The effects of soil solid components on soil sensitivity to acid deposition by sequential extraction method were studied. A multiple regression equation of soil sensitivity was set up on the basis of stepwise regressi...The effects of soil solid components on soil sensitivity to acid deposition by sequential extraction method were studied. A multiple regression equation of soil sensitivity was set up on the basis of stepwise regression analysis. The results showed that organic matter expressed dual effects that were decided by soil original pH value and exchangeable cation composition on acid buffering reactions. The hydrolysis of activated oxides was a very important proton buffering reaction when in low pH situation. The crystalline oxides also played a role in the buffering reactions, but the role was restricted by the rate of activation of oxides. Meanwhile, the results by stepwise analysis showed that factors that had significant effect on soil acid buffering capacity were content of montmorillite, soil original pH value, Al 0, Mn 0 and CEC in decreasing order. Finally, sixteen soils were classified into four types of sensitive with single index cluster and multiple fuzzy cluster analysis respectively.展开更多
Soil samples from several forest areas in China were analyzed by X-ray powder diffractometry after mineral separation and enrichment. The density gradient separation method with sequential extraction by acetone-methyl...Soil samples from several forest areas in China were analyzed by X-ray powder diffractometry after mineral separation and enrichment. The density gradient separation method with sequential extraction by acetone-methylene iodide mixtures was applied for the separation of fine sand fraction of soil samples. The clay fraction (【 2μm) was separated from silt fraction of soil samples prior to examination. Mineral components in some fine sand and clay samples were compared, and their weathering potentiality and buffering capacity against acidic precipitation were discussed.展开更多
Lime and coal flying ash applications could mitigate pollution from acid deposition and improve the buffering ability of two acidic soils sampled from Zhejiang Province. The results showed that soil alkalinity and aci...Lime and coal flying ash applications could mitigate pollution from acid deposition and improve the buffering ability of two acidic soils sampled from Zhejiang Province. The results showed that soil alkalinity and acidified buffering capacities (QpHs ) were significantly increased, especially for liming treatment; whereas, the amounts of SO24- adsorbed by treated soils were decreased to some degrees because net negative charges of soil oxide colloidal surfaces were increased with the decrease in soil acidity, although the soil fixation abilities for adsorbed SO24- were not reduced. These facts indicated that after the alkaline ameliorators were applied, the positive and adverse effects resulted from sulfate-type acid deposition were simultaneously existed in these soil treatments.展开更多
Extensive acidic soils,which suffer from accelerated soil acidification,are found in southern China.Soil acidity,aluminum toxicity,and nutrient deficiencies severely limited crop productivity in acidic soils.It has be...Extensive acidic soils,which suffer from accelerated soil acidification,are found in southern China.Soil acidity,aluminum toxicity,and nutrient deficiencies severely limited crop productivity in acidic soils.It has been widely reported that crop residue biochars can ameliorate acidic soils and increase crop productivity.Here,we summarized the positive effects and mechanisms involved in the correction of soil acidity,the alleviation of aluminum toxicity and the increase of soil pH buffering capacity by crop residue biochars.The carbonate,oxygen-containing functional groups and silicates in biochars are the major components responsible for their efficacy in amending acidic soils and resisting soil re-acidification.We conclude that application of crop residue biochars may be a better option than traditional liming to ameliorate acidic soils.Nonetheless,further researches into soil acidification are still required to address some issues that are controversial and poorly understood.展开更多
