scholarly journals Initial limnological observations at five small lakes in southern Pacific Costa Rica

2018 ◽  
Vol 10 (1) ◽  
Author(s):  
Sally P. Horn ◽  
Erik N. Johanson ◽  
Kurt A. Haberyan ◽  
Mathew S. Boehm ◽  
Jessie L. Johanson ◽  
...  
Keyword(s):  
Costa Rica ◽  
Environmental History ◽  
Global Climate ◽  
Sediment Cores ◽  
Organic Matter Content ◽  
Plant Macrofossils ◽  
Matter Content ◽  
Radiocarbon Dates ◽  
Natural Lakes ◽  
Lake Formation

Costa Rica has hundreds of lakes, many of which have never been described or sampled by limnologists. Here we summarize initial observations of five small (0.2–1.7ha) lakes located at low elevation (365–490m) in the cantón of Buenos Aries. We collected basic limnological data and samples during visits in 2013 and 2014, and compiled environmental and archaeological data for their surroundings as a contribution to the documentation of lake diversity in Costa Rica, and to support parallel investigations of indicators of environmental history preserved in the sediments of the lakes. Lagunas Carse, Los Mangos, Danta, and Ojo de Agua all appear to owe their origin to landslide events, while Laguna Junquillo is an artificial impoundment. Radiocarbon dates on plant macrofossils near the bases of sediment cores from three of the natural lakes provide minimum ages for lake formation; results indicate that Laguna Los Mangos formed over 4 100 years ago, while Laguna Danta formed prior to 1 320 CE and Laguna Carse formed ca. 1 550 CE, near the time of the Spanish Conquest. More than two dozen archaeological sites are located within 1–3Km of the natural lakes, documenting pre-Columbian human occupation and likely use of lake resources. Lake water temperatures and water chemistry were in keeping with observations at lakes throughout Costa Rica. All five lakes are probably polymictic lakes that turn over frequently; none evinced stratification. The surface lake sediments showed similar organic matter content (22,1–28,8%), with values falling near the middle of the range of lakes previously sampled in Costa Rica. Phytoplankton samples included taxa previously reported from small lowland lakes, but differed between lakes and included dominant taxa that were subdominant or uncommon at other lakes surveyed. Our investigation adds to knowledge of lake characteristics and diversity in Costa Rica, and provides benchmarks for assessing future changes in these lakes and their watersheds resulting from human activity, natural disturbances, and regional and global climate change.

scholarly journals Environmental change within the Balkan region during the past ca. 50 ka recorded in the sediments from lakes Prespa and Ohrid

2010 ◽  
Vol 7 (10) ◽  
pp. 3187-3198 ◽  
Author(s):  
B. Wagner ◽  
H. Vogel ◽  
G. Zanchetta ◽  
R. Sulpizio
Keyword(s):  
Organic Matter ◽  
Environmental Change ◽  
Environmental History ◽  
Sediment Cores ◽  
Organic Matter Content ◽  
Matter Content ◽  
Lake Ohrid ◽  
Sediment Record ◽  
Lake Prespa ◽  
Balkan Region

Abstract. Lakes Prespa and Ohrid, in the Balkan region, are considered to be amongst the oldest lakes in Europe. Both lakes are hydraulically connected via karst aquifers. From Lake Ohrid, several sediment cores up to 15 m long have been studied over the last few years. Here, we document the first long sediment record from nearby Lake Prespa to clarify the influence of Lake Prespa on Lake Ohrid and the environmental history of the region. Radiocarbon dating and dated tephra layers provide robust age control and indicate that the 10.5 m long sediment record from Lake Prespa reaches back to 48 ka. Glacial sedimentation is characterized by low organic matter content and absence of carbonates in the sediments, which indicate oligotrophic conditions in both lakes. Holocene sedimentation is characterized by particularly high carbonate content in Lake Ohrid and by particularly high organic matter content in Lake Prespa, which indicates a shift towards more mesotrophic conditions in the latter. Long-term environmental change and short-term events, such as related to the Heinrich events during the Pleistocene or the 8.2 ka cooling event during the Holocene, are well recorded in both lakes, but are only evident in certain proxies. The comparison of the sediment cores from both lakes indicates that environmental change affects particularly the trophic state of Lake Prespa due to its lower volume and water depth.

