Sanjeev Kumar Professor E-mail: sanjeev AT prl.res.in Telephone : +91-79-26314265 (Office) +91-79-26314270 (Lab)

Research Statement

• My research interest broadly revolves around the cycling of bio-available elements in different ecosystems.
  I normally employ elemental and isotopic approaches to understand the interactions among physical, chemical,
  and biological processes that control the distribution of these elements in the Earth System, which ultimately regulate
  our environment and climate.

Current Research Projects

• Nitrogen and carbon cycling in the Indian estuaries and lakes
• Effect of natural and anthropgenic forcings on the coastal biogeochemistry of the Arabian Sea
• Dissolved trace gases and inorganic carbon dynamics in the Bay of Bengal and Arabian Sea
• Nitrogen and carbon transformation rates and stock assessment in soils of different ecozones of India
• Transport and evasion of carbon and nitrogen through Indian rivers
• Reconstruction of paleoenvironmental conditions using stable isotopes in lake sediments

Education

• Ph.D.                     Geology                                   Physical Research Laboratory, Ahmedabad, India
• M.Tech.             Applied Geology                   Indian Institute of Technology (IIT) - Roorkee, India
• B.Sc.                      Geology                                   Science College, Patna University, Patna, India

Professional Experience

• 2022-                   Professor                                 Physical Research Laboratory, Ahmedabad, India
• 2017-2021         Associate Professor              Physical Research Laboratory, Ahmedabad, India
• 2011-2016         Reader                                      Physical Research Laboratory, Ahmedabad, India
• 2010- 2011        Visiting Scholar                      University of Saskatchewan, Saskatoon, SK, Canada
                                Postdoctoral Fellow              Lakehead University, Thunder Bay, ON, Canada
• 2009- 2010       Postdoctoral Fellow               University of Victoria, Victoria, BC, Canada
                                                                                      Alberta Research Council (Victoria office) Victoria, BC, Canada
• 2007- 2008       Postdoctoral Fellow               St. Francis Xavier University, Antigonish, NS, Canada
• 2005- 2006       Postdoctoral Associate          University of Minnesota, Minneapolis-Saint Paul, MN, USA

Professional Services

• Associate Editor - Frontiers in Marine Science (2016- Present)

Group Members (Present and Past)

• Ms. Sangeeta Verma    (Scientific Assistant)
  
• Ms. Ajayeta Rathi    (Ph.D. Candidate)
  
• Mr. Siddhartha Sarkar    (Ph.D. Candidate)
  
• Mr. Mohammad Atif Khan    (Ph.D. Candidate)
  
• Mr. Abdur Rahman    (Postdoctoral Fellow)
  
• Dr. Saranya P    (National Postdoctoral Fellow)
  
• Dr. Niharika Sharma    (Presently at Academia Sinica, Taiwan)
  
• Dr. P. Ragavan    (Presently Scientist at MoFECC)
  
• Dr. Shah Rayees    (Presently Research Scientist at Kashmir University)
  
• Dr. Rupa Mukherjee    (Presently Assistant Professor at Rajendra College, Bihar)
  
• Dr. P. S. Bhavya    (Presently Research Scientist at Leibniz Institute, Germany)
  
• Dr. Manab Kumar Dutta   (Presently Research Scientist at NCESS, Trivandrum)
  

Selected Publications
  ( * Students or postdocs under supervision)

• Molecular tracers for characterization and distribution of organic matter in a
  freshwater lake system from the Lesser Himalaya
  D. Beheraa, S. Bhattacharyaa, A. Rahman, S. Kumar, A. Anoop
  Biogeochemistry (Accepted).


• Contribution of Carbon Fixation towards Carbon Sink in the Ocean Twilight Zone
  H. Saxena, D. Sahoo, S. Nazirahmed, D. Rai, A. Khan, N. Sharma, S. Kumar, and A. Singh
  Geophysical Research Letters, doi://10.1029/2022GL099044, 2022.


• Variability of particulate organic carbon and assessment of satellite retrieval algorithms over the eastern Arabian Sea
  S. Shaju, G. M. Sunny, Sherin C. K., Vishnu N., B. Reddy, Sudheesh V., Prachi M.,
  S. Kumar, Anilkumar V., G.V.M. Gupta
  Environmental Monitoring and Assessment, https://doi.org/10.1007/s10661-022-10264-9, 2022.


