Sediment is a principal reservoir which accumulates and releases the pollutants. It is an important way of nutrients releasing from pore water of sediments to overlying water across the sediment-water interface. Five ...Sediment is a principal reservoir which accumulates and releases the pollutants. It is an important way of nutrients releasing from pore water of sediments to overlying water across the sediment-water interface. Five sampling sites were selected in the Hengshui Lake. Overlying water and sediments were collected in each of them. The phosphorus fractions and their relationships were analyzed. The results showed that the change of the total phosphorus （TP） in sediment was similar to that of the total dissolved phosphorus （TDP） and soluble orthophosphate （PO4^3-） in pore water. The concentrations of PO4^3- in pore water were higher than those in overlying water, reflecting a possible diffuse trend for PO4^3-P in the five zones of Hengshui Lake. It is indicated that phosphorus and other nutrients will be transferred from sediment to pore water and then to overlying water, which can lead to lake eutrophication.展开更多
The five chemical associations of heavy metals have been extracted continuously using the Tessier extracting method. Results show that Cu, Pb, Fe, Zn and Cr in the sediments are mainly distributed in residual fraction...The five chemical associations of heavy metals have been extracted continuously using the Tessier extracting method. Results show that Cu, Pb, Fe, Zn and Cr in the sediments are mainly distributed in residual fraction, while the major chemical association of Mn is carbonates. Carbonate heavy metals are converted into Fe-Mn oxides in autumn. And in the low tidal flat, after carbonates have changed into ionic heavy metals, some of the elements are transported to the overlying water. Cu, Pb, Fe and Mn have good correlations with each other, and Zn, Cr also show their similarity of chemical behavior in the sediments.展开更多
Actual sandstone micromodel was used in this work to conduct the microscopic waterflooding experiment of ultra-low sandstone reservoir,since the inside seepage characteristics of microscopic waterflooding process of C...Actual sandstone micromodel was used in this work to conduct the microscopic waterflooding experiment of ultra-low sandstone reservoir,since the inside seepage characteristics of microscopic waterflooding process of Chang 8 ultra-low permeability sandstone reservoir of Upper Triassic Yanchang formation in Huaqing region of the Ordos Basin,China is difficult to observe directly.Combined with physical property,casting thin sections,constant-rate mercury injection capillary pressure and nuclear magnetic resonance,the influence of reservoir property on the waterflooding characteristics in pores were analyzed and evaluated.Seepage paths of waterflooding characteristics were divided into four types:homogeneous seepage,reticular-homogeneous seepage,finger-reticular seepage and finger-like seepage,the waterflooding efficiency of which decreases in turn.More than 70%of residual oil occurs as flowing-around seepage and oil film.Physical property,pore structure and movable fluid characteristics are all controlled by digenesis and their impacts on waterflooding efficiency are in accordance.Generally,the pore throat radius size and distribution and movable fluid percentage are closely related to waterflooding law.展开更多
文摘Sediment is a principal reservoir which accumulates and releases the pollutants. It is an important way of nutrients releasing from pore water of sediments to overlying water across the sediment-water interface. Five sampling sites were selected in the Hengshui Lake. Overlying water and sediments were collected in each of them. The phosphorus fractions and their relationships were analyzed. The results showed that the change of the total phosphorus （TP） in sediment was similar to that of the total dissolved phosphorus （TDP） and soluble orthophosphate （PO4^3-） in pore water. The concentrations of PO4^3- in pore water were higher than those in overlying water, reflecting a possible diffuse trend for PO4^3-P in the five zones of Hengshui Lake. It is indicated that phosphorus and other nutrients will be transferred from sediment to pore water and then to overlying water, which can lead to lake eutrophication.
基金This work is supported by the National Natural Science Focal Projects Foundation of China(Grant No.40131020)the National Natural Science Foundation of China(Grant No.49833030)+2 种基金the Venus Program Foundation for Young Scientists of Shanghai(Grant No.97QA14023)its Tracking Program(Grant No.01QMH1406)the Dawn Program of Shanghai Ecucational Development Foundation.
文摘The five chemical associations of heavy metals have been extracted continuously using the Tessier extracting method. Results show that Cu, Pb, Fe, Zn and Cr in the sediments are mainly distributed in residual fraction, while the major chemical association of Mn is carbonates. Carbonate heavy metals are converted into Fe-Mn oxides in autumn. And in the low tidal flat, after carbonates have changed into ionic heavy metals, some of the elements are transported to the overlying water. Cu, Pb, Fe and Mn have good correlations with each other, and Zn, Cr also show their similarity of chemical behavior in the sediments.
基金Project(2015KTCL01-09)supported by the Innovation Project of Science and Technology of Shaanxi Province,ChinaProject(2015M582699)supported by the China Postdoctoral Science Foundation+1 种基金Project(2016JQ4022)supported by the Natural Science Foundation Research Project of Shaanxi Province,ChinaProject(41702146)supported by the National Natural Science Foundation of China
文摘Actual sandstone micromodel was used in this work to conduct the microscopic waterflooding experiment of ultra-low sandstone reservoir,since the inside seepage characteristics of microscopic waterflooding process of Chang 8 ultra-low permeability sandstone reservoir of Upper Triassic Yanchang formation in Huaqing region of the Ordos Basin,China is difficult to observe directly.Combined with physical property,casting thin sections,constant-rate mercury injection capillary pressure and nuclear magnetic resonance,the influence of reservoir property on the waterflooding characteristics in pores were analyzed and evaluated.Seepage paths of waterflooding characteristics were divided into four types:homogeneous seepage,reticular-homogeneous seepage,finger-reticular seepage and finger-like seepage,the waterflooding efficiency of which decreases in turn.More than 70%of residual oil occurs as flowing-around seepage and oil film.Physical property,pore structure and movable fluid characteristics are all controlled by digenesis and their impacts on waterflooding efficiency are in accordance.Generally,the pore throat radius size and distribution and movable fluid percentage are closely related to waterflooding law.
