Lakeshore Environments Research Articles

Site formation processes at Cenjiawan (Nihewan Basin, North China): a case study on the structure of the Early Pleistocene archaeological record in lakeshore environments

ABSTRACTLakeshore environments offer an excellent opportunity to explore how early humans adapted to changing landscapes and environments. The Nihewan fluvio‐lacustrine sequence in North China contains one of the densest concentrations of Early Pleistocene Palaeolithic sites outside of Africa. Among these, the Cenjiawan site, dated at 1.1 Ma, draws attention due to the large number of stone tool refits. We present here Cenjiawan's sedimentary context, artefact spatial patterns, size distribution and taphonomic features, which are complemented by an experimental programme to better understand archaeological debitage size patterns, thus enabling a detailed analysis of formation processes at the site. The Cenjiawan assemblage is also interpreted in the light of its geographical and geological context, where a synsedimentary fault induced a minor topographic relief across the lacustrine lakeshore. This resulted in a shallow‐water setting in the down‐thrown hanging wall of the fault compartment, and a fluvial environment in the uplifted footwall. Our results indicate that Cenjiawan, situated in the hanging wall of the fault, underwent minimal disturbance, constituting a remarkable example of optimal preservation of archaeological assemblages in Early Pleistocene lakeshore environments.

Sedimentary Environments and Coal Accumulation of the Middle Xishanyao Formation, Jurassic, in the Western Dananhu Coalfield, Turpan-Hami Basin

The Dananhu coalfield, at the southern margin of Turpan-Hami Basin, Xinjiang, has good coal-forming geological conditions. Due to the low research level on the depositional environment and coal accumulation, the comprehensive coal mining is restricted. Based on drilling and sectioning outcrop data, the depositional characteristics, lithofacies, paleogeography, and coal accumulation of the coal-bearing formations in western Dananhu coalfield are analyzed. The middle member of the Xishanyao Formation is the major coal-bearing strata of the Dananhu coalfield, composed of conglomerate, sandstone, siltstone, mudstone, and combustible organic rock, which can be further subdivided into 14 lithofacies according to substance composition, sediment texture, and structure. During the early Middle Jurassic coal-accumulating period, alluvial fan, fluvial plain, fluvial delta, and shallow lacustrine deposits were developed from northeast to southwest in the western Dananhu mining area. Coal accumulation was most developed in the center regions of the study area extending from northeast to southwest, which were primarily concentrated in margin fans, floodplains, interdeltaic bays, and lakeshore environments, especially the transitional zone between the fluvial plain and the delta plain in the west of No. 1 mining area. This coal accumulation was mainly controlled by synsedimentary tectonic subsidence and clastic sediments supply or sedimentary environment, where tectonic subsidence was the primary controlling factor and the source supply was the secondary controlling factor for coal accumulation, which provided theoretical support for the coal prediction and geological exploration in western Dananhu coalfield.

Pronounced early human impact on lakeshore environments documented by aquatic invertebrate remains in waterlogged Neolithic settlement deposits

At waterlogged archaeological sites paleolimnological approaches can provide important supporting information about conditions and processes of past human life and human impact on environments around former settlements. In this study, subfossil Cladocera and Chironomidae assemblages were analysed from Neolithic lakeside sediments uncovered at Zürich-Parkhaus Opéra (OP), Switzerland. Our main objectives were to assess how periodic settlement phases altered lakeshore environments and aquatic invertebrate communities during the Neolithic. Aquatic invertebrates occurred in considerable numbers throughout the investigated sediment sections, supporting that Neolithic settlements at site OP were established above the lake surface and sedimentation occurred mostly under water. Two separate aquatic invertebrate communities were distinguished: an impacted community within cultural layers and a pre- and post-impacted community in sediments above, below and in between cultural layers. Aquatic invertebrates indicated that human impact likely resulted in surplus organic material load and nutrient input into the water during the cultural periods. This substantially increased biological oxygen demand of the sediments and overall nutrient concentrations of the near-shore water and thereby led to hypoxic conditions. Chironomids showed generally higher amplitude assemblage changes than cladocerans. This could be explained by the very local influence of humans and higher susceptibility of the less mobile chironomids to local hypoxia in and above the sediment. After settlements were abandoned invertebrate assemblages rapidly recovered to pre-impacted states, suggesting their considerable resilience to local human impact. Our results confirm that cladoceran and chironomid remains can trace localised environmental changes associated with human presence and provide important information for the interpretation of prehistoric human activities.

