaction region analysis for a high-field hadron collider  

SciTech Connect

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

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

1996-12-01

303

[Distribution characteristics and sources identification of PAHs in ancient paddy soil].  

PubMed

Soil samples of current paddy soils, ancient paddy soil/ancient dry land soil, and bottom soils were collected from two sites in Chuodunshan Site of Majiabang Culture (about 6,000a). 15 polycyclic aromatic hydrocarbons (PAHs) were analyzed with HPLC, and their possible sources were identified. The sum of 15 PAHs was 202.9microg x kg(-1) and 207.7microg x kg(-1) in the surface soils from Site A and Site B respectively, which were mainly deposited from atmosphere. In ancient paddy soil from Site A, the total PAHs concentration sharply decreased to 56.0microg x kg(-1), but was still higher than those in ancient dry land soil and bottom soils with the sum of 32.0 approximately 36.9microg x kg(-1). In ancient paddy soil, the concentrations of 2-ring and 3-ring PAHs took a larger portion of 63 percents to the total PAHs, and naphthalene and phenanthrene were the most abundant compounds, while PAHs of more than 4 rings took a small part. The ratios of phenanthrene anthracene and benzo(a) anthracene chrysene and 13C-NMR spectrum of soil organic matter showed that PAHs in ancient paddy soil mainly originated from rice straw burning, biogenesis under reducing conditions may be another source. PMID:16921968

Li, Jiu-hai; Dong, Yuan-hua; Cao, Zhi-hong; Wang, Hui; An, Qiong; Hu, Zheng-yi; Yang, Lin-zhang; Lin, Xian-gui; Yin, Rui

2006-06-01

304

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

E-print Network

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

Ingólfsson, Ólafur

305

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

E-print Network

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

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

2003-01-01

306

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

E-print Network

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

Ghole, Saba (Saba Ashfaq)

2007-01-01

307

5 CFR Appendix II to Part 1201 - Appropriate Regional or Field Office for Filing Appeals  

Code of Federal Regulations, 2010 CFR

...Bergen, Essex, Hudson, and Union; Pennsylvania; Rhode Island...Bergen, Essex, Hudson, and Union; New York; Puerto Rico; and...otherwise covered). 5. Western Regional Office, 201 Mission...Denver Field Office, 165 South Union Blvd., Suite 318,...

2010-01-01

308

5 CFR Appendix II to Part 1201 - Appropriate Regional or Field Office for Filing Appeals  

Code of Federal Regulations, 2013 CFR

...Bergen, Essex, Hudson, and Union; Pennsylvania; Rhode Island...Bergen, Essex, Hudson, and Union; New York; Puerto Rico; and...otherwise covered). 5. Western Regional Office, 201 Mission...Denver Field Office, 165 South Union Blvd., Suite 318,...

2013-01-01

309

5 CFR Appendix II to Part 1201 - Appropriate Regional or Field Office for Filing Appeals  

Code of Federal Regulations, 2012 CFR

...Bergen, Essex, Hudson, and Union; Pennsylvania; Rhode Island...Bergen, Essex, Hudson, and Union; New York; Puerto Rico; and...otherwise covered). 5. Western Regional Office, 201 Mission...Denver Field Office, 165 South Union Blvd., Suite 318,...

2012-01-01

310

5 CFR Appendix II to Part 1201 - Appropriate Regional or Field Office for Filing Appeals  

Code of Federal Regulations, 2014 CFR

...Bergen, Essex, Hudson, and Union; Pennsylvania; Rhode Island...Bergen, Essex, Hudson, and Union; New York; Puerto Rico; and...otherwise covered). 5. Western Regional Office, 201 Mission...Denver Field Office, 165 South Union Blvd., Suite 318,...

2014-01-01

311

5 CFR Appendix II to Part 1201 - Appropriate Regional or Field Office for Filing Appeals  

Code of Federal Regulations, 2011 CFR

...Bergen, Essex, Hudson, and Union; Pennsylvania; Rhode Island...Bergen, Essex, Hudson, and Union; New York; Puerto Rico; and...otherwise covered). 5. Western Regional Office, 201 Mission...Denver Field Office, 165 South Union Blvd., Suite 318,...

2011-01-01

312

Speciation and release kinetics of cadmium in an alkaline paddy soil under various flooding periods and draining conditions  

Technology Transfer Automated Retrieval System (TEKTRAN)

Understanding the chemical forms in which Cd is present in paddy soils is needed to develop efficient and cost-effective strategies to clean up the soils, and/or minimize Cd uptake by rice. This study aims to determine Cd speciation and release kinetics in an alkaline paddy soil, at various flooding...

313

Oxidation of elemental sulfur in paddy soils as influenced by flooded condition and plant growth in pot experiment  

Microsoft Academic Search

A pot experiment was conducted to study the effects of rice cropping on elemental sulfur (S0) oxidation in three paddy soils under flooded conditions. Unaltered wet samples of paddy soils derived from cinnamon soil, black soil and red soil, respectively, were used. Repacked soils were incubated for 14, 28 and 42 days with or without addition of 2,000 mg kg-1

Wei Zhou; Min Wan; Ping He; Shutian Li; Bao Lin

2002-01-01

314

Sorption isotherms and isosteric heats of sorption of Malaysian paddy.  

PubMed

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

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

2014-10-01

315

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

USGS Publications Warehouse

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

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

2000-01-01

316

What Supports the Parallel Electric Field in the Birkeland (Field-Aligned) Current Regions of the Earth's Magnetosphere  

NASA Astrophysics Data System (ADS)

Quasi-steady electric fields parallel to the geomagnetic field exist in both upward and downward Birkeland (field-aligned) current regions above the aurora. These fields, together with the turbulence found on auroral field lines, energize the plasma particles as they flow either away from or toward the earth. In general, these parallel electric fields are supported by one or more strong double layers, mirror force, generalized pressure gradient, and anomalous resistivity due to the turbulence. Recently, and for the first time, we have developed a new kinetic and multi-moment fluid theory for the Birkeland current system that contains the effect of turbulence for the inhomogeneous, non-uniformly magnetized plasma. Applying the new theory to observations in a downward-current sheet, we show that anomalous resistivity accounts for only a small portion of the parallel electric field and that contributions from the double layer, mirror force, and generalized pressure gradient terms in the generalized Ohm's law for the problem are more important. These results have important implications in other regions of space such as magnetospheric reconnection sites and solar coronal loops where parallel electric fields are likely to exist.

