Variability of aquatic chemistry in central Guizhou karst region, China |
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| Authors: | Bai Zhanguo Wan Guojiang |
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| Institution: | (1) Chinese Agricultural Ministry Key Laboratory of Plant Nutrition Research, Institute of Soils and Fertilizers, Chinese Academy of Agricultural Sciences, 0100081 Beijing;(2) State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, 550002 Guiyang |
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| Abstract: | It is necessary to understand the aquatic chemical characteristics of natural surface fresh water for water quality assessment.
The chemical data from different kinds of water in the central Guizhou karst area showed that spring water from carbonate
rock cracks (crack-water) is of neutrality or meta-alkalinity and C] Ca II type. The amounts of all ions and the concentrations
of HCO
3
-
and Ca2+ were higher in the autumn than in the spring, the crack-water was influenced by the infiltration of surface water in the
process of erosion and/or transportation with decreasing HCO
3
-
and increasing pH, SO
4
2-
, Cl-, K+ and Na+ during running in a certain distance on the land surface. In particular, the chemical compositions of the waters at Tianxingqiao
(upper-stream), Shuiliandong (mid-waterfall) and Luoshuitan (down-pool) near the Huangguoshu Waterfall were much different
from those of the crack-water. The concentrations of SO
4
2-
, Na+, Fe3+ and NO
3
-
varied closely with seasons. The CaCO3 deposited violently with CO2 release in the spring. In Lake Hongfeng the HCO
3
-
/SO
4
2-
equivalent ratios were only 2.1–2.4, but Ca2+ /Mg2+ up to 2.4-4.2. The Cl- concentration increased by a factor of 1 and Na+ by order of magnitude relative to the spring water. These indicated the increase in artificial pollutant discharge in the
Lake Hongfeng watershed. In addition, porewater in the soils covering carbonate rocks belongs to strongly mineralized water.
The obvious differences in water quality were controlled by carbonate deposition, sulphate mineralization and nitrogen fixation
as well as ammonification. It is indicated that the chemical compositions in the waters from the karst region were unstable
and changeable.
This project was financially supported by the IFS of Sweden and by the National Natural Science Foundation of China. |
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| Keywords: | karst region variability of aquatic chemistry central Guizhou Plateau |
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