scholarly journals Sedimentological characteristics of ice-wedge polygon terrain in Adventdalen (Svalbard) – environmental and climatic implications for the late Holocene

Solid Earth ◽  
2014 ◽  
Vol 5 (2) ◽  
pp. 901-914 ◽  
Author(s):  
M. Oliva ◽  
G. Vieira ◽  
P. Pina ◽  
P. Pereira ◽  
M. Neves ◽  
...  
Keyword(s):  
Organic Matter Content ◽  
Soil Formation ◽  
Matter Content ◽  
Valley Bottom ◽  
Radiocarbon Dates ◽  
Climate Conditions ◽  
Fluvial Terraces ◽  
Ice Wedge ◽  
Homogeneous Composition ◽  
Climatic Severity

Abstract. Ice wedges are widespread periglacial features in the landscape of Adventdalen, Svalbard. The networks of ice wedges have created areas with well-developed polygonal terrains in the lowest fluvial terraces in this valley. We have examined the sedimentological characteristics of the northern and southern banks of the Advent river for palaeoenvironmental purposes. The base of two sedimentary sections reported radiocarbon dates of 3.3 and 3.9 ka BP, respectively. The northern site is constituted by three very different lithostratigraphical units, which suggests that their formation should be related to different environmental and climate conditions. By contrast, the southern section shows a rather homogeneous composition, with no significant variations in grain size and organic matter content. In both cases the uppermost sediments are constituted by a thick aeolian deposit. According to our data, warmer climate conditions may have prevailed during the mid Holocene until 3.3 ka BP with widespread peat formation in the valley bottom. Subsequently, a period with alternating soil formation and aeolian sedimentation took place from 3 to 2.5 ka BP, probably due to increasing climatic severity. During the last millennium a long-term cooling trend has favoured aeolian deposition in the lowest part of Adventdalen.

Groundtmthing Multibeam Bathymetric Surveys of Finfish Aquaculture Sites in the Bay d’Espoir Estuarine Fjord, Newfoundland

2000 ◽  
Vol 34 (1) ◽  
pp. 59-67 ◽  
Author(s):  
Michael F. Tlusty ◽  
John E. Hughes Clark ◽  
John Shaw ◽  
Vem A. Pepper ◽  
M. Robin Anderson
Keyword(s):  
Sediment Cores ◽  
Sediment Quality ◽  
Organic Matter Content ◽  
Matter Content ◽  
Sediment Characteristics ◽  
High Resolution Images ◽  
Sonar Images ◽  
Scale Characterization ◽  
Finfish Aquaculture

Current and potential salmonid aquaculture sites in the Bay d’Espoir estuarine fjord on the south coast of Newfoundland were surveyed using multibeam SWATH sonar. In 1997, shallow sites were surveyed using the CSS Puffin EM3000POS/MV system, and deeper sites were surveyed in 1998 using the CCGS Creed hull mounted EM 1000. Sediment cores from representative areas were collected during this period and analyzed for organic matter content, and pore water ammonium and sulfate. We discuss the correlation between the sediment core profiles and the results of the side scan and sun-illuminated bathymetric imagery. Bay d’Espoir is a natural depositional area, and that, coupled with the unique backscatter properties of fish farm wastes, increases the difficulty of interpreting these multibeam sonar images. A fairly accurate broad scale characterization of sediment quality can be made from high-resolution images. However’, much of the fine scale detail and inherent variation of sediment characteristics associated with impacts from aquaculture cannot be determined from multibeam imagery.

