Methanogenic bacterial populations in some lowland paddy field soils of Burkina Faso (West Africa)

In wetland ecosystems, such as rice fields, methanogenic bacteria (MB) play important roles in global carbon cycling as terminal organic decomposers and in hydrogen cycling as hydrogen consumers, leading to methane production (Jorgensen 1982). In the global atmosphere, concentration of methane has been increasing by about 1% per year (Blake and Rowland 1986; Bouwman 1989; Dlugokensky et al. 1994) and it is considered that 80% is of biological origin (Seiler 1984). The environmental impact of methane on global warming has also been confirmed (Chappellaz et al. 1990). Rice paddy fields contribute to an estimated 10% of the global methane emission (Bouwman 1989; IPCC 1992) and the intensification of paddy cultivation may contribute considerably to the gradual increase of atmospheric methane (Rasmussen and Khalil 1981). From 1970 to 1990, rice production increased by 110% in West Africa (FAO 1970, 1990), as a direct result of encroachment on new lands throughout most of West Africa (Windmeijer and Andriesse 1993; Issaka et al. 1996a, b). In Burkina Faso, about 85% of the rice cultivation areas are lowlands (Sié 1991). In recent years, many studies on methane emission from paddy fields and limited ecological studies on methanogenic populations have been conducted (Schütz et al. 1989; Asakawa and Hayano 1995; Adachi et al. 1996). However, studies on both methane emission and populations of methanogens in African paddy fields are very limited. Garcia et al. (1974) enumerated methanogenic populations in Sénégal rice soils by the most probable number (MPN) method. With the gradual increase in the land area under rice cultivation, more information is needed on methane fluxes, populations, and species of methanogens in paddy fields of West Africa. We reported here the enumeration of methanogenic populations in the soils of lowland paddy fields located in the Sudan and Guinea Savanna zones of Burkina Faso (West Africa) by the MPN method.     

Characterization of plasma membrane-bound Fe3+-chelate reductase from Fe-deficient and Fe-sufficient cucumber roots

Abstract

One of the authors analyzed the brown spot symptoms developed on plant leaves caused by nutritional disorders using an X-ray Micro-Analyser (Sasaki et al. 1980). The use of an X-ray Fluorescence Element Mapping Spectrometer (XEMS) revealed that external and internal stresses such as X-ray irradiation and manganese excess induced the transport of manganese, and excess of manganese concentration as cationic Mn²⁺ was related to the formation of the abnormal brown spots (Watanabe and Kobayashi 1986; Watanabe et al. 1988). Since, the mechanism of the transport of manganese remains to be elucidated the analysis of the chemical state of manganese in plant is important. Since the valency of manganese readily changes depending on the redox potential, non-destructiye analysis may be effective. In fact, few studies have been carried out on the non-destructive determination of the manganese state in plant tissues. We studied the state of manganese in rice leaf in performing Extended X-ray Absorption Fine Structure (EXAFS) and X-ray Absorption Near Edge Structure (XANES) analyses by X-ray Absorption Spectrometry with syncrotron radiation as the analytical source. X-ray absorption spectrometry provides structural information about the local surroundings of a metal ion, the binding configuration, etc. The concept and method of analysis were reviewed in detail by Teo (1981). The advantage of these methods over the previous methods is reported and the state and transport of manganese in leaf are discussed.     

Methane uptake by unflooded paddy soils

Abstract

Methane (CH₄) is one of the most abundant organic gases in the atmosphere. Recently the importance of CH₄ as a greenhouse gas has been recognized and studies have been carried out to assess its contribution to global warming. Although the rate of increase has slowed down in the last decade (Steel et al. 1992; Rudolph 1994), the results from some of these studies have shown that the atmospheric concentration of CH₄ is increasing at a rate estimated to be approximately 1% per year (Rowland 1991; Blake and Rowland 1988; Bolle et al. 1986; Graedel and McRae 1980). Clearly it is important to identify sources and sinks of CH₄, in both terrestrial and oceanic ecosystems, in order to estimate global methane budgets (Cicerone and Oremland 1988).     

