Characterizing urban soils in New York City: profile properties and bacterial communities

The influence of human activities on the development and functioning of urban soils and their profile characteristics is still inadequately understood. Microbial communities can change due to anthropogenic disturbances and it is unclear how they exist along urban soil profiles. This study investigates the dynamic soil properties (DSPs) and the bacterial communities along the profiles of urban soils in New York City (NYC) with varying degree of human disturbances. Eleven pedons were investigated across NYC as well as one control soil in a nearby non-urban area. Six soils are formed in naturally deposited materials (ND) and five in human-altered and human-transported materials (HAHT). For each soil, the profile was described and each horizon was sampled to assess DSPs and the bacterial community composition and diversity. The development and the DSPs of NYC soils are influenced by the incorporation of HAHT materials and atmospheric deposits. The most abundant bacterial taxa observed in the NYC soils are also present in most natural and urban soils worldwide. The bacterial diversity was lower in some soils formed in ND materials, in which the contribution of low-abundance taxa was more restricted. Some differences in bacterial community composition separated the soils formed in ND materials and in dredged sediments from the soils formed in high artifact fill and serpentinite till. Changes in bacterial community composition between soil horizons were more noticeable in urban soils formed in ND materials than in those formed in HAHT materials which display less differentiated profiles and in the non-urban highly weathered soil. The bacterial diversity is not linked to the degree of disturbance of the urban soils but the variations in community composition between pedons and along soil profiles could be the result of changes in soil development and properties related to human activities and should be consistently characterized in urban soils.