A late Miocene ostracod record from the northeastern Tibetan Plateau

Lake Qinghai, the largest inland brackish lake in China, is located on the northeastern margin of the Tibetan Plateau and is affected by both the Asian Monsoon and Westerlies climate systems. It is very sensitive to climate and environmental changes. Moreover, its sediments accumulated over the Cenozoic Era and contain abundant information about past tectonics and environmental changes. Here we present a record of late Miocene ostracods from Lake Qinghai sediment cores. A taxonomic analysis of the ostracods yielded 7 families, 14 genera, and 31 species. Six distinct sediment facies were recognized and their corresponding paleolimnological and paleoenvironmental changes were inferred from the ostracod assemblages. The first appearance of ostracod shells at about 7.60 Ma reflects a switch from an eolian sedimentation facies (ca. 8.10–7.60 Ma) to a shallow lacustrine environment (ca. 7.60–5.85 Ma). Ostracod shells were absent from ca. 5.85 to 4.64 Ma in eolian sediments. A transition to a deep lacustrine facies began at ca. 4.64 Ma, and ended at ca. 3.58 Ma. Thus, Lake Qinghai existed in the late Miocene and became larger and deeper in the early Pliocene (ca. 4.64 Ma). During the time interval ca. 3.58–0.70 Ma, littoral lacustrine sedimentation occurred at the core sites. After ca. 0.70 Ma, there were alternating shallow lacustrine and lakeshore environments at the sites, until ca. 0.12 Ma. Changes in ostracod assemblages and their abundance during the intervals ca. 4.64–3.56 Ma and ca. 0.70–0.12 Ma indicate that the sedimentary environment fluctuated over short time scales. Given Lake Qinghai’s sensitivity to environmental and tectonic changes, related to its special location, we concluded that changes in the relative and absolute abundances of ostracods reflect the evolution of the Asian monsoon-arid environment and Plateau growth, as well as global climate changes.

Hunting in yellow waters: an ethnoarchaeological perspective on selective fishing on Lake Turkana

As riverine and lacustrine environments expanded across north tropical Africa during early Holocene times, certain characteristic fishing or “aquatic hunting” strategies became widespread. This paper investigates one such strategy and an associated technology: selective fishing and barbed bone “harpoon” points in the Turkana Basin, northwest Kenya. These tools have a geographically widespread distribution across Africa, primarily north of the equator, and can shed light on hunter-gatherer technology and resource acquisition in the face of environmental and social change. Interviews with contemporary Turkana fishers highlight near-shore fishing practices analogous to those of early Holocene hunter-gatherers. For example, Turkana fishers exploiting deltaic “yellow waters” have traditionally employed selective harpoon-like tools to acquire large aquatic fauna like Lates niloticus (Nile perch) and Synodontis sp. (catfish), while using non-selective traps, hooks and nets to catch smaller and deeper-water species. These practices have changed over several decades in response to local socioeconomic and environmental shifts. Today these selective strategies show a marked seasonality and regional variability that the archaeological record of this region has thus far been ill-equipped to investigate. Through carefully constructed analogy, this preliminary work contributes to a better understanding of human technological and behavioral responses to shifting lakeshore environments today and during early Holocene times.

Desert camouflage and what wildlife see

Desert, desert-scrub, savanna and sandy beach, and lakeshore environments can be particularly tricky in terms of camouflage selection due to their low vegetative density. Therefore many companies focus on the development of paint color schemes that match the vegetation and the desert soils/sands. However another factor in the consideration of which camouflage to purchase may lie in what the animal can see. White-tailed deer and similar large mammals have been shown to have three classes of photo pigments that are sensitive to the range of blue to yellow-green during day light hours and blue to blue-green at night. Six commercially-available camouflage patterns were investigated to determine if the reflectance characteristics measured in the laboratory and under field conditions were elevated in the blue range and perhaps more likely to be seen by wildlife. The camouflage patterns were evaluated against standard vegetation indices including normalized difference vegetation index, soil adjusted vegetation index, enhanced vegetation index, and simple ratio. Only two of the patterns (S4 and S5) possessed a reflectance more like vegetation. Patterns S4, S6, S3, and S2 all showed only slight elevations in the blue wavelength range which could only have been detected by near infrared measurements instead of visual observation by the human eye.

