Profiles

arjun

Arjun Chakrawal

Doktorand

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Works at Department of Physical Geography
Telephone 08-16 48 90
Email arjun.chakrawal@natgeo.su.se
Visiting address Svante Arrhenius väg 8
Room T 309
Postal address Inst för naturgeografi 106 91 Stockholm

About me

I am a doctoral student currently working on scaling problems related to biogeochemical processes in soil carbon cycling models. I have a background in hydrology specifically groundwater hydrology. My doctoral research goal is to understand the impact of micro-scale heterogeneities of soil structure on the macroscopic dynamics of microbial decomposition of soil carbon. Currently, I am trying to construct a theoretical model to link the two spatial scales and using hypothetical scenarios to test the model. 

Interests:

  • Soil carbon cycle modeling
  • Bioenergetics
  • Groundwater modeling
  • Agro-ecosystem modeling 
  • Data assimilation and parameter estimation
  • Global sensitivity and uncertainty analysis

Education:

GroundwatCh, Erasmus Mundus-MSc, 2016-17

BSc, MSc in Earth and Environmental Sciences, 2011-16

  • Indian Institute of Science (IISc), Bangalore, india

Upscaling project

An accurate representation of soil organic matter (SOM) decomposition dynamics in large scale Earth system models is required for a better prediction of carbon storage and its fluxes. Often soil scientists simplify the dynamics of soil carbon decomposition by assuming soils as well-mixed homogeneous compartments of varying substrate quality and microorganisms. However, soils are naturally heterogeneous, which results in a non-uniform spatial distribution of substrate carbon as well as microorganisms inhabiting it. Here, we introduce a methodology to account for spatial heterogeneities in soil carbon cycling models and discuss the limitations of using traditional models that neglect spatial variability.

The importance of spatially heterogeneous distribution of substrate at the micro-scale in soil organic matter (SOM) dynamics has been shown both experimentally and in modeling studies; however, a theoretical framework for understanding the effects of micro-scale heterogeneities on the macroscopic rate of decomposition of soil organic matter is lacking. Most soil carbon cycling models do not account for this micro-scale heterogeneity, motivating the development of a macro-scale model that can account for micro-scale heterogeneities. To meet this need, we use scale transition theory to analytically link micro- and macro-scale dynamics in a two dimensional spatially heterogeneous medium.

Bioenergetics Project

Energetic limitations on the microbial growth act as additional constraints to the decomposition of soil organic matter (SOM). The coupling of Gibbs energy in anabolic (biosynthesis) and catabolic biochemical reactions form a basis for the energy requirements of microorganisms growth. In SOM decomposition reactions, the substrate act as the carbon as well as the energy source. This reaction is associated with negative enthalpy change which result in the heat release from the system. This heat can be measured using micro-Calorimeter. In this project, we formulate a mass-energy balance model for SOM decomposition to explain the observed heat from soils. We aim to provide a general theoretical base for estimating biomass yield from routine thermodynamic measurement.

 

Teaching/TA'ing

  • GE 7006 Informations- och modelleringssystem för mark- och vattenresurser ( Information and Modeling Systems for Land and Water Resources, Masters level)

Last taught Jan 2018 – Feb 2018  Stockholm University

Teaching basics of data analysis using MATLAB

  • GE 8029 Informations- och modelleringssystem för mark och vattenresurser ( Information and Modeling Systems for Land and Water Resources, Masters level)

Last taught Nov 2018 – Dec 2018  Stockholm University

Development of introductory Python tutorials and teaching basics of data analysis using Python

  • GE 7078 Avancerad hydrogeologi (Advanced Hydrogeology, Masters level)

Last taught Feb 2019 – Mar 2019  Stockholm University

Responsibilities include: (in supervision of course instructure)
  • Development of groundwater flow and transport modeling excercise and tutorials
  • Teaching groundwater modeling using open source software ModelMuse-USGS

Conference Presentations

  • Ecology of Soil Microorganisms (ESM) 2018 Helsinki, Finland. (oral)

  • European Geosciences Union (EGU) 2019 (poster)

 

Last updated: April 26, 2019

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