This study mainly studied the characteristics of non-point source pollution output of runoff areas of four different lands use pattern in Jianshan river

Chengjiang

under natural precipitation condition.The result showed that the total phosphorous outputs were different at various runoff areas of the lands use pattern

and the farmland had the maximum total phosphorous output among the four different runoff areas

and followed by planted forest

the secondary forest and shrub-grassland.The COD and NH 4-N outputs at planted forest and farmland were higher than the secondary forest and shrub-grassland.The non-point source pollution output at the four different runoff areas of different lands use pattern had no definate differences

however

on the whole view

the higher vegetation coverage caused the higher concentrations of phosphorous and nitrogen output in runoff

while leaded to the lower COD and NH 4-N

NO-3-N concentrations.The nitrate concentration reached 8.5~111 times of the nitrite

and the soluble nitrate was the main loss form.The eroded sediment was capable to enrich nutrient

and the enrichment ratios at secondary forest and shrub-grassland were higher than the farmland.The total phosphorous and nitrogen outputs at the eroded sediments of different lands use pattern were orderly followed as farmland

planted forest

shrub-grassland and secondary forest

but the available nitrogen and phosphorus concentrations were followed as farmland

planted forest

secondary forest and shrub-grassland.Compared with nitrogen

the surface soil phosphorus was more easily to be lost with the runoff activity

and the phosphorous output was mainly connected with sediment

particularly for the available phosphorus.