Rapa Nui (Easter Island) Rano Raraku crater lake basin: Geochemical characterization and implications for the Ahu-Moai Period

E. Argiriadis; M. Bortolini; N. M. Kehrwald; M. Roman; C. Turetta; S. Hanif; E. O. Erhenhi; J. M. Ramirez Aliaga; D. B. McWethy; A. E. Myrbo; A. Pauchard; C. Barbante; D. Battistel

doi:10.1371/journal.pone.0254793

Rapa Nui (Easter Island) Rano Raraku crater lake basin: Geochemical characterization and implications for the Ahu-Moai Period

PLoS ONE ◽

10.1371/journal.pone.0254793 ◽

2021 ◽

Vol 16 (10) ◽

pp. e0254793

Author(s):

E. Argiriadis ◽

M. Bortolini ◽

N. M. Kehrwald ◽

M. Roman ◽

C. Turetta ◽

...

Keyword(s):

Lake Water ◽

Lake Level ◽

Crater Lake ◽

Environmental Changes ◽

Easter Island ◽

Lake Basin ◽

High Concentration ◽

Rapa Nui ◽

Reducing Conditions ◽

Freshwater Source

Rano Raraku, the crater lake constrained by basaltic tuff that served as the primary quarry used to construct the moai statues on Rapa Nui (Easter Island), has experienced fluctuations in lake level over the past centuries. As one of the only freshwater sources on the island, understanding the present and past geochemical characteristics of the lake water is critical to understand if the lake could have been a viable freshwater source for Rapa Nui. At the time of sampling in September 2017, the maximum lake depth was ~1 m. The lake level has substantially declined in the subsequent years, with the lake drying almost completely in January 2018. The lake is currently characterized by highly anoxic conditions, with a predominance of ammonium ions on nitrates, a high concentration of organic carbon in the water-sediment interface and reducing conditions of the lake, as evidenced by Mn/Fe and Cr/V ratios. Our estimates of past salinity inferred from the chloride mass balance indicates that it was unlikely that Rano Raraku provided a viable freshwater source for early Rapa Nui people. The installation of an outlet pipe around 1950 that was active until the late 1970s, as well as grazing of horses on the lake margins appear to have significantly impacted the geochemical conditions of Rano Raraku sediments and lake water in recent decades. Such impacts are distinct from natural environmental changes and highlight the need to consider the sensitivity of the lake geochemistry to human activities.

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Historical environmental changes in the Poyang Lake basin (Yangtze River, China) and impacts on agricultural activities

The Holocene ◽

10.1177/09596836211047777 ◽

2021 ◽

pp. 095968362110477

Author(s):

Maofeng He ◽

Fengxian Bu ◽

Claudio O Delang ◽

Jialin Xie ◽

Quan Ye ◽

...

Keyword(s):

Climate Change ◽

Lake Water ◽

Human Activities ◽

Environmental Changes ◽

Poyang Lake ◽

Lake Basin ◽

Lake Area ◽

Poyang Lake Basin ◽

Past 2000 Years ◽

Floods And Droughts

Climate change and human activities have been an important part of studies regarding historical environmental changes in China over the past 2000 years. In this study, we focused on environmental changes, that is, natural disasters and human activities, in the Poyang Lake Basin over the past 2000 years, to analyze interactions between land use cover changes and human activities from the perspective of regional sustainable development. We collected historical records of climate and hydrology, floods and droughts, and rivers and lakes in the Poyang Lake area, and established time sequences for the floods and droughts, lake water level and lake area, amount of farming land, and population, in order to discuss interactions between changes in the environment and the climate, with emphasis on the impacts of extreme events on lake and river basin environment changes. The following results were obtained. First, climate changes in historical periods had wide-ranging and far-reaching impacts on agricultural production, especially disasters caused by climate change. Among the changes in the Poyang Lake basin environment, including river network systems, lake water levels, etc., changes in lake water volume are direct evidence of climate change, adaptation to climate change, and obvious phased characteristics. Second, in the process of changes to the lake and river network in the Poyang Lake Basin, social and economic development is accompanied by evolution of the lake. Increases and decreases in population, the scale of agricultural production, and lake environment changes have direct and significant interactions. Third, the Poyang Lake basin’s environmental changes during the historical period are mainly reflected in the pressure feedback mode of “population–agriculture” in the lake environment.