• Spectrochemical and stable isotopic characteristics of magnesite deposit from Salem, Southern India:
  CO2 repository through supergene processes
  A. Haritha, V.J. Rajesh, S. Kumar, M. Santosh, P.M. Thesniya
  Ore Geology Reviews, https://doi.org/10.1016/j.oregeorev.2022.105016, 2022.


• Control of regional climate on carbon and nitrogen turnover and their stable isotopic compositions in Indian soils
  N.Sharma* and S. Kumar
  Geoderma Regional, https://doi.org/10.1016/j.geodrs.2022.e00539, 2022.


• Holocene climate events and associated land use changes in the eastern coast of India:
  inferences from the Chilika Lagoon
  R. Shah*, I. Khan, A. Rahman, S. Kumar, H. Achyuthan, A. Shukla, P. Kumar, C. Dash
  The Holocene, https://doi.org/10.1177/09596836221106964, 2022.


• Water and sediment geochemistry of an urban lake:
  Implications to weathering and anthropogenic activity
  M. Saleem, Gh Jeelani, I. A. Pall, J. Ganai, S. Kumar
  International Journal of Sediment Research, https://doi.org/10.1016/j.ijsrc.2022.05.003, 2022


• Nitrous oxide in the central Bay of Bengal during the summer monsoon
  M. Atif Khan*, A. Rahman, D. Sahoo, H.Saxena, A. Singh, S. Kumar
  Regional Studies in Marine Science 52, 102314, https://doi.org/10.1016/j.rsma.2022.102314, 2022.


• Reassessing riverine carbon dioxide emissions from the Indian subcontinent
  O. K. Nayna, M. S. Begum, V.V.S.S. Sarma, J. Hartmann, S. Kumar, S. M. Tareq, J. Hyung Park
  Science of the Total Environment, 816, 151610, https://doi.org/10.1016/j.scitotenv.2021.151610, 2022.


• Signatures of natural to anthropogenic transition in lake sediments
  from the Central Himalaya using stable isotopes
  A. Rahman*, A. Rathi, R. Nambiar, P.K. Mishra, A. Anoop, R. Bhushan, S. Kumar
  Applied Geochemistry, 134, 105095, https://doi.org/10.1016/j.apgeochem.2021.105095, 2021.


• C-Sr isotope stratigraphy of carbonate formations of the late Neoproterozoic -
  Cambrian Marwar Supergroup
  B. G. George, S. Kumar, J.S. Ray
  Precambrian Research, 364:106378, doi: 10.1016/j.precamres.2021.106378, 2021.


• Monsoon signature in corals from the northern Indian Ocean
  H. Raj R. Bhushan, S. Kumar, U. Banerji, C. Shah, S. Verma
  Journal of Marine Systems, https://doi.org/10.1016/j.jmarsys.2021.103664, 2021.


• Trait-based and taxonomic macrofauna community patterns in the
  upwelling ecosystem of the southeastern Arabian Sea
  S. K. Sivadas, GVM Gupta, S. Kumar, B. S. Ingole
  Marine Environmental Research,170, 105431, https://doi.org/10.1016/j.marenvres.2021.105431, 2021.


• Biomass and vegetation carbon stock in mangrove forests of the Andaman Islands, India
  P. Ragavan*, S. Kumar, K. Kathiresan, P.M. Mohan, R.S.C. Jayaraj, K. Ravichandaran, T. S. Rana
  Hydrobiologia, https://doi.org/10.1007/s10750-021-04574-1, 2021.


• Role of eddies and N2 fixation in regulating C:N:P proportions in the Bay of Bengal
  D. Sahoo, H. Saxena, S. Nazirahmed, S. Kumar, A. K. Sudheer, R. Bhushan, A. Sahay, A. Singh
  Biogeochemistry, https://doi.org/10.1007/s10533-021-00833-4, 2021.


• Hydrological characteristics of the Bay of Bengal water column using δ18O during the Indian summer monsoon
  A. Rahman*, M. Atif Khan*, A. Singh, S. Kumar
  Continental Shelf Research, 226, https://doi.org/10.1016/j.csr.2021.104491, 2021.


