Cenozoic Climatic Record for Monsoonal Rainfall over the Indian Region

Atmospheric carbon dioxide level is one of the major drivers responsible for the global temperature change (Lacis et al., 2010). The role of carbon dioxide as an important greenhouse gas, and its contribution towards regulation of global surface temperature has been recognized for over a century (Arrhenius, 1896; Chamberlin, 1899; Royer, 2006). The ice core records along with other proxy based records provides an evidence signifying a strong coupling between CO2 and global temperature for at least the last ~65 m.y. (million years) (Petit et al., 1999; Siegenthaler et al., 2005, Zachos et al., 2001). The intensification of convective hydrological cycle inducing heavy rainfall during high pCO2 condition is both simulated and estimated from General Circulation Models (GCM) and geochemical analyses of fossil record respectively (Kutzbach & Gallimore, 1989). The evidences of intensification of monsoon, which refer to the rainfall due to seasonal reversal of the wind direction along the shore of the Indian Ocean especially in the Arabian Sea and surrounding regions, are preserved in the sedimentary records from continental and oceanic region (Fig.1). The other factor which affected the regional hydrological cycle apart from the concentration of CO2 in the atmosphere is tectonic rise of Himalayan mountain. Proxy record based on parameters like stomata index, alkenones and boron isotopes clearly suggested high concentration of CO2 in the atmosphere (~400 ppm) during Miocene time. The estimated concentration of CO2 observed in the atmosphere was rather similar to the concentration of CO2 in the atmosphere measured in the recent years at Mauna Loa (Thoning et al., 1989). The effect of such high CO2 concentration is seen to have significantly modulated and altered the pattern of rainfall distribution, intensity and its spatial variability. Record from sedimentary archives from the continental and marine sites over the Indian region yielded evidence of warmer, wetter and higher temperature seasonal climate for the Miocene period. A similarity of signature both from continental region and the marine archives support the argument for the change in hydrological condition during last 20 m.y. The marine records are only a few but the largely scattered along the continental margin and central Indian Ocean. A more recent study of such sedimentary sequences lying on the western and eastern India provided glimpses of spatial variability of regional climate. The chapter will narrate the long term variation in Miocene monsoonal rainfall and its spatial pattern using large set of available observations from the palaeo record.https://digitalcommons.usu.edu/modern_climatology/1009/thumbnail.jp

Intense deep convective mixing in the Southeast Arabian Sea linked to strengthening of the Northeast Indian monsoon during the middle Pliocene (3.4 Ma)

The climate of the Indian Ocean is dominated by monsoon reversals, influencing hydrography and biogeochemistry of the Indian Ocean as well as land vegetation through changes in precipitation. During summer or southwest monsoon season, intense upwelling zones driven by Ekman spiral appear in the western and eastern parts of the Arabian Sea that enhance surface primary production and thus proliferation of distinct fauna and flora. During the winter season, northeast monsoon winds cause deep convective overturning (mixing) that injects nutrients to the surface ocean and increases surface production. As a result, the primary production in the Arabian Sea has bimodal annual distribution. The present study analyses 5.6 Ma record of surface-dwelling planktic foraminifera, Globigerina bulloides, Globigerinoides ruber and Globigerinoides sacculifer from Deep Sea Drilling Project Site 219, southeast Arabian Sea to understand changes in the surface ocean as driven by the Indian monsoon coinciding with the northern hemisphere glaciation (NHG). An increase in mixed-layer species at ~3.4 Ma suggests intense deep convective overturning caused by strong NE monsoon winds related to strengthening of NHG. G. bulloides shows a high positive relation with G. ruber during the past 3.4 Ma and a weak relation in the early Pliocene (5.6-3.4 Ma). The high G. bulloides percentages during the past 3.4 Ma could be linked to the injection of nutrients in the top layer by the advecting sub-surface nutrient-rich water

