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Your search keyword '"Nakao, Atsushi"' showing total 299 results
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299 results on '"Nakao, Atsushi"'

1. Impact of radiocesium contamination in flood sediment deposited after the 2019 typhoon on decontaminated fields of Fukushima Prefecture, Japan

Author

Asano, Ikumi, Harada, Nodoka, Nakao, Atsushi, Evrard, Olivier, and Yanai, Junta

Subjects
Cesium-137 ($^{137}\mathrm{Cs}$), Radiocesium, Flood sediment, Decontaminated field, Fukushima, Geophysics. Cosmic physics, QC801-809, Chemistry, QD1-999, Geology, QE1-996.5
Abstract

Sediment that has deposited after the flood generated by the 2019 typhoon (referred to as Flood Sediment, FS) was collected along two rivers in eastern Fukushima Prefecture, Japan to determine the total and exchangeable radiocesium ($^{137}\mathrm{Cs}$), and acid-extractable potassium (K) contents. Then, these FS parameters were compared with those of decontaminated soils (DS) in nearby agricultural fields to discuss the potential transfer risk of $^{137}\mathrm{Cs}$ from rivers to nearby remediated soils. While FS had about four times higher total $^{137}\mathrm{Cs}$ content, it showed a three-times lower exchangeable $^{137}\mathrm{Cs}$ content than DS. Furthermore, acid-extractable K referred to as non-exchangeable K (Nex-K) content was high enough to restrict $^{137}\mathrm{Cs}$ transfer from soil to crops for both FS and DS. From these comparisons, we concluded that deposition of FS onto DS may not increase the transfer of $^{137}\mathrm{Cs}$ from soil to crops.

Published
2022
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2. Impact of the 2019 typhoons on sediment source contributions and radiocesium concentrations in rivers draining the Fukushima radioactive plume, Japan

Author

Evrard, Olivier, Durand, Roxanne, Nakao, Atsushi, Patrick Laceby, J., Lefèvre, Irène, Wakiyama, Yoshifumi, Hayashi, Seiji, Asanuma-Brice, Cécile, and Cerdan, Olivier

Subjects
Source tracing, Sediment fingerprinting, Nuclear accident, Catchment, Cesium-137 ($^{137}$Cs), Geophysics. Cosmic physics, QC801-809, Chemistry, QD1-999, Geology, QE1-996.5
Abstract

The Fukushima nuclear accident in March 2011 generated a 3000 km$^{2}$ plume of soils heavily contaminated with $^{137}$Cs. Decontamination was completed early in 2019. Typhoon Hagibis was the first extreme event that occurred in the region after decontamination. Its impact on sediment sources and sediment $^{137}$Cs contamination was investigated through the application of a sediment fingerprinting procedure using spectrocolorimetry and geochemical properties. Sediment deposits ($n=24$) were collected in the Mano and Niida River catchments after the 2019 typhoons, and their signature was compared to that of potential sources (e.g., cropland, forests, and subsurface; $n=57$). Results demonstrate the dominance of cropland as the main source of sediment (mean: 54%) followed by forests (41%) with much lower contributions of subsurface material (5%). Overall, $^{137}$Cs concentrations in sediment were on average 84%–93% lower than the levels recorded after the accident in 2011, which demonstrates the effectiveness of cropland decontamination.

Published
2020
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3. Disentangling the pedogenic factors controlling active Al and Fe concentrations in soils of the Cameroon volcanic line

Author

Watanabe, Tetsuhiro, Ueda, Shiori, Nakao, Atsushi, Ze, Antoine Mvondo, Dahlgren, Randy A, and Funakawa, Shinya

Subjects
Environmental Sciences, Biological Sciences, Agricultural and Veterinary Sciences, Agronomy & Agriculture
Abstract