Methanogenic Characteristics of Flooded Rice Soils in Response to Glucose Amendment

Extract

It was reported that flooded rice soil was an important source of atmospheric CH₄ (Cicerone and Shetter 1981; Sciler et al. 1984). In flooded rice soils, CH₄ is produced under strict anaerobic conditions by methanogenic bacteria (Jones et al. 1987; Jones 1991). Rice plants carry the produced CH₄ from anoxic sediment and release it to the atmosphere (Cicerone and Shetter 1981; Nouchi et al. 1990). More than 90% of emitted CH₄ is released through rice plants and the emission pattern usually shows large seasonal variations (Cicerone et al. 1983; Sciler et al. 1984; Inubushi et al. 1989). Since the number of methanogens did not change throughout the rice growth season (Schutz et al. 1989; Mayer and Conrad 1990), seasonal variations of CH₄ emission could be ascribed to the activities of methanogens and the amount of available substrates. However, the changes in the methanogenic activities in response to available substrates especially in relation to the growth period of rice plants are poorly documented.     

磷素迁移的动力学方程

Studies on kinetics of adsorption and release of phosphorus by soil, a new field in soil chemistry, began only over ten years ago (He et al., 1989; Wang and Zhu, 1988; Zhang and Zhang, 1991; Lin, 1989; Lin and Xue, 1989; Jiang, 1993; Xue et al., 1995; Lü et al., 1997). The stress of this field is laid on the speed at which a soil system reaches balance between adsorption and release of phosphorus. Being more close to the field condition and helpful to explain the mechanism of adsorption and release of the phosphorus by the soil, kinetic methods have attracted much attention of the researchers (Aharoni et al., 1991; Griffin and Jurinak, 1974). Different kinetic equations have been used to describe the characteristics of the adsorption and release of phosphorus by the soil (He et al., 1989; Wang and Zhu, 1988; Lü et al., 1997); however, until now which equations are better remains a point of debate. Phosphorus transport in soil is, in fact, a comprehensive process, which includes adsorption, fixation and release of phosphorus by the soil. This study aimed to determine equations useful for describing phosphorus transport process through fitting the phosphorus transport processes in four soils sampled from Shaanxi Province using 17 types of kinetics equations selected.     

Shoot control of nodulation is modified by the root in the supernodulating soybean mutant En6500 and its wild-type parent cultivar Enrei

Abstract

Based on grafting studies, both supernodulating (Carroll et al. 1985a, b) and hypernodulating (Gremaud and Harper 1989) soybean ([itGlycine max} L. Merr.) phenotypes were reported to be under the control of shoot factors (Delves et al. 1986, 1987; Cho and Harper 1991). Recently Akao and Kouchi (1992) have isolated a new supernodulating mutant (En6500) from ethyl methane sulfonate (EMS)-treated Enrei, a cultivar which is widely grown in the central districts of Japan. This mutant has been shown to produce several fold as many nodules as its wild-type parent cultivar when grown at a low concentration (0.5 mol m^-3) of nitrate. Moreover, it exhibited a continuous increase in the nodule number with the increasing nitrate concentration, even at 15 mol m^-3 (Francisco et al. 1992), in contrast to the similar mutant nts382 in which the nodulation decreased even at the relatively low nitrate level of 5.5 mol m^-3 (Carroll et al. 1985a). In this study we conducted grafting experiments to determine which plant part controls the supernodulation of En6500.     

