Chemical composition of the small rivers of the north-western part of Lake Tanganyika

Kimbadi, S.; Vandelannoote, A.; Deelstra, H.; Mbemba, Mackline; Ollevier, Frans

doi:10.1007/978-94-017-1622-2_7

Cited by 9 publications

(13 citation statements)

References 5 publications

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“…10). In addition, even mountain streams with headwaters several kilometers above the lake surface have mean temperatures over 24uC (Kimbadi et al 1999), too high to contribute to deep water formation, while the largest inflow, the Ruzizi, has a mean temperature of 25uC , almost 2uC higher than the bottom water. Craig et al (1974) concluded that the deep water was a ''relic hypolimnion,'' formed in a colder and drier time when evaporation was greater than at present.…”

Section: Discussionmentioning

confidence: 99%

The physics of the warming of Lake Tanganyika by climate change

Verburga

Hecky

2009

Limnology & Oceanography

124

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Climate warming over the 20th century has increased the density stratification and stability of Lake Tanganyika, a deep rift valley lake. Here we examine the physical processes involved in and affected by the warming of the lake, and we discuss effects on lake productivity. The rate of net heat absorption by Lake Tanganyika has been 0.4 W m 22 since 1913, twice the rate in the global ocean, indicating stronger climate forcing in the East African region. Lakes warm through increased incoming long-wave radiation. While lakes in general will increase heat outputs in a warming climate, heat outputs will increase more slowly in deeper lakes than in shallower lakes. Temperatures have increased by 0.2uC at 1000 m in depth, in part because of reduced cool marginal inflows, while water surface temperatures have increased by about 1.3uC. This differential heating over depth has increased the density gradient through the water column, reducing the potential for vertical mixing and thereby limiting nutrient fluxes to the phototrophic zone. An increase in transparency, indicating a reduction in productivity as a result of the reduced vertical mixing, occurred both in Lake Tanganyika and in Lake Malawi, a similar deep tropical lake in which warming has also been documented.

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Section: Discussionmentioning

confidence: 99%

The physics of the warming of Lake Tanganyika by climate change

Verburga

Hecky

2009

Limnology & Oceanography

124

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“…The only instance where dry season concentrations for inflows exceed those of rainy seasons was for TDP and SRP for minor rivers, and this comprises a relatively small component of total lake P inputs. Existing data Edmond et al 1993;Kimbadi et al 1999;Langenberg et al 2003b) on major phosphorus sources and sinks can be contrasted with our hypothesized wet and dry climate conditions. The excess of modern precipitation and runoff inputs over outflow implies a current TP increase of approximately~4.42 kt yr )1 .…”

Section: Implications For Productivity and Nutrient Cyclingmentioning

confidence: 99%

“…Rainfall and river inputs of total, dissolved, and soluble reactive phosphorus (TP, TDP, SRP respectively) have been characterized for Lake Tanganyika (Kimbadi et al 1999;Langenberg et al 2003b, FAO/FINNIDA unpubl. data).…”

Section: Implications For Productivity and Nutrient Cyclingmentioning

confidence: 99%

Late Holocene linkages between decade–century scale climate variability and productivity at Lake Tanganyika, Africa