Active Al, Fe and Si (i.e., oxalate extractable fraction: Alo, Feo, Sio) strongly affect soil physical, chemical and biological properties. This study examined the pedogenic factors affecting Alo, Feo and Sio contents across a soil weathering sequence in the Cameroon volcanic line. We investigated the B horizon (∼50-cm depth) from 26 soils formed in basaltic materials at different elevations (110–2570 m) incorporating a wide range of temperature (14–27 °C) and precipitation (1520–3130 mm). The weathering sequence ranged from weakly weathered Andisols in the southwest region grading to strongly weathered Oxisols on the central highlands. We assumed pyrophosphate extractable Al/Fe (Alp/Fep) as organo-Al/Fe complexes, and Sio, (Alo − Alp) and (Feo − Fep) as short-range-order (SRO) minerals. Factor analysis of climatic (e.g., temperature and precipitation/leaching metrics) and soil geochemical properties (e.g., weathering indices) identified three independent factors representing temperature/dry season intensity, weathering degree and precipitation/leaching as the primary determinants of Alo, Feo and Sio concentrations. Organo-metal complexes (Alp and Fep) were negatively correlated with the temperature/dry season intensity factor, whereas the SRO mineral phases (Sio, Alo − Alp and Feo − Fep) were negatively correlated with weathering degree. The precipitation/leaching factor positively correlated with Alo, Feo and Sio. Our analysis infers that low temperature promotes the formation and preservation of organo-Al/Fe complexes, whereas weathering degree is more critical for SRO minerals. Further, increased weathering and a drier climate enhance the formation of crystalline clay minerals at the expense of SRO minerals. Allophanic materials (Sio) were evident (Sio: 9–43 g kg−1) only in weakly weathered soils. However, low allophanic contents were found in more highly weathered soils (Sio: 2–7 g kg−1) accompanied by high Alp and Fep, suggesting the importance of volcanic parent materials as a direct source of Al and Fe via weathering for the formation of organo-metal complexes. In sum, we clarified the discriminatory effects of climatic factors and degree of weathering in regulating the composition of the active Al, Fe and Si fractions along the Cameroon volcanic line.

Published
2023

14. Materials and Methods

Author

Yanai, Junta, Tanaka, Sota, Nakao, Atsushi, Abe, Shin, Yanai, Junta, editor, Tanaka, Sota, editor, Abe, Shin, editor, and Nakao, Atsushi, editor

Published
2022
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22. Effects of long-term application of inorganic fertilizer and organic amendments on the amounts of fractionated soil organic carbon and their determining factors in paddy fields

Author

Nishimura, Chinari, primary, Yanai, Junta, additional, Nakao, Atsushi, additional, Ando, Kaori, additional, Oga, Toshiya, additional, Otake, Toshiya, additional, Taki, Katsutoshi, additional, Kasuya, Masahiro, additional, Takayama, Takayuki, additional, Hasukawa, Hiroyuki, additional, Takehisa, Kunihiko, additional, Takahashi, Tomoki, additional, Togami, Kazuki, additional, Takamoto, Akira, additional, and Funakawa, Shinya, additional

Published
2024
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28. Effects of long-term application of inorganic fertilizers and organic amendments on the turnover rates of fractionated soil organic carbon and their determining factors in paddy fields.

Author

Yanai, Junta, Nishimura, Chinari, Nakao, Atsushi, Ando, Kaori, Oga, Toshiya, Otake, Toshiya, Taki, Katsutoshi, Kasuya, Masahiro, Takayama, Takayuki, Hasukawa, Hiroyuki, Takehisa, Kunihiko, Takahashi, Tomoki, Togami, Kazuki, Takamoto, Akira, Haraguchi, Takashi, F., Tayasu, Ichiro, and Funakawa, Shinya

Subjects
ORGANIC fertilizers, PADDY fields, FERTILIZER application, ACCELERATOR mass spectrometry, CARBON in soils
Abstract

To investigate how the long-term application of inorganic fertilizer and organic amendments affects the turnover rates of organic matter in physico-chemically fractionated components in paddy soils and how their rates are related to their amounts, we studied the effect of variable management of inorganic fertilizer and organic amendments for > 50 years on the ∆14C values of accumulated soil organic carbon (SOC) in fractionated components of 5 soil samples from three paddy fields. SOC was fractionated into four components based on their physico-chemical properties: (1) light fraction (LF) derived from plant residues, (2) heavy fraction (HF) containing stable aggregates, (3) oxidizable fraction (OxF) and (4) non-oxidizable fraction (NOxF) forming organo-mineral complexes with fine-textured minerals. The ∆14C values were determined by accelerator mass spectrometry using graphitized samples. The ∆14C values of SOC in NOxF (from −305‰ to − 90.5‰) were much lower than those of HF (from −123‰ to − 3.7‰) and OxF (from −215‰ to 21.0‰). Lowest values for NOxF suggested slowest turnover rates as expected, and higher and comparable values for OxF and HF implied much faster turnover rates of SOC in OxF compared with upland soils. This could be one of the characteristics of SOC dynamics in paddy soils, probably reflecting repeated puddling of plow layer soils. ∆14C values in all the fractions increased in response to the application of inorganic fertilizer and organic amendments, suggesting faster turnover rate. Soils with clayey and weathered characteristics had the lowest ∆14C values, or slowest turnover rates among the study fields. The relationship between the ∆14C value and the amount of accumulated C for HF, OxF and NOxF indicated that the more the SOC accumulated, the faster the turnover rate of the SOC was, regardless of the fractions, and the relationship of the HF was considerably different from those of OxF and NOxF. In conclusion, these results can be the basis for understanding the C dynamics and for improving soil fertility status and soil C sequestration in paddy soils. [ABSTRACT FROM AUTHOR]

