Modern river discharge and pathways of supplied material in the Eurasian Arctic Ocean: evidence from mineral assemblages and major and minor element distribution

2000 ◽  
Vol 89 (3) ◽  
pp. 486-495 ◽  
Author(s):  
F. Schoster ◽  
M. Behrends ◽  
C. Müller ◽  
R. Stein ◽  
M. Wahsner
Keyword(s):  
Arctic Ocean ◽  
River Discharge ◽  
Minor Element ◽  
Element Distribution ◽  
Mineral Assemblages

Minor-Element Distribution in Olivine

1970 ◽  
Vol 78 (3) ◽  
pp. 304-325 ◽  
Author(s):  
Tom Simkin ◽  
J. V. Smith
Keyword(s):  
Minor Element ◽  
Element Distribution

Rare-earth and minor element distribution and petrographic features of fluorites and associated Mesozoic limestones of northwestern Sicily

1981 ◽  
Vol 32 (1-4) ◽  
pp. 255-269 ◽  
Author(s):  
A. Bellanca ◽  
P. Di Salvo ◽  
P. Möller ◽  
R. Neri ◽  
F. Schley
Keyword(s):  
Rare Earth ◽  
Minor Element ◽  
Element Distribution

scholarly journals Cryospheric Impacts of Soviet River Diversion Schemes

1984 ◽  
Vol 5 ◽  
pp. 61-68 ◽  
Author(s):  
T. Holt ◽  
P. M. Kelly ◽  
B. S. G. Cherry
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
River Discharge ◽  
Large Scale ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Sea Ice Concentration ◽  
Ice Concentration ◽  
The Arctic Ocean ◽  
The Impact

Soviet plans to divert water from rivers flowing into the Arctic Ocean have led to research into the impact of a reduction in discharge on Arctic sea ice. We consider the mechanisms by which discharge reductions might affect sea-ice cover and then test various hypotheses related to these mechanisms. We find several large areas over which sea-ice concentration correlates significantly with variations in river discharge, supporting two particular hypotheses. The first hypothesis concerns the area where the initial impacts are likely to which is the Kara Sea. Reduced riverflow is associated occur, with decreased sea-ice concentration in October, at the time of ice formation. This is believed to be the result of decreased freshening of the surface layer. The second hypothesis concerns possible effects on the large-scale current system of the Arctic Ocean and, in particular, on the inflow of Atlantic and Pacific water. These effects occur as a result of changes in the strength of northward-flowing gradient currents associated with variations in river discharge. Although it is still not certain that substantial transfers of riverflow will take place, it is concluded that the possibility of significant cryospheric effects and, hence, large-scale climate impact should not be neglected.

scholarly journals On the biogeochemical signature of the Lena River from its headwaters to the Arctic Ocean

2011 ◽  
Vol 8 (2) ◽  
pp. 2093-2143 ◽  
Author(s):  
I. P. Semiletov ◽  
I. I. Pipko ◽  
N. E. Shakhova ◽  
O. V. Dudarev ◽  
S. P. Pugach ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Arctic Ocean ◽  
River Discharge ◽  
Total Carbon ◽  
The Arctic ◽  
Time Shift ◽  
Laptev Sea ◽  
Lena River ◽  
The Arctic Ocean ◽  
The Laptev Sea