• Localized Pollution Impacts on Greenhouse Gas Dynamics in Three Anthropogenically Modified Asian River Systems
  Shirina Begum M., M. Bogard, D. Butman, C. Eliyan, S. Kumar, Xi Xi Lu,
  O. K. Nayna, L. Ran, J. E. Richey, S. M. Tareq, D. T. Xuan, R. Yu, J. Park
  Journal of Geophysical Research: Biogeosciences, 126, https://doi.org/10.1029/2020JG006124, 2021.


• Sources, controls, and probabilistic health risk assessment of fluoride contamination in groundwater
  from a semi-arid region in Gujarat, Western India: An isotope–hydrogeochemical perspective
  R. Mandal, A. Das, A. K. Sudheer, S. Kumar, S. Verma, M. Gaddam, R.D. Deshpande
  Environmental Geochemistry and Health, DOI: 10.1007/s10653-021-00894-2, 2021.


• Potential role of priming effect in the open ocean oxygen minimum zones - an outlook
  P. Ragavan* and Sanjeev Kumar
  Hydrobiologia, https://doi.org/10.1007/s10750-021-04574-1, 2021.


• The world's largest coastal deoxygenation zone is not anthropogenically driven
  Gupta, G.V.M., R. Jyothibabu, Ch.V.Ramu, A. Y. Reddy, K. K. Balachandran, V. Sudheesh,
  S. Kumar, N.V.H.K.Chari, K. F. Bepari, P. H. Marathe, B. Reddy, A. K. Vijayan
  Environment Research Letters, https://doi.org/10.1088/1748-9326/abe9eb, 2021.


• Carbon biogeochemistry of two contrasting tropical estuarine ecosystems during premonsoon
  M. K. Dutta*, S. Kumar, R. Mukherjee*, N. Sharma*, R. Bhushan,
  P. Sanyal, M. Paul, S. K. Mukhopadhyay
  Estuaries and Coasts, https://doi.org/10.1007/s12237-021-00908-3, 2021.


• Signatures of hyperthermal events in the Late Paleocene–Early Eocene limestone
  succession of the Jaisalmer basin, India
  A. Patra, A. Shukla, S. Kumar, B.P. Singh
  Carbonates and Evaporites, https://doi.org/10.1007/s13146-020-00666-6, 2021.


• Non-Redfieldian C:N:P ratio in the inorganic and organic pools of
  the Bay of Bengal during the summer monsoon
  D. Sahoo, H. Saxena, N. Tripathi, M. Atif Khan, A. Rahman,
  S. Kumar, A.K. Sudheer, A. Singh
  Marine Ecology Progress Series, 653, 41–55, https://doi.org/10.3354/meps13498, 2020.


• Paleoenvironment of the Central Himalaya during late MIS 3 using stable isotopic composition
  of lacustrine organic matter occluded in diatoms and sediments
  Abdur Rahman*, Siddhartha Sarkar*, and Sanjeev Kumar
  Quaternary International, https://doi.org/10.1016/j.quaint.2020.08.024, 2020.


• Gross rates of nitrogen transformation in soils of a global biodiversity hotspot (Western Ghats, India)
  Niharika Sharma* and Sanjeev Kumar
  Journal of Plant Nutrition and Soil Science, https://doi.org/10.1002/jpln.201900126, 2020.


• Effects of forest type alteration on gross nitrogen mineralization in soils of Southern India
  Niharika Sharma* and Sanjeev Kumar
  Journal of Forestry Research, https://doi.org/10.1007/s11676-020-01225-4, 2020.


• Zooplankton and Nekton: Gatekeepers of the Biological Pump (Editorial)
  R. Kiko, D. Bianchi, C. Grenz, H. Hauss, M.H. Iversen, S. Kumar, A. E. Maas, C. Robinson
  Frontiers in Marine Science, 7:545,doi: 10.3389/fmars.2020.00545, 2020.


• Nitrogen transformation rates in the Himalayan soils at different temperature and elevation conditions
  Niharika Sharma* and Sanjeev Kumar
  Journal of Soils and Sediments, https://doi.org/10.1007/s11368-020-02722-z, 2020.