KINETICS AND MODELING OF TANNASE PRODUCTION USING ASPERGILLUS FOETIDUS IN BATCH FERMENTATION

Objective: To produce tannase enzyme using Aspergillus foetidus with red gram husk as substrate in batch fermentor and investigate the suitable un structured kinetic model for the system.Methods: The present study was done via two steps. At first to study the maximum production of tannase enzyme by Aspergillus foetidus (MTCC 3557) using red gram husk as a substrate in a modular ferment or followed by to develop the kinetic model of tannase production.Results: The maximum tannase activity and biomass concentration were found to be 157.26 U/ml and 7.12 g/l respectively at the end of 96 hours of fermentation. The biomass yield coefficient (YX/S) and the product yield coefficient (YP/S) were found to be 0.23 g of biomass/g of substrate and 21.2 U/g of substrate respectively. Logistic model, Luedeking-Piret model and substrate utilization kinetic model were found to represent closely the experimental data of growth kinetics, product formation kinetics and substrate utilization kinetics respectively.Conclusion: Tannase enzyme production was studied using A. foetidus with redgram husk as substrate by modular fermenter and suitable models were predicted. The kinetic parameters were also estimated by fitting the data to the model using the Lineweaver-Burk method.Â

Community wells for sustainable irrigation in tank commands: a case study

An optimization model has been formulated to maximize the net benefit from a tank command with conjunctive use of surface water from the tank and ground water from wells and community well in the tank area. The Kannangudi tank in Pudukkottai district, Tamil Nadu, India has been taken as the case study. Six crops were found in the command area and are considered for arriving the optimal cropping pattern. The study result shows that, the wells and community well in a tank command contributes to a sustainable irrigation and apparently maximize the net benefit from that tank command

Biochar composition-dependent impacts on soil nutrient release, carbon mineralization, and potential environmental risk: A review

Biochar application has multiple benefits for soil fertility improvement and climate change mitigation. Biochar can act as a source of nutrients and sequester carbon (C) in the soil. The nutrient release capacity of biochar once applied to the soil varies with the composition of the biochar, which is a function of the feedstock type and pyrolysis condition used for biochar production. Biochar has a crucial influence on soil C mineralization, including its positive or negative priming of microorganisms involved in soil C cycling. However, in various cases, biochar application to the soil may cause negative effects in the soil and the wider environment. For instance, biochar may suppress soil nutrient availability and crop productivity due to the reduction in plant nutrient uptake or reduction in soil C mineralization. Biochar application may also negatively affect environmental quality and human health because of harmful compounds such as polycyclic aromatic hydrocarbons (PAHs), polychlorinated dibenzodioxins, and dibenzofurans (PCDD/DF). In this review, we discuss the linkage between biochar composition and function, evaluate the role biochar plays in soil fertility improvement and C sequestration, and discuss regulations and concerns regarding biochar's negative environmental impact. We also summarize advancements in biochar production technologies and discuss future challenges and priorities in biochar research

Simulation of Water Balance Components Using SWAT Model at Sub Catchment Level

Simulation of Water Balance Components (WBCs) is import for sustainable water resources development and management. The Soil Water and Assessment Tool (SWAT) is a semi-distributed hydrological model to estimate the WBCs by forcing the hydrological response unit (HRU) and meteorological variables. The developed model simulates five WBCs viz. surface runoff, lateral flow, percolation, actual evapotranspiration and soil water at sub catchment level. To demonstrate the model compatibility a case study taken over Chittar catchment, Tamilnadu, India. The catchment was divided in to 11 sub catchments. The ten year interval LULC (i.e., 2001 and 2011), twenty year daily meteorological data (i.e., 2001–2020) and time invariant soil and slope data were used in developing the water balance model. Developed model was calibrated and evaluated with river gauge monthly discharging using SUFI-2 algorithm in SWAT-CUP. The model calibration performed in two stage i.e., pre-calibration (2001–2003) and post-calibration (2004–2010). The model performance was evaluated with unseen river gauge discharging data (i.e., 2011–2015). Then, results of statistical outputs for the model were coefficient of determination (R2) is 0.75 in pre-calibration, 0.94 in post-calibration and 0.81 in validation. Further strengthen the model confidential level the sub catchments level monthly actual evapotranspiration were compared with gridded global data GLEAM v3.6a. Finally, the developed model was simulate the five WBCs whereas, surface runoff, lateral flow, percolation, actual evapotranspiration and soil water at sub catchment level during 2001–2020. The sub catchment level WBCs trend helps to make fast and accurate decision. At all 11 sub catchments a long drought was observed during 2016–2018 due to failure of northeast monsoon. The WBCs were directly reinforced by their north east monsoon which gives the major portion of rainfall i.e., September to December. Hence all the WBCs were directly correlated with rainfall with or without time lag. By understanding the sub catchment level of monthly WBCs over the Chittar catchment is useful for land and water resource management

