Annually laminated sediments from Onondaga Lake, New York (USA) provide a basis for high-resolution studies of lake degradation and recovery

Rowell, H. Chandler; Bopp, Richard F.; Peng, Feng; Velinsky, David J.; Bloomfield, Jay A.

doi:10.1007/s10933-014-9811-5

Cited by 6 publications

(4 citation statements)

References 36 publications

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“…A peak value of 137 Cs found in the same layer in this sediment core has been regarded as maxima atmospheric fallout in 1964 in the sediment and was used as time marker for the whole sediment core (Liu et al, 2008, mentioned in section 2.1). The fallout signal in 1964 has been recorded in many other sediment cores collected in China and other locations all over the world by other anthropogenic radionuclides (Appleby, 2013;Baskaran et al, 2014;Liu et al, 2013;Rowell et al, 2015;Santos et al, 2007;Oktay et al, 2000;Wu et al, 2010). The global NWTs in the early 1960s by USA and USSR also released considerable amount of radioactive substance to the atmosphere including 129 I into the atmosphere, which is characterized by the distinct peak in the estimated annual 129 I releases from the NWTs (Fig.…”

Section: Contribution Of Nuclear Weapons Testingmentioning

confidence: 92%

129I record of nuclear activities in marine sediment core from Jiaozhou Bay in China

Fan

Hou

Zhou

et al. 2016

Journal of Environmental Radioactivity

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Iodine-129 has been used as a powerful tool for environmental tracing of human nuclear activities. In this work, a sediment core collected from Jiaozhou Bay, the east coast of China, in 2002 was analyzed for (129)I to investigate the influence of human nuclear activities in this region. Significantly enhanced (129)I level was observed in upper 70 cm of the sediment core, with peak values in the layer corresponding to 1957, 1964, 1974, 1986, and after 1990. The sources of (129)I and corresponding transport processes in this region are discussed, including nuclear weapons testing at the Pacific Proving Grounds, global fallout from a large numbers of nuclear weapon tests in 1963, the climax of Chinese nuclear weapons testing in the early 1970s, the Chernobyl accident in 1986, and long-distance dispersion of European reprocessing derived (129)I. The very well (129)I records of different human nuclear activities in the sediment core illustrate the potential application of (129)I in constraining ages and sedimentation rates of the recent sediment. The releases of (129)I from the European nuclear fuel reprocessing plants at La Hague (France) and Sellafield (UK) were found to dominate the inventory of (129)I in the Chinese sediments after 1990, not only the directly atmospheric releases of these reprocessing plants, but also re-emission of marine discharged (129)I of these reprocessing plants in the highly contaminated European seas.

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Section: Contribution Of Nuclear Weapons Testingmentioning

confidence: 92%

129I record of nuclear activities in marine sediment core from Jiaozhou Bay in China

Fan

Hou

Zhou

et al. 2016

Journal of Environmental Radioactivity

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“…Caution must also be exercised when interpreting changes seen in surface sediment samples (upper 0-1 cm) in terms of recovery as the reduced period of decomposition experienced by recently deposited diatoms can result in these being over-represented (Sayer, 2001). Varved sequences, offering an annual resolution, lend themselves particularly well to studies of degradation and recovery (e.g., Chandler Rowell et al, 2015). A combination of long-term datasets and palaeolimnological approaches provides a particularly powerful tool for assessing timescales of ecological change (Battarbee et al, 2005;Bennion et al, 2012;Dong et al, 2012).…”

Section: Degradation Vs Recovery Pathwaysmentioning

confidence: 99%

Assessing degradation and recovery pathways in lakes impacted by eutrophication using the sediment record

