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 s...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.展开更多
Three extraction methods, ultrasonic assisted extraction (USE), microwave assisted extraction (MSE), and conventional single extraction (CSE), in conjunction with the modified three-stage BCR sequential extraction pro...Three extraction methods, ultrasonic assisted extraction (USE), microwave assisted extraction (MSE), and conventional single extraction (CSE), in conjunction with the modified three-stage BCR sequential extraction procedure (SEP) were applied to examine the contents of Cd, Cu, Cr, Ni, Pb and Zn from lake sediment samples, to know whether these techniques can reduce extraction time and improve reproducibility. The SEP and developed alternative single extrac- tion methods were validated by the analysis of certified reference material BCR 601. By the use of optimized sonication and microwave conditions, steps 1, 2 and 3 of the BCR sequential extraction methods (excluding the hydrogen peroxide digestion in step 3, which was not performed with sonication and microwave) could be completed in 15-30 min and 60- 150 s, respectively. The recoveries of total extractable metal contents in BCR 601, obtained by three single extractions ranged from 93.3%-102%, 88.9%-104% and 81.2%-96.2% for CSE, USE and MSE, respectively. The precision of the single extraction methods was found in the range of 3.7%-9.4% for all metals (n = 6).展开更多
基金Supported by the National Natural Science Foundation of China (Nos.40976044,40920164004 and 30490232)the National Basic Research Program of China (973 Program) (Nos.2002CB12405 and 2005CB422305)
文摘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.
基金Project supported by the Higher Education Commission of Pakistan (No.Ac-I/GS/963)
文摘Three extraction methods, ultrasonic assisted extraction (USE), microwave assisted extraction (MSE), and conventional single extraction (CSE), in conjunction with the modified three-stage BCR sequential extraction procedure (SEP) were applied to examine the contents of Cd, Cu, Cr, Ni, Pb and Zn from lake sediment samples, to know whether these techniques can reduce extraction time and improve reproducibility. The SEP and developed alternative single extrac- tion methods were validated by the analysis of certified reference material BCR 601. By the use of optimized sonication and microwave conditions, steps 1, 2 and 3 of the BCR sequential extraction methods (excluding the hydrogen peroxide digestion in step 3, which was not performed with sonication and microwave) could be completed in 15-30 min and 60- 150 s, respectively. The recoveries of total extractable metal contents in BCR 601, obtained by three single extractions ranged from 93.3%-102%, 88.9%-104% and 81.2%-96.2% for CSE, USE and MSE, respectively. The precision of the single extraction methods was found in the range of 3.7%-9.4% for all metals (n = 6).
