The study was conducted in Zhifanggou Watershed,Shaanxi Province,China,to evaluate the effect of different vegetation types on hot-water extractable C,N and P fractions,with the aim to determine whether hot-water extr...The study was conducted in Zhifanggou Watershed,Shaanxi Province,China,to evaluate the effect of different vegetation types on hot-water extractable C,N and P fractions,with the aim to determine whether hot-water extractable fractions could be used as indicators of soil quality change in Loess Plateau.The six vegetation types established in 1975 were（i） Robinia pseudoacacia L.,（ii） Caragana korshinkii Kom.,（iii） Pinus tabulaeformis Carr.,（iv） P.tabulaeformis-Amorpha fruticosa L.,（v） R.pseudoacacia-A.fruticosa,and（vi） grassland.A cropped hillslope plot and a Platycladus orientalis L.native forest plot were used as references.The results indicated that the conversion of native forest to cropland resulted in a significant decline in the hot-water extractable C,N and P fractions.Hot-water extractable C,N,and P increased when cultivated land was revegetated,but after 30 years the amount of hot-water extractable C,N,and P in revegetated fields was still much lower compared to native forest.Hot-water extractable fractions increased more under mixed-forest than under pure-forest stands.Furthermore,there was a significant correlation between the hot-water extractable fractions and soil chemical and microbiological properties.The results showed that hot-water extractable fractions could be used as indicators of soil quality change on the Loess Plateau.展开更多
Carbohydrate represents an important part of the soil labile organic carbon pool. Water soluble carbohydrate drives the C cycle in forest soil by affecting microbial activity and hot water extractable car- bohydrate i...Carbohydrate represents an important part of the soil labile organic carbon pool. Water soluble carbohydrate drives the C cycle in forest soil by affecting microbial activity and hot water extractable car- bohydrate is thought related to soil carbon sequestration due to the asso- ciation with soil aggregation. In a temperate forest region of northeast China, Changbai Mountain, we investigated the abundance, spatial dis- tribution, and seasonal dynamics of cool and hot-water extractable car- bohydrate in soils under mixed broad-leaved Korean pine forest. The concentrations of cool-water extractable carbohydrate （CWECH） in three soil layers （0-5, 5-10, 10-20 cm） ranged from 4.1 to 193.3 g.kg-1 dry soil, decreasing rapidly with soil depth. On an annual average, the CWECH concentrations in soils at depths of 5-10 and 10-20 cm were 54.2% and 24.0%, respectively, of that in the 0-5 cm soil layer. CWECH showed distinct seasonal dynamics with the highest concentrations in early spring, lowest in summer, and increasing concentrations in autumn. Hot-water extractable carbohydrate （HWECH） concentrations in three soil layers ranged from 121.4 to 2026.2 g.kgq dry soil, which were about one order of magnitude higher than CWECH. The abundance of HWECH was even more profile-dependent than CWECH, and decreased more rapidly with soil depth. On an annual average, the HWECH concentration in soils 10-20 cm deep was about one order of magnitude lower than that in the top 0-5 cm soil. The seasonality of HWECH roughly tracked that of CWECH but with seasonal fluctuations of smaller amplitude. The car- bohydrate concentrations in cool/hot water extracts of soil were positively correlated with UV254 and UV2s0 of the same solution, which has implications for predicting the leaching loss of water soluble organic carbon.展开更多