Abstract. The Lena River integrates biogeochemical signals from its vast drainage basin and its signal reaches far out over the Arctic Ocean. Transformation of riverine organic carbon into mineral carbon, and mineral carbon into the organic form in the Lena River watershed, can be considered a quasi-equilibrated processes. Increasing the Lena discharge causes opposite effects on total organic (TOC) and inorganic (TCO2) carbon: TOC concentration increases, while TCO2 concentration decreases. Significant inter-annual variability in mean values of TCO2, TOC, and their sum (TC) has been found. This variability is determined by changes in land hydrology which cause differences in the Lena River discharge, because a negative correlation may be found between TC in September and mean discharge in August (a time shift of about one month is required for water to travel from Yakutsk to the Laptev Sea). Total carbon entering the sea with the Lena discharge is estimated to be almost 10 Tg C y−1. The annual Lena River discharge of particulate organic carbon (POC) may be equal to 0.38 Tg (moderate to high estimate). If we instead accept Lisytsin's (1994) statement concerning the precipitation of 85–95% of total particulate matter (PM) (and POC) on the marginal "filter", then only about 0.03–0.04 Tg of POC reaches the Laptev Sea from the Lena River. The Lena's POC export would then be two orders of magnitude less than the annual input of eroded terrestrial carbon onto the shelf of the Laptev and East Siberian seas, which is about 4 Tg. The Lena River is characterized by relatively high concentrations of primary greenhouse gases: CO2 and dissolved CH4. During all seasons the river is supersaturated in CO2 compared to the atmosphere: up to 1.5–2 fold in summer, and 4–5 fold in winter. This results in a narrow zone of significant CO2 supersaturation in the adjacent coastal sea. Spots of dissolved CH4 in the Lena delta channels may reach 100 nM, but the CH4 concentration decreases to 5–20 nM towards the sea, which suggests only a minor role of riverborne export of CH4 for the East Siberian Arctic Shelf (ESAS) CH4 budget in coastal waters. Instead, the seabed appears to be the source that provides most of the CH4 to the Arctic Ocean.

scholarly journals Climate change and the Arctic hydrologic cycle as calculated by a global coupled atmosphere–ocean model

1995 ◽  
Vol 21 ◽  
pp. 91-95 ◽  
Author(s):  
James R. Miller ◽  
Gary L. Russell
Keyword(s):  
Arctic Ocean ◽  
River Discharge ◽  
Surface Air Temperature ◽  
Horizontal Resolution ◽  
Ocean Model ◽  
Hydrologic Cycle ◽  
Transient Simulation ◽  
The Arctic ◽  
Glacial Ice ◽  
The Arctic Ocean

A global coupled atmosphere–ocean model is used to examine the hydrologic cycle of the Arctic Ocean. The model has a horizontal resolution of 4° × 5°, nine vertical layers in the atmosphere and 13 in the ocean. River discharge into the Arctic Ocean is included by allowing runoff from each continental grid box to flow downstream according to a specified direction file and a speed that depends on topography. A 74 year control simulation of the present climate is used to examine variability of the hydrologic cycle, including precipitation, sea ice, glacial ice and river discharge. A 74 year transient simulation in which atmospheric CO2increases each year at a compound rate оf 1% is then used to examine potential changes in the hydrologic cycle. Among these changes are a 4°C increase in mean annual surface air temperature in the Arctic Ocean, a decrease in ice cover which begins after 35 years, and increases in river discharge and cloud cover. There is little change in the net difference between precipitation and evaporation. Also in the transient simulation, glacial ice on Greenland decreases relative to the control.

scholarly journals Recent trends and variability in river discharge across northern Canada

2016 ◽  
Vol 20 (12) ◽  
pp. 4801-4818 ◽  
Author(s):  
Stephen J. Déry ◽  
Tricia A. Stadnyk ◽  
Matthew K. MacDonald ◽  
Bunu Gauli-Sharma
Keyword(s):  
Arctic Ocean ◽  
River Discharge ◽  
Flow Regulation ◽  
Data Availability ◽  
Labrador Sea ◽  
James Bay ◽  
River Diversion ◽  
Northern Canada ◽  
Annual Variability ◽  
Hydropower Production

