Effects Of Several Key Factors On Bromide,Phosphorus In Red Soil Transport Along With Runoff Mechanism

Abstract:Study on soil solute migration mechanism of soil degradation and agricultural non-point source pollution is not only the core content of research, but also the intersection of soil erosion, slope land hydrology, environmental science and other disciplines. Soil moisture migration pathways affect the slope surface water and solute transport; influence factors of hillslope hydrological changes but also an important factor inducing slope variation of water and sand and solute migration. To explore the differences between the formation of slope water migration pathway and its effect factors, and to analyze the impact of the differences on soil solute migration and its related parameters, provides the theory basis for soil solute soil erosion mechanism research, has the important practical significance and optimal management of efficient utilization of the agricultural ecological environment in the area of protection and soil and water resources. This research mainly in the red soil in southern hilly land, by the experimental method of simulating rainfall indoor, using a special design of small trough observation interflow, choose non adsorbing bromide ion and the adsorption of phosphorus as the subject investigated, to explore the existence conditions of water and sediment flow in soil slope soil erosion characteristics and soil solute transport, to reveal the antecedent soil moisture, bulk density, slope of the red soil hillslope interflow and solute transport mechanism. The principal conclusions of this analysis are as follows:1. Interflow under the antecedent soil moisture(ASM) at20%still exist soil adhesive force. In the low water content of3.5%,10%Interflow accounted less in the total amount of runoff, respectively53.3%,0%; in high water content20%and saturation, interflow accounted for the total runoff99.9%and76.1%, the main part of ASM is higher when the interflow of runoff. Sediment loss and runoff was positive correlation, different ASM of slope sediment loss relations is10%> saturation>20%>3.5%. Bromide ion in surface runoff present power function of the attenuation trend with rainfall duration, the relation of initial concentration is10%> saturation>20%>3.5%; however, interflow bromide ion concentration was gradually increased with the rainfall duration, The average concentration of bromide ion in different antecedent soil moisture of slope in the interflow has big difference. Except the ASM at10%has no interflow, other slope interflow bromide ion loss accounted for the total runoff loss of99.9%, showed that the interflow is an important way to non adsorbing chemicals loss. 2.Existence of interflow condition, With the increase of slope runoff amount decreased firstly and then increased, relationship is10°>5°>25°>20°>15°; interflow increase with the slope, interflow accounted for the runoff volume is25>20°>15°>10°>5°; the total loss of sediment is25°>20°>10°>15°>5°.Bromide loss in interflow in larger gradient (25°,20°) is the10.18-52.53times than in smaller slope (15°,10°,5°), and in20°,25°interflow bromide loss amount accounted for81%、95%of the total runoff loss, bromide ion almost loss all in interflow; the smaller slope surface runoff is the main pathway of bromide ion erosion, at the higher slope, interflow is leading role. For the strong adsorption of phosphorus, in the low slope condition, strong leaching effect by raindrop splash, while high slope the rapid flow of strong runoff erosion have accelerated the surface soil phosphorus dissolving. Therefore, the low slope (5°) and high grade (25°) runoff on slope surface soluble phosphorus (DP) concentration is obviously higher than other slope, the interflow of phosphorus loss is not significantly affected.3. The soil bulk density increases, the average intensity of slope runoff, surface runoff is greater; sediment loss was greater. Sediment loss and runoff were proportional relationship also was correlated with soil bulk density, the relationship of total sediment density is1.05<1.15<1.20<1.25; There is no interflow formation when soil density at1.25, the disciplinarian of interflow intensity and total interflow is1.05>1.15>1.20, Soil bulk density is more high the more difficult to produce the interflow. The relationship of average Bromide ion concentration about density at1.05,1.15,1.20is1.20>1.15>1.05, and Bromide ion’s amount is0.54、0.73、1.48mg respectively.4.Under saturated condition, compared with different ASMs, the smallest runoff volume and soil loss were obtained because of the red soil strongest compressive force, the most stable structure, and the longest initial runoff time at the mediate ASM level (20%), and the most water infiltration caused the formation runoff generation under saturated condition and. There were conversely results obtained at the highest ASW level (saturated condition). The loss of bromide ion in runoff and attrition rate changed as the change of ASW and the loss amount was ordered as20%>10%>2%.The total loss of phosphorus was ordered as saturation>20%>10%>2%, no matter dissolved phosphorus or solid phosphorus.