Jasperse, John; Basu, Bamandas; Lund, Eric; Grossbard, Neil

2008-11-01

317

How heavy are probability tails of wet and dry durations in regionally averaged rain fields ?  

E-print Network

How heavy are probability tails of wet and dry durations in regionally averaged rain fields ? Harry The durations of rain events and drought over a given region provide important infor- mation about the water. These findings are based on radar measurements of spatially averaged rain rate (SARR) over a tropical oceanic

Jureckova, Jana

318

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

E-print Network

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

Rubloff, Gary W.

319

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

320

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

Microsoft Academic Search

Nineteen electron diffusion regions at magnetic field reconnection sites have been found in one hour of Cluster satellite data near the subsolar magnetopause. Investigations on previously unachieved spatial and temporal scales show the following for the first time: direct conversion of magnetic energy to electron energy (The resulting accelerated electrons, their field-aligned currents, and their post-acceleration fate were measured); the

F. S. Mozer; S. D. Bale; J. P. McFadden; R. B. Torbert

2005-01-01

321

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

Microsoft Academic Search

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

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

1991-01-01

322

Study of magnetic fields in solar active regions from radio observations  

Microsoft Academic Search

In this work we present the results of our 3D atmospheric model over solar active regions. Our model considers the temperature and density distributions with height, as well the local magnetic 3D structure. To obtain the positions and intensities of magnetic field lines in the solar atmosphere, we made force-free extrapolations of the magnetic field intensities measured in the MDI

C. L. Selhorst; J. E. R. Costa; A. V. R. Silva

2006-01-01

323

Energy use pattern of some field crops and vegetable production: Case study for Antalya Region, Turkey  

Microsoft Academic Search

This research examines the energy use patterns and energy input–output analysis of some field crops (wheat, cotton, maize, sesame) and vegetables (tomato, melon, watermelon) widely grown in the Antalya region, which is one of the most important agricultural centres in Turkey. Operational inputs and energy sources for cultivating the field crops and vegetables were determined by a questionnaire applied to

M. Canakci; M. Topakci; I. Akinci; A. Ozmerzi

2005-01-01

324

Dose discrepancies in the buildup region and their impact on dose calculations for IMRT fields  

SciTech Connect

Purpose: Dose accuracy in the buildup region for radiotherapy treatment planning suffers from challenges in both measurement and calculation. This study investigates the dosimetry in the buildup region at normal and oblique incidences for open and IMRT fields and assesses the quality of the treatment planning calculations. Methods: This study was divided into three parts. First, percent depth doses and profiles (for 5x5, 10x10, 20x20, and 30x30 cm{sup 2} field sizes at 0 deg., 45 deg., and 70 deg. incidences) were measured in the buildup region in Solid Water using an Attix parallel plate chamber and Kodak XV film, respectively. Second, the parameters in the empirical contamination (EC) term of the convolution/superposition (CVSP) calculation algorithm were fitted based on open field measurements. Finally, seven segmental head-and-neck IMRT fields were measured on a flat phantom geometry and compared to calculations using {gamma} and dose-gradient compensation (C) indices to evaluate the impact of residual discrepancies and to assess the adequacy of the contamination term for IMRT fields. Results: Local deviations between measurements and calculations for open fields were within 1% and 4% in the buildup region for normal and oblique incidences, respectively. The C index with 5%/1 mm criteria for IMRT fields ranged from 89% to 99% and from 96% to 98% at 2 mm and 10 cm depths, respectively. The quality of agreement in the buildup region for open and IMRT fields is comparable to that in nonbuildup regions. Conclusions: The added EC term in CVSP was determined to be adequate for both open and IMRT fields. Due to the dependence of calculation accuracy on (1) EC modeling, (2) internal convolution and density grid sizes, (3) implementation details in the algorithm, and (4) the accuracy of measurements used for treatment planning system commissioning, the authors recommend an evaluation of the accuracy of near-surface dose calculations as a part of treatment planning commissioning.

Hsu, Shu-Hui; Moran, Jean M.; Chen Yu; Kulasekere, Ravi; Roberson, Peter L. [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan 48109 (United States)

2010-05-15

325

Dose discrepancies in the buildup region and their impact on dose calculations for IMRT fields  

PubMed Central

Purpose: Dose accuracy in the buildup region for radiotherapy treatment planning suffers from challenges in both measurement and calculation. This study investigates the dosimetry in the buildup region at normal and oblique incidences for open and IMRT fields and assesses the quality of the treatment planning calculations. Methods: This study was divided into three parts. First, percent depth doses and profiles (for 5×5, 10×10, 20×20, and 30×30 cm2 field sizes at 0°, 45°, and 70° incidences) were measured in the buildup region in Solid Water using an Attix parallel plate chamber and Kodak XV film, respectively. Second, the parameters in the empirical contamination (EC) term of the convolution?superposition (CVSP) calculation algorithm were fitted based on open field measurements. Finally, seven segmental head-and-neck IMRT fields were measured on a flat phantom geometry and compared to calculations using ? and dose-gradient compensation (C) indices to evaluate the impact of residual discrepancies and to assess the adequacy of the contamination term for IMRT fields. Results: Local deviations between measurements and calculations for open fields were within 1% and 4% in the buildup region for normal and oblique incidences, respectively. The C index with 5%?1 mm criteria for IMRT fields ranged from 89% to 99% and from 96% to 98% at 2 mm and 10 cm depths, respectively. The quality of agreement in the buildup region for open and IMRT fields is comparable to that in nonbuildup regions. Conclusions: The added EC term in CVSP was determined to be adequate for both open and IMRT fields. Due to the dependence of calculation accuracy on (1) EC modeling, (2) internal convolution and density grid sizes, (3) implementation details in the algorithm, and (4) the accuracy of measurements used for treatment planning system commissioning, the authors recommend an evaluation of the accuracy of near-surface dose calculations as a part of treatment planning commissioning. PMID:20527537

Hsu, Shu-Hui; Moran, Jean M.; Chen, Yu; Kulasekere, Ravi; Roberson, Peter L.

2010-01-01

326

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

SciTech Connect

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

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

2010-08-20

327

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

NASA Technical Reports Server (NTRS)

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

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

1973-01-01

328

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

PubMed

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

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

2011-05-01

329

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

PubMed

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

Stanley, Sabine; Bloxham, Jeremy

2004-03-11

330

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

NASA Astrophysics Data System (ADS)

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

Wissing, Livia

2013-04-01

331

What Supports the Parallel Electric Field in the Birkeland (Field-Aligned) Current Regions of the Earth's Magnetosphere?  

