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Major and trace element geochemistry of Lake Bogoria and Lake Nakuru, Kenya, during extreme draught.

Jirsa F, Gruber M, Stojanovic A, Omondi SO, Mader D, Körner W, Schagerl M - Chem. Erde (2013)

Bottom Line: Due to an extreme draught from March to October 2009, the water level of Lake Nakuru dropped significantly.In Lake Bogoria the evapoconcentration effects were less pronounced (total salinity changed from about 40‰ to 48‰).The results show a high abundance of the REE and a very distinct Eu depletion of Eu/Eu* = 0.33-0.45.

View Article: PubMed Central - PubMed

Affiliation: University of Vienna, Institute of Inorganic Chemistry, Währingerstrasse 42, A-1090 Vienna, Austria.

ABSTRACT

The physico-chemical properties of water samples from the two athalassic endorheic lakes Bogoria and Nakuru in Kenya were analysed. Surface water samples were taken between July 2008 and October 2009 in weekly intervals from each lake. The following parameters were determined: pH, salinity, electric conductivity, dissolved organic carbon (DOC), the major cations (FAAS and ICP-OES) and the major anions (IC), as well as certain trace elements (ICP-OES). Samples of superficial sediments were taken in October 2009 and examined using Instrumental Neutron Activation Analysis (INAA) for their major and trace element content including rare earth elements (REE). Both lakes are highly alkaline with a dominance of Na > K > Si > Ca in cations and HCO3 > CO3 > Cl > F > SO4 in anions. Both lakes also exhibited high concentrations of Mo, As and fluoride. Due to an extreme draught from March to October 2009, the water level of Lake Nakuru dropped significantly. This created drastic evapoconcentration, with the total salinity rising from about 20‰ up to 63‰. Most parameters (DOC, Na, K, Ca, F, Mo and As) increased with falling water levels. A clear change in the quality of DOC was observed, followed by an almost complete depletion of dissolved Fe from the water phase. In Lake Bogoria the evapoconcentration effects were less pronounced (total salinity changed from about 40‰ to 48‰). The distributions of REE in the superficial sediments of Lake Nakuru and Lake Bogoria are presented here for the first time. The results show a high abundance of the REE and a very distinct Eu depletion of Eu/Eu* = 0.33-0.45.

No MeSH data available.


Related in: MedlinePlus

Selected parameters from Lakes Nakuru and Bogoria between July 2008 and October 2009.
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fig0020: Selected parameters from Lakes Nakuru and Bogoria between July 2008 and October 2009.

Mentions: The results for the physico-chemical parameters, dissolved major and trace elements as well as dissolved organic carbon (DOC) and dissolved bound nitrogen (DN) are presented in Table 1. The statistical evaluation of the charge balance showed a significant correlation (p < 0.05) between the summed up charges of cations and anions. This demonstrates that all major ions in the two lakes were analysed. The concentrations and values varied significantly during the survey due to drought at both lakes. We therefore present minimum, median and maximum values from all three sampling points in each lake. In order to show the behaviour of certain interesting components, mean values for the measurements of the three sites were calculated and presented over time in Fig. 4. The statistical evaluation of salinity and electric conductivity from the three different sample sites at each lake showed no significant difference (p > 0.05). This contradicts results reported by Vincens et al. (1986) for Lake Bogoria, who described a gradient in rising salinity from north to south. Our sample points were situated far offshore, near the centre of the lake. Accordingly, the hot springs that drain into the lake, most of which contain less salt than the lake water (Owen et al., 2008; Cioni et al., 1992), appear to have no influence on the salinity there. In addition the major river flowing into the lake from the north discharged very little or no water during the observation period. This also might have contributed to the equal distribution of the salt content from south to north.


Major and trace element geochemistry of Lake Bogoria and Lake Nakuru, Kenya, during extreme draught.

Jirsa F, Gruber M, Stojanovic A, Omondi SO, Mader D, Körner W, Schagerl M - Chem. Erde (2013)

Selected parameters from Lakes Nakuru and Bogoria between July 2008 and October 2009.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4375630&req=5

fig0020: Selected parameters from Lakes Nakuru and Bogoria between July 2008 and October 2009.
Mentions: The results for the physico-chemical parameters, dissolved major and trace elements as well as dissolved organic carbon (DOC) and dissolved bound nitrogen (DN) are presented in Table 1. The statistical evaluation of the charge balance showed a significant correlation (p < 0.05) between the summed up charges of cations and anions. This demonstrates that all major ions in the two lakes were analysed. The concentrations and values varied significantly during the survey due to drought at both lakes. We therefore present minimum, median and maximum values from all three sampling points in each lake. In order to show the behaviour of certain interesting components, mean values for the measurements of the three sites were calculated and presented over time in Fig. 4. The statistical evaluation of salinity and electric conductivity from the three different sample sites at each lake showed no significant difference (p > 0.05). This contradicts results reported by Vincens et al. (1986) for Lake Bogoria, who described a gradient in rising salinity from north to south. Our sample points were situated far offshore, near the centre of the lake. Accordingly, the hot springs that drain into the lake, most of which contain less salt than the lake water (Owen et al., 2008; Cioni et al., 1992), appear to have no influence on the salinity there. In addition the major river flowing into the lake from the north discharged very little or no water during the observation period. This also might have contributed to the equal distribution of the salt content from south to north.

Bottom Line: Due to an extreme draught from March to October 2009, the water level of Lake Nakuru dropped significantly.In Lake Bogoria the evapoconcentration effects were less pronounced (total salinity changed from about 40‰ to 48‰).The results show a high abundance of the REE and a very distinct Eu depletion of Eu/Eu* = 0.33-0.45.

View Article: PubMed Central - PubMed

Affiliation: University of Vienna, Institute of Inorganic Chemistry, Währingerstrasse 42, A-1090 Vienna, Austria.

ABSTRACT

The physico-chemical properties of water samples from the two athalassic endorheic lakes Bogoria and Nakuru in Kenya were analysed. Surface water samples were taken between July 2008 and October 2009 in weekly intervals from each lake. The following parameters were determined: pH, salinity, electric conductivity, dissolved organic carbon (DOC), the major cations (FAAS and ICP-OES) and the major anions (IC), as well as certain trace elements (ICP-OES). Samples of superficial sediments were taken in October 2009 and examined using Instrumental Neutron Activation Analysis (INAA) for their major and trace element content including rare earth elements (REE). Both lakes are highly alkaline with a dominance of Na > K > Si > Ca in cations and HCO3 > CO3 > Cl > F > SO4 in anions. Both lakes also exhibited high concentrations of Mo, As and fluoride. Due to an extreme draught from March to October 2009, the water level of Lake Nakuru dropped significantly. This created drastic evapoconcentration, with the total salinity rising from about 20‰ up to 63‰. Most parameters (DOC, Na, K, Ca, F, Mo and As) increased with falling water levels. A clear change in the quality of DOC was observed, followed by an almost complete depletion of dissolved Fe from the water phase. In Lake Bogoria the evapoconcentration effects were less pronounced (total salinity changed from about 40‰ to 48‰). The distributions of REE in the superficial sediments of Lake Nakuru and Lake Bogoria are presented here for the first time. The results show a high abundance of the REE and a very distinct Eu depletion of Eu/Eu* = 0.33-0.45.

No MeSH data available.


Related in: MedlinePlus