scholarly journals Temporal and Spatial Variations of Freshwater Reservoir Ages in the Loire River Watershed

Radiocarbon ◽  
2016 ◽  
Vol 58 (3) ◽  
pp. 549-563 ◽  
Author(s):  
C Coularis ◽  
N Tisnérat-Laborde ◽  
L Pastor ◽  
F Siclet ◽  
M Fontugne
Keyword(s):  
Inorganic Carbon ◽  
River Flow ◽  
Dissolved Inorganic Carbon ◽  
Dominant Factor ◽  
Reservoir Effect ◽  
Flow Discharge ◽  
Temporal And Spatial ◽  
Freshwater Reservoir ◽  
The Relationship ◽  
Loire River

AbstractIn order to map the freshwater reservoir effect (FRE) variability of the Loire River and its tributaries, spatial and temporal carbon isotope (13C and 14C) analyses of the dissolved inorganic carbon (DIC) were conducted. Sites were selected to represent the diversity of geological settings, soil type, and land use. Results show a large spatial variability of 14C FRE ranging between 135 and 2251±30 yr, objectively correlated to DIC contents and alkalinity. Deeper investigations of the relationship between 14C activity of DIC and environmental variables show that the geological substrate is the dominant factor in the 14C reservoir effect, and far more influential than the river flow discharge.

Influence of Aquatic Plant Photosynthesis on the Reservoir Effect of Genggahai Lake, Northeastern Qinghai-Tibetan Plateau

Radiocarbon ◽  
2017 ◽  
Vol 60 (2) ◽  
pp. 561-569 ◽  
Author(s):  
Yuan Li ◽  
Mingrui Qiang ◽  
Yanxiang Jin ◽  
Li Liu ◽  
Aifeng Zhou ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Lake Water ◽  
Aquatic Plant ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Reservoir Effect ◽  
Core Sediments ◽  
Plant Remains ◽  
Plant Photosynthesis ◽  
Gonghe Basin

AbstractTerrestrial plant remains in the sediments of lakes from semi-arid and arid regions are rare and therefore the establishment of a sediment chronology depends on accurate assessment of the reservoir effect of the lake water. In a study of Genggahai Lake in the Gonghe Basin, northeastern Qinghai-Tibetan Plateau, we used accelerator mass spectrometry radiocarbon (AMS 14C) dating to determine the age of (1) dissolved inorganic carbon in the water (DICLW), (2) macrophyte remains in the uppermost samples of core sediments, (3) living P. pectinatus in the lake, and (4) dissolved inorganic carbon of spring water in the catchment. The results show that the ages of the DICLW (910 14C yr BP on average) were much younger than the ages of the groundwater (6330 14C yr BP on average), which may result mainly from CO2 exchange between the lake water and the atmosphere. In addition, the 14C ages of DICLW and macrophyte remains in the uppermost core sediments varied from site to site within the lake, which we ascribe to the different photosynthesis rates of Chara spp. and vascular plants. The higher photosynthesis rate of Chara spp. decreases lake-water pCO2, which leads to more atmospheric CO2 being absorbed by the lake water, and thereby greatly reducing the age of carbon species in areas dominated by Chara spp. Although Genggahai Lake is well mixed, the differences between the apparent ages of the lake water are significantly modulated by the photosynthesis intensity of submerged plants.

scholarly journals Calibration of Lacustrine Sediment Ages Using the Relationship Between 14C Levels in Lake Waters and in the Atmosphere: The Case of Lake Kinneret

Radiocarbon ◽  
2001 ◽  
Vol 43 (2B) ◽  
pp. 821-830 ◽  
Author(s):  
Mariana Stiller ◽  
Aaron Kaufman ◽  
Israel Carmi ◽  
Genia Mintz
Keyword(s):  
Lake Water ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Lacustrine Sediments ◽  
Lacustrine Sediment ◽  
Lake Kinneret ◽  
The Past ◽  
Organic And Inorganic Carbon ◽  
Lake Waters ◽  
The Relationship

The source of endogenic organic and inorganic carbon in lacustrine sediments is the dissolved inorganic carbon (DIC) in the lake water. The relation between the radiocarbon levels of DIC in Lake Kinneret and of CO2 in the atmosphere has been investigated. The ratio of the former to the latter was found to be 0.814 ± 0.013. This ratio is used for calibrating the age of the sediment according to the natural fluctuations in the atmospheric levels of 14C that occurred during the past 10,000 years.

