Distribution characteristics of urban soil active organic carbon and nitrogen and related controlling factors

In order to understand the distribution characteristics and related affecting factors of soil active organic carbon and nitrogen in urban green space,the soil samples at the depths of 0-10 cm,10-20 cm,and 20-30 cm were collected from the green spaces in the urban parks,campuses,residential areas,roadsides,and factories in Hefei City of Anhui Province,East China,with the contents of soil microbial biomass carbon(MBC),microbial biomass nitrogen(MBN),dissolved organic carbon(DOC),and dissolved organic nitrogen(DON) determined,and taking the soil samples from the Shushan forest park in Hefei suburb as the comparison.Green space type had significant effects on the soil active carbon and nitrogen(P0.05),and the contents of soil active carbon and nitrogen were decreased with increasing depth.As compared with the green space in the Shushan forest park in Hefei suburb,the urban green spaces had lower contents of soil active carbon and nitrogen.The contents of soil MBC,MBN,DOC,and DON in the urban green spaces were 46.81%-64.39%,49.90%-80.13%,28.95%-45.52%,and 5.67%-48.90% lower than those in the Shushan forest park green space,respectively,indicating that land use change could be the main factor leading to the changes of green space soil active carbon and nitrogen.Correlation analysis indicated that the soil MBC was positively correlated with the soil MBN and DON(P0.01),soil MBN was positively correlated with soil DOC(P0.01),and soil DOC was positively correlated with soil DON(P0.01).The soil active organic carbon and nitrogen also had negative correlations with soil pH(P0.01),suggesting that to appropriately reduce the intrusion of alkaline pollutants could be conducive to the accumulation of urban soil active organic carbon and nitrogen.