Late-twentieth-century warming in Lake Tanganyika unprecedented since AD 500

Tierney, Jessica E.; Mayes, Marc; Meyer, Natacha; Johnson, Christopher; Swarzenski, Peter W.; Cohen, Andrew S.; Russell, James M.

doi:10.1038/ngeo865

Cited by 199 publications

(184 citation statements)

References 20 publications

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“…A longer stratification period each year will exacerbate the extent and duration of hypolimnetic hypoxic or anoxic conditions [21,36,83]. In many lakes, changes in the amount of vertical mixing can also contribute to changes in nutrient dynamics and ultimately lake productivity [84,85] and changing fisheries [86]. Warming and increasingly anoxic deepwater can both result in increased cyanobacterial recruitment in species that both overwinter in and draw phosphorus from the sediments (e.g., [87]).…”

Section: Ecological Implicationsmentioning

confidence: 99%

Transparency, Geomorphology and Mixing Regime Explain Variability in Trends in Lake Temperature and Stratification across Northeastern North America (1975–2014)

Richardson

Melles

Pilla

et al. 2017

Water

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Lake surface water temperatures are warming worldwide, raising concerns about the future integrity of valuable lake ecosystem services. In contrast to surface water temperatures, we know far less about what is happening to water temperature beneath the surface, where most organisms live. Moreover, we know little about which characteristics make lakes more or less sensitive to climate change and other environmental stressors. We examined changes in lake thermal structure for 231 lakes across northeastern North America (NENA), a region with an exceptionally high density of lakes. We determined how lake thermal structure has changed in recent decades and assessed which lake characteristics are related to changes in lake thermal structure. In general, NENA lakes had increasing near-surface temperatures and thermal stratification strength. On average, changes in deepwater temperatures for the 231 lakes were not significantly different than zero, but individually, half of the lakes experienced warming and half cooling deepwater temperature through time. More transparent lakes (Secchi transparency >5 m) tended to have higher near-surface warming and greater increases in strength of thermal stratification than less transparent lakes. Whole-lake warming was greatest in polymictic lakes, where frequent summer mixing distributed heat throughout the water column. Lakes often function as important sentinels of climate change, but lake characteristics within and across regions modify the magnitude of the signal with important implications for lake biology, ecology and chemistry.

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Section: Ecological Implicationsmentioning

confidence: 99%

Transparency, Geomorphology and Mixing Regime Explain Variability in Trends in Lake Temperature and Stratification across Northeastern North America (1975–2014)

Richardson

Melles

Pilla

et al. 2017

Water

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“…These programs and similar efforts have provided a vehicle for a wide range of sustained scientific data collection on diverse topics, including climate change impacts, water quality, and land-use on the lake (Cohen et al, 1993;Tierney et al, 2010). They have resulted in new data on historic profiles of Cd, Fe, Mo, Re, and U in the lake's sediment (Brucker et al, 2011) and a report on Hg fluxes to the lake (Conaway et al, 2012).…”

Section: Environmental Changes In Lake Tanganyikamentioning

confidence: 99%

“…For example, average annual air temperatures around the lake have increased by 0.5-0.7°C since the late 1970s (O'Reilly et al, 2003), and the temperature of the lower metalimnion ($110 m-depth water column) of the lake has increased by 0.9°C between 1913 and 2000 (Tierney et al, 2010). Moreover, it has been predicted that surface temperatures in Central Africa could rise by 1.25-1.5°C by the end of this century (IPCC, 2013).…”

Section: Environmental Changes In Lake Tanganyikamentioning

confidence: 99%

Using lead isotopes and trace element records from two contrasting Lake Tanganyika sediment cores to assess watershed – Lake exchange