Enrichment of natural 15N abundance in frankia-infected nodules

Abstract

The enrichment of ¹⁵N in the nodules of some N₂-fixing leguminous plants is an interesting finding (Shearer et al. 1982). The extent of ¹⁵N enrichment differed depending on the plant species (Shearer et al. 1982; Yoneyama 1987) and bacterial strains (Steele et al. 1983), and in soybeans it was apparently related to the nitrogen fixation efficiency (Shearer et al. 1984)     

Comparison of community structures of microbiota at main habitats in rice field ecosystems based on phospholipid fatty acid analysis

The present study compares the community structures of microbiota at different habitats in Japanese rice fields by comparing their phospholipid fatty acid (PLFA) compositions to understand the contribution of different habitats to microbiological diversity. The data were collected from four neighboring rice fields. Comparison was made for the PLFA compositions extracted from the floodwater, percolating water, rice soils under flooded and drained conditions, rice straw (RS) placed in flooded and drained rice soils, RS in the composting process, and RS compost placed in a flooded rice field. Average amounts of PLFAs were 33 μg L⁻¹ in the floodwater, 17.1 μg L⁻¹ in the percolating water from plow layers, 34.6 μg L⁻¹ in the percolating water from subsoil layers, 108 μg g⁻¹ dry weight basis (dw) in flooded rice soils, 382 μg g⁻¹ dw in RS materials, 2,510 μg g⁻¹ dw in RS composts, 2,850 μg g⁻¹ dw in RS composts after application to a flooded rice soil, 222 μg g⁻¹ wet weight basis (ww) in RS in drained rice soils, and 284 μg g⁻¹ ww in RS in flooded rice soils. The total amount of PLFAs to the soil depth of 10 cm was estimated to be about 12 g m⁻². The PLFA compositions were different from each other depending on the habitats. Rice soils were characterized by the predominance of actinomycetes and Gram-positive bacteria in comparison with the other habitats. In contrast, the microbial communities in the floodwater and percolating water were characterized by the predominance of Gram-negative bacteria and eukaryotes (presumably algae), and Gram-negative bacteria, respectively. The microbial community of RS materials was dominated by fungi. Gram-positive bacteria became predominant in RS after application to flooded rice soils, while RS placed in a drained rice field after harvesting rice was characterized by the predominance of Gram-negative bacteria and fungi. The community structures at respective habitats were stable and specific, irrespective of the season of sampling and the duration of decomposition of RS.     

Increase in phosphorus availability of upland Andosol under different fertilization conditions measured by isotopic techniques

In Japan, since about 50% of upland fields are covered with Andosols, in which phosphorus (P) supplied by fertilizer is likely to be immobilized, there is a large accumulation of P in upland soil (Agriculture, Forestry and Fisheries Research Council 1991). However, information on the changes in the availability of accumulated P under long-term field conditions is very limited.

In order to analyze the effect of continuous application of compound fertilizer and farmyard manure on the changes in P compounds and their availability to crop plants in the plow layer of an upland Andosol, a long-term field trial has been carried out in an experimental field of Tokyo University of Agriculture and Technology, Tokyo, Japan since November, 1982. The results obtained in the field trial demonstrated that although crop growth in the plot without P fertilizer application was more reduced than that in the plot with P fertilizer application during each stage of the trial, the differences in crop growth between the plots became attenuate as time passed. These findings suggest that in the plot without P fertilizer application, soil P that accumulated before the start of the trial became available for the growth of crops as time passed (Hirata 1997).

While Truog and Bray No.2 methods have been traditionally used for routine analysis of available soil P in Japan, it has been recently reported that P extraction by these methods led to an overestimation of the amount of available soil P (Kato et al. 1995b). It was reported that the L-value measured by the isotopic dilution method and E-value measured by the isotopic exchange kinetic method were more suitable for estimating the amount of available soil P (Russel et al. 1957; Dalal and Hallsworth 1976; Tran et al. 1988; Kato et al. 1995a, b), and that isotope techniques could become valuable tools for understanding the P dynamics in soil-plant systems (Di et al. 1997).

In the present report, we carried out investigations on P availability in soils taken from plots differing in P fertilizer application in the above trial over a period of 13.5 y by using the ³²P isotopic dilution method and the isotopic exchange kinetic method.     