NASA Astrophysics Data System (ADS)

Quasi-steady electric fields parallel to the background geomagnetic field exist in both upward and downward Birkeland (field-aligned) current regions above the aurora. These fields, together with the turbulence found on auroral field lines, energize the plasma particles as they flow either away from or toward the earth. In general, these parallel electric fields are supported by one or more strong double layers, the mirror force, the generalized pressure gradient, and the anomalous resistivity due to the turbulence. Recently, and for the first time, we have developed and published a new kinetic and multi-moment fluid, anomalous transport theory that contains the effect of electrostatic turbulence for inhomogeneous, non-uniformly magnetized plasmas [1, 2]. Applying the new theory to observations in a downward-current sheet, we show that anomalous resistivity accounts for only a small portion of the parallel electric field and that contributions from the double layer, mirror force, and generalized pressure gradient terms in the generalized Ohm's law for the problem are more important. Calculations in the double-layer-and-transition-propagation region for a downward-current sheet show that a strong double layer forms, propagates upward at the local ion-acoustic speed, is destabilized as the current falls below the local critical value, and reforms at a lower altitude. These results have important implications in other regions of space such as magnetospheric reconnection sites and solar coronal loops where parallel electric fields are likely to exist. [1] J. R. Jasperse et al. (2006), Phys. Plasmas 13, 072903, and [2] J. R. Jasperse et al. (2006), Phys. Plasmas 13, 112902.

Basu, B.; Jasperse, J. R.; Lund, E. J.; Grossbard, N.

2008-12-01

332

Methane Production Pathways in a California Rice Paddy: Isotopic Evidence for Substantial CO2 Reduction as Cause for Isotopically Light Emitted CH4 Carbon  

NASA Astrophysics Data System (ADS)

We report measurements of ? 13C of emitted CH4 and sediment CH4 and CO2 during the 1999 rice-growing season near Maxwell, CA. Two treatments, one with rice straw incorporated from the previous season and one without rice straw were studied. The ? 13C value of emitted CH4 was consistently lighter isotopically (-67‰ to -83‰ throughout the season) in both straw incorporated and straw removed (burned) plots than in fields we have studied in Texas, Kenya, and Japan. Measured isotopic values of the production zone CH4 were compared to a two-point mixing curve representative of isotopic CH4 produced from either pure methyl-group fermentation or CO2 reduction pathways to partition the production pathways and to track seasonal changes in the production processes. Our sediment CH4 and CO2 isotope data indicate that fermentation was rarely the dominant methanogenic pathway - on the contrary CO2 reduction with H2 was more prevalent than fermentation methanogenesis throughout most of the season. The relatively isotopically light CH4 emitted by the paddy fields is also a product of oxidation and stem-transport processes which have isotopic effects of their own. These effects are discussed in context with the methanogenic isotope effects to provide a complete picture of the paddy field CH4 carbon isotope system.

Tyler, S. C.; McMillan, A. M.; Bearden, K.; Chidthaisong, A.; Macalady, J.

2003-12-01

333

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

PubMed

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

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

2015-01-01

334

Multitemporal crop surface models: accurate plant height measurement and biomass estimation with terrestrial laser scanning in paddy rice  

NASA Astrophysics Data System (ADS)

Appropriate field management requires methods of measuring plant height with high precision, accuracy, and resolution. Studies show that terrestrial laser scanning (TLS) is suitable for capturing small objects like crops. In this contribution, the results of multitemporal TLS surveys for monitoring plant height on paddy rice fields in China are presented. Three campaigns were carried out on a field experiment and on a farmer's conventionally managed field. The high density of measurement points allows us to establish crop surface models with a resolution of 1 cm, which can be used for deriving plant heights. For both sites, strong correlations (each R2=0.91 between TLS-derived and manually measured plant heights confirm the accuracy of the scan data. A biomass regression model was established based on the correlation between plant height and biomass samples from the field experiment (R2=0.86). The transferability to the farmer's field was supported with a strong correlation between simulated and measured values (R2=0.90). Independent biomass measurements were used for validating the temporal transferability. The study demonstrates the advantages of TLS for deriving plant height, which can be used for modeling biomass. Consequently, laser scanning methods are a promising tool for precision agriculture.

Tilly, Nora; Hoffmeister, Dirk; Cao, Qiang; Huang, Shanyu; Lenz-Wiedemann, Victoria; Miao, Yuxin; Bareth, Georg

2014-01-01

335

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

NASA Astrophysics Data System (ADS)

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

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

2005-12-01

336

H-Alpha Velocity Fields of H II Regions in Nearby Dwarf Irregular Galaxies  

E-print Network

We present H-alpha velocity fields of thirteen giant H II regions in four nearby dwarf irregular galaxies, NGC 2366, Holmberg II, IC 2574, and WLM. We classify the velocity features as well as the morphologies of the H II regions. The H-alpha velocity features are divided into three categories; three H II regions show chaotic feature with a typical scale of variation of a few 100 pc in size and a few 10 km s^{-1} in velocity, one shows expanding-bubble feature, and the remaining nine have calm velocity fields. There is a correlation between the H-alpha velocity feature and the morphology of H II regions. We measured bulk motion of the H II regions relative to the ambient H I velocity for the H II regions with calm velocity fields and found a typical velocity difference of about 5 km s^{-1}. We discuss a model for origin of star-forming regions based on the presence of the velocity difference between H-alpha and H I gas as well as the H I characteristics.

A. Tomita; K. Ohta; K. Nakanishi; T. T. Takeuchi; M. Saito

1998-03-19

337

Characterization of scattered acoustic intensity fields in the resonance region of a motionless rigid sphere.  

