scholarly journals Projections for Future Radiocarbon Content in Dissolved Inorganic Carbon in Hardwater Lakes: A Retrospective Approach

Radiocarbon ◽  
2018 ◽  
Vol 60 (3) ◽  
pp. 791-800 ◽  
Author(s):  
Thomas M Blattmann ◽  
Martin Wessels ◽  
Cameron P McIntyre ◽  
Timothy I Eglinton

ABSTRACTInland water bodies contain significant amounts of carbon in the form of dissolved inorganic carbon (DIC) derived from a mixture of modern atmospheric and pre-aged sources, which needs to be considered in radiocarbon-based dating and natural isotope tracer studies. While reservoir effects in hardwater lakes are generally considered to be constant through time, a comparison of recent and historical DI14C data from 2013 and 1969 for Lake Constance reveals that this is not a valid assumption. We hypothesize that changes in atmospheric carbon contributions to lake water DIC have taken place due to anthropogenically forced eutrophication in the 20th century. A return to more oligotrophic conditions in the lake led to reoxygenation and enhanced terrigenous organic matter remineralization, contributing to lake water DIC. Such comparisons using DI14C measurements from different points in time enable nonlinear changes in lake water DIC source and signature to be disentangled from concurrent anthropogenically induced changes in atmospheric 14C. In the future, coeval changes in lake dynamics due to climate change are expected to further perturb these balances. Depending on the scenario, Lake Constance DI14C is projected to decrease from the 2013 measured value of 0.856 Fm to 0.54–0.62 Fm by the end of the century.

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 ◽  
2017 ◽  
Vol 60 (2) ◽  
pp. 561-569 ◽  
Author(s):  
Yuan Li ◽  
Mingrui Qiang ◽  
Yanxiang Jin ◽  
Li Liu ◽  
Aifeng Zhou ◽  
...  

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.


2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Han Zhang ◽  
Kuo Wang

AbstractSince preindustrial times, as atmospheric CO2 concentration increases, the ocean continuously absorbs anthropogenic CO2, reducing seawater pH and $$[{{\rm{C}}{\rm{O}}}_{3}^{2-}]$$[CO32−], which is termed ocean acidification. We perform Earth system model simulations to assess CO2-induced acidification for ocean in the East China, one of the most vulnerable areas to ocean acidification. By year 2017, ocean surface pH in the East China drops from the preindustrial level of 8.20 to 8.06, corresponding to a 35% rise in [H+], and reduction rate of pH becomes faster in the last two decades. Changes in surface seawater acidity largely result from CO2-induced changes in surface dissolved inorganic carbon (DIC), alkalinity (ALK), salinity and temperature, among which DIC plays the most important role. By year 2300, simulated reduction in sea surface $$[{{\rm{C}}{\rm{O}}}_{3}^{2-}]$$[CO32−] is 13% under RCP2.6, contrasted to 72% under RCP8.5. Furthermore, simulated results show that CO2-induced warming acts to mitigate reductions in $$[{{\rm{C}}{\rm{O}}}_{3}^{2-}]$$[CO32−], but the individual effect of oceanic CO2 uptake is much greater than the effect of CO2-induced warming on ocean acidification. Our study quantifies ocean acidification induced by anthropogenic CO2, and indicates the potentially important role of accelerated CO2 emissions in projections of future changes in biogeochemistry and ecosystem of ocean in the East China.


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 ◽  
2017 ◽  
Vol 60 (2) ◽  
pp. 705-716 ◽  
Author(s):  
Taibei Liu ◽  
Weijian Zhou ◽  
Peng Cheng ◽  
G S Burr

AbstractWe present radiocarbon (14C) measurements of dissolved inorganic carbon (DIC) from surface waters of 11 lakes, widely distributed in China. Surface lake water DIC F14C values show distinct differences, and we relate these to the physical exchange character (“open” or “closed”) of each lake. Open lakes studied here generally have lower DIC F14C values than closed lakes. We present a simple model of a lake water cycle to calculate an average residence time for each lake. Comparisons between lake DIC F14C and average residence time shows that the DIC F14C increases with the average residence time and reflects a steady-state.


1995 ◽  
Vol 40 (5) ◽  
pp. 994-1000 ◽  
Author(s):  
Toshihiro Miyajima ◽  
Yoshihiro Miyajima ◽  
Yuko T. Hanba ◽  
Koichi Yoshii ◽  
Tadatoshi Koitabashi ◽  
...  

2010 ◽  
Vol 33 (6) ◽  
pp. 1020-1030 ◽  
Author(s):  
Yan-Hui ZHANG ◽  
Yan-Jie AN ◽  
Chi ZHU ◽  
Shao YANG

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