The carbon cycle and global forest ecosystem

Attempts to account for the fluxes by quantifying C sources and sinks have provided evidence of a missing C sink (Detwiler and Hall, 1988), which may be located somewhere in the temperate region of the northern hemisphere (Tanset al., 1990). Until recently, most estimates have concluded that the temperate forest is a small C source. Two recent papers (Sedjo, 1992; Kauppiet al., 1992) provided evidence that the temperate forests are substantial C sinks. This paper combines these earlier findings on temeperate forest carbon sequestration with a new estimate of the annual C releases due to tropical deforestation, 1.7 Gt, which is obtained using the FAO estimates of the rate of deforestation in the tropics over the decade of the 1980s and conservative estimates of C releases associated with this deforestation. Finally, to this is added the crude estimate of C export by the global river system found in Hallet al. (1992). Applying these estimates of the C sink function of both temperate and tropical forests to Detwiler and Hall's alternative C budgets largely eliminates the “missing C” hypothesized by Detwiler and Hall, and Tanset al.     

Sesbania spp., Aeschynomene indica and Crotalaria spp. are amide-exporters

Abstract

Extract

Leguminous plants consist of two groups, amide-exporting and ureide-exporting plants. The former legumes export a large fraction of fixed-N in the form of amides (asparagine and glutamine), and the latter legumes in the form of ureides (allantoic acid and allantoin). Another characteristic of the nodules is the enrichment in ¹⁵N. There are two types of legumes: one characterized by the enrichment with ¹⁵N in N₂-fixing nodules, in contrast to the other where the enrichment does not occur. The first investigation by Shearer et al. (1982) suggested that the nodules exporting fixed-N in the form of ureides were enriched in ¹⁵N unlike those exporting it in the form of amides. Soybeans, mungbean, and cowpea belong to the former group and groundnut, alfalfa, white clover to the latter. Although pea and faba bean were first classified into the latter group (Shearer et al. 1982), a recent investigation (Yoneyama 1988) showed that these nodules were also enriched in ¹⁵N.     

Methane emission from an Indonesian rainfed paddy field

In relation to global warming, a great deal of attention has been paid to methane (CH4 ) emission from paddy fields. The amount of CH₄ emitted from paddy fields is now estimated to account for about 12% of the total CH₄ emission according to Prather et al. (1995). Harvested area of rough rice in Asia covered 1,320,000 km² in 1990 and 38% of the area was estimated to be maintained under rainfed conditions (IRRI 1991).     

Comparative toxicity of Al3+, Yb3+, and La3+ to root-tip cells differing in tolerance to high Al3+ in terms of ionic potentials of dehydrated trivalent cations

Abstract

Green manure legumes are often used to compare biomass production as well as nitrogen-fixing capacity. Mineral deficiency often limits the symbiotic nitrogen fixation of many legumes, thus limiting their productivity despite their high yielding potential (O’Hara et al. 1988; Flis et al. 1993). Leguminous species require large amounts of P for growth, nodulation, and nitrogen fixation. Consequently, they are often unable to grow in acid soils with low available P. The low P availability in tropical acid soils often arises from fixation of P by Al and Fe in soil. Generally, Al and Fe-phosphates are relatively unavailable to plants (McLachlan 1976; Ae et al. 1990).     

Development of QSAR's in soil ecotoxicology: Earthworm toxicity and soil sorption of chlorophenols,chlorobenzenes and chloroanilines

Soil adsorption and the toxicity of four chloroanilines for earthworms were investigated in two soil types. The toxicity tests were carried out with two earthworm species, Eisenia andrei and Lumbricus rubellus. LC₅₀ values in mg kg^?1 dry soil were recalculated towards molar concentrations in pore water using data from soil adsorption experiments. An attempt has been made to develop Quantitative Structure Activity Relationships (QSAR's) using these results and data on five chlorophenols and dichloroaniline in four soils and five chlorobenzenes in two soils published previously (Van Gestel and Ma, 1988, 1990; Van Gestel et al., 1991). Significant QSAR relationships were obtained between 1) adsorption coefficients (log K _om ) and the octanol/water partition coefficient (log k _ow ), and 2) LC₅₀ values (in itμmol L^?1 soil pore water) and log K _ow . It can be concluded that both earthworm species tested are equally sensitive to chlorobenzenes and chloroanilines, E. andrei is more sensitive than L. rubellus to chlorophenols.     