et al. 2006

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Microlaminated sediment cores from the Kalya slope region of Lake Tanganyika provide a near-annually resolved paleoclimate record between~2,840 and 1,420 cal. yr B.P. demonstrating strong linkages between climate variability and lacustrine productivity. Laminae couplets comprise dark, terrigenous-dominated half couplets, interpreted as low density underflows deposited from riverine sources during the rainy season, alternating with light, planktonic diatomaceous ooze, with little terrigenous component, interpreted as windy/dry season deposits. Laminated portions of the studied cores consist of conspicuous dark and light colored bundles of laminae couplets. Light and dark bundles alternate at decadal time scales. Within dark bundles, both light and dark half couplets are significantly thinner than within light bundles, implying slower sediment accumulation rates during both seasons over those intervals.Time series analyses of laminae thickness patterns demonstrate significant periodicities at interannual-centennial time scales. Longer time scale periodicities (multidecadal to centennial scale) of light and dark half couplet thicknesses are coherent and in some cases are similar to solar cycle periods on these time scales. Although laminae thickness cycles do not strongly covary with the actual D 14 C record for this same time period, two large D 14 C anomalies are associated with substantial decreases in both light and dark laminae thickness. In contrast to the multidecadal- centennial time scale, significant annual to decadal periodicities, which are broadly consistent with ENSO/PDO forcing and their impact on East African climate, are not coherent between light and dark half couplets. The coherency of light-dark couplets at decadal-centennial time scales, but not at shorter time scales, is consistent with a model of a long-term relationship between precipitation (recorded in wet season dark laminae thickness) and productivity (light laminae thickness), which is not manifest at shorter time scales. We hypothesize that this coupling results from long-term recharging of internal nutrient loading during wet periods (higher erosion of soil P) and reduced loading during drought intervals. The relationship is not expressed on short time scales during which the dominant control on productivity is wind-driven, dry season upwelling, which is uncorrelated with wet-season precipitation. Our record greatly extends the temporal record of this quasi-periodic behavior throughout the late Holocene and provides the first evidence linking decade-to century-scale episodes of enhanced productivity to enhanced precipitation levels and nutrient recharge in a productive tropical lake.

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“…The water availability is greatly influenced by the local geology and climate (Zhu et al 2012a). Understanding of the source and recharge of natural waters is of great significance not only to the policy makers for regional planning but also to the scientists interested in hydrological cycles in arid environments over the world (Meyer et al 1988;George et al 1997;Arnell 1999;Kimbadi et al 1999;Cramer and Hobbs 2002;Hagg et al 2007;Jolly et al 2008;Zhu et al 2012b;Dragon and Gorski 2015).…”

Section: Introductionmentioning

confidence: 99%

Statistical study to identify the key factors governing ground water recharge in the watersheds of the arid Central Asia

Zhu

Wang

2015

Environ Monit Assess

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Understanding the source and recharge of ground waters is of great significance to our knowledge in hydrological cycles in arid environments over the world. Northern Xinjiang in northwestern China is a significant repository of information relating to the hydrological evolution and climatic changes in central Asia. In this study, two multivariate statistical techniques, hierarchical cluster analysis (HCA) and principal component analysis (PCA), were used to assess the ground water recharge and its governing factors, with the principal idea of exploring the above techniques to utilize all available hydrogeochemical variables in the quality assessment, which are not considered in the conventional techniques like Stiff and Piper diagrams. Q-mode HCA and R-mode PCA were combined to partition the water samples into seven major water clusters (C1-C7) and three principal components (PC1-PC3, PC1 salinity, PC2 hydroclimate, PC3 contaminant). The water samples C1 + C4 were classified as recharge area waters (Ca-HCO 3 water), C2 + C3 as transitional zone waters (Ca-Mg-HCO 3 -SO 4 water), and C5 + C6 + C7 as discharge area waters (Na-SO 4 water). Based on the Q-mode PCA scores, three groups of geochemical processes influencing recharge regimes were identified: geogenic (i.e., caused by natural geochemical processes), geomorphoclimatic (caused by topography and climate), and anthropogenic (caused by ground water contamination). It is proposed that differences in recharge mechanism and ground water evolution, and possible bedrock composition difference, are responsible for the chemical genesis of these waters. These will continue to influence the geochemistry of the northern Xinjiang drainage system for a long time due to its steady tectonics and arid climate. This study proved that the chemistry differentiation of ground water can effectively support the identification of ground water recharge and evolution patterns.

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Chemical composition of the small rivers of the north-western part of Lake Tanganyika

Cited by 9 publications

References 5 publications

The physics of the warming of Lake Tanganyika by climate change

The physics of the warming of Lake Tanganyika by climate change

Late Holocene linkages between decade–century scale climate variability and productivity at Lake Tanganyika, Africa

Statistical study to identify the key factors governing ground water recharge in the watersheds of the arid Central Asia

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