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Fluctuations of Lake Lisan (the Dead Sea) during the last glacial: Implications for paleoclimatic changes of the Levant.

10.5194/egusphere-egu2020-12906 ◽

2020 ◽

Author(s):

Shahrazad Abu Ghazleh ◽

Stephan Kempe

Keyword(s):

Fresh Water ◽

Lake Water ◽

Lake Level ◽

Eastern Mediterranean ◽

Xrd Analysis ◽

Dead Sea ◽

Climatic Conditions ◽

Lake Basin ◽

Fresh Water Input ◽

The Dead

&#160;Calcareous stromatolite crusts overgrowing beach gravels and stabilising piles of rocks were observed on shoreline terraces of Lake Lisan along the eastern coast of the Dead Sea. The stromatolite crusts are thick, massive and hard, with a dark-grey or white-grey finely-laminated structure, indicating that they are mostly calcareous organic build-up of cyanobacterial origin. Samples from these stromatolites have been analyzed using Stable Isotopes (&#948;13C &&#160;&#948;18O), AAS and XRD analysis. The samples range in altitude between -350 m and -19 m, representing the time interval of Lake Lisan (~ 80-19 ka BP) according to our U/Th dating. Since stromatolites grow in shallow water, they are very sensitive to minor shifts in rainfall and evaporation and therefore an excellent tool to track small changes in hydrology, in climate and in paleoenvironmental conditions of the lake basin.&#160;Oxygen and carbon isotopic compositions of these stromatolites show a linear covariant trend with a strong positive correlation (r = 0.8) and large ranges of 7.85 and 6.78&#8240;, respectively. This trend is most typical of primary carbonates formed in closed lakes. Isotopes analyses show low negative values of stromatolites from the lake highest stands at -76 m to -19 m, reflecting fresh water conditions of the lake basin at the last interglacial-glacial boundary (80-76 ka BP). The lowest values were derived from stromatolites at -103 to -119 m associated with the transgression of the lake to these high stands between 55 and 33 ka BP. The heaviest values were derived from stromatolites at -137 to -160 m indicating a change to dry climatic conditions in the Eastern Mediterranean that caused a subsequent drop of the lake level during MIS 2 (31-19 ka BP).&#160;The Mg/Ca ratio and the XRD analysis of the stromatolites correlate also with transgression-regression phases of the lake. Dominance of calcite in stromatolites at -76 to 0 m and inferred low Mg/Ca ratios of the lake water (i.e. ~2) imply a high fresh water input of the lake during the &#160;&#160;highest stands period. A high Mg/Ca ratio of the lake water of >7 inferred from low-level stromatolite at -350 m and the existence of aragonite as the sole mineral reflect low fresh water input and high evaporation rates that caused a lake level regression during H6, ~ 60 ka BP.&#160;Inferred low Mg/Ca ratios of stromatolites at -247 to -101 m and the existence of calcite as a main mineral phase indicate wet climatic conditions of the eastern Mediterranean and lake level transgression to higher than -137 during MIS 3. The appearance of more aragonite in stromatolites at -137 to -154 m and the inferred high Mg/Ca ratio of the lake water points to a return to dry climatic conditions that caused a regression of Lake Lisan between 32 to 22 ka BP (MIS 2). However, the change in the mineral composition to pure calcite at -160 m in addition to the inferred low Mg/Ca ratio correlates well with the transgression of the lake to this level by the end of the LGM.&#160;&#160;

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Late Glacial to Holocene dune development at southern Krakower See

DEUQUA Special Publications ◽

10.5194/deuquasp-2-83-2019 ◽

2019 ◽

Vol 2 ◽

pp. 83-88 ◽

Cited By ~ 2

Author(s):