scholarly journals Earthworm population ecology; Guyana, S A

2019 ◽  
Author(s):  
Reshma Persaud
Keyword(s):  
Global Climate ◽  
Organic Matter Content ◽  
Terrestrial Ecosystem ◽  
Distinct Species ◽  
Matter Content ◽  
Steady Increase ◽  
Statistical Significant Difference ◽  
Soil Ecosystems ◽  
Significant Difference ◽  
Earthworm Population

Earthworms are regarded as the bio-indicators of soil quality and are perhaps the most significant regulators of soil structure and organic matter content in a variety of terrestrial soil ecosystems, paving the way for sustainable green agriculture and land rehabilitation. Due to the steady increase in industrialization and shifts in global climate, their population is now more susceptible to change/decline as a result of the strains placed on soil ecosystems by agriculture, mining and deforestation. This research aimed to and successfully established the composition of earthworm populations present in Guyana while exploring their relationship with the biogeographical regions and pedobiological components of their respective ecosystem. Earthworms and soil samples were collected from 15 sites per natural region after which they were taxonomically identified following methodological dissections which yielded 68 distinct species. Of the four natural regions, the earthworm population of Highland Region was found to be the most diverse, rich, even and dense. Earthworm abundance, epigeic abundance, endogeic abundance, anecic abundance and species richness among the four natural regions of Guyana, were all of statistical significant difference, likewise, earthworm abundance in the various climate and soil types along with disturbance were of statistical significant difference. It was found that epigeic earthworms were significantly affected by phosphorus (0.01), moisture (0.01) and calcium (0.02) while anecic earthworms were significantly affected by magnesium (0.04), and the degree at which these affect the various ecotype is different among natural regions. This study has proven with conviction that earthworm population structure varies depending on the biogeographical and pedobiological factors present within any respective terrestrial ecosystem.

Trace metals in fine grained sediments of the Kaštela Bay, adriatic sea

1998 ◽  
Vol 38 (11) ◽  
pp. 169-175 ◽  
Author(s):  
D. Bogner ◽  
M. Juracic ◽  
N. Odžak ◽  
A. Baric
Keyword(s):  
Trace Metals ◽  
Adriatic Sea ◽  
Sediment Cores ◽  
Organic Matter Content ◽  
Matter Content ◽  
Homogeneous Distribution ◽  
Sediment Samples ◽  
Fine Grained ◽  
The Past ◽  
Cu And Zn

The aim of the present work was to study the past and present contamination of the Kaštela bay using chemical analysis of selected trace metals (Cd, Pb, Zn, Cu, Cr, Mn and Ni) in fine grained sediment cores. Sediment samples were taken at three locations with silty sediments. The highest concentrations of Cd, Pb, Cu and Zn and the lowest concentration of Ni were found in the east, the most contaminated part of the Bay. The decrease of Cd, Pb, Cu and Zn concentrations with increased depth, indicates their anthropogenic origin. Homogeneous distribution of Cr, Mn and Ni in the sediment cores indicates their terrigenous origin. The correlation of Zn, Cu and Ni concentration with the organic matter content was determined.

Interpreting basal sediments and plant fossils in kettle lakes: insights from Silver Lake, Michigan, USA

2020 ◽  
Vol 57 (2) ◽  
pp. 292-305
Author(s):  
Catherine H. Yansa ◽  
Albert E. Fulton ◽  
Randall J. Schaetzl ◽  
Jennifer M. Kettle ◽  
Alan F. Arbogast
Keyword(s):  
Lake Michigan ◽  
Sediment Cores ◽  
Mixed Forest ◽  
Plant Macrofossils ◽  
Plant Colonization ◽  
Plant Fossils ◽  
The Core ◽  
Chord Distance ◽  
Lake Formation ◽  
Silver Lake

