Dissolved organic carbon and its controls of urban soil in Hefei, Eastern China

Abstract

Soil dissolved organic carbon (DOC) plays an important role in biogeochemical cycling and energy transformation in the ecosystem. The objectives of the study are to assess the impacts of land use types and planation modes on carbon dynamics and to determine the major soil factors influencing the DOC concentration in urban soils. The spatial pattern of DOC was studied with soil samples collected from a suburban natural forest park and urban green-lands (including campus green-land, park greenland, residential green-land, roadside green-land and factory green-land) in Hefei, Eastern China. The results showed that green-land types significantly impact on the DOC concentration (P<0.05) and that DOC concentration in suburban forest (44.28 mg kg -1 ) is obviously higher than that in the urban site (27.45 mg kg -1 ). The soil under arbor-lawn mode had the highest DOC concentration with an average of 44.96 mg kg -1 at the 0 to 30 cm soil depth. Land use change resulted in an obvious variation in soil DOC concentration (0 to 30 cm) across the environmental gradient. Results from regression analysis indicate that soil DOC concentration is significantly and positively correlated with soil moisture, soil NH4 + -N, microbial biomass nitrogen (MBN), dissolved organic nitrogen (DON), and negatively correlated with soil pH, bulk density, electric conductivity and total phosphorus. It is suggested that the expansion of the urban area may lead to the loss of DOC in the soil.