TY - JOUR
T1 - Geochemical and isotopic (U, Th) variations in lake waters in the Qinghai Lake Basin, Northeast Qinghai-Tibet Plateau, China
T2 - origin and paleoenvironmental implications
AU - Zhang, Pu
AU - Cheng, Hai
AU - Liu, Weiguo
AU - Mo, Lingtong
AU - Li, Xiangzhong
AU - Ning, Youfeng
AU - Ji, Ming
AU - Zong, Baoyun
AU - Zhao, Chen
N1 - Publisher Copyright:
© 2019, Saudi Society for Geosciences.
PY - 2019/2/1
Y1 - 2019/2/1
N2 - A uranium (U) geochemical study of lake water samples from Qinghai Lake, Northeast Qinghai-Tibet Plateau, China, was undertaken to assess the primary controls on lake water chemistry. The 234 U/ 238 U activity ratios of lake water exhibited limited spatial and vertical variations and were relatively high compared to the values measured in rivers worldwide (( 234 U/ 238 U) = 1.171), lower than in the four river discharge inside the Lake Qinghai catchment. The U concentrations also varied minimally within three vertical sampling profiles and exhibited spatial patterns in surface waters that correlated with the distribution of total dissolved solid (TDS) values and salinity concentrations. These data suggest that the variability in U, TDS, and salinity are partially controlled by evaporation or a different secondary concentration pathway. Moreover, the U concentration and 234 U/ 238 U activity ratio indicates that the length of this procedure, which is controlled by the duration of water-rock interaction, is probably an important factor to consider when accounting for the variable salinities of lakes located in similar geographical areas. The 230 Th XS content is primarily derived from the decay of dissolved 234 U. The various 230 Thxs concentrations observed in the water column are interpreted to reflect various scavenging residence times in Qinghai Lake, ranging from 0.7 to 4 years. The lower water mass age, such as at site 123, suggests a more rapid scavenging rate. Dissolved 232 Th is placed into the lake via the incomplete dissolution of lithogenic substances, such as dust aerosol, or other lithogenic sources (e.g., lake bed sediment or suspended riverine sediment). Water column 232 Th concentration data suggest that the Th concentrations of the lake water are controlled by three processes: (1) the dissolution of aerosol dust, (2) the dissolution of riverine and lake bed sediment, and (3) the scavenging of Th from the water.
AB - A uranium (U) geochemical study of lake water samples from Qinghai Lake, Northeast Qinghai-Tibet Plateau, China, was undertaken to assess the primary controls on lake water chemistry. The 234 U/ 238 U activity ratios of lake water exhibited limited spatial and vertical variations and were relatively high compared to the values measured in rivers worldwide (( 234 U/ 238 U) = 1.171), lower than in the four river discharge inside the Lake Qinghai catchment. The U concentrations also varied minimally within three vertical sampling profiles and exhibited spatial patterns in surface waters that correlated with the distribution of total dissolved solid (TDS) values and salinity concentrations. These data suggest that the variability in U, TDS, and salinity are partially controlled by evaporation or a different secondary concentration pathway. Moreover, the U concentration and 234 U/ 238 U activity ratio indicates that the length of this procedure, which is controlled by the duration of water-rock interaction, is probably an important factor to consider when accounting for the variable salinities of lakes located in similar geographical areas. The 230 Th XS content is primarily derived from the decay of dissolved 234 U. The various 230 Thxs concentrations observed in the water column are interpreted to reflect various scavenging residence times in Qinghai Lake, ranging from 0.7 to 4 years. The lower water mass age, such as at site 123, suggests a more rapid scavenging rate. Dissolved 232 Th is placed into the lake via the incomplete dissolution of lithogenic substances, such as dust aerosol, or other lithogenic sources (e.g., lake bed sediment or suspended riverine sediment). Water column 232 Th concentration data suggest that the Th concentrations of the lake water are controlled by three processes: (1) the dissolution of aerosol dust, (2) the dissolution of riverine and lake bed sediment, and (3) the scavenging of Th from the water.
KW - Lake water chemistry
KW - Northeast Qinghai-Tibet Plateau, China
KW - Paleoenvironments
KW - Qinghai Lake Basin
KW - U and Th isotopes
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U2 - 10.1007/s12517-019-4255-x
DO - 10.1007/s12517-019-4255-x
M3 - Article
AN - SCOPUS:85060852651
SN - 1866-7511
VL - 12
JO - Arabian Journal of Geosciences
JF - Arabian Journal of Geosciences
IS - 3
M1 - 92
ER -