Field measurement of carbon dioxide evolution from soil by a flow-through chamber method using a portable photosynthesis meter

Extract

Since a rise in atmospheric carbon dioxide (CO₂) concentration is expected to lead to global warming, it is important to quantify the global carbon circulation. The CO₂ evolution rate from soil has usually been measured by one of three methods: 1) CO₂ absorption (Anderson 1982), where the evolved CO₂ is absorbed in an alkali solution and the content subsequently determined, 2) closed chamber (Rolston 1986) in which the CO₂ evolution rate is calculated from the increase of the CO₂ concentration in a closed chamber covering the soil surface, and 3) flow-through chamber (Rolston 1986) in which a fixed rate of ambient air is pumped through an open chamber and the difference in the. CO₂ concentration between the inlet and the outlet is measured. Although the CO₂ absorption method is very simple in terms of apparatus and procedure, the determined CO₂ evolution rate tends to be underestimated in cases where the evolved CO₂ is not fully absorbed in the alkali solution (Ewel et al. 1987; Sakamoto and Yoshida 1988), or overestimated in cases where the CO₂ concentration in the chamber is too low to stimulate microbial activity (Koizumi et al. 1991; Nakadai et al. 1993), In the closed chamber method, when the gas concentration in the chamber is higher than that of the ambient air, gas diffusion from the soil to the atmosphere is restricted (Denmead 1978). At this point, the flow-through chamber method seems to be most suitable for measuring the CO₂ evolution rate, because the rate is determined under nearly natural conditions. However, this method has a disadvantage in that the apparatus is composed of an infra-red CO₂ analyzer, air pumps, mass flow meters, a recorder, and other items, which are too large, heavy, and complex to use in the field (Freijer and Bouten 1991). Hence, in spite of the above limitations, most of the studies on CO₂ evolution in situ have been carried out using the CO₂ absorption method (Kowalenko et al. 1978; Seto et al. 1978a, b; Ewel et al 1981, 1987; Gupta and Singh 1981; Reinke et al. 1981; Edwards and Ros-Todd 1983; Grahammer et al. 1991) or the closed chamber method (Naganawa et al. 1989; Mariko et al. 1994). The flow-through chamber method has been used only at sites where electric power supply and other types of equipment were available (Mathes and Schriefer 1985; Ewel et al. 1987; Nakadai et al. 1993). In the present report a flow-through chamber method using a portable CO₂ analyzer system was examined, for the determination of CO₂ evolution from soil without an electric power supply or other special equipment.     

Desert system microbial biomass determined by phospholipid phosphate and muramic acid measurement