We report on pollen, plant macrofossils, and associated lithostratigraphy of a sediment core extracted from the base of Silver Lake, a kettle lake in northern Lower Michigan, USA, which reveal a complex deglacial scenario for ice block melting and lake formation, and subsequent plant colonization. Complementary multivariate statistical and squared chord distance analyses of the pollen data support these interpretations. The basal radiocarbon age from the core (17 540 cal years BP) is rejected as being anomalously old, based on biostratigraphic anomalies in the core and the date’s incongruity with respect to the accepted regional deglaciation chronology. We reason that this erroneous age estimate resulted from the redeposition of middle-Wisconsin-age fossils by the ice sheet, mixed with the remains of plants that existed as the kettle lake formed at ca. 10 940 cal years BP by ice block ablation. Thereafter, the kettle lake became a reliable repository of Holocene-age fossils, documenting a mature boreal forest that existed until 10 640 cal years BP, followed by a pine-dominated mixed forest, an early variant of the mixed conifer–hardwood forest that persists to the present day. Our study demonstrates that researchers investigating kettle lakes, a common depositional archive for plant fossils in deglaciated landscapes, should exercise caution in interpreting the basal (Late Pleistocene/early Holocene-age) part of lake sediment cores.

scholarly journals Methane and sulfate dynamics in sediments from mangrove-dominated tropical coastal lagoons, Yucatán, Mexico

2016 ◽  
Vol 13 (10) ◽  
pp. 2981-3001 ◽  
Author(s):  
Pei-Chuan Chuang ◽  
Megan B. Young ◽  
Andrew W. Dale ◽  
Laurence G. Miller ◽  
Jorge A. Herrera-Silveira ◽  
...  
Keyword(s):  
Sulfate Reduction ◽  
Coastal Lagoons ◽  
Large Fraction ◽  
Sediment Cores ◽  
Organic Matter Content ◽  
Matter Content ◽  
Reduction Zone ◽  
Overlying Water ◽  
Transport Reaction ◽  
Dissolved Methane

Abstract. Porewater profiles in sediment cores from mangrove-dominated coastal lagoons (Celestún and Chelem) on the Yucatán Peninsula, Mexico, reveal the widespread coexistence of dissolved methane and sulfate. This observation is interesting since dissolved methane in porewaters is typically oxidized anaerobically by sulfate. To explain the observations we used a numerical transport-reaction model that was constrained by the field observations. The model suggests that methane in the upper sediments is produced in the sulfate reduction zone at rates ranging between 0.012 and 31 mmol m−2 d−1, concurrent with sulfate reduction rates between 1.1 and 24 mmol SO42− m−2 d−1. These processes are supported by high organic matter content in the sediment and the use of non-competitive substrates by methanogenic microorganisms. Indeed sediment slurry incubation experiments show that non-competitive substrates such as trimethylamine (TMA) and methanol can be utilized for microbial methanogenesis at the study sites. The model also indicates that a significant fraction of methane is transported to the sulfate reduction zone from deeper zones within the sedimentary column by rising bubbles and gas dissolution. The shallow depths of methane production and the fast rising methane gas bubbles reduce the likelihood for oxidation, thereby allowing a large fraction of the methane formed in the sediments to escape to the overlying water column.

scholarly journals Sedimentological characteristics of ice-wedge polygon terrain in Adventdalen (Svalbard). Environmental and climatic implications for the Late Holocene

2014 ◽  
Vol 6 (1) ◽  
pp. 1191-1225
Author(s):  
M. Oliva ◽  
G. Vieira ◽  
P. Pina ◽  
P. Pereira ◽  
M. Neves ◽  
...  
Keyword(s):  
Organic Matter Content ◽  
Soil Formation ◽  
Matter Content ◽  
Valley Bottom ◽  
Radiocarbon Dates ◽  
Climate Conditions ◽  
Fluvial Terraces ◽  
Ice Wedge ◽  
Homogeneous Composition ◽  
Climatic Severity