2015

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Efforts to restore enriched lakes have increased yet there remains uncertainty about whether restoration targets can be achieved and over what timescale. Paleoecological techniques, principally diatom analyses, were used to examine the degree of impact and recovery in 12 European lakes subject to eutrophication and subsequent reduction in nutrient loading. Dissimilarity scores showed that all sites experienced progressive deviation from the reference sample (core bottom) prior to nutrient reduction, and principal curves indicated gradual compositional change with enrichment. When additive models were applied to the latter, the changes were statistically significant in 9 of the 12 sites. Shifts in diatom composition following reduction in nutrient loading were more equivocal, with a reversal toward the reference flora seen only in four of the deep lakes and one of the shallow lakes. Of these, only two were significant (Lake Bled and Mjøsa). Alternative nutrient sources seem to explain the lack of apparent recovery in the other deep lakes. In three shallow lakes diatom assemblages were replaced by a community associated with lower productivity but not the one seen prior to enrichment. Internal loading and top down control may influence recovery in shallow lakes and climate change may have confounded recovery in several of the study sites. Hence, ecosystem recovery is not simply a reversal of the degradation pathway and may take several decades to complete or, for some lakes, may not take place at all. By assessing ecological change over a decadal to centennial timescale, the study highlights the important role that paleolimnology can play in establishing a benchmark against which managers can evaluate the degree to which their restoration efforts are successful.

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“…This type of recent onset of varve preservation, VJ26 33-5 cm/1966VJ26 33-5 cm/ -1975 Clay layer 2 D ± 0%; mean 9 years Error estimates (± %) are presented with corresponding number of varve years (years) and varve counting means (years). The depth and duration of each section and the occurrence of marker layers in each section are provided triggered by anthropogenic stressors, has been observed worldwide (Kienel et al 2013;Rowell et al 2015;Jenny et al 2013Jenny et al , 2016a. Moreover, it is likely that in lakes experiencing cultural eutrophication, a climate signal can be overridden by human impact.…”

Section: Onset and Changes In Varve Preservationmentioning

confidence: 99%

Human actions were responsible for both initiation and termination of varve preservation in Lake Vesijärvi, southern Finland

et al. 2021

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The influence of lake restoration efforts on lake bottom-water conditions and varve preservation is not well known. We studied varved sediments deposited during the last 80 years along a water-depth transect in the Enonsaari Deep, a deep-water area of the southernmost Enonselkä Basin, Lake Vesijärvi, southern Finland. For the last few decades, the Enonselkä Basin has been subject to ongoing restoration efforts. Varve, elemental, and diatom analyses were undertaken to explore how these actions and other human activities affected varve preservation in the Enonsaari Deep. In contrast to most varved Finnish lakes, whose water columns have a natural tendency to stratify, and possess varve records that span thousands of years, varve formation and preservation in Lake Vesijärvi was triggered by relatively recent anthropogenic stressors. The multi-core varve analysis revealed that sediment in the Enonsaari Deep was initially non-varved, but became fully varved in the late 1930s, a time of increasing anthropogenic influence on the lake. The largest spatial extent of varves occurred in the 1970s, which was followed by a period of less distinguishable varves, which coincided with diversion of sewage from the lake. Varve preservation weakened during subsequent decades and was terminated completely by lake aeration in the 2010s. Despite improvements in water quality, hypolimnetic oxygen depletion and varve preservation persisted beyond the reduction in sewage loading, initial aeration, and biomanipulation. These restoration efforts, however, along with other human actions such as harbor construction and dredging, did influence varve characteristics. Varves were also influenced by diatom responses to anthropogenic forcing, because diatoms form a substantial part of the varve structure. Of all the restoration efforts, a second episode of aeration seems to have had the single most dramatic impact on profundal conditions in the basin, resulting in replacement of a sediment accumulation zone by a transport or erosional zone in the Enonsaari Deep. We conclude that human activities in a lake and its catchment can alter lake hypolimnetic conditions, leading to shifts in lake bottom dynamics and changes in varve preservation.

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Annually laminated sediments from Onondaga Lake, New York (USA) provide a basis for high-resolution studies of lake degradation and recovery

Cited by 6 publications

References 36 publications

129I record of nuclear activities in marine sediment core from Jiaozhou Bay in China

129I record of nuclear activities in marine sediment core from Jiaozhou Bay in China

Assessing degradation and recovery pathways in lakes impacted by eutrophication using the sediment record

Human actions were responsible for both initiation and termination of varve preservation in Lake Vesijärvi, southern Finland

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