The effect of soil moisture on the biomass of the natural microbial communities in the Negev Desert was studied during 1991–1993 using measurements of phospholipid phosphate and muramic acid. The immediate response of the microbial communities to varying amounts of nitrogen added as a single pulse was also studied. Two different weather conditions were observed during the study period: (1) the winter of 1992, which was very cold and snowy, with intermittent rainfall occurring at the end of winter and beginning of spring; (2) the winter of 1993 which was warmer, without snow, but with periodical rainfall occurring through early spring. Soil samples collected from the 0–10 cm and 10–20 cm depths during 1991–1992 showed significant changes in soil moisture and phospholipid phosphate and muramic acid concentrations following precipitation events. The greatest concentration of phospholipid phosphate was observed in December 1991. The concentrations of phospholipid phosphate at the two sample depths were 4–50 times greater than those found during other months. The concentration of muramic acid (31·19 mg g⁻¹) was greatest in March at 0–10 cm depth, as compared with the greatest concentration (46·37 mg g⁻¹) at 10–20 cm depth, which occurred in January. These muramic acid concentrations were 2–3 times greater than those found during other months. In 1992–93, soil samples were collected from 0–10 cm depth areas amended with three different concentrations of nitrogen (25, 50 or 100 kg NH₄NO₃ ha⁻¹) and from unamended soil. Fluxes of the microbial communities (phospholipid phosphate and muramic acid) were correlated with the nitrogen treatments and diurnal fluctuations in soil moisture. The greatest concentrations of phospholipid phosphate and muramic acid were found in soil treated with 50 or 100 kg NH₄NO₃ ha⁻¹. Our results demonstrated that phospholipid phosphate and muramic acid concentrations were greatest and more stable after nitrogen addition than in control soils lacking nitrogen amendments. This paper demonstrates that the soil microbiota in the Negev Desert ecosystem are dependent on the moisture and nitrogen content of the soil and are influenced by seasonal variations in weather conditions, as well as by individual precipitation levels.     

Effect of land use on the abundance and diversity of autotrophic bacteria as measured by ribulose-1,5-biphosphate carboxylase/oxygenase (RubisCO) large subunit gene abundance in soils

Elucidating the biodiversity of CO₂-assimilating bacterial communities under different land uses is critical for establishing an integrated view of the carbon sequestration in agricultural systems. We therefore determined the abundance and diversity of CO₂ assimilating bacteria using terminal restriction fragment length polymorphism and quantitative PCR of the cbbL gene (which encodes ribulose-1,5-biphosphate carboxylase/oxygenase). These analyses used agricultural soils collected from a long-term experiment (Pantang Agroecosystem) in subtropical China. Soils under three typical land uses, i.e., rice–rice (RR), upland crop (UC), and paddy rice–upland crop rotation (PU), were selected. The abundance of bacterial cbbL (0.04 to 1.25?×?10⁸ copies g^?1 soil) and 16S rDNA genes (0.05–3.00?×?10¹⁰ copies g^?1 soil) were determined in these soils. They generally followed the trend RR?>?PU?>?UC. The cbbL-containing bacterial communities were dominated by facultative autotrophic bacteria such as Mycobacterium sp., Rhodopseudomonas palustris, Bradyrhizobium japonicum, Ralstonia eutropha, and Alcaligenes eutrophus. Additionally, the cbbL-containing bacterial community composition in RR soil differed from that in upland crop and paddy rice–upland crop rotations soils. Soil organic matter was the most highly statistically significant factor which positively influenced the size of the cbbL-containing population. The RR management produced the greatest abundance and diversity of cbbL-containing bacteria. These results offer new insights into the importance of microbial autotrophic CO₂ fixation in soil C cycling.     

Long-term submergence of non-methanogenic oxic upland field soils helps to develop the methanogenic archaeal community as revealed by pot and field experiments