• Dinitrogen Fixation Rates in the Bay of Bengal during Summer Monsoon
  H. Saxena, D. Sahoo, M. A. Khan, S. Kumar, A. K. Sudheer, and A. Singh
  Environmental Research Communications, 2, 051007, doi:10.1088/2515-7620/ab89fa, 2020.


• Gross nitrogen transformation rates in semi-arid tropical soils
  under different salinity and vegetation conditions
  Niharika Sharma* and Sanjeev Kumar
  Ecosphere,11(2):e03034.10.1002/ecs2.3034, 2020.


• Holocene palaeoenvironmental records from the high-altitude Wular Lake, Western Himalayas
  S. Rayees, H. Achyuthan, A. Lone, S. Kumar, P. Kumar,
  R. Sharma, Mohd. Amir, A. Singh, and C. Dash
  Holocene, https://doi.org/10.1177/095968361989559, 2020.


• Diurnal carbon dynamics in a mangrove-dominated tropical estuary (Sundarbans, India)
  M. K. Dutta*, S. Kumar, R. Mukherjee*, N. Sharma*,
  A. Acharya, P. Sanyal, R. Bhushan, S. K. Mukhopadhyay
  Estuarine, Coastal and Shelf Science, 229, https://doi.org/10.1016/j.ecss.2019.106426, 2019.


• Potential importance of N2 fixers in the coastal northwestern East- Japan Sea
  P. S. Bhavya, Jun-Oh Min , Jae Joong Kang, Jae Hyung Lee, Dabin Lee, Naeun Jo, Hyo Keun Jang
  Min Gu Kang, Myung Joon Kim, Jun Beom Lee, S. Kumar, Sang Heon Lee
  Regional Studies in Marine Science, https://doi.org/10.1016/j.rsma.2019.100785, 2019.


• Sources and transformations of organic matter in sediments of Asia's largest
  brackish water lagoon (Chilika, India) and nearby mangrove ecosystem
  R. Mukherjee^*, P. R. Muduli, S. Barik and S. Kumar
  Environmental Earth Science, 78:332, DOI: 10.1007/s12665-019-8329-6, 2019.


• The fate of ¹⁵N labeled urea in a soybean-wheat cropping sequence under elevated CO2 and/or temperature
  N. K. Lenka, S. Lenka, P. Mahapatra, N. Sharma, S. Kumar, S. B. Aher, and D. S. Yashona
  Agriculture, Ecosystems and Environment, 282, 23-29, https://doi.org/10.1016/j.agee.2019.04.033, 2019.


• The postmonsoon carbon biogeochemistry of the Hooghly-Sundarbans estuarine system
  under different levels of anthropogenic impacts
  M. K. Dutta^*, S. Kumar, R. Mukherjee*, P. Sanyal, and S. Mukhopadhyay
  Biogeosciences, 16, 289-307, https://doi.org/10.5194/bg-16-289-2019, 2019.


• Spatial variation of nitrogen uptake rates in the largest brackish water lagoon of Asia (Chilika, India).
  R. Mukherjee^*, S. Kumar, and P. R. Muduli
  Estuarine, Coastal and Shelf Science, 216, 87-97, https://doi.org/10.1016/j.ecss.2018.01.012, 2019.


• Nitrogen uptake potential under different temperature-salinity conditions:
  Implications for nitrogen cycling under climate change scenarios
  S. Kumar, P.S. Bhavya*, R. Ramesh, G.V.M. Gupta, F. Chiriboga, A. Singh,
  I. Karunasagar, A. Rai, A. Rehnstam-Holm, L. Edler and A. Godhe
  Marine Environmental Research, 141, 196-204, https://doi.org/10.1016/j.marenvres.2018.09.001, 2018.


• Geochemistry of carbonate formations of the Chhattisgarh Supergroup, central India:
  implications for Mesoproterozoic global events
  B. G. George, J.S. Ray and S. Kumar
  Canadian Journal of Earth Sciences, https://doi.org/10.1139/cjes-2018-0144, 2018.


• Reviews and syntheses: Anthropogenic perturbations to carbon fluxes in Asian river systems-
  Concepts, emerging trends, and research challenges.
  J.H. Park, O.K. Nayna, M.S. Begum, E. Chea, J. Hartmann, R.G. Keil,
  S. Kumar, X. Lu, L. Ran, J.E. Richey, V.V.S.S. Sarma, S. Tareq, D.T. Xuan, and R. Yu
  Biogeosciences, 15, 3049-3069, https://doi.org/10.5194/bg-15-3049-2018.


