摘要
根据对1980年汛期在黄河18个水文站采集样品的分析结果,本文讨论了黄河悬浮物的粒度、矿物和化学组成从上游到下游的地理分异。
Huanghe is located in semi-dry and semi-humid areas and temperate climate zone. The soil formation processes have been disturbed by extremely serious soil erosion. The compositions of suspended matter in the Huanghe (Yellow River) were controlled by physical weathering. This was indicated by the following observations. 1) Most of the suspended matter, no matter from upper, middle or lower reaches, was products of physical breakdown of existing crystals, such as quartz, feldspar, mica and chlorite, 2) The differences in grain size distribution between the suspended matter in middle reach and loess may be only due to deposition of coarse particles during transport by water, 3) Correspondingly, the quartz content, which makes up the major part of coarse particles, is lower than that in loess, and the contents of feldspar and mica are higher.Owing to weak chemical weathering, rocks were the dominant factors controlling geographic variations of the composition of the suspended matter. According to the sources and composition characteristics, the suspended matter could be divided into four groups. 1) Suspended matter originated from base rocks in the Qinghai Plateau. The percentage of particles.o .063 mm is rather high (38% and 85%) , quartz is the mineral of the highest content, and contents of SiO2 and Na2O are rather high, while those of other oxides are low, 2) Suspended matter originated from the major coarse sediment producing area in the loess plateau, of which the content of sand and coarse, medium silt (>0.01mm) is>60%, feldspar is the mineral of the highest content,the chemical composition is similar to that of suspended matter in the Qinghai Plateau except the CaO content is higher. 3) Suspended matter originated from fine sediment producing area in the loess plateau, of which the content of fine silt and clay (<.0.01mm ) is >50%, mica is the mineral of the highest content, the content of SiO2 and Na2O are lower than those originated from coarse sediment producing area, while the content of other oxides are higher. 4)Suspended matter originated from both base rocks and loess, of which the content of particles >0.01mm is >50%, either quartz or feldspar is the mineral of the mineral of the highest content, but the content of mica is significantly higher than that of suspended matter in (1) and (2) groups, correspondingly, the content of SiO2 and Na2O are higher, while the contents of most other oxides are lower.In addition, soil erosion controlling factors play an active role in the controlling of compositions of the suspended matter. For example, the compositions of sus pended matter in Huanghe are controlled by compositions of loess in the major sediment producing area where 1)most of storm in Huanghe basin occurs, 2) the low resistant loess is of the thickest layer in the loess plateau, and 3) the vegetation is rare.The relations of grain size, mineral and chemical compositions are as fol-low: 1) Quartz and feldspar contents are high in coarse particles (0.01mm). Correspondingly, the content of SiO2 and Na2O are high either. 2) The contents of layer silicates, such as mica (including illite) are high in fine particles (<0.01mm). Correspondingly, the contents of A12O3, Fe2O3, CaO, MgO and K2O are high either.
出处
《地理研究》
CSSCI
CSCD
北大核心
1989年第4期96-106,共11页
Geographical Research
基金
地理研究所所长基金
关键词
悬浮物
黄河
化学地理
suspendel matter, yellow River, chemical geography
