Sayak Basu

Indian Institute of Science Education and Research Kolkata · Department of Earth Sciences

The large difference in the fractionation of stable carbon isotopes between C3 and C4 plants is widely used in vegetation reconstructions, where the predominance of C3 plants suggests wetter and that of C4 plants drier conditions. The stable carbon isotopic composition of organic carbon (OC) preserved in soils or sediments may be a valuable (paleo-...

The large difference in the fractionation of stable carbon isotopes between C3 and C4 plants is widely used in vegetation reconstructions, where the predominance of C3 plants suggests wetter and that of C4 plants drier conditions. The isotopic composition of organic carbon (OC) preserved in soils or sediments may be a valuable (paleo-)environmental...

A multiproxy study involving bulk (TOC, δ13Corg, grain size) and molecular (n-alkane biomarkers) analyses is used to investigate surface sediments from the Mandovi estuary in Goa, west coast of India to determine the origin, distribution and composition of organic matter (OM). The δ13Corg and n-alkane based indices (terrigenous/aquatic ratio (TAR)...

The carbon isotopic composition of C3 plant leaf tissue (δ¹³CC3) provides insights into carbon cycling, climate, and vegetation at various spatiotemporal scales. By disentangling the competing influences of climatic and biological factors, modern δ¹³CC3 calibrations can offer quantitative constraints on their applications. In this work, we examined...

A multiproxy study involving bulk (TOC, δ13Corg, grain size) and molecular (n-alkane biomarkers) analyses is used to investigate surface sediments from the Mandovi estuary in Goa, west coast of India to determine the origin, distribution and composition of organic matter (OM). The δ13Corg and n-alkane based indices (terrigenous/aquatic ratio (TAR)...

Study region The Godavari River is the largest non-Himalayan, monsoon-fed river in India, providing water resources for ∼75 million people. Study focus Stable isotopes of Godavari River water in a pre-monsoon (dry) and monsoon (wet) season are used to evaluate seasonal and spatial dynamics and gain insights into hydrological processes, provenance...

Broad disagreement between modelled and observed trends of Indian summer monsoon (ISM) over the north-central part of the Indian subcontinent (NCI) implies a gap in understanding of the relationship between the forcing factors and monsoonal precipitation. Although the strength of the land–sea thermal gradient (LSG) is believed to dictate monsoon in...

Biomass burning is an important component of major biomes as it acts as an ecological forcing factor in controlling the vegetation composition as well as biomass production. Thus long-term paleo-fire records are required to understand the extent to which future fire regimes will affect ecosystem health and the global carbon balance. Unfortunately,...

Banni, located in the arid western India, is one of the largest tropical grasslands of the Asian continent. The net primary production in this grassland ecosystem is currently mediated by precipitation during the Indian summer monsoon (ISM). However, timing of the grassland expansion and its link to the intensity of monsoonal precipitation remains...

The dotted line represents the variations in the %Char in the Banni grassland for the last 4600 cal yr BP. The values of %Char has been taken from Pillai et al., 2017. The dashed line represents the variability of pCO2 concentration. The source of pCO2 dataset is Lüthi et al., 2008. (JPG)

Representative distribution of n-alkanes from the modern vegetation (trees and grasses) in Banni region. Pr and Ph represent the concentration of pristane and phytane isoprenoids in the vegetation. (JPG)

Representative distribution of long-chain n-alkanes derived from Chachi core sediments. Pr and Ph represent the concentration of pristane and phytane isoprenoids in the sediments. (JPG)

The %C4 plants for the last 4600 cal yr BP has been estimated using bulk δ13Corg, δ13CC29 and δ13CC31 values from the Chachi core sediments. Numbers in bold represent outliers. (DOCX)

Understanding the causes of large variations in carbon isotopic composition of C 3 plants (δ ¹³ C C3 ) is a key challenge for paleoenvironmental reconstruction. Several investigations have attempted to study the global patterns in the δ ¹³ C C3 values and their correlation with the precipitation variability. Sparse representation of dataset from lo...

The modern-day Godavari River transports large amounts of sediment (170 Tg per year) and terrestrial organic carbon (OCterr; 1.5 Tg per year) from peninsular India to the Bay of Bengal. The flux and nature of OCterr is considered to have varied in response to past climate and human forcing. In order to delineate the provenance and nature of organic...

The modern-day Godavari River transports large amounts of sediment (170 Tg per year) and terrestrial organic carbon (OCterr; 1.5 Tg per year) from peninsular India to the Bay of Bengal. The flux and nature of OCterr is considered to have varied in response to past climate and human forcing. In order to delineate the provenance and nature of organic...

Indian summer monsoon (ISM) rainfall is contributed by two moisture sources; Arabian Sea (AS) and Bay of Bengal (BoB). While monsoonal rainfall in eastern and central India is dominantly contributed by the vapor derived from BoB, the source of rainfall in western India is mostly from AS vapor. Meteorological conditions in these regions also differ....

We have undertaken a comprehensive study on sediments (catchment, surface and core) and modern vegetation samples in and around lake Ennamangalam, south India with focus on the reconstruction of past climate during mid to late Holocene epoch using lipid biomarkers (n-alkanes) distribution and carbon isotopic composition of organic matter (δ ¹³COM)....

The Indian monsoon shapes the livelihood of ca. 40% of world’s population. Despite dedicated efforts, comprehensive picture of monsoon variability has proved elusive largely due to the absence of long-term qualitative high-resolution record from key climatic zones and variability of monsoon with respect to various forcing mechanisms (e.g., solar in...

For the first time, carbon isotope ratios (d13C) of plants and occluded carbon in phytoliths were analyzed from three locations of the middle (26.5°N, 80.3°E) and lower (22.3°N, 87.3°E and 22.9°N, 88.5°E) Gangetic plains, India. The bulk d13C values of C3 plants range from –32.6 to –19.2‰ with an average of –29.6±1.9‰ (n=76, 1) and for C4 plants v...