Bacterial Diversity and Community Composition in a Range of Urban Soils of New York City.

The development of urban soils is likely to be influenced by human activities (e.g. human-altered and human-transported materials (HAHTM), soil excavation, mixing, compaction, contamination). Human disturbances can change dynamic soil properties (DSPs) and soil profile development. Soil is home of large microbial communities, that are sensitive to soil conditions and may respond to these disturbances. This project investigates the bacterial diversity, in correlation with DSPs, down through the profile of a range of urban soils collected across New York City, representing different parent materials, vegetative cover and moisture regime. Some soils were formed in naturally deposited materials (NDM) (e.g. till, outwash) while others were formed in HAHTM (e.g. coal ash, construction debris, dredged material). DSPs examined include pH, texture, organic C, salt, metals and available nutrients. Bacterial community composition was analyzed by extracting DNA and sequencing the 16S rRNA gene with Illumina MiSeq. Data were processed using QIIME and additional statistical tests in R. Soils formed in HAHTM had generally less developed profiles (A-C type) than NDM soils (A-B-C type). Soils formed in construction debris and coal ash were characterized by a high content of human artifacts (> 10%). They displayed higher average metal content and higher pH values, when carbonated artifacts (e.g. concrete) were present. Bacterial diversity was comparable, or slightly higher in these soils than in NDM soils. Differences in the bacterial community structure were observed between both soil categories. Bacterial diversity seemed to be driven by pH and Zn, two properties influenced by human activities through the presence of artifacts and atmospheric deposition. Decrease of bacterial diversity and changes in community structure with soil depth were more pronounced in NDM soils, possibly due to greater differentiation of horizons and hence of microorganism habitats.