Drinking water-type fluorosis is the most harmful endemic disease in China with the largest number of sufferers. Although the implementation of the policy to alter water sources to lower fluoride level has effectively...Drinking water-type fluorosis is the most harmful endemic disease in China with the largest number of sufferers. Although the implementation of the policy to alter water sources to lower fluoride level has effectively controlled the spread of this kind of endemic disease,its prevalence could not thoroughly be stopped because the high-fluoride environmental background in these endemically diseased areas could still do harm to human health through food chain. Therefore,it is necessary to conduct a more deep-going study on the drinking water-type fluoro-sis. To investigate the effect of high fluorine environmental background on crops and human health in the hot spring-type fluorosis-diseased areas,local water,paddy soil,rice,whole vegetables and soils around their roots were sampled for analysis. The results were compared with those of the control groups in fluorosis-free areas which are similar to the fluorosis-diseased areas both in natural background and in social background. It is indicated that rice and vegetables can accumulate water-soluble fluorine either in soils or in irrigating water,and different crops have different abilities of fixing fluorine. The contents of fluorine in different parts of vegetables in the fluorosis-diseased and fluorosis-free areas were statistically categorized. The results showed that the fluorine contents of roots,tubers,leaves and flowers of vegetables in the fluorosis-diseased areas are 3.56,1.17,3.07 and 3.23 mg/kg,respectively. However,comparisons showed that in the fluorosis-free areas,the fluorine contents are 2.17,0.70,1.91 and 2.52 mg/kg,respectively. Moreover,different parts of a crop also show significantly different fluorine fixation abilities. It is demonstrated that the fluorine contents of the strongly metabolic parts are relatively high. For example,the fluo-rine contents of roots,leaves and flowers of vegetables are much higher than those of stems. The fluorine fixation ability of seeds is very weak. In order to reduce the risk of human body’s exposure to fluoride,the impact of hot spring water on the capability of crops to fix fluorine should be reduced as much as possible. It is of great importance to prevent crops from being irrigated with hot spring water and it is advisable to grow crops with relatively low ca-pabilities to enrich fluorine,such as those with seeds or tubers as the main edible parts in the areas which are se-verely affected by hot spring water.展开更多
研究了不同土壤含水量对辣椒果实抗氧化物质及酶活性的影响。结果表明,随着土壤相对含水量的逐渐下降,果实辣椒素、黄酮、自由酚、维生素 C 及类胡萝卜素含量呈逐渐增加趋势,当土壤相对含水量为20%时达到最高水平,土壤含水量80%时为最低...研究了不同土壤含水量对辣椒果实抗氧化物质及酶活性的影响。结果表明,随着土壤相对含水量的逐渐下降,果实辣椒素、黄酮、自由酚、维生素 C 及类胡萝卜素含量呈逐渐增加趋势,当土壤相对含水量为20%时达到最高水平,土壤含水量80%时为最低;叶绿素含量随着土壤含水量的下降而不断降低,其中土壤含水量为80%时含量最高,土壤含水量为20%时含量最低;SOD、POD、PAL、PPO 的活性随着土壤十旱程度的加剧呈逐渐增加趋势。展开更多
基金financially supported by the Strategic Technology Project of Chinese Academy of Sciences,China(XDA05060300)the Science and Technology Research and Development Program of Shaanxi Province,China(2011KJXX63)the Fundamental Research Funds for the Central Universities,China(ZD2013021)
文摘The study was conducted in Zhifanggou Watershed,Shaanxi Province,China,to evaluate the effect of different vegetation types on hot-water extractable C,N and P fractions,with the aim to determine whether hot-water extractable fractions could be used as indicators of soil quality change in Loess Plateau.The six vegetation types established in 1975 were（i） Robinia pseudoacacia L.,（ii） Caragana korshinkii Kom.,（iii） Pinus tabulaeformis Carr.,（iv） P.tabulaeformis-Amorpha fruticosa L.,（v） R.pseudoacacia-A.fruticosa,and（vi） grassland.A cropped hillslope plot and a Platycladus orientalis L.native forest plot were used as references.The results indicated that the conversion of native forest to cropland resulted in a significant decline in the hot-water extractable C,N and P fractions.Hot-water extractable C,N,and P increased when cultivated land was revegetated,but after 30 years the amount of hot-water extractable C,N,and P in revegetated fields was still much lower compared to native forest.Hot-water extractable fractions increased more under mixed-forest than under pure-forest stands.Furthermore,there was a significant correlation between the hot-water extractable fractions and soil chemical and microbiological properties.The results showed that hot-water extractable fractions could be used as indicators of soil quality change on the Loess Plateau.
