title: 2D visualization captures the local heterogeneity of oxidative metabolism across soils from diverse land-use.
abstract: Fine-scale processes in soils affect large-scale phenomena by controlling mixing and reaction rates, yet technological constraints have hampered the collection of micro-scale kinetic data. As a result, limited information is available on the magnitude of fine-scale biogeochemical rates and their temporal and spatial pattern in response to environmental perturbations. In this work we investigate the spatio-temporal dynamics in oxidative microbial activity and the development of anoxic micro zones (i.e., anoxic hot-spots) at the microscopic level (μm - cm). These analyses rely on novel non-invasive & non-destructive optodes, which are able to capture real-time imaging of oxygen concentrations over time at an interval of twenty seconds. Results showed that labile carbon addition resulted in maximum rates of local metabolic activity within a few minutes (5 to 15) and led to the subsequent formation of anoxic hot-spots. Different areas within a given soil sample presented up to one order of magnitude variation in metabolic rate values. As a result, oxic and anoxic micro-zones coexisted closely. The relationship between oxygen concentrations and heterogeneity of oxidative metabolism resulted in an initial increase in metabolic heterogeneity over time followed by a decrease when anoxic conditions dominated. A similar link was found by comparing metabolic activity and its heterogeneity across a range of soil types. These results demonstrate that the microbial activity and hot-spot development can be monitored by using a non-invasive quantitative imaging system that allows real-time monitoring of spatial oxygen distribution. We conclude that local dynamics of heterogeneity in space and time at the fine-scale present the same functional behavior encountered in most ecosystems at the landscape-scale.
authors: Department of Biological Sciences, Marine Environmental Biology Section, University of Southern California, Los Angeles, CA 90089, USA. Electronic address: rubol@usc.edu.
authors: Simonetta
authors: S
authors: Rubol
authors: Department of Civil & Environmental Engineering, Hanyang University, 222 Wangsimni-Ro, Seoul 04763, Republic of Korea.
authors: Tanushree
authors: T
authors: Dutta
authors: Department of Biodiversity and Molecular Ecology, Fondazione Edmund Mach, Research and Innovation Centre, S. Michele all'Adige Trento, Italy.
authors: Duccio
authors: D
authors: Rocchini
mesh_terms: D002244:Carbon / Q000378:metabolism; D004867:Equipment Design; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008853:Microscopy / Q000295:instrumentation / Q000379:methods; D010084:Oxidation-Reduction; D010100:Oxygen / Q000032:analysis / Q000378:metabolism*; D012987:Soil / Q000737:chemistry; D013030:Spain; D062211:Spatio-Temporal Analysis
chemical_list: D012987:Soil; D002244:Carbon; D010100:Oxygen
keywords: Interspersion; Labile substrate addition; Micro-habitats; Microbial activity; Planar optode; Real-time oxygen imaging