Abstract. This study presents an analysis of the observed inter-annual variability and inter-decadal trends in river discharge across northern Canada for 1964–2013. The 42 rivers chosen for this study span a combined gauged area of 5.26  ×  106 km2 and are selected based on data availability and quality, gauged area and record length. Inter-annual variability in river discharge is greatest for the eastern Arctic Ocean (coefficient of variation, CV  =  16 %) due to the Caniapiscau River diversion into the La Grande Rivière system for enhanced hydropower production. Variability is lowest for the study area as a whole (CV  =  7 %). Based on the Mann–Kendall test (MKT), no significant (p > 0.05) trend in annual discharge from 1964 to 2013 is observed in the Bering Sea, western Arctic Ocean, western Hudson and James Bay, and Labrador Sea; for northern Canada as a whole, however, a statistically significant (p < 0.05) decline of 102.8 km3 25 yr−1 in discharge occurs over the first half of the study period followed by a statistically significant (p < 0.05) increase of 208.8 km3 25 yr−1 in the latter half. Increasing (decreasing) trends in river discharge to the eastern Hudson and James Bay (eastern Arctic Ocean) are largely explained by the Caniapiscau diversion to the La Grande Rivière system. Strong regional variations in seasonal trends of river discharge are observed, with overall winter (summer) flows increasing (decreasing, with the exception of the most recent decade) partly due to flow regulation and storage for enhanced hydropower production along the Hudson and James Bay, the eastern Arctic Ocean and Labrador Sea. Flow regulation also suppresses the natural variability of river discharge, particularly during cold seasons.

scholarly journals Recent Eurasian river discharge to the Arctic Ocean in the context of longer-term dendrohydrological records

2007 ◽  
Vol 112 (G4) ◽  
pp. n/a-n/a ◽  
Author(s):  
G. M. MacDonald ◽  
K. V. Kremenetski ◽  
L. C. Smith ◽  
H. G. Hidalgo
Keyword(s):  
Arctic Ocean ◽  
River Discharge ◽  
The Arctic ◽  
The Arctic Ocean

Petrochemistry of metamorphosed pillows, and the geochemical status of the amphibolites (Proterozoic) from the Sirohi district, Rajasthan, India

1984 ◽  
Vol 121 (5) ◽  
pp. 465-473 ◽  
Author(s):  
P. K. Bhattacharyya ◽  
A. D. Mukherjee
Keyword(s):  
Regional Metamorphism ◽  
Element Distribution ◽  
Island Arcs ◽  
Oceanic Sediments ◽  
Crystalline Core ◽  
Mineral Assemblages ◽  
Trace Element Contents ◽  
Closed Systems ◽  
Low K ◽  
Middle Proterozoic

AbstractRelic pillows in the middle Proterozoic amphibolites, occurring in the Sirohi Road–Abu Road tract of Rajasthan, India exhibit contrasted mineral assemblages from core to rim – mimetic after the crystalline core, the zone of incipient crystallization, and the rim of the original pillows. The major element distribution pattern across the pillows indicates exchange of Na–Al for Ca (Mg, Fe) in an inner reaction zone, surrounding the core and in the inner margin of the rim, and Fe–Al exchange for Ca–Si at the outer margin of the rim.Despite such exchanges around the rims, these pillows have retained their initial geochemical characteristics internally and thus have largely acted as closed systems during post-emplacement metamorphism. Mineral parageneses indicate that the contrasted mineral assemblages could evolve from domainal characters of the co-existing fluids, the compositions of which were only buffered by the reacting minerals during regional metamorphism.The major, minor and trace element contents of the pillows and of amphibolites of diverse petrographic character in the region further establish that the pillow interiors and the massive amphibolites were least modified during metamorphism(s), and represent oceanic tholeiites. Their average 2300 ppm K, 4.5 ppm Rb, 150 ppm Sr, along with the K/Rb and K/Sr ratios of 510 and 15 respectively resemble that of the low K-tholeiites, occurring nearest to the trenches in modern island arcs. On the other hand, the higher values of 17300 ppm K, 4.9 ppm Rb, and 210 ppm Sr of the banded and the schistose amphibolites indicate that they were contaminated in various magnitudes by oceanic sediments.

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