Human impact and ecological changes in lakeshore environments. The contribution of non-pollen palynomorphs in Lake Banyoles (NE Iberia)

The analysis of non-pollen palynomorphs (NPP) provides useful information about local environmental conditions. The study of a core from Lake Banyoles (Girona, NE Iberia) enabled the reconstruction of ecological changes and assessment of human impact in a lakeshore environment during the Mid-Holocene. This work aims to fill the gap in knowledge about the ecological significance of NPP in lowland areas in NE Iberia, and provides descriptions and illustrations of new types documented.Deforestation induced by Early Neolithic communities caused the proliferation of lignicolous fungi in decaying wood and an increase in soil erosion. The input of allochthonous mud led to higher turbidity in the lake water, causing a succession in aquatic organisms, from cyanobacteria to green algae. In that context, a group of erosion-associated fungal spore types were recorded. Indicators of soil disturbance and coprophilous fungi were recorded from 5000 to 4200cal BP, linked with local habitation during the Late Neolithic–Chalcolithic. The NPP analysis reflects the significant human impact that caused changing local environmental conditions, consistent with the signals based on pollen analysis.

The Food Web of Boiling Springs Lake Appears Dominated by the Heterolobosean Tetramitus thermacidophilus Strain BSL.

We studied the protist grazers of Boiling Springs Lake (BSL), an acid geothermal feature in Lassen Volcanic National Park, using a combination of culture and genetic approaches. The major predator in BSL is a vahlkampfiid ameba closely related (95% 18S+ITS rRNA identity) to Tetramitus thermacidophilus, a heterolobose ameboflagellate recently isolated from volcanic geothermal acidic sites in Europe and Russia, as well as an uncultured heterolobosean from the nearby Iron Mountain acid mine drainage site. Tetramitus thermacidophilus strain BSL is capable of surviving the physical extremes of BSL, with optimal growth at 38-50 °C and pH 2-5. This bacterivore also ingested conidiospores of the ascomycete Phialophora sp., but ultrastructural observations reveal the latter may not be readily digested, and conidia were not separable from the ameoboflagellate culture, suggesting a possible symbiosis. DGGE fingerprint transects studies showed the organism is restricted to near-lake environs, and we detected an average of ~500 viable cysts/cm(3) sediment on the shoreline. Other grazing protists were isolated from lakeshore environments, including the lobose amebae Acanthamoeba sp. and Hartmannella sp., and the kinetoplastid flagellate Bodo sp., but none could tolerate both low pH and high temperature. These appear to be restricted to cooler near lake geothermal features, which also contain other potential grazer morphotypes observed but not successfully cultured, including ciliates, euglenids, testate amebae, and possible cercozoans. We compare the food web of BSL with other acidic or geothermal sites, and discuss the impact of protists in this unique environment.

Modeling the climate-induced changes of lake ecosystem structure under the cascade impacts of hurricanes and droughts

Lake Okeechobee, located in south Florida and originated about 6000 years ago during oceanic recession, is the second largest freshwater lake contained entirely within the United States. During recent years, four major hurricanes, Irene (1999), Frances (2004), Jeanne (2004), and Wilma (2005), made landfall near Lake Okeechobee. As a result, the lake's hydrodynamic patterns, water level, and water quality have been extensively influenced by hurricanes in the past decade. The direct landfall of Hurricane Wilma on the Lake Okeechobee area led to a drastic structural change to the ecosystem, resulting in an abrupt population decrease of submerged aquatic vegetation (SAV). During the same time period, south Florida also suffered from intermittent droughts in 2000–2001 and 2006–2008 due to climate variability. Drought stress and hurricane impacts induce complex ecosystem responses, including pervasive changes in species composition and productivity that may persist as changes in habitat, lake trophic state, light penetration depth, water levels, and nutrient cycling. After the 2006–2008 drought, decreased turbidity due to reduced sediment hydrodynamics, along with the increased runoff and nutrient inflows to the aquatic ecosystem, led to a range of ecological responses associated with gradual increases in primary productivity and the recovery of SAV in lake shore environments. The ecosystem then recovered after the population increase of SAV, triggering active ecodynamics among phytoplankton, zooplankton, and fish that had abruptly vanished after successive hurricanes in 2004 and 2005. To address such a unique structural change in the lake ecosystem, this study developed a structurally dynamic model to quantify the ecodynamics of the four main aquatic system organisms (SAV, phytoplankton, zooplankton, and fish) based on a thermodynamics index (exergy) and elucidated the ecosystem recovery pathways under the coupled impact of hurricanes and droughts.

