Conversions from rural to urban land uses have the potential to greatly modify soil phosphorus （P） levels. Soils in shrubs, Masson pine forest, conifer and broadleaf mixed forest, evergreen broadleaved forest and ba...Conversions from rural to urban land uses have the potential to greatly modify soil phosphorus （P） levels. Soils in shrubs, Masson pine forest, conifer and broadleaf mixed forest, evergreen broadleaved forest and bamboo forest in the mid-subtropical region along an urban-rural gradient in Nanchang City, southern China, were analyzed for total P and P fractions using the modified Hedley P sequential fractionation method. Results show that the topsoil total P and total exactable P concentrations were significantly higher in the urban area （0.71 g·kg^-1 and 378.50 mg·kg^-1, respectively） than in the suburban （0.30 g·kg^-1 and 150.74 mg·kg^-1, respectively） and rural areas （0.31 g·kg^-1 and 147.38 mg·kg^-1, respectively） （p〈0.05）. Among the five P fractions of resin-P, NaHCO3-P NaOH-P, Sonication-P and HCI-P, the relative abundance of HCl-P in urban forest soils （36%） was the highest and also significantly higher than in suburban （8%） and rural soils （6%）, while NaOH-P was the dominant form in suburban （41%） and rural soils （50%）. Phosphorus accumulation in the urban soils could affect the cycle of P in urban forest systems, particularly the HCl-P fraction that might rapidly enrich aquatic systems in urban areas.展开更多
In order to provide the scientific basis for the governance of Tien Lake. The experiment was conducted to investigate different types of surface soiI phospho-rus in Tien Lake Basin, the author malnIy studied the evoIu...In order to provide the scientific basis for the governance of Tien Lake. The experiment was conducted to investigate different types of surface soiI phospho-rus in Tien Lake Basin, the author malnIy studied the evoIution and the accumuIa-tion characteristics of the surface soiI phosphorus in Tien Lake Basin. The resuIts showed that： The content of surface soiI total phosphorus, OIsen-P and water soIu-bIe phosphorus in Tien Lake was significant accumuIated over the past 20 years. The content of total phosphorus, OIsen-P and water soIubIe phosphorus in different Iand utiIization types showed the same sequence： greenhouse soi〉arabIe soi〉buiIt-up area soi〉woodIand soiI. The content of soiI total phosphorus, OIsen-P and water soIubIe phosphorus was signal y reIevant. The content of soiI phosphorus in Tien Lake Basin had reached the IeveI of very rich, the accumuIation characteristic of phosphorus was obvious and there was a high risk of phosphorus poI ution.展开更多
Cells of Haematococcus pluvialis Flot. et Will were collected in four different growth phases. We quantified the initial and total enzyme activity of ribulose-1,5-bisphosphate carboxylase （Rubiseo） in crude extracts...Cells of Haematococcus pluvialis Flot. et Will were collected in four different growth phases. We quantified the initial and total enzyme activity of ribulose-1,5-bisphosphate carboxylase （Rubiseo） in crude extracts, and the relative expression of large-subunit ribulose-1,5-bisphosphate caboxylase / oxygenase （rbcL） mRNA. We measured the ratio of photosynthetic rate to respiration rate （P/R）, maximal effective quantum yield of photosystem II （Fv/Fm）, electron transport rate （ETR）, actual photochemical efficiency of PSI1 in the light （ФPSII）, and non-photochemical quenching （NPQ）. Green vegetative cells were found to be in the most active state, with a relatively higher P/R ratio. These cells also displayed the lowest NPQ and the highest Fv/Fm, ETR, and ФPSII, indicating the most effective PSII. However, both Rubisco activity and rbcL mRNA expression were the lowest measured. In orange resting cysts with relatively lower P/R and NPQ, Rubisco activity and rbcL expression reached a peak, while Fv/Fm, ETR, and ФPSII were the lowest measured. Taking into account the methods of astaxanthin induction used in industry, we suggest that Rubisco may participate in astaxanthin accumulation in H. pluvialis. A continuous and sufficient supply of a carbon source such as CO2 may therefore aid the large scale production of astaxanthin.展开更多
基金funded by the National Natural Science Foundation of China(No.3060047&30960311)Natural Science Foundation of Jiangxi Provinces(No.2007GQN1935)
文摘Conversions from rural to urban land uses have the potential to greatly modify soil phosphorus （P） levels. Soils in shrubs, Masson pine forest, conifer and broadleaf mixed forest, evergreen broadleaved forest and bamboo forest in the mid-subtropical region along an urban-rural gradient in Nanchang City, southern China, were analyzed for total P and P fractions using the modified Hedley P sequential fractionation method. Results show that the topsoil total P and total exactable P concentrations were significantly higher in the urban area （0.71 g·kg^-1 and 378.50 mg·kg^-1, respectively） than in the suburban （0.30 g·kg^-1 and 150.74 mg·kg^-1, respectively） and rural areas （0.31 g·kg^-1 and 147.38 mg·kg^-1, respectively） （p〈0.05）. Among the five P fractions of resin-P, NaHCO3-P NaOH-P, Sonication-P and HCI-P, the relative abundance of HCl-P in urban forest soils （36%） was the highest and also significantly higher than in suburban （8%） and rural soils （6%）, while NaOH-P was the dominant form in suburban （41%） and rural soils （50%）. Phosphorus accumulation in the urban soils could affect the cycle of P in urban forest systems, particularly the HCl-P fraction that might rapidly enrich aquatic systems in urban areas.