PubMed

In this study, the properties of the scattered acoustic vector fields generated by simple rigid motionless spheres are investigated. Analytical solutions are derived from general acoustic pressure scattering models, and analyzed for wave numbers in the resonance region. The separable active and reactive components of the acoustic intensity are used to investigate the structural features of the scattered field components. Numerical results are presented. The ability to extract scattered field features is illustrated with measurements obtained from a recent in-air experiment using an anechoic chamber and acoustic intensity probes to measure the scattered acoustic vector field from motionless rigid spheres. PMID:20550226

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

2010-06-01

338

Magnetic field near the central region of the Galaxy: Rotation measure of extragalactic sources  

E-print Network

To determine the properties of the Faraday screen and the magnetic field near the central region of the Galaxy, we measured the Faraday rotation measure (RM) towards 60 background extragalactic source components through the -6 deg < l <6 deg, -2 deg < b < 2 deg region of the Galaxy using the 4.8 and 8.5 GHz bands of the ATCA and VLA. Here we use the measured RMs to estimate the systematic and the random components of the magnetic fields. The measured RMs are found to be mostly positive for the sample sources in the region. This is consistent with either a large scale bisymmetric spiral magnetic fields in the Galaxy or with fields oriented along the central bar of the Galaxy. The outer scale of the RM fluctuation is found to be about 40 pc, which is much larger than the observed RM size scales towards the non-thermal filaments (NTFs). The RM structure function is well-fitted with a power law index of 0.7 +/- 0.1 at length scales of 0.3 to 100 pc. If Gaussian random processes in the ISM are valid, the power law index is consistent with a two dimensional Kolmogorov turbulence. If there is indeed a strong magnetic field within 1 degree (radius 150 pc) from the GC, the strength of the random field in the region is estimated to be 20 microGauss. Given the highly turbulent magnetoionic ISM in this region, the strength of the systematic component of the magnetic fields would most likely be close to that of the random component. This suggests that the earlier estimated milliGauss magnetic field near the NTFs is localised and does not pervade the central 300 pc of the Galaxy.

Subhashis Roy; A. Pramesh Rao; Ravi Subrahmanyan

2007-12-03

339

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

PubMed

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

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

2012-09-01

340

Calculation of electromagnetic fields in the near-field region of a moving scattering object  

Microsoft Academic Search

The problem of scattering of electromagnetic fields by perfectly conducting, moving objects is solved with the Lorentz transformation and the plane wave formulation. Apart from the physical optics approximation, the solution is exact. The result is subsequently applied to the special case of monostatic reflection by an object that moves slowly with respect to the velocity of light. The result

M. H. Vogel

1990-01-01

341

Vertical polarization electric field in the equatorial E-region during days of intense meteor showers  

NASA Astrophysics Data System (ADS)

Rocket observations made from India shows that the electrojet current and the Cowling conductivity profiles estimated using model atmospheric parameters and measured electron density profiles do not maximize at the same height. The height difference in the peaks is more than 3 km. The vertical polarization electric field profile estimated from the conductivity and current profiles indicate an upward gradient that is unrealistic. The role of dust particles in modifying the conductivity profile has recently been discussed. Dust particles of meteoric origin in the E-region can also modify considerably the height profile of the vertical polarization field. Even for a primary east-west electric field, constant with altitude in the E-region, the dust particles, especially the charged ones not only can modify the vertical polarization field but also can reverse the direction of it in the lower E-region altitudes. Such a reversal in the direction of the vertical polarization filed can drive reversed currents in these altitudes with longitudinal and latitudinal extensions controlled by the extension of the dust particles. It should be noted here that the dust particles produce local effects on the vertical polarization field and do not affect the large-scale dynamo electric field. The vertical polarization electric field is estimated for different neutral and charged dust density profiles using model atmospheric parameters.

Muralikrishna, Polinaya; Kulkarni, Vaman

2012-07-01

342

Characteristics of the Region of Interaction between the Interplanetary Plasma and the Geomagnetic Field: Pioneer 5  

Microsoft Academic Search

Measurements of the magnetic fields in the distant geomagnetic cavity and in the region of interaction between the solar wind and the magnetosphere are described. These measurements were' Obtained on March 11, 1960, with instruments aboard the interplanetary probe Pioneer 5 in the'region between 5.2 and 15.4 Re and between 1500 and 1700 local time. The observations obtained between 5.2

Paul J. Coleman

1964-01-01

343

Magnetic field near the central region of the Galaxy: rotation measure of extragalactic sources  

Microsoft Academic Search

Aims:We determine the properties of the Faraday screen and the magnetic field near the central region of the Galaxy. Methods: We measured the Faraday rotation measure (RM) towards 60 background extragalactic source components through the -6° region of the Galaxy using the 4.8 and 8.5 GHz bands of the ATCA and VLA. Here we use the measured

Subhashis Roy; A. Pramesh Rao; Ravi Subrahmanyan

2008-01-01

344

Evaluation of wind field interpolation schemes used in studies of regional-scale pollutant transport  

Microsoft Academic Search

Numerical simulations of regional-scale pollutant transport often use wind fields interpolated from observational data of insufficient spatial resolution. Wind data are interpolated to transient puff positions in Lagrangian models, or to a fixed horizontal grid of about 50 to 100 km spacing in Eulerian finite-difference models. The most common interpolation schemes used in regional-scale simulation are: (1) inverse distance weighting;

Sheih

1983-01-01

345

Simulating Pesticide Leaching and Runoff in Rice Paddies with the RICEWQ–VADOFT Model  

Microsoft Academic Search

toring study was performed in the most important rice area along the Axios River (15000 ha of rice). In the There is a current need to simulate leaching and runoff of pesticide interregional program of the Ministry of Agriculture of from rice (Oryza sativa L.) paddies for assessing environmental impacts on a valuable agricultural system. The objective of this study

Zewei Miao; Mark J. Cheplick; Martin W. Williams; Marco Trevisan; Laura Padovani; Mara Gennari; Aldo Ferrero; Francesco Vidotto; Ettore Capri

2003-01-01

346

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

NASA Astrophysics Data System (ADS)

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

Ho, Adrian; Frenzel, Peter

2010-05-01

347

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

Microsoft Academic Search

China's paddy soils are crucial both for food security through high cereal productivity, and for climate mitigation through high soil carbon storage. These functions are increasingly threatened by widespread heavy metal pollution, resulting from rapid industrial development. Heavy metal-polluted soils generally have a reduced microbial biomass and reduced soil respiration, as well as reduced functional diversity through changes in microbial

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

2010-01-01

348

Paddy soil — A suitable target for monitoring heavy metal pollution by magnetic proxies  

Microsoft Academic Search

A preliminary magnetic study around Meishan steel mill in Nanjing (SE China) was carried out combining geochemical analysis with scanning electron microscopy (SEM) to prove that paddy soil can be a suitable target for environmental study on heavy metal pollution. Magnetic background investigation showed a strong variation in this area due to different land uses and soil types. Magnetic susceptibilities

H. T. Yan; S. Y. Hu; U. Blaha; W. Rösler; X. M. Duan; E. Appel

2011-01-01

349

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

E-print Network

Speciation and Release Kinetics of Zinc in Contaminated Paddy Soils Saengdao Khaokaew,*, Gautier of Plant and Soil Sciences, 152 Townsend Hall, Newark, Delaware 19716, United States U.S. Department is an important nutrient for plants, but it can be toxic at high concentrations. The solubility and speciation

Sparks, Donald L.

