Suspended particulate matter (SPM) collected in the Changjiang (Yangtze River) estuary in June 2006 was separated into five fractions via water elutriation:clay-very fine silt (<8 μm),fine silt (8-16 μm),medium silt (16-32 μm),coarse silt (32-63 μm) and sand (>63 μm).The SPM and fractionated particles were sequentially analyzed by a modified SEDEX sequential extraction method to obtain six species of phosphorus:exchangeable or loosely-sorbed P,organic P,Fe-bound P,authigenic P,detrital P and refractory P.The results indicated that all particulate phosphorus species except for detrital P were negatively correlated to particle size;a high detrital P content was found in coarse silt and very coarse silt.From the inside of the river mouth to the gate of the river mouth,organic P,Fe-bound P and refractory P in the suspended particles decreased and a higher amount of exchangeable P appeared around the gate of the river mouth.From the gate of the river mouth to the sea,exchangeable P and organic P in suspended particles increased distinctly.The total particulate P flux into the estuary from the Changjiang River was about 45.45×108 μmol/s during sampling.Of this,about 8.27×108 μmol/s was associated with the "truly suspended" fraction.The bio-available particulate P flux was about 13.58×108 μmol/s.Of this,about 4.24×108 μmol/s was transported by "truly suspended" particles.
采用3对特异性引物,对中国近海常见3种原甲藻的18S rDNA的部分序列进行PCR扩增,运用变性梯度凝胶电泳技术(Denaturing Gradient Gel Electrophoresis,DGGE)对PCR产物进行了差异性分析。结果表明,各对引物具有不同的区分效果,选择包含较多差异碱基的短片段进行扩增,可以对藻种进行更好的区分;PCR-DGGE技术具有较高的灵敏性,不同藻种间即使1个碱基的差异也可以区分开;PCR-DGGE技术可以对3种原甲藻进行区分。
