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Application of allochthonous organic carbon and phosphorus forms in the interpretation of past environmental conditions 总被引:2,自引:0,他引:2
Changwei Lü Jiang He Huimin Sun Hongxi Xue Ying Liang Saruli Bai Ying Sun Lili Shen Qingyun Fan 《Environmental Geology》2008,55(6):1279-1289
Organic matter in sediments, for instance, carbon, nitrogen and phosphorus, can be used to reconstruct the paleoecological
and pollution history of lakes and their catchment basins. In this paper, the contents of allochthonous organic carbon (allochthonous
OC) and autochthonous organic carbon (autochthonous OC) in sediment cores taken from Wuliangsuhai Lake and Daihai Lake in
northern China are quantified by using a binary model, and phosphorus forms in the sediment cores from the two lakes are extracted
by sequential extraction techniques. The results indicate that the palaeoenvironment and paleoclimate of Daihai Lake and
its catchment basin in the recent 250 years can be well reconstructed based on the content of allochthonous OC. The climate
was relatively humid and warm in the period of 1865–2005, while relatively dry and cold in the period of 1765–1865. The sedimentary
information of allochthonous OC in the 22–42-cm portion of the sediment cores in Daihai Lake corresponds to the final cold
fluctuation of the Little Ice Age that occurred since the Middle Holocene. The difference of phosphorus forms in the sediment
cores between the two lakes indicates that phosphorus input to the lakes and the correlation between phosphorus forms and
distribution and the changes of environment are influenced by the eutrophication mechanisms and environmental conditions of
the two lakes. 相似文献
2.
Competitive adsorption,release and speciation of heavy metals in the Yellow River sediments,China 总被引:2,自引:0,他引:2
Qingyun Fan Jiang He Hongxi Xue Changwei LÜ Ying Liang Saruli Ying Sun Lili Shen 《Environmental Geology》2007,53(2):239-251
The competitive adsorption and the release of selected heavy metals and their speciation distribution before and after adsorption
in the Yellow River sediments are discussed. The adsorption of metals onto sediments increases with increasing pH value and
decreases with increasing ionic strength. The competitive coefficient K
c and the distribution coefficient K
d are obtained to analyze the competitive abilities of selected heavy metals, which are ranked as Pb > Cu >> Zn > Cd. The competition
among selected heavy metals becomes more impetuous with increasing ion concentration in water. Speciation analysis was done
by an improved analytical procedure involving five steps of sequential extraction. Cu, Pb and Zn were mainly transformed into
the carbonate-bound form (50.8–87.7%) in adsorption. Most of (60.7–77.3%) Cd was transformed into the exchangeable form, and
the percentage of carbonate-bound Cd was 19.7–30.4%. The release reaction was so quick that the release capacity of selected
heavy metals from sediments to aqueous solution reached half of the maximum value only in 30 s. As opposed to adsorption,
the release capacities of selected heavy metals were ranked as Cd > Zn >> Cu > Pb. In this study, Cd produces the most severe
environmental hazards, because its concentration in the release solution is 85.8 times more than the human health criteria
of US EPA. 相似文献
3.
The impacts of common ions on the adsorption of heavy metal 总被引:1,自引:0,他引:1
Jiang He Hong-Xi Xue Chang-Wei Lü Qing-Yun Fan Ying Liang Ying Sun Li-Li Shen Saruli Bai 《Environmental Geology》2009,58(7):1499-1508
Researches on the impact of common ions onto sediments are of great importance for the study of the heavy metal adsorption
mechanisms. Considering the surface sediments from the relatively clean reach in the Baotou section of the Yellow River as
the adsorbent, this work presents the impacts of common ions (Na+, Mg2+, K+, Ca2+, Cl−, SO4
2−, and NH4
+) on heavy metals (Cu2+, Zn2+, Cd2+, and Pb2+) adsorption. The experimental results reveal that the adsorptive capacities of the heavy metals are controlled by different
adsorption mechanisms in different ion concentration ranges. With the increase of the ionic strength, the adsorption of the
heavy metals increases for the compression of the electric double layer, whereas decreases for the decreasing of the ionic
activities of the heavy metals. The competitive adsorption and complexations between the heavy metals and common ions are
also important factors controlling the heavy metal adsorption. According to the experimental results and the real concentration
of common ions in the Baotou section of the Yellow River, the increase of the concentrations of Na+, Mg2+, K+, and Ca2+ would cause the increase of Zn2+ adsorption and reduce the Zn pollution. The NH4
+ from the industrial discharge of the tributaries has a strong impact on the heavy metal adsorption. 相似文献
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