This paper deals with the sensitivity of soils to acid rain in 5 provinces, South China. Based on field work and literature, and taking soil pH, CEC, and the types of residua into account, the authors classified the s...This paper deals with the sensitivity of soils to acid rain in 5 provinces, South China. Based on field work and literature, and taking soil pH, CEC, and the types of residua into account, the authors classified the sensitivity into 4 categories: highly sensitive, sensitive, slightly sensitive, and non-sensitive. By overlapping the maps of soil pH, CEC, and types of residua, the map of soil sensitivity in South China has finally resulted.The authors try to summarize the regularity of soil sensitivity to acid rain in this area. The sensitivity of different soil types in the studied area has also discussed.The seriousness and its prospects of acid rain in this area have been pointed out in order to draw the attention of relevant authorities.展开更多
This study aimed to clarify the ability of the buffer systems of saliva to inhibit enamel demineralization after intake of an acid beverage. In the first experiment, titrable acidity tests were carried out. Ten millil...This study aimed to clarify the ability of the buffer systems of saliva to inhibit enamel demineralization after intake of an acid beverage. In the first experiment, titrable acidity tests were carried out. Ten milliliters of saliva stimulated by chewing gum base was obtained from 10 healthy adult subjects and the pH of each saliva sample was measured. The beverages used for the experiment were a carbonated soft drink (pH 2.2), a sports drink (pH 3.5), and 100% orange juice (pH 3.8). Distilled water adjusted to the pH of each saliva sample was used as a control. In the second experiment, the suppressive ability of saliva against enamel demineralization was quantitatively analyzed using quantitative light- induced fluorescence (QLF). Aliquots of stimulated saliva obtained from a subject were mixed with 15 ml of 100% orange juice in saliva:orange juice ratios of 1/30, 1/15, 1/10 and 1/5, and bovine teeth were soaked for 24 hours in the solutions. The △Q of the QLF analyses of the enamel was then measured. The lowest titrant volume which reduced the pH of the initial saliva (7.7 on average) to pH 5.4 was that of the orange juice. No relationship was found between the buffer capacity and the pH of the acid beverages. From the QLF measurement, the saliva-orange juice group showed a significantly decreased amount of enamel demineralization (p < 0.01 at 20% level) compared with the distilled water-orange juice group. In conclusion, saliva acts as a buffer to suppress enamel demineralization caused by low-pH beverages.展开更多
There are about 5 million ha of strongly acid soils (pH < 4.8 in 0.01 mol·L -1 CaCl 2 ) in Victoria and about 11 million ha of mildly acid soils (pH 4.8～5.5) that are considered susceptible to furthe...There are about 5 million ha of strongly acid soils (pH < 4.8 in 0.01 mol·L -1 CaCl 2 ) in Victoria and about 11 million ha of mildly acid soils (pH 4.8～5.5) that are considered susceptible to further acidification under current agricultural use. However, there appear to be differences in the rate of acidification, as measured by soil pH change, between soils under perennial pastures in the higher rainfall areas of southern Victoria and soils under annual pastures in the sheep-wheat areas of the north-east. Measurements made on representative soils from both regions showed that the southern soils generally had a higher pH buffer capacity, which was primarily determined by the organic carbon content. There was a consistent relationship between the short-term buffer capacity (measured by titration) and the long-term buffer capacity (measured by incubation), irrespective of the origin of the soils. Exchangeable Al, measured in 0.01 mol·L -1 CaCl 2 , was strongly negatively correlated with pH and the relationship for all soils suggested that Al was adsorbed as a cation with an average charge of 1.2展开更多
氮肥施用是引起土壤酸化的主要原因之一,酸性环境促进紫色母岩的风化过程,并影响紫色母岩风化产物的理化性质,然而氮肥施用对风化产物的盐基离子和酸缓冲容量(pH Buffer Capacity,pHBC)的影响尚不明晰.因此,以蓬莱镇组(J_(3)p)紫色泥岩...氮肥施用是引起土壤酸化的主要原因之一,酸性环境促进紫色母岩的风化过程,并影响紫色母岩风化产物的理化性质,然而氮肥施用对风化产物的盐基离子和酸缓冲容量(pH Buffer Capacity,pHBC)的影响尚不明晰.因此,以蓬莱镇组(J_(3)p)紫色泥岩为研究对象,设置3组氮肥施用水平(280,560,840 kg/hm^(2))以及不施肥处理(CK),通过淋溶试验模拟母岩风化,以探明氮肥施用对紫色泥岩风化产物盐基离子及pHBC的影响.结果表明:与CK处理相比,氮肥施用处理下风化产物的化学蚀变指数(Chemical Index of Alteration,CIA)增加0.9%~4.7%,且风化产物的CIA随施肥水平的增加而呈现先增加后减小的趋势.氮肥施肥处理下风化产物的pHBC较CK处理降低4.0%~8.9%,且风化产物的pHBC随氮肥施用水平的增加呈现先减小后增加的趋势.风化产物的交换性盐基离子、水溶性盐基离子和盐基离子的淋失总量表现为:Ca^(2+)>Mg^(2+)>Na^(+)>K^(+),且风化产物的二价盐基离子(Ca^(2+)和Mg^(2+))含量远高于一价盐基离子含量(K^(+)和Na^(+)).基于多元线性逐步回归分析和结构方程模型分析结果表明:氮肥施用对风化产物水溶性K^(+)(R^(2)=0.75)和Na^(+)(R^(2)=0.99)含量存在显著负效应(p<0.05),而水溶性K^(+)和Na^(+)含量对风化产物pHBC(R^(2)=0.44)存在正效应,进而导致氮肥施用对风化产物pHBC存在负效应,这可能是氮肥施用影响风化产物pHBC的主要机制之一.研究结果表明:为了紫色土肥力的可持续发展,紫色土区域的氮肥施用量应小于280 kg/hm^(2).展开更多
