Holocene organic geochemical record from the Western Indus continental shelf (northern Arabian Sea)

The Holocene ◽  
2020 ◽  
Vol 30 (6) ◽  
pp. 810-819
Author(s):  
Sanober Kahkashan ◽  
Jianfang Chen ◽  
Xinhong Wang ◽  
Peter D Clift ◽  
Bassem Jalali ◽  
...  
Keyword(s):  
Primary Production ◽  
Continental Shelf ◽  
Arabian Sea ◽  
Warming Trend ◽  
Indus River ◽  
Geochemical Tracers ◽  
Northern Arabian Sea ◽  
Show Evidence ◽  
Winter Insolation

Primary production on the Western Indus continental shelf has been linked to the large quantities of nutrients delivered to the shelf by the Indus River. Multiple geochemical tracers and biomarker records, including stable isotopes (δ13C and δ15N), total organic carbon (TOC), total nitrogen (TN), molar carbon/nitrogen (C/N) ratio, the branched and isoprenoid tetraether (BIT) index, and glycerol dialkyl glycerol tetraether (GDGT), have been analyzed from the Indus-23AP sediment core recovered from the northern Arabian Sea. Our records show evidence of a mixture of marine and terrestrially derived organic matter (OM) during the last 14,000 years, as indicated by the C/N ratio, δ13C, δ15N, and the BIT index. The three sterol biomarkers (brassicasterol, dinosterol, and cholesterol) show concurrent enrichments during the last 3 millennia reflecting increased phytoplankton abundance because of increased Indus river discharge of nutrients during the summer monsoon. GDGT crenarchaeol enrichment is related to the BIT index. The TEX86-derived sea surface temperature (SST) record is shifted toward the summer season because Crenarchaeota are more abundant and active during periods of high primary production. SSTs indicate a long-term warming trend during the Holocene related to increasing winter insolation in the low latitudes northern Hemisphere.

scholarly journals Enhanced biological production in the southeastern Arabian Sea during spring intermonsoon

2012 ◽  
Vol 3 (2) ◽  
pp. 133 ◽  
Author(s):  
C.M. Laluraj ◽  
K.K. Balachandran ◽  
P. Sabu
Keyword(s):  
Primary Production ◽  
Arabian Sea ◽  
Water Mass ◽  
Light Limitation ◽  
Important Process ◽  
Northern Arabian Sea ◽  
Previous Season ◽  
Southeastern Arabian Sea ◽  
Saline Waters ◽  
Near Shore

Hydrographic observations in the southeastern Arabian Sea (SEAS) have identified a warm (>30°C) and stratified water mass (stability >5 × 10−5 m−1) along the near shore area between 10°N and 15°N during spring intermonsoon. This water mass was relatively low saline (34.2) and nitrate-rich (0.5 µM), favoring moderate primary production (6.7 mg C m−3 d−1). Since the mixing of the Arabian Sea and the Bay of Bengal waters is an important process during this period, the enhanced primary production in the SEAS is attributed to the entrainment of unconsumed nitrate left over during the previous season from the northern Arabian Sea. The season was further characterized by the presence of a deep chlorophyll a maximum (0.5 mg.m−3) in the outer shelf below (>50 m) the subducted Arabian Sea High Saline Waters, which was photosynthetically less active (<1.5 mg C m−3 d−1) due to light limitation.

Enhanced chlorophyllaand primary production in the northern Arabian Sea during the spring intermonsoon due to greenNoctilucascintillansbloom

2012 ◽  
Vol 8 (2) ◽  
pp. 182-188 ◽  
Author(s):  
Nikathithara V. Madhu ◽  
Retnamma Jyothibabu ◽  
Padinjaratte A. Maheswaran ◽  
Kadeparambil A. Jayaraj ◽  
Chittur T. Achuthankutty
Keyword(s):  
Primary Production ◽  
Arabian Sea ◽  
Northern Arabian Sea

The Stability of the WHO Reference Thromboplastin NIBS & C 67/40

1979 ◽  
Vol 42 (04) ◽  
pp. 1135-1140 ◽  
Author(s):  
G I C Ingram
Keyword(s):  
Human Brain ◽  
Collaborative Study ◽  
Calibration Constant ◽  
Long Term Stability ◽  
Freeze Dried ◽  
Show Evidence ◽  
Human Material ◽  
Reference Preparation ◽  
The Stability

SummaryThe International Reference Preparation of human brain thromboplastin coded 67/40 has been thought to show evidence of instability. The evidence is discussed and is not thought to be strong; but it is suggested that it would be wise to replace 67/40 with a new preparation of human brain, both for this reason and because 67/40 is in a form (like Thrombotest) in which few workers seem to use human brain. A �plain� preparation would be more appropriate; and a freeze-dried sample of BCT is recommended as the successor preparation. The opportunity should be taken also to replace the corresponding ox and rabbit preparations. In the collaborative study which would be required it would then be desirable to test in parallel the three old and the three new preparations. The relative sensitivities of the old preparations could be compared with those found in earlier studies to obtain further evidence on the stability of 67/40; if stability were confirmed, the new preparations should be calibrated against it, but if not, the new human material should receive a calibration constant of 1.0 and the new ox and rabbit materials calibrated against that.The types of evidence available for monitoring the long-term stability of a thromboplastin are discussed.