Abstract. Ice-wedges are widespread periglacial features in the landscape of Adventalen, Svalbard. The networks of ice-wedges have created areas with well-developed polygonal terrains in the lowest fluvial terraces in this valley. We have examined the sedimentological characteristics of the northern and southern banks of the Advent river for palaeoenvironmental purposes. The base of two sedimentary sections reported radiocarbon dates of 3.3 and 3.9 ka cal BP, respectively. The northern site is constituted by three very different lithostratigraphical units, which suggests that their formation should be related to different environmental and climate conditions. By contrast, the southern section shows a rather homogeneous composition, with no significant variations in grain size and organic matter content. In both cases the uppermost sediments are constituted by a thick aeolian deposit. According to our data, warmer climate conditions may have prevailed during the Mid Holocene until 3.3 ka cal BP with widespread peat formation in the valley bottom. Subsequently, a period with alternating soil formation and aeolian sedimentation took place from 3 to 2.5 ka cal BP, probably due to increasing climatic severity. During the last millennium a long-term cooling trend has favoured aeolian deposition in the lowest Adventalen valley.

Geochemistry of Mercury in Two Hydroelectric Reservoirs in Quebec, Canada

1993 ◽  
Vol 50 (2) ◽  
pp. 269-281 ◽  
Author(s):  
Patrick Louchouarn ◽  
Marc Lucotte ◽  
Alfonso Mucci ◽  
Pierre Pichet
Keyword(s):  
Close Association ◽  
Organic Matter Content ◽  
Matter Content ◽  
Depth Interval ◽  
Flooded Soils ◽  
Hydroelectric Reservoirs ◽  
Erosion Processes ◽  
Natural Lakes ◽  
Mechanical Erosion ◽  
Atmospheric Inputs

Carbon, nitrogen, phosphorus, and iron oxyhydroxide profiles were used to explain the retention of Hg in sediments of natural lakes and flooded soils in Quebec. In lake sediments, Hg levels increased from background concentrations of approximately 100 ng/g beneath the 10- to 16-cm depth interval to 150–490 ng/g near the surface. This increase was attributed to atmospheric inputs to the environment. In forest soils, the close association of Hg with the surficial organic horizon appears to be a potential source of contamination for the aquatic system through the transport of particulate matter by surface runoff. High organic matter content observed in the flooded soil of LG-2 Reservoir suggests that postsedimentation biodegradation is a slow process. In contrast, at Cabonga Reservoir, an 80% reduction in C, N, and Hg concentrations was observed between the flooded and the adjacent forest soil. Mechanical erosion processes (marling, waves, ice) rather than biodegradation seem responsible for the observed loss in C, N, and Hg. We propose that suspension of the humic horizon from flooded soils could constitute a significant source of Hg contamination to the overlying waters and biota until the exposed littoral zone stabilizes.

scholarly journals Lead in the environment of Lake Wigry (NE Poland)

2011 ◽  
Vol 11 (2) ◽  
pp. 59-68 ◽  
Author(s):  
Urszula Aleksander-Kwaterczak ◽  
Anna Kostka
Keyword(s):  
Surface Layer ◽  
Sediment Cores ◽  
Organic Matter Content ◽  
Matter Content ◽  
Sediment Type ◽  
Sediment Samples ◽  
Ne Poland ◽  
Positive Linear Correlation ◽  
Component Content ◽  
Spatial And Vertical Distribution

Lead in the environment of Lake Wigry (NE Poland)Analysis was performed for lead content in the sediments of Lake Wigry (NE Poland), taking into account lithology, basic chemical component content and physical characteristics of sediment, Several hundred sediment samples from different parts of the lake and peatland around the lake, were collected. Their locations were determined by GPS and the depth of sediment by echosounder. The surface layer (0-10 cm) of sediment and sediment cores were taken to determine the spatial and vertical distribution of Pb. Concentrations of lead in the surface sediment range from 2.52 to 469 mg kg-1. One of the most important factors influencing spatial distribution of Pb is sediment type. The highest content of Pb was found in samples of organic gyttja and the lowest in clastic sediment samples. Strong positive linear correlation (r = 0.7) between organic matter content and Pb concentration in sediment was observed. It may be the result of simple bio-accumulation of lead. A large influence of sediment location on Pb distribution was found. The largest concentration of this element was found in sediment of the Wigry Basin. The major part of Pb accumulates in the surface layer of sediment.

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