Published
2024
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36. Adjoint-based data assimilation for reconstruction of thermal convection in a highly viscous fluid from surface velocity and temperature snapshots.

Author

Nakao, Atsushi, Kuwatani, Tatsu, Ito, Shin-ichi, and Nagao, Hiromichi

Subjects
*SURFACE temperature, *EARTH'S mantle, *INTERNAL structure of the Earth, *COST functions, *EARTH temperature, *SURFACE waves (Seismic waves), *FLUID-structure interaction
Abstract

It is a general problem in geoscience to estimate the time-series of velocity and temperature fields for a fluid based on limited observations, such as the flow velocity at the fluid surface and/or a temperature snapshot after flow. In this study, an adjoint-based data assimilation method (also known as 4-D variational data assimilation) was used to reconstruct the thermal convection in a highly viscous fluid (e.g. Earth's mantle) to investigate which observations constrain the thermal convection and how accurately the convection can be reconstructed for different wavelengths. The data assimilated to the adjoint-based model were generated synthetically from forward models with convecting cells of different length-scales. Based on the surface velocity and temperature snapshot, our simulations successfully reconstructed thermal convection over 50 Myr in the case that the wavelength of the convective cells is sufficiently large. We obtained two main results from this parametric study. (1) When we only considered instantaneous thermal structure fitting in the cost function, the convection reconstruction tended to fail. However, there are some cases where the laminar thermal convection can be reconstructed by assimilating only the velocity along the fluid surface. (2) There is a limit to the reconstruction of thermal convection in the case that the convecting cells are small (∼1000 km for a 50 Myr reconstruction). We propose that (1) is related to the balance of forces due to the thermal buoyancy and viscous stress around the thermal anomalies and (2) is related to how information is preserved (i.e. how the previous thermal structure is maintained in the observable state throughout the convection process). The results enable the use of geological records to estimate time-series of velocity and temperature in Earth's deep interior, even though the records may only contain information from shallow parts of Earth. [ABSTRACT FROM AUTHOR]

Published
2024
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40. Neonatal Outcomes of Very Low Birth Weight and Very Preterm Neonates: An International Comparison