基金Supported by the Science and Technology Major Projects of Tien lake of National Water Pollution Control and Management"Integrated Control and Water Conservation Forest protection Key Technology and Engineering Demonstration of Agricultural Non-point Source Pollution in Tien Lake Basin"(2012ZX07102-003)Applied Basic Research Major Projects of Yunnan Province"The Research on Phosphorus Supergene Migration and Aquatic Organisms Response of Tien Lake"(2009CC006)~~
文摘In order to provide the scientific basis for the governance of Tien Lake. The experiment was conducted to investigate different types of surface soiI phospho-rus in Tien Lake Basin, the author malnIy studied the evoIution and the accumuIa-tion characteristics of the surface soiI phosphorus in Tien Lake Basin. The resuIts showed that： The content of surface soiI total phosphorus, OIsen-P and water soIu-bIe phosphorus in Tien Lake was significant accumuIated over the past 20 years. The content of total phosphorus, OIsen-P and water soIubIe phosphorus in different Iand utiIization types showed the same sequence： greenhouse soi〉arabIe soi〉buiIt-up area soi〉woodIand soiI. The content of soiI total phosphorus, OIsen-P and water soIubIe phosphorus was signal y reIevant. The content of soiI phosphorus in Tien Lake Basin had reached the IeveI of very rich, the accumuIation characteristic of phosphorus was obvious and there was a high risk of phosphorus poI ution.
基金Supported by the National Basic Projects for Science and Technology(No. SQ2012FY4910019-1)the Project of Science and Technology for Supporting Tianjin Development (No. 10ZCKFSH0070)the Project for Developing Marine Economy by Science and Technology in Tianjin(KX2010-0005)
文摘Cells of Haematococcus pluvialis Flot. et Will were collected in four different growth phases. We quantified the initial and total enzyme activity of ribulose-1,5-bisphosphate carboxylase （Rubiseo） in crude extracts, and the relative expression of large-subunit ribulose-1,5-bisphosphate caboxylase / oxygenase （rbcL） mRNA. We measured the ratio of photosynthetic rate to respiration rate （P/R）, maximal effective quantum yield of photosystem II （Fv/Fm）, electron transport rate （ETR）, actual photochemical efficiency of PSI1 in the light （ФPSII）, and non-photochemical quenching （NPQ）. Green vegetative cells were found to be in the most active state, with a relatively higher P/R ratio. These cells also displayed the lowest NPQ and the highest Fv/Fm, ETR, and ФPSII, indicating the most effective PSII. However, both Rubisco activity and rbcL mRNA expression were the lowest measured. In orange resting cysts with relatively lower P/R and NPQ, Rubisco activity and rbcL expression reached a peak, while Fv/Fm, ETR, and ФPSII were the lowest measured. Taking into account the methods of astaxanthin induction used in industry, we suggest that Rubisco may participate in astaxanthin accumulation in H. pluvialis. A continuous and sufficient supply of a carbon source such as CO2 may therefore aid the large scale production of astaxanthin.
