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A Model for Anion Electric Adsorption on Variable Charge soils

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pedosphere 1991年第2期1卷 169-176页

作者： HU GUo-SoNGInstitute of soil science, a cademia sinica, p. o box 821. nanjing 210008 (China)

A model was established for anion electric adsorption on variable charge surfaces and an equation to describe the relationship of adsorption amount with equalibrium concentration and suspension pH was derived according to the principles of surface reaction between variable charge surface and *** adsorption behaviours of nitrate and chloride on variable charge soils were modelled and the results showed that the model could describe the adsorption of nitrate very well.

关键词： anion electric adsorption,model variable charge soils

Status of soil Zn in Citrus-Cultivated Area of South China

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pedosphere 1992年第4期2卷 379-382页

作者： oUYANG TAoInstitute of soil science, a cademia sinica. p.o. box 821. nanjing 210008 (China)

INTRoDUCTIoN In recent 10 years,citrus production has developed rapidly in *** citrus-cul-tivated area of our country is among the largest and its yield occupies the third place inthe world(Shen,1991).However,in some of our citrus-producing areas the yield is onthe low side and the sugar content of the fruit tends to ***“mosaic”-a physio-

关键词： citrus soil type zinc effect

Human Activity and soil Fertility-Nutrients Depletion of Arable soils in China

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pedosphere 1991年第4期1卷 371-376页

作者： LU RU-KUNInstitute of soil science, a cademia sinica, nanjing 210008 (China)

The reserve of soil nutrients is limited. In case of irrational use of land, nutrients would be depleted sooner. Before the 1950s the low grain production in China was maintained only by expanding the cultivated area and by recycling of nutrients in agriculture. Calculation of nutrients balance showed that in the year of 1949 there were great deficits of N, p and K elements in agriculture of China. It revealed that there would have really been danger of soil nutrients exhaustion if such a situation had continued. Things have changed since the beginning of 1950s. The nutrients balance in agriculture has been getting better and better. In the year 1987 N and p balance got rid of their great deficits. But for K the deficit grew even larger. This resulted in a rapid expansion of soil area deficient in K in China since the mid 1970s. In spite of the fact that the p balance in the arable land of the whole country was positive, the field which did not receive p fertilizer had become deficient in p. So the area deficient in p also increased. It is stressed that great attention should be paid to the depletion of soil nutrients, especially K in the northern part of China where the soil is relatively rich in K. of course, soil sulfur and microelements should be considered next.

关键词： soil degradation soil nutrients

Zn Adsorption by Variable Charge soils in Relation to pH

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pedosphere 1993年第1期3卷 23-33页

作者： SUN HAN-YUANInstitute of soil science, a cademia sinica, nanjing 210008 (China)

Zn adsorption by pure oxides or in the presence of a high concentration of inner electrolyte has been extensively studied. But, in studies on Zn adsorption in the complicated soil system, especially in variable charge soils, profound knowledge about the adsorption mechanism still lacks. In this paper, taking Zn ion adsorption by two typical variable charge soils as the object of the study, author discusses the relation between Zn adsorption and pH and possible adsorption mechanisms. The results showed that in the low pH range where the amount of Zn adsorbed did not exceed 50% of Zn added, the specific adsorption was the dominant mechanism. The species of Zn specifically adsorbed was free Zn2+ ion. In the middle and high pH ranges, the mechanisms of specific and electrostatic adsorptions, co-existed, accounting for about 70% and 30% , respectively. Noteworthily, in the high pH range, the hydroxyl Zn ion (ZnoH +) from Zn2+ hydrolysis probably was a preferable species for specific adsorption.

关键词： electrostatic adsorption pH specific adsorption variable charge soils zinc

Apparent Mobilities of Na^+, K^+and Ca^(2+) Ions in Variable Charge soil Colloid Systems

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pedosphere 1992年第1期2卷 43-49页

作者： LI chenG-BAoInstitute of soil science, a cademia sinica, nanjing 210008 (China)

In this paper a simple method for determination of the apparent mobility of cation in a soil colloid system was described. With this method apparent mobilities of Na+, K+, and Ca2+ ions in the systems of the ferric luvisol, acrisol, and ferralsol were determined, and the reduction percentages of the mobilities were calculated. The results showed that the apparent mobilities of different cations at the same normality in a given soil system were in the order UNa> UK> UCa; those of the same cations among different soil systems were in the order ferralsol > acrisol > ferric luvisol, but the reduction percentages were in a reverse order, which among different cations at the same normality was Ca2+> K+> Na+ for ferric luvisol and acrisol systems, but was K+> Ca2+> Na+ for farralsol system. These results were interpreted in terms of different amounts of negative charge the clay fraction of different soils carries, and different mechanisms by which the soils adsorb the cations.

