From the sedimentologic view, this paper analyses the grain-size distribution and the chemical composition of the deposits from sand-dust storm, occurring in Harbin on March 20, 2002. The result indicates that there e...From the sedimentologic view, this paper analyses the grain-size distribution and the chemical composition of the deposits from sand-dust storm, occurring in Harbin on March 20, 2002. The result indicates that there exist plentiful coarse matters in the sand-dust deposits in Harbin, and the sand-dust composition presents obvious three peak distribution characteristics, indicating that the sand-dust in Harbin is composed of multi-origin components. The grain-size composition consists of silt （4-8Φ）, accounting for 71.18% of the total, sand （〉4Φ）, 21.70%, and clay （〈8Φ）, only 7.13%. The average grain size （Mz） is 5.14Φ. The chemical elements of the deposits are mainly SiO2 and A1203 and Fe203, totally occupying 77.8%. The enrichment factors （EF） of Mg, K, Si, Fe, Mn, P, Ti, Co, Ni and V elements are all about 1, which mainly come fi＇om lithosphere source, while parts of Cu, Pb, Zn, Cr and Se elements are from pollution sources out of lithosphere source, and As, Cd and Sb elements are mainly from pollution sources. Based on the comprehensive analysis of grain-size, chemical composition, enrichment factor （EF）, discriminant function （DF） and matter source index （PI）, this paper points out that the grain-size distribution and element composition of the sand-dust deposits in Harbin are evidently different from the loess and sand-dust in Lanzhou, and that matter source of the sand-dust in Harbin is different from the loess in Northwest China and the sand-dust in Lanzhon. The sand-dust deposits in Harbin are an admixture of coarse grains transmitted in short distance and fine grains transported in long distance. The plentiful coarse grains of the sand-dust deposits in Harbin origin from sand of local spot, and are the near-souroe deposits transported by low altitude airflow.展开更多
We represent a two-dimensional model of polydisperse granular mixtures with a power-law size distribution. The model consists of smooth hard disks in a rectangular box with inelastic collisions,driven by a homogeneous...We represent a two-dimensional model of polydisperse granular mixtures with a power-law size distribution. The model consists of smooth hard disks in a rectangular box with inelastic collisions,driven by a homogeneous heat bath at zero gravity.The width of particle size distribution is characterized by the only parameter,namely,the fractal dimension D.The energy dissipation of the mixture is increased as D increases or as e decreases.Furthermore,it is found that the steady-state properties of the mixture such as the collision rate,granular temperature,kinetic pressure and velocity distribution depend sensitively on size distribution parameter D.展开更多
This paper has demonstrated that there is great variation in the size range and chemical composition of metalliferous PM （particulate matter） present within Comarca Lagunera, M6xico due to the physiography of the te...This paper has demonstrated that there is great variation in the size range and chemical composition of metalliferous PM （particulate matter） present within Comarca Lagunera, M6xico due to the physiography of the terrain together the intense vehicular traffic, unpaved roads, cement and lime plants, marble quarries, brick plants, and the largest smelter of non-ferrous material in Latin America. Cascade impactor PM samples from six size ranges： 〈 0.49 μm, 0.49-0.9 μm, 0.9-1.5μm, 1.5-3.0 p.m, 3.0-7.2 μm and 7.2-10 μm were collected from inside two stacks within G6mez Palacios and Torreon cities. ICP-AES （inductively coupled plasma-atomic emission spectrometry） analysis on collected Whatman fiberglass filters demonstrates that the PM are matrices mostly constituted of carbonates and silicates with abundant fine metalliferous particles. The metals with the most concentrations averaged over all size ranges were Cu, Fe, Mn, Ni, Pb and Ti. The size distributions of metals detected in this work have been plotted as normalized histogram concentration of each size fraction, the total concentration, and the aerodynamic particle diameter, which is a useful method for comparing the contributions of coarse and fine particles to pollutant concentrations.展开更多
To evaluate the effect of vegetative filter strips on sediment trapping, the spatial distribution of deposited sediment, and the size distribution of deposited particles from hyperconcentrated flows, a simulated grass...To evaluate the effect of vegetative filter strips on sediment trapping, the spatial distribution of deposited sediment, and the size distribution of deposited particles from hyperconcentrated flows, a simulated grass filter strip experiment was conducted with plastic grass using an adjustable slope steel flume. The simulated vegetation cover was 36%, and the inflow sediment concentrations applied were 147, 238, 320, and 429 kg m^(-3). The sediment concentration in the outflow, and the sediment particle size were determined. The results showed that the grass filter strips trapped most of the sediment from inflow at low sediment concentration. The deposition efficiency decreased with increasing sediment concentration, being 55.2% and 15.7% in the 147 and 429 kg m^(-3)sediment treatments, respectively. Most of the deposited sediments were distributed in the upper flume. In addition, the grass filter strips mainly trapped the coarse sediment (particle size>10 μm).展开更多
