The Release Of The Soil Phosphorus From Riparian Zones In The Huaxi River In Karst Region Of Guizhou Province,PRC

Riparian zone is an interlaced zone with amphibious characteristics in watershed ecosystem.The researches on riparian zone have important meanings for the environmental protection and non-point source pollution control.The Huaxi River in Guiyang of Guizhou province was selected as the research object and the riparian zone of the river was classified by field survey method.Furthermore,the simulation of surface runoff scour in different riparian zone were conducted and the runoff was collected.Correspondingly,soil infiltration,the content of phosphorus in runoff,and the release rule of phosphorus from soils were analyzed.The results showed that:(1)Along The Huaxi River,there were 22 different types of riparian zone.The degree of riparian diversity showed medium.The river bank mainly consisted of gravel soil and rock with poor water retention ability.The physical and chemical properties of riparian basin soil were variable and are related with each other properties.(2)The surface runoff was significantly different in different types of riparian zone.With the increase of filler number of the simulation water,the surface runoff rose.The initial surface runoff and cumulative surface runoff of the riparian type(Hills valley + Heavy gravel soil+ Park and green land+ severe interference type)both increased and reached the highest,8.31±0.17 mm and 0.17±0.08 mm,and averaged runoff 9.82±0.04 mm.The initial surface runoff were the lowest in different riparian type(Hilly slope +Loam + Construction land + Severe interference type,Hilly slope +Loam + Grass + Moderate interference type,Hilly valley + Loam + Grass + Severe interference type,Hilly valley + Loam,park + Green space,Hilly valley + Moderate interference + Gravel soil + Park,Green space + Moderately,Severe interference,Hilly valley + Light gravel soil + Green,park + Moderate interference type)were allequal to 0 mm.Meanwhile,the cumulative infiltration of soil moisture and steady infiltration were different in different types of riparian zone.With the increase of filler number,the soil infiltration gradually decreased,then reach steady.Except the individual sample points,the water infiltration reduced significantly after the second adding water.The cumulative infiltration of soil moisture and steady infiltration of the riparian zone(Hilly valley + gravel soil + park,green space + severe interference)reached the lowest,4.85±0.08 mm,and 0.31±0.01 mm,and the average infiltration were 0.97 + /-0.03 mm.The cumulative infiltration of soil moisture and steady infiltration of riparian zone(Hilly slope + Loam + Construction land + Severe interference type)reached the highest,97.71 ± 0.56 mm and 0.56 + /-0.12 mm,and the average infiltration amounted to 19.54±0.08 mm.(3)The amount of phosphorus loss from different types of riparian zone was significantly different.The initial phosphorus loss and average phosphorus loss of the riparian zone(Hilly valley + Loam + Arable land + Severe interference)were the highest.Total phosphorus and phosphate content in the initial runoff were 0.43mg/L±0.005 and 0.52±0.005 mg/L.The average total phosphorus and average phosphate content were 0.43 mg/L±0.005 ? 0.37 mg/L±0.003.The initial phosphorus loss and the average phosphorus loss of the riparian zone(Hills valley + loam +inland tidal flats + light interference)were the lowest and total phosphorus,phosphate content in the initial runoff were 0.01±0.001 mg/L and 0.01±0.001 mg/L.The average total phosphorus in runoff and the average phosphate content were 0.008 mg/L± 0.001 and 0.005±0.001 mg/L.Average total phosphorus loss in various types of riparian zone ranged from 0.005 to 0.43 mg/L.The average of phosphate loss content ranged from 0.004 to 0.37 mg/L.According to the quality standard of surface water environment,the quality of surface water were ? ~ ? type of surface water and most of surface water reached the quality standard of ?,? water.The results showed that the ecological environment of the riparian zone along the Huaxi River was relatively good.(4)According to four characteristics of riparian zone,interference had asignificant effect on soil water infiltration.The analysis between the factors influencing the water infiltration and the amount of soil water infiltration showed that the content of soil water had a significantly negative correlation with soil cumulative infiltration amount,but slope had a positive correlation with accumulated soil water content.Soil organic matter content also had a negative correlation with cumulative infiltration amount.Interference degree had no a significant correlation with cumulative water infiltration amount.Vegetation coverage also had no significant correlations with the accumulation infiltration amount of the soil water.(5)According to the characteristics of four types of theriparian zone,the type of land use had a significant impact on the phosphorus loss in surface runoff.At the same time,the analysis between the factors influencing the water infiltration and the content of total phosphorus and phosphate in surface water showed that the content of phosphorus in surface runoff had a positive correlation with soil effective phosphorus,interference degree and slope,and had a negative correlation with soil water content,soil organic matter,soil pH,and organic phosphorus.