Author

Badawi, Nadia, Marshall, Peter, Craven, Paul, Simmer, Karen, Stack, Jacqueline, Casalaz, Dan, Carse, Elizabeth, Cooke, Lucy, Shingde, Vijay, Cartwright, David, Hunt, Rod, Kilburn, Charles, Dargaville, Peter, Lui, Kei, Paradisis, Mary, Rieger, Ingrid, Kuschel, Carl, Numa, Andrew, Carlisle, Hazel, Koh, Guan, Andersen, Chad, Luig, Melissa, Austin, Nicola, Broadbent, Roland, Mildenhall, Lindsay, Battin, Malcolm, Bourchier, David, Richardson, Vaughan, Synnes, Anne, Rouvinez-Bouali, Nicole, Piedboeuf, Bruno, Bulleid, Barbara, Yee, Wendy, Singhal, Nalini, Harrison, Adele, Tan-Dy, Cherrie, Shivananda, Sandesh, Tan, Kenneth, James, Andrew, Seshia, Molly, Barrington, Keith, Lefebvre, Francine, McMillan, Doug, Andrews, Wayne, Kovacs, Lajos, Dow, Kimberly, Clarke, Maxine, Riley, Patricia, Shah, Prakesh, Ohlsson, Arne, Aziz, Khalid, Peliowski, Abraham, Cieslak, Zenon, Sorokan, Todd, Kalapesi, Zarin, Ninan, Abraham, Sankaran, Koravangattu, Faucher, Daniel, Cronin, Gerarda, Canning, Roderick, da Silva, Orlando, Lee, David, Ojah, Cecil, Dunn, Michael, Heymann, Eli, Zangen, Shmuel, Kushnir, Amir, Mimouni, Francis, Bader, David, Rothschild, Avi, Strauss, Zipora, Felszer, Clari, Jeryes, Jamalia, Even Tov-Friedman, Smadar, Bar-Oz, Benjamin, Feldman, Michael, Saad, Nizar, Flidel-Rimon, Orna, Weisbrod, Meir, Lubin, Daniel, Litmanovitz, Ita, Blazer, Shraga, Shinwell, Eric, Sirota, Leah, Nijim, Yousif, Golan, Agneta, Mandel, Dror, Fleisher-Sheffer, Vered, Kohelet, David, Bakhrakh, Lev, Hattori, Satoshi, Konishi, Shohei, Amizuka, Takasuke, Kasai, Takeo, Takahasi, Ritsuko, Arai, Hirokazu, Sato, Maki, Miyazono, Yayoi, Shimizu, Junichi, Suzumura, Hiroshi, Kono, Yumi, Inoue, Takahiro, Miyabayashi, Hiroshi, Sobajima, Hisanori, Ishiguro, Rika, Sato, Hiroyuki, Totsu, Satsuki, Ishii, Nozomi, Hosono, Shigeharu, Shiraishi, Mika, Miura, Humihiro, Nakao, Atsushi, Yoda, Hitoshi, Shimizu, Mitsumasa, Seki, Kazuo, Itani, Yasuhumi, Suzuki, Keiji, Nemoto, Atsushi, Nakamura, Tomohiko, Wada, Masaki, Nagayama, Yoshihisa, Numata, Osamu, Futatani, Takeshi, Ueno, Yasuhisa, Iwai, Kazuyuki, Kono, Yoshinori, Ooki, Shigeru, Nakazawa, Yusuke, Suzuki, Chizuko, Tanaka, Taihei, Bonno, Motoki, Nakamura, Kenji, Kihara, Minako, Sano, Hiroyuki, Shiraishi, Atsushi, Ohashi, Atsushi, Ichiba, Hiroyuki, Sumi, Kiyoaki, Yoshimoto, Seiji, Takahashi, Yukihiro, Okutani, Takahiro, Miura, Masumi, Kato, Fumihide, Watabe, Shinichi, Kageyama, Misao, Fukuhara, Rie, Hayashitani, Michiko, Hasegawa, Keiko, Koyano, Kosuke, Kobayashi, Shoko, Akiyoshi, Shinosuke, Nakata, Yusei, Kanda, Takeshi, Tadashi, Hisano, Kanda, Hiroshi, Nakamura, Masaki, Matsumoto, Naoko, Ochiai, Masayuki, Aoki, Mikihiro, Kawase, Akihiko, Iida, Koichi, Ishihara, Chie, Kohama, Moriyasu, Seara, M<ce:sup loc='post">a</ce:sup> José Fernández, Bermúdez, José M<ce:sup loc='post">a</ce:sup> Fraga, Martínez Gutiérrez, Andrés, Martínez Ayúcar, María Mercedes, Díaz, Carolina Vizcaíno, Quiles Durá, José Luis, González Santacruz, María, Siguile, M<ce:sup loc='post">a</ce:sup> Anne Feret, Fernández, Adela Rodríguez, Fernández Colomer, Belén, García López, Enrique, Figuera Aloy, Josep, Botet Mussons, Francesc, Anquela Sanz, Israel, Galiana, Gemma Ginovart, Moliner Calderon, Elisenda, Pujol, Antonio Natal, Vives, Alicia Mirada, Iriondo Sanz, Martín, Porta, Roser, Cogul, Eva Capdevila, Castells Vilella, Laura, Álvarez, Bruno Alonso, Montero Macarro, José María, Barrio Sacristán, Ana R., Cuesta, M<ce:sup loc='post">a</ce:sup> Jesús López, Tardío, Ortiz, Sánchez Puerta, Eugenia Valls, Benavente Fernández, Isabel, Romero, Juan Mena, Martinez Gimenez, María Dolores, Olmos, Ramón Aguilera, Segura, Ricardo Tosca, Cabañas, Juana M<ce:sup loc='post">a</ce:sup> Guzmán, Muñoz, M<ce:sup loc='post">a</ce:sup> Dolores Huertas, Trujillo, Alberto, Moltó Ripoll, Luis Fidel, Hurtado Suazo, José Antonio, Aldea Romero, Ana