scholarly journals Major Effects of Alkalinity on the Relationship Between Metabolism and Dissolved Inorganic Carbon Dynamics in Lakes

Ecosystems ◽  
2020 ◽  
Vol 23 (8) ◽  
pp. 1566-1580 ◽  
Author(s):  
Hares Khan ◽  
Alo Laas ◽  
Rafael Marcé ◽  
Biel Obrador
Keyword(s):  
High Frequency ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Singular Spectrum Analysis ◽  
Automatic Monitoring ◽  
Carbon Dynamics ◽  
Metabolic Changes ◽  
Calcite Precipitation ◽  
Wide Range ◽  
The Relationship

AbstractSeveral findings suggest that CO2 emissions in lakes are not always directly linked to changes in metabolism but can be associated with interactions with the dissolved inorganic carbon equilibrium. Alkalinity has been described as a determining factor in regulating the relative contributions of biological and inorganic processes to carbon dynamics in lakes. Here we analyzed the relationship between metabolic changes in dissolved oxygen (DO) and dissolved inorganic carbon (DIC) at different timescales in eight lakes covering a wide range in alkalinity. We used high-frequency data from automatic monitoring stations to explore the sensitivity of DIC to metabolic changes inferred from oxygen. To overcome the problem of noisy data, commonly found in high-frequency measurements datasets, we used Singular Spectrum Analysis to enhance the diel signal-to-noise ratio. Our results suggest that in most of the studied lakes, a large part of the measured variability in DO and DIC reflects non-metabolic processes. Furthermore, at low alkalinity, DIC dynamics appear to be mostly driven by aquatic metabolism, but this relationship weakens with increasing alkalinity. The observed deviations from the metabolic 1:1 stoichiometry between DO and DIC were strongly correlated with the deviations expected to occur from calcite precipitation, with a stronger correlation when accounting also for the benthic contribution of calcite precipitation. This highlights the role of calcite precipitation as an important driver of CO2 supersaturation in lakes with alkalinity above 1 meq L−1, which represents 57% of the global area of lakes and reservoirs around the world.

scholarly journals Temporal Changes of the 14C Reservoir Effect in Lakes

Radiocarbon ◽  
1997 ◽  
Vol 40 (2) ◽  
pp. 921-931 ◽  
Author(s):  
Mebus A. Geyh ◽  
U. Schotterer ◽  
M. Grosjean
Keyword(s):  
Arid Regions ◽  
Climate Changes ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Temporal Changes ◽  
Organic Fraction ◽  
Radiocarbon Dates ◽  
Reservoir Effect ◽  
Plant Remains ◽  
C Value

Conventional radiocarbon dates for sediment samples from aquatic systems and of coeval terrestrial samples deviate from each other due to the reservoir effect. The reservoir correction is usually assumed to be constant with time for a specific aquatic system. Our studies confirm that seasonal and secular changes are frequent and are governed by the limnological conditions. Lakes have two principal sources of 14C: atmospheric CO2 and the total dissolved inorganic carbon (TDIC) of the entering groundwater and runoff. The former has values of ca. 100 pMC; the latter usually has a 14C value well below 100 pMC. Atmospheric CO2 enters the lake by exchange via its surface. The proportions of these two kinds of input determine the magnitude of the reservoir correction in freshwater lakes. It is mainly a function of the volume/surface ratio of the lake and, consequently a function of the water depth. The surface of lakes with outflow does not change when sedimentation decreases the depth of the water. The depth of Schleinsee Lake in southern Germany has decreased from 30 to 15 m since ca. 9000 bp. As a result, the reservoir correction has decreased from ca. -1550 to -580 yr. In contrast, the depth of Lake Proscansko in Croatia increased with growth of the travertine dam and the reservoir correction changed from ca. -1790 to -2650 yr during the last 8800 yr. The largest fluctuations of lake levels occur in closed lakes in arid regions when the climate changes from humid to arid and vice versa. As a result, the reservoir correction of the 14C dates for the total organic fraction from Lejía Lake in the Atacama Desert of Chile varied between <-1800 yr and -4700 yr over a period of only 1800 yr between 11,500 and 9700 bp. The corresponding reservoir correction for the marl fraction is much higher. In summary, accurate and reliable 14C dating of lake sediments requires a study of the temporal changes of the reservoir effect by analysis of both the organic and marl fractions. The most reliable 14C dates are obtained from terrestrial plant remains.

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