Motohei Kanayama
Kyushu University
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Communications in Soil Science and Plant Analysis | 2010
Nguyen Thi Lan Huong; Masami Ohtsubo; Loretta Y. Li; Takahiro Higashi; Motohei Kanayama
The To Lich and Kim Nguu Rivers, laden with untreated waste from industrial sources, serve as sources of water for irrigating vegetable farms. The purposes of this study were to identify the impact of wastewater irrigation on the level of heavy metals in the soils and vegetables and to predict their potential mobility and bioavailability. Soil samples were collected from different distances from the canal. The average concentrations of the heavy metals in the soil were in the order zinc (Zn; 204 mg kg−1) > copper (Cu; 196 mg kg−1) > chromium (Cr; 175 mg kg−1) > lead (Pb; 131 mg kg−1) > nickel (Ni; 60 mg kg−1) > cadmium (Cd; 4 mg kg−1). The concentrations of all heavy metals in the study site were much greater than the background level in that area and exceeded the permissible levels of the Vietnamese standards for Cd, Cu, and Pb. The concentrations of Zn, Ni, and Pb in the surface soil decreased with distance from the canal. The results of selective sequential extraction indicated that dominant fractions were oxide, organic, and residual for Ni, Pb, and Zn; organic and oxide for Cr; oxide for Cd; and organic for Cu. Leaching tests for water and acid indicated that the ratio of leached metal concentration to total metal concentration in the soil decreased in the order of Cd > Ni > Cr > Pb > Cu > Zn and in the order of Cd > Ni > Cr > Zn > Cu > Pb for the ethylenediaminetetraaceitc acid (EDTA) treatment. The EDTA treatment gave greater leachability than other treatments for most metal types. By leaching with water and acid, all heavy metals were fully released from the exchangeable fraction, and some heavy metals were fully released from carbonate and oxide fractions. The concentrations of Cd, Cr, Cu, Ni, Pb, and Zn in the vegetables exceeded the Vietnamese standards. The transfer coefficients for the metals were in the order of Zn > Ni > Cu > Cd = Cr > Pb.
Paddy and Water Environment | 2008
Nguyen Thi Lan Huong; Masami Ohtsubo; Loretta Y. Li; Takahiro Higashi; Motohei Kanayama
The To Lich and Kim Nguu Rivers in Hanoi City are the main sources of irrigation water for suburban agricultural land and fish farm. Wastewater from the industrial plants located along these rivers has been discharged, and has degraded the water quality of the rivers. This study describes the chemical properties of water from the rivers, focusing on heavy metal pollution and the suitability of water quality for irrigation water. Water from the rivers was heavily polluted with organic matter and heavy metals such as Pb, Cu, Zn, Cr, Cd and Ni. Dissolved oxygen, chemical oxygen deman, and total suspended solids, and the concentrations of all heavy metals exceeded the Vietnamese standard for surface water quality in all investigated sites. The concentrations of some heavy metals such as Cu, Cd, Cr and Ni were above the internationally recommended WHO maximum level for irrigation water. A wide variation in the heavy metal concentration of water due to metal types is the result of wastewater discharged from different industrial sources.
Marine Georesources & Geotechnology | 2015
Phanny He; Masami Ohtsubo; Takahiro Higashi; Motohei Kanayama
This study aims to determine whether the principle that “divalent cation predominance in the pore water precludes quick clay development” applies to the Ariake Bay sediments. The chemical and geotechnical properties of an Ariake clay sediment are presented, and sensitivity is discussed with a focus on pore-water salinity and cation composition. In recent years, reduction of pore-water salinity has occurred due to permeation of river water through the sediments because of overpumping of groundwater. Sodium remains the dominant pore-water cation in an upper zone, whereas divalent cations are dominant in the deeper zone. Divalent cation domination in the deeper zone is ascribed to Ca release from nearby cement-stabilized sediments and to Mg increase in response to a change in river water quality. The upper zones sensitivity ranged from 15 to 77, and the remolded strength was mostly <0.5 kPa, such that quick clay was present over much of its depth. In contrast, the deeper zones sensitivity was <40, and its remolded strength exceeded 0.5 kPa; quick clay was not present despite the <2 g/L salinity. The absence of quick clay is ascribed to the high remolded strength caused by the pore-water divalent to monovalent cation ratio being greater than 0.25.