关键词： apparent mobility DC conductivity method mobility reduction variable charge soil

Effect of Heavy Metals on phosphorus Retention by Typic Udic Ferrisols: Equilibrium and Kinetics

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pedosphere 2002年第1期12卷 15-24页

作者： TU CoNG, ZHENG CHUNRoNG and chen HUAIMAN LMCp, Institute of soil science, the Chinese Academy of sciences, p.o. box 821. nanjing 210008 (China) Department of plant pathology North Carolina State University P.O. Box 7616 RaleighNC 27695-7616 USA 中科院南京土壤所 LMCP CAS Nanjing 210008

A study was conducted to examine the effect of heavy metals (Cu,pb, Zn and Cd in combination or alone) on the equilibrium andkinetics of phosphorus (p) retention in typic udic ferrisols by usingboth equilibrium and flow techniques. Fourteen soil samples withvarying artificial contamination of Cu, pb, Zn and Cd were *** metal pollution led to increases in retention capacity andmaximum buffering capacity (MBC) of soil p. The rate of p retentionwas also increased and the time to reach equilibrium was advanced byheavy metals addition.

关键词： equilibrium kinetics heavy metlas phosphorus retention

Effect of K and Al on Growth and Nutrient Uptake of Rice

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pedosphere 1998年第4期8卷 305-310页

作者： chenJIXING XUANJIAXIANG Instituteofsoilscience theChineseAcademyofSciences.P.O.Box821Nanjing210008（CHina） InstituteofsoilSci

The effects of K and Al in K-deficient and complete nutrient solutions on the growth and nutrient uptake of rice were studied in the work. The effect of Al on the growth of roots and above-ground part of rice was associated with the concentration of Al in solution. A low level (0.1 mmol L-1) of Al promoted but a high level (1 mmol L-1) of Al inhibited the growth of both the root and the aerial part of rice, and the magnitude of K concentration in the nutrient solution also had an appreciable impact on this. Thus, in the low-Al solution, the plant treated with K2 (80 mg K L-1) produced much longer roots, showing the presence of interaction between Al and K; in the high-Al solution the K-treated plant had more and longer roots and a considerably greater dry weight of the above-ground pat compared with the plant deficient in K, showing the alleviating effect of K+ on Al *** mechanism of the Al-K interaction affecting the rice aerial part growth is not yet known, but part of the reason might be that the excessive amount of Al inhibited the uptake of some nutrients such as Ca and Mg and reduced their transfer to the plant aerial organs, whereas K showed its compensating effect on this; therefore, K could relieve Al toxicity at a high level of Al and promoted rice growth at a low level of Al.

关键词： aluminum nutrient uptake potassium rice growth

Content and partial Characterization of Unknown N in Humic Acids

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pedosphere 1991年第3期1卷 283-287页

作者： YEWEI WENQI－XIAo 等 DepartmentofsoilBiochemistry InstituteofSoilScienceAcademiaSinicaP.O.Box821Nanjing210008（China） La

INTRoDUCTIoN Nitrogen is a key component of soil organic matter. only when we have succeeded in characterizing the major part of organic N-containing compounds will we be able to understand fully the transformation reactions in the soil and to use soil-N more efficiently. However, only about 1/ 4——1/ 2 of the total N in humic acid (HA), one of the major constituents of soil organic matter, can be accounted for as amino acids and amino sugars, and most of the remainder has still to be accounted for. It has been

关键词： humic acid non-α-amino acid N-phenyl amino acid real amide unknown N

Effect of Anions on Adsorbability and Extractability of Lead Added in soil

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pedosphere 1991年第1期1卷 51-62页

作者： chen HUAI-MAN, ZHENG CHUN-RoNG and SUN XIAo-HUALaboratory of Material Cycling in pedosphere, ’Institute of soil science, a cademia sinica, p. o. box 821. nanjing (China)

The effect of accompanying anions on the adsorbability and extractability of pb added in soils was studied by using bach equilibria and incubation-extraction *** concentration ranged between 0.48-2.41 mM in the adsorption experiment,and pb added to soil from 2.14 to 19.31mM pb/kg with an incubation time of 2-16 weeks in the incubation-extraction test in which 1M NH4oAc(pH 7) was taken as an extraction agent,and the pb compounds used are pbCl2,pb(No3)2 and pb(oAc)*** values of pH50 for pb retention and the parameters,b and k values,of Langmuir equation were used to distinguish the difference of adsorbability and extractability of pb affected by anions,*** from the results of either pH50 value or b value,the influences of Cl^- and No3^- on the adsorbability and extractability of pb in soils were similar but quite different from those of oAc^-.The relative loading capacities of soils to pb calculated according to the extraction rate showed that the values of pb(oAc)2 were higher than those of pbCl2 and pb(No3)2.

关键词： anion Langmuir equation pb pH50 soil