Phosphorus Retention in a 20‐Year‐Old Septic System Filter Bed

Septic systems in lakeshore environments often occur where thin soils overlie bedrock and, consequently, filter beds may be constructed of imported filter sand. The objective of this study was to assess the mobility of wastewater phosphorus (P) in such a potentially vulnerable setting by examining a 20-yr-old domestic septic system located near Parry Sound, ON, Canada, where the filter bed is constructed of imported noncalcareous sand. The groundwater plume is acidic (pH 6.0) and has a zone of elevated PO-P (up to 3.1 ± 1.7 mg L) below the tile lines but no elevated PO-P is present beyond 5 m from the tile lines. Elevated concentrations of desorbable P (up to 137 mg kg) and acid-extractable P (up to 3210 mg kg) occur in the filter sand within 1 m below four of seven tile lines present and the total mass of excess acid-extractable P (39 kg) is similar to the estimated total lifetime P loading to the system (33 kg). Microprobe images reveal abundant Fe and Al-rich authigenic mineral coatings on the sand grains that are increasingly P rich (up to 10% w/w P) near the tile lines. Additionally, 6 yr of monitoring data show that groundwater PO concentrations are not increasing. This indicates that mineral precipitation, not adsorption, dominates P immobilization at this site. This example of robust long-term P retention opens up the possibility of improving P removal in on-site treatment systems by prescribing specific sand types for filter bed construction.

Changing depositional environments in the Colombian Fúquene Basin at submillennial time-scales during 284-27 ka from unmixed grain-size distributions and aquatic pollen

AbstractIn a ~60 m long record reflecting the period from 284 ka to 27 ka we analysed grain size distributions (GSD), organic carbon content, and aquatic pollen assemblages at 1-cm increments. The 4768-points time series show with ~60 yr resolution the dynamic history of Lake Fúquene (2540 m alt., 4° N lat.) of the northern Andes during two full interglacial-glacial cycles. GSD show proportions of clay, fine silt, coarse silt, and sand evidencing the location of the sediment source (proximal vs distal) in relation to the drilling site, and available energy to transport sediments in the catchment area. Loss-on-ignition (LOI) values reflect estimates of the abundance of organic matter (OM) in the sediments. Aquatic pollen were grouped into assemblages characteristic of deep water, shallow water, swamp, and wet lake shore environments, reflecting a hydrological gradient sensitive for lake level changes.The End-Member Modelling Algorithm (EMMA) showed that 4 end-members (EMs) explain an optimal proportion (70%) of the observed variation. EMMA is able to unmix GSD of lacustrine sediments in a genetically meaningful way allowing EMs to be interpreted in past depositional and environmental settings. Most unexplained variability is located in the fraction of coarse sediment. OM content was estimated on the basis of LOI data and formed a fifth EM that mainly indicates presence of peat. Changes concur with submillennial-scale variability established in other proxies from this record (Groot et al., 2011). Periods with distinct sediment compositions are 284-243 ka (mainly MIS 8), 243-201 ka (mainly MIS 7), 201-179 ka (mainly MIS 7/6 transition), 179-133 ka (mainly MIS 6), 133-111 ka, (mainly MIS 5e) 111-87 ka (mainly MIS 5d-5b), 87-79 ka (mainly MIS 5a), 79-62 ka (mainly MIS 4), and 62-27 ka (MIS 3) showing sedimentological regimes are climate driven.

Comparison of Recent Siliceous and Carbonate Mat Development on the Shore of Hyper-Alkaline Lake Van and Mt. Nemrut Soğuk Lake, NE Anatolia, Turkey

This article focuses on the molecular geochemistry of previously unreported carbonate- and siliceous-mat assemblages at two adjacent lake-shore environments. The first study area, on the Lake Van shore, is an intersection of hyper-alkaline lake water and seep water discharge, both of which represent an acid-base geochemical barrier. Comparing alkaline lake water with seep water samples collected from a biomineralization site reveals that seep water has an acidic character and is rich in Ca and Si cations. The second study area, Mt. Nemrut, is the largest volcanic caldera located west of Lake Van in eastern Anatolia, and is the only volcano that has erupted in historical time. While the main lithified-mat components of Lake Van's shore environments are Ca-carbonate and diatoms, Na-carbonate and diatom assemblages represent recent biomineralization in the Mt. Nemrut Soğuk Lake shores. In particular, the normal habitat for the development of these unique microbial mat assemblages can be changed in a short time by the decreasing seep water discharge into the Lake Van shore environment. A detailed study on these lake shore microbialites, before they are lost, would provide a great opportunity to understand the biogeochemical interactions that produce unique sediment fabrics.

Irreversible Phosphorus Sorption in Septic System Plumes?