Sebastian Lorenz ◽

Henrik Rother ◽

Michael Kenzler ◽

Sara Kaphengst

Keyword(s):

Land Use ◽

Lake Level ◽

Environmental Changes ◽

Past Research ◽

Late Glacial ◽

Quaternary Geology ◽

Lake Basin ◽

Surrounding Area ◽

Quaternary Deposits ◽

Anthropogenic Land Use

Abstract. The site at the southern shore of Krakower See shows the Quaternary geology of the surrounding area. The local Quaternary sequence comprises a thickness of 50–100 m of Quaternary deposits while the surface morphology is dominated by the ice marginal position of the Pomeranian moraine, which passes through the area. The bathymetry of the lake basin of Krakower See indicates a predominant genesis by glaciofluvial erosion in combination with glacial exaration. Past research in this area has focussed on the reconstruction of Pleniglacial to Holocene environmental changes, including lake-level fluctuations, aeolian dynamics, and pedological processes and their modification by anthropogenic land use.

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Drought, vegetation change, and human history on Rapa Nui (Isla de Pascua, Easter Island)

Quaternary Research ◽

10.1016/j.yqres.2007.10.009 ◽

2008 ◽

Vol 69 (1) ◽

pp. 16-28 ◽

Cited By ~ 80

Author(s):

Daniel Mann ◽

James Edwards ◽

Julie Chase ◽

Warren Beck ◽

Richard Reanier ◽

...

Keyword(s):

Vegetation Change ◽

Environmental Changes ◽

Human Impacts ◽

Sediment Cores ◽

Lake Basin ◽

Rapa Nui ◽

Agricultural Colonization ◽

Sediment Types ◽

Forest Clearance ◽

And Shifts

Stratigraphic records from lake sediment cores and slope deposits on Rapa Nui document prehistoric human impacts and natural environmental changes. A hiatus in sedimentation in Rano Raraku suggests that this lake basin dried out sometime after 4090–4410 cal yr BP and refilled only decades to centuries before AD 1180–1290. Widespread ecosystem changes caused by forest clearance by Polynesian farmers began shortly after the end of this drought. Terrestrial sections show a chronology of burning and soil erosion similar to the lake cores. Although changing sediment types and shifts in the pollen rain suggest that droughts occurred earlier in the Holocene, as yet there is no evidence for droughts occurring after AD 1180–1290. The timing of the agricultural colonization of Rapa Nui now seems well established at ca. AD 1200 and it was accompanied by rapid deforestation that was probably exacerbated by the island's small size, its droughty climate, and the rarity of primeval fires. Detailed records of a large interval of Rapa Nui's ecological history remain elusive due to the drought hiatus in the Rano Raraku sediment record. We find no evidence for a "rat outbreak impact" on Rapa Nui's vegetation preceding anthropogenic forest clearance.

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Water Quality Characterization of Varsity Lake, University of Malaya, Kuala Lumpur, Malaysia

E-Journal of Chemistry ◽

10.1155/2010/396215 ◽

2010 ◽

Vol 7 (s1) ◽

pp. S245-S254 ◽

Cited By ~ 8

Author(s):

M. Aqeel Ashraf ◽

M. Jamil Maah ◽

Ismail Yusoff

Keyword(s):

Water Quality ◽

Lake Water ◽

Best Management Practices ◽

Management Practices ◽

Lake Basin ◽

High Concentration ◽

Oil And Grease ◽

Lake Water Quality ◽

Body Contact ◽

Lakes And Reservoirs

Lakes and reservoirs are important sources of water supply, generate electricity and to irrigate fields. Since, lakes act as catchment basins for close to 40% of the landscape so serve as recreational, sporting and fishing activities. Varsity Lake University of Malaya (UM) is beautiful landscape at the front of the UM main entrance. It is used mainly for recreational and sporting (canoeing) activities. Study has been carried out in order to analyze water quality, nutrients and metals load starting from water inlets into the lake basin. It was found that there is high concentration of oil and grease particles in water due to water flow from cafeteria of college 2, engineering and built environment faculties which cause BOD and TSS value to be higher then normal in the lake. It was one of the main factors that caused the death of fish in the lake in recent months. Mercury and nitrate concentration is also high in the lake. A body contact is involved due to sporting and recreational activities so parameters are compared with Malaysian Interim water quality standards and it was concluded that lake water quality is not fulfilling the recreational spot criteria and is hazardous to human and fish life in the lake. Recommendations are proposed for immediate action. Best management practices is also discussed for prevention of oil and grease particles from entry into lake water to protect this valuable water resource from being polluted.