Distribution of deep-sea benthic foraminifera in the Neogene of Blake Ridge, NW Atlantic Ocean

This study describes and illustrates the evolution of deep-sea benthic foraminifera from the Blake Ridge during the late Neogene. In total, 305 species of benthic foraminifera belonging to 107 genera were identified. The Blake Ridge receives fine-grained nannofossil-bearing hemipelagic sediments, transported from the Canadian continental margin by the Deep Western Boundary Undercurrent (DWBUC). We thus presume that changes in benthic foraminifera at Ocean Drilling Program (ODP) sites 991A, 994C, 995A and B and 997A reflect mainly changes in the intensity of the DWBUC, which is closely related to North Atlantic Deep Water (NADW) production. However, the dominance of Uvigerina peregrina, U. proboscidea and Cassidulina carinata during the late Miocene in all the holes suggests an increased influence of Southern Component Waters in the Blake Ridge region. During the early Pliocene (4.8-2.8 Ma) in all the sites benthic faunal assemblages suggest that there was an increased transport of organic-rich sediments by the DWBUC from the Canadian margin to the Blake Ridge, driven by increased production of NADW. During this time the species diversity (Sanders' rarefied values) was low. In the younger interval (since 2.8 Ma), the faunal data suggest less transport of organic-rich sediments to the Blake Ridge, which appears to be related to weakening of the DWBUC during cold intervals. An increase in species diversity at 3 Ma probably resulted from decreased population of bacteria due to low organic matter and/or less competition. In the late Pleistocene (c.0.6 Ma), Stilostomella lepidula became extinct in all the studied holes, suggesting that this species may have possessed a mode of feeding which no longer existed in the cold, well-oxygenated oceans of the present

Relative abundances of twenty-eight dominant benthic foraminifera species of DSDP Hole 23-219 (Table 1s)

Tropical climate is variable on astronomical time scale, driving changes in surface and deep-sea fauna during the Pliocene-Pleistocene. To understand these changes in the tropical Indian Ocean over the past 2.36 Myr, we quantitatively analyzed deep-sea benthic foraminifera and selected planktic foraminifera from >125 µm size fraction from Deep Sea Drilling Project Site 219. The data from Site 219 was combined with published foraminiferal and isotope data from Site 214, eastern Indian Ocean to determine the nature of changes. Factor and cluster analyses of the 28 highest-ranked species distinguished four biofacies, characterizing distinct deep-sea environmental settings. These biofacies have been named after their most dominant species such as Stilostomella lepidula-Pleurostomella alternans (Sl-Pa), Nuttallides umbonifer-Globocassidulina subglobosa (Nu-Gs), Oridorsalis umbonatus-Gavelinopsis lobatulus (Ou-Gl) and Epistominella exigua-Uvigerina hispido-costata (Ee-Uh) biofacies. Biofacies Sl-Pa ranges from ~2.36 to 0.55 Myr, biofacies Nu-Gs ranges from ~1.9 to 0.65 Myr, biofacies Ou-Gl ranges from ~1 to 0.35 Myr and biofacies Ee-Uh ranges from 1.1 to 0.25 Myr. The proxy record indicates fluctuating tropical environmental conditions such as oxygenation, surface productivity and organic food supply. These changes appear to have been driven by changes in monsoonal wind intensity related to glacial-interglacial cycles. A shift at ~1.2-0.9 Myr is observed in both the faunal and isotope records at Site 219, indicating a major increase in monsoon-induced productivity. This coincides with increased amplitude of glacial cycles, which appear to have influenced low latitude monsoonal climate as well as deep-sea conditions in the tropical Indian Ocean