Elena, Grisolía, Luis Paisán, Garrido Ocana, Ana Isabel, Soblechero, Eduardo Garcia, Ruiz del Prado, M<ce:sup loc='post">a</ce:sup> Yolanda, Díez, Inés Esteba, González-Luis, Gema E., García-Muñoz Rodrigo, Fermín, Iglesias, Emilio Álvaro, Calvo, Fernando Fernandez, Solé Mir, Eduard, Martí, Jordi Garcia, Ortiz Movilla, Roberto, Vilaplana, Lucía Cabanillas, San Miguel, Marta García, Martín, Isabel Llana, Díaz, María Fernández, Pérez Rodríguez, Jesús, Salas, Sofía, Labian, Carmen Muñoz, González Armengod, Carmen, Comeche, Laura Domingo, Sánchez Tamayo, Tomás, García del Río, Manuel, Alonso Gallego, José Ángel, Lloreda Garcia, José María, González, Javier Vilas, Ocampo, Insunza, Nieves Balado, García González, Pilar, Granero Asencio, Mercedes, Sanz, Antonia López, Díaz, Carmen Macías, Ferrari Cortés, Araceli, Fuster Jorge, Pedro Amadeo, López Mendoza, Santiago, Ramírez, Sabina Romero, Font, M<ce:sup loc='post">a</ce:sup> del Mar Albújar, de Ureta Huertas, Alicia, Plana, Antonio Arroyos, Capell, Javier Estañ, Roqués, Vicente, Morcillo, F., Marín, Sara, Omaña, María Fernanda, Iturriaga, Gabriel Saitua, Kofron, Jiri, Brodd, Katarina Strand, Odlind, Andreas, Alberg, Lars, Arwehed, Sofia, Engström, Eva, Kasemo, Anna, Ekelund, Charlotte, Åhman, Lars, Ingemarsson, Fredrik, Österdahl, Laura, Thurn, Pernilla, Albinsson, Eva, Selander, Bo, Lundberg, Fredrik, Heimdahl, Ingela, Hafström, Ola, Wejryd, Erik, Kuusima-Löfbom, Johanna, Lund, Ellen-Elisabeth, Thorén, Annelie, Hallberg, Boubou, Broström, Eva Berggren, Hertzberg, Torbjörn, Stjernstedt, Björn, Robinson, Johan, Farooqi, Aijaz, Normann, Erik, Fredriksson, Magnus, Palm, Anders, Hedblom, Åsa, Sjöberg, Kenneth, Thorbjörnsson, Leif, Ohlin, Andreas, Florell, Rein, Smedsaas-Löfvenberg, Agneta, Meyer, Philipp, Anderegg, Claudia, Schulzke, Sven, Nelle, Mathias, Wagner, Bendicht, Bär, Walter, Kaczala, Grégoire, Pfister, Riccardo E., Tolsa, Jean-François, Roth, Matthias, Berger, Thomas M., Laubscher, Bernhard, Malzacher, Andreas, Micallef, John P., Hegi, Lukas, Bassler, Dirk, Arlettaz, Romaine, Bernet, Vera, Bag, Santanu, Kefas, Jonathan, Rackham, Oliver, Thirumurgan, Arumugavelu, Yoxall, Bill, McBride, Tim, Webb, Delyth, Amegavie, Laweh, Hassan, Ahmed, Ambadkar, Priyadarshan, Dyke, Mark, Babiker, Seif, Rubin, Susan, Ogilvy-Stuart, Amanda, Panasa, Nagesh, Settle, Paul, Moise, Jonathan, Edi-Osagie, Ngozi, Heal, Carrie, Birch, Jacqeline, Hasib, Abdul, Soe, Aung, Kumar, Niraj, Kisat, Hamudi, Vasu, Vimal, Lama, Meera, Gupta, Richa, Rawlingson, Chris, Wickham, Tim, Schwarz, Karin, Sommen, Van, Watkin, Sara, Gupta, Aashish, Aladangady, Narendra, Ali, Imdad, Alsford, Lesley, Mannan, Khalid, Rainer, Ebel, Wilson, Nicholas, Thomas, Mark, Mathur, Ramnik, Cruwys, Michele, Godambe, Sunit, Watts, Timothy, Kuna, Jauro, Chang, John, Filkin, Jon, Huddy, Charlotte, Shephard, Ruth, Zieba, Krzystof, Rao, Patti, Currie, Andrew, Manzoor, Azhar, Ahmed, Munir, Simmons, Phil, Nycyk, Julie, Gallagher, Andrew, Halahakoon, Chrisantha, Deshpande, Sanjeev, Mohite, Anand, Palmer, Kate, Gibson, Alan, Garbash, Mehdi, Lal, Mithilesh, Abu-Harb, Majd, McKeon-Carter, Róisín, Selter, Michael, Munyard, Paul, Lewis, Vaughan, Raman, Mala, Whincup, Graham, Mallik, Abdus, Amess, Philip, Godden, Charles, Reynolds, Peter, Misra, Indranil, Shettihalli, Naveen, De Halpert, Peter, Salgia, Sanjay, Sanghavi, Rekha, Wigfield, Ruth, Deketelaere, Abby, Khashu, Minesh, Hall, Michael, Groves, Charlotte, Brown, Nick, Brennan, Nick, Vamvakiti, Katia, Ratnayaka, Mal, Pirie, Simon, Jones, Stephen, Mannix, Paul, Harding, David, Eaton, Megan, Gibson, David, Miall, Lawrence, Shah, Prakesh S., Sjörs, Gunnar, Mirea, Lucia, Reichman, Brian, Adams, Mark, Modi, Neena, Darlow, Brian A., Kusuda, Satoshi, San Feliciano, Laura, Yang, Junmin, Håkansson, Stellan, Mori, Rintaro, Figueras-Aloy, Josep, and Lee, Shoo K.