Remote sensing of phytoplankton fluorescence in northern Arabian Sea

2018 ◽  
Vol 51 (2) ◽  
Author(s):  
Imran Ahmed Khan ◽  
Lubna Ghazal ◽  
Mudassar Hassan Arsalan ◽  
Muhammad Faheem Siddiqui
Keyword(s):  
Remote Sensing ◽  
Arabian Sea ◽  
Northern Arabian Sea

scholarly journals Biogeochemical Controls on the Redox Evolution of Earth’s Oceans and Atmosphere

Elements ◽  
2020 ◽  
Vol 16 (3) ◽  
pp. 191-196 ◽  
Author(s):  
Christopher T. Reinhard ◽  
Noah J. Planavsky
Keyword(s):  
Redox State ◽  
Modeling Tools ◽  
Evolutionary Trajectory ◽  
Geochemical Tracers ◽  
Atmosphere System ◽  
Ocean Atmosphere ◽  
Dramatic Shift ◽  
Redox Evolution

The redox state of Earth’s atmosphere has undergone a dramatic shift over geologic time from reducing to strongly oxidizing, and this shift has been coupled with changes in ocean redox structure and the size and activity of Earth’s biosphere. Delineating this evolutionary trajectory remains a major problem in Earth system science. Significant insights have emerged through the application of redox-sensitive geochemical systems. Existing and emerging biogeochemical modeling tools are pushing the limits of the quantitative constraints on ocean–atmosphere redox that can be extracted from geochemical tracers. This work is honing our understanding of the central role of Earth’s biosphere in shaping the long-term redox evolution of the ocean–atmosphere system.

Long-term primary production trends in the Laurentian Great Lakes: a comparison of geochemical methods

2021 ◽  
Author(s):  
Euan D. Reavie ◽  
Meijun Cai ◽  
Carsten Meyer-Jacob ◽  
John P. Smol ◽  
Josef P. Werne
Keyword(s):  
Primary Production ◽  
Great Lakes ◽  
Laurentian Great Lakes

scholarly journals Nutrient retention behind a tropical mega-dam: a case study of the Sardar Sarovar Dam, India

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Harish Gupta ◽  
S. Kiran Kumar Reddy ◽  
Mounika Chiluka ◽  
Vamshikrishna Gandla
Keyword(s):  
Arabian Sea ◽  
Inorganic Nitrogen ◽  
Nutrient Retention ◽  
Significant Loss ◽  
N Removal ◽  
Narmada River ◽  
Sardar Sarovar ◽  
The Impact

AbstractIn this study, we demonstrate the impact of the construction of a mega-dam on the nutrient export regime of a large tropical river into the Arabian Sea. Long-term (11 years) fortnight nutrient parameters, upstream and downstream to Sardar Sarovar (SS) Dam, were examined to determine the periodical change in nutrient fluxes from the Narmada River, India. During this 11-year period, the average discharge of the Narmada River upstream to Rajghat (35.3 km3 year−1) was higher than that of downstream at Garudeshwar (33.9 km3 year−1). However, during the same period, the suspended sediment load was reduced by 21 million tons (MT) from 37.9 MT at Rajghat to 16.7 MT at Garudeshwar. Similarly, mean concentrations of dissolved silica (DSi) reduced from 470 (upstream) to 214 µM (downstream), dissolved inorganic phosphate (DIP) from 0.84 to 0.38 µM, and dissolved inorganic nitrogen (DIN) from 43 to 1.5 µM. It means that about 54%, 55%, and 96% flux of DSi, DIP, and DIN retained behind the dam, respectively. The estimated denitrification rate (80,000 kg N km−2 year−1) for the reservoir is significantly higher than N removal by lentic systems, globally. We hypothesize that processes such as biological uptake and denitrification under anoxic conditions could be a key reason for the significant loss of nutrients, particularly of DIN. Finally, we anticipated that a decline in DIN fluxes (by 1.13 × 109 mol year−1) from the Narmada River to the Arabian Sea might reduce the atmospheric CO2 fixation by 7.46 × 109 mol year−1.

scholarly journals CD34+ human marrow cells that express low levels of Kit protein are enriched for long-term marrow-engrafting cells

Blood ◽  
1996 ◽  
Vol 87 (10) ◽  
pp. 4136-4142 ◽  
Author(s):  
I Kawashima ◽  
ED Zanjani ◽  
G Almaida-Porada ◽  
AW Flake ◽  
H Zeng ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Bone Marrow Cells ◽  
Marrow Cell ◽  
In Utero ◽  
Fetal Sheep ◽  
Hematopoietic Stem ◽  
Show Evidence ◽  
Marrow Cells

Using in utero transplantation into fetal sheep, we examined the capability of human bone marrow CD34+ cells fractionated based on Kit protein expression to provide long-term in vivo engraftment. Twelve hundred to 5,000 CD34+ Kit-, CD34+ Kit(low), and CD34+ Kit(high) cells were injected into a total of 14 preimmune fetal sheep recipients using the amniotic bubble technique. Six fetuses were killed in utero 1.5 months after bone marrow cell transplantation. Two fetuses receiving CD34+ Kit(low) cells showed signs of engraftment according to analysis of CD45+ cells in their bone marrow cells and karyotype studies of the colonies grown in methylcellulose culture. In contrast, two fetuses receiving CD34+ Kit(high) cells and two fetuses receiving CD34+ Kit- cells failed to show evidence of significant engraftment. Two fetuses were absorbed. A total of six fetuses receiving different cell populations were allowed to proceed to term, and the newborn sheep were serially examined for the presence of chimerism. Again, only the two sheep receiving CD34+ Kit(low) cells exhibited signs of engraftment upon serial examination. Earlier in studies of murine hematopoiesis, we have shown stage-specific changes in Kit expression by the progenitors. The studies of human cells reported here are in agreement with observations in mice, and indicate that human hematopoietic stem cells are enriched in the Kit(low) population.

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