• Spatio-temporal variation in δ¹³C_DIC of a tropical eutrophic estuary (Cochin estuary, India)
  and adjacent Arabian Sea.
  P.S. Bhavya*, S. Kumar, G.V.M. Gupta, K.V. Sudharma,and V. Sudheesh
  Continental Shelf Research, 153, 75-85, https://doi.org/10.1016/j.csr.2017.12.006, 2018.


• Coping with catastrophe: foraging plasticity enables a benthic reef predator
  to survive in rapidly degrading coral reefs.
  R. Karkarey, T. Alcoverro, S. Kumar, and Rohan Arthur
  Animal Behaviour, 131, 13-22, https://doi.org/10.1016/j.anbehav.2017.07.010, 2017.


• Heavy metals in the Ganga (Hooghly) River estuary sediment column:
  evaluation of association, geochemical cycling and anthropogenic enrichment
  S. Samanta, K. Amrutha, T. K. Dalai and S. Kumar
  Environmental Earth Science, 76:140, DOI 10.1007/s12665-017-6451-x, 2017.


• Carbon uptake rates in the Cochin estuary and adjoining coastal Arabian Sea
  P. S. Bhavya*, S. Kumar, G.V.M. Gupta and V. Sudheesh
  Estuaries and coasts; 40:447,DOI 10.1007/s12237-016-0147-4, 2017.


• Aquatic Response of a coastal tropical pelagic microbial community to changed salinity and temperature
  G. Kaur-Kahlon, S. Kumar, A. Rehnstam-Holm, A. Rai, P.S. Bhavya, L. Edler,
  A. Singh, B. Andersson, I. Karunasagar, R. Ramesh, A. Godhe
  Aquatic Microbial Ecology, 77, 37-50,doi: 10.3354/ame01785, 2016.


• Carbonaceous Aerosol over semi-arid region of western India:
  Heterogeneity in sources and characteristics
  A.K. Sudheer, M. Y. Aslam, M. Upadhyay, R. Rengarajan, R. Bhushan, J. S. Rathore, S. K. Singh and S. Kumar
  Atmospheric Research 178-179, 268-278, http://dx.doi.org/10.1016/j.atmosres.2016.03.026, 2016.


• Carbon isotopic composition of suspended particulate matter and dissolved inorganic carbon
  in the Cochin estuary during post-monsoon
  P. S. Bhavya*, S. Kumar, G.V.M. Gupta, K.V. Sudharma,V. Sudheesh, and K.R. Dhanya
  Current Science, 110(8) 1539-1543, 2016.


• Nitrogen uptake dynamics in a tropical eutrophic estuary (Cochin, India) and adjacent coastal waters
  P. S. Bhavya*, S. Kumar, G.V.M. Gupta, V. Sudheesh, K.V. Sudharma, D.S.Varrier, K.R. Dhanya, and N. Saravanane
  Estuaries and coasts, 39,54-67, doi:10.1007/s12237-015-9982-y, 2016.


• Soil nitrogen dynamics within profiles of a managed moist temperate forest chronosequence
  consistent with long-term harvesting-induced losses
  L. Kellman, S. Kumar, and A. Diochon
  Journal of Geophysical Research - Biogeosciences, doi: 10.1002/2013JG002469, 2014.


• Primary production in the northern Red Sea
  M. A. Qurban, A. C. Balala, S. Kumar, P.S. Bhavya and M. Wafar
  Journal of Marine Systems, 132, 75-82, 2014.


• Modelling nitrogen in streamflow from Boreal forest watersheds in Alberta, Canada, using SWAT
  S. Kumar, B.M. Watson, G. Putz and E. Prepas
  Proc. Inter. SWAT conf., 417-429, 2012.


• Measurement of marine productivity using 15N and 13C tracers: some methodological aspects
  N. Gandhi, S. Kumar, S. Prakash, R. Ramesh and M. S. Sheshshayee
  Journal of Earth System Science, 120 (1), 1-13, 2011.


