Isotopic and geochemical composition of marl lake waters and implications for radiocarbon dating of marl lake sediments

1983 ◽  
Vol 20 (4) ◽  
pp. 599-615 ◽  
Author(s):  
J. V. Turner ◽  
P. Fritz ◽  
P. F. Karrow ◽  
B. G. Warner

Radiocarbon dates on organic and calcareous fractions of sediment cores from marl lakes may yield anomalous ages due to the assumption of a constant hardwater correction factor along the sediment sequence. A study of eight marl lakes in southern Ontario that are actively precipitating calcium carbonate was conducted in order to assess those isotopic and aqueous geochemical parameters in modern lakes that may be utilized to estimate the history and extent of variations in the hardwater effect along such sediment sequences. Results show an increase in the δ13C composition of lake DIC (dissolved inorganic carbon) as approach to isotopic equilibrium with atmospheric CO2 occurs. Differences in the extent to which this equilibrium is established also appear responsible for observed differences in the 14C activity of DIC between lakes of as much as 20 pmc (percent modern carbon). These variations have been related to the relative residence times of water in each lake by examination of their corresponding seasonal variations in 18O and 2H content. Consequently δ13C and δ18O of marl and molluscs have been used to identify variations in the hardwater effect along the sediment profile. A profile of radiocarbon dates on marl from Little Lake in southern Ontario shows satisfactory agreement with an independently determined pollen chronology. Where certain criteria are met, marl deposits appear to be suitable material for establishing Quaternary chronology.

Elem Sci Anth ◽  
2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Kosuke Ota ◽  
Yusuke Yokoyama ◽  
Yosuke Miyairi ◽  
Shinya Yamamoto ◽  
Toshihiro Miyajima

Lakes are sensitive recorders of anthropogenic activities, as human society often develops in their vicinity. Lake sediments thus have been widely used to reconstruct the history of environmental changes in the past, anthropogenic, or otherwise, and radiocarbon dating provides chronological control of the samples. However, specific values of radiocarbon in different carbon reservoirs due to the different pathways of radiocarbon from the upper atmosphere to the lake, called the radiocarbon reservoir age, is always difficult to evaluate because of dynamic processes in and around lakes. There are few systematic studies on radiocarbon reservoir ages for lakes owing to the complex radiocarbon transfer processes for lakes. Here, we investigate lake waters of the Fuji Five Lakes with monthly monitoring of the radiocarbon reservoir effects. Radiocarbon from dissolved inorganic carbon (DIC) for groundwater and river water is also measured, with resulting concentrations (Δ14C) at their lowest at Lake Kawaguchi in August 2018 (–122.4 ± 3.2‰), and at their highest at Lake Motosu in January 2019 (–22.4 ± 2.5‰), despite a distance of 25 km. However, winter values in both lakes show similar trends of rising Δ14C (about 20‰). Our lake water DIC Δ14C results are compared to previously published records obtained from sediments in Lake Motosu and Lake Kawaguchi. These suggest that total organic carbon and compound-specific radiocarbon found in sediments are heavily influenced by summer blooms of aquatic organisms that fix DIC in water. Thus, future studies to conduct similar analyses at the various lakes would be able to provide further insights into the carbon cycle around inland water, namely understanding the nature of radiocarbon reservoir ages.


Radiocarbon ◽  
1978 ◽  
Vol 20 (3) ◽  
pp. 455-460 ◽  
Author(s):  
R A Parker ◽  
W M Sackett

Organic and carbonate carbon in sediments deposited in the Cariaco Basin and on the Mississippi River Delta and the total dissolved inorganic carbon in four water column profiles comprise the samples in this list. Except as noted below the samples were processed using the benzene synthesis and other procedures described by Mathews, et al (1972).


Radiocarbon ◽  
2015 ◽  
Vol 57 (3) ◽  
pp. 397-406 ◽  
Author(s):  
I Carmi ◽  
D Yakir ◽  
Y Yechieli ◽  
J Kronfield ◽  
M Stiller