350

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

EPA Science Inventory

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

351

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

Microsoft Academic Search

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

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

352

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

SciTech Connect

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

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

2012-11-15

353

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

354

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

355

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

356

The three-dimensional structure of atmospheric magnetic fields in two active regions. [of sun  

NASA Technical Reports Server (NTRS)

The magnetic field above two unrelated active regions on September 11-12, 1974 has been studied by means of magnetograms obtained in C I 9111, Fe I 8688, Ca II 8542, and H-alpha. In C I, originating low in the photosphere, the fields are strong and sharply defined, by contrast with Ca II and H-alpha, where they are very diffuse. The similar diffuseness of Fe I is due to the spreading of the field with height to form nearly horizontal magnetic canopies over regions free of field at lower levels. Within a region between two small sunspots some 140 Mm apart, the canopy height is typically 300-400 km, and it is about 150-250 km within a small superpenumbra. It is hypothesized that the chromospheric fibrils taken to delineate the field configuration are not due primarily to lateral variations in field, but rather to differences in density or excitation of gas across the lines of force.

Giovanelli, R. G.; Jones, H. P.

1982-01-01

357

Calculation of electromagnetic fields in the near-field region of a moving scattering object  

NASA Astrophysics Data System (ADS)

The problem of scattering of electromagnetic fields by perfectly conducting, moving objects is solved with the Lorentz transformation and the plane wave formulation. Apart from the physical optics approximation, the solution is exact. The result is subsequently applied to the special case of monostatic reflection by an object that moves slowly with respect to the velocity of light. The result can be used to predict the time dependent reflection from an aircraft that passes the antenna of a proximity fuze, and the optimum fuze algorithm can be selected.

Vogel, M. H.

1990-07-01

358

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

NASA Astrophysics Data System (ADS)

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

Dias, F.; Assumpcao, M.

2012-12-01

359

Characterization, Identification and Application of Lactic Acid Bacteria Isolated from Forage Paddy Rice Silage  

PubMed Central

There has been growing interest to develop forage rice as a new feed resource for livestock. This study was to characterize the natural population of lactic acid bacteria (LAB) and select potentially excellent strains for paddy rice silage preparation in China. One hundred and twenty-six strains were isolated and screened from paddy rice silage prepared using a small-scale fermentation system, and ninety-nine of these isolates were considered to be LAB based on their Gram-positive and catalase-negative morphology and the production of most of their metabolic products as lactic acid. These isolates were divided into eight groups (A-H) on the basis of their morphological and biochemical characteristics. The Group A to H strains were identified as Lactobacillus (L.) plantarum subsp. plantarum (species ratio: 8.1%), L. casei (5.1%), Leuconostoc (Ln.) pseudomesenteroides (11.1%), Pediococcus (P.) pentosaceus (24.2%), Enterococcus (E.) mundtii (12.1%), Lactococcus (Lc.) garvieae (15.2%), E. faecium (9.1%) and Lc. lactis subsp. lactis (15.2%) based on sequence analyses of their 16S rRNA and recA genes. P. pentosaceus was the most abundant member of the LAB population in the paddy rice silage. A selected strain, namely L. casei R 465, was found to be able to grow under low pH conditions and to improve the silage quality with low pH and a relatively high content of lactic acid. This study demonstrated that forage paddy rice silage contains abundant LAB species and its silage can be well preserved by inoculation with LAB, and that strain R 465 can be a potentially excellent inoculant for paddy rice silage. PMID:25803578

Ni, Kuikui; Wang, Yanping; Li, Dongxia; Cai, Yimin; Pang, Huili

2015-01-01

360

Characterization, identification and application of lactic Acid bacteria isolated from forage paddy rice silage.  

PubMed

There has been growing interest to develop forage rice as a new feed resource for livestock. This study was to characterize the natural population of lactic acid bacteria (LAB) and select potentially excellent strains for paddy rice silage preparation in China. One hundred and twenty-six strains were isolated and screened from paddy rice silage prepared using a small-scale fermentation system, and ninety-nine of these isolates were considered to be LAB based on their Gram-positive and catalase-negative morphology and the production of most of their metabolic products as lactic acid. These isolates were divided into eight groups (A-H) on the basis of their morphological and biochemical characteristics. The Group A to H strains were identified as Lactobacillus (L.) plantarum subsp. plantarum (species ratio: 8.1%), L. casei (5.1%), Leuconostoc (Ln.) pseudomesenteroides (11.1%), Pediococcus (P.) pentosaceus (24.2%), Enterococcus (E.) mundtii (12.1%), Lactococcus (Lc.) garvieae (15.2%), E. faecium (9.1%) and Lc. lactis subsp. lactis (15.2%) based on sequence analyses of their 16S rRNA and recA genes. P. pentosaceus was the most abundant member of the LAB population in the paddy rice silage. A selected strain, namely L. casei R 465, was found to be able to grow under low pH conditions and to improve the silage quality with low pH and a relatively high content of lactic acid. This study demonstrated that forage paddy rice silage contains abundant LAB species and its silage can be well preserved by inoculation with LAB, and that strain R 465 can be a potentially excellent inoculant for paddy rice silage. PMID:25803578

Ni, Kuikui; Wang, Yanping; Li, Dongxia; Cai, Yimin; Pang, Huili

2015-01-01

361

Phase-based Regional Oxygen Metabolism in Magnetic Resonance Imaging at High Field  

E-print Network

Tesla (3T). We also extended our method to high-field human imaging at 7 Tesla (7T), which allows us-susceptibility measurements in magnetic resonance imaging (MRI) have been used to quantify Yv in candidate cerebral veins. However, currently there is no method to quantify regional CMRO2 using MRI. Here we propose a novel

362

Field-Aligned E-Region Irregularities Identified with Acoustic Plasma Waves  

Microsoft Academic Search

This paper describes some measurements related to the nature of field-aligned irregularities in the E region. The measurements were performed near the magnetic equator, and the irregularities are attributed to the equatorial electrojet. It is shown that the irregular- ities are most likely to consist of plane acoustic waves generated by an instability resulting from the flow of current in