• Stable isotopic composition of suspended particulate matter in Lake Superior:
  Implications for nutrient cycling and organic matter transformaion
  S. Kumar, J.C. Finlay, and R. Sterner
  Biogeochemistry, 103, 1-14, 2011.


• Nitrogen sources for new production in the NE Arabian Sea
  N. Gandhi, R. Ramesh, S. Prakash, and S. Kumar
  Journal of Sea Research, 65, 265-274, 2011.


• Nitrogen uptake in the northeastern Arabian Sea during winter cooling
  S. Kumar, R. Ramesh, R.M. Dwivedi, M. Raman, M.S. Sheshashayee, and W. D'Souza
  International Journal of Oceanography, Doi:10.1155/2010/819029, 2010.


• Nitrogen uptake rates and new production in the northern Indian Ocean
  N. Gandhi, S. Prakash, R. Ramesh, and S. Kumar
  IJMS, 39(3),362-368, 2010.


• Interannual variations in water yield to lakes in northeastern Alberta:
  Implications for critical load estimation
  J.J. Gibson, S.J. Birks, S. Kumar, P. McEachern, and R. Haziwinkel
  Journal of Limnology, 69 (S1), 126-134, Doi:10.3274/JL10-69-S1-13, 2010.


• Site-specific estimates of water yield applied in regional acid sensitivity surveys across western Canada
  J. J. Gibson, S.J. Birks, D. Jeffries, S. Kumar, K. Scott, J. Aherne and P. Shaw
  Journal of Limnology, 69(S1): 67-76, DOI: 10.3274/JL10-69-S1-08, 2010.


• Nitrogen and Carbon uptake dynamics in Lake Superior
  S. Kumar, R.W. Sterner, and J.C. Finlay
  Journal of Geophysical Research - Biogeosciences, 113, G04003, Doi: 10.1029/2008JG000720, 2008.


• Isotopic constraints on the source of long-term nitrate accumulation in Lake Superior
  J.C. Finlay, R.W. Sterner, and S. Kumar
  Ecological Applications, 17(8), 2323-2332, 2007.


• Spatial and temporal variation of ammonium in Lake Superior
  S. Kumar, R.W. Sterner, J.C. Finlay, and S. Brovold
  Journal of Great Lakes Research, 33, 581-591, 2007.


• ¹⁵N enrichment in the surface Particulate Organic Nitrogen of the north-eastern Arabian Sea
  from the middle to the waning phase of the winter monsoon: possible causes
  S. Kumar and R. Ramesh
  Ocean Science Discussion, 4, 245- 264, 2007.


• Increasing stoichiometric imbalance in North America's largest lake :
  Nitrification in Lake Superior
  R.W. Sterner, E. Agnoustou, S. Brovold, G.S. Bullerjahn, J.C. Finlay, S. Kumar, R.M.L. McKay, and R.M.Sherrell
  Geophysical Research Letters, 34, L10406, Doi: 10.1029/2006GL028861, 2006.


• Effect of incubation time and substrate concentration on N-uptake rates by phytoplankton in the Bay of Bengal
  S. Kumar, R. Ramesh, S.Sardesai, and M. S. Sheshshayee
  Biogeosciences Discussion, 2, 1331-1352, 2005.


• Signature of terrestrial influence on nitrogen isotopic composition of suspended particulate matter in the Bay of Bengal
  S. Kumar, R. Ramesh, M. S. Sheshshayee, S.Sardesai and P.P. Patel
  Current Science, 88 (5), 770-774, 2005.


• Productivity measurements in the Bay of Bengal using 15N tracer: Implications to the global carbon cycle
  S. Kumar and R. Ramesh
  IJMS, 34 (2), 153-162, 2005.


• Natural isotopic composition of nitrogen in suspended particulate matter in the Bay of Bengal
  S. Kumar, R. Ramesh, N.B.Bhosle, S. Sardesai, and M.S. Sheshashayee
  Biogeosciences, 1, 63-70, 2004.


• High new production in the Bay of Bengal : Possible causes and implications
  S. Kumar, R. Ramesh, S. Sardesai, and M.S. Sheshashayee
  Geophysical Research Letters, 31, L18304, Doi: 10.1029/2004GL021005, 2004.