Soil & Sediment Contamination | 2012
Nguyen Thi Lan Huong; Masami Ohtsubo; Takahiro Higashi; Motohei Kanayama
The heavy metal pollution of sediment in the Nhue River, which receives wastewater from the To Lich and Kim Nguu River system, was investigated together with the effects of use of this water for irrigation of the surrounding farmland. Eighty soil samples and 40 sediment samples were collected from six locations in the Nhue River and two locations in the To Lich River for chemical and physical analyses. The results showed that the sediments in the Nhue River are heavily polluted by metals (71–420 mg/kg for Cu, 77–433 mg/kg for Pb, 150–350 mg/kg for Zn, 0.7–8.7 mg/kg for Cd, 80– 583 mg/kg for Cr, and 32–70 mg/kg for Ni). There were positive correlations between heavy metal concentration and both clay and organic matter contents in the sediment samples. The concentrations of all metals in soil samples were much higher than the background levels in the farmland, Cd, Cu, and Pb, exceeding Vietnamese standards for agricultural grounds.
Journal of Astm International | 2009
Masami Ohtsubo; Takahiro Higashi; Motohei Kanayama; S. Inoue; Yuji Oshima
Tributyltin (TBT) is used as effective antifouling agents in boat paints and has been found to be present in marine and freshwaters ecosystem at concentrations exceeding acute and chronic toxicity levels. In the present study, horizontal and vertical TBT distributions in the sediment of Hakata Bay, Japan, have been investigated. Basic properties of the sediment such as clay mineralogy, particle size and organic matter content were also determined, and their relations with TBT concentrations in the sediment were discussed, focusing on organic matter. Sediments in the study sites consist mostly of clay soil with clay fraction of 21 % to 35 %, and major clay minerals in the sediments were smectite, followed by vermiculite, illite, and kaolinite. TBT concentration in overlying water ranged from 13 to 94 ng⋅L−1 at locations within the harbor, and from 13 to 32 ng⋅L−1 at locations outside of the harbor. TBT concentration in top 3 cm sediment varied from 0.018 to 1.101 mg⋅kg−1. Sorption coefficient was in a range of 1.03 to 5.7×103 (L kg−1) for sediments at most stations, and on the order of 104 for sediments with higher organic matter content. The organic matter content and TBT concentration in sediments changed with depth in a similar pattern at all stations. The organic matter decreased with depth up to 12 cm and was almost constant below 12 cm. TBT concentrations appeared to be higher at depth above 12 cm than below 12 cm. A positive correlation was observed between TBT concentration and organic matter content for all core samples data. According to other researchers, an increase in TBT concentration due to increase in organic matter appears to be the results of sorption of TBT+ on negatively charged surfaces of organic matter as well as hydrophobic sorption of TBT compounds on organic matter.
1st International Workshop on Characterisation and Engineering Properties of Natural Soils | 2007
Masami Ohtsubo; T. Higashi; Motohei Kanayama; M. Takayama
International Journal of Soil, Sediment and Water | 2010
Huong Thi Lan Nguyen; Masami Ohtsubo; Loretta Y. Li; Takahiro Higashi; Motohei Kanayama
Geotechnical and Geological Engineering | 2014
Motohei Kanayama; Alexander Rohe; Leon A. van Paassen
International Journal of Soil, Sediment and Water | 2010
Huong Thi Lan Nguyen; Masami Ohtsubo; Loretta Y. Li; Takahiro Higashi; Motohei Kanayama
International Journal of Geosciences | 2014
Phanny He; Masami Ohtsubo; Hiroshi Abe; Takahiro Higashi; Motohei Kanayama