基金Under the auspices of Natural Science Fund of Heilongjiang Province (No. G0213), Heilongjiang Province Education Bureau (No. 11511132)
文摘From the sedimentologic view, this paper analyses the grain-size distribution and the chemical composition of the deposits from sand-dust storm, occurring in Harbin on March 20, 2002. The result indicates that there exist plentiful coarse matters in the sand-dust deposits in Harbin, and the sand-dust composition presents obvious three peak distribution characteristics, indicating that the sand-dust in Harbin is composed of multi-origin components. The grain-size composition consists of silt （4-8Φ）, accounting for 71.18% of the total, sand （〉4Φ）, 21.70%, and clay （〈8Φ）, only 7.13%. The average grain size （Mz） is 5.14Φ. The chemical elements of the deposits are mainly SiO2 and A1203 and Fe203, totally occupying 77.8%. The enrichment factors （EF） of Mg, K, Si, Fe, Mn, P, Ti, Co, Ni and V elements are all about 1, which mainly come fi＇om lithosphere source, while parts of Cu, Pb, Zn, Cr and Se elements are from pollution sources out of lithosphere source, and As, Cd and Sb elements are mainly from pollution sources. Based on the comprehensive analysis of grain-size, chemical composition, enrichment factor （EF）, discriminant function （DF） and matter source index （PI）, this paper points out that the grain-size distribution and element composition of the sand-dust deposits in Harbin are evidently different from the loess and sand-dust in Lanzhou, and that matter source of the sand-dust in Harbin is different from the loess in Northwest China and the sand-dust in Lanzhon. The sand-dust deposits in Harbin are an admixture of coarse grains transmitted in short distance and fine grains transported in long distance. The plentiful coarse grains of the sand-dust deposits in Harbin origin from sand of local spot, and are the near-souroe deposits transported by low altitude airflow.
基金Supported by the National Natural Science Foundation of China under Grant Nos.10675048 and 1068006
文摘We represent a two-dimensional model of polydisperse granular mixtures with a power-law size distribution. The model consists of smooth hard disks in a rectangular box with inelastic collisions,driven by a homogeneous heat bath at zero gravity.The width of particle size distribution is characterized by the only parameter,namely,the fractal dimension D.The energy dissipation of the mixture is increased as D increases or as e decreases.Furthermore,it is found that the steady-state properties of the mixture such as the collision rate,granular temperature,kinetic pressure and velocity distribution depend sensitively on size distribution parameter D.
文摘This paper has demonstrated that there is great variation in the size range and chemical composition of metalliferous PM （particulate matter） present within Comarca Lagunera, M6xico due to the physiography of the terrain together the intense vehicular traffic, unpaved roads, cement and lime plants, marble quarries, brick plants, and the largest smelter of non-ferrous material in Latin America. Cascade impactor PM samples from six size ranges： 〈 0.49 μm, 0.49-0.9 μm, 0.9-1.5μm, 1.5-3.0 p.m, 3.0-7.2 μm and 7.2-10 μm were collected from inside two stacks within G6mez Palacios and Torreon cities. ICP-AES （inductively coupled plasma-atomic emission spectrometry） analysis on collected Whatman fiberglass filters demonstrates that the PM are matrices mostly constituted of carbonates and silicates with abundant fine metalliferous particles. The metals with the most concentrations averaged over all size ranges were Cu, Fe, Mn, Ni, Pb and Ti. The size distributions of metals detected in this work have been plotted as normalized histogram concentration of each size fraction, the total concentration, and the aerodynamic particle diameter, which is a useful method for comparing the contributions of coarse and fine particles to pollutant concentrations.
基金Supported by the National Natural Science Foundation of China (No. 40901131)the Fundamental Research Funds for the Central Universities of China (No. GK201103003)
文摘To evaluate the effect of vegetative filter strips on sediment trapping, the spatial distribution of deposited sediment, and the size distribution of deposited particles from hyperconcentrated flows, a simulated grass filter strip experiment was conducted with plastic grass using an adjustable slope steel flume. The simulated vegetation cover was 36%, and the inflow sediment concentrations applied were 147, 238, 320, and 429 kg m^(-3). The sediment concentration in the outflow, and the sediment particle size were determined. The results showed that the grass filter strips trapped most of the sediment from inflow at low sediment concentration. The deposition efficiency decreased with increasing sediment concentration, being 55.2% and 15.7% in the 147 and 429 kg m^(-3)sediment treatments, respectively. Most of the deposited sediments were distributed in the upper flume. In addition, the grass filter strips mainly trapped the coarse sediment (particle size>10 μm).