文摘The effects of soil solid components on soil sensitivity to acid deposition by sequential extraction method were studied. A multiple regression equation of soil sensitivity was set up on the basis of stepwise regression analysis. The results showed that organic matter expressed dual effects that were decided by soil original pH value and exchangeable cation composition on acid buffering reactions. The hydrolysis of activated oxides was a very important proton buffering reaction when in low pH situation. The crystalline oxides also played a role in the buffering reactions, but the role was restricted by the rate of activation of oxides. Meanwhile, the results by stepwise analysis showed that factors that had significant effect on soil acid buffering capacity were content of montmorillite, soil original pH value, Al 0, Mn 0 and CEC in decreasing order. Finally, sixteen soils were classified into four types of sensitive with single index cluster and multiple fuzzy cluster analysis respectively.
文摘Soil samples from several forest areas in China were analyzed by X-ray powder diffractometry after mineral separation and enrichment. The density gradient separation method with sequential extraction by acetone-methylene iodide mixtures was applied for the separation of fine sand fraction of soil samples. The clay fraction (【 2μm) was separated from silt fraction of soil samples prior to examination. Mineral components in some fine sand and clay samples were compared, and their weathering potentiality and buffering capacity against acidic precipitation were discussed.
文摘Lime and coal flying ash applications could mitigate pollution from acid deposition and improve the buffering ability of two acidic soils sampled from Zhejiang Province. The results showed that soil alkalinity and acidified buffering capacities (QpHs ) were significantly increased, especially for liming treatment; whereas, the amounts of SO24- adsorbed by treated soils were decreased to some degrees because net negative charges of soil oxide colloidal surfaces were increased with the decrease in soil acidity, although the soil fixation abilities for adsorbed SO24- were not reduced. These facts indicated that after the alkaline ameliorators were applied, the positive and adverse effects resulted from sulfate-type acid deposition were simultaneously existed in these soil treatments.
基金funded by the National Key Research and Development of China(2016YFD0200302)the National Key Basic Research Program of China(2014CB441003)
文摘Extensive acidic soils,which suffer from accelerated soil acidification,are found in southern China.Soil acidity,aluminum toxicity,and nutrient deficiencies severely limited crop productivity in acidic soils.It has been widely reported that crop residue biochars can ameliorate acidic soils and increase crop productivity.Here,we summarized the positive effects and mechanisms involved in the correction of soil acidity,the alleviation of aluminum toxicity and the increase of soil pH buffering capacity by crop residue biochars.The carbonate,oxygen-containing functional groups and silicates in biochars are the major components responsible for their efficacy in amending acidic soils and resisting soil re-acidification.We conclude that application of crop residue biochars may be a better option than traditional liming to ameliorate acidic soils.Nonetheless,further researches into soil acidification are still required to address some issues that are controversial and poorly understood.
文摘This paper deals with the sensitivity of soils to acid rain in 5 provinces, South China. Based on field work and literature, and taking soil pH, CEC, and the types of residua into account, the authors classified the sensitivity into 4 categories: highly sensitive, sensitive, slightly sensitive, and non-sensitive. By overlapping the maps of soil pH, CEC, and types of residua, the map of soil sensitivity in South China has finally resulted.The authors try to summarize the regularity of soil sensitivity to acid rain in this area. The sensitivity of different soil types in the studied area has also discussed.The seriousness and its prospects of acid rain in this area have been pointed out in order to draw the attention of relevant authorities.