K. L. Bowles; B. B. Balsley; Robert Cohen

1963-01-01

363

Tectonic elements of the Arctic region inferred from small-scale geophysical fields  

Microsoft Academic Search

Satellite altimetry data, Bouguer anomalies, anomalous magnetic field, bottom topography, and Love wave tomography for the deepwater part of the Arctic Ocean Basin and East Siberian Sea have made it possible to detect several new regional tectonic elements. The basin area, 700 km wide and 1800 km long, extending from the Laptev Sea to the Chukchi Borderland is a dextral

S. Yu. Sokolov

2009-01-01

364

This version 06 January 2005 Radio Observations of the Hubble Deep Field South region  

E-print Network

This version 06 January 2005 Radio Observations of the Hubble Deep Field South region: I. Survey ABSTRACT This paper is the first of a series describing the results of the Australia Telescope Hubble Deep-S. We 1 Hubble Fellow #12;­ 2 ­ discuss in detail the properties of a subset of these sources

Norris, Ray

365

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

E-print Network

Magnetic field visualization of magnetic minerals and grain boundary regions using magneto to characterize magnetic minerals embedded in a nonmagnetic matrix. We have studied magnetite grains and magnetite. The magneto-optical images resolve directly magnetic structures on length scales ranging from millimeter down

Podladchikov, Yuri

366

Mapping land-surface fluxes of carbon, water and energy from field to regional scales  

Technology Transfer Automated Retrieval System (TEKTRAN)

A framework for routine mapping of land-surface fluxes of carbon, water, and energy at the field to regional scales has been established for drought monitoring, water resource management, yield forecasting and crop-growth monitoring. The framework uses the ALEXI/DisALEXI suite of land-surface model...

367

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

Microsoft Academic Search

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

Masahiro Fujioka

1998-01-01

368

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

SciTech Connect

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

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

2010-02-19

369

Magnetic Fields and Mass Inflow in Central Regions of Barred Galaxies  

NASA Astrophysics Data System (ADS)

Radio continuum emission is an excellent tracer of star formation in central regions of galaxies. We observed a sample of 20 galaxies with massive bars. The regular magnetic fields around the bar, as traced by the polarized emission, do not always follow the gas flow predicted from numerical simulations and show little compression by the shock. The galaxies with the longest bars show the strongest deviations of the magnetic field pattern from axial symmetry, and most of them host nuclear rings. The total magnetic fields in these nuclear rings of up to ~= 100 ?G are among the strongest fields known in spiral galaxies. The regular field in the nuclear ring of NGC 1097 is of spiral shape. Magnetic stress in the ring can drive mass inflow of about one solar mass per year which is sufficient to feed the active nucleus. This process may also work in non-barred galaxies.

Beck, Rainer; Ehle, Matthias; Fletcher, Andrew; Harnett, Julienne; Shoutenkov, Vladimir; Shukurov, Anvar; Sokoloff, Dmitry

2005-08-01

370

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

NASA Astrophysics Data System (ADS)

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

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

371

On open and closed field line regions in Tsyganenko's field model and their possible associations with horse collar auroras  

SciTech Connect

Using the empirical Tsyganenko (1987) long model as a prime example of a megnetospheric field model, the authors have attempted to identify the boundary between open and closed field lines. They define as closed all field lines that are connested with the Earth at both ends and cross the equatorial plane earthward of x = {minus}70 R{sub E}, the tailward validity limit of the Tsyganenko model. They find that the form of the open/closed boundary at the Earth's surface, identified with the polar cap boundary, can exhibit the arrowhead shape, pointed toward the Sun, observed in horse collar auroras (Hones et al., 1989). The polar cap size in the Tsyganenko model increases with increasing K{sub p} values, and it becomes rounder and less pointed. The superposition of a net B{sub y} field, which is the expected consequence of an IMF B{sub y}, rotates the polar cap pattern and, for larger values, degrades the arrowhead shape, resulting in polar cap configurations consistent with known asymmetries in the aurora. The pointedness of the polar cap shape also diminishes or even completely disappears if the low-latitude magnetopause is assumed open and located considerably inside of the outermost magnetic flux surface in the Tsyganenko model. The arrowhead shape of the polar cap is found to be associated with a strong increase of B{sub z} from midnight toward the tail flanks, which is observed independently, and is possibly related to the NBZ field-aligned current system, observed during quiet times and strongly northward IMF B{sub z}. The larger B{sub z} values near the flanks of the tail cause more magnetic flux to close through these regions than through the midnight equatorial region.

Birn, J.; Hones, E.W. Jr. (Los Alamos National Lab., NM (USA)); Craven, J.D.; Frank, L.A. (Univ. of Iowa, Iowa City (USA)); Elphinstone, R.D. (Univ. of Calgary, Alberta (Canada)); Stern, D.P. (NASA Goddard Space Flight Center, Greenbelt, MD (USA))

1991-03-01

372

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

373

Diazinon Accumulation and Dissipation in Oryza sativa L. Following Simulated Agricultural Runoff Amendment in Flooded Rice Paddies  

Microsoft Academic Search

Flooded post-harvest rice paddies were examined as systems for reducing diazinon (organophosphate insecticide) concentrations\\u000a in stormwater runoff. Two paddies were cultivated in Oryza sativa L. and amended with a 3-h simulated stormwater diazinon runoff event. Initial diazinon adsorption peaked at 347 and 571 ?g\\u000a kg?1 (3% mass load reduction) for mean above-ground plant tissue concentrations in each pond, respectively. Subsequent senescence

R. Kröger; M. T. Moore; C. M. Cooper; M. M. Holland

2009-01-01

374

The methods to consolidate scattered tenanted lots into large rice paddy lots by the land consolidation projects in Japan  

Microsoft Academic Search

Today in Japan, agricultural productivity of rice cropping farmers is low. In order to get sufficient agricultural productivity,\\u000a Japanese government is encouraging enlarging core farmers' farm sizes to 10–20 ha by borrowing farm lots from retiring farmers\\u000a of small farms and carrying out the land consolidation projects to construct large rice paddy lots. In order to realize large\\u000a rice paddy lots

Atsushi Ishii

2005-01-01

375

A modified pool permutation procedure for short regional climate model simulations nested within analyzed fields  

NASA Astrophysics Data System (ADS)

Short regional climate model simulations are routinely compared with observations, though because of extremely small sample sizes (often only a single season or year is simulated) it is generally difficult to establish whether any model-reality differences are statistically significant. In the following, a permutation technique is proposed to estimate the statistical significance of similarities between spatial fields as simulated by a regional climate model, and observations, when the climate model is nested within operational analyses (i.e. “perfect” lateral boundary conditions). To illustrate the technique, we consider a short simulation over the Mackenzie River Basin of northwestern Canada made using the Canadian Regional Climate Model, and focus our attention on accumulated monthly precipitation and monthly average screen temperature. For comparison we have a 45 year gridded, monthly climate dataset produced by the Meteorological Service of Canada over the same region, based on adjusted operational climate station data.