The mobility of phosphorus (P) in septic system plumes remains a topic of debate because of the considerable reactivity of this constituent. In this study, a septic system plume in Ontario was monitored over a 16-year period with detail that clearly shows the advancing frontal portion of the P plume. This monitoring record provides insight into the extent of secondary P attenuation in the ground water zone beyond that available from previous studies. A P plume 16 m in length developed over the monitoring period with PO(4)-P concentrations (3 to 6 mg/L) that approached the concentrations present under the tile bed. Simulations using an analytical model showed that when first-order solute decay was considered to account for the possibility of secondary P attenuation in the ground water zone, field values could only be matched when decay was absent or occurred at an exceedingly slow rate (half-life greater than 30 years). Thus, hypothesized secondary P attenuation mechanisms such as slow recystallization of sorbed P into insoluble metal phosphate minerals, diffusion into microsites, or kinetically slow direct precipitation of P minerals such as hydroxyapatite were inactive in the ground water zone at this site or occurred at rates that were too slow to be observed in the context of the current 16-year study. Desorption tests on sediment samples from below the tile bed indicated a PO(4) distribution coefficient (K(d)) of 4.8, which implies a P retardation factor of 25, similar to the field apparent value of 37 determined from model calibrations. This example of inactive secondary P attenuation in the ground water zone shows that phosphorus in some ground water plumes can remain mobile and conservative for decades. This has important implications for septic systems located in lakeshore environments when long-term usage scenarios are considered.

New Light on the Earliest Hominid Occupation in East Asia

New Light on the Earliest Hominid Occupation in East Asia

Enhanced attenuation of septic system phosphate in noncalcareous sediments.

Review of phosphate behavior in four mature septic system plumes on similar textured sand has revealed a strong correlation between carbonate mineral content and phosphate concentrations. A plume on calcareous sand (Cambridge site, 27 wt % CaCO3 equiv.) has proximal zone PO4 concentrations (4.8 mg/L P average) that are about 75% of the septic tank effluent value, whereas three plumes on noncalcareous sand (Muskoka, L. Joseph, and Nobel sites, <1 wt % CaCO3 equiv.) have proximal zone phosphate concentrations (<0.1 mg/L P) that are consistently less than 2% of the effluent values. Phosphate attenuation at the noncalcareous sites appears to be an indirect result of the development of acidic conditions (site average pH 3.5 to 5.9) and elevated Al concentrations (up to 24 mg/L), which subsequently causes the precipitation of Al-P minerals such as variscite (AlPO4 x 2H2O). This is supported by scanning electron microscope analyses, which show the widespread occurrence of (Al+P)--rich secondary mineral coatings on sand grains below the infiltration beds. All of these septic systems are more than 10 years old, indicating that these attenuation reactions have substantial longevity. A field lysimeter experiment demonstrated that this reaction sequence can be readily incorporated into engineered waste water treatment systems. We feel this important P removal mechanism has not been adequately recognized, particularly for its potential significance in reducing P loading from septic systems in lakeshore environments.

Hands On or Hands Off? Disgust Sensitivity and Preference for Environmental Education Activities

Detailed descriptions of barriers to environmental education (EE) can provide opportunities for educators to foresee potential problems in programs. High disgust sensitivity is an intrapersonal barrier that constrains preference for learning opportunities involving manipulation of some organic materials. Middle school students in Texas (N = 450) completed a science activity preference scale and a disgust-sensitivity scale. Respondents who expressed the lowest interest in activities that required manipulation of organic substances also had the highest disgust-sensitivity scores. However, no differences were found among students for activities that required observation only. Using a photographic scale, students rated their preference for lake shore environments as places to conduct an aquatic entomology study. Students with high disgust sensitivity were significantly more likely to prefer the poorer locations, which were characterized by clear water and no algae or submerged objects. The addition of a barriers analysis to EE curricula and formation of strategies for working effectively with students with high disgust sensitivity are recommended.

Modelling of atmospheric pollutant transport and deposition in lakeshore environments

In order to study the effects of lakes on weather modification, pollutant transport and deposition, the hydrodynamic equations were solved numerically on a variable horizontal and vertical grid. Time splitting was applied to couple an explicit pseudospectral and an implicit finite difference scheme. The resulted model difference equations were used to predict the local wind, temperature, and pressure fields as well as the evolution of the atmospheric planetary boundary layer parameters. The modeling domain was centered around a lake to investigate the potential impact of nearby industrial sources. The situation studied was characteristic of summertime conditions, driven by a synoptic weather system with air moving from land, over a cooler lake surface. This flow is shown to become highly modified by a mesoscale meteorological phenomenon known as lake-breeze. It is also shown that the presence of a lake limits pollutant deposition over its length, due to stabilization and plume entrainment in the lake-breeze. On the hand, deposition was enhanced over the upwind land due to the lake-breeze effect, and the downwind shore due to intense mxing.