文摘This study aimed to clarify the ability of the buffer systems of saliva to inhibit enamel demineralization after intake of an acid beverage. In the first experiment, titrable acidity tests were carried out. Ten milliliters of saliva stimulated by chewing gum base was obtained from 10 healthy adult subjects and the pH of each saliva sample was measured. The beverages used for the experiment were a carbonated soft drink (pH 2.2), a sports drink (pH 3.5), and 100% orange juice (pH 3.8). Distilled water adjusted to the pH of each saliva sample was used as a control. In the second experiment, the suppressive ability of saliva against enamel demineralization was quantitatively analyzed using quantitative light- induced fluorescence (QLF). Aliquots of stimulated saliva obtained from a subject were mixed with 15 ml of 100% orange juice in saliva:orange juice ratios of 1/30, 1/15, 1/10 and 1/5, and bovine teeth were soaked for 24 hours in the solutions. The △Q of the QLF analyses of the enamel was then measured. The lowest titrant volume which reduced the pH of the initial saliva (7.7 on average) to pH 5.4 was that of the orange juice. No relationship was found between the buffer capacity and the pH of the acid beverages. From the QLF measurement, the saliva-orange juice group showed a significantly decreased amount of enamel demineralization (p < 0.01 at 20% level) compared with the distilled water-orange juice group. In conclusion, saliva acts as a buffer to suppress enamel demineralization caused by low-pH beverages.
文摘There are about 5 million ha of strongly acid soils (pH < 4.8 in 0.01 mol·L -1 CaCl 2 ) in Victoria and about 11 million ha of mildly acid soils (pH 4.8～5.5) that are considered susceptible to further acidification under current agricultural use. However, there appear to be differences in the rate of acidification, as measured by soil pH change, between soils under perennial pastures in the higher rainfall areas of southern Victoria and soils under annual pastures in the sheep-wheat areas of the north-east. Measurements made on representative soils from both regions showed that the southern soils generally had a higher pH buffer capacity, which was primarily determined by the organic carbon content. There was a consistent relationship between the short-term buffer capacity (measured by titration) and the long-term buffer capacity (measured by incubation), irrespective of the origin of the soils. Exchangeable Al, measured in 0.01 mol·L -1 CaCl 2 , was strongly negatively correlated with pH and the relationship for all soils suggested that Al was adsorbed as a cation with an average charge of 1.2
文摘氮肥施用是引起土壤酸化的主要原因之一,酸性环境促进紫色母岩的风化过程,并影响紫色母岩风化产物的理化性质,然而氮肥施用对风化产物的盐基离子和酸缓冲容量(pH Buffer Capacity,pHBC)的影响尚不明晰.因此,以蓬莱镇组(J_(3)p)紫色泥岩为研究对象,设置3组氮肥施用水平(280,560,840 kg/hm^(2))以及不施肥处理(CK),通过淋溶试验模拟母岩风化,以探明氮肥施用对紫色泥岩风化产物盐基离子及pHBC的影响.结果表明:与CK处理相比,氮肥施用处理下风化产物的化学蚀变指数(Chemical Index of Alteration,CIA)增加0.9%~4.7%,且风化产物的CIA随施肥水平的增加而呈现先增加后减小的趋势.氮肥施肥处理下风化产物的pHBC较CK处理降低4.0%~8.9%,且风化产物的pHBC随氮肥施用水平的增加呈现先减小后增加的趋势.风化产物的交换性盐基离子、水溶性盐基离子和盐基离子的淋失总量表现为:Ca^(2+)>Mg^(2+)>Na^(+)>K^(+),且风化产物的二价盐基离子(Ca^(2+)和Mg^(2+))含量远高于一价盐基离子含量(K^(+)和Na^(+)).基于多元线性逐步回归分析和结构方程模型分析结果表明:氮肥施用对风化产物水溶性K^(+)(R^(2)=0.75)和Na^(+)(R^(2)=0.99)含量存在显著负效应(p<0.05),而水溶性K^(+)和Na^(+)含量对风化产物pHBC(R^(2)=0.44)存在正效应,进而导致氮肥施用对风化产物pHBC存在负效应,这可能是氮肥施用影响风化产物pHBC的主要机制之一.研究结果表明:为了紫色土肥力的可持续发展,紫色土区域的氮肥施用量应小于280 kg/hm^(2).