A study of water and carbon isotopes was conducted in a bare plot in the unsaturated zone of the Yatir Forest in the northern Negev of Israel. Sediment cores were collected in three different seasons. Measurements include profiles of mineralogy, moisture and its δ18O and tritium content, dissolved inorganic carbon (DIC) and its δ13C (‰) and Δ14C (‰) content, and δ13C (‰) and Δ14C (‰) in the solid sediment. The profiles of moisture and δ18O in the cores show clearly the effect of evaporation. The tritium profile indicates infiltration of water (0.11 m yr−1). The source of carbon in the DIC is CO2 released by biotic activity through roots of trees and of seasonal plants, which show seasonal variations, and by decay of organic debris. The δ13C (‰) profiles show clearly the chemical transition from dissolved CO2 (δ13C = −22‰) to bicarbonate (δ13C = −14‰). At greater depth (–11.3‰), the δ13C becomes similar to the δ13C in the aquifer below (–12.5‰). The effect of secondary processes is evident in the profile of Δ14C in the DIC. It shows a clear decrease with depth due to exchange with the sediment at a rate of 10‰ yr−1. Precipitation of carbon from the DIC on the sediment is 1.1 mg C Lsed−1 yr−1, negligible compared to the 28 g C in 1 Lsed. In the solid sediment, there is a gradient in Δ14Ccarb at the top meter. The net precipitation of 14C from the DIC on the sediment (0.25 to 1.1‰ yr−1), corrected for decay, cannot be observed in the deeper sediment. The presence of 14C in the top 1 m of the sediment is explained by two possible processes: accumulation of 14C-tagged dust (∼0.05 mm yr−1) and/or long-term cumulative precipitation from the DIC.


2010 ◽  
Vol 61 (1) ◽  
pp. 119 ◽  
Author(s):  
Sonja Lojen ◽  
Ivan Sondi ◽  
Mladen Juracic

Conditions for the preservation of recent aragonite-rich sediments during early diagenesis in two semi-enclosed Mediterranean karstic seawater lakes on the island of Mljet (Adriatic Sea) were examined. The concentrations and stable isotope compositions of carbonate and sedimentary organic matter, as well as the geochemical parameters in pore water were measured. It was found that the smaller lake (Malo Jezero) receives considerably more terrestrial detritus than the larger lake (Veliko Jezero). A decrease in carbonate δ13C values with depth indicated a rather intensive transfer of organically derived C into the carbonate pool by diagenetic recrystallisation, masking the changes in carbonate δ13C caused by increasing amounts of aragonite. Dissolution of calcite as a result of CO2 released from the decomposition of organic debris and the upward diffusive flux of dissolved inorganic carbon were together responsible for up to 24% of the dissolved inorganic carbon added to the pore water. This indicated locally occurring carbonate dissolution, irrespective of its saturation state in the bulk sediment. Despite the larger input of terrigenous material into Malo Jezero, the carbonate content in the sediment was much higher than in Veliko Jezero, indicating greater authigenic aragonite production. As magnesium calcite accounted for most of the carbonate dissolution, aragonite preservation in the sediment is favoured.


2021 ◽  
Author(s):  
Tiantian Sun ◽  
Michael E Böttcher ◽  
Jens Kallmeyer ◽  
Tina Treude ◽  
Marko Lipka ◽  
...  

<p>In the Black Sea, sediment cores covering the last brackish-limnic transition were recovered and investigated for anaerobic biogeochemical processes controlling sulfur, carbon, and metal cycling. The development of a sulfate-methane transition zone (SMTZ) is nowadays found below the brackish zone in the limnic part of the sediments that limits the upward migration of biogenic methane into surface sediments and the water column. The position of the SMTZ may have changed in the past due to dynamic fluxes of dissolved species in the pore water. Besides dissolved sulfate, metal-bearing minerals have been shown to serve as potential reactants, also converting CH<sub>4</sub> into dissolved inorganic carbon (DIC). The pore water and sediment stable isotope (C, S, O) and geochemical composition were investigated, as well as in-situ microbial rates of sulfate reduction and total anaerobic oxidation of CH<sub>4</sub> (AOM) obtained from sediment incubations for the identification of a potential contribution of manganese-bearing minerals to AOM in the limnic part of the sediments (Mn-AOM). In the limnic Black Sea sediments Mn-AOM is causes an upward flux of dissolved Mn whereas intense SO<sub>4</sub>-AOM located in shalower sediments leads to an increase in pH and a maximum in DIC concentrations in the SMTZ. The resulting change in saturation states leads to the precipitation of mixed MnCa-carbonate solid-solutions (‘rhodochrozitization front’) and the development of a zone enriched in excess sedimentary Mn(II). We further argue that these authigenic fronts may survive changes in pore water composition and are stable in the anoxic sedimentary record, marking the position of paleo-SMTZs. The persisting formation of this geochemical marker has advantage in application over the transient development of a sulfidization front of metastable mackinawite, that is fromed by the reaction of downard migrating sulfide with upward diffusing Fe(II), originating from SO<sub>4</sub>-AOM and Fe-AOM, respectively.</p>


1985 ◽  
Vol 42 (1) ◽  
pp. 70-76 ◽  
Author(s):  
K. R. Solomon ◽  
J. Y. Yoo ◽  
D. Lean ◽  
N. K. Kaushik ◽  
K. E. Day ◽  
...  

