The Speciation Distribution Study Of Arsenic And Mercury In The Water Body Of Yellow River In Inner Mongolia Section

Heavy metal mercury and metalloid arsenic are listed toxic elements in environmental science. As unlackiny material in industrial production and scientific research, arsenic and mercury play an important function in human production and lives, but compounds of mercury and arsenic are usually toxic ,thus in their application ,they benefit human ,in one way ; cause environmental pollution ,threaten human health, in other way, and their harm to human and environment is closely related to their forms in environment.Yellow river is a richly silty river. Among the essential factors about yellow river, there is very little research about geochemical characteristics of mercury and arsenic. Using three-factor evaluation method, this paper mainly studied the unpolluted section of yellow river in Inner Mongolia, and synthetically evaluated the total and speciation content of mercury and arsenic in water column, suspended matter and sediment.This research will enrich and expand the environmental geochemical research contents of mid-upper reaches of yellow river, and has theoretic and practical meaning on Inner Mongolian water sources protection and reasonable utilization. The results found through various experiments are as below:1. All the content of soluble speciation of arsenic in water is very low, the content of arsenic in free subsiding water is much higher. So the arsenic in free subsiding water is actually this in suspended solid matter. Mercury in water is all undetected.2. Mercury in suspended matter is dominated by mercury bound to humus, because the strong combining ability of humus, this can be reference for mercury pollution harness.3. Arsenic in suspended matter is dominated by Ca-As and O-As; the content of A-As, Al-As and Fe-As is very low. The content of total arsenic, Ca-As and O-As decreased along the way. The variance of arsenic content along yellow river is directly decided by silt content in water. Silt content is related to geographic environment along the way, especially to the arsenic content of local soil and sediment and their supply for yellow river. Because, ninety percent of silt is from loess, the ratio of loess in suspended matter of yellow river directly affect the arsenic content of yellow river. Some previous research also show that the percent of Ca-As is 30%; rest '"wrapped" arsenic is 25%.4. Total content of arsenic decreased with depth of sediment column. This is mainly because the soluble arsenic in water can easily combine with Fe, Al and Ca in sediment surface to form insoluble arsenides; coprecipitate with several oxides and chlorides of Fe and Al, accumulated in sediment surface difficult to move. Arsenic in sediment is dominated by Ca-As, secondly O-As, very similar to the distribution of arsenic in loess, this further verified the deduction that arsenic in yellow river is from riversides soil.5. Total content of mercury decreased with depth of sediment column and dominated by mercury bound to humus, but with the increase of depth the content of mercury bound to humus decreased. The content of residual mercury increased along the way. The content of the rest three speciation was very low and had no obvious variation along the way.