基金supported by made possible through National Key Basic Research Foundation, China (grants 2011CB403202)the National Natural Science Foundation of China (40930107)Program for Changjiang Scholars and Innovative Research Team in University (IRT1054)
文摘Carbohydrate represents an important part of the soil labile organic carbon pool. Water soluble carbohydrate drives the C cycle in forest soil by affecting microbial activity and hot water extractable car- bohydrate is thought related to soil carbon sequestration due to the asso- ciation with soil aggregation. In a temperate forest region of northeast China, Changbai Mountain, we investigated the abundance, spatial dis- tribution, and seasonal dynamics of cool and hot-water extractable car- bohydrate in soils under mixed broad-leaved Korean pine forest. The concentrations of cool-water extractable carbohydrate （CWECH） in three soil layers （0-5, 5-10, 10-20 cm） ranged from 4.1 to 193.3 g.kg-1 dry soil, decreasing rapidly with soil depth. On an annual average, the CWECH concentrations in soils at depths of 5-10 and 10-20 cm were 54.2% and 24.0%, respectively, of that in the 0-5 cm soil layer. CWECH showed distinct seasonal dynamics with the highest concentrations in early spring, lowest in summer, and increasing concentrations in autumn. Hot-water extractable carbohydrate （HWECH） concentrations in three soil layers ranged from 121.4 to 2026.2 g.kgq dry soil, which were about one order of magnitude higher than CWECH. The abundance of HWECH was even more profile-dependent than CWECH, and decreased more rapidly with soil depth. On an annual average, the HWECH concentration in soils 10-20 cm deep was about one order of magnitude lower than that in the top 0-5 cm soil. The seasonality of HWECH roughly tracked that of CWECH but with seasonal fluctuations of smaller amplitude. The car- bohydrate concentrations in cool/hot water extracts of soil were positively correlated with UV254 and UV2s0 of the same solution, which has implications for predicting the leaching loss of water soluble organic carbon.
基金financially supported jointly by the National Natural Science Foundation of China (Grant No.40601004)the Scientific and Technological Project of the Educa-tion Department of Jiangxi Province (No. GJJ08032)+1 种基金the K.C. Wong Education FoundationHong Kong and China’s Post-doctoral Science Funds
文摘Drinking water-type fluorosis is the most harmful endemic disease in China with the largest number of sufferers. Although the implementation of the policy to alter water sources to lower fluoride level has effectively controlled the spread of this kind of endemic disease,its prevalence could not thoroughly be stopped because the high-fluoride environmental background in these endemically diseased areas could still do harm to human health through food chain. Therefore,it is necessary to conduct a more deep-going study on the drinking water-type fluoro-sis. To investigate the effect of high fluorine environmental background on crops and human health in the hot spring-type fluorosis-diseased areas,local water,paddy soil,rice,whole vegetables and soils around their roots were sampled for analysis. The results were compared with those of the control groups in fluorosis-free areas which are similar to the fluorosis-diseased areas both in natural background and in social background. It is indicated that rice and vegetables can accumulate water-soluble fluorine either in soils or in irrigating water,and different crops have different abilities of fixing fluorine. The contents of fluorine in different parts of vegetables in the fluorosis-diseased and fluorosis-free areas were statistically categorized. The results showed that the fluorine contents of roots,tubers,leaves and flowers of vegetables in the fluorosis-diseased areas are 3.56,1.17,3.07 and 3.23 mg/kg,respectively. However,comparisons showed that in the fluorosis-free areas,the fluorine contents are 2.17,0.70,1.91 and 2.52 mg/kg,respectively. Moreover,different parts of a crop also show significantly different fluorine fixation abilities. It is demonstrated that the fluorine contents of the strongly metabolic parts are relatively high. For example,the fluo-rine contents of roots,leaves and flowers of vegetables are much higher than those of stems. The fluorine fixation ability of seeds is very weak. In order to reduce the risk of human body’s exposure to fluoride,the impact of hot spring water on the capability of crops to fix fluorine should be reduced as much as possible. It is of great importance to prevent crops from being irrigated with hot spring water and it is advisable to grow crops with relatively low ca-pabilities to enrich fluorine,such as those with seeds or tubers as the main edible parts in the areas which are se-verely affected by hot spring water.
文摘研究了不同土壤含水量对辣椒果实抗氧化物质及酶活性的影响。结果表明,随着土壤相对含水量的逐渐下降,果实辣椒素、黄酮、自由酚、维生素 C 及类胡萝卜素含量呈逐渐增加趋势,当土壤相对含水量为20%时达到最高水平,土壤含水量80%时为最低;叶绿素含量随着土壤含水量的下降而不断降低,其中土壤含水量为80%时含量最高,土壤含水量为20%时含量最低;SOD、POD、PAL、PPO 的活性随着土壤十旱程度的加剧呈逐渐增加趋势。
