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δ 13 C‐δ 18 O Covariance: An Effective Indicator of Hydrological Closure for Lakes?
Author(s) -
Jing'an CHEN,
Fushun WANG,
Guojiang WAN,
Degui TANG,
ZHANG David Dian,
Ronggui HUNAG,
Jian LI,
Tangfu XIAO
Publication year - 2008
Publication title -
acta geologica sinica ‐ english edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.444
H-Index - 61
eISSN - 1755-6724
pISSN - 1000-9515
DOI - 10.1111/j.1755-6724.2008.tb00653.x
Subject(s) - covariance , environmental science , hydrology (agriculture) , closure (psychology) , covariant transformation , eddy covariance , physical geography , geology , ecology , mathematics , ecosystem , statistics , geography , biology , geometry , geotechnical engineering , economics , market economy
The correlation between the δ 13 C and δ 18 0 in primary carbonates is affected by several factors such as hydrological balance, total CO 2 concentrations, climatic condition and lake productivity. The influence of these factors on the δ 13 C‐δ 18 0 correlation may be different on different time scales. In this paper, two different‐type lakes in southwestern China, Lake Erhai and Lake Chenghai, are selected to investigate the influence of climatic pattern on the δ 13 C‐δ 18 0 correlation and to evaluate the reliability of the δ 13 C‐δ 18 0 covariance as an indicator of hydrological closure. The results show that there exists good correlation between the δ 13 C and δ 18 0 in Lake Erhai (overflowing open lake) and in Lake Chenghai (closed lake). This suggests that the δ 13 C‐δ 18 0 covariance may be not an effective indicator of hydrological closure for lakes, especially on short time scales. On the one hand, a hydrologically open lake may display covariant δ 13 C and δ 18 0 as a result of climatic influence. The particular alternate warm‐dry and cold‐wet climatic pattern in southwestern China may be the principal cause of the δ 13 C‐δ 18 0 covariance in Lake Erhai and Lake Chenghai. On the other hand, a hydrologically closed lake unnecessarily displays covariant trends between δ 13 C and δ 18 O because of the buffering effect of high CO 2 concentration on the δ 13 C shift in hyper‐alkaline lakes. We should be prudent when we use the covariance between δ 13 C and δ 18 O to judge the hydrological closure of lake.