MacKay, Murray D.

2000-08-01

376

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

SciTech Connect

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

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

2011-09-10

377

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

378

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

379

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...

380

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...

381

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...

382

The magnetic field structure of the central region in M 31  

NASA Astrophysics Data System (ADS)

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

Gießübel, R.; Beck, R.

2014-11-01

383

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

384

Novel anaerobic ultramicrobacteria belonging to the Verrucomicrobiales lineage of bacterial descent isolated by dilution culture from anoxic rice paddy soil.  

PubMed Central

The use of dilution culture techniques to cultivate saccharolytic bacteria present in the anoxic soil of flooded rice microcosms allowed the isolation of three new strains of bacteria, typified by their small cell sizes, with culturable numbers estimated at between 1.2 x 10(5) and 7.3 x 10(5) cells per g of dry soil. The average cell volumes of all three strains were 0.03 to 0.04 microns3, and therefore they can be termed ultramicrobacteria or "dwarf cells." The small cell size is a stable characteristic, even when the organisms grow at high substrate concentrations, and thus is not a starvation response. All three strains have genomic DNA with a mol% G+C ratio of about 63, are gram negative, and are motile by means of a single flagellum. The three new isolates utilized only sugars and some sugar polymers as substrates for growth. The metabolism is strictly fermentative, but the new strains are oxygen tolerant. Sugars are metabolized to acetate, propionate, and succinate. Hydrogen production was not significant. In the presence of 0.2 atm of oxygen, the fermentation end products or ratios did not change. The phylogenetic analysis on the basis of 16S ribosomal DNA (rDNA) sequence comparisons indicates that the new isolates belong to a branch of the Verrucomicrobiales lineage and are closely related to a cloned 16S rDNA sequence (PAD7) recovered from rice paddy field soil from Japan. The isolation of these three strains belonging to the order Verrucomicrobiales from a model rice paddy system, in which rice was grown in soil from an Italian rice field, provides some information on the possible physiology and phenotype of the organism represented by the cloned 16S rDNA sequence PAD7. The new isolates also extend our knowledge on the phenotypic and phylogenetic depths of members of the order Verrucomicrobiales, to date acquired mainly from cloned 16S rDNA sequences from soils and other habitats. PMID:9097435

Janssen, P H; Schuhmann, A; Mörschel, E; Rainey, F A

1997-01-01

385

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

386

Magnetic fields of active galactic nuclei and quasars with regions of polarized broad H ? lines  

NASA Astrophysics Data System (ADS)

Estimates of magnetic fields for a number of active galactic nuclei are presented. These estimates are based on the observed polarization degrees and position angles of broad H ? lines and in the nearby continuum and on asymptotic analytical formulas for the Stokes parameters of the radiation emerging from a magnetized accretion disk (the Milne problem in a magnetized atmosphere). The characteristic observed feature of the wavelength dependence of the polarization degree inside the line—a minimum at the center and a fast increase of the position angle from one wing to another—can be explained by the superposition of resonance emission from two or more clouds located in the right (Keplerian velocity directed away from the observer) and left (Keplerian velocity directed toward the observer) parts of the orbit in the rotating magnetized accretion disk. The main component in our mechanism is the azimuthal magnetic field in the disk. The presence of a magnetic field perpendicular to the disk plane (which is usually weaker than the azimuthal field) results in the asymmetry of the distribution of the polarization degree and position angle inside the line. The inferred magnetic field strengths at the galactocentric distances where broad lines are emitted can be used to estimate the magnetic fields in the region of the centermost stable orbit and at the horizon of the central black hole, using the power-law dependence of the magnetic field strength corresponding to the standard model of the accretion disk.

Silant'ev, N. A.; Gnedin, Yu. N.; Buliga, S. D.; Piotrovich, M. Yu.; Natsvlishvili, T. M.

2013-01-01

387

E region electric fields at the dip equator and anomalous conductivity effects  

NASA Astrophysics Data System (ADS)

Zonal and vertical electric fields were estimated at E region heights in the Brazilian sector. Zonal electric fields are obtained from the vertical electric fields based on their relation through the Hall-to-Pedersen ionospheric conductivities ratio. The technique for obtaining the vertical electric field is based on its proportionality to the Doppler velocities of type 2 irregularities as detected by coherent radars. The 50 MHz backscatter coherent (RESCO) radar was used to estimate the Doppler velocities of the type 2 irregularities embedded in the equatorial electrojet. A magnetic field-line integrated conductivity model was developed to provide the conductivities. It considers a multi-species ionosphere and a multi-species neutral atmosphere, and uses the IRI 2007, the MISIS 2000 and the IGRF 10 models as input parameters for ionosphere, neutral atmosphere and Earth's magnetic field, respectively. The ion-neutral collision frequencies of all the species are combined through the momentum transfer collision frequency equation, and different percentages of electron-neutral collisions were artificially included for studying the implication of such increase in the zonal electric field, which resulted ranging from 0.13 to 0.49 mV/m between the 8 and 18 h (LT), under quiet magnetic conditions.

Denardini, C. M.; Aveiro, H. C.; Sobral, J. H. A.; Bageston, J. V.; Guizelli, L. M.; Resende, L. C. A.; Moro, J.

2013-05-01

388

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

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

389

Entanglement entropy for non-coplanar regions in quantum field theory  

NASA Astrophysics Data System (ADS)

We study the entanglement entropy in a relativistic quantum field theory for regions which are not included in a single spatial hyperplane. This geometric configuration cannot be treated with the Euclidean time method and the replica trick. Instead, we use a real time method to calculate the entropy for a massive free Dirac field in two dimensions in some approximations. We find some specifically relativistic features of the entropy. First, there is a large enhancement of entanglement due to boosts. As a result, the mutual information between relatively boosted regions does not vanish in the limit of zero volume and large relative boost. We also find extensivity of the information in a deeply Lorentzian regime with large violations of the triangle inequalities for the distances. This last effect is relevant to an interpretation of the amount of entropy enclosed in the Hawking radiation emitted by a black hole.