Permethrin (3-phenoxybenzyl(1RS)-cis,trans-3-(2,2-dimethy[-3-dichlorovinyl)-2,2-dimethylcyciopropanecarboxylate) applied to approximately 100-m3 enclosures (limnocorrals) in a small mesotrophic lake in Southern Ontario (47°51′25″N; 77°25′30″W) at concentrations of 500, 50, 5, and 0.5 μ∙L−1 dissipated from the water rapidly and approximated first-order kinetics in the first 8–12 d. Time taken for 50 and 90% dissipation ranged from 1.65 and 3.65 d, respectively, at 0.5 μ∙L−1 to 3.5 and 6.75 d, respectively, at 50 μ∙L−1. Inter- and intra-seasonal replication of dissipation patterns was good. Rate of dissipation varied slightly with depth, normally being slower at greater depth. Absorption of permethrin to sediments was rapid, penetration shallow, and disappearance slow. Permethrin had no effect on water chemistry but there was an increase in the Secchi disk depth in the treated limnocorrals. Dissolved inorganic carbon decreased in all limnocorrals, including controls after treatment, suggesting precipitation of calcium carbonate which may act as a scavenging agent for permethrin in the water. Limnocorrals are a useful tool for evaluating the behavior of pesticides in the aquatic system.


Radiocarbon ◽  
2001 ◽  
Vol 43 (2B) ◽  
pp. 821-830 ◽  
Author(s):  
Mariana Stiller ◽  
Aaron Kaufman ◽  
Israel Carmi ◽  
Genia Mintz

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.


Radiocarbon ◽  
1999 ◽  
Vol 41 (3) ◽  
pp. 271-286 ◽  
Author(s):  
Elisabeth Gibert ◽  
Yves Travi ◽  
Marc Massault ◽  
Tesfaye Chernet ◽  
Florent Barbecot ◽  
...  

We studied a 12.6-m-long sequence from Lake Abiyata (Central Ethiopia) to establish a reliable and accurate chronology for use in global paleoclimatic reconstructions. The 26 accelerator mass spectrometry radiocarbon (AMS 14C) ages, performed on carbonates and organic matter, define 2 parallel chronologies, representing the complete Holocene period. However, these chronologies show a significant discrepancy from 500 to 900 BP in depth; ages obtained on carbonates were always older than those on organic matter. The hydrogeological and geochemical behavior of the Lake Abiyata basin has shed light on this discrepancy. We found that the carbonate crystallization is due mainly to the mixing of lake waters with groundwaters from the multi-layered aquifer contained in the 600-m-thick basement of the lake. The 14C activity of total dissolved inorganic carbon (TDIC) measured by AMS from bottom and surface lake waters (111.4 and 111.8 pMC, respectively) confirms that the mixing occurs at the water-sediment interface. This evidence of groundwater participation in the carbonate crystallization calls into question the current paleoclimatic reconstructions based on inorganic carbonates in lakes. Specific attention should thus be given to the respective proportions of each end-member in the mixing for the quantitative estimation of the groundwater input. This will help to validate the paleoenvironmental reconstructions and to highlight an eventual diagenetical evolution of inorganic carbonates during burial, via the study of pore waters.


1999 ◽  
Vol 52 (3) ◽  
pp. 293-299 ◽  
Author(s):  
Giovanni Zanchetta ◽  
Francesco Paolo Bonadonna ◽  
Gabriello Leone

New stable isotope analyses on molluscan shells from a long core drilled in the crater lake of Valle di Castiglione, near Rome, extended the investigated portion of the core to 37 m. The succession of δ18O‰ values in the core interval 37–2.3 m ranges from −2.8 to +6.9‰ with only six samples below 0‰ (PDB). These results point to arid climatic phases coupled with the high measured δ18O values of the biogenic carbonate. In contrast, depleted 18O samples correspond to wet climatic periods, in agreement with a strong evaporative control on the lake water isotopic composition. The 13C content of the shells shows sharp changes controlled by the dissolved inorganic carbon isotope budget. Isotopic data suggest that the whole body of water behaved as a closed system, thus resembling lacustrine systems located in arid and semiarid regions where hydrological control dominates the geochemical parameters.


Radiocarbon ◽  
1997 ◽  
Vol 40 (2) ◽  
pp. 921-931 ◽  
Author(s):  
Mebus A. Geyh ◽  
U. Schotterer ◽  
M. Grosjean

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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