Odigie

Cohen

Swarzenski

et al. 2014

Applied Geochemistry

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Editorial handling by M. Kersten a b s t r a c tLead isotopic and trace element records of two contrasting sediment cores were examined to reconstruct historic, industrial contaminant inputs to Lake Tanganyika, Africa. Observed fluxes of Co, Cu, Mn, Ni, Pb, and Zn in age-dated sediments collected from the lake varied both spatially and temporally over the past two to four centuries. The fluxes of trace elements were lower (up to 10-fold) at a mid-lake site (MC1) than at a nearshore site (LT-98-58), which is directly downstream from the Kahama and Nyasanga River watersheds and adjacent to the relatively pristine Gombe Stream National Park. Trace element fluxes at that nearshore site did not measurably change over the last two centuries (1815-1998), while the distal, mid-lake site exhibited substantial changes in the fluxes of trace elements -likely caused by changes in land use -over that period. For example, the flux of Pb increased by $300% from 1871 to 1991. That apparent accelerated weathering and detrital mobilization of lithogenic trace elements was further evidenced by (i) positive correlations (r = 0.77-0.99, p < 0.05) between the fluxes of Co, Cu, Mn, Ni, Pb, and Zn and those of iron (Fe) at both sites, (ii) positive correlations (r = 0.82-0.98, p < 0.01, n = 9) between the fluxes of elements (Al, Co, Cu, Fe, Mn, Ni, Pb, and Zn) and the mass accumulation rates at the offshore site, (iii) the low enrichment factors (EF < 5) of those trace elements, and (iv) the temporal consistencies of the isotopic composition of Pb in the sediment. These measurements indicate that accelerated weathering, rather than industrialization, accounts for most of the increases in trace element fluxes to Lake Tanganyika in spite of the development of mining and smelting operations within the lake's watershed over the past century. The data also indicate that the mid-lake site is a much more sensitive and useful recorder of environmental changes than the nearshore site. Furthermore, the lead isotopic compositions of sediment at the sites differed spatially, indicating that the Pb (and other trace elements by association) originated from different natural sources at the two locations.

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“…Lacustrine sediments are a useful archive of environmental changes, including cycling of environmentally persistent contaminants, in a lake's catchment area (Tierney et al 2010;Brucker et al 2011). In addition, Pb isotopic compositions (e.g., 206 Pb/ 207 Pb: 208 Pb/ 206 Pb) may be used as tracers of natural and industrial sources of mobilized Pb in the environment (Ellam 2010;Flegal et al 2010).…”

Section: Study Objectivesmentioning

confidence: 99%

Remobilization of trace elements by forest fire in Patagonia, Chile

et al. 2015

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Temporal changes in the amounts of trace elements (As, Co, Cu, Mn, Ni, Pb, and Zn) and their correlations with temporal changes in charcoal abundance in age-dated sediments collected from Lake Thompson in Patagonia, Chile, attest to the substantial pyrogenic remobilization of contaminants that occurred in Patagonia during the mid-1900s. This remobilization was concurrent with the extensive slash and burn period in the region during that period. The changes in concentrations of Co, Cu, and Ni in relation to charcoal abundance in the lacustrine sediments over time were small compared to those of As, Mn, Pb, and Zn. However, the relatively low enrichment factors of all those trace elements, normalized to Fe, indicate that they were predominantly derived from local, natural sources impacted by fires rather than industrial sources. The primarily local source of Pb in the sediments was corroborated by the temporal consistency of its isotopic ratios ( 206 Pb/ 207 Pb: 208 Pb/ 206 Pb), which were similar to previously reported values for natural lead in Central and Southern Chile. However, the pyrogenic remobilization of both natural and industrial trace elements by forest fires in Chile and elsewhere is expected to rise as a consequence of climate change, which is projected to increase both the frequency and intensity of forest fires on a global scale.

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Late-twentieth-century warming in Lake Tanganyika unprecedented since AD 500

Cited by 199 publications

References 20 publications

Transparency, Geomorphology and Mixing Regime Explain Variability in Trends in Lake Temperature and Stratification across Northeastern North America (1975–2014)

Transparency, Geomorphology and Mixing Regime Explain Variability in Trends in Lake Temperature and Stratification across Northeastern North America (1975–2014)

Using lead isotopes and trace element records from two contrasting Lake Tanganyika sediment cores to assess watershed – Lake exchange

Remobilization of trace elements by forest fire in Patagonia, Chile

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