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First Records and Descriptions of Early Life Stages of Cephalopods from Rapa Nui (Easter Island) and the Nearby Apolo Seamount

Pacific Science ◽

10.2984/73.1.8 ◽

2019 ◽

Vol 73 (1) ◽

pp. 163 ◽

Cited By ~ 1

Author(s):

Sergio A. Carrasco ◽

Erika Meerhoff ◽

Beatriz Yannicelly ◽

Christian M. Ibáñez

Keyword(s):

Early Life ◽

Easter Island ◽

Life Stages ◽

Early Life Stages ◽

Rapa Nui

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FIRST CHARACTERIZATION OF DRILLING PREDATION ON EASTER ISLAND - RAPA NUI

10.1130/abs/2017am-303900 ◽

2017 ◽

Author(s):

Julieta Martinelli ◽

◽

Sandra Gordillo ◽

Maria Carla De Aranzamendi ◽

...

Keyword(s):

Easter Island ◽

Rapa Nui ◽

Drilling Predation

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Daily accumulation rates of marine litter on the shores of Rapa Nui (Easter Island) in the South Pacific Ocean

Marine Pollution Bulletin ◽

10.1016/j.marpolbul.2021.112535 ◽

2021 ◽

Vol 169 ◽

pp. 112535

Author(s):

Martin Thiel ◽

Bárbara Barrera Lorca ◽

Luis Bravo ◽

Iván A. Hinojosa ◽

Hugo Zeballos Meneses

Keyword(s):

Pacific Ocean ◽

South Pacific ◽

Easter Island ◽

Accumulation Rates ◽

The South ◽

Rapa Nui ◽

Marine Litter ◽

South Pacific Ocean

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Thermal Imaging Shows Submarine Groundwater Discharge Plumes Associated with Ancient Settlements on Rapa Nui (Easter Island, Chile)

Remote Sensing ◽

10.3390/rs13132531 ◽

2021 ◽

Vol 13 (13) ◽

pp. 2531

Author(s):

Robert J. DiNapoli ◽

Carl P. Lipo ◽

Timothy S. de Smet ◽

Terry L. Hunt

Keyword(s):

Fresh Water ◽

Submarine Groundwater Discharge ◽

Groundwater Discharge ◽

Water Sources ◽

Easter Island ◽

Human Populations ◽

Rapa Nui ◽

Hydrologic Processes ◽

Submarine Groundwater ◽

Aerial Systems

Submarine groundwater discharge (SGD) is an important component of many coastal environments and hydrologic processes, providing sources of nutrients to marine ecosystems, and potentially, an important source of fresh water for human populations. Here, we use a combination of unpiloted aerial systems (UAS) thermal infrared (TIR) imaging and salinity measurements to characterize SGD on the remote East Polynesian island of Rapa Nui (Easter Island, Chile). Previous research has shown that coastal freshwater seeps are abundant on Rapa Nui and strongly associated with the locations of ancient settlement sites. We currently lack, however, information on the differential magnitude or quality of these sources of fresh water. Our UAS-based TIR results from four locations on Rapa Nui suggest that locations of variably-sized SGD plumes are associated with many ancient settlement sites on the island and that these water sources are resilient to drought events. These findings support previous work indicating that ancient Rapa Nui communities responded to the inherent and climate-induced hydrological challenges of the island by focusing on these abundant and resilient freshwater sources. Our results highlight the efficacy of using UAS-based TIR for detecting relatively small SGD locations and provide key insights on the potential uses of these water sources for past and current Rapa Nui communities.

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