Published
2016
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43. Use of soil nonexchangeable potassium by paddy rice with clay structural changes under long‐term fertilizer management

Author

Yanai, Junta, primary, Inoue, Nanami, additional, Nakao, Atsushi, additional, Kasuya, Masahiro, additional, Ando, Kaori, additional, Oga, Toshiya, additional, Takayama, Takayuki, additional, Hasukawa, Hiroyuki, additional, Takehisa, Kunihiko, additional, Takamoto, Akira, additional, Togami, Kazuki, additional, and Takahashi, Tomoki, additional

Published
2023
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44. Trans-Pacific Multicenter Collaborative Study of Minimally Invasive Proximal Versus Total Gastrectomy for Proximal Gastric and Gastroesophageal Junction Cancers

Author

Ikoma, Naruhiko, primary, Grotz, Travis, additional, Kawakubo, Hirofumi, additional, Kim, Hyoung-Il, additional, Matsuda, Satoru, additional, Hirata, Yuki, additional, Nakao, Atsushi, additional, Williams, Lori, additional, Wang, Xin, additional, Mendoza, Tito, additional, Wang, Xuemei, additional, Badgwell, Brian, additional, Mansfield, Paul, additional, Hyung, Woo-Jin, additional, and Kitagawa, Yuko, additional

Published
2023
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49. Interactive effect of parent material and topography on spatial variability of paddy soil material characteristics in the alluvial plain.

Author

Ito, Ryo, Yanai, Junta, and Nakao, Atsushi

Subjects
ALLUVIAL plains, TOPOGRAPHY, SOIL composition, SOIL topography, PARTICLE size distribution, FLUVISOLS
Abstract

To investigate the interactive effects of parent material and topography as soil forming factors, we examined the distribution of soil materials in an alluvial plain, where two types of surface geology were situated upstream and different parent materials supplied accordingly. We hypothesized that these two types of parent material make it possible to trace alluvial processes by analyzing their spatial distribution based on soil physicochemical properties. We collected 101 soil samples from the alluvial plain and nine soil samples from two types of unmixed upstream areas, i.e., granite and mélange. Particle size distributions and total concentrations of 32 elements were analyzed for spatial variabilities. Elemental composition of unmixed upstream samples and isarithmic maps of elemental composition of the soils in the alluvial plain based on geostatistical analysis revealed that gravel, coarse sand and total Na, Al, K, Ca, and Mn concentrations were higher at the southern part close to granite rock areas, whereas silt+clay content and total C, N, Mg, Ti, and Fe concentrations were higher at the northern part close to the mélange area, suggesting strong influence from parent material. In contrast, fine sand content and total P and Si concentrations showed west-east trends, suggesting topography effects reflecting particle size selection. Directional semivariograms suggest coarse sand and silt+clay content, as well as total C, N, Na, Mg, Al, K, Ca, Ti, and Mn concentrations were more strongly affected by parent material, whereas gravel and fine sand and total P concentration were more strongly affected by topography. Accordingly, the combination of elemental composition analysis and geostatistics revealed that the contribution of parent material and topography to total elemental contents in paddy surface soils in the alluvial plain varied among elements. In conclusion, evaluation of the interactive effects of parent material and topography on spatial variability of soil material characteristics enabled better understanding of soil formation processes and their potential fertility. [ABSTRACT FROM AUTHOR]

Published
2023
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