Blanco, David D.; Casini, Horacio

2011-11-01

390

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

NASA Technical Reports Server (NTRS)

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

Ohtani, S.; Potemra, T. A.; Newell, P.T.; Zanetti, L. J.; Iijima, T.; Watanabe, M.; Blomberg, L. G.; Elphinstone, R. D.; Murphree, J. S.; Yamauchi, M.

1995-01-01

391

Using the full tensor of GOCE gravity gradients for regional gravity field modelling  

NASA Astrophysics Data System (ADS)

With its 3-axis gradiometer GOCE delivers 3-dimensional (3D) information of the Earth's gravity field. This essential advantage - e.g. compared with the 1D gravity field information from GRACE - can be used for research on the Earth's interior and for geophysical exploration. To benefit from this multidimensional measurement system, the combination of all 6 GOCE gradients and additionally the consistent combination with other gravity observations mean an innovative challenge for regional gravity field modelling. As the individual gravity gradients reflect the gravity field depending on different spatial directions, observation equations are formulated separately for each of these components. In our approach we use spherical localizing base functions to display the gravity field for specified regions. Therefore the series expansions based on Legendre polynomials have to be adopted to obtain mathematical expressions for the second derivatives of the gravitational potential which are observed by GOCE in the Cartesian Gradiometer Reference Frame (GRF). We (1) have to transform the equations from the spherical terrestrial into a Cartesian Local North-Oriented Reference Frame (LNOF), (2) to set up a 3x3 tensor of observation equations and (3) finally to rotate the tensor defined in the terrestrial LNOF into the GRF. Thus we ensure the use of the original non-rotated and unaffected GOCE measurements within the analysis procedure. As output from the synthesis procedure we then obtain the second derivatives of the gravitational potential for all combinations of the xyz Cartesian coordinates in the LNOF. Further the implementation of variance component estimation provides a flexible tool to diversify the influence of the input gradiometer observations. On the one hand the less accurate xy and yz measurements are nearly excluded by estimating large variance components. On the other hand the yy measurements, which show systematic errors increasing at high latitudes, could be manually down-weighted in the corresponding regions. We choose different test areas to compute regional gravity field models at mean GOCE altitudes for different spectral resolutions and varying relative weights for the observations. Further we compare the regional models with the static global GOCO03S model. Especially the flexible handling and combination of the 3D measurements promise a great benefit for geophysical applications from GOCE gravity gradients, as they contain information on radial as well as on lateral gravity changes.

Lieb, Verena; Bouman, Johannes; Dettmering, Denise; Fuchs, Martin; Schmidt, Michael

2013-04-01

392

Field quality in Fermilab-built models of quadrupole magnets for the LHC interaction region  

Microsoft Academic Search

Superconducting quadrupole magnets for the interaction regions of the Large Hadron Collider are being developed by the US-LHC Accelerator Project. These 70 mm bore quadrupole magnets are intended to operate in superfluid helium at 1.9 K with a nominal field gradient of 215 T\\/m. A series of 2 m model magnets has been built and cold tested at Fermilab to

N. Andreev; T. Arkan; P. Bauer; R. Bossert; J. Brandt; S. Caspi; D. R. Chichili; J. Carson; J. DiMarco; S. Feher; A. Ghosh; H. Glass; V. V. Kashikhin; J. Kerby; M. J. Lamm; A. D. McInturff; A. A. Makarov; A. Nobrega; I. Novitski; T. Ogitsu; D. Orris; J. P. Ozelis; T. Peterson; R. Rabehl; W. Robotham; G. Sabbi; R. Scanlan; P. Schlabach; C. Sylvester; J. Strait; M. Tartaglia; J. C. Tompkins; G. Velev; S. Yadav; A. V. Zlobin

2001-01-01

393

Tectonic elements of the Arctic region inferred from small-scale geophysical fields  

Microsoft Academic Search

Satellite altimetry data, Bouguer anomalies, anomalous magnetic field, bottom topography, and Love wave tomography for the\\u000a deepwater part of the Arctic Ocean Basin and East Siberian Sea have made it possible to detect several new regional tectonic\\u000a elements. The basin area, 700 km wide and 1800 km long, extending from the Laptev Sea to the Chukchi Borderland is a dextral

S. Yu. Sokolov

2009-01-01

394

The Dynamical Character of the Holocene Paleomagnetic Field: Evidence from the North America Region  

NASA Astrophysics Data System (ADS)

We have developed a new compilation of paleomagnetic time series spanning the past 8000 years - PSVMOD2.0. PSVMOD2.0 now consists of 185 PSV time series (inclination, declination, or intensity) from 85 global sites, including 30 full-vector records (inclination, declination, intensity). In almost all cases, the sediment relative paleointensity records have been normalized to absolute intensity values based on comparisions to nearby absolute archeomagnetic records. Time series data have advantages over isolated spot measurements in that they can provide an independent assessment of data quality, chronology and accuracy by comparisons between successive epochs and between spatially adjacent records. We are using these time series for two types of field analysis: spherical harmonic analysis and high-resolution, regional studies of field variability. We have broken up PSVMOD2.0 into seven study regions for individual studies. We present here new results from one region - North America. A subset of our North American time series was previously studied by Lund (JGR, 1996). Lund (1996) used unit-vector directions (no paleointensity) from 9 sites comprising 18 time series. We are using 21 sites with 53 time series (inclination, declination, and paleointensity), of which 12 sites have full vector records. Our sites cover twice the spatial region of the Lund (1996) study. We have replicated all of the conclusions of Lund (1996) documenting no appreciable long-term drift of the field and evidence for strong looping of the directional field. We have also found clear evidence for two time-scales of open looping and our paleointensity studies let us note for the first time that the directional circularity is matched by centennial-millennial scale intensity variability.

Lund, S.; Burton, M. E.

2013-12-01

395

Dense and stagnant ions in the low-latitude boundary region under northward interplanetary magnetic field  

Microsoft Academic Search

The ion behavior in the low-latitude boundary region is studied based on Geotail data accumulated over several years, toward understanding the formation mechanism of the cold-dense plasma sheet under prolonged northward interplanetary magnetic field (IMF). A statistical survey shows that, during extended northward IMF, (1) dense magnetosheath-like ions appear far more often, especially on the flanks, (2)