The community structure of methanogenic archaea is relatively stable,i.e.,it is sustained at a high abundance with minimal changes in composition,in paddy field soils irrespective of submergence and drainage.In contrast,the abundance in non-methanogenic oxic soils is much lower than that in paddy field soils.This study aimed to describe methanogenic archaeal community development following the long-term submergence of non-methanogenic oxic upland field soils in pot and field experiments.In the pot experiment,a soil sample obtained from an upland field was incubated under submerged conditions for 275 d.Soil samples periodically collected were subjected to culture-dependent most probable number(MPN)enumeration,polymerase chain reaction-denaturing gradient gel electrophoresis(PCR-DGGE)analysis of archaeal 16 S r RNA gene,and quantitative PCR analysis of the methyl-coenzyme M reductase alpha subunit gene(mcr A)of methanogenic archaea.The abundance of methanogenic archaea increased from 102 to 103 cells g-1 dry soil and 104 to 107 copies of mcr A gene g-1 dry soil after submergence.Although no methanogenic archaeon was detected prior to incubation by the DGGE analysis,members from Methanocellales,Methanosarcinaceae,and Methanosaetaceae proliferated in the soils,and the community structure was relatively stable once established.In the field experiment,the number of viable methanogenic archaea in a rice paddy field converted from meadow(reclaimed paddy field)was monitored by MPN enumeration over five annual cycles of field operations.Viability was also determined simultaneously in a paddy field where the plow layer soil from a farmer’s paddy field was dressed onto the meadow(dressed paddy field)and an upland crop field converted from the meadow(reclaimed upland field).The number of viable methanogenic archaea in the reclaimed paddy field was below the detection limit before the first cultivation of rice and in the reclaimed upland field.Then,the number gradually increased over five years and finally reached 103–104 cells g-1 dry soil,which was comparable to that in the dressed paddy field.These findings showed that the low abundance of autochthonous methanogenic archaea in the non-methanogenic oxic upland field soils steadily proliferated,and the community structure was developed following repeated and long-term submergence.These results suggest that habitats suitable for methanogenic archaea were established in soil following repeated and long-term submergence.     

Identification of thiosulfate- and sulfur-reducing bacteria unable to reduce sulfate in ricefield soils

Using peptides as energy sources, H₂ as electron donor, thiosulfate as electron acceptors, we isolated, from four ricefield soils originating from France and the Philippines, 52 strains of anaerobes, among which 18 reduced thiosulfate but not sulfate. These 18 strains were strict proteolytic asaccharolytic anaerobes producing H₂S when grown on thiosulfate + H₂. They exhibited the same restriction fragment length polymorphism (RFLP) profile (11 restriction enzymes tested). Partial sequencing of the 16S rDNA showed that they belonged to the genus Clostridium and were phylogenetically related to C. subterminale. DNA–DNA hybridization of a representative strain with the closest C. subterminale strain (DSM 6970^T) yielded a value of 68.9%. Previous counts of thiosulfate reducers unable to reduce sulfate (TSRnSR) in ricefield soils, their identification as Clostridium strains, and the known ubiquity of this genus in such soils indicate that TSRnSR of the genus Clostridium may play a significant role in S cycling in some wetland soils.     

Relationship between Gu(II) sorption and active H+ sorption sites of soils

Sorption characteristics of Cu(PI) were investigated using six soils coPBected in Korea (JUF9 SUM, and HHM) and in Japan (HNG, TWD, and ISM). The Cu(IH) sorption amount increased with increasing initial Cu(II) concentration. The maximnm sorption amount of @u(PI) increased in the order of KHM< ISK< JUM < JUF < TWD < KNG, and was related to the pH and BZSE of soils. The H⁺ release curves due to Cu(II) sorption apparently were characterized by a two or three step pattern. The amount of H⁺ released due do Cu(II) sorption increased with the increase in the Cu(II) sorption amount. The amount of protons released per Cu(II) sorbed onto soils with a larger Gu(II) sorption amount tended to be smaller compared with soils with a smaller Cu(HHQ sorption amount. The W⁺ sorption amount of the original soils and those with Cu(II) sorption at the PZSE, which was referred to as σ_P (Sakurai et al. 1988: Soil Sci. Plant Nutr., 34, 171–182; 1996: Jpn. J. Soil Sci. Plant Nutr., 67, 32–39), was determined by the STPT method proposed by Sakurai et al. (4988: Soil Sci. Plant Nutp., 34, 171–182). The active H⁺ sorption sites of soils were used for Cu(II) sorption and their amount decreased after Cu(II) sorption because they were covered with Cu(II). Soils with a larger amount of active H⁺ sorption sites exhibited a higher aEamity to Cu(II) khan those with a smaller amount of active H⁺ sorption sites. The Cu(II) sorption created a positive charge in soils, causing the decrease in the amount of active H⁺ sorption sites.